Drive unit for power-assisted bicycle

Abstract

To materialize a drive unit for power-assisted bicycles which facilitates enhancement of the amenity of an operator who operates a power-assisted bicycle.SOLUTION: A drive unit 10 for power-assisted bicycles includes an input member 21 to which a human power drive force is inputted, an output member 61 coupled to and driven by a wheel, a first rotary electric MG1 having a first rotor Rm1, a second rotary electric MG2 having a second rotor Rm2, and a distribution differential gear mechanism 40 that includes a first rotary element 41, a second rotary element 42, and a third rotary element 43, and that is configured so that the rotation speeds of the first rotary element 41, second rotary element 42, and third rotary element 43 are set in the described order. The first rotary element 41 is coupled to and driven by the first rotor Rm1, the second rotary element 42 is coupled to and driven by the input member 21, and the third rotary element 43 is coupled to and driven by the output member 61 and second rotor Rm2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a drive device for an electric assist bicycle that is attached to an electric assist bicycle.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2000-335474 (Patent Document 1) discloses an assisted bicycle in which a human power drive unit such as a pedal, a crankshaft (35), and a front sprocket (43) and an electric drive unit such as an auxiliary power motor (46) are provided side by side, and it is possible to operate the human power drive unit alone or the human power drive unit and the electric drive unit simultaneously.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the assisted bicycle of Patent Document 1, the driving force is transmitted from the auxiliary power motor to the chain between the front sprocket that outputs human power and the rear wheel sprocket via a two-stage speed reducer. That is, the gear ratio of the auxiliary power motor with respect to the front sprocket that outputs human power is fixed. For this reason, in order to keep the rotational speed of the feet within a certain range in a relatively wide speed range, it was necessary to provide a speed change gear in the human power drive unit. However, in such a case, there is a problem that the work of the operator who operates the bicycle increases and the comfort is impaired.

[0005] Therefore, it is desired to realize a drive device for an electric assist bicycle that can easily improve the comfort for the operator who operates the electric assist bicycle.

Means for Solving the Problems

[0006] The drive device for an electric assist bicycle according to the present disclosure is a drive device for an electric assist bicycle that is attached to the body frame of the electric assist bicycle and adds an auxiliary driving force to the human driving force and transmits it to the wheels. The drive device includes an input member to which the human driving force is input, an output member that is drivingly connected to the wheels, a first rotating electric machine including a first rotor, a second rotating electric machine including a second rotor, a first rotating element, a second rotating element, and a third rotating element, and a differential gear mechanism for distribution configured such that the order of the rotational speeds of the first rotating element, the second rotating element, and the third rotating element is the same as the described order. The first rotating element is drivingly connected to the first rotor, the second rotating element is drivingly connected to the input member, and the third rotating element is drivingly connected to the output member and the second rotor.

[0007] According to this configuration, by controlling the rotational speed of the first rotor, the ratio of the rotational speed of the output member to the rotational speed of the input member can be changed. Therefore, since it is not necessary to switch between a plurality of speed stages like a general bicycle transmission, the change of the speed ratio can be smoothly performed. Further, according to this configuration, by controlling the torques of the two rotating electric machines, the magnitude of the auxiliary driving force with respect to the human driving force can be changed. Therefore, compared with a general electric assist bicycle, it is easy to improve the comfort for the operator who operates the bicycle.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] 〔First Embodiment〕 Hereinafter, the drive device for an electric assist bicycle according to the first embodiment will be described with reference to the drawings.

[0010] FIGS. 1 and 2 are views showing an example of an electric assist bicycle 11 on which a drive device (hereinafter referred to as a drive device) 10 for an electric assist bicycle is mounted. The electric assist bicycle 11 includes a wheel 12 and a vehicle body frame 13. In the present embodiment, the electric assist bicycle 11 is a four-wheel bicycle, but it may be a three-wheel bicycle or a two-wheel bicycle. The drive device 10 is attached to the vehicle body frame 13. Examples of the vehicle body frame 13 include a ladder frame, a pipe frame, a monocoque body in which the frame and the body are integrated, a chassis, and the like. The drive device 10 adds an auxiliary driving force to the human driving force and transmits it to the wheel 12. The wheel 12 is connected to the vehicle body frame 13 via a suspension 14 so as to move up and down with respect to the drive device 10. In this specification, an electric vehicle capable of transmitting the human driving force to the wheel 12 regardless of performance (such as the magnitude of the auxiliary driving force) and dimensions is referred to as an “electric assist bicycle”.

[0011] FIG. 3 is a view showing an example of the drive device 10. The drive device 10 includes a first rotating electric machine MG1 having a first rotor Rm1. The drive device 10 includes a second rotating electric machine MG2 having a second rotor Rm2. The first rotating electric machine MG1 includes a first stator St1. The first stator St1 is fixed to a non-rotating member. The second rotating electric machine MG2 includes a second stator St2. The second stator St2 is fixed to a non-rotating member. In the present embodiment, the non-rotating member is the vehicle body frame 13.

