Plug-in hybrid power chain system

Abstract

The invention relates to the technical field of new energy automobile power systems, in particular to a plug-in hybrid power chain system which comprises a front axle power unit, an engine is connected with a CVT gearbox, and an output shaft of the engine is integrated with a P1 generator; the rear axle power unit comprises a first driving motor and a second driving motor which are connected with the rear axle through mechanical couplers; the control module triggers a working mode based on the battery power; the power pressure limiting valve controls the output power of the engine and the input current of the rear axle motor; by setting the control strategy that the battery electric quantity is higher than 40%, the pure electric mode or the hybrid mode can be freely selected, the light hybrid mode is forcibly entered when the electric quantity is smaller than or equal to 40%, and the heavy hybrid mode is switched when the electric quantity is smaller than or equal to 30%, the anxiety of a user for insufficient pure electric endurance is thoroughly eliminated, and it is ensured that the vehicle can stably run in any electric quantity state; and the possible power interruption stall risk of the existing plug-in hybrid system under extreme conditions is completely avoided.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle powertrain technology, and in particular to a plug-in hybrid powertrain system. Background Technology

[0002] Plug-in hybrid electric vehicles (PHEVs) have become increasingly popular in the market in recent years as a transitional solution between traditional gasoline vehicles and pure electric vehicles. These vehicles typically have multiple operating modes, including pure electric drive, hybrid drive, and gasoline drive. However, in actual use, users still face problems such as range anxiety, imperfect hybrid mode switching logic, and the risk of power interruption under extreme conditions. In particular, when the battery is low, the system needs to rely on the coordinated control of the engine and motor to maintain driving. If the energy management strategy is flawed, it can easily lead to a decline in vehicle dynamic performance or even driving safety hazards. Therefore, there is an urgent need to develop a plug-in hybrid powertrain system that can eliminate user anxiety and achieve smooth driving under all conditions.

[0003] Current mainstream plug-in hybrid systems have low power generation but high drive motor power, and the engine cannot provide full-speed, all-time direct drive. Therefore, when the vehicle battery is severely depleted and direct drive is required, existing mainstream plug-in hybrid vehicles have the following defects in direct drive mode. For example, the hybrid-specific transmission has 1 or 2 gears, or even 3 or 4 gears. The engine cannot provide full-speed, all-time direct drive. It can only provide direct drive within a certain speed range or multiple speed ranges. When the vehicle cannot reach the direct drive speed, in extreme road conditions, the generator's power generation efficiency may not keep up with the usage efficiency. At this time, when the power battery stops supplying power for self-protection, the vehicle will experience a sudden deceleration and stall.

[0004] Therefore, in response to the problems mentioned above, this invention proposes a plug-in hybrid powertrain system. This system uses a CVT transmission, which can ensure that the engine can maintain direct drive mode at all times and speeds in the low-electricity hybrid mode, and achieves higher efficiency in energy recovery. Summary of the Invention

[0005] To overcome the problem of uneven power switching in existing plug-in hybrid systems when the battery is depleted, this invention proposes a plug-in hybrid powertrain system.

[0006] The technical solution of this invention is: a plug-in hybrid powertrain system, comprising:

[0007] The front axle power unit connects the engine to the CVT transmission. The engine output shaft integrates a P1 generator, which is only used to generate electricity and start the engine, and is not used to drive the vehicle.

[0008] The rear axle power unit is a dual-motor drive structure, which includes a first drive motor and a second drive motor. The two are connected to the rear axle through a mechanical coupler. The coupler can physically disconnect the mechanical link between the second drive motor and the rear axle according to the control command, so that the two motors can work independently.

[0009] The control module triggers the working mode based on the battery level. The working mode is divided into pure electric mode or hybrid mode. The hybrid mode is further divided into mild hybrid mode and full hybrid mode according to the battery level.

[0010] The P1 generator has the same power as the first drive motor. Nearly half of the engine power is used to drive the P1 generator, and the power of the P1 generator is equal to half of the engine power.

[0011] The power pressure limiting valve controls the engine output power and the input current of the rear axle motor.

