Piston zero position self-learning method, device and electronic hydraulic brake system

Abstract

The present invention proposes a piston zero position self-learning method, device and electronic hydraulic brake system, which belongs to the field of vehicle braking. The method includes: controlling the motor of the pressure-building cylinder to reverse to control the piston of the pressure-building cylinder to retreat, and obtaining the piston speed in real time; according to the piston speed, when it is confirmed that the piston retreats to the first zero position, the piston retreat control of the pressure-building cylinder ends; and controlling the motor to rotate forward to make the piston rotate forward to the second zero position. In this way, the piston position of the pressure-building cylinder can be calibrated by first retreating the piston of the pressure-building cylinder to the first zero position and then rotating it to the second zero position from the last time the electronic hydraulic brake system is powered off to the next time the electronic hydraulic brake system enters the working mode, thereby improving the control accuracy and braking performance of the electronic hydraulic brake system.

Description

Technical Field

[0001] The present invention relates to the field of vehicle braking, and in particular to a piston zero position self-learning method, device and electronic hydraulic braking system. Background Art

[0002] The integrated electronic hydraulic brake system is an advanced automotive braking technology, which is particularly widely used in the automotive field. The integrated electronic hydraulic brake system generally includes a main brake circuit, an oil pot module, a mechanical brake circuit and a wheel end module. The main brake circuit and the mechanical brake circuit can use the oil provided by the oil pot module to generate hydraulic pressure and transmit it to the wheel end module to control vehicle braking. Among them, the main brake circuit includes a pressure-building cylinder and two PSV valves. The pressure-building cylinder is connected to the first wheel group through the first PSV valve, and the pressure-building cylinder is connected to the second wheel group through the second PSV valve. When the piston of the pressure-building cylinder moves to the bottom of the pressure-building cylinder, hydraulic pressure will be generated under the action of the oil provided by the oil pot module.

[0003] In the integrated electronic hydraulic brake system, the pressure-building accuracy of the pressure-building cylinder piston is the key to the main brake circuit providing accurate main braking force. Since the pressure-building cylinder builds pressure through the oil provided by the oil tank module and the piston displacement, it is difficult to avoid excessive oil, resulting in residual fluid pressure in the main brake circuit after the integrated electronic hydraulic brake system is awakened, which in turn causes the vehicle to drag the brakes, resulting in increased fuel consumption and reduced brake system life, and also affects the braking accuracy after power-on.

[0004] At present, it is difficult for the integrated electronic hydraulic brake system to detect whether there is residual hydraulic pressure in the brake circuit during power-on or power-off self-test. As a result, after entering the driving state, the residual hydraulic pressure can easily lead to low control accuracy of the brake pressure and poor braking performance. Therefore, a solution for calibrating the piston position of the pressure-building cylinder is urgently needed. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a piston zero position self-learning method, device and electronic hydraulic brake system, which can more accurately calibrate the piston position of the pressure building cylinder of the electronic hydraulic brake system to more fully unload the residual hydraulic pressure of the pressure building cylinder.

[0006] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:

[0007] In a first aspect, the present invention provides a piston zero position self-learning method, which is applied to a controller of an electronic hydraulic brake system, wherein the controller is communicatively connected to a motor of a pressure-building cylinder of the electronic hydraulic brake system, and the method comprises:

[0008] Controlling the motor to rotate in reverse to control the piston of the pressure-building cylinder to retreat, and obtaining the piston speed in real time;

[0009] When it is confirmed according to the piston speed that the piston has retreated to the first zero position, the piston retreat control of the pressure building cylinder is terminated;

[0010] When it is determined that the piston of the pressure building cylinder has retracted to the first zero position, the motor is controlled to rotate forward so that the piston rotates forward to the second zero position; wherein, the distance between the second zero position and the bottom of the pressure building cylinder is smaller than the distance between the first zero position and the bottom of the pressure building cylinder, the first zero position is the position of the piston when it reaches the retraction dead point, and the second zero position is the position of the piston when the residual liquid pressure in the system is released.

[0011] Optionally, the step of controlling the motor to reverse to control the piston of the pressure building cylinder to retreat includes:

[0012] Extracting the torque corresponding to the initial moment from the preset torque curve as the target torque; wherein the change characteristic of the torque curve is that the torque at the previous moment is greater than the torque at the next moment;

[0013] Sending a control signal to the motor at the target torque and performing control timing; wherein the control signal is used to instruct the motor to reverse at the target torque;

[0014] When the control timing reaches the preset adjustment time, the torque corresponding to the adjustment time is extracted from the torque curve as the next target torque, and the process returns to execute the steps of sending a control signal to the motor with the target torque and performing control timing.

[0015] Optionally, the controller is also communicatively connected to a speed sensor of the motor;

[0016] The step of ending the piston retreat control of the pressure building cylinder when confirming, based on the piston speed, that the piston retreats to the first zero position comprises:

[0017] When the piston speed collected by the speed sensor is equal to the preset speed lower limit, the timing is reset to zero;

[0018] When the zeroing timing reaches the preset zeroing time, it is determined that the piston has retreated to the first zero position, and the piston retreat control of the pressure building cylinder is ended.

[0019] Optionally, the pressure building cylinder further comprises a screw rod and a nut, the screw rod is provided with a first limiter, and the nut is provided with a second limiter;

[0020] When the first limiting member and the second limiting member are in abutment with each other, the piston is located at the first zero position.

[0021] Optionally, the step of controlling the motor to rotate forward to control the piston to rotate forward to the second zero position includes:

[0022] The motor is controlled to rotate forward with a preset pressure relief compensation value as the target moving distance, so that the piston moves to the second zero position; wherein the pressure relief compensation value is the distance between the first zero position and the second zero position.

