Parking mechanism of electronic mechanical braking system

Abstract

The utility model discloses a parking mechanism of an electronic mechanical braking system, which comprises an iron core shaft, a telescopic component positioned on the iron core shaft and a sliding component matched with the telescopic component, and the sliding component is movably connected with a pawl rocker arm; the electromagnet is located at one end of the iron core shaft; the pawl rocker arm is clamped with the parking ratchet wheel through the action of the iron core shaft, the telescopic assembly and the electromagnet, reliable parking of the EPB can be achieved from the mechanical angle, and parking does not need to be supplemented through too complex control strategies. And secondly, the method can be realized in a smaller space without occupying an overlarge angular space in the output circumferential direction of the motor. The bidirectional holding electromagnet is used in the scheme, frequent electrification in a certain direction is not needed, accurate parking is completed without additionally and repeatedly adjusting the angle of the motor, and the energy-saving effect of the system is achieved.

Description

Technical Field

[0001] This utility model relates to the field of vehicle electromechanical braking, specifically a parking mechanism for an electromechanical braking system. Background Technology

[0002] Electronic parking brake (EPB) is a technology that integrates temporary braking during driving and long-term braking after parking, using electronic control to achieve parking. It gradually replaced the traditional cable-operated handbrake at the beginning of the last century, representing a significant advancement in parking braking.

[0003] Currently, most automotive EPB systems on the market use a BLDC motor to drive a reduction mechanism (gear system or gear / belt combination) to rotate, which in turn drives a screw with a self-locking function to rotate, thereby pushing the rear axle hydraulic piston to press the friction plate and clamp the rear axle brake disc to achieve vehicle parking.

[0004] When using electromechanical braking systems in vehicles, because the service brake is driven by an electric motor rather than hydraulically, for system simplification, the EPB (Electronic Braking Brake) typically uses an EMB (Electronic Braking Motor) instead of an additional parking motor. Due to this configuration, the entire mechanical part of the EPB's actuator is also an EMB system actuator, consisting of a motor, reducer, and ball screw. However, the EMB mechanism is primarily used for service braking and does not have, and cannot have, a self-locking function. Additional auxiliary mechanisms are needed to achieve EPB functionality. Currently, mainstream EMB solutions generally use a bidirectional holding electromagnet to lock the motor output shaft to achieve EPB functionality.

[0005] However, using a bidirectional holding electromagnet to implement the EPB function has inherent problems. For example, the parking mechanisms mentioned in CN116424292A and CN117905881A have complex structures and are unstable. They cannot achieve parking using simple mechanical structures. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model provides a parking mechanism for an electromechanical braking system, which enables convenient parking.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A parking mechanism for an electromechanical braking system includes an iron core shaft, a telescopic assembly located on the iron core shaft, a sliding assembly cooperating with the telescopic assembly, the sliding assembly being movably connected to a pawl rocker arm, and an electromagnet located at one end of the iron core shaft; the pawl rocker arm engages with a parking ratchet through the action of the iron core shaft, the telescopic assembly, and the electromagnet.

[0009] Further preferably, an iron core is disposed inside the iron core shaft.

[0010] Furthermore, the telescopic component is a spring;

[0011] More preferably, the sliding component is a slider, the slider is provided with a slider pin, one end of the pawl rocker arm is connected to the slider pin, and the other end of the pawl rocker arm is connected to a rocker arm pin.

[0012] Further preferably, the electromagnet is a bidirectional holding electromagnet.

[0013] In a further preferred embodiment, the parking ratchet is connected to the motor output shaft.

[0014] In a further preferred embodiment, the upper end of the iron core shaft near the slider is provided with a stepped surface or a retaining spring, and the stepped surface or retaining spring is located between the iron core and the slider.

[0015] This utility model has the following beneficial effects:

[0016] This invention provides a parking mechanism for an electromechanical braking system (EPB), which solves the problem of reliable EPB parking from a mechanical perspective without requiring overly complex control strategies. Secondly, it can be implemented in a smaller space, avoiding excessive circumferential angular space occupied by the motor output. Furthermore, this solution uses a bidirectional holding electromagnet, eliminating the need for constant energization in one direction and the need for repeated adjustments to the motor angle for accurate parking, thus achieving energy-saving effects. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the parking mechanism of this utility model in the driving state.

[0018] Figure 2 This is a structural diagram of the parking mechanism of this utility model in the normal parking state.

