Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Patent
1995-10-19
1997-11-18
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
477 43, 474 18, B60K 4112
Patent
active
056882041
DESCRIPTION:
BRIEF SUMMARY
The invention refers to a shifting device for a continuously variable transmission of a motor vehicle where the ratio of the transmission is automatically selected in an operating mode, and adjusted by an electronic unit through signals from a regulating device depending on the operation parameters of the motor vehicle. In another operating mode, the driver can effect a manual engagement in which an operation parameter is changed by the regulating device.
BACKGROUND OF THE INVENTION
DE-A-39 32 720 has disclosed a regulating device. It has a selector lever with which a speed range can be reduced. In the device known already, the ratio or the engine speed is downwardly limited. A disadvantage of this known system is that the possibility of the driver having an influence is greatly reduced by the preset range limits. Beside, it is not to be understood from said prior art how a combination of several operation parameters could be possible.
SUMMARY OF THE INVENTION
The invention is based on the problem of providing a shifting device for a continuously variable transmission of a motor vehicle with which it is possible to influence, by manual engagement, the characteristic field of a speed range.
Fundamentally aside from the configuration of the shifting device for a continuously variable transmission, the solution of the stated problem consists in that in the additional operating mode, the working point can be controlled by a continuously variable or incremental or decremental change of individual operation parameters or a combination of at least two operation parameters. Said operation parameters consist of the engine speed, the transmission ratio and the output speed.
It is of a particular advantage to form the operation parameters, for influencing the working point, from a combination of the engine speed and the transmission ratio, or from a combination of the engine speed with the output speed, or from a combination of all three parameters. When said two parameters are actually combined, an excellent travel behavior, especially in mountainous terrains, results in relation to a manual engagement. When ascending mountains, undesirable shift changes are prevented while, when descending mountains, the braking effect of the engine can be fully utilized.
With the combination of the output speed, it is additionally possible to maintain a desired road speed, in a certain range, when needed.
In a shifting device such as conventionally used in automatic transmissions, a regulating device is provided the swiveling of which to a shifting gate makes it possible to preselect the automatic multiplication stages. The regulating device can be further transferred to a second shifting gate through a transverse gate. In another solution of the stated problem, by swiveling the regulating device to the second gate, the limits of a characteristic field can be changed by the combination of the engine speed and the transmission ratio.
By swiveling the regulating device to the second gate, analog or digital output signals are produced which are passed on to the electronic control unit. In a preferred embodiment, said output signals effect a uniform (absolute) change according to a value of at least one operation parameter, such as the engine speed or the transmission ratio. Unlike in the shifting devices already known (for instance, DE-A-41 20 540), said change is not a function of the working point (and thus more or less great) but always uniform. Therefore, the result of a shifting operation is always foreseeable for the driver. The manually effected change can also be produced by a time-dependent function. The change is then primarily a function of the duration of the activation. The result of a manual actuation is then also readily foreseeable for the driver.
In another preferred embodiment, the digital signals are combined by the control unit to form an output signal which takes into account at least the engine speed and transmission ratio operation parameters. In this manner, it is ensured that by a digital or an analog s
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Frei Walter
Runge Wolfgang
Welte Anton
Kwon Peter T.
Marmor Charles A.
ZF Friedrichshafen AG
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