Power transmission device, drive device, and vehicle

Abstract

This power transmission device transmits power, to an output shaft, from an input shaft to which power of a motor is inputted. The power transmission device comprises a low-speed gear mechanism and a high-speed gear mechanism, each of which forms a power transmission path between the input shaft and the output shaft. The high-speed gear mechanism includes a centrifugal clutch that couples, to the output shaft, the input shaft rotating at a prescribed rotation rate or higher in the forward rotation direction. The low-speed gear mechanism includes: a first one-way clutch that couples, to the output shaft, the input shaft rotating at a rotation rate lower than the prescribed rotation rate in the forward rotation direction; a second one-way clutch that couples, to the output shaft, the input shaft rotating at a rotation rate lower than the prescribed rotation rate in the reverse rotation direction; and a clutch mechanism that disconnects the second one-way clutch from the output shaft to which the input shaft is coupled via the high-speed gear mechanism.

Description

Power transmission device, drive device, and vehicle

[0001] The present invention relates to a power transmission device, a drive device, and a vehicle.

[0002] In Patent Document 1, in an automatic transmission having a low-speed transmission system and a high-speed transmission system that respectively form power transmission paths between the crankshaft of an engine and the main shaft, the main shaft is connected to the low-speed transmission system via a one-way clutch, and the high-speed transmission system is connected to a centrifugal clutch. A configuration is disclosed.

[0003] Japanese Utility Model Publication No. 57-117430

[0004] In recent years, efforts to realize a low-carbon society or a decarbonized society have become active, and in vehicles as well, research and development on electrification technologies have been conducted in order to reduce CO2 emissions and improve energy efficiency. Generally, in an electric vehicle in which an engine is replaced with an electric motor, reverse travel is possible by rotating the motor in the reverse direction. However, when the automatic transmission disclosed in Patent Document 1 is applied to an electric vehicle, when the main shaft is rotated in the reverse direction, the one-way clutch does not engage, so the electric vehicle cannot be reversed.

[0005] Therefore, an object of the present invention is to provide a technology capable of transmitting power from an input shaft to an output shaft when the input shaft to which the power of a motor is input is rotated in each of the forward rotation direction and the reverse rotation direction. And by extension, it contributes to the improvement of energy efficiency.

[0006] To achieve the above objective, a power transmission device as one aspect of the present invention is a power transmission device that transmits power from an input shaft to which the power of a motor is input to an output shaft, and comprises a low-speed gear mechanism and a high-speed gear mechanism that each form a power transmission path between the input shaft and the output shaft, wherein the reduction ratio of the low-speed gear mechanism is higher than the reduction ratio of the high-speed gear mechanism, the high-speed gear mechanism includes a centrifugal clutch that connects the input shaft, which is rotating at a predetermined rotational speed or higher in the forward direction, to the output shaft, and the low-speed gear mechanism includes a first one-way clutch that connects the input shaft, which is rotating at less than the predetermined rotational speed in the forward direction, to the output shaft, a second one-way clutch that connects the input shaft, which is rotating at less than the predetermined rotational speed in the reverse direction, to the output shaft, and a clutch mechanism that disconnects the second one-way clutch from the output shaft to which the input shaft is connected via the high-speed gear mechanism.

[0007] According to the present invention, for example, when the input shaft to which the power of a motor is input is rotated in both the forward and reverse directions, it is possible to provide a technology that can transmit power from the input shaft to the output shaft, and furthermore, it is possible to improve energy efficiency.

[0008] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are given the same reference numeral.

[0009] The attached drawings are included in the specification and constitute a part thereof, illustrating embodiments of the present invention and are used to explain the principles of the present invention together with the description thereof. Figures: Figure showing an example of the configuration of an electric vehicle; Figure showing the internal structure of the drive unit of the first embodiment; Schematic diagram of the drive unit of the first embodiment; Figure showing an example of the configuration of a clutch mechanism; Figure showing an example of the operation of the clutch mechanism; Schematic diagram for explaining the operation of the drive unit of the first embodiment; Schematic diagram for explaining the operation of the drive unit of the first embodiment; Schematic diagram for explaining the operation of the drive unit of the first embodiment; Flowchart showing an example of the control of the drive unit; Figure showing the internal structure of the drive unit of the second embodiment; Schematic diagram of the drive unit of the second embodiment; Schematic diagram showing a modified example of the drive unit of the second embodiment; Schematic diagram showing a modified example of the drive unit of the second embodiment; Schematic diagram of the drive unit of the third embodiment.

[0010] Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and includes changes and modifications to the configuration within the scope of the spirit of the invention. Furthermore, not all combinations of features described in these embodiments are essential to the present invention. The same reference numeral is used for identical components, and their descriptions are omitted.

[0011] <First Embodiment> A first embodiment of the present invention will now be described. Figure 1 shows a left side view of the electric vehicle A of this embodiment (hereinafter sometimes simply referred to as vehicle A). In this embodiment, vehicle A is described using a scooter-type motorcycle equipped with a front wheel FW and a rear wheel RW as an example, but the present invention can be applied to any vehicle that uses an electric motor as a power source, including other types of motorcycles, saddle-type vehicles, or electric vehicles other than saddle-type vehicles (for example, four-wheeled vehicles).

