Method and system for auto hold for electric vehicle

Abstract

To provide an auto hold method for an electric vehicle and an auto hold method for the electric vehicle.SOLUTION: A method includes: generating brake fluid pressure on the basis of an event of depression of a brake pedal of an electric vehicle and recording a brake fluid pressure value; determining whether or not the electric vehicle satisfies a prerequisite of auto hold; executing the auto hold by using a power train if the prerequisite of the auto hold is satisfied; if not, further determining whether or not a hydraulic function of a hydraulic unit of a brake system is normal; taking over the auto hold by using the hydraulic function if it is normal; and taking over the auto hold by using an automatic parking brake (APB) function or an electric parking brake (EPB) function if the hydraulic function has a failure. The auto hold function is not affected if the hydraulic function of the brake system has a failure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to the field of autonomous driving technology, and more particularly, to a method and system for auto-hold for electric vehicles.

Background Art

[0002] AVH (AutoVehicleHold) or auto-hold is a comfort function that enables the vehicle to be held for a long time using brakes on slopes and horizontal surfaces, and then released when a driving start command is detected. This function facilitates driving in situations such as traffic signal stops, slope driving, and traffic jams (especially in the case of vehicles with automatic transmissions).

[0003] Currently, the AVH function typically relies on a hydraulic system to establish pressure to hold the vehicle until the holding time elapses, and then the auto-parking brake (APB) or electric parking brake (EPB) function takes over. However, problems occur when there are defects in the hydraulic system (e.g., defects in solenoid valves), which can affect the auto-hold function.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Based on the problems existing in the prior art, an object of the present disclosure is to provide a method and system for auto-hold for electric vehicles that prevent the auto-hold function from being affected even when there are defects in the hydraulic function.

Means for Solving the Problems

[0005] One aspect of the present disclosure includes an auto-hold method for an electric vehicle, which generates brake hydraulic pressure based on an event that the brake pedal of the electric vehicle is depressed, and records a brake hydraulic pressure value, Determine whether an electric vehicle meets the preconditions for auto hold. If the preconditions for auto hold are met, execute auto hold by the power train. Otherwise, further determine whether the hydraulic function of the hydraulic unit of the brake system is normal. If it is normal, take over auto hold by the hydraulic function. If there is a defect in the hydraulic function, take over auto hold by the auto parking brake (APB) function or the electric parking brake (EPB) function, including.

[0006] One aspect of the present disclosure also includes an auto hold system for an electric vehicle, which a trigger module for generating brake hydraulic pressure and a trigger signal based on an event that the brake pedal is depressed, a first control module triggered by the trigger signal for determining whether the electric vehicle meets the preconditions for auto hold. When the preconditions are met, control the power train to execute auto hold. When the preconditions are not met, control the execution of the operation of the second control module, the first control module; a second control module for determining whether the hydraulic function of the hydraulic unit of the brake system is normal. When it is normal, control the hydraulic function to take over auto hold. When there is a defect in the hydraulic function, control the APB function or the EPB function to take over auto hold, the second control module; comprising.

[0007] As described above, according to the auto hold method and system for an electric vehicle of the present disclosure, the APB function or the EPB function can take over and execute auto hold when there is a defect in the hydraulic function in the brake system. Therefore, even when there is a defect in the hydraulic function, the auto hold method of the present disclosure can achieve the auto hold function.

[0008] Furthermore, according to the automatic parking method and system of the present disclosure, when the preconditions for automatic parking are not met, the power train has exceeded a predetermined threshold time for executing automatic parking, and the electric vehicle is overheated, it is possible to shift to a hydraulic function that takes over automatic parking. Furthermore, when the time for the hydraulic function to take over automatic parking exceeds a predetermined time threshold, it is possible to shift to an APB function or an EPB function that takes over automatic parking.

[0009] The foregoing objects, other objects, and advantages of the present application will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings, in which like or similar elements are denoted by the same reference numerals.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0011] The following describes some of the examples of the present disclosure for the purpose of providing a basic understanding of the present disclosure, and is not intended to identify important elements or decisive elements of the present invention, nor to limit the scope of protection required.

[0012] FIG. 1 is a flowchart of an automatic parking method for an electric vehicle according to an embodiment of the present disclosure.

