CHECKING THE OIL IN THE CLUTCHES OF A DOUBLE-CLUTCH GEARBOX OF A HYBRID GEARBOX OF A LAND VEHICLE

Abstract

A method is implemented in a land vehicle comprising a powertrain comprising first and second thermal and electric prime movers respectively and adapted to be coupled to a gearbox with two clutches, comprising oil and adapted to be each placed in an open state or a closed state, and having a neutral position in which the clutches are in the open state. This method comprises a step (10-20) in which, when the gearbox is in its neutral position, the second prime mover is operated according to a chosen speed in order to induce in the clutches a shearing of the oil and an at least partial evacuation of the latter. Figure 3

Description

Title of the invention: CONTROL OF THE OIL IN THE CLUTCHES OF A DUAL-CLUTCH GEARBOX OF A HYBRID POWERTRAIN OF A VEHICLE TERRESTRIAL Technical field of the invention

[0001] The invention relates to land vehicles comprising a hybrid (thermal and electric) powertrain (or GMP) and a dual-clutch gearbox, and more specifically to the control of the oil present in such clutches. State of the art

[0002] Certain land vehicles, generally of the automobile type, include a hybrid (thermal and electric) powertrain (or GMP) and a dual clutch gearbox (or DCT (“Dual Clutch Transmission”)).

[0003] Here, the term “hybrid GMP” means a GMP comprising a first thermal motor and capable of providing a first engine torque, for example for drive wheels, after having been coupled to the gearbox, and at least one second electric motor and capable at least of providing a second engine torque, for example for drive wheels, after having been coupled to the gearbox. It will be noted that in this type of GMP the second motor is supplied with electrical energy by a battery or a fuel cell (for example hydrogen).

[0004] In a dual-clutch gearbox, both clutches contain oil and are each capable of being placed in an open state, a closed state, or a sliding state. Furthermore, this type of gearbox has a neutral position in which both of its clutches are in the open state and which can be selected by the driver of the vehicle using the gear lever.

[0005] As is known to those skilled in the art, when a vehicle of the type described above is stationary with its GMP active (or started) and the gearbox in its neutral position, and the driver places the gear lever in the forward or reverse position, a gear is engaged in the gearbox and then the second electric motor must be operated to set in motion the clutch concerned by this engaged gear before placing this clutch in its closed state. In fact, the discs of a clutch must be in motion so that the latter can transmit the engine torque that it receives.

[0006] However, the simple fact that the second electric motor increases in speed suddenly causes, before closing, a transmission of torque at the level of the clutch concerned (due to the internal licking of the discs in the open state), and therefore this torque is transmitted to the drive wheels because a gear is engaged, which causes a sudden sensation of shock which is all the more unpleasant for the vehicle's passengers as the intensity of the torque transmitted to the wheels is high. It turns out that this transmission of torque by the open clutch results from an inertial effect and the presence of oil in the clutch. Consequently, the colder the oil, the more viscous it is, and therefore the higher the intensity of the torque transmitted to the wheels. Thus, when the oil is very cold this intensity can typically reach 300 Nm.

[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0008] It proposes in particular for this purpose a control method intended to be implemented in a land vehicle comprising a powertrain comprising first and second thermal and electric motors respectively and suitable for being coupled to a gearbox with two clutches, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which the clutches are in the open state.

[0009] This control method is characterized by the fact that it comprises a step in which, when the gearbox is in its neutral position, the second driving machine is operated at a speed chosen in order to induce in the clutches a shearing of the oil and an at least partial evacuation of the latter.

[0010] Thanks to this shearing and at least partial evacuation of the oil present in the clutches of the gearbox, once a gear is engaged in the gearbox and during the increase in speed of the second driving machine to set in motion the clutch concerned by this gear engaged, the torque transmitted by the latter is notably reduced, and therefore the sensation of shock is almost imperceptible for the passengers of the vehicle.

