Power-split hybrid drive system

Abstract

A power-split hybrid drive system comprising an internal combustion engine, an electric motor, and a power transmission mechanism that connects the internal combustion engine and the electric motor. The electric motor includes a first electric motor. The power transmission mechanism comprises: a planetary gear set that provides power coupling between the internal combustion engine and the first electric motor; a clutch connected between the planetary gear set and the first electric motor to enable and disengage power transmission between the planetary gear set and the first electric motor; a differential connected to the ring gear of the planetary gear set and capable of receiving the power transmitted through the ring gear to propel the vehicle forward; and a locking mechanism connected to the planetary gear set that can lock the ring gear of the planetary gear set.Since the ring gear of the planetary gearbox is equipped with a locking mechanism, the ring gear can be fully locked to the housing in park-start mode and park-charge mode, preventing the ring gear from transmitting knocking vibrations to the gears in the power transmission mechanism due to torque fluctuations, which would cause vehicle vibrations and jerking.

Description

Technical field

[0001] The present disclosure relates to the technical field of drive systems for hybrid vehicles and in particular a power-split hybrid drive system. General state of the art

[0002] A hybrid drive system is a system that possesses purely electric drive, purely internal combustion engine drive, and hybrid drive capabilities, with the switching between the different drive modes primarily achieved by the drive system itself. With the continuous development of numerous drive systems, power-split hybrid drive systems with high output power have become prevalent. Power-split drive systems are configured so that, through the series / parallel connection of the internal combustion engine and electric motor, the electric motor can deliver power simultaneously with the internal combustion engine, thus increasing the overall power output of the drive system.

[0003] In existing power-split hybrid drive systems that incorporate a planetary gear structure, the ring gear of the planetary gear is not equipped with a locking mechanism. Therefore, when the system is in park-start mode with a gear engaged (e.g., when the combustion engine is started by one of the electric motors with a gear engaged), another electric motor must provide a counter-torque to lock the ring gear of the planetary gear. However, because the transmission chain from the other electric motor to the ring gear of the planetary gear is long and can easily develop backlash, the counter-torque acting on the ring gear is often subject to fluctuations.This means that the ring gear of the planetary gearbox cannot be completely locked by a calibration strategy, which leads to strong vehicle vibrations and noises when starting in park mode with a gear engaged, and can even prevent the combustion engine from starting.

[0004] Furthermore, if the ring gear of the planetary gear set lacks a locking mechanism, it cannot be completely locked in Park-Start mode with a gear engaged or in Park-Charge mode with a gear engaged (e.g., when the combustion engine is charging the electric motor with a gear engaged) due to backlash in the transmission chain between the ring gear and the differential caused by torque fluctuations. This leads to the transmission of knocking vibrations to the gears in the power transmission mechanism, causing vibrations and knocking noises from the gears and thus resulting in significant vibrations and noise throughout the vehicle.

[0005] Therefore, a power-split hybrid drive system is needed that can solve the problems mentioned above. Disclosure of the invention

[0006] One purpose of the present disclosure is to reduce vibrations and anomalous noises during the operation of the power-split hybrid drive system.

[0007] The present disclosure provides a power-split hybrid drive system comprising an internal combustion engine, an electric motor and a power transmission mechanism that connects the internal combustion engine and the electric motor for propulsion.The electric motor comprises a first electric motor, and the power transmission mechanism comprises: a planetary gear set that implements a power coupling between the internal combustion engine and the first electric motor, the planetary gear set comprising a sun gear, planet gears, a ring gear, and a planet carrier, the planet gears being arranged on the planet carrier and meshing with the sun gear and the ring gear, respectively; a clutch connected between the planetary gear set and the first electric motor to enable and disengage the power transmission between the planetary gear set and the first electric motor; a differential drivenly connected to the ring gear of the planetary gear set and capable of receiving the power transmitted through the ring gear to propel the vehicle forward; and a locking mechanism connected to the planetary gear set and capable of locking the ring gear of the planetary gear set.

