WO2018173696A1

WO2018173696A1 - Power unit for electric vehicle

Info

Publication number: WO2018173696A1
Application number: PCT/JP2018/008022
Authority: WO
Inventors: 宣人武藤; 利記小久保
Original assignee: 武蔵精密工業株式会社
Priority date: 2017-03-23
Filing date: 2018-03-02
Publication date: 2018-09-27
Also published as: TW201836911A; JP2018159443A

Abstract

A power unit for an electric vehicle, wherein a reduction mechanism (R) comprises a reduction sun gear (51) rotatably driven by a motor (M), a reduction carrier (53) that rotatably supports a first gear (52a) meshing with the reduction sun gear and a second gear (52b) coaxially aligned with the first gear, a first reduction ring gear (54) that is fitted in an open end part (31a) of a motor case (31) and that meshes with the first gear, and a second reduction ring gear (55) that is provided to one end wall part (He) of a hub case (H) and that meshes with the second gear, a bearing (B7) for rotatably supporting the first reduction ring gear (54) on the hub case (H) being interposed between the first reduction ring gear (54) and the hub case (H). It is thereby possible to stably and firmly support the motor-case-side first reduction ring gear on the hub case while ensuring a high reduction ratio in the reduction mechanism for transmitting driving force of the motor to the hub case.

Description

Power unit for electric vehicles

The present invention relates to an electric motor in which a motor and a speed reduction mechanism that decelerates the driving force of the motor and transmits it to the hub case are accommodated side by side in an axial direction in a vehicle, particularly a wheel hub case rotatably supported by a hub shaft. The present invention relates to a vehicle power unit.

In the present invention and this specification, “axial direction” and “radial direction” refer to an axial direction and a radial direction based on the hub axis, respectively.

As the power unit for the electric vehicle, a speed reduction mechanism portion including a planetary gear mechanism is provided. A speed reduction sun gear that is rotationally driven by a motor, a speed reduction carrier that rotatably supports a speed reduction planetary gear meshing with the speed reduction sun gear, and a bottomed cylindrical shape And a reduction ring gear that is fixed to the open end of the motor case (first case member 32) and meshes with the reduction planetary gear, and the closed end of the motor case is fixed to and supported by the hub axle. (For example, refer to Patent Document 1 below).

Japanese Patent No. 5300830

By the way, in the above conventional structure, the reduction ring gear is fixed to the free end portion (that is, the open end portion) of the motor case that is separated in the axial direction from the support point (that is, the closed end portion) to the hub shaft. Thus, the reduction ring gear is supported in a cantilever manner. Therefore, the reduction ring gear is likely to vibrate due to the rotational vibration of the motor, and the vibration may cause problems such as poor contact of the meshing portion between the reduction ring gear and the reduction planetary gear, uneven wear, and noise generation due to meshing. there were.

The present invention has been made in view of such circumstances, and for an electric vehicle capable of solving the above-mentioned problem by ensuring that the reduction ring gear can be stably and firmly supported on the hub case while ensuring a high reduction ratio in the reduction mechanism. An object is to provide a power unit.

In order to achieve the above object, according to the present invention, one end wall portion and the other end wall portion of a hub case of a wheel are rotatably supported by a hub shaft, and a motor and a driving force of the motor are provided to the hub case. A speed reduction mechanism that decelerates and transmits to the hub case is housed side by side in the axial direction, and the motor has a bottomed cylindrical motor case that is open at one end and faces the one end wall of the hub case. In addition, the other end portion which becomes the bottom wall of the motor case is a power unit for an electric vehicle fixed and supported on the hub shaft, and the speed reduction mechanism portion includes a speed reduction sun gear which is rotationally driven by the motor, A first gear that meshes with the reduction sun gear, a speed reduction carrier that rotatably supports a second gear arranged coaxially with the first gear, and meshed with the first gear by being fitted to the one end portion of the motor case A first reduction ring gear, and a second reduction ring gear provided on the hub case and meshing with the second gear, and the first reduction ring gear is disposed between the first reduction ring gear and the hub case. A first feature is that a bearing that is rotatably supported by the actuator is interposed.

According to the second aspect of the invention, in addition to the first feature, the two side walls of the speed reduction carrier that sandwich the first and second gears in the axial direction are rotatably supported by the hub shaft. Features.

Further, according to the present invention, in addition to the first or second feature, the first reduction ring gear integrally has a ring gear extending portion extending in the axial direction from the one end portion of the motor case to the outside of the motor case. The third feature is that the outer peripheral surface or inner peripheral surface of the extending portion is the mounting surface of the bearing on the first reduction ring gear side.

According to the first feature of the present invention, the planetary gear of the speed reduction mechanism portion formed by the planetary gear mechanism has the coaxial first and second gears, and the first reduction ring gear meshing with the first gear has a bottomed cylindrical shape. A second reduction ring gear that fits to one end (open end) of the motor case and meshes with the second gear is provided in the hub case, and the first reduction ring gear rotates to the hub case between the first reduction ring gear and the hub case. Since the bearing to be freely supported is interposed, the support rigidity of the first and second reduction ring gears can be increased while ensuring a high reduction ratio in the reduction mechanism.