[0011] The control method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0012] - in its step, one can choose the regime according to a temperature in progress oil, this increasing regime when the current temperature decreases;

[0013] - in the presence of the first option, in its step, the regime can be chosen in an interval having a lower limit between 50 rpm and 150 rpm and an upper limit between 400 rpm and 800 rpm;

[0014] - in the presence of the last sub-option, in its step, the interval can be understood between 100 rpm and 600 rpm;

[0015] - also in the presence of the first option, in its stage, the regime can be chosen from a table establishing a correspondence between oil temperatures and diets;

[0016] - one can perform his step at least just before a required motor torque is produced by at least one of the first and second prime movers.

[0017] 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 land vehicle comprising a powertrain comprising first and second thermal and electric motors respectively and capable of being coupled to a gearbox with two clutches, comprising oil and capable of each being placed in an open state or a closed state, and having a neutral position in which the clutches are in the open state, to control the presence of oil in the clutches.

[0018] The invention also proposes a control device intended to equip a land vehicle comprising a powertrain comprising first and second thermal and electric motors respectively and suitable for being coupled to a gearbox with two clutches, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which the clutches are in the open state.

[0019] 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, when the gearbox is in its neutral position, in triggering operation of the second driving machine according to a chosen speed in order to induce in the clutches a shearing of the oil and an at least partial evacuation of the latter.

[0020] The invention also proposes a land vehicle, possibly of the automobile type, and comprising:

[0021] - a powertrain comprising first and second prime movers respectively thermal and electric and suitable for being coupled to a two-clutch gearbox, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which the clutches are in the open state, and

[0022] - a control device of the type presented above. Brief description of the figures

[0023] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0024] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a land vehicle comprising a control device according to the invention and a chain transmission comprising a hybrid GMP, with a double-clutch gearbox and associated with a supervision computer,

[0025] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a supervision computer comprising an exemplary embodiment of a control device according to the invention, and

[0026] [Fig.3] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0027] The invention aims in particular to propose a control method, and an associated control device DC3, intended to allow control of the oil present in the two clutches of a dual-clutch gearbox BV of a hybrid (thermal and electric) powertrain (or GMP) of a land vehicle V.

[0028] In the following, it is considered, by way of non-limiting example, that the land 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 land vehicle. It in fact relates to any type of land vehicle comprising a GMP transmission chain comprising first and second driving machines, respectively thermal and electric, and suitable for being coupled to a gearbox with double (or two) clutches.

[0029] Furthermore, it is considered in the following, by way of non-limiting example, that the second electric motor MM2 of the GMP is associated with at least one rechargeable BP battery and called main (or “traction” or even “power”). But it could be associated with a fuel cell (for example hydrogen).

[0030] In addition, the transmission chain could also allow a four-wheel drive (or 4x4) or 4x2 mode.

[0031] [Fig.l] schematically shows a (land) vehicle V comprising a GMP transmission chain comprising first MM1 and second MM2 thermal and electric motors respectively and a dual-clutch gearbox BV, a supervision computer CS, a service battery BS, a rechargeable main (or traction) battery BP, a converter CV, and a control device DC3 according to the invention.

[0032] The service battery BS is responsible for supplying electrical energy to an on-board network of the vehicle V, in addition to that supplied by the CV converter powered by the main battery BP via a main electrical circuit, and sometimes instead of this CV converter. For example, this service battery BS can be arranged in the form of a very low voltage type battery (typically 12 V or 24 V). It is rechargeable at least by the CV converter. In the following, as a non-limiting example, we consider that the BS service battery is of the 12 V Lithium-ion type.

[0033] The on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0034] The main electrical circuit (or "high voltage" or "power") is connected, on the one hand, to the main battery BP via an interface device, and, on the other hand, to electronic equipment, such as for example the CV converter and (here) the second (electric) motive power machine MM2. It can also possibly allow the main battery BP to be recharged by an external power source temporarily coupled to the vehicle V.

[0035] As illustrated in [Fig.l], the transmission chain also comprises, here, a motor shaft AM, a first coupling device DC1, a second coupling device DC2, and a transmission shaft AT.

