WO2009101331A1

WO2009101331A1 - Method of operating a motor vehicle hill start assistance system

Info

Publication number: WO2009101331A1
Application number: PCT/FR2009/050178
Authority: WO
Inventors: Olivier Cayol; Alessandro De-Rinaldis; Richard Pothin
Original assignee: Renault S.A.S.
Priority date: 2008-02-05
Filing date: 2009-02-05
Publication date: 2009-08-20
Also published as: FR2927040A1; FR2927040B1

Abstract

Method of operating a motor vehicle hill start assistance system comprising a gear box equipped with a crawling means, characterized in that the crawling means is inhibited or uninhibited according to the gradient of the ground on which the vehicle is standing.

Description

Method of operating an assistance system for starting a motor vehicle uphill

The present invention relates to an assistance system for starting a motor vehicle uphill. The invention also relates to a method of operating such a system. The invention also relates to a software implementing such a method. The invention finally relates to a motor vehicle comprising a hill start assistance system. Studies are now being conducted to integrate active systems in motor vehicles. The purpose of these systems is to improve the behavior of the vehicle and, consequently, to improve the safety of the occupants of the vehicle.

On today's vehicles, starting on a hill is a source of stress and, in some cases, a risk for the driver who tries as much as possible to limit the recoil of the vehicle during a take-off on a slope, ie say in the phase where the vehicle starts to leave its immobile state to move. Generally, when starting on a hill, the driver moves his foot from the brake pedal as fast as possible to the accelerator pedal, or simultaneously acts on the accelerator pedal and the hand brake lever. dosing his actions on each of these organs.

It is nevertheless known assistance systems or hill start assistance to avoid this stress by simplifying the actions that must execute the driver to move the vehicle.

WO 82/02176 discloses a device enabling a motor vehicle to avoid advancing without the driver acting on the accelerator. Indeed, it is known that automated transmissions produce an effect called "rampage", that is to say a tendency of the vehicle to move against the intention of the driver while the transmission mode selector lever is in the forward or reverse position. This effect is due to the architecture of the automated gearbox which causes a low torque to be transmitted from the engine to the wheels as soon as the transmission mode selector lever is in the forward or reverse position. To remedy this phenomenon of rampage which can be seen as a disadvantage, the device described has means of action on the brakes of the vehicle as the driver does not act on the accelerator pedal. Such a device has a completely different operation of the system proposed in the present invention. In addition, it should be noted that the device described in the application WO 82/02176 can generate a consumption of the clutch faster and thus reduce the life of the automated transmission. There is also a safety problem because when the vehicle is immobilized, the driver could leave with all the risks that ensue.

Application FR 2 875 202 also discloses a vehicle control method in which the rampage is controlled in terms of torque or speed, depending on whether the objective is to avoid the movement of the vehicle on a slope or to move the vehicle to a vehicle. given speed. Indeed, the ramping torque can be used to prevent the vehicle from moving in a slope. However, such a method permanently activates the clutch of the transmission which could overheat if the gearbox has a "dry" clutch: this is particularly the case of robotized or dual-clutch gearboxes. In these cases, such a control method would not be applicable because the life of the clutch would be seriously reduced.

Finally, there is known from Application FR 2 552 190 a system in which a motor vehicle is stopped while its engine is running. when the transmission mode selection lever is in the forward or reverse position, the transmission of torque between the engine and the drive wheels of the vehicle is completely interrupted. This is achieved by automatically placing the transmission device in neutral. In this way, the fuel consumption can be reduced and the crawling effect of the vehicle avoided. With such a system, there is no answer to the problem of hill start. In addition, this system increases the reaction time of the vehicle which could therefore move back in a hill.

The object of the invention is to provide a system for assisting the starting of a motor vehicle on the hill to obviate the disadvantages identified above and to improve the assistance systems known from the prior art. In particular, the invention proposes an assistance method making it possible to use the ramping effect of an automated or robotic gearbox to assist in hill start without limiting the life of the gearbox and in particular the life of the clutch of the gearbox.

The method according to the invention governs the operation of an assistance system for starting a vehicle on a hill, comprising a gearbox provided with a ramping means. 11 is characterized in that the crawling means is inhibited or not inhibited depending on the slope of the ground on which the vehicle is.

