Background Art In cars with manual transmission, the use of a clutch to engage the propeller shaft on the drive shaft. In detail, the clutch normally comprises at least a pair of disks, whereof the first is integral with the drive shaft and the second one is integral with the propeller shaft. One or more springs put the two disks in contact against each other so that they become integral by friction.

Clutch disengagement is commanded by a pedal, movable between a rest position and at least a working position in which it commands an actuator that moves the disks away from each other, allowing a relative rotation between drive shaft and propeller shaft.

The force to be applied to the pedal to disengage the clutch can be considerable, especially when the clutch is associated to high torque engines. In this situation, the forces with which the springs move the disks against each other must be high, to allow all of the torque to be transmitted to the propeller shaft, preventing the sliding of a disk against the other.

To overcome this drawback, servo-systems can be used which enhance the action exerted on the pedal. This situation too, however, is not free of drawbacks. In order to ensure that the user perceives the use of the clutch pedal, the latter is subject to contrasting forces that tend to bring it back to the rest position. Such contrasting forces cause, in the long run, the tiring of the driver. This problem is particularly acute in city traffic, in which the vehicle has to be subjected to frequent stops with

the engine running, which are often too short to allow placing the engine in idle.

Description of Invention The aim of the present invention is to overcome the aforementioned drawbacks.

In particular, the technical task of the invention is to provide a device that allows to maintain, under certain condition, the operation of the friction with little or no effort, thereby rendering the driving of the vehicle less fatiguing.

A further aim of the invention is to devise a solution to the aforementioned technical problem that is constructively simple, of small size and low cost.

In accordance with an aspect of the present invention, a device for operating a vehicle clutch is presented as specified in the independent claim. The dependent claims refer to preferred and advantageous embodiments of the invention.

Description of the Drawings The description is now provided, purely by way of non limiting example, of some preferred but not exclusive embodiments of a device in accordance with the present invention, illustrated in the accompanying drawings, in which: Figure 1 shows a schematic view of a first embodiment of the device according to the invention; Figure 2 shows a schematic view of a second embodiment of the device according to the invention; and Figure 3 shows a detail of a third embodiment of the device according to the invention.

Detailed Description of the Preferred Embodiments With reference to the aforementioned figures, the device for operating a vehicle clutch is globally indicated with the number 1.

It comprises a first actuator 2 operatively active on the clutch 3. The actuator 2 is able to switch between an operative condition in which it disengages the clutch

3 and a non operative condition in which the clutch 3 is engaged.

A command element 4, typically constituted by a pedal 5, is active on the first actuator 2 through transmission means 6. Said command element 4 is movable between a resting position whereto corresponds the non operative position of the first actuator 2 and at least a working position corresponding to the operative condition of the first actuator 2.

The device 1 further comprises a locking element 7 active on the first actuator 2. The locking element 7 is driven by a control unit 8 between an operative condition and a non operative condition. In the non operative condition the locking element 7 is not active on the first actuator 2, on the contrary in its operative condition the locking element 7 is active on the first actuator 2 to maintain the first actuator 2 in the operative condition, i. e. with the clutch 3 disengaged, when the command element 4 is in the working position.

The device 1 further comprises a first sensor 9. A second sensor 10 can also be added. The first sensor 9 is able to measure the speed of the vehicle. The second sensor 10 is active on the brake 11 of the vehicle to detect its activation, in practice the latter sensor 10 can be the switch of the brake lights which is already present in vehicles. The control unit 8 is connected with the sensor 9, and it can optionally be connected to the sensor 10, if the latter exists and is used. The control unit 8 is active on the locking element 7 to place it in the operative condition if vehicle speed is zero.

If the brake sensor 10 is also present, the activated brake 11 consent must be sent to the control unit 8.

A third sensor 12 can be provided in addition to the first two sensors 9,10, or instead of the first sensor 9. The third sensor 12 is active on a gear selector 25 of the vehicle, i. e. the manual transmission lever associated to the engine of the vehicle, to detect the condition of engagement of the first gear.

The control unit 8 is also connected with the third sensor 12 and is active on the locking element 7 to put it in the operative condition when the gear selector 25 is in the condition of engaged first gear.

In a first embodiment, shown in Figure 1, the transmission means 6 are hydraulic. In detail, the pedal 5 activates a pump 14 which pressurises the fluid of a hydraulic circuit 13 which in turn operates the first actuator 2.

