Patent Application
20100258367
The present invention relates to a drive system, traction or propulsion drive, for hybrid type vehicles.
This type of vehicles generally combines a thermal engine, mainly an internal-combustion engine, and an electric machine connected to an electric source, such as one or more electric accumulators, for propelling them. This combination allows the energy efficiency of the drive system to be optimized while decreasing the total fuel consumption and limiting emissions.
In the example described in document FR-2,670,440, the thermal engine comprises an output shaft that drives the motive part of a variable transmission, such as a variable speed drive, and whose transmission receiving part is connected to the motive axle of the vehicle. The output shaft carries, between the thermal engine and the variable speed drive, an electric machine connected to an electric battery and two clutches, a first clutch between the thermal engine and the electric machine, and a second clutch between the electric machine and the variable speed drive.
When the vehicle is to be driven with a high torque available over a wide speed range while limiting exhaust gas emissions and noise generation, as in an urban site, the electric machine is preferably used for driving the motive axle of the vehicle and, consequently, the driving wheels of this vehicle.
On the other hand, for uses where a high engine driving power and a wide operating range are required, the thermal engine is used for driving the motive axle and thus providing displacement of the vehicle.
Although satisfactory, this drive system however involves some significant drawbacks.
In fact, when only the electric machine is used to drive the vehicle, sufficient torque and/or power is required for driving the vehicle as well as overcoming all the resistances (inertia, friction, . . . ) of the variable transmission. Furthermore, during vehicle braking operations, part of the energy released thereby is absorbed by the variable speed drive and only another part of this energy is recovered, then converted by the electric machine.
If a mechanical gearbox is used instead of the variable speed drive, it is essential to change the gear ratio in order to recover the braking energy. It is therefore necessary to disengage the motive axle, which causes a break in the motion transmission and an interruption of the braking energy recovery.
The present invention aims to overcome the aforementioned drawbacks by means of a simple drive system that requires no complicated control devices for the various uses of the system.
The invention therefore relates to a travel drive system for a hybrid vehicle comprising a thermal engine, notably an internal-combustion engine, with a shaft, at least one electric machine with a rotor supplied by batteries, a disengageable coupling between said shaft and said rotor, and a driven shaft driving the wheels of the vehicle, characterized in that it comprises a first transmission path for motion transmission between the shaft of the thermal engine and the driven shaft, and a second transmission path for motion transmission between the rotor and said driven shaft.
At least one of the paths can comprise a variable gear transmission.
The transmission can comprise a variable gear transmission.
The continuously variable gear transmission can comprise two pairs of variable spacing pulleys connected by a belt.
Alternatively, the variable gear transmission can comprise a gear box.
At least one of the paths can comprise a fixed gear transmission.
The fixed gear transmission can comprise two pulleys connected by a belt.
The system can comprise a disengageable coupling between the rotor of the electric machine and the second transmission path.
The system can comprise a coupling between the first transmission path and the engine shaft.
The system can comprise at least one coupling between the driven shaft and the first transmission path.
The coupling can comprise a centrifugal coupling.
The coupling can comprise a one-directional coupling.
The coupling can comprise a disengageable coupling.
The system can comprise an additional electric machine driven by the engine.
The invention also relates to a method intended for travel drive of a hybrid vehicle comprising a thermal engine, notably an internal-combustion engine, with a shaft, at least one electric machine with a rotor supplied by batteries, a disengageable coupling between said shaft and said rotor, and a driven shaft driving the wheels of the vehicle characterized in that it consists in connecting the driven shaft by a first motion transmission path to the shaft of the thermal engine and/or by a second motion transmission path to the rotor of the electric machine.
The method can consist, for starting the thermal engine, in supplying the electric machine by means of the batteries so as to operate it as an electric starter and in connecting the rotor of this machine to the engine shaft through the coupling.
The method can consist, jointly with the operation of the thermal engine and drive of the driven shaft by the first transmission path, in charging the batteries through actuation of the electric machine via the coupling between the engine shaft and the machine rotor.
