Brake control system, brake control method, brake control device and vehicle

Abstract

The application discloses a kind of brake-by-wire system vehicle stationary braking limit control method, equipment and vehicle, belong to vehicle technical field.The method comprises: in the case where vehicle speed is less than low-speed threshold, obtain vehicle state;According to the vehicle state, determine the gradient of brake torque change;According to the gradient of brake torque change, vehicle control is carried out.The application is used to limit the brake torque request of vehicle low speed and stationary state under the premise of avoiding the occurrence of unexpected vehicle coasting, to reduce the power consumption of the whole vehicle, so that the driver has better NVH experience and reduces the power consumption of the whole vehicle, while limiting the increase and release torque gradient of brake, reduces the working speed of brake-by-wire motor to reduce brake noise.

Description

Technical Field

[0001] This invention belongs to the field of vehicle technology, specifically relating to a method, device, and vehicle for limiting vehicle stationary braking in a brake-by-wire system. Background Technology

[0002] Currently, most new energy vehicles use a brake-by-wire system, where the vehicle's power supply powers the brake-by-wire motor for braking assistance. New energy vehicles use an electric drive system, resulting in a relatively quiet environment at low speeds and when stationary. However, since braking is necessary even when stationary to prevent rolling, excessive braking torque at low speeds and when stationary can generate significant noise and increase overall energy consumption. Summary of the Invention

[0003] One objective of this invention is to provide a method, device, and vehicle for limiting vehicle braking in a brake-by-wire system, which can solve the technical problems in the prior art of generating significant noise and increasing normal power consumption due to excessive braking torque at low speeds and when stationary.

[0004] According to a first aspect of the present invention, a method for limiting vehicle stationary braking in a brake-by-wire system is provided, comprising:

[0005] When the vehicle speed is less than the low speed threshold, obtain the vehicle status;

[0006] The gradient of the braking torque change is determined based on the vehicle's condition;

[0007] Vehicle control is performed based on the gradient of the braking torque change.

[0008] Optionally, determining the gradient of the braking torque change based on the vehicle state includes:

[0009] Determine the target deceleration when the vehicle is under braking;

[0010] When the brake pedal force reaches the preset target, the braking capacity is increased to the level of conventional braking.

[0011] When the brake pedal force does not reach the preset target, the gradient of the increase in braking torque is determined according to the first limiting condition and the target deceleration, wherein the first limiting condition is that the braking time is less than the first preset time.

[0012] Optionally, determining the gradient of the increase in braking torque based on the first constraint and the target deceleration includes:

[0013] The maximum value of the gradient of the increase in braking torque is determined based on the target deceleration and the first constraint condition;

[0014] The gradient of the increase in braking torque is determined based on the maximum value of the gradient of the increase in braking torque and a pre-set first coefficient.

[0015] Optionally, determining the gradient of the braking torque change based on the vehicle state includes:

[0016] Determine the target acceleration while the vehicle is in the state of starting and releasing the brakes;

[0017] Based on the second constraint and the target acceleration, the gradient of the reduction in braking torque is determined, wherein the second constraint is that the time to release the brake is less than a second preset time.

[0018] Optionally, determining the gradient of the reduction in braking torque based on the second constraint and the target acceleration includes:

[0019] The minimum value of the gradient of the reduction in braking torque is determined based on the target acceleration and the second constraint.

[0020] The gradient of the braking torque reduction is determined based on the minimum value of the gradient of the braking torque reduction and a pre-set second coefficient.

[0021] Optionally, determining the gradient of the braking torque change based on the vehicle state includes:

[0022] If no wheel speed change is detected within the target time, the braking torque intensity of the vehicle is limited to the braking torque intensity value of the pre-set static braking limit function, and the gradient of the increase in the braking torque of the vehicle is limited to the gradient value of the increase in the braking torque of the pre-set static braking limit function.

[0023] Optionally, the method further includes:

[0024] If vehicle movement is detected during parking restrictions, a higher braking intensity limit will be used to prevent the vehicle from rolling away until the vehicle is next powered on and restarted.

[0025] If vehicle movement is detected again, conventional braking will be used until the vehicle is powered on and restarted, and the static braking limitation function of the vehicle will be disabled.

[0026] Optionally, the method further includes:

[0027] If a fault is detected in the wheel speed signal of the vehicle, the static braking limitation function of the vehicle shall be disabled.

[0028] According to a second aspect of the present invention, an electronic device is provided, including a processor and a memory, the memory storing a program or instructions executable on the processor, the program or instructions, when executed by the processor, implementing the steps of the vehicle stationary braking limit control method of the brake-by-wire system as described in the first aspect of the present invention.

[0029] According to a third aspect of the present invention, a vehicle is provided, including an electronic device as described in the second aspect of the present invention.

