Control method for reducing braking distance of vehicle

Abstract

The invention discloses a control method for reducing the braking distance of a vehicle, which comprises the following steps: when the vehicle is braked emergently, a control system detects the transfer degree of axle load, and adjusts the pressure buildup rate of wheels in real time according to the transfer degree of axle load, so that the wheel pressure and the transfer degree of axle load of the vehicle keep a certain relationship. According to the control method for reducing the vehicle braking distance, the wheel pressure buildup rate is adjusted in real time according to the axle load transfer degree, so that the wheel pressure and the vehicle axle load are kept in a certain relation, the wheels can be prevented from entering an ABS too early, the road adhesion force is fully utilized, and therefore the vehicle braking distance under the emergency braking working condition can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle braking, and in particular, relates to a control method for reducing the braking distance of a vehicle. Background Art

[0002] When the vehicle is in emergency braking (for example, moving forward), the vehicle will tilt forward, especially for vehicles with soft suspension, the tilt will be more obvious. At this time, the braking system will build pressure at the maximum pressure building rate. When the vehicle has not reached the maximum forward tilt and the suspension has not reached the maximum compression, the front wheels have already entered the ABS pressure relief, resulting in the adhesion of the ground not being used to the maximum extent, resulting in a loss of deceleration and an increase in braking distance, thus causing unnecessary traffic accidents.

[0003] Patent document with publication number CN108528446A discloses an automatic emergency brake assist system based on active suspension control. In the braking warning stage, the system simulates the forward tilting action of the vehicle during braking by simultaneously lowering the front suspension of the active suspension to a greater extent and the rear suspension of the active suspension to a lesser extent, thereby reducing the impact of emergency braking on the driver. The technical solution disclosed in the patent document also cannot solve the technical problems described above. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a control method for reducing the braking distance of a vehicle, the purpose of which is to reduce the braking distance of the vehicle under emergency braking conditions.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a control method for reducing the braking distance of a vehicle. When the vehicle performs emergency braking, the control system detects the degree of axle load transfer, and then adjusts the wheel pressure building rate in real time according to the degree of axle load transfer, so that the wheel pressure maintains a certain relationship with the degree of axle load transfer of the vehicle.

[0006] The control system detects the degree of axle load transfer through sensors, which are suspension height sensors of the front and rear suspensions of the vehicle.

[0007] When the vehicle performs emergency braking, the vehicle tilts forward. At this time, the control system obtains the compression A of the front suspension and the extension B of the rear suspension according to the suspension height sensor. The axle load transfer degree is the sum of the compression A and the extension B.

[0008] The control system is an electronically controlled hydraulic unit.

[0009] The control system is a brake-by-wire system.

[0010] The control system is ESC (Electronic Stability Control System).

[0011] The control method for reducing the braking distance of a vehicle of the present invention adjusts the wheel pressure building rate in real time according to the degree of axle load transfer so that the wheel pressure maintains a certain relationship with the vehicle axle load, thereby preventing the wheel from entering the ABS too early and making full use of the road adhesion, thereby reducing the vehicle braking distance under emergency braking conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] This specification includes the following drawings, which show the following contents:

[0013] Figure 1 It is a graph of the relationship between the maximum wheel pressure and the degree of axle load transfer;

[0014] Figure 2 It is the wheel pressure curve graph;

[0015] Figure 3 It is a schematic diagram of vehicle braking axle load transfer;

[0016] Figure 4 It is a schematic diagram of circuit pressure building control of the decoupled braking system of the present invention;

[0017] Figure 5 This is a wheel pressure curve diagram for a conventional vehicle during braking. DETAILED DESCRIPTION

[0018] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0019] The present invention provides a control method for reducing the braking distance of a vehicle. When the vehicle performs emergency braking, axle load transfer will occur in the vehicle. The control system detects the degree of axle load transfer, and then adjusts the wheel pressure building rate in real time according to the degree of axle load transfer, so that the wheel pressure and the degree of axle load transfer of the vehicle maintain a certain relationship, that is, the wheel pressure increases with the increase of the degree of axle load transfer of the vehicle.