[0012] Here, the "rotating electrical machine" is used as a concept that includes any of a motor (electric motor), a generator (dynamo), and a motor-generator that performs the functions of both a motor and a generator as required.

[0013] The drive device 10 includes an output member that is drivingly connected to the wheel 12. Examples of the "output member" include a differential input gear, a sprocket for chain drive, a counter gear, a rotating member that rotates integrally with the wheel, and the like. The wheel 12 includes a pair of drive wheels 12d that are spaced apart in the width direction Y of the electric assist bicycle 11. In the present embodiment, a differential input gear 61 described later is the output member. The differential input gear 61 is drivingly connected to the pair of drive wheels 12d. In the present embodiment, the rear wheel is the drive wheel 12d, but the front wheel may be the drive wheel 12d.

[0014] Here, "drivingly connected" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or two or more transmission members. Such transmission members include various members that transmit rotation at the same speed or with speed change, and for example, shafts, gear mechanisms, belts, chains, and the like are included. Further, as such a transmission member, an engagement device that selectively transmits rotation and a driving force, for example, a friction engagement device or a meshing engagement device, may be included. However, when one of the two rotating elements that are the object of "drivingly connected" is a rotating element of a differential gear mechanism, it refers to a state in which these two rotating elements are connected so as to be able to transmit a driving force without passing through the other rotating element of the differential gear mechanism.

[0015] The drive device 10 includes an input member to which a human driving force is input. Examples of the "input member" include a crankshaft, another rotating member that rotates in synchronization with the crankshaft, a pedal, the handle of a hand-pedaled bicycle, and the like. Here, the front-rear direction of the electric assist bicycle 11 is defined as the front-rear direction X, the width direction of the electric assist bicycle 11 is defined as the width direction Y, and the vertical direction is defined as the up-down direction Z. In the present embodiment, the crankshaft 21 disposed along the width direction Y of the electric assist bicycle 11 is the input member. The crankshaft 21 is rotatably supported by a support member 25 around the rotation axis A1 of the input member (around the crankshaft axis in the example shown in FIG. 3). The support member 25 is fixed to the vehicle body frame 13.

[0016] The drive device 10 includes a crank member 22 connected to rotate integrally with the crankshaft 21. The crank member 22 is arranged to extend in the radial direction, which is a direction orthogonal to the crankshaft axis (rotation axis A1) that is the rotation axis of the crankshaft 21. The drive device 10 includes a pedal 23. The pedal 23 is connected to the crank member 22 so as to be rotatable around an axis parallel to the crankshaft axis (rotation axis A1) at a position radially separated from the crankshaft axis (rotation axis A1) in the crank member 22. In the illustrated example, a pair of the crank member 22 and the pedal 23 are provided respectively.

[0017] The drive device 10 includes a transmission mechanism 30. The transmission mechanism 30 transmits a driving force between the crankshaft 21 and a differential gear mechanism 40 for distribution (described later). The transmission mechanism 30 includes a first input gear 31 and a second input gear 32 that meshes with the first input gear 31. The first input gear 31 is connected to rotate integrally with the crankshaft 21. The transmission mechanism 30 includes a third input gear 33 and a fourth input gear 34 that meshes with the third input gear 33. In the present embodiment, the first input gear 31, the second input gear 32, the third input gear 33, and the fourth input gear 34 are bevel gears.

[0018] The transmission mechanism 30 includes a transmission member 35. In the present embodiment, the transmission member 35 is a rotating shaft member and is arranged coaxially with the second input gear 32 and the third input gear 33. The transmission member 35, the second input gear 32, and the third input gear 33 are connected so as to rotate integrally with each other. In this way, since the second input gear 32, the third input gear 33, and the transmission member 35 are arranged coaxially, it is easy to reduce the size of the transmission mechanism 30 in the width direction.

[0019] In the present embodiment, the transmission mechanism 30 is configured to transmit a driving force between the crankshaft 21 and a second rotating element 42 (described later). The fourth input gear 34 is connected so as to rotate integrally with the second rotating element 42. Note that the transmission mechanism 30 may be configured to transmit a driving force between the crankshaft 21 and the second rotating element 42 by including a chain and a sprocket without including a rotating shaft member.

[0020] The drive device 10 includes a differential gear mechanism 40 for distribution having a first rotating element 41, a second rotating element 42, and a third rotating element 43. The differential gear mechanism 40 for distribution is configured such that the order of the rotational speeds of the first rotating element 41, the second rotating element 42, and the third rotating element 43 is the same as the described order. Examples of the differential gear mechanism 40 for distribution include a single pinion type planetary gear mechanism, a double pinion type planetary gear mechanism, a compound planetary gear mechanism such as a Ravigneaux, a bevel gear type differential gear mechanism, and the like.

