Motors: expansible chamber type – Working member position feedback to motive fluid control – With main valve position feedback to pilot valve
Patent
1996-05-09
1998-11-03
Lopez, F. Daniel
Motors: expansible chamber type
Working member position feedback to motive fluid control
With main valve position feedback to pilot valve
91380, 91368, F15B 910
Patent
active
058293361
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hydraulic drive unit with a hydraulic motor as a power drive, said motor being designed for a high drive power and accordingly (necessarily) high throughput of hydraulic oil, a main control valve by means of which an afflux of hydraulic oil under high pressure to the power drive, as well as the efflux of at least a portion of the hydraulic oil supplied to the power drive, for example to the zero-pressure supply container of the pressure supply assembly, can be controlled, a hydraulic servo drive designed as a double-acting linear cylinder for actuating the main control valve, and with an overtravel regulating valve, provided to control the servo drive, with setting of the setpoint of the position as well as the speed of movement of the movable element of the power hydraulic motor under electric motor control and mechanical feedback of the corresponding actual values, said valve assuming a blocking position corresponding to the stoppage of the power drive when the setpoint and actual value of the controlled position are the same, said blocking position being controllable by the position setpoint setting to assume the alternate through flow positions assigned to the alternate drive directions of the power hydraulic motor, in which positions the respective effective through flow cross section varies monotonically with the degree of deflection of the valve and is controllable by the position actual value feedback upon assumption of the blocking position, with the overtravel regulating valve and the main control valve being designed as piston slide valves operable by relative axial displacements of their valve pistons and housing elements that occur along axes that are parallel to one another, and the piston of the main control valve forms the housing of the overtravel regulating valve. In a known hydraulic drive unit of this type (U.S. Pat.) the overtravel regulating valve has a piston that is elongate and in the form of a rod, and is displaceable in a central axial through bore of the piston of the main control valve in a pressure-tight manner, said rod-shaped piston, viewed in the axial direction, traversing drive pressure chambers located on both sides of the main control valve piston, by whose alternate exposure to pressure and release, controllable by means of the overtravel regulating valve, produces the servo drive of the main control valve piston, with the piston of the overtravel regulating valve also having to be guided displaceably in a pressure-tight manner in the end walls forming the housing-integral axial limits of these two drive pressure chambers of the housing of the main control valve. One end of the piston of the overtravel regulating valve projects out of the housing of the main control valve and is firmly connected at this end with a rack meshing with a pinion of the electromechanical position setpoint setting and actual value feedback, said pinion being drivable by a differential gearbox that produces the phase comparison required for overtravel regulation.
The known drive unit, because of the design described above, suffers from at least the following disadvantages:
The manufacture of the assembly formed by the main control valve and the overtravel regulating valve is extremely expensive in view of the precision required for reliable function, since the bores of the housing of the main control valve that receive the respective end sections of the piston of the overtravel regulating valve and the central bore of its valve piston, with the required exactly flush arrangement, are very difficult to produce, and the exact arrangement of the controlling edges of the piston of the overtravel regulating valve with respect to the control edges of the piston of the main control valve, to the extent that the latter are supposed to have a zero overlap that is as exact as possible in the blocking position of the overtravel regulating valve, is also very expensive, with the result that the known drive unit suffers from high manufacturing costs.
It is also disadvantageous th
REFERENCES:
patent: 4161905 (1979-07-01), Ota
patent: 4901627 (1990-02-01), Schulze
Hartmann & Lammle GmbH & Co. KG
Lopez F. Daniel
LandOfFree
Hydraulic drive unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic drive unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic drive unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-679642