The present invention concerns a control device of an automotive vehicle comprising at least one speed variation system. The invention also concerns a method for controlling the speed of such a vehicle.

BACKGROUND

Automotive vehicles are often equipped with one or several speed variation systems. For instance, these systems can be formed by gearboxes, retarder brakes and cruise control systems. These equipments are used by the driver to control directly or indirectly the speed of his vehicle. Such speed variation systems come in addition to the primary control systems which include the engine, controlled through an accelerator pedal, and the service brakes, controlled through an accelerator pedal, and could therefore be considered as secondary speed variation systems.

Speed variation systems can be controlled by the driver by means of a stalk mounted around the steering wheel of the vehicle. In many cases, a stalk is dedicated to one speed variation system. By moving the corresponding stalk, the driver can control, for instance, the speed ratio of the gearbox, the intensity of the retarder brake or the speed limit of the cruise control system. In some cases, the value of the operating parameter is directly connected to the position of the stalk. In other cases, the value of the operating parameter is increased at a certain rate when the stalk is maintained in a given position.

Known techniques provide one rate of variation of the operating parameters of each speed variation system. These techniques do not permit a smooth, quick and practical setting of the parameters of the speed variation system.

SUMMARY

This invention aims at proposing a new control device of an automotive vehicle, which allows the driver to use speed control means of the vehicle quickly, according to his wishes, while providing the driver flexibility in the setting of the parameters of the speed control means.

To this end, the invention concerns a control device of an automotive vehicle comprising at least one speed variation system, said control device comprising a movable stalk, to be manually operated by a driver, wherein said stalk is adapted to be moved, from a neutral position, into a first predefined position or range of positions, where an operating parameter of the speed variation system is increased with a first increase rate, and into at least a second predefined position or range of positions where said operating parameter of said speed variation system is increased with a second increase rate. Thanks to the invention, the driver can smoothly or quickly increase the operating parameter of the speed variation system he uses. This allows him to quickly reach the level of speed control he desires and prevents him from waiting several seconds for the value of the parameter to increase to the desired level.

According to further aspects of the invention which are advantageous but not compulsory, such a control device might incorporate one or several of the following features:

- the stalk is adapted to be moved in an extreme position where an operating parameter of the speed variation system is directly set to its maximal value or its minimal value;

- the stalk is adapted to be moved, from the stable neutral position, into a predefined position or range of positions, opposed to the first position or range of positions, where an operating parameter of the speed variation system is decreased with a first decrease rate, and into at least a predefined position or range of positions opposed to the second position range of positions, where said operating parameter of said speed variation system is decreased with a second decrease rate;

- the stalk is adapted to be moved in an extreme opposed position, where an operating parameter of the speed variation system is respectively directly set to its maximal value or its minimal value;

- the control device comprises means to measure the time period during which the stalk is in one of said predefined positions or ranges of positions, and/or comprises means to determine the angle between the stalk and the neutral position;

- the means to determine the angle comprise a position sensor;

- the control device comprises means to compute the values of the increase and/or decrease rates on the basis of said time period and/or said angle;

- the movable stalk is adapted to be operated to selectively control at least two speed variation systems formed of a retarder brake and a cruise control system, and the control device further comprises means to select which of said speed variation systems to control with the stalk;

- said two speed variation systems are controlled using the same patterns of movements of the stalk between the stable central position and the predefined ranges of positions;

- the means to select the speed variation system to control with the stalk comprise a switch on the stalk; - the stalk is adapted to be moved at least from the first opposed ranges of positions to the second opposed ranges of positions by over passing a hard point;

- the neutral position of the stalk is a stable position towards which the stalk is biased;

- the stalk is also used to control a gearbox in such a way that, when said stalk is moved into the first predefined position or range of positions, the gearbox ratio is increased by a one-time increment, and when said stalk is moved into the second predefined position or range of positions, the gearbox ratio is increased by a second onetime increment;

- the movable stalk is adapted to be operated to selectively control one of at least three speed variation systems formed of the gearbox, of the retarder brake and the cruise control system;

The invention also provides for a method for controlling the speed of an automotive vehicle comprising at least one speed variation system, wherein

an operating parameter of the speed variation system is respectively increased or decreased with a first increase rate or a first decrease rate in a first position or range of positions of a movable stalk,

said operating parameter of the speed variation system is respectively increased or decreased with a second increase rate or a second decrease rate in a second predefined position or range of positions of the movable stalk, and

said operating parameter of the speed variation system remains unchanged in a neutral position of the movable stalk.