In this case, the locking element 7 comprises a valve 15, preferably of the electromechanical type, able to be driven by the control unit 8 between an open condition of the hydraulic circuit 13, corresponding to the non operative condition of the locking element 7, and a closed condition of the hydraulic circuit 13, corresponding to the operative condition of the locking element.

In particular, as shown in Figure 1, the valve 15 is a two-position valve: it is normally maintained in the open condition of the hydraulic circuit 13 by a spring 7a, and it is operated by an electromagnet 7b which moves the valve 15 in the position in which the hydraulic circuit 13 is shut.

In case of malfunction of the locking device 7, of the control unit 8, of the sensors or of other components, the normal functionality of the device 1 for operating the clutch is always assured.

Advantageously, the device according to the invention can also serve an anti- theft function. In this case the device comprises, in addition to the elements described above, a security key 26, which advantageously is integrated with the vehicle starting key. The security key 26 can be associated to a unit 27 for recognising the key 26, said recognition unit 27, shown only schematically in the accompanying figures, being mounted in correspondence with the vehicle starting block. The association of the key 26 with the recognition unit 27 takes place, in a known manner not described in detail, inserting the key in an appropriate seat obtained in the starting block.

Preferably, the security key 26 and the recognition unit 27 constitute a "transponder" (transmitter-receiver) type of system. In particular, the security key 26 comprises a transmitter 28 of an electromagnetic signal whilst the recognition unit 27 includes a receiver 29 of said signal and means for verifying whether the signal received corresponds to the predefined one emitted by the security key 26.

When the security key 26 is associated to the recognition unit 27, in such a way

that the latter receives the predefined signal emitted by the key 26, the recognition unit 27 assumes a first operative condition. The same recognition unit 27 assumes instead a second operative condition when the security key 26 is not associated to the recognition unit 27.

The control unit 8 is connected to the recognition unit 27 to place the valve 15 in the closed condition when the recognition unit 27 is in the second operative condition. In this way, when the key 26 is not associated to the recognition unit 27, i. e. is not inserted in the starting block, the valve 15 interrupts the hydraulic circuit 13 preventing the command element 4 from acting on the first actuator 2.

In a second embodiment, shown in Figure 2, the transmission means 6 are of the mechanical type and comprise a kinetic chain 16 that connects the pedal 5 with the actuator 2, which in this case is substantially constituted by a lever 17 connected to one of the disks of the clutch 3.

The kinetic chain 16 presents an engagement portion 18, advantageously constituted by a wheel 19 provided with a toothed sector 19a. In this case, the locking element 7 comprises at least an engagement element 20 movable between a first position in which it locks the kinetic chain 16 and a second position. In the first position, corresponding to the operative condition of the locking element 7, the engagement element 20 engages the engagement portion 18; whilst in the second position, shown in Figure 2, corresponding to the non operative condition of the locking element 7, the engagement element 20 does not engage the engagement portion 18. A second actuator 21 is provided for moving the engagement element 20 between the first and the second position upon the command of the control unit 8.

In detail, the engagement element 20 comprises a retaining pawl 22 and a spring 22a which tends to maintain the pawl 22 in the unlocked condition of the wheel 19. The pawl 22 abuts against at least one of the teeth 23 of the wheel 19 when the second actuator 21 is operated. In this embodiment as well, since the spring 22a tends to maintain the pawl 22 disengaged relative to the wheel 19, in case of malfunction of the locking element 7, of the control unit 8, of the sensors or of other

components, the normal functionality of the device 1 for operating the clutch is always assured.

Alternatively, in accordance with a third embodiment, shown in Figure 3, the engagement portion 18 can present a braking track 24 whereon is active an engagement element 20 comprising a pair or braking shoes 26, operated by an electromagnetic device 26a.

Similarly to the first embodiment, in the case of the second and third embodiments as well the device according to the invention can serve an anti-theft function. In this case, too, the device comprises a security key 26 able to be associated to a unit 27 for recognising the key 26 itself. The recognition unit is in a first operative condition when the security key 26 is associated to the recognition unit 27 and in a second operative condition when the security key 26 is not associated to the recognition unit 27. In this case the control unit 8 is connected to the recognition unit 27 to place the engagement element 20 in the first position when the recognition unit 27 is in the second operative condition. In this way, when the key 26 is not associated to the recognition unit 27 the engagement element 20 blocks the kinetic chain 16 preventing the command element 4 from acting on the first actuator 2.

The operation of the device, previously illustrated in prevalently structural terms, is as follows.

To disengage the clutch 3 it is necessary to exert a force on the command element 4, typically by pressing the pedal 5 of the clutch. In this way the command element 4 is brought to the working condition and the first actuator 2 is placed in the operative condition. In this situation the control unit 8 verifies whether vehicle speed is zero.

