Parking brake control methods, systems and motor vehicles

Abstract

This invention relates to a parking brake control method, system, and motor vehicle. It utilizes a vehicle controller to jointly control the execution module of the electronic parking system and the motor torque to solve problems such as vehicle roll-off on inclines and dragging / jamming on flat roads. When the parking or temporary stop function of the electronic parking system is released, it monitors real-time changes in the vehicle's gear position and motor speed to execute different motor torque-increasing gradient logics, ensuring both safety on inclines and comfort on flat roads.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, specifically to parking brake control methods, systems, and motor vehicles. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In new energy vehicles, pneumatic parking brakes generally use either mechanical or electronic parking brakes. Electronic parking brakes are highly intelligent but have lower calibration precision, which can easily cause problems such as vehicle rollback when starting on an incline and dragging and jerking on flat roads. On the other hand, the actuators of electronic parking brake systems generally use electronic parking brake memory valves, which do not have dynamic anti-lock braking function. When the tire adhesion coefficient is low, the rear wheel slip ratio cannot be effectively controlled when the vehicle is driving at high speed and performing emergency parking braking. At this time, when subjected to a small yaw moment, it is easy to cause sideslip and fishtailing. Summary of the Invention

[0004] To address the technical problems mentioned above, this invention provides a parking brake control method, system, and vehicle. The system uses a vehicle controller to jointly control the EPB execution module and motor torque, resolving issues such as vehicle roll-off on inclines and dragging / jamming on flat roads. When the EPB parking or temporary stop function is released, real-time changes in the vehicle's gear position and motor speed are monitored to execute different motor torque-increasing gradient logics, ensuring both safety during incline starts and comfort during flat road starts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of the present invention provides a parking brake control method, comprising the following steps:

[0007] Acquire the vehicle's longitudinal acceleration signal and gear information and determine the road surface slope;

[0008] When the road slope is less than the first set value, it is a flat road or downhill condition. At this time, the accelerator pedal opening is greater than the second set value, the parking or temporary stop function is released, and the vehicle starts.

[0009] When the road slope is not less than the first set value, it is an uphill condition. At this time, the accelerator pedal opening is greater than the third set value and the motor torque is greater than the calibration value under the corresponding slope. The parking or temporary stop function is released and the vehicle starts.

[0010] When the external vehicle speed of the anti-lock braking system is greater than the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hard-wire signal is greater than the fifth set value, the vehicle controller issues an external braking request under the premise that the vehicle service braking system is fault-free, and the service braking system performs emergency braking according to the received external braking request.

[0011] If the vehicle's service braking system malfunctions, the vehicle controller will control the electronic parking system to apply parking brakes to the rear wheels and control the braking force based on the slip ratio and wheel deceleration of the two rear wheels.

[0012] Furthermore, before determining the road slope based on the longitudinal acceleration signal and gear information, the system sequentially checks whether the air pressure values ​​in the pre- and post-braking circuits are greater than the set values, the fault status of the electronic parking system execution module, the activation status of the parking or temporary parking function, and the vehicle's gear position.

[0013] Furthermore, the longitudinal acceleration signal and gear information determine the road surface slope, specifically as follows:

[0014] When the longitudinal acceleration signal is positive and the vehicle is in forward gear, or when the longitudinal acceleration signal is negative and the vehicle is in reverse gear, the slope is negative.

[0015] The slope is positive when the longitudinal acceleration signal is positive and the vehicle is in reverse gear, or when the longitudinal acceleration signal is negative and the vehicle is in forward gear.

[0016] Furthermore, after the vehicle starts, if the vehicle is in forward gear and the motor speed is negative, or if the vehicle is in reverse gear and the motor speed is positive, it is determined to be an uphill condition. The motor torque is then controlled to execute the set maximum torque increase gradient to remedy the vehicle's rolling backward.

[0017] Furthermore, after the vehicle starts, when the vehicle is in forward gear and the motor speed is non-negative, or when the vehicle is in reverse gear and the motor speed is non-positive, it is determined to be a flat road or downhill condition, and the motor torque is controlled to execute the set torque increase gradient.

