Automatic transmission anti-flameout control method

Abstract

The application discloses an automatic gearbox anti-flameout control method, which calculates an anti-flameout self-help rotating speed by monitoring signals such as engine rotating speed and engine idling rotating speed, combining with a predetermined bottom line rotating speed and processing time, compares the anti-flameout self-help rotating speed with the engine rotating speed and the idling rotating speed, identifies the possible flameout risk of the engine in advance, triggers the anti-flameout self-help function to activate in the first time, makes the TCU enter an anti-flameout processing mode in a short time, controls the clutch to cut off power transmission, and avoids the flameout caused by the non-expected transmission torque of the gearbox leading to the excessive engine load. The application can be applied to any working condition in the vehicle driving process, effectively identifies the triggering time of the anti-flameout function, timely cuts off the torque transmission between the engine and the gearbox, thereby reducing the vehicle flameout risk, avoiding the uncontrollable danger of the vehicle caused by the flameout, and even avoiding the personal harm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile gearbox control, and in particular to an automatic gearbox anti-stall control method. BACKGROUND

[0002] When an AMT automatic gearbox is matched with a commercial vehicle or a passenger vehicle, the problem of stall is a relatively serious and unacceptable problem, especially abnormal stall during driving, which can bring great danger to the driver. Therefore, in order to further avoid the risk of stall, a safety protection measure needs to be added on the basis of the existing AMT function strategy to avoid the risk of stall as much as possible.

[0003] The existing safety protection measure is to cut off the power transmission between the engine and the gearbox when the engine speed is lower than a certain predetermined speed below the idle speed, so as to avoid engine stall due to the gearbox.

[0004] However, this measure can only cover one stall condition and cannot reasonably and effectively avoid most stall conditions. SUMMARY

[0005] In view of the above, the present application aims to provide an automatic gearbox anti-stall control method to solve the aforementioned technical problems.

[0006] The technical solution adopted by the present application is as follows:

[0007] The present application provides an automatic gearbox anti-stall control method, which comprises:

[0008] An engine bottom line speed and an anti-stall processing time are preset, the engine bottom line speed is a calibrated lower limit speed of opening the clutch, and the anti-stall processing time is a calibrated clutch pressure relief time;

[0009] During vehicle operation, the engine speed is monitored in real time;

[0010] The current engine speed gradient is obtained using the engine speed;

[0011] Based on the engine bottom line speed, the engine speed gradient and the anti-stall processing time, the anti-stall self-rescue speed at the current time is calculated in real time;

[0012] The anti-stall self-rescue speed, the engine speed at the current time and the predetermined engine idle speed are compared;

[0013] According to the comparison result, it is determined whether to activate the preset anti-stall trigger flag;

[0014] When it is determined that the misfire trigger flag is activated, a misfire processing function is executed within a preset time to control the clutch to cut off power transmission.

[0015] In at least one possible implementation, the calculating the misfire self-rescue speed at the current time comprises:

[0016] The initial misfire self-rescue speed is calculated according to the following formula: initial misfire self-rescue speed = engine bottom line speed + current engine speed gradient × misfire processing time;

[0017] The target misfire self-rescue speed is obtained by multiplying a preset compensation factor with the initial misfire self-rescue speed.

[0018] In at least one possible implementation, the way of obtaining the compensation factor comprises:

[0019] The transmission oil temperature and the vehicle speed at the current time are obtained in real time;

[0020] A pre-calibrated misfire compensation value data table related to the transmission oil temperature and the vehicle speed is queried to obtain a compensation coefficient represented by a numerical value as the compensation factor.

[0021] In at least one possible implementation, the determining whether to activate the preset misfire trigger flag according to the comparison result comprises:

[0022] If the engine speed at the current time is greater than the engine idle speed, and the misfire self-rescue speed at the current time is greater than the engine speed at the current time, it is determined that the misfire trigger flag is activated; and,

[0023] If the engine speed at the current time is less than the engine idle speed, and the misfire self-rescue speed at the current time is greater than the engine speed at the current time, it is determined that the misfire trigger flag is activated.

