Work vehicle

Abstract

To provide a work vehicle designed to operate a hydraulic pump using the combined force of an engine and an electric motor, prioritizing the use of one with the higher rotational speed while deactivating the other.SOLUTION: A work vehicle comprises a planetary gear mechanism surrounding a sun gear, which is connected to an engine output shaft housed in an engine carrier. The planetary gear mechanism includes a pinion gear with a one-way clutch and a ring gear section that combines driving force of the engine with that of an electric motor. This configuration allows the work vehicle to utilize the driving force of either the engine or the electric motor, depending on which has the higher rotational speed, as output.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a work vehicle that uses an engine and an electric motor to output power to a hydraulic pump to drive the vehicle and operate a work implement. [Background technology]

[0002] The hydraulic pump is driven by an engine or electric motor, and the transmission source is switched by the meshing of each gear.A one-way clutch is installed on the drive shaft, and a high-speed power source is used. (Patent Document 1) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-315059 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, one-way clutches are provided on the main shafts of both the engine and electric motor. When there is frequent switching between the engine and electric motor power, providing a one-way clutch on the main shaft is a highly efficient configuration, but in agricultural machinery and the like, the rotation speed is fixed at low and high speeds for a certain period of time, and operation continues at high loads at high speeds, so it is thought that this may affect durability under high loads.

[0005] In the present invention, durability under high load is further improved. [Means for solving the problem]

[0006] The first aspect of the present invention is achieved by the following technical means.

[0007] An engine (101) and an electric motor (120) as driving power sources Equipped with , A sun gear (131) connected to the engine output shaft (104) is disposed in the engine carrier. Equipped with , and a planetary gear mechanism (130) is provided on its outer periphery, The ring gear (136) on the outer periphery of the planetary gear mechanism (130) Electric motor(120) This is a mechanism to transmit power from the input gear (121) Planetary gear mechanism The pinion gear (132) of (130) is equipped with a one-way clutch (133). Preparation, engine (101) , and an electric motor (120) The power of the one with the faster rotation speed is output to the hydraulic pump (150).

[0008] The second invention is solved by the following technical means.

[0009] Engine (101) In the power output to the engine carrier output shaft (135), the operation of the engine (101) or the electric motor (120) whose input power has been cut off is stopped after a predetermined time, and when a change in the rotation speed of the engine carrier output shaft (135) requires switching of the power of the engine (101) or the electric motor (120), the engine (101) or the electric motor (120) on the moving side is operated a predetermined time before the change.

[0010] The third aspect of the invention is solved by the following technical means.

[0011] An engine (101A) and an electric motor (120A) as driving power sources Equipped with A sun gear (131A) connected to the engine output shaft (104A) in the engine carrier. Equipped with A planetary gear mechanism (130A) is provided on the outer periphery of the The ring gear (136A) on the outer periphery of the planetary gear mechanism (130A) Electric motor (120A) This is a mechanism that transmits power from the input gear (121A), A clutch (137) is provided on the engine output shaft (104A), which allows power transmission to the sun gear (131A) to be switched on and off. The pinion gear (132A) of the planetary gear mechanism does not have a one-way clutch. When the clutch (137) is engaged, the power is the combined power of the engine (101A) and the electric motor (120A), and when the clutch (137) is disengaged, the power is the power of the electric motor (120A) alone. [Effects of the Invention]

[0012] In the first aspect of the present invention, a one-way clutch is provided on the pinion gear, which distributes the power applied to the one-way clutch during high rotation and high load conditions. As this is a work vehicle, sudden high loads can occur, but even in such cases, the repulsive force is distributed and absorbed, ensuring sufficient durability.

[0013] The second invention allows smooth switching with less shock even when power is received from the higher rotation side. In addition, the power on the stop side can be automatically stopped, which also saves power.

