Drive unit and electric vehicle

Abstract

To provide a drive device which enables downsizing while inhibiting scattering of a lubricant, and to provide an electric vehicle which uses the drive device.SOLUTION: A drive device includes: a motor 20; an output part 30 which outputs torque to the outside; a gear part 40 which transmits torque of the motor to the output part; and a housing 50 having an internal space. The gear part has: at least one gear shaft 41 which extends in an axial direction and to which at least one gear is fixed; and a gear case which houses the gear. The gear case has: a wall part facing an outer peripheral surface of the gear housed therein in a radial direction and extending in a circumferential direction; and an opening which is located adjacent to the wall part in the circumferential direction and penetrates through the gear case in the radial direction. The opening faces the housing in the radial direction. In a gear rotation direction, the wall part has a front side end part which is disposed forward of the opening and located adjacent to the opening. The front side end part contacts with the housing.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a drive device and an electric vehicle. [Background technology]

[0002] Conventionally, a driving force transmission device using gears and lubricating oil for lubricating the gears is known. In this driving force transmission device, a housing portion that houses the gears is disposed inside a transmission case. (For example, see JP 2019-132411 A.) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-132411 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described driving force transmission device, since the housing portion is housed inside the transmission case, it is difficult to reduce the size of the transmission case.

[0005] The present invention provides a drive device that can be made compact while suppressing scattering of lubricant, and an electric vehicle using the drive device. [Means for solving the problem]

[0006] An exemplary drive device of the present invention includes a motor, an output section that outputs torque to the outside, a gear section that transmits the torque of the motor to the output section, and a housing having an internal space in which the motor, a part of the output section, and the gear section are housed. The gear section includes at least one gear shaft that extends in the axial direction and has at least one gear fixed thereto, and a gear case that houses the gear. The gear case has a wall section that faces radially an outer circumferential surface of the housed gear and extends in the circumferential direction, and an opening that is adjacent to the wall section in the circumferential direction and penetrates the gear case in the radial direction. The opening faces radially to the housing, and in the rotation direction of the gear, the wall section has a front end portion that is disposed on the front side of the opening and adjacent to the opening, and the front end portion contacts the housing.

[0007] An exemplary electric vehicle of the present invention includes a drive device and a power supply unit that supplies power to the drive device. Effect of the Invention

[0008] According to the illustrative embodiment of the present invention, it is possible to provide a drive device that can be made compact while suppressing scattering of lubricant, and an electric vehicle using the drive device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an electric vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the drive unit. [Diagram 3] FIG. 3 is a perspective view of the inside of the drive device from which the second plate member and the second cylindrical portion have been removed, as viewed from the upper left. [Figure 4] FIG. 4 is a perspective view of the inside of the drive device from which the second plate member and the second cylindrical portion have been removed, as viewed from the lower left. [Diagram 5] FIG. 5 is a schematic perspective view showing the meshing of gears of the gear portion. [Figure 6] FIG. 6 is a cross-sectional view of the drive unit. [Figure 7] FIG. 7 is a cross-sectional view showing the crankshaft and the output section. [Figure 8]FIG. 8 is a perspective view of the first plate member and the first cylindrical portion. [Figure 9] FIG. 9 is a perspective view of the second plate member and the second cylindrical portion. [Figure 10] FIG. 10 is a perspective view of a support member that supports the motor and the gear portion and is fixed to the first cylindrical portion. [Figure 11] FIG. 11 is an enlarged cross-sectional view of the opening of the gear case. [Figure 12] FIG. 12 is a schematic layout diagram of the second gear shaft of the first modified example. [Figure 13] FIG. 13 is a schematic layout diagram of a support member according to the second modified example. [Figure 14] FIG. 14 is an enlarged cross-sectional view of an opening of a gear case of the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings. In this specification, when describing the drive device 10, a direction parallel to the central axis J2 of the first gear shaft 41 of the drive device 10 shown in FIG. 1 is referred to as the "axial direction". In addition, a direction perpendicular to the central axis of each rotatable shaft is referred to as the "radial direction", and a direction along an arc centered on the central axis is referred to as the "circumferential direction". In addition, based on the state where the electric vehicle 100 is attached, the traveling direction of the electric vehicle 100 is referred to as the "forward F", and the opposite direction is referred to as the "backward B". In addition, "upward U", "downward D", "leftward L", and "rightward R" are defined when facing forward. Note that the descriptions of directions in the following description are defined for ease of explanation, and may not match the directions of the drive device 10 actually used.

[0011] <Electric vehicle 100> 1 is a schematic diagram of an electric vehicle according to an embodiment of the present invention. In this embodiment, the electric vehicle 100 is an electric-assisted bicycle that assists a user in exerting force on a pedal 106. As shown in FIG. 1, the electric vehicle 100 has a body 101, two wheels 102, a power transmission mechanism 103, a drive unit 10, and a power supply unit 104.

[0012] The vehicle body 101 includes a handlebar 107 and a saddle 108. Two wheels 102, a power transmission mechanism 103, a driving device 10, and a power supply unit 104 are attached to the vehicle body 101. The two wheels 102 are attached to the front of the vehicle body 101 as a front wheel 102f and to the rear of the vehicle body 101 as a rear wheel 102r. The power transmission mechanism 103 is connected to the rear wheel 102r.

