WO2011125231A1

WO2011125231A1 - Vehicle brake device

Info

Publication number: WO2011125231A1
Application number: PCT/JP2010/056633
Authority: WO
Inventors: 泰昭鶴見
Original assignee: トヨタ自動車株式会社
Priority date: 2010-04-07
Filing date: 2010-04-07
Publication date: 2011-10-13

Abstract

A vehicle brake device (S) is provided with a disc rotor (11) which is a rotation body, and a brake caliper (12) which is a frictional engagement means. Furthermore, the device (S) is provided with a piece of latent heat storage material (21) housed in a housing space (11b) which is formed in a frictional slide section (11a) of the disc rotor (11). The latent heat storage material (21) undergoes a phase change from a solid phase to a liquid phase due to the frictional heat (thermal energy) generated in the frictional slide section (11a), thereby storing the frictional heat as latent heat. At this time, the volume change accompanying the phase change in the latent heat storage material (21) is absorbed by a volume change absorbing mechanism (22). Moreover, the device (S) is provided with a thermoelectric conversion section (31) which is disposed between a hub section (11c) of the disc rotor (11) and the frictional slide section (11a), namely, the latent heat storage material (21), of the disc rotor (11). Furthermore, a heated surface (31a) is heated by the frictional heat stored in the latent heat storage material (21), and a cooled surface (31b) is maintained at the temperature of the hub section (11c), with the result that the thermoelectric conversion section (31) converts the frictional heat to regenerated electrical power (electrical energy).

Description

Braking device for vehicle

The present invention relates to a braking device for a vehicle such as an automobile, and more particularly to a braking device for a vehicle that collects thermal energy generated by the braking in addition to braking the wheels of the vehicle.

Conventionally, for example, as disclosed in Japanese Patent Laid-Open No. 5-26270, a friction member is coupled to one of two relatively rotatable shafts, and a friction mating member having a hollow structure is coupled to the other. A wet friction apparatus in which a metal at 150 to 270 ° C. is sealed in a hollow portion is known. In this wet friction device, when the wet friction material provided on the friction member is pressed against the friction counterpart member, the temperature rise of the friction counterpart member is suppressed by the latent heat of fusion of the metal enclosed in the hollow portion of the friction counterpart member. It has become.
Conventionally, for example, as disclosed in JP-A-5-167104, a thermoelectric element having a high-temperature side joint and a low-temperature side joint, and means for heating the high-temperature side joint of the thermoelectric element; Thermoelectric power generation using the Seebeck effect due to the temperature difference between the high temperature side junction and the low temperature side junction of the thermoelectric element A thermoelectric generator is also known. In this thermoelectric generator, the thermoelectric element has a thermoelectromotive force characteristic that exhibits a peak change with respect to temperature, and the phase change heat storage material interposed between the heating means and the high-temperature side junction of the thermoelectric element is a thermoelectric element. A phase change is selected at a temperature that limits the upper limit of a given temperature range centered on the peak of the thermoelectromotive force characteristic of the element.

By the way, when the recovered thermal energy is converted into, for example, electric energy using a thermoelectric element, that is, a thermoelectric conversion means, generally, a temperature difference between a heating surface and a cooling surface in the thermoelectric conversion means is large. It is said that the thermoelectric conversion efficiency is improved. For this reason, when converting the thermal energy collected by mounting the thermoelectric conversion means on the vehicle to electric energy, a device that generates heat and increases in temperature as the vehicle travels is used as a heat source, and the heating surface of the thermoelectric conversion means Is preferably heated.
As a device that can serve as such a heat source, a vehicle braking device that generates a braking force by friction is extremely effective in that a high temperature can be obtained by the generation of frictional heat. However, in order to always generate an appropriate braking force, there is a limit to the temperature at which the vehicle braking device is operated. That is, the vehicle braking device has a characteristic that the coefficient of friction decreases when the temperature of the friction sliding portion increases. For this reason, when the vehicle braking device is operated at a high temperature, there is a possibility that a phenomenon in which the braking force is reduced, that is, a so-called fade phenomenon occurs.
In this way, from the viewpoint of properly operating the vehicle braking device, it is preferable to release the generated frictional heat, in other words, to cool appropriately and maintain the temperature of the vehicle braking device itself at a low temperature. . On the other hand, when recovering thermal energy using thermoelectric conversion means and converting it to electrical energy, from the viewpoint of the thermoelectric conversion efficiency of the thermoelectric conversion means, the frictional heat generated by the operation of the braking device for the vehicle is released. Without maintaining, the vehicle braking device itself is preferably maintained at a high temperature.
Therefore, when the frictional heat generated by the operation of the vehicle braking device, that is, thermal energy is recovered using the thermoelectric conversion means and converted into, for example, electric energy, the braking force of the vehicle braking device is reduced. It is extremely important to satisfy both contradictory requirements of improving the thermoelectric conversion efficiency by the thermoelectric conversion means.
In this regard, for example, as shown in each of the above publications, using a heat storage material that can recover thermal energy as latent heat in accordance with phase change, that is, latent heat storage means is effective in that it can satisfy the contradicting requirements. It can be said that.
However, in the vehicle braking device, it is necessary to efficiently change the phase of the latent heat storage means and recover the heat energy. Also, the recovered heat energy is used to efficiently heat the heating surface of the thermoelectric conversion means and There is room for consideration in that it is necessary to create an appropriate temperature difference between the heating surface and the cooling surface of the conversion means. In particular, when a latent heat storage means is provided on a rotating body that rotates integrally with a wheel, the balance of mass may be lost with a phase change, and as a result, for example, it may affect the running behavior of the vehicle. Is concerned.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle braking device that appropriately brakes the vehicle and efficiently recovers the thermal energy of the vehicle.
In order to achieve the above object, a feature of the present invention is to provide a braking device for a vehicle that applies a braking force to the rotation of a wheel of the vehicle and collects thermal energy generated by the application of the braking force. A rotating body that rotates integrally with a wheel of the vehicle and a friction engagement means that frictionally engages with a friction sliding portion of the rotating body to apply a braking force by friction to the rotation of the wheel And a braking force applying means that is housed in a friction sliding portion of the rotating body, and is generated from the solid phase to the liquid phase or from the liquid phase to the solid phase by the thermal energy generated by the friction engagement by the friction engagement means. A heat recovery means having a latent heat storage means for storing the thermal energy as latent heat by changing phase, and a latent heat storage means of the heat recovery means and a fixed portion of the rotating body with respect to the vehicle, Stored in the latent heat storage means In further comprising a power recovery means for recovering and converting the thermal energy into electrical energy. In this case, the braking force applying means may be, for example, a disk brake unit in which the rotating body is a disk rotor and the friction engagement means is a brake caliper, or the rotating body is a brake drum, and the friction engagement means is The drum brake unit may be a brake shoe.
In this case, the heat recovery means may further include a volume change absorbing means for absorbing a volume change accompanying a phase change of the latent heat storage means inside the friction sliding portion of the rotating body. In this case, the volume change absorbing means may be provided at equal intervals in the circumferential direction of the rotating body, for example. Also, in these cases, the volume change absorbing means is elastically deformed with respect to the volume change accompanying the phase change of the latent heat storage means inside the friction sliding portion of the rotating body, for example, and the volume change Should be absorbed.
In these cases, the heat recovery means may further include a fin that transfers heat energy generated in accordance with the friction engagement by the friction engagement means to the latent heat storage means. In this case, the fins may be arranged alternately with the latent heat storage means in the circumferential direction of the rotating body, for example. Further, in these cases, the fins may be thermally connected to the inner wall surface forming the friction sliding portion inside the friction sliding portion of the rotating body.
In these cases, for example, the power recovery means is configured such that one side is heated by the latent heat storage means of the heat recovery means and the other side is maintained at a lower temperature than the one side, The thermoelectric conversion means may convert the thermal energy into the electric energy according to a temperature difference from the other side. In this case, the thermoelectric conversion means may be provided at a predetermined interval in the circumferential direction of the rotating body. In this case, the thermoelectric conversion means is fixed to the rotating body by, for example, floating coupling. Good. In these cases, the power recovery means may further include power storage means for storing the electric energy converted by the thermoelectric conversion means as electric power.
Another feature of the present invention is that, in the case described above, the heat recovery means is further accommodated inside the fixed portion of the rotating body and on the high temperature side accommodated inside the friction sliding portion. There is also provided a low-temperature latent heat storage means that changes phase from a solid phase to a liquid phase or from a liquid phase to a solid phase at a temperature lower than that of the latent heat storage means.
In this case, the heat recovery means may further include a volume change absorbing means for absorbing a volume change accompanying a phase change of the low temperature side latent heat storage means inside the fixed portion of the rotating body. In this case, the volume change absorbing means may be provided at equal intervals in the circumferential direction of the rotating body. In these cases, the volume change absorbing means is elastically deformed with respect to the volume change accompanying the phase change of the low-temperature side latent heat storage means inside the fixed portion of the rotating body, for example, and the volume It is better to absorb changes.
According to these, the latent heat storage means of the heat recovery means is provided in the friction sliding portion of the rotating body (for example, the disk rotor or the brake drum), and the friction sliding portion (specifically, the friction sliding portion of the rotating body). An electric power recovery means (specifically, a thermoelectric conversion means) can be provided between the latent heat storage means housed inside the rotary body and a fixed part (for example, a hub part) of the rotating body. Thereby, the heat energy (for example, frictional heat) generated by braking can be efficiently transferred to the latent heat storage means, and the latent heat storage means can be efficiently used by the centrifugal force accompanying the rotation of the rotating body. The phase can be changed. Therefore, the heat energy generated in the friction sliding portion of the rotating body can be efficiently recovered as latent heat, and as a result, the temperature rise of the friction sliding portion of the rotating body can be effectively suppressed.
In addition, since the power recovery means (specifically, the thermoelectric conversion means) can be disposed adjacent to the heat recovery means (specifically, the latent heat storage means), the thermal energy stored in the latent heat storage means One side (specifically, the heating surface) of the thermoelectric conversion means can be heated to appropriately maintain the temperature difference from the other side (specifically, the cooling surface). Thereby, the thermoelectric conversion means can convert and collect | recover the collect | recovered thermal energy to an electrical energy by favorable thermoelectric conversion efficiency.
Further, since the volume change absorbing means can be provided in the heat recovery means, the volume change accompanying the phase change of the latent heat storage means inside the friction sliding portion can be reliably absorbed. As a result, it is possible to prevent the occurrence of voids in the frictional sliding part, which is likely to occur when the latent heat storage means changes phase from the liquid phase to the solid phase, and the mass balance of the rotating body is lost. Can be prevented. Therefore, for example, it is possible to prevent an adverse effect on the running behavior and riding comfort of the vehicle due to the loss of the balance of the mass of the rotating body.