[0018] Furthermore, when the outgoing vehicle speed of the anti-lock braking system exceeds the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hardwire signal exceeds the fifth set value, it is assumed that the driver has a dynamic parking intention.

[0019] Furthermore, when the vehicle speed of the anti-lock braking system is less than the sixth set value and the anti-lock function of the service braking system is not activated, the electronic parking system will activate the parking pull-up function.

[0020] A second aspect of the present invention provides a system for implementing the above method, comprising a brake pedal opening sensor, an accelerator pedal opening sensor, and a gear position controller respectively connected to a vehicle controller. The vehicle controller is connected to an anti-lock braking system (ABS) controller, an electronic stability controller, and corresponding instruments via a vehicle CAN network. The vehicle controller is connected to a motor controller via a powertrain CAN network. The motor controller is connected to a motor. The vehicle controller is connected to an electronic parking brake module via hardwired drive. The ABS controller and the electronic stability controller are connected to a yaw rate sensor.

[0021] The longitudinal acceleration signal of the vehicle acquired by the yaw rate sensor and the gear information acquired by the gear position controller are sent to the vehicle controller to determine the road slope.

[0022] If the road slope is less than the first set value and the value of the accelerator pedal opening sensor is greater than the second set value, the parking or temporary stop function is released and the vehicle starts moving.

[0023] If the road slope is not less than the first set value, the accelerator pedal opening sensor value is greater than the third set value, and the motor torque is greater than the calibration value under the corresponding slope, the parking or temporary stop function is released, and the vehicle starts.

[0024] When the external vehicle speed of the anti-lock braking system is greater than the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hard-wire signal is greater than the fifth set value, the vehicle controller issues an external braking request under the premise that the vehicle service braking system is fault-free, and the service braking system performs emergency braking according to the received external braking request.

[0025] If the vehicle's service braking system malfunctions, the vehicle controller will control the electronic parking system to apply parking brakes to the rear wheels and control the braking force based on the slip ratio and wheel deceleration of the two rear wheels.

[0026] A third aspect of the invention provides a motor vehicle equipped with the above-described system.

[0027] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects:

[0028] 1. By monitoring and performing logical operations on the vehicle gear and motor speed in real time through the obtained road slope, the electronic parking brake module and motor torque are jointly controlled. Different motor torque increase gradients are executed when the parking or temporary stop function is released, which solves the problem of vehicle slipping on slopes and lurching on flat roads.

[0029] 2. When performing emergency parking braking under low-friction road conditions, the vehicle controller prioritizes the use of the service braking system. If the service braking system fails, the electronic parking brake module is driven to perform dynamic anti-lock braking control, which solves the problem of sideslip and fishtailing caused by rear axle lock-up on low-friction roads, improves the safety of parking braking of pure electric vehicles, and reduces economic losses caused by traffic accidents. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0031] Figure 1 This is a schematic diagram of the parking brake control system architecture provided in one or more embodiments of the present invention;

[0032] Figure 2 This is a schematic diagram of ramp start control logic provided in one or more embodiments of the present invention;

[0033] Figure 3 This is a schematic diagram of the dynamic parking brake control logic provided in one or more embodiments of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] As described in the background section, electronic parking systems do not have dynamic anti-lock braking functionality. When the vehicle is traveling at high speed under low-traction conditions, the rear wheel slip ratio cannot be effectively controlled during emergency parking braking. At this time, when subjected to a small yaw moment, the vehicle is prone to sideslip and fishtailing.

[0037] Therefore, the following embodiments provide a parking brake control method, system, and vehicle. The vehicle controller jointly controls the EPB execution module and motor torque to solve problems such as vehicle roll-off on slopes and dragging or jerking on flat roads. When the EPB parking or temporary stop function is released, the real-time changes in the vehicle's gear position and motor speed are monitored to execute different motor torque-increasing gradient logics, ensuring both safety during slope starts and comfort during flat road starts.

[0038] When in dynamic parking mode, the vehicle brakes are applied first through the external brake request function (XBR) to ensure anti-lock braking during emergency braking. If the external brake request function cannot be executed due to a malfunction of the vehicle brakes, the rear wheels are braked through the EPB execution module. The rear wheel slip ratio and wheel deceleration are further monitored and controlled to avoid the problem of sideslip and fishtailing caused by rear wheel lock-up, thereby reducing the safety risks of dynamic parking under low-adhesion conditions of pure electric vehicles.