[0012] Vehicle A is equipped with a seat 1 on which the driver sits, and a handle 2 for steering the front wheel FW is provided in front of the seat. The front wheel FW is pivotally supported at the lower end of the front fork 3, and the handle 2 is attached to the front fork 3 via a steering stem (not shown). The grip of the handle 2 (for example, the right grip) functions as an accelerator. The driver can operate the accelerator by rotating the grip of the handle 2. In addition, an operating section 4 for the driver to perform various operations on vehicle A and a meter unit 5 including a speedometer are provided near the handle 2. The operating section 4 may include an operator (for example, a switch) for switching between a forward mode that drives vehicle A forward and a reverse mode that drives vehicle A backward.

[0013] A floor section 6 is formed in the lower part between the seat 1 and the steering wheel 2. A high-output battery and the like are stored inside the floor section 6, and a control unit 13 and a low-output battery may be stored in the lower part of the seat 1. The control unit 13 is composed of a computer including a processor such as a CPU, a storage device such as semiconductor memory, and an interface with an external device, and controls the operation of vehicle A. In this embodiment, the control unit 13 is configured as, for example, an ECU (Electronic Control Unit) and / or a PCU (Power Control Unit), and can control the motor 11, which will be described later.

[0014] A cargo bed 7 is provided behind the seat 1. A swing unit 9 is also provided behind the seat 1 and below the cargo bed 7. The swing unit 9 is pivotally supported at its front end by the vehicle frame (not shown) and also pivotally supports the rear wheel RW. A rear shock unit 8 is provided between the rear end of the swing unit 9 and the rear frame (not shown) in the cargo bed 7, and the swing unit 9 is suspended by the rear shock unit 8.

[0015] The swing unit 9 is provided with a drive device 10 for driving the rear wheel RW. The drive device 10 includes a motor 11 (electric motor) and a power transmission unit 12 (power transmission device), and is covered by an external case. In a vehicle A equipped with the motor 11, the vehicle A can be moved backward by reversing the rotation direction of the motor 11 under the control of the control unit 13. Specifically, the control unit 13 rotates the motor 11 in the forward direction when moving the vehicle A forward, and rotates the motor 11 in the reverse direction when moving the vehicle A backward. The reverse direction is the direction of rotation opposite to the forward direction. Here, the drive device 10 may be understood to include the motor 11 and the power transmission unit 12, as well as the control unit 13 that controls the motor 11.

[0016] The power transmission unit 12 is a device that transmits power from the input shaft (e.g., the motor shaft) to which the power of the motor 11 is input, to the output shaft. The output shaft is connected to the axle of the rear wheel RW via a gear train. In this embodiment, the power transmission unit 12 is configured as an automatic transmission that transmits power from the input shaft, which is rotating in the forward direction, to the output shaft in multiple stages (e.g., two stages) when the vehicle A is moving forward, and also transmits power from the input shaft, which is rotating in the reverse direction, to the output shaft when the vehicle A is moving backward.

[0017] [Configuration of the drive unit] The configuration example of the drive unit 10 (power transmission unit 12) of this embodiment will be described below. Figure 2 shows the internal structure of the drive unit 10 of this embodiment, and Figure 3 shows a schematic diagram of the drive unit 10 of this embodiment.

[0018] The drive unit 10 is a device for driving the output shaft 22 and comprises a motor 11, a power transmission unit 12, an input shaft 21, and an output shaft 22. The input shaft 21 is connected to the motor shaft of the motor 11, and power is input from the motor 11. The input shaft 21 may be configured as the motor shaft of the motor 11. Power is transmitted to the output shaft 22 from the input shaft 21 via the power transmission unit 12. The drive unit 10 of this embodiment may also include a gear train 24 for transmitting the power of the output shaft 22 to the axle 23 of the drive wheel (e.g., rear wheel RW). The gear train 24 may include an input gear 24a attached to the output shaft 22 and an output gear 24b attached to the axle 23. The drive unit 10 of this embodiment may also directly transmit the power of the output shaft 22 to the axle 23 of the drive wheel (e.g., rear wheel RW).

[0019] The drive unit 10 is housed inside a transmission case (not shown). The input shaft 21, output shaft 22, and axle 23 are each rotatably supported by bearings (input bearing 25, output bearing 26, axle bearing 27) having an inner ring fixed to the shaft, an outer ring fixed to the transmission case, and rolling elements that slide and rotate between the inner and outer rings. The dimensions of the bearings, the number and location of bearings on the shafts, etc., may be appropriately changed according to the loads expected to act on the bearings. For example, three bearings may be placed on the input shaft, or bearings of different diameters may be placed on the input shaft.

[0020] The power transmission unit 12 has a low-speed gear mechanism 30 and a high-speed gear mechanism 40 that form power transmission paths between the input shaft 21 and the output shaft 22, respectively. The reduction ratio of the low-speed gear mechanism 30 is higher than the reduction ratio of the high-speed gear mechanism 40. In this embodiment, when the motor 11 rotates the input shaft 21 in the forward direction to move the vehicle A forward, the power transmission unit 12 transmits power from the input shaft 21 to the output shaft 22 in such a way that it automatically shifts between 1st gear (low speed) and 2nd gear (high speed). The power transmission unit 12 also transmits power from the input shaft 21 to the output shaft 22 when the motor 11 rotates the input shaft 21 in the reverse direction to move the vehicle A backward.

