FR3008367A1 - "METHOD FOR CONTROLLING THE IMMOBILIZATION OF A MOTOR VEHICLE BY AUTOMATIC ACTUATION OF THE SERVICE BRAKE" - Google Patents

Abstract

The invention relates to a method for controlling the temporary immobilization of an automobile vehicle (10) driven by an electric motor (12), the method comprising: a first step (E1) for detecting the temporary stopping of the vehicle (10) during which it is determined whether conditions for starting the temporary stopping of the vehicle are satisfied; a second vehicle immobilization step (E2) that is triggered when all the conditions of the start of a temporary stop are satisfied; characterized in that during the second immobilization step (E2), an electronic control unit (28) operates a vehicle service brake system.

Description

The invention relates to a method of temporary immobilization of a vehicle with an electric motor. The invention relates more particularly to a method of controlling the temporary immobilization of a motor vehicle driven by an electric motor which is capable of providing a traction torque and which is permanently coupled with the driving wheels of the vehicle, the vehicle being equipped with a service brake system comprising: - at least one braking member which is capable of applying a braking torque to the vehicle wheels to slow down or even immobilize the vehicle; a first control member for the intensity of the braking torque that can be actuated by the driver; a second device for controlling the intensity of the braking torque that can be actuated by an electronic control unit; - At least one service actuating device of the braking member which is alternately controlled by the first control member and the second control member; the method comprising: - a first step of detecting the temporary stopping of the vehicle during which it is determined whether the conditions for starting the temporary stopping of the vehicle are satisfied; a second vehicle immobilization step that is triggered when all the conditions of the beginning of a temporary stop are satisfied. Motor vehicles with combustion engines are subject to the phenomenon of "stall" as soon as the drive shaft is forced to turn at an insufficient speed. To solve this problem, vehicles with combustion engines are generally equipped with clutch devices that are arranged in the drive train between the combustion engine and the driving wheels of the vehicle.

Motor vehicles driven by an electric motor are not subject to these constraints. An electric motor can not "stall". Thus, the clutch devices are absent from the traction chains of electric vehicles. The electric motor is therefore permanently coupled to the drive wheels of the vehicle. In addition, because of the absence of clutch device, the driver has only two control pedals. A first brake pedal is for controlling the service brake of the motor vehicle, while a second accelerator pedal is for controlling the traction torque supplied to the drive wheels by the electric motor. This configuration is identical to that of motor vehicles with combustion engines equipped with an automatic gearbox.

Because of this common configuration, it is known to control the electric motor of the vehicle so as to simulate the behavior of a vehicle with automatic gearbox. Thus, the electric motor is controlled so as to permanently provide at least a minimum traction torque which is positive. When the vehicle is stationary and the driver releases the brake pedal, this minimum traction torque allows the vehicle to accelerate gradually and smoothly even before the driver presses on the accelerator pedal. This type of driving similar to that of an automatic transmission vehicle is also known as the Anglo-Saxon term "ramping". This type of driving is particularly popular when the vehicle is caught in a traffic jam, because the driver does not have to operate the accelerator pedal to move forward. However, this type of driving requires the driver to keep the service brake pedal depressed permanently when the vehicle is temporarily stopped for a prolonged period, for example at a red light. But this obligation of permanent braking is a constraint not appreciated by drivers. To avoid having to constantly use the service brake, the driver can also use a parking brake of the vehicle, including a parking brake, to immobilize the vehicle. Nevertheless, the driver must then voluntarily release the parking brake before it can advance again.