[0021] Here, the "order of rotational speeds" refers to the order of the rotational speeds in the rotational states of the respective rotating elements. The rotational speeds of the respective rotating elements change depending on the rotational state of the differential gear mechanism for distribution, but the order of the magnitudes of the rotational speeds of the respective rotating elements is constant because it is determined by the structure of the differential gear mechanism for distribution. Note that the "order of the rotational speeds of the respective rotating elements" is equal to the arrangement order in the speed diagram (collinear diagram, see FIG. 4) of the respective rotating elements.

[0022] FIG. 4 is a diagram showing an example of a speed diagram of the differential gear mechanism 40 for distribution. In FIG. 4, the input member is shown as "IN" and the output member is shown as "OUT". As shown in FIGS. 3 and 4, the first rotating element 41 is drivingly connected to the first rotor Rm1 of the first rotating electric machine MG1. The second rotating element 42 is drivingly connected to the input member (IN). The third rotating element 43 is drivingly connected to the output member (OUT) and the second rotor Rm2 of the second rotating electric machine MG2.

[0023] In this embodiment, the differential gear mechanism 40 for distribution is a planetary gear mechanism including a sun gear, a carrier, and a ring gear. In the example shown in FIGS. 3 and 4, the first rotating element 41 is the sun gear. The first rotating element 41 rotates integrally with the first rotor Rm1. The second rotating element 42 is the carrier. The third rotating element 43 is the ring gear. Λ shown in FIG. 4 is the ratio of the number of teeth of the sun gear to the number of teeth of the ring gear, that is, the distribution gear ratio.

[0024] The drive device 10 includes a first gear 51 that rotates integrally with the third rotating element 43. In this embodiment, the first gear 51 is an external gear that rotates integrally with the internal gear ring gear. In this embodiment, the first gear 51 overlaps the ring gear in a radial view, but it may not overlap.

[0025] The drive device 10 includes a counter gear mechanism 50. The counter gear mechanism 50 transmits the driving force between the third rotating element 43 and the output member (in the illustrated example, the differential input gear 61). The counter gear mechanism 50 includes a second gear 52 and a third gear 53. The second gear 52 meshes with the first gear 51. The third gear 53 meshes with the differential input gear 61. The third gear 53 is connected so as to rotate integrally with the second gear 52.

[0026] The drive device 10 includes a fourth gear 54 that rotates integrally with the second rotor Rm2. The fourth gear 54 meshes with any one of a first gear 51, a second gear 52, a third gear 53, and a differential input gear 61. In the present embodiment, the fourth gear 54 meshes with the second gear 52. In this way, the torque output by the second rotating electric machine MG2 can be amplified by the counter gear mechanism 50.

[0027] The drive device 10 includes an output differential gear mechanism 60. The output differential gear mechanism 60 includes a differential input gear 61 as an output member, and distributes the driving force transmitted to the differential input gear 61 to a pair of drive wheels 12d. In the present embodiment, the differential input gear 61 is a differential ring gear.

[0028] Here, one side of the direction of rotation around the rotation axis A1 of the input member (around the crank axis) is defined as the first input rotation side A1a, and the other side is defined as the second input rotation side A1b. Also, one side of the direction of rotation around the axis A2 of the differential gear mechanism 40 for distribution (in the example shown in FIG. 3, around the rotation axis of the first rotating element 41) is defined as the forward rotation side A2a, and the other side is defined as the reverse rotation side A2b. Further, one side of the direction of rotation around the rotation axis A3 of the output member (in the example shown in FIG. 3, around the rotation axis of the differential input gear 61) is defined as the first output rotation side A3a, and the other side is defined as the second output rotation side A3b.

[0029] In the present embodiment, the first input rotation side A1a is the rotation direction in which the pedal 23 descends on the front side X1 and ascends on the rear side X2 with respect to the rotation axis A1. The first output rotation side A3a is the direction in which the output member rotates so that the electric assist bicycle 11 moves forward. The drive device 10 is configured such that when the input member rotates on the first input rotation side A1a, the output member rotates on the first output rotation side A3a when the first rotating element 41 is non-rotating. In the illustrated example, when the input member rotates on the first input rotation side A1a, the drive device 10 is configured such that the second rotating element 42 rotates on the forward rotation side A2a, the third rotating element 43 rotates on the forward rotation side A2a when the first rotating element 41 is non-rotating, and the output member rotates on the first output rotation side A3a.