According to alternative embodiments, the control unit 8 also verifies whether the brake pedal 11 is operated and/or whether the gear selector 25 is in the condition of first gear engagement. If the zero speed condition is met or if, alternatively, the zero speed and brake operation conditions, in combination, and/or the gear selector 25 in first gear condition, are a met, then the locking element 8 is activated to

maintain the actuator 2 in the operative condition with no need to continue exerting a noticeable force on the pedal 5.

To summarise, the conditions of the consents to allow the operation of the device 1 can be the following: a) only zero speed consent from the sensor 9; b) zero speed consent from the sensor 9 and brake operation consent from the sensor 10; c) zero speed consent from the sensor 9, brake operation consent from the sensor 10 and gear selector 25 in first gear consent from the sensor 12, in combination; d) operated brake consent from the sensor 10 and gear selector 25 in first gear consent from the sensor 12, in combination.

Moreover, in the conditions (conditions b, c and d) in which the brake operation consent is required, anomalous conditions may arise.

For instance, a driving condition that causes such anomalous operation may occur during a standing start on an uphill slope in which, instead of operating the hand brake and simultaneously accelerating (i. e. pressing the gas pedal) the clutch is released, the brake pedal and the gas pedal are operated simultaneously with the right foot alone, performing the manoeuvre known in automotive jargon as heel and toe.

In the latter condition the clutch could not be released since the aforesaid consent conditions b, c and d which allow the operation of the device 1 are met. To solve the problem that could arise in the driving condition described above, an additional consent could be required at the gas pedal. The gas pedal should not therefore be pressed to allow the operation of the device 1, when the condition of simultaneous operation of the brake pedal and of the gas pedal is met the device 1 must be deactivated. Alternatively, as indicated in the consent condition a), the zero velocity determination alone would be sufficient to allow a correct operation in all driving conditions.

Returning to the case of the first embodiment, shown in Figure 1, the activation of the locking element 8 to maintain the actuator 2 in the operative condition without

need to continue exerting a noticeable force on the pedal 5, is obtained closing the valve 15, thereby interrupting the hydraulic circuit 13 and maintaining the hydraulic pressure that bring the actuator 2 to the operative condition.

In the case of the second embodiment, shown in Figure 2, the control element 4 acts on the first actuator 2 by means of the engagement element 20 which blocks the kinetic chain 16 in a configuration in which the actuator 2 is in the operative condition.

Regardless of the embodiment of the device, when vehicle speed is not zero (or in addition the brake 11 is deactivated, or alternatively the gear selector 25 is no longer in the condition of first gear engagement), the control unit 8 brings the locking element into the non operative condition returning full control of the clutch 3 to the pedal 5.

In other words, the valve 15 for shutting the hydraulic circuit 13 or the engagement element 20 to engage the portion 18 receive the signal from the control unit 8 which in turn acts upon the consent of the speed sensor 9, which is generally already provided on the vehicle. If said sensor is not present or cannot be applied, it can be replaced by a sensor 12, or a sensor 12 can be added, which sensor 12 is installed on the gear selector 25, able to signal the shifting into first gear, the most used one when moving in traffic.

With this scheme, the consent coming from the speed sensor 9 for the stopped vehicle, possibly combined with the brake pedal 11 operation consent or (in addition) with the first gear engagement consent from sensor 12, determines the stopped vehicle situation. As a consequence of the aforesaid consents (at least the one of the speed sensor 9, in addition to that of the sensor 10 of the brake, and/or of the first gear engaged sensor 12), the control unit 8 provides the command to the valve 15 to close the hydraulic circuit of the clutch or the command to the engagement element 20 to engage the portion 18.

The return of the clutch pedal is thereby prevent, allowing the driver, with the first gear engaged and the brake pedal operated-i. e. with the right foot on the brake-

to remove, for the period during which the vehicle is motionless, the left foot from the clutch pedal. To disengage the device, it is sufficient to remove one's foot from the brake pedal and thereby deactivate the brake sensor 10.

The invention achieves important advantages.

The claimed device allows first of all to minimise the effort required to operated a clutch, making it less tiresome to drive a vehicle. In particular the device allows to maintain the clutch disengaged without having to exert a force on the pedal 5 in a continuous manner. A further advance of the invention is that of achieving the aforementioned aims by means of a constructively simple device, of small size and of low cost.

The same device can also be advantageously used also as an anti-theft device.