Motors: expansible chamber type – With motive fluid valve – Contracting chamber exhaust valve controlled by expanding...
Patent
1984-09-27
1985-12-17
Cline, William R.
Motors: expansible chamber type
With motive fluid valve
Contracting chamber exhaust valve controlled by expanding...
92 85R, 92250, F15B 1108
Patent
active
045586306
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE PRESENT INVENTION
This invention relates to a hydraulic piston cylinder device comprising a cylinder, a piston dividing the cylinder into two cylinder spaces, and valve elements between the cylinder spaces and the respective pipes for actuation by a pressure medium.
When this kind of piston cylinder device is being used and the external actuating pressure stops, both valve elements are closed by springs whereby the piston cannot be moved by any external force in either direction because liquid cannot escape from either of the cylinder spaces. It would be sometimes necessary, however, that the pressing or tractive force of the cylinder is maintained even when the external actuating pressure is no longer present. For this purpose it is known to use a pressure accumulator in the hydraulic system. In most cases a separate pressure accumulator connected with hoses is sufficient, but sometimes such accumulator does not provide the required reliability. For example breaking of the hose between the piston cylinder and the accumulator stops the function of the accumulator. There are some events where such uncertain factor cannot be allowed, e.g.:
A retaining centralizer of the drill rod whereby the pressure accumulator prevents the dropping of drill rods into the hole if the external working pressure stops for some reason,
Different kinds of support devices, for instance the top supports of wagon drills,
Some brake systems.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improved hydraulic piston cylinder device and such cooperation of valve elements incorporated therewith, that the above-mentioned uncertain factor is eliminated.
This object is achieved through the present invention by the cooperation of piston parts having elastic means that is elastically compressible by means of the pressure of the cylinder and the valve elements which are coupled so that when one of them is closed, the other cannot be closed. If under these conditions the movement of the piston is stopped by an external obstacle before the piston has reached the end surface of the cylinder, the elastic means of the piston is elastically compressed, whereby it absorbs pressure energy. When the external actuating pressure stops and the valve member prevents the escape of pressure from the corresponding cylinder space, there prevails in the cylinder space the pressure caused by the compressible elastic means of the piston. The pressure exerts upon the piston rod a force which has the same direction as the force caused by the external actuating pressure before stopping. To make this force effective, it is necessary that the pressure can escape from the cylinder space on the other side of the piston. This is facilitated by the above-mentioned coupling of the valve elements, allowing only one of the valve members to be closed at a time.
One embodiment of the invention will be described in the following with reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The single FIGURE is a somewhat diagrammatic illustration which shows a partial crosscut of a piston cylinder device according to the invention, and of valve elements incorporated with it.
DETAILED DESCRIPTION
The piston cylinder device comprises a cylinder 1 which is divided by a piston 2 into two cylinder spaces A and B. The piston 2 is divided in the axial direction into two successive parts 21 and 22 which are separated by a space 6 and between which there is elastic material 3, e.g. rubber, plastic, a steel spring, or the like. The piston rod 5 is connected to the part 22, while the other part 21 is movable in relation thereto within the limits of the space 6 against the elastic material 3. The piston is moved to and fro inside the cylinder by means of pressure liquid which is fed by pipes 11 and 12 via a pilot controlled non-return valve 4. The pilot controlled non-return valve 4 comprises a movable poppet 8 in the middle of which there is piston 8' to move the poppet 8 according to which side of the piston 8' is
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Cline William R.
OY Tampella AB
Smith Randolph A.
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