[0030] FIG. 5 is a diagram showing an example of the control device 75 of the drive device 10. The drive device 10 includes a first inverter 71 that drives the first rotating electrical machine MG1. The drive device 10 includes a second inverter 72 that drives the second rotating electrical machine MG2. The drive device 10 includes a power storage device 73. The power storage device 73 is electrically connected to both the first inverter 71 and the second inverter 72.

[0031] The drive device 10 includes a control device 75. The control device 75 controls the first inverter 71 and the second inverter 72. In the present embodiment, when the control device 75 detects an input driving force (for example, the torque of the pedal 23, the torque of the crankshaft 21, the torque of the transmission member 35, etc.), it generates an auxiliary driving force. The control device 75 has at least two modes out of the first mode, the second mode, and the third mode, and is configured to selectively execute one of them. In the present embodiment, the control device 75 has three modes: the first mode, the second mode, and the third mode.

[0032] In the first mode, the first rotating electrical machine MG1 generates electricity, supplies the electric power obtained by the generation to the power storage device 73, and the second rotating electrical machine MG2 generates an auxiliary driving force by using the electric power of the power storage device 73 to perform power running. In the present embodiment, the first mode is executed in a region where the first rotating element 41 rotates in the positive rotation side A2a (the region above 0 on the vertical axis in FIG. 4). In the first mode, the transmission of the driving force between the third rotating element 43 and the counter gear mechanism 50 may be interrupted and the third rotating element 43 may be fixed. Further, for example, the drive device 10 may further include a clutch that separates between the third rotating element 43 and the output member and the second rotor Rm2, and a brake that fixes the third rotating element 43.

[0033] In the second mode, at least the second rotating electrical machine MG2 generates electricity, supplies the electric power obtained by the generation to the power storage device 73, and transmits the negative torque generated by the generation to the output member. The second mode is performed, for example, during deceleration of the electric assist bicycle 11, during a braking operation by the operator of the electric assist bicycle 11, and the like. In the present embodiment, the drive device 10 is configured to be able to supply electric power from both the first rotating electrical machine MG1 and the second rotating electrical machine MG2 to the power storage device 73. Note that in the second mode, the first rotating electrical machine MG1 may not generate electricity.

[0034] In the third mode, both the first rotating electrical machine MG1 and the second rotating electrical machine MG2 generate an auxiliary driving force by performing power running using the electric power of the power storage device 73. In the present embodiment, the third mode is executed in a region where the first rotating element 41 rotates on the reverse rotation side A2b (the region below 0 on the vertical axis in FIG. 4). Further, the third mode is executed in a region where the second rotating element 42 rotates on the forward rotation side A2a (the region above 0 on the vertical axis in FIG. 4). Note that the third mode may be a mode executed in a state where the second rotating element 42 is stopped.

[0035] In FIG. 4, the directions of the torque Tmg1 of the first rotating electrical machine MG1, the torque Tmg2 of the second rotating electrical machine MG2, and the torque Th of the human power driving force input to the input member are each indicated by an arrow. In the illustrated example, in the first mode and the third mode, the torque Th is a torque in a direction that accelerates the rotation of the output member on the first output rotation side A3a.

[0036] In the first mode, the torque Tmg1 of the first rotating electrical machine MG1 functions as a reaction force receiver that supports the reaction force of the torque Th transmitted to the first rotating element 41. In the illustrated example, in the first mode, the torque Tmg1 of the first rotating electrical machine MG1 is a torque in a direction that decelerates the rotation of the first rotating element 41. In the first mode, the torque Tmg2 of the second rotating electrical machine MG2 is a torque in a direction that accelerates the rotation of the output member on the first output rotation side A3a.

[0037] Although not shown, in the second mode, the torque Tmg1 of the first rotating electric machine MG1 is a torque in a direction to decelerate the rotation of the output member on the first output rotation side A3a, and the first rotating electric machine MG1 generates electricity. In the second mode, the torque Tmg1 of the first rotating electric machine MG1 is a torque in a direction to decelerate the rotation of the first rotating element 41. Although not shown, in the second mode, the torque Tmg2 of the second rotating electric machine MG2 is a torque in a direction to decelerate the rotation of the output member on the first output rotation side A3a, and the second rotating electric machine MG2 generates electricity.

[0038] In the example shown in the figure, in the third mode, the torque Tmg1 of the first rotating electric machine MG1 is a torque in a direction to accelerate the rotation of the first rotating element 41 toward the reverse rotation side A2b. In the third mode, the torque Tmg1 of the first rotating electric machine MG1 is a torque in a direction to accelerate the rotation of the output member on the first output rotation side A3a. In the third mode, the torque Tmg2 of the second rotating electric machine MG2 is a torque in a direction to accelerate the rotation of the output member on the first output rotation side A3a.

