Drive unit

Abstract

To suppress increase in size in a radial direction.SOLUTION: A centrifugal clutch device transmits torque output by an electric motor in a blockable manner, A control part controls the electric motor based on a throttle opening detected by an opening sensor and a vehicle speed detected by a vehicle speed sensor. A cam mechanism of the centrifugal clutch device moves a pressure plate toward a clutch part when a first rotation member and the pressure plate relatively rotate. The control part stops the electric motor for a predefined period of time when it is determined that the throttle opening detected by the opening sensor is equal to or more than a first threshold value and the vehicle speed detected by the vehicle speed sensor is equal to or less than a second threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive unit. [Background technology]

[0002] In recent years, motorcycles using electric motors as a drive source have been proposed. In such electric motorcycles, the rotation speed of the electric motor is reduced to increase the torque and transmit it to the drive wheels (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-171404 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to increase the torque at start-up and enable high-speed driving without increasing the size of the electric motor, it is preferable to combine a transmission mechanism with the electric motor. However, combining a transmission mechanism can cause a problem of increasing the radial dimension. Therefore, an object of the present invention is to provide a drive unit that can suppress the increase in the radial dimension. [Means for solving the problem]

[0005] A drive unit according to a first aspect includes an electric motor, a shaft, a centrifugal clutch, an opening sensor, a vehicle speed sensor, and a control unit. The shaft is configured to rotate by a torque output by the electric motor. The centrifugal clutch device is attached to the shaft. The centrifugal clutch device is configured to transmit the torque output by the electric motor in an interruptable manner. The opening sensor is configured to detect a throttle opening. The vehicle speed sensor is configured to detect a vehicle speed. The control unit is configured to control the electric motor based on the throttle opening detected by the opening sensor and the vehicle speed detected by the vehicle speed sensor. The centrifugal clutch device has a first rotating member, a second rotating member, a clutch unit, a pressure plate, a centrifugal element, and a cam mechanism. The first rotating member is arranged to rotate integrally with the shaft. The second rotating member is arranged to be rotatable relative to the first rotating member. The clutch unit is configured to transmit torque in an interruptable manner between the first rotating member and the second rotating member. The pressure plate is arranged to be axially movable. The centrifugal element is configured to rotate integrally with the first rotating member. The centrifugal element is configured to receive centrifugal force and press the clutch portion via the pressure plate. The cam mechanism has a first assist cam surface and a second assist cam surface. The first assist cam surface is formed on the first rotating member. The second assist cam surface is formed on the pressure plate so as to face the first assist cam surface. The cam mechanism is configured to move the pressure plate toward the clutch portion when the first rotating member and the pressure plate rotate relative to each other. The control unit is configured to stop the electric motor for a predetermined time when it is determined that the throttle opening detected by the opening sensor is equal to or greater than a first threshold and the vehicle speed detected by the vehicle speed sensor is equal to or less than a second threshold.

[0006] According to this configuration, since the pressing force of the pressure plate by the cam mechanism of the centrifugal clutch device can be increased, the torque capacity can be ensured without increasing the size of the centrifugal clutch device. In other words, the radial size of the drive unit can be suppressed. In detail, if the pressing force of the pressure plate by the cam mechanism of the centrifugal clutch device is increased, the clutch unit may not be in the clutch-off state even if the rotation speed of the first rotating member decreases and the pressing force of the centrifugal element on the pressure plate disappears. In contrast, in the above configuration, when the throttle opening is equal to or greater than the first threshold value and the vehicle speed is equal to or less than the second threshold value, the control unit stops the electric motor for a predetermined time. Therefore, since the pressing force of the cam mechanism on the pressure plate disappears, the pressure plate can be moved in a direction away from the clutch unit to enter the clutch-off state. In this way, in the above configuration, the pressing force of the pressure plate by the cam mechanism of the centrifugal clutch device can be increased.

[0007] A drive unit according to a second aspect is the drive unit according to the first aspect, further comprising a first gear train and a second gear train. The shaft includes a first shaft and a second shaft. The first shaft is configured to receive torque from an electric motor drive source. The first gear train is configured to transmit torque from the first shaft to the second shaft. The second gear train has a centrifugal clutch device. The second gear train is configured to transmit torque from the first shaft to the second shaft via the centrifugal clutch device. The second gear train has a smaller gear ratio than the first gear train.

[0008] A drive unit according to a third aspect is configured as follows in the drive unit according to the second aspect. The first gear train has a first gear, a second gear, and a first one-way clutch. The first gear is attached to the first shaft. The second gear meshes with the first gear. The second gear is attached to the second shaft. The first one-way clutch is configured to transmit torque from the first shaft to the second shaft. The second gear train has a third gear, a fourth gear, and a second one-way clutch. The third gear is attached to the first shaft. The fourth gear meshes with the third gear. The fourth gear is attached to the second shaft. The second one-way clutch is configured to transmit torque from the second shaft to the first shaft.

[0009] A drive unit according to a fourth aspect is the drive unit according to the third aspect, and is configured as follows: the first gear is configured to rotate integrally with the first shaft; the second gear is attached to the second shaft via a first one-way clutch; and the first one-way clutch is configured to transmit torque from the second gear to the second shaft.