[0036] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0037] The first (thermal) driving machine MM1 comprises a crankshaft (not shown) which is fixedly secured to the engine 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, here for the driving wheels of the vehicle V, a first torque cl which is defined by a first driving setpoint, for example determined by the supervision computer CS.

[0038] The operation of the first driving machine MM1 is controlled by a first machine computer CM1, and supervised by the supervision computer CS.

[0039] In addition, the first driving machine MM1 is capable of being coupled to a primary shaft of the gearbox BV, via at least the first coupling device DC1. The latter (DC1) is capable of delivering a torque from the first torque, in particular (here) for at least one train T1 of driving wheels, when it is in its closed (or coupled) position and therefore when it couples the first driving machine MM1 to the gearbox BV (and more precisely to one of the two clutches associated with the primary shaft of the latter (BV)).

[0040] For example, the first coupling device DC1 may be a hydraulic circuit clutch. But it could be of another type.

[0041] Also for example, the train T1 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) DI. But in a variant this train T1 could be that referenced T2 which is located in the rear part PRV of the vehicle V.

[0042] It will be noted that in the example illustrated non-limitingly in [Fig.l] the crankshaft of the first prime mover MM1 is also coupled to a belt, itself coupled to an alternator-starter AD which is supplied with electrical energy by the service battery BS (and which can also recharge the latter (BS)). Thus, the alternator-starter AD can provide torque to the belt, which can provide this torque to the crankshaft to start the first prime mover MM1. But as a variant or in addition the first prime mover MM1 could be started by the second prime mover MM2 (by placing the first coupling device DC1 in its closed state).

[0043] The second (electric) driving machine MM2 is capable, when it is supplied with electrical energy (here by the main battery BP), of providing, here for the driving wheels of the vehicle V, a second torque defined by a second driving setpoint, for example determined by the supervision computer CS.

[0044] Furthermore, this second driving machine MM2 is suitable for being coupled, downstream of the first coupling device DC1, by the second coupling device DC2, to the primary shaft of the gearbox BV to provide it with the second driving torque that it produces. The second driving machine MM2 therefore provides here the second torque that it produces for the train TL

[0045] It will be noted that the second driving machine MM2 may also be arranged so as to recover in the vehicle V a third torque defined by a setpoint, for example in a regenerative braking phase, and in this case this third recovered torque may be used to recharge the main battery BP associated with the second driving machine MM2. But the recovery may also be done on a part of the first torque provided by the first driving machine MM1.

[0046] The operation of the second driving machine MM2 is controlled by a second machine computer CM2, and supervised by the supervision computer CS.

[0047] The second coupling device DC2 can be placed in coupled (or closed) and decoupled (or open) states, depending on a state instruction generated by the GMP supervision computer CS.

[0048] Furthermore, this second coupling device DC2 may, for example, comprise a cascade of pinions connecting the second driving machine MM2 to the input of the gearbox BV (downstream of the first coupling device DC1).

[0049] It will be understood that when the first coupling device DC1 has been placed in its (completely) closed (or coupled) state and the first driving machine MM1 is in operation (and therefore has a first non-zero speed to provide the first torque), the first coupling device DC1 delivers a torque which is added to a possible second torque provided, upstream of the gearbox BV, by the second driving machine MM2 when it is supplied (here) with electrical energy. (here) by the main battery BP. When the first coupling device DC1 has been placed in its (completely) open (or decoupled) state, only the second prime mover MM2 can provide a second torque upstream of the gearbox BV in a purely electric driving phase.

[0050] For example, the main battery (or traction or even power) 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.

[0051] As indicated above, the gearbox BV comprises at least one primary shaft which is associated with its two clutches which comprise oil and are each able to be placed in a state chosen from an open (or decoupled) state, a closed (or coupled) state, and a sliding state. For example, the gearbox BV offers odd ratios (1, 3, 5, 7,...) associated with the first clutch, and even ratios (2, 4, 6,...) associated with the second clutch.

[0052] It will be noted that the gearbox BV has a neutral position in which its two clutches are in the open state and which can be selected by the driver of the vehicle by means of a gear lever LV.

