Method for managing the braking of a motor vehicle

Abstract

The invention relates to a method for managing the braking of a motor vehicle, the vehicle comprising an engine control unit configured to determine a first wheel torque setpoint according to the first depression level, the vehicle comprising a speed control device able to determine a second wheel torque setpoint, the speed control device being able to determine a third wheel torque setpoint when the determined wheel torque is higher than the second wheel torque setpoint, characterized in that the method comprises a step of the engine control unit maintaining the third wheel torque setpoint when the second depression level is strictly higher than 0, wherein the second wheel torque setpoint decreases proportionally to the increase in the second depression level.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: METHOD FOR MANAGING THE BRAKING OF A MOTOR VEHICLE

[0003]

[0001] The invention relates to the management of braking in motor vehicles.

[0004]

[0002] Prior art patent application EP3363696 is known, describing a speed control system with several disengagement modes selected by a brake pedal of an automated vehicle. The system comprises the brake pedal and a controller. Each disengagement mode is determined by the pressure exerted on the brake pedal, the duration of the pressure, or a combination of the pressure exerted on the brake pedal and the duration of the pressure. A first disengagement mode is the disengagement of the vehicle's acceleration control, while maintaining the vehicle's deceleration control. A second disengagement mode is the disengagement of both the vehicle's acceleration control and the vehicle's deceleration control. Another disengagement mode is the complete deactivation of the speed control system.The pressure applied to the brake pedal and / or the duration of brake pedal pressure is transmitted to the controller, which is responsible for providing a command to activate one of the disengagement modes. However, a drawback remains. When the vehicle is descending and / or heavily loaded, its speed may exceed the speed set by the cruise control system. Therefore, the driver will not exert the same force over the same duration to slow the vehicle down compared to driving on level ground. Similarly, when going uphill, the driver will not exert the same force and pressure duration to achieve the same braking effect as when going downhill, for example. The disengagement modes do not take into account the terrain on which the vehicle is traveling. They are therefore not suitable for all types of terrain.

[0005]

[0003] The objective of the present invention is to overcome these drawbacks and to enable linear braking of the vehicle when the cruise control is deactivated by the driver.

[0004] To achieve this objective, the invention proposes a method for managing the braking of a motor vehicle, said vehicle comprising an accelerator pedal configured to have a first depressment rate and a brake pedal configured to have a second depressment rate, said vehicle comprising an engine control unit configured to determine a first torque setpoint at the wheel as a function of the first depressment rate, said vehicle having a determined wheel torque, said vehicle comprising a speed control device capable of determining a second torque setpoint at the wheel when said speed control device is activated by the driver.said speed control device being capable of determining a third wheel torque setpoint when said determined wheel torque is greater than said second wheel torque setpoint and when said speed control device is activated, the second and third wheel torque setpoints determining the determined wheel torque, the third wheel torque setpoint being less than the second wheel torque setpoint, notable in that said method includes a step of maintaining the third wheel torque setpoint by the engine control unit when said second penetration rate is strictly greater than 0, said second wheel torque setpoint decreasing proportionally to the increase in the second penetration rate.

[0006]

[0005] Thanks to the invention, braking is linear because it is solely linked to the driver's will.

[0007]

[0006] Advantageously, said method includes a step of canceling the third torque setpoint to the wheel when said second sinking rate decreases to a predetermined threshold value.

[0008]

[0007] In this way, the reduction imposed by the third wheel torque setting is canceled at an appropriate time, that is, when the driver releases at least partially the brake pedal, rather than when he wishes to reduce the wheel torque more strongly.

[0009]

[0008] Advantageously, during said step of cancellation of the third wheel torque setting, said third wheel torque setting increases proportionally to the decrease of the second compression rate, said second compression rate decreasing when the driver releases said brake pedal, said third wheel torque setting being cancelled when said second compression rate decreases to the predetermined threshold value.

[0010]

[0009] Thus, the increase in the determined wheel torque is done gradually so as not to surprise the driver.

[0011]

[0010] Advantageously, said predetermined threshold value is equal to 0%.

[0012]

[0011] Thus, the speed regulation device is completely deactivated as soon as the driver fully releases the brake pedal.