[0010] A drive unit according to a fifth aspect is the drive unit according to the third or fourth aspect, and is configured as follows: the third gear is configured to rotate integrally with the first shaft; the fourth gear is configured to rotate integrally with the second rotating member; and the second one-way clutch is configured to transmit torque from the second shaft to the fourth gear.

[0011] A drive unit according to a sixth aspect is the drive unit according to the fifth aspect, and is configured as follows. The second one-way clutch has an inner ring and an outer ring. The inner ring is configured to rotate integrally with the second shaft. The outer ring is disposed radially outward from the inner ring. The fourth gear is integrally formed with the outer ring by a single member.

[0012] A power transmission device according to a seventh aspect is the power transmission device according to the second aspect, and is configured as follows: The first gear train has a first gear, a second gear, and a first one-way clutch. The first gear is attached to the first shaft. The second gear meshes with the first gear. The second gear is attached to the second shaft. The first one-way clutch is configured to transmit torque from the first shaft to the second shaft. The second gear train has a third gear and a fourth gear. The third gear is attached to the first shaft. The fourth gear meshes with the third gear. The fourth gear is attached to the second shaft so as to be unable to transmit torque.

[0013] A power transmission device according to an eighth aspect is the power transmission device according to the seventh aspect, and is configured as follows: The second gear train has a bearing disposed between the fourth gear and the second shaft. The fourth gear is attached to the second shaft only via the bearing.

[0014] A power transmission device according to a ninth aspect is the power transmission device according to the seventh or eighth aspect, and is configured as follows. The first gear is configured to rotate integrally with the first shaft. The second gear is attached to the second shaft via a first one-way clutch. The first one-way clutch is configured to transmit torque from the second gear to the second shaft.

[0015] A power transmission device according to a tenth aspect is the power transmission device according to any one of the seventh to ninth aspects, and is configured as follows: the third gear is configured to rotate integrally with the first shaft, and the fourth gear is configured to rotate integrally with the second rotating member.

[0016] The power transmission device according to an eleventh aspect is the power transmission device according to any one of the first to tenth aspects, and is configured as follows: The centrifugal clutch device has a regenerative cam mechanism. The regenerative cam mechanism is configured to move the pressure plate axially toward the clutch portion during deceleration.

[0017] A drive unit according to a twelfth aspect is the drive unit according to any one of the first to eleventh aspects, and is configured as follows: The assist coefficient of the cam mechanism is 1 or more. Effect of the Invention

[0018] According to the present invention, an increase in size in the radial direction can be suppressed. [Brief description of the drawings]

[0019] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] Schematic diagram of a cam mechanism. [Figure 4] 6 is a flowchart showing an example of a control method performed by a control unit. [Diagram 5] FIG. 11 is a schematic diagram of a drive unit according to a modified example. [Figure 6] FIG. 11 is a schematic diagram of a cam mechanism according to a modified example. [Figure 7] FIG. 11 is a schematic diagram of a drive unit according to a modified example. [Figure 8] FIG. 11 is a cross-sectional view of a centrifugal clutch according to a modified example. [Figure 9] FIG. 11 is a schematic diagram of a drive unit according to a modified example. [Figure 10] FIG. 11 is a schematic diagram of a cam mechanism according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The drive unit 100 according to this embodiment will be described below with reference to the drawings. In the following description, the axial direction is the direction in which the rotation axis O of the centrifugal clutch device 8 extends. The circumferential direction is the circumferential direction of a circle centered on the rotation axis O, and the radial direction is the radial direction of a circle centered on the rotation axis O.

[0021] <Drive unit> 1, the drive unit 100 includes an electric motor 101, a power transmission device 102, an opening sensor 103, a vehicle speed sensor 104, and a control unit 105. The drive unit 100 is mounted on, for example, an electric motorcycle. The drive unit 100 is configured to drive a drive wheel 120.

[0022] <Electric motor> The electric motor 101 is a drive source of the drive unit 100. The electric motor 101 drives the drive wheels 120 by receiving power from a battery or the like.

[0023] <Power transmission device> The power transmission device 102 is configured to transmit torque between the electric motor 101 and the drive wheels 120. That is, the power transmission device 102 is configured to transmit the torque output by the electric motor 101 to the drive wheels 120. In addition, the power transmission device 102 is configured to transmit the torque from the drive wheels 120 to the electric motor 101 during deceleration, and to activate regenerative braking.

[0024] The power transmission device 102 includes a shaft 10 , a first gear train 3 , and a second gear train 4 .

[0025] <Shaft> The shaft 10 is configured to rotate by torque output from the electric motor 101. The shaft 10 includes a first shaft 1 and a second shaft 2. The first shaft 1 is configured to receive torque from the electric motor 101, which is a drive source. The first shaft 1 is arranged to be rotatable. The first shaft 1 rotates integrally with, for example, the rotor of the electric motor 101. The first shaft 1 is arranged coaxially with the rotation axis of the electric motor 101.

[0026] The second shaft 2 is rotatably arranged. The second shaft 2 extends substantially parallel to the first shaft 1. The second shaft 2 is arranged downstream of the first shaft 1 in a torque transmission path from the electric motor 101 to the drive wheels 120. The second shaft 2 receives torque from the first shaft 1 via the first gear train 3 or the second gear train 4.

