JP2965600B2 - Driving force transmission device for four-wheel drive vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a front wheel drive shaft and a rear wheel drive shaft of a four-wheel drive vehicle,
Alternatively, a four-wheel drive vehicle including a hydraulic pump interposed between the left-wheel drive shaft and the right-wheel drive shaft, and transmitting a driving force between the two drives by hydraulic pressure generated according to the rotational speed difference between the two drive shafts The present invention relates to a driving force transmission device for use.

<Prior Art> Conventionally, a four-wheel drive vehicle in which a front wheel drive shaft and a rear wheel drive shaft are rigidly connected has been provided. However, in this case, when a difference occurs in the rotation speed of the front wheel and the rear wheel due to a difference in the turning radius between the front wheel and the rear wheel during the turning travel, the propeller shaft is twisted and the turning of the turning is performed. The rear wheel on the inner side is dragged in a state where it has slipped, and there is a drawback that a so-called tight corner braking phenomenon that causes rattling of the vehicle occurs.

In order to solve such difficulties, in the current four-wheel drive vehicle, the propeller shaft allows a rotational speed difference between the front wheel drive shaft and the rear wheel drive shaft, and transmits a torque corresponding to the rotational speed difference. For example, a driving force transmitting device such as a differential pump is provided.

The differential pump is provided with a vane-provided rotor that rotates with one of a pair of drive shafts arranged in series, concentrically with the rotor, and disposed in a cam ring of a casing that rotates with the other. The rotor and the cam ring are connected to each other via a pressure oil interposed between the rotor and the cam ring, and transmit a driving force between the two drive shafts in accordance with a rotational speed difference between the two drive shafts.

By employing this differential pump, it is possible to automatically and optimally distribute the driving force to the front wheels and the rear wheels. That is, when the front wheel drive shaft and the rear wheel drive shaft are rotating at the same rotational speed, the drive force is not transmitted to the rear wheel side, but, for example, the front wheels slip and the rotational speed is transmitted to both drive shafts. When a difference occurs, the driving force corresponding to the difference in the number of rotations is transmitted to the rear wheel side that is not slipping, and the driving force distribution to the rear wheel side is increased. By automatically distributing the driving force in this way, good power transmission to the road surface can always be obtained.

As a further advanced four-wheel drive vehicle, differential pumps are disposed between the left front wheel drive shaft and the right front wheel drive shaft and between the left rear wheel drive shaft and the right rear wheel drive shaft, respectively. Thus, there is provided a vehicle in which the driving force distribution between the left front wheel and the right front wheel and the driving force distribution between the left rear wheel and the right rear wheel are performed. In this four-wheel drive vehicle, the driving force can be transmitted to the four wheels without waste, and more favorable power transmission to the road surface can be obtained.

By the way, in the above-mentioned differential pump, there is provided an orifice with a throttle means in the middle of an oil passage formed between the oil discharge port and the suction port in order to adjust the throttle opening degree of the oil path. It has been proposed (for example, Japanese Patent Application Laid-Open No.
Gazette). According to this differential pump, the pressure generated between the rotor and the casing, i.e., the coupling force between the rotor and the casing, is changed by adjusting the degree of opening of the oil passage by the above-described throttling means. The coupling state between the drive shafts can be set as appropriate from a rigid state to a loose state. Therefore, for example, on a road surface having a low coefficient of friction such as a snowy road or a rough road surface such as a gravel road, a rigid connection is provided between the front wheel and the rear wheel to reliably transmit a driving force necessary for both. As a result, stable running becomes possible. Further, by making a loose connection between the front wheel and the rear wheel at the time of turning, it is possible to more reliably prevent the occurrence of the tight braking phenomenon. Furthermore, when either of the left and right wheels is disengaged, it is possible to easily escape from the disengaged state by rigidly connecting the two wheels. In addition, by adjusting the coupling state between the left and right wheels according to various traveling conditions, such as the traveling speed of the vehicle, the turning speed, and the difference in the road surface condition between the left and right wheels, optimal driving corresponding to the conditions is performed. Power transmission can be performed.

<Problem to be Solved by the Invention> In the driving force transmission device that constitutes the above-described throttling means, since the throttling means is provided on a supporting portion that supports a rotating portion such as a hydraulic pump or a drive shaft, discharge from the hydraulic pump is performed. It is necessary to once guide the discharged high-pressure oil to the support portion side and then return it to the hydraulic pump side again. Therefore, as a result of the high pressure being applied to the seal that seals between the rotating part and the support part, there is a problem that oil leakage easily occurs in the seal part, resulting in poor durability.

