Dual-motor dual-planetary-gear coaxial power split hybrid system and driving method thereof

Abstract

The present application relates to the technical field of automobile power system, in particular to a coaxial power split hybrid power system with double-motor and double-planetary gears and a driving method thereof. The hybrid power system adopts coaxial arrangement of double-motor and double-planetary gears, and two sun gears are directly connected. Since both of the sun gears belong to high-speed gears, the torque is small under the condition of transmitting equal power, so the size of the planetary gear can be reduced. The combination of planetary gear and parallel shaft can realize larger speed ratio, reduce the size of the motor and improve the power density. In the power split mode, the engine, generator and drive motor simultaneously affect the output power, and the generator and drive motor can intervene the vehicle torque (driving or generating) at any time, improving the dynamic response performance. Since only two planetary gears are used without clutch, the vehicle energy flow can be adjusted by adjusting the generator power flow, having the advantages of relatively simple arrangement and low cost.

Description

Technical Field

[0001] This invention relates to the field of automotive powertrain technology, specifically to a dual-motor dual-planetary gear coaxial power split hybrid power system and its driving method. Background Technology

[0002] Hybrid-specific transmissions, due to the addition of a drive motor, generator, and their control system components, have a larger overall structural size and more complex layout than traditional transmissions, making them difficult to integrate into a vehicle. Furthermore, current hybrid drive systems have excessively long transmission paths, complex control mechanisms, and require improved dynamic response performance, while also aiming to reduce costs.

[0003] In view of the above problems, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a dual-motor dual-planetary-gear coaxial power split hybrid power system and its driving method.

[0005] The technical solution adopted in this invention is as follows:

[0006] On the one hand, a dual-motor dual-planetary-gear coaxial power split hybrid power system is provided, characterized in that it includes an engine, a generator, a drive motor, a first planetary gear set, a second planetary gear set, an intermediate shaft, and a differential.

[0007] The sun gear of the first planetary gear set and the sun gear of the second planetary gear set are fixedly connected to the input shaft. The input shaft is arranged parallel to the intermediate shaft. An intermediate shaft driving gear and an intermediate shaft driven gear are fixed on the intermediate shaft.

[0008] The engine is driven by the ring gear of the first planetary gear set, the generator rotor is fixedly connected to the planet carrier of the first planetary gear set, the drive motor rotor is fixedly connected to the input shaft, the ring gear of the second planetary gear set is fixed on the gearbox housing, the planet carrier of the second planetary gear set is driven by the intermediate shaft gear, and the intermediate shaft drive gear is driven by the differential.

[0009] Furthermore, the engine is fixedly connected to the torsional damper, and the torsional damper is driven by the gear ring of the first planetary gear set.

[0010] Furthermore, the planet carrier of the second planetary set and the driven gear of the intermediate shaft form a parallel shaft gear pair.

[0011] On the other hand, a driving method for a dual-motor dual-planetary gear coaxial power split hybrid power system is provided:

[0012] This includes controlling the hybrid power system to operate in one of the following modes:

[0013] Pure electric drive mode: The engine is off, and power is output through the drive motor rotor;

[0014] Engine starting mode: The engine is started by cooperating with the generator and drive motor;

[0015] Power split mode: The engine is running, and the speed of the generator rotor is adjusted. The generator and engine work together to output power to drive the vehicle.

[0016] Parallel drive mode: In power split mode, the drive motor participates in the drive.

[0017] Furthermore, in the pure electric drive mode, the torque of the drive motor rotor is transmitted to the planet carrier of the second planetary gear set via the sun gear of the second planetary gear set, and then from the planet carrier of the second planetary gear set to the driven gear of the intermediate shaft, and then from the driving gear of the intermediate shaft to the large ring gear of the differential, and the power is output to the left and right drive half shafts of the vehicle via the differential.

[0018] Furthermore, in the pure electric drive mode, the energy source is the electrical energy stored in the vehicle's high-voltage battery, and the pure electric drive mode can enable the vehicle to start moving forward or in reverse.