[0027] <First gear train> The first gear train 3 is configured to transmit torque from the first shaft 1 to the second shaft 2. The first gear train 3 is configured not to transmit torque from the second shaft 2 to the first shaft 1.

[0028] The first gear train 3 has a first gear 31, a second gear 32, and a first one-way clutch 33. The first gear 31 is attached to the first shaft 1. The first gear 31 rotates integrally with the first shaft 1. The first gear 31 is fixed to the first shaft 1. Note that the first gear 31 may be formed integrally with the first shaft 1 by a single member.

[0029] The second gear 32 is attached to the second shaft 2. In detail, the second gear 32 is attached to the second shaft 2 via a first one-way clutch 33. The second gear 32 meshes with the first gear 31.

[0030] The first one-way clutch 33 is configured to transmit torque from the first shaft 1 to the second shaft 2 during forward movement. In detail, the first one-way clutch 33 is configured to transmit torque from the second gear 32 to the second shaft 2.

[0031] For example, the first one-way clutch 33 has an inner ring, an outer ring, and a plurality of rollers. The inner ring of the first one-way clutch 33 is configured to rotate integrally with the second shaft 2. The outer ring of the first one-way clutch 33 is configured to rotate integrally with the second gear 32. Note that the outer ring of the first one-way clutch 33 may be integrally formed with the second gear 32 by a single member.

[0032] When the outer ring rotates faster than the inner ring, the rollers mesh with each other and transmit torque between the inner ring and the outer ring. On the other hand, when the inner ring rotates faster than the outer ring, the rollers disengage from each other and do not transmit torque between the inner ring and the outer ring. In this manner, the first one-way clutch 33 transmits torque from the first shaft 1 to the second shaft 2, but does not transmit torque from the second shaft 2 to the first shaft 1. In this embodiment, the rotational speed means the rotational speed of each member when the vehicle equipped with the drive unit 100 moves forward.

[0033] <Second gear train> The second gear train 4 is configured to have a smaller gear ratio than the first gear train 3. The second gear train 4 is configured to transmit torque from the first shaft 1 to the second shaft 2. In detail, the second gear train 4 transmits torque from the first shaft 1 to the second shaft 2 when the rotation speed becomes greater than a predetermined value. In detail, the second gear train 4 transmits torque from the first shaft 1 to the second shaft 2 when the rotation speed of a first rotating member 81 of a centrifugal clutch device 8 described later becomes greater than a predetermined value. The second gear train 4 is installed in parallel with the first gear train 3 between the first shaft 1 and the second shaft 2.

[0034] The second gear train 4 has a third gear 41, a fourth gear 42, a second one-way clutch 43, and a centrifugal clutch device 8. The second gear train 4 is configured to transmit torque from the first shaft 1 to the second shaft 2 via the centrifugal clutch device 8 in an interruptable manner.

[0035] The third gear 41 is attached to the first shaft 1. Specifically, the third gear 41 rotates integrally with the first shaft 1. The third gear 41 is fixed to the first shaft 1. The third gear 41 may be integrally formed with the first shaft 1 by a single member. The third gear 41 has a larger number of teeth than the first gear 31. Also, the third gear 41 has a larger diameter than the first gear 31.

[0036] The fourth gear 42 is attached to the second shaft 2. In detail, the fourth gear 42 is attached to the second shaft 2 via a second one-way clutch 43 and a centrifugal clutch device 8. The fourth gear 42 meshes with the third gear 41. The fourth gear 42 has fewer teeth than the second gear 32. In addition, the fourth gear 42 has a smaller diameter than the second gear 32.

[0037] The second one-way clutch 43 is configured to transmit torque from the second shaft 2 to the first shaft 1 during forward movement. In particular, the second one-way clutch 43 is configured to transmit torque from the second shaft 2 to the fourth gear 42. The second one-way clutch 43 is configured not to transmit torque from the first shaft to the second shaft 2. In other words, the second one-way clutch 43 does not transmit torque from the fourth gear 42 to the second shaft 2.

[0038] 2 is a cross-sectional view of the centrifugal clutch device 8 and the second one-way clutch 43. As shown in FIG.

[0039] The inner ring 431 is configured to rotate integrally with the second shaft 2. For example, the inner ring 431 has a splined hole, and the second shaft 2 is fitted into the splined hole of the inner ring 431.

[0040] The outer ring 432 is disposed radially outward from the inner ring 431. The outer ring 432 is configured to rotate integrally with the fourth gear 42. In this embodiment, the outer ring 432 is integrally formed with the fourth gear 42 by one member. The outer ring 432 may be configured by a member separate from the fourth gear 42 and fixed to rotate integrally with each other. The fourth gear 42 is rotatably supported by the second shaft 2 via a bearing 106.