According to further aspects of the invention which are advantageous but not compulsory, such a method might incorporate one or several of the following features:

- the increase and decrease variation rates are computed on the basis of a measured time period during which the movable stalk is in one of the said predefined positions or ranges of positions, and/or on the basis of an angle between the movable stalk and the neutral position of the stalk;

- an operating parameter of the speed variation system is set to a maximal or minimal value in an extreme position of the movable stalk;

- the method comprises the following steps:

choice of a speed variation system to control, amongst at least two speed variation systems formed of a retarder brake and a cruise control system;

actuation of a selection mean to select, amongst said speed variation systems, one speed variation system to be controlled by the movable stalk; action on the movable stalk to control an operating parameter of the selected speed variation system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexed figure 1 and as an illustrative example, without restricting the object of the invention. Figure 1 is a schematic representation of a control device embodying the invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Figure 1 shows a control device 2 installed in an automotive vehicle V.

Control device 2 is installed in vehicle V, whose driveline 16 is equipped with several speed variation systems. In this example, vehicle V is equipped with at least three speed variation systems formed by an automated gearbox 10, a retarder brake 12 and a cruise control system 1 .

Automated gearbox 10 can be any type of gearbox, whose speed ratios are not directly selected by an operator through a physical link. It can be a robotized manual gearbox, an automatic gearbox, a continuously variable transmission (CVT), etc.... The speed ratio determined by the gearbox can include a neutral ratio, where the input and the output of the gearbox are disconnected and a number of ratios, discrete or not, ranging from a smallest ratio to a highest ratio. Conventionally, the highest ratio is the one for which the vehicle speed is the highest for a given engine speed. In heavy duty vehicles such as trucks, the gearbox may include a range gear and/or a splitter gear. The speed ratio can be considered as an operating parameter of the gearbox, and the driver may control the speed ratio through a control device.

The retarder brake system can be for example an engine compression brake, an exhaust brake, a hydrodynamic brake, an electro-dynamic brake, etc... The retarder brake exerts on the driveline 16 a retardation torque which tends to reduce the vehicle speed. Seen in another way, the retarder can be considered as exerting on the driveline a driving torque having always a negative value, so that the retarder can be seen as providing a minimal driving torque when its retarding torque is maximum, and providing a maximal driving torque (equal to zero) when the retardation torque is minimal, i.e. when the retarder is off. The retarder's driving torque can be considered as an operating parameter, just as its retardation torque, except that one of them increases when the other decreases.

The cruise control system can have one or several modes, such as a speed regulation mode where the driveline is controlled to maintain the vehicle at a target vehicle speed, a speed limitation mode, where the driveline is controlled only to make sure the vehicle does not exceed a target speed. In both cases, the vehicle target speed can be considered as the operating parameter of the cruise control system. The cruise control system can have a so-called adaptative cruise control mode where the vehicle is equipped with means for measuring the distance to a vehicle in front and for keeping a clearing distance between the two vehicles. In most cases, the driver is given the possibility to adjust the clearing distance which is then another operating parameter of the cruise control system which the driver may set.

Control device 2 comprises a stalk 4 which can be mounted on a block 6 on which a non-represented steering wheel may be rotatably mounted. Several other stalks, which are not represented on the drawings and may control other functions like radio or lights, can be mounted near stalk 4. In this example, stalk 4 is adapted to be pivoted around an axis A4 which is perpendicular to the plane of the drawing. Nevertheless, the stalk according to the invention should not be limited to such embodiment, and could be any type of hand actuated member which the driver may conveniently use, such as a rotating button, a slider, etc...

In this embodiment, the control device 2 is equipped with a selection mean 8 which, as shown on Figure 1 can be mounted on the stalk, but could also be separate from the stalk.

Stalk 4 is moveable from a neutral position PO, which is preferably a stable position. The stalk is preferably biased towards such position. In the shown embodiment, the neutral position is substantially horizontal. From this position, stalk 4 can be moved, for example upwards, into a first intermediate position PU1 and into a second position PU2. The movement of stalk 4 is respectively possible into two ranges of positions RU1 and RU2, between positions PO and PU1 and between positions PU1 and PU2. The second position or range of positions is located further away from the neutral position than the first position or set of positions. The number of predefined positions and corresponding ranges is not limited to two, and could be more. The second position PU2 can be an extreme upwards position of stalk 4, but it could be provided a distinct extreme position PUMax.

In this embodiment, the stalk 4 can also be moved in an opposed direction, for example downwards, in a first opposed position PD1 and into a second opposed position PD2. In the same way, stalk 4 can be moved in ranges RD1 and RD2 between positions PO and PD1 and between positions PD1 and PD2. The second opposed position PD2 can be an extreme opposed position of stalk 4, but it could be provided a distinct extreme position PDMin. The predefined positions and ranges of positions are arranged so that the rate of decrease or increase for the operating parameter will be higher when the stalk moves away from the neutral position.