Further, the heat recovery means can be provided with fins alternately with the latent heat storage means in the circumferential direction of the rotating body. As a result, the heat energy generated in the frictional sliding portion can be efficiently transferred to the latent heat storage means, and in a state where the solid phase and the liquid phase coexist, it is effectively accompanied with the rotation of the rotating body. Can be stirred. Therefore, the temperature of the latent heat storage means can be made uniform, and for example, one side (heating surface) of the thermoelectric conversion means can be appropriately heated.
In this case, heat energy can be more efficiently transferred by thermally connecting the fin to the inner wall surface forming the friction sliding portion inside the friction sliding portion. Therefore, for example, one side (heating surface) of the thermoelectric conversion means can be heated more stably, and more efficiently converted into electric energy and recovered.
Further, the thermoelectric conversion means can be fixed to the rotating body by floating coupling. Thereby, for example, displacement due to heating and cooling or rotation of the rotating body can be absorbed, so that stress can be prevented from acting on the thermoelectric conversion means.
Furthermore, the heat recovery means can be provided with a low-temperature side latent heat storage material means housed inside the fixed portion of the rotating body. Thereby, the high temperature side latent heat storage means can be accommodated in the friction sliding portion of the rotating body, and the low temperature side latent heat storage means can be accommodated in the fixed portion. Therefore, for example, one side (heating surface) of the thermoelectric conversion means can be heated by the high-temperature side latent heat storage means, and the other side (cooling surface) can be maintained at a relatively low temperature by the low-temperature side latent heat storage means. The temperature difference between one side (heating surface) and the other side (cooling surface) of the thermoelectric conversion means can be continuously maintained at the temperature difference at which the thermoelectric conversion efficiency is good. Thereby, heat energy can be more efficiently converted into electric energy and recovered, and for example, the recovered electric energy can be used in other devices mounted on the vehicle.

FIG. 1 is a schematic cross-sectional view showing a configuration of a vehicle braking device according to a first embodiment of the present invention.
FIG. 2 is a schematic partial cross-sectional view for explaining the arrangement of the heat recovery unit and the thermoelectric conversion unit in FIG. 1.
FIG. 3 is a cross-sectional view showing the configuration of the volume change absorption mechanism of FIG.
FIG. 4 is a cross-sectional view for explaining the operation of the volume change absorption mechanism.
FIG. 5 is a graph for explaining the thermoelectric conversion efficiency of the thermoelectric converter.
FIG. 6 is a graph for explaining the change of the disk rotor temperature with respect to the amount of heat generated by braking according to the first embodiment of the present invention.
FIG. 7 is a schematic partial cross-sectional view for explaining the fins of the heat recovery unit according to the first modification of the first embodiment of the present invention.
FIG. 8 is a schematic partial cross-sectional view for explaining a thermoelectric conversion unit according to a second modification of the first embodiment of the present invention.
FIG. 9 is a cross-sectional view for explaining the floating fastening mechanism of FIG.
FIG. 10 is a cross-sectional view for explaining the assembled state of the thermoelectric conversion unit of FIG.
FIG. 11 is a schematic partial cross-sectional view for explaining a modified example of the thermoelectric conversion unit in FIG. 8.
12 is a cross-sectional view for explaining a modified example of the floating fastening mechanism of FIG.
FIG. 13 is a schematic cross-sectional view for explaining the configuration of a vehicle braking device according to a third modification of the first embodiment of the present invention.
FIG. 14 is a schematic partial cross-sectional view for explaining the arrangement of the heat recovery unit and the thermoelectric conversion unit in FIG. 13.
FIG. 15 is a graph for explaining a change in the disk rotor temperature with respect to the heat generation amount due to braking according to the third modification of the first embodiment of the present invention.
FIG. 16 is a schematic cross-sectional view for explaining the configuration of the vehicle braking device according to the second embodiment of the present invention.
FIG. 17 is a schematic partial cross-sectional view for explaining the arrangement of the heat recovery unit and the thermoelectric conversion unit in FIG. 16.
18 is a cross-sectional view showing the configuration of the volume change absorption mechanism of FIG.
FIG. 19 is a cross-sectional view for explaining a modification of the volume change absorption mechanism of FIG.
20 is a cross-sectional view for explaining a modified example of the volume change absorbing mechanism of FIG.
FIG. 21 is a schematic partial cross-sectional view for explaining a modification of the heat recovery unit in FIG. 16.

a. First embodiment
Hereinafter, a vehicle braking device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a system configuration of a vehicle braking device S according to the first embodiment. In addition to braking the vehicle, the vehicle braking device S collects kinetic energy generated as a result of braking as thermal energy, and further converts the collected thermal energy into electrical energy for storage. is there.
For this reason, as shown in FIG. 1, the vehicle braking device S includes a braking unit 10 as a braking force applying unit that applies a braking force to the wheels W, and heat generated by braking by the braking unit 10. A heat recovery unit 20 as a heat recovery unit that absorbs and recovers energy, and a power recovery unit 30 as a power recovery unit that converts the thermal energy recovered by the heat recovery unit 20 into electrical energy and stores the energy. Yes. In the following description, the case where the vehicle braking device S is provided on the left and right front wheels of the vehicle (represented by the right front wheel of the vehicle in FIG. 1) will be described. It is also possible to implement by providing the braking device S or providing the vehicle braking device S only on the rear wheel side of the vehicle.
The braking unit 10 in the first embodiment is a disc brake unit that includes a disc rotor 11 that is a rotating body and a brake caliper 12 that is a friction engagement means. The disk rotor 11 is assembled with a nut on one side of a hub H that is rotatably supported by a knuckle N constituting a suspension device (not shown) via a hub bearing (not shown). It will rotate. In addition, the disc rotor 11 includes a friction sliding portion 11a that frictionally slides with a brake pad that is assembled to a brake caliper 12, which will be described later, at the outer periphery thereof. As shown in FIG. 1, the friction sliding portion 11 a is formed with an accommodation space 11 b that is filled with and accommodated with a latent heat storage material 21 as latent heat storage means that constitutes a heat recovery portion 20 described later. Yes. Further, as shown in FIG. 1, the disk rotor 11 includes a hub portion 11 c as a fixing portion that is fixed in contact with the hub H.
The brake caliper 12 accommodates a pair of brake pads, and generates a frictional force by pressing against the friction sliding portion 11a of the disk rotor 11 that rotates the brake pad. The detailed structure and operation of the disc brake unit are the same as those of the well-known disc brake unit, and are not directly related to the present invention, so the description thereof is omitted.
In the braking unit 10 configured as described above, when the brake pedal (not shown) is operated by the driver, the brake hydraulic pressure is supplied to the brake caliper 12. As a result, the brake caliper 12 presses the brake pad against the friction sliding portion 11 a of the disc rotor 11 as the supplied brake fluid pressure increases. A frictional force is generated by friction-engaging the brake pad against the frictional sliding portion 11a of the disk rotor 11 that rotates integrally with the wheel W, and this frictional force brakes the rotation of the wheel W. Is applied as a braking force. Therefore, the braking unit 10 brakes the rotating wheel W by converting the kinetic energy into heat energy (friction heat) by friction accompanying braking of the vehicle.
Thus, the heat energy (friction heat) generated by braking is recovered by the heat recovery unit 20 provided in the friction sliding portion 11a of the disk rotor 11. As shown in FIG. 2, the heat recovery unit 20 includes a latent heat storage material 21 accommodated in an accommodation space 11b formed in the friction sliding portion 11a. The latent heat storage material 21 has a physical property that absorbs or dissipates heat without causing its own temperature change in accordance with a change in the state of the substance, that is, a phase change from the solid phase to the liquid phase or a phase change from the liquid phase to the solid phase. It is what you have. As the latent heat storage material 21, for example, an organic solid such as pentaerythritol having a melting point of about 200 ° C. or a molten eutectic salt such as LiOH—NaOH can be employed.
In the latent heat storage material 21 having such physical properties, when the temperature in the accommodation space 11b rises, the thermal energy is absorbed and the phase changes from the solid phase to the liquid phase, and the temperature in the accommodation space 11b falls. The heat energy absorbed in the is released to change from a liquid phase to a solid phase. Here, when the latent heat storage material 21 undergoes a phase change and the solid phase and the liquid phase coexist, the thermal energy is absorbed (endothermic) or released (radiated) without accompanying its own temperature change. To do.
By the way, when the latent heat storage material 21 undergoes a phase change from the solid phase to the liquid phase or from the liquid phase to the solid phase, for example, a volume change of about 1 to 10% occurs. Specifically, the volume increases when the latent heat storage material 21 changes phase from a solid phase to a liquid phase, and the volume decreases when the latent heat storage material 21 changes phase from a liquid phase to a solid phase. Since the volume of the latent heat storage material 21 accommodated in the accommodation space 11b is changed in this way, especially when the latent heat storage material 21 is changed to a solid phase, a gap is generated in the accommodation space 11b and rotated. There is a possibility that the balance of mass in the disk rotor 11 as a body is lost.
Therefore, the heat recovery unit 20 absorbs the volume change of the latent heat storage material 21 accommodated in the accommodation space 11b and suppresses the generation of voids in the accommodation space 11b, as shown in FIG. A volume change absorbing mechanism 22 is provided as a plurality of volume change absorbing means provided at equal intervals (symmetrically left and right) in the circumferential direction of the friction sliding portion 11a of the disk rotor 11. As shown in detail in FIG. 3, the volume change absorption mechanism 22 is assembled to a sleeve 22a, a metal bellows 22b housed in one end of the sleeve 22a, and the other end of the metal bellows 22b. And a disk-shaped bottom plate 22c. Here, as will be described later, the sleeve 22a is formed with a plurality of notches 22a1 in the circumferential direction that allow the latent heat storage material 21 to flow.
As shown in FIG. 4, the volume change absorbing mechanism 22 configured in this manner is press-fitted toward the accommodation space 11 b so as to be flush with the friction sliding portion 11 a on the side surface of the disk rotor 11. . Thereby, even if the disk rotor 11 rotates and a centrifugal force acts on the volume change absorption mechanism 22, it is possible to prevent the volume change absorption mechanism 22 from falling off.
In the volume change absorption mechanism 22 press-fitted into the accommodation space 11b, when the latent heat storage material 21 is in a solid phase, that is, when the volume of the latent heat storage material 21 in the accommodation space 11b is the smallest, the metal bellows 22b is the bottom plate 22c. The latent heat storage material 21 is pushed down elastically through the.
When the temperature in the accommodation space 11b rises above the melting point of the latent heat storage material 21 from this state and the latent heat storage material 21 undergoes a phase change from the solid phase to the liquid phase, the volume of the latent heat storage material 21 expands. At this time, in the volume change absorption mechanism 22, the volume-expanded liquid phase latent heat storage material 21 flows into the sleeve 22a from the notch 22a1 formed in the sleeve 22a, and the bottom plate 22c is pressed. As a result, the metal bellows 22b assembled to the bottom plate 22c contracts in the axial direction of the sleeve 22a against the elastic force, so that the volume change absorption mechanism 22 absorbs the volume change (expansion change) of the latent heat storage material 21. can do.
