Expansible chamber devices – Mutually relatively movable cylinder or sleeve – member... – With additional cylinder relatively slidable exteriorly of...
Patent
1989-01-23
1991-02-12
Look, Edward K.
Expansible chamber devices
Mutually relatively movable cylinder or sleeve, member...
With additional cylinder relatively slidable exteriorly of...
92 75, 91173, 91189A, F01B 720
Patent
active
049914936
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a cylinder-piston combination actuated by a pressure medium. The combination has an out-stretched cylinder space and a two-part piston assembly so arranged that it will move in opposite directions in the axial direction of the cylinder space.
BACKGROUND OF THE INVENTION
In previously used solutions in this category, the pistons in the piston assembly are placed inside the cylinder space opposite to each other, with the piston rods protruding from opposite ends of the cylinder, the length of each rod equalling essentially half the length of the cylinder space Thus the maximum length of the combination is essentially twice that of the cylinder space. In many cases, this is not sufficient in view of the required change in the length, especially when the space available imposes restrictions on the maximum length and other dimensions of the cylinder space. Such a situation prevails especially in telescopic boom structures which should be extendable to a sufficient length when working and still be able to contract into a sufficiently compact form when at rest.
SUMMARY OF THE INVENTION
The object of the present invention is to propose a cylinder-piston combination which is extendable to a length essentially three times that of the cylinder space. None of the external dimensions of the combination differs substantially from the corresponding dimension of a conventional dual-piston cylinder. The combination has a simple structure and its control functions are easy to implement using normal control techniques.
The chief characteristics of the invention are as exposed in claim 1. Certain preferred embodiments are presented in the subclaims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is described with reference to the drawings attached. FIGS. 1-3 are longitudinal sectional views of one of the possible implementations in different phases.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 represents the cylinder-piston combination with the piston rods inside the cylinder, the combination being contracted to its minimum length The cylinder space 1 is constituted by a jacket tube 1a, preferably of a round sectional form. The first part 3 of the piston assembly--via the mediation of the outer piston 4 belonging to it--is in contact with the inside surface 2 of the jacket tube. The outer piston 4 is provided with sealings 5 between the piston and the inside surface 2. When the combination opens, the piston rod 6 of the first part 3 in FIG. 1 moves right and is pushed against the seal 7 belonging to the right-hand end flange 1b of the cylinder space 1. The piston rod 6 is of a tubular construction and its inner diameter corresponds to the diameter of the inner piston 9 belonging to the second part 8 of the piston assembly. In the closed position of the combination, the second part 8 is substantially inside the first part 3. The outer surface of the inner piston 9 is provided with several axial grooves 10. When the combination opens, the piston rod 13 of the second part 8 in FIG. 1 moves left and is pushed against the sealing 12 belonging to the left-hand end flange 1c of the cylinder space 1. The piston rod 13 may be either tubular, as in the present example, or a solid rod.
The combination also comprises an auxiliary piston 14, with sealings 15 between the piston and the inside surface 2 of the cylinder space 1. The auxiliary piston 14 is provided with a central opening 16 to allow the piston rod 13 of the second part 8 to move relative to the auxiliary piston 14. In addition, the auxiliary piston has a cut-out 17 whose dimensions essentially correspond to those of the inner piston 9, and one or more projections 18 and 19 or equivalent, preferably located on the end faces 20 and 21. The auxiliary piston 14 is also provided with a sealing 23 to seal the gap between itself and the piston rod 13. At the point of connection between the outer piston 4 and the piston rod 6 is a shoulder 24.
The jacket tube 1a of the cylinder space 1
REFERENCES:
patent: 3877349 (1975-04-01), Schindel
patent: 3945300 (1976-03-01), Bourges
Look Edward K.
Ryznic John
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