[0021] First, the high-speed gear mechanism 40 will be described. The high-speed gear mechanism 40 is a gear mechanism for connecting an input shaft 21, which is rotating at a predetermined rotational speed or higher, to an output shaft 22, and may include a gear train 41 and a centrifugal clutch 42. The gear train 41 has an input gear 41a directly attached to the input shaft 21 and an output gear 41b that is coupled to the input gear 41a. The output gear 41b is attached to the output shaft 22 via a centrifugal clutch 42.

[0022] The centrifugal clutch 42 is configured to engage when the input shaft 21 is rotating at a predetermined rotational speed or higher. The centrifugal clutch 42 includes, for example, a clutch inner 42a attached to the output gear 41b and a clutch outer 42b attached to the output shaft 22, as shown in Figure 3. A clutch shoe 42c (friction member, weight) is provided at the outer end of the clutch inner 42a. When the input shaft 21 rotates at a predetermined rotational speed or higher, the output gear 41b and the clutch inner 42a rotate accordingly, and the clutch shoe 42c moves outward due to centrifugal force and engages with the clutch outer 42b. Engagement of the centrifugal clutch 42 means that the clutch shoe 42c and the clutch outer 42b are engaged, and in this state, the power of the input shaft 21 is transmitted to the output shaft 22 (i.e., the output shaft 22 rotates). Here, the predetermined rotational speed is the rotational speed of the input shaft 21 when the centrifugal clutch 42 begins to engage.

[0023] Next, the low-speed gear mechanism 30 will be described. The low-speed gear mechanism 30 is a gear mechanism for connecting an input shaft 21, which is rotating at a speed less than a predetermined rotational speed, to an output shaft 22, and may include a gear train 31, a first one-way clutch 32, a second one-way clutch 33, and a clutch mechanism 34. The gear train 31 has an input gear 31a directly attached to the input shaft 21 and an output gear 31b that engages with the input gear 31a. The output gear 31b is attached to the output shaft 22 via the first one-way clutch 32 and the second one-way clutch 33.

[0024] The first one-way clutch 32 is configured to connect the input shaft 21 (specifically the output gear 31b) to the output shaft 22 when the input shaft 21 is rotating in the forward direction, but not to connect the input shaft 21 to the output shaft 22 when the input shaft 21 is rotating in the reverse direction. Furthermore, the first one-way clutch 32 is configured not to connect the input shaft 21 to the output shaft 22 even when the input shaft 21 is rotating in the forward direction at a predetermined rotational speed or higher. On the other hand, the second one-way clutch 33 has the opposite configuration to the first one-way clutch 32, connecting the input shaft 21 (specifically the output gear 31b) to the output shaft 22 when the input shaft 21 is rotating in the reverse direction, but not to connect the input shaft 21 to the output shaft 22 when the input shaft 21 is rotating in the forward direction.

[0025] Each of the first one-way clutch 32 and the second one-way clutch 33 may have an inner ring and an outer ring, and a general structure may be used in which the inner ring and the outer ring are locked together when one of the inner ring and the outer ring rotates relative to the other in a predetermined rotational direction. Hereinafter, the locking of the inner ring and the outer ring constituting the one-way clutch may be referred to as "fastening".

[0026] The clutch mechanism 34 is positioned between the second one-way clutch 33 and the output shaft 22, and is a mechanism for disengaging the second one-way clutch 33 from the output shaft 22, to which the input shaft 21 is connected via the high-speed gear mechanism 40. The clutch mechanism 34 is configured to connect the second one-way clutch 33 to the output shaft 22 when the input shaft 21 is rotating in the reverse direction.

[0027] Figure 3 illustrates the case where the clutch mechanism 34 is not provided (i.e., the output gear 31b is connected to the output shaft 22 only via the second one-way clutch and not via the clutch mechanism 34). In this case, when the forward rotation power of the motor 11 is transmitted from the input shaft 21 to the output shaft 22 via the high-speed gear mechanism 40, the output shaft 22 rotates faster than the output gear 31b because the reduction ratio of the low-speed gear mechanism is higher than the reduction ratio of the high-speed gear mechanism. At this time, the first one-way clutch does not engage, and the second one-way clutch 33 is engaged, forming two power transmission paths with different reduction ratios between the input shaft 21 and the output shaft. In other words, a power transmission path via the second one-way clutch 33 and a power transmission path via the high-speed gear mechanism 40 are formed, and the rotation of the power transmission unit 12 is restricted. In the power transmission unit 12 of this embodiment, a clutch mechanism 34 is provided to avoid such engagement of the second one-way clutch.

[0028] Figure 4 shows an example of the configuration of the clutch mechanism 34. The clutch mechanism 34 of this embodiment may include a cylindrical first member 34a through which the output shaft 22 passes, a second member 34b through which the first member 34a passes, and a third member 34c fixed to the output shaft 22. The third member 34c may be an input gear 24a of a gear train 24 that transmits power from the output shaft 22 to the axle 23.

[0029] The gear pair 34d, consisting of a gear provided on the side of the second member 34b and a gear provided on the side of the third member 34c opposite to it, is formed in a ratchet structure. Specifically, the gear pair 34d engages when the input shaft 21, which is rotating in the reverse direction, is connected to the output shaft 22 via the second one-way clutch 33, and is configured to rotate freely when the input shaft 21, which is rotating in the forward direction, is connected to the output shaft 22 via the first one-way clutch 32 or the high-speed gear mechanism 40.