[0023] Optionally, the controller is also electrically connected to a PSV valve, a CSV valve and an SSV valve of the electronic hydraulic brake system respectively;

[0024] The method further comprises:

[0025] Detecting whether the power-off self-test of the electronic hydraulic brake system has been completed;

[0026] If yes, the step of controlling the motor to reverse to control the piston of the pressure-building cylinder to retreat and obtaining the piston speed in real time is performed;

[0027] After the step of ending the piston retreat control of the pressure building cylinder when it is confirmed that the piston retreats to the first zero position according to the piston speed, the method further includes:

[0028] The PSV valve, the CSV valve, and the SSV valve are powered off, and the controller is powered off to enter a dormant state.

[0029] Optionally, the method further comprises:

[0030] Detecting whether the electronic hydraulic brake system is awakened;

[0031] If so, the step of controlling the motor to rotate forward to control the piston to rotate forward to the second zero position when it is determined that the piston of the pressure building cylinder has retreated to the first zero position is performed.

[0032] Optionally, the method further comprises:

[0033] Detecting whether the electronic hydraulic brake system is awakened;

[0034] If so, the steps of controlling the motor to reverse to control the piston of the pressure building cylinder to retreat and obtaining the piston speed in real time are performed.

[0035] In a second aspect, the present invention provides a piston zero position self-learning device, which is applied to a controller of an electronic hydraulic brake system, wherein the controller is communicatively connected with a motor of a pressure-building cylinder of the electronic hydraulic brake system, and the piston zero position self-learning device comprises a piston retraction module, a retraction end module and a forward rotation compensation module, so as to execute the piston zero position self-learning method as described in the first aspect;

[0036] The piston retraction module is used to control the motor to reverse, so as to control the piston retraction of the pressure building cylinder, and obtain the piston speed in real time;

[0037] The retraction end module is used to end the piston retraction control of the pressure building cylinder when confirming that the piston has retracted to the first zero position according to the piston speed;

[0038] The forward rotation compensation module is used to control the motor to rotate forward when it is determined that the piston of the pressure building cylinder has retracted to the first zero position, so as to control the piston to rotate forward to the second zero position; wherein, the distance between the second zero position and the bottom of the pressure building cylinder is smaller than the distance between the first zero position and the bottom of the pressure building cylinder, the first zero position is the position of the piston when it reaches the retraction dead point, and the second zero position is the position of the piston when the residual liquid pressure in the system is released.

[0039] In a third aspect, the present invention provides an electronic hydraulic brake system, comprising a controller and a pressure-building cylinder, wherein the pressure-building cylinder comprises a motor and a piston, and the controller is communicatively connected with the motor;

[0040] The controller is used to execute the piston zero position self-learning method as described in the first aspect.

[0041] In a fourth aspect, the present invention provides a control device, comprising a processor and a memory, wherein the memory stores machine executable instructions that can be executed by the processor, and the processor can execute the machine executable instructions to implement the piston zero position self-learning method as described in the first aspect.

[0042] On the fifth side, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the piston zero position self-learning method as described in the first aspect.

[0043] The piston zero position self-learning method, device and electronic hydraulic brake system provided by the embodiment of the present invention include: controlling the motor of the pressure-building cylinder to reverse to control the piston of the pressure-building cylinder to retreat, and obtaining the piston speed in real time; when confirming that the piston retreats to the first zero position according to the piston speed, ending the piston retreat control of the pressure-building cylinder; when determining that the piston of the pressure-building cylinder has retreated to the first zero position, controlling the motor to rotate forward to make the piston rotate forward to the second zero position, and the second zero position is closer to the bottom of the pressure-building cylinder than the first zero position. In this way, the piston position of the pressure-building cylinder can be calibrated by first retreating the piston of the pressure-building cylinder to the first zero position and then rotating to the second zero position from the last time the electronic hydraulic brake system is powered off to the next time the electronic hydraulic brake system enters the working mode, thereby greatly improving the control accuracy and braking performance of the electronic hydraulic brake system.

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A schematic structural diagram of an electronic hydraulic brake system provided by an embodiment of the present invention is shown.

[0047] Figure 2 A block diagram of an electronic device provided by an embodiment of the present invention is shown.

[0048] Figure 3 One of the flow charts of the piston zero position self-learning method provided in an embodiment of the present invention is shown.

[0049] Figure 4 The second flowchart of the piston zero position self-learning method provided in the embodiment of the present invention is shown.

[0050] Figure 5 The third flow chart of the piston zero position self-learning method provided in the embodiment of the present invention is shown.

[0051] Figure 6 Shows Figure 3-Figure 5 Schematic diagram of the process of some sub-steps of step 12.

[0052] Figure 7 Shows Figure 3-Figure 5 Schematic diagram of the process flow of some sub-steps of step 14.

[0053] Figure 8 A schematic structural diagram of a pressure building cylinder provided in an embodiment of the present invention is shown.

[0054] Fig. 9 A block diagram of a piston zero position self-learning device provided in an embodiment of the present invention is shown.

[0055] Explanation of the reference numerals: 10 - electronic hydraulic braking system; 110 - controller; 120 - main braking circuit; 1201 - pressure-building cylinder; 1202 - piston; 1203 - screw rod; 1204 - nut; 1205 - motor; 1206 - pressure-building chamber; 1207 - first limit member; 1208 - second limit member; 130 - oil tank module; 140 - mechanical braking circuit; 150 - wheel end module; 20 - electronic device; 210 - memory; 220 - processor; 230 - communication module; 30 - piston zero position self-learning device; 310 - piston retraction module; 320 - retraction end module; 330 - forward rotation compensation module. DETAILED DESCRIPTION

[0056] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0057] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0058] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0059] The piston zero position self-learning method provided by the embodiment of the present invention can be applied to Figure 1In the electronic hydraulic brake system 10 shown, the electronic hydraulic brake system 10 includes a controller 110, a main brake circuit 120, an oil tank module 130, a mechanical brake circuit 140 and a wheel end module 150. The main brake circuit 120 and the mechanical brake circuit 140 are respectively connected to the oil tank module 130 and the wheel end module 150. The main brake circuit 120 and the mechanical brake circuit 140 can use the oil provided by the oil tank module 130 to generate hydraulic pressure and transmit it to the wheel end module 150 to control vehicle braking.

