WO2022007887A1

WO2022007887A1 - Double-clutch coasting downshift control method

Info

Publication number: WO2022007887A1
Application number: PCT/CN2021/105197
Authority: WO
Inventors: 朱桂庆; 曹龙; 王歆誉; 张学锋; 孙飞
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-07-08
Filing date: 2021-07-08
Publication date: 2022-01-13
Also published as: CN111810627B; CN111810627A

Abstract

A double-clutch coasting downshift control method. The double-clutch coasting downshift control method comprises: during a coasting downshift process of a vehicle, determining whether clutches are in an oil charging stage; if the clutches are not in the oil charging stage, detecting whether a degree of opening of an accelerator is greater than an accelerator limit value; if the degree of opening of the accelerator is greater than the accelerator limit value, further determining whether a power mode of the vehicle is in a power state; and if the power mode of the vehicle is in the power state, executing an operation of performing switching from coasting downshift to power downshift and simultaneously controlling a rotation speed and torque, wherein when switching from the coasting downshift to the power downshift is performed and the rotation speed and the torque are simultaneously controlled, the following formulae are satisfied: first torque of high-gear clutch = max{first minimum torque of high-gear clutch, first total torque of clutches * first coefficient}; and first torque of low-gear clutch = first total torque of clutches * (1 - first coefficient).

Description

Dual-clutch coasting downshift control method

This application claims the priority of a Chinese patent application with application number 202010651760.4 filed with the China Patent Office on July 8, 2020, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the field of dual-clutch torque control, for example, to a dual-clutch coasting downshift control method.

Background technique

The dual-clutch automatic transmission consists of two sets of gear transmission systems, in which the odd-numbered clutches control the power transmission of odd-numbered gears, such as 1st, 3rd, 5th, and 7th; the even-numbered clutches control the power transmission of even-numbered gears, such as 2nd, 4th gear, 6th gear and R gear. After the control program in the transmission control unit selects the appropriate gear and completes the gear engagement, it respectively controls the combination and separation of the odd-numbered clutch and the even-numbered clutch to realize gear switching.

The shifting sequence of coasting downshift is clutch oil filling, torque exchange and speed adjustment. After the torque exchange stage, the working gear is switched from high gear to low gear, and the low gear clutch is the main clutch, and because of this When the engine speed is lower than the low gear clutch speed, the torque transmitted by the low gear clutch acts as a brake on the whole vehicle. At this stage, if the driver depresses the accelerator, the engine speed will rise rapidly. After exceeding the low-gear clutch speed, the torque transmitted by the low-gear clutch drives the vehicle. When the torque transmitted by the low-gear clutch to the vehicle changes from braking to driving, it is easy to generate shocks and affect the driving experience.

SUMMARY OF THE INVENTION

The present application provides a dual-clutch coasting downshift control method. When the accelerator is stepped on for coasting downshift, the torque is transmitted by controlling the low-gear clutch and the high-gear clutch at an appropriate time, and the speed of the engine is controlled to achieve two The torque transmitted by the clutch to the vehicle smoothly transitions from the braking effect to the driving effect, which improves the smoothness of shifting of the dual-clutch automatic transmission.

Provided is a dual-clutch coasting downshift control method, comprising: judging whether a clutch is in an oil-filling stage during a vehicle coasting downshift; if the clutch is not in an oil-filling stage, detecting whether an accelerator opening is greater than an accelerator limit; If the speed is greater than the throttle limit value, continue to judge whether the power mode of the vehicle is the power state; if the power mode of the vehicle is the power state, execute the operation of switching from coasting downshift to power downshift and controlling the speed and torque at the same time; When the gear is converted to power downshift and the speed and torque are controlled at the same time, set the first torque of the high-speed clutch=max{the first minimum torque of the high-speed clutch, the first total torque of the clutch*the first coefficient}, and the first torque of the low-speed clutch=max Clutch first total torque*(1-first coefficient); the first coefficient is greater than zero and less than or equal to 1, and the first coefficient gradually increases to 1 over time.