To solve these problems, the invention proposes a method of the type described above, characterized in that during the second immobilization step, the second control member is actuated automatically by the electronic control unit so as to apply a torque high intensity braking via the service actuating device. According to other features of the invention: - in the second step, a signaling means is activated to indicate to the driver of the vehicle that the second immobilization step is engaged; the first control member is formed by a brake pedal; the first step comprises the checking of the parameters of actuation of the brake pedal indicating a will of temporary stopping of the vehicle, such as the total release of the brake pedal after the application of a pressure greater than a determined threshold; and / or the total release of the brake pedal after a brake pedal bearing travel greater than or equal to a determined distance; the first step comprises verifying vehicle state parameters indicating that the vehicle is stationary, such as the speed of rotation of the wheels and / or the traction torque produced by the engine and / or the acceleration of the vehicle; the first step comprises verifying that no traction torque is required by the driver; - The service actuating device is a piston which is controlled by a hydraulic circuit which is capable of transmitting the actuation order in the form of a pressure increase, the second control member being formed by a pump and / or a piston adapted to increase the pressure in the hydraulic circuit; the service actuation device is an electric actuator; the method comprises a third step of detecting the end of the temporary stopping of the vehicle during which it is determined whether conditions of the end of the temporary stopping of the vehicle are satisfied; the third step comprises the verification of the control by the driver of a traction torque; the third step comprises the verification of a new actuation of the first control member; the method comprises a fourth stage of immobilization of the vehicle which is triggered when at least one temporary end-of-stop condition of the vehicle is satisfied and during which the braking torque is controlled at zero via the service actuation device; the braking torque is progressively decreased during the fourth step; - In the fourth step, a signaling means is activated to indicate to the driver of the vehicle that the fourth stage of end of immobilization is engaged. Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: FIG. 1 is a schematic view from above which represents the traction chain and braking systems of an electric motor vehicle in which the process carried out according to the teachings of the invention is carried out; FIG. 2 is a block diagram which represents the method according to the teachings of the invention. In the remainder of the description, elements having an identical structure or similar functions will be designated by the same references. There is shown in Figure 1 a vehicle 10 automobile. The vehicle 10 is driven by an electric motor 12 which rotates two driving wheels 14 which are here arranged at the rear of the vehicle 10. The vehicle 10 also comprises two non-driving wheels 16 which are arranged at the front. The electric motor 12 is coupled to the drive wheels via a longitudinal motor shaft 18 which drives two transverse transmission coaxial shafts 25 via a differential 22. Each transmission shaft 20 is attached to a drive shaft. driving wheel 14 associated. A gearbox 24 is further interposed between the electric motor 12 and the motor shaft 18. Since the electric motor 12 can not stall, the traction chain does not have a clutch device. As a result, the electric motor 12 is permanently coupled with the driving wheels.

The electric motor 12 is capable of supplying a traction torque Cr to the driving wheels 14. For this purpose, the cockpit of the vehicle 10 is equipped with an accelerator control member which is here formed by a pedal The accelerator pedal 26 is adapted to send a signal representative of the required traction torque "Cr" up to an electronic control unit. This electronic control unit then controls the electric motor 12 to provide the required traction torque T. The vehicle 10 is also equipped with a service brake system which is controlled by the driver of the vehicle 10 in order to slow down the vehicle 10, or even completely immobilize the vehicle 10.

The service brake system comprises at least one braking member which is capable of applying a controlled braking torque "Cf" to an associated wheel 14, 16 of the vehicle 10 in order to slow down or even immobilize the vehicle 10. The vehicle 10 comprises here four braking members each of which is associated with a wheel 14, 16. Each braking member 30 is for example formed by a disk brake. Alternatively, at least the braking members associated with the rear wheels of the vehicle are formed by drum brakes. The service brake system also comprises a first control member of the torque "Cf" braking force which can be actuated by the driver. The control member is for example formed by a brake pedal 30 which is arranged in the cockpit of the vehicle. The intensity of the braking torque "Cf" is, for example, a function of the pressure applied to the braking pedal 32 and / or of the braking pedal 32 and / or of the bearing speed.

The service brake system also comprises a device 34 for transmitting the order of actuation of the first control member 32 to each braking member. In the example shown in Figure 1, the transmission device 34 is an electrical system, also known by the Anglo-Saxon name "brake by wire". The transmission device 34 is formed by means 36 for transmitting a signal representative of the intensity of the braking torque "Cf" and by means 38 for receiving said signal.