[0008] According to one embodiment of the present disclosure, the planet carrier is connected to the internal combustion engine via a first shaft and is rigidly connected to the first shaft. The sun gear is connected to the first electric motor via a second shaft and is rigidly connected to the second shaft.

[0009] According to one embodiment of the present disclosure, the coupling is connected to the sun gear and the ring gear of the planetary gear, and the locking mechanism is connected to the ring gear of the planetary gear.

[0010] According to one embodiment of the present disclosure, the coupling is configured for three positions: a first position in which no power is transmitted between the first electric motor and the planetary gear; a second position in which power is transmitted between the first electric motor and the sun gear of the planetary gear; and a third position in which power is transmitted between the first electric motor and the ring gear of the planetary gear, as well as between the first electric motor and the sun gear of the planetary gear. According to one embodiment of the present disclosure, the power-split hybrid drive system further comprises a synchronizer that is rigidly connected to the ring gear of the planetary gear. A first gear and a second gear are rotatably mounted on the second shaft.The synchronizer is arranged between the first and second gears and can be switched between them to achieve different gear ratios. According to one embodiment of the present disclosure, when the synchronizer engages with the first gear, the ring gear of the planetary gear is driven by a first drive train to the differential. When the synchronizer engages with the second gear, the ring gear of the planetary gear is driven by a second drive train, which differs from the first drive train.

[0011] According to one embodiment of the present disclosure, the first shaft and the second shaft are arranged coaxially. The first shaft is connected to the internal combustion engine, and the second shaft is connected to the first electric motor.

[0012] According to one embodiment of the present disclosure, the electric motor further comprises a second electric motor which is connected to the differential in a drive manner, so that when the internal combustion engine is not running, the power of the second electric motor is transferred to the differential in order to move the vehicle at low speed.

[0013] By incorporating a locking mechanism on the ring gear of the planetary gear set, as described in the power-split hybrid drive system of this disclosure, the ring gear can be fully locked to the housing during power transmission between the internal combustion engine and the first electric motor in park-start and park-charge modes. This prevents the ring gear from transmitting knocking vibrations to the gears in the power transmission mechanism due to torque fluctuations, which would otherwise lead to vehicle vibrations and jerking. Additionally, by incorporating the locking mechanism on the ring gear of the planetary gear set, the system speed ratio of the power-split hybrid drive system can be expanded in park-start and park-charge modes, thereby improving the coordination of the power output of the internal combustion engine and the first electric motor and increasing the system's operational efficiency. Description of the enclosed figures

[0014] The features, advantages and technical effects of exemplary embodiments of the present application are described below with reference to the attached drawings. Fig. Figure 1 shows a schematic structural representation of a power-split hybrid drive system according to an embodiment of the present disclosure. Designs

[0015] The embodiments of the present application are described in detail below in conjunction with the accompanying drawings and embodiments. The detailed description of the following embodiments and the accompanying drawings serve as an exemplary illustration of the principle of the present application, but cannot be used to limit the scope of the present application; that is, the present application is not limited to the described embodiments. In the description of the present application, terms such as "top", "bottom", "inside", "outside", etc.Unless otherwise stated, the terms used in this application refer only to directional or positional relationships to facilitate and simplify the description of the present application and do not indicate or imply that the device or element in question must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be understood as limiting the present application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and are not to be understood as indicating or suggesting any relative importance. The orientation terms used in the following description represent the directions shown in the figures and do not constitute a definition of the specific construction of the present application.

[0016] It should be noted that, in the description of this application, the terms "assembly," "connection," and "connection" are to be understood in a broad sense unless explicitly specified and defined otherwise. This may include, for example, a permanent connection, a detachable connection, or a one-piece connection. It may also refer to a direct connection or an indirect connection via an intermediate medium. For the person skilled in the art, the specific meanings of the aforementioned terms within the meaning of this application are to be understood according to specific situations.