[0014] According to the third invention, by providing a clutch on the input shaft of the larger engine as the power source, power can be turned on and off manually, improving the durability of the work vehicle and enabling safe work by maintaining a minimum level of power. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing the overall state of a power transmission mechanism of a work vehicle according to the present invention; [Figure 2] 1 is a diagram showing the layout of an engine, an electric motor, and a planetary gear mechanism of a work vehicle according to the present invention. [Figure 3] FIG. 2 is a layout diagram of a transmission mechanism to a hydraulic pump of the work vehicle of the present invention. [Figure 4] 1 is a diagram illustrating the layout of an engine, an electric motor, and a planetary gear mechanism according to the present invention. [Figure 5]FIG. 10 is a diagram showing the layout of a clutch provided on the engine output shaft of the present invention. [Figure 6] FIG. 10 is a diagram showing the overall state of a power transmission mechanism in a work vehicle according to another embodiment of the present invention. [Figure 7] FIG. 10 is a partially enlarged view of a power transmission mechanism in a work vehicle according to another embodiment of the present invention. [Figure 8] 4 is a flowchart showing the process of switching power from the engine to the electric motor according to the present invention. [Figure 9] 4 is a flowchart showing a process for switching power from the electric motor to the engine according to the present invention. [Figure 10] 1 is a cross-sectional view of an electric motor of the present invention equipped with a planetary gear mechanism and a starter motor provided as a mechanism for taking in engine power as a resultant force. [Figure 11] 1 is a schematic diagram showing an electric motor of the present invention equipped with a planetary gear mechanism and a starter motor provided as a mechanism for taking in engine power as a resultant force. [Figure 12] 1 is a cross-sectional view of an engine of the present invention equipped with a planetary gear mechanism and a starter motor provided as a mechanism for taking in the power of an electric motor as a resultant force. [Figure 13] 1 is a schematic diagram showing an engine of the present invention equipped with a planetary gear mechanism and a starter motor provided as a mechanism that takes in the power of an electric motor as a resultant force. [Figure 14] 1 is a cross-sectional view of a mechanism that includes a planetary gear mechanism in an engine of the present invention and receives the power of an electric motor as a resultant force. [Figure 15] 1 is a schematic diagram of a mechanism in which the engine of the present invention is provided with a planetary gear mechanism and receives the power of an electric motor as a resultant force. [Figure 16] 1 is a cross-sectional view of an engine of the present invention equipped with a planetary gear mechanism and a clutch on the engine output shaft as a mechanism for taking in the power of an electric motor as a resultant force. [Figure 17] 1 is a schematic diagram showing an engine of the present invention equipped with a planetary gear mechanism and a clutch on the engine output shaft as a mechanism for taking in the power of an electric motor as a resultant force. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described below with reference to the embodiments shown in the drawings.

[0017] The work vehicle shown in FIGS. 1 to 17 shows an example of this embodiment.

[0018] The background of the present invention will be explained.

[0019] Unlike automobiles, work vehicles that use hydraulic pumps to travel and operate work equipment are sometimes operated continuously at high speeds and high loads, and the work equipment is controlled by keeping the hydraulic pump on standby with pilot pressure using minimal power.

[0020] This type of usage requires various switching functions, such as smoothly changing power to the high rotation side and charging control using an electric motor, and a mechanism that satisfies these specifications by providing a one-way clutch in the appropriate location is required.

[0021] The present invention provides control that is required in agricultural work and construction work, and examples of work vehicles include tractors, rice transplanters, combine harvesters, and riding cultivators, but in the examples, we will explain using riding cultivators and combine harvesters as representative examples.

[0022] An embodiment of the present invention will be explained based on a ride-on cultivation machine with reference to Figure 1. Figure 1 shows the work vehicle with its exterior parts removed, and Figures 2 and 3 are enlarged views of parts, but to make the explanation easier, the interior is shown with parts cut out or omitted, and some parts are shown as being attached to a work vehicle in the completed stage.

[0023] The power generating devices are grouped together in an area that fits under the hood at the front of the work vehicle 100. The battery 110 provides power for the electric motor 120 and is also used as a power source for operating the operation device 180 of the work vehicle. When the electric motor 120 is used as a charger, electricity is stored in the battery 110.

[0024] An engine 101 is disposed next to the electric motor 120. The output shafts of the electric motor 120 and engine 101 are parallel and in the same direction. The engine's intake section 103 and exhaust section 102 are compactly arranged on the engine side, and the exhaust muffler passes through the exterior hood (not shown) and exits to the outside.

[0025] The power transmission mechanism 130 that combines the power of the engine and the electric motor will now be described.

