Control method and device for vehicle coasting with engine off

Abstract

The present invention relates to the field of vehicle control technology, and provides a method and device for controlling vehicle coasting with the engine off. The method of the present invention comprises: judging the driving state of the vehicle and the state of the brake pedal; when judging that the driving state of the vehicle is coasting with the engine off and the state of the brake pedal is stepped on, detecting the vacuum degree of the vacuum booster of the vehicle; when detecting that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active boosting condition, controlling the motor boost of the vehicle. The method can ensure that the vehicle can achieve the expected deceleration, thereby ensuring safety.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control, and in particular to a method and device for controlling vehicle coasting during engine shutdown. Background Art

[0002] At present, in some typical road conditions such as continuous downhill curve driving, drivers may adopt the driving mode of turning off the engine and gliding in neutral gear to reduce vehicle fuel consumption. However, the vacuum source of the brake system comes from the engine. When the engine is turned off, the vacuum in the vacuum booster is consumed and cannot be compensated. The expected deceleration may not be achieved, which may cause serious vehicle accidents. Summary of the invention

[0003] In view of this, the present invention aims to provide a control method for coasting with the engine off, so as to ensure that the vehicle can achieve the expected deceleration, thereby ensuring safety.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for controlling vehicle coasting with the engine off, the method comprising: judging the driving state of the vehicle and the state of a brake pedal; when judging that the driving state of the vehicle is coasting with the engine off and the state of the brake pedal is pressed, detecting the vacuum degree of a vacuum booster of the vehicle; and when detecting that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets an active boost condition, controlling the motor boost of the vehicle.

[0006] Furthermore, determining the driving state of the vehicle includes: detecting at least one of an ignition switch position, a gear position, and an engine state, and a vehicle speed; when at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off, and the vehicle speed is greater than or equal to a preset speed, determining that the driving state of the vehicle is coasting with the engine off.

[0007] Furthermore, the method also includes: detecting the brake master cylinder pressure of the vehicle; calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting the current deceleration of the vehicle; detecting the four-wheel speed slip of the vehicle; and when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active boost condition, controlling the motor boost of the vehicle includes: when it is detected that the vacuum degree is less than or equal to the first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration and the four-wheel speed slip of the vehicle is 0, controlling the motor boost of the vehicle.

[0008] Furthermore, the method also includes: detecting the brake master cylinder pressure of the vehicle; calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting the current deceleration of the vehicle; and controlling the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle satisfies the active boost condition, including: controlling the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to the first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0.

[0009] Furthermore, the method also includes: when it is detected that the vacuum degree is less than or equal to a second preset vacuum degree, controlling the engine of the vehicle to start.

[0010] Compared with the prior art, the vehicle control method of the present invention has the following advantages:

[0011] A method for controlling a vehicle coasting with the engine off, the method comprising: judging the driving state of the vehicle and the state of the brake pedal; when judging that the driving state of the vehicle is coasting with the engine off and the state of the brake pedal is pressed, detecting the vacuum degree of the vacuum booster of the vehicle; when detecting that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets an active boost condition, controlling the motor of the vehicle to boost. The present invention can perform boost auxiliary braking when the vacuum degree is insufficient to enable the vehicle to achieve the expected deceleration, ensuring that the vehicle can achieve the expected deceleration, thereby ensuring safety.

[0012] Another object of the present invention is to provide a control device for coasting with the engine off, so as to ensure that the vehicle can achieve the expected deceleration and ensure safety.

[0013] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0014] A control device for vehicle coasting with the engine off, the device comprising: a judgment unit, a vacuum detection unit and a control unit, wherein the judgment unit is used to judge the driving state of the vehicle and the state of the brake pedal; the vacuum detection unit is used to detect the vacuum degree of the vacuum booster of the vehicle when it is judged that the driving state of the vehicle is coasting with the engine off and the state of the brake pedal is pressed; and the control unit is used to control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active boost condition.

[0015] Furthermore, the device also includes a driving state detection unit, which is used to detect at least one of the ignition switch position, gear position and engine state of the vehicle, and the vehicle speed; the judgment unit includes a driving state judgment unit, and the driving state judgment unit is used to judge that the driving state of the vehicle is engine-off coasting when at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off, and the vehicle speed is greater than or equal to a preset vehicle speed.

