Vehicle downhill control method and vehicle

Abstract

The invention belongs to the technical field of vehicles, and discloses a vehicle downhill control method and a vehicle. The vehicle downhill control method comprises a downhill cruise mode, when it is judged that starting conditions of the downhill cruise mode are met, the vehicle enters the downhill cruise mode, and the vehicle speed at the entering moment serves as the set vehicle speed; calculating the total braking force required for the vehicle to go downhill at the set speed; the maximum electric braking force capable of being provided by the motor is compared with the total braking force, and when the maximum electric braking force capable of being provided by the motor is larger than or equal to the total braking force, the motor is controlled to conduct electric braking through the total braking force; and when the maximum electric braking force capable of being provided by the motor is smaller than the total braking force, the motor is controlled to conduct electric braking with the maximum electric braking force, and an air braking controller is controlled to conduct air braking so as to compensate the electric braking. Through timely intervention of pneumatic braking, electric braking can be compensated, so that the vehicle is decelerated to a safe vehicle speed at which the motor can maintain a constant downhill speed, and a driver does not need to control the vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular, to a vehicle downhill control method and a vehicle. Background Art

[0002] In terms of braking of non-wire-controlled chassis new energy engineering vehicles, at present, many new energy vehicles adopt a combination of regenerative braking and pedal braking. The regenerative braking is achieved by reversing the motor. This braking method can only provide electric braking at a low vehicle speed according to the slope and vehicle speed, and it is necessary to frequently adjust the gear of the regenerative braking handle to output different braking forces to decelerate or maintain the vehicle speed. When the vehicle speed is high or the vehicle load is high, there will be a phenomenon of insufficient electric braking, and only the air braking can be increased through the brake pedal to ensure the braking ability of the vehicle. The driver needs to frequently step on the brake pedal, which not only makes the driver more fatigued, but also makes it difficult to stably control the vehicle speed. Summary of the Invention

[0003] The purpose of the present invention is to provide a vehicle downhill control method and a vehicle, which can enable the vehicle to descend at a uniform and stable speed, avoid the risks of overspeed and rolling back of the vehicle, and do not require the driver to operate.

[0004] To achieve this purpose, the present invention adopts the following technical solutions:

[0005] A vehicle downhill control method includes a downhill cruise mode, and the downhill cruise mode includes:

[0006] When it is determined that the start condition of the downhill cruise mode is met, enter the downhill cruise mode, and use the vehicle speed at the moment of entering the downhill cruise mode as the set vehicle speed;

[0007] Calculate the total braking force required for the vehicle to descend at a uniform speed at the set vehicle speed;

[0008] Compare the maximum electric braking force that the motor can provide with the total braking force. When the maximum electric braking force that the motor can provide is greater than or equal to the total braking force, control the motor to perform electric braking with the total braking force; when the maximum electric braking force that the motor can provide is less than the total braking force, control the motor to perform electric braking with the maximum electric braking force, and control the air braking controller to implement air braking to compensate for the electric braking.

[0009] As a preferred technical solution of the vehicle downhill control method, the start conditions of the downhill cruise mode include the start of the downhill cruise rocker switch, the closing of the regenerative braking handle, the release of the accelerator pedal, the release of the brake pedal, and the release of the handbrake.

[0010] As a preferred technical solution of the vehicle downhill control method, calculating the total braking force required for the vehicle to descend at a uniform speed at the set vehicle speed specifically includes:

[0011] The feedforward braking force is calculated based on the longitudinal dynamics formula of the vehicle, the fully-loaded or empty state of the vehicle, and the slope of the vehicle going downhill.

[0012] The compensation braking force is calculated based on the difference between the set vehicle speed and the actual vehicle speed.

[0013] The total braking force is obtained by adding the feedforward braking force and the compensation braking force.

[0014] As a preferred technical solution of the vehicle downhill control method, when it is detected that the brake pedal is stepped on to the set depth or the accelerator pedal is stepped on, the downhill cruise mode is exited.

[0015] As a preferred technical solution of the vehicle downhill control method, it further includes an auxiliary braking mode, and the auxiliary braking mode includes:

[0016] When it is detected that the auxiliary braking rocker switch is activated and the retarder handle is in the high gear position, the auxiliary braking mode is entered.

[0017] Control the motor to perform electric braking with the maximum electric braking force, and control the air braking controller to output corresponding air braking force according to the gear position where the retarder handle is located.

[0018] As a preferred technical solution of the vehicle downhill control method, after the vehicle stops braking, control the air braking controller to continue to perform air braking, and at the same time control the parking controller to perform parking; when it is detected that the vehicle is parked, control the air braking controller to release the air braking.

