Control method of locking mechanism of electronic mechanical brake system

Abstract

The invention discloses a control method for a locking mechanism of an electronic mechanical braking system, the locking mechanism comprises an electromagnet and a multi-stage gear transmission mechanism, the locking head of the electromagnet is arranged to be embedded in a locking groove formed in any gear of the multi-stage gear transmission mechanism in a locking state, and the locking head of the electromagnet is arranged to be embedded in a locking groove formed in any gear of the multi-stage gear transmission mechanism. And a plurality of locking grooves are formed in the gear. According to the control method for the locking mechanism of the electronic mechanical braking system, under the condition that the parking locking and releasing functions are met, a position detection mechanism is omitted, parts of the mechanism are simplified, the manufacturing cost is reduced, meanwhile, accurate control over the locking and releasing process is achieved through a control strategy, and the control method is suitable for popularization and application. Noise is reduced; and product reliability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of braking systems. Specifically, the present invention relates to a control method for a locking mechanism of an electromechanical braking system. Background Art

[0002] With the development of automotive electrification, intelligence, and by-wire technology, the level of automated driving of automobiles is getting higher and higher, and the demand for chassis by-wire is also increasing. Components such as by-wire service brakes, by-wire parking brakes, and by-wire steering are also continuously developing and gradually starting pre-research on industrialization.

[0003] Currently, by-wire hydraulic braking technology has gradually matured and started to be promoted in the automotive industry. With the improvement of the intelligence level of automobiles, the demand for by-wire of the execution system is also continuously increasing. The advantages of by-wire mechanical braking, such as flexible layout, environmental friendliness, higher efficiency, faster response, and sufficient redundancy, are gradually emerging. By-wire braking systems are gradually becoming a major development trend in the automotive industry. The electromechanical braking system (EMB) adopts a form of direct drive by wheel-end motors. Through a motion conversion mechanism, the torque and rotational motion of the motor are converted into the thrust and translational motion of a connecting member, which pushes the brake pads to clamp the brake disc to obtain braking force. At the same time, as an emerging braking system, electromechanical braking abandons large-sized components such as vacuum boosters and hydraulic pipelines, making the overall vehicle chassis layout simpler and more flexible, and having the advantages of fast and precise pressure regulation speed, which can significantly improve the braking performance of the whole vehicle.

[0004] In the existing technical solutions of EMB brake calipers, the brake caliper structures all have locking mechanisms. Among them, there is a structure that uses a bistable electromagnet as the locking power device. By the extension and retraction of the locking head of the electromagnet, the power transmission is locked and unlocked, so as to realize the locking of the entire parking system. However, the bistable electromagnet itself has the characteristic of fast action, and during the execution of the entire locking action, it can only be held at the starting two positions. Therefore, the action state of the bistable electromagnet can be stuck at any position.

[0005] The patent document with the publication number CN218598679U discloses a parking brake locking device. In this parking brake locking device, due to the instantaneous action of the electromagnet and directly locking the system by the electromagnet, there may be a risk of ineffective locking. Therefore, an additional position detection system is required to realize the position state of the locking head, and the layout of the position detection system is difficult. At the same time, during the locking process, there may be impacts between the gear groove and the locking head, which will not only generate impact noise but also have impact stress, affecting the noise evaluation and service life of the product. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a control method for a locking mechanism of an electro-mechanical braking system, aiming to improve the reliability of locking.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: a control method for a locking mechanism of an electro-mechanical braking system, the locking mechanism of the electro-mechanical braking system includes an electromagnet and a multi-stage gear transmission mechanism, and the locking head of the electromagnet is configured to be embedded in a locking groove provided on any one of the gears of the multi-stage gear transmission mechanism in the locking state, and a plurality of locking grooves are provided on the gear.

[0008] When performing a locking or releasing action, first control the rotation of the gear until the center line of the target locking groove on the gear rotates to a position aligned with the center line of the locking head, and then control the electromagnet to be energized, the locking head extends and inserts into the locking groove, and then the motor controls the gear to rotate in a first direction until the locking head contacts the locking end face of the locking groove to complete the locking action.

[0009] The width of the locking groove is greater than the width of the locking head.

[0010] The difference between the width of the locking groove and the width of the locking head is greater than twice the control accuracy.

[0011] After the locking end face of the locking groove fits with the locking head, the ECU marks the position of the gear at this time and stores the corresponding locking position information in the memory of the ECU.