[0019] Furthermore, the engine start-up mode includes the following two operating conditions:

[0020] Parking-start mode: The generator acts as the power source, driving the motor rotor in a locked state, thus locking the input shaft. Torque is transmitted from the generator rotor to the planet carrier of the first planetary gear set, driving the ring gear of the first planetary gear set to rotate, thereby starting the engine;

[0021] Vehicle start-up mode: The sun gear of the first planetary gear set is rotating in the forward direction, and the generator rotor is also rotating in the forward direction, thus keeping the engine crankshaft stationary. At this time, the speed of the generator rotor is increased to make the ring gear of the first planetary gear set rotate in the forward direction, thereby starting the engine.

[0022] Furthermore, in the power split mode, the engine torque is transmitted from the crankshaft to the ring gear of the first planetary gear set via the torsional damper; by adjusting the speed of the generator rotor, i.e., adjusting the speed of the planet carrier of the first planetary gear set, the speed of the sun gear of the first planetary gear set is adjusted, thereby adjusting the speed of the sun gear of the second planetary gear set, and then the torque is transmitted to the driven gear of the intermediate shaft through the planet carrier of the second planetary gear set, and then to the differential.

[0023] Furthermore, in the power split mode, the direction of rotation of the sun gear can be reversed by adjusting the speed of the generator rotor, thereby achieving the reversing function.

[0024] Furthermore, in the power split mode, the torque of the drive motor is superimposed on the sun gear of the second planetary gear set, thus entering a parallel drive mode. At this time, the engine split drive and the drive motor torque are superimposed.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The hybrid power system of this invention employs a coaxial arrangement of dual motors and dual planetary gear sets, with the two sun gears directly connected. Since both sun gears are high-speed gears, they deliver lower torque for the same power output, thus allowing for a smaller planetary gear set size. The combination of planetary gear sets and parallel shafts enables a larger speed ratio, reduces motor size, and increases power density. In power-split mode, the engine, generator, and drive motor simultaneously influence output power. Both the generator and drive motor can intervene in the vehicle's torque (driving or generating power) at any time, improving dynamic response performance. Because only two planetary gear sets are used, there is no clutch; the vehicle's energy flow can be adjusted by regulating the generator's power flow, offering advantages such as relatively simple layout and low cost. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a hybrid power system according to an embodiment of the present invention is shown. Detailed Implementation

[0029] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, unless otherwise explicitly specified.

[0032] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] like Figure 1 As shown, in a dual-motor, dual-planetary-gear coaxial power-split hybrid system, the engine ENG1 is bolted to the torsional damper 2, which is splined to the ring gear 3 of the first planetary gear set. The ring gear 3 of the first planetary gear set is supported by the first bearing 4. The sun gear 7 of the first planetary gear set and the sun gear 14 of the second planetary gear set are fixedly connected to the input shaft A. The sun gear 7 of the first planetary gear set is supported by the first sun gear bearing 5 and the second sun gear bearing 11, while the sun gear 14 of the second planetary gear set is supported by the second sun gear bearing 11 and the third sun gear bearing 15. The generator rotor 9 is fixedly connected to the planet carrier 6 of the first planetary gear set and is supported by the second bearing 8. The drive motor rotor 16 is fixedly connected to the input shaft A. The ring gear 13 of the second planetary gear set is fixed to the gearbox housing and is supported by the third sun gear bearing 15 and the drive motor rear bearing 17. The planet carrier 12 of the second planetary gear set is driven by the intermediate shaft driven gear 19 and is supported by the second bearing 10. Input shaft A is arranged parallel to intermediate shaft B. Intermediate shaft B has a drive gear 20 and a driven gear 19 fixed on it. Intermediate shaft B is supported by a front bearing 21 and a rear bearing 18. Differential 23 is supported by a front bearing 25 and a rear bearing 22. The drive gear 20 is connected to the large gear ring 24 of the differential.