[0019] As a preferred technical solution of the vehicle downhill control method, when it is detected that the accelerator is stepped on, determine whether the vehicle needs to lift the goods. If not, control the parking brake to release the parking. If so, control the parking brake not to release the parking.

[0020] As a preferred technical solution of the vehicle downhill control method, it further includes a safety redundant braking mode, and the safety redundant braking mode includes:

[0021] It is detected that braking force needs to be provided, and it is detected that the maximum electric braking force provided by the motor is insufficient, and it is detected that the air braking controller fails.

[0022] Send a maximum air braking command to the air braking valve.

[0023] As a preferred technical solution of the vehicle downhill control method, after sending the maximum air braking command to the air braking valve, the vehicle speed is detected in real time. When it is detected that the vehicle speed is less than the set value, a parking command is sent to the parking valve.

[0024] A vehicle adopts the vehicle downhill control method described in any of the above solutions.

[0025] Advantages of the present invention:

[0026] The present invention provides a vehicle downhill control method, including a downhill cruise mode. When it is determined that the start conditions of the downhill cruise mode are met, the vehicle enters the downhill cruise mode, and the vehicle speed at the moment of entering the downhill cruise mode is used as the set vehicle speed; calculate the total braking force required for the vehicle to travel downhill at a constant speed with the set vehicle speed; compare the maximum electric braking force that the motor can provide with the total braking force. When the maximum electric braking force that the motor can provide is greater than or equal to the total braking force, control the motor to perform electric braking with the total braking force; when the maximum electric braking force that the motor can provide is less than the total braking force, control the motor to perform electric braking with the maximum electric braking force, and control the air brake controller to implement air braking to compensate for the electric braking. When the set vehicle speed is not high, the braking torque that the motor can provide is sufficient to make the vehicle travel at a constant speed with the set vehicle speed, and at this time, there is no need to intervene in the air braking for additional deceleration; when the set vehicle speed is relatively high, the braking torque provided by the motor is not sufficient to make the vehicle travel at a constant speed with the set vehicle speed. At this time, by intervening in the air braking, the electric braking can be compensated, so that the vehicle can be decelerated to a safe vehicle speed at which the motor can maintain its uniform downhill travel, avoiding the risk of vehicle speeding and the risk of vehicle slipping, and without the need for driver operation.

[0027] The present invention also provides a vehicle that adopts the vehicle downhill control method provided by the present invention. By adopting the vehicle downhill control method provided by the present invention, the vehicle can travel downhill at a constant speed stably, avoiding the risk of vehicle speeding and the risk of vehicle slipping, and without the need for driver operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic flow chart of the downhill cruise mode in the vehicle downhill control method provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic flow chart of the auxiliary braking mode in the vehicle downhill control method provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic flow chart of the safety redundancy braking mode in the vehicle downhill control method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following further describes the present invention in detail with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of convenience of description, only parts related to the present invention rather than all structures are shown in the drawings.

[0032] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above the", and "on the" second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below the", and "under the" second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0034] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.

[0035] As Figure 1 shown, the embodiment of the present invention provides a vehicle downhill control method, including a downhill cruise mode, and the downhill cruise mode includes:

[0036] S11. When it is judged that the starting conditions of the downhill cruise mode are met, enter the downhill cruise mode, and use the vehicle speed at the moment of entering the downhill cruise mode as the set vehicle speed.

[0037] The starting conditions of the downhill cruise mode include the start of the downhill cruise rocker switch, the closing of the retarder handle, the release of the accelerator pedal, the release of the brake pedal, and the release of the handbrake; or it is detected that the vehicle speed increases by a set range value within a set time period, for example, it is detected that the vehicle speed increases by 0.5 - 1.0 km / h within 1 - 2 s, and the retarder handle is closed, the accelerator pedal is released, and the brake pedal is released.

[0038] After entering the downhill cruise mode, the driver can increase or decrease the set vehicle speed through the speed adjustment key, and the range of increasing or decreasing the set vehicle speed is ±3 km / h.

[0039] After entering the downhill cruise mode, the vehicle control unit will issue a prompt indicating that the vehicle has entered the downhill cruise mode. For example, it will send the prompt message to the instrument panel or emit a prompt sound, etc.

[0040] S12. Calculate the total braking force required for the vehicle to travel downhill at a set speed uniformly.

[0041] Specifically, step S12 includes:

[0042] S121. Calculate the feedforward braking force according to the longitudinal dynamics formula of the vehicle, the empty / full load state of the vehicle, and the slope of the vehicle going downhill.