[0012] Preferably, the pure electric mode or hybrid mode allows full-power drive of the dual motors when SOC > 40%, the trigger threshold for mild hybrid mode is SOC ≤ 40%, and the trigger threshold for full hybrid mode is SOC ≤ 30%.

[0013] Preferably, the mild hybrid mode includes: in the mild hybrid mode, the battery power is relatively sufficient, dual motors drive, the control module controls the output power to be about 70%, the generator allocates half of the total power for power generation, and the front drive only allocates about 20% for driving the vehicle.

[0014] In mild hybrid mode, if four-wheel drive is required, the control module can be turned off with one click, and the engine power will be distributed to the front drive.

[0015] Preferably, the hybrid mode includes: switching to hybrid mode when the battery SOC is ≤30%. In this mode, the control module is automatically shut down, the generator outputs its power, nearly half of the power directly drives the front wheels, and nearly half of the power drives the P1 generator to generate electricity. Only the first drive motor keeps working, and the single motor still has spare power when the battery is at 30%. During start-up and rapid acceleration, electric drive is the main mode to reduce fuel consumption.

[0016] Preferably, the set power of the first drive motor of the rear axle power unit is the same as the rated speed power output of the P1 generator; the power of the second drive motor is freely configured according to the vehicle size and power requirements, and the second drive motor is powered on simultaneously with the first drive motor and drives the rear axle in cooperation only in pure electric mode or mild hybrid mode.

[0017] Preferably, the mechanical coupler performs a physical disconnection operation in hybrid mode, completely separating the mechanical connection between the second drive motor and the rear axle, so that only the first drive motor works.

[0018] Preferably, the clutch device provided between the CVT transmission and the differential cuts off the power transmission from the engine to the front axle in pure electric mode, completely disengaging the front-drive system from its working state.

[0019] Preferably, in hybrid mode, when the vehicle is traveling at a constant speed and the power demand is not high, the power limiting valve enforces two restrictions: first, it constrains the upper limit of the engine output power; second, it limits the input current value of the first drive motor so that the real-time electrical power consumed does not exceed the current actual output power of the P1 generator.

[0020] Preferably, during hybrid operation, the electrical energy generated by the P1 generator is first supplied directly to the first drive motor, and only the remaining electrical energy after the first drive motor has consumed it is sent to the battery to perform charging.

[0021] As a preferred option, when the SOC drops to 42%, the control module starts in advance to give the engine time to idle and warm up. High-speed drive is prohibited before the warm-up is complete. When the generator is idling and warming up, the P1 generator will also charge the battery with a small amount of electrical energy, so as not to waste too much fuel and energy.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention completely eliminates users' anxiety about insufficient pure electric range by setting a control strategy that allows users to freely choose between pure electric or hybrid mode when the battery charge is above 40%, forces the vehicle to enter mild hybrid mode when the charge is ≤40%, and switches to full hybrid mode when the charge is ≤30%. It also ensures that the vehicle can drive stably in any charge state and completely avoids the risk of power interruption and stalling that may occur in existing plug-in hybrid systems under extreme conditions.

[0024] 2. In the hybrid mode, the present invention uses 50% of the engine power to drive the front wheels and 50% of the power to drive the P1 generator to supply power. Only the first drive motor is activated. At the same time, the power consumption of the first drive motor is forced to be equal to the real-time power generation of the P1 generator through the power limiting valve. This fundamentally solves the problem of power drop caused by the motor forcibly extracting the residual power of the battery under the condition of low battery, and ensures that the vehicle still has continuous and reliable power output capability when the battery is low.

[0025] 3. This invention initiates the engine idle preheating program in advance when the battery level drops to 42%, allowing the engine to complete the lubrication system circulation and temperature balance before entering high-speed drive. This completely solves the abnormal wear problem caused by direct high-load operation during cold starts in existing plug-in hybrid vehicles, thereby significantly improving the reliability and durability of engine operation. Attached Figure Description

[0026] Figure 1 The diagram shown is a schematic representation of the operation of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides an embodiment: a plug-in hybrid powertrain system, comprising:

[0029] The front axle power unit connects the engine to the CVT transmission. The engine output shaft integrates a P1 generator, which is only used to generate electricity and start the engine, and is not used to drive the vehicle.