[0039] Returning to FIG. 1, in the present embodiment, the first rotating electric machine MG1, the second rotating electric machine MG2, the differential gear mechanism 40 for distribution, the counter gear mechanism 50, the output member, and the differential gear mechanism 60 for output are mounted on the electric assist bicycle 11 as the drive unit 90. The drive unit 90 is mounted on the electric assist bicycle 11 so as to move up and down with respect to the wheel 12 by the suspension 14. Note that the drive unit 90 may be mounted on the electric assist bicycle 11 so as to move up and down with respect to the vehicle body frame 13 by the suspension 14 together with the drive wheel 12d.

[0040] As shown in FIG. 3, in the present embodiment, the axis A2 of the differential gear mechanism 40 for distribution, the rotation axis of the second rotor Rm2, the axis of the counter gear mechanism 50, and the axis of the differential gear mechanism 60 for output (the rotation axis A3 of the output member) are different axes from each other. Further, the rotation axis A1 of the input member, the axis A2 of the differential gear mechanism 40 for distribution, the rotation axis of the second rotor Rm2, the axis of the counter gear mechanism 50, and the rotation axis A3 of the output member are parallel axes to each other.

[0041] According to the above-described drive device 10, while keeping the rotation of the second rotating element 42 drivingly connected to the input member within a certain range, the rotational speed or torque transmitted to the drive wheel 12d can be changed. Further, for example, by providing a locking mechanism that makes the first rotor Rm1 of the first rotating electric machine MG1 non-rotatable, even when power supply to the second rotating electric machine MG2 becomes impossible, the vehicle can be run by the manual driving force from the input member. Further, for example, by providing the above-described locking mechanism, or by forming an active short circuit when an abnormality occurs in the first inverter 71 so that a braking force acts on the first rotor Rm1 of the first rotating electric machine MG1, even when an abnormality occurs in the first inverter 71, the electric assist bicycle 11 can be run by the manual driving force or the driving force of the second rotating electric machine MG2. Note that the active short circuit refers to a state of the inverter circuit formed by turning on some of the plurality of switching elements of the first inverter and turning off the remaining ones so that the current flowing through the coil of the first rotating electric machine MG1 passes through the first inverter and returns to the coil.

[0042] 〔Second Embodiment〕 Hereinafter, the drive device 10 according to the second embodiment will be described with reference to FIGS. 6 and 7. Hereinafter, the description will focus on the differences from the first embodiment. Note that points not particularly described are the same as those in the first embodiment.

[0043] In the present embodiment, the electric assist bicycle 11 is a two-wheeled bicycle. The drive wheel 12d is a rear wheel. In the present embodiment, the transmission mechanism 30 includes a chain as a transmission member 35, a first sprocket as a first input gear 31, and a second sprocket as a fourth input gear 34. The first input gear 31 is connected so as to rotate integrally with the crankshaft 21. The fourth input gear 34 is connected so as to rotate integrally with the second rotating element 42. Note that the transmission mechanism 30 of the present embodiment may have the same configuration as the transmission mechanism 30 of the first embodiment.

[0044] The first rotor Rm1 of the first rotating electric machine MG1 is connected so as to rotate integrally with the first rotating element 41. The first stator St1 of the first rotating electric machine MG1 is connected to the vehicle body frame 13 so as to be non-rotatable about the rotation axis of the first rotor Rm1 (in the illustrated example, about the rotation axis A3 of the output member). The outer peripheral surface of the first stator St1 is covered by the first cover Cm1. The first stator St1 is connected to the vehicle body frame 13 via the first cover Cm1. The first rotor Rm1 and the first stator St1 are covered by the first cover Cm1 on the side opposite to the second rotating electric machine MG2 in the width direction Y.

[0045] The second rotor Rm2 of the second rotating electric machine MG2 is connected so as to rotate integrally with the third rotating element 43. The second stator St2 of the second rotating electric machine MG2 is connected to the vehicle body frame 13 so as to be non-rotatable about the rotation axis of the second rotor Rm2 (in the illustrated example, about the rotation axis A3 of the output member). The outer peripheral surface of the second stator St2 is covered by the second cover Cm2. The second stator St2 is connected to the vehicle body frame 13 via the second cover Cm2. The second rotor Rm2 and the second stator St2 are covered by the second cover Cm2 on the side opposite to the first rotating electric machine MG1 in the width direction Y.

[0046] In the present embodiment, at least one of the first rotating electric machine MG1 and the second rotating electric machine MG2 is disposed between the pair of vehicle body frames 13 in the width direction Y. In the illustrated example, both the first rotating electric machine MG1 and the second rotating electric machine MG2 are disposed between the pair of vehicle body frames 13 in the width direction Y. In the present embodiment, the axis A2 of the differential gear mechanism 40 for distribution, the rotation axis A3 of the output member, the rotation axis of the first rotor Rm1, and the rotation axis of the second rotor Rm2 are the same axis, but any one of them may be a different axis, or all of them may be different axes.

