Method for piloting a clutch in pre-engagement

Abstract

The invention relates to a method for a clutch in a motor vehicle transmission comprising a gear lever (8), a powertrain (1) including an engine (3, 5) and a transmission device (4) including a gearbox (41, 42) having a primary shaft (6) and a clutch (K1, K2), wherein, when the gear lever (8) leaves a "parking" position (P), the method comprises the steps of: at least partially filling a clutch slave cylinder to generate engine torque by friction; and simultaneously, engaging a gear in the gearbox. Figure 1

Description

Title of the invention: METHOD FOR CONTROLLING A PRE-ENGAGED CLUTCH Technical field of the invention

[0001] The invention relates, in general, to the technical field of the management of the control of a powertrain of a motor vehicle equipped with a thermal powertrain.

[0002] More specifically, the invention relates to the control of the clutch of the transmission, in particular of the DCT or e-DCT type, in pre-engagement when a clutch lever moves from the parking position to the driving position via the neutral position. State of the prior art

[0003] In the remainder of the description, the example of implementation of the invention described is a hybrid motor vehicle whose motive power is alternately or cumulatively provided by a heat engine and an electric machine supplied with electrical energy by batteries. The heat engine and the electric machine form a motor assembly whose motive energy is transmitted by a DCT type transmission device to a front or rear wheel set. This example of implementation of the invention has been chosen to facilitate the description of the invention, without it being limited thereto. Indeed, the invention can also, for example, be applied to a motor vehicle in which the motive energy is transmitted to more than one wheel set, or via a single clutch, or to a motor vehicle comprising only a heat engine.

[0004] In known DCT type transmission devices for hybrid motor vehicles, a control device makes it possible to ensure the transmission to the drive wheel set of an engine torque generated by the thermal engine, the electric machine or both. This control device manages a first clutch connecting the engine assembly to a first gearbox comprising odd transmission ratios, and a second clutch connecting the engine assembly to a second gearbox comprising even transmission ratios.

[0005] Currently, when a motor vehicle equipped with such a transmission is set in motion, a gear lever is moved from a “parking” position P to one of the “forward” and “reverse” positions D and R, briefly passing through a “neutral” position N. A transmission clutch control device closes the clutch once position D or R is reached, which allows engine torque to be transmitted to the wheel. However, closing the clutch The clutch is not immediate, because this closure is carried out by a clutch slave cylinder (or CSC for "Clutch Slave Cylinder" according to Anglo-Saxon terminology). The latter requires a filling which lasts approximately 300 ms. The engine torque is then only available to the wheels once the CSC is filled. There is therefore a delay between the instruction to the gear lever and its realization. This is illustrated on the chronograph of [Fig.2] of the prior art.

[0006] There is therefore a need to control a clutch of a transmission to overcome this delay. Statement of the invention

[0007] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular a solution allowing control of the clutch making it possible to obtain an available engine torque as soon as position D or R is reached at the gear lever.

[0008] To do this, there is proposed, according to a first aspect of the invention, a method for controlling a clutch of a transmission of a motor vehicle comprising a gear lever, a powertrain comprising an engine and a transmission device comprising a gearbox having a primary shaft and a clutch, characterized in that, when the gear lever leaves a “parking” position P, the method comprises steps of: • at least partial filling of a clutch slave cylinder (CSC) in order to generate engine torque by licking; • At the same time, engage a gear within the gearbox.

[0009] According to one embodiment, following filling and engagement, the method comprises a step of positioning the gear lever in position N or neutral.

[0010] According to one embodiment, beyond a predetermined time delay TA, the gear lever remaining in position N, the method comprises steps of • emptying of the clutch slave cylinder (CSC) in order to cancel the engine torque generated by licking; • At the same time, disengagement of the gear previously engaged within the gearbox.

[0011] According to one embodiment, the time delay TA is greater than a filling duration.

[0012] According to one embodiment, the engine torque thus generated by licking is 3N.m.

