Transmission and power system for use in hybrid vehicle

A transmission and a power system for use in a hybrid vehicle. A first ring gear or a first planetary frame is drivingly connected with an output gear of the transmission to serve as an output member, when either the first ring gear or the first planetary frame is drivingly connected with the output gear, the other one is connected with a casing of the transmission via a brake. A second clutch is configured as: when the brake is disengaged, the second clutch is engaged to make the rotational speed of the output member equal to the rotational speed of an input shaft. The transmission and the power system are structurally compact, work steadily, and effectively increase the acceleration performance of the hybrid vehicle.

TECHNICAL FIELD

The present invention relates to the technical field of hybrid vehicles, and in particular, to a transmission and a power system for use in hybrid vehicles.

BACKGROUND OF THE INVENTION

At present, the use of petrol-electric hybrid power as a vehicle power source has increasingly become the mainstream trend of vehicle development. A hybrid vehicle usually includes an engine with a smaller displacement than a traditional engine and one or two electric motors. Under normal circumstances, when driving at low speeds (such as urban roads) or when frequent starting is required, the vehicle can be driven only by the electric motor; when high-speed driving is required, the vehicle can be driven only by the engine to save energy. In the prior art, the hybrid mode of a petrol-electric hybrid vehicle mainly includes three modes: series, parallel and hybrid.

The structure of the power system in the existing hybrid vehicle is relatively simple and has poor adaptability.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a transmission for use in a hybrid vehicle with a simple structure but strong adaptability.

A further object of the present invention is to enable the transmission to provide a relatively large reduction ratio, and effectively reduce the size of the electric motor or improve the acceleration performance of the vehicle.

Another further object of the present invention is to simplify the power system of the hybrid vehicle, provide a relatively large reduction ratio, and effectively reduce the size of the electric motor or improve the acceleration performance of the vehicle.

In one aspect, the present invention provides a transmission for a hybrid vehicle. A first planetary gear mechanism, an input shaft, a first clutch, a second clutch and a brake are arranged in a casing of the transmission;

the first planetary gear mechanism comprises a first sun gear, a first planetary gear set, a first ring gear and a first planetary frame, the first sun gear is fixed on the input shaft so that the first sun gear rotates with the input shaft, either the first ring gear or the first planetary frame is in driving connection with an output gear of the transmission as an output member;

when one of the two components of the first ring gear and the first planetary frame is drivingly connected with the output gear, the other component is connected to the casing of the transmission through the brake; the second clutch is configured such that when the brake is disengaged, the second clutch is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft.

Optionally, when the first ring gear is drivingly connected with the output gear, the brake is arranged between the first planetary frame and the casing of the transmission, and the second clutch is arranged between the first ring gear and the input shaft or between the first ring gear and the first planetary frame, wherein when the brake is engaged and the second clutch is disengaged, the first gear of the transmission is realized; when the second clutch is engaged and the brake is disengaged, the second gear of the transmission is realized.

Optionally, when the first planetary frame is drivingly connected to the output gear, the brake is arranged between the first ring gear and the casing of the transmission, and the second clutch is arranged between the input shaft and the first planetary frame or between the input shaft and the first ring gear, wherein when the brake is engaged and the second clutch is disengaged, the first gear of the transmission is realized; when the second clutch is engaged and the brake is disengaged, the second gear of the transmission is realized.

In another aspect, the present invention also provides a power system for a hybrid vehicle. The power system includes an engine, a first electric motor, a second electric motor, a first planetary gear mechanism, an input shaft, a first clutch, a second clutch, and a brake;

the engine is connected to the first electric motor, the first clutch is arranged between the first electric motor and the input shaft to cut off or combine the power transmission between the first electric motor and the input shaft through the first clutch; the second electric motor is drivingly connected with the input shaft for driving the input shaft to rotate;

the first planetary gear mechanism comprises a first sun gear, a first planetary gear set, a first ring gear and a first planetary frame, the first sun gear is fixed on the input shaft so that the first sun gear rotates with the input shaft, either the first ring gear or the first planetary frame is drivingly connected with the output gear of the power system as an output member;

when one of the two components of the first ring gear and the first planetary frame is drivingly connected with the output gear, the other component is connected to a casing of the power system through the brake; the second clutch is configured such that when the brake is disengaged, the second clutch is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft.