On the other hand, when the temperature in the accommodation space 11b falls and the latent heat storage material 21 changes from a liquid phase to a solid phase, the volume of the latent heat storage material 21 contracts. At this time, in the volume change absorption mechanism 22, the latent heat storage material 21 in the liquid phase that has flowed into the sleeve 22a from the notch 22a1 formed in the sleeve 22a is contained in the accommodation space 11b. Spills towards For this reason, the pressing of the bottom plate 22c by the latent heat storage material 21 is released, and the metal bellows 22b pushes the liquid phase latent heat storage material 21 together with the bottom plate 22c in the axial direction of the sleeve 22a by its elastic force. Thereby, the volume change absorption mechanism 22 absorbs the volume change (shrinkage change) of the latent heat storage material 21, and maintains the state in which the latent heat storage material 21 that contracts in the accommodation space 11b is filled without generating a void. Can do. Therefore, even when the temperature in the accommodation space 11b further falls to below the melting point of the latent heat storage material 21, and the volume further shrinks and the latent heat storage material 21 exists as a solid phase, there are voids in the accommodation space 11b. Occurrence can be suppressed.
Further, as shown in FIG. 2, the heat recovery unit 20 includes fins 23 formed inside the accommodation space 11 b. The fins 23 are arranged so as to alternate with the volume change absorbing mechanism 22 in the circumferential direction of the disk rotor 11, more specifically, the friction sliding portion 11 a. The fin 23 prevents the deformation of the frictional sliding portion 11a of the disk rotor 11 when the brake caliper 12 presses the brake pad, that is, during braking, while the latent heat storage material changed in phase from the solid phase to the liquid phase. The latent heat storage material 21 whose phase has changed from a liquid phase to a solid phase is fixed while encouraging convection of 21.
Thus, the thermal energy (frictional heat) recovered (stored) by the heat recovery unit 20 is converted into electrical energy by the power recovery unit 30 and stored. For this reason, as shown in FIGS. 1 and 2, the power recovery unit 30 is provided between the friction sliding part 11a (more specifically, the latent heat storage material 21 accommodated in the accommodation space 11b) and the hub part 11c. A thermoelectric conversion unit 31 is provided which is arranged in an annular shape and is assembled to the disk rotor 11. The thermoelectric conversion unit 31 converts thermal energy into electrical energy using a well-known Seebeck effect possessed by a substance (for example, a Bi—Te based semiconductor). As shown in FIG. 2, the thermoelectric conversion unit 31 is heated by the thermal energy (friction heat) stored on one side, that is, the heating surface 31 a by the latent heat storage material 21 stored in the storage space 11 b, and the other side. That is, the cooling surface 31b is maintained (cooled) at a relatively low temperature by the hub portion 11c in contact with the outside air.
Here, as schematically shown in FIG. 5, the thermoelectric conversion unit 31 changes the thermoelectric conversion efficiency for converting heat energy into electric energy depending on the temperature difference between the heating surface 31 a and the cooling surface 31 b. That is, in the thermoelectric conversion unit 31, when the temperature difference between the heating surface 31a and the cooling surface 31b increases to a predetermined temperature difference T1 determined in terms of physical properties, the thermoelectric conversion efficiency changes until the maximum is reached. When the temperature difference between 31a and the cooling surface 31b becomes larger than the predetermined temperature difference T1, the thermoelectric conversion efficiency is reduced.
And in the thermoelectric conversion part 31, since the heating surface 31a is heated by the thermal energy (friction heat) stored by the latent heat storage material 21, and the cooling surface 31b is relatively cooled by the hub part 11c, it is well known. An electromotive force (hereinafter, this electromotive force is referred to as regenerative power) corresponding to the temperature difference between the heating surface 31a and the cooling surface 31b is generated by the Seebeck effect. That is, the thermoelectric conversion unit 31 can convert the thermal energy (friction heat) generated by the braking by the braking unit 10 and recovered by the heat recovery unit 20 into electric energy.
As described above, the electric energy (regenerative power) converted from the heat energy (friction heat) by the thermoelectric converter 31 is supplied to the battery 33 as the power storage means via the transformer circuit 32 as shown in FIG. . The transformer circuit 32 is an electric circuit having, for example, a DC-DC converter or a capacitor as a main component, and transforms the regenerative power output from the thermoelectric converter 31 and outputs it to the battery 33. The battery 33 stores the transformed output regenerative power. The connection between the thermoelectric converter 31 and the transformer circuit 32 is not directly related to the present invention, and any method may be adopted. For example, when the transformer circuit 32 electromagnetically collects regenerative power from the thermoelectric converter 31 by non-contact, or the transformer circuit 32 collects regenerative power from the thermoelectric converter 31 by contact via a slip ring or the like. Good.
Next, the operation of the vehicle braking device S according to the first embodiment configured as described above will be described. When a brake pedal (not shown) is operated by the driver, the braking unit 10 applies a braking force to the rotation of the wheel W. That is, in the braking unit 10, as described above, the brake hydraulic pressure corresponding to the operation of the brake pedal is supplied to the brake caliper 12. Then, the brake caliper 12 causes the brake pad to be pressed against and frictionally engaged with the friction sliding portion 11a of the disk rotor 11 that rotates integrally with the wheel W by the supplied brake hydraulic pressure. Thereby, a frictional force is generated between the frictional sliding portion 11a of the disk rotor 11 and the brake pad, and this frictional force is applied to the rotating wheel W as a braking force.
On the other hand, frictional heat (heat energy) generated in the frictional sliding portion 11a of the disk rotor 11 due to braking by the frictional force is recovered by a heat recovery unit 20 provided in the frictional sliding portion 11a. Hereinafter, recovery of frictional heat (thermal energy) by the heat recovery unit 20 will be described in detail.
In general, in the disc brake unit, a part of frictional heat (heat energy) generated in the friction sliding portion 11a of the disc rotor 11 is transferred to the hub portion 11c along with braking by friction. For this reason, as shown in FIG. 6, the temperature of the disk rotor 11 changes depending on the amount of heat generated by frictional heat (thermal energy) generated during braking. That is, as shown by a one-dot chain line for comparison in FIG. 6, the temperature of the conventional friction sliding portion 11a without the heat recovery portion 20 (hereinafter referred to as the conventional friction sliding portion temperature) is the amount of heat generated by braking. As it increases, it rises quickly. On the other hand, the temperature of the hub portion 11c indicated by a solid line in FIG. 6 (hereinafter referred to as the hub portion temperature) rises with an increase in the amount of heat generated by braking, but is gentler than the conventional friction sliding portion temperature. To rise. Therefore, the temperature difference between the conventional friction sliding portion temperature and the hub portion temperature tends to increase as the amount of heat generated by braking increases.
By the way, in the disk rotor 11 according to the present invention, the accommodation space 11b is formed in the friction sliding portion 11a to accommodate the latent heat storage material 21 of the heat recovery portion 20. As a result, most of the frictional heat (heat energy) generated in the frictional sliding part 11a is transferred to the inside of the frictional sliding part 11a, in other words, into the accommodating space 11b. For this reason, the heat recovery unit 20 recovers frictional heat (thermal energy) by absorbing heat (thermal energy) of the frictional heat (thermal energy) transferred by the latent heat storage material 21 accommodated in the accommodation space 11b. As a result, it is possible to suppress an increase in the temperature difference between the temperature of the friction sliding part 11a provided with the heat recovery part 20 (hereinafter referred to as the friction sliding part temperature) and the hub part temperature. This will be described in detail below.
First, the case where the braking unit 10 applies a braking force will be described. When the braking unit 10 starts to apply the braking force, the latent heat storage material 21 is heated by frictional heat (heat energy) transferred to the accommodation space 11b. And when the temperature of the heated latent heat storage material 21 is below melting | fusing point, the latent heat storage material 21 absorbs friction heat (thermal energy) in a solid-phase state (heat storage). In this case, as the temperature of the latent heat storage material 21 rises, the frictional sliding part temperature gradually rises as compared with the conventional frictional sliding part temperature, as indicated by a broken line in FIG. The heat recovery unit 20 (more specifically, the latent heat storage material 21) transmits the frictional heat (heat energy) stored (recovered) in this way to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30. Heat to friction sliding part temperature.
In such a solid phase, when the temperature of the latent heat storage material 21 exceeds the melting point due to heating, more specifically, as shown in FIG. 6, when the temperature of the latent heat storage material 21 becomes the melting point + ΔT2, the latent heat storage material 21 A part starts a phase change from the solid phase to the liquid phase, and the latent heat storage material 21 absorbs friction heat (heat energy) in a state where the solid phase and the liquid phase coexist. In the following description, the melting point + ΔT2 at which the solid phase and the liquid phase coexist is referred to as the coexistence temperature.
At this time, the latent heat storage material 21 absorbs frictional heat (thermal energy) as melting heat, that is, latent heat, and absorbs (stores heat) partly to change the phase from the solid phase to the liquid phase. As a result, when the latent heat storage material 21 is in a state in which the solid phase and the liquid phase coexist, the frictional sliding part temperature is kept constant at the coexistence temperature, as shown by the broken line in FIG. Therefore, an increase in the temperature difference between the friction sliding part temperature and the hub part temperature can be suppressed. The heat recovery unit 20 (more specifically, the latent heat storage material 21) transmits the frictional heat (heat energy) stored (recovered) in this way to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30. Heat to friction sliding part temperature (coexistence temperature).
Here, since the latent heat storage material 21 generally has a low thermal conductivity, the whole hardly changes from a solid phase to a liquid phase only by heating with frictional heat (thermal energy). As a result, the overall temperature of the latent heat storage material 21 may become uneven due to the presence of a relatively low temperature solid phase and a relatively high temperature liquid phase.
By the way, since the accommodation space 11b rotates integrally with the disk rotor 11, a centrifugal force can be applied to the latent heat storage material 21 accommodated in the accommodation space 11b. In this case, since the densities of the solid phase and the liquid phase are different from each other, in the state where the solid phase and the liquid phase coexist, the solid phase having a large density moves relatively to the outer peripheral side of the accommodation space 11b. The liquid phase having a small density moves relatively to the inner peripheral side of the accommodation space 11b. Further, the fins 23 formed in the accommodation space 11b can transfer frictional heat (thermal energy) to the latent heat storage material 21, and the solid phase of the latent heat storage material 21 and the rotation of the accommodation space 11b. The liquid phase can be stirred. Thereby, the phase change from a solid phase to a liquid phase is promoted, and the temperature of the entire latent heat storage material 21 is made uniform.
In the state where such a solid phase and a liquid phase coexist, when further heated, the latent heat storage material 21 changes to a liquid phase as a whole, and absorbs frictional heat (thermal energy) in the liquid phase state (heat storage). ) For this reason, when the latent heat storage material 21 is in a liquid phase state, as shown by a broken line in FIG. The heat recovery unit 20 (more specifically, the latent heat storage material 21) transmits the frictional heat (heat energy) stored (recovered) in this way to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30. Heat to friction sliding part temperature.