[0013] According to another aspect of the invention, there is provided a powertrain for a motor vehicle comprising an engine and a transmission device comprising a gearbox having a primary shaft, and a clutch, as well as a computer. arranged so as to implement the method having one of the preceding technical characteristics.

[0014] According to one aspect of the invention, in the powertrain, the transmission device comprises a first gearbox coupled to the primary shaft via a coupling clutch and a second gearbox coupled to the primary shaft via a coupling clutch.

[0015] According to one aspect of the invention, in the powertrain unit comprises a heat engine and an electric machine, a coupling clutch between the heat engine and the primary shaft, and a gear train kinematically connecting the primary shaft to an input of the electric machine.

[0016] According to yet another aspect of the invention, there is provided a motor vehicle comprising a powertrain having one of the preceding technical characteristics. brief description of the figures

[0017] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: • [Fig.l]: a diagram of a powertrain of a hybrid motor vehicle intended to be driven by a driving method according to the invention; • [Fig.2]: a chronograph illustrating the prior art piloting process of a transmission clutch when shifting the gear lever from position P to position D or R, via position N; • [Fig.3]: a chronograph illustrating the process of controlling a clutch of a transmission according to the invention during the same shift of the gear lever from position P to position D or R, via position N; • [Fig.4]: a chronograph illustrating the process of controlling a clutch of a transmission according to the invention when the gear lever is shifted from position P to position N, while maintaining this position N.

[0018] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0019] [Fig.l] schematically illustrates a powertrain 1 of a hybrid motor vehicle within which a method for controlling the clutch of a transmission according to the invention will be implemented. The powertrain 1 drives a front or rear wheel set 2. Alternatively, the powertrain drives two or more wheel sets.

[0020] The powertrain 1 is here a hybrid powertrain. The latter comprises a thermal engine 3, a DCT type transmission device 4. The DCT type transmission device is here an e-DCT type transmission device in that it comprises an electric machine 5.

[0021] On the other hand, the DCT type transmission device 4 comprises a primary shaft 6 and a coupling clutch KO between the thermal engine 3 and the primary shaft 6. The DCT type transmission device 4 also comprises a gear train 65 connecting the electric machine 5 to the primary shaft 6.

[0022] The DCT 4 type transmission device comprises, in a manner known per se, a first gearbox 41, comprising odd transmission ratios, a first clutch K1 for coupling between the primary shaft 6 and that of the first gearbox 41, a second gearbox 42, comprising even transmission ratios, and a second clutch K2 for coupling between the primary shaft 6 and that of the second gearbox 42. Each of the clutches K1 and K2 comprises an associated CSC allowing it to be opened or closed depending on the orders received. In the remainder of the description, K1 and K2 will refer to both the clutch and its associated CSC.

[0023] Finally, a control device or calculator 9 makes it possible to manage the operation of the hybrid powertrain 1, in particular the DCT type transmission device 4, as a function of the position of a gear lever 8 which can take four positions: P for “Parking”, N for “Neutral”, D for “Drive” (Anglo-Saxon term for forward gear) and R for “Reverse” (Anglo-Saxon term for reverse gear). In particular, the control device or calculator 9 is arranged so as to be able to implement the method for controlling a transmission according to the invention which will now be described in more detail.

[0024] With reference to [Fig. 3], we will describe an application of the method for controlling a clutch of a transmission according to the invention applied to a DCT type transmission previously described.

[0025] The method for controlling a clutch of a transmission according to the invention consists in filling the CSC of the clutch K1 / K2 at the moment when the gear lever 8 leaves the position P while engaging a gear in the associated gearbox 41, 42. This filling is carried out in such a way as to make the clutch K1 / K2 in question lick: a diaphragm of the clutch K1 / K2, under the action of the CSC, begins to pinch linings of a clutch disc between a plate of the clutch K1 / K2 and an associated flywheel, thus beginning to transmit an engine torque to the wheel 2 via the associated gearbox 41, 42. The clutch disc is then blocked in rotation due to the fact that the wheel 2 is braked, there is friction of the linings of the clutch disc, sandwiched together, against the plate and the flywheel of the clutch K1 / K2. For example, this licking is arranged so as to obtain an engine torque of the order of 3 Nm

