EP1819933A1

EP1819933A1 - Method and system for controlling a motor vehicle comprising an actuator-operated clutch

Info

Publication number: EP1819933A1
Application number: EP05819329A
Authority: EP
Inventors: Pascal Geffroy; Christian Hoffmann
Original assignee: Valeo Embrayages SAS
Current assignee: Valeo Embrayages SAS
Priority date: 2004-11-25
Filing date: 2005-11-24
Publication date: 2007-08-22
Also published as: FR2878303B1; CN101065595A; JP2008522108A; FR2878303A1; WO2006056723A1

Abstract

The invention relates to a method and system for controlling a motor vehicle comprising an actuator-operated clutch (E), which is equipped with a device (26) for automatically stopping and restarting the engine (10) in pre-determined conditions, in which the biting point of the actuator-operated clutch (E) is determined during the period of time preceding the stopping of the engine (10) of the vehicle which is controlled by said device (26).

Description

METHOD AND SYSTEM FOR CONTROLLING A MOTOR VEHICLE WITH PILOT CLUTCH

The invention relates to a method and a control system for a motor vehicle with a controlled clutch equipped with an automatic engine stop and restart device.

This device for stopping and restarting the engine automatically (or "Stop and Go" device according to a terminology commonly used) is primarily intended to reduce fuel consumption, especially in the city at a stop at traffic lights and in traffic jams , and to consequently reduce the pollution of the atmosphere by the exhaust gases of the engine of the vehicle.

This device is advantageously used in combination with an actuator clutch control, which is associated with a robotized gearbox, an automatic gearbox or a manual gearbox with a clutch pedal acting by electrical connection. The clutch control by an actuator requires a determination of the licking point of the clutch, that is to say the point on the most advanced clutch curve in the direction of the clutch for which one does not still transmits no torque, and a follow-up of the evolution of this point, to avoid shocks and jerks in the transmission of the vehicle during the controlled actuations of the clutch.

Different modes of determining this point have already been proposed in the art, but do not always give satisfaction and are sometimes not easy to implement.

The invention particularly aims a method for determining the licking point of a clutch driven in a vehicle equipped with a device for stopping and starting automatic engine of the aforementioned type, this determination being performed in masked time and without degrading the behavior of the vehicle and the comfort of driving.

It proposes for this purpose a method of controlling a vehicle automobile comprising a clutch controlled by an actuator and a device for stopping and restarting the engine automatically under predetermined conditions, in particular comprising a neutral position of the gearbox, which consists in determining the licking point of the clutch during the the interval of time preceding the stopping of the engine of the vehicle when this stop is controlled by the aforementioned device.

The method according to the invention therefore takes advantage, to determine the licking point of the clutch, the time interval between the effective stop engine stop order given by the aforementioned device when the conditions wanted are met. This time interval is short, typically about one second, but sufficient to make this determination which, when performed under these conditions, takes place when the vehicle is stopped and does not harm the behavior of the vehicle and the comfort driving. According to another characteristic of the invention, this method also consists in determining the licking point of the clutch at each stop of the engine controlled by the aforementioned device.

This makes it possible to precisely follow the evolution of the licking point according to the environmental and operating conditions of the engine and the vehicle, and thus to be able to precisely control the actuation of the controlled clutch in order not to harm the behavior of the vehicle. and driving comfort.

The invention also provides for inhibiting or stopping the determination of the licking point if the aforesaid time interval is too short for this determination.

This avoids delaying the stopping of the engine of the vehicle, when this stop was controlled by the aforementioned automatic stopping and restarting device and the determination of the licking point at the next stop. In a preferred manner according to the invention, this method also consists in detecting the position of the licking point of the clutch by detecting the the rotation of a primary shaft of the vehicle gearbox.

In a practical way, the method according to the invention consists in detecting the point of licking of the clutch by progressive closing of the clutch from its open position, the speed of rotation of the motor being greater than or equal to a predetermined minimum value, and by ré¬ opening of the clutch.

This determination of the licking point is totally transparent for the driver or passengers of the vehicle: it is sufficient indeed, the clutch being open, the gearbox being in the neutral or dead position and the primary shaft of the gearbox being stopped (the vehicle being in principle stopped), partially closing the clutch until detection of the rotation of the primary shaft of the vehicle gearbox after which the clutch is opened again to return to the initial condition. Since the clutch is controlled by an actuator comprising a movable element whose displacement corresponds to the opening and closing of the clutch, the method according to the invention consists in detecting and recording the position of this movable element of the clutch. actuator when it corresponds to the licking point of the clutch. The time interval between the stop command given by the aforementioned device and the actual stopping of the motor is also used to search for the previously recorded value of the licking point of the clutch, or the corresponding position of the clutch. moving element of the clutch actuator, before making a new determination of the licking point. This makes it possible to directly observe the evolution of the licking point.