[0013] The power transmission mechanism 103 includes a crank 105 attached to a crankshaft 105a, and a pedal 106. The power transmission mechanism 103 further includes a drive gear attached to an output unit 30 (described later) of the drive unit 10, a driven gear attached to the rear wheel 102r, and a chain (all not shown) connecting the drive gear and the driven gear. The crank 105 is fixed to a crankshaft 105a rotatably attached to the vehicle body 101. Furthermore, a pedal 106 is rotatably attached to the tip of the crank 105.

[0014] The driving device 10 is attached to a power transmission mechanism 103. The driving device 10 transmits torque from an output unit 30 (see FIG. 2) to the power transmission mechanism 103. The torque transmitted from the driving device 10 is transmitted to the rear wheel 102r via the power transmission mechanism 103. In other words, the electric vehicle 100 has the power transmission mechanism 103 that transmits the output from the output unit 30 to the wheel 102r.

[0015] The output unit 30 of the drive device 10 is formed of a single member together with the output gear 31 described below, but is not limited to this. For example, the output unit 30 may also function as the crankshaft 105a. In other words, the drive device 10 can widely adopt a configuration that can assist the rotation of the wheels by the force of the user.

[0016] The power supply unit 104 is attached to the vehicle body 101. The power supply unit 104 is, for example, a battery, and supplies power to a motor 20 (described later) of the drive device 10 via wiring shown in the figure. That is, the electric vehicle 100 has the drive device 10 and the power supply unit 104 that supplies power to the motor 20 of the drive device 10.

[0017] In the electric vehicle 100, a user seated on a saddle 108 steps on a pedal 106, which applies torque to the crankshaft 105a. The torque applied to the crankshaft 105a is transmitted to the rear wheel 102r via the output unit 30 and the power transmission mechanism 103. The transmitted torque rotates the rear wheel 102r, and the electric vehicle 100 travels. The drive unit 10 detects the torque applied to the crankshaft 105a, and applies torque from the output unit 30 to the power transmission mechanism 103 as necessary. The torque transmitted from the output unit 30 is added to the torque for traveling of the electric vehicle 100. In other words, the drive unit 10 assists the torque required for traveling of the electric vehicle 100 as necessary.

[0018] <Driver 10> Fig. 2 is a perspective view of the drive device 10 as viewed from below. Fig. 3 is a perspective view of the inside of the drive device 10 as viewed from the upper left with the second plate member 52 and the second tubular portion 54 removed. Fig. 4 is a perspective view of the inside of the drive device 10 as viewed from the lower left with the second plate member 52 and the second tubular portion 54 removed. Fig. 5 is a schematic perspective view showing the meshing of the gears of the gear portion. Fig. 6 is a cross-sectional view of the drive device 10.

[0019] As shown in FIGS. 2 to 6, the drive device 10 includes a motor 20, an output portion 30, a gear portion 40, and a housing 50.

[0020] <Motor 20> The motor 20 is a DC brushless motor. The motor 20 is driven by power from the power supply unit 104. The motor 20 has a rotor (not shown) that rotates around a central axis J1, and a stator (not shown) that is located radially outward of the rotor. That is, the motor 20 is an inner rotor type motor in which the rotor is rotatably disposed inside the stator. The motor 20 is not limited to an inner rotor type motor, and may be an outer rotor type motor. The motor 20 also has a motor shaft 21. The motor shaft 21 is fixed to the rotor, extends along the central axis J1 that extends in the left-right direction, and rotates around the central axis J1. As shown in FIG. 5, the motor shaft 21 protrudes leftward from the main body of the motor 20.

[0021] A drive gear 22 is disposed at the tip end, i.e., the left end, of the motor shaft 21. The drive gear 22 is fixed to the motor shaft 21 and rotates integrally with the motor shaft 21. The drive gear 22 can be fixed to the motor shaft 21 by a wide variety of methods that can firmly fix the drive gear 22 to the motor shaft 21, such as press fitting, welding, or adhesive.

[0022] Fig. 7 is a cross-sectional view showing the crankshaft 105a and the output portion 30. As shown in Figs. 3, 5, 7, etc., the crankshaft 105a extends along the output axis J4. The left end of the crankshaft 105a protrudes to the left of the housing 50. The right end of the crankshaft 105a protrudes to the right of the housing 50. As described above, the left and right cranks 105 (see Fig. 1) are fixed to both ends of the crankshaft 105a, respectively.

[0023] The output unit 30 and the torque detector Sr are disposed on the crankshaft 105a in the direction of the output shaft J4. More specifically, the output unit 30 and the torque detector Sr are disposed around the crankshaft 105a.

[0024] The torque detector Sr detects the torque acting on the crankshaft 105a. That is, the drive device 10 further includes a torque detector Sr that detects the torque acting on the crankshaft 105a. In the drive device 10 of this embodiment, the torque detector Sr includes a sleeve fixed to the crankshaft 105a and an outer cylinder portion that surrounds the radial outside of the sleeve.

[0025] The outer cylinder portion has a protrusion Sr1 protruding radially outward, and the protrusion Sr1 is fixed to a fixing portion 560 (see FIG. 3) of the support member 56. That is, a part of the torque detection portion Sr is fixed to the support member 56. With this configuration, a member for attaching the torque detection portion Sr can be omitted, and the drive device 10 can be made smaller. Note that the torque detection portion Sr is not limited to this configuration, and a wide variety of configurations that can accurately detect the torque of the rotating crankshaft 105a can be adopted.