[0030] Furthermore, grooves with a helical spline structure are provided on the outer circumference of the first member 34a and the inner circumference of the second member 34b, and the first member 34a and the second member 34b are helically spline engaged. This structure constitutes a drive mechanism 34e that drives the gear pair 34d to engage when connecting the input shaft 21, which is rotating in the reverse direction, to the output shaft 22 via the second one-way clutch 33. In this embodiment, the drive mechanism 34e may be configured to drive the second member 34b toward the third member 34c when connecting the input shaft 21, which is rotating in the reverse direction, to the output shaft 22 via the second one-way clutch 33.

[0031] By configuring the clutch mechanism 34 in this way, the second one-way clutch 33 can be disengaged from the output shaft 22 when the input shaft 21 is connected to the output shaft 22 via the high-speed gear mechanism 40. Furthermore, the second one-way clutch 33 can be connected to the output shaft 22 when the input shaft 21 is rotating in the reverse direction.

[0032] Figures 5A to 5B show examples of the operation of the clutch mechanism 34. Figures 5A to 5B show the structure of the clutch mechanism 34 and its surroundings, while other structures are not shown.

[0033] When the input shaft 21 is rotating in the reverse direction, as shown in Figure 5A, the power of the output gear 31b is transmitted to the first member 34a via the second one-way clutch 33, causing the first member 34a to rotate. In this case, the second member 34b is driven toward the third member 34c by the drive mechanism 34e having a helical spline structure. As a result, the gear pair 34d, which consists of a gear on the side of the second member 34 and a gear on the side of the third member 34c, engages, causing the output shaft 22 to which the third member 34c is fixed to rotate.

[0034] On the other hand, when the input shaft 21 is rotating in the forward direction, as shown in Figure 5B, the power of the input shaft 21 is transmitted to the output shaft 22 via the first one-way clutch 32 or the high-speed gear mechanism 40. In this case, the ratchet gear pair 34d rotates freely. Also, since the power of the output gear 31b is not transmitted to the first member 34 via the second one-way clutch 33, the second member 34b is not driven toward the third member 34c by the drive mechanism 34e. Therefore, the second one-way clutch 33 and the output shaft 22 are disconnected. Here, the clutch mechanism 34 may be provided with a spring structure 34f that provides friction to generate axial movement of the second member 34b by the helical spline.

[0035] [Operation of the Drive Unit] The operation of the drive unit 10 of this embodiment will be described below. Figures 6A to 6C are schematic diagrams illustrating the operation of the drive unit 10 of this embodiment. In Figures 6A to 6C, the axle 23 and gear train 24 are not shown, and elements not used in forming the power transmission path between the input shaft 21 and the output shaft 22 are shown with dashed lines.

[0036] Figure 6A shows the state in which the input shaft 21 is rotated in the forward direction by the motor 11 at a speed less than a predetermined number of revolutions (first gear state). In this state, the first one-way clutch 32 is engaged, and the centrifugal clutch 42 and the second one-way clutch 33 of the high-speed gear mechanism 40 are not engaged. Therefore, the power of the input shaft 21 is transmitted to the output shaft 22 via the gear train 31 and the first one-way clutch 32.

[0037] Figure 6B shows the state in which the input shaft 21 is rotated in the forward direction at a predetermined speed or higher by the motor 11 (second gear state). In this state, the centrifugal clutch 42 of the high-speed gear mechanism 40 is engaged, and the first one-way clutch 32 and the second one-way clutch 33 are not engaged. Therefore, the power from the input shaft 21 is transmitted to the output shaft 22 via the gear train 41 and the centrifugal clutch 42.

[0038] Figure 6C shows the state in which the input shaft 21 is rotated in the reverse direction by the motor 11 at a speed below a predetermined rotational speed (reverse state). In this state, the second one-way clutch 33 is engaged, and the centrifugal clutch 42 and the first one-way clutch 32 of the high-speed gear mechanism 40 are not engaged. Therefore, the power of the input shaft 21 is transmitted to the output shaft 22 via the gear train 31 and the second one-way clutch 33.

[0039] [Motor Control] The following describes an example of control of the drive device 10 by the control unit 13. When the motor 11 rotates the input shaft 21 in the reverse direction, if the rotational speed of the input shaft 21 is above a predetermined rotational speed, the centrifugal clutch 42 of the high-speed gear mechanism 40 is engaged, and two power transmission paths with different reduction ratios are formed between the input shaft 21 and the output shaft. In other words, a power transmission path via the first one-way clutch 32 and a power transmission path via the high-speed gear mechanism 40 are formed, and the reverse rotation of the drive device is restricted. To avoid this situation, when the input shaft 21 is rotated in the reverse direction, the control unit 13 controls the motor 11 so that the rotational speed of the input shaft 21 is below a predetermined rotational speed.

[0040] Figure 7 is a flowchart illustrating an example of the control of the drive unit 10. The flowchart in Figure 7 shows an example of the control of the drive unit 10 when driving vehicle A in reverse, and can be executed by the control unit 13. Furthermore, the flowchart in Figure 7 starts, for example, when the ignition of vehicle A is turned on, and ends when the ignition of vehicle A is turned off.

