METHOD FOR DETERMINING A BITE POINT OF A HYBRID CLUTCH IN A HYBRID VEHICLE

Abstract

The invention relates to a method for determining a bite point of a hybrid clutch in a hybrid vehicle. The hybrid clutch is actuated by a hydrostatic clutch actuator (12) and disconnects or connects an internal combustion engine (2) and an electric motor (3); the bite point is determined by slowly actuating the hybrid clutch (4) starting from a separating position of the hybrid clutch (4), this position being in the non-actuated state, with a defined torque reaction of the electric motor (3) being detected. The invention also relates to a method in which the quality of the bite point is improved, the duration of the bite point adaptation is essentially shortened, the bite point being adapted during the running of the internal combustion engine (2) and when the electric motor (3) is immobile and a torque reaction of the electric motor (3) is validated by the torque reaction of the internal combustion engine (2).

Claims

1. A method for determining a bite point of a hybrid clutch of a hybrid vehicle, which is actuated by a hydrostatic clutch actuator, with the hybrid clutch disconnecting or connecting an internal combustion engine and an electric motor, the method comprising: detecting the bite point by slowly activating the hybrid clutch, starting from a separating position of the hybrid clutch, which said hybrid with assumes in an idle state, to a defined torque reaction of the electric motor, adapting the bite point while the internal combustion engine is operating and the electric motor is stationary, and validating a torque reaction of the electric motor with a torque reaction of the internal combustion engine.

2. The method according to claim 1, further comprising speed controlling the electric motor when stationary.

3. The method according to claim 1, further comprising controlling the internal combustion engine to an idling speed.

4. The method according to claim 1, wherein during the adaption of the bite point the method further comprising disconnecting the internal combustion engine from the drive train.

5. The method according to claim 1, wherein for adapting the bite point during operation of the hybrid vehicle the method further comprises: using a start-up routine by which a first bite point is determined during the start-up of the hybrid vehicle, with the hybrid clutch being approached to a proximity of a previously determined bite point and the hybrid clutch, starting from said previously determined bite point, further displacing the hybrid clutch until the defined torque reaction is detected.

6. The method according to claim 5, further comprising during the start-up of the hybrid vehicle determining the first bite point of the hybrid clutch via the start-up routine, and using said bite point is used during a first adaption in order to determine a presently given bite point during operation of a hybrid vehicle based on the previously determined bite point.

7. The method according to claim 5, wherein a most recently determined bite point is used as the previously determined bite point, which was determined in the adaption phase directly preceding the present adaption phase.

8. The method according to claim 1, further comprising monitoring a torque increase as the torque reaction, and drawing conclusions regarding the defined torque increase when a predetermined threshold of the torque increase is exceeded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention allows numerous embodiments. One of them shall be explained in greater detail based on the figure shown in the drawing.

[0015] Shown is

[0016] FIG. 1: an illustration of the principle of a hybrid drive of a hybrid vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 shows an illustration of the principle of a drive train 1 of a hybrid vehicle. The drive train 1 comprises an internal combustion engine 2 and an electric motor 3. A hybrid clutch 4 is arranged between the internal combustion engine 2 and the electric motor 3, directly downstream the internal combustion engine 2. The internal combustion engine 2 and the hybrid clutch 4 are connected to each over via a crankshaft 5. The electric motor 3 comprises a rotational rotor 6 and a stationary stator 7. The driven shaft 8 of the hybrid clutch 4 is connected to a transmission, which comprises a coupling element, not shown in greater detail, for example a second clutch or a torque converter, arranged between the electric motor 3 and the transmission 9. The transmission 9 transfers the torque generated by the internal combustion engine 2 and/or the electric motor 3 to the driving wheels 10 of the hybrid vehicle. The hybrid clutch 4 and the transmission form here a transmission system 11, which is controlled by a hydrostatic clutch actuator 12 used in combination with the hybrid clutch 4, which is closed in the idle state. The hybrid clutch 4 is actuated over a hydrostatic path by the hydrostatic clutch actuator 12.