The crawling means may be inhibited when the slope of the ground on which the vehicle is located is greater than a first threshold value of between 0% and 15% and preferably between 2% and 10%. The ramping means can be inhibited when the position value of an acceleration control member is smaller than a second threshold value, this second threshold value being dependent on the slope of the ground on which the vehicle is located.

The second threshold value may be constant, in particular zero, when the slope of the slope of the ground on which the vehicle is located is less than a third threshold value of between 0% and 15% and preferably between 2% and 10%. .

A brake device may be activated when the ramping means is inhibited and the hill start assist system is to be active.

A brake device may be activated or deactivated depending on whether the crawling means is sufficient or not to retain the vehicle.

According to the invention, the assistance system for starting a vehicle on a hill includes hardware and / or software means for implementing the previously defined operating method.

The material means may comprise a unit for processing and controlling a brake device.

The material means may comprise a gearbox provided with a means of creep that can be inhibited and a means for determining the slope of the ground on which the vehicle is located.

The means for determining the slope of the ground on which the vehicle is located can provide a slope value to the processing and control unit and to the gearbox. The means of determining the slope of the ground on which the vehicle is located can provide a slope value to the processing and control unit and the processing and control unit can control the inhibition of the ramping means of the vehicle. gearbox.

According to the invention, a motor vehicle comprises a hill start assistance system defined above.

The appended drawing shows, by way of example, two embodiments of a hill start assist system according to the invention.

Figure 1 is a diagram of a first embodiment of a hill start assist system according to the invention.

Figure 2 is a diagram illustrating the principle of operation of the first embodiment of a hill start assist system according to the invention.

Figure 3 is a flow chart detailing an embodiment of the method of operation of the first embodiment of a hill start assist system according to the invention.

Figure 4 is a diagram of a second embodiment of a hill start assist system according to the invention.

Figure 5 is a diagram illustrating the principle of operation of the second embodiment of a hill start assist system according to the invention. FIG. 6 is a flowchart detailing an embodiment of the method of operation of the second embodiment of a hill start assist system according to the invention.

Hill-start assist systems for vehicles with an automated (automated or robotic) gearbox may use not only a brake device but also the engine energy to hold the vehicle on a slope. Indeed, according to the various technical solutions adopted, automated gearboxes can indeed provide ramping on slopes that typically range up to 10 - 12% inclination. In this case, the creeping effect produced by the gearbox can avoid the recoil of the vehicle without the need for a brake device. On the other hand, for larger slopes, the ramping torque is insufficient to hold the vehicle in the slope. A brake device must be activated to prevent the vehicle from moving.

A first embodiment of a system for assisting or starting a motor vehicle on a hill, shown in FIG. 1, mainly comprises a brake device 14 acting on wheels 18 of the vehicle, a box of automated speeds 17 (for example robotized or automatic) for transmitting mechanical power from a motor 16 for driving the vehicle to the wheels, a logic unit 13 for processing and controlling the brake device and a means 15 for determining (by measurement and / or estimate) of the slope of the ground on which the vehicle is resting.

The assistance system may interact with vehicle movement control members 12, in particular a vehicle accelerator control member such as a pedal. The system can receive from these organs information such as accelerator pedal position information and / or pressure information exerted on one of the control members.

The assistance system is in interaction with the engine 16. In fact, the power of the latter is transmitted to the gearbox and information can be transmitted to the processing and control unit.

The gearbox includes a ramping means 19. This means produces a ramping effect, that is, it tends to set the vehicle in motion against the intention of the driver while the gear selector lever transmission mode is in the forward or reverse position. By "against the intention of the driver" is meant that it does not act on the accelerator member. It is possible to inhibit the ramping means. In its inhibited state, the ramping effect is inhibited.

The device that controls and controls the gearbox may inhibit ramping at the request of another system, or if the device is able to verify that conditions are being met, such as the slope of the ground on which the vehicle is located. is greater than a slope threshold.

The slope determining means sends slope value information to the processing and control logic unit and the gearbox. Thus, the determination means is shared between the gearbox and a brake system including the brake device 14 and the logic unit 13 for processing and control.

