An Electronic Parking Brake System Control Strategy

Abstract

The present invention provides an electronic parking brake system control strategy, which includes: setting a light clamping current of the motor when the motor performs a clamping operation in the controller of the electronic parking brake system; the light clamping current is the current of the motor when the friction plate of the parking brake actuator just contacts the brake disc; the light clamping current is less than the current when the motor clamps but greater than the current when the motor idles; when the parking brake actuator is in the clamping state and a release instruction is received, if the current clamping current of the motor is less than the light clamping current, then after executing to the light clamping current, then perform electric braking, and immediately respond to the release instruction after the braking ends. The present invention can enable the parking brake actuator to timely change the working state according to the driver's request instruction during the operation of the motor, so as to be able to respond more quickly to the driver's clamping or release request, and thus better meet the driver's driving needs.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle braking systems, and in particular relates to a control strategy for an electronic parking brake system. Background Art

[0002] When the electronic parking brake system (EPB) is working, the current control curve of the motor when the parking brake actuator is released is as follows: Figure 1 As shown in the figure, the current control curve of the motor when the parking brake actuator is clamping is as follows Figure 2 As shown, I: motor current; Irsh: motor inrush current; Iload: motor clamping current; Iidle: motor idling current (no load); Ibrake: motor deceleration current; t: time. When the motor is in Figure 1 Between a and b in Figure 2 When the motor is between A and B in the figure, the motor is in the state adjustment period after the release or clamping action, that is, the motor goes from braking to stopping. At this time, the motor cannot be interrupted and new instructions cannot be executed; when the motor is at b or after point B, the parking brake actuator is in the release or clamping state, and the motor can execute new instructions.

[0003] The state change diagram of the parking brake actuator is as follows Figure 3 As shown, 0x0: Unknown, unknown status; 0x1: ParkApplied, clamped; 0x2: Released, released; 0x3: CompletelyReleased (not shown in the figure), completely released, used for maintenance mode; 0x4: Applying, clamping; 0x5: Releasing. The existing EPB control strategy is that when the motor is in motion, it does not respond to new operation instructions. This makes the motor of the parking brake actuator unable to execute new operation instructions when it is in motion and when adjusting the state after the action. For example, when performing a clamping operation, Figure 3 The motor cannot execute new operation instructions during the c period, and the d period is the state adjustment period of the motor. Figure 2 No new operation instructions can be executed between 0 and B in the figure. Only when the motor is in a non-operating state and the state adjustment is completed, that is, after point B, can new operation instructions be executed, which results in the parking brake actuator being unable to respond quickly to the driver's release or clamping request. Therefore, how to design an electronic parking brake system control strategy so that the parking brake actuator can respond to the driver's request more quickly has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to provide an electronic parking brake system control strategy to solve the above technical problems in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An electronic parking brake system control strategy, which includes:

[0007] An electronic parking brake system control strategy, which includes: setting a light clamping current of the motor when the motor performs a clamping operation in the controller of the electronic parking brake system; the light clamping current is the current of the motor when the friction plate of the parking brake actuator just touches the brake disc; the light clamping current is less than the current when the motor clamps but greater than the current when the motor idles.

[0008] When the parking brake actuator is in the process of clamping and receives a release instruction, if the current clamping current of the motor is less than the light clamping current, then after reaching the light clamping current, the motor performs braking, and after the braking ends, the release instruction is immediately responded to.

[0009] Preferably, if the current clamping current of the motor is less than the target clamping current but greater than the light clamping current, then after completing the current clamping operation, the release instruction is responded to.

[0010] Preferably, the light clamping current is 2.5 A to 3.5 A.

[0011] Preferably, the light clamping current is set to 2 A.

[0012] Preferably, when the parking brake actuator is in the process of releasing or in the released state and receives a clamping instruction, then the current operation is immediately interrupted and the clamping instruction is responded to.

[0013] Preferably, when the clamping or releasing operation of the motor is continuously interrupted more than a set number of times, the motor is calibrated by performing a complete and uninterrupted operation once.

[0014] Preferably, the set number of times is 4 to 6 times.

[0015] Preferably, the set number of times is 5 times.