Optionally, when the first ring gear is drivingly connected with the output gear, the brake is arranged between the first planetary frame and the casing of the power system, and the second clutch is arranged between the first ring gear and the input shaft or between the first ring gear and the first planetary frame, wherein when the brake is engaged and the second clutch is disengaged, the first gear of the power system is realized; when the second clutch is engaged and the brake is disengaged, the second gear of the power system is realized.

Optionally, when the first planetary frame is drivingly connected to the output gear, the brake is arranged between the first ring gear and the casing of the power system, and the second clutch is arranged between the input shaft and the first planetary frame or between the input shaft and the first ring gear, wherein when the brake is engaged and the second clutch is disengaged, the first gear of the power system is realized; when the second clutch is engaged and the brake is disengaged, the second gear of the power system is realized.

Optionally, the second electric motor is connected to the input shaft through a second planetary gear mechanism, the second planetary gear mechanism comprises a second sun gear, a second planetary gear set, a second ring gear and a second planetary frame.

Optionally, one of the three components of the second sun gear, the second ring gear and the second planetary frame is fixed relative to the casing of the power system, the rotor of the second electric motor is drivingly connected to one of the remaining two unfixed components to provide power thereto, and another unfixed component is drivingly connected to the input shaft to drive the input shaft.

In another aspect, the present invention also provides a transmission for a hybrid vehicle. The transmission includes a first planetary gear mechanism, a second planetary gear mechanism, an input shaft, a second clutch, a first brake and a second brake;

the first planetary gear mechanism comprises a first sun gear, a first planetary gear set, a first ring gear and a first planetary frame; the first sun gear is fixed on the input shaft so that the first sun gear rotates with the input shaft; the second planetary gear mechanism comprises a second sun gear, a second planetary gear set, a second ring gear and a second planetary frame; the second sun gear and the input shaft are independent of each other; wherein the second ring gear is fixedly connected to the first planetary frame, the first ring gear is fixedly connected to the second planetary frame, and the second planetary frame is used to transmit the power output by the transmission;

the first brake is arranged between the first planetary frame and a casing of the transmission, the second brake is arranged between the second sun gear and the casing of the transmission, and the second clutch is arranged between the second sun gear and the input shaft.

In another aspect, the present invention also provides a power system for a hybrid vehicle. The power system includes an engine, a first electric motor, a second electric motor, a first planetary gear mechanism, a second planetary gear mechanism, an input shaft, a first clutch, a second clutch, a first brake and a second brake;

the engine is connected to the first electric motor, the first clutch is arranged between the first electric motor and the input shaft to cut off or combine the power transmission between the engine and/or the first electric motor and the input shaft through the first clutch; the second electric motor is drivingly connected with the input shaft for driving the input shaft to rotate;

the first planetary gear mechanism comprises a first sun gear, a first planetary gear set, a first ring gear and a first planetary frame; the first sun gear is fixed on the input shaft so that the first sun gear rotates with the input shaft; the second planetary gear mechanism comprises a second sun gear, a second planetary gear set, a second ring gear and a second planetary frame; the second sun gear and the input shaft are independent of each other; wherein the second ring gear is fixedly connected to the first planetary frame, the first ring gear is fixedly connected to the second planetary frame, and the second planetary frame is used to transmit the power output by the power system;

the first brake is arranged between the first planetary frame and a casing of the power system, the second brake is arranged between the second sun gear and the casing of the power system, and the second clutch is arranged between the second sun gear and the input shaft.

Preferably, the second electric motor is connected to the input shaft through a third planetary gear mechanism, and the third planetary gear mechanism comprises a third sun gear, at least one set of planetary gear, a third ring gear, and a third planetary frame.

In the transmission and the power system of the present invention, the first ring gear or the first planetary frame is drivingly connected to the output gear of the transmission as an output member. When one of the two components of the first ring gear and the first planetary frame is drivingly connected to the output gear, another component is connected to the casing of the transmission through the brake; and the second clutch is configured such that when the brake is disengaged, the second clutch is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft. The transmission and the power system described above have a compact structure and a stable operation, to effectively improve the acceleration performance of the hybrid vehicle.