Next, a case where the braking unit 10 stops applying the braking force will be described. When the braking unit 10 stops applying the braking force, frictional heat (thermal energy) is not generated, and the frictional sliding unit 11a, that is, the disc rotor 11, is cooled by, for example, traveling wind. In this case, for example, as described above, in the state in which the entire latent heat storage material 21 accommodated in the accommodation space 11b is phase-changed to the liquid phase, the latent heat storage material 21 is cooled along with the cooling of the friction sliding portion 11a. 21 changes from a liquid phase to a solid phase through a state in which the solid phase and the liquid phase coexist.
At this time, the latent heat storage material 21 releases (dissipates) the heat energy absorbed (stored) as described above in accordance with the phase change. In this case, particularly in a state where the solid phase and the liquid phase coexist, the latent heat storage material 21 is kept constant at the coexistence temperature until the phase changes to the solid phase. Thus, since the frictional heat (heat energy) stored (recovered) with the phase change can be released (released), the heat recovery is possible even when the braking unit 10 stops applying the braking force. The unit 20 can continue to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30 and transfer the frictional heat (thermal energy) to the frictional sliding unit temperature.
When the latent heat storage material 21 undergoes a phase change due to heat transfer of frictional heat (thermal energy) and undergoes volume expansion or contraction, as described above, the latent heat storage material 21 in the accommodation space 11b is accommodated by the volume change absorption mechanism 22. 21 volume changes are absorbed. In this case, in particular, when the latent heat storage material 21 undergoes a phase change from the liquid phase to the solid phase and the volume contracts, the metal bellows 22b of the volume change absorption mechanism 22 is liquid phase latent heat storage material 21 together with the bottom plate 22c by its elastic force. Is pushed down in the axial direction of the sleeve 22a. Thereby, the volume change absorption mechanism 22 absorbs the volume change (shrinkage change) of the latent heat storage material 21, and maintains the state in which the latent heat storage material 21 that contracts in the accommodation space 11b is filled without generating a void. Can do. Therefore, even when the temperature in the accommodation space 11b further falls to below the melting point of the latent heat storage material 21, and the volume further shrinks and the latent heat storage material 21 exists as a solid phase, there are voids in the accommodation space 11b. It is possible to suppress the occurrence, and it is possible to prevent the balance of mass in the disk rotor 11 that is a rotating body from being lost.
Thus, the electric power collection | recovery part 30 converts a thermal energy into an electrical energy using the friction heat (thermal energy) collect | recovered by the heat recovery part 20. FIG. More specifically, in the power recovery unit 30, the heating surface 31 a of the thermoelectric conversion unit 31 is heated to the friction sliding unit temperature by frictional heat (heat energy) stored (collected) by the heat recovery unit 20. Thus, the cooling surface 31b of the thermoelectric conversion part 31 is maintained at the hub part temperature by the hub part 11c. That is, in the disk rotor 11, the frictional sliding part temperature is on the high temperature side, and the hub part temperature is on the low temperature side.
Here, the friction sliding part temperature is maintained at a constant coexistence temperature by storing (recovering) frictional heat (thermal energy) by the heat recovery part 20 as described above. For this reason, especially when the braking unit 10 is applying a braking force, an increase in the temperature difference between the frictional sliding unit temperature on the high temperature side and the hub temperature on the low temperature side is effectively prevented. Is done. Incidentally, as described above, in the thermoelectric conversion unit 31, the temperature difference between the heating surface 31a and the cooling surface 31b, in other words, the temperature difference between the friction sliding portion temperature and the hub portion temperature is maintained at a predetermined temperature difference T1. The thermoelectric conversion efficiency is the best.
In this regard, as shown in FIG. 6, when the frictional sliding part temperature is maintained constant at the coexistence temperature, the temperature difference between the frictional sliding part temperature and the gradually rising hub part temperature is substantially equal to the temperature difference T1. Can be maintained. Furthermore, by maintaining the frictional sliding part temperature at the coexistence temperature, even if the frictional sliding part temperature rises from the coexistence temperature, the temperature difference between the frictional sliding part temperature and the hub part temperature increases. It is possible to prevent the temperature from becoming too high and to approach the temperature difference T1. Therefore, the thermoelectric conversion part 31 can convert friction heat (thermal energy) into regenerative electric power (electric energy) and collect it with favorable thermoelectric conversion efficiency.
Further, when the braking unit 10 stops applying the braking force, the heat recovery unit 20 continuously dissipates (releases) the frictional heat (thermal energy) stored (collected), thereby continuously maintaining the frictional sliding unit temperature. The heating surface 31a of the thermoelectric converter 31 can be heated. Thereby, even in a situation where frictional heat (heat energy) is not newly generated, a temperature difference can be generated between the frictional sliding part temperature on the high temperature side and the hub part temperature on the low temperature side.
Therefore, the thermoelectric conversion unit 31 can efficiently convert heat energy into electric energy and generate regenerative power by the well-known Seebeck effect according to the temperature difference between the heating surface 31a and the cooling surface 31b. . The regenerative power generated in this way is transformed by the transformer circuit 32 and stored in the battery 33. Thus, since the regenerative electric power stored in the battery 33 can be used by other devices mounted on the vehicle, for example, it is possible to reduce engine load and improve fuel efficiency.
As can be understood from the above description, according to the first embodiment, the latent heat storage material 21 of the heat recovery unit 20 is provided in the housing space 11b formed in the friction sliding portion 11a of the disc rotor 11, and the disc The thermoelectric conversion part 31 can be provided between the friction sliding part 11a (that is, the latent heat storage material 21) of the rotor 11 and the hub part 11c. Thereby, the frictional heat (thermal energy) generated by braking can efficiently transfer the frictional heat (thermal energy) to the latent heat storage material 21, and the latent heat storage by the centrifugal force accompanying the rotation of the disk rotor 11. The phase of the material 21 can be changed efficiently. Therefore, the frictional heat (heat energy) generated in the frictional sliding part 11a can be efficiently recovered as latent heat, and as a result, the temperature rise of the frictional sliding part 11a can be effectively suppressed.
Moreover, since the thermoelectric conversion part 31 can be arrange | positioned adjacent to the latent heat storage material 21, the heating surface 31a is heated with the frictional heat (thermal energy) stored in the latent heat storage material 21, and the thermoelectric conversion part 31 is contacted with the cooling surface 31b. The temperature difference between them can be maintained appropriately. Thereby, the thermoelectric conversion part 31 can convert the collect | recovered frictional heat (thermal energy) into regenerative electric power (electrical energy) by favorable thermoelectric conversion efficiency.
Moreover, since the volume change absorption mechanism 22 can be provided in the heat recovery part 20, the volume change accompanying the phase change of the latent heat storage material 21 in the accommodation space 11b can be absorbed reliably. Thereby, in particular, it is possible to prevent the generation of voids in the accommodation space 11b, which is highly likely to occur when the latent heat storage material 21 undergoes a phase change from the liquid phase to the solid phase, and the mass balance of the disk rotor 11 can be prevented. It can be prevented from collapsing. Therefore, due to the mass balance of the disc rotor 11 being lost, for example, it is possible to prevent an adverse effect on the running behavior and riding comfort of the vehicle.
Furthermore, the fins 23 can be provided alternately with the latent heat storage material 21 in the circumferential direction of the disk rotor 11 in the heat recovery unit 20. As a result, the frictional heat (heat energy) generated in the frictional sliding portion 11a can be efficiently transferred to the latent heat storage material 21, and the disk rotor 11 is in a state where the solid phase and the liquid phase coexist. Stirring can be effectively performed with rotation. Therefore, the temperature of the latent heat storage material 21 can be made uniform, and the heating surface 31a of the thermoelectric conversion unit 31 can be appropriately heated.
b. First modification of the first embodiment
In the first embodiment, the volume change absorption mechanism 22 and the fins 23 of the heat recovery unit 20 are provided without being brought into contact with the wall surface forming the accommodation space 11b. In this case, in order to efficiently transfer the frictional heat (heat energy) generated in the friction sliding part 11a to the latent heat storage material 21 of the heat recovery part 20, the shape of the fins 23 is changed, and further fins are provided. It is also possible to implement. Hereinafter, although this 1st modification is demonstrated in detail, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the description is abbreviate | omitted.
In the first modification, as shown in FIG. 7, the heat recovery unit 20 includes fins 23 ′ instead of the fins 23 in the first embodiment. The fins 23 ′ are thermally connected to an inner wall surface forming the accommodation space 11b, more specifically, an inner wall surface located on the outer peripheral side of the friction sliding portion 11a and an inner wall surface located on the inner peripheral side. Is formed.
Moreover, in this 1st modification, fin 23'a and 23'b which thermally connects the inner wall face which forms the accommodation space 11b, and the outer peripheral surface of the sleeve 22a of the volume change absorption mechanism 22 as needed. Is formed. The fin 23'a thermally connects the inner wall surface located on the outer peripheral side of the friction sliding portion 11a and the outer peripheral surface of the sleeve 22a of the volume change absorbing mechanism 22 among the inner wall surfaces forming the accommodation space 11b. The fin 23'b thermally connects the inner wall surface located on the inner circumferential side of the friction sliding portion 11a and the outer circumferential surface of the sleeve 22a of the volume change absorbing mechanism 22 among the inner wall surfaces forming the accommodation space 11b. . Whether or not the fins 23′a and 23′b are to be provided is confirmed by experimentally confirming the amount of heat necessary to change the phase of the latent heat storage material 21, and based on this confirmation, the fins 23′a and fins It may be determined that at least one of 23′b is provided or that fins 23′a and 23′b are not provided.
When the fins 23 ′ a and 23 ′ b are provided, the frictional heat (heat energy) transferred through the fins 23 ′ a and 23 ′ b is more effectively transferred to the latent heat storage material 21. Therefore, for example, it is desirable to form the sleeve 22a of the volume change absorption mechanism 22 from a material having better thermal conductivity than iron such as aluminum. By selecting the material for forming the sleeve 22a in this way, frictional heat (thermal energy) can be efficiently transferred to the inside of the latent heat storage material 21.
In the first modified example configured as described above, when a braking force is applied by the braking unit 10, the frictional heat (heat energy) generated in the frictional sliding part 11 a of the disk rotor 11 is applied to the fins 23 ′. The heat is transferred to the inside of the latent heat storage material 21 accommodated in the accommodation space 11b. Further, when the fins 23 ′ a and 23 ′ b are provided, the frictional heat generated in the friction sliding portion 11 a through the fins 23 ′ a and 23 ′ b and the sleeve 22 a of the volume change absorbing mechanism 22. (Heat energy) is transferred to the inside of the latent heat storage material 21.