[0039] Terminology Explanation:

[0040] EPB (Electrical Park Brake) refers to the electronic control of the parking brake.

[0041] Low-adhesion conditions refer to conditions where the vehicle tire adhesion coefficient is low, such as on icy or snowy roads.

[0042] Example 1:

[0043] like Figure 1 As shown, the parking brake control system includes a brake pedal opening sensor, an accelerator pedal opening sensor, and a gear position controller (integrated eP switch) connected to the vehicle control unit (VCU). The VCU is connected to the ABS (anti-lock braking system) + ESC (electronic stability control) controller and instrument cluster via the vehicle CAN network. The VCU is also connected to the motor controller (MCU) via the powertrain CAN network. The MCU is connected to the motor. The VCU is connected to the EPB (efficiency brake) actuator module via hard-wired drive. The ABS + ESC controller is connected to the yaw rate sensor. The EPB actuator module includes an intake solenoid valve, a check valve, a pressure holding solenoid valve, and a pressure reducing solenoid valve.

[0044] like Figure 2 As shown, this relates to the control of safety and comfort during hill starts.

[0045] When starting the vehicle on a slope or flat road, first check if the air pressure in the front and rear brake circuits is greater than the set value. This is to prevent insufficient air pressure from causing the parking brake to not fully release, which could lead to brake drag during driving. If the air pressure in the circuit is greater than the set value, proceed to the next step; otherwise, end the process.

[0046] When the EPB execution module is fault-free, the parking or temporary parking function is activated, and the vehicle is not in neutral (N) gear, the slope of the road surface where the vehicle is located is monitored and different release logics are executed. The road slope is calculated in real time by the VCU (Vehicle Control Unit, the central controller of electric vehicles) through the longitudinal acceleration signal collected by the yaw rate sensor and the current gear.

[0047] When the longitudinal acceleration signal is positive (vehicle facing downhill) and the vehicle is in D gear, or when the longitudinal acceleration signal is negative (vehicle facing uphill) and the vehicle is in R gear, the calculated slope is negative; when the longitudinal acceleration signal is positive (vehicle facing downhill) and the vehicle is in R gear, or when the longitudinal acceleration signal is negative (vehicle facing uphill) and the vehicle is in D gear, the calculated slope is positive.

[0048] When the slope of the road surface where the vehicle is located is less than the first set value, it is judged to be a flat road or downhill condition, and there is no risk of rolling back when starting. At this time, when the accelerator pedal opening is greater than the second set value, the parking or temporary stop function is released and the vehicle starts. The calibration of the first and second set values ​​should ensure the comfort of starting the parking or temporary stop function and avoid the vehicle from jerking.

[0049] When the slope of the road surface where the vehicle is located is greater than or equal to the first set value, it is judged as an uphill condition. At this time, when the accelerator pedal opening is greater than the third set value and the real-time torque of the motor is greater than the calibration value of the corresponding slope, the parking or temporary stop function is released and the vehicle starts. The corresponding motor torque calibration value under different slopes must ensure that the vehicle does not roll back when starting, and also avoid the problem of the parking or temporary stop function being released late or not being released due to the calibration value being too large.

[0050] After the vehicle starts, the VCU adjusts the torque increase gradient requested by the motor by monitoring the vehicle's current gear and the motor's real-time speed. When the vehicle is in D gear and the motor's real-time speed is negative, or when the vehicle is in R gear and the motor's real-time speed is positive, it is determined to be an uphill condition. In this case, the VCU executes the maximum torque increase gradient (calibrated value) when requesting motor torque to remedy the vehicle's rolling backward. When the vehicle is in D gear and the motor's real-time speed is non-negative, or when the vehicle is in R gear and the motor's real-time speed is non-positive, it is determined to be a flat road or downhill condition. In this case, the VCU executes the normal torque increase gradient when requesting motor torque.

[0051] like Figure 3 As shown, dynamic parking brake safety control.

