GB2051957A

GB2051957A - Fluid Operated Piston and Cylinder Device

Info

Publication number: GB2051957A
Application number: GB8019405A
Authority: GB
Original assignee: DOBLJEKAR M
Current assignee: DOBLJEKAR M
Priority date: 1979-06-19
Filing date: 1980-06-13
Publication date: 1981-01-21
Also published as: FR2459392A1; NL8001376A; SE8001744L; YU143979A; DE3005193A1; IT1194656B; IT8021959A0

Abstract

A piston and cylinder device has two cylinders (1, 2) each with a piston (4, 5) and one of the cylinders (1) is of larger diameter than the other (2). The pistons are interconnected by flexible transmission means (3) which passes over guide means (12) at the ends of the cylinders. The cylinders are interconnected by common cylinder heads (10) in which the guide means are located. The guide means are associated with output shafts (13) by which movement of the pistons provides movement of a driven member. An arrangement is described, Fig. 5 (not shown) whereby self tensioning of the flexible transmission means occurs in use of the device. <IMAGE>

Description

SPECIFICATION Fluid Operated Piston and Cylinder Device This invention relates to fluid-operated piston and cylinder devices in which movement of the piston is transmitted by flexible drive means.

Recently piston and cylinder devices without conventional piston rods have come to the fore because such devices can be installed where conventional devices cannot be accommodated and because a long stroke device of compact design can be provided. At the present time such devices are used in industrial automation where the power requirements are relatively small and compressed air of up to 10 bar is available.

Where a flexible element is connected to the piston this is usually in the form of a steel wire or cable which is led out of the cylinder over guide rollers. Such an arrangement gives rise to problems regarding seals for the wire or cable and there are limitations in the form of the flexible element that can be used, in particular in providing an element with small turning radius when passing over guide rollers.

An object of this invention is to provide a fluidoperated piston and cylinder device which obviates these disadvantages.

According to the invention a fluid-operated piston and cylinder device comprises a first and a second cylinder, the first cylinder being of larger diameter than the second cylinder, a first piston movable in the first cylinder and a second piston movable in the second cylinder, flexible transmission means connecting the first and second pistons and passing over guide means, common cylinder heads for the first and second cylinders whereby the cylinders are in fluid communication with one another, the guide means being located in the cylinder heads, and at least one power output shaft associated with the guide means.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with references to the drawings, in which: Figure 1 is a side elevation partly in section, Figure 2 is a side elevation in the direction of arrow X in Figure 1, Figure 3 is a cross-section on the line A-A in Figure 2, Figure 4 is a cross-section on the line B-B in Figure 2, and Figure 5 is a longitudinal cross-section of a modification to one end of the device of Figures 1-4.

Referring to the drawings and firstly to Figures 1-4 a fluid-operated piston and cylinder device includes a first large diameter cylinder 1 and a second small diameter cylinder 2 parallel to and closely spaced from the cylinder 2. A piston 4 is movable along the first cylinder 1 and a piston 5 is movable along the second cylinder 2.

A tranmission element 3 is in two parts each of which is connected at one end to the piston 4 through a connection 8 and at the other end to the piston 5 through a connection 9. The piston 4 is provided with sealing rings 6 and the piston 5 with sealing rings 7.

The transmission element 3 passes over rollers, pulleys, sprockets or the like 12 at each end of the cylinders 1 and 2 and each roller 12 is mounted on a shaft 13 located in seals 15, the outer ends of the shafts 13 each extending outwardly to carry a sprocket 14 on each end. A chain or toothed belt 16 pass around pairs of sprockets 14. The rollers 12 are located in the operating fluid in cylinder heads 10 at the ends of the cylinder and the cylinder heads 10 provide communication of operating fluid between the cylinders 1 and 2. Openings 11 are provided in the cylinder heads to admit and discharge operating fluid to the cylinder heads and thence to the cylinders.

The device operates as follows. Operating fluid is admitted to one or other of the cylinder heads 10 to drive the pistons in one or other direction.

Due to the different sizes of the pistons and associated cylinders the large piston 4 is driven in one or other direction drawing with it the smaller piston 5 due to the connection 13 between the pistons.

The linear movement of the pistons is converted to rotary motion at the output shafts 13 and the motion can be utilised in rotary motion at the shafts 13 or as linear motion by movement of the chains 1 6. Thus the item to be moved (not shown) is attached to the shaft or shafts 13 or to the chain or chain 16.

Referring now to Figure 5 the cylinder heads 10 or one cylinder head 10 of the Figures 1 4 embodiment may be constructed to provide a self-tightening action of the element 13 and the chains 1 6. In this arrangement the cylinders 1 and 2 are movably located in bores in the cylinder head and are sealed by seals 1 9. A spring flange 20 and a supporting flange 1 8 hold the cylinder head 10 by means of a screw 22 and screw nuts 23 and 24. The nuts 23 serve to pretension the chain 3 and the nuts 24 and a cup spring 25 make self-tensioning under the action of the fluid in the cylinders possible. The supporting flange 1 8 is held against the spring flange 20 by the nuts 23 by means of the screw 22 and the cup springs 25. On overcoming the elastic force of the cup springs the cylinder head 10 can move to bring about self tensioning of the chain 3.