[0017] The power-split hybrid drive system according to the present disclosure can be used in vehicles so that the vehicle can switch between the following driving modes: Park-Start mode, Park-Charge mode, all-electric driving mode, hybrid driving mode, and power-split driving mode. In Park-Start mode, the vehicle is stationary and the combustion engine is started by the electric motor. In Park-Charge mode, the vehicle is stationary and the combustion engine charges the electric motor. At relatively low driving speeds, the vehicle can be operated in all-electric mode or in power-split driving mode. At medium to high speeds, the vehicle can be operated in all-electric, parallel hybrid, or power-split driving mode to achieve good fuel efficiency at medium to high speeds.The operating modes of the power-split hybrid drive system according to an embodiment of the present disclosure are described below with reference to . Fig. 1 described.

[0018] Fig. Figure 1 shows a schematic structural representation of a power-split hybrid drive system according to an embodiment of the present disclosure. As in Fig. As shown in Figure 1, the power-split hybrid drive system according to an embodiment of the present disclosure comprises an internal combustion engine 2, an electric motor, and a power transmission mechanism 1 that connects the internal combustion engine 2 and the electric motor in a drive-related manner. The electric motor can, for example, comprise a first electric motor 3 and a second electric motor 4. The term "drive-related" here means that two components are connected to each other via one or more gear sets with a specific transmission ratio in order to achieve power coupling. The power transmission mechanism 1 mainly comprises: a planetary gear set 10, a clutch 20, a synchronizer 30, a locking mechanism 40, and a differential 50, etc.

[0019] The planetary gear set 10 is connected between the internal combustion engine 2 and the first electric motor 3 and comprises a sun gear 11, several planet gears 12, a planet carrier 13, and a ring gear 14. The planet carrier 13 is connected to the internal combustion engine 2 via a first shaft 71, for example, via a torque-limiting vibration damper. The planet carrier 13 is rigidly connected to the first shaft 71. The first shaft 71 is connected to the internal combustion engine 2 and can serve as both the input and output shaft of the internal combustion engine 2. The sun gear 11 is located radially within the several planet gears 12 and can mesh with them. The sun gear 11 is connected to the first electric motor 3 via a second shaft 72. The sun gear 11 is rigidly mounted on the second shaft 72.The second shaft 72, for example, is connected to the first electric motor 3 and can serve as both the input and output shaft of the first electric motor 3. The multiple planet gears 12 are evenly distributed on the planet carrier 13 and can each mesh with the sun gear 11 and the ring gear 14. Thus, the planetary gear set 10 can be driven by both the internal combustion engine 2 and the first electric motor 3, thereby enabling power transmission between them. On the one hand, the charging process of the first electric motor 3 is carried out by the internal combustion engine 2; on the other hand, the starting process of the internal combustion engine 2 is carried out by the first electric motor 3.

[0020] The coupling 20 is arranged between the planetary gear 10 and the first electric motor 3 to enable and interrupt the power transmission between the planetary gear 10 and the first electric motor 3. The coupling 20 comprises a rotating element fixedly mounted on the second shaft 72, a connecting element fixedly connected to the ring gear 14 of the planetary gear 10, and a locking element fixedly attached to a housing (not shown). The rotating element can rotate with the rotation of the second shaft 72. The connecting element is rotationally fixed to the ring gear 14 of the planetary gear 10. The rotating element can be switched and coupled with the locking element and the connecting element, so that the coupling assumes three positions. In the first position (i.e., the right-hand position in Fig. 1) The rotating element is coupled to the locking element, so that the clutch 20 is in a locked state and the power transmission between the first electric motor 3 and the planetary gear 10 is interrupted. In the second position (i.e., the middle position in Fig. 1) The rotating element is neither coupled to the locking element nor to the connecting element, and the rotating element can rotate synchronously with the second shaft 72. Therefore, the coupling 20 can transmit power between the first electric motor 3 and the sun gear 11 of the planetary gear 10. In the third position (i.e., the left position in Fig. 1) The rotating element is coupled to the connecting element, so that the rotating element is coupled to both the ring gear 14 of the planetary gear 10 and the sun gear 11 of the planetary gear. Therefore, the coupling 20 can transmit power between the first electric motor 3 and the sun gear 11 of the planetary gear 10, as well as between the first electric motor 3 and the ring gear 14 of the planetary gear 10. In this case, the coupling 20 / sun gear 11 and the ring gear 14 have the same rotational speed, so that the sun gear 11 and the ring gear 14 rotate synchronously.

