GB1570333A

GB1570333A - Piston and cylinder actuator

Info

Publication number: GB1570333A
Application number: GB2069/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-06-25
Filing date: 1977-01-19
Publication date: 1980-06-25
Also published as: FR2356027A1; ES229525U; CH600168A5; ES229525Y; FR2356027B3; NL7700551A; SE7701067L; ATA42477A; BE855727A; YU154676A; AT364621B; DE2706163C2; YU37220B; IT1077792B; DE2706163A1

Description

(54) PISTON AND CYLINDER ACTUATOR (71) We, RADIVOJE MIRSOVIC, a Yugoslavian Citizen, of A. Stamboliskog 29, Belgrade 11000, Yugoslavia, and STANISLAV VICAR, a Yugoslavian Citizen, of Ptuj 62250, Mestni, Vrh 20, Yugoslavia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to fluid-operated piston and cylinder actuates for use in a wide variety of applications and using different operating fluids.

An object of the invention is to provide an improved piston and cylinder actuator.

According to the invention a piston and cylinder actuator comprises a tube having its ends closed by end walls, a piston movable along the tube between the end walls, means for introducing fluid to each side of the piston, an elongate flexible element connected to the piston and extending from opposite sides of the piston through opposite ends of the tube and over guide members at said ends of the tube, a driven element connected to the element externally of the tube, sealing means around the element and located in the ends of the tube for preventing discharge of the operating fluid from the tube, and lubricating means for lubricating the flexible element as it passes through the ends of the tube. Preferably the flexible element is a closed loop and is connected to the piston by wedge means.

Conveniently the driven element is a slide member slidable along the outside of the tube.

Further features of the invention will appear from the following description of an embodiment of the invention given by way of example only and with reference to the accompanying drawing in which: Fig. I is a longitudinal section through an actuator according to the invention, Fig. II is a side elevation of the actuator of Fig. I with a modified form of driven member, and Figs. III and IV are sections through the ends of the actuator of Figs. I and II to a larger scale.

Referring to the drawings, the actuator includes a tubular cylinder 1 internally of which a piston 4 is movable, the piston having a circular cross-section and seals 5.

The piston 4 is movable along the cylinder 1 between the ends of the cylinder which are defined by cylinder heads 6.

The piston 4 is connected to an elongate closed loop flexible element or band 2 by a wedging action through a wedge element 3, and the element 2 extends from each side of the piston through opposite ends of the cylinder 1 and around rollers 9 carried on each cylinder head 6. The element is then connected to a driven member 11 (Fig. I) in the form of a slide which moves along the outside of the cylinder parallel to the axis of the cylinder when the piston is moved. An item (not shown) to be powered is attached to the member 11.

An alternative form of the driven member is shown in Fig. II in which it takes the form of an annular ring 12.

Each of the cylinder heads 6 is formed with- an opening 13 for the introduction and discharge of operating fluid from the cylinder so that the piston can be driven in either direction. The rollers 9 are each carried on a shaft 10 journalled in roller bearings.

Centrally of each cylinder head 6 is formed an opening 14 through which the element 2 passes and in each opening is located an impregnated felt lubricating element 7 and a sealing element 8 for preventing operating fluid escaping through the aperture for the element 2. The sealing element 8 is in the form of a truncated cone and the arrangement is such that, using a flexible sealing element 8, the fluid pressure in the cylinder 1 causes the element to be contracted tightening the element 8 onto the flexible element 2 to thereby effect a seal. On the opposite side of the piston 4 the fluid is not under pressure and the flexible element 2 can easily pass out of the cylinder chamber.

The flexible element 2 has high tensile strength to transmit the driving force from the piston 4 to the driven member 11 or 12 and can be made of steel wire, nylon or other suitable material sufficiently flexible to pass around the rollers 9.

It will be appreciated that the driven member 11 or 12 will always move in the opposite direction to the piston 6 and that the overall length of the actuator is not appreciably greater than the stroke of the piston. Moreover the driving force on the member 11 or 12 is the same for a given pressure of the operating fluid whatever the direction of movement, and the length of the cylinder is substantially without limit.

The invention should find application in many situations where conventional piston and cylinder devices have previously been used for example in long vehicles, in operating doors, and in other situations particularly in applications where a long travel of the piston is required.

WHAT WE CLAIM IS: - 1. A piston and cylinder actuator comprising a tube having its ends closed by end walls, a piston movable along the tube between the end walls, means for introducing fluid to each side of the piston, an elongate flexible element connected to the piston and extending from opposite sides of the piston through opposite ends of the tube and over guide members at said ends of the tube, a driven element connected to the element externally of the tube, sealing means around the element and located in the ends of the tube for preventing discharge of the operating fluid from the tube, and lubricating means for lubricating the flexible element as it passes through the ends of the tube.

2. An actuator according to claim 1 where the flexible element is a closed loop and is connected to the piston by wedge means.

3. An actuator according to any one of the preceding claims wherein the flexible element is a wire.

4. An actuator according to any one of the preceding claims wherein the driven element is a slide member slidable along the outside of the tube.

5. An actuator according to claim 4 wherein the slide member is in the form of a ring encircling the tube.

6. An actuator according to any one of the preceding claims wherein the guide members are in the form of rollers.

7. An actuator according to any one of the preceding claims wherein the sealing means includes a flexible sealing element in the form of a truncated cone whose wider end faces the piston, the flexible element from the piston passing through the sealing element.

8. A piston and cylinder actuator substantially as described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. other suitable material sufficiently flexible to pass around the rollers 9. It will be appreciated that the driven member 11 or 12 will always move in the opposite direction to the piston 6 and that the overall length of the actuator is not appreciably greater than the stroke of the piston. Moreover the driving force on the member 11 or 12 is the same for a given pressure of the operating fluid whatever the direction of movement, and the length of the cylinder is substantially without limit. The invention should find application in many situations where conventional piston and cylinder devices have previously been used for example in long vehicles, in operating doors, and in other situations particularly in applications where a long travel of the piston is required. WHAT WE CLAIM IS: -

1. A piston and cylinder actuator comprising a tube having its ends closed by end walls, a piston movable along the tube between the end walls, means for introducing fluid to each side of the piston, an elongate flexible element connected to the piston and extending from opposite sides of the piston through opposite ends of the tube and over guide members at said ends of the tube, a driven element connected to the element externally of the tube, sealing means around the element and located in the ends of the tube for preventing discharge of the operating fluid from the tube, and lubricating means for lubricating the flexible element as it passes through the ends of the tube.