GB2071254A

GB2071254A - Remote control mechanisms

Info

Publication number: GB2071254A
Application number: GB8106948A
Authority: GB
Original assignee: Bowden Controls Ltd
Current assignee: Bowden Controls Ltd
Priority date: 1980-03-12
Filing date: 1981-03-05
Publication date: 1981-09-16
Also published as: GB2071254B

Abstract

A Bowden-type mechanism having a conduit 23 with an inner liner 26 and a longitudinally slidable inner member 30 has an end sealing member 27 for preventing ingress of moisture. The liner 26 is arranged to project from the end of the conduit and the sealing member 27 which is secured to the end of the conduit is formed so that one portion of such member makes sealing contact with the projecting end of the liner while another portion of the sealing member makes sealing contact with the inner member 30. <IMAGE>

Description

SPECIFICATION Remote control mechanisms This invention relates to flexible remote control mechanisms comprising a flexible conduit within which there is an inner member which is longitudinally displaceable relative to the conduit.

It is known to provide such mechanisms with a conduit liner of synthetic polymeric material. Such a liner can be an integral part of the conduit or a separateiy fabricated inserted component. The presence of a liner is advantageous for reducing static and sliding friction and so improving the efficiency of the mechanism.

It is desirable to provide some means for reducing the risk of the performance of the mechanism becoming impaired by the entry of foreign matter, e.g. water, between the relatively sliding surfaces. If the conduit comprises a tube formed by one or more helically wound wires and this wound wire tube is not externally covered, the presence of a liner as above referred to can serve as a barrier preventing foreign matter which may pass between neighbouring convolutions of such wire(s) from gaining access to the inner member of the control mechanism. It is however in any case desirable to provide some form of sealing means at one or each end of the mechanism. The present invention provides a mechanism incorporating a very simple but effective end sealing arrangement.

According to the present invention, a flexible remote control mechanism comprising a flexible conduit with an integral or separate liner of synthetic polymeric material within which there is a relatively longitudinally displaceable forcetransmitting inner member, is characterised in that at least one end region of the mechanism an end portion of the liner projects from the conduit or from the surrounding layer(s) of the conduit as the case may be and the conduit has attached thereto a flexible sealing bush of elastically deformable material, which bush at one portion of its length surrounds and makes sealing contact with the projecting end portion of the liner and at another portion of its length surrounds and makes sealing contact with the said inner member.

The invention can be applied with advantage for example to mechanisms wherein the conduit comprises an externally uncovered tube formed by one or more helically wound wires. In this case, while water may pass inwardly between neighbouring wire convolutions in such tube, any water which reaches the interior of the tube at an end thereof where there is sealing arrangement according to the invention cannot flow directly inwardly past an end of the liner. Access of such water to the interior of the liner is obstructed by the sealing engagement of the sealing bush with the periphery of the axially projecting portion of the liner. It is a simple matter to ensure than such sealing engagement is effective. The projecting portion of the liner may for example be a tirm push fit in the receptive portion of the sealing bush.

Preferably the sealing bush is made of rubber or another elastomeric material, e.g. neoprene.

For forming an effective water-tight seal between the sealing bush and the inner member of the control mechanism, the inner member should present an uninterrupted surface to the sealing bush. If the inner member comprises a flexible cable of stranded wire construction the surface grooves of the cable can be filled by a wax or other suitable lubricant (see e.g. United Kingdom Patent No. 978.315).

In preferred embodiments of the invention the inner member comprises a force-transmitting core, e.g. a stranded wire cable as above mentioned, having a coating or sheath of synthetic polymeric material, e.g. nylon or high density polyethylene, the coating or sheath having a smooth continuous outer surface.

The inner member of the control mechanism may be flexible over its entire length or at least one end portion can comprise a rigid rod (see United Kingdom patent No 1 409 528) which makes sliding sealing contact with a sealing bush on the corresponding end of the conduit.