[0013] In FIG. 1, area A represents an AVH (Automatic Vehicle Hold) activation zone, and area B represents a takeover zone (including takeover of the hydraulic function and takeover of the APB or EPB function). As shown in FIG. 1, an embodiment of the automatic parking method for an electric vehicle in the present disclosure includes the following steps. S1: Start. S2: The driver depresses the brake pedal. S3: Based on the event that the brake pedal is depressed, brake hydraulic pressure is generated, a trigger signal is generated, and a brake hydraulic pressure value is recorded. In FIG. 1, P represents the brake hydraulic pressure value, which is recorded and transmitted to area B for participation in subsequent step S8. S4: Triggered by the trigger signal, it is determined whether the preconditions for auto hold are met. If the preconditions are met, proceed to step S5; otherwise, proceed to step S7. The preconditions include, for example, no fault in the power train, not too steep a gradient on the slope where the electric vehicle is located, and sufficient battery level of the electric vehicle (i.e., the main battery circuit is appropriate). S5: Auto parking is executed by the power train, i.e., the power train maintains a certain torque to keep the vehicle in a stationary state. S6: It is determined whether the time for auto hold executed by the power train exceeds a predetermined threshold value, and whether the temperature of the power train exceeds a predetermined temperature. If the time exceeds the predetermined threshold value or the temperature exceeds the predetermined temperature (i.e., the electric vehicle overheats), proceed to step S7; otherwise, proceed to step S11. S7: It is determined whether the hydraulic function of the hydraulic unit of the hydraulic system is normal. If the hydraulic function is normal, proceed to step S8; otherwise, proceed to step S10. S8: Auto parking is taken over by the hydraulic function, i.e., the brake hydraulic pressure value recorded in step S3 is used by the hydraulic function to execute auto hold to keep the vehicle in a stationary state. S9: It is determined whether the time for auto hold taken over by the hydraulic function exceeds the time threshold value. If it exceeds the time threshold value, proceed to step S10. S10: Auto parking is taken over by the APB or EPB function to keep the vehicle in a stationary state. S11: The automatic parking is executed by the power train until the driver is ready to escape from that state (e.g., the driver steps on the accelerator). S12: End.

[0014] As described above, according to the automatic hold method for an electric vehicle of this embodiment, by adding step S7 to determine whether there is a defect in the hydraulic function, when there is a defect in the hydraulic function in the hydraulic unit of the brake system, the APB or EPB function can take over the automatic hold. Therefore, even when there is a defect in the hydraulic function, the automatic hold method for an electric vehicle of the present disclosure does not affect the automatic hold function.

[0015] Furthermore, by adding the determinations in steps S4 and S6, when the related preconditions are not satisfied, the time for the automatic hold to be executed by the power train exceeds a predetermined time threshold, and the power train is overheated, it is possible to shift to the takeover of the hydraulic function to maintain the electric vehicle.

[0016] Furthermore, by adding the determination in step S9, when the time for the automatic hold to be taken over by the hydraulic function exceeds a predetermined time threshold, it is possible to shift to the takeover of the APB or EPB function to maintain the electric vehicle.

[0017] On the other hand, by analyzing the relationship between the defective state and the AVH function in the automatic hold method for an electric vehicle in this embodiment, Table 1 is obtained.

[0018] Table 1 shows the relationship between the defective state of the automatic hold method for an electric vehicle in this embodiment and the state of the AVH function.

Table 1

[0019] As shown in Table 1, according to the auto-hold method for electric vehicles in the present disclosure, when the hydraulic function is turned off, the auto-hold is taken over by the APB or EPB function, and the defect of the hydraulic function does not affect the AVH function. In the case of a power train failure, the auto-hold is taken over by the hydraulic function. Therefore, the defect of the power train only affects the auto-hold executed by the power train and does not affect the auto-hold executed by the hydraulic function. Since the APB or EPB function finally takes over, when the APB or EPB function is turned off, it will affect the AVH function. Therefore, the defect of the APB or EPB function affects the AVH function.

[0020] The above describes the auto-hold method for electric vehicles in the present disclosure. Next, the auto-hold system for electric vehicles in the present disclosure will be described.

[0021] FIG. 2 is a block diagram of an auto-hold system for an electric vehicle according to an embodiment of the present disclosure.

[0022] As shown in FIG. 2, the auto-hold system 100 for an electric vehicle in the present disclosure includes a trigger module 110 that generates a brake hydraulic pressure and a trigger signal based on an event that the brake pedal is depressed and records a brake hydraulic pressure value; a first control module 120 triggered by a trigger signal for determining whether the electric vehicle satisfies the preconditions for auto-hold. When the preconditions are satisfied, it controls the power train to execute auto-hold. When the preconditions are not satisfied, it controls the execution of the above operation by the second control module 130; a second control module 130 for determining whether the hydraulic function of the hydraulic unit of the brake system is normal. When it is normal, it controls the hydraulic function to take over the auto-hold. When there is a defect in the hydraulic function, it controls the APB function or the EPB function to take over the auto-hold. A third control module 140 for determining whether the time for the hydraulic function to take over the auto hold exceeds a preset first time threshold, and if so, controlling the APB function or the EPB function to take over the auto hold. A fourth control module 150 for determining whether the time for the auto hold to be executed by the power train exceeds a preset second time threshold and whether the temperature of the power train exceeds a predetermined temperature, and if any condition is satisfied, controlling the execution of the operation of the second control module 130. Comprising.