[0019] Figure 3 This is a structural diagram of the ratchet pawl of this utility model in the state of being engaged with the tooth tip. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and relevant knowledge. Obviously, the described applications are only some embodiments of the present invention, and not all embodiments.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Example 1: Refer to Figures 1-2As shown, a parking mechanism of an electromechanical braking system includes an iron core shaft 5, a telescopic component located on the iron core shaft, preferably a spring 6, a sliding component cooperating with the telescopic component, preferably a slider 7, and a pawl rocker arm 3 movably connected to the sliding component; an electromagnet, preferably a bidirectional holding electromagnet 9, and the iron core shaft 5 being an extension of the electromagnet core; the pawl rocker arm 3 engages with the parking ratchet 1 through the action of the iron core shaft 5, the telescopic component, and the electromagnet. This parking mechanism, through the synergistic action of the iron core shaft 5, the telescopic component, and the electromagnet, achieves precise engagement between the pawl rocker arm 3 and the parking ratchet 1, thereby ensuring the stable execution of the vehicle parking function.

[0023] In this invention, the iron core shaft 5 is an extension of the electromagnet core, preferably an integral design of the core and the iron core shaft 5. A slider pin 8 is provided on the slider 7. One end of the pawl rocker arm 3 is connected to the slider pin 8, and the other end of the pawl rocker arm 3 is connected to a rocker arm pin 4. The parking ratchet 1 is connected to the motor output shaft 2. Specifically, the iron core shaft 5 is fixed to the core and is used to achieve axial movement under the action of the electromagnet, thereby driving the movement of the iron core shaft 5. The slider 7 is provided with a slider pin 8, which serves as the connecting fulcrum of the pawl rocker arm 3. One end of the pawl rocker arm 3 is hinged to the slider pin 8, and the other end is fixed to the mechanism base via the rocker arm pin 4, allowing it to rotate and swing around the rocker arm pin 4. Furthermore, the parking ratchet 1 is rigidly fixed to the motor output shaft 2 through an interference fit or key connection, ensuring synchronous rotation of both.

[0024] The specific working process is as follows:

[0025] Under normal driving conditions: the bidirectional holding electromagnet 9 is in the extended holding state, and the iron core shaft 5 is kept extended under the magnetic force of the electromagnet. At this time, the spring 6 is in the naturally extended state. The slider 7 is limited by the shoulder or retaining spring on the iron core shaft 5. It is preferable to use a retaining spring, and more preferably, the retaining spring is sleeved on the iron core shaft 5 and located at the upper end of the slider 7. It can slide together with the slider 7. Due to the obstruction of the retaining spring, the slider 7 cannot move towards the electromagnet, or in other words, it cannot move into the electromagnet. Similarly, the same principle applies to using a shoulder. It should be noted that the main structure of the shoulder type is a bushing. The bushing part is located inside the bidirectional holding electromagnet 9, and the other part is used to limit the slider 7. The shoulder is sleeved on the iron core shaft 5 and located at the upper end of the slider 7. The slider 7 keeps the pawl on the pawl rocker arm 3 disengaged from the parking ratchet 1. Since the parking ratchet 1 is fixedly connected to the motor output shaft 2, the entire motor drive system can rotate freely without affecting the braking and power transmission during normal vehicle operation. Meanwhile, the design ensures that the holding force of the electromagnet is greater than the inertial force generated by the slider 7, pawl rocker arm 3 and iron core shaft 5 under extreme acceleration / deceleration conditions of the vehicle, so as to avoid the parking function being triggered erroneously.