[0047] The differential gear mechanism 40 for distribution is disposed between the pair of vehicle body frames 13 in the width direction Y. In the present embodiment, the differential gear mechanism 40 for distribution is disposed between the first rotor Rm1 of the first rotating electric machine MG1 and the second rotor Rm2 of the second rotating electric machine MG2 in the width direction Y.

[0048] In the present embodiment, the first rotating electric machine MG1, the second rotating electric machine MG2, the differential gear mechanism 40 for distribution, and the output member are mounted on the electric assist bicycle 11 as a drive unit 90. The drive unit 90 is connected to the vehicle body frame 13 via a suspension (not shown) so as to move up and down with respect to the vehicle body frame 13 together with the drive wheel 12d. In the present embodiment, the drive unit 90 is disposed between the pair of vehicle body frames 13 in the width direction Y.

[0049] 〔Other Embodiments〕 Next, other embodiments of the drive device 10 will be described.

[0050] (1) In the above embodiment, the configuration in which the first rotor Rm1 rotates integrally with the first rotating element 41 and the first gear 51 rotates integrally with the third rotating element 43 has been described as an example. However, the present invention is not limited to such an example. For example, a gear meshing with the first rotating element 41 may be provided on the first rotor Rm1. Further, for example, the first gear 51 may be a gear meshing with the third rotating element 43. Further, for example, the drive device 10 may be configured not to include any one or all of the first gear 51, the fourth gear 54, and the counter gear mechanism 50.

[0051] (2) In the above-described embodiment, the control device 75 having three modes of a first mode, a second mode, and a third mode has been described as an example. However, without being limited to such an example, for example, the control device 75 may have a configuration having two modes of a first mode and a second mode or a third mode. Further, for example, the control device 75 may have a configuration having only any one of the first mode, the second mode, and the third mode. Further, for example, the control device 75 may have a configuration having only a mode different from all of the first mode, the second mode, and the third mode. Further, for example, the drive device 10 may have a configuration not including any one or all of the first inverter 71, the second inverter 72, and the power storage device 73.

[0052] (3) In the above-described embodiment, the first rotating element 41 is a sun gear, the second rotating element 42 is a carrier, the third rotating element 43 is a ring gear, and the fourth gear 54 meshes with the second gear 52 have been described as an example. However, without being limited to such an example, for example, the third rotating element 43 may be a sun gear or a carrier. Further, for example, the third gear 53 may be configured not to rotate integrally with the second gear 52. Further, for example, the fourth gear 54 may be configured such that the driving force is transmitted without directly meshing with any one of the first gear 51, the second gear 52, the third gear 53, and the differential input gear 61. Further, for example, the drive device 10 may have a configuration not including any one or all of the first gear 51, the counter gear mechanism 50, the fourth gear 54, and the output differential gear mechanism 60.

[0053] (4) In the above-described embodiment, the drive device 10 having the crankshaft 21, the crank member 22, the pedal 23, and the transmission mechanism 30 has been described as an example. However, without being limited to such an example, for example, the drive device 10 may have a configuration not including any one or all of the crankshaft 21, the crank member 22, the pedal 23, and the transmission mechanism 30.

[0054] (5) In the above-described embodiment, the rotation axis A1 of the input member and the axis A2 of the differential gear mechanism 40 for distribution are different from each other and parallel to each other, and this configuration has been described as an example. However, without being limited to such an example, for example, any one or all of the rotation axis A1 of the input member, the rotation axis of the second rotor Rm2, the axis of the counter gear mechanism 50, and the rotation axis A3 of the output member may be the same axis as the axis A2 of the differential gear mechanism 40 for distribution. Further, for example, any one or all of the rotation axis A1 of the input member, the rotation axis of the second rotor Rm2, the axis of the counter gear mechanism 50, and the rotation axis A3 of the output member may not be parallel to the axis A2 of the differential gear mechanism 40 for distribution. Further, for example, the rotation axis of the first rotor Rm1 and the axis A2 of the differential gear mechanism 40 for distribution may not be the same and may not be parallel.

[0055] Summary of the above embodiment Hereinafter, a drive device for an electric assist bicycle according to the present disclosure will be described.

[0056] In one aspect, a drive device (10) for an electric assist bicycle is a drive device (10) for an electric assist bicycle that is attached to a vehicle body frame (13) of an electric assist bicycle (11) and adds an auxiliary driving force to a human driving force and transmits it to a wheel, and includes an input member (21) to which a human driving force is input, an output member (61) that is drivingly connected to the wheel, a first rotating electric machine (MG1) including a first rotor (Rm1), a second rotating electric machine (MG2) including a second rotor (Rm2), a first rotating element (41), a second rotating element (42), and a third rotating element (43), and is configured such that the order of the rotational speeds of the first rotating element (41), the second rotating element (42), and the third rotating element (43) is the described order, and a differential gear mechanism (40) for distribution. The first rotating element (41) is drivingly connected to the first rotor (Rm1), the second rotating element (42) is drivingly connected to the input member (21), and the third rotating element (43) is drivingly connected to the output member (61) and the second rotor (Rm2).