[0034] In this embodiment, the hybrid power system employs a coaxial arrangement of two motors and two planetary gear sets. The sun gear 7 of the first planetary gear set is directly connected to the sun gear 14 of the second planetary gear set. The ring gear 13 of the second planetary gear set is fixed, and the planet carrier 12 of the second planetary gear set provides output power. This results in lower torque for the same power transmission, allowing for a smaller planetary gear set size. The planet carrier 12 of the second planetary gear set and the driven gear 19 on the intermediate shaft form a parallel shaft gear pair, enabling a larger speed ratio, reducing motor size, and increasing power density. Using only two planetary gear sets without a clutch offers advantages such as relatively simple layout and low cost.

[0035] The driving method of the dual-motor dual-planetary gear coaxial power split hybrid power system is as follows:

[0036] (1) Pure Electric Drive Mode: Engine 1 is off, and the drive motor rotor 16 outputs power. The torque of the drive motor rotor 16 is transmitted to the planet carrier 12 of the second planetary gear set via the sun gear 14. The ring gear 13 of the second planetary gear set is fixed on the transmission housing. Power is transmitted from the planet carrier 12 of the second planetary gear set to the driven gear 19 of the intermediate shaft, and then from the driving gear 20 of the intermediate shaft to the differential large ring gear 24. The power is then output to the left and right drive half shafts via the differential 23. In this condition, the energy source is the electrical energy stored in the vehicle's high-voltage battery. This mode can achieve forward start or reverse start.

[0037] (2) Engine starting modes: There are two operating conditions: parking start mode and driving start mode. In parking start mode, the generator EMG serves as the power source, and the drive motor rotor 16 is locked, thus locking the sun gear 14 of the second planetary gear set. Torque is transmitted from the generator rotor 9 to the planet carrier 6 of the first planetary gear set, driving the ring gear 3 of the first planetary gear set to rotate, thereby starting the engine. In driving start mode, the sun gear 7 of the first planetary gear set is rotating in the forward direction (the same direction as the engine crankshaft rotation is forward), and the generator rotor 9 is also rotating in the forward direction to keep the engine crankshaft stationary. At this time, controlling the increase of the generator rotor 9 speed can make the ring gear of the first planetary gear set rotate in the forward direction, thereby starting the engine. In other words, starting the engine requires the coordinated control of the generator and the drive motor.

[0038] (3) Power Split Mode: When engine 1 is running, torque is transmitted from the crankshaft through torsional damper 2 to the ring gear 3 of the first planetary gear set. The speed of the sun gear 7 of the first planetary gear set is adjusted by regulating the speed of generator rotor 9 (which is also the speed of planet carrier 6 of the first planetary gear set). The sun gear 7 of the first planetary gear set transmits torque to sun gear II 14, and then through the planet carrier 12 of the second planetary gear set to the driven gear 19 of the intermediate shaft. From the driving gear 20 of the intermediate shaft, the torque is transmitted to the differential large ring gear 24, and then through the differential 23 to the left and right drive half shafts. In this mode, the direction of rotation of the sun gear can also be reversed by adjusting the speed of generator rotor 9, thereby realizing the reversing function.

[0039] (4) Parallel drive mode: In the above power split mode, the drive motor EMD can participate in the drive, and its torque can be superimposed on the sun gear 14 of the second planetary gear set, thereby achieving the parallel drive mode. At this time, the engine split drive and the drive motor torque are superimposed.

[0040] In the power split mode, the hybrid power system of the present invention allows the engine, generator and drive motor to simultaneously affect the output power. Both the generator and drive motor can intervene in the vehicle torque (driving or generating) at any time. There is no clutch control element. The energy flow of the vehicle can be adjusted by adjusting the power flow of the generator. At the same time, the drive motor can intervene in driving or energy recovery at any time to improve the power response performance.