[0016] Furthermore, the device also includes a boost condition detection unit, which is used to: detect the brake master cylinder pressure of the vehicle; calculate the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detect the current deceleration of the vehicle; detect the four-wheel speed slip of the vehicle; the control unit is also used to: control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration and the four-wheel speed slip of the vehicle is 0.

[0017] Furthermore, the device also includes a boost condition detection unit, which is used to: detect the brake master cylinder pressure of the vehicle; calculate the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detect the current deceleration of the vehicle; the control unit is also used to: control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel wheel speed slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0.

[0018] Furthermore, the control unit is also used to: control the engine of the vehicle to start when it is detected that the vacuum degree is less than or equal to a second preset vacuum degree.

[0019] The advantages of the vehicle stall coasting control device and the vehicle stall coasting control method described above relative to the prior art are the same, and will not be described in detail here.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 is a flow chart of a method for controlling vehicle coasting while engine off provided by an embodiment of the present invention;

[0023] Figure 2 A flow chart of a method for determining a stall coasting condition provided by an embodiment of the present invention;

[0024] Figure 3 A flow chart of an active boost determination method provided by an embodiment of the present invention;

[0025] Figure 4 is a structural block diagram of a vehicle shutdown coasting control device provided by an embodiment of the present invention;

[0026] Figure 5 It is a structural block diagram of a vehicle shutdown coasting control device provided by another embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 101 judgment unit 102 vacuum degree detection unit

[0029] 103 Control unit 201 Driving state detection unit

[0030] 202 Driving state judgment unit 301 Boost condition detection unit DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0033] Figure 1 FIG. 1 is a flow chart of a method for controlling a vehicle coasting while engine off according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0034] Step S11, determining the driving state of the vehicle and the state of the brake pedal;

[0035] For example, Figure 2 As shown, judging the driving state of the vehicle specifically includes the following steps:

[0036] Step S21, detecting at least one of an ignition switch position, a gear position, and an engine state of the vehicle, and a vehicle speed;

[0037] Step S22, when at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off, and the vehicle speed is greater than or equal to a preset speed, it is determined that the driving state of the vehicle is coasting with the engine off.

[0038] For example, when the vehicle is not ignited, the engine is not started, the gear is in neutral, and the vehicle speed is greater than or equal to a preset speed (eg, 10 KM / h), it indicates that the vehicle is in a stalled coasting state.

[0039] When the vehicle is turned off and coasting, if the driver presses the brake pedal, the vacuum degree of the vacuum booster will decrease. Therefore, judging the state of the brake pedal here can ensure that the reduction in the vacuum degree of the vacuum booster is caused by the brake pedal being pressed.

[0040] Step S12, when it is determined that the driving state of the vehicle is engine-off coasting and the state of the brake pedal is depressed, detecting the vacuum degree of the vacuum booster of the vehicle;

[0041] For example, when the vehicle is in a coasting state with the engine off and the brake pedal is in a depressed state, the vacuum degree in the vacuum booster can be detected by a vacuum degree sensor;

[0042] Step S13, when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets an active supercharging condition, controlling the motor of the vehicle to supercharge;

[0043] For example, the first preset vacuum degree can be understood as a vacuum degree that cannot cause the vehicle to produce the expected deceleration. When the vacuum degree is less than or equal to the first preset vacuum degree, auxiliary intervention is required (for example, active boosting of the motor to enable the vehicle to achieve the expected deceleration. In addition, in order to ensure safety, it is also necessary to determine whether the active boosting conditions are met. When the vehicle meets the active boosting conditions, the motor boost can be controlled until it is detected that the current deceleration of the vehicle is equal to the driver's expected deceleration, so as to achieve the purpose of assisting the vehicle to decelerate normally. Figure 3 As shown, the specific steps are as follows:

[0044] Step S31, detecting the brake master cylinder pressure of the vehicle;

[0045] For example, the vehicle's brake master cylinder pressure can be detected in real time through the master cylinder pressure sensor;

[0046] Step S32, calculating the driver's expected deceleration according to the brake master cylinder pressure of the vehicle;

[0047] For example, the master cylinder pressure is equivalent to the pressure of the driver stepping on the brake pedal, which is basically not affected by whether the vacuum is sufficient. Therefore, the master cylinder pressure can be used to calculate the driver's expected deceleration. This calculation method can be implemented by those skilled in the art and will not be repeated here. In addition, the brake pedal displacement sensor can also be used to detect whether the brake pedal has been displaced, so as to confirm that the detected master cylinder pressure is definitely generated by the driver stepping on the brake pedal.