[0023] Here, when the hydraulic function is normal, the second control module 130 controls the use of the brake hydraulic pressure value recorded by the trigger module 110 to hold the electric vehicle.

[0024] The above description is only for specific embodiments of the present application, and the protection scope of the present application is not limited thereto. Those skilled in the art can contemplate other feasible modifications or substitutions according to the technical scope disclosed in the present application, and all such modifications or substitutions are within the protection scope of the present application. If there is no contradiction, the embodiments of the present application and the features within the embodiments can also be combined with each other. The protection scope of the present application shall follow the protection scope of the claims.

Claims

1. 1. An autohold method for an electric vehicle, comprising: generating brake fluid pressure based on a brake pedal depression event of the electric vehicle and recording the brake fluid pressure value; determining whether the electric vehicle meets an autohold prerequisite; executing an autohold by the powertrain if the preconditions for the autohold are met; If not, further determining whether the hydraulic function of the hydraulic unit of the brake system is normal; if so, taking over AUTOHOLD by said hydraulic function; if the hydraulic function is defective, then AutoHold is taken over by an Auto Parking Brake (APB) function or an Electric Parking Brake (EPB) function; 1. An autohold method for an electric vehicle, comprising:

2. 2. The autohold method for an electric vehicle of claim 1, further comprising: if autohold is taken over by the hydraulic function, further determining whether the time that the hydraulic function has taken over autohold exceeds a preset first time threshold, and if so, causing autohold to be taken over by the APB function or the EPB function.

3. 2. The autohold method for an electric vehicle according to claim 1, characterized in that, if the autohold is taken over by the hydraulic function, the brake hydraulic pressure value is used to perform the autohold.

4. 2. The autohold method for an electric vehicle as described in claim 1, further determining whether the time during which the autohold is executed by the powertrain exceeds a preset second time threshold and whether the temperature of the powertrain exceeds a predetermined temperature, and if either condition is met, further determining whether the hydraulic function is normal, and if normal, having the hydraulic function take over the autohold, and if it is determined that the hydraulic function is defective, having the APB function or the EPB function take over the autohold.

5. The preconditions for AutoHold are: the powertrain is free of defects; the slope on which the electric vehicle is located is within a preset gradient threshold; and a battery level of the electric vehicle is greater than a pre-established battery level threshold; 2. The autohold method for an electric vehicle according to claim 1, further comprising one or more of the following:

6. 1. An autohold system for an electric vehicle, comprising: a trigger module for generating brake hydraulic pressure and a trigger signal based on the event of depression of the brake pedal; a first control module triggered by a trigger signal for determining whether the electric vehicle meets the preconditions for an autohold, the first control module controlling the powertrain to perform an autohold if the preconditions are met, and controlling execution of an operation of the second control module if the preconditions are not met; a second control module for determining whether the hydraulic function of the hydraulic unit of the brake system is normal, and if so, controlling the hydraulic function to take over AUTOHOLD, and if the hydraulic function is defective, controlling the APB function or the EPB function to take over AUTOHOLD; An autohold system for an electric vehicle, comprising:

7. 7. The autohold system for an electric vehicle of claim 6, further comprising a third control module that determines whether the time that the hydraulic function has taken over autohold exceeds a first preset time threshold, and if so, controls the APB function or the EPB function to take over autohold.

8. 8. The autohold system for an electric vehicle of claim 7, further comprising a fourth control module for determining whether a time during which the autohold is performed by the powertrain exceeds a second preset time threshold and whether a temperature of the powertrain exceeds a predetermined temperature, and for controlling the execution of the operation of the second control module if either condition is met.

9. 6. The auto-hold system for electric vehicles according to claim 5, wherein the trigger module further records the brake hydraulic pressure value, and the second control module controls the use of the brake hydraulic pressure value recorded by the trigger module to realize auto-hold when the hydraulic function is normal.

10. A computer readable medium storing a computer program which, when executed by a processor, is for implementing the autohold method for an electric vehicle according to any one of claims 1 to 5.

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