JP7794067B2 - Vehicle drive system - Google Patents

Description

The present invention relates to a vehicle drive system.

Patent Document 1 discloses an electric vehicle equipped with an engine, a generator motor that generates electricity using the driving force of the engine, and a traction motor that is driven by the electricity generated by the generator motor. This electric vehicle is configured with a clutch and gear train that can switch between a series hybrid mode, in which the traction motor is driven using electricity generated by the driving force of the engine, and a direct engine mode, in which the vehicle travels by transmitting the driving force of the engine to the drive wheels.

Japanese Patent Application Laid-Open No. 2021-20599

The electric vehicle described in Patent Document 1 is equipped with a two-shaft transmission mechanism that transmits the rotation of the traction motor to the drive wheels, as well as a three-shaft transmission mechanism that transmits the rotation of the engine to the generator motor and a two-shaft transmission mechanism that transmits the rotation of the engine to the drive wheels. Therefore, the inclusion of these multiple transmission mechanisms not only increases the weight, but also increases the number of parts, resulting in an increase in the size of the drive system.

The present invention aims to provide a vehicle drive system that can reduce weight and the number of parts.

According to one aspect of the present invention, the present invention is applied to a drive system for a vehicle equipped with a motor and an engine and running on the driving force of at least one of the motor and the engine. The drive system includes a first rotating shaft connected at one end to the motor, a first transmission mechanism that reduces the rotation of the first rotating shaft and transmits it to a second rotating shaft, and a second transmission mechanism that reduces the rotation of the second rotating shaft and transmits it to an axle. The other end of the first rotating shaft is connected to an engine via a second clutch that interrupts the transmission of rotation, and the first transmission mechanism includes: a first gear train consisting of a first gear supported rotatably relative to the first rotating shaft and a second gear fixed to the second rotating shaft, and transmitting the rotation of the first rotating shaft to the second rotating shaft at a first reduction ratio , a second gear train consisting of a third gear supported rotatably relative to the first rotating shaft and a fourth gear fixed to the second rotating shaft, and transmitting the rotation of the first rotating shaft to the second rotating shaft at a second reduction ratio smaller than the first reduction ratio , and a first clutch that switches between the first gear train and the second gear train. The second transmission mechanism includes a third gear train consisting of a fifth gear fixed to the second rotating shaft and a sixth gear fixed to a differential device of an axle.

According to the present invention, a vehicle includes a first rotating shaft, a second rotating shaft, and an axle. Between the first and second rotating shafts, a first gear train transmits the rotation of the motor to the second rotating shaft, and a second gear train transmits the rotation of the engine to the second rotating shaft. As a result, the vehicle is composed of three rotating shafts and two gear trains, and can transmit the rotation of the motor and engine to the drive wheels to travel without increasing the number of parts or weight.

FIG. 1 is a configuration diagram of a vehicle drive system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a running state of the drive system.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figure 1 is a configuration diagram of a vehicle drive system 1 according to an embodiment of the present invention.

The drive system 1 of this embodiment is mounted on a vehicle to drive the vehicle. The drive system 1 includes a motor 10, an engine 20, a first transmission mechanism 11, a second transmission mechanism 12, and a control device 80.

The motor 10 is driven by power supplied from a battery and inverter device (not shown), and transmits its rotation to the first rotating shaft 31. The motor 10 also functions as a generator that regenerates (generates electricity) when driven by the rotation of the first rotating shaft 31. The rotor shaft (rotating shaft) of the motor 10 is coaxially connected to the first rotating shaft 31 and rotates together with the first rotating shaft 31.

Engine 20 is an internal combustion engine such as a gasoline engine. The crankshaft of engine 20 is coaxially connected to engine-side rotating shaft 311, which is provided coaxially with first rotating shaft 31. Engine-side rotating shaft 311 and first rotating shaft 31 are connected via a one-way clutch (second clutch) 52, which will be described in detail later, so that the transmission of rotation can be interrupted.

The first rotating shaft 31 has the motor 10 and engine 20 arranged at opposite ends. The first rotating shaft 31 transmits rotation to the second rotating shaft 32 via the first transmission mechanism 11. The first transmission mechanism 11 reduces the rotation of the first rotating shaft 31 and transmits it to the second rotating shaft 32.

