Hill-start assist control methods, control devices and vehicles to prevent braking drag

Abstract

A hill-start assist control method, control device, and vehicle for preventing brake drag are disclosed. The method includes: when the hill-start assist function is activated, determining whether the accelerator pedal is depressed; if the accelerator pedal is depressed, attenuating a preset braking pressure according to a pressure adjustment coefficient, and providing a target braking pressure to the vehicle based on the attenuated preset braking pressure. This invention attenuates the preset braking pressure according to a pressure adjustment coefficient after the driver depresses the accelerator pedal, reducing the time required to release the target braking pressure and improving the problem of brake drag during vehicle start-up.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and more specifically, to a slope assist control method, control device, and vehicle for preventing brake drag. Background Technology

[0002] When starting on a slope, the brake pressure decreases after the driver releases the brake pedal. If the brake pressure is less than the vehicle's downward force on the slope, the vehicle may roll backward. To address this issue, some vehicles offer a hill start assist function, which maintains brake pressure for a period of time after the driver releases the brake pedal, preventing the driver from becoming flustered and causing the vehicle to roll backward when starting on a slope.

[0003] However, for vehicle systems that use both hydraulic and electric brakes, the electric motor responds quickly. When the hill start assist function is working, if the pressure release rate of the hydraulic brakes is slow after the driver presses the accelerator to output the drive torque, it may cause brake drag when starting. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] To address the shortcomings of existing technologies, the first aspect of this invention proposes a slope-assisted control method to prevent braking drag, the method comprising:

[0006] When the hill start assist function is activated, determine whether the accelerator pedal is pressed;

[0007] If the accelerator pedal is depressed, the preset braking pressure is attenuated according to the pressure adjustment coefficient, and the target braking pressure is provided to the vehicle based on the attenuated preset braking pressure.

[0008] In one embodiment, the method further includes: determining the difference between a preset driving torque and a current driving torque;

[0009] Determine the ratio between the difference and the preset drive torque, and determine the pressure adjustment coefficient based on the ratio.

[0010] In one embodiment, the pressure adjustment coefficient gradually decreases as time increases.

[0011] In one embodiment, the method further includes: controlling the hill start assist function to be turned off when the accelerator pedal is depressed for a first preset time or the driving torque of the vehicle reaches a preset driving torque.

[0012] In one embodiment, the control to disable the ramp assist function includes:

[0013] The target braking pressure is gradually reduced to zero.

[0014] In one embodiment, the method further includes: ensuring that the target braking pressure is within the preset braking pressure range during the attenuation of the preset braking pressure according to the pressure adjustment coefficient.

[0015] In one embodiment, the method further includes: when the hill start assist function is activated, if the accelerator pedal is not depressed, providing the target braking pressure according to the preset braking pressure, and maintaining the target braking pressure until a second preset time.

[0016] In one embodiment, the method further includes: determining the preset drive torque based on the slope of the ramp currently in which the vehicle is located.

[0017] In one embodiment, the method further includes: determining whether the activation conditions for the ramp assist function are met, and activating the ramp assist function when the activation conditions are met.

[0018] Another aspect of the present invention provides a ramp assist control device for preventing braking drag. The control device includes a memory and a processor. The memory stores a computer program that is run by the processor. When the computer program is run by the processor, it executes the ramp assist control method for preventing braking drag as described above.

[0019] In another aspect, the present invention provides a vehicle that includes a hill-start assist control device for preventing brake drag as described above.

[0020] The hill start assist control method, control device and vehicle of the present invention reduce the preset braking pressure of the hill start assist function according to the pressure adjustment coefficient after the driver presses the accelerator pedal, thereby reducing the time required for the target braking pressure to be released and improving the problem of braking drag when the vehicle starts. Attached Figure Description

[0021] The above and other objects, features, and advantages of the present invention will become more apparent from the more detailed description of embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate embodiments of the invention and form part of the specification. They are used together with the embodiments to explain the invention and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same parts or steps.

[0022] Figure 1 A schematic flowchart of a ramp auxiliary control method for preventing braking drag according to an embodiment of the present invention;

[0023] Figure 2 A logic diagram of an anti-braking drag ramp auxiliary control method according to an embodiment of the present invention is shown;

[0024] Figure 3 This is a graph showing the changes in vehicle speed, braking pressure, and driving torque during the implementation of a ramp assist control method according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic block diagram of a ramp assist control device for preventing braking drag according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0027] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0028] It should be understood that this application can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0030] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solution proposed in this application. Optional embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0031] The following description, with reference to the accompanying drawings, outlines an embodiment of the slope assistance control method, control device, and vehicle for preventing braking drag. First, refer to... Figure 1 , Figure 1 A schematic flowchart of a ramp assist control method 100 for preventing braking drag according to an embodiment of the present invention is shown. The ramp assist control method 100 for preventing braking drag according to an embodiment of the present invention includes:

[0032] In step S110, when the hill start assist function is activated, it is determined whether the accelerator pedal is pressed.