According to the proposed example, the signal representative of the intensity of the braking torque "Cf" is derived from one or more load bearing sensors of the brake pedal 32. The signal transits here by a wired connection in the form of electrical pulses. A pressing on the brake pedal 32 is detected by the sensor. The signal is then transmitted to each receiver 38 arranged near a wheel 14, 16 associated. The signal passes through the electronic control unit 28 here. The service brake system comprises four service actuating devices 40 each of which is associated with a braking member. Each service actuating device 40 is here formed by an electric actuator which makes it possible to actuate the associated braking member 30 towards the required braking position as a function of the signal received by the receiving means 38 in order to brake the wheels 14 , 16 with the "Cf" braking torque required. According to a not shown variant of the invention, the transmission device is formed by a hydraulic circuit which is capable of transmitting the actuation order in the form of a pressure increase. The brake pedal then makes it possible to actuate a piston that increases the pressure in the hydraulic circuit. The hydraulic fluid echoes this increase in pressure to the service actuating device formed by a jack which actuates the braking member to the required braking position. According to another variant not shown of the invention, the transmission device is both electrical and hydraulic.

In this case, the transmission of the actuation command is electric from the pedal to a receiver that actuates a pump. The pump controls the pressure in a hydraulic circuit that transmits the actuation command from the receiver to the main actuating member formed by a jack. The vehicle 10 also comprises a second member 42 for controlling the intensity of the braking torque which can be actuated by the electronic control unit 28. The second control member 42 is capable of being actuated automatically by the electronic control unit 28 so as to apply a high intensity braking torque "Cf" via the transmission device 34. In the case of the totally electric transmission device 34, as shown in FIG. 1, the second control member 42 is formed by a device for transmitting a signal representative of the required braking torque "Cf". by the electronic control unit 28 to each service actuating device 40. The second control member 42 is here integrated with the electronic control unit 28. Alternatively, when the service actuating device is formed by a hydraulic cylinder, the second control member is formed by a pump and / or a piston adapted to increase the pressure in the hydraulic circuit.

The second control member 42 can also be used by an active vehicle safety method such as a vehicle stabilization process, better known by its Anglo-Saxon name "Electronic Stability Program" or "ESP".

The vehicle 10 furthermore comprises a parking brake system which is used solely to immobilize the vehicle 10. The parking brake system comprises at least one parking control actuating device 44 of a parking braking device, this device 44 of parking actuation being distinct from the main actuating device. This is for example a hand brake 46 which is capable of actuating the braking members 14 of the rear wheels 14 via a lever 44 pulled by a cable 48, in particular when said braking members 30 are formed by drum brakes. In this case, the parking actuation device 44 is formed by the lever, and the transmission device 48 is formed by the traction cable.

According to a variant not shown of the invention, the parking brake system comprises a retractable finger which is capable of occupying an extended position in which it blocks the rotation of the motor shaft. The retractable finger is for example controlled from the cockpit via a gear lever likely to occupy a "parking" blocking position. The electric motor 12 of the vehicle 10 is here controlled so as to provide at least a minimum positive torque "Ctmin" of traction when the vehicle is in use and when the accelerator pedal 26 is not requested by the driver. . In this way, the vehicle 10 behaves in the same manner as a vehicle with an automatic transmission. In particular, a "ramping" behavior is observed which allows the stationary vehicle to accelerate progressively as soon as the service and parking brakes are released. The invention relates to a control method for temporarily immobilizing the vehicle 10, for example at a red light, by automatically using the service brake system without the driver having to keep the brake pedal 32 depressed. As shown in FIG. 2, the method comprises a first step "El" detecting the temporary stopping of the vehicle 10 during which it is determined whether at least certain conditions of the beginning of the temporary stopping of the vehicle 10 are satisfied. The first step "El" comprises the verification of operating parameters of the brake pedal 32 indicating a temporary stopping will of the vehicle 10. Among the operating parameters of the brake pedal 32, mention may be made of: total release of the brake pedal 32 just after the application by the driver of a pressure "Pr greater than a threshold" Ps "determined and / or - the total release of the brake pedal 32 after a race" Dr d the brake pedal is greater than or equal to a specified distance; and / or - the complete release of the brake pedal 32 after a depression at a speed greater than a threshold speed. In a variant, when the service actuation device is formed by a hydraulic cylinder, the first parameter relating to the pressing pressure on the brake pedal can be determined by measuring the pressure of the hydraulic brake fluid in the hydraulic circuit. The first step "El" also comprises the verification of vehicle state parameters indicating that the vehicle 10 is at a standstill. Amongst these state parameters, mention may be made of: the speed "V" of rotation of the wheels 14, 16 is zero; And / or - the torque "Cr of traction produced by the electric motor 12 is minimal, and / or - the longitudinal acceleration of the vehicle 10 is zero, and / or - the transverse acceleration of the vehicle 10 is zero; or - the normal acceleration of the vehicle 10 is zero, and / or - the inclination of the vehicle 10. The first step "El" also includes the verification that no torque "Cr traction is required by the driver, for example by checking that the accelerator pedal 26 is completely released.