[0030] The beneficial effects of the present invention are as follows: The present invention is used to limit the excessive braking torque request of the vehicle at low speed and when stationary, so as to provide the driver with a better NVH experience and reduce the overall vehicle power consumption, while avoiding the vehicle from rolling away unexpectedly. This is done by limiting the braking torque gradient and reducing the operating speed of the brake-by-wire motor to reduce braking noise. Attached Figure Description

[0031] Figure 1 This is a flowchart of the vehicle stationary braking limit control method of the brake-by-wire system of the present invention. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0033] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0034] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0036] In the specification of this invention, the terms "first" and "second" may explicitly or implicitly include one or more of the same feature. In the description of this invention, unless otherwise stated, "multiple" means two or more. Furthermore, in the specification, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0037] like Figure 1 As shown in the figure, this embodiment introduces a vehicle stationary braking limit control method for a brake-by-wire system, including steps 1100-1300.

[0038] Step 1100: Obtain the vehicle status when the vehicle speed is less than the low speed threshold.

[0039] When the vehicle speed is below the low-speed threshold, the vehicle's static braking limitation function is activated to limit the braking torque and its variation gradient when the vehicle is at low speeds. It must also meet safety requirements to prevent rollover. When the vehicle is stationary, it should maintain the braking intensity specified by regulations, for example, not lower than the equivalent of 500N producing 6.43 m / s². The low-speed threshold can be set to 2 km / h; when the vehicle speed is below 2 km / h, the vehicle's static braking limitation function is activated.

[0040] Step 1200: Determine the gradient of the braking torque change based on the vehicle state.

[0041] The gradient of braking torque change includes the gradient of braking torque increase and the gradient of braking torque decrease. The gradient of braking torque change reflects the rate of increase or decrease of braking torque change; a gentle gradient means that the torque change is slow.

[0042] Vehicle status includes applying and releasing the brakes, and relevant regulations specify the timing for both. The gradient of the braking torque change affects the timing of both braking application and release. Therefore, determining the gradient of the braking torque change based on the vehicle status ensures that the timing of braking application and release complies with relevant regulations, thereby guaranteeing safety.

[0043] Step 1300: Perform vehicle control based on the gradient of the braking torque change.

[0044] After determining the gradient of the braking torque change, the torque is controlled according to this gradient of braking torque change.

[0045] This invention aims to improve the driver's NVH (Noise, Vibration, Harshness) experience and reduce overall vehicle energy consumption when the vehicle is at low speed and stationary. It limits excessive braking torque requests at low speeds and when the vehicle is stationary, while preventing unexpected vehicle rollover. Simultaneously, it limits the increase and release torque gradient during braking and reduces the operating speed of the brake-by-wire motor to decrease braking noise.

[0046] In this embodiment, step 1200 includes steps 1210-1230.

[0047] Step 1210: Determine the target deceleration when the vehicle is under braking.

[0048] Step 1220: When the brake pedal force reaches the preset target, the braking capacity is increased to the normal braking level.

[0049] Step 1230: When the brake pedal force does not reach the preset target, determine the gradient of the increase in braking torque according to the first limiting condition and the target deceleration, wherein the first limiting condition is that the braking time is less than the first preset time.

[0050] When a braking request is received, the vehicle is considered to be in a braking state. If the brake pedal force reaches a preset target, such as close to 500N, it indicates that the driver's braking request is relatively strong and a collision may be imminent. In this case, braking cannot be restricted, and conventional braking methods should be used to avoid a collision.

[0051] If the brake pedal force does not reach the preset target, it indicates that there is no significant braking demand. In this case, noise can be reduced by limiting the braking gradient. Relevant regulations limit the time for vehicle braking, requiring it not to exceed a certain time, i.e., a first preset time, to prevent accidents caused by delayed braking. For example, the first preset time is 600ms. If the gradient of braking torque change is set unreasonably, it will lead to the vehicle applying brakes for too long, exceeding the relevant regulations.

[0052] The target deceleration can be determined based on the braking request. The time required for the vehicle to apply braking is the time needed to reach the target deceleration. The braking time is related to the target deceleration and the gradient of the braking torque increase. The greater the target deceleration, the longer the braking time will be. For example, to apply a relatively large deceleration of 10 m / s²... 2 If using 28m / s 3 The gradient is expected to be applied in 350ms, which is lower than the regulatory requirement of 600ms and meets the requirements.

[0053] Specifically, step 1230 includes: determining the maximum value of the gradient of the increase in braking torque based on the target deceleration and the first constraint; and determining the gradient of the increase in braking torque based on the maximum value of the gradient of the increase in braking torque and a pre-set first coefficient.

[0054] When braking is applied at the maximum value of the gradient of increasing braking torque, the braking time required to reach the target deceleration is the first preset time.