[0060] The wheel-end module 150 includes a first wheel group and a second wheel group, and the main brake circuit 120 includes a pressure-building cylinder 1201 and two PSV valves. The pressure-building cylinder 1201 is connected to the first wheel group through a first PSV valve, and the pressure-building cylinder 1201 is connected to the second wheel group through a second PSV valve. The mechanical brake circuit 140 includes a brake pedal, a master cylinder, and two CSV valves. The brake pedal is connected to the master cylinder. The master cylinder is connected between the first PSV valve and the first wheel group through the first CSV valve, and the master cylinder is connected between the second PSV valve and the second wheel group through the second CSV valve. The master cylinder is also connected to the oil pot through the SSV valve.

[0061] The controller 110 can communicate with the motor 1205 of the pressure building cylinder 1201, the CSV valve, the PSV valve, the SSV valve and each isolation valve of other modules and devices requiring electrical control through the bus to control the working state of the motor 1205 and the conduction and disconnection of each isolation valve.

[0062] In the power-on state, the PSV valve and the SSV valve are connected, that is, in the open state, and the CSV valve is disconnected and in the closed state. Conversely, in the power-off state, the PSV valve and the SSC valve are disconnected and in the closed state, and the CSV valve is connected and in the open state.

[0063] In addition, the pressure-building cylinder 1201 includes a piston 1202, a pressure-building chamber 1206, a screw rod, a nut and a motor 1205. The output shaft of the motor 1205 is connected to the screw rod, the nut is sleeved on the screw rod and threaded with the screw rod, the piston 1202 is arranged on the nut, and when the motor 1205 drives the screw rod to rotate, the piston 1202 is driven to move in the pressure-building chamber with the cooperation of the nut. The pressure-building chamber 1206 is connected to the oil pot module 130 through the oil circuit, so that when the main brake circuit 120 responds to the braking request, the two PSV valves are in the conducting state, and the piston 1202 is in the process of moving to the bottom of the pressure-building chamber 1206. The pressure-building chamber 1206 extracts the oil in the oil pot module 130 to build pressure to generate hydraulic pressure, and then the pressure-building chamber 1206 transmits the generated hydraulic pressure to the first wheel group and the second wheel group through the two PSV valves respectively, so as to realize the braking demand of the vehicle where the voltage midnight brake system is located.

[0064] When the vehicle in which the electronic hydraulic braking system 10 is located generates a mechanical braking demand, the two CSV valves are de-energized and in an on state, and the pressure building chamber 1206 is in a closed state with the first wheel group and the second wheel group. When the brake pedal is pressed, the master cylinder draws oil from the oil tank module 130 to generate hydraulic pressure, and then transmits the hydraulic pressure to the first wheel group and the second wheel group through the two CSV valves to achieve vehicle braking.

[0065] In order to facilitate the acquisition of the rotation speed of the motor 1205, the moving distance of the piston 1202, etc., the electronic hydraulic braking system 10 may also include a speed sensor and a stroke sensor. The stroke sensor can be arranged on the piston 1202 of the pressure-building cylinder 1201, and the speed sensor can be an encoder electrically connected to the motor 1205, a Hall sensor arranged on the rotor of the motor 1205, or any other sensor that can measure the speed (including the rotational speed) of the motor 1205.

[0066] Here, the controller 110 is also used to implement the piston zero position self-learning method provided in the embodiment of the present invention.

[0067] It should be noted that the controller 110 may be a driving computer, a vehicle-mounted terminal, etc. of the vehicle in which the electronic hydraulic brake system 10 is located, or may be a control device of the electronic hydraulic brake system 10 itself.

[0068] Please refer to Figure 2 , is a block diagram of an electronic device 20, which may be Figure 1 The controller 110 in the electronic hydraulic brake system 10 shown. The electronic device 20 includes a memory 210, a processor 220 and a communication module 230. The memory 210, the processor 220 and the communication module 230 are electrically connected to each other directly or indirectly to achieve data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines.

[0069] The memory 210 is used to store programs or data and can be, but not limited to, a random access memory, a read-only memory, a programmable read-only memory, an erasable read-only memory, an electrically erasable read-only memory, and the like.

[0070] The processor 220 is used to read / write data or programs stored in the memory 210 and execute corresponding functions. For example, Figure 1 In the electronic hydraulic brake system 10 shown, the processor 220 in the controller 110 executes the computer program stored in the memory 210 to implement the piston zero position self-learning method provided in the embodiment of the present invention.

[0071] The communication module 230 is used to establish a communication connection between the electronic device 20 and other communication terminals and electronic control devices through wireless communication such as the Internet, WiFi, Bluetooth, or communication data lines such as buses, and is used to send and receive data. Figure 1 In the electronic hydraulic brake system 10 shown, the controller 110 can receive detection data from each sensor through the communication module 230, and send control signals to each isolation valve.

[0072] It should be understood that Figure 2 The structure shown is only a schematic diagram of the structure of the electronic device 20. The electronic device 20 may also include Figure 2 More or fewer components as shown, or with Figure 2 Different configurations are shown. Figure 2 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0073] Please refer to Figure 3 The piston zero position self-learning method provided in the embodiment of the present invention includes steps 12 to 16. Figure 1 In the electronic hydraulic brake system 10 shown, the controller 110 can Figure 2 The structure shown in , through the processor 220 executing the stored computer program, performs the above steps 12 to 16 to implement the piston zero position self-learning method.