[0026] As shown in Figures 3 and 4, a sun gear 131 is located at the tip of the output shaft of the engine 101. A planetary gear mechanism surrounds this sun gear 131. In the planetary gear mechanism, a pinion gear 132, which corresponds to a planetary gear, is disposed between the sun gear 131 and an outer ring gear 136. For example, if the outer ring gear 136 is fixed, the pinion gear 132 will increase its rotation speed due to the diameter of the sun gear 131 and the diameter of the pinion gear 132. However, when a difference in rotation occurs due to the load of this increase, the planet carrier 134 will begin to rotate. The planet carrier 134 is connected to an engine carrier output shaft 135.

[0027] Furthermore, although the outer circumferential ring gear 136 has been described above as being fixed, in the embodiment it is configured to rotate, and the rotation of the electric motor 120 is transmitted to the ring gear 136 as the electric motor gear 121. The outer periphery of the ring gear 136 has teeth that mesh with the teeth of the electric motor gear 121, so that the rotation of the electric motor gear 121 can be combined with the outer circumferential ring gear 136.

[0028] For example, if the electric motor 120 is rotated so that the outer ring gear 136 rotates in the opposite direction to the sun gear 131, the driving force of the electric motor 120 becomes a resultant force, which increases the rotational speed of the planetary carrier 134 and the rotational torque.

[0029] In this diagram, a simple spur gear shape is used, but in cases where power is large, a helical gear (including a double helical gear) is better. Also, in Figure 4, the electric motor gear 121 to the outer ring gear 136 are shown exposed, but these parts are housed inside the engine carrier and protected by lubricating oil, with only the engine carrier output shaft 135 protruding from the engine carrier.

[0030] Regarding lubrication inside the engine carrier, the electric motor gear 121 to the outer ring gear 136 are protected in separate cases with individual lubricating oil, but it is also possible to combine the lubricating oil for the engine 101 and manage the inside of the engine carrier all at once.

[0031] To combat heat buildup in the engine periphery, a water-cooled radiator 140 is provided to cool the engine. The engine 101 and radiator 140 are connected by a radiator hose 141, and heat is dissipated by the radiator as coolant circulates through them. The radiator 140 has a built-in radiator fan that draws in air from the front of the vehicle, cooling the battery 110, electric motor 120, and power transmission mechanism 130 while also cooling the radiator 140 itself. The air that absorbs heat is discharged from underneath the work vehicle, so the operator's seat is not directly exposed to the exhaust air. The power transmission mechanism 130 can be configured to be discharged to the outside from the engine carrier, but it can also be configured to be housed within the engine case, which allows for the engine carrier to be managed together with the lubricating oil for the engine 101 as described above, making it possible to reduce the size and still achieve cooling.

[0032] Power is input from the engine carrier output shaft 135 of the engine 101 to a hydraulic pump 150 provided at the rear. The hydraulic pump 150 is connected to an HST mechanism, and the output rotation speed is variable, changing the traveling speed, the rotation speed of the work equipment, and the operating speed of small hydraulic pumps provided at each position.

[0033] 3, the engine carrier output shaft 135 of the engine 101 is misaligned with the input shaft of the hydraulic pump 150. In this case, a method of transmitting power using a V-belt or the like is available.

[0034] The use of the engine 101 and the electric motor 120 for power will now be described.

[0035] When an engine is operated at low speeds, variations in rotation can occur, resulting in unstable torque. It can also knock or stop rotating when a load is applied, so at low speeds, an electric motor provides more stable power. Especially from the perspective of fuel economy, engines are inefficient at low speeds, and low-speed operation using an inverter-controlled electric motor is more efficient.

[0036] When using a low-speed electric motor, by maintaining the hydraulic pump at the pilot pressure, which is the base pressure, the hydraulic pump can start operating instantly and can also handle slow, minute movements.If the pilot pressure is not maintained, the hydraulic pump cannot operate instantly, and if high pressure is applied all at once, the hydraulic pump may move significantly, making it highly likely that the pump will not be able to move slowly when it first starts operating.

[0037] It is also possible to activate the parking brake. When the engine idling stop function is activated, or when it becomes necessary to operate the hydraulic actuator to store the work equipment, the electric motor will start rotating and continue to operate until the storage of the work equipment is complete. Once the storage of the work equipment is complete, the electric motor will stop. When such a small amount of power is required, energy-saving operation is also possible by switching from the engine to the electric motor.