[0026] <Output unit 30> The output unit 30 extends along an output axis J4 parallel to the central axis J1. That is, the output unit 30 extends parallel to the motor shaft 21. The output unit 30 has an output gear 31. The output unit 30 covers the periphery of the crankshaft 105a at the right end of the crankshaft 105a. The output unit 30 is connected to a power transmission mechanism 103 (see FIG. 1). The output unit 30 outputs torque to the power transmission mechanism 103. That is, the drive device 10 has the output unit 30 that outputs torque to the outside. The output unit 30 is connected to the crankshaft 105a via an output bearing unit 33 and a one-way clutch 34. By being attached in this manner, the torque from the crankshaft 105a is transmitted to the power transmission mechanism 103 only when the torque is transmitted from the crankshaft 105a to the output unit 30.

[0027] Although the output bearing unit 33 employs a ball bearing as a bearing member, this is not limiting. Any bearing structure capable of supporting the output unit 30 rotatably around the crankshaft 105a can be widely employed. Although one bearing member is used as the output bearing unit 33, this is not limiting and a configuration using multiple bearing members may also be used. Hereinafter, when the term "bearing unit" is used, this is taken to mean the same configuration.

[0028] The crankshaft 105a and the output section 30 are rotatably supported by the housing 50 via the bearing section Br. More specifically, the left end of the crankshaft 105a is rotatably supported by an inner surface 521 of a second plate member 52 of the housing 50 (described later) via the bearing section Br. The output section 30 covers the left end of the crankshaft 105a and is rotatably supported by an inner surface 511 of a first plate member 51 of the housing 50 (described later) via the bearing section Br. As described above, the crankshaft 105a is connected to the output section 30 via the output bearing section 33 and the one-way clutch 34. Therefore, the left end of the crankshaft 105a is rotatably supported by the first plate member 51 of the housing 50 via the output bearing section 33, the output section 30, and the bearing section Br.

[0029] <Gear part 40> The gear unit 40 transmits the torque of the motor shaft 21 to the output unit 30. In other words, the gear unit 40 transmits the torque of the motor 20 to the output unit 30. The gear unit 40 is a speed reduction mechanism that reduces the speed when transmitting the torque from the motor shaft 21 to the output unit 30. The gear unit 40 has a first gear shaft 41, a second gear shaft 42, a first gear 43, a second gear 44, a third gear 45, and a fourth gear 46.

[0030] The first gear shaft 41 extends along a first intermediate shaft J2 parallel to the central axis J1. The first gear shaft 41 is cylindrical and rotatable around the first intermediate shaft J2. The first gear shaft 41 is rotatably supported by the housing 50 via a first bearing 411 and a second bearing 412 that are spaced apart from each other in a direction along the first intermediate shaft J2.

[0031] The second gear shaft 42 extends along a second intermediate shaft J3 that is parallel to the central axis J1 and the first intermediate shaft J2. The second gear shaft 42 is cylindrical and rotatable around the second intermediate shaft J3. The second gear shaft 42 is rotatably supported by the housing 50 via a third bearing 421 and a fourth bearing 422 that are spaced apart from each other in a direction along the second intermediate shaft J3.

[0032] The first gear 43 and the second gear 44 are fixed to the first gear shaft 41. The first gear 43 meshes with the drive gear 22. The second gear 44 meshes with a third gear 45 fixed to the second gear shaft 42. That is, the second gear 44 meshes with the gear 45 fixed to the second gear shaft 42. The outer diameter of the first gear 43 is larger than the outer diameter of the second gear 44. In other words, the number of teeth of the first gear 43 is larger than the number of teeth of the second gear 44. That is, the gear unit 40 has a first gear shaft 41 to which the first gear 43 and the second gear 44, which has fewer teeth than the first gear 43, are fixed.

[0033] Therefore, the torque transmitted from the drive gear 22 to the first gear shaft 41 via the first gear 43 is reduced in speed by the gear ratio between the first gear 43 and the second gear 44, and then transmitted to the second gear shaft 42. In addition, the number of teeth of the second gear 44 is smaller than the number of teeth of the third gear 45. Therefore, the torque of the first gear shaft 41 is also reduced in speed by the gear ratio between the second gear 44 and the third gear 45, and then transmitted to the second gear shaft 42.

[0034] In addition, the phrase "torque is reduced in speed by the gear ratio and then transmitted" means that the rotation speed is reduced using the gear ratio as a reduction ratio, that is, the rotation speed is reduced and the torque is amplified and then transmitted, and the same applies below.

[0035] The third gear 45 and the fourth gear 46 are formed separately. The fourth gear 46 is formed integrally with the second gear shaft 42. The third gear 45 is rotatably supported by the second gear shaft 42 via a one-way clutch 423 and a bearing portion 424. By attaching in this manner, torque is transmitted to the second gear shaft 42 only when torque is transmitted from the second gear 44 to the third gear 45.

[0036] The fourth gear 46 meshes with the output gear 31. The outer diameter of the third gear 45 is larger than that of the fourth gear 46. In other words, the number of teeth of the third gear 45 is larger than that of the fourth gear 46. Therefore, the torque transmitted from the fourth gear 46 to the second gear shaft 42 via the output gear 31 is decelerated by the gear ratio between the third gear 45 and the fourth gear 46. Moreover, the number of teeth of the output gear 31 is larger than that of the fourth gear 46. Therefore, the torque of the second gear shaft 42 is also decelerated by the gear ratio between the fourth gear 46 and the output gear 31 and transmitted to the output section 30.

