WO2011036394A1 - Device for synchronising and rigidly connecting the input shafts of a dual-clutch gearbox - Google Patents

Abstract

The invention relates to a semi-automatic gearbox (10) for an automobile, including two clutches, first and second input shafts (11, 12) and first and second output shafts (13, 14), each input shaft (11, 12) being connected to a respective clutch, each input shaft having sprockets suitable for meshing with pinions supported by either one of the output shafts (13, 14), such that the first input shaft (11) is suitable for meshing with the pinions of odd-numbered gear ratios and the second input shaft (12) is suitable for meshing with the pinions of even-numbered gear ratios, characterised in that the gearbox includes a coupling device (15) suitable for equalising the respective speeds of rotation when shifting ratios.

Description

 DEVICE FOR SYNCHRONIZING AND SOLIDARIZING PRIMARY SHAFTS OF A DOUBLE GEARBOX

 CLUTCH

The present invention relates to a dual-clutch gearbox, particularly for a motor vehicle.

 To vary the gear ratio between the output shaft of the engine and the wheels of a vehicle, a gearbox with several ratios, associated with a clutch, is usually used. It is advantageous, in particular in the case of an automatic control gearbox, to use two clutches, one controlling the odd ratios, the other the even ratios, in order to allow a continuous transition from a gear to the other. 'other.

 In known manner, for example from EP 1 589 257, a double clutch box comprises two primary shafts, the first associated with the odd-speed gears and with the reverse gear, the second with the even gear ratios, these two primary shafts being associated respectively with a first and a second friction clutch, a first and a second secondary shaft. The first primary shaft, solid, and the second primary shaft, hollow, are mounted coaxial. Such an architecture makes it possible to carry out torque shifts by selectively actuating one or other of the clutches associated with one or the other of the primary shafts. This avoids a well-known disadvantage of gearboxes with a single clutch: the phenomenon of breaking torque during a shift of gear ratio.

Indeed, such a split architecture makes it possible to have two transmission subassemblies (including each clutch, primary shaft and secondary shaft) independent, each subassembly respectively ensuring the transmission of gear ratios of even and odd degree. Thus, when a report is engaged on one of the two subsets, for example the one managing the even relations, it is possible that the second subset is already engaged on the odd relation which must a priori follow, that is. that is, the odd ratio sensed as desired by the driver after gearshift. The shift strategy relies on the interpretation of the driver's will: for example, in case of strong acceleration on the second gear, the non-subset will be predisposed. engaged on the third gear and, conversely, in the event of deceleration, on the first gear.

 FIG. 1 shows a diagram of a known box comprising a first and a second primary shaft, respectively Ap1 and Ap2, a first and a second primary shaft, respectively As1 and As2, as well as the gears of six forward gears (numbered 1 to 6), and a reverse pinion Mar. The first primary shaft Ap1 is adapted to drive the gears corresponding to odd reports 1, 3, 5, while the second primary shaft Ap2 is adapted to drive the pinions corresponding to the even reports 2, 4, 6 and that of reverse Mar.

 When a vehicle equipped with such a box is propelled on the second gear, and the prediction of the next gear change provides for a passage on the third gear, then the subset of the odd gear must move from gear 1 to gear the report 3 to preposition this subset on the report 3. However, if this passage is made late vis-à-vis the engine revving, there may be a problem of synchronization: the energy to be dissipated by the synchronizer associated with the ratio 3 may be too large, because the speed difference to be absorbed by this synchronizer will be very important.

 Indeed, when the ratio 2 is engaged, the second primary shaft

Ap2 drives the second secondary shaft As2 through the second gear. The ratio pinion 1, integral with the second secondary shaft As2 drives the first primary shaft Ap1. For example, if the engine speed is 6000 rpm on the ratio 2, the speed of the input shaft can reach (depending on the gear ratio 1) nearly 10,000 rpm.