The method can consist, jointly with the operation of the thermal engine and drive of the driven shaft by the first transmission path, in driving said driven shaft by means of the electric machine by connecting the rotor thereof to the engine shaft.
The method can consist, jointly with the operation of the thermal engine and drive of the driven shaft by the first transmission path, in driving said driven shaft by means of the electric machine through the agency of the second transmission path.
The method can consist, jointly with the operation of the thermal engine and drive of the driven shaft by the second transmission path, in driving said driven shaft by means of the thermal engine by connecting the shaft thereof to the rotor through the coupling.
The method can consist, during deceleration phases of the vehicle, in recovering the mechanical energy of the driven shaft in order to transmit it to the rotor of the electric machine by connecting said rotor to the second transmission path through the coupling.
The method can consist, during deceleration phases of the vehicle, in recovering the mechanical energy of the driven shaft in order to transmit it to the rotor of the electric machine by connecting said rotor to the second transmission path through the coupling and to transmit it to the engine shaft by making the coupling between the rotor and the shaft operational.
Other features and advantages of the invention will be clear from reading the description hereafter, given by way of non limitative example, with reference to the accompanying figures wherein:
As illustrated in
Shaft 12 of thermal engine 10 and rotor 16 of electric machine 14 are connected to one another by a disengageable coupling 22. This coupling comprises a housing 24 fixedly carried in rotation and in translation by the end of rotor 16 with respect to this rotor. This coupling also comprises a coupling disc 26 arranged in the housing while being fixedly carried in rotation by the end of shaft 12 and freely in axial translation on this shaft. The coupling also comprises pressure means 28 arranged in housing 24, allowing to provide coupling between the disc and the housing, thus enabling simultaneous rotation of the rotor and of the shaft. By way of example, these pressure means comprise a pressure plate 30 subjected to the action of elastic means, generally in form of Belleville washers or coil springs.
Shaft 12 also carries, between coupling 22 and thermal engine 10, an element 34 of a first motion transmission path 36, preferably of variable gear, while rotor 16 carries, between coupling 22 and electric machine 14, an element 38 of a second motion transmission path 40, advantageously of fixed gear.
These two transmission paths, preferably arranged parallel to one another, are provided to control, separately or simultaneously, a driven shaft 42 advantageously arranged parallel to the shaft and to the rotor. This driven shaft is connected to a motive axle, directly or by means of a transmission, like a differential bridge, allowing the driving wheels of the engine (not shown) to be driven.
These motion transmission paths allow any rotating motion of the rotor and/or of the shaft, as well as any torque and/or power generated by this shaft and/or this rotor to be transmitted to the driven shaft.
The first variable gear transmission path, with a continuously variable gear here, comes in form of a speed variator with variable pulleys. This variator generally consists of two pairs of opposite conical discs driven by a trapezoidal belt. The first pair of opposite conical discs comprises a conical disc 44 carried fixedly in rotation and in translation on shaft 12 and another disc 46 that is mobile while being mounted fixed in rotation but free in translation on this shaft. Means 48 for controlling the translational displacement of conical disc 46 are provided so as to allow control of the spacing between these two conical discs. Advantageously, as it is widely known, these means are centrifugal means with weights 50 that rest, on the one hand, on a flange 52, fixed in translation and in rotation, carried by shaft 12 while being substantially perpendicular to this shaft and, on the other hand, on the outer face of mobile conical disc 46.
Driven shaft 42 carries the second pair of opposite conical discs 54, 56 arranged opposite the first pair of discs 44, 46. Conical disc 54 facing conical disc 46 is fixedly mounted on a sleeve 58 coaxial to driven shaft 42, this sleeve being free in rotation with respect to this shaft but fixed in translation with respect thereto. The other conical disc 56 opposite conical disc 44 is fixed in rotation with respect to disc 54 but mobile in translation on sleeve 58 under the action of elastic means 60. These elastic means come here in the form of a spring 62 resting on the outer face of conical disc 56 and on a plate 64 orthogonal to sleeve 58.
The two pairs of conical discs are kinetically connected to one another by a trapezoidal belt 66 or by any other equivalent means.