In particular, the first reduction ring gear is fixed to the free end (one end) of the motor case and is in a cantilevered form with respect to the hub shaft. The first reduction ring gear is connected to the hub case via a bearing. Since the first reduction ring gear is substantially supported by both ends, the support is stable and effective in preventing shaft misalignment. As a result, even if the rotational vibration of the motor is directly transmitted to the first reduction ring gear, the vibration of the first reduction ring gear can be effectively suppressed. Therefore, the contact of the meshing portion between the first reduction ring gear and the reduction planetary gear is good. Thus, the durability can be enhanced and the generation of noise from the meshing portion can be reduced.

In particular, according to the second feature, both side wall portions of the speed reduction carrier sandwiching the first and second gears in the axial direction are rotatably supported on the hub shaft, so that the open end portion (one end of the motor case) Part) is supported on the hub case side through the first reduction ring gear and the bearing, and the reduction carrier can be supported at both ends with a long support span in the axial direction by utilizing the space generated around the hub shaft. . As a result, the speed reduction carrier can be stably supported while reducing the size of the power unit.

In particular, according to the third feature, the first reduction ring gear integrally has a ring gear extending portion extending axially out of the motor case from one end portion of the motor case. Since the outer peripheral surface or inner peripheral surface is the mounting surface on the first reduction ring gear side of the bearing, it is possible to easily secure the bearing diameter without specially increasing the motor case diameter, and further reducing the size of the power unit It can contribute to the conversion.

FIG. 1 is an overall longitudinal sectional view of a power unit for a battery-assisted bicycle according to a first embodiment of the present invention. (First embodiment) FIG. 2 is an enlarged view taken along the arrow 2 in FIG. (First embodiment) 3 is an enlarged view taken along the line 3 in FIG. 1 (a cross-sectional view taken along line 3-3 in FIG. 4). (First embodiment) 4 shows the locked state of the transmission sun gear with respect to the hub shaft. FIG. 4 (A) is a sectional view taken along line 4A-4A in FIG. 3, and FIG. 4 (B) is a sectional view taken along line 4B-4B in FIG. It is. (First embodiment) 5A and 5B show the unlocked state of the transmission sun gear with respect to the hub shaft. FIG. 5A is a diagram corresponding to FIG. 4A, and FIG. 5B is a diagram corresponding to FIG. It is. (First embodiment) FIG. 6 is a view corresponding to FIG. 2 showing a second embodiment of the present invention. (Second Embodiment) FIG. 7 is a view corresponding to FIGS. 2 and 6 showing a third embodiment of the present invention. (Third embodiment)

B7... First reduction ring gear support bearing (bearing)
H: Hub case He ... End wall member (one end wall)
Hmb ... end wall (other end wall)
M... Motor R... Deceleration mechanism part s1, s2 .. First and second side wall parts (side wall parts)
U: Power unit for battery-assisted bicycles (Power unit for electric vehicles)
11 .... hub shaft 31a ... one end 31 ... motor case 31b ... end wall (other end)
··· Deceleration sun gears 52a, 52b ··· First and second gears 53 ··· Reduction carrier 54 ··· First

reduction ring gears

54a, 54a ', 54a "· · Ring gear extension 55 ·· ..Second reduction ring gear

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First embodiment

First, a first embodiment of an electric vehicle power unit according to the present invention will be described with reference to FIGS.

An electric assist bicycle power unit U, which is an example of an electric vehicle power unit, includes a single hub shaft 11 that functions as a wheel of an electric bicycle, for example, a rear wheel axle, and a hub shaft that functions as a hub portion of a rear wheel. 11, a hub case H that is rotatably supported by the motor 11, a transmission mechanism T that is housed in the hub case H and that transmits a pedaling force input from a pedal to the hub case H so as to be capable of shifting, and the transmission mechanism T in the hub case H And a motor drive system MD that is adjacently disposed in the axial direction and can drive the hub case H electrically.

In the present embodiment, the hub shaft 11 is formed as an integral shaft by forging or machining. Although not shown, both end portions of the hub shaft 11 are inserted and supported by the left and right rear forks, and are coupled and fixed by fastening means such as nuts, as in a conventionally known electric bicycle.

The hub case H has a bottomed cylindrical hub case body Hm having one end opened and an end wall Hmb integrally formed at the other end, and an annular end detachably coupled to the opened one end Hme of the hub case body Hm. A wall member He.

In this embodiment, the end wall member He has a first end so as to surround the first end wall member half He1 and the first end wall member half He1, for example. The second end wall member half body He <b> 2 is fitted and fixed to the outer peripheral portion of the wall member half body He <b> 1. The outer peripheral portion of the second end wall member half body He2 is inlay-fitted to one end portion Hme of the hub case main body Hm. The first and second end wall member halves He1 and He2 may be coupled to each other by an appropriate coupling means, for example, press fitting, welding, screwing, or the like, or may be integrally formed.

In this embodiment, the coupling means of the end wall member He to the hub case main body Hm penetrates the end wall member He (more specifically, the second end wall member half body He2), and the outer periphery of the one end Hme of the hub case main body Hm. Although constituted by a plurality of bolts 14 screwed into the boss portion, other suitable coupling means such as press-fitting can also be adopted. A rear wheel spoke (not shown) is fixed to the outer periphery of the hub case body Hm.