[0013]

[0012] Preferably, said speed control device is an adaptive speed regulator, a fixed speed regulator, a speed limiter or a speed limiting device.

[0014]

[0013] The invention also relates to a computer program comprising instructions which, when said program is executed by a computer, lead the latter to implement the steps of the braking management process of a motor vehicle previously described.

[0015]

[0014] Furthermore, the invention relates to a motor vehicle comprising an engine control unit configured to implement the motor vehicle braking management method described above.

[0016]

[0015] Preferably, said vehicle is of the electric, hybrid or hydrogen type.

[0017]

[0016] The invention will be further detailed by the description of a non-limiting embodiment, and on the basis of the attached figure illustrating the invention, in which [Fig.1] represents a graph representing several parameters related to the braking of the vehicle as a function of time t.

[0018]

[0017] The invention relates to a method for managing the braking of a motor vehicle. Preferably, the motor vehicle is electric, hybrid, or hydrogen-powered. The vehicle includes an accelerator pedal configured to have a first depress rate and a brake pedal configured to have a second depress rate. Furthermore, the vehicle includes an engine control unit configured to determine a first wheel torque setpoint based on the first depress rate, i.e., based on the depress rate of the accelerator pedal. The vehicle has a predetermined wheel torque. The wheel torque is positive when the vehicle accelerates. The wheel torque is negative when the vehicle brakes.Furthermore, the vehicle is equipped with a speed control system configured to determine a second wheel torque setting when the driver activates the speed control system. For example, the speed control system is activated when the driver moves a lever located on the steering wheel. The primary function of the speed control system is to maintain a constant vehicle speed, regardless of the terrain. Thus, when driving downhill, it is necessary to reduce wheel torque to prevent unintended acceleration. Preferably, the speed control system is selected from among adaptive cruise control, fixed cruise control, a speed limiter, or a speed-limiting device.Adaptive cruise control, also known as adaptive cruise control, is a speed regulation system that, in addition to maintaining a constant speed, automatically adjusts the vehicle's speed based on the distance to the vehicle ahead. Fixed cruise control is another system that maintains a constant speed, regardless of the position of surrounding vehicles. A speed limiter is a device that allows the driver to set a maximum speed that the vehicle must not exceed. Unlike adaptive or fixed cruise control, the driver must manually maintain acceleration, but the system will prevent the vehicle from exceeding the preset speed.The speed limiter is a safety feature that restricts a vehicle's maximum speed to a predetermined value. This can be mandated by the manufacturer for safety reasons or activated voluntarily by the driver. The speed limiter is designed to prevent the risk of excessive speeds. Furthermore, the speed control system is capable of determining a third wheel torque setting when the specified wheel torque exceeds the specified second wheel torque setting and the speed control system is activated. The specified wheel torque is therefore determined based on the second and third wheel torque settings.During a step to maintain the third wheel torque setting, the engine control unit commands the maintenance of the third wheel torque setting when the second brake pedal pressure is strictly greater than 0. In other words, the third wheel torque setting is maintained when the driver applies force to the brake pedal. However, a second brake pedal pressure strictly greater than 0 causes the second wheel torque setting to decrease. The decrease in the second wheel torque setting is proportional to the increase in the second brake pedal pressure. Indeed, as in the prior art, the speed control device deactivates when the driver presses the brake pedal. This results in a decrease in the second wheel torque setting.The invention prevents the third wheel torque setting from being canceled simultaneously with the second wheel torque setting. This is because the third wheel torque setting is lower than the second wheel torque setting. When applied, the third wheel torque setting constantly reduces the vehicle's speed, resulting in braking. If the driver presses the brake pedal and the third wheel torque setting is canceled at the same time as the second wheel torque setting decreases, the braking effect of the third wheel torque setting is interrupted, which is contrary to the driver's intention to brake more effectively. Thanks to the invention, maintaining the third wheel torque setting as long as the driver applies force to the brake pedal allows for linear braking, tailored to the driver's desired braking force.In this case, the third wheel torque command is canceled by the engine control unit when the driver releases the brake pedal. Optionally, the method includes a step of canceling the third wheel torque command when the second brake pedal travel decreases to a predetermined threshold value. Preferably, during this step of canceling the third wheel torque command, the third wheel torque command increases proportionally to the decrease in the second brake pedal travel. This is because the second brake pedal travel decreases as the driver gradually releases the brake pedal. The third wheel torque command therefore increases gradually to achieve smoother braking, which is less likely to surprise the driver. The third command is completely canceled when the second brake pedal travel decreases to the predetermined threshold value.Preferably, the predetermined threshold value is equal to 0%. In other words, the brake pedal is fully released.