Optionally, the method further includes: if the power mode of the vehicle is not the power state, executing a coasting downshift control operation, and judging whether the power mode is the power state every preset time; wherein the coasting downshift control The operation includes judging whether the shift stage is in the torque exchange stage; when the shift stage is in the torque exchange stage, set the second torque of the high-gear clutch to max{the second minimum torque of the high-gear clutch, the second total torque of the clutch*(1 - second coefficient)}, the second torque of the low gear clutch is the second total torque of the clutch * the second coefficient; the second coefficient is greater than zero and less than or equal to 1, and the second coefficient gradually increases over time to 1.

Optionally, the coasting downshift control operation further includes: when the shift stage is not in the torque exchange stage, setting the second torque of the high-speed clutch to be the second minimum torque of the high-speed clutch, and the second torque of the low-speed clutch. is the clutch second total torque.

Optionally, performing the operation of converting from coasting downshift to power downshift and controlling the rotational speed and torque at the same time includes: calculating a first change of engine torque; calculating a first torque of clutch PID; according to the first change of engine torque and the clutch The PID first torque calculates the clutch first total torque.

Optionally, the coasting downshift control operation further includes: calculating a second change in engine torque; calculating a second clutch PID torque; calculating a second clutch PID based on the second change in engine torque and the second clutch PID torque. total torque.

Optionally, the first coefficient=first set time/total time for simultaneous control of speed and torque, where the first set time is the duration of simultaneous control of speed and torque.

Optionally, the second coefficient=second set time/total time of coasting downshift torque exchange, where the second set time is the duration of coasting downshift torque exchange.

Optionally, it is determined whether the power mode of the vehicle is the power state according to the engine torque.

Optionally, the method further includes:

Determine whether the duration of simultaneous control of speed and torque exceeds a predetermined value;

If the duration of the simultaneous control of the rotational speed and torque exceeds a predetermined value, a normal power downshift operation is performed.

Optionally, the throttle limit value is 3% to 20%.

Description of drawings

1 is a schematic flowchart of a dual-clutch coasting downshift control method according to an embodiment of the application;

2 is a schematic flowchart of another dual-clutch coasting downshift control method according to an embodiment of the application;

FIG. 3 is a schematic flowchart of another dual-clutch coasting downshift control method according to an embodiment of the present application.

detailed description

The embodiments of the present application will be described below with reference to the accompanying drawings and embodiments. The embodiments described herein are only used to explain the embodiments of the present application, but are not intended to limit the embodiments of the present application. For ease of description, the drawings only show some but not all structures related to the embodiments of the present application.

1 is a schematic flowchart of a dual-clutch coasting downshift control method provided by an embodiment of the present application. Referring to FIG. 1 , this embodiment provides a dual-clutch coasting downshift control method, which includes the following steps.

Step 110: During the vehicle coasting and downshifting process, determine whether the clutch is in the oil-filling stage.

Step 120: If the clutch is not in the oil-filling stage, detect whether the accelerator opening is greater than the accelerator limit.

Step 130: If the accelerator opening degree is greater than the accelerator limit value, continue to determine whether the power mode of the vehicle is the power state.

Step 140: If the power mode of the vehicle is the power state, perform the operation of switching from coasting downshift to power downshift and controlling the speed and torque at the same time; wherein, when the coasting downshift is switched to power downshift and the speed and torque are controlled at the same time, set The first torque of the high-speed clutch=max{the first minimum torque of the high-speed clutch, the first total torque of the clutch*the first coefficient}, the first torque of the low-speed clutch=the first total torque of the clutch*(1-first coefficient); The first coefficient is greater than zero and less than or equal to 1, and the first coefficient gradually increases to 1 over time.

In one embodiment, when the vehicle is coasting and downshifting, it is determined that the clutch is not in the oil-filling stage and it is detected that the accelerator opening is greater than the accelerator limit value, indicating that the driver steps on the accelerator to accelerate, wherein the accelerator opening is obtained by the accelerator pedal position sensor. . When the power mode of the vehicle is in the power state, the whole vehicle is in the driving acceleration state. If it is detected that the power mode of the vehicle is in the power state during the coasting downshift process, the vehicle is prone to rubbing, which affects the driving experience.

