CONTROL OF THE PRIMARY SHAFT SPEED OF A DUAL-CLUTCH TRANSMISSION IN A VEHICLE

Abstract

A control method is implemented in a vehicle comprising a powertrain coupled to a primary shaft driving first and second secondary shafts coupled respectively to first and second clutches within a dual-clutch transmission and having first and second secondary speeds respectively in operation. This method includes a step (10-20) in which maximum permissible first and second secondary speeds are determined for the first and second secondary shafts respectively at a given instant, and then a maximum primary speed equal to the lower of the determined maximum first and second secondary speeds is determined for the primary shaft. Figure 3

Description

Title of the invention: CONTROL OF THE SPEED OF THE PRIMARY SHAFT OF A DOUBLE CLUTCH GEARBOX OF A VEHICLE Technical field of the invention

[0001] The invention relates to vehicles comprising a powertrain (or GMP) coupled to a dual-clutch gearbox, and more specifically to the control of the speed of the primary shaft of such a gearbox. State of the art

[0002] Certain vehicles, possibly of the automobile type, comprise a powertrain (or GMP) coupled to a main input shaft of a dual-clutch gearbox (or DCT (“Dual-Clutch Transmission”)).

[0003] As is known to those skilled in the art, the main input shaft drives first and second secondary input shafts which are coupled respectively to first and second clutches themselves coupled respectively to first and second sub-parts dedicated respectively to first and second sub-sets of ratios (for example 1, 3 and 5, and 2, 4, 6 and possibly 7), within the gearbox.

[0004] During a rolling phase of the vehicle, torque is successively transferred through the first or second clutch (via respectively the first or second secondary primary shaft), depending on the gear engaged.

[0005] In order not to damage the friction linings of the first and second clutches, maximum slip speeds must be respected within these first and second clutches. However, since the GMP is coupled to the main input shaft, it frequently happens that the speed of the latter causes the maximum slip speed of the first or second clutch to be exceeded, which reduces its service life as well as potentially the service life of the associated first or second secondary input shaft.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] It proposes in particular for this purpose a control method intended to be implemented in a vehicle comprising a powertrain (or GMP) coupled to a main primary shaft driving first and second secondary primary shafts coupled respectively to first and second clutches within a dual-clutch gearbox and having respectively first and second secondary speeds in progress.

[0008] This control method is characterized by the fact that it comprises a step in which first and second secondary primary shafts are determined respectively for the first and second maximum secondary speeds authorized at a given instant, then a maximum main speed is determined for the main primary shaft which is equal to the smallest of these first and second maximum secondary speeds determined.

[0009] Thanks to the invention, it is now certain that the maximum sliding speeds of the first and second clutches will be respected and therefore that the friction linings of the latter will not be damaged, which makes it possible to avoid excessively high primary speeds of the main primary shaft leading to a reduction in the service lives of the first and second clutches and potentially of the first and second secondary primary shafts.

[0010] For example, in the step of the method, it is possible to determine, on the one hand, the first maximum secondary speed authorized at the instant considered by adding to the first current secondary speed a first value which is a function of a first torque currently being transmitted by the first clutch, and, on the other hand, the second maximum secondary speed authorized at the instant considered by adding to the second current secondary speed a second value which is a function of a second torque currently being transmitted by the second clutch.

[0011] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a control method of the type presented above, in a vehicle comprising a powertrain coupled to a main input shaft driving first and second secondary input shafts coupled respectively to first and second clutches within a dual-clutch gearbox and having respectively first and second current secondary speeds, to control a maximum main speed for the main input shaft.

[0012] The invention also provides a control device intended to equip a vehicle comprising a powertrain coupled to a main input shaft driving first and second secondary input shafts coupled respectively to first and second clutches within a dual-clutch gearbox and having respectively first and second current secondary speeds.

[0013] This control device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting of determining for the first and second secondary primary shafts respectively first and second maximum secondary speeds authorized at a given instant, then determining for the main primary shaft a maximum main speed which is equal to the smallest of these determined first and second maximum secondary speeds.

[0014] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a powertrain (or GMP) coupled to a main primary shaft driving first and second secondary primary shafts coupled respectively to first and second clutches within a double clutch gearbox and having respectively first and second secondary speeds in progress, and, on the other hand, a control device of the type presented above.