The second rotating shaft 32 transmits the rotation transmitted from the first rotating shaft 31 via the first transmission mechanism 11 to the axle 33 via the second transmission mechanism 12. The second transmission mechanism 12 reduces the rotation of the second rotating shaft 32 and transmits it to the axle 33.

Drive wheels 70 are connected to the axle 33, and the rotation transmitted from the second rotating shaft 32 via the second transmission mechanism 12 is transmitted to the drive wheels 70, causing the vehicle to move.

The first rotating shaft 31, second rotating shaft 32, and axle 33 are arranged in parallel with each other.

The first transmission mechanism 11 includes a first gear train 41 and a second gear train 42 that reduce rotation between the first rotating shaft 31 and the second rotating shaft 32. The first gear train 41 transmits the rotation of the first rotating shaft 31 to the second rotating shaft 32 at a predetermined first reduction ratio. The second gear train 42 transmits the rotation of the first rotating shaft 31 to the second rotating shaft 32 at a second reduction ratio that is smaller than that of the first gear train 41.

The first gear train 41 and the second gear train 42 are configured to be selectively switchable by a first clutch 51. The first clutch 51 switches between a first state in which the first gear train 41 is selected and the rotation of the first rotating shaft 31 is transmitted to the second rotating shaft 32; a second state in which the second gear train 42 is selected and the rotation of the first rotating shaft 31 is transmitted to the second rotating shaft 32; and a third state in which neither the first gear train 41 nor the second gear train 42 is selected and the rotation of the first rotating shaft 31 is not transmitted to the second rotating shaft 32. As described below, when the vehicle speed is less than a predetermined vehicle speed (e.g., 40 km/h), the first state using the first gear train 41 is selected, and when the vehicle speed is equal to or greater than the predetermined vehicle speed, the second state using the second gear train 42 is selected.

The second transmission mechanism 12 includes a third gear train 43 and a differential gear 35 between the second rotating shaft 32 and the axle 33. The third gear train 43 reduces the rotation of the second rotating shaft 32 at a third reduction ratio and transmits it to the differential gear 35. The differential gear 35 transmits the rotation to the drive wheels 70 while allowing for a difference in rotation between the left and right axles 33.

The control device 80 controls the operation of the motor 10, engine 20, and first clutch 51. The control device 80 switches the second clutch 52 of the first transmission mechanism 11 between a first state, a second state, or a third state depending on the vehicle state (vehicle speed, torque of the motor 10, torque of the engine 20, etc.).

Next, the structure of the first transmission mechanism 11 and the second transmission mechanism 12 will be described.

The first transmission mechanism 11 switches between the first gear train 41 and the second gear train 42 using the first clutch 51, thereby switching between transmitting the rotation of the first rotating shaft 31 to the second rotating shaft 32 after reducing the speed at a first reduction ratio, and transmitting the rotation of the first rotating shaft 31 to the second rotating shaft 32 after reducing the speed at a second reduction ratio.

In the first transmission mechanism 11, the first gear train 41 is composed of a first gear 41a supported on the first rotating shaft 31 via a bearing member B1 so as to be rotatable relative to the first rotating shaft 31, and a second gear 41c fixed to the second rotating shaft 32 and meshing with the first gear 41a. A first clutch gear 41b is formed integrally with the first gear 41a.

The second gear train 42 is composed of a third gear 42a supported on the first rotating shaft 31 via bearing member B2 so as to be rotatable relative to the first rotating shaft 31, and a fourth gear 42c fixed to the second rotating shaft 32 and meshing with the third gear 42a. A second clutch gear 42b is formed integrally with the third gear 42a.

The first rotating shaft 31 is equipped with a first clutch 51. The first clutch 51 is composed of a clutch hub 51c fixed to the first rotating shaft 31, a sleeve 51b configured to be movable axially around the outer periphery of the clutch hub 51c, and an actuator 51a that moves the sleeve 51b in the axial direction. The outer peripheries of the clutch hub 51c, first clutch gear 41b, and second clutch gear 42b are formed into cylindrical surfaces of the same diameter, and spline grooves parallel to the axial direction are formed on the outer peripheries. The sleeve 51b engages with spline grooves formed on the outer peripheries of the clutch hub 51c, first clutch gear 41b, and second clutch gear 42b, respectively, and moves in the axial direction.