The invention also proposes a motor vehicle control system intended for the execution of the method described above, this system being characterized in that it comprises means for detecting and recording the position of an element. movable actuator acting on the clutch of the vehicle, means for detecting the rotation or the speed of rotation of a primary shaft of the box. vehicle speeds and information processing means connected to the aforementioned means of detection and to the aforementioned device for automatically stopping and restarting the engine and programmed to control the actuator in the direction of closing the clutch and for registering the position of the movable element of the actuator corresponding to a rotation of the gearbox primary shaft from a zero rotation, during the period of time preceding the stopping of the engine being driven by the aforementioned device.

Advantageously, other means may be provided in the system according to the invention to improve its performance as well as the approval of the use of the vehicle and the comfort of driving.

For example, it can be provided to associate the controlled clutch and the device for stopping and restarting the engine automatically, means of "creeping" (moving the vehicle at a very slow speed) to the release of the brake pedal by the driver, which forces the driver to press this pedal to prevent the vehicle from moving and thus allows the engine to stop, if the conditions are met, by the aforementioned automatic stop and restart device.

It is also possible, when the vehicle is equipped with an air conditioning device, auxiliary means of regulating the temperature of the passenger compartment of the vehicle when the engine is stopped by the aforementioned automatic stop and restart device.

It is possible, for example, with these auxiliary means, to constitute a reserve of cold (or hot) when the engine rotates and use this reserve when the engine is stopped by the aforementioned device for stopping and automatic restart.

It is also possible to provide means for detecting the position of the vehicle on a hill-side terrain, these means comprising, for example, an inclinometer, for preventing the aforementioned device from stopping the engine if the predicted conditions are met. This avoids the recoil of the vehicle when restarting the engine, which would most often result in a shock or a jerk in the transmission. It is also possible to associate the brake locking means to the aforementioned means for releasing the brakes only after detecting the passage of a torque in the controlled clutch, which prevents the vehicle from backing up hill at engine restart. In certain cases, it is also conceivable to detect the position of the licking point of the driven clutch, not at the standstill of the vehicle in the time interval immediately preceding the stopping of the engine controlled by the above-mentioned device. automatic stop and restart, but during the movement of the vehicle at the passage of a lower speed, the licking point being determined when closing the clutch by detecting the point of inflection of the speed of rotation of the motor output shaft.

The aforementioned clutch may or may not include automatic means of catching up wear. The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the accompanying drawings, in which:

- Figure 1 shows schematically a control system according to the invention;

FIG. 2 is a general flowchart of the various operations of the control method according to the invention.

The control system according to the invention is intended to equip a motor vehicle comprising an internal combustion engine 10 of a conventional type, the output shaft 12 is connected by a clutch E to an input shaft or primary shaft 14 of a gearbox 16, such as for example a robotized mechanical gearbox, whose output shaft 18 drives the drive wheels 20 of the vehicle via a differential 22. The clutch E is driven by an actuator 24, for example of the electrical or fluidic type, comprising a movable actuating element of the clutch.

The vehicle is also equipped with a device 26 for stopping and restarting the engine automatically or "Stop and Go" device, essentially comprising a reversible alternator-starter controlled by a computer 28 conventionally comprising one or more microprocessors, memories , and input-output interfaces, this computer can also control, inter alia, the actuator 24 of the clutch E and the gearbox 16.

The automatic stopping and restarting device 26 is for controlling the stopping of the vehicle engine 10 to reduce fuel consumption when certain conditions are met, including:

- The gearbox 16 is in the neutral position (or in neutral);

the clutch E is open,

the input shaft 14 of the gearbox does not rotate; - The rotational speed of the output shaft 12 of the motor 10 is greater than or equal to a predetermined minimum value corresponding for example approximately to the idle speed;

the vehicle is at a standstill (its traveling speed is zero) or its speed is very low, for example less than 2 km / h. These conditions may also include driver support on the brake pedal.

When these conditions are met, a stop command of the motor 10 is given by the computer 28 and causes the actual stopping of the motor 10 with a response time which is typically less than one second. This time interval is sufficient for the search of the licking point previously determined and for a new determination of the licking point, which essentially consists of:

to order a progressive closing of the clutch E,

to detect the beginning of the rotation of the primary shaft 14 of the gearbox,

to record the corresponding position of the movable element of the actuator 24,

- and reopen the clutch.

It suffices for this to equip the movable member of the actuator 24 with a position sensor 30, and the primary shaft 14 of the gearbox of a sensor 32 of angular position or rotational speed.

The detection of the licking point of the clutch E is done without modifying the conditions for stopping the engine 10 by the device for stopping and restarting the engine automatically. If the time interval between the stop command and the actual stopping of the engine is too short to allow a determination of the clutch licking point as indicated, and if the determination is started, this is discontinued. determination and restoring the actuator to the initial position, the stop being given priority over the determination in progress.

Alternatively, in some cases it may be possible to delay the stopping of the motor, for example by about one second, to allow completion of the determination of the licking point.