Thus, any variation in the spacing of the discs at the level of the first pair of conical discs 44, 46 under the effect of control means 48 is translated into a variation in the spacing of conical discs 54, 56 under the combined effect of the elastic means and of the translational displacement of belt 66 in an orthogonal direction to shafts 12 and 42. Driven shaft 42 therefore undergoes a speed variation that depends on the spacing of the conical discs.
The other transmission path, preferably of fixed gear, comprises a pulley 68, preferably notched, mounted loose on rotor 16 but that can be connected in rotation to this rotor under the effect of a disengageable coupling 70. The pulley is therefore arranged between housing 24 of coupling 22 and pressure means 72 carried by a flange 74 fixedly connected to shaft 16.
Pressure means 72 are advantageously similar to those described above with a pressure plate 76 and elastic means 78. This second transmission path also comprises another pulley 80, also preferably notched, which is fixedly mounted on driven shaft 42. A motion transmission means 82 such as a preferably notched belt allows the rotating motion of one of the pulleys to be transmitted to the other one.
A coupling 84, preferably centrifugal, controlled by a one-directional coupling 86 such as a free wheel, is housed between fixed pulley 80 and the pair of conical discs 54, 56 arranged on driven shaft 42.
As it is known per se, free wheel 86 comprises an inner ring 88 connected to sleeve 58, rollers 90 (or balls) resting on the inner ring and on an outer ring 92 connected to an axial collar 94.
Centrifugal coupling 84 is arranged between collar 94 and a fixed axial drum 96 carried by fixed pulley 80. By way of example, this coupling carries a multiplicity of articulated radial arms 98 on the collar at pins 100. These arms carry friction pads 102 subjected to the action of return springs 104 and they allow to achieve a clutch coupling between this drum and this collar under the centrifugal effect provided by the rotation of the collar and/or the drum.
Pressure means 28 and 72 of couplings 22 and 70 described above are controlled under the action of control means 106, 108 respectively, such as swivelling levers subjected to the action of a jack (not shown).
A calculator 110 allows control means 106, 108 to be controlled by means of control lines 112 so as to actuate the operating mode of the drive system. This calculator also allows to control the operation of engine 10 and/or of electric machine 14 through lines 114 and it comprises mappings or data charts allowing, mainly according to the driver's requirements, to start either electric machine 14 or engine 10, or both.
The operation of the system is now described in connection with the various configurations illustrated in
In this table, reference numbers 22, 70, 84 and 86 relate to the various couplings already described, reference numbers 36 and 40 to the transmission paths, reference numbers 10 and 14 to the thermal engine and to the electric machine respectively, and reference number 42 to the driven shaft. Values 0 or 1 represent the coupled or uncoupled state of couplings 22, 70 and 84, the free wheel or driving wheel state for one-directional coupling 86, the non-motive or motive transmission state of the transmission paths (with an additional value 2 for a receiving transmission state in the case of engine braking and a value 3 for a state of transmission in motion without power transmission), and the inactive or active state of engine 10, electric machine 14 and driven shaft 42.
One-directional coupling 86 is in the driving wheel state (value 1) when the rotating speed of sleeve 58 (Nf) is higher than the rotating speed of fixed pulley 80 (Np). Similarly, centrifugal coupling 84 is in an active position when one-directional coupling 86 is in the driving wheel state and when the rotating speed of the sleeve (NO is higher than a threshold value (Ne).
During this start-up stage, the rotating motion of shaft 12 is transmitted to the second pair of conical discs 54, 56 via the first pair of discs 44, 46 and belt 66. This rotating motion is then transmitted to sleeve 58 and to free wheel 86 that will be in a driving wheel configuration by providing the link between this sleeve and collar 94. Since the rotating speed at the level of this collar is below the threshold value Ne, the centrifugal coupling with drum 96 is not achieved and fixed pulley 80 connected to this drum is not driven into rotation. Neither driven shaft 42 nor belt 82 is therefore driven into rotation.
After engine start-up, control means 20 of electric machine 14 are controlled by the calculator to stop supply thereof so that rotor 16 is driven by shaft 12 if pressure means 28 remain actuated. Under the effect of this rotation, machine 14 can run as an electric energy generator and the electric power delivered thereby is used to supply batteries 18.