Further, the second electric motor of the present invention is connected with the input shaft through a planetary gear mechanism, which can provide a larger reduction ratio, effectively reduce the size of the electric motor or further improve the acceleration performance of the vehicle.

Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will better understand the above and other objectives, advantages and features of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The transmission and the power system100according to the embodiments of the present invention will be described below with reference toFIGS. 1 to 5.

Referring toFIGS. 1 to 4, a transmission for a hybrid vehicle is provided. In the casing of the transmission, there are provided with a first planetary gear mechanism4, an input shaft6, a first clutch7, a second clutch9, and a brake8. The first planetary gear mechanism4includes a first sun gear41, a first planetary gear set42, a first ring gear44, and a first planetary frame43. The first sun gear41is fixed on the input shaft6so that the first sun gear41rotates with the input shaft6. The first ring gear44or the first planetary frame43is drivingly connected with the output gear14of the transmission as an output member. The first planetary gear set42may include one set of planetary gear set or multiple sets of planetary gear set. When one of the two components of the first ring gear44and the first planetary frame43is drivingly connected with the output gear14, the other component is connected to the casing of the transmission through the brake8; the second clutch9is configured such that when the brake8is disengaged, the second clutch9is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft6.

The transmission can form a power system100with a first electric motor2, a second electric motor3, an engine1, etc. Specifically, the power system100includes the engine1, the first electric motor2, the second electric motor3, the first planetary gear mechanism4, the input shaft6, the first clutch7, the second clutch9, and the brake8. Preferably, the first electric motor2is an integrated starter motor (ISG motor), and the second electric motor3is a high-power drive motor (TM motor). The first clutch7, the second clutch9and the brake8are used to realize combination or cutting off of the transmission power of the power system100. The engine1, the first electric motor2and the second electric motor3may be arranged coaxially or non-coaxially.

The engine1is connected to the first electric motor2. The crankshaft of the engine1is connected with the rotor of the first electric motor2through a shock absorber. The first clutch7is arranged between the first electric motor2and the input shaft6to cut off or combine the power transmission between the first electric motor2and the input shaft6through the first clutch7. The first electric motor2has two functions, i.e., generating electricity and driving, and its structure and working principle have been described in detail in many related patents, and will not be repeated herein. By directly connecting the engine1with the first electric motor2, the first electric motor2can start the engine1, and the engine1can directly drive the first electric motor2to efficiently generate electricity. The electric energy of the first electric motor2is directly transmitted to the electric motor to drive, so as to reduce the conversion loss of electric energy to chemical energy.

The second electric motor3is drivingly connected with the input shaft6for driving the input shaft6to rotate. The second electric motor3may also be used as the first electric motor2to recover the braking energy of the vehicle. In order to improve gear transmission accuracy and improve NVH performance, the three prime movers (i.e., the engine1, the first electric motor2and the second electric motor3) are preferably arranged coaxially. Except for the differential12, the entire transmission has only two shafts. Further, by connecting the engine1with the second electric motor3through the first clutch7, when the second electric motor3is driving individually, the first clutch7is disengaged, so that the drag force of the engine1will not hinder the driving of the second electric motor3, thereby improving the efficiency of motor driving.

The first planetary gear mechanism4includes a first sun gear41, a first planetary gear set42, a first ring gear44, and a first planetary frame43. The first sun gear41is fixed on the input shaft6so that the first sun gear41rotates with the input shaft6. Specifically, the first sun gear41may be connected to the input shaft6through a spline connection. The first ring gear44or the first planetary frame43is drivingly connected with the output gear14of the power system100as an output member. When one of the two components of the first ring gear44and the first planetary frame43is drivingly connected with the output gear14, the other component is connected to the casing of the power system100through the brake8, and the engagement of the brake8can make the component stationary relative to the casing. The second clutch9is configured such that when the brake8is disengaged, the second clutch9is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft6.

In order to obtain a larger reduction ratio, the second electric motor3and the second planetary gear mechanism5can be connected in different ways. In a preferred embodiment, the second planetary gear mechanism5includes a second sun gear51, a second planetary gear set53, a second ring gear54, and a second planetary frame52. Either one of the three components of the second sun gear51, the second ring gear54and the second planetary frame52is fixed relative to the casing of the power system100, the rotor of the second electric motor3is drivingly connected to one of the remaining two unfixed components to provide power thereto, and another unfixed component is drivingly connected to the input shaft6to drive the input shaft6.