[0037] Although the gear unit 40 of this embodiment has two gear shafts, it may have one gear shaft or three or more gear shafts if a desired reduction ratio can be obtained. Also, it may have a so-called intermediate gear mechanism in which one gear is attached to one gear shaft and used to reverse the direction of rotation. That is, the gear unit 40 has at least one gear shaft rotatably supported by the housing 50 via two bearings arranged axially apart.

[0038] <Housing 50> The housing 50 will be described in detail with reference to the drawings. Fig. 8 is a perspective view of the first plate member 51 and the first cylindrical portion 53. Fig. 9 is a perspective view of the second plate member 52 and the second cylindrical portion 54. As shown in Figs. 3 to 6 etc., the housing 50 has an internal space 500. The motor 20, a part of the output portion 30 and the gear portion 40 are accommodated in the internal space 500. That is, the housing 50 has the internal space 500 in which the motor 20, a part of the output portion 30 and the gear portion 40 are accommodated.

[0039] 1 to 9, the housing 50 has a first plate member 51, a second plate member 52, a first cylindrical portion 53, and a second cylindrical portion 54. As shown in Fig. 6, the housing 50 has the first plate member 51 and the second plate member 52 which face the internal space 500 and oppose each other in the axial direction. More specifically, the first plate member 51 is disposed to the right of the internal space 500, and the second plate member 52 is disposed to the left of the internal space 500.

[0040] 8, the first cylindrical portion 53 protrudes leftward in the axial direction from an inner surface 511 of the first plate member 51 that faces the internal space 500. That is, the housing 50 has the first cylindrical portion 53 extending in the axial direction from an outer edge of the surface 511 of the first plate member 51 that faces the second plate member 52. Note that in this embodiment, the first cylindrical portion 53 is formed of a single member together with the first plate member 51, but is not limited thereto, and may be formed of a separate member and fixed by a fixing method such as adhesion or screwing.

[0041] 9, the second tubular portion 54 protrudes rightward in the axial direction from an inner surface 521 of the second plate member 52 facing the internal space 500. That is, the housing 50 has the second tubular portion 54 extending in the axial direction from an outer edge of the surface 521 of the second plate member 52 facing the first plate member 51. Note that in this embodiment, the second tubular portion 54 is formed of a single member together with the second plate member 52, but is not limited thereto, and may be formed of a separate member and fixed by a fixing method such as adhesion or screwing.

[0042] 1, 6, etc., at least a portion of the axially opposing end faces of the first cylindrical portion 53 and the second cylindrical portion 54 contact each other. More specifically, the axially left end face 531 of the first cylindrical portion 53 and the axially right end face 541 of the second cylindrical portion 54 face each other in the axial direction. The end face 531 of the first cylindrical portion 53 and the end face 541 of the second cylindrical portion 54 contact each other in a portion other than the portion that contacts a support member 56 described later. As a result, an internal space 500 surrounded by the housing 50 is formed.

[0043] Further, the first tube portion 53 has a protruding portion 55. The protruding portion 55 protrudes inward from the first tube portion 53. Here, "protruding inward" means a configuration in which the protruding portion 55 protrudes from the surface of the first tube portion 53 facing the internal space 500 into the internal space 500. In this embodiment, the first tube portion 53 is provided with four protruding portions 55, but the present invention is not limited thereto, and any number of protruding portions may be provided as long as the support member 56 can be firmly fixed. The protruding portion 55 protrudes inward from the first tube portion 53, thereby increasing the rigidity of the protruding portion 55. As a result, the protruding portion 55 is less likely to bend, and the fixing strength of the support member 56 can be increased.

[0044] The protruding portion 55 extends in the axial direction, and a right end portion thereof is connected to the first plate member 51. That is, when the protruding portion 55 protrudes from the first tubular portion 53, the protruding portion 55 is connected to the first plate member 51. The protruding portion 55 is connected to the first plate member 51 in any of the following cases: the protruding portion 55 is formed of a single member together with the first plate member 51, the protruding portion 55 is fixed to the first plate member 51, and the protruding portion 55 is in contact with the first plate member 51. With this configuration, the axial force of the protruding portion 55 can be supported by the first plate member 51, and therefore, the axial movement and deformation of the support member 56 fixed to the protruding portion 55 is suppressed.

[0045] In the housing 50 of the present embodiment, the protruding portion 55 is formed of a single member together with the first plate member 51, but is not limited to this. For example, in a configuration in which the first plate member 51 and the first cylindrical portion 53 are formed of separate members and fixed together, the protruding portion 55 may be configured to be in contact with the first plate member 51 but not fixed thereto. Also, the protruding portion 55 may be configured not to be connected to the first plate member 51.

[0046] Furthermore, the protruding portion 55 is formed on the first cylindrical portion 53, but may be formed on the second cylindrical portion 54, or may be formed on both. That is, the housing 50 further has a protruding portion 55 that protrudes inward from at least one of the first cylindrical portion 53 and the second cylindrical portion. When the protruding portion 55 is formed on the second cylindrical portion 54, the protruding portion 55 extends in the axial direction, and the left end portion may be connected to the second plate member 52. That is, when the protruding portion 55 protrudes from the second cylindrical portion 54, it is connected to the second plate member 52.