Calculator 110 therefore controls means 106, 108 in such a way that couplings 70 and 22 are operational, and means 20 for supplying the electric machine through batteries 18 so as to drive it into rotation. Coupling 22 thus allows to connect rotor 16 of electric machine 14 to shaft 12 of the thermal engine. Under the action of the rotation of rotor 16, shaft 12 is driven into rotation until engine 10 is started. As soon as this engine starts, couplings 22 and 70 remain operational and supply of machine 14 is stopped.
During the start-up phase and thereafter, continuity of the vehicle motion is provided by the fact that second transmission path 40 remains constantly active. In fact, coupling 70 allows to connect in rotation loose pulley 68 with rotor 16 that is either driving for engine start-up or driven after this start-up phase. The rotating motion of this pulley is transmitted by belt 82 to fixed pulley 80 that is fixedly connected to driven shaft 42 by driving it into rotation.
As described above in connection with
Another situation consists, after start-up of the thermal engine, in releasing coupling 22 while maintaining traction of the vehicle by the electric motor. The thermal engine can then rev up until centrifugal coupling 84 is operational. The motion is then transmitted to the vehicle by first transmission path 36.
Similarly, after start-up of engine 10, the calculator controls means 20 of electric machine 14 in such a way that it runs as an electric energy generator driven by shaft 12 for supplying batteries 18 or the vehicle accessories if need be.
Thus, in the configuration of
For operation of the vehicle in electric traction (in forward or in reverse gear) as illustrated in
Since coupling 22 is not operational, engine 10 may or may not be running, without the vehicle drive being disturbed thereby and without free wheel 86 being motive.
In this case, none of the two couplings 22 or 70 is operational and operation of thermal engine 10 causes rotation of shaft 12.
Under the effect of this rotation, the first pair of conical discs 44, 46 is driven into rotation, a rotation that is transmitted to the second pair of discs 54, 56 and to sleeve 58 by belt 66. Since the speed of the sleeve is higher than that of fixed pulley 80 (pulley in off position), free wheel 86 is motive and drives collar 94 into rotation. Under the effect of the rotating speed and of the centrifugal force, pads 102 of centrifugal coupling 84 come into contact with the inside of drum 96 while driving it, and consequently driven shaft 42, into rotation.
The rotation of fixed pulley 80 has no effect on rotor 16 since coupling 70 is not active and pulley 68 can freely rotate on this rotor under the action of belt 82.
In the case of
Simultaneously, the rotating motion of shaft 12 is transmitted by first transmission path 36 (first pair of discs 44, 46, belt 66, second pair of discs 54, 56) to sleeve 58. Since the speed of sleeve 58 (Nf) is sufficient to make free wheel 86 motive, the latter drives collar 94 into rotation. Under the effect of this rotation, coupling 84 is operational by thus securing in rotation drum 96 and fixed pulley 80 to sleeve 58. In this position, since the drum is fixedly connected to driven shaft 42, the latter is driven into rotation and consequently provides, directly or indirectly, displacement of the vehicle.
The rotation of fixed pulley 80 has no effect on rotor 16 since coupling 70 is not active and pulley 68 can freely rotate on this rotor under the action of belt 82.
In this case, calculator 110 controls engine 10 through line 114 and control means 106 and 108 through lines 12 in such a way that the internal-combustion engine is operational and couplings 22 and 70 are active by securing, on the one hand, shaft 12 to rotor 16 and, on the other hand, rotor 16 to pulley 68.
Thus, the engine drives into rotation shaft 12 that in turn drives rotor 16 at the same rotating speed by means of coupling 22. The rotation of the rotor thus allows to provide charging of batteries 18 by means of electric machine 14 that works as an electric energy generator.
Furthermore, the rotation of this rotor is transmitted to driven shaft 42 by the second transmission path (pulley 68, belt 82, fixed pulley 80) and it thus allows this driven shaft to be driven into rotation.