[0026] Parking Operation Process: When the vehicle stops and the control system receives the EPB parking command, the EMB control system first adjusts the braking force of each wheel to the required parking clamping force and stops the rotation of the motor output shaft 2 and the parking ratchet 1. Then, the EMB controller supplies current (assuming a positive current) to the bidirectional holding electromagnet 9. The permanent magnet inside the electromagnet interacts with the magnetized iron core, generating a strong attraction that quickly pulls the iron core shaft 5 back into the electromagnet. During this process, the slider 7 moves synchronously towards the electromagnet under the drive of the iron core shaft 5. Simultaneously, the spring 6 is compressed and deformed under the pressure of the slider 7, accumulating elastic potential energy and pushing the slider 7 to drive the pawl rocker arm 3 to rotate clockwise around the rocker arm pin 4, so that the pawl precisely engages in the tooth groove of the parking ratchet 1. At this time, the rotation of the parking ratchet 1 is restricted by the pawl, thereby locking the rotation of the motor output shaft 2, which is fixedly connected to it, preventing the motor from continuing to drive the screw to clamp, and simultaneously counteracting the reverse thrust generated by the friction plate and the screw, achieving reliable maintenance of the vehicle's braking force and completing the parking action. This position can be limited by the aforementioned retaining ring or the shoulder. After the iron core shaft 5 is pulled back, the shoulder or retaining ring is outside the electromagnet frame. In normal operation, the shoulder or retaining ring will prevent the slider 7 from moving further toward the bidirectional holding electromagnet 9. That is, in this application, the shoulder or retaining ring is mainly used to limit the slider 7 in normal operation, preventing the slider 7 from moving toward the bidirectional holding electromagnet 9 and causing the motor output shaft to be accidentally locked.

[0027] Special Case Handling: If, during parking operation, the pawl of the pawl rocker arm 3 initially aligns with the tip of the parking ratchet 1 tooth, preventing immediate engagement, the system can still reliably park. After the bidirectional holding electromagnet 9 is energized, the iron core shaft 5 remains in its returned position. At this time, the compressed spring 6 continuously applies a return force to the slider 7 and its connected pawl rocker arm 3. Once the drive motor is de-energized, the parking ratchet 1, under the reverse force of the EMB screw, will slowly rotate at a lower speed with the motor output shaft 2. When the ratchet 1 has rotated half a tooth pitch, the pawl of the pawl rocker arm 3 will engage with the ratchet tooth under the push of the spring 6, locking the motor output and ensuring the vehicle successfully enters the parking state.

[0028] Release of parking brake process: Upon receiving the release command, the EMB controller supplies a reverse current to the bidirectional holding electromagnet 9, changing the direction of the magnetic field. The electromagnet generates a thrust that pushes out the core shaft 5, and the slider 7 moves outward synchronously under the drive of the core shaft 5. Since the end of the slider 7 near the electromagnet has a stepped surface or a retaining spring (preferably a retaining spring), it moves as part of the core shaft 5, ensuring that the slider 7 can fully drive the pawl rocker arm 3 to reset, completely separating the pawl from the parking ratchet 1. At this time, the motor output shaft 2 is unlocked, and the vehicle can resume normal driving. This process does not interfere with the service braking function.

[0029] This invention allows the electromechanical braking system to quickly and accurately park the vehicle after the driver or vehicle control system sends a parking command to the electromechanical braking mechanism controller. Similarly, upon receiving a release command, the controller can quickly release the vehicle from its parking state by controlling the mechanism.

[0030] This invention achieves reliable execution of the EPB function through the cooperation of mechanical structures.

[0031] This invention, through its ingenious pawl and rod structure design, combined with the spring at the end of the iron core rod of the bidirectional holding electromagnet, structurally ensures that the pawl will engage with the ratchet every time the vehicle is parked.

[0032] The specific process is as follows: When a vehicle equipped with EMB stops, the system maintains the braking force on each wheel. At this time, the driver or vehicle control system outputs an EPB parking request, and the EMB controller controls the bidirectional holding electromagnet to be energized, pulling the iron core back. The energizing time is generally controlled within the hundreds of milliseconds range. When the iron core returns to its original position, the sliding sleeve on the iron core compresses the spring due to inertia. Since the spring can deform and store energy, after the iron core is in position, the spring can continue to drive the rocker arm to move the pawl and engage the ratchet. When the pawl is aligned with the backlash of the ratchet, the pawl locks the ratchet, and the output motor cannot rotate. In special cases, if the pawl fails to engage the ratchet the first time, after the bidirectional holding electromagnet is energized, the iron core rod has already returned to its original position and is held. At this time, the elastic potential energy stored in the spring will continue to exert a returning force on the rocker arm. When the reducer drives the motor and is powered off, the ratchet will rotate with the motor shaft under the action of the lead screw and the reverse force. Because the rotation speed is low when it starts, once the rotation angle exceeds half a tooth, the rocker arm and pawl pushed by the spring will be engaged in the ratchet, thereby locking the motor output end and parking the vehicle.