The present invention has been made in view of the above problems, and has as its object to provide a driving force transmission device for a four-wheel drive vehicle that can reliably seal a gap between a rotating part and a support part for a long period of time.

<Means for Solving the Problems> To achieve the above object, a four-wheel drive vehicle driving force transmission device according to the present invention includes a front wheel drive shaft and a rear wheel drive shaft, or a left wheel drive shaft and a right wheel drive shaft. A hydraulic pump that transmits driving force between the two drive shafts by a hydraulic pressure generated according to the rotational speed difference between the two drive shafts, and a support that rotatably supports a rotating unit including the hydraulic pump In the driving force transmission device for a four-wheel-drive vehicle, the hydraulic pump includes a suction oil passage connecting one working chamber and a tank, and a discharge oil passage connecting the other working chamber and the tank. And provided
An oil passage that is provided in the middle of the discharge oil passage of the hydraulic pump and that adjusts a throttle opening degree of the oil passage by hydraulic pressure on the rotating unit side and that supplies hydraulic oil to the throttle unit; Is guided to the throttle means through the support portion.

<Operation> According to the driving force transmission device for a four-wheel drive vehicle having the above configuration,
Hydraulic oil is supplied to the throttle means through an oil passage led to the throttle means through the support portion, and the throttle opening of the oil passage is adjusted by operating the throttle means provided in the rotating portion by the oil pressure. be able to.

As described above, according to the driving force transmission device for a four-wheel drive vehicle of the present invention, adjustment of the throttle opening of the discharge oil passage can be performed in the rotating portion, so that the high-pressure oil discharged from the hydraulic pump is supported. There is no need to lead to the department side. Therefore, high pressure is not applied to the seal that seals between the rotating part and the support part.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a driving force transmission device for a four-wheel drive vehicle according to the present invention. In the figure, the driving force transmission device includes a first drive shaft 1 that rotates integrally with a left front wheel drive shaft, and is rotatable relative to the first drive shaft 1, and is integrated with the right front wheel drive shaft. Rotating second drive shaft 2
And a vane pump 3 serving as a hydraulic pump for transmitting torque between the drive shaft 1 and the drive shaft 2, and disposed at an intermediate portion of a discharge oil passage 30 of the vane pump 3, and the oil pressure of the discharge oil passage 30 is reduced by hydraulic pressure. Aperture means 4 for adjusting the degree;
A differential gear device 5 is provided for absorbing a differential rotation between the left front wheel and the right front wheel.

Referring also to FIG. 2, the vane pump 3 includes a rotor 3
1, a cam ring 32 that includes the rotor 31 and forms a plurality of pairs of differential chambers A and B that generate hydraulic pressure with the rotor 31;
A plurality of vanes 34 projecting from the groove 31a on the outer periphery of the rotor 31 and pressed against the inner surface of the cam ring 32 by the coil spring 33;
A check plate V1, V2 interposed between the working chambers A, B and a tank T described later, a side plate 37 sandwiching the cam ring 32 from both sides in the axial direction and forming a pump chamber with the rotor 31;
It consists of 38 etc.

The vane pump 3 is covered by a casing 6, and a gap between the casing 6 and the cam ring 32 is configured as a tank T that stores oil for the vane pump 3. The rotor 31 is connected to the first drive shaft 1.
The cam ring 32 and the side plates 37 and 38 are connected so as to be integrally rotatable by splines.
It is connected to the casing 6 by bolts 39.

At one end of the casing 6, a pressing portion 60 having a substantially L-shaped cross section including a cylindrical portion 60a and a flange portion 60b extending outward from the end of the cylindrical portion 60a is bolted. The first drive shaft 1 is inserted into the inside of the cylindrical portion 60a of the 60. The casing 6 includes bearings 61 and 62
The casing 6 and the vane pump 3 incorporated in the casing 6 are rotatably supported by the support portion 7 through
The differential gear device 5 and the like are configured as a rotating unit R.
The casing 6 and the support 7 are sealed by seals 63, 64 and the like.