[0074] Step 12, controlling the motor to reverse, so as to control the piston of the pressure-building cylinder to retreat, and obtaining the piston speed in real time.

[0075] Step 14, when it is confirmed according to the piston speed that the piston has retreated to the first zero position, the piston retreat control of the pressure building cylinder is ended.

[0076] Step 16: When it is determined that the piston of the pressure building cylinder has retreated to the first zero position, the motor is controlled to rotate forward so that the piston rotates forward to the second zero position.

[0077] Among them, the distance between the second zero position and the bottom of the pressure building cylinder is smaller than the distance between the first zero position and the bottom of the pressure building cylinder. The first zero position is the position when the piston reaches the retraction dead point (that is, the piston cannot continue to retract), and the second zero position is the position of the piston when the residual liquid pressure in the system is released.

[0078] For the second zero position, the technician can detect the residual liquid pressure in the main brake circuit of the electronic hydraulic brake system when the piston of the pressure-building cylinder returns to the first zero position multiple times in different scenarios or at different times, remove the residual liquid pressure by moving the piston, and record the position of the piston when the residual liquid pressure is completely eliminated as the pressure relief compensation position. In this way, multiple sets of compensation values ​​can be obtained, and the compensation data include the residual liquid pressure and the corresponding pressure relief compensation position. Furthermore, data fitting can be performed based on the multiple sets of residual liquid pressures and pressure relief compensation positions to obtain a pressure relief compensation value, and the second zero position can be determined by the pressure relief compensation value. It can also be based on the multiple sets of residual liquid pressures and pressure relief compensation positions. Machine learning training is performed to generate a pressure relief compensation value to determine the second zero position. In addition, the second zero position can also be a fixed value set by the technician based on experience. The above-mentioned methods of obtaining the second zero position are only examples, and their specific implementation methods are not limited.

[0079] For example, in combination Figure 1 In the electronic hydraulic brake system 10 shown, when it is necessary to release the residual hydraulic pressure in the main brake circuit 120, the controller 110 can fix the speed or change the speed to control the motor 1205 to reverse, so as to control the piston 1202 of the pressure-building cylinder 1201 to retreat in a direction away from the bottom of the pressure-building cylinder 1201, and in this process, the speed sensor of the motor 1205 obtains the speed of the piston 1202 in real time. Here, since the piston 1202 is driven by the screw rod of the motor 1205, the obtained speed of the piston 1202 can be the rotation speed of the screw rod, the rotation speed of the rotor of the motor 1205, the displacement speed of the screw rod or the displacement speed of the piston 1202, etc., which is not limited.

[0080] While controlling the motor 1205 to reverse, the controller 110 confirms in real time whether the piston 1202 has retreated to the first zero position based on the obtained speed of the piston 1202. If so, the control of the retreat of the piston 1202 of the pressure-building cylinder 1201 ends. Then, when it is determined that the piston 1202 of the pressure-building cylinder 1201 has retreated to the first zero position, the controller 110 then controls the motor 1205 to rotate forward so that the piston 1202 rotates forward to the second zero position. In this way, the piston 1202 is first retreated to the first zero position to unload most of the residual hydraulic pressure, and then rotated to the second zero position to unload the remaining small amount of hydraulic pressure, so as to achieve the effect of returning the hydraulic pressure of the main brake circuit 120 to zero.

[0081] In the above-mentioned piston 1202 zero position self-learning method, the piston position of the pressure-building cylinder can be calibrated by first retracting the piston of the pressure-building cylinder to the first zero position and then rotating it to the second zero position from the last time the electronic hydraulic brake system is powered off to the next time the electronic hydraulic brake system enters the working mode, thereby greatly improving the control accuracy and braking performance of the electronic hydraulic brake system. In addition, whether the first zero position is returned is confirmed based on the piston speed, so there is no need to add additional position monitoring devices, reducing the cost of pressure relief calibration.

[0082] Among them, the time period for executing the above steps 12 to 16 can be flexibly set. For example, it can be before the electronic hydraulic braking system or the integrated electronic hydraulic braking system is powered off, or it can be after the electronic hydraulic braking system or the integrated electronic hydraulic braking system is powered on and awakened. The above time period is only an example and its setting is not limited.

[0083] When the piston 1202 of the pressure-building cylinder 1201 retreats to the first zero position, since the piston 1202 moves away from the bottom of the pressure-building cylinder 1201, that is, it is getting closer and closer to the bottom of the pressure-building cylinder 1201 (that is, the top of the pressure-building cylinder 1201), it is very easy for the piston 1202 or the screw rod to hit the nut and generate loud noise. In order to reduce the noise generated by zero-position self-learning after power-on wake-up and to improve the user's comfort, the pressure relief calibration of the piston 1202 of the pressure-building cylinder 1201 retreating to the first zero position can be performed after the electronic hydraulic brake system 10 or the integrated electronic hydraulic brake system completes the power-off self-test and before the power is turned off and into sleep mode. For example, refer to Figure 4 The piston zero position self-learning method may further include step 11.

[0084] Step 11A, detecting whether the power-off self-test of the electronic hydraulic brake system has been completed.

[0085] If yes, go to step 12.

[0086] Here, after the power-off self-test is completed, the controller can automatically generate an instruction indicating the end of the power-off self-test, and the controller can detect whether the instruction exists to determine whether the power-off self-test is completed. It can also be other detection methods, which are not limited in this embodiment. In addition, after step 14 and before step 16, the piston zero position self-learning method also includes step 15A, that is, the step of controlling the electronic hydraulic brake system to enter a dormant state.

