CN103010009B - Electric vehicle powertrain and two gear variable-speed dynamic drivings device thereof - Google Patents

Abstract

The present invention relates to an electric vehicle power system and a two-speed variable speed power transmission device thereof. The power transmission device includes a housing fixedly installed on the frame of the vehicle. The housing is provided with a drive motor, a drive shaft extending axially along the front and rear directions, and In the planetary gear transmission mechanism, the rotor of the drive motor is connected to the sun gear, the internal gear is coaxially fixed on the drive shaft, the planet carrier has first and second power transmission ends, and the planet gear is set on the planet On the first power transmission end of the carrier, a first clutch is provided between the second power transmission end of the planet carrier and the casing, and the planet carrier can be selectively connected or disconnected from the casing through the first clutch; the planet carrier A second clutch is provided between the second power transmission end of the inner gear and the inner gear, and the planet carrier is selectively connected or disconnected from the inner gear through the second clutch. The invention provides a power transmission device capable of two-speed shifting.

Description

Electric vehicle power system and its two-speed variable speed power transmission device

technical field

The invention relates to a vehicle power system for an electric vehicle and a two-speed variable speed power transmission device thereof.

Background technique

With the aggravation of the world's energy shortage and environmental pollution, energy saving and environmental protection have become the development direction of modern vehicles, and electric vehicles provide a way to solve the above problems. An electric vehicle is a vehicle driven by a driving motor alone or jointly driven by an engine and a driving motor, and the electric vehicle power system is the power generation and transmission mechanism of the electric vehicle, and is the artery of the whole vehicle. At present, the power system of electric vehicles is relatively mature and has various forms. However, the power system of electric vehicles, especially the pneumatic transmission device, is not perfect, and the highest efficiency transmission of the motor cannot be guaranteed in the process of driving the vehicle, and the structure is not compact enough. It is difficult to give full play to the advantages of electric vehicles in terms of energy saving and environmental protection.

Existing electric vehicle power systems such as the "plug-in integrated starter generator hybrid car drive system" disclosed in Chinese patent CN101293478A, the drive system includes power input components and a power transmission device, and the power transmission device includes a drive motor and a planetary gear transmission mechanism And the drive shaft for transmission connection to the corresponding wheel, the drive motor is connected with the drive shaft through the planetary gear transmission mechanism; the power input component includes the engine and the ISG motor with two power transmission ends for power input or power output, where the ISG One power transmission end of the motor is connected to the power output end of the engine, and the other power transmission end of the ISG motor is connected to the drive shaft through a clutch. Although the existing electric vehicle power system realizes deceleration and torque increase through the planetary gear transmission mechanism, it cannot realize gear shifting, which limits the economic performance.

Contents of the invention

The purpose of the present invention is to provide a power transmission device capable of two-speed transmission; the purpose of the present invention is also to provide an electric vehicle power system using the power transmission device.

In order to solve the above problems, the technical scheme of the two-speed variable speed power transmission device in the present invention is:

The two-speed variable speed power transmission device includes a housing for fixed installation on the vehicle frame of the corresponding vehicle. The housing is provided with a drive motor, a drive shaft extending axially along the front and rear directions, and a planetary gear, a sun gear, and a planetary carrier. 1. The planetary gear transmission mechanism of the internal gear, the rotor of the drive motor is connected to the sun gear, the internal gear is coaxially fixed on the drive shaft, and the planet carrier has first and second Two power transmission ends, the planetary gear is arranged on the first power transmission end of the planet carrier, a first clutch is arranged between the second power transmission end of the planet carrier and the housing, the planet The carrier is selectively connected or disconnected from the housing through the first clutch; a second clutch is provided between the second power transmission end of the planet carrier and the internal gear, and the planet carrier passes through the The second clutch can be selectively connected to or disconnected from the internal gear.