[0024] In at least one possible implementation, the determining whether to activate the preset misfire trigger flag according to the comparison result specifically comprises:

[0025] If the engine speed at the current time is greater than the engine idle speed, and the misfire self-rescue speed at the current time is greater than the engine speed at the current time, the misfire trigger flag is activated after a preset fault tolerance time is exceeded;

[0026] If the engine speed at the current time is less than the engine idle speed, and the misfire self-rescue speed at the current time is greater than the engine speed at the current time, the misfire trigger flag is directly activated.

[0027] In at least one possible implementation, the executing the misfire processing function comprises:

[0028] The clutch expected pressure is released and set to 0;

[0029] When the pressure is released below the Kiss Point, it is determined that the anti-stall processing function is completed.

[0030] In at least one possible implementation, the control method further comprises:

[0031] After the anti-stall processing function is completed, the engine speed state is continuously monitored;

[0032] Only when the engine speed is no longer decreasing and rises to the engine idle speed, the anti-stall self-rescue function is triggered, and the normal working mode of the transmission is executed.

[0033] The main design concept of the present application is that by monitoring the engine speed, the engine idle speed, the clutch torque signal, and combining the established bottom line speed and processing time, the anti-stall self-rescue speed is calculated, the anti-stall self-rescue speed is compared with the aforementioned speed and idle speed of the engine, the possible risk of engine stall is identified in advance, the anti-stall self-rescue function is activated in the first time, the TCU enters the anti-stall processing mode in a short time, the clutch is cut off to avoid the stall condition caused by the excessive load of the engine due to the unexpected torque of the transmission. The present application avoids the mis-triggering of the anti-stall processing function, which affects the driving experience, and effectively avoids the real risk of stall. The anti-stall function is the bottom function of vehicle stall protection, i.e. the last line of defense. The present application can be applied to any working condition during vehicle driving, the trigger timing of the anti-stall function is effectively identified, and the torque transmission between the engine and the transmission is cut off in time, thereby reducing the risk of vehicle stall and avoiding the uncontrollable danger of vehicle stall and even personal harm. BRIEF DESCRIPTION OF DRAWINGS

[0034] To make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described below with reference to the drawings, in which:

[0035] Figure 1 A flowchart of the automatic transmission anti-stall control method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0036] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, in which the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.

[0037] The present application proposes an embodiment of an automatic transmission anti-stall control method, specifically, as shown inFigure 1 The method comprises the following steps:

[0038] Step S1, presetting an engine bottom line speed and an anti-stalling processing time, wherein the engine bottom line speed is a calibrated lower limit speed of opening the clutch, and the anti-stalling processing time is a calibrated clutch pressure relief time;

[0039] Step S2, monitoring the engine speed in real time during vehicle operation;

[0040] Step S3, obtaining the current engine speed gradient by using the engine speed;

[0041] Step S4, calculating the anti-stalling self-help speed at the current time in real time based on the engine bottom line speed, in combination with the engine speed gradient and the anti-stalling processing time;

[0042] Step S5, comparing the anti-stalling self-help speed, the engine speed at the current time, and the predetermined engine idle speed;

[0043] Step S6, determining whether to activate the preset anti-stalling trigger flag according to the comparison result;

[0044] Step S7, when it is determined to activate the anti-stalling trigger flag, performing an anti-stalling processing function within a preset time to control the clutch to cut off power transmission.

[0045] Specifically, the calculation of the current anti-stalling self-help speed comprises:

[0046] calculating the initial anti-stalling self-help speed according to the following formula: initial anti-stalling self-help speed = engine bottom line speed + current engine speed gradient × anti-stalling processing time;

[0047] multiplying a preset compensation factor with the initial anti-stalling self-help speed to obtain a target anti-stalling self-help speed.

[0048] Therefore, the way of obtaining the compensation factor comprises:

[0049] obtaining the transmission oil temperature and the vehicle speed at the current time in real time;

[0050] querying a preset anti-stalling compensation value data table related to the transmission oil temperature and the vehicle speed to obtain a compensation coefficient represented by a numerical value as the compensation factor.