[0015] For example, the GMP may comprise a first prime mover coupled via a first coupling device to a second prime mover coupled to the main input shaft. In this case, the first prime mover may be thermal, and the second prime mover may be non-thermal (and for example electric). Brief description of the figures

[0016] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0017] [Fig-1] schematically and functionally illustrates an example of the embodiment of a vehicle comprising a control device according to the invention and a hybrid GMP transmission chain and associated with a supervision computer,

[0018] [Fig.2] schematically and functionally illustrates an example of the embodiment of a supervision calculator comprising an exemplary embodiment of a control device according to the invention,

[0019] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention, and

[0020] [Fig.4] schematically illustrates within a diagram examples of evolutions temporal (t in seconds (s)) of the first secondary regime (rsl), of the first maximum secondary regime (rslmax), of the second secondary regime (rs2), of the second maximum secondary regime (rs2max), and of the maximum main regime (rpmax). Detailed description of the invention

[0021] The invention aims in particular to propose a control method, and an associated control device DC2, intended to allow control, in a vehicle V comprising a dual-clutch gearbox BV, of the main speed rp of the main input shaft APP of this gearbox BV.

[0022] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car, as illustrated in [Fig.l]. But the invention is not limited to this type of vehicle. It in fact concerns any type of vehicle comprising a transmission chain with a double-clutch gearbox. Thus, it concerns land vehicles (utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, and trains, for example), aircraft and boats.

[0023] Furthermore, it is considered in the following, by way of non-limiting example, that the transmission chain of the vehicle V comprises a hybrid powertrain (or GMP) (and therefore comprising at least a first thermal motor engine (MM1) and at least a second non-thermal motor engine (MM2)). But the invention is not limited to this type of GMP. It in fact concerns any type of GMP, and in particular purely thermal GMPs and purely electric GMPs.

[0024] Furthermore, it is considered in the following, by way of non-limiting example, that the second non-thermal driving machine MM2 of the GMP is electric. But the second non-thermal driving machine could be of another type, since it can at least provide a (second) torque for the driving wheels of its vehicle.

[0025] [Fig.l] schematically shows a vehicle V comprising a control device DC2 according to the invention, a hybrid GMP transmission chain (and therefore comprising at least a first thermal motor MM1 and a second non-thermal motor MM2) and a dual-clutch gearbox BV, a supervision computer CS, and a main battery (or traction or power) BP.

[0026] As illustrated, the transmission chain also comprises, here, a motor shaft AM, a coupling device DC1, a gearbox BV, and a transmission shaft AT.

[0027] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0028] The first (thermal) driving machine MM1 comprises a crankshaft (not shown) which is fixedly secured to the motor shaft AM in order to drive the latter (AM) in rotation. This first driving machine MM1 is capable of operating according to a first speed to provide a first torque which is a function of a first torque setpoint, for example determined by the supervision computer CS.

[0029] The control of the operation of this first driving machine MM1 is ensured by a machine computer CM.

[0030] Furthermore, the first driving machine MM1 is capable of being coupled to the gearbox BV, via at least the coupling device DC1. The latter (DC1) is capable of delivering a torque from the first torque, in particular for at least one train T1 of driving wheels, when it is in its coupled (or closed) position and therefore when it couples the first thermal driving machine MM1 to the main input shaft APP of the gearbox BV.

[0031] For example, the coupling device DC1 may be a hydraulic circuit clutch. But it could be of another type.

[0032] Also for example and as illustrated non-limitingly in [Fig.l], the train Tl can be located in the front part PVV of the vehicle V. It is preferably, and as illustrated, coupled to the transmission shaft AT via a differential (here front) DV. But in a variant this train Tl could be the one referenced T2 which is located in the rear part PRV of the vehicle V.

[0033] The second (non-thermal (here electric)) driving machine MM2 is capable of providing for the driving wheels of the vehicle V a second torque defined by a second torque setpoint, for example determined by the supervision computer CS.

[0034] The second prime mover MM2 is, here, installed between the coupling device DC1 and the main input shaft APP of the gearbox BV. It therefore provides a second torque for the train T1 when it is supplied with electrical energy by the main battery BP. But in a variant it could provide a second torque for the train T2. ​​More precisely, in the example illustrated non-limitingly in [Fig.l], the second prime mover MM2 is here connected to the output of the coupling device DC1 and to the main input shaft APP of the gearbox BV. It is therefore physically interposed between the coupling device DC1 and the main input shaft APP of the gearbox BV, and therefore the first torque provided by the first prime mover MM1 via the coupling device DC1 is transferred to the gearbox BV via the second prime mover MM2.But in an alternative embodiment (not shown) the transmission chain could comprise another coupling device physically interposed between the coupling device DC1 and the main input shaft APP of the gearbox BV, and in this case the second driving machine MM2 is coupled via a mechanism between the output of the coupling device DC1 and this other coupling device.