The second power transmission end of the planet carrier has front and rear installation bases facing away from each other. The driving discs of the first and second clutches are respectively installed on the front and rear installation bases. A driven plate of a clutch is fixedly connected with the housing, and a driven plate of the second clutch is fixedly connected with the internal gear.

The first and second clutches are electronically controlled clutches or manually controlled clutches.

The technical scheme of the electric vehicle power system in the present invention is:

The electric vehicle power system includes a power output unit and a power transmission device. The power transmission device includes a housing for fixed installation on the vehicle frame of the corresponding vehicle. The housing is provided with a drive motor, and the shaft extends along the front and rear directions The drive shaft and the planetary gear transmission mechanism with planetary gears, sun gears, planetary carriers, and internal gears, the rotor of the drive motor is in transmission connection with the sun gear, and the internal gear is coaxially fixed on the drive On the shaft, the planetary carrier has first and second power transmission ends, the planetary gear is arranged on the first power transmission end of the planetary carrier, and the second power transmission end of the planetary carrier is connected to the A first clutch is arranged between the casings, and the planetary carrier is selectively connected or disconnected from the casing through the first clutch; the second power transmission end of the planetary carrier and the internal gear A second clutch is arranged between them, and the planet carrier is selectively connected or disconnected from the internal gear through the second clutch.

The second power transmission end of the planet carrier has front and rear installation bases facing away from each other. The driving discs of the first and second clutches are respectively installed on the front and rear installation bases. A driven plate of a clutch is fixedly connected with the housing, and a driven plate of the second clutch is fixedly connected with the internal gear.

The power output unit includes a power battery and a drive motor controller, and the power battery is electrically connected to the drive motor through the drive motor controller.

The power output unit further includes an engine, and the power output end of the engine is in transmission connection with the drive shaft through a third clutch.

The power output unit also includes an engine, a third clutch, and an ISG motor with two power transmission ends, one of the power transmission ends of the ISG motor is in drive connection with the power output end of the engine, and the other of the ISG motor A power transmission end is connected to the drive shaft through the third clutch, and the power battery is electrically connected to the ISG motor through the ISG motor controller.

The power battery is provided with an external plug.

The first, second and third clutches are electronically controlled clutches or manually controlled clutches.

The beneficial effects of the present invention are: the two-speed variable speed power transmission device of the present invention can realize five working modes: 1. Low-speed gear transmission mode, when the vehicle starts or runs at low speed and heavy load, the first clutch is engaged and the second clutch is disengaged. At this time, the planetary frame is connected to the frame through the shell, and the planetary gear transmission mechanism acts as a large transmission ratio reduction box, which realizes the effect of deceleration and torque increase; 2. In the direct transmission mode, when the vehicle is running at medium and high speeds, the first clutch is disconnected , the second clutch is engaged, the planetary carrier and the internal gear are locked, and the entire planetary gear transmission mechanism rotates as a whole, which is a direct transmission mode, which realizes the transmission without loss of drive motor efficiency; 3. Neutral mode, when the vehicle is stopped, the first 1. Both the second clutches are disconnected to realize the power cut-off, and the whole vehicle is in the neutral state; 4. In the parking mode, when the vehicle stops for a long time, both the first and second clutches are engaged, and the drive shaft, the planetary gear transmission mechanism and the frame are connected Integrated, the whole vehicle is in the parking mode; 5. Reverse gear mode, when the vehicle needs to be reversed, the driving motor reverses, the first clutch is engaged, and the second clutch is separated. Acting as a gearbox with a large transmission ratio, it realizes the deceleration and torque increase effect on the drive motor, and the whole vehicle is in reverse gear mode. In the present invention, two clutches are used as the execution parts for the vehicle to switch among low-speed gear, direct gear, neutral gear and parking gear, and through different combinations of connection modes between the two clutches and the corresponding parts of the planetary gear transmission mechanism, the vehicle is in low-speed gear. , direct gear, neutral gear and parking gear, so as to achieve the purpose of speed change. It has the advantages of compact structure, large transmission ratio, large load capacity, stable transmission and high transmission efficiency. Through a large transmission ratio, it can directly Connected with the drive axle, no need to set up other reducers. At the same time, through two clutches and a planetary gear transmission mechanism, the power demand of the drive motor is greatly reduced under the same output power condition, and the torque output is greatly improved under the same motor power condition, avoiding the complicated speed change system.