Thereby, for example, in a state where the solid phase and the liquid phase coexist, in addition to stirring by the relative movement of the solid phase and the liquid phase by the centrifugal force described above, frictional heat (thermal energy) ) Is further transferred, the phase change from the solid phase to the liquid phase is further promoted, and the temperature of the entire latent heat storage material 21 is made uniform. That is, in the first modification, frictional heat (heat energy) can be transferred more efficiently than in the first embodiment. Therefore, the heating surface 31a of the thermoelectric conversion unit 31 can be heated more stably, and regenerative power can be generated.
Furthermore, in this 1st modification, it becomes the structure where the latent heat storage material 21 is partitioned off by adjacent fin 23 '. Therefore, when the latent heat storage material 21 undergoes a phase change, the volume change is absorbed by the volume change absorption mechanism 22 and the movement in the circumferential direction in the accommodation space 11b is suppressed, so that the disk rotor which is a rotating body The effect that the balance of the mass in 11 can be prevented more effectively can be expected.
Other effects are the same as in the first embodiment.
c. Second modification of the first embodiment
In the first embodiment and the first modified example, the thermoelectric converter 31 of the power recovery unit 30 is the frictional sliding part 11a of the disk rotor 11 (more specifically, the latent heat storage material accommodated in the accommodating space 11b). 21) and the hub portion 11c, the heating surface 31a was heated to the friction sliding portion temperature, and the cooling surface 31b was maintained at the hub portion temperature. By the way, since the disk rotor 11 is disposed under the so-called spring of the vehicle, vibrations and the like are easily input as the vehicle travels. Further, there is a possibility that a shearing force or stress accompanying heating and cooling acts on the thermoelectric conversion unit 31. For this reason, when the thermoelectric conversion part 31 is assembled | attached to the disk rotor 11, it is desirable to protect the thermoelectric conversion part 31 favorably from the above-mentioned external force. Hereinafter, although this 2nd modification is demonstrated in detail, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the description is abbreviate | omitted.
In the second modified example, as shown in FIG. 8, the thermoelectric conversion unit 31 constituting the power recovery unit 30 is divided into a plurality. In the second modification, each thermoelectric conversion unit 31 is coupled to the disk rotor 11 by the floating fastening mechanism 34. The floating fastening mechanism 34 is connected to the disk rotor 11 by a fastening collar 34a for fixing the connected thermoelectric conversion part 31 to the disk rotor 11, a connecting member 34b for connecting the thermoelectric conversion parts 31 adjacent to each other in a circumferential shape, and the fastening collar 34a. A heat-resistant heat insulating material 34c that is fixed and covers the thermoelectric conversion portion 31.
Here, the fastening collar 34a is formed in a hollow cylindrical shape from stainless steel having a low thermal conductivity, for example, and is connected by a connecting member 34b by forming stepped portions at both ends as shown in FIG. The thermoelectric conversion portion 31 and the heat-resistant heat insulating material 34 c thus fixed are fixed to the disk rotor 11. In addition, when fixing the thermoelectric conversion part 31 connected by the connection member 34b to the disk rotor 11, as shown in FIG. 9, the fastening collar 34a is between the molded step part and the heat-resistant heat insulating material 34c. Fix it so that some clearance is generated.
Further, the connecting member 34b is formed from a flexible material. And the connection member 34b connects each thermoelectric conversion part 31 spaced apart from the fastening collar 34a, in order to prevent that unnecessary stress acts on the thermoelectric conversion part 31. As shown in FIG.
Further, as shown in FIG. 10, the floating fastening mechanism 34 includes a displacement regulating member 34 d having a substantially U-shaped cross section, and a thermoelectric conversion unit in order to allow a radial displacement of the thermoelectric conversion unit 31 in the disk rotor 11. 31 and a displacement absorbing member 34e disposed between the displacement regulating member 34d. Here, the displacement regulating member 34d is formed of, for example, a copper plate having a high thermal conductivity. Further, the displacement absorbing material 34e is also made of, for example, a copper mesh, a copper mesh wire, a copper mesh or the like having a high thermal conductivity.
In the second modification configured as described above, the thermoelectric conversion section 31 divided into a plurality is so-called floating coupled to the disk rotor 11 by the floating fastening mechanism 34. For this reason, in a situation where a shearing force or the like can act on the thermoelectric conversion part 31 in the circumferential direction with heating and cooling, for example, the connecting member 34b is deformed, thereby causing a shearing force or the like on the thermoelectric conversion part 31. Can be prevented from acting. Moreover, in the situation where the thermoelectric conversion part 31 is displaced in the radial direction of the disk rotor 11, for example, the displacement of the thermoelectric conversion part 31 is allowed by deformation of the displacement absorbing material 34 e, and stress acts on the thermoelectric conversion part 31. This can be prevented.
In addition, the fastening collar 34a is formed of a material having a small thermal conductivity, and the displacement regulating member 34d and the displacement absorbing member 34e are formed of a material having a large thermal conductivity, so that the friction sliding portion 11a of the disk rotor 11 can be used. The generated frictional heat (thermal energy) can be preferentially transferred to the heating surface 31a of the thermoelectric converter 31. Further, the heat-resistant heat insulating material 34 c covers the thermoelectric conversion part 31, so that the frictional heat (heat energy) generated in the frictional sliding part 11 a of the disk rotor 11 is preferentially applied to the heating surface 31 a of the thermoelectric conversion part 31. Heat can be transferred.
That is, as in the second modification, friction is transferred from the friction sliding portion 11a to the hub portion 11c by appropriately selecting the material of the members constituting the floating fastening mechanism 34 based on the thermal conductivity. The amount of heat (heat energy) heat transfer can be controlled appropriately. Therefore, since the heating surface 31a of the thermoelectric conversion unit 31 can be efficiently heated, the power generation efficiency of regenerative power by the thermoelectric conversion unit 31 can be improved.
Other effects are the same as those of the first embodiment and the first modification.
Various modifications can be made in the second modified example. For example, in the said 2nd modification, the thermoelectric conversion part 31 was shape | molded in circular arc shape, and it implemented so that it might be connected by the connection member 34b. In this case, for example, as shown in FIG. 11, it is also possible to implement such that the connecting member 34b connects the thermoelectric conversion portion 31 formed in a linear shape. In this case, although the thermoelectric conversion part 31 can be molded very easily, the width in the radial direction of the frictional sliding part 11a of the disk rotor 11 may be reduced. Accordingly, when the linear thermoelectric conversion unit 31 is employed, it is preferable that the thermoelectric conversion unit 31 is assembled to the large-diameter disk rotor 11.
Further, in the second modification, as shown in FIG. 9, the step portions formed at both ends of the fastening collar 34a are fixed to the disk rotor 11 via the heat-resistant heat insulating material 34c. In this case, when the mechanical strength of the heat-resistant heat insulating material 34c is small, as shown in FIG. 12, two step portions are formed at both ends of the fastening collar 34a, and each step portion has a heat-resistant heat insulating material 34c. It is also possible to carry out so as to contact the disk rotor 11.
Furthermore, in the said 2nd modification, the heat resistant heat insulating material 34c was provided and implemented. However, it goes without saying that the heat-resistant heat insulating material 34c can be omitted if necessary.
d. Third modification of the first embodiment
In the first embodiment and each modification, the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 is relatively cooled by the hub portion 11c. More specifically, the hub portion temperature is maintained. Carried out. In these cases, for example, as shown in FIG. 6, the hub portion temperature also gradually increases as the amount of heat generated by braking increases, so the temperature difference T1 that maximizes the thermoelectric conversion efficiency of the thermoelectric conversion portion 31 is continued. And may be difficult to maintain. In this case, it is possible to absorb the frictional heat (heat energy) transferred to the hub portion 11c of the disk rotor 11 and suppress the increase in the hub portion temperature. Hereinafter, although the 3rd modification of this 1st Embodiment is demonstrated in detail, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the description is abbreviate | omitted. In the following description, for easy understanding, the accommodation space 11b in the first embodiment is referred to as a high temperature side accommodation space 11b, the latent heat storage material 21 is referred to as a high temperature latent heat storage material 21, and the coexistence temperature is The high temperature side coexistence temperature.
In the third modified example, as shown in FIGS. 13 and 14, a low-temperature side accommodation space 11 d is formed in the hub portion 11 c of the disk rotor 11. And the heat recovery part 20 in this 3rd modification is equipped with the low temperature latent heat storage material 24 accommodated in the low temperature side accommodation space 11d. Similarly to the high-temperature latent heat storage material 21, the low-temperature latent heat storage material 24 changes its own temperature according to a change in the state of the substance, that is, a phase change from the solid phase to the liquid phase or a phase change from the liquid phase to the solid phase. It has physical properties to absorb heat or dissipate without generating any. As the low-temperature latent heat storage material 24, for example, Na having a melting point of about 50 to 100 ° C. ₂ SO ₄ ・ 10H ₂ Hydrated salts such as O can be employed.
Therefore, in the low-temperature latent heat storage material 24, when the temperature in the low-temperature side accommodation space 11d rises, it absorbs thermal energy and changes in phase from a solid phase to a liquid phase at a temperature lower than that of the high-temperature latent heat storage material 21. When the temperature in the side accommodating space 11d is lowered, the absorbed thermal energy is released and the phase changes from the liquid phase to the solid phase. When the low-temperature latent heat storage material 24 also undergoes a phase change and the solid phase and the liquid phase coexist, the thermal energy is absorbed (endothermic) or released (radiated) without accompanying its own temperature change. To do.
Similarly to the high-temperature latent heat storage material 21, the low-temperature latent heat storage material 24 also undergoes a volume change when the phase changes from the solid phase to the liquid phase or from the liquid phase to the solid phase. For this reason, the heat recovery unit 20 in the second embodiment absorbs the volume change of the low-temperature latent heat storage material 24 accommodated in the low-temperature side accommodation space 11d, and suppresses the generation of voids in the low-temperature side accommodation space 11d. For this purpose, as shown in FIG. 14, the hub portion 11c of the disk rotor 11 is provided with a plurality of volume change absorbing mechanisms 22 at equal intervals in the circumferential direction.
Next, the operation of the vehicle braking device S according to the third modified example configured as described above will be described. Also in the third modified example, the braking unit 10 applies a braking force to the rotation of the wheel W, as in the first embodiment. That is, also in the braking unit 10, when brake fluid pressure corresponding to the operation of a brake pedal (not shown) by the driver is supplied to the brake caliper 12, the brake caliper 12 is integrated with the wheel W by the supplied brake fluid pressure. A brake pad is pressed against the frictional sliding portion 11a of the rotating disc rotor 11 and frictionally engaged. As a result, as in the first embodiment, frictional force (braking force) is generated between the frictional sliding portion 11a of the disk rotor 11 and the brake pad, and frictional heat (thermal energy) is generated.
Thus, the frictional heat (heat energy) generated in the frictional sliding portion 11a of the disk rotor 11 due to braking by the frictional force is recovered by the heat recovery unit 20. The recovered frictional heat (thermal energy) is converted into regenerative power (electric energy) by the power recovery unit 30 and stored. First, recovery of frictional heat (thermal energy) by the heat recovery unit 20 of the third modification will be described in detail.