[0043] The longitudinal dynamics formula of the vehicle is: F m =F f +F t +F w

[0044] Among them, F m is the component force of gravity. The total vehicle weight can be obtained based on the vehicle load and the vehicle's own weight, and then the component force F m of the total vehicle weight on the slope can be calculated according to the total vehicle weight and the slope of the vehicle going downhill; F f is the rolling resistance, and the rolling resistance F f can be calculated according to the total vehicle weight and the rolling resistance coefficient; F w is the air resistance. Since the vehicle tonnage is large and the vehicle speed is low, the air resistance can be ignored; F t is the feedforward braking force. After both F m and F f are known, F t can be calculated through the above longitudinal dynamics formula of the vehicle.

[0045] S122. Calculate the compensation braking force according to the difference between the set speed and the actual speed.

[0046] S123. Add the feedforward braking force and the compensation braking force to obtain the total braking force.

[0047] The feedforward braking force may be too large or too small. By calculating the compensation braking force and adding the feedforward braking force and the compensation braking force, the feedforward braking force can be PID-adjusted to finally obtain a more accurate total braking force.

[0048] S13. Compare the maximum electric braking force that the motor can provide with the total braking force. When the maximum electric braking force that the motor can provide is greater than or equal to the total braking force, control the motor to perform electric braking with the total braking force; when the maximum electric braking force that the motor can provide is less than the total braking force, control the motor to perform electric braking with the maximum electric braking force, and control the air braking controller to implement air braking to compensate for the electric braking.

[0049] When the set vehicle speed is not high, the braking torque that the motor can provide is sufficient to enable the vehicle to travel at a constant speed at the set vehicle speed. At this time, there is no need to intervene in the air brake for additional deceleration; when the set vehicle speed is high, the braking torque provided by the motor is not sufficient to enable the vehicle to travel at a constant speed at the set vehicle speed. At this time, by intervening in the air brake, the electric brake can be compensated, so that the vehicle can be decelerated to a safe vehicle speed at which the motor can maintain its uniform downhill travel, avoiding the risk of vehicle speeding and the risk of slipping, and without the need for driver operation.

[0050] Further, during the execution of step S13, when it is detected that the air brake controller cannot implement the air brake, a maximum air brake command is directly sent to the air brake valve. It should be noted that both the air brake controller and the air brake valve can implement the air brake. When the air brake controller has no fault, the air brake is preferably implemented by controlling the air brake controller; when the air brake controller fails, by directly controlling the air brake valve to implement the maximum air brake, the vehicle can be braked to a stop, ensuring the safe braking of the vehicle, thereby avoiding the risk of vehicle speeding and the risk of slipping.

[0051] S14. When it is detected that the brake pedal is stepped on to the set depth or it is detected that the accelerator pedal is stepped on, the downhill cruise mode is exited.

[0052] Further, when it is detected that the brake pedal is stepped on but not to the set depth, a prompt to step on the brake pedal deeper is issued to prompt the driver to continue stepping on the brake pedal until it reaches the set depth. In this embodiment, the braking force when the brake pedal is stepped on to the set depth is greater than the total braking force required for the vehicle to travel downhill at a constant speed at the set vehicle speed.

[0053] As Figure 2 shown, the vehicle downhill control method provided by the embodiment of the present invention further includes an auxiliary braking mode, and the auxiliary braking mode includes:

[0054] S21. When it is detected that the auxiliary braking rocker switch is started and the retarder handle is in the high gear position, the auxiliary braking mode is entered.

[0055] S22. Control the motor to perform electric braking with the maximum electric braking force, and control the air brake controller to output corresponding air braking forces according to the gear position where the retarder handle is located.

[0056] By combining the electric brake and the air brake, the vehicle is braked to a stop on the slope.

[0057] During the execution of step S22, when it is detected that the air brake controller cannot apply the air brake, a maximum air brake command is directly sent to the air brake valve. It should be noted that both the air brake controller and the air brake valve can implement the air brake. When the air brake controller is fault-free, the air brake is preferably applied by controlling the air brake controller; when the air brake controller fails, the maximum air brake is applied by directly controlling the air brake valve, which can stop the vehicle and ensure the safe braking of the vehicle.

[0058] S23. After the vehicle stops, control the air brake controller to continue applying the air brake, and at the same time control the parking controller to apply parking. When it is detected that the vehicle is parked, control the air brake controller to release the air brake.

[0059] Through this step, it can ensure that the vehicle stops stably and avoid the risk of the vehicle slipping.

[0060] S24. When it is detected that the accelerator is stepped on, determine whether the vehicle needs to lift the goods. If not, control the parking brake to release the parking. If so, control the parking brake not to release the parking.