[0021] The synchronizer 30 is arranged between a first gear 61 and a second gear 62, which are rotatably mounted on the second shaft 72, and can be rigidly connected to the ring gear 14 of the planetary gear set 10. The synchronizer 30 can be engaged with the first gear 61 or the second gear 62 to create two gears and thus influence the output speed of the differential 50. The gear changes via the first gear 61 and the second gear 62 through the synchronizer 30 make the structure of the entire drive system simple and practical, and allow for a variety of drive modes. Of course, the synchronizer 30 can also be disengaged from both the first gear 61 and the second gear 62. In this case, the power from the internal combustion engine 2 and the power from the first electric motor 3 are not transmitted to the differential 50.

[0022] The first gear 61 can mesh with a third gear 63, which in turn meshes with a fourth gear 64. The fourth gear 64 is fixed on a fourth shaft 74 and can mesh with a fifth gear 65. The fifth gear 65 is fixed on a fifth shaft 75, which is connected, for example, to the second electric motor 4 and can serve as both its input and output shafts. Thus, when the synchronizer 30 is engaged with the first gear 61, the power from the ring gear 14 of the planetary gear set 10 can be transmitted via the synchronizer 30, the first gear 61, the third gear 63, the fourth gear 64, the fifth gear 65, and the fifth shaft 75 to the second electric motor 4.

[0023] Simultaneously, a sixth gear 66 is also fixedly mounted on the fourth shaft 74, which, together with the fourth gear 64, can rotate at the same speed as the fourth shaft 74. The sixth gear 66 can mesh with a seventh gear 67, which is fixedly connected to the housing of the differential 50. Thus, when the synchronizer 30 is engaged with the first gear 61, the ring gear 14 of the planetary gear 10 can also be driven by the differential 50 via the synchronizer 30, the first gear 61, the third gear 63, the fourth gear 64, the fourth shaft 74, the sixth gear 66, and the seventh gear 67. The first gear 61, the third gear 63, the fourth gear 64, the sixth gear 66, and the seventh gear 67 together form the first drive train of the present disclosure.The power from the ring gear 14 of the planetary gear 10 can be transmitted via the first drive train to the differential 50, so that the differential 50 controls the power transmitted to the wheels to propel the vehicle.

[0024] The second gear 62 can mesh with an eighth gear 68, which is fixedly mounted on a third shaft 73. A ninth gear 69 is also fixedly mounted on the third shaft 73, so that the eighth gear 68 and the ninth gear 69 can rotate at the same speed as the third shaft 73. The ninth gear 69 can mesh with the seventh gear 67, which is fixedly connected to the housing of the differential 50. Thus, when the synchronizer 30 is engaged with the second gear 62, the ring gear 14 of the planetary gear 10 can be driven by the differential 50 via the synchronizer 30, the second gear 62, the eighth gear 68, the ninth gear 69, and the seventh gear 67. The second gear 62, the eighth gear 68, the ninth gear 69 and the seventh gear 67 form the second drive train of the present disclosure.The force from the ring gear 14 of the planetary gear 10 can be transmitted via the second drive train to the differential 50, whereby the differential controls the force transmitted to the wheels and thus regulates the driving condition of the vehicle.

[0025] Additionally, when the synchronizer 30 is engaged with the second gear 62, the ring gear 14 of the planetary gear 10 can also be driven further via the synchronizer 30, the second gear 62, the eighth gear 68, the ninth gear 69, the seventh gear 67, the sixth gear 66, the fourth gear 64, the fifth gear 65 and the fifth shaft 75 to the second electric motor 4.

[0026] According to one embodiment of the present disclosure, the first shaft 71 and the second shaft 72 are arranged coaxially, and the first shaft 71, the second shaft 72, the third shaft 73, the fourth shaft 74, and the fifth shaft 75 are parallel to each other. Therefore, the overall structure of the power transmission mechanism 1 of the embodiment of the present disclosure is more compact.