In the third modification, the heat recovery unit 20 includes a high-temperature latent heat storage material 21 housed in a high-temperature side housing space 11b formed in the friction sliding part 11a, and a low-temperature side housing formed in the hub part 11c. And a low-temperature latent heat storage material 24 housed in the space 11d. Thereby, the high-temperature latent heat storage material 21 is heated by the frictional heat (heat energy) generated in the friction sliding portion 11a, and the solid phase and the liquid phase coexist in the same manner as in the first embodiment. After that, the phase changes from the solid phase to the liquid phase. Therefore, as shown in FIG. 15, the high-temperature latent heat storage material 21 of the heat recovery unit 20 changes with a high-temperature side coexistence temperature with respect to the heat generation amount change due to braking, and the heating surface 31a of the thermoelectric conversion unit 31 is changed. Heat.
On the other hand, the low-temperature latent heat storage material 24 stored in the low-temperature-side storage space 11d absorbs (stores) the frictional heat (heat energy) transferred to the hub portion 11c. Thereby, the heat recovery unit 20 in the third modification can further suppress an increase in the temperature difference between the frictional sliding part temperature and the hub part temperature as compared with the first embodiment. This will be described in detail below.
First, the case where the braking unit 10 applies a braking force will be described. When the braking unit 10 starts applying the braking force, the low-temperature latent heat storage material 24 is heated by frictional heat (heat energy) transferred to the low-temperature side accommodation space 11d. When the temperature of the heated low-temperature latent heat storage material 24 is equal to or lower than the melting point, the low-temperature latent heat storage material 24 absorbs frictional heat (heat energy) in a solid state (stores heat). In this case, as the temperature of the low-temperature latent heat storage material 24 increases, the hub temperature gradually increases as shown by the solid line in FIG. Then, the low-temperature latent heat storage material 24 of the heat recovery unit 20 transfers the frictional heat (heat energy) stored (recovered) in this way to the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 to the hub part temperature. maintain.
In such a solid phase, when the temperature of the low-temperature latent heat storage material 24 exceeds the melting point due to heating, more specifically, as shown in FIG. 15, when the temperature of the low-temperature latent heat storage material 24 reaches the melting point + ΔT3, the low-temperature latent heat storage material 24 A part of the material 24 starts a phase change from the solid phase to the liquid phase, and the low-temperature latent heat storage material 24 absorbs friction heat (thermal energy) in a state where the solid phase and the liquid phase coexist. In the following description, the melting point + ΔT3 at which the solid phase and the liquid phase coexist in the low-temperature latent heat storage material 24 is referred to as a low-temperature side coexistence temperature.
At this time, the low-temperature latent heat storage material 24 absorbs frictional heat (thermal energy) as melting heat, that is, latent heat, and absorbs (stores heat) partly to change the phase from the solid phase to the liquid phase. It becomes. Thereby, when the low-temperature latent heat storage material 24 is in a state where the solid phase and the liquid phase coexist, the hub portion temperature is kept constant at the low-temperature side coexistence temperature as shown by the solid line in FIG. Therefore, an increase in the temperature difference between the friction sliding part temperature and the hub part temperature can be further suppressed. Then, the low-temperature latent heat storage material 24 of the heat recovery unit 20 transfers the frictional heat (thermal energy) stored (recovered) in this way to the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 and transfers the hub temperature ( Maintain the coexistence temperature.
Here, since the low-temperature latent heat storage material 24 also generally has a low thermal conductivity, the whole is unlikely to change from a solid phase to a liquid phase only by heating with frictional heat (thermal energy). As a result, similar to the high-temperature latent heat storage material 21, the overall temperature of the low-temperature latent heat storage material 24 may become nonuniform due to the presence of a relatively low-temperature solid phase and a relatively high-temperature liquid phase.
By the way, since the low temperature side accommodation space 11d also rotates integrally with the disk rotor 11, a centrifugal force can be applied to the low temperature latent heat storage material 24 accommodated in the low temperature side accommodation space 11d. Thereby, a solid phase with a high density moves relatively to the outer peripheral side of the low temperature side accommodation space 11d, and a liquid phase with a low density moves relatively to the inner circumference side of the low temperature side accommodation space 11b. Thereby, the phase change from a solid phase to a liquid phase is promoted, and the temperature of the entire low-temperature latent heat storage material 24 is made uniform.
When the solid phase and the liquid phase coexist in this state and further heated, the low-temperature latent heat storage material 24 changes to the liquid phase as a whole and absorbs frictional heat (thermal energy) in the liquid phase ( Heat storage). For this reason, when the low-temperature latent heat storage material 24 is in a liquid phase state, the hub portion temperature rises from the coexistence temperature as shown by a solid line in FIG. Then, the low-temperature latent heat storage material 24 of the heat recovery unit 20 transfers the frictional heat (heat energy) stored (recovered) in this way to the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 to the hub part temperature. maintain.
Next, a case where the braking unit 10 stops applying the braking force will be described. When the braking unit 10 stops applying the braking force, frictional heat (thermal energy) is not generated, and the frictional sliding unit 11a and the hub unit 11c, that is, the disc rotor 11 are cooled by, for example, traveling wind. In this case, for example, as described above, in the state where the whole of the low-temperature latent heat storage material 24 accommodated in the low-temperature side accommodation space 11d is in the liquid phase, the low-temperature latent heat is accompanied by the cooling of the hub portion 11c. Similar to the high-temperature latent heat storage material 21, the heat storage material 24 changes from a liquid phase to a solid phase through a state in which the solid phase and the liquid phase coexist.
At this time, the high-temperature latent heat storage material 21 and the low-temperature latent heat storage material 24 release (release) the heat energy absorbed (stored) as described above in accordance with the phase change. In this case, in particular, in a state where the solid phase and the liquid phase coexist, the high temperature latent heat storage material 21 and the low temperature latent heat storage material 24 are all kept constant at the coexistence temperature until the phase changes to the solid phase. Thus, since the frictional heat (heat energy) stored (recovered) with the phase change can be released (released), the heat recovery is possible even when the braking unit 10 stops applying the braking force. The high-temperature latent heat storage material 21 of the unit 20 can continue to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30 and transfer frictional heat (heat energy) to the frictional sliding unit temperature, The heat recovery unit 20 low-temperature latent heat storage material 24 can transfer heat to the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 and maintain it at the hub temperature.
In the third modified example, when the low-temperature latent heat storage material 24 undergoes phase change due to heat transfer of frictional heat (thermal energy) and undergoes volume expansion or contraction, as described above, the volume change absorption mechanism 22 The volume change of the low-temperature latent heat storage material 24 in the low-temperature side accommodation space 11d is absorbed. In this case, in particular, when the low-temperature latent heat storage material 24 undergoes a phase change from the liquid phase to the solid phase and the volume shrinks, the metal bellows 22b of the volume change absorption mechanism 22 moves together with the bottom plate 22c with the liquid phase low-temperature latent heat storage. The material 24 is pushed down in the axial direction of the sleeve 22a.
Thereby, the volume change absorption mechanism 22 absorbs the volume change (shrinkage change) of the low-temperature latent heat storage material 24, and the low-temperature latent heat storage material 24 that shrinks in volume in the low-temperature side accommodation space 11d is filled without generating a gap. Can be maintained. Therefore, even when the temperature in the low-temperature side storage space 11d is further lowered to below the melting point of the low-temperature latent heat storage material 24, the volume is further contracted, and the low-temperature latent heat storage material 24 exists as a solid phase, It can suppress that a space | gap arises in the space 11d, and it can prevent that the balance of the mass in the disc rotor 11 which is a rotary body collapse | crumbles.
As described above, the power recovery unit 30 converts the thermal energy into electrical energy using the frictional heat (thermal energy) recovered by the heat recovery unit 20 as described above. Specifically, in the power recovery unit 30, the heating surface 31 a of the thermoelectric conversion unit 31 is heated to the frictional sliding unit temperature by frictional heat (thermal energy) stored (collected) by the high-temperature latent heat storage material 21. Thus, the cooling surface 31 b of the thermoelectric converter 31 is maintained at the hub temperature by the low-temperature latent heat storage material 24.
Here, the friction sliding part temperature is maintained at a constant high temperature side coexistence temperature by the high-temperature latent heat storage material 21 of the heat recovery part 20 as described above. Further, as described above, the hub portion temperature is maintained at a constant low-temperature side coexistence temperature by the low-temperature latent heat storage material 24 of the heat recovery unit 20. Accordingly, in the third modification, as shown in FIG. 15, the temperature difference between the heating surface 31a and the cooling surface 31b, in other words, the temperature difference between the friction sliding portion temperature and the hub portion temperature is set to a predetermined temperature. Since it can maintain continuously with difference T1, thermoelectric conversion efficiency can be maintained more favorably.
For this reason, the thermoelectric conversion unit 31 can efficiently convert heat energy into electric energy and generate regenerative power by the well-known Seebeck effect according to the temperature difference between the heating surface 31a and the cooling surface 31b. it can. The regenerative power generated in this way is transformed by the transformer circuit 32 and stored in the battery 33, as in the first embodiment. Thus, since the regenerative electric power stored in the battery 33 can be used by other devices mounted on the vehicle, for example, it is possible to reduce engine load and improve fuel efficiency.
Therefore, in the third modification, the high temperature side accommodation space 11b is formed in the friction sliding portion 11a of the disk rotor 11 as the rotating body to accommodate the high temperature latent heat storage material 21, and the low temperature side accommodation space is accommodated in the hub portion 11c. 11d can be formed and the low-temperature latent heat storage material 24 can be accommodated. And the temperature difference between the heating surface 31a and the cooling surface 31b of the thermoelectric conversion part 31 by the high temperature latent heat storage material 21 and the low temperature latent heat storage material 24 becoming constant at the high temperature side coexistence temperature and the low temperature side coexistence temperature, respectively. Can be continuously maintained at a temperature difference at which the thermoelectric conversion efficiency is good. As a result, the frictional heat (thermal energy) can be generated (converted) into regenerative power (electric energy) more efficiently, and the generated regenerative power can be used in other devices mounted on the vehicle. it can.
Other effects are the same as those of the first embodiment and the respective modifications.
e. Second embodiment
Next, a vehicle braking device S according to a second embodiment of the present invention will be described. In the first embodiment and each modification, the brake unit 10 is implemented as a disc brake unit including the disc rotor 11 as a rotating body and the brake caliper 12 as friction engagement means. In the second embodiment, as shown in FIG. 16, the brake unit 10 employs a drum brake unit including a brake drum 13 as a rotating body and a brake shoe 14 as a friction engagement means. Since the vehicle braking device S of the second embodiment includes the heat recovery unit 20 and the power recovery unit 30 similar to those of the first embodiment, the heat recovery unit 20 and the power recovery unit 30 Detailed description is omitted.