The rotation of shaft 12 is transmitted, via belt 66, from the first pair of conical discs 44, 46 to the second pair of discs 54, 56 connected to sleeve 58. Since the speed of fixed pulley 80 (Np) is higher than that of the sleeve (Nf), free wheel 86 is not operational. No motion transmission therefore occurs between transmission path 36 and driven shaft 42.
In the case of
Calculator 110 therefore controls engine 10 through line 114 and control means 106 and 108 through lines 112 in such a way that the internal-combustion engine is operational and coupling 70 is active by securing pulley 68 to rotor 16 while coupling 22 is inactive by separating this rotor from shaft 12.
The rotating motion of shaft 12 is transmitted by the first pair of conical discs 44, 46 and belt 66 to the second pair of discs 54, 56 and sleeve 58. The speed of sleeve 58 is such that free wheel 86 becomes motive and drives into rotation collar 94. Under the effect of this rotation, centrifugal coupling 84 is operational and allows to secure in rotation drum 96 and fixed pulley 80 to the collar and, consequently, to sleeve 58. Since the drum is fixedly connected to driven shaft 42, the latter is driven into rotation and thus provides direct or indirect displacement of the vehicle.
Furthermore, fixed pulley 80 drives into rotation, by means of belt 82, pulley 68 that has been secured in rotation to rotor 16. Under the action of the rotation of this pulley 68, rotor 16 is driven into rotation and thus allows to provide charging of batteries 18 by means of electric machine 14 that works as an electric energy generator.
The configurations illustrated by
Thus, in the configuration of
The power of electric motor 14 is therefore transmitted from rotor 16 to shaft 12 of the thermal engine via coupling 22. This power adds to the power transmitted to this shaft by the thermal engine and the resulting power is transferred through first transmission path 36 (conical discs 44 and 46, belt 66, conical discs 54 and 56) to driven shaft 42 via sleeve 58, free wheel 86, collar 94, centrifugal coupling 84, drum 96 and fixed pulley 80 connected to this driven shaft.
As already described in connection with
For the configuration of
The power generated by thermal engine 10 is transmitted to shaft 12 and it is in turn transmitted to rotor 16 through coupling 22. This power is combined with that of electric motor 14 through its rotor 16. Since coupling 70 is active, the combination of these powers is then transferred to driven shaft 42 by second transmission path 40 (pulley 68, belt 82 and fixed pulley 80).
Since free wheel 86 is not motive, on the one hand, the rotating motion of fixed pulley 80 cannot be transmitted to sleeve 58 and, on the other hand, the rotating motion of shaft 12 transferred by first transmission path 36 to sleeve 58 cannot be transmitted to this fixed pulley.
According to the configuration of
In this configuration, the power generated by electric motor 14 is transmitted from rotor 16 to driven shaft 42 by second transmission path 40 (pulley 68, belt 82 and fixed pulley 80), by means of coupling 70. Simultaneously, the power of the thermal engine is transferred from shaft 12 to driven shaft 42 by first transmission path 36 (conical discs 44 and 46, belt 66, conical discs 54 and 56) through free wheel 86, collar 94, centrifugal coupling 84, drum 96 and fixed pulley 80), coupling 22 being inactive.
The configuration of
Therefore, from a configuration where the vehicle is driven either by thermal engine 10 or by electric machine 14, or by both 10 and 14, calculator 110 controls, during deceleration phases of the vehicle, coupling 70 in active position and coupling 22 in inactive position. This calculator also controls the thermal engine, if it is running, so as to idle or to stop it. The rotating speed of shaft 12 transmitted to sleeve 58 by first path 36 is therefore not sufficient to make free wheel 86 motive.
In order to recover this deceleration energy and to convert it to electric energy, the calculator controls machine 14 so that it works as an electric energy generator for charging batteries 18.
Thus, during the deceleration phases, the driving wheels of the vehicle generate a rotating motion that is directly or indirectly transmitted to driven shaft 42. This rotating motion is then transmitted to rotor 16 by second transmission path 40 via fixed pulley 80, belt 82 and pulley 68, coupling 70 being active. The rotation of rotor 16 allows, under control of the calculator and of control means 20, to operate machine 14 as a mechanical energy receiving machine, which mechanical energy will be converted, as with an electric generator, to electric energy in order to be used or stored in batteries 18.