In a specific embodiment, the second sun gear51is fixed on the rotor of the second electric motor3and rotates with the rotor. The external gear of the second sun gear51meshes with the external gear of the second planetary gear set53, the second planetary frame52is fixed to the input shaft6, the external gear of the second planetary gear set53meshes with the internal gear of the second ring gear54, the second ring gear54is fixed to the casing, and the power of the second electric motor3is transmitted to the input shaft6through the second planetary frame52. This structure is suitable for a hybrid vehicle with a smaller power, smaller space and higher speed of the second electric motor3. If the second electric motor3has a large power and a large battery power in a plug-in hybrid vehicle, the second planetary gear mechanism5connected with the second electric motor3can be omitted, in order to save costs.

Of course, those skilled in the art may understand that the power system100of the hybrid vehicle may further include, for example, a shock absorber between the engine1and the first electric motor2, a differential12that achieves different speeds when the wheels turn, wheels for driving the vehicle, and driving axles for driving the wheels. The power system100may be directly connected to the above-mentioned elements in a conventional manner to realize the operation of the vehicle. These are not the focus of the technical solution of the present invention, and are well-known technologies to those skilled in the art, and therefore, are not repeated in this specification. The specific connection modes and working principle of each element of the power system100will be described in detail in the following.

In the transmission and the power system100of the present invention, the first ring gear44or the first planetary frame43is drivingly connected with the output gear14of the transmission as an output member. When one of the two components of the first ring gear44and the first planetary frame43is drivingly connected to the output gear14, the other component is connected to the casing of the transmission through the brake8; and the second clutch9is configured such that when the brake8is disengaged, the second clutch9is engaged to make the rotational speed of the output member equal to the rotational speed of the input shaft6. The transmission and the power system100described above have a compact structure and a stable operation, to effectively improve the acceleration performance of the hybrid vehicle.

Several embodiments of the present invention are specifically described below.

First Embodiment

FIG. 1is a schematic structural diagram of a power system100according to a first embodiment of the present invention. As shown inFIG. 1, when the first ring gear44is drivingly connected with the output gear14, the brake8is arranged between the first planetary frame43and the casing of the power system100, and the second clutch9is arranged between the first ring gear44and the input shaft6. When the brake8is engaged and the second clutch9is disengaged, the first gear of the power system100is realized; when the second clutch9is engaged and the brake8is disengaged, the second gear of the power system100is realized.

Specifically, the crankshaft of the engine1is connected with the rotor of the first electric motor2through a shock absorber. The rotor of the first electric motor2is connected to the input shaft6through the first clutch7. The first sun gear41of the first planetary gear mechanism4is fixed to the input shaft6. One side of the first planetary frame43is connected to the rolling drum of the brake8, and the first planetary frame43can be braked when the brake8works. When the second clutch9is engaged and the brake8is disengaged, the input shaft6and the first ring gear44are connected together, and the transmission ratio is 1. The first ring gear44is used to output power, and the output gear14fixed to the first ring gear44meshes with a driven gear15on the intermediate shaft11, so as to transmit the input power received by the first planetary gear mechanism4to the intermediate shaft11after changing the speed. The rotor of the second electric motor3is connected to the second sun gear51of the second planetary gear mechanism5. The second sun gear51and the input shaft6are independent of each other. The second ring gear54of the second planetary gear mechanism5is fixed to the casing of the transmission. The second planetary frame52is fixed to the input shaft6. The output member of the second planetary gear mechanism5is the second planetary frame52. The second planetary gear mechanism5changes the speed of the driving motor (i.e., the second electric motor3) and transmits it to the input shaft6, and then changes the input speed through the first planetary gear mechanism4and transmits it to the intermediate shaft11. The main reduction gear (i.e., the driving gear16) on the intermediate shaft11then drives the differential ring gear17on the differential12to transmit the driving power of the engine1and the electric motors to the driving axles, to finally drive the vehicle to move.

The present invention has three prime movers: the engine1, the first electric motor2and the second electric motor3. The first electric motor2may also be used as a generator to start the engine1. The second electric motor3may also be used as a motor to recover the braking energy of the vehicle. In order to improve gear transmission accuracy and improve NVH performance, the three prime movers may be arranged coaxially, so that in addition to the differential12, the entire transmission has only two shafts.