[0041] In step S11, the control unit 13 determines whether or not the vehicle A is in reverse mode. As mentioned above, the operation unit 4 of the vehicle A is provided with an operator (e.g., a switch) for switching between a forward mode, which drives the vehicle A forward, and a reverse mode, which drives the vehicle A in reverse. When the driver drives the vehicle A in reverse, the driver operates the operator while the vehicle is stopped so that the reverse mode is set. As a result, the control unit 13 can determine whether or not the vehicle is in reverse mode based on the information received from the operation unit 4. If the vehicle is not in reverse mode, step S11 is repeated, and if it is in reverse mode, the process proceeds to step S12.

[0042] In step S12, the control unit 13 determines whether or not there is an accelerator operation by the driver. As described above, the accelerator operation is performed by rotating the grip of the steering wheel 2. If there is no accelerator operation, the process returns to step S11, and if there is an accelerator operation, the process proceeds to step S13.

[0043] In step S13, the control unit 13 starts controlling the motor 11 so that the input shaft 21 rotates in the reverse direction. The control unit 13 can control the motor 11 so that the rotational speed of the input shaft 21 changes according to the amount of accelerator operation by the driver. Next, in step S14, the control unit 13 determines whether or not the rotational speed of the input shaft 21 has reached a predetermined rotational speed. If the rotational speed of the input shaft 21 has reached the predetermined rotational speed, the process proceeds to step S15, and the control unit 13 controls the motor 11 so that the rotational speed of the input shaft 21 becomes less than the predetermined rotational speed. Here, the control unit 13 can control the motor 11 by, for example, PWM (Pulse Width Modulation) control. Specifically, the control unit 13 can control the rotational speed of the motor 11 by changing the width (pulse width) of the pulse signal supplied to the motor 11.

[0044] As described above, the drive device 10 (power transmission unit 12) of the present embodiment is provided with a first one-way clutch 32, a second one-way clutch 33, and a clutch mechanism 34 in the low-speed gear mechanism 30, and a centrifugal clutch 42 in the high-speed gear mechanism 40. With such a configuration, in the forward running of the vehicle A, power is transmitted from the input shaft 21 rotating in the forward rotation direction to the output shaft 22 with multiple stages (for example, two stages) of speed change, and in the reverse running of the vehicle A, power is transmitted from the input shaft 21 rotating in the reverse rotation direction to the output shaft 22, thereby realizing an automatic transmission.

[0045] <Second Embodiment> A second embodiment of the present invention will now be described. Figure 8 shows the internal structure of the drive unit 10 of this embodiment, and Figure 9 shows a schematic diagram of the drive unit 10 of this embodiment. This embodiment differs from the first embodiment described above in the configuration of the low-speed gear mechanism 30 in the drive unit 10 (power transmission unit 12). Therefore, the configuration of the low-speed gear mechanism 30 in this embodiment will be described below. Note that this embodiment basically follows the first embodiment, and except for the matters mentioned below, it can follow the first embodiment.

[0046] The low-speed gear mechanism 30 of this embodiment may include a first gear train 35 that connects the input shaft 21 to the output shaft 22 via a first one-way clutch 32, and a second gear train 36 that connects the input shaft 21 to the output shaft 22 via a second one-way clutch 33. In the example shown in Figures 8 to 9, the first gear train 35 has a first input gear 35a directly attached to the input shaft 21 and a first output gear 35b that engages with the first input gear 35a. The first output gear 35b is attached to the output shaft 22 via a first one-way clutch 32. The second gear train 36 has a second input gear 36a attached to the input shaft 21 and a second output gear 36b that engages with the second input gear 36a. The second input gear 36a is attached to the input shaft 21 via a second one-way clutch, and the second output gear 36b is attached to the output shaft via a clutch mechanism 34. Here, the first gear train 35 and the second gear train 36 may be configured such that their reduction ratios are equal.

[0047] [Modified Examples] Figures 10A to 10C show modified examples of the drive unit 10 of this embodiment. In Figures 10A to 10C, only a schematic diagram of the low-speed gear mechanism 30 of this embodiment is shown, and other elements of the drive unit 10 (such as the high-speed gear mechanism 40) are not shown.

[0048] In FIG. 10A, in the first gear train 35, the first input gear 35a is directly attached to the input shaft 21, and the first output gear 35b is attached to the output shaft 22 via the first one-way clutch 32. Also, in the second gear train 36, the second input gear 36a is directly attached to the input shaft 21, and the second output gear 36b is attached to the output shaft 22 via the second one-way clutch 33 and the clutch mechanism 34.

[0049] In FIG. 10B, in the first gear train 35, the first input gear 35a is attached to the input shaft 21 via the first one-way clutch 32, and the first output gear 35b is directly attached to the output shaft 22. Also, in the second gear train 36, the second input gear 36a is directly attached to the input shaft 21, and the second output gear 36b is attached to the output shaft 22 via the second one-way clutch 33 and the clutch mechanism 34.

[0050] In FIG. 10C, in the first gear train 35, the first input gear 35a is attached to the input shaft 21 via the first one-way clutch 32, and the first output gear 35b is directly attached to the output shaft 22. Also, in the second gear train 36, the second input gear 36a is attached to the input shaft 21 via the second one-way clutch 33, and the second output gear 36b is attached to the output shaft 22 via the clutch mechanism 34.

