Powertrain control method for switching between d and r ranges

Abstract

The application discloses a kind of D and R mutual switching power assembly control method, belong to new energy automobile control technical field.It includes: let VCU according to received shift lever gear signal, determine whether the shift lever gear is the mutual switching operation between D and R;According to shift lever gear, request target gear to TCU, TCU controls DCT transmission to shift according to target gear, and after DCT transmission shift is completed, actual gear signal of DCT transmission is sent to VCU;Judge whether engine participates in driving.The D and R mutual switching power assembly control method of the application is for the hybrid power architecture of P2+DCT, realizes when driver is in low vehicle speed and stationary state and D and R mutual switching, vehicle is according to the intention of driver and travels.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle control, and more specifically, relates to a powertrain control method for switching between D gear and R gear. Background Art

[0002] When driving a vehicle, the driver often operates the gear lever from D to R, or from R to D, or from D to N and then to R, or from R to N and then to D, according to the needs of forward and reverse. Of course, in order to respond to the driver's needs more quickly, many vehicles can also directly shift to R when moving forward at a low speed and reverse directly, and vice versa, they can also directly shift to D when moving backward at a low speed.

[0003] Shifting from D gear to R gear and vice versa is the most basic requirement. For the driver's switching between D gear and R gear, different powertrain control strategies are needed to meet the needs of different power architectures. For example, for the P2+DCT hybrid architecture, the P2+DCT hybrid architecture is characterized by two clutches connecting the motor and the DCT transmission, so it can select different clutches to combine according to different transmission gears to drive the vehicle. However, among the multiple possible gear and torque distribution combinations, in order to simultaneously meet the switching control of D gear and R gear in place, and also meet the needs of shifting to R gear when moving forward at low speeds and shifting to D gear when reversing at low speeds, this is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] 1. Problems to be solved

[0005] In response to the problems existing in the prior art, the present invention provides a powertrain control method for switching between D gear and R gear. For the P2+DCT hybrid architecture, when the driver switches between D gear and R gear at low speed and in a stationary state, the vehicle drives according to the driver's intention.

[0006] 2. Technical solution

[0007] To solve the above problems, the present invention adopts the following technical solutions.

[0008] A powertrain control method for switching between D gear and R gear is used to control vehicle operation according to the driver's intention, and the control method includes:

[0009] Step S010: Instruct the VCU to determine whether the gear lever position is a switch operation between D and R based on the received gear lever position signal; wherein the switch operation between D and R includes switching from D to R, switching from D to N and then to R, switching from R to D, and switching from R to N and then to D.

[0010] Step S020: Requesting a target gear position from the TCU based on the gear lever position. The TCU controls the DCT transmission to shift gears based on the target gear position and sends an actual gear position signal of the DCT transmission to the VCU after the DCT transmission shifts gears.

[0011] Step S030: determine whether the engine is involved in driving;

[0012] Step S040: If the DCT transmission shift is completed and the engine is not involved in driving, the VCU is instructed to request the motor torque to synchronize the motor speed with the clutch input shaft speed;

[0013] Step S050: If the DCT transmission shift is completed, or the motor speed and the clutch input shaft speed are synchronized, and the engine is driving at this time, determine whether the clutch input shaft speed is less than 0. If the clutch input shaft speed is less than 0, the VCU requests the TCU to execute a fixed torque of the K1 clutch or the K2 clutch, so that the vehicle decelerates under the action of the fixed torque until the vehicle decelerates to 0, and the powertrain control is terminated. If the clutch input shaft speed is equal to 0, the powertrain control is terminated.

[0014] Preferably, before step S010, the method further includes:

[0015] The driver operates the gear lever, causing the TCU to analyze the gear lever position signal and send it to the VCU.