[0035] It will be noted that the main input shaft APP has a main speed rp which is a function of the torque supplied to it by the GMP.

[0036] For example, the main battery BP may be of the cellular type. In this case, it comprises electrical energy storage cells, possibly electrochemical (such as, for example, lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type cells). Also, for example, this main battery BP may be of the 450 V type. But this is not an obligation. Indeed, it could alternatively be of the 48 V or 600 V type, for example.

[0037] The gearbox BV being a double clutch (or DCT), it comprises first APS1 and second APS2 secondary primary shafts, first El and second E2 clutches, and first SP1 and second SP2 sub-parts dedicated respectively to first and second sub-sets of ratios (for example 1, 3 and 5, and 2, 4, 6 and possibly 7).

[0038] The first APS1 and second APS2 secondary primary shafts are driven in rotation by the main input shaft APP and are coupled respectively to the first El and second E2 clutches in order to transfer to them the torque they receive from the main input shaft APP coming from the GMP. Furthermore, the first APS1 and second APS2 secondary input shafts have respectively first rsl and second rs2 secondary speeds in progress.

[0039] The vehicle V also includes here an accelerator pedal PA (or similar) which allows the driver to signal his desire to accelerate, which then serves to define a torque request (driver).

[0040] As mentioned above, the invention proposes in particular a control method intended to allow the control of the main speed rp of the main primary shaft APP of the gearbox BV.

[0041] This (control) method can be implemented at least partially by the control device DC2 (illustrated at least partially in FIGS. 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one memory MD. This control device DC2 can therefore be produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can be a microcontroller.

[0042] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the control method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0043] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC2 is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC2 could comprise its own dedicated computer, which can then be coupled to the supervision computer CS, or could be part of another computer on board the vehicle V and providing at least one other function.

[0044] As illustrated non-limitingly in [Fig. 3], the (control) method, according to the invention, comprises a step 10-20 which is implemented each time the GMP of the vehicle V is in operation and therefore provides torque to the main input shaft APP of the gearbox BV.

[0045] Step 10-20 of the method comprises a sub-step 10 in which one (for example the control device DC2) determines for the first APS1 and second APS2 secondary primary shafts respectively the first rslmax and second rs2max maximum secondary speeds authorized at a considered instant t.

[0046] Step 10-20 of the method comprises a sub-step 20 in which one (for example the control device DC2) determines for the main primary shaft APP a maximum main speed rpmax which is equal to the smallest of the first rslmax and second rs2max maximum secondary speeds determined, i.e. rpmax = min(rslmax, rs2max).

[0047] The main speed rp of the main primary shaft APP can then be limited at each instant t by the determined maximum main speed rpmax.

[0048] By imposing that the main speed rp of the main primary shaft APP is at all times at most equal to the smallest of the first rslmax and second rs2max maximum secondary speeds, it is certain that the maximum sliding speeds of the first El and second E2 clutches are respected and therefore that the friction linings of the latter (El and E2) will not be damaged. There is therefore no longer any risk that the service lives of the first El and second E2 clutches and potentially of the first APS1 and second APS2 associated secondary primary shafts are reduced by excessively high primary speeds rp of the main primary shaft APP. In addition, this allows better resistance to mechanical stresses and organic protection of the gearbox BV.

[0049] [Fig.4] schematically illustrates an example of a time evolution diagram (t in seconds (s)) of five regimes r (in revolutions per minute (or rpm)). These five regimes r are the first current secondary regime rsl, the first maximum secondary regime rslmax (function of the first current secondary regime rsl), the second secondary regime rs2, the second maximum secondary regime rs2max (function of the second current secondary regime rs2), and the maximum main regime rpmax (function of the first rslmax and second rs2max maximum secondary regimes).

[0050] As can be seen, as long as the first maximum secondary speed rslmax is less than the second maximum secondary speed rs2max, the maximum main speed rpmax is equal to the first maximum secondary speed rslmax, and as soon as the first maximum secondary speed rslmax becomes greater than the second maximum secondary speed rs2max, the maximum main speed rpmax is equal to the second maximum secondary speed rs2max. In other words, the maximum main speed rpmax is always equal to the smaller of the first rslmax and second rs2max maximum secondary speeds.