[0041] The above are merely preferred embodiments of the present invention and are illustrative rather than restrictive. The structure and connection methods of the components in the present invention can be varied, and any equivalent transformations and improvements made based on the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A driving method for a dual-motor, dual-planetary-gear coaxial power-split hybrid power system, characterized in that, The dual-motor dual-planetary-gear coaxial power split hybrid system includes an engine (1), a generator, a drive motor, a first planetary gear set, a second planetary gear set, an intermediate shaft (B), and a differential (23). The sun gear (7) of the first planetary gear set and the sun gear (14) of the second planetary gear set are fixedly connected to the input shaft (A). The input shaft (A) is parallel to the intermediate shaft. An intermediate shaft drive gear (20) and an intermediate shaft driven gear (19) are fixed on the intermediate shaft (B). The engine is driven by the ring gear (3) of the first planetary gear set. The generator rotor (9) is fixedly connected to the planet carrier (6) of the first planetary gear set. The drive motor rotor (16) is fixedly connected to the input shaft (A). The ring gear (13) of the second planetary gear set is fixed on the gearbox housing. The planet carrier (12) of the second planetary gear set is driven by the intermediate shaft driven gear (19). The intermediate shaft drive gear (20) is driven by the differential (23). The driving method includes controlling the hybrid power system to one of the following operating modes: Pure electric drive mode: The engine (1) is in a stopped state and outputs power through the drive motor rotor (16); In the pure electric drive mode, the torque of the drive motor rotor (16) is transmitted to the planet carrier (12) of the second planetary gear set through the sun gear (14) of the second planetary gear set, and then from the planet carrier (12) of the second planetary gear set to the driven gear (19) of the intermediate shaft, and then from the drive gear (20) of the intermediate shaft to the differential large gear ring (24), and the power is output to the left and right drive shafts of the vehicle through the differential (23); Engine starting mode: The engine is started by cooperating with the generator and the drive motor (1); Power split mode: When the engine (1) is in working condition, the speed of the generator rotor (9) is adjusted, and the generator and engine jointly output power to drive the vehicle. Parallel drive mode: In power split mode, the drive motor participates in the drive.

2. The driving method as described in claim 1, characterized in that, In the pure electric drive mode, the energy source is the electrical energy stored in the vehicle's high-voltage battery. The pure electric drive mode enables the vehicle to start moving forward or in reverse.

3. The driving method as described in claim 1, characterized in that, The engine start-up modes include the following two operating conditions: Parking start mode: The generator acts as a power source, driving the motor rotor (16) to be locked, thereby locking the input shaft (A); The torque is transmitted from the generator rotor (9) to the planet carrier (6) of the first planetary set, which drives the gear ring (3) of the first planetary set to rotate, thereby starting the engine; Driving start mode: The sun gear (7) of the first planetary gear set is in a forward rotation state, and the generator rotor (9) is also in a forward rotation state, so as to keep the engine crankshaft from rotating; at this time, the speed of the generator rotor (9) is increased, so that the gear ring (3) of the first planetary gear set rotates in the forward direction, thereby starting the engine.

4. The driving method as described in claim 1, characterized in that, In the power split mode, the torque of the engine (1) is transmitted from the crankshaft to the ring gear (3) of the first planetary gear set via the torsional damper (2); by adjusting the speed of the generator rotor (9), that is, adjusting the speed of the planet carrier (6) of the first planetary gear set, the speed of the sun gear (7) of the first planetary gear set is adjusted, thereby adjusting the speed of the sun gear (14) of the second planetary gear set, and then the torque is transmitted to the driven gear (19) of the intermediate shaft via the planet carrier (12) of the second planetary gear set, and then to the differential (23).

5. The driving method as described in claim 4, characterized in that, In the power split mode, the direction of rotation of the sun gear (7, 14) can be changed by adjusting the speed of the generator rotor (9), thereby realizing the reversing function.

6. The driving method as described in claim 5, characterized in that, In the power split mode, the torque of the drive motor is superimposed on the sun gear (14) of the second planetary gear set, thus being in parallel drive mode. At this time, the engine split drive and the torque of the drive motor are superimposed.

Images