[0055] Braking is applied by a brushless motor. The larger the gradient, the slower the motor speed and the lower the noise. To improve the driving experience and reduce noise, theoretically, within the legally required range, the larger the gradient of braking torque increase, the better. If minimizing noise is the primary goal, then the maximum value of the braking torque increase gradient should be selected for braking. However, in real-world scenarios, using the maximum value of the braking torque increase gradient may cause the braking time to exceed the first preset time due to various unforeseen circumstances, thus affecting driving safety.

[0056] To address this issue and minimize noise while ensuring safety, this embodiment sets a first coefficient. The gradient of the increase in braking torque is calculated based on the first coefficient and the maximum value of the gradient of the increase in braking torque. When braking is applied using this calculated gradient of the increase in braking torque, the braking time is less than a first preset time, for example, 90% of the first preset time, with the remaining 10% reserved to handle possible unexpected situations.

[0057] This approach ensures that, in the event of an emergency, the braking time complies with relevant regulations, thus guaranteeing driving safety. Furthermore, it minimizes braking noise and enhances the driving experience.

[0058] In this embodiment, step 1200 includes steps 1230-1240.

[0059] Step 1230: Determine the target acceleration when the vehicle is in the state of starting and releasing the brake.

[0060] Step 1240: Determine the gradient of the reduction in braking torque based on the second constraint and the target acceleration, wherein the second constraint is that the time to release the brake is less than a second preset time.

[0061] Regarding brake release, relevant regulations also stipulate the time required for brake release, requiring it to be less than a certain time, namely a second preset time, to prevent delayed brake release. If the gradient of braking torque change is not set appropriately, it can lead to excessively long brake release time, exceeding the regulations. The brake release time is also related to the gradient of braking torque change. By limiting the gradient of braking torque change, the brake release time is ensured to comply with regulations.

[0062] Specifically, step 1240 includes: determining the minimum value of the gradient of the reduction of braking torque based on the target acceleration and the second constraint; and determining the gradient of the reduction of braking torque based on the minimum value of the gradient of the reduction of braking torque and a pre-set second coefficient.

[0063] When control is applied based on the maximum value of the braking torque reduction gradient, the brake release time required to reach the target acceleration is a second preset time. To minimize noise while ensuring safety, a second coefficient is set in this embodiment. The braking torque reduction gradient is calculated based on this second coefficient and the maximum value of the braking torque reduction gradient. When control is applied based on this calculated braking torque reduction gradient, the brake release time is less than the second preset time, with the excess used to handle potential unforeseen circumstances.

[0064] In this embodiment, step 1200 includes: if no wheel speed change is detected within the target time, limiting the braking torque intensity of the vehicle to the braking torque intensity value of the preset static braking limit function, and limiting the gradient of the increase in the braking torque of the vehicle to the gradient value of the increase in the braking torque of the preset static braking limit function.

[0065] If the wheel speed remains unchanged within a certain time, it indicates that the vehicle is in a safe stationary state. This means the vehicle has been completely stationary for a period of time; for example, even if there is a tendency to roll backward on a slope, it is suppressed by the system, and the wheel speed is 0. The braking torque intensity value of the static braking limiting function can meet the braking requirements of the vehicle in a safe stationary state, for example, it can be 7 m / s. 2 By limiting the intensity of the braking torque, unnecessary energy consumption is avoided due to increased braking torque caused by system malfunctions or misoperation.

[0066] The static braking limit function's gradient value for increasing braking torque can respond promptly to braking requests when the brake pedal speed is less than 80 mm / s, covering 99% of situations. This limit will remain effective until the brake pedal is released.

[0067] When the vehicle is stationary, the driver may unintentionally make slight movements or press the brake pedal harder. A gentle gradient limit can filter out these minor actions, preventing the system from frequently adjusting torque and improving the static NVH experience. At the same time, this gradient can respond to normal, conscious braking requests without making the driver feel like they are not pressing the brake pedal at all.

[0068] In this embodiment, the method further includes: if vehicle movement is detected during the parking restriction process, using a higher braking intensity limit to prevent the vehicle from rolling away until the vehicle is powered on and restarted again; if vehicle movement is detected again, using conventional braking until the vehicle is powered on and restarted again, and disabling the static braking restriction function of the vehicle.

[0069] If vehicle movement is detected during parking, indicating that the braking force is insufficient and a higher braking force is needed to prevent further rolling, the system will no longer rely on the original standard limit and will instead use a higher braking torque with a greater safety margin to ensure the vehicle stops rolling.