The power system100of this embodiment can implement the following common functions:

(1) Starting and Charging of the Engine1

Since the crankshaft of the engine1is directly connected to the rotor of the first electric motor2, the engine1can be started by the rotation of the first electric motor2. On the contrary, the operation of the engine1can drive the first electric motor2to charge the battery. Since the main function of the engine1is to generate electricity, and the speed of the first electric motor2is always the same as that of the engine1, the high-efficiency speed zones of the engine1and the first electric motor2should be designed to be consistent with each other.

(2) Driving Individually by the Engine1

When the engine1is operating, the first clutch7is engaged in order to transmit all or part of the power of the engine1to the input shaft6. If the brake8is engaged, the first sun gear41on the input shaft6drives the first ring gear44through the first planetary gear mechanism4. The first planetary gear mechanism4is a two-row planetary gear mechanism. The two-row planetary gear mechanism is adopted to ensure that the first sun gear41and the first ring gear44rotate in the same direction. The output gear14on the first ring gear44meshes with the driven gear15on the intermediate shaft11to transmit the power of the engine1to the intermediate shaft11. The driving gear16on the intermediate shaft11meshes with the differential ring gear17on the differential12to drive the driving axles, so as to finally drive the wheels to move. When driven by the engine1alone, a certain power of the engine1can be allocated to charge the battery through the first electric motor2. According to the operating conditions of the vehicle, the remaining power of the engine1can be allocated to the first electric motor2, thereby improving fuel economy. At full throttle, the torque of the first electric motor2can be controlled to zero, so that all the power of the engine1can be allocated to the driving axles to ensure the acceleration performance during the starting stage of the vehicle.

In this embodiment, when the speed of the vehicle is relatively high, the brake8is released and the second clutch9is engaged, so that the transmission ratio of the first planetary gear mechanism4drops from about 3 in the first gear to 1 in the second gear. If the overall transmission ratio of the first gear is 9, then the transmission ratio of the second gear becomes 3, which can be used for high-speed cruising or efficient power generation.

(3) Driving Individually by the Driving Motor

The second clutch9is disengaged, and the second electric motor3is started. In the second planetary gear mechanism5, the second ring gear54is fixed, and the rotor of the second electric motor3drives the second sun gear51to rotate. At this time, the output speed of the second planetary frame52drops to:
ns/nc=1+α1

wherein nsis the rotational speed of the second sun gear51, which is also the rotational speed of the rotor of the second electric motor3; ncis the output speed of the second planetary frame52; α1is the gear ratio of the second ring gear54to the second sun gear51.

Generally, the value of α1is set between 2 and 3. It can be seen from the above formula that the second planetary gear mechanism5reduces the speed of the second electric motor3by about 3 times, that is, the torque is increased by 3 times, thereby effectively reducing the size of the driving motor or improving the acceleration performance of the vehicle.

If different reduction ratios are required, the second planetary gear mechanism5may adopt different coupling modes. For example, the rotor of the second electric motor3is connected to the second ring gear54, the second sun gear51, or the second planetary frame52to output.

(4) Driving Simultaneously by the Engine1and the Driving Motor

The second electric motor3and the engine1are started simultaneously. The first clutch7is engaged, and the torque of the engine1is subtracted by the torque of the first electric motor2and then transmitted to the input shaft6through the first clutch7. The torque of the second electric motor3is also superimposed on the input shaft6after being amplified by the second planetary gear mechanism5. If the torque of the first electric motor2is controlled to be zero, the maximum input torque on the input shaft6is:
Tin=Te+α1*TP3

wherein Teis the output torque of the engine1; T p3is the output torque of the second electric motor3; T1is the input torque, which is equivalent to twice the output torque of the ordinary engine1, to ensure good acceleration performance of the vehicle.

When the engine1is driving, the first clutch7and the brake8are each engaged, so that the torque of the engine1is transmitted to the input shaft6through the first clutch7. The first sun gear41of the first planetary gear mechanism4is an input gear, the first ring gear44is an output gear, and the transmission ratio of the two-row planetary gear mechanism4is α2. α2is the gear ratio of the first ring gear44to the first sun gear41. Generally, the value of α2is set between 2 and 3.