[0033] In step S120, if the accelerator pedal is depressed, the preset braking pressure is attenuated according to the pressure adjustment coefficient, and the target braking pressure is provided to the vehicle based on the attenuated preset braking pressure.

[0034] The hill start assist control method 100 for preventing brake drag in this embodiment of the invention attenuates the preset braking pressure of the hill start assist function according to the pressure adjustment coefficient after the driver presses the accelerator pedal, thereby reducing the time required to release the target braking pressure and improving the problem of brake drag when the vehicle starts.

[0035] In this embodiment of the invention, hill start assist activation means that after the driver releases the brake pedal, the hill start assist function maintains braking pressure to prevent the vehicle from rolling backward on a slope. Specifically, the activation conditions for hill start assist can be determined based on the vehicle's current state information, thereby deciding whether to activate the hill start assist function. The hill start assist function is used to provide the vehicle with a target braking pressure.

[0036] Specifically, the system can acquire current vehicle status information from sensors such as torque sensor, wheel speed sensor, acceleration sensor, brake displacement sensor, master cylinder pressure sensor, EPB (Electronic Parking Brake) status sensor, gear position sensor, and throttle depth sensor. The torque sensor acquires the vehicle's drive torque, the wheel speed sensor acquires the four-wheel speed, the acceleration sensor acquires the vehicle's longitudinal acceleration and monitors the gradient, the brake displacement sensor acquires the driver's braking demand, the master cylinder pressure sensor acquires the master cylinder pressure, the EPB status sensor acquires the EPB status, the gear position sensor acquires the gear signal, and the throttle depth sensor acquires changes in throttle depth. Based on the signals from these sensors, relevant information about the current road, vehicle, and driver can be obtained, thereby determining whether the vehicle is in a hill start condition and whether to activate the hill start assist function.

[0037] For example, the hill-start assist function can be activated when it is determined that the vehicle's total driving force is less than or equal to the vehicle's roll-off force on a slope. When the vehicle is stationary on the slope, the roll-off force equals the component of the vehicle's weight along the slope downwards minus the frictional force along the slope upwards; when the vehicle begins to move normally, the roll-off force equals the component of the vehicle's weight along the slope downwards plus the frictional force along the slope downwards. If the total driving force is less than or equal to the roll-off force, it is determined that the vehicle will enter a rolling state. By activating the hill-start assist function, a target braking pressure can be provided to the vehicle, preventing the vehicle from rolling away due to a continuous decrease in braking pressure.

[0038] like Figure 2 As shown, when the hill start assist function is activated, it is determined whether the accelerator pedal is depressed. If the accelerator pedal is depressed, the preset braking pressure of the hill start assist function is attenuated according to the pressure adjustment coefficient, and the target braking pressure is provided based on the attenuated preset braking pressure, where the pressure adjustment coefficient is less than 1.

[0039] The preset braking pressure refers to the braking pressure value calibrated for different slopes to prevent the vehicle from rolling backwards. As the driving torque gradually increases after the accelerator pedal is pressed, the target braking pressure required to prevent the vehicle from rolling backwards gradually decreases. Therefore, the preset braking pressure can be attenuated. This ensures that the vehicle does not roll backwards and reduces the time required for the target braking pressure to be released after the hill start assist function is activated, thereby improving the problem of braking sluggishness when starting the vehicle.

[0040] In one embodiment, the difference between a preset drive torque and the current drive torque can be determined, and the ratio between this difference and the preset drive torque can be determined. Based on this ratio, a pressure adjustment coefficient can be determined, i.e.:

[0041]

[0042] Here, the preset drive torque is the drive torque threshold for activating the hill start assist function, and k is a preset constant. For example, the preset drive torque can be determined based on the gradient of the current slope of the hill, ensuring that the vehicle does not roll back after the hill start assist function is activated. As time increases, the difference between the current drive torque and the preset drive torque gradually decreases, thus the pressure adjustment coefficient gradually decreases, and the attenuation of the preset braking pressure gradually increases. This allows the target braking pressure and the gradually increasing drive torque to complement each other, reducing the target braking pressure as quickly as possible while ensuring that the vehicle does not roll back.