[0061] When the downhill slope is relatively large, the auxiliary braking mode provided by this embodiment can be enabled to achieve the auxiliary braking of the vehicle, ensure the safe braking of the vehicle, and avoid the risk of the vehicle slipping.

[0062] As Figure 3 shown, the vehicle downhill control method provided by the embodiment of the present invention further includes a safety redundant braking mode, and the safety redundant braking mode includes:

[0063] S31. It is detected that braking force needs to be provided, and it is detected that the maximum electric braking force provided by the motor is insufficient, and it is detected that the air brake controller fails;

[0064] S32. Send a maximum air brake command to the air brake valve;

[0065] S33. Continuously detect the vehicle speed in real time. When it is detected that the vehicle speed is less than the set value, a parking command is sent to the parking valve.

[0066] When the air brake controller fails, the safety redundant braking mode provided by this embodiment can be enabled to ensure the safe braking of the vehicle.

[0067] The embodiment of the present invention also provides a vehicle that adopts the above vehicle downhill control method. By adopting the above vehicle downhill control method, the vehicle can descend at a uniform and stable speed, avoid the risks of the vehicle speeding and slipping, and does not require the driver to operate; the auxiliary braking of the vehicle is realized; the redundant control when the air brake control fails is realized, ensuring the safe braking of the vehicle.

[0068] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A vehicle downhill control method, characterized in that: Including a downhill cruising mode, the downhill cruising mode includes: When it is determined that the start condition of the downhill cruise mode is met, the downhill cruise mode is entered, and the vehicle speed at the time of entering the downhill cruise mode is used as the set vehicle speed; Calculating the total braking force required for the vehicle to go downhill at a constant speed at the set vehicle speed; The maximum electric braking force that the motor can provide is compared with the total braking force. When the maximum electric braking force that the motor can provide is greater than or equal to the total braking force, the motor is controlled to perform electric braking with the total braking force. When the maximum electric braking force that the motor can provide is less than the total braking force, the motor is controlled to perform electric braking with the maximum electric braking force, and the air brake controller is controlled to implement air braking to compensate for the electric braking.

2. The vehicle downhill control method according to claim 1, characterized in that: The activation conditions of the downhill cruise mode include activation of the downhill cruise rocker switch, closing of the deceleration handle, release of the accelerator pedal, release of the brake pedal and release of the handbrake.

3. The vehicle downhill control method according to claim 1, characterized in that: Calculating the total braking force required for a vehicle to go downhill at a set speed includes: The feed-forward braking force is calculated based on the longitudinal dynamics formula of the vehicle, the empty and full load states of the vehicle, and the downhill slope of the vehicle; The compensatory braking force is calculated based on the difference between the set vehicle speed and the actual vehicle speed; The total braking force is obtained by adding the feedforward braking force and the compensation braking force.

4. The vehicle downhill control method according to claim 1, characterized in that: When it is detected that the brake pedal is stepped on to a set depth or it is detected that the accelerator pedal is stepped on, the downhill cruising mode is exited.

5. The vehicle downhill control method according to claim 1, characterized in that: Also included is an auxiliary braking mode, the auxiliary braking mode comprising: When it is detected that the auxiliary brake rocker switch is activated and the deceleration handle is in a high gear position, the auxiliary brake mode is entered; The control motor performs electric braking with the maximum electric braking force, and controls the air brake controller to output corresponding air braking force according to the gear position of the deceleration handle.

6. The vehicle downhill control method according to claim 5, characterized in that: When the vehicle stops, the air brake controller is controlled to continue to implement the air brake, and the parking controller is controlled to implement parking at the same time; when it is detected that the vehicle is parked, the air brake controller is controlled to release the air brake.

7. The vehicle downhill control method according to claim 6, characterized in that: When it is detected that the accelerator is stepped on, it is determined whether the vehicle needs to lift cargo. If not, the parking brake is controlled to release the parking. If so, the parking brake is controlled not to release the parking.

8. The vehicle downhill control method according to any one of claims 1 to 7, characterized in that: It also includes a safety redundant braking mode, wherein the safety redundant braking mode includes: It is detected that braking force needs to be provided, it is detected that the maximum electric braking force provided by the motor is insufficient, and it is detected that the air brake controller fails; Sends a maximum air brake command to the air brake valve.

9. The vehicle downhill control method according to claim 8, characterized in that: After sending the maximum air brake command to the air brake valve, the vehicle speed is detected in real time. When it is detected that the vehicle speed is less than the set value, a parking command is sent to the parking valve.

10. A vehicle, characterized in that A vehicle downhill control method as described in any one of claims 1 to 9 is adopted.

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