[0041] Each roller 433 is disposed between the inner ring 431 and the outer ring 432. When the inner ring 431 rotates faster than the outer ring 432, each roller 433 meshes with the inner ring 431 and the outer ring 432, and transmits torque between the inner ring 431 and the outer ring 432. That is, the torque is transmitted from the inner ring 431 to the outer ring 432. On the other hand, when the outer ring 432 rotates faster than the inner ring 431, each roller 433 is released from meshing with the inner ring 431 and the outer ring 432, and does not transmit torque between the inner ring 431 and the outer ring 432. That is, the torque is not transmitted from the outer ring 432 to the inner ring 431. In this way, the second one-way clutch 43 transmits torque from the second shaft 2 to the first shaft 1, but does not transmit torque from the first shaft 1 to the second shaft 2.

[0042] <Centrifugal clutch device> The centrifugal clutch device 8 is attached to the shaft 10. In this embodiment, the centrifugal clutch device 8 is attached to the second shaft 2. The centrifugal clutch device 8 is configured to transmit the torque output by the electric motor 101 in an interruptable manner. The centrifugal clutch device 8 is configured to transmit the torque when the rotation speed of the centrifugal clutch device 8 becomes greater than a predetermined value. In detail, the centrifugal clutch device 8 is configured to transmit the torque when the rotation speed of the first rotating member 81 of the centrifugal clutch device 8 becomes greater than a predetermined value. That is, when the rotation speed of the first rotating member 81 becomes greater than a predetermined value, the centrifugal clutch device 8 is in a clutch-on state and transmits the torque. On the other hand, when the rotation speed of the first rotating member 81 is equal to or less than the predetermined value, the centrifugal clutch device 8 is in a clutch-off state and interrupts the torque transmission.

[0043] The centrifugal clutch device 8 includes a first rotating member 81 , a second rotating member 82 , a clutch portion 83 , a pressure plate 84 , a pressure-receiving member 85 , a centrifugal element 86 , and a cam mechanism 87 .

[0044] The first rotating member 81 is configured to rotate integrally with the second shaft 2. The first rotating member 81 is disk-shaped. The first rotating member 81 has a spline hole 811 that penetrates in the axial direction. The second shaft 2 is fitted into the spline hole 811.

[0045] The first rotating member 81 has a plurality of accommodating portions 812. The accommodating portions 812 are arranged on the outer periphery of the first rotating member 81. The accommodating portions 812 are arranged in the circumferential direction. The accommodating portions 812 are recesses that open toward the clutch portion 83. Of the surfaces that define the accommodating portions 812, the surface that faces the clutch portion 83 is a cam surface 813. The cam surface 813 faces in the axial direction and is inclined so as to face radially inward.

[0046] The second rotating member 82 is disposed so as to be rotatable relative to the first rotating member 81. The second rotating member 82 is configured so as to transmit torque between the second rotating member 82 and the first rotating member 81 via a clutch portion 83. The second rotating member 82 is configured so as to rotate integrally with the fourth gear 42. In detail, the second rotating member 82 is fixed to the fourth gear 42 by a bolt. Note that the second rotating member 82 may be configured integrally with the fourth gear 42 by a single member.

[0047] The second rotating member 82 has a disk portion 821 and a first cylindrical portion 822. The disk portion 821 has an opening in the center. The second one-way clutch 43 is disposed in the opening of the disk portion 821. The disk portion 821 is fixed to the fourth gear 42.

[0048] The first cylindrical portion 822 extends in the axial direction from the outer circumferential end of the disc portion 821. In detail, the first cylindrical portion 822 extends in the axial direction from the disc portion 821 toward the first rotating member 81. The first cylindrical portion 822 has a plurality of notches (not shown) extending in the axial direction. The plurality of notches are arranged in the circumferential direction.

[0049] The clutch portion 83 is configured to transmit torque in an interruptible manner between the first rotating member 81 and the second rotating member 82. When the clutch portion 83 is in a clutch-on state, the clutch portion 83 transmits torque between the first rotating member 81 and the second rotating member 82. On the other hand, when the clutch portion 83 is in a clutch-off state, the clutch portion 83 interrupts the transmission of torque between the first rotating member 81 and the second rotating member 82.

[0050] The clutch portion 83 has a plurality of first clutch discs 831 and second clutch discs 832. The first clutch discs 831 and the second clutch discs 832 are annular. The first clutch discs 831 and the second clutch discs 832 are disposed between the pressure plate 84 and the pressure-receiving member 85 in the axial direction. The first clutch discs 831 and the second clutch discs 832 are disposed alternately in the axial direction.

[0051] The first clutch disc 831 is movable in the axial direction but is unable to rotate relative to the second rotating member 82. That is, the first clutch disc 831 rotates integrally with the second rotating member 82. In detail, a plurality of engagement protrusions that protrude radially outward are formed on the outer periphery of the first clutch disc 831. The engagement protrusions mesh with notches formed in the first cylindrical portion 822 of the second rotating member 82. Friction materials 833 are attached to both sides of the first clutch disc 831.

[0052] The second clutch disc 832 has a plurality of engagement protrusions formed at its inner circumferential end portion, which protrude radially inward. The engagement protrusions mesh with grooves (not shown) formed in the pressure plate 84. Therefore, the second clutch disc 832 is movable in the axial direction with respect to the pressure plate 84 but is unable to rotate relative thereto. In other words, the second clutch disc 832 rotates integrally with the pressure plate 84.