[0087] Step 15A, controlling the PSV valve, the CSV valve, and the SSV valve to be powered off, and controlling the controller to be powered off to enter a dormant state.

[0088] Through the above steps 11A to 15A, after the power-off self-test is completed, that is, when there is no one in the car or someone is getting off the car, the electronic hydraulic brake system will execute the pressure relief calibration function of returning the piston to the first zero position, thereby reducing the loud noise generated by the piston or screw rod hitting the nut to a certain extent and improving the use comfort.

[0089] Through the above steps 11A to 15A, after the electronic hydraulic brake system or the integrated electronic hydraulic brake system completes the power-off self-test and before power-off sleep, the piston of the pressure-building cylinder is retracted to the first zero position for pressure relief calibration. In order to make the electronic hydraulic brake system have high control accuracy and high braking performance after entering the working mode next time, after the electronic hydraulic brake system or the integrated electronic hydraulic brake system is powered on and awakened, and before entering the working mode, the piston of the pressure-building cylinder is rotated to the second zero position for pressure relief calibration. For example, please refer to Figure 4 The piston zero position self-learning method may further include step 15B.

[0090] Step 15B, detecting whether the electronic hydraulic brake system is awakened.

[0091] If yes, then execute step 16. In step 15, the controller may generate an instruction indicating that the electronic hydraulic brake system is awakened after confirming that it is awakened, so it is possible to detect whether the instruction exists to determine whether it is awakened. Other detection methods may also be used, which are not limited in this embodiment.

[0092] Through the above-mentioned step 15B, before powering off and entering sleep mode, the piston of the pressure-building cylinder is returned to the first zero position. After each power-on wake-up, the piston of the pressure-building cylinder is first moved to the second zero position through steps 15B and 16 to calibrate the hydraulic pressure by completely eliminating the residual hydraulic pressure, thereby ensuring that there is no influence of residual hydraulic pressure after the electronic hydraulic brake system enters the working mode, so as to improve the control accuracy and braking performance.

[0093] In addition, the pressure relief calibration function of the piston zero position self-learning can also be set after each power-on wake-up of the electronic hydraulic brake system, and enter the working mode after the pressure relief calibration is completed. Figure 5 , the piston zero position self-learning method also includes step 11B.

[0094] Step 11B, detecting whether the electronic hydraulic brake system is awakened.

[0095] If yes, go to step 12.

[0096] By executing steps 11B to 16, after each power-on wake-up, the piston position of the pressure building cylinder is calibrated by first returning the piston of the pressure building cylinder to the first zero position and then rotating it to the second zero position, thereby realizing hydraulic pressure calibration before entering the working mode and eliminating the influence of residual hydraulic pressure, thereby greatly improving the control accuracy and braking performance of the electronic hydraulic brake system.

[0097] In order to further reduce the noise during the period when the piston retreats to the first zero position and protect the pressure-building cylinder, a slow retreat concept is introduced in the process of controlling the motor to reverse in step 12 to reduce the impact force and impact noise when the piston or the screw hits the nut. Figure 6 , step 12 may include steps 121 to 125.

[0098] Step 121 , extracting the torque corresponding to the initial moment from the preset torque curve as the target torque.

[0099] The change characteristic of the torque curve is that the torque at the previous moment is greater than the torque at the next moment. It can also be understood that the torque curve is a curve in which the torque decreases according to a fixed change amount, that is, the torque curve is a curve in which the torque gradually decreases. As time goes by, the torque gradually decreases. In addition, the setting of the torque curve can be flexibly selected. For example, after setting at least the maximum torque and the minimum torque, the torque curve can be fitted by curve fitting or machine learning training. It can also be drawn by manually setting multiple torques.

[0100] In addition, the piston speed corresponding to the maximum torque (i.e., initial torque) in the torque curve is less than the upper speed limit. For example, if the upper speed limit is 10 mm / s, the piston speed corresponding to the maximum torque in the torque curve is less than 10 mm / s. Thus, the piston speed is prevented from being too high and reaching the first zero position before the speed decreases, thereby preventing collision and reducing noise.

[0101] Step 123, sending a control signal to the motor with the target torque and performing control timing.

[0102] The control signal is used to instruct the motor to reverse at a target torque.

[0103] Step 125 , when the control timing reaches the preset adjustment time, the torque corresponding to the adjustment time is extracted from the torque curve as the next target torque.

[0104] Here, after step 125 , the process returns to step 123 .

[0105] Through the above steps 121 to 125, the torque of the motor is dynamically adjusted according to the torque curve, so that the motor drives the piston with a slowly decreasing torque to slowly reduce the speed of the piston. As a result, when the first zero position is reached, the speed of the piston is very small or even zero, so as to avoid collision, greatly reduce noise, and protect the piston and the pressure building cylinder.

[0106] Considering that before each power-off, if the hydraulic pressure established in the main brake circuit is different, the piston is located at a different position. At this time, no matter what position the piston is in, if the same initial torque is used to control the motor to reverse and retreat to the first zero position, if the position of the piston before retreat is close to the first zero position, it is very easy for the piston to hit the first zero position because it still has a large speed.

[0107] In order to ensure that the piston does not collide when retreating, a corresponding hydraulic pressure is set for each torque on the torque curve. Therefore, in step 121, the last hydraulic pressure established by the pressure-building cylinder can be extracted, and the torque corresponding to the hydraulic pressure can be extracted from the torque curve, and the torque is used as the first target torque, and the moment corresponding to the torque is used as the initial retreat moment.