 A numerical example is given below, assuming that the two secondary trees have the same reduction ratio and lasl = ûapl Kl

 "Coas2x K3

 (Opr3 =

 Kl

 ήωαρΐ = 6000ir / min_ Kl = 0.2857 K2 = 0.4792 and that K3 = 0.7447 then (Oasl = 2872ir / min

 (ûpr3 = 7586ir / min

that the first report remains committed until the passage of report 2 to the report With:

m ^s ^: speed of the second secondary shaft As2

m ^p2 : speed of the second primary shaft Ap2

^close to gear ratio gear 3

 ^ 1: report of multiplication of the first report

K2 _: second report multiplication report

 : gear ratio of the third gear When the "odd" subassembly is to be passed, the difference in speed between the first input shaft and the gear ratio 3 is therefore 7586 - 2872 = 4714 tr / min. As recalled above, it is this difference in speed which must be absorbed by the synchronizer of the gear ratio 3.

 As shown above, the energy to be dissipated by the synchronizers during shifts is very important and there is great interest in minimizing this energy. Indeed, it allows to use synchronizers smaller dimensions, with all the associated gains (including: cost, space, heat and less wear). It is the objective of the present invention to provide a solution that drastically limits the differences in speed between the parts to be synchronized, and therefore the energy to be dissipated.

 Thus, the invention relates to a mechanical gearbox for a motor vehicle, comprising two clutches, a first and a second primary shaft, a first and a second secondary shaft, each primary shaft being associated with a respective clutch, each primary shaft carrying gear wheels. adapted to mesh with pinions carried by one or the other of the secondary shafts so that the first primary shaft is able to mesh with the gears corresponding to the odd-degree velocity ratios and the second primary shaft is adapted to meshing with the gears corresponding to gear ratios of even degree, characterized in that the gearbox comprises a coupling device to equalize their respective speeds of rotation during a gear change.

In one embodiment, the first and second primary shafts are coaxial mounted, the first primary shaft being solid and bearing in the second primary shaft which is hollow, the coupling device being disposed between the first and second primary shafts. In one embodiment, the coupling device is a synchronization and interconnection device;

 In one embodiment, the coupling device is a clutch, in particular a wet type clutch.

 In one embodiment, the coupling device is activated by means of an actuator, in particular by means of a sliding sleeve.

 In one embodiment, the gearbox according to the invention comprises five or six or forward gears and a reverse gear.

 The invention also relates to a motor vehicle provided with a gearbox according to one of the preceding claims.

 The invention will be better understood on reading the detailed description which follows, description made with reference to the appended figures, figures among which:

 FIG. 1, already described, represents the architecture of a known gearbox;

 FIG. 2 represents a simplified diagram of a gearbox according to the invention

 - Figure 3 shows a possible embodiment of the synchronization system of the primary shafts according to the invention.

Figure 2 shows a simplified diagram of a gearbox for a motor vehicle according to the invention. The gearbox 1 0 comprises a first and a second primary shaft, respectively 1 1 and 1 2. In known manner, the two primary shafts are each connected to the motor shaft of the vehicle via a respective clutch ( not shown). The two primary shafts 1 1, 1 2 are coaxial, the first primary shaft 1 1 being solid and disposed inside the second primary shaft 1 2, the latter being hollow. The gearbox 1 0 also comprises a first and a second secondary shaft, respectively 1 3 and 14, disposed on either side of the entire axis of rotation of the primary shafts. Transmission gears are distributed on these two secondary shafts 1 3, 14, and are arranged so that the gears corresponding to the odd ratios of the gearbox (first, third and fifth gear) are able to be driven by the first input shaft ( via gear wheels integral in rotation with the latter), and that the gears corresponding to the even gear ratio of the gearbox and to the reverse gear ratio are able to be driven by the second main shaft (via gear wheels integral with it). The architecture described above is known in itself and moreover analogous to that described in FIG. 1 which represents the state of the art of the present invention.