[0016] The beneficial effects of the present invention are as follows:

[0017] The electronic parking brake system control strategy of the present invention can enable the parking brake actuator to adjust the working state of the motor according to the driver's release request instruction during the process of the motor performing a clamping operation, so that the motor performs a release action. In the prior art, the driver's release request cannot be responded to during the motor clamping action. Therefore, the present invention can enable the motor to respond to the driver's release request more timely during the clamping action, so that the electronic parking brake system can respond to the driver's release request more quickly, and thus can better meet the driving needs of the driver. Brief Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments, and will further elaborate on the specific embodiments of the present invention in conjunction with the drawings. Among them

[0019] Figure 1 is the current control curve when the existing motor performs the release action;

[0020] Figure 2 is the current control curve when the existing motor performs the clamping action;

[0021] Figure 3 is a schematic diagram of the state change of the existing parking brake actuator;

[0022] Figure 4 is a comparison diagram of the current control curve when the motor in the embodiment of the present invention performs the clamping action and the current control curve when the existing motor performs the clamping action;

[0023] Figure 5 is another comparison diagram of the current control curve when the motor in the embodiment of the present invention performs the clamping action and the current control curve when the existing motor performs the clamping action;

[0024] Figure 6 is a comparison diagram of the current control curve when the motor in the embodiment of the present invention performs the release action and the current control curve when the existing motor performs the release action.

[0025] Reference signs in the drawings:

[0026] I, current of the motor; Irsh, inrush current of the motor; Iload, current when the motor is clamping;

[0027] Iidle, current when the motor is idling; Ibrake, current when the motor is decelerating; t, time;

[0028] Iqj, light clamping current. Detailed Embodiments

[0029] To enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the solutions in detail in conjunction with specific embodiments.

[0030] The embodiment of the present invention provides a control strategy for an electronic parking brake system, which includes:

[0031] Set the light clamping current of the motor when the motor performs the clamping operation in the controller of the electronic parking brake system; the light clamping current is the current of the motor when the friction plate of the parking brake actuator just contacts the brake disc; the light clamping current is less than the load current when the motor is turned off but greater than the current when the motor idles.

[0032] When the parking brake actuator is in the clamping state and a release instruction is received, if the current clamping current of the motor is less than the light clamping current, it will be executed until the light clamping current, and then the motor braking will be executed. After the braking is completed, the release instruction will be immediately responded to and the release operation will be executed.

[0033] In a specific embodiment, as Figure 4 shown, at point e, the controller receives a release instruction. At this time, the motor of the parking brake actuator is in the clamping state, and the current clamping current of the motor at point e is less than the light clamping current Iqj. At this time, the controller controls the current clamping current of the motor to execute according to the current control curve of the motor during the original normal clamping action until the current clamping current of the motor reaches the light clamping current, and then the motor braking is executed. After the braking is completed, the release action is performed, that is, the motor braking starts at point f. The period between point f and point g is the state adjustment period of the motor. At point g, the motor can start to execute the release instruction. It can be seen that compared with the prior art in which the motor can only execute the release instruction at point B during the clamping action, the response time of the parking brake actuator is effectively improved.

[0034] The control strategy of the electronic parking brake system provided by the embodiment of the present invention can enable the parking brake actuator to adjust the working state of the motor according to the driver's release request instruction during the clamping operation of the motor, so that the motor performs the release action. In the prior art, the driver's release request cannot be responded to during the clamping action of the motor. Therefore, the present invention can enable the motor to respond to the driver's release request more timely during the clamping action, so that the electronic parking brake system can respond to the driver's release request more quickly, and thus can better meet the driving needs of the driver.

[0035] Further, when the parking brake actuator is in the clamping state and a release instruction is received, if the current clamping current of the motor is less than the target clamping current but greater than the light clamping current, after the current clamping operation is completed, the release instruction will be responded to and the release operation will be executed. In a specific embodiment, as Figure 5As shown, a release instruction is received at point h. At this time, the parking brake actuator is in the clamping state. The current clamping current of the motor at point h is less than the target clamping current but greater than the light clamping current Iqj. At this time, the controller controls the current of the motor to complete the current clamping operation according to the original current control curve of the motor during normal clamping, and then responds to the release instruction to perform the release operation, that is, the motor starts braking at point j. The period between point j and point k is the state adjustment period of the motor. At point k, the motor starts to respond to the release instruction.