[0027] According to one embodiment of the present disclosure, the first electric motor 3 and the second electric motor 4 are electrically connected. Thus, when the internal combustion engine drives the first electric motor 3 via the planetary gear 10 to generate electricity, the electrical energy generated by the first electric motor 3 directly supplies the second electric motor 4. Excess electrical energy is used directly to charge the traction battery. This design enables the recovery of electrical energy during vehicle propulsion, which reduces the energy consumption of this drive system.

[0028] The locking mechanism 40 is located between the planetary gear set 10 and the clutch 20 and can be connected to both the ring gear 14 of the planetary gear set 10 and the housing of the power-split hybrid drive system. When the locking mechanism 40 is in the braked position, it locks the ring gear 14 of the planetary gear set 10 to the housing of the power transmission mechanism 1, preventing the ring gear 14 from rotating and thus preventing it from transmitting power to the differential 50. Power is then transmitted only between the internal combustion engine 2 and the first electric motor 3, enabling the park-start and park-charge modes of the drive system. The park-start mode is the mode in which the internal combustion engine 2 is driven by an electric motor (e.g., the first electric motor 3), while the park-charge mode is the mode in which the internal combustion engine 2 charges the first electric motor 3.According to the embodiment of the present disclosure, the locking mechanism 40 can completely lock the ring gear 14 in both park-start mode and park-charge mode, which can significantly reduce noise and vibration under these two operating conditions and improve the NVH (noise / vibration / sound roughness) performance of the entire vehicle.

[0029] In Park-Start mode, clutch 20 is in the second position (i.e., the middle position in Fig. 1) The first electric motor 3 drives the second shaft 72 for synchronous rotation. The ring gear 14 of the planetary gear 10 is blocked by the locking mechanism 40 and does not transmit any power to the differential 50. Therefore, power is transmitted only from the first electric motor 3 via the planetary gear 10 to the internal combustion engine 2 to start the internal combustion engine 2. Depending on whether the synchronizer 30 is engaged with the first gear 61 and the second gear 62, the park-start mode can be further subdivided into a park-neutral-start mode and a park-start mode with a gear engaged. In the park-neutral-start mode, the synchronizer 30 is not engaged with either the first gear 61 or the second gear 62. The clutch 20 is in the second position (i.e., the middle position in the gear). Fig. 1) The first electric motor 3 drives the second shaft 72 to rotate. Since the locking mechanism 40 completely locks the ring gear 14 and transmits no power to the differential 50, the power of the first electric motor 3 can be successively transmitted via the second shaft 72, the clutch 20, the sun gear 11, the planet carrier 13, and the first shaft 71 to the internal combustion engine 2 to start the internal combustion engine 2. This ensures that the speed ratio of the internal combustion engine 2 to the speed of the first electric motor 3 is less than 1, thus achieving a speed reduction and torque increase function. Therefore, the function of the first electric motor 3 and the internal combustion engine 2 is optimally coordinated. In Park-Start mode with a gear engaged, the synchronizer 30 can be engaged with either the first gear 61 or the second gear 62. The clutch 20 is also in the second position.The first electric motor 3 drives the second shaft 72 to rotate. Since the locking mechanism 40 completely locks the ring gear 14 and transmits no power to the differential 50, the power of the first electric motor 3 can be successively transmitted via the second shaft 72, the clutch 20, the sun gear 11, the planet carrier 13, and the first shaft 71 to the internal combustion engine 2 to start the internal combustion engine 2. This results in a speed ratio of the internal combustion engine 2 to the speed of the first electric motor 3 that is less than 1, thus achieving a speed reduction and torque increase function. Therefore, the function of the first electric motor 3 and the internal combustion engine 2 is optimally matched. Regardless of whether the vehicle is in park-start mode or park-start mode with a gear engaged, a system gear ratio of less than 1 can be achieved as long as the locking mechanism 40 completely locks the ring gear 14.Compared to a configuration without locking mechanism 40, which can only achieve a system gear ratio of 1:1 in park-start mode, this allows for more reliable optimization of the power matching between the first electric motor 3 and the combustion engine 2, thereby improving the operating efficiency of the power-split hybrid drive system. However, to improve the responsiveness and starting efficiency of the entire vehicle, the gear-engaged start mode is generally preferred in most cases, allowing the vehicle to switch to parallel driving mode after the combustion engine 2 has started by quickly releasing locking mechanism 40.