[0038] A characteristic of work vehicles is that they are required to maintain high revolutions and high loads for long periods of time. At these high revolutions, the engine's rotation is easier to utilize, and even under load, there is little fluctuation in the rotation speed, making it stable. Therefore, at high output and high revolutions, only the engine is running, and the motor is controlled to stop.

[0039] There is also a means called motor assist, which responds when the engine speed drops due to the load on the work equipment. The engine carrier output shaft 135 is equipped with a torque sensor and a rotation speed sensor, which activates the electric motor 120 when it detects a drop in torque or rotation speed per unit time of more than a predetermined value.

[0040] As described above, when the electric motor 120 is rotated so that the outer ring gear 136 rotates in the opposite direction to the sun gear 131, the driving force of the electric motor 120 becomes a resultant force, which increases the rotational speed of the planetary carrier 134 and the rotational torque. With this configuration, when the engine rotation speed drops, the assist function of the electric motor 120 is activated, thereby stabilizing the output.

[0041] The power switching between the engine 101 and the electric motor 120 can be set in advance to be performed based on the engine output rotation speed or the engine output torque.

[0042] The structure of the one-way clutch according to the present invention will be described below in order to improve durability.

[0043] One-way clutches can be used in places where reverse rotation is prohibited, as they only accept rotation in one direction and spin freely in the reverse direction. They can also be used to utilize the faster rotation speed. When the rotation speed increases, the slower rotation speed side inevitably becomes the same as if it were rotating in the reverse direction, making it possible to prevent power from being transmitted to the slower rotation speed side.

[0044] This mechanism allows for the adoption of power from the higher rotational speed. One way to achieve this is by providing one-way clutches on each power transmission shaft. This mechanism is efficient because, in applications where vehicle speed changes frequently, such as in automobiles, the engine and electric motor are frequently switched between, preventing biased power distribution. However, agricultural and construction machinery require additional power for the work equipment in addition to the traction system. Compared to automobiles, load fluctuations are significantly greater. Even when a work vehicle is in standby mode, pilot pressure must be maintained to maintain the working equipment's state, requiring effective rotation at low rotational speeds. Therefore, electric motor rotation is more energy-efficient than engine rotation. Furthermore, when operating solely for driving, the overall power required is intermediate, and an electric motor can be used. However, when driving with the work equipment operating, the load is high, and high-speed operation by the engine may be preferable due to the power distribution of the HST. The decision to switch between the two must be made after considering when the output power is stable.

[0045] In this way, the rotational speed is fixed at different values ​​depending on the operating mode and maintained in that state for a long time. This biased power distribution can lead to durability issues if a one-way clutch is installed on the main shaft. Furthermore, for efficiency reasons, a one-way clutch of a suitable size for the power is required for a large main shaft, which is not effective in terms of efficiency. To address these issues, a one-way clutch is installed on each of the multiple pinion gears of the planetary gear mechanism. This not only distributes the load but also reduces the load on the bearing balls that fall into the drop grooves in the direction of freewheeling within the one-way clutch. This allows the bearing balls in the one-way clutch to sequentially select the required rotational side, even if there is a short time lag. This prevents a sudden change in the power selection destination, and allows for a smooth response by slightly adjusting the distribution of power from both sides. This is achieved by installing a one-way clutch 133 on the pinion gear 132 of the planetary gear mechanism 130.

[0046] The one-way clutch is used to select and take in the power of the engine 101 or the electric motor 120 with the higher rotation speed, but the side with the power cut off must be stopped to prevent unnecessary rotation. In this case, if the power cut off side is immediately stopped before and after switching, there is a problem that it cannot be used again when the stopped side is used.

[0047] To deal with this, the side that has received the power transfer is stopped only after it is determined that the power transfer is stable and there is no problem with the power transfer. The criterion for this determination is that when changing power sources, there is a predetermined time during the switching period during which both the engine and the electric motor are operating.

[0048] 8 shows a flowchart of the flow of switching from the engine 101 to the electric motor 120. Control S8-1 is performed to reduce the rotation speed of the output shaft 130 of the engine carrier. The engine rotation speed at which switching is made to the electric motor 130 is registered in advance, and when S8-2 is performed to detect that the engine rotation speed has fallen below a predetermined rotation speed, S8-4 is performed to start operation of the electric motor 120. Then, S8-5 is performed to determine whether a predetermined time has elapsed since the electric motor started operation.