[0036] Specifically, the light clamping current is 2.5 A to 3.5 A, that is, the light clamping current can be selected between 2.5 amperes and 3.5 amperes.

[0037] Preferably, the light clamping current is 2 A, that is, the light clamping current is 2 amperes.

[0038] Specifically, when the parking brake actuator is in the releasing or released state and a clamping instruction is received, the controller immediately interrupts the current operation of the motor and responds to the clamping instruction. With this solution, when the motor of the parking brake actuator is performing a release action, according to the driver's clamping request instruction, the release action of the motor can be stopped in time to respond to the clamping request and perform a clamping action. In the prior art, when the motor is performing a release action, it cannot respond to the driver's clamping request. It can be seen that the present invention can respond to the driver's clamping request in time when the motor is performing a release action, so as to better meet the driver's driving needs.

[0039] In a specific embodiment, as Figure 6 shown, a clamping instruction is received at point m. At this time, the parking brake actuator is in the releasing state. When the controller receives the clamping instruction, it immediately interrupts the current release operation of the motor and starts to respond to the clamping instruction, that is, the motor starts braking at point m. The period between m and n is the state adjustment period of the motor. After point n, the motor responds to the clamping instruction. The curve after point n in the figure is the current control curve of the motor clamping operation. Compared with the prior art in which the motor starts to respond to the clamping instruction at point b during the release action, the present invention can enable the parking brake actuator to respond to the driver's clamping instruction faster and more timely.

[0040] Further, when the clamping or release operation of the motor is continuously interrupted more than a set number of times, the motor is calibrated by performing a complete and uninterrupted clamping or release operation. With this solution, after the motor is interrupted during continuous multiple clamping or releasing processes and then a new request instruction is received, the controller will control the motor to perform a complete clamping or release operation, that is, according to the original normal clamping or release operation, such as in the prior art Figure 2 or Figure 1The control motor performs normal clamping or releasing operations without responding to new operation instructions, i.e., request instructions, sent again during this process, so as to confirm the wheel cylinder position and avoid the disorder of the wheel cylinder position caused by the motor operation being interrupted multiple times.

[0041] Specifically, the set number of times is 4 to 6 times, and it can be preferably 5 times.

[0042] The above are only the preferred embodiments of the present invention. It should be noted that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, after reading the content of the present invention, those skilled in the relevant art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. An electronic parking brake system control strategy, characterized in that, It includes: Setting a light clamping current of the motor when the motor performs a clamping operation in the controller of the electronic parking brake system; The light clamping current is the current of the motor when the friction plate of the parking brake actuator just contacts the brake disc; the light clamping current is less than the current when the motor clamps but greater than the current when the motor idles; When the parking brake actuator is in the clamping state and receives a release command, if the current clamping current of the motor is less than the light clamping current, the controller controls the current clamping current of the motor to execute according to the current control curve of the motor during the original normal clamping operation until the current clamping current of the motor reaches the light clamping current, and then performs motor braking. After the braking is completed, the release command is immediately responded to; If the current clamping current of the motor is less than the target clamping current but greater than the light clamping current, after the current clamping operation is completed, the release command is responded to; When the parking brake actuator is in the releasing or released state and receives a clamping command, the current operation is immediately interrupted and the clamping command is responded to.

2. The electronic parking brake system control strategy according to claim 1, wherein The light clamping current is 2.5 A to 3.5 A.

3. The electronic parking brake system control strategy according to claim 1, characterized in that, The light clamping current is set to 2 A.

4. The control strategy of the electronic parking brake system according to claim 1, wherein When the clamping or releasing operation of the motor is continuously interrupted more than the set number of times, the motor is calibrated by performing a complete and uninterrupted operation.

5. The electronic parking brake system control strategy according to claim 4, characterized in that, The set number of times is 4 to 6 times.

6. The control strategy of the electronic parking brake system according to claim 5, characterized in that, The set number of times is 5 times.

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