When the speed is higher than the set value, the brake8is released and the second clutch9is engaged. The first sun gear41of the first planetary gear mechanism4rotates at the same speed as the first ring gear44, and the transmission ratio of the first planetary gear mechanism4drops to 1. It is assumed: a=Z15/Z14(wherein a represents the gear ratio of the driven gear15to the output gear14, Z represents the number of teeth of meshed gears); and b=Z17/Z16(wherein b represents the gear ratio of the differential ring gear17to the driving gear16, Z represents the number of teeth of meshed gears), then the product of the two is id, and id=a*b, which can be used to drive the vehicle to cruise at high speed or efficiently generate electricity. The total transmission ratio of the first gear is id*α2, which can be used to assist the electric motor to start or accelerate.

When the second electric motor3is driving, only the brake8needs to be engaged to achieve the first gear. The total transmission ratio of the first gear is id*α2*α1. When the speed of the vehicle is high, the brake8is released and the second clutch9is engaged, and the transmission ratio of the first planetary gear mechanism4is 1. The total transmission ratio of the second gear is id*α1.

(6) Vehicle Braking Energy Recovery

When the vehicle decelerates and brakes, the brake8is engaged, and the inertia of the vehicle is transmitted through the differential12and the intermediate shaft11to drag the first ring gear44, the first sun gear41, the input shaft6, the second planetary frame52, the second sun gear51and the rotor of the second electric motor3to generate electricity, thereby realizing the recovery of braking energy.

In summary, the power system100of this embodiment can at least realize several working modes as shown in the following table:

wherein IGE refers to the engine1, P1refers to the first electric motor2, P3refers to the second electric motor3, C1refers to the first clutch7, C2refers to the second clutch9, and B refers to the brake8.

Second Embodiment

FIG. 2is a schematic structural diagram of a power system100according to a second embodiment of the present invention. As shown inFIG. 2, when the first ring gear44is drivingly connected with the output gear14, the brake8is arranged between the first planetary frame43and the casing of the power system100, and the second clutch9is arranged between the first ring gear44and the first planetary frame43. When the brake8is engaged and the second clutch9is disengaged, the first gear of the power system100is realized; when the second clutch9is engaged and the brake8is disengaged, the second gear of the power system100is realized.

The working principle of the power system100in this embodiment is basically the same as the working principle of the power system100in the first embodiment, except that the position of the second clutch9is different, and the way to achieve the second gear is different, which will not be described in detail herein.

Third Embodiment

FIG. 3is a schematic structural diagram of a power system100according to a third embodiment of the present invention. As shown inFIG. 3, when the first planetary frame43is drivingly connected with the output gear14, the brake8is arranged between the first ring gear44and the casing of the power system100, and the second clutch9is arranged between the input shaft6and the first planetary frame43. When the brake8is engaged and the second clutch9is disengaged, the first gear of the power system100is realized; when the second clutch9is engaged and the brake8is disengaged, the second gear of the power system100is realized. In this embodiment, since the first planetary frame43is used to output power, the first planetary gear set42is a single planetary gear set.

Fourth Embodiment

FIG. 4is a schematic structural diagram of a power system100according to a fourth embodiment of the present invention. As shown inFIG. 4, when the first planetary frame43is drivingly connected with the output gear14, the brake8is arranged between the first ring gear44and the casing of the power system100, and the second clutch9is arranged between the input shaft6and the first ring gear44. When the brake8is engaged and the second clutch9is disengaged, the first gear of the power system100is realized; when the second clutch9is engaged and the brake8is disengaged, the second gear of the power system100is realized. In this embodiment, since the first planetary frame43is used to output power, the first planetary gear set42is a single planetary gear set.

Fifth Embodiment

FIG. 5is a schematic structural diagram of a power system100according to a fifth embodiment of the present invention. As shown inFIG. 5, a transmission for a hybrid vehicle includes a first planetary gear mechanism5, a second planetary gear mechanism4, an input shaft6, a second clutch8, a first brake9, and a second brake10. The first planetary gear mechanism5includes a first sun gear51, a first planetary gear set53, a first ring gear54, and a first planetary frame52. The first sun gear51is fixed on the input shaft6so that the first sun gear51rotates with the input shaft6. The second planetary gear mechanism4includes a second sun gear41, a second planetary gear set42, a second ring gear44, and a second planetary frame43. The second sun gear41and the input shaft6are independent of each other. The second ring gear44is fixedly connected to the first planetary frame52. The first ring gear54is fixedly connected to the second planetary frame43. The second planetary frame43is used to transmit the power output by the transmission. The first brake9is arranged between the first planetary frame52and the casing of the transmission, the second brake10is arranged between the second sun gear41and the casing of the transmission, and the second clutch8is arranged between the second sun gear41and the input shaft6.