[0016] Preferably, in step S020, a target gear position is requested from the TCU according to the gear lever position signal of the VCU, and the TCU controls the DCT transmission to shift gears according to the target gear position, which specifically includes:

[0017] If the current VCU gear lever is in R gear, the VCU requests the TCU to set the target gear to R gear;

[0018] If the current VCU gear lever is in D gear, the VCU requests the TCU to set the target gear to 1 gear. The TCU controls the DCT transmission to shift gears according to the target gear. After the DCT transmission shifts gears, the TCU sends the actual gear position signal of the DCT transmission to the VCU, and the VCU determines that the shift is completed.

[0019] Preferably, in step S030, determining whether the engine is involved in driving specifically includes:

[0020] The VCU receives the status information of the K0 clutch and the engine status information fed back by the EMS;

[0021] Based on the K0 clutch status information received by the VCU and the engine status information fed back by the EMS, it is determined whether the engine is involved in driving; wherein:

[0022] If the VCU receives feedback from the TCU that the K0 clutch state is engaged and the EMS feedback that the engine state is running, it is determined that the engine is involved in driving; otherwise, it is determined that the engine is not involved in driving.

[0023] Preferably, in step S040, the VCU is instructed to request the motor torque so as to synchronize the motor speed with the clutch input shaft speed, which specifically includes:

[0024] The VCU uses the difference between the actual motor speed and the clutch input shaft speed to perform PID control and request the motor torque from the PEU.

[0025] After receiving the motor torque request from the VCU, the PEU controls the motor to execute the requested torque so that the motor speed approaches the clutch input shaft speed; wherein:

[0026] If the difference between the actual motor speed and the clutch input shaft speed is less than a certain value, the motor speed and the clutch input shaft speed are considered to be synchronized.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention is aimed at the P2+DCT hybrid power architecture. Based on the characteristics of the P2+DCT hybrid power architecture, when the driver switches between D gear and R gear at low speed and in a stationary state, the vehicle can still drive according to the driver's intention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. 1 This is the P2+DCT hybrid architecture diagram;

[0031] Fig. 2 This is the interactive signal diagram of the VCU, TCU, and PEU in this application;

[0032] Fig. 3 This is a control flow chart for switching between D gear and R gear in one embodiment of the present application;

[0033] Fig. 4 This is a schematic diagram of the control of switching from D gear to R gear with the engine participating in driving while the vehicle is moving in one embodiment of the present application;

[0034] Fig. 5 A schematic diagram of the control of switching from D gear to R gear in which the engine does not participate in driving while the vehicle is moving in one embodiment of the present application;

[0035] In the figure: 1. DCT transmission; 2. PRND gear; 3. TCU; 4. VCU; 5. PEU; 6. Motor; 7.; 8. Engine; 9. EMS; 11. K2 clutch; 12. K1 clutch; 13. DCT transmission input shaft; 14. DCT transmission shaft 2; 15. DCT transmission shaft 1. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments and accompanying drawings. However, those skilled in the art will appreciate that the present invention is not limited to the accompanying drawings and the following embodiments.

[0037] like Figs. 1-5 As shown, the P2+DCT hybrid architecture features two clutches connecting the motor 6 and the DCT transmission 1: a K1 clutch 12 and a K2 clutch 11. Different clutches are selected for engagement according to different transmission gears to drive the vehicle. For example, shaft 15 of the DCT transmission 1 is connected to the K1 clutch 12 and has gears 1, 3, 5, and R, while shaft 2 14 is connected to the K1 clutch and has gears 2, 4, and 6. Of course, the gears on different DCT transmissions 1 may be designed differently.

[0038] The TCU3 is responsible for controlling the opening and closing of the K1 clutch 12, the K2 clutch 11, and the K0 clutch 7 on the DCT transmission 1, as well as torque loading. It also controls the shifting of various gears on the DCT transmission 1. The TCU3 is also responsible for parsing the PRND gear 2 information.

[0039] This embodiment mainly provides a powertrain control method for switching between D gear and R gear, which is used to control vehicle operation according to the driver's intention. The control method includes:

[0040] Step S010, instruct the VCU to determine whether the gear lever position is a mutual switching operation between D gear and R gear based on the received gear lever position signal; wherein the mutual switching operation between D gear and R gear includes switching from D gear to R gear, switching from D gear to N gear and then to R gear, switching from R gear to D gear, and switching from R gear to N gear and then to D gear.