These various parameters are verified by the electronic control unit 28 as a function of measurement signals emitted by appropriate sensors distributed in the vehicle. Such sensors are well known to those skilled in the art and will not be described in more detail later.

These various parameters to be checked during the first step "El" have been cited as an example. Only some of these parameters can be verified during the first "El" step without departing from the spirit of the invention, provided that the combination of selected parameters is representative of a temporary stopping of the vehicle 10 of the driver's share. Any other parameter or any combination of parameters representative of the temporary stopping of the vehicle by the driver can be taken into account during this first step "El". In the method represented by an example in FIG. 2, three conditions for starting the temporary stopping of the vehicle 10 have been selected. The conditions for starting the temporary stopping of the vehicle 10 verified during the first step "El" are as follows: the total release of the brake pedal 32 just after the application by the driver of a pressure "Pr greater than a determined threshold" Ps ", and the speed" V "of rotation of the wheels 14, 16 is zero; and - the accelerator pedal 26 is completely released When at least one of the conditions of the temporary start of the vehicle 10 is not satisfied, the process is repeated without any action on the service brake system. the conditions of the beginning of temporary stop are satisfied, a second step "E2" of immobilization of the vehicle 10 is triggered.In this second step "E2" of immobilization, the second control member 42 is actuated automatically. by the electronic control unit 28 so as to apply a high intensity braking torque "Cf" through each service actuating device 40. The "Cf" braking torque is sufficient to completely immobilize the vehicle 10.

During the second step "E2" of immobilization, a means (not shown) signaling is activated to indicate to the driver of the vehicle that the second step "E2" of immobilization is engaged. These are, for example, visual and / or sound and / or vibratory prevention means.

Preferably, but not necessarily, during this second step "E2", the electronic control unit 28 sends an order to the electric motor 12 to stop producing the traction torque "Ctmin". The electric motor 12 then produces no torque "Cr traction.

The method includes a third step "E3" for detecting the end of a temporary stop during which it is determined whether conditions for the end of the temporary stopping of the vehicle 10 are satisfied. During this third detection step "E3", the actions performed during the second step "E2" continue to apply to the vehicle 10 so that the latter remains immobilized.

Any parameter or combination of parameters representative of the driver's willingness to restart the vehicle 10 can be taken into account. These parameters are verified by the electronic control unit.

By way of example, the third step "E3" comprises the following checks - the control by the driver of a torque "Cr of traction by pressing on the accelerator pedal 26, or - a new actuation of the brake pedal 32 .

As long as neither of these two conditions is satisfied, the vehicle 10 remains immobilized by actuation of the service brake system by the electronic control unit 28. When at least one of the conditions of end of temporary stopping of the vehicle is satisfied, a fourth step "E4" end of immobilization of the vehicle 10 is triggered. During this fourth step "E4", the electronic control unit 28 actuates the service actuating devices 40 so as to cancel the braking torque "Cf". Simultaneously, the electronic control unit 28 sends the electric motor 12 the order to produce at least the minimum traction torque "Ctmin", or even the torque "Cr of traction required by the driver when the pedal 26 is depressed. In the fourth step "E4", a signaling means is activated to indicate to the driver of the vehicle that the fourth step "E4" of the end of immobilization is engaged. signaling used in the second step "E2" To avoid surprising the driver, during this fourth step "E4", the torque "Cf" braking is decreased gradually.