Continuing to refer toFIG. 5, a power system for a hybrid vehicle is also provided. The power system100includes an engine1, a first electric motor2, a second electric motor3, a first planetary gear mechanism5, a second planetary gear mechanism4, an input shaft6, a first clutch7, a second clutch8, a first brake9, and a second brake10.

The engine1is connected to the first electric motor2. The first clutch7is arranged between the first electric motor2and the input shaft6to cut off or combine the power transmission between the engine1and/or the first electric motor2and the input shaft6through the first clutch7. The second electric motor3is drivingly connected with the input shaft6for driving the input shaft6to rotate. The first planetary gear mechanism5includes a first sun gear51, a first planetary gear set53, a first ring gear54, and a first planetary frame52. The first sun gear51is fixed on the input shaft6so that the first sun gear51rotates with the input shaft6. The second planetary gear mechanism4includes a second sun gear41, a second planetary gear set42, a second ring gear44, and a second planetary frame43. The second sun gear41and the input shaft6are independent of each other. The second ring gear44is fixedly connected to the first planetary frame52. The first ring gear54is fixedly connected to the second planetary frame43. The second planetary frame43is used to transmit the power output by the power system. The first brake9is arranged between the first planetary frame52and the casing of the power system. The second brake10is arranged between the second sun gear41and the casing of the power system. The second clutch8is arranged between the second sun gear41and the input shaft6.

The transmission or the power system with the above structure can realize three gear modes of the vehicle. The details are as follows. When the second brake10is engaged and the first brake9and the second clutch8are each disengaged, the second sun gear41is fixedly connected to the casing of the power system through the engagement of the second brake10, and the power is transmitted to the output gear by the second planetary frame43, such that the power system has a first transmission ratio, i.e., the first gear, which can be used to assist the electric motor to start or accelerate. When the first brake9is engaged and the second brake10and the second clutch8are each disengaged, the first planetary frame52and the second ring gear44are fixedly connected to the casing of the power system, and the power is transmitted to the output gear by the second planetary frame43, such that the power system has a second transmission ratio, i.e., the second gear. When the second clutch8is engaged and the first brake9and the second brake10are each disengaged, the second sun gear41rotates with the input shaft6at the same speed. At this time, the two sun gears51,41rotate together with the input shaft6, it is equivalent to locking the interior of the first planetary gear mechanism5, and the final transmission ratio of the power system is irrelevant to the first planetary gear mechanism5, to realize the third gear, which can be used to drive the vehicle to cruise at high speed or efficiently generate electricity. Regarding the operating modes of the power system, the principle is basically the same as that in the first embodiment, and will not be detailed herein.

Further, in a preferred embodiment, the second electric motor3is connected to the input shaft6through a third planetary gear mechanism, and the third planetary gear mechanism includes a third sun gear, at least one set of planetary gear, a third ring gear, and a third planetary frame. One of the three components of the third sun gear, the third ring gear and the third planetary frame is fixed relative to the casing of the power system, the rotor of the second electric motor3is drivingly connected to one of the unfixed components to provide power thereto, and another unfixed component is drivingly connected to the input shaft6to drive the input shaft6.

Further, the hybrid vehicle adopting the power system of the present invention may further be provided with, for example, a lithium battery energy storage system, a battery management system for managing the energy storage system, etc. In this way, the power of the second electric motor3and the first electric motor2can be directly supplied through the lithium battery energy storage system, and the first electric motor2can charge the lithium battery energy storage system through the engine1. These are not the focus of the present invention, and will not be repeated herein.

So far, those skilled in the art should realize that although several exemplary embodiments of the present invention have been illustrated and described in detail herein, many other variations or modifications can be made according to the content disclosed without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all these other variations or modifications.