Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Patent
1994-12-16
1996-08-13
Wright, Dirk
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
477 48, B60K 4112, F16H 5906, F02D 4104
Patent
active
055451063
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for inputting the actual transmission ratio of a continuously variable transmission (CVT=continuously variable transmission) such as of a passenger motor vehicle wherein operating points of a shift characteristic field can be assumed. The operating points lie on a characteristic line of optimized consumption of a motor characteristic field of a motor of the motor vehicle. In the method, operating points of the shift characteristic field can also be assumed which lie on a characteristic line of optimized power of the motor characteristic field. The trace of the characteristic lines of the shift characteristic field results from the particular selected characteristic line of the motor characteristic field.
BACKGROUND OF THE INVENTION
Transmissions having continuous transmission ratio adjustment are available in the marketplace and operate utilizing hydraulic controls. Such controls are very complex.
Furthermore, electronically controlled continuously variable transmissions are known wherein a motor vehicle can be driven pursuant to driver command or automatically on different characteristic lines of a motor characteristic field of the motor. It is known to undertake this operation on the characteristic line of optimal consumption (efficiency) or on the characteristic line of optimal power. Shift characteristic lines of shift characteristic fields are derived from these respective characteristic lines of the motor characteristic field. These shift characteristic lines permit the known economy operation or sport operation of the transmission. It is disadvantageous that a relatively poor acceleration performance referred to a specific throttle flap change of the motor is present in the economy mode and that, in the sport mode, a high and therefore uneconomical rpm level is pregiven for a drive at constant speed.
SUMMARY OF THE INVENTION
The method of the invention affords the advantage compared to the above that a dynamic adjustment of the transmission ratio of the continuously variable transmission takes place so that especially a favorable, low rpm level in the economy mode is combined with excellent acceleration capacity. According to the invention, special characteristic lines in the motor characteristic field are selected for the derivation of the shift characteristic field of the dynamic control. The special characteristic lines in the motor characteristic field are selected in such a manner that (proceeding from the characteristic line of optimal or optimized consumption for a drive at constant speed) a power excess and therefore an improved acceleration is obtained from a change of the power demand. The power excess results in correspondence to the rate of change of the power demand. The transition from one operating point having optimized consumption to an operating point of optimized or desired power does not take place abruptly but rather continuously. Jumps in the characteristic field are therefore avoided. To realize an acceleration command of the driver of the motor vehicle, the relevant characteristic line is shifted correspondingly far in a direction toward the power optimized characteristic line. If the demand for a lesser acceleration is present, then the characteristic line is moved in the direction of the consumption-optimized characteristic line. The shift characteristic field of the invention results from these inputs. There, operating points can be assumed which lie on a dynamic characteristic line of the motor characteristic field running between the characteristic line of optimized consumption and the characteristic line of optimized power. As mentioned, the position of the dynamic characteristic line is dependent upon the magnitude of the rate of change of the power requirement.
According to another embodiment of the invention, the power demand corresponds to the position of the throttle flap of the motor and therefore the rate of change of the power demand corresponds to the rate of change of the throttle flap.
In view of
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Bauerle Peter
Keuper Gerhard
Senger Karl-Heinz
Ottesen Walter
Robert & Bosch GmbH
Wright Dirk
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