As shown in detail in FIG. 4, the throttle means 4 is provided in the vicinity of the inner peripheral portion of the flange portion 60b. And a coil spring 42 constantly biased to the left. The piston 41 includes an annular stepped portion 60c, 37a formed on the inner periphery of the flange portion 60b and the side plate 37,
The piston 41 and the cylinder 41 are slidably fitted in an annular cylinder 43 formed between the piston 41 and the cylinder.
The space 43 is sealed by a seal 44. Also,
An oil hole 41a is formed in a predetermined portion on one end side of the piston 41 in a radial direction.The oil hole 41a is formed in the side while the piston 41 is moved against the urging force of the coil spring 42. Conduction with the discharge oil passage 30 formed in the plate 37 (FIG. 4b)
), The oil discharged from the inside of the vane pump 3 through the discharge oil passage 30 can be guided to the inner periphery of the rotor 31 and finally returned to the tank T.

Further, the cylinder 43 is connected to an oil passage 8 for supplying hydraulic oil. The oil passage 8 includes a through hole 80 formed in the support portion 7, the support portion 7, the casing 6, and the seal.
Space 81 surrounded by 63 and 64, cylindrical part 60a of holding part 60
And a gap 84 between the inner periphery of the cylindrical portion 60a and the first drive shaft 1. The through hole 83 is formed from a hydraulic source such as a power steering pump, a brake pump, an oil pump, or the like. By supplying hydraulic oil to the oil passage 8, the piston 41 can be moved against the urging force of the coil spring. Note that a seal 45 is interposed between the inner periphery of the cylindrical portion 60a and the first drive shaft 1 in order to ensure the tightness of the gap 84.

The operating gear device 5 is a known device that includes a pair of planetary gears 51 and 52 and a pair of differential gears 53 and 54 meshed with the planetary gears 51 and 52. The difference in the number of rotations between the connected second drive shaft 2 and the first drive shaft 1 connected to the differential gear 54 can be absorbed.

FIG. 5 is a hydraulic system diagram. Each working chamber B of the vane pump 3 is communicated with each other via a first oil passage L1.
The first oil passage L1 is guided to the tank T via the above-described check valve V1, and is connected to the check valve V3 and the fixed throttle.
The discharge oil passage formed on the side plate 37 via V5
Communicated with 30. The check valve V1 regulates the oil in the working chamber A from flowing into the tank T, and the check valve V3 regulates the reverse flow of the oil from the throttle means 4 side to the vane pump 3 side.

The other working chambers A are communicated with each other via a second oil passage L2. The second oil passage L2 is guided to the tank T via the above-described check valve V2, The fixed throttle V5 is communicated via a valve V4. The check valve V2 regulates the oil in the working chamber B from flowing into the tank T.
This restricts the reverse flow of oil from the side to the vane pump 3 side.

Next, the operation of the driving force transmission device will be described with reference to FIGS. 2, 3, and 5.

In a state where the discharge oil passage 30 is closed by the throttle means 4, for example, when the left front wheel slips and the first drive shaft 1 rotates faster than the second drive shaft 2, the rotor 31 becomes the cam ring 32. 2, the vane 34 moves in the direction of the working chamber A. In this state, the oil in the vane pump 3 cannot move from the working chamber A to the working chamber B. Therefore, the working chamber A
Is trying to flow into the tank T through the second oil passage L2 and the discharge oil passage 30, but this is blocked by the check valve V2 and the throttle means 4. As a result, high pressure is generated in the working chamber A, and the vane 34 pushes the cam ring 32 through this high pressure, and torque is transmitted from the rotor 31 to the cam ring 32. In other words, the operation of the differential gear device 5 is restricted, torque is transmitted from the left front wheel drive shaft on the slipping side to the right front wheel drive shaft on the non-slip side, and torque is automatically distributed. Grip force on the road surface is ensured.

The above pressure increases as the rotational speed difference between the rotor 31 and the cam ring 32 increases, and a driving force corresponding to the rotational speed difference is transmitted between the two drive shafts. In the working chamber B,
Oil is supplied from the tank T via the opened check valve V1.

The high-pressure oil generated in the working chamber A is supplied to the groove 31a below the vane 34 via a check valve (not shown) so that the vane 34 is pressed against the inner wall of the cam ring 32. The adhesion of the vane 34 is enhanced.