[0033] Meanwhile, a stepped surface or a retaining ring is designed at the position of the slider near the bidirectional electromagnet to ensure that when the electromagnet pushes out the iron core, that is, when the EPB is released, the slider, the iron core and the rod move rigidly, achieving 100% release of the parking brake without hindering the service brake.

[0034] In this invention, it should be noted that the iron core is embedded inside the iron core shaft, and the iron core shaft is the extension of the iron core away from the electromagnet, essentially the iron core shaft being sleeved on the outside of the iron core, with one end of the iron core protruding from the iron core shaft. When the electromagnet is bidirectionally energized, the magnetic field generated by the current and the magnetic field of the internal permanent magnet act together on the iron core. Because the iron core is magnetized, it tends to move axially under the influence of the magnetic force. Since the iron core and the iron core shaft are an integral structure, the movement of the iron core will cause the iron core shaft to move axially within the electromagnet. For example, when a positive current is applied to the electromagnet, an attractive force is generated, and the iron core moves inward under the attraction, pulling the iron core shaft back; when a reverse current is applied, a pushing force is generated, causing the iron core to push the iron core shaft outward. The slider is sleeved on the iron core shaft, which has a limiting structure (such as a shoulder or retaining ring). Under normal operating conditions, the iron core shaft remains extended under the magnetic force of the electromagnet, and the shoulder or retaining ring restricts the slider from moving towards the electromagnet. When parking is activated, the iron core shaft moves inward under the action of the electromagnet. A certain connection exists between the slider and the iron core shaft (e.g., the slider and the iron core shaft can slide relative to each other, but are constrained in a specific direction). The movement of the iron core shaft causes the slider to move synchronously towards the electromagnet. After reaching a certain position, the slider abuts against the shoulder of the iron core shaft. When parking is released, the iron core shaft is pushed out, which similarly causes the slider to move outward synchronously. Throughout the entire operation, the bidirectional electromagnet controls the direction of the magnetic field, causing the iron core to be subjected to magnetic force inside the iron core shaft, thus driving the iron core shaft to move axially. The axial movement of the iron core shaft, in turn, drives the slider to move synchronously through the limiting structure and connection relationship. This motion relationship allows for precise control of the slider position under the control of the electromagnet, which in turn drives components such as the pawl rocker arm to complete the engagement and disengagement of the parking mechanism's pawl and parking ratchet. For example, during parking, the electromagnet is energized, causing the iron core to pull back the iron core shaft. The iron core shaft then moves the slider, which in turn compresses the spring and pushes the pawl rocker arm to rotate, thus engaging the pawl with the parking ratchet. When parking is released, reverse energization causes all three components to move in opposite directions, thus separating the pawl from the ratchet.

[0035] In addition, the bidirectional electromagnet contains a permanent magnet. When the iron core shaft moves to the designated position (engaged or extended) under the electromagnet's action, the magnetic field generated by the permanent magnet remains even after the current is cut off. The magnetic field of the permanent magnet interacts with the iron core inside the iron core shaft, generating a holding force that stably holds the iron core shaft in its current position, preventing it from falling out. For example, in the normal driving state of the parking mechanism, the iron core shaft is held in the extended position by the electromagnet's magnetic force. At this time, the magnetic field of the permanent magnet interacts with the iron core, maintaining the stability of the iron core shaft. The mechanical structure design between the iron core shaft and the electromagnet also plays an auxiliary role in fixation. When the iron core shaft moves inside the electromagnet, its fit with the electromagnet is highly precise, and there is a certain mechanical constraint between them. For example, the guide structure inside the electromagnet ensures that it will not shake or detach during movement; at the same time, the internal chamber structure of the electromagnet also has a certain limiting effect on the iron core shaft, further preventing it from falling out.

[0036] Example 2: Refer to Figures 1-3 As shown, a parking mechanism of an electromechanical braking system includes an iron core shaft 5, a telescopic component (preferably a spring 6) located on the iron core shaft, a sliding component (preferably a slider 7) cooperating with the telescopic component, and a pawl rocker arm 3 movably connected to the sliding component; an electromagnet, preferably a bidirectional holding electromagnet 9, located at one end of the iron core shaft 5; the pawl rocker arm 3 engages with the parking ratchet 1 through the action of the iron core shaft 5, the telescopic component, and the electromagnet. This parking mechanism, through the coordinated action of the iron core shaft 5, the telescopic component, and the electromagnet, achieves precise engagement between the pawl rocker arm 3 and the parking ratchet 1, thereby ensuring the stable execution of the vehicle parking function.

