METHOD FOR REGULATING A REGENERATIONAL BRAKING SYSTEM OF AN ELECTRIC OR HYBRID MOTOR VEHICLE

Abstract

The invention relates to a method for regulating a regenerative braking system of an electric or hybrid motor vehicle, comprising a step of calculating a brake temperature (E1) by said temperature measurement or estimation means; a step of increasing a regenerative braking torque setpoint (E2) when the brake temperature is above a first predetermined threshold temperature and when the brake pad depth is above a first predetermined threshold; and a step of further increasing the regenerative braking torque setpoint (E3) when the brake temperature is above the first predetermined threshold temperature and when the brake pad depth is above a second predetermined threshold, said increase being constant. Figure 1

Description

Title of the invention: METHOD FOR REGULATING A REGENERATIONAL BRAKING SYSTEM ELECTRIC OR HYBRID MOTOR VEHICLE

[0001] The invention relates to the various braking means of electric or hybrid motor vehicles, and to the cooperation of these various braking means.

[0002] Prior art patent application DE102019006733, which describes a method for decelerating a motor vehicle, is known. The vehicle includes a friction braking device and a regenerative braking device. The friction braking device and the regenerative braking device together cause an overall deceleration of the vehicle. The method includes an increase in the total deceleration when the operating temperature of the friction braking device is above a predetermined limit temperature. However, some drawbacks remain. The vehicle's deceleration is triggered when the temperature of the friction braking device is above a single limit temperature.Thus, the braking system may be activated late if this temperature threshold is high. Conversely, if it is low, deceleration is controlled in such a way as to prevent overheating of the friction braking system. However, if the friction braking system continues to heat up, deceleration is not accelerated, which poses a danger to the vehicle's occupants.

[0003] The objective of the present invention is to remedy these drawbacks and improve the safety of vehicle occupants in the event of brake overheating.

[0004] To achieve this objective, the invention proposes a method for regulating a regenerative braking system of an electric or hybrid motor vehicle, said vehicle having wheel torque, said vehicle comprising brakes and a brake pedal, said vehicle comprising a dissipative braking system and a regenerative braking system, the dissipative braking system being configured to determine a dissipative braking torque setpoint, the regenerative braking system being configured to determine a regenerative braking torque setpoint, said vehicle comprising a computer capable of determining a combined braking torque setpoint as a function of the dissipative braking torque setpoint and the regenerative braking torque setpoint, the combined braking torque setpoint being the sum of the dissipative braking torque setpoint and the regenerative braking torque setpoint,the combined braking torque setting determining the torque at the wheel, said brakes comprising a means for measuring or estimating the temperature, said brake pedal being configured to present, a deflection rate, the deflection rate being equal to 0% when said brake pedal is fully released, the deflection rate being equal to 100% when said brake pedal is fully depressed, notable in that said method comprises the following steps: - a step of measuring or calculating a brake temperature by said means of measuring or estimating temperature; - a step of increasing the regenerative braking torque setpoint when the brake temperature is above a first predetermined threshold temperature and when the sinking rate is above a first threshold of the predetermined sinking rate and below a second threshold of the predetermined sinking rate, the increase in the regenerative braking torque setpoint causing the increase in the combined braking torque setpoint; - a further increase in the regenerative braking torque setpoint when the brake temperature is above the first predetermined threshold temperature and when the sink rate is above a second predetermined sink rate threshold, said increase in the regenerative braking torque setpoint being constant, the further increase in the regenerative braking torque setpoint causing the increase in the combined braking torque setpoint.

[0005] Thanks to the invention, occupant safety is improved in the event of brake overheating.

[0006] Advantageously, said first threshold of the penetration rate is equal to 0% and said second threshold of the penetration rate is equal to 100%.

[0007] Preferably, said regenerative braking torque setpoint being equal to a first value when the brake temperature is between the first predetermined threshold temperature and a second predetermined threshold temperature, said regenerative braking torque setpoint being equal to a second value when the brake temperature is above the second predetermined threshold temperature, the second predetermined threshold temperature being above the first predetermined threshold temperature, the second regenerative braking torque setpoint value being above the first regenerative braking torque setpoint value.

[0008] In this way, if the estimated temperature of the brakes continues to increase, the deceleration provided by regenerative braking is improved.

[0009] Preferably, the first threshold of the sinking rate is equal to a first value and the second threshold of the sinking rate is equal to a first value when the brake temperature is between the first predetermined threshold temperature and the second predetermined threshold temperature, the first threshold of the the sinking rate being equal to a second value and the second sinking rate threshold being equal to a second value when the brake temperature is above the second predetermined threshold temperature, the first value of the first sinking rate threshold being greater than the second value of the first sinking rate threshold, the first value of the second sinking rate threshold being greater than the second value of the second sinking rate threshold.

[0010] In this way, the deceleration is adapted according to the estimated temperature of the brakes.

[0011] Advantageously, said vehicle includes a warning means, said method including a driver warning step during which said warning means is activated when the brake temperature is above the first predetermined threshold temperature.

