GB2237097A

GB2237097A - Actuator

Info

Publication number: GB2237097A
Application number: GB8920362A
Authority: GB
Inventors: Brian George Hopkins
Original assignee: Xomox Ltd
Current assignee: EMR Barnstaple Ltd
Priority date: 1989-09-08
Filing date: 1989-09-08
Publication date: 1991-04-24
Also published as: GB8920362D0

Abstract

An actuator for a gate valve or sluice gate comprises a first member 1 rotatable about an axis and a plurality of linkage members 4, each of which is operably connected at one end to said first member 1 and which in a neutral or unoperated state extends therefrom generally radially and at an angle to said axis to a second member 6 which is displaceable only along said axis, said linkage members being each operably connected to said second member, the arrangement being such that rotation of the first member 1 from the neutral position causes said linkage members 4 to wrap around the first member thereby drawing the second member 6 towards it. The linkage members may be flexible, or they may be stiff/resilient to permit operation in either direction. <IMAGE>

Description

Improvements in and relating to actuators This invention relates to actuator devices and in particular to devices which are useful for translating rotary motion into linear motion and/or vice versa.

It is known to use a gear mechanism such as a rack and pinion for this purpose, one example being the mechanism used to lift the gate in a gate valve, or in a sluice gate. Whilst such systems are effective, they have a poor response time, in that many turns of the pinion shaft are needed to lift the gate. It is an object of the present invention to provide an actuator which has improved response time.

According to this invention, an actuator device comprises a first member rotatable about an axis and a plurality of linkage members, each of which is operably connected at one end to said first member and which in a neutral or unoperated state extends therefrom generally radially and at an angle to said axis to a second member which is displaceable only along said axis, said linkage members being each operably connected to said second member, the arrangement being such that rotation of the first member from the neutral position causes said linkage members to wrap around the first member thereby drawing the second member towards it.

The linkage members may be flexible, for example cords or cables, in which case operation is controlled by the first member, or they may be relatively stiff or resilient, in which case operation may be from either end. Thus rotary movement may be translated into linear movement or vice versa, depending on the materials used.

The mechanical advantage of the system may be changed very considerably be changing the diameter of that part of the first member onto which the linkage members are wrapped. The larger the diameter, the more rapidly will the second member move in response to rotation of the first member. This can be used to achieve very fast operation of, for example, a gate valve and the invention includes a gate valve equipped with such an actuator device.

In order that the invention be better understood, a preferred embodiment of it will now be described by way of example with reference to the accompanying drawing in which: Figure 1 is a schematic cross-sectional side view of an actuator constructed in accordance with the invention, shown in an unoperated or neutral state, and Figure 2 is the actuator of Figure 1 shown in an operated state.

Like reference numerals are used for like parts in both figures. Referring first to Figure 1, a first member 1, is mounted for rotary movement about axis X-X by means of a bearing system 2, supported by a plate 3. The latter is carried by a tubular housing 5. The member 1 is operated by a handwheel 12, although a gear mechanism could equally well be used. Inside the housing 5, the member 1 has a cylindrical boss 8 at its free end. This housing is internally recessed at 15,16 to receive the free, upper end of an operating rod 9 and a helical return spring 7, respectively. The spring 7 is retained between the top of the recess 16 and the surface of a second member 6 which is slidably but non-rotatably mounted in the housing 5 and secured to the rod 9 (by means not shown).

The rod extends through a plate 10 containing a seal 11.

Parts only of the rod 9 and the plate 10 are shown, since they are not material to the functioning of the actuator itself.

A plurality of linkage members 4 are connected between the member 1 and the member 6. In the interests of clarity, only two linkage members are shown although any number may be used. In this example, flexible wires are employed; they extend from the member 1 over the outer surface of the cylindrical boss 8 to their respective attachment points on the second member 6.

As shown in figure 1, the wires 4 allow the member 6 and rod 9 to hang in its lowest position relative to the plate 3 and the first member, 1, under the influence of the helical return spring 7. However, in figure 2, the handwheel 12 has been rotated and the wires 4 are now wrapped about the boss 8, thereby lifting the member 6 and rod 9, so that the free, upper end of the Latter is now almost fully received into the recess 15. The return spring is compressed between the top of the recess 16 and the member 6, as shown.

By selecting the diameter of the boss 8 in relation to the attachment positions of the wires on the member 6, the rate of movement of the latter in response to rotation of the member 1 can be altered. In general terms, the larger the boss the faster the second member will be raised (or lowered) by rotating the first member about axis X-X.

Although not shown in great detail herein, components 10 and 11 may form part of the casing of a gate valve, with the lowermost end (not shown) of rod 9 being a part of the gate lifting mechanism. The arrangement shown would then facilitate rapid operation of the latter in response to relatively few turns of the handwheel 12.

Claims

CLAIMS:

1. An actuator device comprising a first member rotatable about an axis and a plurality of linkage members, each of which is operably connected at one end to said first member and which in a neutral or unoperated state extends therefrom generally radially and at an angle to said axis to a second member which is displaceable only along said axis, said linkage members being each operably connected to said second member, the arrangement being such that rotation of the first member from the neutral position causes said linkage members to wrap around the first member thereby drawing the second member towards it.

2. An actuator device according to claim 1 wherein the linkage members are flexible.

3. An actuator device according to claim 1 wherein the linkage members are relatively stiff or resilient.

4. An actuator device according to any preceding claim including a return spring operable to urge the second member away from the first.

5. An actuator device according to any preceding claim wherein the first member includes a cylindrical boss about the outer surface of which the linkage members are, in use, wrapped.

6. An actuator device substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

7. A gate valve equipped with an actuator device according to any preceding claim.