As will be seen in more detail later, depending on the slope value provided by the determining means, the ramping means 19 is inhibited or not. According to the illustration of FIG. 2, in one embodiment of the method of operation of the system, the means ramping is not inhibited if the slope is lower than a first slope threshold and inhibited in the opposite case. For example, the first threshold of slope can be between 0 and 15%, and preferably can take any value between 2 and 10%. Of course, the slope value must be counted algebraically taking into account the direction of movement of the desired vehicle;

if the slope tends to drive the vehicle in reverse and the direction of travel of the desired vehicle is forward, the means of ramping is not inhibited, in the same situation, if the direction of movement of the desired vehicle is In reverse, the creeping means is inhibited.

When the crawling means is inhibited, it is the brake device which is activated to retain the vehicle in the slope, if it is necessary to retain it. The brake device is controlled by the processing and control unit. The latter sends him an activation or deactivation information and, if necessary, a control set of the braking torque,

The assistance system described above comprises hardware and / or software means for governing its operation in accordance with the method that is the subject of the invention. These means comprise in particular a means for interpreting slope value information and for translating this information into an inhibition or non-inhibition control of the ramping means, a means for interpreting a value information of slope, motor information and action information on control members of the movement of the vehicle and translation of this information into an activation or deactivation command of the brake device and, if necessary, a set of braking. The means mentioned in the preceding paragraph can at least partially be achieved by computer programs.

One embodiment of a method of operation of the assistance system mentioned above is described below with reference to FIG.

In a first step 100, the value of the slope of the so! on which is the vehicle,

In a second step 110, the value of the slope determined in the preceding step is compared with a first threshold value of slope.

If the determined slope value is greater than the threshold value, a step 120 is set in which the ramping means is inhibited and in which the brake device is activated.

If the determined slope value is lower than the threshold value, a step 130 is taken in which the crawling means is not inhibited,

In a step 140, it is determined whether the ramping effect is sufficient to hold the vehicle.

If this is the case, go to a step 150 in which the brake device is deactivated.

If this is not the case, go to a step 180 in which the brake device is activated.

It is possible to do without steps 140 to 160, if it is certain that with the chosen slope threshold, the ramping torque is greater than the cut minimum required to drive the vehicle.

A second embodiment of a system for assisting or starting a motor vehicle on a hill, shown in FIG. 4, mainly comprises a brake device 24 acting on wheels

28 of the vehicle, an automated gearbox 27 (for example robotized or automatic) for transmitting a mechanical power from a motor 26 for driving the vehicle to the wheels, a logic unit

23 for processing and controlling the brake device and means 25 for determining (by measuring and / or estimating) the slope of the brake. on which the vehicle rests.

The assistance system is in interaction with vehicle movement control members 22, in particular a vehicle accelerator control member such as a pedal. The system receives from these bodies information such as, for example, accelerator pedal position information and / or pressure information exerted on one of the control members.

The assistance system is in interaction with the engine 26. In fact, the power of the latter is transmitted to the gearbox and information is transmitted to the processing and control unit.

The gearbox includes a ramping means 29. It is possible to inhibit this ramping means. In its inhibited state, the ramping effect is inhibited.

The slope determining means sends slope value information to the processing and control logic unit.

Like i! will be seen in more detail later, depending on the value of slope provided by the determining means, the ramping means 29 is inhibited or not. According to the illustration of FIG. 5, in one embodiment of the method of operation of the system, the ramping means is not inhibited if the acceleration control member is positioned beyond a position threshold and inhibited if the acceleration control member is positioned below the threshold position, this threshold position depending on the slope. This threshold position is determined for example by mapping and dependent on the slope of the ground on which the vehicle is based. Preferably, the threshold position is independent of the slope below a second threshold threshold value. In particular, below the second threshold value of slope, the threshold position may be the relaxed position of the accelerator control member. For example, the second threshold of slope can be between 0 and 15%, and preferably can take any value between 2 and 10%.

Of course, as previously explained, the ramping means remains uninhibited regardless of the slope if this slope tends to drive the vehicle in the desired direction of travel.

When the crawling means is inhibited, it is the brake device which is activated to retain the vehicle in the slope, if it is necessary to retain it. The brake device is controlled by the processing and control unit. The latter sends him an activation or deactivation information and, if necessary, a setpoint for controlling the braking torque.