[0053] When the gearbox BV receives a torque as input (on its primary shaft associated with the clutch in use (and therefore placed in its closed state or its sliding state)), and it has a gear engaged (chosen from all its gears), it delivers on its output (and therefore here to the transmission shaft AT) an output torque (here for the drive wheels of the front axle T1).

[0054] The operation of the gearbox BV is controlled by a gearbox computer CB, and supervised by the supervision computer CS.

[0055] As mentioned above, the invention proposes in particular a control method intended to enable the control of the oil which is present in the two clutches of the gearbox BV.

[0056] This (control) method can be implemented at least partially by the control device DC3 (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 DC3 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.

[0057] The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the control method. The processor PR1 may include integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is any type of device capable of performing at least one electrical or electronic operation.

[0058] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC3 is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC3 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, such as for example the second machine computer CM2.

[0059] As illustrated non-limitingly in [Fig. 3], the (control) method, according to the invention, comprises a step 10-20 which is implemented each time a condition is verified, namely the gearbox BV is in its neutral position, and therefore the vehicle V is stationary with its GMP active (or started).

[0060] Step 10-20 of the method comprises a sub-step 20 in which, when the aforementioned condition is verified, the second driving machine MM2 is temporarily operated (for example the control device DC3 triggers the temporary operation of) according to a chosen speed rc in order to induce in the clutches of the gearbox BV (placed in their open state) a shearing of the oil and an at least partial evacuation of this oil.

[0061] For this purpose, one (for example the control device DC3) can transmit (or have transmitted by the supervision computer CS) to the second machine computer CM2 a speed instruction defining the chosen speed rc.

[0062] This shearing and at least partial evacuation of the oil present in the clutches of the gearbox BV advantageously allows, once a gear is engaged in the gearbox BV and during the increase in speed of the second driving machine MM2 to set in motion the clutch concerned by this gear engaged (and still in its open state), a significant reduction of the inertial effect in this clutch, and therefore a significant reduction of the torque transmitted by the latter. This results in a significant reduction of the torque transmitted to the drive wheels by the gearbox BV, and therefore a sensation of shock that is almost imperceptible for the passengers of the vehicle V. Typically, the intensity of the torque transmitted to the wheels can now be approximately 50 Nm instead of approximately 300 Nm (without the implementation of the invention).

[0063] It will be understood that step 10-20, making it possible to carry out shearing and at least partial evacuation of the oil, can be carried out in an anticipatory manner, for example due to programming of the control device DC3 or on request, for example from the supervision computer CS. For example, this step 10-20 is carried out at least just before a motor torque, required by the CS supervision computer, is produced by at least one of the first MM1 and second MM2 driving machines.

[0064] It will be noted, as illustrated non-limitingly in [Fig. 3], that it is advantageous for step 10-20 to include a sub-step 10 in which one (for example the control device DC3) chooses the speed rc as a function of the current temperature of the oil. In this case, the speed rc increases when the current temperature decreases. The current temperature of the oil is generally known to the gearbox computer CB which controls the operation of the gearbox BV, thanks to the measurements taken periodically by a dedicated temperature sensor (for example installed in a casing of the gearbox BV).

[0065] This option is intended to take into account the fact that the colder the oil, the more viscous it is, and therefore the higher the intensity of the torque that can be transmitted by one of the two open clutches during an increase in speed of the second driving machine MM2. Consequently, the colder the current temperature of the oil, the more preferable it is that the chosen speed rc be high to accentuate the shearing effect of the oil and the quantity of oil evacuated.

[0066] But in an alternative embodiment the chosen regime rc could be fixed and predefined (and therefore independent of the current oil temperature).

[0067] For example, in sub-step 10 of step 10-20 the speed rc can be chosen in an interval which has a lower limit between 50 rpm and 150 rpm and an upper limit between 400 rpm and 800 rpm. For example, in sub-step 10 of step 10-20 the interval in which the speed rc is chosen can be between 100 rpm and 600 rpm. In this case, a chosen speed rc of 100 rpm is preferably used when the current oil temperature is greater than or equal to +20°C, and a chosen speed rc of 600 rpm is preferably used when the current oil temperature is less than or equal to 0°C, and therefore between 0°C and +20°C, speeds rc strictly greater than 100 rpm and strictly less than 600 rpm are chosen.