The end wall Hmb of the hub case H is rotatably supported by the hub shaft 11 via the hub supporting first bearing B1 and the end wall member He via the hub supporting second bearing B2. *

The support structure will be described more specifically. A hub support ring 15r that holds the hub support first bearing B1 between the inner periphery of the end wall portion Hmb and the hub shaft 11 is supported via a support nut 15n. Is done. The support nut 15n fits and supports the inner peripheral portion of the hub support ring 15r. The support nut 15n is screwed to the hub shaft 11, and the screwed position is fixed by the lock nut 16. Thus, in the assembly process in which the end wall Hmb is supported on the hub shaft 11 via the hub support first bearing B1 and the hub support ring 15r, the preload on the hub support first bearing B1 can be adjusted by the support nut 15n. It is.

Further, the hub shaft 11 has a transmission carrier of the transmission mechanism T that holds the hub supporting second bearing B2 between the inner periphery of the end wall member He (more specifically, the first end wall member half body He1). 22 is rotatably supported via a carrier support bearing B3 as will be described later.

The hub supporting first and second bearings B1 and B2 are arranged on the radially inner side of the outer diameter of the motor drive system MD (and therefore the motor M) when viewed in a projection plane orthogonal to the hub shaft 11. The

Next, an example of the transmission mechanism T will be described. The transmission mechanism T includes a driven sprocket 21 as an input member to which a pedaling force from a pedal is input, a transmission carrier 22 that is coupled to the driven sprocket 21 so as to rotate integrally with the driven sprocket 21, and can rotate on the hub shaft 11. The transmission sun gear 23 is rotatably fitted and supported on the outer periphery of the motor 11, and is interposed between the transmission sun gear 23 and the hub shaft 11 so that the transmission sun gear 23 can be switched between a fixed state and a rotatable state on the hub shaft 11. A shift mechanism S as switching means, a plurality of transmission planetary gears 24 rotatably supported on the transmission carrier 22 and meshing with the transmission sun gear 23, a transmission ring gear 25 meshing with the transmission planetary gear 24, and a hub of the transmission sun gear 23 In the fixed state with respect to the shaft 11, the pedal force input to the speed change carrier 22 is transferred to the hub case via the speed change planetary gear 24 and the speed change ring gear 25. Is transmitted to the end wall member He, also in the rotatable state and a one-way transmission mechanism OT for transmitting to the end wall member He without via the transmission planetary gear 24 to the pedal force.

The pedal treading force is transmitted as a rotational force to the driven sprocket 21 through a chain transmission mechanism including the driven sprocket 21, and the rotational force is transmitted to the transmission carrier 22 and further transmitted to the hub case H through the transmission mechanism T. To drive the rear wheels.

In this embodiment, the transmission carrier 22 is divided into, for example, a cylindrical first carrier half body 22A and a disk-shaped second carrier half body 22B in order to facilitate manufacturing. One end 22Aa of the first carrier half 22A integrally has a carrier shaft support wall that supports both ends of the carrier shaft 27, whereby the one end 22Aa is connected to the carrier shaft 27 and the variable planetary gear 24. And supported by the hub shaft 11 via the transmission sun gear 23. On the other hand, between the inner periphery of the other end 22Ab of the first carrier half body 22A and the outer periphery of the stopper ring 17 that is non-rotatably fitted (for example, press-fitted) to the outer periphery of the hub shaft 11, the carrier support bearing B3. Thus, the other end 22Ab is rotatably supported by the hub shaft 11 via the carrier supporting bearing B3.

Further, the inner peripheral portion of the second carrier half body 22B is fitted and fixed to the outer periphery of the intermediate portion in the axial direction of the first carrier half body 22A by press-fitting. Furthermore, each inner peripheral portion of the driven sprocket 21 adjacent to the second carrier half 22B is spline fitted to the outer periphery of the first carrier half 22A, and is fixed by a washer 28 and a retaining ring 29.

In addition, instead of the retaining ring 29, other suitable fixing means, for example, a nut, may be used as the fixing means for the driven sprocket 21. In addition, the first and second carrier halves 22A and 22B may be coupled to each other by other suitable coupling means such as welding, screwing, bonding, or the like, or may be integrally formed.

A cylindrical carrier extension 22Ba extending toward the motor M is integrally formed on the axial inner side surface of the outer peripheral portion of the second carrier half 22B, and the carrier extension 22Ba is more than the transmission ring gear 25. It is formed in a large diameter cylindrical shape. Between the outer peripheral surface of the carrier extension portion 22Ba and the opposed peripheral surface between the inner periphery of the end wall member He (more specifically, the second end wall member half body He2), the above-described second bearing for hub support is provided. B2 is interposed.

The transmission ring gear 25 is integrally formed with a ring gear main body portion 25m having an inner tooth 25mg that meshes with the transmission planetary gear 24, and a ring gear extending portion 25a extending from the ring gear main body portion 25m in the opposite direction to the motor drive system MD in the axial direction. The ring gear extension 25a is concentrically surrounded by the carrier extension 22Ba. Between the inner circumference of the ring gear extension 25a and the outer circumference of the transmission carrier 22 (more specifically, the one end 22Aa of the first carrier half 22A), a transmission ring gear support bearing B4 is interposed. .