[0051] Also, with the configuration of the drive device 10 (power transmission unit 12) of the present embodiment described above, it is possible to realize an automatic transmission that transmits power by shifting in multiple stages from the input shaft 21 rotating in the forward rotation direction to the output shaft 22 during forward travel of the vehicle A, and transmits power from the input shaft 21 rotating in the reverse rotation direction to the output shaft 22 during reverse travel of the vehicle A.

[0052] <Third Embodiment> A third embodiment of the present invention will now be described. Figure 11 shows a schematic diagram of the drive device 10 of this embodiment. This embodiment differs from the first embodiment in the configuration of the low-speed gear mechanism 30 in the drive device 10 (power transmission unit 12). Therefore, the configuration of the low-speed gear mechanism 30 in this embodiment will be described below. Note that this embodiment basically follows the first embodiment, and can be followed except for matters mentioned below.

[0053] The gear train 37 included in the low-speed gear mechanism 30 of this embodiment has an input gear 37a directly attached to the input shaft 21, a first output gear 37b that is coupled to the input gear 37a, and a second output gear 37c that is coupled to the input gear 37a. In other words, in the low-speed gear mechanism 30 of this embodiment, the input gear 37a is used in common with multiple output gears (first output gear 37b, second output gear 37c). The first output gear 37b is attached to the output shaft 22 via a first one-way clutch 32, and the second output gear 37c is attached to the output shaft 22 via a second one-way clutch 33 and a clutch mechanism 34. Here, the gear train consisting of the input gear 37a and the first output gear 37b and the gear train consisting of the input gear 37a and the second output gear 37c may be configured to have equal reduction ratios.

[0054] With the configuration of the drive unit 10 (power transmission unit 12) of this embodiment described above, an automatic transmission can be realized that transmits power from the input shaft 21, which is rotating in the forward direction, to the output shaft 22 in multiple stages when the vehicle A is moving forward, and transmits power from the input shaft 21, which is rotating in the reverse direction, to the output shaft 22 when the vehicle A is moving backward.

[0055] <Summary of Embodiments> (Item 1) A power transmission device (e.g., 12) that transmits power from an input shaft (e.g., 21) to an output shaft (e.g., 22) to which power from a motor (e.g., 11) is input, comprising a low-speed gear mechanism (e.g., 30) and a high-speed gear mechanism (e.g., 40) that form power transmission paths between the input shaft and the output shaft, respectively, wherein the reduction ratio of the low-speed gear mechanism is higher than the reduction ratio of the high-speed gear mechanism, and the high-speed gear mechanism includes a centrifugal clutch (e.g., 42) that connects the input shaft, which is rotating at a predetermined rotational speed or higher in the forward direction, to the output shaft. The low-speed gear mechanism includes a first one-way clutch (e.g., 32) that connects the input shaft, which is rotating in the forward direction at a speed less than a predetermined rotational speed, to the output shaft; a second one-way clutch (e.g., 33) that connects the input shaft, which is rotating in the reverse direction at a speed less than a predetermined rotational speed, to the output shaft; and a clutch mechanism (e.g., 34) that disconnects the second one-way clutch from the output shaft, to which the input shaft is connected via the high-speed gear mechanism. This power transmission device is characterized by the fact that, according to this item, a power transmission device (automatic transmission) can be realized that transmits power from an input shaft rotating in the forward direction to an output shaft by shifting speed in multiple stages, and also transmits power from an input shaft rotating in the reverse direction to an output shaft.

[0056] (Item 2) The power transmission device according to Item 1, characterized in that the first one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the reverse direction, and the second one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the forward direction. According to this item, it is possible to avoid the input shaft being connected to the output shaft via both the first one-way clutch and the second one-way clutch.

[0057] (Item 3) The power transmission device according to Item 1 or 2, characterized in that the first one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the forward direction at a predetermined rotational speed or higher. According to this item, when the input shaft is connected to the output shaft via a high-speed gear mechanism, it is possible to avoid the input shaft being connected to the output shaft via the first one-way clutch.

[0058] (Item 4) The power transmission device according to any one of Items 1 to 3, characterized in that the input shaft, which is rotating in the reverse direction, is connected to the output shaft via the second one-way clutch and the clutch mechanism. According to this item, due to the action of the clutch mechanism, the input shaft is not connected to the output shaft via the second one-way clutch when the input shaft is rotating in the forward direction, while the input shaft can be connected to the output shaft via the second one-way clutch when the input shaft is rotating in the reverse direction.

[0059] (Item 5) The power transmission device according to any one of Items 1 to 4, characterized in that the clutch mechanism is disposed between the second one-way clutch and the output shaft, and is configured to connect the second one-way clutch to the output shaft when the input shaft is rotating in the reverse direction. According to this item, the clutch mechanism prevents the second one-way clutch from being connected to the output shaft when the input shaft is rotating in the forward direction, while it can connect the second one-way clutch to the output shaft when the input shaft is rotating in the reverse direction.

[0060] (Item 6) The power transmission device according to Item 5, characterized in that the clutch mechanism has a gear pair (for example, 34d) configured to engage when connecting the input shaft, which is rotating in the reverse direction, to the output shaft via the second one-way clutch, and to free-rotate when the input shaft, which is rotating in the forward direction, is connected to the output shaft via the first one-way clutch or the high-speed gear mechanism. According to this item, a configuration can be realized in which the second one-way clutch is not connected to the output shaft when the input shaft is rotating in the forward direction, while the second one-way clutch is connected to the output shaft when the input shaft is rotating in the reverse direction.

