GB2119441A - Combined fluid-pressure- operable rotary and linear actuator - Google Patents

Abstract

The actuator 1, which affords at least two modes of output movement, includes a main casing 6, an element 12 housed in the casing and having a shaft 2 rotatably supported by the casing, a piston 19 housed in and cooperable with the hollow part 18 of said shaft, and a piston rod 21 extending from said piston outwardly of the shaft. The casing 6 and element 12 are relatively-rotatable under fluid pressure applied thereto and the shaft 2 and the piston 19 are relatively- slidable under fluid pressure applied thereto. The hollow part 18 of the shaft with which the piston is cooperable is disposed within the overall length of said casing, or substantially so. The actuator is used in robotic machines. <IMAGE>

Description

SPECIFICATION Fluid-pressure-operable actuators This invention relates to fluid-pressure-operable actuators and more particularly to those affording at least two modes of output movement, for example those where a single output member is capable of both rotary and linear movement, or, where two output members are provided, one of which is capable of rotary movement and the other of linear movement.

Hitherto, such actuators have been somewhat heavy and cumbersome and not without mechanical complexity, thus imposing limitation on their application, particularly where they are required to be installed in confined locations.

The invention as claimed is intended to provide a remedy. It solves the problem of how to design a fluid-pressure-operable actuator, affording at least two modes of output movement, which is relatively light in weight, is not cumbersome and is well-suited for ready application in many fields including locations which are somewhat confined.

According to this invention .a fluid-pressureoperable actuator, affording at least two modes of output movement, includes a main casing, an element housed in said casing and having a shaft rotatably supported by the casing, a piston housed in and cooperable with a hollow part of said shaft, and a piston rod extending from said piston outwardly of said shaft, said casing and said element being relatively-rotatable under fluid pressure applied thereto, said shaft and said piston with its rod being relatively-slidable under fluid pressure applied thereto, and said part of said shaft with which said piston is cooperable being disposed within the overall length of said casing, or substantially so.

Preferably said hollow part of said shaft is in the form of a cylinder.

The piston and piston rod may be provided with a splined connectiori to said shaft and in consequence said casing and said- rod may be relatively-rotatable and relatively-axially-slidable under fluid pressure, thereby pro.ducing said two modes of output movement in combination.

Alternatively, and where said shaft is formed so as to extend substantially outwardly of said casing, said casing and said shaft are relativelyrotatable under fluid pressure, and, independently of such movement, said casing and said piston rod are relatively-axially-slidable under fluid pressure, so that said two modes of output movement are separate the one from the other.

The advantages offered by the invention are mainly that as a result of the disposition of said part of the shaft within the overall length of the casing, or substantially so, a relatively compact actuator construction is provided, and required fluid-pressure supply and return passages can be incorporated within the main casing itself thus eliminating the need for external pipes, other than the main supply and return pipes, which could otherwise give rise to installational difficulties with the actuator.

Three ways of carrying out the invention are described in detail below with reference to drawings which illustrate three specific embodiments, in which: Figure 1 is a cross-sectional side elevation of an actuator in accordance with the first embodiment, Figure 2 is a cross-sectional side elevation of an actuator in accordance with the second embodiment, and Figure 3 is a view of the output end portion of an actuator in accordance with the third embodiment. In Figure 1 the actuator shown includes a main casing 1 adapted to be secured to fixed structure and having a hollow shaft 2 mounted for rotary movement in bearings 3, 4.

The casing comprises three parts 5, 6, 7 which are held together by set screws 8, 9 and which, with the shaft, define an annular chamber 10 which houses a fixed radial vane 1 The shaft has a movable element comprising a radial vane 1 2 which is formed integrally therewith and disposed in the chamber 10, suitable sealing means 13,14 being carried by the fixed and movable vanes and arranged in sealing engagement with the walls of the chamber. This assembly forms the vane section 15 of the actuator.