The flexibility of the sealing bush is a factor of importance because the portion of the sealing bush which projects from the end of the conduit can be deflected responsive to directional changes which may be imposed on the said contacting portion of the inner member during operation of the mechanism. The said projecting portion of the sealing bush may be tapered away from the end of the conduit to make that projecting portion more flexible.

Preferably the sealing bush is shaped with one or more annular sealing ridges which make the sealing contact with the inner member.

The sealing bush may be directly or indirectly connected to the conduit. As an example of an indirect connection, the end of the conduit may carry a rigid ferrule which may be swaged, crimped or otherwise secured to the conduit, and the sealing bush may be connected to such ferrule, either permanently as for example by bonding, or releasably as for example by frictional inter-engagement of the two components.

In certain embodiments of the invention, the sealing bush is an integral part of an elastically deformable body which can bear against a fixture or other part for transmission thereto of axial forces imposed on the conduit during operation of the mechanism. Such a body can serve as a noisedamper which prevents or restricts noise transmission via the conduit to said fixture or other part.

In some mechanisms according to the invention the sealing bush is directly connected to the conduit. An end portion of the conduit is accommodated in one end portion of the sealing bush. The bush may be held in place by frictional grip of the conduit, by a bonding medium, and/or by interlocking engagement. Because of the sealing engagement between the sealing bush and the projecting end portion of the liner, any water penetrating along the joint between the sealing bush and the exterior surface of the conduit cannot flow past the end of the liner. It is nevertheless preferred for the bush to seal or to be sealed water tightly to the conduit.

In certain very advantageous embodiments of the invention, the sealing bush is shaped with a female screw portion which is screwed onto an end portion of the conduit. Preferably said end portion of the conduit has a mating external male screw profile formed by one or more helically wound wires. In these circumstances the formation of a water-tight joint between the conduit and the sealing bush is facilitated. A watertight joint can be achieved by ensuring a sufficiently firm sealing contact between the interengaging male and female screw profiles. Such contact can be ensured by appropriate choice of the dimensions of ths female screw profile of the sealing bush and/or by use of a constraining or clamping ring as hereinafter exemplified. The sealing can be improved if necessary by means of a sealing substance between the inter-engaging surfaces.An adhesive can be used to prevent unscrewing.

An effective screw engagement between an elastically deformable sealing bush and the exterior of a wound wire conduit is easier to achieve if the male thread on the conduit is a deep thread. A very satisfactory male screw for directly receiving the sealing bush can be formed if the conduit comprises helically interwound wires of different cross-sections as described in United Kingdom Patent specification No 1 409 526.

Control mechanisms wherein a sealing bush is in screw engagement with a male screw profile at the surface of the conduit and also makes sealing contact with the inner member of the control mechanism have important advantages.

Certain embodiments of the invention, selected by way of examples, will now be described with reference to the accompanying diagrammatic drawings, in which: Fig. 1 is a part cross-sectional elevation of part of one mechanism according to the invention Fig. 2 is a cross-sectional elevation of part of a second mechanism according to the invention; Fig. 3 is a perspective view, partly in section, of a third mechanism according to the invention; and Fig. 4 is a part sectional elevation of part of a fourth mechanism according to the invention.

The mechanism which is the subject of Fig.1 comprises a noise damping component 1 made of an elastomer and a damper support 2 moulded from plastics, for example nylon. The damping component comprises an annular base portion 3 and an integral bush 4 and has an axial bore for the passage of the inner member for example the stranded wire cable, of the flexible remote control mechanism. The bore is stepped over a portion of the length of the component to provide a portion of largest diameter which receives a spigot 5 which is an integral part of the support 2. The support has a flange 6 against which the damping component seats when the two components are combined as illustrated. The spigot 5 of the support can be a tight push fit in the largest diameter portion of the bore of the damping component and reliance can be made on this friction coupling.An adhesive can however be used if required. The support has a bore for the passage of the inner member of the control mechanism and is counter-bored at its free end to receive an end portion of the conduit 7 of the mechanism which conduit is formed by helically interwound wires (e.g. is of the type generally known as "Bowdenex"). The support 2 can be secured to said conduit by a force fit, by adhesive, by screw engagement, by swaging or in any other suitable manner.