Next, an example of the one-way transmission mechanism OT will be described. The one-way transmission mechanism OT is provided between the transmission ring gear 25 and the end wall member He, and can transmit power from the transmission ring gear 25 only to the end wall member He side, and the first one-way clutch C1. Is provided between the speed change carrier 22 and the speed change ring gear 25 at a position shifted in the axial direction, and includes a second one-way clutch C2 capable of transmitting power only from the speed change carrier 22 to the speed change ring gear 25.

In particular, in the present embodiment, the first one-way clutch C1 is interposed between the opposed peripheral surfaces of the outer periphery of the ring gear main body portion 25m and the inner peripheral boss portion 63 of the first end wall member half body He1, and the second one-way clutch. C2 is interposed between opposing peripheral surfaces of the inner periphery of the carrier extension portion 22Ba and the outer periphery of the ring gear extension portion 25a.

Thus, at least a part (most part in the present embodiment) of the second one-way clutch C2 and at least a part (all in the present embodiment) of the transmission ring gear support bearing B4 are in the same position in the axial direction. That is, the arrangement is overlapped in the radial direction. Further, at least a part (all in this embodiment) of the second one-way clutch C2 and at least a part (most part in the present embodiment) of the second hub supporting bearing B2 are in the same position in the axial direction, that is, the diameter. It is an arrangement that overlaps in the direction.

The first and second one-way clutches C1 and C2 have the same structure as a conventionally well-known one-way clutch structure, and although not shown, for example, any one of the opposing circumferential surfaces of the inner race and the outer race A plurality of engagement grooves provided at intervals on one peripheral surface, and an engaging member (for example, a ratchet claw) that is pivotally supported on one of the other peripheral surfaces so as to be able to engage with and disengage from the engagement groove. And a spring that repels each engaging element in a locking direction with the engaging groove. The inner race and the outer race may be separated from the members provided with the first and second one-way clutches C1 and C2, may be retrofitted, or may be formed integrally.

In this embodiment, the outer peripheral surfaces of the ring gear main body portion 25m and the ring gear extending portion 25a, which are the attachment surfaces of the first and second one-way clutches C1 and C2 in the transmission ring gear 25, have the same diameter. In addition, the inner peripheral surface of the inner peripheral boss 63 of the first end wall member half body He1 serving as the mounting surface of the first one-way clutch C1 in the end wall member He and the mounting surface of the second one-way clutch C2 in the transmission carrier 22 are provided. The inner peripheral surface of the carrier extension 22Ba has the same diameter. Accordingly, the first and second one-way clutches C1 and C2 can use parts having the same specifications, and cost savings can be achieved by sharing parts. However, since the power transmission directions of the first and second one-way clutches C1 and C2 are opposite to each other, the circumferential direction of the engagement element and the engagement groove in the first one-way clutch C1 is the same as that of the second one-way clutch C2. They are set in opposite directions.

Next, an example of the shift mechanism S will be described mainly with reference to FIGS.

The shift mechanism S includes a plurality of ratchet grooves 23 a that are recessed in the circumferential direction on the inner circumferential surface of the transmission sun gear 23, and a plurality that are recessed in the circumferential direction on the outer circumferential surface of the hub shaft 11. A claw storage hole 11a, a ratchet claw 41 which is fitted and supported so as to be able to swing up and down in the claw storage hole 11a, and by which the claw tip portion 41as of the claw body 41a can be engaged and disengaged with the ratchet groove 23a, and a ratchet The claw 41 is fitted in the outer periphery of the hub shaft 11 in an elastically contracted state and pressed against the outer periphery of the intermediate portion 41m of the ratchet claw 41 so as to constantly urge the claw 41 in the engagement direction with the ratchet groove 23a (that is, the standing direction of the ratchet claw 41). The ring spring 42 and a recess 431i in which the tip portion 41bs of the base end portion 41b of the ratchet pawl 41 can protrude and retract are provided on the inner peripheral surface and can be rotated between a predetermined lock position and an unlock position. Then, the operation drum 43 fitted and supported on the outer periphery of the hub shaft 11 and the movable end 44a is provided on the operation drum 43 so as to urge the operation drum 43 to the unlock position (namely, the position of FIG. 5B). A return spring 44 made of a torsion spring to be locked, a spring receiving ring 45 fitted to the outer periphery of the hub shaft 11 so as not to be relatively rotatable (for example, press-fitted) to lock the fixed end 44b of the return spring 44, and an operation drum 43 and a fixing ring 46 for retaining the operation drum, which is disposed adjacent to the outer end of 43 and fitted into the outer periphery of the hub shaft 11 so as not to be relatively rotatable (for example, press-fitted).

The operation drum 43 is divided into first and second drum halves 431 and 432 that are connected to each other so as not to rotate relative to each other (for example, meshing and coupling). From the outer end of the second drum half 432, a plurality of operating rod portions 432t arranged at intervals in the circumferential direction of the operating drum 43 are integrally extended outward in the axial direction. Each operation lever 432t protrudes outwardly from the speed change carrier 22 through the insertion grooves formed in the inner peripheral surfaces of the fixing ring 46 and the stopper ring 17 respectively. The operation lever 432t can rotate the operation drum 43 between a lock position and an unlock position by an operation unit CU described later.

