Method for determining clutch parameters of an automatic transmission having at least one clutch

Abstract

A method for determining transmission and/or clutch parameters of a motor vehicle automatic transmission having at least one clutch, in particular for basic calibration of the transmission, in particular an automated manual transmission and/or a dual-clutch transmission, includes determining drag torque and/or kiss point of the clutch using an actuable synchronization device. The clutch has at least one drive side connected to an internal combustion engine output shaft and at least one output side connected to a transmission input shaft. The transmission output and/or drive shaft is blocked. The drive side of the clutch is driven. Basic calibration of the transmission is improved by driving the drive side of the clutch by an electric motor, providing a freewheel-shifted gear stage, and driving the drive side of the clutch by the electric motor in a rotation direction opposite the internal combustion engine output shaft.

Claims

1. A method for determining at least one of transmission or clutch parameters of a motor vehicle automatic transmission having at least one clutch or an automated manual transmission or a dual clutch transmission, for basic calibration of the automatic transmission, the method comprising the following steps: determining at least one of a drag torque or a kiss point of the at least one clutch by using at least one actuable synchronization device; providing the at least one clutch with a drive side being actively connected to or configured to be actively connected to an internal combustion engine output shaft and providing the at least one clutch with an output side being actively connected to at least one transmission input shaft; blocking at least one of the internal combustion engine output shaft or the transmission input shaft; driving the drive side of the at least one clutch by using an electric motor; providing at least one freewheel-shifted gear stage; and driving the drive side of the at least one clutch in a direction of rotation of the electric motor being opposite to a direction of rotation of the internal combustion engine output shaft.

2. The method according to claim 1, which further comprises in a first step or at a first point in time, closing the at least one clutch with a specific clutch force or realizing a specific clutch torque, and then increasing the rotational speed of the transmission input shaft in terms of magnitude to the rotational speed of the drive side of the at least one clutch or the rotational speed of the transmission input shaft or at a second point in time substantially reaching the rotational speed of the drive side of the at least one clutch or while maintaining a minimum slip or a stationary differential rotational speed.

3. The method according to claim 2, which further comprises in a second step or at a third point in time, actuating the synchronization device or starting an ansynchronization process of a gear stage of the transmission by using the synchronization device and acting upon the synchronization device with a synchronization force increasing continuously.

4. The method according to claim 3, which further comprises at a specific determined first synchronization force or at a fourth point in time, breaking the rotational speed of the transmission input shaft away from the rotational speed of the drive side of the at least one clutch, resulting in the drag torque of the at least one clutch then being determined or calculated.

5. The method according to claim 4, which further comprises upon determination of a specific slip or a specific rotational speed difference between the transmission input shaft and the drive side of the at least one clutch or at a fifth point in time, determining and using or calling upon the specific second synchronization force when present to determine the kiss point of the at least one clutch or then determining the synchronization torque existing at the fifth point in time.

6. The method according to claim 5, which further comprises moving the synchronization device into a neutral position so that the rotational speed of the transmission input shaft in terms of magnitude approaches the rotational speed of the drive side of the at least one clutch or is brought substantially to the rotational speed of the drive side of the at least one clutch or substantially reaches the rotational speed of the drive side of the at least one clutch, at a sixth point in time.

7. The method according to claim 6, which further comprises closing the at least one clutch with a maximum clutch pressure or after the fifth point in time or after the sixth point in time, and the rotational speed of the transmission input shaft approaches the rotational speed of the drive side of the at least one clutch or is brought substantially to the rotational speed of the drive side of the at least one clutch or has already substantially reached the rotational speed of the drive side of the at least one clutch, at the sixth point in time.

8. The method according to claim 6, which further comprises closing the synchronization device with the previously determined second synchronization force after an application of the maximum clutch pressure, and then continuously reducing the clutch pressure and, at a seventh point in time, when the second synchronization force exceeds the currently acting clutch pressure in terms of magnitude, breaking the rotational speed of the transmission input shaft away from the rotational speed of the drive side of the at least one clutch, and then determining the kiss point of the at least one clutch when, at an eighth point in time, a specific slip or a specific rotational speed difference exists between the transmission input shaft and the drive side of the at least one clutch.

9. The method according to claim 1, which further comprises forming the automatic transmission as a dual clutch transmission or forming the drivetrain of the motor vehicle as a hybrid drivetrain with at least one electric motor driving the drive side of the at least one clutch.

10. The method according to claim 1, which further comprises driving the drive side of the at least one clutch by using an external electric motor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a schematic transmission representation of a dual clutch transmission formed in particular as an automated manual transmission, wherein here the first gear stage is formed as a freewheel-shifted gear stage or the first gear stage has a freewheel,

(2) FIG. 2 shows, in a schematic representation, the performance of the method according to the invention with the respective method steps in a schematic graphic representation.