[0048] Step S33, detecting the current deceleration of the vehicle;

[0049] For example, the current deceleration of the vehicle can be detected by a longitudinal acceleration sensor;

[0050] Step S34, detecting the four-wheel speed slip of the vehicle;

[0051] For example, the wheel speed slip of the vehicle's four wheels can be detected by wheel speed sensors;

[0052] Step S35, when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, and the four-wheel slip of the vehicle is 0, control the motor boost of the vehicle.

[0053] For example, when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, it means that the vehicle cannot achieve the expected deceleration without assistance. At this time, when the four-wheel slip of the vehicle is 0, that is, the vehicle has no slip, it can be determined that the vehicle meets the active supercharging condition, that is, active supercharging is required to assist the vehicle in decelerating.

[0054] In addition, step S35 can also be ( Figure 3 Not shown): When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0, the motor boost of the vehicle is controlled.

[0055] For example, controlling the motor boost of the vehicle requires not only that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration and the four-wheel slip of the vehicle is 0, but also that the master cylinder pressure is greater than 0 and the travel of the brake pedal is greater than 0. When all the above conditions are met, it is determined that the vehicle meets the active boost condition, and the motor boost of the vehicle is controlled, so as to ensure the lack of vacuum caused by braking and maximize safety.

[0056] In addition, when it is detected that the vacuum degree is less than or equal to the second preset vacuum degree (for example, 30KPA, but not limited thereto), the engine of the vehicle is controlled to start. When the existing vehicle performs the third braking (brake vacuum booster characteristics) with a required deceleration greater than 2.44m / s (legislation requires that the braking should reach a deceleration after the vacuum booster fails) after the engine is turned off, the vacuum degree in the vacuum booster will be lower than the minimum boost design value (i.e., the second preset vacuum degree), and the driver will no longer be able to support braking with a deceleration greater than 2.44m / s. Therefore, the engine can be started at this time, and the driver is prompted to drive safely. After starting the engine, the driver can drive normally.

[0057] The present invention monitors the vacuum degree of the vacuum booster after the vehicle is turned off through the function of the electronic control system, actively builds up pressure, ensures driving safety and enables the driver to continue driving the vehicle; the development and calibration cycle cost of this function is low, and only requires the addition of a signal interaction strategy, which can actively increase pressure and start the power system, and can avoid safety problems caused by vehicle coasting due to stalling.

[0058] Figure 4 FIG. 1 is a structural block diagram of a vehicle coasting control device provided by an embodiment of the present invention. Figure 4 As shown, the device includes: a judgment unit 101, a vacuum detection unit 102 and a control unit 103, wherein the judgment unit 101 is used to judge the driving state of the vehicle and the state of the brake pedal; the vacuum detection unit 102 is used to detect the vacuum degree of the vacuum booster of the vehicle when it is judged that the driving state of the vehicle is engine-off coasting and the state of the brake pedal is pressed; the control unit 103 is used to control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active boost condition.

[0059] In this embodiment, the judgment unit 101 can judge the driving state of the vehicle and the state of the brake pedal, and after obtaining the judgment result, send the corresponding signal to the vacuum detection unit 102. The signal received by the vacuum detection unit 102 represents that when the driving state is engine-off and coasting and the state of the brake pedal is pressed, the vacuum degree of the vacuum booster is detected.

[0060] Figure 5 FIG. 1 is a block diagram of a vehicle shutdown coasting control device provided by an embodiment of the present invention. Figure 5As shown, the device also includes a driving state detection unit 201, which is used to detect at least one of the ignition switch position, gear position and engine state of the vehicle, and the vehicle speed; the judgment unit 101 includes a driving state judgment unit 202, and the driving state judgment unit 202 is used to judge that the driving state of the vehicle is engine-off coasting when at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off is satisfied, and the vehicle speed is greater than or equal to a preset vehicle speed.

[0061] Furthermore, the device also includes a boost condition detection unit 301, which is used to: detect the brake master cylinder pressure of the vehicle; calculate the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detect the current deceleration of the vehicle; detect the four-wheel speed slip of the vehicle; the control unit 103 is also used to: control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration and the four-wheel speed slip of the vehicle is 0.

[0062] Furthermore, the device also includes a boost condition detection unit 301, which is used to: detect the brake master cylinder pressure of the vehicle; calculate the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detect the current deceleration of the vehicle; detect the four-wheel speed slip of the vehicle; the control unit 103 is also used to: control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel speed slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0.