[0012] In this way, the driver is informed of the greater deceleration of his vehicle in the event of braking, thus avoiding a surprise effect likely to generate dangerous behavior.

[0013] Preferably, said vehicle includes a dashboard, said warning means being a dashboard indicator light, said indicator light being configured to illuminate during said warning step.

[0014] A warning light on a dashboard is directly visible to the driver while driving.

[0015] Preferably, said vehicle includes a dashboard comprising a screen, said warning means being a message configured to be displayed on said screen during said warning step.

[0016] A message on a screen is clearer and does not require interpretation.

[0017] Furthermore, the invention relates to a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the steps of the method of regulating a regenerative braking system of an electric or hybrid motor vehicle previously described.

[0018] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates, in the form of a logic diagram, a method for regulating a regenerative braking system of an electric or hybrid motor vehicle according to an embodiment of the invention; - [Fig.2] represents a graph illustrating the evolution of the torque at the wheel in function of the position of the brake pedal according to one embodiment of the invention.

[0019] A method for regulating a regenerative braking system of an electric or hybrid motor vehicle is schematically illustrated in Figure 1 in the form of a flowchart. The vehicle includes brakes and a brake pedal. In addition, the vehicle includes a regenerative braking system and a dissipative braking system. The regenerative braking system is used in electric or hybrid vehicles to recover some of the kinetic energy during braking and convert it into electrical energy to recharge the vehicle's traction battery. This improves the vehicle's range. When the driver fully or partially releases the accelerator pedal, the vehicle brakes automatically. The dissipative braking system converts the vehicle's kinetic energy into heat to slow down or stop its movement.This is achieved primarily through brake discs or drums, where brake pads or linings exert friction on rotating surfaces, dissipating energy as heat. The dissipative braking system is configured to determine a dissipative braking torque setpoint. The regenerative braking system is configured to determine a regenerative braking torque setpoint. The vehicle has a control unit capable of determining a combined braking torque setpoint based on the dissipative braking torque setpoint and the regenerative braking torque setpoint. In effect, the combined braking torque setpoint is the sum of the dissipative braking torque setpoint and the regenerative braking torque setpoint. The combined braking torque setpoint determines the wheel torque applied to the vehicle, which in turn determines its speed.Dissipative braking complements regenerative braking to maintain a combined braking torque setting that reflects the driver's intent based on the brake pedal deflection. The deflection varies from 0% when the brake pedal is fully released to 100% when it is fully depressed. The vehicle's brakes include a means for measuring or estimating temperature. For example, this could be a temperature sensor that measures the vehicle's brake temperature in real time, either continuously or intermittently. During a step in calculating brake temperature (E1), the brake temperature is determined by this temperature measurement or estimation means.During a step of increasing a regenerative braking torque setpoint E2, the regenerative braking torque setpoint is increased when the brake temperature is above a first predetermined threshold temperature and when the brake pedal depress rate is above. to a first threshold of the predetermined depressment rate PI. The increase in the regenerative braking torque setpoint follows a monotonic evolution, which may be linear or non-linear. The increase in the regenerative braking torque setpoint results in an increase in the combined braking torque setpoint. Preferably, the first threshold of the depressment rate PI is equal to 0%, i.e., when the brake pedal is fully released. During a further increase in the regenerative braking torque setpoint E3, the regenerative braking torque setpoint is increased again when the brake temperature, calculated by said temperature measurement or estimation means, is above the first threshold temperature and when the depressment rate of said brake pedal is above a second threshold of the predetermined depressment rate P2.The increase in the regenerative braking torque setpoint is constant as a function of the brake pedal depressment rate. A further increase in the braking torque setpoint causes an increase in the combined braking torque setpoint. Preferably, the second depressment rate threshold P2 is equal to 100%, i.e., the brake pedal is fully depressed.

[0020] Figure 2 illustrates a graph showing the evolution of wheel torque CR as a function of brake pedal position PP according to an embodiment of the invention. The solid line represents braking when the brake temperature is below the first threshold temperature. The dashed line represents braking, i.e., the increase in wheel torque CR, when the brake temperature is above the first threshold temperature. When the compression ratio is below the first threshold of the compression ratio PI, the wheel torque CR is the same regardless of the brake temperature. When the compression ratio is between the first threshold of the compression ratio PI and the second threshold of the compression ratio P2, the wheel torque CR increases when the brake temperature is above the first threshold temperature. The evolution of the solid line is non-linear.When the penetration rate is greater than the second penetration rate threshold P2, the increase in torque at the CR wheel is constant.