[0030] The rear axle power unit is a dual-motor drive structure, which includes a first drive motor and a second drive motor. The two are connected to the rear axle through a mechanical coupler. The coupler can physically disconnect the mechanical link between the second drive motor and the rear axle according to the control command, so that the two motors can work independently.

[0031] The control module triggers the working mode based on the battery level. The working mode is divided into pure electric mode or hybrid mode. The hybrid mode is further divided into mild hybrid mode and full hybrid mode according to the battery level.

[0032] The P1 generator has the same power as the first drive motor. Nearly half of the engine power is used to drive the P1 generator, and the power of the P1 generator is equal to half of the engine power.

[0033] The power pressure limiting valve controls the engine output power and the input current of the rear axle motor.

[0034] The core of this invention lies in its hierarchical power threshold control strategy, dual-motor time-sharing collaborative architecture, and dynamic power limiting mechanism, which completely solves the problems of power interruption risk, battery over-discharge damage, and engine cold start wear in existing plug-in hybrid vehicles under low-power conditions.

[0035] Furthermore, the front axle power unit will be explained in detail:

[0036] The engine is a four-cylinder gasoline engine, with its crankshaft end rigidly connected to the rotor shaft of the P1 generator via a flange, achieving direct conversion of mechanical energy to electrical energy. The three-phase output cables of the P1 generator stator winding are connected to the rear axle motor control unit and the battery management system. The input shaft of the CVT transmission is coupled to the engine flywheel housing via a hydraulic torque converter, while the output shaft is connected to the front axle differential input gear via a multi-plate wet clutch. This clutch performs engagement / disengagement operations under the command of the control module: in pure electric mode, the clutch is completely disengaged, cutting off the entire power transmission path from the engine to the front axle; in hybrid mode or pure oil mode, the clutch is fully engaged, and the engine torque drives the front wheels after being transmitted through the CVT. Regarding the CVT transmission, the torque is adapted to the total torque of the engine, but in actual operation, the P1 generator allocates half of the engine's power, thus being subjected to the torque of the CVT transmission, reducing its power by almost half, thereby ensuring that the CVT transmission does not slip due to torque during operation.

[0037] Furthermore, the rear axle power unit will be explained in detail:

[0038] The rear axle adopts a coaxial dual-motor structure. The rated power of the first drive motor is strictly matched with the maximum output power of the P1 generator. For example, if the peak power of the P1 generator is 20kW, then the rated power of the first drive motor is also 20kW. The power of the second drive motor is dynamically adjusted according to the vehicle model. For example, a small car is equipped with 30kW, and a mid-size car is equipped with 60kW. The output shafts of the two motors are connected to a mechanical coupler. Under the command of the control module, the coupler can perform two states:

[0039] Engagement state: The combined output torque of the two motors is transmitted to the rear axle differential;

[0040] Disconnected state: The output shaft of the second drive motor is completely disengaged from the rear axle differential, and only the first drive motor drives the rear wheels.

[0041] Furthermore, the operating logic of the control module will be explained in detail:

[0042] The control module uses the battery state of charge (SOC) as the sole criterion and divides the operation into three levels:

[0043] When SOC > 40%, the driver can freely choose between pure electric mode or hybrid mode;

[0044] When 40% ≥ SOC > 30%, the system is forced to enter mild hybrid mode and pure electric mode is prohibited.

[0045] When SOC ≤ 30%, the system is forced to enter remixing mode.

[0046] When the SOC drops to 42%, the control module triggers the engine preheating program, starts the engine to idle at 800 rpm and maintains it for at least 30 seconds. During this period, the engine speed is prohibited from exceeding 1500 rpm. The preheating is considered complete when the oil pressure reaches 2.5 Bar and the coolant temperature is >60℃.

[0047] Furthermore, the power pressure limiting valve will be explained in detail below:

[0048] In hybrid mode, the power limiting valve enforces two restrictions: first, it constrains the upper limit of the engine output power; second, it limits the input current value of the first drive motor so that the real-time electrical power consumed by it does not exceed the actual power output of the P1 generator.