[0051] The determination of whether to activate the preset anti-stalling trigger flag according to the comparison result comprises:

[0052] If the engine speed at the current time is greater than the engine idle speed, and the anti-flameout self-help speed at the current time is greater than the engine speed at the current time, it is determined that the anti-flameout trigger flag is activated (set to 1);

[0053] If the engine speed at the current time is less than the engine idle speed, and the anti-flameout self-help speed at the current time is greater than the engine speed at the current time, it is determined that the anti-flameout trigger flag is activated (set to 1);

[0054] If the above conditions are not met, the anti-flameout trigger flag is not activated (set to 0).

[0055] Based on this concept, more preferably, if the engine speed at the current time is greater than the engine idle speed, and the anti-flameout self-help speed at the current time is greater than the engine speed at the current time, and after exceeding the preset fault tolerance time, the anti-flameout trigger flag is activated (set to 1);

[0056] If the engine speed at the current time is less than the engine idle speed, and the anti-flameout self-help speed at the current time is greater than the engine speed at the current time, the anti-flameout trigger flag is directly activated (set to 1).

[0057] The anti-flameout processing function includes:

[0058] The clutch expected pressure is released to 0;

[0059] When the actual pressure is released below the KissPoint point, it is determined that the release is complete, and the anti-flameout processing function is executed.

[0060] In combination with the above various embodiments, generally under normal temperature conditions, when the engine speed is lower than 500 rpm, even if the gearbox immediately cuts off the clutch torque, the engine cannot self-help successfully, and then the engine still stalls. When the engine speed is higher than 500 rpm, the clutch torque is immediately cut off, and the engine can self-help successfully. Therefore, the engine bottom line speed for opening the clutch is defined as 500 rpm.

[0061] Secondly, since the clutch is hydraulically controlled, the release time of the clutch under normal temperature and different pressures is analyzed and counted to obtain the release time under normal temperature. Therefore, the clutch release time is defined as the anti-flameout processing time, which is set to 130 ms in some embodiments of the present application.

[0062] Based on the above engine anti-flameout self-help speed calculation, the self-help speed calculation method is based on the engine bottom line speed, the engine change rate (i.e. gradient) is calculated in real time according to the engine speed, and the self-help speed at the current time is calculated according to the anti-flameout processing time, as follows:

[0063] Flameout self-help rotation speed = engine bottom line rotation speed + current engine change rate x flameout processing time

[0064] In addition, considering that the pressure relief during the flameout processing is affected by the transmission oil temperature, and the flameout mainly occurs at low vehicle speed, that is, affected by the vehicle speed factor. Therefore, on the basis of the above-mentioned self-help rotation speed, the transmission oil temperature and the vehicle speed factor are added as the flameout compensation factor. In actual operation, the flameout compensation factor can be obtained by looking up the corresponding compensation coefficient through a pre-marked two-dimensional table, and then multiplied by the flameout self-help rotation speed calculated at the current time to obtain the final flameout self-help rotation speed. Among them, the transmission oil temperature and the vehicle speed compensation coefficient can be obtained by analyzing and counting the test data in the early stage.

[0065] Then, the calculated flameout self-help rotation speed is compared and analyzed with the actual engine rotation speed and the idle rotation speed at the current time. When the engine rotation speed is greater than the idle rotation speed, the self-help rotation speed is greater than the engine rotation speed, and exceeds the fault tolerance time, the flameout trigger flag is activated and set to 1; When the engine rotation speed is less than the idle rotation speed, the self-help rotation speed is greater than the engine rotation speed, then the flameout trigger flag is directly activated and set to 1; Otherwise, set to 0.

[0066] When the flameout function is activated, the TCU processes first (the aforementioned preset time can be set to the minimum value according to the technical scene, such as milliseconds, 1ms-5ms): the clutch expected pressure is immediately relieved to 0, and when the actual pressure is relieved to below KP and no longer transmits torque, it is determined that the relief is completed, and the flameout processing is completed.

[0067] Finally, it can be supplemented that after the flameout processing function is executed, the flameout self-help function is preferably not directly exited, but the engine rotation speed state is continued to be monitored. Only when the engine rotation speed no longer decreases and rises to the idle rotation speed, it is determined that the engine rotation speed self-help is successful, at this time the flameout self-help function can be triggered to exit, and the normal working mode of the TCU is restored.