[0041] Before step S010, when the driver operates the gear lever, the TCU first analyzes the gear lever position signal and sends it to the VCU. The VCU then determines whether the gear lever position is a switch between D and R according to the received gear lever position signal.

[0042] Step S020: Requesting a target gear position from the TCU based on the gear lever position. The TCU controls the DCT transmission to shift gears based on the target gear position and sends an actual gear position signal of the DCT transmission to the VCU after the DCT transmission shifts gears. This process specifically includes:

[0043] If the current VCU gear lever is in R gear, the VCU requests the TCU to set the target gear to R gear;

[0044] If the current VCU gear lever is in D gear, the VCU requests the TCU to set the target gear to 1 gear. The TCU controls the DCT transmission to shift gears according to the target gear. After the DCT transmission shifts gears, the TCU sends the actual gear position signal of the DCT transmission to the VCU, and the VCU determines that the shift is completed.

[0045] Step S030: Determine whether the engine 8 is involved in driving. There are different control strategies for determining whether the engine 8 is involved in driving. The determination of whether the engine 8 is involved in driving specifically includes:

[0046] The VCU receives the status information of the K0 clutch and the engine status information fed back by the EMS;

[0047] Based on the K0 clutch status information received by the VCU and the engine status information fed back by the EMS, it is determined whether the engine is involved in driving; wherein:

[0048] If the VCU receives feedback from the TCU that the K0 clutch state is engaged and the EMS feedback that the engine state is running, it is determined that the engine is involved in driving; otherwise, it is determined that the engine is not involved in driving.

[0049] If the DCT transmission shift is completed and the engine is not involved in driving, the VCU requests the motor torque to synchronize the motor speed with the clutch input shaft speed. This process specifically includes:

[0050] The VCU uses the difference between the actual motor speed and the clutch input shaft speed to perform PID control and request the motor torque from the PEU.

[0051] After receiving the motor torque request from the VCU, the PEU controls the motor to execute the requested torque so that the motor speed approaches the clutch input shaft speed; wherein:

[0052] If the difference between the actual motor speed and the clutch input shaft speed is less than a certain value, the motor speed and the clutch input shaft speed are considered to be synchronized.

[0053] Step S050: If the DCT transmission shift is completed, or the motor speed and the clutch input shaft speed are synchronized, and the engine is driving at this time, determine whether the clutch input shaft speed is less than 0. If the clutch input shaft speed is less than 0, the VCU requests the TCU to execute a fixed torque of the K1 clutch or the K2 clutch, so that the vehicle decelerates under the action of the fixed torque until the vehicle decelerates to 0, and the powertrain control is terminated. If the clutch input shaft speed is equal to 0, the powertrain control is terminated.

[0054] During the above process, when engine 8 is driving, because it is in speed control at low speeds, if the vehicle is currently in motion, the VCU4 requests the TCU3 to apply a fixed torque to the K1 clutch 12. This torque value can be calibrated. The vehicle then decelerates under the action of the fixed torque. When the vehicle decelerates to 0, the powertrain control for switching between D and R gears ends, and the vehicle then reverses direction. If the speed of the DCT transmission 1 input shaft 13 is 0, the powertrain control for switching between D and R gears ends. When engine 8 is not driving, if the vehicle is currently in motion, there is a certain difference between the actual speed of the motor 6 and the speed of the DCT clutch 1 input shaft 13. The VCU4 uses this difference to perform PID control and request torque from the PEU5. By requesting the PEU5 to control the motor 6 to deliver the requested torque, the actual speed of the motor 6 is brought to the same speed as the input shaft 13 of the DCT transmission 1. This strategy serves two purposes: first, engaging the K1 clutch only after the speed difference between the actual speed of the motor 6 and the input shaft 13 of the DCT transmission 1 is minimized, thereby reducing vehicle jerk. Second, the smaller the speed difference between the actual speed of the motor 6 and the input shaft 13 of the DCT transmission 1 after the K1 clutch is engaged, the less slip work in the K1 clutch 12 is generated, resulting in less energy loss and a lower risk of overheating of the K1 clutch 12 at the same drive torque. If the speed of the input shaft 13 of the DCT transmission 1 reaches zero, the powertrain control for switching between D and R gears is terminated.