[0047] With this configuration, the axial force of the protruding portion 55 can be supported by the second plate member 52, so that axial movement and deformation of the support member 56 fixed to the protruding portion 55 is suppressed.

[0048] The housing 50 also has a support member 56 disposed inside the internal space 500. In the present embodiment, the support member 56 is disposed within the internal space 500, but is not limited thereto, and a portion of the support member 56 may be disposed outside the housing 50 or exposed to the outside. That is, the housing 50 has the support member 56 at least a portion of which is disposed within the internal space 500.

[0049] The support member 56 is a plate material extending in a direction intersecting the axial direction. In the housing 50 according to this embodiment, the support member 56 supports the motor 20 and the gear unit 40. FIG. 10 is a perspective view of the support member 56 that supports the motor 20 and the gear unit 40 and is fixed to the first cylindrical portion 53. As shown in FIG. 10, the support member 56 is fixed to a protrusion 55 formed on the first cylindrical portion 53 by a fastener such as a screw. The support member 56 is also sandwiched in the axial direction between the bottom of a first pillar portion 512 and the bottom of a second pillar portion 522, which will be described later. The support member 56 is then fastened together by a fastener such as a screw inserted into the first pillar portion 512 and the second pillar portion 522 from the outside of the housing 50. That is, the support member 56 is fixed to the protrusion 55, the first pillar portion 512, and the second pillar portion 522.

[0050] The support member 56 is fixed to the protruding portion 55 by, for example, a screw. Moreover, a screw is passed through the support member 56 sandwiched between the first pillar portion 512 and the second pillar portion 522, and the first pillar portion 512, the second pillar portion 522 and the support member 56 are fastened together to be fixed. In this way, the support member 56 is fixed within the internal space 500 of the housing 50.

[0051] The housing 50 has a first pillar portion 512 that protrudes leftward along the axial direction from a region surrounded by the first cylindrical portion 53 of the inner surface 511 of the first plate member 51. The housing 50 also has a second pillar portion 522 that protrudes rightward along the axial direction from a region surrounded by the second cylindrical portion 54 of the inner surface 521 of the second plate member 52.

[0052] The first pillar portion 512 and the second pillar portion 522 are cylindrical with a bottom, and when an end face 531 of the first cylinder portion 53 and an end face 541 of the second cylinder portion 54 are brought into contact with each other and fixed, the bottom of the first pillar portion 512 and the bottom of the second pillar portion 522 face each other in the axial direction and sandwich the support member 56 from both sides in the axial direction. Note that, in the housing 50 of this embodiment, pillar portions are formed on both the first plate member 51 and the second plate member 52, but this is not limited thereto, and pillar portions may be formed on either the first plate member 51 or the second plate member 52.

[0053] That is, the housing 50 further has pillars 512, 522 protruding in the axial direction toward the internal space 500 from at least one of the area surrounded by the first cylindrical portion 53 of the first plate member 51 and the area surrounded by the second cylindrical portion of the second plate member 52. With this configuration, the support portion of the support member 56 can be dispersed, and the concentration of stress on the support member 56 can be suppressed. Therefore, even if the rigidity of the support member 56 is low, the motor 20 and the gear portion 40 can be supported, and the support member 56 can be made smaller and simpler. This allows the proportion of the internal space 500 that the support member 56 occupies to be reduced, and as a result, the drive device 10 can be made smaller.

[0054] It is also possible to provide only the first pillar portion 512 and fix the support member 56 to the first pillar portion 512. That is, the pillar portion 512 contacts only the surface on the other axial side of the support member 56. With this configuration, the surface on the other side of the support member 56 contacts the pillar portion 512, so that neither the gear shaft nor the pillar portion is arranged on one axial side. This makes it possible to reduce the size of the housing 50 or to form an area in the internal space of the housing to arrange another member, thereby reducing the size of the drive device itself.

[0055] The support member 56 has a first through hole 561, a second through hole 562, and a motor support hole 563 (see Figs. 3 and 4). The motor 20 is fixed to the first plate member 51. The motor shaft 21 passes through the motor support hole 563 and is rotatably supported by the support member 56 via the motor bearing portion 23. That is, the motor shaft 21 extends in the axial direction and is rotatably supported by the support member 56 via the motor bearing portion 23. More specifically, the outer ring of the motor bearing portion 23 is fixed to the motor support hole 563, and the motor shaft 21 is fixed to the inner ring. With this configuration, it is possible to suppress misalignment between the motor shaft 21 and the gear shafts 41 and 42. As a result, the torque of the motor shaft 21 can be accurately transmitted to the gear portion 40.

[0056] Moreover, the first gear shaft 41 is rotatably supported by the inner surface 521 of the second plate member 52 via the first bearing portion 411. The outer ring of the second bearing portion 412 is fixed to the first through hole 561 of the support member 56, and the first gear shaft 41 is fixed to the inner ring. As a result, the first gear shaft 41 is rotatably supported by the second plate member 52 via the first bearing portion 411, and is rotatably supported by the support member 56 via the second bearing portion 412.

[0057] The second gear shaft 42 is rotatably supported by the inner surface 511 of the first plate member 51 via the fourth bearing portion 422. An outer ring of the fourth bearing portion 422 is fixed to the second through hole 562, and the second gear shaft 42 is fixed to the inner ring. As a result, the second gear shaft 42 is rotatably supported by the first plate member 51 via the fourth bearing portion 422, and is rotatably supported by the support member 56 via the third bearing portion 421. That is, the gear unit 40 has the second gear shaft 42 that is disposed parallel to the first gear shaft 41 and rotatably supported by the support member 56.