[0012] After performing the fitting action of the locking groove and the locking head, the deviation error between the target value and the actual value of the gear position and the clamping force is judged through a control variable, and a reliable locking position is judged. The control variables include the current, position and clamping force signal of the motor. The deviation between the target value and the actual value refers to controlling the set target position or clamping force, but still exceeding the reasonable control error after a period of time.

[0013] After receiving a locking request, the ECU executes the detection and control of the locking mechanism according to the following steps:

[0014] The ECU accepts the locking request;

[0015] Execute center line alignment, the ECU reads the locking position information stored in the memory, and makes the target locking groove on the gear run to this locking position;

[0016] The electromagnet is energized, and the locking head is inserted into the locking groove;

[0017] The gear rotates until the locking end face of the locking groove fits with the locking head;

[0018] Perform locking state confirmation, continuously rotate the gear, and determine whether the deviation of the rotation angle of the gear and the clamping force of the electro-mechanical braking system exceeds the release judgment threshold; if it exceeds, it is judged as a reliable locking state, otherwise it is judged as a locking failure, and the locking action is performed again;

[0019] Position memory: After the locking state is confirmed, the fitting position of the locking groove and the locking head is memorized, and the entire locking process is completed.

[0020] Before the start of the parking release action, the ECU marks the position of the gear when the locking groove and the locking head are in the fitting state, and stores the locking position information corresponding to the marking result in the memory of the ECU.

[0021] After performing the release action of the locking groove and the locking head, judge the deviation error between the target value and the actual value of the gear position and the clamping force by controlling variables. The control variables include the current, position and clamping force signal of the motor. The deviation between the target value and the actual value means that the position or clamping force of the control setting target is still beyond the reasonable control error after a certain period of time.

[0022] After receiving the release request, the ECU performs the detection and control of the locking mechanism according to the following steps:

[0023] The ECU accepts the release request;

[0024] Perform center line alignment. The ECU reads the locking position information stored in the memory, and then controls the gear to rotate to the position where the center line of the locking groove rotates to align with the center line of the locking head;

[0025] The electromagnet is energized, and the locking head is moved out of the locking groove;

[0026] The gear rotates to release the clamping force of the electro-mechanical braking system;

[0027] Perform release state confirmation, continuously rotate the gear, and determine whether the deviation of the rotation angle of the gear and the clamping force of the electro-mechanical braking system exceeds the locking judgment threshold; if it does not exceed, it is judged as a reliable release state, otherwise it is judged as a release failure, and the release action is performed again;

[0028] Position memory: After the release state is confirmed, the locking position information read in the second step is memorized, and the entire release process is completed.

[0029] The control method of the locking mechanism of the electro-mechanical braking system of the present invention has the following advantages:

[0030] 1. Before the locking head enters the locking groove, by controlling the position of the locking groove, the center alignment of the locking groove and the locking head is achieved, avoiding the collision between the two in the case where the locking head cannot enter the locking groove, reducing the noise of the system and avoiding the stress damage to the locking head and the gear caused by the collision;

[0031] 2. After the locking head enters the locking groove, by controlling the rotation of the locking groove, the low-speed or zero-speed fitting of the locking groove and the locking head is achieved, avoiding the collision at the moment when the locking head and the locking groove are fitted, reducing the noise of the system and avoiding the stress damage to the locking head and the gear caused by the collision;

[0032] 3. By controlling the following and deviation conditions of the position of the locking groove, the judgment of the reliable fitting and reliable release of the locking head and the locking groove is achieved, reducing the position sensors of the locking head and lowering the system cost. Brief Description of the Drawings

[0033] This specification includes the following drawings, and the shown contents are respectively:

[0034] Figure 1 is a schematic structural diagram of a double gear;

[0035] Figure 2 is a schematic diagram of the centering state of the locking head and the locking groove;

[0036] Figure 3 is a schematic diagram of the fitting state of the locking head and the locking groove;

[0037] Figure 4 is a schematic diagram of the locking process flow;

[0038] Figure 5 is a schematic diagram of the release process flow;

[0039] The marks in the figure are:

[0040] 1. Double gear; 1a. Locking groove; 1a1. Locking end face; 1a2. Non-locking end face; 1b. Deburring groove. Detailed Description of the Preferred Embodiments

[0041] The following is a more detailed description of the specific embodiments of the present invention by describing the embodiments with reference to the drawings, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitate its implementation.