Thus, when the operation drum 43 is held at the unlock position shown in FIG. 5B, the claw body 41a of the ratchet claw 41 interlocked with the operation drum 43 resists the urging force of the ring spring 42. Thus, it is placed in a state of being detached from the ratchet groove 23a (ie, stored in the claw storage hole 11a). As a result, the transmission sun gear 23 becomes rotatable with respect to the hub shaft 11, and the transmission planetary gear 24 is free to rotate as well as the transmission sun gear 23. Therefore, the rotation of the speed change carrier 22 in response to the pedaling force is directly transmitted to the end wall member He and thus to the hub case H via the second one-way clutch C2, the speed change ring gear 25, and the first one-way clutch C1 (that is, not via the speed change planetary gear 24). Communicated. Thus, the first speed is established in the transmission mechanism T.

On the other hand, when the operation drum 43 is held at the lock position shown in FIG. 4B against the return spring 44, the ratchet pawl 41 released from the operation drum 43 is based on the biasing force of the ring spring 42. Since the state is switched to the latched state in the ratchet groove 23a, the transmission sun gear 23 is connected to the hub shaft 11, that is, in a fixed state and cannot be rotated. As a result, the speed change planetary gear 24 meshed with the speed change sun gear 23 revolves around the speed change carrier shaft 27 while revolving around the hub shaft 11 as the speed change carrier 22 rotates, so that the speed change planet 22 rotates. The speed is increased at 24 and transmitted to the transmission ring gear 25, and the increased rotation of the transmission ring gear 25 is transmitted to the end wall member He and thus to the hub case H via the second one-way clutch C <b> 2. Thus, the second speed increased from the first speed in the transmission mechanism T is established.

Incidentally, a unit case CUc of an operation unit CU for switching the shift mechanism S is fixed to the outer periphery of the hub shaft 11 by a nut 18 at a position adjacent to the outer side in the axial direction of the transmission carrier 22. In the unit case CUc, an operation plate 71 that can engage with the operation lever portion 432t of the shift mechanism S and can rotate the operation drum 43 is accommodated and supported in a rotatable manner.

The operation plate 71 is connected to an operation lever 72 that protrudes outside the unit case CUc and can rotate the operation plate 71. The operation lever 72 can be remotely operated from the outside. Therefore, the occupant can operate the operation unit CU by hand operation, and by selectively switching the operation drum 43 of the shift mechanism S to either the lock position or the unlock position based on the operation input, the first operation described above is performed. The speed change operation between the second speed and the second speed can be arbitrarily performed.

Next, an example of the motor drive system MD will be described. The motor drive system MD includes an electric motor M and a speed reduction mechanism R that decelerates the driving force of the motor M and transmits it to the end wall member He of the hub case H.

The motor M includes, for example, a bottomed cylindrical motor case 31 that is open at one end 31 a and faces the end wall member He, a stator 32 that is fixed to the inner peripheral surface of the body portion of the motor case 31, and the radial direction of the stator 32. A rotor 33 with a permanent magnet disposed on the inner side and a cylindrical motor shaft 34 for fixing the rotor 33 to the outer peripheral portion are provided. The motor shaft 34 is rotatably fitted and supported on the outer periphery of the hub shaft 11 via a pair of motor shaft support first and second bearings B5 and B5 '.

A boss-like inner peripheral portion of the end wall portion 31b that becomes the bottom wall of the motor case 31 is fitted and fixed to the outer periphery of a boss member 35 that is fitted and fixed to the outer periphery of the hub shaft 11 (press-fit in this embodiment), for example. (In this embodiment, spline press-fitting). Note that the inner peripheral portion of the end wall portion 31b may be fixed to the outer periphery of the hub shaft 11 by a fixing means (for example, combined use of a spline and a retaining ring, screwing or the like) different from the present embodiment.

Further, on the outer surface of the end wall portion 31b of the motor case 31, an electronic control unit ECU for controlling energization to the motor M (more specifically, the coil portion of the stator 32) is attached. The wiring extending from the electronic control unit ECU is drawn out through the through hole of the hub support ring 15r. Note that the wiring is connected to a pedaling force detection means, an in-vehicle battery or the like (not shown).

Next, an example of the deceleration mechanism R will be described. The reduction mechanism R integrally couples a reduction sun gear 51 that is rotationally driven by the motor M, a first gear 52a that meshes with the reduction sun gear 51, and a second gear 52b that is arranged coaxially with the first gear 52a. A plurality of reduction planetary gears 52, a reduction carrier 53 that rotatably supports the reduction planetary gear 52, and a first reduction ring gear 54 that is fitted to one end 31a of the motor case 31 and meshes with the first gear 52a. And a second reduction ring gear 55 that meshes with the second gear 52b.

The reduction sun gear 51 is press-fitted and fixed to the outer periphery of the hub shaft 11 adjacent to a reduction carrier supporting first bearing B6 described later. In addition, as a fixing means of the reduction sun gear 51, a fixing means different from the present embodiment, for example, welding, caulking, adhesion, spline fitting, and a combined use of a retaining ring may be employed.

