Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1988-05-04
1990-02-20
Garrett, Robert E.
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
91376A, 91380, F15P 910
Patent
active
049016270
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic idling-regulating valve means for controlling movements of a machine element drivable by a hydraulic cylinder. The valve means includes at least two mechanically operated through-flow valves arranged in a casing and controlled, by the reciprocating movements of an actuating element, to move from a neutral central position with both valves closed into alternative directions into a flow position and closure position. An electromechanical specified-value setting system and a mechanical actual-value feedback system are provided for setting and/or controlling the specified and actual values of the instantaneous position of the pistons of the driving hydraulic cylinder. The specified-value setting system comprises a hollow shaft rotatably mounted in a housing of the valve means and reciprocable in the longitudinal direction. The hollow shaft rotates a number of revolutions correlated with the respective specified value, by electric motor provided for the purpose of controlling the specified value. The actual-value feedback device comprises a feedback spindle engageable, via an external thread, with an internal thread of the hollow shaft and which is coupled, by form-locking means, to move with a piston of the driving hydraulic cylinder either, when the connection with the piston is rigid, in such a manner that it follows any displacement of the latter or, in the case of a rotational connection with the piston, in such a manner that it performs a number of rotations correlated with the movements of the piston, in which case the valve-actuating member is subjected to the same displacements in the axial direction as the specified-value setting shaft, with the specified-value setting shaft being rotatably supported in the valve-actuating element which in turn is secured against rotation in the casing.
Idling-regulating valves of the aforementioned type have been proposed in DE-PS 20 62 134 and DE-OS 29 10 530, and are equipped with an electromechanical specified-value setting system and a mechanical actual-value feedback system for setting and/or controlling the specified and actual values of the instantaneous position of the pistons of the driving hydraulic cylinder. The specified-value setting system, which comprises a hollow shaft mounted to rotate in the housing of the valve and to reciprocate in the longitudinal direction, is rotatable a number of revolutions correlated with the respective specified value, by an electric motor provided for the purpose of controlling the specified value. The actual-value feedback system comprises a feedback spindle which, is in engagement via an external thread with an internal thread of the hollow shaft and which is movably coupled in a form-locking manner with the piston of the driving hydraulic cylinder either, when the connection with the piston is rigid, in such a manner that it follows any displacement of the latter or, in the case of a rotational connection with the piston, in such a manner that it performs a number of rotations correlated with the movements of the piston, in which case the valve-actuating member is subjected to the same displacements in the axial direction as the specified-value setting shaft, the latter being rotatably supported in the valve-actuating element which in turn is, however, secured against rotation in the casing. The casing in which the pressure tank and supply ducts leading to the individual through-flow valves as well as the consumer connection ducts leading from the valves to the controlled hydraulic cylinder are integrated, have been implemented heretofore as aluminium die-castings comprising the valve cores and bores accommodating the specified-value setting hollow shaft and the actual-value feedback spindle as well as the space for the valve-actuating element which can be described as being arranged between the valve cores and actuating the latter by a radially projecting actuating element.
However, a particular disadvantage of conventional idling-regulating valv
REFERENCES:
patent: 2370137 (1945-02-01), Biggert, Jr.
patent: 3315569 (1967-04-01), Dever
patent: 3797364 (1974-03-01), Schulze
patent: 4369693 (1983-01-01), Schulze
patent: 4633759 (1987-01-01), Schulze
Garrett Robert E.
Williamson Mark A.
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