[0057] According to this configuration, by controlling the rotational speed of the first rotor (Rm1), the ratio of the rotational speed of the output member (61) to the rotational speed of the input member (21) can be changed. Therefore, since there is no need to switch between a plurality of speed stages like a general bicycle transmission, the change in the speed ratio can be smoothly performed. Also, according to this configuration, by controlling the torques of the two rotary electric machines, the magnitude of the auxiliary driving force with respect to the human driving force can be changed. Therefore, compared with a general electric assist bicycle (11), it is easy to improve the comfort for the operator who operates the bicycle.

[0058] As one aspect, a drive device (10) for an electric assist bicycle includes a first inverter (71) that drives a first rotary electric machine (MG1), a second inverter (72) that drives a second rotary electric machine (MG2), a power storage device (73) electrically connected to both the first inverter (71) and the second inverter (72), and a control device (75) that controls the first inverter (71) and the second inverter (72). The control device (75) has at least two modes, namely a first mode, a second mode, and a third mode, and is configured to selectively execute one of them. In the first mode, the first rotary electric machine (MG1) generates electricity and supplies the electric power obtained by the power generation to the power storage device (73), and the second rotary electric machine (MG2) generates an auxiliary driving force by performing power running using the electric power of the power storage device (73). In the second mode, at least the second rotary electric machine (MG2) generates electricity, supplies the electric power obtained by the power generation to the power storage device (73), and transmits the negative torque generated by the power generation to the output member (61). In the third mode, both the first rotary electric machine (MG1) and the second rotary electric machine (MG2) generate an auxiliary driving force by performing power running using the electric power of the power storage device (73), which is preferable.

[0059] According to this configuration, by appropriately selecting a mode according to the driving situation of the electric assist bicycle (11), it is possible to improve the comfort for the operator and also improve the overall energy efficiency of the electric assist bicycle (11). Specifically, in the first mode, a part of the human driving force is used to generate electricity in the first rotating electric machine (MG1), and the second rotating electric machine (MG2) is driven by using the electric power of the power storage device (73) including the electric power obtained by the power generation, so that the assistance for the human driving force can be appropriately performed according to the driving situation. In the second mode, since the second rotating electric machine (MG2) can be used to generate electricity by utilizing the inertia of the electric assist bicycle (11), the kinetic energy of the electric assist bicycle (11) can be recovered and the power storage device (73) can be charged during downhill or deceleration. In the third mode, in a situation where a large auxiliary driving force is required, such as during uphill climbing, both the first rotating electric machine (MG1) and the second rotating electric machine (MG2) are driven to increase the auxiliary driving force.

[0060] As one aspect, the wheel (12) includes a pair of drive wheels (12d) arranged apart in the width direction Y of the electric assist bicycle (11), and the electric assist bicycle drive device (10) includes a differential input gear (61) as an output member, and an output differential gear mechanism (60) that distributes the driving force transmitted to the differential input gear (61) to the pair of drive wheels, and a counter gear mechanism (50) that transmits the driving force between the third rotating element (43) and the differential input gear (61). The distribution differential gear mechanism (40) is a planetary gear mechanism including a sun gear (41), a carrier (42), and a ring gear (43). The third rotating element (43) is the ring gear (43), and an external gear first gear (51) is provided so as to rotate integrally with the internal gear ring gear (43). The counter gear mechanism (50) includes a second gear (52) meshing with the first gear (51), and a third gear (53) connected so as to rotate integrally with the second gear (52) and meshing with the differential input gear (61). A fourth gear (54) rotating integrally with the second rotor (Rm2) meshes with any one of the first gear (51), the second gear (52), the third gear (53), and the differential input gear (61).

[0061] According to this configuration, it is possible to adopt a four-axis configuration in which the differential gear mechanism (40) for distribution, the counter gear mechanism (50), the differential gear mechanism (60) for output, and the second rotating electric machine (MG2) are arranged on different axes. Therefore, it is easier to reduce the size in the width direction (Y) compared to a configuration in which these are arranged on the same axis.

[0062] As one aspect, the drive device (10) for an electric assist bicycle includes a crankshaft (21) as an input member arranged along the width direction of the electric assist bicycle (11), and a crankshaft member (22) arranged so as to extend in the radial direction, which is a direction orthogonal to the crankshaft axis (A1) that is the rotation axis of the crankshaft (21), and connected so as to rotate integrally with the crankshaft (21). A pedal (23) is connected to the crankshaft member (22) so as to be rotatable about an axis parallel to the crankshaft axis (A1) at a position radially separated from the crankshaft axis (A1) in the crankshaft member (22). The drive device further includes a transmission mechanism (30) that transmits a driving force between the crankshaft (21) and the second rotating element (42).