The actuator 51a moves the sleeve 51b axially toward the first gear 41a (left side in Figure 1), thereby establishing a state (first state) in which the clutch hub 51c and first clutch gear 41b are connected by the sleeve 51b. The actuator 51a also moves the sleeve 51b axially toward the third gear 42a (right side in Figure 1), thereby establishing a state (second state) in which the clutch hub 51c and second clutch gear 42b are connected by the sleeve 51b. The actuator 51a also moves the clutch hub 51c to the outer periphery of the sleeve 51b, thereby establishing a neutral state (third state) in which the clutch hub 51c is not connected to either the first clutch gear 41b or the second clutch gear 42b.

The control device 80 controls the position of the actuator 51a to switch between the first, second, and third states.

In the first state, the clutch hub 51c and the first clutch gear 41b are connected, and the rotation of the first rotating shaft 31 is transmitted to the second rotating shaft 32 via the first gear 41a and the second gear 41c. The reduction ratio (first reduction ratio) at this time is the gear ratio between the first gear 41a and the second gear 41c.

In the second state, the clutch hub 51c and the second clutch gear 42b are connected, and the rotation of the first rotating shaft 31 is transmitted to the second rotating shaft 32 via the third gear 42a and the fourth gear 42c. The reduction ratio (second reduction ratio) at this time is the gear ratio between the third gear 42a and the fourth gear 42c. The first reduction ratio is set to a reduction ratio (LO gear) greater than the second reduction ratio.

In the third state, the rotation of the first rotating shaft 31 is not transmitted to the second rotating shaft 32.

In this way, the first transmission mechanism 11 is configured to be able to switch between two reduction ratios, the first reduction ratio and the second reduction ratio, between the first rotating shaft 31 and the second rotating shaft 32, which are arranged in parallel.

Furthermore, on the first rotating shaft 31, the engine 20 has its crankshaft connected to the engine-side rotating shaft 311, which is connected to the end of the first rotating shaft 31 via the second clutch 52. The second clutch 52 is configured as a one-way clutch that does not transmit the rotation of the engine-side rotating shaft 311 from the first rotating shaft 31, but transmits the rotation of the engine-side rotating shaft 311 caused by the engine 20 to the first rotating shaft 31.

Therefore, when only the motor 10 is driven and the engine 20 is not, the rotation of the first rotating shaft 31 is not transmitted to the engine 20. Here, by starting the engine 20 and increasing the rotational speed of the engine 20 to a speed equal to or greater than the rotational speed of the first rotating shaft 31, the driving force of the engine 20 is transmitted to the first rotating shaft 31 via the second clutch 52, which is a one-way clutch. This transmits the driving force of the engine 20 to the first rotating shaft 31, and the driving force is then transmitted to the drive wheels 70 via the first transmission mechanism 11 and the second transmission mechanism 12. Since the rotation of the motor 10 is not transmitted to the engine 20, the engine 20 is equipped with a starter motor (not shown) for cranking the engine 20 to start it.

When the first clutch 51 is in the third state, the rotation of the engine 20 is transmitted only to the motor 10 via the first rotating shaft 31, and is not transmitted to the second rotating shaft 32. In this way, for example, when the vehicle is stopped, the motor 10 can be rotated by driving the engine 20, thereby generating electricity using the motor 10.

The second transmission mechanism 12 reduces the rotation of the second rotating shaft 32 at the third reduction ratio of the third gear train 43 and transmits it to the differential device 35.

The second transmission mechanism 12 includes a third gear train 43 between the second rotating shaft 32 and the differential device 35. The third gear train 43 includes a fifth gear 43a fixed to the second rotating shaft 32 and a sixth gear 43b fixed to the differential device 35 of the axle 33 and meshing with the fifth gear 43a. The rotation of the second rotating shaft 32 is transmitted to the differential device 35 via the third reduction ratio of the third gear train 43.