[0030] In park-charge mode, clutch 20 is in the second position (i.e., the middle position in Fig. 1) The first electric motor 3 drives the second shaft 72 to synchronous rotation. The ring gear 14 of the planetary gear set 10 is blocked by the locking mechanism 40 and transmits no power. Therefore, power is transmitted only from the internal combustion engine 2 to the first electric motor 3 to charge it. Depending on whether the synchronizer 30 is engaged with the first gear 61 and the second gear 62, the park-charge mode includes a park-neutral charge mode and a park-charge mode with a gear engaged. In park-neutral charge, the synchronizer 30 is not engaged with either the first gear 61 or the second gear 62. The clutch 20 is in the second position (i.e., the middle position in the gear). Fig. 1) The first electric motor 3 drives the second shaft 72 for synchronous rotation. Since the locking mechanism 40 completely locks the ring gear 14 and transmits no power, the power of the internal combustion engine 2 can only be transmitted sequentially via the first shaft 71, the planet carrier 13, the sun gear 11, the clutch 20, and the second shaft 72 to the first electric motor 3 to charge it. This ensures that the speed ratio of the internal combustion engine 2 to the speed of the first electric motor 3 is less than 1, thus achieving a speed-increasing and torque-reducing function. Therefore, the function of the first electric motor 3 and the internal combustion engine 2 is optimally matched. In park-charge mode with a gear engaged, the synchronizer 30 can be engaged with either the first gear 61 or the second gear 62. The clutch 20 is also in the second position (i.e., the middle position in the gear). Fig.1) Since the locking mechanism 40 completely locks the ring gear 14, the power of the internal combustion engine 2 can be successively transmitted via the first shaft 71, the planet carrier 13, the sun gear 11, the clutch 20, and the second shaft 72 to the first electric motor 3 to charge it. This ensures that the speed ratio of the internal combustion engine 2 to the speed of the first electric motor 3 is also less than 1, thus achieving a speed-increasing and torque-reducing function. Therefore, the function of the first electric motor 3 and the internal combustion engine 2 is optimally matched. Regardless of whether the vehicle is in park-idle-charging mode or park-charging mode with a gear engaged, a system gear ratio of less than 1 can be achieved as long as the locking mechanism 40 completely locks the ring gear 14.Compared to a configuration without locking mechanism 40, which can only achieve a system gear ratio of 1:1 in park-charge mode, this allows for more reliable optimization of the power matching between the first electric motor 3 and the combustion engine 2, thereby improving the operating efficiency of the power-split hybrid drive system. However, charging efficiency is typically high in park-charge mode with a gear engaged, and only the locking mechanism 40 needs to be released to quickly switch to parallel driving mode, resulting in a faster response to power demand. Therefore, park-charge mode with a gear engaged is preferred.

[0031] It is evident that, according to the embodiments of the present disclosure, the system transmission ratio can be increased in both park-start mode (including park-idle-start mode and park-start mode with a gear engaged) and park-charge mode (including park-idle-charge mode and park-charge mode with a gear engaged) by completely locking the ring gear 14 using the locking mechanism 40. Compared to a configuration without the locking mechanism 40, which can only achieve a system transmission ratio of 1:1, two additional operating modes can be added to the power-split hybrid drive system, and the power matching between the first electric motor 3 and the internal combustion engine 2 can be optimized more reliably, thereby improving the operating efficiency of the power-split hybrid drive system.