[0052] When the vehicle performs emergency parking braking under dynamic driving conditions on a low-friction surface, if the external vehicle speed of the ABS system (external vehicle speed refers to the minimum vehicle speed at which the ABS system takes effect) is greater than the fourth set value, the VCU monitors the external parking enable message signal and the hard-wired signal of the eP switch from the gear position controller (integrated eP switch).

[0053] When the VCU receives the parking enable message signal and the eP switch hard-wire signal for a time longer than the fifth set value, it determines that the driver intends to dynamically park. At this time, the VCU judges whether there is a fault in the service braking system (including but not limited to ABS+ESC, EBS, EBS+ESC, etc.). If there is no fault in the service braking system, the VCU sends an external braking request message. After receiving the message, the service braking system executes an emergency braking command while ensuring that the ABS anti-lock braking function operates normally.

[0054] If the service braking system is currently malfunctioning, the VCU will drive the EPB execution module to dynamically park the rear wheels. At the same time, it will monitor and regulate the slip ratio and wheel deceleration of the two rear wheels in real time. Since the parking air chambers of the two rear wheels are controlled by the same air source, ABS low-select control is required. If the slip ratio and wheel deceleration of any rear wheel exceed the set threshold, the two rear wheels will be regulated synchronously to avoid the problem of vehicle skidding and tail-swing caused by rear axle lock-up.

[0055] When the ABS vehicle speed is less than the sixth set value and the ABS function of the service braking system is not activated, the VCU drives the EPB execution module to start the parking pull-up function.

[0056] The aforementioned system uses the VCU to calculate the slope in real time, monitors and performs logical operations on the vehicle's gear position and the motor's real-time speed, and achieves joint control of the EPB execution module and motor torque. When the parking or temporary stop function is released, different motor torque increase gradients are executed, solving the problem of vehicle slippage on slopes and jerking on flat roads. At the same time, when the vehicle performs emergency parking braking under low-friction road conditions, the VCU prioritizes the service braking system. If the service braking system fails, the EPB execution module is driven to perform dynamic parking anti-lock control, solving the problem of sideslip and fishtailing caused by rear axle lock-up on low-friction roads, improving the safety of parking braking of pure electric vehicles, and thus reducing the economic losses caused by traffic accidents.

[0057] Example 2:

[0058] The parking brake control method based on the above system includes the following steps:

[0059] Determine the road slope based on longitudinal acceleration signals and gear information;

[0060] When the road slope is less than the first set value, it is a flat road or downhill condition. At this time, the accelerator pedal opening is greater than the second set value, the parking or temporary stop function is released, and the vehicle starts.

[0061] When the road slope is not less than the first set value, it is an uphill condition. At this time, the accelerator pedal opening is greater than the third set value and the motor torque is greater than the calibration value under the corresponding slope. The parking or temporary stop function is released and the vehicle starts.

[0062] When the speed of the vehicle outside the ABS system exceeds the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hard wire signal exceeds the fifth set value, the vehicle controller will issue an external braking request under the premise that the vehicle service braking system is fault-free, and the service braking system will perform emergency braking according to the received external braking request.

[0063] If the vehicle's service braking system malfunctions, the vehicle controller will control the electronic parking system to apply parking brakes to the rear wheels and control the braking force based on the slip ratio and wheel deceleration of the two rear wheels.

[0064] By calculating the slope gradient, the vehicle gear and motor speed are monitored and logically calculated in real time, enabling joint control of the electronic parking brake module and motor torque. Different motor torque increase gradients are executed when the parking or temporary stop function is released, solving the problem of vehicle slippage on slopes and lurching on flat roads.

[0065] Meanwhile, when the vehicle performs emergency parking braking under low-friction road conditions, the vehicle controller prioritizes the use of the service braking system. In the event of a failure of the service braking system, the electronic parking brake module is driven to perform dynamic parking anti-lock braking control. This solves the problem of sideslip and fishtailing caused by rear axle lock-up on low-friction roads, improves the safety of parking braking of pure electric vehicles, and thus reduces the economic losses caused by traffic accidents.

[0066] Example 3

[0067] A motor vehicle equipped with the system described in Embodiment 1.