[0068] To sum up, the main design concept of the application is that the engine speed, the engine idle speed, and the clutch torque signal are monitored, the bottom line speed and the processing time are combined, the anti-stalling self-help speed is calculated, the anti-stalling self-help speed is compared with the aforementioned speed and the idle speed of the engine, the possible risk of engine stall is identified in advance, the anti-stalling self-help function is activated in the first time, the TCU enters the anti-stalling processing mode in a short time, the clutch is controlled to cut off the power transmission, and the stall condition caused by the excessive load of the engine due to the unexpected torque of the gearbox is avoided. The application avoids the mis-triggering of the anti-stalling processing and affects the driving feeling, and effectively avoids the real risk of stall. The anti-stalling function is the bottom function of the vehicle stall protection, that is, the last line of defense. The application can be applied to any condition during vehicle driving, the triggering time of the anti-stalling function is effectively identified, and the torque transmission between the engine and the gearbox is cut off in time, so as to reduce the risk of vehicle stall and avoid the uncontrollable danger of the vehicle caused by stall and even personal harm.

[0069] In the embodiments of the application, "at least one" refers to one or more, and "multiple" refers to two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which means that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it. "At least one of the following" and the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b and c can mean: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b, and c can be single or multiple.

[0070] The above embodiments according to the drawings illustrate the structure, features and effects of the application, but the above is only a preferred embodiment of the application, and it should be noted that the technical features involved in the above embodiments and preferred modes can be reasonably combined and matched into various equivalent schemes by those skilled in the art without departing from or changing the design idea and technical effects of the application. Therefore, the application is not limited by the drawings shown in the drawings, and any changes or modifications made in accordance with the concept of the application, or equivalent embodiments with equivalent changes, are still within the scope of the application.

Claims

1. A method for preventing engine stall in an automatic transmission, characterized in that, include: The engine's minimum operating speed and anti-stalling time are preset. The engine's minimum operating speed is the calibrated lower limit speed for clutch disengagement, and the anti-stalling time is the calibrated clutch depressurization time. During vehicle operation, engine speed is monitored in real time; The current engine speed gradient is obtained using the engine speed. Based on the engine baseline speed, combined with the engine speed gradient and the anti-shutdown processing time, the anti-shutdown self-rescue speed at the current moment is calculated in real time, including: calculating the initial anti-shutdown self-rescue speed according to the following formula: initial anti-shutdown self-rescue speed = engine baseline speed + current engine speed gradient × anti-shutdown processing time; multiplying the preset compensation factor with the initial anti-shutdown self-rescue speed to obtain the target anti-shutdown self-rescue speed; The engine speed for preventing engine stall, the current engine speed, and the predetermined engine idle speed are compared. Based on the comparison results, determine whether to activate the preset anti-stalling trigger flag, including: if the current engine speed is greater than the engine idle speed and the current anti-stalling self-rescue speed is greater than the current engine speed, then determine to activate the anti-stalling trigger flag, or activate the anti-stalling trigger flag after a preset fault tolerance time has elapsed; and if the current engine speed is less than the engine idle speed and the current anti-stalling self-rescue speed is greater than the current engine speed, then determine to directly activate the anti-stalling trigger flag. When the anti-shutdown trigger flag is activated, the anti-shutdown processing function is executed within a preset time to control the clutch to cut off power transmission.

2. The automatic transmission anti-stalling control method according to claim 1, characterized in that, The methods for obtaining the compensation factor include: Real-time acquisition of transmission oil temperature and vehicle speed; Query the pre-calibrated anti-stalling compensation value data table related to transmission oil temperature and vehicle speed to obtain the compensation coefficient represented by the numerical value as the compensation factor.

3. The automatic transmission anti-stalling control method according to any one of claims 1 to 2, characterized in that, The flameout prevention function includes: Release the desired clutch pressure and set it to 0; When the pressure drops below the Kiss Point, the anti-flameout function is confirmed to have completed.

4. The automatic transmission anti-stalling control method according to claim 3, characterized in that, The control method further includes: After the anti-stalling function has been completed, continue to monitor the engine speed. Only when the engine speed stops decreasing and rises to the engine idle speed will the anti-stalling self-rescue function be deactivated and the normal working mode of the transmission be executed.

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