The reduction carrier 53 includes a reduction carrier shaft 56 that rotatably penetrates and supports each reduction planetary gear 52, a first carrier half 53a having a first side wall portion s1 that fixes one end of the reduction carrier shaft 56, and A second carrier half 53b having a second side wall portion s2 that sandwiches the reduction planetary gear 52 between the first side wall portion s1 and fixes the other end portion of the reduction carrier shaft 56; The first carrier half 53a integrally has a plurality of connecting arm portions 53au, and the tip of the connecting arm portion 53au is fixed to the second carrier half 53b.

The first side wall portion s1 is connected to the motor shaft 34 (and thus via the motor shaft 34) via the first carrier B6 for speed reduction carrier support interposed between the inner periphery of the first carrier half 53a and the opposed peripheral surface of the motor shaft 34. The hub shaft 11) is rotatably supported. On the other hand, the second side wall portion s2 is rotatable on the hub shaft 11 via the second carrier B6 ′ for supporting the speed reduction carrier interposed between the inner periphery of the second carrier half 53b and the opposed peripheral surface of the hub shaft 11. Supported. On the outer periphery of the hub shaft 11, a fixing ring 57 for engaging the inner race of the second bearing B 6 ′ for supporting the deceleration carrier and holding the second bearing B 6 ′ (and hence the deceleration carrier 53) on the hub shaft 11. Is inserted (for example, press-fitted).

The first reduction ring gear 54 is integrally formed with a ring gear main body portion 54m having an inner tooth 54mg that meshes with the first gear 52a and a ring gear extension portion 54a that extends from the ring gear main body portion 54m to the outside of the motor case 31 in the axial direction. Have.

By the way, on the inner side surface in the axial direction of the end wall member He, particularly the second end wall member half body He2, there is a cylindrical outer extending portion 61 that extends inward in the axial direction and fits into the inner periphery of the hub case body Hm. A cylindrical shape projecting integrally and extending inward in the axial direction and concentrically surrounded by an outer extending portion 61 on the inner peripheral portion of the inner end surface in the axial direction of the second end wall member half body He <b> 2. The inner extending portion 62 is integrally projected. The ring gear extension 54 a of the first reduction ring gear 54 enters an annular gap defined between the outer extension 61 and the inner extension 62.

Further, between the inner periphery of the ring gear extension 54a and the outer periphery of the inner extension 62, the first reduction ring gear 54 is rotated via the hub case H (more specifically, the second end wall member half body He2). A first reduction ring gear support bearing B7 to be freely supported is interposed. Accordingly, the inner peripheral surface of the ring gear extending portion 54a becomes the mounting surface on the first reduction ring gear 54 side of the bearing B7.

Thus, when the rotation of the reduction sun gear 51 driven by the motor M is transmitted to the first gear 52 a of the reduction planetary gear 52, the first reduction ring gear 54 is fixed to the motor case 31. The reduction planetary gear 52 supported so as to rotate freely rotates around the reduction carrier shaft 56 while revolving around the hub shaft 11. Then, the revolution and rotation of the reduction planetary gear 52 are transmitted from the second gear 52b to the second reduction ring gear 55, so that the rotation of the drive electric motor 4 is transmitted to the hub case H at a high reduction ratio, as will be described later. It becomes possible.

Next, the operation of the first embodiment will be described. During the travel of the battery-assisted bicycle, the pedaling force of the pedal by the occupant is shifted in two stages (first speed or second speed) via the speed change mechanism T and transmitted to the end wall member He and thus the hub case H.

For example, when the operation drum 43 of the shift mechanism S is in the unlocked position and the connection between the transmission sun gear 23 and the hub shaft 11 is released, the rotation of the transmission carrier 22 is rotated by the second one-way clutch C2, the transmission ring gear. 25, directly transmitted to the end wall member He via the first one-way clutch C1. As a result, the hub case H that is a part of the rear wheel rotates at the same rotational speed as that of the transmission carrier 22.

On the other hand, when the operation drum 43 of the shift mechanism S is in the locked position and the transmission sun gear 23 is fixed to the hub axle 11, the rotation of the transmission carrier 22 is increased through the transmission planetary gear 24 and the transmission ring gear 25. And transmitted to the end wall member He. As a result, the hub case H rotates at an increased speed relative to the rotation of the transmission carrier 22.

The second one-way clutch C2 is interposed between the transmission carrier 22 and the transmission ring gear 25, and the first one-way clutch C1 is interposed between the transmission ring gear 25 and the end wall member He. Even when the pedal rotation is slow and the hub case H is fast, the rotation of the hub case H is not transmitted to the pedal side.

Further, when the rear wheel driving load increase is detected by a load detection means (not shown) while the battery-assisted bicycle is traveling, the motor M is energized from the electronic control unit ECU, and the rotation of the motor shaft 34 causes the speed reduction mechanism R to be After that, it is sufficiently decelerated and transmitted to the end wall member He and therefore to the hub case H. As a result, insufficient pedaling force is assisted by the driving force of the motor M, so that it is possible to travel without difficulty even on an uphill.