Next, we will explain how the vehicle runs using the drive system 1 configured in this way.

Figure 2 is an explanatory diagram of the driving state using the drive system 1 of this embodiment.

[Driving from vehicle start to predetermined speed]
When starting the vehicle from a stopped state, the control device 80 switches the first transmission mechanism 11 to the first state, i.e., controls the actuator 51a of the first clutch 51 to switch the rotation of the first rotating shaft 31 to the second rotating shaft 32 via the first gear train 41, and drives the motor 10. As a result, the rotation of the motor 10 is transmitted from the first rotating shaft 31 through the first gear train 41 to the second rotating shaft 32, and the vehicle starts moving. At this time, the rotation of the first rotating shaft 31 is not transmitted to the engine 20 due to the second clutch 52, so the engine 20 can be kept stopped.

The control device 80 drives the vehicle in the first state using the driving torque of the motor 10 until the vehicle speed reaches a predetermined speed (e.g., 40 km/h). This predetermined speed is set so that, when the driving torque of the engine 20 is transmitted via the second gear train 42, the predetermined vehicle speed can be achieved at a rotational speed of the engine 20 that is sufficient to prevent noise and vibration problems (e.g., 2000 rpm).

[Driving at a specified speed or faster]
When the vehicle speed reaches or exceeds a predetermined vehicle speed (dotted line in FIG. 2 ), the control device 80 controls the actuator 51 a of the first clutch 51 to switch the first transmission mechanism 11 from the first state to the second state. As a result, the rotation of the first rotating shaft 31 is transmitted to the second rotating shaft 32 at the second reduction ratio by the second gear train 42. Then, the engine 20 is started so that the rotation of the engine 20 is transmitted to the first rotating shaft 31.

At this time, when the rotational speed of the engine 20 becomes greater than the rotational speed of the first rotating shaft 31, the second clutch 52, which is a one-way clutch, transmits the rotation of the engine 20 to the first rotating shaft 31. As a result, the driving torque of the engine 20 becomes dominant over the driving torque of the motor 10, and the vehicle can be driven by these driving torques. The second reduction ratio of the second gear train 42 of the first transmission mechanism 11 is set to a reduction ratio such that, at a predetermined vehicle speed (40 km/h), the rotational speed of the engine 20 is equal to or greater than a rotational speed (2000 rpm) that does not cause noise and vibration problems.

In addition, when traveling at or above a predetermined vehicle speed, in operating conditions where the drive torque required for vehicle travel is fully covered by the drive torque of the motor 10 (for example, when the vehicle is on a flat road and no acceleration or deceleration is required), the engine 20 may be stopped and only the drive torque of the motor 10 may be transmitted to the drive wheels 70 via the second gear train 42 to allow the vehicle to travel.

[Charge Battery]
As described above, when the engine 20 is started and the vehicle is running on the driving torque of the engine 20, if the driving torque of the engine 20 is sufficiently greater than the driving torque required for the vehicle to run, the control device 80 sets the motor 10 to a power generating state. As a result, the driving torque that is the amount by which the driving torque of the engine 20 exceeds the driving torque required for the vehicle to run is transmitted to the motor 10, allowing the motor 10 to generate power while the vehicle is running. The generated power is charged to the battery.

[Continuous operation at low speed]
For example, in a driving condition where a large driving torque is continuously required during low-speed driving, such as when driving uphill, the battery charge capacity may be insufficient to drive the motor 10. In such a case, the control device 80 starts the engine 20 and switches the first transmission mechanism 11 to the first state. This causes the rotation of the engine 20 to be transmitted to the second rotating shaft 32 at the first reduction ratio. In this way, the vehicle can be driven by the driving torque of the engine 20 during low-speed driving. At this time, the driving torque of the engine 20 that exceeds the driving torque required for vehicle driving is transmitted to the motor 10, allowing the motor 10 to generate electricity.