[0019]

[0018] Figure 1 is a graph representing several parameters related to vehicle braking as a function of time t. Part A represents the period during which the third wheel torque setpoint is maintained. Part B represents the transition period during which said third wheel torque setpoint increases proportionally to the decrease in the second compression rate. A first curve C1 represents the predetermined wheel torque, taking into account the second and third wheel torque setpoints, as a function of time t. A second curve C2 represents the evolution of the third wheel torque setpoint as a function of time t. A third curve C3 represents the evolution of the second wheel torque setpoint as a function of time t.A fourth curve, C4, represents the evolution of the second brake pedal pressure, that is, the evolution of the force exerted by the driver on the brake pedal, as a function of time t. During period A, the third wheel torque setting is constant, as shown on the second curve, C2, while the third curve, C3, decreases to progressively reduce the predetermined wheel torque represented by the first curve, C1. The evolution of the third curve, C3, is inversely proportional to the evolution of the fourth curve, C4. Indeed, as the driver increases the pressure on the brake pedal, the second wheel torque setting decreases proportionally. The third wheel torque setting is not affected because it remains constant as long as the driver applies force to the brake pedal. This results in an overall decrease in the predetermined wheel torque represented by the first curve, C1.During period B, the fourth curve, C4, gradually decreases as the driver progressively releases the brake pedal. This causes the second wheel torque setting to increase proportionally. The third wheel torque setting, represented by the second curve, C2, increases proportionally to the decrease in the second brake pedal travel, represented by the fourth curve, C4.

[0020]

[0019] The invention also relates to a computer program configured to implement the method described above. Furthermore, the invention relates to a motor vehicle comprising an engine control unit configured to implement said method.

Claims

DEMANDS 1. A method for managing the braking of a motor vehicle, said vehicle comprising an accelerator pedal configured to have a first depressment rate and a brake pedal configured to have a second depressment rate, said vehicle comprising an engine control unit configured to determine a first wheel torque setpoint as a function of the first depressment rate, said vehicle having a determined wheel torque, said vehicle comprising a speed control device capable of determining a second wheel torque setpoint when said speed control device is activated by the driver, said speed control device being capable of determining a third wheel torque setpoint when said determined wheel torque is greater than said second wheel torque setpoint and when said speed control device is activated,the second torque setpoint and the third wheel torque setpoint determining the determined wheel torque, the third wheel torque setpoint being lower than the second wheel torque setpoint, characterized in that said method comprises a step of maintaining the third wheel torque setpoint by the motor control unit when said second penetration rate is strictly greater than 0, said second wheel torque setpoint decreasing proportionally to the increase in the second penetration rate.

2. Method according to claim 1 characterized in that said method comprises a step of canceling the third torque setpoint to the wheel when said second sinking rate decreases to a predetermined threshold value.

3. A method according to claim 2 characterized in that, during said step of canceling the third wheel torque setting, said third wheel torque setting increases proportionally to the decrease in the second compression rate, said second compression rate decreasing when the driver releases said pedal brake, said third wheel torque setting being cancelled when said second sinking rate decreases to the predetermined threshold value.

4. A method according to claim 2 or 3 characterized in that said predetermined threshold value is equal to 0%.

5. A method according to any one of claims 1 to 4 characterized in that said speed control device is an adaptive speed regulator, a fixed speed regulator, a speed limiter, or a speed-limiting device.

6. Computer program comprising instructions which, when said program is executed by a computer, cause the computer to implement the steps of the braking management method of a motor vehicle according to any one of claims 1 to 5.

7. Motor vehicle comprising an engine control unit configured to implement the method of managing the braking of a motor vehicle according to any one of claims 1 to 5.

8. Vehicle according to claim 7 characterized in that said vehicle is of the electric, hybrid or hydrogen type.

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