Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Patent
1999-04-02
2000-07-11
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
701 51, B60K 4112
Patent
active
060865075
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention proceeds from an arrangement and a method for automatically adjusting the transmission ratio of a continuously variable transmission.
BACKGROUND OF THE INVENTION
Continuously variable vehicle transmissions are, for example, known from EP, A1, 0 451 887. Here, the rpms of the drive end (primary end) and the output end (secondary end) are measured by two rpm sensors for adjusting or shifting the transmission ratio. The transmission ratio which is to be adjusted or is adjusted is determined from these sensor signals.
A belt transmission, which is continuously adjustable with respect to its transmission ratio, having a drive end and output end is known from DE, A1, 44 11 628. The drive end and output end have at least one axially displaceable element which has essentially the form of a conical disc. The belt part is, in general, put in place as a band, preferably a thrust element band or a belt or a chain between disc pairs which define the drive end and the output end.
To control the slip of the belt part, the axial displacement of at least one of the axially displaceable elements as well as the rpms of the drive end and the output end are detected. The output signal of a single sensor is evaluated for the rpm detection of one of the two ends as well as for the detection of the axial displacement on this end.
SUMMARY OF THE INVENTION
The object of the present invention is to adjust, as precisely as possible, the transmission ratio of a continuous transmission in all operating regions in a simple and cost-effective manner.
As already mentioned, the invention proceeds from an arrangement and a method for adjusting the transmission ratio of a continuously adjustable belt transmission having a drive end and an output end. The drive end and the output end have at least one axially displaceable element which essentially has the form of a conical disc. On the one hand, an rpm signal, which represents the rotational movement of the drive end or the output end, is detected by sensor means and, on the other hand, a displacement signal is detected which represents the axial displacement of at least one of the elements which are axially displaceable.
The essence of the invention is that means for adjusting the transmission ratio are provided by means of which the adjustment takes place at least in dependence upon the detected displacement signal.
An advantage of the invention is that the possibility is hereby given to be able to omit an rpm sensor. Furthermore, and as will be shown more precisely in the course of the description, the entire transmission ratio adjustment is substantially independent of the engine load or of the drive torque operating on the drive train.
In an especially advantageous first embodiment of the invention, it is provided that the means for adjusting the transmission ratio are so configured that the adjustment takes place in dependence upon the detected rpm signal which represents the rotational movement of the drive end and in dependence upon the detected displacement signal which represents the axial displacement of one of the elements which is axially displaceable on the drive end. Here, it can be especially provided that the adjustment of the transmission ratio takes place without a rotational movement of the output end detected directly by a sensor. In this embodiment, the axial displacement and the drive rpm are applied to adjust the transmission ratio. Compared to the transmission ratio adjustment, which considers also the output rpm, the adjustment of the transmission ratio for a low longitudinal vehicle speed is hereby advantageously more precise because, in this operating range, the drive rpm is in general greater than the output rpm.
In this first embodiment, it can be provided that, in dependence upon the detected rpm signal, which represents the rotational movement of the drive end and the detected signal, which represents the axial displacement of an axially displaceable element which is arranged on the drive end, the rotational movement
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patent: 5600557 (1997-02-01), Ogawa
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patent: 5871416 (1999-02-01), Sawada et al.
Marmor Charles A.
Ottesen Walter
Pang Roger
Robert & Bosch GmbH
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