In the transmission mechanism T of the present embodiment, the first one-way clutch C1 interposed between the end wall member He and the transmission ring gear 25, and the second one-way clutch C2 interposed between the transmission ring gear 25 and the transmission carrier 22; Are arranged in series on the transmission ring gear 25 (more specifically, the outer peripheral surfaces of the transmission ring gear main body 25m and the ring gear extension 25a) at positions shifted in the axial direction, and further between the transmission carrier 22 and the end wall member He. The second bearing B2 for supporting the hub interposed between the second one-way clutch C2 and the second one-way clutch C2 is positioned so as to be in the same position in the axial direction (that is, overlaps in the radial direction) with the majority of the second one-way clutch C2. Surrounding arrangement. As a result, the transmission mechanism T is reduced in the axial direction compared to the conventional structure in which the first and second one-way clutches C1 and C2 and the hub supporting second bearing B2 are arranged in the axial direction. Miniaturization of the power unit U is achieved.

The first and second one-way clutches C1 and C2 are arranged in series on the transmission ring gear 25 as described above, while one end wall portion of the hub case H, that is, the end wall member He is provided from the motor drive system MD. A driven portion to which power is input (more specifically, the inner extending portion 62 of the second end wall member half body He2) is provided. As a result, the driven portion from which the end wall member He receives power includes the driven portion from the motor drive system MD (the inner extending portion 62 of the second end wall member half body He2) and the driven portion from the first one-way clutch C1. There is only (the inner peripheral boss portion 63 of the first end wall member half body He1), so that the end wall member He can be reduced in size and structure, and the power unit U can be further reduced in size.

The transmission ring gear 25 includes a ring gear main body portion 25m having an inner tooth 25mg meshing with the transmission planetary gear 24, and a ring gear extending portion 25a extending axially outward from the ring gear main body portion 25m. The clutch C2 is interposed between the outer periphery of the ring gear extension 25a and the inner periphery of the carrier extension 22Ba. As a result, even if the total axial width of the first and second one-way clutches C1 and C2 is longer than the tooth width of the transmission planetary gear 24, both the clutches C1 and C2 are axially adjacent to each other, and the transmission ring gear 25 Can be placed in series without difficulty.

Further, a transmission ring gear support bearing B4 is interposed between the inner periphery of the ring gear extension 25a and the opposed peripheral surface of the transmission carrier 22, and this transmission ring gear support bearing B4 is a large one of the second one-way clutch C2. Arranged in the same position in the axial direction as the part. As a result, the transmission ring gear 25 is stably supported on the transmission carrier 22 via the transmission ring gear support bearing B4 even if the transmission ring gear 25 becomes longer in the axial direction due to the series arrangement of the first and second one-way clutches C1 and C2. Therefore, the tooth contact with the speed change planetary gear 24 is good, and the speed change planetary gear 24 can rotate smoothly and quietly. Moreover, since the transmission ring gear support bearing B4 partially overlaps the ring gear extension 25a in the radial direction, the axial extension of the bearing B4 is suppressed, so that the power unit U can be downsized in the axial direction. It is done.

In the speed reduction mechanism R of the present embodiment, the reduction planetary gear 52 has first and

second gears

52a and 52b arranged coaxially, and the first reduction ring gear 54 meshed with the first gear 52a is a bottomed cylinder. The second reduction ring gear 55 fitted to the one end 31a of the motor case 31 and meshed with the second gear 52b is connected to the end wall member He (more specifically, the inner extension of the second end wall member half He2). 62, and a first reduction ring gear support bearing B7 is provided between the first reduction ring gear 54 and the end wall member He (more specifically, the outer periphery of the inner extension 62). Intervened. As a result, the speed reduction mechanism R has sufficient support rigidity of the first and second speed reduction ring gears 54 and 55 for securing the speed reduction ratio while ensuring a high speed reduction ratio by utilizing the end wall member He. It can be secured.

In particular, the first reduction ring gear 54 is fixed to one end 31 a of the motor case 31, that is, a free end (open end), and is in a cantilevered form with respect to the hub shaft 11. The ring gear extension 54a of the reduction ring gear 54 is supported by the end wall member He via the first reduction ring gear support bearing B7, so that the first reduction ring gear 54 is supported in a substantially doubly supported form. Is stable and effective in preventing shaft misalignment. Therefore, even if the rotational vibration of the motor M is directly transmitted to the first reduction ring gear 54, the vibration of the first reduction ring gear 54 can be suppressed as much as possible. Therefore, the first reduction ring gear 54 and the reduction planetary gear 52 (more specifically, the first reduction ring gear 54). It is possible to improve the durability by making the contact of the meshing portion with the 1 gear 52a) good, and to reduce the generation of noise from the meshing portion.

Further, as described above, the one end portion 31a of the motor case 31 is supported on the hub case H side via the first reduction ring gear 54 and the first reduction ring gear support bearing B7. It is not necessary to support the 31a side, and accordingly, there is a space around the hub shaft 11. In this embodiment, by using this space, both side walls s1, s2 (first and

second carrier halves

53a, 53b) of the speed reduction carrier 53 are connected to the speed reduction carrier supporting first and second bearings B6, B6. Since it is supported on the hub axle 11 via B6 ', the deceleration carrier 53 that is wide in the axial direction can be supported at both ends with a long support span in the axial direction. Thereby, the stable support of the deceleration carrier 53 is achieved, aiming at size reduction of the power unit U.

Further, the first reduction ring gear 54 of the present embodiment integrally has a ring gear extension 54a that extends in the axial direction from the one end 31a of the motor case 31 to the outside of the motor case 31, and this ring gear extension 54a. Since the peripheral surface is the mounting surface of the first reduction ring gear support bearing B7, a sufficient bearing diameter can be secured without specially increasing the diameter of the motor case 31 itself.