If, in the time interval between the stop command and the stopping of the engine, the speed of rotation of the primary shaft 14 of the gearbox does not return quickly enough to a zero value, one can by partially closing the clutch E, braking the primary shaft 14 of the gearbox, and then detecting the licking point of the clutch E when this speed has dropped sufficiently.

The main operations of the control method according to the invention have been shown schematically in FIG. 2. When a stop command of the motor 10 is given by the above-mentioned automatic stop and restart device as indicated at 34, it is checked whether a certain conditions are met, including:

the verification 36 of the state of the gearbox 16 in the neutral position and of the opening of the clutch E,

the verification 38 of the zero or substantially zero rotation of the primary shaft 14 of the gearbox,

the verification 40 of a zero or very low speed of the vehicle (possibly of pressing on the brake pedal),

checking 42 the rotation of the output shaft 12 of the motor at a speed greater than or equal to a minimum value,

the search 44 of the licking point previously determined. These conditions being satisfied, the determination 46 of the licking point of the clutch E comprises the control of the actuator 24, the detection of the rotation of the primary shaft 14 of the gearbox and the recording of the position of the movable element of the actuator 24, then the re-opening of the clutch.

The next operation 48 is the actual stopping of the engine 10 of the vehicle, which is followed by the restarting of the engine 50 by the device 26, when the driver indicates his intention to restart the vehicle. It is also possible to determine the licking point in other conditions, for example when the engine is started cold, when the driver stops the engine, during all stops, or some of them, by the device. "Stop and Go".

The stops at which this determination is made are determined according to certain parameters, such as the time elapsed or the distance traveled since a previous determination, the number of actuations of the clutch, the engine temperature (a rise in temperature causing a variation of the licking point due to thermal expansion). The invention is applicable to a clutch comprising or not an internal friction wear compensating system, the invention allowing in the first case to monitor the proper operation of the wear-compensating system, for example by giving information by a diagnostic system accessible to a repairer.

Claims

A method of controlling a motor vehicle comprising a clutch (E) controlled by an actuator (24) and a device (26) for automatically stopping and restarting the engine under predetermined conditions including in particular a neutral position of the gearbox, characterized in that it consists in determining the point of licking of the clutch (E) during the time interval preceding the stopping of the engine (10) of the vehicle when this stop is controlled by the device (26) cited above.

2. Method according to claim 1, characterized in that it consists in determining the point of licking of the clutch (E) at each stop of the motor (10) controlled by the device (26) above.

3. Method according to claim 1 or 2, characterized in that it consists in determining the licking point for some of the above-mentioned stops only, depending on the evolution of parameters such as the distance traveled or the time elapsed since a determination. previous, the number of actuations of the clutch or the engine temperature.

4. Method according to one of the preceding claims, characterized in that it consists in detecting the position of the licking point of the clutch (E) by detecting the rotation of a primary shaft (14) of the box. vehicle speeds.

5. Method according to one of the preceding claims, characterized in that it consists in detecting and recording the position of a movable element of the actuator (24) of the clutch (E), when this position corresponds to the point licking the clutch.

6. Method according to one of the preceding claims, characterized in that it consists in detecting the licking point of the clutch (E) by progressive closure of this clutch from its open position, the speed of rotation of the motor (10). ) being greater than or equal to a predetermined minimum value.

7. Method according to claim 6, characterized in that it consists in slowing down the rotation of the primary shaft (14) of the gearbox by partial closing of the clutch (E), to open it later and to detect the licking point of the clutch by progressive closing of this clutch.

8. Method according to one of the preceding claims, characterized in that it also consists in searching for the previously recorded value of the licking point before making a new determination of this point, in the aforementioned time interval.

9. Method according to one of the preceding claims, characterized in that it consists, after determining the licking point, to reopen the clutch (E) during the aforementioned time period preceding the engine stop.

10. Method according to one of the preceding claims, characterized in that it consists in inhibiting the determination of the point of licking of the clutch if the aforementioned time interval is too short for this determination or to interrupt this determination if stop occurs before the end of this determination.

11. Control system of a motor vehicle for carrying out the method described in one of the preceding claims, characterized in that it comprises means (30, 28) for detecting and recording the position of a movable element of an actuator (24) acting on the clutch (E) of the vehicle, means (32) for detecting the rotation or the speed of rotation of a primary shaft (14) of the gearbox of the vehicle, and information processing means (28) connected to the aforementioned means of detection and the aforementioned device (26) for stopping and starting the engine automatically and programmed to control the actuator (24) in the direction closing the clutch and to record the position of the movable member of the actuator corresponding to a rotation of the gearbox primary shaft (14) from a substantially zero rotation of this tree, during the time interval which precedes the stopping of the motor (10) controlled by the above-mentioned device (26).

12. System according to claim 11, characterized in that the clutch (E) comprises means of catching wear.