[0063] According to this configuration, it is possible to convert the stepping force applied to the pedal (23) of the operator who operates the electric assist bicycle (11) into a rotational driving force and output it, and it is possible to appropriately transmit the rotational driving force to the differential gear mechanism (40) for distribution. Further, according to this configuration, even when the crankshaft (21) and the differential gear mechanism (40) for distribution are separated in the front-rear direction (X) of the electric assist bicycle (11), it is possible to appropriately transmit the driving force between the crankshaft (21) and the differential gear mechanism (40) for distribution.

[0064] The drive device for an electric assist bicycle according to the present disclosure only needs to be able to exhibit at least one of the above-described effects.

Description of Reference Numerals

[0065] 10: Driving device (driving device for an electric assist bicycle), 11: Electric assist bicycle, 12: Wheel, 12d: Driving wheel, 13: Vehicle body frame, 21: Crankshaft (input member), 22: Crank member, 23: Pedal, 30: Transmission mechanism, 40: Differential gear mechanism for distribution, 41: First rotating element, 42: Second rotating element, 43: Third rotating element, 50: Counter gear mechanism, 51: First gear, 52: Second gear, 53: Third gear, 54: Fourth gear, 60: Differential gear mechanism for output, 61: Differential input gear (output member), 71: First inverter, 72: Second inverter, 73: Power storage device, 75: Control device, MG1: First rotating electric machine, MG2: Second rotating electric machine, Rm1: First rotor, Rm2: Second rotor

Claims

1. A drive device for an electric assist bicycle that is attached to the body frame of an electric assist bicycle and adds an auxiliary driving force to the human driving force and transmits it to the wheels, comprising: an input member to which the human driving force is input; an output member that is drivingly connected to the wheels; a first rotating electric machine having a first rotor; a second rotating electric machine having a second rotor; a differential gear mechanism for distribution including a first rotating element, a second rotating element, and a third rotating element, configured such that the order of the rotational speeds of the first rotating element, the second rotating element, and the third rotating element is the same as the described order; the first rotating element is drivingly connected to the first rotor; the second rotating element is drivingly connected to the input member; the third rotating element is drivingly connected to the output member and the second rotor, a drive device for an electric assist bicycle.

2. a first inverter that drives the first rotating electric machine; a second inverter that drives the second rotating electric machine; a power storage device electrically connected to both the first inverter and the second inverter; a control device that controls the first inverter and the second inverter; comprising the control device has at least two modes among a first mode, a second mode, and a third mode, and is configured to selectively execute one of them; in the first mode, the first rotating electric machine generates electricity, supplies the electric power obtained by the power generation to the power storage device, and the second rotating electric machine generates the auxiliary driving force by performing power running using the electric power of the power storage device; in the second mode, at least the second rotating electric machine generates electricity, supplies the electric power obtained by the power generation to the power storage device, and transmits the negative torque generated by the power generation to the output member; in the third mode, both the first rotating electric machine and the second rotating electric machine generate the auxiliary driving force by performing power running using the electric power of the power storage device, the drive device for an electric assist bicycle according to Claim 1.

3. the wheels include a pair of drive wheels arranged spaced apart in the width direction of the electric assist bicycle; an output differential gear mechanism including a differential input gear as the output member, and distributing the driving force transmitted to the differential input gear to the pair of drive wheels; a counter gear mechanism that transmits the driving force between the third rotating element and the differential input gear; further comprising the differential gear mechanism for distribution is a planetary gear mechanism including a sun gear, a carrier, and a ring gear The third rotating element is the ring gear, and a first gear with external teeth is provided so as to rotate integrally with the ring gear with internal teeth. The counter gear mechanism includes a second gear meshing with the first gear, and a third gear connected so as to rotate integrally with the second gear and meshing with the differential input gear. The drive device for an electric assist bicycle according to claim 1 or 2, wherein a fourth gear rotating integrally with the second rotor meshes with any one of the first gear, the second gear, the third gear, and the differential input gear.

4. A crankshaft as the input member arranged along the width direction of the electric assist bicycle, a crank member arranged so as to extend in a radial direction which is a direction orthogonal to the crankshaft axis which is the rotation axis of the crankshaft, and connected so as to rotate integrally with the crankshaft, a pedal rotatably connected to the crank member about an axis parallel to the crankshaft axis at a position spaced from the crankshaft axis in the radial direction in the crank member, and a transmission mechanism for transmitting a driving force between the crankshaft and the second rotating element. The drive device for an electric assist bicycle according to claim 1 or 2, further comprising the above.

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