[0061] (Item 7) The power transmission device according to Item 6, characterized in that the clutch mechanism further comprises a drive mechanism (34e) that drives the gear pair to engage when connecting the input shaft, which is rotating in the reverse direction, to the output shaft via the second one-way clutch. According to this item, the engagement / free rotation of the gear pair can be appropriately operated when the input shaft is rotating in the forward direction and when it is rotating in the reverse direction.

[0062] (Item 8) The power transmission device according to any one of Items 1 to 7, characterized in that the low-speed gear mechanism includes an input gear (e.g., 31a) attached to the input shaft and an output gear (e.g., 31b) coupled to the input gear, the output gear is attached to the output shaft via the first one-way clutch and the second one-way clutch, and the clutch mechanism is arranged between the second one-way clutch and the output shaft. According to this item, a power transmission device that enables reverse drive can be provided without adding a gear train for transmitting power in the reverse direction.

[0063] (Item 9) The power transmission device according to any one of Items 1 to 7, characterized in that the low-speed gear mechanism includes a first gear train (e.g., 35) that connects the input shaft to the output shaft via the first one-way clutch, and a second gear train (e.g., 36) that connects the input shaft to the output shaft via the second one-way clutch and the clutch mechanism. According to this item, an example of a power transmission device can be provided that transmits power from an input shaft rotating in the forward direction to an output shaft by shifting speed in multiple stages, and also transmits power from an input shaft rotating in the reverse direction to an output shaft.

[0064] (Item 10) The power transmission device according to Item 9, characterized in that the first gear train and the second gear train are configured such that their reduction ratios are equal. According to this item, when transmitting power from an input shaft rotating in the reverse direction to an output shaft, it is possible to avoid the formation of two power transmission paths with different reduction ratios between the input shaft and the output shaft, which would restrict the rotation of the power transmission device.

[0065] (Item 11) The power transmission device according to Item 9 or 10, characterized in that the first gear train includes a first input gear (e.g., 35a) and a first output gear (e.g., 35b) that is coupled to the first input gear, the first input gear is mounted on the input shaft via the first one-way clutch and the first output gear is directly mounted on the output shaft, or the first input gear is directly mounted on the input shaft and the first output gear is mounted on the output shaft via the first one-way clutch. According to this item, an example of a configuration in which the input shaft is connected to the output shaft via the first one-way clutch can be provided.

[0066] (Item 12) The power transmission device according to Item 9 or 10, characterized in that the second gear train includes a second input gear (e.g., 36a) and a second output gear (e.g., 36b) coupled to the second input gear, wherein the second input gear is mounted on the input shaft via the second one-way clutch and the second output gear is mounted on the output shaft via the clutch mechanism, or the second input gear is directly mounted on the input shaft and the second output gear is mounted on the output shaft via the second one-way clutch and the clutch mechanism. According to this item, an example of a configuration in which the input shaft is connected to the output shaft via the second one-way clutch and the clutch mechanism can be provided.

[0067] (Item 13) The power transmission device according to any one of Items 1 to 7, characterized in that the low-speed gear mechanism includes an input gear (e.g., 37a) mounted on the input shaft, and a first output gear (e.g., 37b) and a second output gear (e.g., 37c) that are coupled to the input gear, the first output gear is mounted on the output shaft via the first one-way clutch, and the second output gear is mounted on the output shaft via the second one-way clutch and the clutch mechanism. According to this item, the number of input gears mounted on the input shaft can be reduced.

[0068] (Item 14) The power transmission device according to Item 13, characterized in that the gear train consisting of the input gear and the first output gear and the gear train consisting of the input gear and the second output gear are configured such that their reduction ratios are equal. According to this item, when transmitting power from an input shaft rotating in the reverse direction to an output shaft, it is possible to avoid the formation of two power transmission paths with different reduction ratios between the input shaft and the output shaft, which would restrict the rotation of the power transmission device.

[0069] (Item 15) A drive device (e.g., 10) for driving an output shaft (e.g., 22), comprising: a motor (e.g., 11); an input shaft (e.g., 21) to which the power of the motor is input; and a power transmission device (e.g., 12) described in any one of Items 1 to 14 for transmitting power from the input shaft to the output shaft. According to this item, a drive device can be realized that transmits power from an input shaft rotating in the forward direction by a motor to an output shaft with multiple speed changes, and also transmits power from an input shaft rotating in the reverse direction by a motor to an output shaft.

[0070] (Item 16) The drive device according to Item 15, further comprising a control unit (e.g., 13) for controlling the motor, wherein the predetermined rotational speed is the rotational speed of the input shaft when the centrifugal clutch is engaged, and the control unit controls the motor such that the rotational speed of the input shaft is less than the predetermined rotational speed when the input shaft is rotated in the reverse direction. According to this item, the second one-way clutch is engaged when the centrifugal clutch of the high-speed gear mechanism is engaged, and it is possible to avoid the formation of two power transmission paths with different reduction ratios between the input shaft and the output shaft, thereby limiting the rotation of the power transmission device.

[0071] (Item 17) A vehicle equipped with the drive system described in Item 15 or 16. According to this item, it is possible to provide a vehicle that can transmit power from an input shaft rotating in the forward direction to an output shaft in multiple stages by a motor, and also transmit power from an input shaft rotating in the reverse direction to an output shaft by a motor.