The brake drum 13 in the second embodiment is assembled with a nut with respect to a hub H that is rotatably supported by a knuckle N that constitutes a suspension device (not shown), and rotates integrally with a wheel W. . Further, the brake drum 13 includes a friction sliding portion 13a that frictionally slides with a lining assembled to a brake shoe 12 to be described later at an outer peripheral portion thereof. As shown in FIG. 16, the friction sliding portion 13 a is formed with an accommodation space 13 b that is filled with and accommodated with a latent heat storage material 21 as latent heat storage means constituting the heat recovery portion 20. Further, as shown in FIG. 16, the brake drum 13 includes a hub portion 13 c as a fixing portion that is fixed in contact with the hub H.
As shown in FIG. 16, the brake shoe 14 is housed in the brake drum 13 and assembled to a backing plate 15 that is fixed to the vehicle body so as not to rotate. The brake shoe 14 is frictionally engaged with the friction sliding portion 13 a of the brake drum 13 by the operation of the wheel cylinder WS fixed to the backing plate 15. The detailed structure and operation of the drum brake unit are the same as those of the well-known drum brake unit, and are not directly related to the present invention, so the description thereof is omitted.
In the braking unit 10 configured as described above, when a brake pedal (not shown) is operated by the driver, the brake fluid pressure is supplied to the wheel cylinder WS. Thereby, the brake shoe 14 presses the lining against the friction sliding portion 13a of the brake drum 13 and frictionally engages with the increase of the supplied brake hydraulic pressure. A frictional force is generated by frictionally engaging the lining with the brake drum 13 that rotates integrally with the wheel W, and this frictional force is applied as a braking force for braking the rotation of the wheel W. Therefore, the braking unit 10 in the second embodiment also brakes the rotating wheel W by converting the kinetic energy into heat energy (friction heat) by friction as the vehicle is braked.
Thus, the heat energy (friction heat) generated by braking is recovered by the heat recovery unit 20 provided in the friction sliding portion 13a of the brake disk 13. And in this 2nd Embodiment, as shown in FIG.16 and FIG.17, the heat recovery part 20 is the latent heat storage material 21 accommodated in the accommodation space 13b formed in the friction sliding part 13a, and latent heat. A plurality of volume change absorbing mechanisms 22 that suppress the generation of voids in the accommodation space 13b by absorbing the volume change of the heat storage material 21 and fins 23 (not shown) formed in the accommodation space 13b are provided. Here, in this 2nd Embodiment, the volume change absorption mechanism 22 differs a little compared with the said 1st Embodiment.
That is, as shown in FIGS. 17 and 18, the volume change absorbing mechanism 22 in the second embodiment is directed in the direction along the rotation axis of the brake drum 13, that is, from the side surface of the brake drum 13 toward the housing space 13b. And press-fitted. That is, the second embodiment is different in that the volume change direction of the latent heat storage material 21 and the expansion / contraction direction of the bellows 22b can be matched, so that the formation of the notch 22a1 in the sleeve 22a becomes unnecessary. In addition, by providing the volume change absorption mechanism 22 on the side surface of the brake drum 13, the volume change absorption mechanism 22 is prevented from falling off even when the brake drum 13 rotates and a centrifugal force acts on the volume change absorption mechanism 22. can do.
Here, as shown in FIG. 19, the volume change absorbing mechanism 22 may be press-fitted from the outer peripheral surface side of the brake drum 13 toward the accommodation space 13 b. In this case, it is necessary to press-fit the volume change absorption mechanism 22 deeply into the accommodation space 13b in order to prevent the drop due to the centrifugal force. For this reason, in this case, a plurality of notches 22a1 that allow the circulation of the latent heat storage material 21 in the accommodation space 13b may be formed in the sleeve 22a in the circumferential direction, as in the first embodiment. When the possibility of dropping due to the centrifugal force is low depending on the vehicle, it is possible to reduce the amount of press-fitting into the accommodation space 13b of the volume change absorption mechanism 22 as shown in FIG. In this case, since the circulation of the latent heat storage material 21 is allowed without forming the notch 22a1 in the sleeve 22a, the volume change of the latent heat storage material 21 can be absorbed.
In the second embodiment as well, although not shown, the fins 23 are alternately formed with the latent heat storage material 21 in the circumferential direction of the brake drum 13 in the accommodation space 13b.
Also in the second embodiment, the heat energy (friction heat) recovered (stored) by the heat recovery unit 20 is converted into electric energy by the power recovery unit 30 and stored. For this reason, also in this 2nd Embodiment, the electric power collection | recovery part 30 is provided with the thermoelectric conversion part 31, the transformation circuit 32, and the battery 33, as shown in FIG. Here, as shown in FIGS. 16 and 17, the thermoelectric converter 31 in the second embodiment has one side, that is, the heat energy stored by the latent heat storage material 21 in which the heating surface 31 a is accommodated in the accommodation space 13 b. Heated by (frictional heat), the other side, that is, the cooling surface 31b is cooled by the hub portion 13c in contact with the outside air.
Next, the operation of the vehicle braking device S according to the second embodiment configured as described above will be described. Also in the second embodiment, the braking unit 10 applies a braking force to the rotation of the wheel W, as in the first embodiment. That is, in the brake unit 10 as well, when brake fluid pressure corresponding to the operation of a brake pedal (not shown) by the driver is supplied to the wheel cylinder WS, the brake shoe 14 is integrated with the wheel W by the supplied brake fluid pressure. The lining is pressed against the friction sliding portion 13a of the brake drum 13 that rotates in a frictional manner, and is frictionally engaged. Thereby, a frictional force (braking force) is generated between the frictional sliding portion 13a of the brake drum 13 and the lining, and frictional heat (thermal energy) is generated.
As described above, the frictional heat (heat energy) generated in the frictional sliding portion 13a of the brake drum 13 due to the braking by the frictional force is recovered by the heat recovery unit 20 as in the first embodiment. The recovered frictional heat (thermal energy) is converted into regenerative power (electric energy) by the power recovery unit 30 and stored. First, recovery of frictional heat (thermal energy) by the heat recovery unit 20 of the second embodiment will be described in detail.
In the second embodiment, the latent heat storage material 21 is housed in the housing space 13b formed in the friction sliding portion 13a of the brake drum 13. Thereby, the latent heat storage material 21 is heated by the frictional heat (thermal energy) generated in the friction sliding portion 13a, and the solid phase and the liquid phase coexist as in the first embodiment. Phase change from solid phase to liquid phase. Accordingly, the latent heat storage material 21 of the heat recovery unit 20 changes with a coexisting temperature with respect to the heat generation amount change due to braking, for example, as shown in FIG. 6, and the heating surface of the thermoelectric conversion unit 31. 31a is heated to the friction sliding part temperature.
When the braking unit 10 stops applying the braking force, frictional heat (thermal energy) is not generated, and the frictional sliding unit 13a, that is, the brake drum 13 is cooled by, for example, traveling wind. In this case, the latent heat storage material 21 dissipates (releases) the heat energy absorbed (stored) as described above in accordance with the phase change. In particular, in a state where the solid phase and the liquid phase coexist, all of the latent heat storage material 21 is kept constant at the coexistence temperature until the phase changes to the solid phase. Thus, since the frictional heat (heat energy) stored (recovered) with the phase change can be released (released), the heat recovery is possible even when the braking unit 10 stops applying the braking force. The unit 20 can continue to the heating surface 31a of the thermoelectric conversion unit 31 of the power recovery unit 30 and transfer the frictional heat (thermal energy) to the frictional sliding unit temperature.
And also in this 2nd Embodiment, the electric power collection | recovery part 30 converts a thermal energy into an electrical energy using the friction heat (thermal energy) collect | recovered by the heat recovery part 20. FIG. More specifically, in the power recovery unit 30, the heating surface 31 a of the thermoelectric conversion unit 31 is heated to the friction sliding unit temperature by frictional heat (heat energy) stored (collected) by the heat recovery unit 20. Thus, the cooling surface 31b of the thermoelectric conversion part 31 is maintained at the hub part temperature by the hub part 13c. That is, also in the brake drum 13, the friction sliding part temperature becomes a high temperature side, and the hub part temperature becomes a low temperature side.
Here, the friction sliding part temperature is maintained at a constant coexistence temperature by storing (recovering) frictional heat (thermal energy) by the heat recovery part 20 as described above. For this reason, especially when the braking unit 10 is applying a braking force, an increase in the temperature difference between the frictional sliding unit temperature on the high temperature side and the hub temperature on the low temperature side is effectively prevented. Is done. By the way, as described above, the thermoelectric converter 31 in the second embodiment also has a predetermined temperature difference between the heating surface 31a and the cooling surface 31b, in other words, the temperature difference between the friction sliding portion temperature and the hub portion temperature. Since the temperature difference T1 can be maintained, the thermoelectric conversion efficiency is the best.
In this regard, also in the second embodiment, as shown in FIG. 6, when the frictional sliding part temperature is kept constant at the coexistence temperature, the frictional sliding part temperature and the hub that rises gradually The temperature difference from the part temperature can be maintained at the temperature difference T1. Furthermore, by maintaining the frictional sliding part temperature at the coexistence temperature, even if the frictional sliding part temperature rises from the coexistence temperature, the temperature difference between the frictional sliding part temperature and the hub part temperature increases. It is possible to prevent the temperature from becoming too high and to approach the temperature difference T1.
In addition, when the braking unit 10 stops applying the braking force, the heat recovery unit 20 continuously releases the accumulated heat (recovered) frictional heat (thermal energy), thereby continuously converting the temperature to the frictional sliding unit temperature. The heating surface 31a of the part 31 can be heated. Thereby, even in a situation where frictional heat (heat energy) is not newly generated, a temperature difference can be generated between the frictional sliding part temperature on the high temperature side and the hub part temperature on the low temperature side.
Therefore, the thermoelectric conversion unit 31 can efficiently convert heat energy into electric energy and generate regenerative power by the well-known Seebeck effect according to the temperature difference between the heating surface 31a and the cooling surface 31b. . The regenerative power generated in this way is transformed by the transformer circuit 32 and stored in the battery 33. Thus, since the regenerative electric power stored in the battery 33 can be used by other devices mounted on the vehicle, for example, it is possible to reduce engine load and improve fuel efficiency.
As can be understood from the above description, according to the second embodiment, the latent heat storage material 21 of the heat recovery unit 20 is provided in the housing space 13b formed in the friction sliding portion 13a of the brake drum 13, and the brake A thermoelectric conversion portion 31 can be provided between the friction sliding portion 13a (that is, the latent heat storage material 21) of the drum 13 and the hub portion 13c. Thereby, the frictional heat (thermal energy) generated by braking can efficiently transfer the frictional heat (thermal energy) to the latent heat storage material 21 and the latent heat storage by the centrifugal force accompanying the rotation of the brake drum 13. The phase of the material 21 can be changed efficiently. Therefore, the frictional heat (heat energy) generated in the frictional sliding part 13a can be efficiently recovered as latent heat, and as a result, the temperature rise of the frictional sliding part 13a can be effectively suppressed.