[0108] In order to further improve the accuracy of the first target torque of rollback, a corresponding piston position can be set for each torque on the torque curve, and the speed sensor of the motor can be set as a photoelectric sensor. Thus, the photoelectric sensor is used to measure the piston position before rollback, and the torque corresponding to the piston position is extracted from the torque curve. This torque is used as the first target torque, and the moment corresponding to the torque is used as the initial rollback moment.

[0109] It should be noted that the above method of determining the first target torque of the motor is only an example, and the implementation method thereof is not limited in this embodiment.

[0110] In the process of executing the above steps 121 to 125 to control the piston to retreat to the first zero position, in step 14, the method of confirming whether the piston retreats to the first zero position can be flexibly set. For example, the piston position can be collected in real time by a sensor. When the piston position is consistent with the first zero position, it is confirmed that the piston has reached the first zero position. The displacement distance of the piston can also be collected by a sensor. When the sum of the displacement distance of the piston and the initial position of the piston is consistent with the first zero position, it is confirmed that the piston has reached the first zero position. The above method is only an example, and its specific implementation method is not limited.

[0111] In order to quickly and accurately determine whether the piston has retreated to the first zero position, the idea of ​​using the piston speed collected by a speed sensor connected to or arranged on the motor to determine whether the piston has retreated to the first zero position is introduced in step 14. Figure 7 , step 14 may include steps 141 to 143.

[0112] Step 141, when the piston speed collected by the speed sensor is equal to the preset speed lower limit, the timing is reset to zero.

[0113] Step 143: When the zeroing timer reaches the preset zeroing time, it is determined that the piston has retreated to the first zero position, and the piston retreat control of the pressure building cylinder is ended.

[0114] In the above steps 141 to 143, the lower speed limit value and the corresponding zeroing time can be values ​​determined after data fitting based on a large amount of historical piston retraction data, or can be values ​​determined based on calibration tests by technicians, or can be values ​​set based on experience, and the determination method is not limited.

[0115] In addition, the zero return time varies with the change of the speed lower limit. For example, when the speed lower limit is 0.2mm / s, the zero return time can be 0.2ms. When the speed lower limit becomes 0.3mm / s, the zero return time increases to 0.4ms. It should be noted that the above speed lower limit and zero return time are only examples. The values ​​will be different when the performance of the integrated electronic hydraulic brake system, pressure cylinder or motor is different, and can be adaptively adjusted in actual scenarios.

[0116] Considering that the performance of the integrated electronic hydraulic brake system, pressure-building cylinder or motor varies with the length of time it is used, coupled with errors and other reasons, the accuracy of the original lower speed limit and zero return time may deteriorate. Therefore, in order to ensure that the piston can reach the first zero position and avoid overadjustment, a first zero position limit mechanism is introduced on the screw rod and nut of the pressure-building cylinder. Figure 8 The pressure building cylinder 1201 further includes a screw rod 1203 and a nut 1204 . The screw rod 1203 is provided with a first limit member 1207 , and the nut 1204 is provided with a second limit member 1208 .

[0117] When the first limiting member 1207 and the second limiting member 1208 are in contact with each other, the piston 1202 is located at the first zero position.

[0118] Among them, the shape and size of the first limit member 1207 and the second limit member 1208 can be flexibly set. For example, the first limit member 1207 can be a polymorphic piece arranged on the screw rod 1203, and the second limit member 1208 can be a boss arranged on the nut 1204. When the piston 1202 reaches the first zero position, the boss is embedded and fixed with the polymorphic piece.

[0119] In addition, the first limit member 1207 and the second limit member 1208 can also be baffles. As the motor 1205 drives the screw rod 1203 to rotate, the nut 1204 will move along the length direction of the screw rod 1203. When the nut 1204 is close to the screw rod 1203, the first limit member 1207 and the second limit member 1208 abut against each other, and the nut 1204 is difficult to move, so that the piston 1202 is fixed, which means that the piston 1202 reaches the first zero position.

[0120] Through the above structure, the first limit member 1207 and the second limit member 1208 are used to limit the piston 1202 from moving further after reaching the first zero position, thereby avoiding overadjustment of the first zero position and improving calibration accuracy.

[0121] Furthermore, in step 16, the preset pressure relief compensation value can be used as the target moving distance, and the motor can be controlled to rotate forward to move the piston to the second zero position.

[0122] Here, the pressure relief compensation value is (equal to) the distance between the first zero position and the second zero position, and the target torque corresponding to the second zero position is 0. It can also be understood that when the piston moves to the second zero position, the current hydraulic pressure of the electronic hydraulic brake system is 0 or almost 0. In addition, the distance between the second zero position and the first zero position is the target moving distance, so that the preset constant torque (i.e., corresponding to a constant piston speed) can be used to control the motor to rotate forward for a preset time, so that the moving distance of the piston is equal to the target moving distance, that is, reaching the second zero position. It can also be that the moving distance of the piston is measured in real time by a photoelectric sensor or other similar sensor on the motor. When the moving distance is equal to the pressure relief compensation value, the motor stops working and the piston reaches the second zero position.

[0123] In addition, the setting of the pressure relief compensation value can be flexibly selected. For example, the pressure relief compensation value can be a fixed value set, or it can be a pressure relief compensation value fitted according to historical data. The distance between the second zero position and the first zero position is the pressure relief compensation value, and it is closer to the bottom of the pressure building cylinder 1201 (that is, the bottom of the pressure building bin).

[0124] Taking into account that the accuracy of the motor 1205 and the pressure-building cylinder 1201 changes with the setting of the usage time, therefore, at each preset period, with the preset time period before the current moment as the target time period, multiple pressure relief error values ​​of the first zero position of the pressure-building cylinder 1201 removing the residual hydraulic pressure within the target time period can be obtained, and data fitting is performed on the multiple pressure relief error values ​​to obtain the pressure relief compensation value, and the position of the second zero position is determined by the pressure relief compensation value.