[0021] Optionally, the first threshold of the compression rate PI and the second threshold of the compression rate P2 vary according to the brake temperature. The first threshold of the compression rate PI is equal to a first value and the second threshold of the compression rate P2 is equal to a first value when the brake temperature is between the first threshold temperature and a predetermined second threshold temperature. The first threshold of the compression rate PI is equal to a second value and the second threshold of the compression rate P2 is equal to a second value when the brake temperature is above the second threshold temperature. predetermined. The first value of the first threshold of the penetration rate PI is greater than the second value of the first threshold of the penetration rate PL. Furthermore, the first value of the second threshold of the penetration rate P2 is greater than the second value of the second threshold of the penetration rate P2. Preferably, the regenerative braking torque setpoint varies according to the brake temperature. The regenerative braking torque setpoint has a first value when the brake temperature is between the first predetermined threshold temperature and a second predetermined threshold temperature. The second predetermined threshold temperature is greater than the first predetermined threshold temperature.The regenerative braking torque setpoint has a second regenerative braking torque setpoint value when the brake temperature exceeds the second predetermined threshold temperature. This second regenerative braking torque setpoint value is higher than the first regenerative braking torque setpoint value. Optionally, the vehicle includes an instrument panel and a warning means. Preferably, the instrument panel includes a display. The warning means, preferably an instrument panel indicator light or a message, is designed to warn the driver that deceleration is more pronounced during a warning phase. When the warning means is an instrument panel indicator light, that light is configured to illuminate during the warning phase.When the warning method is a message, said message is configured to be displayed on said dashboard screen during said warning step.

[0022] In addition, the invention relates to a computer program configured to implement the steps of said method of regulating a regenerative braking system of an electric or hybrid motor vehicle previously described.

Claims

1. Demands Method for regulating a regenerative braking system of an electric or hybrid motor vehicle, said vehicle having wheel torque, said vehicle having brakes and a brake pedal, said vehicle having a dissipative braking system and a regenerative braking system, the dissipative braking system being configured to determine a dissipative braking torque setpoint, the regenerative braking system being configured to determine a regenerative braking torque setpoint, said vehicle having a control unit capable of determining a combined braking torque setpoint as a function of the dissipative braking torque setpoint and the regenerative braking torque setpoint, the combined braking torque setpoint being the sum of the dissipative braking torque setpoint and the regenerative braking torque setpoint, the combined braking torque setpoint determining the wheel torque,said brakes comprising a means for measuring or estimating the temperature, said brake pedal being configured to exhibit a deflection rate, the deflection rate being equal to 0% when said brake pedal is fully released, the deflection rate being equal to 100% when said brake pedal is fully depressed, characterized in that said method comprises the following steps: - a step of measuring or calculating a brake temperature (El) by said means of measuring or estimating temperature; - a step of increasing the regenerative braking torque setpoint (E2) when the brake temperature is above a first predetermined threshold temperature and when the brake pad depth is above a first predetermined threshold (PI) and below a second predetermined threshold (P2), the increase in the regenerative braking torque setpoint causing an increase in the combined braking torque setpoint; - a further step of increasing the regenerative braking torque setpoint (E3) when the brake temperature is above the first predetermined threshold temperature and when the brake pad depth is above a second threshold predetermined indentation (P2), said increase in regenerative braking torque setpoint being constant, the further increase in regenerative braking torque setpoint causing the increase in combined braking torque setpoint.

2. The method according to claim 1 characterized in that said first penetration rate threshold (PI) is equal to 0% and said second penetration rate threshold (P2) is equal to 100%.

3. A method according to claim 1 or 2 characterized in that said regenerative braking torque setpoint is equal to a first value when the brake temperature is between the first predetermined threshold temperature and a second predetermined threshold temperature, said regenerative braking torque setpoint is equal to a second value when the brake temperature is above the second predetermined threshold temperature, the second predetermined threshold temperature being above the first predetermined threshold temperature, the second regenerative braking torque setpoint being above the first regenerative braking torque setpoint.

4. A method according to claim 3 characterized in that the first threshold of the sinking rate (PI) is equal to a first value and the second threshold of the sinking rate (P2) is equal to a first value when the brake temperature is between the first predetermined threshold temperature and the second predetermined threshold temperature, the first threshold of the sinking rate (PI) being equal to a second value and the second threshold of the sinking rate (P2) being equal to a second value when the brake temperature is greater than the second predetermined threshold temperature, the first value of the first threshold of the sinking rate (PI) being greater than the second value of the first threshold of the sinking rate (PI), the first value of the second threshold of the sinking rate (P2) being greater than the second value of the second threshold of the sinking rate (P2).

5. A method according to any one of claims 1 to 4, characterized in that said vehicle comprises a warning means, said method comprising a driver warning step during which said warning means is activated when the brake temperature is above the first predetermined threshold temperature.

6. Method according to claim 5 characterized in that said vehicle comprises a dashboard, said warning means being a dashboard indicator light, said indicator light being configured to illuminate during said warning step.

7. Method according to claim 5 or 6 characterized in that said vehicle comprises a dashboard including a screen, said warning means being a message configured to be displayed on said screen during said warning step.

8. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to implement the steps of the method for regulating a regenerative braking system of an electric or hybrid motor vehicle according to any one of claims 1 to 7.

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