Furthermore, the first and second clutches are both electronically controlled clutches, which eliminates the clutch pedal, gear shift lever and other devices of traditional vehicles through electric control, simplifies the operation of the vehicle, and well adapts to the characteristics of electric transmission vehicles. ; Since the technology of the electronically controlled clutch is relatively mature and the control requirements are low, the present invention skillfully utilizes the mature technology, and the manufacturing and use costs are low.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of a two-speed variable speed power transmission device in the present invention;

Fig. 2 is a schematic structural view of Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 3 is the energy transfer route diagram of the low-speed driving mode in Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 4 is an energy transfer route diagram of the high-speed drive mode in Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 5 is an energy transfer route diagram of the neutral parking mode in Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 6 is an energy transfer route diagram of the parking mode in Embodiment 1 of the electric vehicle power system of the present invention;

Fig. 7 is an energy transfer route diagram of deceleration braking mode in Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 8 is an energy transfer route diagram of high-speed gliding mode in Embodiment 1 of the electric vehicle power system in the present invention;

Fig. 9 is a schematic structural view of Embodiment 2 of the electric vehicle power system in the present invention;

Fig. 10 is a schematic structural view of Embodiment 3 of the electric vehicle power system in the present invention;

Fig. 11 is a schematic structural view of Embodiment 4 of the electric vehicle power system in the present invention;

Fig. 12 is a schematic structural view of Embodiment 5 of the electric vehicle power system in the present invention.

detailed description

The embodiment of the two-speed variable-speed power transmission device is shown in Figure 1: it includes a housing 2 that is fixedly installed on the vehicle frame of the corresponding vehicle, the housing 2 is provided with a drive shaft 7, a drive motor 1 with power generation function and a In the planetary gear transmission mechanism 6 including the planetary gear 6b, the sun gear 6c, the planetary carrier 6d, and the internal gear 6a, the axial direction of the drive shaft 7 extends in the front-rear direction. The stator 1b of the driving motor 1 is fixed on the housing 2, the rotor 1a of the driving motor is connected to the sun gear 6, the internal gear 6a is coaxially fixed on the driving shaft 7, and the planet carrier 6d has the first and second power At the transmission end, the planetary gear 6b is arranged on the first power transmission end of the planet carrier 6d, the first clutch 3 is arranged between the second power transmission end of the planet carrier 6d and the housing 2, and the first clutch 3 is arranged between the inner gear 6a and the internal gear 6a. Two clutches 4, on the second power transmission end of planet carrier 6d, there are front and rear mounting bases facing away from each other, the driving disc 3b of the first clutch is installed on the front mounting base, and the driving disc 4a of the second clutch is installed on On the rear installation base, the driven disc 3a of the first clutch is installed on the housing 2, the driven disc 4b of the second clutch is installed on the internal gear 6a, the first and second clutches are both electronically controlled clutches, and the planet carrier The second power transmission end is selected to be brake-connected to the housing through the first clutch and/or to be connected to the internal gear through the second clutch.