In this embodiment, when it is detected that the vehicle is in a power state during the coasting downshift, the operation of converting the coasting downshift to the power downshift and controlling the rotational speed and torque at the same time is performed, and the first torque of the high-speed clutch is set = max {high-speed clutch The first minimum torque, the first total torque of the clutch*the first coefficient}; the first torque of the low-gear clutch=the first total torque of the clutch*(1-the first coefficient). In the process of simultaneous control of speed and torque, the torque of the high-speed clutch and the low-speed clutch and the speed of the engine are controlled so that the speed of the engine is greater than the speed of the low-speed clutch. Since the first torque of the high-speed clutch is not lower than the first minimum torque of the high-speed clutch, it is ensured that the high-speed clutch continues to fit with the engine during the transition from coasting to power downshift. The speed of the low-speed clutch is lower than the engine speed, the speed of the low-speed clutch is greater than the engine speed, the high-speed clutch continues to drive the vehicle, and the low-speed clutch brakes the vehicle. After the engine speed is higher than the low-speed clutch, the The low-gear clutch drives the whole vehicle. By first using the high-gear clutch and the low-gear clutch in conjunction with the low-gear clutch and then switching to the low-gear clutch during the gear shifting process, it is possible to avoid the change caused by stepping on the accelerator when switching directly to the low-gear clutch. If the gear is not smooth, improve the stability of downshifting and improve the user experience.

In the embodiment of the present application, during coasting downshift, after detecting that the throttle opening exceeds the throttle limit value, it is detected that the power mode is the power state, then the coasting downshift is converted to the operation of power downshifting and the speed and torque are controlled at the same time, in this process Control the first torque of the high-speed clutch to not be lower than the first minimum torque of the high-speed clutch, and the first torque of the high-speed clutch gradually increases. At this time, the vehicle is driven by the high-speed clutch, and the engine speed gradually increases until it is greater than the low-speed clutch. The engine drives the low-speed clutch to rotate, and the low-speed clutch drives the vehicle to move forward, thus preventing the high-speed clutch from directly leaving the engine, and the low-speed clutch and the engine fitting together causing the vehicle to stumble.

FIG. 2 is a schematic flowchart of another dual-clutch coasting downshift control method provided by an embodiment of the present application. Referring to FIG. 2 , the dual-clutch coasting downshift control method further includes the following steps.

Step 150: If the power mode of the vehicle is not the power state, execute a coasting downshift control operation, and determine whether the power mode is the power state at preset time intervals; wherein the coasting downshift control operation includes judging whether the shift stage is in torque state Exchange stage; when the shift stage is in the torque exchange stage, set the second torque of the high-gear clutch to max{the second minimum torque of the high-gear clutch, the second total torque of the clutch*(1-second coefficient)}, the low-gear clutch The second clutch torque is the second total clutch torque * the second coefficient; the second coefficient is greater than zero and less than or equal to 1, and the second coefficient gradually increases to 1 with time.

In one embodiment, when the shifting stage is in the torque exchange stage, the second torque of the high-speed clutch is set to not be lower than the second minimum torque of the high-speed clutch, and when the second torque of the high-speed clutch is not 0, the high-speed clutch can continue to operate with The engine is in snug condition. With the gradual increase of the second coefficient, the torque of the low gear clutch gradually increases, and the second torque of the high gear clutch will gradually decrease but will not be lower than the second minimum torque of the high gear clutch, so that the high gear clutch continues to drive the whole The car movement, high-speed clutch and low-speed clutch cooperate with each other to improve the smoothness of downshift and enhance the user experience.

Optionally, the coast downshift control operation also includes:

When the shift stage is not in the torque exchange stage, the second torque of the high-gear clutch is set as the second minimum torque of the high-gear clutch, and the second torque of the low-gear clutch is the second total torque of the clutch.

Both the high-speed clutch and the low-speed clutch are fitted with the engine, and the high-speed clutch drives the entire vehicle, thus avoiding the uneven shifting caused by stepping on the accelerator when switching directly to the low-speed clutch.