[0058] That is, at least one gear shaft 42 is rotatably supported by the support member 56 via a bearing portion 422 on one side in the axial direction. With this configuration, the gear shaft 42 of the gear unit 40 supported by the housing 50 and the support member 56 can be shortened, and the gear unit 40 can be made smaller accordingly. This makes it possible to make the housing 50 smaller, or to form an area in the internal space 500 of the housing 50 for arranging another member, thereby making it possible to make the drive unit 10 smaller. Furthermore, by shortening the gear shaft 42, twisting of the gear shaft 42 can be suppressed. This makes it possible to suppress delays in torque transmission due to twisting.

[0059] The second gear shaft 42 has a shaft protruding portion 420 (see FIG. 6) protruding leftward beyond the support member 56. The third gear 45 and the fourth gear 46 are attached to the shaft protruding portion 420 protruding leftward beyond the support member 56 of the second gear shaft 42. That is, the gear unit 40 has at least one gear shaft 42 extending in the axial direction and having at least one gear 45 fixed thereto.

[0060] The second gear shaft 42 is rotatably supported by the support member 56 and the first plate member 51 via the third bearing portion 421 and the fourth bearing portion 422. Therefore, the second gear shaft 42 does not protrude leftward beyond the third gear 45. This allows a space to be provided between the third gear 45 and the second plate member 52 in the internal space 500. The first gear 43 can be disposed in this space. This allows the gear portions 40 to be disposed closely together, and the members can be disposed efficiently in the internal space 500. This allows the drive device 10 to be made compact.

[0061] In addition, in the gear unit 40, the first gear 43 can be disposed at a position overlapping with the second gear shaft 42 when viewed from the direction of the second intermediate shaft J3. That is, a part of the first gear 43 faces an axial end face of the second gear shaft 42. Since the first gear 43 and the second gear shaft 42 do not interfere with each other, the diameter of the first gear 43 can be increased without increasing the size of the internal space 500. This makes it possible to increase the reduction ratio of the gear unit 40 without increasing the size of the drive device 10.

[0062] Further, the right end of the first gear shaft 41 is rotatably supported by the support member 56 via the second bearing portion 412. Therefore, the first gear shaft 41 does not protrude rightward from the support member 56. Therefore, it is possible to dispose a part of the motor 20 in a portion overlapping with the first gear shaft 41 to the right of the support member 56 when viewed from the direction of the first intermediate shaft J2. This allows the components in the internal space 500 to be disposed closely together, and the housing 50, i.e., the drive device 10, can be made compact.

[0063] <Gear Case 47> 11 is an enlarged cross-sectional view of the opening 472 of the gear case 47. The gear unit 40 has a gear case 47 and a gear cover 48. The gear case 47 houses the third gear 45. That is, the gear unit 40 has the gear case 47 that houses the gear 45. The gear cover 48 is disposed axially left of the third gear 45 and covers the axial left side of the third gear 45.

[0064] The gear case 47 has a wall portion 471 that faces the outer circumferential surface of the third gear 45 in the radial direction and extends in the circumferential direction, and an opening portion 472 that is adjacent to the wall portion 471 in the circumferential direction and penetrates the gear case 47 in the radial direction. The wall portion 471 is disposed radially outward of the third gear 45 and extends in the circumferential direction. The opening portion 472 faces the second cylindrical portion 54 of the housing 50 in the radial direction. In other words, the opening portion 472 faces the housing 50 in the radial direction.

[0065] The wall portions 471 are adjacent to both sides of the opening 472 in the circumferential direction. In the rotation direction Rt of the third gear 45, an end portion of the wall portion 471 that is disposed on the front side of the opening 472 and adjacent to the opening 472 is a front end portion 4711. Also, an end portion of the wall portion 471 that is disposed on the rear side of the opening 472 and adjacent to the opening 472 is a rear end portion 4712. That is, the wall portion 471 has the front end portion 4711 that is disposed forward of the opening 472 in the rotation direction Rt of the gear 45. The wall portion 471 has the rear end portion 4712 that is disposed rearward of the opening 472 in the rotation direction Rt of the gear 45.

[0066] 11 , the front end portion 4711 contacts the inner surface of the second cylindrical portion 54 of the housing 50. That is, the front end portion 4711 contacts the housing 50. More specifically, the front end portion 4711 of the wall portion 471 contacts the cylindrical portion 54 that surrounds the internal space 500 of the housing 50.

[0067] With this configuration, the third gear 45 and the gear case 47 can be disposed closer to the second cylindrical portion 54 of the housing 50 by an amount corresponding to the thickness of the wall portion 471 of the gear case 47. This allows the housing 50 to be made more compact, and the drive unit 10 to be made more compact accordingly.

[0068] In the gear section 40, a lubricant is interposed between each gear. A highly viscous lubricant, a so-called grease-like lubricant, is used to lubricate the gears. The gear case 47 has an opening 472, and the second cylindrical portion 54 of the housing 50 is disposed outside the opening 472, so that the lubricant that lubricates the third gear 45 moves to a portion close to the second cylindrical portion 54 of the housing 50, and the temperature rise of the lubricant can be suppressed. This makes it possible to suppress a decrease in the lubricating ability of the lubricant.