DETAILED DESCRIPTION OF THE INVENTION

(3) FIGS. 1 to 2 are supposed to illustrate in greater detail a method for determining transmission and/or clutch parameters of an automatic transmission 1 having at least one clutch K, here in particular two clutches K1 or K2, in particular for basic calibration of automatic transmission 1, in particular here of an automated manual transmission which is formed in particular as a dual clutch transmission 1a.

(4) FIG. 1 shows here an automatic transmission 1 which is formed here in particular as an automated manual transmission, here in particular as dual clutch transmission 1a, and has two clutches K1 and K2.

(5) The drag torque and/or the kiss point of a clutch K, here in particular of first clutch K1, is determined with the method described in greater detail here below with the aid of at least one actuable synchronization device S1. Clutch K, here in particular clutches K1 and K2 of the represented dual clutch, have at least one drive side 3 which can be actively connected and/or is actively connected to an internal combustion engine output shaft 2 and at least one output side 4 which is actively connected to a transmission input shaft 5. A K0 clutch actively provided between internal combustion engine output shaft 2 and drive side 3 of clutch K is not explicitly represented here.

(6) In the case of the exemplary embodiment represented here in FIG. 1 of dual clutch transmission 1a represented there, clutch K there is embodied as a dual clutch and has in particular two clutches K1 and K2 embodied as a friction clutch. Dual clutch or clutch K has a drive side 3 and an output side 4 or two output sides 4a and 4b, wherein here in particular an output side 4, namely output side 4a of first clutch K1, is actively connected to transmission input shaft 5. In the closed state of first clutch K1, a corresponding torque can then be transmitted from drive side 3 of the clutch via output side 4, here output side 4a, to transmission input shaft 5.

(7) Transmission input shaft 5 can be referred to as a first transmission input shaft, wherein dual clutch transmission 1a also has a second transmission input shaft 6. At least one transmission output shaft is and/or in the case of the exemplary embodiment represented here in FIG. 1 of dual clutch transmission 1a represented here two drive shafts 7 and 8 are provided which are actively connected to an axle differential not designated in greater detail.

(8) In particular on an EOL test bench, if automatic transmission 1, in particular dual clutch transmission 1a represented here, is “basically calibrated”, drive side 3 of clutch K, here in particular first clutch K1, is driven, as already explained above. It should once again be pointed out here that, in the case of automatic transmission 1 represented here, in particular dual clutch transmission 1a represented here, freewheel F is assigned to first gear stage G1, as schematically represented. Dual clutch transmission 1a has here several gear stages G, in particular at least six gear stages G1 to G6, and several synchronization devices S, in particular at least synchronization devices S1 to S3.

(9) The above-mentioned disadvantages are thus initially avoided in that drive side 3 of clutch K, here in particular first clutch K1, is driven with the aid of an electric motor, not represented here, that at least one freewheel-shifted gear stage, in particular first gear stage G1 is freewheel-switched or present and that drive side 3 of the clutch is correspondingly driven by the electric motor in a direction of rotation opposite to the direction of rotation of internal combustion engine output shaft 2. As a result of this, the above-mentioned disadvantages are avoided and corresponding advantages are achieved.

(10) Below, the individual steps of the method according to the invention will be explained again in greater detail on the basis of FIG. 2. It should first, however, generally be pointed out that FIG. 2—from the representation—shows negative torques and/or rotational speeds since, according to the invention, the rotation of drive side 3 of clutch K and thus also the rotation of transmission input shaft 5 in an opposite direction of rotation to the—conventional —direction of rotation of internal combustion engine output shaft 2 should represent. The torques and rotational speeds represented there on the y-axis have therefore been provided with a minus sign (−). Reference is, however, made in the following description partially to the values/points/profiles represented in FIG. 2 “in a magnitude-based manner”, wherein this can also be referred to at this point.

(11) FIG. 2 shows that, in a first step, in particular at a first point in time t.sub.1, clutch K, here first clutch K1, is closed with a specific clutch force M.sub.kup, in particular a specific clutch torque is realized. Rotational speed n.sub.fW of the freewheeling transmission input shaft, here first transmission input shaft 5, is increased thereafter in terms of magnitude to rotational speed n.sub.mot of drive side 3 of the clutch, here first clutch K1, as is apparent in FIG. 2 from the dashed ramp-shaped representation between points in time t.sub.1 and t.sub.2. It is initially assumed here that rotational speed n.sub.mot of drive side 3 of the clutch substantially corresponds to the rotational speed of electric motor (n.sub.mot). In particular at a second point in time t.sub.2, rotational speed n.sub.fW of the transmission input shaft, here first transmission input shaft 5, then reaches rotational speed n.sub.mot of drive side 3 of clutch K. The term “substantially” means in particular that the approximation of the rotational speeds is realized in particular while maintaining a minimum slip and/or a stationary differential rotational speed.