When the right front wheel slips and the right front wheel drive shaft rotates faster than the left front wheel drive shaft, the cam ring 32 rotates clockwise with respect to the rotor 31, as shown in FIG. Thus, a high pressure is generated in the working chamber B, and torque is transmitted from the right front wheel drive shaft to the left front wheel drive shaft via the high pressure. In this case, the check valve V1 is closed and the check valve V2 is open.

On the other hand, when the operating oil is supplied to the throttle means 4 through the oil passage 8, the closed state of the discharge oil passage 30 by the throttle means 4 is released, and the working chamber B is fixed to the first oil passage L1, the check valve V3, It is electrically connected to the tank T via the throttle V5 and the throttle unit 4.
The working chamber A is connected to the tank T via the second oil passage L2, the check valve V4, the fixed throttle V5, and the throttle means 4.
Therefore, when a rotation speed difference occurs between the first drive shaft 1 and the second drive shaft 2, the working chamber A or the working chamber B is
Each is pressurized to a pressure corresponding to the degree of opening of the discharge oil passage 30 set by the fixed throttle V5. This pressure is applied to the throttling means 4
As a result, the operation of restricting the operation of the differential gear device 5 is attenuated because the pressure is lower than the state in which the discharge oil passage 30 is closed. Therefore, by opening and closing the throttle means 4 in accordance with various traveling conditions such as the traveling speed of the vehicle, the turning speed, and the difference in road surface condition between the left and right wheels, the coupling state between the left and right wheels is adjusted, Optimal driving force transmission corresponding to the condition can be performed.

In particular, in the above-described driving force transmission device, since the throttle means 4 is provided on the rotating portion R side, in order to adjust the throttle opening degree of the discharge oil passage 30, the high-pressure oil discharged from the vane pump 3 is supported by the support portion 7. There is no need to lead to Therefore, high pressure is not applied to the seal that seals between the rotating part R and the support part 7.

In addition, as the throttle means 4, a taper 41b may be formed on the outer periphery of the distal end of the piston 41 (see FIG. 6). In this case, the discharge oil is supplied according to the pressure of the hydraulic oil supplied to the throttle means 4. The throttle opening of the road 30 can be continuously variably adjusted. Further, the aperture means 4 can be configured at an arbitrary position on the rotating section R side. Further, other pumps such as a trochoid pump can be used instead of the vane pump 3 as the hydraulic pump.

On the other hand, the present invention can be applied to a driving force transmission device that does not constitute the differential gear device 5 or a driving force transmission device interposed between the front wheel drive shaft and the rear wheel drive shaft. .

<Effect of the Invention> As described above, according to the driving force transmission device of the present invention,
Adjustment of the throttle opening of the discharge oil passage of the hydraulic pump can be performed in the rotating section, so that it is not necessary to guide the high-pressure oil discharged from the hydraulic pump to the support section side, and between the rotating section and the support section. The high pressure is not applied to the seal for sealing the seal. Therefore, it is possible to reliably seal the space between the rotating part and the support part for a long period of time, and to provide a driving force transmission device for a four-wheel drive vehicle with excellent durability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a driving force transmitting device according to the present invention, FIG. 2 and FIG. 3 are schematic sectional views showing the principle of operation of a vane pump, and FIG. FIG. 5 is an enlarged sectional view, FIG. 5 is a hydraulic system diagram, and FIG. 6 is a sectional view of a main part showing another embodiment. DESCRIPTION OF SYMBOLS 1 ... 1st drive shaft, 2 ... 2nd drive shaft, 3 ... vane pump (hydraulic pump) 30 ... discharge oil path, 4 ... throttle means, 7 ... support part, 8 ... oil path,
R: rotating part,

Claims (1)

(57) [Claims] 1. A drive system which is interposed between a front wheel drive shaft and a rear wheel drive shaft, or between a left wheel drive shaft and a right wheel drive shaft, and is provided between the two drive shafts by a hydraulic pressure generated according to a rotational speed difference between the two drive shafts. A four-wheel drive vehicle driving force transmission device comprising: a hydraulic pump that transmits a driving force; and a support portion that rotatably supports a rotating portion including the hydraulic pump. The hydraulic pump includes one working chamber and a tank. And a discharge oil path connecting the other working chamber and the tank are provided independently of each other, and are disposed in the middle of the discharge oil path of the hydraulic pump. Throttle means for adjusting the pressure is provided on the rotating part side, and an oil path for supplying hydraulic oil to the throttle means is guided to the throttle means through a support part. Driving force transmission device.