[0051] For example, in sub-step 10 of step 10-20, one (for example the control device DC2) can determine the first maximum secondary speed rslmax authorized at the instant t considered by adding to the first current secondary speed rsl a first value vl which is a function of the first torque being transmitted by the first clutch E1 at this instant t, i.e. rslmax = rsl + vl. Similarly, one (for example the control device DC2) can determine the second secondary speed maximum rs2max authorized at the instant t considered by adding to the second current secondary regime rs2 a second value v2 which is a function of the second torque being transmitted by the second clutch E2 at this instant t, i.e. rs2max = rs2 + v2.

[0052] It will be understood that the first vl or second v2 value is a speed corresponding to the first or second torque transmitted by the first El or second clutch E2, the values ​​vl and v2 being able to be positive or negative. Each first torque transmitted by the first clutch El is therefore converted into a first value vl, and each second torque transmitted by the second clutch E2 is therefore converted into a second value v2, for example by the control device DC2.

[0053] It will be noted that the first rslmax and second rs2max maximum secondary speeds can be determined differently from what is described above, and in particular as a function of correspondence tables (or maps) establishing correspondences between torques of first secondary speed rsl and first torque transmitted by the first clutch E1 and first maximum secondary speeds rslmax, and between torques of second secondary speed rs2 and second torque transmitted by the second clutch E2 and second maximum secondary speeds rs2max.

[0054] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the machine computer CM (or the computer of the control device DC2) can also comprise a mass memory MME, in particular for storing the first rsl and second rs2 current secondary speeds and the first and second torques transmitted respectively by the first El and second E2 clutches, as well as any intermediate data involved in all its calculations and processing.Furthermore, this machine computer CM (or the computer of the control device DC2) can also comprise an input interface IE for receiving the first rsl and second rs2 current secondary speeds and the first and second torques transmitted respectively by the first El and second E2 clutches, to use them in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2. In addition, this machine computer CM (or the computer of the control device DC2) can also comprise an output interface IS, in particular for delivering each message containing a determined maximum main speed rpmax.

[0055] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the control method described above to control the main speed rp of the main primary shaft APP of the dual-clutch gearbox BV of the vehicle V.

Claims

Claims

1. Control method for a vehicle (V) comprising a powertrain coupled to a main input shaft (APP) driving first (APS1) and second (APS2) secondary input shafts coupled respectively to first (El) and second (E2) clutches within a dual-clutch gearbox (BV) and having respectively first and second current secondary speeds, characterized in that it comprises a step (10-20) in which first and second maximum authorized secondary speeds are determined for said first (APS1) and second (APS2) secondary input shafts respectively, then a maximum main speed equal to the smallest of said first and second determined maximum secondary speeds is determined for said main input shaft (APP).

2. Method according to claim 1, characterized in that in said step (10-20) i) said first maximum secondary speed authorized at said instant in question is determined by adding to said first current secondary speed a first value which is a function of a first torque being transmitted by said first clutch (El), and ii) said second maximum secondary speed authorized at said instant in question by adding to said second current secondary speed a second value which is a function of a second torque being transmitted by said second clutch (E2).

3. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to one of claims 1 and 2, in a vehicle (V) comprising a powertrain coupled to a main input shaft (APP) driving first (APS1) and second (APS2) secondary input shafts coupled respectively to first (El) and second (E2) clutches within a dual-clutch gearbox (BV) and having respectively first and second current secondary speeds, to control a maximum main speed for said main input shaft (APP).

4. Control device (DC2) for a vehicle (V) comprising a powertrain coupled to a main input shaft (APP) driving first (APS1) and second (APS2) secondary input shafts coupled respectively to first (El) and second (E2) em- clutches within a dual-clutch gearbox (BV) and having respectively first and second current secondary speeds, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of determining for said first (APS1) and second (APS2) secondary primary shafts respectively first and second maximum secondary speeds authorized at a given time, then determining for said main primary shaft (APP) a maximum main speed equal to the smallest of said first and second determined maximum secondary speeds.

5. Vehicle (V) comprising a powertrain coupled to a main input shaft (APP) driving first (APS1) and second (APS2) secondary input shafts coupled respectively to first (El) and second (E2) clutches within a dual-clutch gearbox (BV) and having respectively first and second secondary speeds in progress, characterized in that it further comprises a control device (DC2) according to claim 4.

6. Vehicle according to claim 5, characterized in that said powertrain comprises a first driving machine (MM1) coupled via a first coupling device (DC1) to a second driving machine (MM2) coupled to said main input shaft (APP).

7. Vehicle according to claim 6, characterized in that said first driving machine (MM1) is thermal, and said second driving machine (MM2) is non-thermal.

8. Vehicle according to claim 7, characterized in that said second driving machine (MM2) is electric.

9. Vehicle according to one of claims 5 to 8, characterized in that it is of the automobile type.

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