Within the conduit 7 there is a liner 8 of synthetic polymeric material which projects from the end of the conduit, through the bore of the support 2 and into a medial portion of the length of the bore of the damping component. The liner is a close press fit in that medial portion of the damper bore, so providing a peripheral contact seal. The end of the liner 8 can abut against the radial shoulder at the end of the said medial portion of the damper bore, or it can stop short of that shoulder. In conformity with practice known per se she conduit 7 is swaged at one ore more places along its length in order to grip the liner 8.

The liner is therefore held against longitudinal displacement out of the damping component.

The bore in the damping component is shaped to provide ridges such as 9,91 which bear elastically against the inner member (not shown) of the control mechanism and form a seal against the ingress of foreign matter.

The damping component accordingly has a dual function. It serves for noise damping, and it provides a sealing bush which makes sealing contact with both the inner member of the mechanism and the conduit liner. Such sealing contact prevents ingress of foreign matter between the inner member and the liner, either via the free end of ths sealing bush or via a path through the wound wire conduit and around the end of the liner. The inner member preferably comprises a stranded wire cable enveloped by a continuous water impervious covering.

The damping bush 4, being flexible, allows the inner member of the control mechanism to be pulled along a path which curves away from a straight prolongation of the axis of the spigot 5.

In a preferred embodiment the damping component is also shaped with an annular protrusion 10 as shown in broken line, the protrusion being spaced from the base portion 3 so as to define a peripheral groove 1 The device can then be connected to an apertured plate or other extraneous part by inserting the spigot portion of the damping component into the aperture until a marginal portion of that part, surrounding the aperture, enters such groove.

The spigot 5 of the damper support 2 extends to the end of the counter-bore in the damping component. This is not essential. The said spigot, can be shorter, for example so as to allow easier radial contraction of the damper spigot when engaging the groove 11 (if provided) with a plate or other extraneous part. The external chamfer or radius on the free end of the support spigot is helpful in allowing fiexure of the bush 4 to take place without very abrupt directional change or high contact pressure with the said support at the region of that end.

The mechanism of which a part is shown in Fig.2 comprises a plastics damper support in the form of a cup or casing 12. The casing has a hub having a bore with an enlarged portion 1 3 for recieving an end portion of the conduit 14 of a control mechanism and a portion 1 5 of smaller diameter for the passage of the conduit liner 1 6 and the inner member (not shown) of such mechanism. The device also comprises a damping component 17 comprising a body of elastomeric material which has a bore for the reception of the said liner and said inner member. A portion 18 of this bore is of a diameter such that it fits onto the inner end portion of the hub of the support. The component 1 7 and the support 12 can be held together by friction and/or adhesive.

Adjacent the portion 1 8, the bore of the damping component is of a diameter for receiving and making peripheral sealing contact with the end portion of the liner 16 and the outer end portion of the damping component is shaped to provide annular sealing ridges 1 9, 20 for sealing against the periphery of the inner member of the control mechanism.

The damping component also has a peripheral groove 21 for receiving a marginal portion of a panel or other fixture surrounding an aperture through which the damping component is inserted. In order to facilitate this insertion, an annular slot 22 is present in the damping component, surrounding its longitudinal axis, so that the surrounding portion of the damping component can be more easily radially contracted.

The outer end portion of the bore of the damping component could be of uniform diameter for sealing against the inner member of the control mechanism instead of being formed with annular sealing ridges, but the formation of such ridges which provide axially spaced annular sealing zones is preferred.