[0037] During normal driving, the bidirectional holding electromagnet is in the extended holding state. The pawl on rocker arm 3 disengages from ratchet 1. Because the electromagnet core shaft 5 has a shoulder or retaining ring, slider 7 cannot move towards the electromagnet without the core shaft being stationary. Therefore, the pawl on rocker arm 3 will not obstruct the rotation of ratchet 1. Ratchet 1 is locked to the motor output shaft 2 by interference fit or other anti-rotation measures, so the system will not restrict the rotation of the output shaft and the subsequent reduction mechanism. At the same time, the design ensures that the holding force of the bidirectional holding electromagnet 9 is greater than the sum of the inertial forces of slider 7, rocker arm 3, and core shaft 5. This ensures that the electromagnet core shaft 5 will not malfunction under the maximum acceleration / deceleration of the vehicle, thus preventing the parking function from being falsely triggered.

[0038] When a parking command is received, ratchet 1 and output shaft 2 stop rotating after reaching the parking clamping force required by the EMB. Then, the EMB controller controls the bidirectional holding electromagnet 9 to be energized (the current direction has opposite directions; assuming a positive current is flowing at this time, i.e., the positive and negative directions of the two DC terminals are set to positive), generating a magnetic field that magnetizes the iron core. The magnetized iron core then interacts with the permanent magnet of the holding electromagnet 9, pulling the iron core back into the electromagnet 9. At this time, slider 7 is pushed to the shoulder position of iron core shaft 5, and rocker arm 3 rotates around rocker arm pin 4 under the action of spring 6, causing the pawl to engage with ratchet 1. At this time, the rotation of ratchet 1, which is locked with output shaft 2, is restricted, and thus the rotational motion output by the motor cannot be implemented. That is, the motor cannot continue to clamp, and the reverse force of the friction plate and lead screw will not push the output shaft 2 to rotate. This achieves the maintenance of braking force, i.e., the parking function.

[0039] In special circumstances, if the pawl at the end of rocker arm 3 moves to align with the tip of ratchet 1 on its first movement but fails to engage immediately, the bidirectional holding electromagnet 9 stops energizing, the iron core shaft 5 returns to its original position and remains in place, and the elastic potential energy stored in spring 6 continues to exert a restoring force on rocker arm 3. When the drive motor is de-energized, ratchet 1 will begin to rotate with motor shaft 2 under the reverse force of the EMB screw. Because the rotation speed is low at startup, once the rotation angle exceeds half a ratchet tooth, rocker arm 3 and pawl pushed by spring 6 will engage with ratchet 1, locking the motor output end 2 and thus maintaining the braking force, allowing the vehicle to enter the parking state.

[0040] Although some embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, and all such changes and alterations should fall within the scope of the present invention.

Claims

1. A parking mechanism for an electromechanical braking system, characterized in that, It includes an iron core shaft, a telescopic assembly located on the iron core shaft, a sliding assembly cooperating with the telescopic assembly, the sliding assembly being movably connected to a pawl rocker arm; an electromagnet located at one end of the iron core shaft; the pawl rocker arm engaging with the parking ratchet through the action of the iron core shaft, the telescopic assembly and the electromagnet.

2. The parking mechanism of an electromechanical braking system according to claim 1, characterized in that, The iron core shaft is fixedly connected to an iron core, and the iron core shaft is the extension of the iron core away from the electromagnet.

3. The parking mechanism of an electromechanical braking system according to claim 1, characterized in that, The telescopic component is a spring.

4. The parking mechanism of an electromechanical braking system according to claim 2, characterized in that, The sliding component is a slider, and a slider pin is provided on the slider. One end of the pawl rocker arm is connected to the slider pin, and the other end of the pawl rocker arm is connected to a rocker arm pin.

5. The parking mechanism of an electromechanical braking system according to claim 4, characterized in that, The electromagnet is a bidirectional holding electromagnet.

6. The parking mechanism of an electromechanical braking system according to claim 4, characterized in that, The parking ratchet is connected to the motor output shaft.

7. The parking mechanism of an electromechanical braking system according to claim 4, characterized in that, The upper end of the iron core shaft near the slider is provided with a stepped surface or a retaining spring, which is located between the iron core and the slider.

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