Second embodiment

Next, a second embodiment of the present invention will be described based on FIG. In the second embodiment, the first reduction ring gear support bearing B7 includes the outer periphery of the ring gear extension 54a 'of the first reduction ring gear 54 and the inner periphery of the outer extension 61' of the second end wall member half body He2. In the first embodiment, only the outer peripheral surface of the ring gear extension 54a 'and the inner peripheral surface of the outer extension 61' serve as the mounting surface of the first reduction ring gear support bearing B7. It differs from the form.

Since the other configuration of the power assisted bicycle power unit U of the second embodiment is the same as that of the power unit U of the first embodiment, each component in FIG. 6 corresponds to the corresponding component of the first embodiment. Only the same reference numerals are attached, and further description of the structure is omitted. Thus, also in the second embodiment, the same effect as the first embodiment can be expected.

Third embodiment

Next, a third embodiment of the present invention will be described based on FIG. In the first and second embodiments, an annular gap is defined between the opposed peripheral surfaces of the outer extending

portions

61 and 61 ′ and the inner extending

portions

62 and 62 ′ that protrude from the inner side surface in the axial direction of the end wall member He. The ring

gear extension portions

54a and 54a 'of the first reduction ring gear 54 are inserted into the annular gap, and the circumferential surfaces of the ring

gear extension portions

54a and 54a' facing the annular gap are provided with the first reduction ring gear support bearing B7. The mounting surface.

On the other hand, in the third embodiment, an inner extending portion 62 ″ is integrally connected to the inner peripheral side of the outer extending portion 61 ″ projecting on the inner side surface in the axial direction of the end wall member He to extend the inner side. The rigidity of the portion 62 ″ (and hence the second reduction ring gear 55) is increased, and the extension end of the ring gear extension 54a ″ of the first reduction ring gear 54 is opposed to the extension end of the inner extension 62 ″. is doing.

Other configurations of the power unit U for the battery-assisted bicycle according to the third embodiment are the same as those of the power unit U according to the second embodiment. Therefore, in FIG. 7, each component is a corresponding component of the second embodiment. Only the same reference numerals are attached, and further description of the structure is omitted. Thus, also in the third embodiment, the same operational effects as those in the first and second embodiments can be expected.

The first to third embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, the power unit U is disposed on the rear wheel, but this can also be disposed on the front wheel.

In the above-described embodiment, the vehicle on which the power unit U is mounted is described as a battery-assisted bicycle. However, the power unit of the present invention can also be applied to a stepping-type battery-assisted three-wheeled vehicle.

In the above embodiment, the vehicle equipped with the power unit U is an electrically assisted vehicle (that is, an electrically assisted bicycle, an electrically assisted tricycle, and a four wheel vehicle) that uses both electric power and human power (stepping input) for driving wheels. However, the present invention can also be applied to an electric vehicle of a type in which wheels are exclusively driven electrically (for example, an electric motorcycle, an electric three-wheeled vehicle, and the like).

Although not shown in the embodiment, in order to prevent the motor M from dragging, the second reduction ring gear 55 is moved from the second reduction ring gear 55 to the hub case H side between the hub case H (end wall member He) and the second reduction ring gear 55. A one-way clutch that transmits power only may be arranged.

Claims

One end wall portion (He) and the other end wall portion (Hmb) of the wheel hub case (H) are rotatably supported by the hub shaft (11), and the hub case (H) includes a motor (M), A speed reduction mechanism (R) that decelerates the driving force of the motor (M) and transmits it to the hub case (H) is housed side by side in the axial direction,
The motor (M) has a bottomed cylindrical motor case (31) that is open at one end (31a) and faces the one end wall (He) of the hub case (H). 31) is a power unit for an electric vehicle in which the other end portion (31b) serving as the bottom portion is fixed and supported on the hub shaft (11),
The reduction mechanism (R) includes a reduction sun gear (51) that is rotationally driven by the motor (M), a first gear (52a) that meshes with the reduction sun gear (51), and the first gear (52a). A reduction carrier (53) that rotatably supports the second gear (52b) arranged coaxially with the first gear (52a) is fitted to the one end (31a) of the motor case (31). A first reduction ring gear (54) that meshes with a second reduction ring gear (55) that is provided on the hub case (H) and meshes with the second gear (52b);
A bearing (B7) for rotatably supporting the first reduction ring gear (54) on the hub case (H) is interposed between the first reduction ring gear (54) and the hub case (H). A power unit for an electric vehicle.
Both side wall portions (s1, s2) of the deceleration carrier (53) sandwiching the first and second gears (52a, 52b) in the axial direction are rotatably supported on the hub shaft (11), respectively. The power unit for an electric vehicle according to claim 1, characterized in that:
The first reduction ring gear (54) includes ring gear extension portions (54a, 54a ′, 54a ″) that extend in the axial direction from the one end portion (31a) of the motor case (31) to the outside of the motor case (31). ), And the outer peripheral surface or inner peripheral surface of the ring gear extension (54a, 54a ′, 54a ″) is the mounting surface of the bearing (B7) on the first reduction ring gear (54) side. The power unit for an electric vehicle according to claim 1, wherein the power unit is for electric vehicles.