The shaft 2 projects just beyond the left-hand end face 1 6 and the right-hand end face 1 7 of the casing 1. The major part of the interior of the shaft forms a cylinder 18 in which a hollow piston 1 9 is slidable. This forms the piston-and-cylinder section 20 of the actuator. The piston has a piston rod 21 which is partly hollow and which projects outwardly of the casing through a sealed opening 22 formed in a ring member 23 fast with the lefthand end portion of the shaft as shown. The righthand end portion of the interior of the shaft is closed by a plug member 24, held fast with the shaft by locking plugs 25. The member 24 has a splined rod 26 formed integrally therewith.This rod extends along and within the cylinder and its splines 27 engage splines 28 formed on the interior of the piston 19, so that the piston and its rod 21 are supported for sliding movement upon the rod 26.

The free end portion of the piston rod 21 is splined at 29 for suitable connection to associated apparatus (not shown) to be operated thereby.

The end faces 30, 31 of the members 23, 24 form stops whereby the cylinder 18 is disposed wholly within the overall length of the casing 1 and thus the stroke of the piston 19 is a little shorter than that overall length.

An inlet port 32 for the admission of pressure liquid to the actuator is provided in the part 5 of the casing 1, and an outlet port (not shown) for liquid exhausting from the actuator is suitably provided in another part of the casing. A suitable channel (also not shown) is provided in the casing structure which places the inlet port in communication with manually-operable control valve means (not shown). These valve means are intended to control the flow of pressure liquid into, and the exhaust of liquid from, the vane section 1 5 of the actuator and the piston-and-cylinder section 20 of the actuator either simultaneously, or, individually, as operational requirements demand.

To facilitate the passage of liquid to and from the section 20 of the actuator during rotative operation of the section 15, hydraulic muffs 33; 34, which include suitable ports 35; 36 and seals 37, 38; 39, 40, are provided between fixed casing structure and cylinder 1 8.

In operation, when liquid under pressure is directed by suitable adjustment of the control valve means into the vane section 15 of the actuator one of the two vane chambers expands and the other which is now open to exhaust contracts so that the movable vane 12 moves with respect to the fixed vane 11 and the shaft 2 turns in the appropriate direction. Since the shaft is fast with respect to the plug member 24 that member and its integral splined rod 26 turn likewise. Such turning movement is transmitted to the piston 19 and piston rod 21 through splines 27, 28, and thus the piston rod, which forms a single output member of the actuator, turns about its longitudinal axis.If it is required to effect linear, axial, movement of the piston rod 21 simultaneously with such turning movement, the valve means are set also to direct liquid under pressure through the appropriate muff 33, 34 to the desired side of the piston-and-cylinder section '20 while the other side is simultaneously placed in communication with exhaust. Hence the rod 21 is either caused to retract, whilst turning, inwardly of the'actuator casing or alternatively to extend, as selected by the valve means for appropriate control of the.apparatus being operated thereby.

If it is desired to cause operation of the section 20 while the vane section 15 is inoperative this can be achieved by suitable operation of the valve means.

With reference to the second embodiment shown in Figure 2, the actuator comprises a main casing 4,1 adapted to be secured to fixed structure and having a shaft 42 mounted for rotary movement in bearings 43, 44. The casing comprises three main parts 45, 46,47 which are held together by set screws 48,49 and which, with the shaft, define an annular chamber 50 which houses a fixed radial vane 51. The shaft has a movable element comprising a radial vane 52 which is formed integrally therewith and disposed in the chamber 50, suitable sealing means 53, 54 being carried by the fixed and movable vanes and arranged in sealing engagement with the walls of the chamber. This assembly forms the vane section- 55 of the actuator.

Bearing retention members 56, 57 are held fast by set screws 58, 59 with respect to the outer and faces of the parts 45, 47. At its right-hand end the shaft 42 terminates just short of the outer face 60 of the member 57 while at its left-hand end the shaft projects substantially outwardly of the outer face 61 of the member 56. being splined at 62 at its free end portion for suitable connection to associated apparatus (not shown) to be operated thereby.