[0049] However, if the engine has completely stopped when it is necessary to return the power source to the original power source, it may not be possible to switch immediately if only a predetermined time has elapsed. To prevent this, it is necessary to confirm that the rotation speed is stable and within a safe range after the power source is switched. As shown in S8-7, if it is confirmed that the electric motor rotation speed exceeds the reference value β1 and the engine rotation speed falls below the reference value α1, and both states are stable, then S8-11, which stops the engine rotation, can be performed. This series of steps completes the power switch to the electric motor.

[0050] 9 is a flowchart showing the flow of switching from the electric motor 120 to the engine 101. Control S9-1 is performed to increase the rotation speed of the output shaft 130 of the engine carrier. The rotation speed of the electric motor when switching to engine rotation is registered in advance, and when S9-2 is performed to detect that the rotation speed has exceeded a predetermined speed, S9-4 is performed to start operation of the engine 101. Then, S9-5 is performed to determine whether a predetermined time has elapsed since the engine started.

[0051] However, if the electric motor has completely stopped when it is necessary to return the power to the source of the power switch, it may not be possible to switch immediately if only the predetermined time has elapsed. To prevent this, it is necessary to confirm that the rotation speed is stable and above a safe range after the power switch. As in S9-7, if it is confirmed that the electric motor rotation speed is below the reference value β2 and the engine rotation speed is above the reference value α2, and that both states are stable, then S9-11 can be performed to stop the rotation of the electric motor. This series of steps completes the power switch to the engine.

[0052] A configuration will be described in which the one-way clutch is not located on the pinion gear of the planetary gear mechanism, but is provided on the engine output shaft, making it possible to switch power transmission to the sun gear on and off.

[0053] 5, the driving power sources are an engine 101A and an electric motor 120A, and the power output directions of both are the same.

[0054] Inside the engine carrier, there is a sun gear 131A connected to the engine output shaft 104A, and on the outer periphery thereof there is provided a planetary gear mechanism 130A.

[0055] This is a mechanism in which power is transmitted from the input gear 121A of the electric motor to a ring gear 136A that corresponds to the outer periphery of the planetary gear mechanism 130A.

[0056] A clutch 137 is provided on the engine output shaft 104A, and is capable of turning on and off power transmission to the sun gear 131A.

[0057] The clutch 137 is connected to a clutch pedal and is a mechanism that is turned on and off by human action, or is an electric clutch mechanism that can be turned on and off by electronic control.

[0058] The electronic clutch mechanism performs control so that the electronic clutch is automatically disengaged when the engine speed falls below a predetermined speed or the motor speed falls below a predetermined speed, thereby preventing the electric motor 120A from rotating the engine 101A in the reverse direction.

[0059] This configuration is suitable for models that frequently use both rotational speeds, namely, the low rotational speed of the motor 120A and the high rotational speed resulting from the combined power of the electric motor 120A and the engine 101A. For example, this applies to a case where a tractor pulls a large pesticide sprayer with a large working power to perform work, but when the vehicle is stopped, only the pilot pressure of the pesticide sprayer pump is secured.

[0060] Another embodiment of the present invention will be described with reference to FIG.

[0061] Although not shown in the figure, transmitting the power input from the pulley of engine carrier output shaft 135B to the pulley of hydraulic pump 150B using a V-belt connecting them is not only easier to control by dealing with positional deviations and changing the rotation speed, but is also effective in terms of layout.

[0062] 6 shows an example of installation on a combine harvester. In this configuration, the engine carrier output shaft 135B and the hydraulic pump 150B are arranged parallel to each other, rather than facing each other.

[0063] The power of the engine carrier output shaft 135B is distributed by a multi-stage pulley 180 attached to the tip, and is transmitted by a transmission mechanism to a hydraulic case 190 of the traveling system, a hydraulic pump 150B, and a work machine (not shown in the figure).

[0064] 7 is an enlarged view showing the internal arrangement of the planetary gear mechanism without the protective case. In this configuration, one-way clutch 133B is provided on pinion gear 132B of the planetary gear mechanism, and a method is used to take in the rotational speed of either engine 101B or electric motor 120B, whichever is faster.

[0065] Different embodiments of the combined configuration of the engine, electric motor, and planetary gear mechanism will be described below with reference to the drawings.