[Vehicle deceleration]
When the vehicle decelerates, the rotation of the drive wheels 70 is transmitted from the axle 33 to the second rotating shaft 32 and the first rotating shaft 31, causing the motor 10 to rotate. At this time, the control device 80 sets the motor 10 to a power generating state. This causes the motor 10 to perform regeneration (power generation). At this time, if there is no need to accelerate the vehicle, the engine 20 is stopped. By causing the motor 10 to generate power, a brake torque is generated, allowing the vehicle to decelerate.

If the vehicle further decelerates and its speed falls below the predetermined speed, the control device 80 switches the first transmission mechanism 11 from the second state to the first state using the first clutch 51. This causes the rotation of the drive wheels 70 to be transmitted from the second rotating shaft 32 to the first rotating shaft 31 at the first reduction ratio, and the rotation of the motor 10 is accelerated beyond the second speed ratio, thereby increasing the amount of power generation.

[Vehicle Stop]
When the vehicle is stopped, the control device 80 switches the first clutch 51 to the third state so that the rotation of the first rotating shaft 31 is not transmitted to the second rotating shaft 32. At this time, if the motor 10 needs to generate electricity because, for example, the battery capacity is insufficient, the control device 80 starts the engine 20 and sets the motor 10 to a power generating state. This allows the motor 10 to be driven by the rotation of the first rotating shaft 31, causing the motor 10 to generate electricity. The generated electricity is charged to the battery. Note that when there is no need to charge the battery or when the ignition key is set to off, the control device 80 stops the engine 20.

The embodiment of the present invention described above is a drive system 1 for a vehicle equipped with a motor 10 and an engine 20, and driven by the driving force of at least one of the motor 10 and the engine 20. The drive system 1 includes a first rotating shaft 31 connected to the motor 10, a first transmission mechanism 11 that reduces the rotation of the first rotating shaft 31 and transmits it to the second rotating shaft 32, and a second transmission mechanism 12 that reduces the rotation of the second rotating shaft 32 and transmits it to the axle 33. The engine 20 is connected to the first rotating shaft 31 via a second clutch 52 that interrupts the transmission of rotation. The first transmission mechanism 11 includes a first gear train 41 that changes the rotation of the motor 10 and transmits it to the second rotating shaft 32, a second gear train 42 that changes the rotation of the engine 20 and transmits it to the second rotating shaft 32, and a first clutch 51 that switches between the first gear train 41 and the second gear train 42.

This configuration is composed of three shafts: the first rotating shaft 31, the second rotating shaft 32, and the axle 33, and two gear trains: the first gear train 41 and the second gear train 42. The rotation of the motor 10 or the engine 20 can be output by switching between the first gear train 41 and the second gear train 42, minimizing the number of parts and weight of the drive system 1 and making it compact in size.

In addition, in this embodiment, the first transmission mechanism 11 is configured so that the gear ratio of the first gear train 41 is greater than the gear ratio of the second gear train 42.

In this configuration, when a large torque is required, such as when starting the vehicle, the first gear train 41, which has a large reduction ratio, can be selected and the vehicle can be started by driving the motor 10.

In addition, in this embodiment, the second clutch 52 is a one-way clutch that transmits the rotation of the engine 20 to the first rotating shaft 31 when the rotation speed of the engine 20 is greater than the rotation speed of the motor 10.

In this configuration, when the engine 20 is not driven, the rotation of the motor 10 is not transmitted to the engine 20, and the vehicle runs using the driving torque of the motor 10. When the engine 20 is driven, the rotation of the engine 20 is transmitted to the first rotating shaft 31, and the vehicle runs using the driving torque of the engine 20.

In addition, in this embodiment, the first transmission mechanism 11 selects the first gear train 41 by the first clutch 51 when the vehicle starts, and selects the second gear train 42 state by the first clutch 51 when the vehicle is traveling steadily at a predetermined speed or higher.

In this configuration, when the vehicle starts, the driving torque of the motor 10 is transmitted by the first gear train 41, which has a large reduction ratio, allowing the vehicle to start moving, and when the vehicle is running steadily, the driving torque of the engine 20 is transmitted by the second gear train 42, allowing the vehicle to run.