[0043] For example, the pressure adjustment coefficient can also be other coefficients that gradually decrease over time, so that the gradual attenuation of the target braking pressure matches the gradual increase of the driving torque.

[0044] When the accelerator pedal is depressed for a first preset time, or when the vehicle's drive torque reaches a preset drive torque, the hill start assist function is deactivated. After deactivating the hill start assist function, the target braking pressure is gradually reduced to zero. Because the target braking pressure has already been attenuated in this embodiment of the invention, the time required to gradually reduce the target braking pressure to zero is less compared to the case without attenuation, thereby improving the problem of braking sluggishness when starting the vehicle.

[0045] For example, during the process of attenuating the preset braking pressure of the hill start assist function according to the pressure adjustment coefficient, it is also necessary to ensure that the target braking pressure (i.e., the attenuated preset braking pressure) is within the preset braking pressure range. The preset braking pressure range can be a pre-calibrated braking pressure range, and it can be related to properties such as the gradient of the current hill. Ensuring that the target braking pressure is within the preset braking pressure range ensures that the vehicle will not roll away due to the attenuation of the target braking pressure. For example, if the target braking pressure attenuates to the lower limit of the preset braking pressure range, the target braking pressure is maintained at that lower limit and no further attenuation occurs.

[0046] For example, if the accelerator pedal is not depressed during the activation of the hill start assist function, the target braking pressure is provided according to the preset braking pressure and maintained until the second preset time T2, after which the hill start assist function is deactivated.

[0047] See Figure 3 The diagram illustrates the changes in vehicle speed, braking pressure, and driving torque over time during the implementation of the ramp assist control method according to embodiments of the present invention.

[0048] At time T1, the driver depresses the brake pedal, and the vehicle speed gradually decreases until it reaches zero at time T2; simultaneously, the braking pressure gradually increases until it reaches its upper limit at time T2. During the time interval from T2 to T3, the driver keeps the brake pedal depressed, and the braking pressure remains at its upper limit. During this process, the hill start assist function is engaged, but because the brake pedal is depressed and providing braking pressure, the hill start assist function is not yet activated.

[0049] At time T3, the driver releases the brake pedal, and the braking pressure gradually decreases until the hill start assist function is activated at time T4, which begins to provide the target braking pressure to prevent the vehicle from rolling backward.

[0050] At time T5, the driver depresses the accelerator pedal, and the vehicle's drive torque begins to increase. Before the drive torque reaches the torque exit threshold, the target braking pressure of the hill start assist function is appropriately reduced according to the pressure adjustment coefficient to prevent sluggish start. At time T6, when the drive torque reaches the preset drive torque, the hill start assist function is deactivated, and the target braking pressure begins to be released, gradually reducing it to zero. Specifically, the slope of the target braking pressure change after the accelerator pedal is depressed but before the hill start assist function is deactivated is less than the slope of the change after the hill start assist function is deactivated.

[0051] If brake drag prevention is not considered, the target braking pressure of the hill start assist function remains at the solid line in the braking pressure curve, i.e., the preset braking pressure, until the driving torque reaches a preset threshold. At this point, the hill start assist function is deactivated, the braking pressure is released, and the braking pressure needs to be reduced from the preset braking pressure to 0. Conversely, if the anti-brake drag scheme of this embodiment is adopted, the target braking pressure of the hill start assist function is... Figure 3 The dotted line gradually diminishes, approaching the minimum value of the braking pressure range, but still remains within the braking pressure range. This results in a relatively small target braking pressure when the hill start assist function is off, and a shorter time to fully release the braking pressure.

[0052] In summary, the hill start assist control method 100 of this invention reduces the preset braking pressure of the hill start assist function according to the pressure adjustment coefficient after the driver presses the accelerator pedal, thereby reducing the time required for the target braking pressure to be released. This can improve the problem of braking drag when starting the vehicle while avoiding rollback.

[0053] Another embodiment of the present invention provides a ramp assist control device for preventing braking drag. Figure 4This is a schematic diagram of a ramp assist control device according to an exemplary embodiment of the present invention. The ramp assist control device 400 includes a memory 410 and a processor 420. The memory 410 stores a computer program that is executed by the processor 420. When the computer program is executed by the processor 420, it performs the ramp assist control method 100 for preventing braking drag as described above.