The method carried out according to the teachings of the invention allows the driver to temporarily immobilize the vehicle 10 without having to permanently apply the brake pedal 32. In addition, this method exempts the driver from having to use the parking brake system. The vehicle 10 is then restarted in a completely natural manner, without the driver having to think about deactivating the parking brake system.

Claims (11)

REVENDICATIONS1. A method for automatically controlling the temporary immobilization of an automobile vehicle (10) driven by an electric motor (12) which is capable of providing a traction torque (Cf) and which is permanently coupled with driving wheels (14) of the vehicle (10), the vehicle (10) being equipped with a service brake system comprising: - at least one braking member (30) which is capable of applying a braking torque (Cf) to the wheels ( 14, 16) of the vehicle (10) to slow down or even immobilize the vehicle (10); - A first member (32) for controlling the torque (Cf) braking intensity which is capable of being actuated by the driver; - a second member (42) for controlling the braking torque (Cf) which can be actuated by an electronic control unit (28); at least one device (40) for operating the braking member (30) which is alternately controlled by the first control member (32) and by the second control member (42); the method comprising: - a first step (E1) for detecting the temporary stopping of the vehicle (10) during which it is determined whether conditions for starting the temporary stopping of the vehicle are satisfied; a second vehicle immobilization step (E2) that is triggered when all the conditions of the start of a temporary stop are satisfied; Characterized in that during the second immobilization step (E2), the second control member (42) is actuated automatically by the electronic control unit (28) so as to apply a strong braking torque (Cf). intensity through the service actuating device (40). 2. Method according to the preceding claim, characterized in that, during the second step (E2), a signaling means is activated to indicate to the driver of the vehicle (10) that the second step (E2) of immobilization is engaged. 3. Method according to any one of the preceding claims, characterized in that the first member (32) of control is formed by a brake pedal. 4. Method according to the preceding claim, characterized in that the first step (El) comprises the verification of operating parameters of the brake pedal (32) indicating a temporary stopping will of the vehicle (10), such as the total release of the brake pedal (32) after the application of a pressure greater than a determined threshold and / or the total release of the brake pedal (32) after a bearing stroke of the pedal (32) of brake greater than or equal to a specified distance. 5. Method according to any one of the preceding claims, characterized in that the first step (El)) comprises the verification of vehicle state parameters indicating that the vehicle (10) is at a standstill, such as the speed of rotation of the wheels and / or the traction torque produced by the engine and / or the acceleration of the vehicle. 25 6. Method according to any one of the preceding claims, characterized in that the first step (El)) comprises the verification that no torque (Ct) traction is required by the driver. 7. Method according to any one of the preceding claims, characterized in that the service actuating device (40) is a piston which is driven by a hydraulic circuit which is capable of transmitting the actuation order in form. a pressure increase, said second control member (42) being formed by a pump and / or a piston adapted to increase the pressure in the hydraulic circuit. 8. Method according to any one of claims 1 to 6, characterized in that the device (40) for operating service is an electric actuator. 9. Method according to any one of the preceding claims, characterized in that it comprises a third step (E3) for detecting the end of the temporary stopping of the vehicle (10) during which it is determined whether conditions of end of temporary stop of the vehicle (10) are satisfied. 10. Method according to the preceding claim, characterized in that the third step (E3) comprises the verification of the control by the driver of a torque (Ct) traction. 15 11. Method according to any one of claims 9 to 10, characterized in that it comprises a fourth step (E4) of immobilization end of the vehicle (10) which is triggered when at least one end condition of Temporary stopping of the vehicle (10) is satisfied and during which the braking torque (Cf) is controlled at zero via the service actuating device (40).