Optionally, the operations of performing coasting downshifting to power downshifting and controlling the rotational speed and torque simultaneously include: calculating a first change in engine torque; calculating a first clutch proportional-integral-differential (PID) torque; The first delta and the clutch PID first torque calculate the clutch first total torque.

In one embodiment, the first variation of the engine torque = the first engine torque at this moment – the first engine torque at the previous moment, the first clutch PID torque is calculated by the PID control algorithm according to the engine target speed and the engine speed difference, the engine The target speed is the clutch speed plus the slippage difference, and the slippage difference is the calibration value, generally between 20 and 70rpm. The engine speed is measured by the speed sensor, and the engine torque is obtained by the Controller Area Network (CAN) signal. The first total torque of the clutch = the first total torque of the clutch at the last moment + the first variation of the engine torque * the first torque coefficient + the first torque of the clutch PID; wherein, the first torque coefficient is a calibration value, generally in the range of 0.5 to 1.

Optionally, the coasting downshift control operation further includes: calculating a second variation in engine torque; calculating a second clutch PID torque; and calculating a second total clutch torque according to the second variation in engine torque and the second clutch PID torque.

In one embodiment, the second variation of the engine torque = the second engine torque at this moment - the second engine torque at the previous moment, and the second clutch PID torque is calculated according to the target engine speed and the difference between the engine speeds. In one embodiment, the second total torque of the clutch=the second total torque of the clutch at the previous moment+the second variation of the engine torque*the second torque coefficient+the second torque of the clutch PID. Among them, the second torque coefficient is a calibration value, generally between 0.5 and 1.

Optionally, the first coefficient=first set time/total time for simultaneous control of rotational speed and torque, wherein the first set time is the duration of simultaneous control of rotational speed and torque.

In one embodiment, the first set time is the duration from the start time of the simultaneous control of the rotational speed and torque to the current time of the simultaneous control of the rotational speed and torque. The first set time can be obtained through system timing, and the first set time increases as the number of periods of the system timing cycle increases. Exemplarily, one timing cycle of the system is 10ms, and the speed and torque are controlled simultaneously for two cycles. Then the first set time is 20ms. The total time of the simultaneous control phase of speed and torque is obtained by calibration, generally 0.1 to 1s.

Optionally, the second coefficient=second set time/total time of coasting downshift torque exchange; wherein, the second set time is the duration of coasting downshift torque exchange.

In one embodiment, the second set time is the duration of the simultaneous control of the rotational speed and torque from the start time of the coasting downshift torque exchange to the current time. The second set time can be obtained by system timing, and the second set time increases with the increase of the number of the system timing period. Exemplarily, one timing period of the system is 10ms, and the torque exchange in coasting downshift lasts for two cycle, the second set time is 20ms. The total time of coasting downshift torque exchange is obtained by calibration, which is generally 0.1 to 1 s.

In one embodiment, the power mode is the power state when the engine torque is positive.

Optionally, FIG. 3 is a schematic flowchart of another dual-clutch coasting downshift control method provided by an embodiment of the present application. Referring to FIG. 3 , the dual-clutch coasting downshift control method further includes:

Step 160: Determine whether the duration of the simultaneous control of the rotational speed and the torque exceeds a predetermined value.

Step 170: If the duration of the simultaneous control of the rotational speed and the torque exceeds a predetermined value, perform a conventional power downshift operation.

In one embodiment, after the duration of the simultaneous control of the rotational speed and torque exceeds a predetermined value, the rotational speed of the engine will be increased to be greater than the rotational speed of the low-speed clutch, so as to perform a conventional power downshift operation, which refers to a high-speed clutch. No longer fit with the engine, the low gear clutch is fitted with the engine, the engine speed is higher than the speed of the low gear clutch, the engine drives the low gear clutch to rotate, and the low gear clutch drives the whole vehicle.

Optionally, the throttle limit is 3% to 20%.