 The invention differs from the state of the art essentially by the presence of a synchronization and coupling device 15 allowing the progressive coupling of the two primary shafts January 1, 12, after equalizing their respective rotational speed. In the example of Figure 3, this device 15 is disposed between the two primary shafts. It may be for example a synchronization and interconnection assembly, a wet clutch, or any device for synchronizing and coupling two rotating parts.

 If we take again the numerical example given previously for a passage of the second report towards the third report, we have, for a gearbox according to the invention, a major difference: unlike the box of FIG. primary tree is here without a committed relation, therefore to the "neutral". The equations for determining the speed deviation to be absorbed by the third gear synchronizer are then written as follows:

 Cûapl = Cûapl _on _ will call _ so _ (ùap

 CûasT. = xip x K2

 ûpr = Cûap x K3

 if ωαρ = 6000ir / min_K2 = 0.4792 and that K3 = 0.7447 then Cûasl = 2872ir / min

It can thus be seen that with a gearbox according to the invention the difference in speed between the first primary shaft and the gear ratio 3 is 4468-2872 = 1596 rpm. The example given shows the significant gain that the invention allows: in the case of a shift from the second gear to the third gear, the synchronizer of the third gear will have to compensate for a rpm deviation of 1596 rpm instead of 4714 rpm. / min for a gearbox with two clutches of known type (almost three times less), which is therefore much less energy to dissipate by the same synchronizer. The order of magnitude of this energy corresponds approximately to the energy that must dissipate a synchronizer of a conventional controlled gearbox, that is to say a simple clutch. Figure 3 shows a possible embodiment of the device 15 according to the invention. FIG. 3 is a detail of FIG. 2, in which is shown a portion of the first and second primary shafts 1 1, 1 2, each bearing a gear wheel, respectively 1 10 and 120 (the other gear wheels carried by the primary shafts are not visible in Figure 3). The device 15 is in the example of Figure 3 a conventional synchronizer. It comprises two synchronizing rings 151, 152 respectively associated with the toothed wheels 1 10; 120, and a synchronization hub 153. In known manner, the synchronizer is implemented by means of a synchronizing sleeve 154 which is able to be moved by an actuator, in a known manner.

 The invention therefore makes it possible to guarantee much less stress on the synchronizers than in a known double-clutch gearbox, typically of the same level as a conventional controlled gearbox (with a single clutch). The invention also makes it possible to control more precisely the control of the synchronizers, by having a perfect control of the speed of the primary shaft, the latter being disengaged before a gear change. Finally, the invention also has the significant advantage of equalizing the speeds of the two primary shafts, thus eliminating the friction between these two shafts and contributing to a reduction of the vehicle's consumption by reducing the internal friction in the system. of transmission.

Claims

1. Mechanical gearbox (10) for a motor vehicle, comprising two clutches, a first and a second primary shaft (1 1, 12), a first and a second secondary shaft (13, 14), each primary shaft (1 1, 12). ) being associated with a respective clutch, each primary shaft carrying gear wheels adapted to mesh with pinions carried by one or the other of the secondary shafts (13, 14, such that the first primary shaft (1 1) is able to mesh with the gears corresponding to the odd-degree speed ratios and that the second primary shaft (12) is able to mesh with the gears corresponding to the gear ratios of even degree, characterized in that the gearbox comprises a gearbox synchronization device and interconnection (15) to equalize their respective rotational speeds during a gear change.  2. Gearbox (10) mechanical according to claim 1, wherein the first and second primary shafts (1 1, 12) are mounted coaxial, the first primary shaft (1 1) being full and carrying the second primary shaft (12). ) which is hollow, the coupling device (1 5) being arranged between the first and second primary shafts.  3. Gearbox (10) mechanical according to one of claims 1 and 2, wherein the synchronization device and clutch (15) is activated by means of an actuator, in particular via a sliding sleeve (154).  4. Transmission (10) mechanical according to one of the preceding claims, comprising 5 or 6 forward gears and a reverse gear.  5. Motor vehicle with a gearbox (10) according to one of the preceding claims.