[0125] It can also be that at each preset period, multiple pressure relief error values ​​of the first zero position of the pressure-building cylinder 1201 are unloaded from the residual hydraulic pressure in the target pressure relief times before the current moment, and data fitting is performed to obtain a pressure relief compensation value, and the position of the second zero position is determined by the pressure relief compensation value.

[0126] In this way, the second zero position is adaptively adjusted with changes in the performance of the pressure-building cylinder 1201 , the motor 1205 , etc., so as to improve the accuracy of the second zero position, thereby improving the calibration effect, while ensuring the control accuracy and braking performance of the electronic hydraulic brake system 10 .

[0127] Based on the same concept as the above piston zero position self-learning method, refer to Fig. 9 The embodiment of the present invention also provides a piston zero position self-learning device 30, which can be applied Figure 1 The controller 110 of the electronic hydraulic brake system 10 shown includes a piston retraction module 310 , a retraction end module 320 and a positive rotation compensation module 330 .

[0128] The piston retraction module 310 is used to control the motor to reverse, so as to control the piston retraction of the pressure-building cylinder, and obtain the piston speed in real time.

[0129] The retraction end module 320 is used to end the piston retraction control of the pressure building cylinder when confirming that the piston has retracted to the first zero position according to the piston speed.

[0130] The forward rotation compensation module 330 is used to control the motor to rotate forward when it is determined that the piston of the pressure building cylinder has retreated to the first zero position, so as to control the piston to rotate forward to the second zero position.

[0131] Among them, the distance between the second zero position and the bottom of the pressure building cylinder is smaller than the distance between the first zero position and the bottom of the pressure building cylinder. The first zero position is the position of the piston when it reaches the retraction dead point, and the second zero position is the position of the piston when the residual liquid pressure in the system is released.

[0132] Furthermore, it also includes a power-off detection module, a sleep module and a wake-up detection module.

[0133] The power-off detection module is used to detect whether the power-off self-test of the electronic hydraulic brake system 10 has been completed.

[0134] The sleep module is used to control the PSV valve, the CSV valve and the SSV valve to be powered off, and to control the controller to be powered off so as to enter a sleep state.

[0135] The wake-up detection module is used to detect whether the electronic hydraulic brake system 10 is awakened.

[0136] In the above-mentioned piston zero position self-learning device 30, through the coordinated action of the piston retraction module 310, the retraction end module 320 and the forward rotation compensation module 330, the piston position of the pressure building cylinder can be calibrated by first retracting the piston of the pressure building cylinder to a first zero position and then rotating it to a second zero position from the time the last electronic hydraulic braking system is powered off to the time the next electronic hydraulic braking system 10 enters the working mode, thereby greatly improving the control accuracy and braking performance of the electronic hydraulic braking system.

[0137] For the specific implementation and effect of the piston zero-position self-learning device 30, please refer to the description of the implementation of the piston zero-position self-learning method above. For example, for the specific implementation and effect of the piston retraction module 310, please refer to the description of the relevant content of step 12 above, for the specific implementation and effect of the retraction end module 320, please refer to the description of the relevant content of step 14 above, and for the specific implementation and effect of the forward rotation compensation module 330, please refer to the description of the relevant content of step 16 above, which will not be repeated here.

[0138] In addition, each module in the piston zero position self-learning device 30 can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of the processor 220 in the electronic device 20 in the form of hardware, or can be stored in the memory 210 of the electronic device 20 in the form of software, so that the processor 220 can call and execute the operations corresponding to each module to implement the piston zero position self-learning method provided above.

[0139] Based on the same inventive concept as the above-mentioned piston zero-position self-learning method, an embodiment of the present invention also provides an electronic device 20, including a processor 220 and a memory 210, the memory 210 stores a computer program that can be executed by the processor 220, and the processor 220 can execute the computer program to implement the piston zero-position self-learning method proposed in the embodiment of the present invention.

[0140] The embodiment of the present invention further provides a storage medium on which a computer program is stored. When the computer program is executed by the processor 220, the piston zero position self-learning method proposed in the embodiment of the present invention is implemented.

[0141] In addition, an embodiment of the present invention further provides a computer program product, which includes computer instructions, wherein when the computer instructions are executed by the processor 220, the piston zero position self-learning method proposed in the embodiment of the present invention is implemented.

[0142] Based on the same concept as the piston zero position self-learning method, refer to Figure 1 The embodiment of the present invention further provides an electronic hydraulic brake system 10, including a controller 110 and a pressure-building cylinder 1201, the pressure-building cylinder 1201 includes a motor 1205 and a piston 1202, and the controller 110 is communicatively connected with the motor 1205.

[0143] The controller 110 is used to execute the piston zero position self-learning method provided above.

[0144] Here, the electronic hydraulic brake system 10 may be an integrated electronic hydraulic brake system, and may be a brake system for a transportation vehicle such as an electric vehicle or a hybrid vehicle.

[0145] In summary, the piston zero position self-learning method, device and electronic hydraulic brake system provided by the embodiments of the present invention have at least the following beneficial effects:

[0146] (i) More accurate zero position calibration of the piston of the pressure building cylinder: by first retracting the piston of the pressure building cylinder to the first zero position and then rotating the piston to the second zero position to perform pressure relief calibration compensation, the calibration accuracy of the piston position of the pressure building cylinder is improved;

[0147] (ii) By calibrating the piston position of the pressure-building cylinder, the residual hydraulic pressure is completely removed as much as possible, thereby eliminating the influence of the residual hydraulic pressure on braking and improving the control accuracy and braking performance of the electronic hydraulic brake system;

[0148] (iii) By slowly returning to the first zero position, the noise is greatly reduced and the user experience is improved.

