Actuators

Claim 2

A rotary actuator having a piston comprising a pair of similar opposed portions secured together to form a substantially planar vane-like member and peripheral sealing means extending around said member, a plane of jointing between said opposed piston portions being substantially coincident with a main central plane of the piston, a tubular recess being formed between said piston portions at one region of the piston, a shaft comprising bearing portions for mounting the piston in a rotary member extending into said tubular recess, and splines being provided on the shaft and on said opposed piston portions for interengagement to prevent rotation between the shaft and the piston portions, the shaft splines being formed by radially outwardly facing surfaces and the piston portion splines being formed by radially inwardly facing portions complementary to the shaft spline surfaces in engagement therewith, the splines on the two piston portions being confined to peripheral regions of the tubular recess remote from the plane of jointing.

Claim 3

A piston according to claim 1 wherein saiD portions of the member are of corresponding shape and abut each other whereby their plane of jointing is at the central plane of the piston.

Claim 4

A piston according to claim 1 wherein said sealing means comprise respective juxtaposed sealing rings, one engaged by each said portion of the vane-like member.

Claim 5

A piston according to claim 3 wherein said sealing rings are clamped together by said portions.

Claim 6

A piston according to claim 4 wherein keying means are provided to retain the sealing rings positively in position on their piston portions.

Claim 7

A piston according to claim 3 wherein the sealing rings are permanently secured onto their respective piston portions.

Claim 8

A piston according to claim 3 wherein each sealing ring has a cross-section comprising a wing portion projecting obliquely away from the periphery of the piston and from the juxtaposed sealing ring whereby the sealing rings provide a double line of sealing around the piston.

Claim 9

A piston according to claim 3 wherein the piston portions are of cast or moulded form and mounting means for the sealing rings are embodied in said portions in the casting or moulding operation.

Claim 10

A rotary actuator piston comprising a pair of opposed rigid plane members secured together to form a substantially planar vane, a plane of jointing of each of said plate members being substantially coincident with a main central plane of the vane, a peripheral recess being provided on each of said plate members facing onto said plane of jointing, respective flexible sealing rings being engaged in said peripheral recesses, each sealing ring having a transverse cross-section comprising a first limb seating in the recess and a second limb projecting obliquely from said first limb peripherally outwardly and away from said plane of jointing to project peripherally outwardly of the piston plate members, a shaft being held between said plate members with the shaft axis substantially in said central plane, opposite ends of the shaft projecting from the vane and bearing portions being provided on said projecting ends for mounting the piston in a rotary manner, a series of axially directed splines being provided on the shaft between said projecting ends and a formation of splines being provided on respective opposed regions of the plate members for engagement with a plurality of the shaft splines on diametrically opposite portions of the shaft to secure the vane non-rotatably to the shaft, said formation of splines on each plate member being confined to a region spaced from the plane of jointing of the member, the individual splines of said formation having radially outwardly convergent faces and said faces being disposed at angles not more than 90* to the plane of jointing.

Claim 11

A rotary actuator piston comprising a pair of opposed rigid plane members secured together to form a substantially planar vane, a plane of jointing of each of said plate members being substantially coincident with a main central plane of the vane, a peripheral recess being provided on each of said plate members facing onto said plane of jointing, respective flexible sealing rings being engaged in said peripheral recesses, each sealing ring having a transverse cross-section comprising a first limb seating in the recess and a second limb projecting obliquely from said first limb peripherally outwardly and away from said plane of jointing to project peripherally outwardly of the piston plate members, a shaft being held between said plate members with the shaft axis substantially in said central plane, opposite ends of the shaft projecting from the vane and bearing portions being provided on said projecting ends for mounting the piston in a rotary manner, a series of axially directed splines being provided on the shaft between said projecting ends and a formation of splines being provided on respective opposed regions of the plate members for engagement with a plurality of the shaft splines on diametrically opposite portions of the shaft to secure the vane non-rotatably to the shaft, said formation of splines on each plate member being confined to a region spaced from the plane of jointing of the member, the individual splines of said formation having radially outwardly convergent faces and said faces being disposed at angles not more than 90* to the plane of jointing.

Claim 12

A piston according to claim 3 wherein the respective sealing rings disposed peripherally of the piston portions extend along radially opposite sides of the shaft periphery for each to form a continuous line of sealing around the piston periphery.

Claim 13

A rotary actuator having a piston comprising a pair of similar opposed portions secured together to form a substantially planar vane-like member, the joint between said opposed portions being substantially co-incident with a main central plane of the piston, a tubular recess being formed between said portions, the axis of said recess lying in said central plane and being laterally offset towards one side edge of the planar member, a shaft comprising bearing portions for mounting the piston in a rotary manner being held in said recess between said opposed portions to project from opposite ends thereof, and peripheral sealing means extending around said vane-like member and the shaft projections at opposite ends of the recess, a series of axially directed and radially outwardly tapered splines being provided on the portion of the shaft in the recess, respective diametrically opposite portions of the recess being provided with series of splines of complementary form to said shaft splines, said recess splines being confined to portions of the recess surface remote from said central plane.

Claim 14

A rotary actuator having a piston comprising a pair of similar opposed portions secured together to form a substantially planar vane-like member, the joint between said opposed portions being substantially co-incident with a main central plane of the piston, a tubular recess being formed between said portions, the axis of said recess lying in said central plane and being laterally offset towards one side edge of the planar member, a shaft comprising bearing portions for mounting the piston in a rotary manner being held in said recess between said opposed portions to project from opposite ends thereof, and peripheral sealing means extending around said vane-like member and the shaft projections at opposite ends of the recess, a series of axially directed and radially outwardly tapered splines being provided on the portion of the shaft in the recess, respective diametrically opposite portions of the recess being provided with series of splines of complementary form to said shaft splines, said recess splines being confined to portions of the recess surface remote from said central plane.