[0054] For example, memory 410 is used to store computer programs. Memory 410 may primarily include a program storage area and a data storage area, wherein the program storage area may store the operating system, application programs required for multiple functions, etc. In addition, memory 410 may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart memory card, secure digital card, flash memory card, multiple disk storage devices, flash memory devices, or other volatile solid-state storage devices.

[0055] The processor 420 can be implemented by software, hardware, firmware, or a combination thereof, and can be a circuit, one or more of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a central processing unit (CPU), a controller, a microcontroller, or a microprocessor, thereby enabling the device to perform some or all of the steps of the air conditioning control method 100 in the various embodiments of this application, or any combination thereof.

[0056] This invention also provides a vehicle including the hill start assist control device described above. The vehicle further includes a brake actuator. The hill start assist control device executes the hill start assist control method described above. The brake actuator is connected to the hill start assist control device and is used to perform corresponding pressure build-up, pressure holding, and pressure release actions according to instructions issued by the hill start assist control device to achieve start-up control. Specifically, the vehicle can be a pure electric vehicle, or it can be a hybrid electric vehicle. When the vehicle starts, the motor drive response is relatively fast, and the hill start assist control device can prevent braking drag caused by the hill start assist function.

[0057] To achieve the above objectives, embodiments of the present invention also propose a computer-readable storage medium storing a computer program thereon. When executed by a processor, this program implements the anti-braking drag ramp assist control method described in the embodiments of the present invention. The computer-readable storage medium includes, but is not limited to, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0058] This invention also proposes a computer program that, when executed by a processor, can implement the anti-braking dragging ramp auxiliary control method 100 described in this invention.

[0059] In summary, the hill start assist control device, vehicle, computer-readable storage medium, and computer program of the present invention reduce the preset braking pressure of the hill start assist function according to the pressure adjustment coefficient after the driver presses the accelerator pedal, thereby reducing the time required for the target braking pressure to be released and improving the problem of braking drag when the vehicle starts.

[0060] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0061] Those skilled in the art will recognize that the units and algorithm steps of the various examples 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 implementation should not be considered beyond the scope of this application.

[0062] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0063] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0064] Similarly, it should be understood that, in order to streamline this application and aid in understanding one or more of the various inventive aspects, features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with features fewer than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0065] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or elements of any method or apparatus so disclosed may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0066] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0067] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules according to the embodiments of this application. This application can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such an implementation of this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0068] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0069] The above description is merely a specific embodiment or illustration of the embodiments of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A slope auxiliary control method for preventing braking drag, characterized in that, The method includes: When the hill start assist function is activated, determine whether the accelerator pedal is pressed; If the accelerator pedal is depressed, the preset braking pressure is attenuated according to the pressure adjustment coefficient, and the target braking pressure is provided to the vehicle based on the attenuated preset braking pressure. The method further includes: Determine the difference between the preset drive torque and the current drive torque; Determine the ratio between the difference and the preset drive torque, and determine the pressure adjustment coefficient based on the ratio; The method further includes: When the accelerator pedal is depressed for a first preset time, the hill start assist function is turned off. The control to turn off the hill start assist function includes: gradually reducing the target braking pressure to zero, wherein the slope of the change of the target braking pressure after the accelerator pedal is depressed and before the hill start assist function is turned off is less than the slope of the change after the hill start assist function is turned off.

2. The method according to claim 1, characterized in that, The pressure adjustment coefficient gradually decreases as time increases.

3. The method according to claim 1, characterized in that, Also includes: During the attenuation of the preset braking, the target braking pressure is ensured to remain within the preset braking pressure range.

4. The method according to claim 1, characterized in that, Also includes: When the hill start assist function is activated, if the accelerator pedal is not depressed, the target braking pressure is provided according to the preset braking pressure, and the target braking pressure is maintained until the second preset time.

5. The method according to claim 1, characterized in that, Also includes: The preset drive torque is determined based on the slope of the ramp where the vehicle is currently located.

6. The method according to claim 1, characterized in that, Also includes: Determine whether the activation conditions for the ramp assist function are met. If the activation conditions for the ramp assist function are met, activate the ramp assist function.

7. A ramp auxiliary control device for preventing braking drag, characterized in that, The control device includes a memory and a processor. The memory stores a computer program that is executed by the processor. When the computer program is executed by the processor, it performs the anti-braking dragging ramp auxiliary control method as described in any one of claims 1-6.

8. A vehicle, characterized in that, The vehicle includes the hill-start assist control device for preventing brake drag as described in claim 7.

Images