[0149] In several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0150] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0151] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk.

[0152] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A piston zero position self-learning method, characterized in that: A controller applied to an electronic hydraulic brake system, wherein the controller is communicatively connected to a motor of a pressure-building cylinder of the electronic hydraulic brake system, and the method comprises: Controlling the motor to rotate in reverse to control the piston of the pressure-building cylinder to retreat, and obtaining the piston speed in real time; When it is confirmed according to the piston speed that the piston has retreated to the first zero position, the piston retreat control of the pressure building cylinder is terminated; When it is determined that the piston of the pressure-building cylinder has retreated to the first zero position, the motor is controlled to rotate forward so that the piston rotates forward to the second zero position; wherein the distance between the second zero position and the bottom of the pressure-building cylinder is less than the distance between the first zero position and the bottom of the pressure-building cylinder, the first zero position is the position of the piston when it reaches the retreat dead point, and the second zero position is the position of the piston when the residual liquid pressure in the system is released; the step of controlling the motor to rotate reversely to control the retreat of the piston of the pressure-building cylinder includes: Extracting the torque corresponding to the initial moment from the preset torque curve as the target torque; wherein the change characteristic of the torque curve is that the torque at the previous moment is greater than the torque at the next moment; Sending a control signal to the motor at the target torque and performing control timing; wherein the control signal is used to instruct the motor to reverse at the target torque; When the control timing reaches a preset adjustment time, extracting the torque corresponding to the adjustment time from the torque curve as the next target torque, and returning to execute the step of sending a control signal to the motor with the target torque and performing control timing; The step of extracting the torque corresponding to the initial moment from the preset torque curve as the target torque includes: The last hydraulic pressure established by the pressure-building cylinder is extracted, and the torque corresponding to the hydraulic pressure is extracted from the torque curve. The torque is used as the first target torque, and the moment corresponding to the torque is used as the initial retraction moment.

2. The piston zero position self-learning method according to claim 1, characterized in that: The controller is also in communication connection with a speed sensor of the motor; The step of ending the piston retreat control of the pressure building cylinder when confirming, based on the piston speed, that the piston retreats to the first zero position comprises: When the piston speed collected by the speed sensor is equal to the preset speed lower limit, the timing is reset to zero; When the zeroing timing reaches the preset zeroing time, it is determined that the piston has retreated to the first zero position, and the piston retreat control of the pressure building cylinder is ended.

3. The piston zero position self-learning method according to claim 2, characterized in that: The pressure building cylinder further comprises a screw rod and a nut, the screw rod is provided with a first limiter, and the nut is provided with a second limiter; When the first limiting member and the second limiting member are in abutment with each other, the piston is located at the first zero position.

4. The piston zero position self-learning method according to claim 1, characterized in that: The step of controlling the motor to rotate forward to control the piston to rotate forward to the second zero position comprises: The motor is controlled to rotate forward with a preset pressure relief compensation value as the target moving distance, so that the piston moves to the second zero position; wherein the pressure relief compensation value is the distance between the first zero position and the second zero position.

5. The piston zero position self-learning method according to claim 1, characterized in that: The controller is also electrically connected to the PSV valve, CSV valve and SSV valve of the electronic hydraulic brake system respectively; The method further comprises: Detecting whether the power-off self-test of the electronic hydraulic brake system has been completed; If yes, the step of controlling the motor to reverse to control the piston of the pressure-building cylinder to retreat and obtaining the piston speed in real time is performed; After the step of ending the piston retreat control of the pressure building cylinder when it is confirmed that the piston retreats to the first zero position according to the piston speed, the method further includes: The PSV valve, the CSV valve, and the SSV valve are powered off, and the controller is powered off to enter a dormant state.

6. The piston zero position self-learning method according to claim 5, characterized in that: The method further comprises: Detecting whether the electronic hydraulic brake system is awakened; If so, the step of controlling the motor to rotate forward to control the piston to rotate forward to the second zero position when it is determined that the piston of the pressure building cylinder has retreated to the first zero position is performed.

7. The piston zero position self-learning method according to claim 1, characterized in that: The method further comprises: Detecting whether the electronic hydraulic brake system is awakened; If so, the steps of controlling the motor to reverse to control the piston of the pressure building cylinder to retreat and obtaining the piston speed in real time are performed.

8. A piston zero position self-learning device, characterized in that: A controller applied to an electronic hydraulic brake system, the controller being in communication connection with a motor of a pressure-building cylinder of the electronic hydraulic brake system, the piston zero position self-learning device comprising a piston retraction module, a retraction end module and a forward rotation compensation module, so as to execute the piston zero position self-learning method as claimed in any one of claims 1 to 7; The piston retraction module is used to control the motor to reverse, so as to control the piston retraction of the pressure building cylinder, and obtain the piston speed in real time; The retraction end module is used to end the piston retraction control of the pressure building cylinder when confirming that the piston has retracted to the first zero position according to the piston speed; The forward rotation compensation module is used to control the motor to rotate forward when it is determined that the piston of the pressure building cylinder has retracted to the first zero position, so as to control the piston to rotate forward to the second zero position; wherein, the distance between the second zero position and the bottom of the pressure building cylinder is smaller than the distance between the first zero position and the bottom of the pressure building cylinder, the first zero position is the position of the piston when it reaches the retraction dead point, and the second zero position is the position of the piston when the residual liquid pressure in the system is released.

9. An electronic hydraulic brake system, characterized in that: It includes a controller and a pressure-building cylinder, the pressure-building cylinder includes a motor and a piston, and the controller is in communication connection with the motor; The controller is used to execute the piston zero position self-learning method as described in any one of claims 1 to 7.

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