[0049] Please see Figure 1 Furthermore, the workflow of the present invention will be described in detail below, specifically:

[0050] When the battery charge is greater than 40%, the driver can actively select pure electric mode or hybrid mode. When the driver actively selects pure electric mode, the system immediately executes the following: the front axle clutch is completely disengaged to cut off the mechanical connection between the engine and the transmission, so that the engine and P1 generator stop running completely; the rear axle mechanical coupler remains engaged, and the power battery simultaneously supplies power to the first drive motor and the second drive motor, and the two motors jointly output torque to drive the rear wheels; the vehicle relies solely on the rear axle dual motors for power throughout the entire journey, and the front axle drive system is in a completely idle state until the driver switches modes or the battery charge drops below 40%.

[0051] When the battery charge drops to 40% for the first time or the driver actively selects hybrid mode when the charge is above 40%, the system is forced into mild hybrid mode: the control module starts the engine and calculates the total power demand of the system in real time, limiting the upper limit of the engine output power to 70% of the total power. 50% of this power is converted into electrical energy through the P1 generator. The generated electrical energy and the battery electrical energy are combined to drive the dual motors on the rear axle. Nearly 20% of the engine power is driven directly to the front wheels through the CVT transmission. The rear axle coupler remains engaged throughout the process to make the dual motors work together. If the driver selects hybrid mode when the charge is above 40%, the engine power distribution is not limited to 70% of the total power, but still prioritizes the 50% generation and 50% direct drive distribution ratio.

[0052] When the battery charge drops to 30% or lower, the system automatically switches to hybrid mode: the engine output power is distributed in a fixed ratio, with 50% directly driving the front wheels and 50% driving the P1 generator to generate electricity. All the electricity generated by the P1 generator is directly supplied to the first drive motor. The power limiting valve monitors the output current of the P1 generator in real time and forcibly limits the input current value of the first drive motor to be equal to it. The control module simultaneously cuts off the power supply to the second drive motor and controls the rear axle coupler to perform a mechanical disengagement operation, so that the second drive motor is completely disconnected from the rear axle transmission system. The battery stops discharging in this mode. If the power generation of the P1 generator exceeds the real-time demand of the first drive motor, the excess power is automatically transferred to the battery charging circuit.

[0053] Furthermore, the key protection mechanism of this invention will be explained in detail:

[0054] In the hybrid mode triggered when the battery charge drops to 30%, the system simultaneously executes three hard protections: the first is that the control module immediately cuts off the power supply circuit of the second drive motor to completely de-energize it; the second is that the rear axle coupler forcibly separates the mechanical connection between the second drive motor and the rear axle differential to eliminate idling; the third is that the power limiting valve locks the upper limit of the input current of the first drive motor, so that its real-time power consumption absolutely does not exceed the output power value of the P1 generator. At the same time, the battery management system starts the one-way conduction mode, allowing only electrical energy to flow into the battery for charging and prohibiting any discharge behavior, thereby completely blocking the path for the motor to forcibly extract the residual power of the battery and avoiding deep discharge damage to the battery from the root.

[0055] When the battery charge drops from above 42% to 42% for the first time, the control module immediately triggers a preheating program: the engine is started to idle at 800 rpm and kept running, while the engine speed is limited to no more than 1,500 rpm. During this preheating period, the front axle clutch remains disengaged to prevent engine power from being transmitted to the front wheels, ensuring that the engine is fully lubricated and warmed up before entering high-load driving.

[0056] The system applies different torque constraints to the CVT transmission in mild hybrid and severe hybrid modes: In mild hybrid mode, since the engine output power is capped at 70% of the total system power and 50% of that is used for power generation, the actual direct drive power delivered to the transmission does not exceed 30% of the total power, and the control module dynamically limits the transmission output torque accordingly; In severe hybrid mode, when the engine is driving the front wheels at 50% power, the control module monitors the transmission output shaft torque in real time, and if the required torque exceeds this threshold, it prioritizes reducing the engine output power.