[0042] Such as Figures 1 to 3As shown in the figure, the present invention provides a control method for an EMB locking mechanism. The EMB locking mechanism includes an electromagnet and a multi-stage gear transmission mechanism. The locking head of the electromagnet is configured to be inserted into a locking groove provided on any one of the gears of the multi-stage gear transmission mechanism in the locking state, and multiple locking grooves are provided on the gear.

[0043] Specifically, as Figure 1 shown, locking grooves with a certain length are arranged on any stage of the gear. At the same time, the electromagnet is arranged as a driving device in a cavity provided on the MGU housing. The locking and unlocking are achieved by the extension and retraction of the locking head of the electromagnet to cooperate with the locking grooves on the gear, so as to realize the parking locking function of the EMB.

[0044] As Figures 1 to 3 shown, a locking end face 1a1 and a non-locking end face 1a2 are provided in the locking groove. The locking end face 1a1 and the non-locking end face 1a2 are the inner wall surfaces at the opposite ends in the length direction of the locking groove. The locking end face 1a1 is used to contact the surface of the locking head in the locking state, and the non-locking end face 1a2 is used to push the locking head out of the locking groove 1a during the rotation of the gear. The non-locking end face 1a2 is a plane inclined in the locking groove. There is an angle between the non-locking end face 1a2 and the axis of the gear, and this angle is an acute angle. The moving direction of the locking head is parallel to the axis of the gear. A first contact surface in contact with the non-locking end face 1a2 is provided on the locking head. This first contact surface is an inclined plane. There is an angle between the first contact surface and the moving direction of the locking head, and this angle is an acute angle. The inclined angles of the first contact surface and the non-locking end face 1a2 are the same. The locking end face 1a1 is a plane parallel to the axis of the gear. A second contact surface in contact with the locking end face 1a1 is provided on the locking head. The second contact surface is a plane parallel to the moving direction of the locking head. In the locking state, the second contact surface fits with the locking end face 1a1, and the locking head plays a circumferential limiting role on the gear to achieve locking.

[0045] Preferably, multiple locking grooves are provided, and all the locking grooves are evenly distributed circumferentially on the gear with the axis of the gear as the center line. In the locking state, the locking head is inserted into one of the locking grooves. The width of the locking groove is greater than the width of the locking head. The width direction of the locking head is parallel to the width direction of the locking groove. The length direction of the locking groove is perpendicular to its width direction. The length and width of the locking groove are both greater than the length and width of the locking head, ensuring that the locking head has enough time to completely enter the locking groove. In this way, when the locking head enters the locking groove, there is sufficient open space in the front, back, left, and right, which will not hinder the movement of the locking head, thus ensuring the effectiveness of the axial movement of the locking mechanism. Thereby, the position sensor can be cancelled, simplifying the module components and reducing the manufacturing cost.

[0046] As Figure 1As shown in the figure, a weight-removing groove 1b is provided on the gear. A plurality of weight-removing grooves 1b are provided. All the weight-removing grooves 1b provided on the gear are evenly distributed circumferentially with the axis of the gear as the center line, achieving a weight-reducing effect.

[0047] The multi-stage gear transmission mechanism is used to transmit the driving force generated by the motor. The multi-stage gear transmission mechanism includes a first-stage transmission mechanism and a second-stage transmission mechanism. The driving gear of the first-stage transmission mechanism is connected to the motor, and the motor provides the driving force. The motor is controlled by an ECU (electronic control unit). A locking groove is provided on the driven gear of the first-stage transmission mechanism. The driving gear and the driven gear of the first-stage transmission mechanism are meshed with each other. The driven gear of the first-stage transmission mechanism is fixedly connected to the driving gear of the second-stage transmission mechanism to form a double gear. The driven gear of the second-stage transmission mechanism is an output gear. The driven gear of the first-stage transmission mechanism is meshed with the driving gear of the second-stage transmission mechanism, and the output gear outputs power to realize the clamping function of the EMB.

[0048] As Figure 1 shown, in this embodiment, a total of 8 locking grooves are provided on the gear. The locking grooves are arc-shaped grooves, and the axis of the locking grooves is the same axis as the axis of the gear. 8 weight-removing grooves are also provided. The weight-removing grooves 1b and the locking grooves are arranged in parallel in the direction from the center to the periphery, and the weight-removing grooves 1b and the locking grooves are arranged staggeredly in the circumferential direction. Such a design structure can increase the strength of the gear.