[0053] The pressure plate 84 is disposed between the clutch portion 83 and the centrifugal element 86. The pressure plate 84 is disposed so as to be movable in the axial direction. The pressure plate 84 is configured to press the clutch portion 83 in the axial direction. Upon receiving the axial load from the centrifugal element 86 and the axial thrust from the cam mechanism 87, the pressure plate 84 moves in the axial direction toward the clutch portion 83 and presses the clutch portion 83. The pressure plate 84 is biased by a biasing member (not shown) so as to move away from the clutch portion 83 in the axial direction.

[0054] The pressure plate 84 is disposed so as to be rotatable relative to the first rotating member 81. The pressure plate 84 is also disposed so as to be rotatable relative to the second rotating member 82.

[0055] The pressure plate 84 has a first annular body portion 841 and a second cylindrical portion 842. The first annular body portion 841 extends in the circumferential direction. The first annular body portion 841 is disposed between the centrifugal element 86 and the clutch portion 83 in the axial direction.

[0056] The second cylindrical portion 842 extends in the axial direction from the inner peripheral end of the first annular main body portion 841. In detail, the second cylindrical portion 842 extends in the axial direction from the first annular main body portion 841 toward the second rotating member 82. The second cylindrical portion 842 is disposed inside the first cylindrical portion 822 in the radial direction. The clutch portion 83 is disposed between the first cylindrical portion 822 and the second cylindrical portion 842 in the radial direction. The second cylindrical portion 842 has a plurality of grooves (not shown) extending in the axial direction. The plurality of grooves are arranged in the circumferential direction.

[0057] The pressure-receiving member 85 is configured to cooperate with the pressure plate 84 to sandwich the clutch portion 83 in the axial direction. The pressure-receiving member 85 is fixed to the first rotating member 81. That is, the pressure-receiving member 85 rotates integrally with the first rotating member 81. Moreover, the pressure-receiving member 85 is immovable in the axial direction.

[0058] The pressure-receiving member 85 has a second annular main body portion 851 and a third cylindrical portion 852. The second annular main body portion 851 extends in the circumferential direction. The second annular main body portion 851 is disposed between the disk portion 821 and the clutch portion 83 in the axial direction. The clutch portion 83 is disposed between the first annular main body portion 841 and the second annular main body portion 851 in the axial direction. The second one-way clutch 43 is disposed radially inside the second annular main body portion 851.

[0059] The third cylindrical portion 852 extends in the axial direction from the inner circumferential end portion of the second annular main body portion 851. In detail, the third cylindrical portion 852 extends in the axial direction from the second annular main body portion 851 to the first rotating member 81. The third cylindrical portion 852 is fixed to the first rotating member 81. The third cylindrical portion 852 is disposed inside the second cylindrical portion 842 in the radial direction.

[0060] The centrifugal element 86 is configured to rotate integrally with the first rotating member 81. More specifically, the centrifugal element 86 is cylindrical. The centrifugal element 86 is disposed in the housing portion 812 of the first rotating member. The outer peripheral surface of the centrifugal element 86 abuts against the cam surface 813. The centrifugal element 86 is movable in the radial direction within the housing portion 812. Furthermore, the centrifugal element 86 is movable in the axial direction within the housing portion 812.

[0061] The centrifugal element 86 is configured to press the clutch portion 83 in the axial direction via the pressure plate 84 when it rotates together with the first rotating member 81 and receives centrifugal force. When the rotation speed of the first rotating member 81 becomes greater than a predetermined value, the centrifugal element 86 presses the clutch portion 83 so that the centrifugal clutch device 8 is in a clutch-on state. The centrifugal element 86 presses the clutch portion 83 via the pressure plate 84.

[0062] In detail, when the centrifugal element 86 rotates together with the first rotating member 81, it moves radially outward due to centrifugal force, and also moves in the axial direction due to the cam surface 813. The centrifugal element 86 moves in the axial direction so as to press the pressure plate 84 toward the clutch portion 83. In this embodiment, the centrifugal element 86 presses the pressure plate 84 via the intermediate plate 88. The intermediate plate 88 rotates integrally with the first rotating member 81. The intermediate plate 88 is attached to the first rotating member 81 so as to be axially movable.

[0063] The cam mechanism 87 is configured to assist the pressing of the centrifugal element 86 against the clutch portion 83. In detail, the cam mechanism 87 is configured to move the pressure plate 84 in the axial direction toward the clutch portion 83 when the first rotating member 81 and the pressure plate 84 rotate relative to each other, more specifically, when the pressure plate 84 rotates relative to the first rotating member 81 in the rotational direction. Note that the rotational direction refers to the rotational direction of each member when the vehicle on which the drive unit 100 is mounted moves forward.

[0064] 3, the cam mechanism 87 has a first assist cam surface 871 and a second assist cam surface 872. The first assist cam surface 871 is formed on the first rotating member 81. The first assist cam surface 871 faces in the direction opposite to the rotation direction and is inclined so as to face the pressure plate 84.

