DE102010001975A1 - Method for operating drive train of motor car, involves completely opening clutch and reducing speed default signal or torque default signal during occurrence of event when rotational torque of drive unit reaches or exceeds threshold value - Google Patents

Abstract

The method involves connecting a transducer lockup clutch (6) parallel to a transducer (5). The clutch is opened and a rotation speed default signal or a torque default signal is increased during occurrence of an event when a rotational speed of a drive unit (1) of a drive train reaches or falls below a threshold value. The clutch is completely opened and the rotation speed default signal or torque default signal is reduced during occurrence of another event when a rotational torque of the drive unit reaches or exceeds the threshold value so as to operate the drive unit in an idling speed.

Description

The invention relates to a method for operating a drive train of a motor vehicle.

The main components of a drive train of a motor vehicle are a drive unit and a transmission. The transmission converts speeds and torques and thus provides a traction power supply of the drive unit at a power take-off of the drive train ready.

The present invention relates to a method for operating a drive train according to 1 a drive unit 1 , one between the drive unit 1 and a downforce 3 switched gear 2 and one between the drive unit 1 and the gearbox 2 switched hydrodynamic starting element with a converter 5 and one parallel to the transducer 5 switched converter lockup clutch 6 having.

The gear 2 is preferably designed as an automatic or automated manual transmission. With the drive unit 1 it is a pure combustion engine or a hybrid drive from internal combustion engine and electric machine.

2 illustrates the known from the prior art procedure for operating a drive unit 1 , a gearbox 2 and a hydrodynamic starting element comprising a drive train in pushing operations, wherein in 2 three curves are shown over time, namely a curve n5, AB to illustrate a driven-side speed of the converter 5 , a time curve n1 to illustrate a speed of the drive unit 1 and a curve p6 to illustrate a pressure control of the converter lockup clutch 6 ,

According to the prior art, it is already common in overrun operation of the drive train, when a defined, applicable event occurs, which occurs in 2 occurs at time t1, the converter lock-up clutch 6 of the drive train starting from a fully closed state or a slipping, partially closed state to fully open, for this purpose according to the prior art 2 at time t1, the pressure control p6 of the converter lockup clutch 6 is ramped down to approximately zero starting from the pressure applied at time t1. In this case, according to the prior art, the parallel to the converter 5 switched converter lockup clutch 6 fully open, in which case the curve n1 for the speed of the drive unit 1 established. So can 2 be taken that in the prior art, the speed n1 of the drive unit 1 At time t2 quickly and uncontrollably drops to an idling speed. This rapid, uncontrolled drop in the speed of the drive unit n1 is noticeable to a driver of the motor vehicle and is perceived as uncomfortable.

There is therefore a need for a method for operating a drive train with a drive unit, a transmission and a hydrodynamic starting element, with which the drive unit can be more conveniently converted to idling speed in overrun operation of the drive train by opening the lockup clutch.

From the US 7,510,505 B2 a method for operating a drive train with a drive unit, a transmission and a hydrodynamic starting element is known. According to the method disclosed therein, a clutch which is connected in parallel with the converter is actuated in overrun mode.

On this basis, the present invention based on the problem to provide a novel method for operating a drive train.

This problem is solved by a method according to claim 1. According to the invention, the torque converter lockup clutch is first opened slipping and increases a speed command signal or torque command signal for the drive unit, wherein subsequently upon occurrence of a second defined, applicable event, the lockup clutch completely open and the speed command signal or torque command signal for the drive unit is reduced again to guide the drive unit to an idling speed in a defined manner.

With the method according to the invention, it is proposed, when based on a defined, applicable event, the converter lock-up clutch is slipping open, simultaneously or in parallel to increase a speed command signal or torque command signal for the drive unit, wherein subsequently upon occurrence of a second defined, applicable event, the lockup clutch completely opened and the speed command signal or torque command signal for the drive unit is reduced again. With the method according to the invention, it is possible to control the rotational speed of the drive unit during overrun operation of the drive train and to conveniently transfer it to the idling speed.

Preferred developments of the invention will become apparent from the dependent claims and the following description. An embodiment of the invention will be described, without being limited thereto, with reference to the drawing. Showing:

1 a Antriebsstrangschema a motor vehicle, in which the inventive method can be used;

2 a diagram illustrating the known from the prior art method for operating a drive train; and

3 a diagram for illustrating the method according to the invention for operating a drive train.

The present invention relates to a method for operating a drive train of a motor vehicle. 1 shows very schematically a drive train scheme of a drive train, in which the inventive method can be used.

The powertrain of 1 includes a drive unit 1 and a gearbox 2 , where the gear 2 between the drive unit 1 and a downforce 3 the drive train is switched. With the drive unit 1 it may be a pure combustion engine or a hybrid drive of internal combustion engine and electric motor. In the transmission 2 it is preferably an automatic or automated manual transmission, wherein the transmission 2 comprises a plurality of switching elements, of which in 1 a switching element 4 is shown as an example. Between the transmission 2 and the drive unit 1 is a hydrodynamic starting element with a converter 5 and one parallel to the transducer 5 switched converter lockup clutch 6 connected.

The present invention now relates to a method for operating such a drive train with drive unit 1 , Transmission 2 and hydrodynamic starting element 5 . 6 , with which in the overrun mode of the drive train, the drive unit 1 comfortable and controlled can be converted into an idle speed.