In addition, in this embodiment, when the first gear train 41 is selected by the first clutch 51, the rotation of the engine 20 is transmitted to the first rotating shaft 31 via the second clutch 52, and the rotation of the engine 20 is transmitted to the second rotating shaft 32 by the first gear train 41.

In this configuration, for example, when traveling uphill, the rotation of the engine 20 is transmitted to the second rotating shaft 32 at the first reduction ratio, allowing the vehicle to travel at low speeds using the driving torque of the engine 20.

In addition, in this embodiment, the motor 10 and engine 20 are arranged facing each other on both ends of the first rotating shaft 31. In this configuration, the first transmission mechanism 11 can be arranged between the motor 10 and the engine 20, allowing the size of the drive system 1 to be made compact.

In addition, in this embodiment, the first rotating shaft 31, the second rotating shaft 32, and the axle 33 are arranged in parallel with one another. With this configuration, the rotation of the motor 10 and the engine 20 can be transmitted to the drive wheels 70 after being changed in speed using only three shafts, making it possible to further reduce the size of the drive system 1.

The above describes embodiments of the present invention, but the configurations described in the above embodiments and each modified example only represent some of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

In the above-described embodiment, the first transmission mechanism 11 is configured such that the first gear train 41 and the second gear train 42 each reduce the speed of the rotation of the first rotating shaft 31 before transmitting it to the second rotating shaft 32, but reduction is not necessarily required. It is sufficient that the first gear train 41 and the second gear train 42 are configured to change the speed of the rotation of the first rotating shaft 31 before transmitting it to the second rotating shaft 32. Similarly, the second transmission mechanism 12 is configured to change the speed of the rotation of the second rotating shaft 32 before transmitting it to the differential 35 of the axle 33.

1: Drive system, 10: Motor, 11: First transmission mechanism, 12: Second transmission mechanism, 20: Engine, 31: First rotating shaft, 32: Second rotating shaft, 33: Axle, 41: First gear train, 42: Second gear train, 51: First clutch, 52: Second clutch, 80: Control device

Claims (5)

A drive system for a vehicle that includes a motor and an engine and runs on driving force from at least one of the motor and the engine,
a first rotating shaft having one end connected to the motor;
a first speed change mechanism that changes the speed of rotation of the first rotating shaft and transmits the rotation to a second rotating shaft;
a second transmission mechanism that changes the speed of rotation of the second rotating shaft and transmits the rotation to an axle;
Equipped with
The engine is connected to the other end of the first rotary shaft via a second clutch that interrupts the transmission of rotation,
the first transmission mechanism includes: a first gear train composed of a first gear supported rotatably relative to the first rotating shaft and a second gear fixed to the second rotating shaft, and transmitting rotation of the first rotating shaft to the second rotating shaft at a first reduction ratio; a second gear train composed of a third gear supported rotatably relative to the first rotating shaft and a fourth gear fixed to the second rotating shaft, and transmitting rotation of the first rotating shaft to the second rotating shaft at a second reduction ratio smaller than the first reduction ratio ; and a first clutch that switches between the first gear train and the second gear train ,
the second transmission mechanism includes a third gear train including a fifth gear fixed to the second rotary shaft and a sixth gear fixed to a differential device of the axle;
Vehicle drive system. 2. A vehicle drive system according to claim 1,
the second clutch is a one-way clutch that transmits the rotation of the engine to the first rotating shaft when the rotation speed of the engine exceeds the rotation speed of the motor.
Vehicle drive system. 2. A vehicle drive system according to claim 1 ,
The first transmission mechanism is
When the vehicle starts moving, the first clutch selects the first gear train,
When the vehicle is traveling at a steady speed equal to or higher than a predetermined speed, the second gear train is selected by the first clutch.
Vehicle drive system. 2. A vehicle drive system according to claim 1 ,
In the first transmission mechanism, when the first gear train is selected by the first clutch, the rotation of the engine is transmitted to the first rotating shaft via the second clutch, and the rotation of the engine is transmitted to the second rotating shaft by the first gear train.
Vehicle drive system. 2. A vehicle drive system according to claim 1,
The first rotation shaft, the second rotation shaft, and the axle are arranged in parallel to each other.
Vehicle drive system.