[0032] Furthermore, according to the embodiments described in this disclosure, since the ring gear 14 of the planetary gear set 10 is equipped with a locking mechanism 40, noise and vibration in park-start mode (including park-neutral-start mode and park-start mode with a gear engaged) and in park-charge mode (including park-neutral-charge mode and park-charge mode with a gear engaged) can be significantly reduced. This prevents the ring gear 14 from transmitting knocking vibrations to the gear sets in the power transmission mechanism due to torque fluctuations, which would cause vehicle vibrations and jerking, and thus improves the NVH (noise, vibration, and harshness) performance of the entire vehicle. When the locking mechanism 40 is in the disengaged state, it does not lock the ring gear 14 of the planetary gear set 10.As a result, the power-split hybrid drive system, according to the embodiments described in this disclosure, achieves the following driving modes. 1. When the locking mechanism 40 is in the disengaged state and the clutch 20 is in the first position, the rotating element of the clutch 20 is coupled to the locking element, regardless of whether the synchronizer 30 is engaged with the first gear 61 and the second gear 62. The clutch 20 is in the locked state, so the second shaft 72 does not rotate. Therefore, there is no power transmission between the first electric motor 3 and the planetary gear 10. Only the internal combustion engine 2 delivers power to the differential 50 via the planetary gear 10. At this point, the power output of the internal combustion engine 2 can, of course, be controlled via the second electric motor 4, depending on the vehicle's driving requirements, in order to reduce the energy consumption of the power-split hybrid drive system of this disclosure. 2. When the locking mechanism 40 is in the disengaged state, the clutch 20 is in the second position, and the synchronizer 30 is engaged with either the first gear 61 or the second gear 62, the rotating element of the clutch 20 is neither coupled to the locking element nor to the connecting element, and the first electric motor 3 can drive the second shaft 72. Therefore, both the internal combustion engine 2 and the first electric motor 3 can supply power. At this point, the parallel hybrid mode of the power-split hybrid drive system 1 can be realized, allowing the internal combustion engine 2, the first electric motor 3, and the second electric motor 4 to operate in parallel hybrid mode with energy recuperation.Furthermore, different gear ratios can be achieved by selectively engaging the synchronizer 30 with the first gear 61 for drive connection to the differential 50 via the aforementioned first drive train and with the second gear 62 for drive connection to the differential 50 via the aforementioned second drive train, i.e., ECVT gear 1 and ECVT gear 2. This results in the power-split hybrid drive system of the present disclosure exhibiting lower energy consumption, faster power response, and higher efficiency. When the locking mechanism 40 is in the disengaged state, the clutch 20 is in the second position, and the synchronizer 30 is not engaged with either the first gear 61 or the second gear 62, the planetary gear set 10 cannot deliver any power at that time.No power is transferred from the combustion engine 2 and the first electric motor 3 to the differential 50. 3. When the locking mechanism 40 is in the disengaged state and the clutch 20 is in the third position, the rotating element of the clutch 20 is coupled to the connecting element. Therefore, the rotating element, together with the second shaft 72, can be coupled to both the ring gear 14 and the sun gear 11 of the planetary gear 10, so that the second shaft 72, the sun gear 11, and the ring gear 14 rotate at the same speed. At this point, the planet carrier 13 also rotates at the same speed as the sun gear 11 and the ring gear 14, respectively, thus achieving a system gear ratio of 1:1. At this point, the internal combustion engine 2 is generally idling and can drive the first electric motor 3.

[0033] Therefore, according to the present disclosure, by additionally providing a locking mechanism 40, which implements the function of locking the ring gear 14 of the planetary gear 10, the locking mechanism 40 and the clutch 20 can cooperate with each other to extend the operating modes of the drive system, so that the internal combustion engine 2 and the electric motor can selectively deliver power according to the driving requirements of the vehicle in order to improve the dynamics of the entire vehicle; or the internal combustion engine 2 can charge the first electric motor 3 and / or the second electric motor 4 to recover energy, thereby significantly reducing the energy consumption of the entire drive system structure.

[0034] Since the ring gear 14 of the planetary gear set 10 is equipped with a locking mechanism, the synchronizer 30 can engage with the first gear 61 or the second gear 62 in park-start mode. This allows the vehicle to start in gear while simultaneously ensuring reliable starting of the combustion engine 2, thus improving the vehicle's responsiveness. Furthermore, if the torque required for vehicle propulsion is high, the locking mechanism 40 can switch from the braked state to the disengaged state, enabling the drive system to quickly switch to parallel driving mode without requiring a more powerful first electric motor 3. This can reduce system costs and accelerate the system's responsiveness.