Claims

1. A fluid-operated piston and cylinder device comprising a first and a second cylinder, the first cylinder being of larger diameter than the second cylinder, a first piston movable in the first cylinder and a second piston movable in the second cylinder, flexible transmission means connecting the first and second pistons and passing over guide means, common cylinder heads for the first and second cylinders whereby the cylinders are in fluid communication with one another, the guide means being located in the cylinder heads, and at

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fluid Operated Piston and Cylinder Device This invention relates to fluid-operated piston and cylinder devices in which movement of the piston is transmitted by flexible drive means. Recently piston and cylinder devices without conventional piston rods have come to the fore because such devices can be installed where conventional devices cannot be accommodated and because a long stroke device of compact design can be provided. At the present time such devices are used in industrial automation where the power requirements are relatively small and compressed air of up to 10 bar is available. Where a flexible element is connected to the piston this is usually in the form of a steel wire or cable which is led out of the cylinder over guide rollers. Such an arrangement gives rise to problems regarding seals for the wire or cable and there are limitations in the form of the flexible element that can be used, in particular in providing an element with small turning radius when passing over guide rollers. An object of this invention is to provide a fluidoperated piston and cylinder device which obviates these disadvantages. According to the invention a fluid-operated piston and cylinder device comprises a first and a second cylinder, the first cylinder being of larger diameter than the second cylinder, a first piston movable in the first cylinder and a second piston movable in the second cylinder, flexible transmission means connecting the first and second pistons and passing over guide means, common cylinder heads for the first and second cylinders whereby the cylinders are in fluid communication with one another, the guide means being located in the cylinder heads, and at least one power output shaft associated with the guide means. Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with references to the drawings, in which: Figure 1 is a side elevation partly in section, Figure 2 is a side elevation in the direction of arrow X in Figure 1, Figure 3 is a cross-section on the line A-A in Figure 2, Figure 4 is a cross-section on the line B-B in Figure 2, and Figure 5 is a longitudinal cross-section of a modification to one end of the device of Figures 1-4. Referring to the drawings and firstly to Figures 1-4 a fluid-operated piston and cylinder device includes a first large diameter cylinder 1 and a second small diameter cylinder 2 parallel to and closely spaced from the cylinder 2. A piston 4 is movable along the first cylinder 1 and a piston 5 is movable along the second cylinder 2. A tranmission element 3 is in two parts each of which is connected at one end to the piston 4 through a connection 8 and at the other end to the piston 5 through a connection 9. The piston 4 is provided with sealing rings 6 and the piston 5 with sealing rings 7. The transmission element 3 passes over rollers, pulleys, sprockets or the like 12 at each end of the cylinders 1 and 2 and each roller 12 is mounted on a shaft 13 located in seals 15, the outer ends of the shafts 13 each extending outwardly to carry a sprocket 14 on each end. A chain or toothed belt 16 pass around pairs of sprockets 14. The rollers 12 are located in the operating fluid in cylinder heads 10 at the ends of the cylinder and the cylinder heads 10 provide communication of operating fluid between the cylinders 1 and 2. Openings 11 are provided in the cylinder heads to admit and discharge operating fluid to the cylinder heads and thence to the cylinders. The device operates as follows. Operating fluid is admitted to one or other of the cylinder heads 10 to drive the pistons in one or other direction. Due to the different sizes of the pistons and associated cylinders the large piston 4 is driven in one or other direction drawing with it the smaller piston 5 due to the connection 13 between the pistons. The linear movement of the pistons is converted to rotary motion at the output shafts 13 and the motion can be utilised in rotary motion at the shafts 13 or as linear motion by movement of the chains 1 6. Thus the item to be moved (not shown) is attached to the shaft or shafts 13 or to the chain or chain 16. Referring now to Figure 5 the cylinder heads 10 or one cylinder head 10 of the Figures 1 4 embodiment may be constructed to provide a self-tightening action of the element 13 and the chains 1 6. In this arrangement the cylinders 1 and 2 are movably located in bores in the cylinder head and are sealed by seals 1 9. A spring flange 20 and a supporting flange 1 8 hold the cylinder head 10 by means of a screw 22 and screw nuts 23 and 24. The nuts 23 serve to pretension the chain 3 and the nuts 24 and a cup spring 25 make self-tensioning under the action of the fluid in the cylinders possible. The supporting flange 1 8 is held against the spring flange 20 by the nuts 23 by means of the screw 22 and the cup springs 25.On overcoming the elastic force of the cup springs the cylinder head 10 can move to bring about self tensioning of the chain 3. Claims

1. A fluid-operated piston and cylinder device comprising a first and a second cylinder, the first cylinder being of larger diameter than the second cylinder, a first piston movable in the first cylinder and a second piston movable in the second cylinder, flexible transmission means connecting the first and second pistons and passing over guide means, common cylinder heads for the first and second cylinders whereby the cylinders are in fluid communication with one another, the guide means being located in the cylinder heads, and at least one power output shaft associated with the guide means.

2. A piston and cylinder device according to Claim 1 wherein the transmission means is in the form of two elements each connected at one end to the first piston and at the other end to the second piston and each passing around guide means, the respective guide means being located at opposite ends of the cylinders.

3. A piston and cylinder device according to Claim 1 or 2 wherein the guide means is in the form of a roller or rollers about which the transmission means passes, the roller or rollers being located in the operating fluid for the pistons.

4. A piston and cylinder device according to Claim 1, 2 or 3 wherein the guide means is rotatable with a shaft which extends outwardly of the cylinder head for connection to driven means.

5. A piston and cylinder device according to Claim 4 wherein the drive means includes a sprocket about which a chain or other drive element passes.

6. A piston and cylinder device according to any one of the preceding claims wherein at least one of the cylinder heads is axially movably received in the cylinders and is spring-biased outwardly of the cylinders to maintain the transmission means under tension.

7. A piston and cylinder device according to any one of the preceding claims wherein the positions of the pistons in the cylinders corresponds to the position of rotation of the output shaft.

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