[0069] The grease-like lubricant adheres to the outer peripheral surface of the third gear 45 and suppresses friction and wear between the gears. However, the grease-like lubricant tends to form clumps. When the lubricant forms clumps to a certain extent, it flies outward in the radial direction of the third gear 45 due to centrifugal force. At this time, because the third gear 45 is rotating, the lubricant flies forward in the direction of rotation and outward in the radial direction.

[0070] Therefore, the front end portion 4711 of the wall portion 471 has a front side elastic portion 4713. The front side elastic portion 4713 comes into contact with the second cylindrical portion 54. In other words, the front end portion 4711 of the wall portion 471 has the elastically deformable front side elastic portion 4713, and the front side elastic portion 4713 comes into contact with the housing 50.

[0071] This ensures more reliable contact between the front end 4711 of the wall portion 471 of the gear case 47 and the second cylindrical portion 54. This makes it possible to more reliably receive the lubricant that is thrown radially outward by the centrifugal force caused by the rotation of the third gear 45. As a result, the lubricant is less likely to enter between the gear case 47 and the second cylindrical portion 54 of the housing 50.

[0072] Furthermore, the front-side elastic portion 4713 extends radially outward as it moves rearward in the rotation direction of the third gear 45. That is, the front-side elastic portion 4713 extends radially outward as it moves rearward in the rotation direction of the gear 45. With this configuration, when the lubricant scattered toward the second cylindrical portion 54 of the housing 50 moves due to the rotation of the third gear 45, the front-side elastic portion 4713 can scoop up the lubricant.

[0073] Moreover, the rear end portion 4712 may come into contact with the second cylindrical portion 54 of the housing 50. That is, the rear end portion 4712 may come into contact with the housing 50. With this configuration, it is possible to suppress the intrusion of the lubricant between the gear case 47 and the housing 50.

[0074] Further, the rear end portion 4712 of the wall portion 471 has a rear side elastic portion 4714. The rear side elastic portion 4714 is elastically deformable and comes into contact with the second cylindrical portion 54 of the housing 50. That is, the rear end portion 4712 of the wall portion 471 has the elastically deformable rear side elastic portion 4714, and the rear side elastic portion 4714 comes into contact with the housing 50. With this configuration, it is possible to further suppress the intrusion of the lubricant between the gear case 47 and the housing 50.

[0075] <First Modification> 12 is a schematic layout diagram of the second gear shaft 42 of the first modified example. This modified example differs in that the third gear 45 and the fourth gear 46 of the second gear shaft 42 are arranged apart in the axial direction. Other than this, the configuration is the same as that of the drive device 10. Therefore, the same reference numerals are used for the reference numerals of the respective components, and detailed description will be omitted.

[0076] 12, the third gear 45 and the fourth gear 46 are arranged apart in the axial direction. The third gear 45 is fixed to the second gear shaft 42, and the fourth gear 46 is attached to the second gear shaft 42 via a one-way clutch 423 and a bearing portion 424. That is, the gear shaft has at least one gear 45. At least one of the gear shafts supported by the support member 56 via the bearing portion 422 has a shaft protruding portion 420 that protrudes further toward one side in the axial direction than the support member 56.

[0077] The third gear 45 is disposed to the left of the support member 56, and the fourth gear is disposed to the right of the support member 56. That is, at least one of the gears is attached to the shaft protrusion 420. By disposing them in this manner, the second gear shaft 42 can be made short. This allows the drive device 10 to be made more compact.

[0078] <Second Modification> FIG. 13 is a schematic layout diagram of the support member 56a of the second modified example. In this modified example, the support member 56a is different from the support member 56. Other than this, the configuration is the same as that of the drive device 10. Therefore, the same reference numerals are given to the members other than the support member 56a, and detailed description is omitted. As shown in FIG. 13, the support member 56a may rotatably support the output portion 30 via the fifth bearing portion 35. That is, the output portion 30 extends in the axial direction and is rotatably supported by the support member 56a via the fifth bearing portion 35. In this way, it is possible to suppress misalignment between the output portion 30 of the support member 56a and the first gear shaft 41 and the second gear shaft 42. This makes it possible to suppress tilting of the output portion 30, that is, the crankshaft 105a, relative to the gear portion 40.

[0079] <Third Modification> Fig. 14 is an enlarged cross-sectional view of an opening 472 of a gear case 47b of a third modified example. Gear case 47b of this modified example differs from gear case 47 shown in Fig. 11 etc. in that it has ribs 49 and ribs 49b. Other than this, gear case 47b has substantially the same configuration as gear case 47. Therefore, the same reference numerals are used for the substantially same parts of gear case 47b as those of gear case 47, and detailed description of the same parts will be omitted.

[0080] 14, the gear case 47b has a rib 49 and a rib 49b protruding from an inner surface of a wall portion 471 toward the third gear 45. That is, the wall portion 471 of the gear case 47b has the ribs 49, 49b protruding radially inward from a surface facing radially to the outer circumferential surface of the gear 45 and facing the outer circumferential surface of the gear 45 with a gap therebetween.

[0081] With this configuration, the lubricant adhering to the outer peripheral surface of the gear 45 can be thinly and evenly distributed along the outer peripheral surface of the gear 45. This prevents the lubricant from forming clumps and from scattering radially outward. In addition, the lubricant can be stably adhered to the gear 45, improving the lubrication effect of the gear 45.