[0020] Specifically, the technical problem to be solved by the present invention is: in an emergency braking condition, when the driver quickly steps on the brake pedal, the control system identifies the degree of compression of the suspension through the suspension height sensor, thereby determining the forward tilt degree and the forward tilt degree of the vehicle.

[0021] like Figure 1As shown, the control system adjusts the pressure building rate in real time so that the wheel (the front wheel of the vehicle in this case) pressure is consistent with the current forward tilt of the vehicle. When the forward tilt reaches the maximum, the braking force also reaches the maximum. In this way, the maximum adhesion provided by the ground during the process from the beginning of the forward tilt of the vehicle to the maximum forward tilt can be fully utilized. This prevents the wheel from entering the ABS pressure relief too early, which causes the deceleration loss, thereby achieving the purpose of shortening the braking distance.

[0022] Preferably, the control system detects the degree of axle load transfer through sensors, which are suspension height sensors of the front suspension and rear suspension of the vehicle.

[0023] like Figure 3 As shown in the figure, when the vehicle is in emergency braking (taking the vehicle moving forward as an example), the vehicle tilts forward. At this time, the control system obtains the compression A of the front suspension and the extension B of the rear suspension according to the suspension height sensor. The axle load transfer degree is the sum of the compression A and the extension B. A+B reflects the axle load transfer degree. The actual vehicle test calibrates the maximum wheel pressure (locking pressure) corresponding to A+B, and the result is as follows Figure 1 As shown, the P_max curve represents the degree of axle load transfer.

[0024] according to Figure 1 As a result, during emergency braking, the braking system first builds pressure in the wheel cylinder at the maximum pressure building rate. When the wheel cylinder pressure intersects the P_max curve, the wheel cylinder pressure building rate is limited to make the wheel cylinder pressure building rate consistent with the axle load transfer degree, that is, the wheel cylinder pressure building rate increases with the increase of the vehicle axle load transfer degree, and then the wheel pressure increases with the increase of the vehicle axle load transfer degree, preventing the wheel from entering the ABS pressure release too early and causing the deceleration loss, thereby achieving the purpose of shortening the braking distance. The actual pressure curve is as follows Figure 2 As shown, the P_act curve represents the wheel cylinder pressure building rate.

[0025] Preferably, the control system is an electronically controlled hydraulic unit, such as a brake-by-wire system or an ESC (electronic stability control system), which can achieve precise control of wheel pressure by controlling internal components (such as solenoid valves or boost cylinders).

[0026] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A control method for reducing the braking distance of a vehicle, characterized in that: When the vehicle performs emergency braking, the control system detects the degree of axle load transfer, and then adjusts the wheel pressure building rate in real time according to the degree of axle load transfer, so that the wheel pressure maintains a certain relationship with the degree of axle load transfer of the vehicle.

2. The control method for reducing the braking distance of a vehicle according to claim 1, characterized in that: The control system detects the degree of axle load transfer through sensors, which are suspension height sensors of the front and rear suspensions of the vehicle.

3. The control method for reducing the braking distance of a vehicle according to claim 2, characterized in that: When the vehicle performs emergency braking, the vehicle tilts forward. At this time, the control system obtains the compression A of the front suspension and the extension B of the rear suspension according to the suspension height sensor. The axle load transfer degree is the sum of the compression A and the extension B.

4. The control method for reducing the braking distance of a vehicle according to any one of claims 1 to 3, characterized in that: The control system is an electronically controlled hydraulic unit.

5. The control method for reducing the braking distance of a vehicle according to any one of claims 1 to 3, characterized in that: The control system is a brake-by-wire system.

6. The control method for reducing the braking distance of a vehicle according to any one of claims 1 to 3, characterized in that: The control system is ESC.

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