[0063] Furthermore, the control unit 103 is further configured to: when it is detected that the vacuum degree is less than or equal to a second preset vacuum degree, control the engine of the vehicle to start.

[0064] The embodiment of the vehicle ignition-off coasting control device described above is similar to the embodiment of the vehicle ignition-off coasting control method described above, and will not be described in detail here.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling vehicle coasting with engine off, characterized in that: The method comprises: Determining the driving state of the vehicle and the state of the brake pedal; When it is determined that the driving state of the vehicle is coasting with the engine off and the state of the brake pedal is depressed, detecting the vacuum degree of the vacuum booster of the vehicle; When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets an active supercharging condition, controlling the motor of the vehicle to supercharge; The method further includes: detecting a brake master cylinder pressure of the vehicle; Calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting a current deceleration of the vehicle; detecting four-wheel wheel slip of the vehicle; When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active supercharging condition, controlling the motor supercharging of the vehicle includes: When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, and the four-wheel slip of the vehicle is 0, the motor of the vehicle is controlled to boost pressure.

2. The vehicle shutdown coasting control method according to claim 1, characterized in that: The determining the driving state of the vehicle includes: detecting at least one of an ignition switch position, a gear position, and an engine state of the vehicle, and a vehicle speed; When at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off, and the vehicle speed is greater than or equal to a preset vehicle speed, it is determined that the driving state of the vehicle is engine-off coasting.

3. The method for controlling vehicle coasting with engine off according to claim 1, characterized in that: The method further includes: detecting a brake master cylinder pressure of the vehicle; Calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting a current deceleration of the vehicle; detecting four-wheel wheel slip of the vehicle; When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active supercharging condition, controlling the motor supercharging of the vehicle includes: When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0, the motor boost of the vehicle is controlled.

4. The method for controlling vehicle coasting with engine off according to claim 1, characterized in that: The method further includes: When it is detected that the vacuum degree is less than or equal to a second preset vacuum degree, the engine of the vehicle is controlled to start.

5. A vehicle coasting control device, characterized in that: The device comprises: A judgment unit, a vacuum detection unit, a control unit and a boost condition detection unit, wherein: The judging unit is used to judge the driving state of the vehicle and the state of the brake pedal; The vacuum degree detection unit is used to detect the vacuum degree of the vacuum booster of the vehicle when it is determined that the driving state of the vehicle is engine-off coasting and the state of the brake pedal is depressed; The control unit is used to control the motor boost of the vehicle when it is detected that the vacuum degree is less than or equal to a first preset vacuum degree and the vehicle meets the active boost condition; The boost condition detection unit is used for: detecting a brake master cylinder pressure of the vehicle; Calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting a current deceleration of the vehicle; detecting four-wheel wheel slip of the vehicle; The control unit is also used for: When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, and the four-wheel slip of the vehicle is 0, the motor of the vehicle is controlled to boost pressure.

6. The vehicle shutdown coasting control device according to claim 5, characterized in that: The device further comprises a driving state detection unit for detecting at least one of an ignition switch position, a gear position and an engine state of the vehicle, and a vehicle speed; The judgment unit includes a driving state judgment unit, which is used to judge that the driving state of the vehicle is engine-off coasting when at least one of the ignition switch position is OFF, the gear position is neutral, and the engine state is off, and the vehicle speed is greater than or equal to a preset vehicle speed.

7. The vehicle shutdown coasting control device according to claim 5, characterized in that: The device also includes a boost condition detection unit, which is used to: detecting a brake master cylinder pressure of the vehicle; Calculating the driver's expected deceleration based on the brake master cylinder pressure of the vehicle; detecting a current deceleration of the vehicle; detecting four-wheel wheel slip of the vehicle; The control unit is also used for: When it is detected that the vacuum degree is less than or equal to a first preset vacuum degree, and when it is detected that the current deceleration of the vehicle is less than or equal to the driver's expected deceleration, the four-wheel slip of the vehicle is 0, the brake master cylinder pressure is greater than 0, and the brake pedal stroke is greater than 0, the motor boost of the vehicle is controlled.

8. The vehicle shutdown coasting control device according to claim 5, characterized in that: The control unit is also used for: When it is detected that the vacuum degree is less than or equal to a second preset vacuum degree, the engine of the vehicle is controlled to start.

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