Power plants – Pressure fluid source and motor – Having condition responsive control in a system of distinct...
Patent
1994-12-05
1996-08-06
Nguyen, Hoang
Power plants
Pressure fluid source and motor
Having condition responsive control in a system of distinct...
60446, 60448, 60492, F16D 3102
Patent
active
055422519
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a control and regulation device for a vehicle travel drive in accordance with the preamble of claim 1.
From DE-PS 25 37 073 such a device is known, the desired-value setting means of which has three control levers, one of which serves for the setting of the speed of travel and each of the two others serves for the steering, through reduction of the transmission ratio of the respective hydrostatic transmission on the inside of a curve. This kind of steering has the disadvantage of the occurrence of undesired alterations of the speed of travel and thus of the power requirement of the drive motor, resulting in a deloading or loading thereof during cornering.
The known control and regulation device further comprises a constant running regulation means which serves for maintaining the respective set transmission ratios of the hydrostatic transmissions upon the occurrence of external disturbances. This constant running regulation means however only comes into effect during straight line travel, so that disturbances arising during cornering, as e.g. different loadings of the two hydrostatic transmissions, lead to undesired changes of the steering radius and the speed of travel. Further, the known control and regulation device has a limit load regulation means which is connected upstream of the constant running regulation means and thus acts upon the adjustment devices of the two hydrostatic transmissions by means of alterations of the control signals. As in general for reasons of stability a relatively slow control behaviour is set in the constant running regulation means, dynamic overloading of the drive motor or even a decelerating thereof to the point of standstill may be the consequence.
It is the object of the invention to further develop a control and regulation device of the kind mentioned in the introduction in such a way that undesired alterations of the speed of travel are hindered.
This object is achieved through the characterising features of claim 1. After formation of the min./max. window from desired values of the transmission ratios of the hydrostatic transmissions, set by means of the control levers, the control and regulation device according to the invention determines whether the previous speed of travel is to be maintained or altered, through comparison of the mean value--corresponding to the speed of travel--of the control signals output before the formation of the min./max. window with the minimum value and the maximum value of the min./max. window. In the first case, which arises if the mean value of the control signals output before the formation of the minimum/maximum window lies within the min./max. window, the control signals to be output are determined through addition or subtraction of the difference of the desired-value signals to or from the mean value of the control signals output before the formation of the minimum/maximum window. In the latter case, which arises if the mean value of the control signals output before the forming of the min./max. window lies outside the min./max. window, the control signals output before the forming of the min./max. window are corrected through addition of the difference between the minimum value of the min./max. window and the mean value of the control signals output before the forming of the min./max. window for the purpose of increasing the speed of travel, or through subtraction of the difference between the control signals output before the forming of the minimum/maximum window and the maximum value of the min./max. window for the purpose of reducing the speed of travel. In this way, on the one hand desired alterations of the speed of travel are made possible when travelling in a straight line and when also cornering, but on the other hand undesired alterations of the same are avoided and thereby the power requirement of the drive motor is at the same time kept largely constant or disturbing load variations of the same are hindered.
In practice, so-called one-lever control systems are known in which by means of a sing
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Hansen Kai-Uwe
Leibing Karl-Heinz
Vonnoe Reinhard
Brueninghaus Hyodromatik GmbH
Nguyen Hoang
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