[0049] The control method of the locking mechanism of the gear with locking grooves proposed by the present invention realizes the central alignment of the locking groove and the locking head during the locking or releasing process through the memory and control of the stop position of the locking groove, and the position memory when the locking groove and the locking head are in contact. When performing the locking or releasing action, first align the center lines of the locking groove and the locking head, then drive the electromagnet to realize the cooperation or separation of the locking groove and the locking head, and then control the speed of the gear to realize the side contact of the locking groove and the locking head, completing the locking or releasing of the entire locking mechanism. At the same time, through the change of the control variables of the gear, the locking or releasing state is confirmed.

[0050] When performing the locking or releasing action, first control the gear to rotate until the center line of the target locking groove on the gear rotates to a position aligned with the center line of the locking head, then control the electromagnet to be energized, the locking head extends and inserts into the locking groove, and then the motor controls the gear to rotate in the first direction until the locking head contacts the locking end surface of the locking groove, completing the locking action.

[0051] The difference between the width of the locking groove and the width of the locking head is greater than twice the control accuracy. Based on this constraint, the rotational control accuracy of the gear is confirmed. The position accuracy of the locking groove's movement is controlled by the controller to rotate the locking groove to the set target rotational position, thereby ensuring the position of the locking groove's rotation. The width difference between the locking groove and the locking head is used to ensure that the locking head can reliably enter the locking groove. The control accuracy refers to the maximum value of the deviation of the gear's rotational angle when the controller controls the motor to drive the gear to rotate. After the locking end face of the locking groove fits with the locking head, the ECU marks the position of the gear at this time and stores the corresponding locking position information of the marking result in the memory of the ECU. The marked position is stored for reference for the next parking locking position.

[0052] After performing the fitting action of the locking groove and the locking head, the deviation error between the target value and the actual value of the gear position and the clamping force is judged through the control variables to determine the reliable locking position. The control variables include the current, position, and clamping force signals of the motor. The deviation between the target value and the actual value means that the position or clamping force of the control set target is controlled, but still exceeds the reasonable control error after a period of time.

[0053] As Figure 4 shown, after the ECU receives the locking request, it performs the detection and control of the locking mechanism according to the following steps:

[0054] The first step is to accept the locking request. The ECU receives the parking locking request transmitted from the upper-level control unit.

[0055] The second step is to perform the center line alignment. The ECU reads the locking position information stored in the memory, calculates the center line positions of the locking groove and the locking head, and then makes the target locking groove on the gear run to this locking position.

[0056] The third step is to energize the electromagnet, and the locking head is inserted into the locking groove.

[0057] The fourth step is that the gear rotates until the locking end face of the locking groove fits with the locking head.

[0058] The fifth step is to confirm the locking state. Control the gear to continue rotating, and judge whether the deviation of the rotation angle of the gear and the clamping force of the EMB exceeds the release judgment threshold; if it exceeds, it is judged as a reliable locking state, otherwise it is judged as a locking failure, and the locking action is performed again, that is, the second step to the fifth step are performed again.

[0059] The sixth step is position memory. After the locking state is confirmed, the fitting position of the locking groove and the locking head is memorized, and the entire locking process is completed.

[0060] Before the start of the parking release operation, the ECU marks the position of the gear when the locking groove and the locking head are in a fitting state, and stores the locking position information corresponding to the marking result in the memory of the ECU.

[0061] As Figure 5 shown, after performing the release operation of the locking groove and the locking head, the deviation error between the target value and the actual value of the gear position and the clamping force is judged by controlling variables to determine the reliable release position. The control variables include the current, position, and clamping force signals of the motor. The deviation between the target value and the actual value means that the position or clamping force of the control setting target is exceeded after a certain period of time, still exceeding the reasonable control error.

[0062] After receiving the release request, the ECU performs the detection and control of the locking mechanism according to the following steps:

[0063] The first step is to accept the release request. The ECU receives the parking release request transmitted from the upper-level control unit.

[0064] The second step is to perform center line alignment. The ECU reads the locking position information stored in the memory, and then controls the gear to rotate to the position where the center line of the locking groove is aligned with the center line of the locking head.

[0065] The third step is to energize the electromagnet, and the locking head moves out of the locking groove.

[0066] The fourth step is to rotate the gear to release the EMB clamping force.

[0067] The fifth step is to confirm the release state. Control the gear to continue rotating, and judge whether the deviation of the rotation angle of the gear and the following of the clamping force of the EMB exceeds the locking judgment threshold; if not, it is judged as a reliable release state, otherwise it is judged as a release failure, and the release operation is performed again, that is, the second step to the fifth step are performed again.