In this embodiment, when it is detected that the vehicle is in a power state during the coasting downshift, the conversion from coasting downshift to power downshift is performed and the speed and torque are controlled at the same time, and the first torque of the high-speed clutch=max{the first high-speed clutch is set Minimum torque, clutch first total torque * first coefficient}; low-gear clutch first torque = clutch first total torque * (1-first coefficient). In the process of simultaneous control of speed and torque, the torque of the high-speed clutch and the low-speed clutch and the speed of the engine are mainly controlled, so that the speed of the engine is greater than the speed of the low-speed clutch. Since the first torque of the high-speed clutch is not lower than the first minimum torque of the high-speed clutch, it is ensured that the high-speed clutch continues to fit with the engine during the transition from coasting to power downshift. Less than the engine speed, the low-speed clutch speed is greater than the engine speed, the high-speed clutch continues to drive the vehicle, and the low-speed clutch brakes the vehicle. After the engine speed is higher than the low-speed clutch, the low-speed clutch The clutch drives the whole vehicle. By first using the high-speed clutch and the low-speed clutch in conjunction with the low-speed clutch during the shifting process, it is possible to avoid the shifting inconsistency caused by stepping on the accelerator when shifting directly to the low-speed clutch. Smooth, improve the stability of downshift, improve user experience.

Claims

A dual-clutch coasting downshift control method, comprising:

Determine whether the clutch is in the oil-filling stage when the vehicle is coasting and downshifting;

When the clutch is not in the oil-filling stage, detecting whether the accelerator opening is greater than the accelerator limit;

In the case that the accelerator opening degree is greater than the accelerator limit value, continue to determine whether the power mode of the vehicle is a power state;

In the case where the power mode of the vehicle is the power state, an operation of shifting from coasting downshift to power downshift with simultaneous control of rotational speed and torque is performed; wherein, when shifting from coasting downshift to power downshift with simultaneous rotational speed and torque In the case of control, set the first torque of the high-speed clutch = the maximum value max {the first minimum torque of the high-speed clutch, the first total torque of the clutch * the first coefficient}, the first torque of the low-speed clutch = the first total torque of the clutch * (1-first coefficient); the first coefficient is greater than zero and less than or equal to 1, and the first coefficient gradually increases to 1 with time.
The method of claim 1, further comprising:

In the case where the power mode of the vehicle is not the power state, a coasting downshift control operation is performed, and whether the power mode is the power state is determined every preset time;

Wherein, the coasting downshift control operation includes judging whether the shifting stage is in the torque exchanging stage; if the shifting stage is in the torque exchanging stage, setting the second torque of the high-gear clutch=max{high-gear clutch second minimum torque, clutch second total torque * (1-second coefficient)}, low-gear clutch second torque = clutch second total torque * second coefficient; the second coefficient is greater than zero and less than or equal to 1, and the second coefficient gradually increases to 1 with time.
3. The method of claim 2, wherein the coast downshift control operation further comprises:

When the shifting stage is not in the torque exchange stage, the second torque of the high-speed clutch is set to be the second minimum torque of the high-speed clutch, and the second torque of the low-speed clutch is set to The clutch second total torque.
The method of claim 1 wherein said performing a coasting downshift to power downshift with simultaneous control of speed and torque comprises:

Calculate the first variation of engine torque;

Calculate the first torque of the clutch proportional-integral-derivative PID;

The first total clutch torque is calculated from the first change in engine torque and the first clutch PID torque.
3. The method of claim 2, wherein the coast downshift control operation further comprises:

calculating a second change in engine torque;

Calculate clutch PID second torque;

The second total clutch torque is calculated based on the second change in engine torque and the second clutch PID torque.
The method according to claim 1, wherein the first coefficient=first set time/total time for simultaneous control of speed and torque, wherein the first set time is the duration of simultaneous control of speed and torque .
2. The method of claim 2, wherein the second coefficient = second set time/total time of coasting downshift torque exchange, wherein the second set time is the duration of coasting downshift torque exchange .
The method according to claim 1, wherein the determining whether the power mode of the vehicle is the power state comprises: judging whether the power mode of the vehicle is the power state according to the torque of the engine.
The method of claim 1, further comprising:

Determine whether the duration of simultaneous control of speed and torque exceeds a predetermined value;

In a case where the duration of the simultaneous control of the rotational speed and the torque exceeds the predetermined value, a normal power downshift operation is performed.
The method of claim 1, wherein the throttle limit value is 3%˜20%.