[0065] The second assist cam surface 872 is formed on the pressure plate 84. The second assist cam surface 872 faces the rotation direction and is inclined so as to face the first rotating member 81. The second assist cam surface 872 faces the first assist cam surface 871. In detail, the second assist cam surface 872 contacts the first assist cam surface 871. When the centrifugal element 86 presses the pressure plate 84 in the axial direction and torque is transmitted from the second rotating member 82 to the pressure plate 84 via the clutch portion 83, the pressure plate 84 rotates in the rotation direction relative to the first rotating member 81. As a result, the second assist cam surface 872 presses the first assist cam surface 871 in the axial direction, and the pressure plate 84 moves in the axial direction away from the first rotating member 81 and presses the clutch portion 83 in the axial direction.

[0066] The assist coefficient b of the cam mechanism 87 can be set to be equal to or greater than 1. The assist coefficient b of the cam mechanism 87 can be calculated by the following formula (1).

[0067]

number

[0068]

number

[0069] 1, the drive unit 100 has a drive shaft 11, a fifth gear 12, and a sixth gear 13. The fifth gear 12 is attached to the second shaft 2. The fifth gear 12 rotates integrally with the second shaft 2. The fifth gear 12 is disposed, for example, between the second gear 32 and the fourth gear 42.

[0070] Torque is transmitted to the drive shaft 11 from the second shaft 2. The sixth gear 13 is attached to the drive shaft 11. The sixth gear 13 rotates integrally with the drive shaft 11. The sixth gear 13 meshes with the fifth gear 12. A driving wheel 120 is attached to the drive shaft 11.

[0071] <Opening sensor, vehicle speed sensor, control unit> The opening sensor 103 is configured to detect the throttle opening. For example, the opening sensor 103 detects the rotation angle of a shaft of a throttle valve. The opening sensor 103 outputs data related to the detected throttle opening to the control unit 105. The opening sensor 103 is connected to the control unit 105 by wire or wirelessly.

[0072] The vehicle speed sensor 104 is configured to detect the speed of the vehicle in which the drive unit 100 is mounted. The vehicle speed sensor 104 outputs data relating to the detected vehicle speed to the control unit 105. The vehicle speed sensor 104 is connected to the control unit 105 by wire or wirelessly.

[0073] The control unit 105 is configured to control the electric motor 101 based on the throttle opening detected by the opening sensor 103 and the vehicle speed detected by the vehicle speed sensor 104. In detail, the control unit 105 determines whether the throttle opening is equal to or greater than a first threshold value based on data relating to the throttle opening obtained from the opening sensor 103.

[0074] Furthermore, the control unit 105 determines whether the vehicle speed is equal to or lower than a second threshold based on data relating to the vehicle speed acquired by the vehicle speed sensor 104. The control unit 105 is configured to stop the electric motor 101 for a predetermined time when it determines that the throttle opening is equal to or higher than the first threshold and the vehicle speed is equal to or lower than the second threshold. For example, the control unit 105 stops the electric motor 101 for 10 to 100 ms.

[0075] In this way, by the control unit 105 stopping the electric motor 101 for a predetermined time, the torque with which the second assist cam surface 872 presses the first assist cam surface 871 is eliminated. As a result, the pressure plate 84 can be reliably moved in a direction away from the clutch unit 83 by the biasing member. Therefore, even if the assist coefficient is set to a high value such as 1 or more, it is possible to prevent a situation in which the pressure plate 84 continues to press the clutch unit 83 even though the pressing force of the centrifugal element 86 has been released, that is, a situation in which the clutch unit 83 does not switch to the clutch-off state.

[0076] The control unit 105 is configured by, for example, a computer (for example, a microcomputer) equipped with a CPU (Central Processing Unit) and a ROM (Read Only Memory). The ROM stores programs for performing various calculations. The CPU executes the programs stored in the ROM. The control unit 105 is connected to the electric motor 101 by wire or wirelessly.

[0077] Fig. 4 is a flowchart illustrating an example of a control method of the control unit 105. As shown in Fig. 4, the control unit 105 first determines whether the throttle opening is equal to or greater than a first threshold value (step S1).

[0078] If the control unit 105 determines that the throttle opening is less than the first threshold (No in step S1), it repeats the process from step S1. On the other hand, if the control unit 105 determines that the throttle opening is equal to or greater than the first threshold (Yes in step S1), it next determines whether the vehicle speed is equal to or less than a second threshold (step S2).

[0079] When the control unit 105 determines that the vehicle speed exceeds the second threshold (No in step S2), it repeats the process from step S1. On the other hand, when the control unit 105 determines that the vehicle speed is equal to or less than the second threshold (Yes in step S2), it stops the electric motor 101 for a predetermined time (step S3). After stopping the electric motor 101 for the predetermined time, it drives the electric motor 101 (step S4). Note that the order of steps S1 and S2 may be reversed.

[0080] <Operation> In the drive unit 100 configured as above, first, when the vehicle speed is low, the torque output by the electric motor 101 is transmitted from the first shaft 1 to the second shaft 2 via the first gear train 3. Here, when the vehicle speed is low, the rotation speed of the first rotating member 81 of the centrifugal clutch device 8 is equal to or lower than a predetermined value, so that the centrifugal clutch device 8 is in a clutch-off state and the second gear train 4 does not transmit torque. In addition, since the rotation speed of the fourth gear 42 is higher than that of the second shaft 2, the second one-way clutch 43 does not transmit torque from the second shaft 2 to the fourth gear 42.

