192 clutches and power-stop control – Transmission control and clutch control – Common control
Patent
1999-03-25
2000-04-11
Marmor, Charles A
192 clutches and power-stop control
Transmission control and clutch control
Common control
192 362, 192 7025, 192111R, F16D 4806
Patent
active
060478004
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention concerns an automatic clutch in the drive train of a motor vehicle, having a motorized adjusting unit which actuates the clutch and is controlled by a system of sensors which allows a moment respectively transmitted by the clutch to be determined. The system of sensors senses whether the clutch is operating with slip and assigns the value of the transmitted moment of the clutch when slip is occurring to the respective value of the travel of the adjusting unit as the moment which can be transmitted by the clutch. The system further evaluates the moment value together with the travel value for adapting a characteristic curve or table of values reflecting the dependence between the clutch moment and the travel of the adjusting unit.
In motor vehicles having customary internal combustion engines, a transmission is arranged in the drive train. The transmission allows the transmission ratio between the speed of the vehicle engine and the speed of the drive wheels to be changed according to the respective traveling speed and loading of the vehicle. In the case of customary manually shifted transmissions, during a change of drive position the power flow between the engine and the 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 the transmission stage and is subsequently re-engaged.
In addition, the clutch is also automatically controlled when starting the vehicle. As soon as a drive position suitable for starting has been selected, the clutch can, for example, be automatically engaged lightly in such a way that a small torque adequate for making the vehicle start to creep forward is transmitted. As soon as the engine power and the engine speed are increased by actuating a gas pedal or some other power control element, the clutch is automatically controlled in the sense of increasing the transmissible torque. To put it in simple terms, the clutch is then increasingly engaged.
These known automatic clutches operate in the manner of friction clutches, the frictional engagement of which is controlled by the assigned adjusting unit of the clutch.
The friction linings of such clutches are subjected to unavoidable wear. This has the consequence that the maximum torque which can be transmitted by the clutch may fall below the torque which can be generated by the engine and the clutch may, as a result, "slip" comparatively frequently. The frictional heat thereby produced may lead to the clutch being destroyed.
In the case of a manually actuated clutch, the state of wear can often be detected from the amount of pedal travel or the actuating force, or in some other way from the "actuating feel".
In the case of an automatic clutch, it is known in principle to monitor parameters correlated with the clutch wear.
In the case of an automatic clutch known from German Patent document DE 30 43 348 A1, the point of engagement of the clutch is detected by sensing the operating behavior of an electric servo motor of the clutch. A characteristic change in the electrical drive current of the electric motor occurs at the point of engagement. The actual position of the point of engagement of the clutch determined in this way is reported to a set point generator. The set point generator is provided as part of the clutch control and predetermines parameter-dependently the desired positions of the electric motor in the clutch control. Consequently, the setpoint generator can adapt the emitted setpoint signals to the actual state. As soon as an excessive shift in the point of engagement is established, a wear signal is generated.
For monitoring the frictional loss of a friction clutch and for monitoring the wear of the friction lining, it is known from German Patent document DE 36 01 708 A1 to calculate the instantaneous frictional loss from the moment transmitted at a given instant by the clutch and the difference between the speed of the clutch on the inpu
REFERENCES:
patent: 4765450 (1988-08-01), Kurihara et al.
patent: 5005680 (1991-04-01), Satoh et al.
Grass Thomas
Kosik Franz
Daimler-Chrysler AG
Marmor Charles A
Rodriguez Saul
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