[0035] Furthermore, the power-split hybrid drive system according to the embodiments of the present disclosure can also implement a purely electric mode. In this mode, the internal combustion engine 2 is not started, while the second electric motor 4 is in drive mode. The power of the second electric motor 4 can be transmitted to the differential 50 via the fifth shaft 75, the fifth gear 65, the fourth gear 64, the fourth shaft 74, the sixth gear 66, and the seventh gear 67, so that the differential 50 can control the power transmitted to the wheels to move the vehicle.

[0036] Although the above embodiments show two electric motors 3 and 4, the present disclosure is not limited thereto. For example, depending on the actual application requirements, the power-split hybrid drive system of the present disclosure may include only the first electric motor 3 and not the second electric motor 4.

[0037] Although the present application has been described with reference to preferred embodiments, various improvements can be made and components thereof replaced by equivalents without altering the scope of protection of the present application. In particular, the individual technical features mentioned in the individual embodiments can be combined in any way, provided there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions that fall within the scope of protection of the claims.

Claims

[1] Power-split hybrid drive system comprising an internal combustion engine, an electric motor and a power transmission mechanism connecting the internal combustion engine and the electric motor for propulsion, wherein the electric motor comprises a first electric motor, characterized by , that the power transmission mechanism includes: a planetary gear unit that provides power coupling between the internal combustion engine and the first electric motor, wherein the planetary gear unit comprises a sun gear, planet gears, a ring gear and a planet carrier, wherein the planet gears are arranged on the planet carrier and each mesh with the sun gear and the ring gear; a coupling connected between the planetary gear and the first electric motor to enable and interrupt the power transmission between the planetary gear and the first electric motor; a differential that is driven by the ring gear of the planetary gear and can absorb the force transmitted via the ring gear to move the vehicle forward; and a locking mechanism that is connected to the planetary gear and can lock the ring gear of the planetary gear. [2] Power-split hybrid drive system according to claim 1, wherein the planet carrier is connected to the internal combustion engine via a first shaft and is fixedly connected to the first shaft, and the sun gear is connected to the first electric motor via a second shaft and is fixedly connected to the second shaft. [3] Power-split hybrid drive system according to claim 1, wherein the clutch is connected to the sun gear and the ring gear of the planetary gear and the locking mechanism is connected to the ring gear of the planetary gear. [4] Power-split hybrid drive system according to claim 3, wherein the clutch is configured for three positions: a first position in which no force is transmitted between the first electric motor and the planetary gear; a second position in which force is transmitted between the first electric motor and the sun gear of the planetary gear; and a third position in which force is transmitted between the first electric motor and the ring gear of the planetary gear as well as between the first electric motor and the sun gear of the planetary gear. [5] Power-split hybrid drive system according to claim 2, further comprising a synchronizer fixedly connected to the ring gear of the planetary gear set, wherein a first gear and a second gear are rotatably mounted on the second shaft, and the synchronizer is arranged between the first and the second gear set and is switchable to connect to the first and the second gear set to realize different gears. [6] Power-split hybrid drive system according to claim 5, wherein, when the synchronizer is engaged with the first gear, the ring gear of the planetary gear is driven by a first drive train to the differential, and when the synchronizer is engaged with the second gear, the ring gear of the planetary gear is driven by a second drive train which is different from the first drive train. [7] Power-split hybrid drive system according to claim 2, wherein the first shaft and the second shaft are arranged coaxially, the first shaft is connected to the internal combustion engine and the second shaft is connected to the first electric motor. [8] Power-split hybrid drive system according to any one of claims 1 to 7, wherein the electric motor further comprises a second electric motor which is connected to the differential in a drive manner, so that when the internal combustion engine is not started, the power of the second electric motor is transferred to the differential to move the vehicle at low speed.

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