In the configuration of
Coupling 22 is therefore active in addition to the activation of coupling 70 as initially shown in
Thus, during vehicle deceleration periods, the rotating motion of driven shaft 42 is transmitted to rotor 16 via second transmission path 40. Coupling 22 being active, this rotating motion is also transmitted to shaft 12 that generates a resistant torque on the thermal engine and therefore engine braking.
It can be noted that, in cases where batteries 18 are fully charged, calculator 110 controls machine 14 so as to make it electrically inactive. This allows engine braking to be improved even further.
As for
In this case, the energy generated by the deceleration of the vehicle is transmitted to rotor 16, as described in connection with
As illustrated in
The operation of this variant is globally identical to that described in connection with
In the variant of
Collar 94 therefore carries a coupling disc 138 fixed in rotation with this collar and preferably free in axial translation on this collar. The drum fixedly carries a reaction plate 140 and pressure means 142 also carried by the drum and allowing to provide coupling between disc 138 and this plate 140. The pressure means comprise for example a support plate 144 subjected to the action of spring means 146.
As already mentioned in connection with the disengageable couplings of
The operation of this variant is also identical to that of
As for the variant of
The free wheel is therefore directly connected to the fixed pulley by a flat ring 148 fixedly connecting its outer ring 92 to pulley 80.
This layout is particularly advantageous when thermal engine 10 is intended to be systematically stopped when the vehicle is stationary. In order to move the vehicle from its stationary position, machine 14 is used as the electric driving motor. This machine 14 can also be used as a starter for thermal engine 10 by making coupling 22 operational. Once the thermal engine started, its power is transmitted to fixed pulley 80 via first transmission path 36 or sleeve 58 and free wheel 86 (couplings 22 and 70 being inactive).
In the variant of
Disc 138 is therefore fixedly mounted in rotation and preferably free in translation on sleeve 58.
This layout affords the advantage of providing an additional energy recovery path during vehicle deceleration phases. Furthermore, transmission path 36 can allow to achieve engine braking on the thermal engine in a wider engine speed range.
In
Collar 94 carrying coupling 84 is thus fixedly connected directly to sleeve 58 through a flank 150.
This layout allows to use first transmission path 36 as an engine brake for thermal engine 10 and/or electric motor 14.
For the variant of
This generator can be connected to control means 20 or comprise specific control means (not shown) controlled by the calculator so as to provide charging of the batteries, drive of the vehicle alone or in combination with the thermal engine, or start-up of this thermal engine.
This allows to obtain series hybrid operation if the speed of thermal engine 10 does not allow coupling 84 to be made operational.
This layout furthermore allows not to be limited as regards the continuous operating time of the vehicle in reverse gear since thermal engine 10 can allow to charge batteries 18 while, simultaneously, these batteries supply energy to electric machine 14 for reversing.
In the example of the variant illustrated in
The additional coupling comprises a housing 156 carried, fixedly in rotation and in translation, by the free end of first part 12A of the shaft and a coupling disc 158 arranged in the housing while being carried, fixedly in rotation and freely in axial translation, by one end of second part 12B of the shaft, the other end of this shaft carrying coupling disc 26 of coupling 22, as already described in connection with
This affords the advantage of neutralizing transmission path 36 by disengaging coupling 154 or of setting, between part 12B of shaft 12 and driven shaft 42, any other speed variation means, such as a discontinuous variation means, a gear box for example. Thus, changing these gears (manually or automatically) will be conventionally done by disengaging coupling 154.
As for the other variants, the operating mode of the variants of
The present invention is not limited to the example described above and it encompasses any variant or equivalent.
Similarly, the thermal engine mentioned in the above description covers internal-combustion engines running on fossil fuels such as gasoline, diesel fuel or gas, as well as biofuels of ethanol type or others.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0707118 | Oct 2007 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR08/01399 | 10/7/2008 | WO | 00 | 6/21/2010 |