[0018] The hydrostatic clutch actuator 12 comprises a control device 13, which is connected to an idling speed control 14 of the internal combustion engine 1, with a first speed sensor 15 leading thereto, detecting the speed of the internal combustion engine 1. Furthermore, the control device 13 is connected to a speed controller 16 of the electric motor 3, which is also supplied with respective rotational speeds of the electric motor 3 by a second speed sensor 17, opposite the rotor 6 of the electric motor 3.

[0019] The bite point is particularly important for controlling the hybrid clutch 4 and is therefore determined during the initial start-up routine of the vehicle. The adaption of the bite point occurs with the internal combustion engine 2 being in motion, operating at idling speeds, during the operation of the vehicle. Here, the vehicle is stationary. In order to determine the bite point the hybrid clutch 4 is slowly closed and the electric motor 3 is controlled via the speed controller 16 to 0 revolutions. By the slow closing of the hybrid clutch 4 it respectively develops slowly a torque and transfers this torque from the internal combustion engine to the electric motor 3. The idling speed controller 14 of the internal combustion engine 2 at the side of the internal combustion engine and the speed controller 16 at the side of the electric motor 3 become active and respectively increase their torque in order to maintain the speed set. Here, the change in torque of the internal combustion engine 1 is used for validation of the change in torque set by the electric motor 2.

[0020] At the point of time at which the hybrid clutch 4 begins to transfer torque, the electric motor 3 is slightly entrained. Due to the speed control applied to the electric motor 3 the torque of the electric motor 3 increases. When a defined increase in torque is given the present bite point is detected. Due to the fact that the electric motor 3 is stationary at the start of the determination process of the bite point any speed undershoots are reliably prevented.

[0021] During the first start-up of the hybrid vehicle a start-up routine is initiated to determine the first bite point. The torque of the electric motor 3 is increased by closing the hybrid clutch 4. The hybrid clutch is closed to a minimum bite point position, which has been determined by way of calculation. Starting from this minimum bite point position, the hybrid clutch 4 is slowly closed, with the hybrid clutch 4 showing constant speed. During the closing process of the hybrid clutch 4 the torque is further monitored both at the electric motor 3 as well as at the internal combustion engine 2. At the very moment at which the torque of the internal combustion engine 2 exceeds a predetermined threshold and the torque of the electric motor 3 shows a similar value a conclusion is drawn regarding the bite point, with a waiting time being shortened in which the electric motor 3 can assume its stationary condition. Subsequently the hybrid clutch 4 is opened again and it is checked if the torque level of the electric motor 3 at the end of the start-up process is equivalent to the torque level the electric motor 3 issued at the onset of the start-up routine.

[0022] This start-up routine, in which the bite point is determined for the first time, is followed by adaption phases during the drive operation of the hybrid vehicle, in which the bite point determined in this fashion is adapted in order to allow considering changes of the bite point caused by wear and tear, temperature, and the like, thus allowing a more precise controlling of the clutch actuator 12.

[0023] At the bite point adaption during operation of the hybrid vehicle, here the start-up routine is used, which was used during the initial start-up operation of the hybrid vehicle. Due to the fact that by the start-up operation a first bite point is already known, this bite point is used to move the hybrid clutch 4 almost up to said bite point position known. By the rapid approach of the hybrid clutch 4 to the known bite point position here the times for bite point adaption is shortened. After the approach to this known bite point position the hybrid clutch 4 is slowly closed again and the torque issued by the electric motor 3 and/or the internal combustion engine 2 is monitored and evaluated in the manner described.

[0024] The method explained significantly improves the quality of the bite point adaption by additionally evaluating the torque of the internal combustion engine. Here, the torque of the internal combustion engine 1 represents a redundant information source by which the precision of the bite point determination can be considerably increased and the duration can be shortened by eliminating waiting times.

LIST OF REFERENCE CHARACTERS

[0025] 1 Drive train [0026] 2 Internal combustion engine [0027] 3 Electric motor [0028] 4 Hybrid clutch [0029] 5 Crankshaft [0030] 6 Rotor [0031] 7 Stator [0032] 8 Driven shaft [0033] 9 Transmission [0034] 10 Driving wheels [0035] 11 Transmission system [0036] 12 Hydrostatic clutch actuator [0037] 13 Control device [0038] 14 Idling speed controller [0039] 15 Speed sensor [0040] 16 Speed controller [0041] 17 Speed sensor