[0068] But other speed ranges can be used. Generally speaking, the lower and upper limits of the speed range used in a vehicle V can be determined during development or testing phases of a vehicle similar to this vehicle V.

[0069] Similarly, the duration during which the second prime mover MM2 is operated according to the chosen regime rc can be determined during development or testing phases of a vehicle similar to the vehicle V. Typically, this duration can be between 100 ms and 5 seconds.

[0070] Also for example, in sub-step 10 of step 10-20 the rc regime can be chosen (for example by the DC3 control device) from a correspondence table (or mapping) which establishes a correspondence between oil temperatures and speeds, and which is stored in a memory (preferably dead and for example from the DC3 control device).

[0071] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the control device DC3) can also comprise a mass memory MEM, in particular for storing each possible current temperature of the oil, as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision computer CS (or the computer of the control device DC3) can also comprise an input interface IE for receiving each possible current temperature of the oil, to use it in calculations or processing, possibly after having shaped and / or demodulated and / or amplified it, in a manner known per se, by means of a digital signal processor PR2.In addition, this supervision calculator CS (or the calculator of the control device DC3) can also include an output interface IS, in particular to deliver each message (or order) containing the chosen regime rc. .

[0072] 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 presence of oil in the two clutches of the gearbox BV of the land vehicle V.

Claims

Claims

1. Control method for a land vehicle (V) comprising a powertrain comprising first (MM1) and second (MM2) thermal and electric prime movers respectively and suitable for being coupled to a gearbox (BV) with two clutches, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which said clutches are in said open state, characterized in that it comprises a step (10-20) in which, when said gearbox (BV) is in said neutral position, said second prime mover (MM2) is operated according to a chosen speed in order to induce in said clutches a shearing of the oil and an at least partial evacuation of the latter.

2. Method according to claim 1, characterized in that in said step (10-20) said regime is chosen as a function of a current temperature of said oil, said regime increasing when said current temperature decreases.

3. Method according to claim 2, characterized in that in said step (10-20) said speed is chosen in an interval having a lower limit between 50 rpm and 150 rpm and an upper limit between 400 rpm and 800 rpm.

4. Method according to claim 3, characterized in that in said step (10-20) said interval is between 100 revolutions / minute and 600 revolutions / minute.

5. Method according to one of claims 2 to 4, characterized in that said regime is chosen from a table establishing a correspondence between oil temperatures and regimes.

6. Method according to one of claims 1 to 5, characterized in that said step (10-20) is carried out at least just before a required engine torque is produced by at least one of said first (MM1) and second (MM2) driving machines.

7. 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 to 6, in a land vehicle (V) comprising a powertrain comprising first (MM1) and second (MM2) thermal and electric motors respectively and capable of being coupled to a gearbox (BV) with two clutches, comprising oil and each capable of being placed in an open state or a closed state, and having a neutral position in which said clutches are in said open state, to control the presence of oil in said clutches.

8. Control device (DC3) for a land vehicle (V) comprising a powertrain comprising first (MM1) and second (MM2) respectively thermal and electric prime movers and suitable for being coupled to a gearbox (BV) with two clutches, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which said clutches are in said open state, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, when said gearbox (BV) is in said neutral position, in triggering an operation of said second prime mover (MM2) according to a chosen regime in order to induce in said clutches a shearing of the oil and an at least partial evacuation of the latter.

9. Land vehicle (V) comprising a powertrain comprising first (MM1) and second (MM2) thermal and electric motors respectively and suitable for being coupled to a gearbox (BV) with two clutches, comprising oil and suitable for each being placed in an open state or a closed state, and having a neutral position in which said clutches are in said open state, characterized in that it further comprises a control device (DC3) according to claim 8.

10. Vehicle according to claim 9, characterized in that it is of the automobile type.

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