A control method for improving power response of a vehicle at a very small throttle

Abstract

The application is a control method for improving the power response of a vehicle at a minimum throttle, which uses the high idle speed of an engine in a crawling working condition to keep the minimum throttle within a certain range, so that the vehicle does not immediately enter a starting working condition. According to the current state of the vehicle, whether it is driving or braking, the clutch control module controls the clutch control process, which mainly includes the crawling or starting state, sets the driving torque and idle torque threshold, so as to find the best critical point of the driving and braking state of the vehicle, and improves the power response of the vehicle through the automatic transmission control means, especially in a low temperature environment, which can avoid the engine speed drop of more than 300 rpm or even engine stall.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for DCT automatic transmissions in passenger vehicles, and in particular to a control method for improving vehicle power response at very low throttle. Background Technology

[0002] Dual-clutch automatic transmissions (DCTs) are mechanical automatic transmissions with advantages such as fast shifting speeds and high transmission efficiency. As DCT technology matures, more and more domestic automakers are equipping their vehicles with independently developed DCTs. Structurally, compared to automatic transmissions (ATs) which lack a torque converter, DCTs cannot provide the torque boost that ATs offer during vehicle start-up. Therefore, vehicles equipped with DCTs exhibit inferior power response compared to those with equivalent AT transmissions during initial acceleration.

[0003] By studying information such as accelerator pedal curves, engine torque, engine speed, transmission output shaft speed, braking status, accelerator pedal opening, vehicle speed signal, and gradient, it was found that vehicles equipped with DCT transmissions have slow starting power response, especially in low-temperature environments, where the engine speed drops significantly or even stalls. Improving vehicle power response at extremely low throttle positions remains a technical challenge, and currently, no literature documents any control methods for improving vehicle power response at very low throttle positions. Summary of the Invention

[0004] This invention addresses the technical problems existing in the prior art by creatively devising a control method to improve vehicle power response at extremely low throttle. By using automatic transmission control, it leverages the advantage of the engine's high idle speed during crawling conditions to improve vehicle power response.

[0005] The technical solution adopted to achieve the present invention is: a control method for improving vehicle power response at extremely low throttle, characterized in that it includes the following steps:

[0006] 1) When the vehicle throttle is ≤2%, the transmission controls the vehicle to creep at 0 throttle.

[0007] 2) When the vehicle throttle is greater than 2% and the torque value at the clutch end is less than the torque setting threshold, the transmission control determines that the engine is in a braking state and the transmission control is set to creep control.

[0008] 3) When the vehicle throttle is greater than 2% and the torque value at the clutch end is greater than the torque setting threshold, the transmission control determines that the engine is in driving state, and the transmission control changes the vehicle from crawl control to start control.

[0009] Furthermore, in step 2), the process of determining whether the engine is in a braking state includes the following steps:

[0010] 1) Engine braking idle speed calibration:

[0011] ① When the enable switch is on, the engine idling condition is not considered during the engine braking state determination process; ② When the enable switch is off, the engine is in idling state and the actual engine torque is less than the idling threshold.

[0012] 2) Engine torque drive state determination process under torque limit conditions:

[0013] ① The engine torque is less than the drive torque threshold, and the engine overspeed fuel cut-off indicator is not enabled;

[0014] ② Engine torque < coasting torque limit threshold;

[0015] ③ The current clutch slippage speed difference is less than the threshold. The judgment method is that the speed difference between the engine and the clutch is less than the set threshold or the current engine speed is less than the speed set threshold corresponding to the throttle.

[0016] ④ Does the current engine idling condition meet the braking idling condition?

[0017] ⑤ If either the torque limit condition or the idling state condition is met, the engine enters the braking state.

[0018] Furthermore, in step 3), the engine being in a driving state includes the following steps:

[0019] 1) Engine drive idle speed calibration:

[0020] ① When the enable switch is on, the engine idling condition is not considered during the engine drive state determination process; ② When the enable switch is off, the engine is in a non-idling state and the engine drive torque is greater than the idling threshold.