Also in the second embodiment, since the thermoelectric converter 31 can be disposed adjacent to the latent heat storage material 21, the heating surface 31 a is heated by the frictional heat (thermal energy) stored in the latent heat storage material 21. Thus, the temperature difference from the cooling surface 31b can be appropriately maintained. Thereby, the thermoelectric conversion part 31 can convert the collect | recovered frictional heat (thermal energy) into regenerative electric power (electrical energy) by favorable thermoelectric conversion efficiency.
Moreover, since the volume change absorption mechanism 22 can be provided in the heat recovery part 20, the volume change accompanying the phase change of the latent heat storage material 21 in the accommodation space 13b can be absorbed reliably. Thereby, in particular, it is possible to prevent the generation of voids in the accommodation space 13b, which is highly likely to occur when the latent heat storage material 21 undergoes a phase change from the liquid phase to the solid phase, and the balance of the mass of the brake drum 13 can be prevented. It can be prevented from collapsing. Therefore, it is possible to prevent an adverse effect on the running behavior and riding comfort of the vehicle due to the mass balance of the brake drum 13 being lost.
Furthermore, the fins 23 can be provided alternately with the latent heat storage material 21 in the circumferential direction of the brake drum 13 in the heat recovery unit 20. As a result, the frictional heat (heat energy) generated in the frictional sliding portion 13a can be efficiently transferred to the latent heat storage material 21, and the brake drum 13 is in a state where the solid phase and the liquid phase coexist. Stirring can be effectively performed with rotation. Therefore, the temperature of the latent heat storage material 21 can be made uniform, and the heating surface 31a of the thermoelectric conversion unit 31 can be appropriately heated.
Here, when implementing this 2nd Embodiment, it can change and implement similarly to the 1st modification of the said 1st Embodiment, a 2nd modification, and a 3rd modification. That is, with respect to the fins 23 of the heat recovery unit 20 in the second embodiment, the frictional heat (heat energy) generated in the frictional sliding portion 13a is efficiently obtained as in the first modification of the first embodiment. In order to transfer heat to the latent heat storage material 21 of the heat recovery unit 20, it is possible to change the shape of the fin 23 and further provide a separate fin. Specifically, the inner wall surface forming the accommodation space 13b is deformed so as to be thermally connected, or the inner wall surface forming the accommodation space 13b and the outer peripheral surface of the sleeve 22a of the volume change absorption mechanism 22 are thermally connected. It can be deformed to connect.
Thereby, also in this 2nd Embodiment, the effect similar to the 1st modification of the said 1st Embodiment is acquired.
In addition, as with the second modification of the first embodiment, the thermoelectric conversion unit 31 of the power recovery unit 30 in the second embodiment is divided into a plurality of brake drums for better protection from the external force described above. 13 can be modified to be floating-coupled.
Thereby, also in this 2nd Embodiment, the effect similar to the 2nd modification of the said 1st Embodiment is acquired.
Furthermore, as with the third modification of the first embodiment, the heat recovery unit 20 according to the second embodiment includes a low-temperature latent heat storage material 24 in order to suppress an increase in the hub temperature of the hub 13c. It is possible to deform. In this case, as shown in FIG. 21, a low-temperature side accommodation space 13 d is formed in the hub portion 13 c of the brake drum 13. And in this low temperature side accommodation space 13d, the low temperature latent heat storage material 24 similar to the 3rd modification of the said 1st Embodiment is accommodated.
Thus, when the temperature of the low-temperature latent heat storage material 24 reaches the melting point + ΔT3 by providing the low-temperature latent heat storage material 24 in the heat recovery unit 20 in the second embodiment, a part of the low-temperature latent heat storage material 24 is released from the solid phase. Phase change is started in the liquid phase, and the low-temperature latent heat storage material 24 can absorb (store) the frictional heat (thermal energy) in a state where the solid phase and the liquid phase coexist.
Thus, the low-temperature latent heat storage material 24 absorbs frictional heat (thermal energy) as melting heat, that is, latent heat and absorbs (stores heat) partly to change the phase from the solid phase to the liquid phase, so that the low temperature side coexistence temperature is maintained. Thus, the hub temperature is kept constant at the low temperature side coexistence temperature. Therefore, an increase in the temperature difference between the friction sliding part temperature and the hub part temperature can be further suppressed. Then, the low-temperature latent heat storage material 24 of the heat recovery unit 20 transfers the frictional heat (thermal energy) stored (recovered) in this way to the cooling surface 31b of the thermoelectric conversion unit 31 of the power recovery unit 30 and transfers the hub temperature ( The coexistence temperature can be maintained.
And the electric power collection | recovery part 30 can convert a thermal energy into an electrical energy like the said 2nd Embodiment using the friction heat (thermal energy) collect | recovered by the heat recovery part 20 in this way. . Specifically, in the power recovery unit 30, the heating surface 31 a of the thermoelectric conversion unit 31 is heated to the frictional sliding unit temperature by frictional heat (thermal energy) stored (collected) by the high-temperature latent heat storage material 21. Thus, the cooling surface 31 b of the thermoelectric converter 31 is maintained at the hub temperature by the low-temperature latent heat storage material 24.
Here, the friction sliding part temperature is maintained at a constant high temperature side coexistence temperature by the high-temperature latent heat storage material 21 of the heat recovery part 20 as described above. Further, as described above, the hub portion temperature is maintained at a constant low-temperature side coexistence temperature by the low-temperature latent heat storage material 24 of the heat recovery unit 20. Therefore, when the heat recovery unit 20 includes the low-temperature latent heat storage material 24, the temperature difference between the heating surface 31a and the cooling surface 31b, in other words, the temperature difference between the friction sliding part temperature and the hub part temperature is a predetermined value. Since the temperature difference T1 can be maintained continuously, the thermoelectric conversion efficiency can be maintained better.
In carrying out the present invention, the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the object of the present invention.
For example, in each of the above-described embodiments and modifications, the heat recovery unit 20 recovers frictional heat (heat energy) generated with braking due to friction. However, the thermal energy recovered by the heat recovery unit 20 is not limited to frictional heat, and may be implemented so as to recover thermal energy from other heat sources.
Moreover, in each said embodiment and each modification, it implemented so that the volume change absorption mechanism 22 might be equipped with the metal bellows 22b which can be elastically deformed. In this case, any material may be employed instead of the metal bellows 22b as long as it can be elastically deformed with respect to the volume change of the (high temperature) latent heat storage material 21 or the low temperature latent heat storage material 24. In this case, for example, a shell in which a concave or convex stretchable deformable portion is formed on a substantially spherical base shell portion made of an elastic material may be used.

Claims

In a vehicle braking device that applies a braking force to the rotation of a vehicle wheel and collects thermal energy generated with the application of the braking force,
A rotating body that rotates integrally with a wheel of the vehicle and a friction engagement means that frictionally engages with a friction sliding portion of the rotating body to apply a braking force due to friction to the rotation of the wheel Braking force applying means for
The heat is contained in the friction sliding portion of the rotating body, and the phase change from the solid phase to the liquid phase or from the liquid phase to the solid phase due to the thermal energy generated by the friction engagement by the friction engagement means. Heat recovery means having latent heat storage means for storing energy as latent heat;
An electric power recovery means disposed between a latent heat storage means of the heat recovery means and a fixed portion of the rotating body with respect to the vehicle, and converts the heat energy stored in the latent heat storage means into electric energy and recovers it. A vehicular braking apparatus comprising:
The vehicle braking device according to claim 1,
The heat recovery means further includes
A vehicular braking apparatus comprising volume change absorbing means for absorbing a volume change accompanying a phase change of the latent heat storage means inside the friction sliding portion of the rotating body.
The vehicle braking device according to claim 2,
The vehicular braking apparatus, wherein the volume change absorbing means is provided at equal intervals in the circumferential direction of the rotating body.
In the vehicle braking device according to claim 2 or 3,
The volume change absorbing means absorbs the volume change by elastically deforming with respect to the volume change accompanying the phase change of the latent heat storage means inside the friction sliding portion of the rotating body. Braking device.
The vehicle braking device according to any one of claims 1 to 4, wherein:
The heat recovery means further includes
A vehicular braking apparatus comprising a fin for transferring heat energy generated in accordance with friction engagement by the friction engagement means to the latent heat storage means.
The vehicle braking device according to claim 5,
The vehicular braking apparatus according to claim 1, wherein the fins are alternately arranged with the latent heat storage means in a circumferential direction of the rotating body.
In the vehicle braking device according to claim 5 or 6,
A braking device for a vehicle, wherein the fin is thermally connected to an inner wall surface forming the friction sliding portion inside the friction sliding portion of the rotating body.
The vehicular braking apparatus according to any one of claims 1 to 7,
The power recovery means is
One side is heated by the latent heat storage means of the heat recovery means and the other side is maintained at a lower temperature than the one side, and the thermal energy is changed according to a temperature difference between the one side and the other side. A braking device for a vehicle, which is thermoelectric conversion means for converting into electric energy.
The vehicle braking device according to claim 8, wherein
The vehicular braking apparatus, wherein the thermoelectric conversion means is provided at a predetermined interval in the circumferential direction of the rotating body.
The vehicle braking device according to claim 9, wherein
A braking device for a vehicle, wherein the thermoelectric conversion means is fixed to the rotating body by floating coupling.
The vehicle braking device according to any one of claims 8 to 10, wherein
The power recovery means further includes:
A braking device for a vehicle, comprising: a power storage unit configured to store the electric energy converted by the thermoelectric conversion unit as electric power.
The vehicle braking device according to any one of claims 1 to 11,
The heat recovery means further includes
The phase change from the solid phase to the liquid phase or from the liquid phase to the solid phase is performed at a temperature lower than that of the high-temperature side latent heat storage unit accommodated in the fixed portion of the rotating body and accommodated in the friction sliding portion. A vehicular braking apparatus comprising a low-temperature latent heat storage means.
The vehicle braking device according to claim 12, wherein
The heat recovery means further includes
A vehicular braking apparatus comprising volume change absorbing means for absorbing a volume change accompanying a phase change of the low temperature side latent heat storage means inside the fixed portion of the rotating body.
The vehicle braking device according to claim 13,
The vehicular braking apparatus, wherein the volume change absorbing means is provided at equal intervals in the circumferential direction of the rotating body.
The vehicle braking device according to claim 13 or 14,
The volume change absorbing means is elastically deformed with respect to a volume change accompanying a phase change of the low-temperature side latent heat storage means inside the fixed portion of the rotating body, and absorbs the volume change. Braking device.
The vehicular braking apparatus according to any one of claims 1 to 15,
The braking force applying means is
A braking device for a vehicle, wherein the rotating body is a disc rotor, and the friction engagement means is a brake caliper.
The vehicular braking apparatus according to any one of claims 1 to 15,
The braking force applying means is
A vehicular braking device, wherein the rotating body is a drum drum unit, and the friction engagement means is a brake shoe.