CVT DRIVE TRAIN

Abstract

A CVT drive train including an input drive, a torque converter is downstream from the input drive in a power flow direction and contained within a torque converter housing, the torque converter serving as a starting element. A disconnect clutch is contained within the torque converter housing along with a converter bridging clutch. A continuously variable variator is operatively connected to and arranged downstream from the torque converter, and a rotation reversing device is downstream of the variator to enable a shift between a neutral position of the drive train and one of a forward driving position and a reverse driving position.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a CVT drive train having an input drive, a torque converter as a starting element, a disconnect clutch, a rotation reversing device, and a continuously variable variator. In addition, the invention relates to a method for operating such a CVT drive train.

A CVT drive train of this type is known from U.S. Pat. No. 4,817,458. In the known CVT drive train, the disconnect clutch is positioned between the torque converter and the rotation reversing device on the input side of the continuously variable variator. The term CVT refers to a stepless transmission; the letters CVT stand for continuously variable transmission.

An object of the present invention is to improve a drive train having an input drive, a torque converter as a starting element, a disconnect clutch, a rotation reversing device, and a continuously variable variator, in particular with regard to the required construction space.

SUMMARY OF THE INVENTION

The object is fulfilled with a CVT drive train having an input drive, a torque converter as a starting element, a disconnect clutch, a rotation reversing device, and a continuously variable variator, characterized in that the disconnect clutch is integrated into the torque converter. That makes it possible, in a simple way, on the one hand to uncouple from the rotation reversing device a torque provided by means of the torque converter prior to a switchover. On the other hand, because of the integration of the disconnect clutch in the torque converter, no construction space is needed for the disconnect clutch between the torque converter and the continuously variable variator in the CVT drive train according to the present invention. An additional separate clutch outside of the torque converter can therefore be completely eliminated.

A preferred exemplary embodiment of the present CVT drive train is characterized in that the disconnect clutch in the torque converter is operable with slip. That enables the driving dynamics of a motor vehicle equipped with the CVT drive train to be improved in certain driving situations by a brief, calculated increase in engine speed.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that the torque converter is designed as a multi-function converter, which contains a converter bridging clutch in addition to the disconnect clutch. The converter bridging clutch serves beneficially, in particular, to block or bridge the torque converter, for example after a driving-off procedure. The converter bridging clutch is also known as a lockup clutch.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that the converter bridging clutch is combined within the torque converter with the disconnect clutch. The converter bridging clutch is preferably positioned between a turbine and an impeller of the torque converter. The disconnect clutch is preferably positioned between the impeller and a housing of the torque converter. The two clutches are preferably designed as friction clutches having friction linings. Among other things, that provides the advantage that both clutches can be operated with slip.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that the rotation reversing device is implemented as a reversing gear with a claw clutch, which makes it possible to shift between a neutral position N, a forward driving position D, and a reverse driving position R. To shift among the various positions of the rotation reversing device, the latter is decoupled from the input drive with the help of the disconnect clutch that is integrated into the torque converter.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that the rotation reversing device includes a synchronizing device. Uncoupling the torque converter from the rotation reversing device simplifies the synchronization prior to switching over the rotation reversing device.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that the rotation reversing device is located on an output side of the variator, between a variator output and a differential. The rotation reversing device is positioned, for example, on an output shaft of the continuously variable variator. The rotation reversal is preferably carried out with an additional shaft.

Another preferred exemplary embodiment of the present CVT drive train is characterized in that a torque sensor is positioned at least partially in an intermediate space between the torque converter and the input side of the variator. In the previously known CVT drive train described earlier, the disconnect clutch is positioned in the intermediate space between the torque converter and the input side of the variator. By integrating the disconnect clutch into the torque converter, the intermediate space can be used advantageously, either entirely or partially, to accommodate the torque sensor.

In addition, the present invention relates to a method for operating a previously described CVT drive train. During operation of the CVT drive train, the disconnect clutch integrated into the torque converter serves advantageously to uncouple the rotation reversing device from the input drive prior to switching over. That decouples a converter torque which impedes or prevents synchronization.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages, features, and details of the invention can be seen from the following description, in which various exemplary embodiments are described in detail with reference to the drawings. The drawing figures show the following:

FIG. 1 shows a simplified representation of a CVT drive train according to the present invention in a longitudinal cross-sectional view;

FIG. 2 shows the CVT drive train of FIG. 1 in a transverse cross-sectional view; and

FIG. 3 shows an exemplary embodiment of a CVT drive train according to the present invention in a longitudinal cross-sectional view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 3 show a CVT drive train 1; 41 according to the present invention having a CVT transmission. The CVT drive train 1; 41 includes an input drive 3; 43. The input drive 3; 43 is, for example, a combustion machine, which is also referred to as an internal combustion engine when used in a motor vehicle. In FIGS. 1 and 3, only an input part 4; 44 of the input drive 3; 43 is visible, which is non-rotatably connected to a crankshaft of the internal combustion engine, for example by means of a flex plate.

Starting to drive a motor vehicle equipped with the CVT drive train 1; 41 is enabled by a starting element 5; 45. The starting element 5; 45 is implemented as a torque converter. A torque from the input drive 3 is transmitted through the torque converter 5; 45 to a variator input of the variator 10; 50.

The variator 10; 50 includes a conical disk set 11; 51 on the input side and a conical disk set 12; 52 on the output side. The two conical disk sets 11; 51 and 12; 52 are coupled with each other by an endless torque-transmitting means 13; 53. The endless torque-transmitting means 13; 53 is, for example, a special chain.