The two-speed variable power transmission device of the present invention can realize the following five operating modes: 1. Low-speed gear transmission mode. When the vehicle starts or runs at low speed and heavy load, the first clutch is engaged and the second clutch is separated. The shell is connected with the frame, and the planetary gear transmission mechanism acts as a large transmission ratio reduction box, which realizes the effect of deceleration and torque increase; 2. In the direct transmission mode, when the vehicle is running at medium and high speeds, the first clutch is disconnected and the second clutch is engaged , the planetary carrier and the internal gear are locked, and the entire planetary gear transmission mechanism rotates as a whole, which is a direct transmission mode, which realizes the transmission without loss in the efficiency of the drive motor; 3. Neutral mode, when the vehicle is stopped, the first and second clutches are both disconnected 4. In the parking mode, when the vehicle stops for a long time, both the first and second clutches are engaged, and the drive shaft, the planetary gear transmission mechanism and the frame are connected together, and the whole vehicle is in neutral position. Parking mode; 5. Reverse gear mode. When reversing is required, the drive motor reverses, the first clutch is engaged, and the second clutch is disengaged. At this time, the planetary carrier is connected to the frame through the housing, and the planetary gear transmission mechanism acts as a large transmission ratio. The reduction box realizes the deceleration and torque increase effect on the driving motor, and the whole vehicle is in the reverse gear mode.

Through the use of the electronically controlled clutch, the traditional vehicle clutch pedal, shift lever and other devices are omitted, the handling of the vehicle is simplified, the use characteristics of the electric drive vehicle are well adapted, and the mature technology is cleverly used , Low cost of manufacture and use. Of course, in other embodiments of the power transmission device, the first and second clutches can also be manually controlled clutches.

Electric vehicles are divided into pure electric drive mode, hybrid electric drive mode and plug-in hybrid electric drive mode, etc., which are described below as examples.

Embodiment 1 of the electric vehicle power system is shown in Figures 2 to 8: it includes a power output unit and a power transmission device. The specific structure of the power transmission device is the same as the above-mentioned embodiments of the power transmission device, and will not be described in detail here. The power output unit includes a power battery 10 and a drive motor controller 9 , and the power battery 10 is connected to the drive motor 1 through the drive motor controller 9 . Figure 8 represents the drive axle.

As a power unit, the drive motor can convert the electric energy of the power battery into mechanical energy, which is transmitted to the wheels through the mechanical system, and can also convert the kinetic energy of the vehicle transmitted from the mechanical system into electrical energy, which is charged into the power battery.

The first and second clutches are used as mode switching devices. The first clutch 3 is disconnected and the second clutch 4 is engaged, or the second clutch 4 is disconnected and the first clutch 3 is engaged to realize the normal running of the vehicle. Engage to realize parking brake; also can disengage both clutches to realize neutral gear.

As a power transmission device, the planetary gear transmission mechanism can cooperate with the first and second clutches to realize two different transmission ratios. When the first clutch is engaged and the second clutch is disconnected, the vehicle can run at a low speed by providing a large transmission ratio. When one clutch is disconnected and the second clutch is engaged, the vehicle can run at a high speed by providing a small transmission ratio.

In the low-speed driving mode, as shown in Figure 3, the first clutch 3 is engaged, the second clutch 4 is disengaged, the planet carrier is fixed, the electric energy of the power battery 10 is converted into mechanical energy through the drive motor 1, and the sun through the planetary gear transmission mechanism 6 Wheels, planetary gears and internal gears are decelerated and transmitted to the wheels to drive the vehicle. The direction of the arrow in the figure indicates the energy transfer direction.

In the high-speed driving mode, as shown in Figure 4, the first clutch 3 is disengaged, the second clutch 4 is engaged, and the planetary carrier and the internal gear are locked together. The electric energy of the battery 10 is converted into mechanical energy through the driving motor 1, and is directly transmitted to the vehicle through the planetary gear transmission mechanism 6 to drive the vehicle to run.

When the vehicle stops, as shown in Figure 5, the first and second clutches are disconnected to realize power cut-off, and the whole vehicle is in a neutral state.

When the vehicle is stopped for a long time, as shown in Figure 6, the first and second clutches are engaged, the drive shaft and the planetary gear transmission mechanism are connected with the vehicle frame 5 through the housing 2, and the vehicle is in the parking mode.

In deceleration braking mode, as shown in Figure 7, the first clutch is engaged, the second clutch is disengaged, the planet carrier is fixed, the kinetic energy of the vehicle is transmitted through the planetary gear transmission mechanism, converted into electric energy by the drive motor, and charged into the power battery , the vehicle is in regenerative braking state.

