Automatic clutch

Details Automatic clutch Automatic clutch

1999-03-25

2000-07-11

Wright, Dirk

Interrelated power delivery controls, including engine control

Transmission control

With clutch control

477171, F16D 4806, B60K 4102

Patent

active

060865083

DESCRIPTION:

BRIEF SUMMARY
The invention concerns an automatic clutch in the drive train of a motor vehicle, having a transmission which is manually shifted between different drive positions or gears, having an adjusting unit which automatically actuates the clutch and having a system of sensors which serves for controlling said adjusting unit, senses (inter alia) driver actuation of a vehicle brake, driver actuation of a control element (e.g. throttle valve) of the engine as well as an activated state of a drive position and sets the clutch to a creeping moment if, with the engine running and the drive position selected, the vehicle brake and the control element of the engine are unactuated, or releases the clutch if the vehicle brake remains actuated and the control element is not actuated.
In the case of motor vehicles with customary internal combustion engines, a transmission must be arranged in the drive train to allow the transmission ratio between the speed of the vehicle engine and the speed of the drive wheels to be changed according to the respective travelling speed and loading of the vehicle. In the case of customary transmissions, during a change of drive position the power flow between engine and drive wheels has to be interrupted by releasing a clutch.
It is known in principle to use automatic clutches for this purpose, i.e. the clutch is automatically released when changing a transmission stage and is subsequently re-engaged.
To make maneuvering operations easier, it is known in principle to set the automatic clutch to a light transmissible torque, i.e. a creeping moment, when a transmission stage has been selected, the engine is running and neither the service brake of the vehicle nor a gas pedal serving for controlling the power of the engine, or the like, are actuated. This makes use of the fact that the engines of motor vehicles nowadays usually have an effective automatic engine control which is able to keep the engine at a minimum speed, generally at the so-called idling speed, when the gas pedal is unactuated, to be precise even if the engine is loaded to varying degrees. On the basis of the transmission of a creeping moment by the clutch envisaged in this case, the vehicle can start creeping forward or perform a creeping movement, as is desired for maneuvering operations.
According to PATENTS ABSTRACTS OF JAPAN, M-857 Jul. 31, 1989, Vol. 13/No. 340, it is known from JP 1-115742 (A) to release the automatic clutch fully after a predetermined time interval in the creeping phase described above.
According to PATENTS ABSTRACTS OF JAPAN, M-1672 Sep. 13, 1994, Vol. 18/No. 491, JP 6-159397 (A) shows in this connection that the creeping moment is to be automatically controlled in a way in which the speed of the vehicle engine does not go below a minimum speed.
The object of the invention is thus to improve further the clutch control in maneuvering operations.
This object is achieved according to the invention by the clutch moment being slowly reduced when the brake is actuated and the control element is unactuated.
The invention is based on the general idea that in driving maneuvres with the gas pedal or the like not actuated, in the event of the brake being actuated the clutch can still transmit a certain torque, which is small in comparison with the achievable braking forces and is also reduced sooner or later with respect to the creeping moment transmitted when the brake is not actuated and when the gas pedal is unactuated, or brought to diminishing values. This ensures that the driver can initially control the travelling speed against the creeping tendency of the vehicle by actuating the brake with varying force. At the same time, it is ensured that undesired overloading of the clutch is avoided.
A particular advantage of the invention is that, if the brake is actuated only for a short time during a creeping maneuvre, a torque is constantly transmitted by the clutch and, when actuation of the brake is ended, is available without delay in reproducible intensity, without complex control measures being necessary for

REFERENCES:
patent: 5632706 (1997-05-01), Kremmling et al.
patent: 5700227 (1997-12-01), Kosik et al.
patent: 5916061 (1999-06-01), Koyama et al.
patent: 5941792 (1999-08-01), Amendt et al.

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