Fig. 3 shows a mechanism according to the invention wherein the conduit 23 is formed by helically interwound wires 24,25 of different cross sections. The wire 24 forms the thread and tlje wire 25 forms the root of a male screw. In accordance with the invention claimed in UK Patent No 1 409 526 a female adjustment member can be provided which makes direct screw engagement can be screwed to any adjusted position along the conduit.In accordance with the present invention the mechansim incorporates a conduit liner 26 which projects from an end of the conduit and a sealing bush 27 or elastically deformable material, e.g. rubber or neoprene, is connected to the end of the conduit and makes direct sealing engagement with the periphery of such liner and with the periphery of the inner member 28 of the mechanism, which member comprises a stranded wire cable 29 sheathed by a layer 30 of a polymeric material, e.g. nylon or polytetrafluoroethylene. The sealing bush 27 is formed over part of its length with an internal screw profile so that it can be screwed onto the end of the conduit. A very effective water-tight seal between the sealing bush and the periphery of the conduit can easily be formed by such screw connection if required.The outer end portion of the bush which projects from the end of the conduit is tapered to make it more flexible for allowing flexure of the enveloped portion of the core.

The sealing bush 27 can be pre-fitted with a metal or plastics constraining ring 31 as shown in broken line. The ring can be secured to the bush by adhesive. When the bush with its attached constraining ring is screwed onto the conduit 23, the ring prevents radial expansion of that portion of the bush which is within the ring and consequently the bush is forced to grip the conduit more tightly. Instead of using a constraining ring, a clamping ring can be employed which is crimped or otherwise tightened onto the bush after this has been screwed onto the conduit.

Fig.4 shows a mechanism according to the invention wherein a metal ferrule 32 is swaged onto an end of the flexible conduit (not shown).

The outer end portion of the ferrule is shaped to provide a spigot portion 33 having at its root a peripheral annular groove. An elastomeric sealing bush 34 having an internal annular bead 35 at its inner end is fitted over that spigot so that such bead is accommodated in the said annular groove.

The sealing bush makes sealing contact with the periphery of the plastics conduit liner 36, which projects from the corresponding end of the conduit, and with the sheathed stranded wire cable forming the inner member 37 of the mechanism.

In any mechanism according to the invention wherein a liner component separate from the conduit is provided, the liner can be held against axial movement relative to the conduit and against axial withdrawal from the sealing bush by slightly localiy contracting the conduit as previously referred to.

The liner need not however be a separate component. It can be an integral part of the conduit as formed, or it can be united with the conduit after production thereof.

Claims

1. A flexible remote control mechanism comprising a flexible conduit with an integral or separate liner of synthetic polymeric material within which there is a relatively longitudinally displaceable force-transmitting inner member characterised in that at least one end region of the mechanism an end portion of the liner projects from the conduit or from the surrounding layer(s) of the conduit as the case may be and the conduit has attached thereto a flexible sealing bush of elastically deformable material, which bush at one portion of its length surrounds and makes sealing contact with the projecting end portion of the liner and at another portion of its length surrounds and makes sealing contact with the said inner member.

2. A mechanism according to claim 1 , wherein the inner member comprises a core having a coating or sheath of synthetic polymeric material providing a smooth continuous surface which is contacted by the sealing bush.

3. A mechanism according to claim 1 or 2, wherein the sealing bush is shaped with one or more annular sealing ridges which make the sealing contact with the inner member of the mechanism.

4. A mechanism according to any preceding claim, wherein the sealing bush is an integral part of an elastically deformable body which can bear against a fixture or other part for transmission thereto of axial forces imposed on the conduit during operation of the mechanism.

5. A mechanism according to any preceding claim, wherein the sealing bush is directly connected to the conduit of the mechanism.

6. A mechanism according to claim 5, wherein the outer surface of the conduit has a male screw profile and the sealing bush is shaped with a female screw portion which makes screw engagement with such male screw.

7. A mechanism according to claim 6, wherein said male screw profile is formed by one or more helically wound wires.

8. A mechanism according to claim 7, wherein the conduit comprises a tube formed by helically interwound wires of different cross-sections, one of which forms the thread and the other of which forms the root of said male screw.

9. A mechanism according to any of claims 6 to 8, wherein the female screw portion of the sealing bush is held tightly pressed against the conduit by a constraining or clamping ring surrounding the sealing bush.