Details of the method according to the invention emerge 3 , where in 3 four temporal curves are shown, namely a curve for the output side speed n5, AB of the converter 5 , A curve for adjusting in the process according to the invention speed n1 of the drive unit 1 , a curve p6 for the pressure control of the lockup clutch 6 and a speed command signal n'1 and a torque command signal M'1 for the drive unit 1 ,

3 can be seen that when at time t1, a first defined, applicable event occurs or occurs, the lockup clutch 6 by corresponding reduction of the pressure control p6 for the converter lockup clutch 6 starting from a fully closed or a slipping, partially closed state is initially slipping open, at the same time or parallel thereto, the speed command signal n'1 and the torque command signal M'1 for the drive unit 1 is increased.

Then, when subsequently a second defined, appliable event occurs or occurs, namely according to 3 at time t3, the lockup clutch becomes 6 is completely opened by further lowering the pressure preset signal p6 and the speed command signal n'1 and the torque command signal M'1 for the drive unit again reduced so as to drive the unit 1 defined to lead to an idling speed.

Between the times t1 and t3, ie between the first defined, administrable event and the second defined, applicable event, the torque converter lock-up clutch 6 controlled by a pressure control and slipping open. Subsequent to the time t3, ie with the occurrence of the second defined, applicable event, the pressure control of the converter lock-up clutch 6 by a speed control for the drive unit 1 replaced or replaced.

The first defined, applicable event occurs, for example, when the actual speed of the drive train reaches or falls below a defined, applicable limit value.

Alternatively, it is possible that the first defined, applicable event occurs or occurs when a rotational speed of the drive assembly 1 reaches or falls below a defined, applicable limit value.

The second defined, administrable event occurs or occurs when a defined, applicable period of time has elapsed after the first defined, administrable event. In this case, there is a fixed time difference between times t1 and t3.

Alternatively, it is also possible for the second defined, administrable event to occur when the rotational speed specification signal n'1 or the torque specification signal M'1 reaches or exceeds a defined, applicable limit value. According to another alternative, it is possible that the second defined, administrable event then occurs when the actual torque of the drive unit reaches or exceeds a defined, applicable limit value.

In the preferred exemplary embodiment shown, between the times t1 and t3, ie between the first defined, administrable event and the second defined, applicable event, the pressure specification signal p6 for the torque converter lockup clutch 6 ramp-like reduced linearly with a constant slope, whereas the speed command signal n'1 and the torque command signal M'1 for the drive unit 1 is linearly increased between these times t1 and t3 with different slopes.

In contrast, however, is also a non-linear curve for the pressure control p6 of the lockup clutch 6 and for the speed command signal n'1 and the torque command signal M'1 for the drive unit 1 possible.

Accordingly, in the context of the method according to the invention, when a first defined, applicable event occurs, the converter lock-up clutch is firstly started 6 slipping open and at the same time a default signal for the drive unit 1 , Preferably, a speed command signal, increases, followed by the occurrence of a second defined, applicable event, the pressure control of the lockup clutch 6 by a speed control of the drive unit 1 is replaced. This makes it possible for the drive unit 1 controlled, jerk-free and comfortable to lead by means of a speed control to the idle speed.

LIST OF REFERENCE NUMBERS

1

power unit

2

transmission

3

output

4

switching element

5

converter

6

Converter lockup clutch

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7510505 B2 [0008]

Claims (8)

Method for operating a drive train of a motor vehicle, wherein the drive train has a drive unit, a gearbox connected between the drive unit and an output gearbox and a hydrodynamic starting element connected between the drive unit and the gearbox with a converter and a converter lockup clutch connected in parallel with the converter, and wherein when the drive train is operated in coasting mode, when a first defined, applicable event, the lockup clutch is opened, starting from a fully closed or a slipping, partially closed state, characterized in that the occurrence of the first defined, applicable event, the lockup clutch initially slipping open and a speed command signal or torque command signal for the drive unit is increased, and that subsequently upon occurrence of a second def In an applicable, applicable event, the lockup clutch is fully opened and the speed command signal or torque command signal for the power pack is reduced again to define the drive unit at an idling speed. A method according to claim 1, characterized in that between the first defined, applicable event and the second defined, applicable event the torque converter lock-up clutch is controlled by a pressure control and slipping open, and that with the occurrence of the second defined, applicable event, the pressure control of the lockup clutch by a Speed control of the drive unit is replaced or replaced. A method according to claim 1 or 2, characterized in that between the first defined, applicable event and the second defined, applicable event the speed command signal or torque command signal for the drive unit is increased in time parallel to or simultaneously with the slipping opening of the lockup clutch. Method according to one of claims 1 to 3, characterized in that the first defined, applicable event occurs when an actual speed of the drive train reaches or falls below a defined, applicable limit value. Method according to one of claims 1 to 3, characterized in that the first defined, applicable event occurs when a speed of the drive unit reaches or falls below a defined, applicable limit value. Method according to one of claims 1 to 5, characterized in that the second defined, administrable event occurs a defined, applicable period of time after the first defined administrable event occurs. Method according to one of claims 1 to 5, characterized in that the second defined, administrable event occurs when the speed command signal or torque command signal reaches or exceeds a defined, applizierbarer threshold. Method according to one of claims 1 to 5, characterized in that the second defined, administrable event occurs when the actual torque of the drive unit reaches or exceeds a defined, applizierbarer threshold.

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