[0082] 14, the rib 49 is formed on the rear end 4712 of the wall portion 471. With this configuration, it is possible to prevent the lubricant from scattering to the outside from the opening 472 and to prevent the lubricant from entering between the gear case 47b and the housing 50.

[0083] 14, the rib 49 has a curved surface that faces the outer circumferential surface of the gear 45 and protrudes toward the gear 45. With this configuration, when the gear 45 comes into contact with the rib 49 due to vibration or the like, the teeth of the gear 45 come into contact with the curved surface, so that both the gear 45 and the rib 49 are less likely to be damaged. This allows the drive device 10 to operate stably for a long period of time.

[0084] 14, the facing surface facing the outer circumferential surface of the gear 45 may have an inclination approaching the outer circumferential surface of the gear 45 as it moves forward in the rotation direction Rt of the gear 45. With this configuration, the lubricant in contact with the facing surface can be efficiently guided along the outer circumferential surface of the gear 45. This makes it possible to prevent the lubricant from scattering to the outside from the opening 472 and entering between the gear case 47b and the housing 50.

[0085] The gear cases 47, 47b shown above have been described as accommodating the third gear 45 attached to the second gear shaft 42, but are not limited thereto. A gear other than the third gear 45 may be accommodated therein.

[0086] Various technical features disclosed in this specification may be modified in various ways without departing from the spirit of the technical creation. Furthermore, multiple embodiments and modifications shown in this specification may be combined to the extent possible. [Industrial Applicability]

[0087] The present invention can be used in electric vehicles that obtain driving force from electricity, such as power-assisted bicycles, electric scooters, and electric wheelchairs. [Explanation of symbols]

[0088] 100 Electric Vehicles 101 Body 102 wheels 102f front wheel 102r rear wheel 103 Power transmission mechanism 104 Power supply section 105 Crank 106 Pedals 107 Handle 108 Saddle 10 Drive unit 20 Motor 21 Motor shaft 22 Drive Gear 23 Motor bearing 25 Stator 30 Output section 31 Output gear 33 Output bearing section 34 One-way clutch 35 5th bearing part 40 Gear section 41 1st gear shaft 411 1st bearing part 412 2nd bearing part 42 2nd gear shaft 420 Shaft protrusion 421 3rd bearing part 422 4th bearing part 423 One-way clutch 424 Bearing section 43 First Gear 44 2nd Gear 45 3rd Gear 46 4th Gear 47 Gear case 471 Wall 4711 Front end 4712 Rear end 4713 Front elastic part 4714 Rear elastic part 472 Opening 47b Gear case 48 Gear cover 49 Ribs 49b Rib 50 Housing 500 Internal space 51 1st plate member 511 Inside 512 1st pillar section 52 Second plate member 521 Inside 522 2nd pillar section 53 First cylinder part 531 End face 532 Protrusion 54 Second cylinder part 541 End face 55 Protrusion 56 Support member 561 First Through Hole 562 Second Through Hole 563 Motor support hole 56a Support member J1 center axis J2 First intermediate shaft J3 Second intermediate shaft J4 output shaft Rt Rotation direction Br bearing part Sr Torque detector

Claims

1. A motor; an output unit that outputs a torque to an outside; a gear portion that transmits the torque of the motor to the output portion; a housing having an internal space in which the motor, a part of the output portion, and the gear portion are accommodated, The gear portion is at least one gear shaft extending axially and having at least one gear fixed thereto; A gear case that houses the gear, The gear case includes: a wall portion that faces the outer peripheral surface of the accommodated gear in a radial direction and extends in a circumferential direction; a radially extending opening on the wall; The opening faces the housing in the radial direction (excluding the opening that faces the housing via a gear provided on the outside of the gear case), the wall portion has a front end portion disposed forward of the opening in a rotation direction of the gear, The forward end of the drive mechanism contacts the housing.

2. The drive unit according to claim 1 , wherein the front end of the wall portion contacts a cylindrical portion that surrounds the internal space of the housing.

3. The front end portion of the wall portion has a front elastic portion that is elastically deformable, The drive unit according to claim 1 or 2, wherein the front elastic portion contacts the housing.

4. The drive unit according to claim 3 , wherein the front elastic portion extends radially outward as it moves rearward in the rotational direction of the gear.

5. The wall portion has a rear end portion disposed rearward of the opening in a rotational direction of the gear. The drive unit according to claim 1 , wherein the rear end portion contacts the housing.

6. The rear end of the wall portion has a rear elastic portion that is elastically deformable, The driving device according to claim 5 , wherein the rear elastic portion contacts the housing.

7. 5. The drive device according to claim 1, wherein the wall portion has a rib that protrudes radially inward from a surface that faces radially the outer circumferential surface of the gear and faces the outer circumferential surface of the gear across a gap.

8. The wall portion has a rear end portion disposed rearward of the opening in a rotational direction of the gear, The drive unit according to claim 7 , wherein the rib is formed at the rear end of the wall portion.

9. 9. The drive device according to claim 7, wherein the rib has a curved surface that faces an outer circumferential surface of the gear and protrudes toward the gear.

10. 9. The drive unit according to claim 7, wherein a surface of the rib that faces the outer circumferential surface of the gear approaches the outer circumferential surface of the gear toward the front in a rotational direction of the gear.

11. A drive device according to any one of claims 1 to 10, A power supply unit that supplies power to the motor; and a power transmission mechanism that transmits the output from the output portion to wheels.

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