[0026] When the gear lever 8 leaves the P position, it briefly moves to the N position before reaching the DouR position. At that moment, the engine torque due to the licking thus implemented is immediately available to set the motor vehicle in motion thanks to the method for controlling a clutch of a transmission according to the invention described. Thus, the method for controlling a clutch of a transmission according to the invention makes it possible to overcome the delay, due to the filling of the CSC, between the instruction to move from the P position to the D / R position of the gear lever 8 and its realization (presence of an engine torque at the wheel 2).

[0027] However, with reference to [Fig.4], there are life situations where the gear lever 8 leaves position P and then remains in position N beyond a predetermined time delay TA. This time delay TA is greater than the filling time of the CSC of the clutch K1 or K2. In this situation, the method for controlling a clutch of a transmission according to the invention cancels the filling of the CSC of the clutch K1 or K2, by emptying it. This cancels the previously described licking generated within said clutch K1 or K2. The gear engaged within the associated gearbox 41, 42 is disengaged. No more engine torque is then transmitted to the wheel. As licking consumes energy, this makes it possible to limit in this life situation the energy losses due to friction of the clutch disc linings against the plate and the flywheel of the clutch.

[0028] The method for controlling a clutch of a transmission according to the invention has been described in the context of an application of a hybrid motor vehicle with a DCT transmission, therefore with a double clutch K1, K2. Alternatively, the method for controlling a clutch of a transmission according to the invention is implemented within a thermal motor vehicle equipped with a double clutch transmission (DCT) or single clutch, or even in a motor vehicle comprising an electric machine and a single clutch transmission.

[0029] Naturally, the invention is described in the foregoing by way of example. It is understood that the person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

[0030] It is emphasized that all features, as they emerge for a person skilled in the art from the present description, the drawings and the attached claims, even if they have been specifically described only in relation to other determined features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or devoid of sense.

Claims

Claims

1. Method for controlling a clutch of a transmission of a motor vehicle comprising a gear lever (8), a powertrain (1) comprising an engine (3, 5) and a transmission device (4) comprising a gearbox (41, 42) having a primary shaft (6) and a clutch (Kl, K2), characterized in that, when the gear lever (8) leaves a “parking” position P, the method comprises steps of: • at least partial filling of a slave cylinder (CSC) of the clutch in order to generate an engine torque by licking; • In parallel, engagement of a gear within the gearbox.

2. Method according to claim 1, characterized in that, following filling and engagement, the method comprises a step of positioning the gear lever in position N or neutral.

3. Method according to claim 2, characterized in that, beyond a predetermined TA time delay, the gear lever remaining in position N, the method comprises steps of • emptying the clutch slave cylinder (CSC) in order to cancel the engine torque generated by licking; • In parallel, disengagement of the gear previously engaged within the gearbox.

4. Method according to claim 3, characterized in that the time delay TA is greater than a duration of the filling.

5. Method according to one of claims 1 to 4, characterized in that the engine torque thus generated by licking is 3 N. m.

6. Powertrain for a motor vehicle comprising an engine (3, 5) and a transmission device (4) comprising a gearbox (41, 42) having a primary shaft (6), and a clutch (Kl, K2), characterized in that it comprises a computer (9) arranged so as to implement the method according to one of claims 1 to 5.

7. Powertrain according to claim 6, characterized in that the transmission device comprises a first gearbox (41) coupled to the primary shaft via a coupling clutch (Kl) and a second gearbox (42) coupled to the primary shaft (6) via a coupling clutch (K2).

8. Powertrain according to claim 6 or 7, characterized in that it comprises a heat engine (3) and an electric machine (5), a coupling clutch (KO) between the heat engine and the primary shaft (6), and a gear train (65) kinematically connecting the primary shaft to an input of the electric machine.

9. Motor vehicle, characterized in that it comprises a powertrain according to one of claims 6 to 8.

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