(12) In a second step, in particular at a third point in time t.sub.3, synchronization device S is actuated, here in particular synchronization device S1 from FIG. 1, namely an ansynchronization process of a gear stage of the transmission assigned to freewheeling transmission input shaft 5, for example, third gear stage G3, is started with the aid of the synchronization device and synchronization device S1 is acted upon with a synchronization force which increases in particular continuously. This is the case or correspondingly represented in FIG. 2 between the third point in time t.sub.3 and a fifth point in time t.sub.5.

(13) As is apparent from FIG. 2, in particular at a fourth point in time t.sub.4, rotational speed n.sub.fW of transmission input shaft 5 breaks away from rotational speed n.sub.mot of drive side 3 of clutch K, wherein the first synchronization force which is then present here is determined and/or identified and as a result of this the drag torque of the clutch can then be determined and/or calculated.

(14) As FIG. 2 shows, in particular at a fifth point in time t.sub.5, a second specific synchronization force which is then present is determined if a specific slip and/or a specific rotational speed difference is determined between the transmission input shaft, here first transmission input shaft 5, and drive side 3 of clutch K, here first clutch K1. This second synchronization force is used or called upon to determine the kiss point of the clutch, here first clutch K1, in particular a corresponding synchronization torque M.sub.sync is then initially determined.

(15) Before the kiss point of the clutch, here first clutch K1, is determined and/or adapted, actuated synchronization device S1 is initially moved into its neutral position, in particular after fifth point in time t.sub.5. As a result of this, rotational speed n.sub.fW of transmission input shaft 5 in terms of magnitude approaches rotational speed n.sub.mot of drive side 3 of clutch K, here clutch K1, or is brought substantially to rotational speed n.sub.mot of drive side 3 of clutch K, here first clutch K1. In particular at a sixth point in time t.sub.6, rotational speed n.sub.fW of transmission input shaft 5 reaches rotational speed n.sub.mot of drive side 3 of clutch K, as represented in FIG. 2.

(16) It is furthermore apparent from FIG. 2 that clutch K, here first clutch K1, is closed with a maximum clutch pressure M.sub.kupmax, in particular, however, after the fifth point in time t.sub.5 and/or after the sixth point in time t.sub.6, in particular, however, only after the sixth point in time t.sub.6. The rotational speed n.sub.fW of transmission input shaft 5 has, in the case of the exemplary embodiment represented in FIG. 2, already approached rotational speed n.sub.mot of drive side 3 of clutch K, here first clutch K1, or rotational speed n.sub.fW of transmission input shaft 5 has already reached rotational speed n.sub.mot of drive side 3 of clutch K if clutch K, here first clutch K1, is closed with maximum clutch pressure M.sub.kupmax.

(17) In a further step, in particular after the application of maximum clutch pressure M.sub.kupmax, synchronization device S1 is closed with the previously determined second synchronization force or corresponding synchronization torque M.sub.Sync is applied. This is the case or correspondingly represented in FIG. 2 in particular between point in time t.sub.6 and seventh point in time t.sub.7. After this, the clutch pressure is in particular continuously reduced starting from clutch pressure M.sub.kupmax. In particular at a seventh point in time t.sub.7, in particular when the second synchronization force or synchronization torque M.sub.Sync exceeds the currently acting clutch pressure in terms of magnitude, rotational speed n.sub.fW of transmission input shaft 5 breaks away from rotational speed n.sub.mot of drive side 3 of clutch K, here first clutch K1. This is clearly represented in FIG. 2.

(18) In particular when, in particular at an eighth point in time t.sub.8, a specific slip and/or a specific rotational speed difference between transmission input shaft 5 and drive side 3 of clutch K is present, based on this the kiss point of the clutch is determined and/or this is correspondingly adapted afterwards, in particular later when the method is ongoing.

(19) As already mentioned above, automatic transmission 1 is formed in particular as a dual clutch transmission 1a, but other forms of automatic transmissions are also conceivable. The known further components such as a control unit, rotational speed sensors for identifying, measuring the respective current rotational speeds or the like, are correspondingly provided or present.

(20) The drivetrain of the motor vehicle can be formed as a hybrid drivetrain and therefore have at least one electric motor. In this case, precisely this electric motor of the hybrid drivetrain can also drive drive side 3 of clutch K, here in particular first clutch K1, where desired.

(21) It is, however, also conceivable that the drive side of the clutch is driven by an external electric motor, in particular by an electric motor which is present on the EOL test bench.

LIST OF REFERENCE NUMBERS

(22) 1 Automatic transmission 1a Dual clutch transmission 2 Internal combustion engine output shaft 3 Drive side 4 Output side 4a, 4b Output side of clutch K1/K2 5 First transmission input shaft 6 Second transmission input shaft 7 Drive shaft 8 Drive shaft MSync Synchronization torque M.sub.kup Clutch force/clutch torque M.sub.kupmax Maximum clutch force/maximum clutch torque K, K1, K2 Clutch, first or second clutch S, S1 to S3 Synchronization devices F Freewheel t1 to t8 First to eighth point in time G, G1 to G6 Gear stages/gears nfW Rotational speed of the transmission input shaft nmot Rotational speed of the drive side of the clutch