By means of the two conical disk sets 11; 51 and 12; 52, the transmission ratio between the input drive 3; 43 and an output drive 15; 55 can be adjusted continuously. The output drive 15; 55 includes at least one driven vehicle wheel (not shown).

Normally, the output drive 15; 55 includes at least two driven vehicle wheels. An equalizing transmission 16; 56, also referred to as a differential, serves to distribute the provided torque to the two driven vehicle wheels. The differential 16; 56 includes a spur gear 18; 58.

The torque converter 5; 45 includes a housing 20; 60. The housing 20; 60 of the torque converter 5; 45 is firmly connected to the input part 4; 44 of the CVT drive train 1; 41. Located in the housing 20; 60 of the torque converter 5; 45 are a turbine 21; 61, a diffuser 22; 62, and an impeller 23; 63. The construction and the function of a torque converter are disclosed, for example, in the international published unexamined application WO 2004/003400 A1.

A torsional vibration damping device 28; 68 is integrated into the torque converter 5; 45. The torsional vibration damping device 28; 68 is non-rotatably connected or connectible on the input side to the input part 4; 44. On the output side, the torsional vibration damping device 28; 68 is connected to an input shaft 29; 70 of the variator 10; 50. In FIG. 3 that connection is made by means of a flange 69, or to input shaft 70 of the variator 50 by means of the turbine 61.

Furthermore, a converter bridging clutch 31; 71 and a disconnect clutch 32; 72 are integrated into the torque converter 5; 45. The converter bridging clutch 31; 71 serves to block or bridge the torque converter 5; 45. The input part 4; 44 of the CVT drive train 1; 41 can be connected directly to the input shaft 30; 70 of the variator 10; 50 through the engaged converter bridging clutch 31; 71.

The disconnect clutch 32; 72 makes it possible to uncouple the input shaft 30; 70 of the variator 10; 50 from the input part 4; 44 of the CVT drive train 1; 41. That enables the torque converter 5; 45 to be uncoupled from the input drive 3; 43.

The variator 10; 50 has an output shaft 35; 75 on the output side. A rotation reversing device 36; 76 is operatively connected to the output shaft 35; 75 of the variator 10; 50.

The rotation reversing device 36; 76 includes a claw clutch 38; 78, which enables shifting between a neutral position N, a reverse driving position R, and a forward driving position D.

The rotation reversing device 36; 76 including the claw clutch 38; 78 is operatively connected with the differential 16; 56 between the output shaft 35; 75 of the variator 10; 50 by the spur gear 18; 58.

The circles shown in FIG. 2 make the construction of a CVT transmission clear. A circle 26 represents the gear 26; 66 shown in FIGS. 1 and 3, respectively. The center point of the circle 26 in FIG. 2 represents the center point of an input drive crankshaft.

In the CVT drive train 1 shown in FIG. 1 the converter bridging clutch 31 is positioned between the torsional vibration damping device 28 and the input part 4. The disconnect clutch 32 is positioned between the impeller 23 and the housing 20 of the torque converter 5.

In the CVT drive train 41 shown in FIG. 3, the converter bridging clutch 71 is combined with the disconnect clutch 72. The converter bridging clutch 71 is positioned between the turbine 61 and the impeller 63. The disconnect clutch 72 is positioned between the impeller 63 and the housing 60.

Furthermore, the variator 50 of the CVT drive train 41 in FIG. 3 is equipped with a torque sensor 80. The torque sensor 80 is positioned in an intermediate space between the input disk set 51 of variator 50 and the gear 66.

The gear 66 shown in FIG. 3, like the gear 26 in the CVT drive train 1 shown in FIG. 1, serves, for example, to drive a pump (not shown). The gear 26; 66 is therefore also referred to as a pump gear.

Claims

1. A CVT drive train comprising: an input drive;a torque converter as a starting element, wherein the torque converter is contained within a torque converter housing;a disconnect clutch;a rotation reversing device; anda continuously variable variator;wherein the disconnect clutch is included within the torque converter housing.

2. A CVT drive train according to claim 1, wherein the disconnect clutch within the torque converter housing is operable with slip.

3. A CVT drive train according to claim 1, wherein the torque converter is a multi-function torque converter and includes within the torque converter housing a bridging clutch in addition to the disconnect clutch.

4. A CVT drive train according to claim 3, wherein the disconnect clutch within the torque converter is operable with slip.

5. A CVT drive train according to claim 1, wherein the rotation reversing device is a reversing gear including a claw clutch for shifting between a neutral position N, a forward driving position D, and a reverse driving position R.

6. A CVT drive train according to claim 1, wherein the rotation reversing device includes a synchronization device.

7. A CVT transmission according to claim 1, wherein the rotation reversing device is located on an output side of the variator between a variator output and a differential.

8. A CVT transmission according to claim 1, including a torque sensor positioned in an intermediate space between the torque converter and the variator.

9. A method for operating a CVT drive train having the drive train components recited in claim 1, said method comprising the steps of: operating the disconnect clutch to uncouple the torque converter and the variator from the input drive;switching the rotation reversing device between a neutral position N, and one of a forward driving position D, and a reverse driving position R; andoperating the disconnect clutch to couple the torque converter and the variator to the input drive to enable a selected one of forward driving and reverse driving.

10. (canceled)