[0021] 2) Under the premise of meeting the engine-driven idle speed condition, the torque-driven condition must also be met. The process for determining the engine torque-driven state is as follows:

[0022] ① Engine torque > drive torque threshold;

[0023] ② Engine torque > coasting torque limit threshold;

[0024] ③ If the current clutch slippage speed difference is greater than the threshold, the available judgment methods are either the engine speed difference between the engine and the clutch is greater than the set threshold or the current engine speed is greater than the speed set threshold corresponding to the throttle.

[0025] ④ Does the current engine idling condition meet the drive idling condition?

[0026] ⑤ Once the torque drive condition and the idle speed condition are both met, the engine enters the drive state.

[0027] Furthermore, the creep control is as follows: when the vehicle has zero throttle input, the transmission control unit controls the vehicle to enter creep control, with vehicle speed control as the primary objective.

[0028] Furthermore, the starting control is as follows: when the vehicle has throttle input, with engine speed as the target, the transmission control unit performs closed-loop torque control on the vehicle, with engine speed control as the primary target.

[0029] The beneficial effects of the control method for improving vehicle power response at extremely low throttle settings in this invention are reflected in the following aspects:

[0030] A control method for improving vehicle power response at extremely low throttle settings involves maintaining a very low throttle within a certain range, preventing the vehicle from immediately entering a starting state. Depending on whether the vehicle is currently in a driving or braking state, the clutch control module controls the clutch process, which mainly includes crawling and starting states. It sets driving torque and idle torque thresholds to find the optimal critical point for the vehicle's driving and braking states. This method improves vehicle power response through automatic transmission control, with particularly significant effects in low-temperature environments, preventing engine speed from dropping above 300 rpm or even stalling. Attached Figure Description

[0031] Figure 1 This is a flowchart for determining the engine's driving / braking status;

[0032] Figure 2 This is a flowchart of the engine braking status determination process;

[0033] Figure 3 This is a flowchart of the engine drive status determination process. Detailed Implementation

[0034] The following is in conjunction with the appendix Figures 1-3 The present invention will be further described in detail below with reference to specific embodiments. In order to make the purpose, technical solution and advantages of the embodiments clearer, the technical solutions in the embodiments will be clearly and completely described with reference to the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0035] Depending on the vehicle's operating status, the DCT transmission clutch control process mainly includes crawling and starting states. Crawling control is described as follows: when the vehicle has zero throttle input, the transmission control unit controls the vehicle to enter crawling control, with the primary objective of controlling vehicle speed. Starting control is described as follows: when the vehicle has throttle input, with engine speed as the target, the transmission control unit performs closed-loop torque control on the vehicle, with the primary objective of controlling engine speed.

[0036] As attached Figure 1 As shown, a control method for improving vehicle power response at extremely low throttle positions includes the following steps:

[0037] 1) When the vehicle throttle is ≤2%, the transmission controls the vehicle to creep at 0 throttle.

[0038] 2) When the vehicle throttle is greater than 2% and the torque value at the clutch end is less than the torque setting threshold, the transmission control determines that the engine is in a braking state and the transmission control is set to creep control.

[0039] 3) When the vehicle throttle is greater than 2% and the torque value at the clutch end is greater than the torque setting threshold, the transmission control determines that the engine is in driving state, and the transmission control changes the vehicle from crawl control to start control.

[0040] As attached Figure 2 As shown, the process for determining whether the engine is in a braking state includes the following steps:

[0041] 1) Engine braking idle speed status indicator:

[0042] ① When the enable switch is on, the engine idling condition is not considered during the engine braking state determination process; ② When the enable switch is off, the engine is in idling state and the actual engine torque is less than the idling threshold.

[0043] 2) Engine torque drive state determination process under torque limit conditions:

[0044] ① The engine torque is less than the drive torque threshold, and the engine overspeed fuel cut-off indicator is not enabled;

[0045] ② Engine torque < coasting torque limit threshold;

[0046] ③ The current clutch slippage speed difference is less than the threshold. The judgment methods include the difference between the engine speed and the clutch speed being less than the set threshold or the current engine speed being less than the speed set threshold corresponding to the throttle.

[0047] ④ Does the current engine idling condition meet the braking idling condition?