The angle a between the stable neutral position PO and an actual position of stalk 4 is detected by a sensor 20, which can be located in stalk 4 itself, adapted to send an electronic signal S20 to a microprocessor 22 located in block 6. The sensor can provide the exact position of the stalk, or it could detect only the passage of the stalk through one of the predefined positions, or it could simply enable to detect the presence of the stalk in one of the predefined ranges. Electronic signal S20 provides data concerning the angles measured by sensor 20, i.e. concerning the position of the stalk with respect to the predefined positions or ranges of positions. The control device is also equipped with a clock 24, adapted to measure the period of time t during which stalk 4 is in a given position or range of positions. This information is sent to the microprocessor 22 in an electronic signal S24.

Movement of stalk 4 is described here as possible upwards and downwards from an approximately horizontal stable neutral position PO. In an alternative and non-shown embodiment, movements of stalk 4 may also be possible around a vertical axis. In that case, movements of stalk 4 can be defined as being frontwards or backwards, with respect to a longitudinal direction of the vehicle.

Microprocessor 22 is adapted to communicate with at least one vehicle speed variation system, i.e., in this embodiment, with each of automated gearbox 10, retarder brake 12 and cruise control system 14 thanks to respective electronic signals S10, S12 and S14. With these electronic signals, microprocessor 22 controls the operating parameters of the speed variation systems 10, 12 and 14 connected to driveline 16. For instance, microprocessor 22 can control the speed ratio G10 of gearbox 10, the braking intensity B12 of retarder 12 and the speed limitation value L14 of cruise control system 14.

With stalk 4, the driver of the vehicle can control at least one speed variation system by setting its operating parameter at a desired value. In fact, it will be seen that, in the refined embodiment shown, the driver can selectively control one of the three speed variation systems 10, 12 and 14.

By moving stalk 4, the driver chooses the variation rate for an operating parameter of a speed variation system he or she wants to use. In this embodiment, the driver can first select, thanks to selection switch 8, which of automated gearbox 10, retarder brake 2 and cruise control system 4 he or she wants to use to control the speed of his vehicle.

In the shown example, the driver can choose to increase an operating parameter of speed variation system at a relatively low increase rate ri1 in range RU1. Indeed, as long as stalk 4 is being moved or maintained by the driver in range RU1 , or at position PU1 , the set value of the operating parameter is increased at increase rate ri1 which be determines by microprocessor 22 on the basis of the information transmitted by sensors 20 and 24. The angle a of stalk 4 between its actual position in range RU1 and stable neutral position P0 determines the increase rate ri1. The time t during which stalk 4 is in this actual position or range of positions determines the value reached by the operating parameter under this increase rate.

In case the driver wants to increase an operating parameter of the speed variation system at a higher rate, he or she can move stalk 4 in a position which exceeds position range RU1. As position PU1 is a pre-defined position, overrunning of position PU1 by stalk 4 is detected and induces a higher increase rate ri2, which allows the driver to reach the desired speed level more quickly. The change between position range RU1 and position range RU2 may be detected by angle sensor 20 or by a contact sensor, which is not represented on the figure. This change of position range can be marked by a hard point during movement of stalk 4, i.e., a point where the resistance of the stalk to movement is increased, in order for the driver to notice the change of increase rate level.

Preferably, the instantaneous value of the operating parameter is displayed to the driver, so that he can, at all times during the adjustment of the operating parameter, see both its value and the rate at which it is varying.

In the case of the cruise control we can take the example of an initial state of the operating parameter value being the instantaneous vehicle speed, for example 60 km/h. If the driver wants to set the cruise control target speed at 90km/h, he may choose to bring the stalk in the second position PU2 corresponding to an increase rate of 5 km/h per second. He then sees the operating parameter increase quickly. When the parameter reaches for example 85 km/h, he may choose to bring back the stalk in the first position or range of positions, corresponding to an increase rate of 1 km/h, until the parameter reaches the desired value of 90km/h. He then releases the stalk which comes back to its stable position where the operating parameter is not anymore changed.

It is of course understood that the increase rate for a parameter can be translated into a decrease rate of a symmetrical parameter, as shown above with reference to the retarder where an increase of the retarder braking torque can be considered as a decrease of retarder driving torque and vice-versa.

In this embodiment of the invention, only two different increase rates are provided, each corresponding to two discrete positions or two ranges of positions. Of course, more increase rates could provided, corresponding to associated predefined positions or range of positions. In an extreme case, where many such increase rates are provided, it may appear to the driver that, to each discernable position of the stalk corresponds a different increase rate. In such a case, the control device will appear to the driver as allowing him to choose a continuously increasing increase rate, depending only on the position of the stalk away from its neutral position.