[0066] Figures 10 and 11 show a mechanism in which an electric motor 120C is equipped with a planetary gear mechanism and receives the power of the engine 101C as a resultant force. The engine's starter motor 122C is connected to the engine's flywheel shaft for starting. The mechanism is linked to the engine's output shaft 104C. This configuration mainly relies on the output of the electric motor 120C to obtain power from the engine 101C when the load is heavy. The mechanism is easy to adapt to the environment, and is suitable for environments where work is primarily done indoors, but outdoor work may also be used.

[0067] 12 and 13 show a mechanism in which an engine 101D is provided with a planetary gear mechanism, and the power of an electric motor 120D is taken in as a resultant force. The engine's starter motor 122D is connected to the engine's flywheel shaft for starting. The mechanism is linked to the engine's output shaft 104D. This configuration mainly uses the output of the engine 101D to obtain power from the electric motor 120D when the load is light. While it is primarily used for outdoor work requiring high power output, it can also be used for a wide range of indoor work.

[0068] 14 and 15 are diagrams illustrating the first aspect of the invention shown in FIGS. 3 and 4. The engine 101E is equipped with a planetary gear mechanism, and this mechanism takes in the power of the electric motor 120E as a resultant force. This mechanism utilizes the rotation of the electric motor 120E to function as a starter motor for the engine 101E.

[0069] Figures 16 and 17 are diagrams of Figure 5, which shows the third invention. The engine 101F is equipped with a planetary gear mechanism, and this mechanism takes in the power of the electric motor 120F as a resultant force. This mechanism uses the rotation of the electric motor 120F to function as a starter motor for the engine 101E. Another feature is that it is equipped with a clutch 137F, which switches the power on and off.

[0070] The schematic contents of Figures 14 to 17 are within the scope of the invention, and variations in the external form and specifications are within the scope of the invention, as are the external forms of Figures 1 to 4 and the forms of Figures 6 to 7. Similarly, the actual layout and shape of the schematic configuration diagrams of Figures 10 to 14 are within the scope of the invention. [Explanation of symbols]

[0071] 100 Work Vehicles 101 Engine 110 Battery 120 electric motor 130 Planetary gear mechanism 131 Sun Gear 132 Pinion gear 133 One-way clutch 134 Planetary Carrier 135 Engine carrier output shaft 136 Ring gear 140 Radiator 150 Hydraulic Pump

Claims

1. The vehicle is provided with an engine (101) and an electric motor (120) as a driving force source, A sun gear (131) connected to an engine output shaft (104) is provided in the engine carrier, and a planetary gear mechanism (130) is provided on the outer periphery of the sun gear (131). This is a mechanism in which power is transmitted from the input gear (121) of the electric motor (120) to the ring gear (136) which is the outer periphery of the planetary gear mechanism (130), The pinion gear (132) of the planetary gear mechanism (130) is provided with a one-way clutch (133), A work vehicle in which the power of either an engine (101) or an electric motor (120), whichever has a higher rotation speed, is output to a hydraulic pump (150).

2. A work vehicle as claimed in claim 1, which performs control to stop the operation of the engine (101) or electric motor (120) whose input power has been cut off after a predetermined time when the power output of the engine (101) to the engine carrier output shaft (135) of the engine (101) is performed, and when a change in the rotation speed of the engine carrier output shaft (135) requires a switch in the power of the engine (101) or electric motor (120), controls to operate the engine (101) or electric motor (120) on the movable side before a predetermined time.

3. The vehicle is provided with an engine (101A) and an electric motor (120A) as driving power sources, A sun gear (131A) connected to an engine output shaft (104A) is provided in the engine carrier, and a planetary gear mechanism (130A) is provided on the outer periphery of the sun gear (131A). A mechanism in which power is transmitted from an input gear (121A) of an electric motor (120A) to a ring gear (136A) that corresponds to the outer periphery of the planetary gear mechanism (130A), A clutch (137) is provided on the engine output shaft (104A), which can switch power transmission to the sun gear (131A) on and off. The pinion gear (132A) of the planetary gear mechanism does not have a one-way clutch, When the clutch (137) is engaged, the power is the combined power of the engine (101A) and the electric motor (120A), and when the clutch (137) is disengaged, the power is the power of the electric motor (120A) alone.

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