[0068] By calculating the slope gradient, the vehicle gear and motor speed are monitored and logically calculated in real time, enabling joint control of the electronic parking brake module and motor torque. Different motor torque increase gradients are executed when the parking or temporary stop function is released, solving the problem of vehicle slippage on slopes and lurching on flat roads.

[0069] Meanwhile, when the vehicle performs emergency parking braking under low-friction road conditions, the vehicle controller prioritizes the use of the service braking system. In the event of a failure of the service braking system, the electronic parking brake module is driven to perform dynamic parking anti-lock braking control. This solves the problem of sideslip and fishtailing caused by rear axle lock-up on low-friction roads, improves the safety of parking braking of pure electric vehicles, and thus reduces the economic losses caused by traffic accidents.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A parking brake control method, characterized by, Includes the following steps: Acquire the vehicle's longitudinal acceleration signal and gear information and determine the road slope; before determining the road slope, sequentially check whether the air pressure values ​​of the pre- and post-braking circuits are greater than the set value, the fault status of the electronic parking system execution module, the activation status of the parking or temporary parking function, and the vehicle's gear. When the road slope is less than the first set value and the accelerator pedal opening is greater than the second set value, the parking or temporary stop function is released and the vehicle starts moving. When the road slope is not less than the first set value, the accelerator pedal opening is greater than the third set value, and the motor torque is greater than the calibration value under the corresponding slope, the parking or temporary stop function is released, and the vehicle starts. When the external vehicle speed of the anti-lock braking system exceeds the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hard-wire signal exceeds the fifth set value, under the premise that the vehicle's service braking system is fault-free, an external braking request is issued, and the service braking system performs emergency braking according to the received external braking request. If the vehicle's service braking system malfunctions, the vehicle controller will control the electronic parking system to apply parking brakes to the rear wheels and control the braking force based on the slip ratio and wheel deceleration of the two rear wheels. When the vehicle speed of the anti-lock braking system is less than the sixth set value and the anti-lock function of the service braking system is not activated, the electronic parking system will activate the parking pull-up function.

2. The parking brake control method of claim 1, wherein, The road slope is determined based on the longitudinal acceleration signal and gear information, specifically as follows: When the longitudinal acceleration signal is positive and the vehicle is in forward gear, or when the longitudinal acceleration signal is negative and the vehicle is in reverse gear, the slope is negative. The slope is positive when the longitudinal acceleration signal is positive and the vehicle is in reverse gear, or when the longitudinal acceleration signal is negative and the vehicle is in forward gear.

3. The parking brake control method as described in claim 1, characterized in that, After the vehicle starts, if the vehicle is in forward gear and the motor speed is negative, or if the vehicle is in reverse gear and the motor speed is positive, it is determined to be an uphill condition. The motor torque is controlled to execute the set maximum torque increase gradient to remedy the vehicle's rolling backward.

4. The parking brake control method as described in claim 1, characterized in that, After the vehicle starts, if the vehicle is in forward gear and the motor speed is non-negative, or if the vehicle is in reverse gear and the motor speed is non-positive, it is determined to be a flat road or downhill condition, and the motor torque is controlled to execute the set torque increase gradient.

5. The parking brake control method as described in claim 1, characterized in that, When the outgoing vehicle speed of the anti-lock braking system exceeds the fourth set value, and the time for the vehicle controller to receive the parking enable message signal and the eP switch hardwire signal exceeds the fifth set value, it is assumed that the driver has a dynamic parking intention.

6. A system for implementing the method according to any one of claims 1-5, characterized in that, This includes a brake pedal opening sensor, an accelerator pedal opening sensor, and a gear position controller, all connected to the vehicle controller. The vehicle controller is connected to the anti-lock braking system (ABS) controller, electronic stability controller, and corresponding instruments via the vehicle CAN network. The vehicle controller is also connected to the motor controller via the powertrain CAN network, and the motor controller is connected to the motor. The vehicle controller is connected to the electronic parking brake module via hardwired drive. The ABS controller and electronic stability controller are connected to the yaw rate sensor.

7. A motor vehicle, characterized in that, It is equipped with the system as described in claim 6.

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