[0048] ⑤ If either the torque limit condition or the idling state condition is met, the engine enters the braking state.

[0049] As attached Figure 3 As shown, the engine being in a driving state includes the following steps:

[0050] 1) Engine drive idle speed status indicator:

[0051] ① When the enable switch is on, the engine idling condition is not considered during the engine drive state determination process; ② When the enable switch is off, the engine is in a non-idling state and the engine drive torque is greater than the idling threshold.

[0052] 2) Under the premise of meeting the engine-driven idle speed condition, the torque-driven condition must also be met. The process for determining the engine torque-driven state is as follows:

[0053] ① Engine torque > drive torque threshold;

[0054] ② Engine torque > coasting torque limit threshold;

[0055] ③ If the current clutch slippage speed difference is greater than the threshold, the judgment methods available include the engine speed difference between the engine and the clutch being greater than the set threshold or the current engine speed being greater than the speed set threshold corresponding to the throttle.

[0056] ④ Does the current engine idling condition meet the drive idling condition?

[0057] ⑤ Once the torque drive condition and the idle speed condition are both met, the engine enters the drive state.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for improving vehicle power response at extremely low throttle, characterized in that, It includes the following steps: 1) When the vehicle throttle is ≤2%, the transmission controls the vehicle to creep at 0 throttle. 2) When the vehicle throttle is greater than 2% and the torque value at the clutch end is less than the torque setting threshold, the transmission control determines that the engine is in a braking state and the transmission control is set to creep control. 3) When the vehicle throttle is greater than 2% and the torque value at the clutch end is greater than the torque setting threshold, the transmission control determines that the engine is in driving state, and the transmission control changes the vehicle from crawl control to start control.

2. The control method for improving vehicle power response at extremely low throttle according to claim 1, characterized in that, In step 2), the process of determining whether the engine is in a braking state includes the following steps: 1) Engine braking idle speed calibration: ① When the enable switch is turned on, the engine idling condition is not considered during the engine braking state determination process. ② The enable switch is closed, the engine is in idle state, and the actual engine torque is less than the idle speed threshold; 2) Engine torque drive state determination process under torque limit conditions: ① The engine torque is less than the drive torque threshold, and the engine overspeed fuel cut-off indicator is not enabled; ② Engine torque < coasting torque limit threshold; ③ The current clutch slippage speed difference is less than the threshold. The judgment method is that the speed difference between the engine and the clutch is less than the set threshold or the current engine speed is less than the speed set threshold corresponding to the throttle. ④ Does the current engine idling condition meet the braking idling condition? ⑤ If either the torque limit condition or the idling state condition is met, the engine enters the braking state.

3. The control method for improving vehicle power response at extremely low throttle according to claim 1, characterized in that, In step 3), the engine being in a driving state includes the following steps: 1) Engine drive idle speed calibration: ① When the enable switch is turned on, the engine idling condition is not considered during the engine drive state determination process. ② The enable switch is closed, the engine is in a non-idling state, and the engine drive torque is greater than the idle speed threshold; 2) Under the premise of meeting the engine-driven idle speed condition, the torque-driven condition must also be met. The process for determining the engine torque-driven state is as follows: ① Engine torque > drive torque threshold; ② Engine torque > coasting torque limit threshold; ③ If the current clutch slippage speed difference is greater than the threshold, the available judgment methods are: the speed difference between the engine and the clutch is greater than the set threshold or the current engine speed is greater than the speed set threshold corresponding to the throttle. ④ Does the current engine idling condition meet the drive idling condition? ⑤ Once the torque drive condition and the idle speed condition are both met, the engine enters the drive state.

4. The control method for improving vehicle power response at extremely low throttle according to claim 1, characterized in that, The aforementioned crawl control is as follows: when the vehicle has zero throttle input, the transmission control unit controls the vehicle to enter crawl control, with vehicle speed control as the primary objective.

5. The control method for improving vehicle power response at extremely low throttle according to claim 1, characterized in that, The aforementioned start-up control is as follows: when the vehicle has throttle input, with engine speed as the target, the transmission control unit performs closed-loop torque control on the vehicle, with engine speed control as the primary target.

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