In the high-speed coasting mode, as shown in Figure 8, the first clutch is disengaged, the second clutch is engaged, and the planetary carrier and the internal gear are locked together. After the drive motor is converted into electric energy and charged into the power battery, the whole vehicle is in a sliding feedback state.

Embodiment 2 of the electric vehicle power system is shown in FIG. 9: different from Embodiment 1 of the electric vehicle power system, the power output unit further includes an engine 12, and the power output end of the engine 12 is connected to the drive shaft 7 through the third clutch 11. Drive connection. The third clutch is an electronically controlled clutch.

The first, second and third clutches are used as mode switching devices. Through the disconnection or engagement of the first, second and third clutches, the vehicle's pure electric driving mode, engine independent driving mode, driving charging mode, parallel hybrid driving mode, Neutral mode, parking mode, deceleration braking mode and high speed coasting mode.

As a power transmission device, the planetary gear transmission mechanism can cooperate with the corresponding clutch to realize two different transmission ratios. When the first clutch is engaged and the second clutch is disconnected, the vehicle can run at low speed by providing a large transmission ratio. When the second clutch is engaged, the vehicle can run at a high speed by providing a small transmission ratio.

In the low-speed pure electric driving mode, the third clutch is disengaged, the first clutch is engaged, the second clutch is disengaged, the planetary carrier is fixed, the electric energy of the power battery is converted into mechanical energy by the drive motor, and then transmitted to the wheels after being decelerated by the planetary gear transmission mechanism , driving the vehicle.

In the high-speed engine independent drive mode, the third clutch is engaged, the first clutch is disengaged, the second clutch is engaged, the planetary carrier and the internal gear are locked together, and the internal gear, the planetary carrier and the sun gear rotate together at the same speed, and the mechanical energy of the engine It is directly transmitted to the vehicle through the planetary gear transmission mechanism to drive the vehicle.

In the driving charging mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planetary carrier and the internal gear are locked together. At this time, the internal gear, the planetary carrier and the sun gear rotate at a constant speed, and part of the mechanical energy of the engine passes through The planetary gear transmission mechanism directly transmits to the wheels to drive the vehicle; the other part of the mechanical energy is transmitted to the driving motor in the reverse power generation state through the sun gear, converted into electrical energy, and charged into the power battery.

In the parallel hybrid drive mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planetary carrier and the internal gear are locked together. The drive motor is converted into mechanical energy, and the mechanical energy of the superimposed engine is transmitted to the wheels through the planetary gear transmission mechanism to drive the vehicle.

When the vehicle is stopped, the first, second and third clutches are all disconnected to realize power cut-off, and the whole vehicle is in a neutral state.

When the vehicle stops running for a long time, the third clutch is disconnected, the first and second clutches are both engaged, the drive shaft and the planetary gear transmission mechanism are connected with the vehicle frame, and the vehicle is in the parking mode.

In deceleration braking mode, the third clutch is disengaged, the first clutch is engaged, the second clutch is disengaged, the planet carrier is fixed, the kinetic energy of the vehicle is transmitted through the planetary gear transmission mechanism, converted into electric energy by the drive motor, and charged into the power battery. The vehicle is in regenerative braking state.

In the high-speed coasting mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planetary carrier and the internal gear are locked together. The driving motor is converted into electric energy, which is charged into the power battery, and the whole vehicle is in the feedback state of coasting.

In other embodiments of the electric vehicle power system, the third clutch may also be a manually controlled clutch.

Embodiment 3 of the electric vehicle power system is shown in Figure 10: the difference between embodiment 3 and embodiment 2 of the electric vehicle power system is that the power battery is provided with an external plug 16, and the external plug 16 can charge the power battery through an external electric post .