There, the invention in its simplest form can provide a control device operating as summarized in the following table:

According to an optional feature of the invention, the control system may allow both to increase and decrease the operating parameter in a similar way. There, the control device may be configured so that the stalk 4 is adapted to be moved in the opposite direction from the stable neutral position PO, into a predefined position PD1 or range of positions RD1 , opposed to the first position PU1 or range of positions RU1 , where an operating parameter of the speed variation system is decreased with a first decrease rate, and into at least a predefined position PD2 or range of positions RD2 opposed to the second position PU2 range of positions RU2, where said operating parameter of said speed variation system is decreased with a second decrease rate.

Positions PU1 , PU2, PD1 and PD2 may be unstable positions. This means stalk 4 gets back to the stable neutral position PO once the driver stops its movement upwards or backwards. The value of the operating parameter controlled by the driver remains unchanged in neutral position PO until a further movement of the driver on the stalk.

Low and high decrease rate values rd1 and rd2 reachable in ranges RD1 and RD2 may be identical to or different from increase rate values ri1 and ri2.

According to an optional feature of the invention, the movable stalk 4 is adapted to be operated to selectively control at least two speed variation systems formed of a retarder brake 12 and a cruise control system 14, and the control device 2 then preferably further comprises means 8 to select which of said speed variation systems to control with the stalk 4.

In such a case, control device 2 preferably uses the same movement pattern to control the increase or decrease rates of the operating parameters of the various speed variation systems 10, 12 and 14. The possibility for the driver to control, with the same pattern of movements, the operating parameters of several speed variation systems permits to install a single control stalk 4 near the steering wheel of the vehicle and also to avoid the need for the driver to use a plurality of stalks or to use a same stalk in different ways depending on the speed variation system..

According to another optional feature of the invention, the driver can respectively set the operating parameter of the speed variation system he or she is using directly to its maximal or minimal value by moving stalk 4 into a corresponding extreme position PUMax and/or PDMin. These positions PDMin and/or PUMax may be a switch off position, in which the speed variation system controlled by the driver is switched off. In the example of Figure 1 , position PUMax could correspond to position PU2 and/or position PDMin could correspond to position PD2. In the case of the retarder, the maximum value of the retarder driving torque can be a null value corresponding to a switch off of the retarder, while the minimal value of the retarder driver torque corresponds to the full retarder torque. In the context of the cruise control, the maximal value may be a predefined maximal speed target value, while the minimum value could be either a minimum target speed value or could be a switch off of the cruise control.

In the shown embodiment, the stalk is also used to control the gearbox in such a way that when said stalk 4 is moved into the first predefined position PU1 or range of positions RU1 , the gearbox ratio is increased by one increment, and when said stalk 4 is moved into the second predefined position PU2 or range of positions RU2, the gearbox ratio is increased by at least two increments. In this way of operating, the different positions of stalk are not associated to a corresponding increase rate of the operating, but to a corresponding one-time increment. For example the one-time increment could be +1 speed ratio in the first position or range of positions, and +2 in the second position or range of positions. In the context of the gearbox, moving the stalk into one extreme position PDMin could be translated by the control device into a shift of the gearbox directly in neutral, and into the other extreme position PUMax could be translated by the control device into a shift of the gearbox directly in a maximum acceptable ratio compatible with the instantaneous speed of the vehicle.

Therefore, in a refined embodiment combining several of the above features, the operation of the control device could be summarized as in the following table: Position or Range of Retarder : Cruise Control: Gearbox Positions of the Retarder driving Speed target value

stalk torque (negative

value)

PUMax 0 (Off) Max Cruise Speed Max acceptable target value ratio

PU2 or RU2 ft ft (rapid increase) ft ft (rapid increase) +2

PU1 or RU1 ft (slow increase) ft (slow increase) +1

PO ^■ => (no change) ^■ = (no change)

PD1 or RD1 (slow decrease) O-(slow decrease) -1

PD2 or RD2 •0- Ό- (rapid increase) ΰ· ·0· (rapid increase) -2

PDMin Minimal driving Off Neutral

torque (full retarder

torque)

A further optional feature of the invention is to provide a control system where the movable stalk 4 is adapted to be operated to selectively control at least two operating parameters of a given speed variation system, and wherein the control device 2 further comprises means 8 to select which of said operating parameters to control with the stalk 4. For exemple, in an adaptative cruise control system, the same stalk can be used to set both a vehicle speed target value and a clearing distance target value.

Selection mean 8 is represented in Figure 1 as a movable ring on stalk 4. This selection mean may also be any type of switch or button.

In an other embodiment which is not represented on the figure, the moving part of control device may be integrated on a stalk dedicated to another function, for instance, wipers or lights, and the speed control functionality may be activated thanks to a dedicated switching mean.