The shaft 42 is provided with a bore of small diameter in relation to the external diameter of the shaft. This bore is blind at its right-hand end and in part forms a cylinder 63 in which a piston 64 is slidable. This forms the piston-and-cylinder section 65 of the actuator. The piston has a piston rod 66 formed integrally therewith which projects outwardly of the left-hand end portion of the shaft 42 through a gland ring assembly 67. At its free end portion (not shown) the rod 66 is suitably adapted for connection to associated apparatus (also not shown) to be operated thereby.

As with the construction of the first embodiment above described, control valve means and suitable porting are provided for controlling the flow of liquid under pressure into, and the exhaust of liquid from, the vane section 55 of the actuator and the piston-and-cylinder section 65 of the actuator. Hydraulic muffs 68; 69, which include suitable ports 70; 71 and seals 72,73; 74, 75, are provided between fixed casing structure and cylinder 63 to facilitate the passage of liquid to and from piston-and-cylinder section 65.

Depending upon requirements, the vane section 55 and the piston-and-cylinder section 65 can be operated simultaneously, or, alternatively one of them can be caused to operate individually while the other is stationary, or vice versa. When both sections are operating simultaneously the shaft 42 effects movement of its associated apparatus quite independently from movement of the apparatus associated with the-piston rod 66. the shaft 42 gnd rod 66 thus providing two separate output members for the actuator rather than a single, dual movement, output member-as-in the above-described first embodiment.

In a manner similar to the construction of the first embodiment above described, the cylinder 63 is disposed wholly within the overall length of casing 41, and here the stroke of piston 64 is substantially shorter than that overall length.

With reference now to the third embodiment shown in Figure 3, the actuator 71 is provided with three output motions. This actuator is similar to that shown in Figure 2, the rotary shaft 72 and linearly-movable piston rod 73 respectively providing'the first and second output motions. The third output motion is obtained by providing a link 74 which is pivotally-connected at 75, externally of the casing of the actuator, to an extension 76 of the shaft 72..This link is provided with a slot and pivot connection at 77 to the piston rod 73. The link 47 is of desired shape and is connectible at 78 to apparatus (not shown) to be operated by such further motion which therefore supplements the motions of the shaft 72 and rod 73. In this way the actuator can be arranged to operate three separate apparatuses.

Although in the embodiments above described with reference to the drawings the vane sections of the actuators each include a single fixed vane and a single movable vane, in alternative embodiments of the invention they may where desirable include two or more fixed vanes and two or more movable vanes.

Further, although in the embodiments above described with reference to the drawings the rotary sections of the actuators include assemblies having fixed and movable vanes, in alternative embodiments of the invention a plurality of radial sliding vanes may instead be provided, these being operable by suitable cam means so that the rotary section of each actuator is continuously turnable. Alternatively, and where such continuous turning is again required, the rotary section of the actuator may comprise a system of two or more intermeshing gears or lobed rotors which form a continuously-rotatable motor section. Yet again, but where only iimited angular movement is required of the rotary section of the actuator, that section may be of rack-and-pinion form, the rack being operable by linear piston-andcylinder means to effect the required turning movement.

Again, although in the embodiments above described with reference to the drawings the piston-and-cylinder section of the actuator is concerned solely with linear movement, in other embodiments helical means may be provided in the cylinder whereby both linear movement of the piston rod and angular movement thereof, about its longitudinal axis, are produced during its extension and retraction.In this case such angular movement would be additive to, or subtractive from, any turning moveinent effected by the rotary section of the actuator; Although in the embodiments above described with reference to the drawings each cylinder is disposed in its shaft wholly within the overall length of the casing, in alternative embodiments the construction may be such that each cylinder is instead substantially within the overall length of the casing with one end.portion or both end portions thereof extending by only a small amount beyond the overall length of the casing.