Embodiment 4 of the electric vehicle power system is shown in Figure 11: Embodiment 4 is different from the electric vehicle power system embodiment 2 in that an ISG motor 13 with two power transmission ends is arranged between the third clutch 11 and the engine 12 One of the power transmission ends of the ISG motor 13 is in transmission connection with the third clutch 11 , the other power transmission end is in transmission connection with the power output end of the engine 12 , and the power battery 10 is connected with the ISG motor 13 through the ISG motor controller 14 .

The drive motor and the engine are used as the power unit, which can respectively convert the electric energy of the power battery and the chemical energy of the fuel into mechanical energy, which is transmitted to the wheels through the mechanical system, and can also convert the kinetic energy of the vehicle transmitted by the mechanical system into electric energy, which is charged into the power battery; ISG motor As a generator and a starter motor, the mutual conversion between the mechanical energy of the engine and the electric energy of the power battery can be realized.

Each clutch is used as a mode switching device, and through the disconnection or engagement of the corresponding clutch, the pure electric mode, series mode, engine independent drive mode, driving charging mode, parallel drive mode, neutral mode, parking mode, and low-speed brake feedback mode are realized. And high-speed coasting feedback mode.

As a power transmission device, the planetary gear transmission mechanism can cooperate with the corresponding clutch to realize two different transmission ratios. When the first clutch is engaged and the second clutch is disconnected, the vehicle can run at low speed by providing a large transmission ratio. Open, when the second clutch is closed, the vehicle can run at a high speed by providing a small transmission ratio.

In the low-speed pure electric driving mode, the engine is turned off, the third clutch is disconnected, the first clutch is engaged, the second clutch is disengaged, the planet carrier is fixed, the electric energy of the power battery is converted into mechanical energy by the drive motor, and decelerated by the planetary gear transmission mechanism After that, it is passed to the wheels to drive the vehicle.

In the low-speed series mode, the engine is turned on, the third clutch is disconnected, the first clutch is engaged, the second clutch is disengaged, the planet carrier is fixed, the kinetic energy of the engine is first converted into electrical energy by the ISG motor and the ISG motor controller, and then by the drive motor The controller and the drive motor convert it into mechanical energy, which is finally transmitted to the wheels after being decelerated by the planetary gear transmission mechanism to drive the vehicle.

In the high-speed pure engine driving mode, the third clutch is engaged, the first clutch is disengaged, the second clutch is engaged, the planetary carrier and the internal gear are locked together, and the internal gear, the planetary carrier and the sun gear rotate together at the same speed, and the engine The mechanical energy is directly transmitted to the vehicle through the planetary gear transmission mechanism to drive the vehicle.

In the high-speed driving charging mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planet carrier and the internal gear are locked together. At this time, the internal gear, planet carrier and sun gear rotate at the same speed. The mechanical energy is directly transmitted to the vehicle through the planetary gear transmission mechanism to drive the vehicle; the other part of the mechanical energy is transmitted to the drive motor in the reverse power generation state through the sun gear, converted into electrical energy, and charged into the power battery.

In the parallel hybrid drive mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planetary carrier and the internal gear are locked together. The electric energy is converted into mechanical energy through the driving motor, and then transmitted to the wheels through the superimposed mechanical energy of the engine through the planetary gear transmission mechanism to drive the vehicle.

When the vehicle is stopped, the first, second and third clutches are all disconnected to realize power cut-off, and the whole vehicle is in a neutral state.

When the vehicle is stopped for a long time, the third clutch is disconnected, the first and second clutches are both engaged, the drive shaft and the planetary gear transmission mechanism are connected with the vehicle frame, and the vehicle is in the parking mode.

In deceleration braking mode, the third clutch is disengaged, the first clutch is engaged, the second clutch is disengaged, the planetary carrier is fixed, the kinetic energy of the vehicle is transmitted through the planetary gear transmission mechanism, converted into electrical energy by the motor, and charged into the power battery. The car is in regenerative braking state.

In the high-speed coasting mode, the third clutch is engaged, the first clutch is disengaged, and the second clutch is engaged. The planetary carrier and the internal gear are locked together. The driving motor is converted into electric energy, which is charged into the power battery, and the whole vehicle is in the feedback state of coasting.