Unlike the first embodiment of the system, in this second embodiment of the system, it is the logical processing and control unit which controls the inhibition or non-inhibition of the ramping means 29. The assistance system described above comprises hardware and / or software means for governing its operation in accordance with the method that is the subject of the invention. These means comprise in particular a means for interpreting slope value information and for translating this information into an inhibition or non-inhibition control of the ramping means, a means for interpreting a value information of slope, engine information and action information on the control members of the movement of the vehicle and translation of this information into an activation or deactivation control of the brake device and optionally a braking setpoint. The logical processing unit comprises in particular hardware and / or software means for comparing the position of the accelerator control member with the threshold position of this member and means for controlling the activation of the ramping means by consequence of this comparison.

The means mentioned in the preceding paragraph can at least partially be achieved by computer programs.

In a first step 200, the value of the slope of the ground on which the vehicle is located is determined.

In a second step 210, a threshold value of the position of the accelerator control member is determined from the value of the slope determined in step 200. This position threshold value is in fact dependent on the value of the slope of the ground on which the vehicle is. In a third step 220, the position value of the accelerator control member is compared with the position threshold value determined in step 210.

If the position value of the accelerator control member is less than the threshold value, step 230 is carried out identical to step 120 previously described.

If the position value of the accelerator control member is greater than the threshold value (i.e. if the position of the accelerator control member defines a larger load than the load corresponding to Ia threshold value of position), we go to a series of steps 240 to 270 identical to the steps 130 to 180 previously described.

Preferably, in steps 120 and 230 and possibly in steps 160 and 270, the activation of the braking device is limited to a few seconds, for example two seconds.

The system according to the invention and its operating method make it possible to avoid unnecessarily multiplying the vehicle holding forces during a hill start. Indeed, it avoids holding the vehicle stationary with the crawling means of the gearbox when its effect is, in any case, insufficient. Thus, it avoids a heating and a deterioration of the clutch.

The brake device mentioned above may consist of a hydraulic system. The logic processing unit may be integrated with a vehicle stability control computer which acts on the brake device. The brake device is only activated for a limited time (typically a few seconds). If the takeoff has not been completed, the brakes will release and the vehicle may move backward or forward unless the driver activates a brake control. In this case, the ramping effect can be useful to achieve a more progressive recoil or advance of the vehicle.

Claims

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1. A method of operating a system (11; 21) for assisting the starting of a motor vehicle on a hill, comprising a gearbox (17; 27) provided with a ramping means (19; 29), characterized in that the ramping means is inhibited or uninhibited depending on the slope of the ground on which the vehicle is located and in that the ramping means is inhibited when the position value of an acceleration control member is less than a second threshold value _" this second threshold value being dependent on the slope of the ground on which the vehicle is.

2. Operating method according to claim 1, characterized in that the second threshold value is constant, in particular zero, when the slope Ia slope of the ground on which the vehicle is located is less than a third threshold value between 0% and 15%. % and, preferably, between 2% and 10%.

3. Operating method according to one of the preceding claims, characterized in that a brake device (14; 24) is activated when the ramping means is inhibited and the hill start assist system must be active. .

4. Operating method according to one of the preceding claims, characterized in that a brake device (14; 24) is activated or deactivated according to whether the crawling means is sufficient or not to retain the vehicle.

5. System (11; 21) for starting assistance of a motor vehicle on a hill comprising material means (13, 14, 15, 17; 23, 24, 25, 27) and / or implementation software for the operating method according to one of the preceding claims,

6. Assistance system according to claim 5, characterized in that the material means comprise a unit (13; 23) for processing and controlling a brake device (14; 24),

7. Assistance system according to claim 5 or 6, characterized in that the material means comprises a gearbox provided with a creeping means that can be inhibited and means (15;

25) to determine the slope of the ground on which the vehicle is.

8. System (11) for assistance according to claim 7, characterized in that means (15) for determining the slope of so! on which the vehicle is provided provides a slope value to the processing and control unit (13) and to the gearbox (17),

9. System (21) for assistance according to claim 7, characterized in that the means (25) for determining the slope of the soil on which the vehicle is located provides a slope value to the unit (23) of treatment and control and that the processing and control unit controls the inhibition of the means (29) of ramping of the gearbox (27),

10. A motor vehicle comprising a hill start assist system (11; 21) according to one of claims 5 to 9.