[0081] When the vehicle speed increases, the rotation speed of the first rotating member 81 of the centrifugal clutch device 8 exceeds a predetermined value, and the centrifugal clutch device 8 is in a clutch-on state. In detail, the pressing force of the centrifugal element 86 and the assisting force of the cam mechanism 87 press the clutch portion 83 sufficiently, so that the first clutch disk 831 and the second clutch disk 832 rotate integrally, and the clutch portion 83 is connected. As a result, torque is transmitted from the second rotating member 82 to the first rotating member 81 via the clutch portion 83. As a result, the torque output from the electric motor 101 to the first shaft 1 is transmitted to the second shaft 2 via the second gear train 4. Note that the second shaft 2 has a faster rotation speed than the second gear 32, so the first one-way clutch 33 does not transmit torque from the second gear 32 to the second shaft 2.

[0082] Furthermore, when the vehicle speed decreases to a low speed, the rotation speed of the first rotating member 81 of the centrifugal clutch device 8 becomes equal to or lower than a predetermined value, and the centrifugal clutch device 8 enters a clutch-off state. As a result, the torque output by the electric motor 101 is transmitted from the first shaft 1 to the second shaft 2 via the first gear train 3.

[0083] When the electric motor 101 stops and decelerates, the torque transmitted from the drive wheels 120 to the second shaft 2 is transmitted to the first shaft 1 via the second one-way clutch 43, rotating the electric motor 101. As a result, regenerative braking can be activated.

[0084] [Variations] Although the embodiment of the present invention has been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can basically be applied simultaneously.

[0085] (a) As shown in FIG. 5, the centrifugal clutch device 8 may be attached to the first shaft 1. In this case, a first rotating member 81 is attached to the first shaft 1. Also, a second rotating member 82 is configured to rotate integrally with a third gear 41. The third gear 41 is attached to the first shaft 1 via a second one-way clutch 43. The fourth gear 42 is attached so as to rotate integrally with the second shaft 2. The second one-way clutch 43 is attached to the first shaft 1. The second one-way clutch 43 is configured to transmit torque from the third gear 41 to the first shaft 1. The second one-way clutch 43 does not transmit torque from the first shaft 1 to the third gear 41.

[0086] 6, the first assist cam surface 871 faces the rotation direction and is inclined to face the pressure plate 84. The second assist cam surface 872 faces in the opposite direction to the rotation direction and is inclined to face the first rotating member 81.

[0087] 7, a first one-way clutch 33 may be attached to the first shaft 1. In this case, the first gear 31 is attached to the first shaft 1 via the first one-way clutch 33. The second gear 32 is attached so as to rotate integrally with the second shaft 2. The first one-way clutch 33 transmits torque from the first shaft 1 to the first gear 31.

[0088] (c) The centrifugal element 86 may be configured to swing about a swing axis. For example, as shown in FIG. 8, the centrifugal element 86 is attached to the first rotating member 81 via a swing pin 860. The centrifugal element 86 has a weight portion 861 and a pressing portion 862. When the centrifugal element 86 receives centrifugal force, it rotates counterclockwise in FIG. 8 about the swing pin 860. In detail, the weight portion 861 receives the centrifugal force and moves radially outward, and as a result, the pressing portion 862 moves so as to press the clutch portion 83.

[0089] (d) In the above embodiment, the second gear train 4 has the second one-way clutch 43, but the configuration of the second gear train 4 is not limited to this. For example, as shown in FIG. 9, the second gear train 4 does not need to have the second one-way clutch 43. That is, the fourth gear 42 is supported on the second shaft 2 without the second one-way clutch 43. The fourth gear 42 is attached to the second shaft 2 so as not to transmit torque. In this modification, the fourth gear 42 is attached to the second shaft 2 only through the bearing 106. The bearing 106 is disposed between the fourth gear 42 and the second shaft 2. In this manner, the fourth gear 42 is supported on the second shaft 2 so as not to transmit torque directly to the second shaft 2. The fourth gear 42 transmits torque to the second shaft 2 only through the centrifugal clutch 8.

[0090] In this modification, as shown in Fig. 10, the centrifugal clutch device 8 has a regenerative cam mechanism 89. The regenerative cam mechanism 89 is configured to transmit torque from the drive wheels 120 to the electric motor 101 via the centrifugal clutch device 8 during deceleration. In detail, during deceleration, the first rotating member 81 rotates relative to the pressure plate 84 in the rotational direction. During this deceleration, the regenerative cam mechanism 89 is configured to move the pressure plate 84 axially toward the clutch portion 83.

[0091] The regeneration cam mechanism 89 has a first regeneration cam surface 891 and a second regeneration cam surface 892. The first regeneration cam surface 891 is formed on the first rotating member 81. The first regeneration cam surface 891 faces the rotation direction and is inclined so as to face the pressure plate 84.

[0092] The second regeneration cam surface 892 is formed on the pressure plate 84. The second regeneration cam surface 892 faces the opposite direction to the rotation direction and is inclined to face the first rotating member 81. The second regeneration cam surface 892 faces the first regeneration cam surface 891. During deceleration, the first rotating member 81 rotates relative to the pressure plate 84 in the rotation direction. As a result, the first regeneration cam surface 891 presses the second regeneration cam surface 892 in the axial direction, and the pressure plate 84 moves axially away from the first rotating member 81 and presses the clutch portion 83 in the axial direction.