Further, although in the embodiments above described with reference to the drawings each main casing:is adapted to be secured to fixed structure and the shaft and piston rod are movable by liquid under pressure applied to the vane section and the piston-and-cylinder section of the actuator, in alternative embodiments of the invention the piston rod may be fast with fixed structure and/or said-shaft may be non-turnable in which case the main casing is turnable under fluid pressure about its longitudinal axis and/or movable linearly, being then suitably connected to associated apparatus to be operated thereby.

Alternatively, the relatively-rotatable casing and shaft may be so arranged that both are capable of movement, under fluid pressure applied thereto, in opposite directions accordingly to effect corresponding opposing movement of parts of associated apparatus to which they are respectively connected. Further such movement of parts of associated apparatus can be effected in similar manner.on relative sliding movement of said casing and piston rod in opposite directions.

In contrast to the embodiments above described with reference to Figures 2 and 3 where the shaft and the piston rod project substantially from the same end of the actuator, in alternative embodiments, and where installationai requirements s6 demand, the shaft may project substantially from one end of the actuator and the piston rod from the other end thereof.

In all the embodiments above described since each cylinder is disposed within the overall length of the actuator casing, or substantially so, and the stroke of the piston is accordingly thus confined within that length, or substantially so, an extremely compact actuator construction is provided. In consequence actuators in accordance with this invention are particularly suitable for application in confined locations where hitherto other forms of dual output actuator have been difficult to accommodate.

This invention can with advantage be applied in the field of robots, for example in robotic machines used in mass production of such products as motor vehicles and certain domestic appliances. In these cases the actuator may be mounted with its rotational axis disposed vertically, or substantially so.

Claims (16)

1. A fluid-pressure-operable actuator, affording at least two modes of output movement, including a main casing, an element housed in said casing and having a shaft rotatably supported by the casing, a piston housed-in and cooperable with a hollow part of said shaft, and a piston rod extending from said piston outwardly of said shaft, said casing and said element being relatively rotatable under fluid pressure applied thereto, said shaft and said piston with its rod being relatively slid able under fluid pressure applied thereto, and said part of said shaft with.which said piston is cooperable being disposed within the overall length of said casing, or substantially so.

2. An actuator as claime.d in claim 1, in which -said hollow part of said shaft is in the form of a cylinder.

3. An actuator as claimed in either claim 1 or claim 2, in which said piston and piston rod are provided with a splined connection to said shaft so that said casing and said rod are relatively rotatable and relatively-axially-slidable under fluid pressure, thereby producing said two modes of output movement in combination.

4. An actuator as claimed in either claim 1 or claim 2, in which said shaft is so formed as to extend substantially outwardly of said casing.

5. An actuator as claimed-in ciaim 4, in which said casing and said shaft are relatively-rotatable.

under fluid pressure, and, independently of such movement, said casing and said piston rod are relatively-axially-slidabie under fluid pressure, so that said two modes of output movement are separate the one from the other.

6. An actuator as claimed in any one of the preceding claims, in which said element housed in said casing and having said shaft includes a radial vane suitably sealingly-disposed in, and relativelyslidable with respect to, an annular chamber formed by said casing, a further radial vane being sealingly-disposed in said chamber and fixed with respect to said casing.

7. An actuator as claimed in either claim 4 or claim 5, in which a link is pivotally-connected, externally of said casing, to both said shaft and said piston rod, said link being suitably shaped and so adapted as to be connectible to apparatus required to be operated by a third mode of actuator output movement.

8. An actuator as claimed in any one of claims 2 to 7, in which helical means is provided in said cylinder whereby both linear movement of the piston rod and angular movement thereof, about its longitudinal axis, are produced during its extension and retraction.

9. A robotic machine having an actuator as claimed in any one of the preceding claims.

10. A robotic machine as claimed in claim 9, in which said actuator is mounted with its rotational axis disposed vertically, or substantially so.

11. An actuator substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

12. An actuator substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

13. An actuator substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

14. A robotic machine having an actuator substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

15. A robotic machine having an actuator substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

16. A robotic machine having an actuator substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.