[0057] Furthermore, under full throttle acceleration, the system will default to shutting down the P1 generator's power generation function for a maximum of ten seconds, regardless of the hybrid mode. The power battery will be fully discharged to drive the motor, and both motors will supply power simultaneously. At this time, the power is the sum of the engine's total power and the total power of the two motors to drive the vehicle for a maximum of ten seconds.

[0058] Furthermore, by leveraging the advantages of the traditional CYT transmission, energy recovery can be made more efficient. Currently, whether it is pure electric, plug-in hybrid, or rear-drive motor, the amount of energy recovery is affected by the vehicle speed. In this invention, the P1 generator, which is directly connected to the engine, is directly connected to the transmission in hybrid mode. Regardless of the vehicle speed, the transmission system will ensure that the engine and P1 generator always maintain a high-efficiency speed when coasting in gear and going downhill, thereby ensuring more efficient energy recovery.

[0059] Furthermore, to make the electric drive axle more efficient, a two-speed gear set can be integrated into the rear axle, allowing the drive motor to meet the vehicle's driving speed within its maximum rated speed range. For example, the low gear is lower than the current driving speed, thereby increasing the torque of the low-speed drive motor, while the high gear is higher than the current driving speed, thereby reducing energy consumption.

[0060] Furthermore, the present invention provides an embodiment:

[0061] When this powertrain system is installed in a mid-size SUV, with the battery initially at 80% charge, the driver selects pure electric mode: the front axle clutch disengages to completely stop the engine, the rear axle coupler engages, and the power battery simultaneously supplies power to the first and second drive motors. The two motors work together to drive the rear wheels, achieving zero-fuel-consumption driving. When the battery charge drops to 42%, the control module automatically starts the engine and maintains an idle speed of 800 rpm for preheating, while monitoring the oil pressure and coolant temperature. After preheating, when the battery charge drops to 40%, it enters mild hybrid mode, where the engine power is limited to 70% of the total system power demand. Of this, 50% is used to drive the P1 generator to generate electricity, which is combined with the battery power to drive the two rear axle motors. The remaining 20% ​​of the kinetic energy is directly driven to the front wheels via the CVT transmission, with no power interruption throughout the entire process.

[0062] Furthermore, the present invention provides an embodiment:

[0063] When the vehicle enters the highway in mild hybrid mode with a battery charge of 32%, the dual rear axle motors work in conjunction with the engine to drive the vehicle. When the battery charge continues to deplete to 30%, the system forcibly switches to full hybrid mode. At this time, the engine power is redistributed 50% to drive the front wheels directly and 50% to drive the P1 generator to generate electricity. The P1 generator outputs 18 kW of electrical energy, which is directly supplied to the first drive motor with a rated power of 20 kW. The power limiting valve limits the input power of the motor to no more than 18 kW in real time. The second drive motor is disconnected from the power supply, and the rear axle coupler mechanically separates it from the differential. If the P1 generator actually outputs 15 kW while the first drive motor only needs 12 kW, the surplus 3 kW of electrical energy is automatically used to charge the battery. The vehicle maintains hybrid driving until the destination, and the battery charge remains stable in the range of 22% to 30%, without triggering deep discharge.

[0064] Furthermore, the present invention provides an embodiment:

[0065] This plug-in powertrain system is also suitable for heavy-duty commercial freight vehicles. Given the limited load capacity of CVT transmissions, freight models need to be replaced with AMT automatic transmissions to handle high torque and high load conditions. Existing diesel or natural gas engines can be used, with an integrated P1 generator (used only for power generation and starting, not for driving). The drive axle structure needs adjustment: a dual-drive axle structure is used, with the front drive axle driven by the engine and the rear drive axle replaced by an electric drive axle, suitable for two-axle or three-axle trucks, or single-rear-drive axle models. The electric drive axle uses a dual-motor configuration, with the main drive motor's power matching the P1 generator to ensure power matching. The auxiliary motor is flexibly configured according to load and power requirements. The system still uses a SOC-based hierarchical control strategy, coordinating engine output and motor power consumption in real time through a power pressure limiting valve. When the battery is low, it forces entry into hybrid mode and limits motor power consumption to prevent over-discharge of the battery. Simultaneously, the P1 generator efficiently generates electricity to ensure continuous driving capability, enabling smooth switching and reliable operation of freight vehicles in pure electric, pure gasoline, or hybrid modes.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A plug-in hybrid powertrain system, characterized in that, Including: The front axle power unit connects the engine to the CVT transmission. The engine output shaft integrates a P1 generator, which is only used to generate electricity and start the engine, and is not used to drive the vehicle. The rear axle power unit is a dual-motor drive structure, which includes a first drive motor and a second drive motor. The two are connected to the rear axle through a mechanical coupler. The coupler can physically disconnect the mechanical link between the second drive motor and the rear axle according to the control command, so that the two motors can work independently. The control module triggers the working mode based on the battery level. The working mode is divided into pure electric mode or hybrid mode. The hybrid mode is further divided into mild hybrid mode and full hybrid mode according to the battery level. The P1 generator has the same power as the first drive motor. Nearly half of the engine power is used to drive the P1 generator, and the power of the P1 generator is equal to half of the engine power. The power pressure limiting valve controls the engine output power and the input current of the rear axle motor.

2. The plug-in hybrid powertrain system according to claim 1, characterized in that: The pure electric mode or hybrid mode allows full-power drive of both motors when SOC > 40%, the trigger threshold for mild hybrid mode is SOC ≤ 40%, and the trigger threshold for full hybrid mode is SOC ≤ 30%.

3. The plug-in hybrid powertrain system according to claim 1, characterized in that, The mild hybrid mode includes: In mild hybrid mode, the battery has relatively sufficient power, dual motors drive, the control module controls the output power to be around 70%, the generator allocates half of the total power for power generation, and the front drive only allocates about 20% for driving the vehicle. In mild hybrid mode, if four-wheel drive is required, the control module can be turned off with one click, and the engine power will be distributed to the front drive.

4. A plug-in hybrid powertrain system according to claim 1, characterized in that, The hybrid mode includes: when the battery SOC is ≤30%, switch to hybrid mode. In this mode, the control module is automatically shut down, the generator outputs its power, nearly half of the power directly drives the front wheels, and nearly half of the power drives the P1 generator to generate electricity. Only the first drive motor keeps working. The single motor still has spare power when the battery is at 30%. During start-up and rapid acceleration, electric drive is the main mode to reduce fuel consumption.

5. A plug-in hybrid powertrain system according to claim 1, characterized in that: The set power of the first drive motor of the rear axle power unit is the same as the rated speed power output of the P1 generator; the power of the second drive motor is freely configured according to the vehicle size and power requirements. The second drive motor is powered on simultaneously with the first drive motor and drives the rear axle in cooperation only in pure electric mode or mild hybrid mode.

6. A plug-in hybrid powertrain system according to claim 1, characterized in that: In hybrid mode, the mechanical coupler performs a physical disconnection operation, completely separating the mechanical connection between the second drive motor and the rear axle, so that only the first drive motor works.

7. A plug-in hybrid powertrain system according to claim 1, characterized in that: The clutch device installed between the CVT transmission and the differential cuts off the power transmission from the engine to the front axle in pure electric mode, completely disengaging the front-wheel drive system from its working state.

8. A plug-in hybrid powertrain system according to claim 1, characterized in that, In hybrid mode, when the vehicle is traveling at a constant speed and the power demand is not high, the power limiting valve enforces two restrictions: the first is to constrain the upper limit of the engine output power. The second is to limit the input current value of the first drive motor so that its real-time electrical energy consumption does not exceed the actual power output of the P1 generator.

9. A plug-in hybrid powertrain system according to claim 1, characterized in that: During hybrid operation, the electrical energy generated by the P1 generator is preferentially supplied directly to the first drive motor. Only when the remaining electrical energy after the first drive motor has consumed the energy will it be supplied to the battery to perform charging operations.

10. A plug-in hybrid powertrain system according to claim 1, characterized in that: When the SOC drops to 42%, the control module starts in advance to give the engine time to idle and warm up. High-speed drive is prohibited before the warm-up is complete. When the generator is idling and warming up, the P1 generator will also charge the battery with a small amount of electrical energy, so as not to waste too much fuel and energy.

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