Embodiment 5 of the electric vehicle power system is shown in Figure 12: the difference between embodiment 5 and embodiment 4 of the electric vehicle power system is that an external plug 16 is provided on the power battery 10, and the external plug 16 can be connected to Power battery charging.

Claims (10)

1. Two-speed variable speed power transmission device, including a housing for fixed installation on the frame of the corresponding vehicle. The housing is provided with a drive motor with power generation function, a drive shaft extending axially along the front and rear directions, and a planetary gear 1. The planetary gear transmission mechanism of sun gear, planet carrier, and internal gear, characterized in that: the rotor of the drive motor is connected to the sun gear, and the internal gear is coaxially fixed on the drive shaft. The planetary carrier has first and second power transmission ends, the planetary gear is arranged on the first power transmission end of the planetary carrier, and the second power transmission end of the planetary carrier is connected to the casing. A first clutch is arranged between, and the planetary carrier is selectively connected or disconnected from the housing through the first clutch; a second power transmission end of the planetary carrier and the internal gear are arranged between The second clutch, through which the planetary carrier is selectively connected or disconnected from the internal gear. 2. The power transmission device according to claim 1, characterized in that: the second power transmission end of the planet carrier has front and rear mounting bases facing away from each other, and the first clutch and the second clutch have The driving disc is installed on the front and rear mounting bases respectively, the driven disc of the first clutch is fixedly connected with the housing, and the driven disc of the second clutch is fixedly connected with the internal gear. 3. The power transmission device according to claim 1 or 2, characterized in that: the first clutch and the second clutch are electronically controlled clutches or manually controlled clutches. 4. Electric vehicle power system, including a power output unit and a power transmission device. The power transmission device includes a housing for fixed installation on the vehicle frame of the corresponding vehicle, and the housing is provided with a driving motor with power generation function, A drive shaft extending axially along the front-to-back direction and a planetary gear transmission mechanism with a planetary gear, a sun gear, a planetary carrier, and an internal gear are characterized in that: the rotor of the drive motor is in transmission connection with the sun gear, and the internal gear The gears are coaxially fixed on the drive shaft, the planetary carrier has first and second power transmission ends, and the planetary gears are arranged on the first power transmission end of the planetary carrier. A first clutch is provided between the second power transmission end of the planet carrier and the casing, and the planet carrier can be selectively connected or disconnected from the casing through the first clutch; the first clutch of the planet carrier A second clutch is provided between the two power transmission ends and the internal gear, and the planet carrier is selectively connected or disconnected from the internal gear through the second clutch. 5. The electric vehicle power system according to claim 4, characterized in that: the second power transmission end of the planet carrier has front and rear installation bases facing away from each other, the first clutch, the second clutch The driving disc of the first clutch is fixedly connected to the housing, and the driven disc of the second clutch is fixedly connected to the internal gear. . 6. The electric vehicle power system according to claim 4, wherein the power output unit includes a power battery and a drive motor controller, and the power battery is electrically connected to the drive motor through the drive motor controller. connect. 7 . The electric vehicle power system according to claim 6 , wherein the power output unit further comprises an engine, and the power output end of the engine is in transmission connection with the drive shaft through a third clutch. 8 . 8. The electric vehicle power system according to claim 6, wherein the power output unit further comprises an engine, a third clutch and an ISG motor with two power transmission ends, one of the ISG motors transmits power end is connected to the power output end of the engine, the other power transmission end of the ISG motor is connected to the drive shaft through the third clutch, and the power battery is connected to the ISG motor through the ISG motor controller. electromechanical connection. 9. The electric vehicle power system according to any one of claims 6-8, characterized in that: the power battery is provided with an external plug. 10. The electric vehicle power system according to any one of claims 7-8, wherein the first clutch, the second clutch and the third clutch are electronically controlled clutches or manually controlled clutches.