[0068] The sixth step is position memory. After the release state is confirmed, the locking position information read in the second step is memorized, and the entire release process is completed.

[0069] The present invention has been described exemplarily in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention; or without improvement, the above-mentioned concept and technical solution of the present invention are directly applied to other occasions, all are within the protection scope of the present invention.

Claims

1. Control method for a locking mechanism of an electro-mechanical braking system, the locking mechanism comprising an electromagnet and a multi-stage gear transmission mechanism, Characterized in that: The locking head of the electromagnet is arranged to be embedded in a locking groove provided on any one of the gears of the multi-stage gear transmission mechanism in the locking state, and a plurality of locking grooves are provided on the gear.

2. The control method for a locking mechanism of an electro-mechanical braking system according to claim 1, Characterized in that: When performing a locking or releasing action, first control the rotation of the gear until the center line of the target locking groove on the gear rotates to a position aligned with the center line of the locking head, and then control the electromagnet to be energized, the locking head extends and inserts into the locking groove, and then the motor controls the gear to rotate in a first direction until the locking head contacts the locking end face of the locking groove to complete the locking action.

3. The control method for a locking mechanism of an electro-mechanical braking system according to claim 1, Characterized in that: The width of the locking groove is greater than the width of the locking head.

4. The control method for a locking mechanism of an electro-mechanical braking system according to claim 3, Characterized in that: The difference between the width of the locking groove and the width of the locking head is greater than twice the control accuracy.

5. The control method for a locking mechanism of an electro-mechanical braking system according to any one of claims 1 to 4, Characterized in that: After the locking end face of the locking groove fits with the locking head, the ECU marks the position of the gear at this time and stores the locking position information corresponding to the marking result in the memory of the ECU.

6. The control method for a locking mechanism of an electro-mechanical braking system according to claim 5, Characterized in that: After performing the fitting action of the locking groove and the locking head, the deviation error between the target value and the actual value of the gear position and the clamping force is judged by a control variable to judge the reliable locking position.

7. The control method for a locking mechanism of an electro-mechanical braking system according to claim 5, Characterized in that: After receiving a locking request, the ECU performs detection and control of the locking mechanism according to the following steps: The ECU accepts the locking request; Perform center line alignment, the ECU reads the locking position information stored in the memory and makes the target locking groove on the gear run to this locking position; The electromagnet is energized and the locking head is inserted into the locking groove; The gear rotates until the locking end face of the locking groove fits with the locking head; Perform locking state confirmation, control the gear to continue rotating, and judge whether the deviation of the rotation angle of the gear and the clamping force of the electro-mechanical braking system exceeds the locking judgment threshold; if it exceeds, it is judged as a reliable locking state, otherwise it is judged as a locking failure and the locking action is performed again; Position memory, after the locking state is confirmed, the fitting position of the locking groove and the locking head is memorized, and the entire locking process is completed.

8. The control method for a locking mechanism of an electro-mechanical braking system according to any one of claims 1 to 4, Characterized in that: Before the start of the parking release operation, the ECU marks the position of the gear when the locking groove and the locking head are in a fitting state, and stores the locking position information corresponding to the marking result in the memory of the ECU.

9. The control method of the locking mechanism of the electro-mechanical braking system according to claim 8, wherein: After performing the release operation of the locking groove and the locking head, the deviation error between the target value and the actual value of the gear position and the clamping force is judged by a control variable to judge the reliable release position.

10. The control method of the locking mechanism of the electro-mechanical braking system according to claim 8, wherein: After receiving the release request, the ECU performs the detection and control of the locking mechanism according to the following steps: The ECU accepts the release request; Perform center line alignment. The ECU reads the locking position information stored in the memory, and then controls the gear to rotate to a position where the center line of the locking groove rotates to align with the center line of the locking head; The electromagnet is energized, and the locking head is removed from the locking groove; The gear rotates to release the clamping force of the electro-mechanical braking system; Perform release state confirmation. Control the gear to continue rotating, and judge whether the deviation of the rotation angle of the gear and the clamping force of the electro-mechanical braking system exceeds the release judgment threshold; if not, it is judged as a reliable release state, otherwise it is judged as a release failure, and the release operation is performed again; Position memory. After the release state is confirmed, the locking position information read in the second step is memorized, and the entire release process is completed.

Images