[0070] If vehicle movement is detected again after applying higher braking intensity, it indicates that the system is still unable to reliably keep the vehicle stationary even with higher braking intensity. This is likely not due to external conditions, but rather an internal system malfunction. In this case, a function degradation is implemented, disabling the vehicle's static braking limitation function. Simultaneously, a backup is activated, using conventional braking. This means the system completely bypasses the optimized static braking logic, employing a more direct and basic, but less comfortable, braking method, such as continuously applying a fixed, large hydraulic pressure, fundamentally preventing the risk of continuous vehicle roll due to repeated failures of the same function.

[0071] The method further includes disabling the vehicle's static braking limit function when a fault is detected in the vehicle's wheel speed signal.

[0072] If the wheel speed signal malfunctions, the change in wheel speed cannot be accurately determined, and therefore the braking torque intensity value and the gradient value of the braking torque increase of the static braking limit function cannot be used. In this case, the static braking limit function should be turned off to improve safety.

[0073] This embodiment introduces an electronic device, including a processor and a memory, wherein the memory stores programs or instructions that can run on the processor, and when the programs or instructions are executed by the processor, they implement the steps of the vehicle stationary braking limit control method of the brake-by-wire system as described in any embodiment of the present invention.

[0074] This embodiment describes a vehicle that includes an electronic device as described in the above embodiments of the present invention.

[0075] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention.

[0076] Those skilled in the art will recognize that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0077] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and equipment can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0078] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0079] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of the embodiments of the present invention, depending on actual needs.

[0080] In addition, the functional modules in the embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0081] If the aforementioned functions are implemented as software functional 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 this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0082] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

[0083] It should be understood that the sequence numbers of the steps in the invention's content and embodiments do not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention. The foregoing description of embodiments of this disclosure has been provided for illustrative and descriptive purposes. The foregoing description is not exhaustive and is not intended to limit this disclosure to the exact form disclosed. Various modifications and variations may exist based on the foregoing teachings, or various modifications and variations may be derived from the practice of this disclosure. These embodiments were chosen and described to illustrate the principles of this disclosure and its practical application, so that those skilled in the art can utilize this disclosure in various implementations and modifications suitable for the specific purpose of the concept.

Claims

1. A method for limiting vehicle stationary braking in a brake-by-wire system, characterized in that, include: When the vehicle speed is less than the low speed threshold, obtain the vehicle status; The gradient of the braking torque change is determined based on the vehicle's condition; Vehicle control is performed based on the gradient of the braking torque change; Determining the gradient of the braking torque change based on the vehicle state includes: Determine the target deceleration when the vehicle is under braking; When the brake pedal force reaches the preset target, the braking capacity is increased to the level of conventional braking. When the brake pedal force does not reach the preset target, the gradient of the increase in braking torque is determined according to the first limiting condition and the target deceleration, wherein the first limiting condition is that the braking time is less than the first preset time. Determining the gradient of the increase in braking torque based on the first constraint and the target deceleration includes: The maximum value of the gradient of the increase in braking torque is determined based on the target deceleration and the first constraint condition; The gradient of the increase in braking torque is determined based on the maximum value of the gradient of the increase in braking torque and a preset first coefficient; Determining the gradient of the braking torque change based on the vehicle state includes: Determine the target acceleration while the vehicle is in the state of starting and releasing the brakes; Based on the second constraint and the target acceleration, the gradient of the reduction in braking torque is determined, wherein the second constraint is that the time to release the brake is less than a second preset time; Determining the gradient of the reduction in braking torque based on the second constraint and the target acceleration includes: The minimum value of the gradient of the reduction in braking torque is determined based on the target acceleration and the second constraint. The gradient of the braking torque reduction is determined based on the minimum value of the gradient of the braking torque reduction and a pre-set second coefficient.

2. The method according to claim 1, characterized in that, Determining the gradient of the braking torque change based on the vehicle state includes: If no wheel speed change is detected within the target time, the braking torque intensity of the vehicle is limited to the braking torque intensity value of the pre-set static braking limit function, and the gradient of the increase in the braking torque of the vehicle is limited to the gradient value of the increase in the braking torque of the pre-set static braking limit function.

3. The method according to claim 2, characterized in that, The method further includes: If vehicle movement is detected during parking restrictions, a higher braking intensity limit will be used to prevent the vehicle from rolling away until the vehicle is next powered on and restarted. If vehicle movement is detected again, conventional braking will be used until the vehicle is powered on and restarted, and the static braking limitation function of the vehicle will be disabled.

4. The method according to claim 3, characterized in that, The method further includes: If a fault is detected in the wheel speed signal of the vehicle, the static braking limitation function of the vehicle shall be disabled.

5. An electronic device, characterized in that, It includes a processor and a memory, the memory storing programs or instructions that can run on the processor, the programs or instructions being executed by the processor to implement the steps of the vehicle stationary braking limit control method for a brake-by-wire system as described in any one of claims 1 to 4.

6. A vehicle, characterized in that, Includes the electronic device described in claim 5.

Images