[0072] The invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention.

[0073] This application claims priority based on Japanese Patent Application No. 2024-159389, filed on September 13, 2024, and all of its contents are incorporated herein by reference.

[0074] 10: Drive unit, 11: Motor, 12: Power transmission unit, 13: Control unit, 21: Input shaft, 22: Output shaft, 30: Low-speed gear mechanism, 32: First one-way clutch, 33: Second one-way clutch, 34: Clutch mechanism, 40: High-speed gear mechanism, 42: Centrifugal clutch

Claims

1. A power transmission device for transmitting power from an input shaft to an output shaft, the power of a motor being input to the input shaft, comprising a low-speed gear mechanism and a high-speed gear mechanism that each form a power transmission path between the input shaft and the output shaft, wherein the reduction ratio of the low-speed gear mechanism is higher than the reduction ratio of the high-speed gear mechanism, the high-speed gear mechanism includes a centrifugal clutch that connects the input shaft, which is rotating at a predetermined rotational speed or higher in the forward direction, to the output shaft, and the low-speed gear mechanism includes a first one-way clutch that connects the input shaft, which is rotating at less than the predetermined rotational speed in the forward direction, to the output shaft, a second one-way clutch that connects the input shaft, which is rotating at less than the predetermined rotational speed in the reverse direction, to the output shaft, and a clutch mechanism that disconnects the second one-way clutch from the output shaft to which the input shaft is connected via the high-speed gear mechanism.

2. The power transmission device according to claim 1, characterized in that the first one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the reverse direction, and the second one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the forward direction.

3. The power transmission device according to claim 1 or 2, characterized in that the first one-way clutch is configured not to connect the input shaft to the output shaft when the input shaft is rotating in the forward direction at a predetermined rotational speed or higher.

4. The power transmission device according to any one of claims 1 to 3, characterized in that the input shaft, which is rotating in the reverse direction, is connected to the output shaft via the second one-way clutch and the clutch mechanism.

5. The power transmission device according to any one of claims 1 to 4, characterized in that the clutch mechanism is disposed between the second one-way clutch and the output shaft, and is configured to connect the second one-way clutch to the output shaft when the input shaft is rotating in the reverse direction.

6. The power transmission device according to claim 5, characterized in that the clutch mechanism has a pair of gears configured to engage when connecting the input shaft, which is rotating in the reverse direction, to the output shaft via the second one-way clutch, and to free-rotate when the input shaft, which is rotating in the forward direction, is connected to the output shaft via the first one-way clutch or the high-speed gear mechanism.

7. The power transmission device according to claim 6, further comprising a drive mechanism for driving the gear pair to engage the gear pair when connecting the input shaft, which is rotating in the reverse direction, to the output shaft via the second one-way clutch.

8. The power transmission device according to any one of claims 1 to 7, wherein the low-speed gear mechanism includes an input gear mounted on the input shaft and an output gear coupled to the input gear, the output gear is mounted on the output shaft via a first one-way clutch and a second one-way clutch, and the clutch mechanism is arranged between the second one-way clutch and the output shaft.

9. The power transmission device according to any one of claims 1 to 7, characterized in that the low-speed gear mechanism includes a first gear train that connects the input shaft to the output shaft via the first one-way clutch, and a second gear train that connects the input shaft to the output shaft via the second one-way clutch and the clutch mechanism.

10. The power transmission device according to claim 9, characterized in that the first gear train and the second gear train are configured such that their reduction ratios are equal to each other.

11. The power transmission device according to claim 9 or 10, wherein the first gear train includes a first input gear and a first output gear coupled to the first input gear, the first input gear being mounted on the input shaft via a first one-way clutch and the first output gear being directly mounted on the output shaft, or the first input gear being directly mounted on the input shaft and the first output gear being mounted on the output shaft via a first one-way clutch.

12. The power transmission device according to claim 9 or 10, wherein the second gear train includes a second input gear and a second output gear coupled to the second input gear, the second input gear being mounted on the input shaft via the second one-way clutch and the second output gear being mounted on the output shaft via the clutch mechanism, or the second input gear being directly mounted on the input shaft and the second output gear being mounted on the output shaft via the second one-way clutch and the clutch mechanism.

13. The power transmission device according to any one of claims 1 to 7, wherein the low-speed gear mechanism includes an input gear mounted on the input shaft, and a first output gear and a second output gear coupled to the input gear, the first output gear being mounted on the output shaft via the first one-way clutch, and the second output gear being mounted on the output shaft via the second one-way clutch and the clutch mechanism.

14. The power transmission device according to claim 13, characterized in that the gear train consisting of the input gear and the first output gear and the gear train consisting of the input gear and the second output gear are configured such that their reduction ratios are equal.

15. A drive device for driving an output shaft, comprising: a motor; an input shaft to which the power of the motor is input; and a power transmission device according to any one of claims 1 to 14 for transmitting power from the input shaft to the output shaft.

16. The drive device according to claim 15, further comprising a control unit for controlling the motor, wherein the predetermined rotational speed is the rotational speed of the input shaft when the centrifugal clutch is engaged, and the control unit controls the motor so that the rotational speed of the input shaft is less than the predetermined rotational speed when the input shaft is rotated in the reverse direction.

17. A vehicle equipped with the drive system according to claim 15 or 16.

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