[0055] The hybrid architecture of P2+DCT in this application is based on the characteristics of the hybrid architecture of P2+DCT, so that when the driver switches between D gear and R gear at low speed and in a stationary state, the vehicle can still drive according to the driver's intention.

[0056] The examples described in the present invention are merely descriptions of the preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should fall within the scope of protection of the present invention.

Claims

1. A powertrain control method for switching between D and R gears, for controlling vehicle operation according to a driver's intention, is characterized by: The control method includes: Step S010: Instruct the VCU to determine whether the gear lever position is a switch operation between D and R based on the received gear lever position signal; wherein the switch operation between D and R includes switching from D to R, switching from D to N and then to R, switching from R to D, and switching from R to N and then to D. Step S020: Requesting a target gear position from the TCU based on the gear lever position. The TCU controls the DCT transmission to shift gears based on the target gear position and sends an actual gear position signal of the DCT transmission to the VCU after the DCT transmission shifts gears. Step S030: determine whether the engine is involved in driving; Step S040: If the DCT transmission shift is completed and the engine is not involved in driving, the VCU is instructed to request the motor torque to synchronize the motor speed with the clutch input shaft speed; Step S050: If the DCT transmission shift is completed, or the motor speed and the clutch input shaft speed are synchronized, and the engine is driving at this time, determine whether the clutch input shaft speed is less than 0. If the clutch input shaft speed is less than 0, the VCU requests the TCU to execute a fixed torque of the K1 clutch or the K2 clutch, so that the vehicle decelerates under the action of the fixed torque until the vehicle decelerates to 0, and the powertrain control is terminated. If the clutch input shaft speed is equal to 0, the powertrain control is terminated.

2. The powertrain control method for switching between D and R gears according to claim 1, characterized in that: Before step S010, the method further includes: The driver operates the gear lever, causing the TCU to analyze the gear lever position signal and send it to the VCU.

3. The powertrain control method for switching between D and R gears according to claim 1, characterized in that: In step S020, a target gear position is requested from the TCU according to the gear lever position signal of the VCU, and the TCU controls the DCT transmission to shift gears according to the target gear position, which specifically includes: If the current VCU gear lever is in R gear, the VCU requests the TCU to set the target gear to R gear; If the current VCU gear lever is in D gear, the VCU requests the TCU to set the target gear to 1 gear. The TCU controls the DCT transmission to shift gears according to the target gear. After the DCT transmission shifts gears, the TCU sends the actual gear position signal of the DCT transmission to the VCU, and the VCU determines that the shift is completed.

4. The powertrain control method for switching between D and R gears according to claim 1, characterized in that: In step S030, it is determined whether the engine is involved in driving, which specifically includes: The VCU receives the status information of the K0 clutch and the engine status information fed back by the EMS; Based on the K0 clutch status information received by the VCU and the engine status information fed back by the EMS, it is determined whether the engine is involved in driving; wherein: If the VCU receives feedback from the TCU that the K0 clutch state is engaged and the EMS feedback that the engine state is running, it is determined that the engine is involved in driving; otherwise, it is determined that the engine is not involved in driving.

5. The powertrain control method for switching between D gear and R gear according to claim 1, characterized in that: In step S040, the VCU is instructed to request the motor torque so that the motor speed is synchronized with the clutch input shaft speed, which specifically includes: The VCU uses the difference between the actual motor speed and the clutch input shaft speed to perform PID control and request the motor torque from the PEU. After receiving the motor torque request from the VCU, the PEU controls the motor to execute the requested torque so that the motor speed approaches the clutch input shaft speed; wherein: If the difference between the actual motor speed and the clutch input shaft speed is less than a certain value, the motor speed and the clutch input shaft speed are considered to be synchronized.

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