[0093] As described above, since the centrifugal clutch device 8 has the regenerative cam mechanism 89, it is possible to rotate the electric motor 101 during deceleration to generate electricity. [Explanation of symbols]

[0094] 1: First shaft 2: Second shaft 3: First gear train 31: 1st gear 32: 2nd gear 33: First one-way clutch 4: Second gear train 41: 3rd gear 42: 4th gear 43: Second one-way clutch 431: Internal 432: Outer ring 8: Centrifugal clutch device 81: First rotating member 82: Second rotating member 83: Clutch section 84: Pressure plate 86: Centrifugal core 87: Cam mechanism 871: First assist cam surface 872: 2nd assist cam surface 89: Regenerative cam mechanism 100: Drive unit 101: Electric motor 102: Power transmission device 103: Opening sensor 104: Vehicle speed sensor 105: Control unit

Claims

1. Electric motor and, A shaft configured to rotate by the torque output by the electric motor, A centrifugal clutch device attached to the shaft and configured to transmit the torque output by the electric motor in a way that can interrupt it, A throttle opening sensor configured to detect the throttle opening, A vehicle speed sensor configured to detect vehicle speed, A control unit is configured to control the electric motor based on the throttle opening detected by the throttle opening sensor and the vehicle speed detected by the vehicle speed sensor. Equipped with, The centrifugal clutch device is A first rotating member is arranged to rotate integrally with the shaft, A second rotating member is arranged to be rotatable relative to the first rotating member, A clutch portion configured to transmit torque intermittently between the first rotating member and the second rotating member, A pressure plate positioned to be movable in the axial direction, A centrifugal element configured to rotate integrally with the first rotating member and to receive centrifugal force and press the clutch portion via the pressure plate, A cam mechanism having a first assist cam surface formed on a first rotating member and a second assist cam surface formed on the pressure plate so as to face the first assist cam surface, configured to move the pressure plate toward the clutch portion when the first rotating member and the pressure plate rotate relative to each other, It has, The control unit is configured to stop the electric motor for a predetermined time when it determines that the throttle opening detected by the throttle opening sensor is equal to or greater than a first threshold, and the vehicle speed detected by the vehicle speed sensor is equal to or less than a second threshold. Drive unit.

2. Further comprising a first gear train and a second gear train, The aforementioned shaft is A first shaft configured to receive torque from the aforementioned electric motor, The second shaft and Includes, The first gear train is configured to transmit torque from the first shaft to the second shaft. The second gear train has the centrifugal clutch device and is configured to transmit torque from the first shaft to the second shaft via the centrifugal clutch device, and has a smaller gear ratio than the first gear train. The drive unit according to claim 1.

3. The first gear train is, A first gear attached to the first shaft, A second gear that meshes with the first gear and is attached to the second shaft, A first one-way clutch configured to transmit torque from the first shaft to the second shaft, It has, The aforementioned second gear train is A third gear attached to the first shaft, A fourth gear that meshes with the third gear and is attached to the second shaft, A second one-way clutch configured to transmit torque from the second shaft to the first shaft, Having, The drive unit according to claim 2.

4. The first gear is configured to rotate integrally with the first shaft, The second gear is attached to the second shaft via the first one-way clutch. The first one-way clutch is configured to transmit torque from the second gear to the second shaft. The drive unit according to claim 3.

5. The third gear is configured to rotate integrally with the first shaft, The fourth gear is configured to rotate integrally with the second rotating member, The second one-way clutch is configured to transmit torque from the second shaft to the fourth gear. The drive unit according to claim 3.

6. The second one-way clutch has an inner ring configured to rotate integrally with the second shaft, and an outer ring positioned radially outward from the inner ring. The fourth gear is integrally formed with the outer ring by a single component. The drive unit according to claim 5.

7. The first gear train is, A first gear attached to the first shaft, A second gear that meshes with the first gear and is attached to the second shaft, A first one-way clutch configured to transmit torque from the first shaft to the second shaft, It has, The aforementioned second gear train is A third gear attached to the first shaft, A fourth gear is attached to the second shaft in such a way that it meshes with the third gear and is unable to transmit torque, Having, The drive unit according to claim 2.

8. The second gear train has a bearing positioned between the fourth gear and the second shaft. The fourth gear is attached to the second shaft only via the bearing. The drive unit according to claim 7.

9. The first gear is configured to rotate integrally with the first shaft, The second gear is attached to the second shaft via the first one-way clutch. The first one-way clutch is configured to transmit torque from the second gear to the second shaft. The drive unit according to claim 7.

10. The third gear is configured to rotate integrally with the first shaft, The fourth gear is configured to rotate integrally with the second rotating member. The drive unit according to claim 7.

11. The centrifugal clutch device has a regenerative cam mechanism configured to move the pressure plate axially toward the clutch portion during deceleration. The drive unit according to claim 1.

12. The assist coefficient of the cam mechanism is 1 or greater. The drive unit according to claim 1.

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