GB2254103A

GB2254103A - Locking mechanism for a valve

Info

Publication number: GB2254103A
Application number: GB9105649A
Authority: GB
Inventors: Joseph Philip Morrison; Trevor Griggs
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-03-18
Filing date: 1991-03-18
Publication date: 1992-09-30
Anticipated expiration: 2011-03-18
Also published as: GB2292207B; GB9105649D0; GB2292207A; GB9521249D0; GB2254103B

Abstract

A key mechanism, suitable for use with a locking mechanism for a valve, comprises a barrel selectively rotatable with respect to a sleeve 36a. In the preferred embodiment the sleeve 26a includes an annular passageway 56a in its base, having a slot 58a extending radially of the annular passageway. The other of the body and the sleeve has a code member or tumbler 40a. At least part 60a of the code member is dimensioned to be movable radially in said slot. In use, a defined radial displacement of the code member enables said at least part of the code member to be positioned in the annular passageway permitting relative rotation of the body and the sleeve. The key mechanism is incorporated in a locking device for a valve - see fig. 1a. An offset spigot 24b (fig. 16, not shown) extends through arcuate slot in plate 28, and on rotation of the lock barrel, causes movement of arms 14a, 14b inward or outward to cause engagement or disengagement of handwheel 8 (fig. 16 not shown) which actually operates the valve. <IMAGE>

Description

LOCKING MECHANISM FOR A VALVE The present invention relates to a locking mechanism and, in particular, to a locking mechanism suitable for locking a valve. An aspect of the present invention further relates to a key mechanism which is particularly suitable for a locking mechanism for a valve.

It is frequently necessary to provide a means for locking a rotatable operating member, in an industrial installation, either to secure that operating member against unauthorised operation or to prevent its operation other than at the correct point in a sequence of other associated operations. For example, fluid-flow control valves often have to be secured in this way.

A valve operating member may be secured against unauthorised operation by a simply chain or padlock but more recently there have been proposals for much more sophisticated mechanisms adapted for mounting on a valve, preferably without the need to modify the valve body in any way. Such a mechanism typically is key-operated and arranged so that the key must be inserted to permit operation of the valve.

A first aspect of the present invention provides a key mechanism comprising a body selectively rotatable with respect to a sleeve wherein one of the body and the sleeve includes an annular passageway having a slot extending radially of the annular passageway, the other of the body and the sleeve having a code member, at least part of the code member being dimensioned to be movable radially in said slot, in use, a defined radial displacement of the code member enabling said at least part of the code member to be positioned in the annular passageway permitting relative rotation of the body and the sleeve.

It will be appreciated that the key mechanism can only be operated by the use of the correct key so that the code member is radially displaced the correct distance to be positioned in the annular passageway. Advantageously, the key mechanism includes a plurality of slots and code members to increase the member of permutations of keys and key mechanisms available.

Preferably a surface of the code member for co-operation with a surface of a key includes a protrusion which may have a defined radial dimension and or a defined axial position. By the use of code members having protrusions of different radial dimensions and different axial positions, the permutations of key mechanisms and keys is thereby increased and the security offered by the key mechanism increased.

Advantageously, the key mechanism includes means for urging the code member to be radially displaced from the annular passageway in the absence of a key.

The key mechanism and key of the present invention are particularly suited for use with a valve locking mechanism. Accordingly, the following description describes an embodiment of the key mechanism and key as used with a valve locking mechanism.

A second aspect of the present invention provides a locking mechanism for a valve, the valve being operable by movement of a first element relative to a second element, the locking mechanism including a first member for mounting on the first element, a second member, means for selectively preventing relative movement of said first member and said second member and means for fixedly connecting said second member of the locking mechanism to said second element, whereby the prevention of relative movement of said first and second members of the locking mechanism locks the valve, wherein said connecting means are configured to be accessible from the exterior of the locking mechanism when fixed in position on the valve and may be broken so that the valve can be operated.

With such a locking mechanism, access to the valve can be obtained in an emergency even when the locking mechanism is in its locked state.

An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Figures la and ib are exploded views of the components of a locking mechanism for a valve; Figures 2a, 2b and 2c show schematic plan views of the locking mechanism in different states; Figures 3a and 3b are sectional views of a key and key mechanism according to the present invention; Figure 4 shows a part of a key being inserted in the key mechanism according to the present invention; Figures 5a and 5b show cross-sectional views of a cover in the key mechanism of the present invention; Figure 6a is a cross-sectional view of a control mechanism forming part of the locking mechanism of Figures la and lb;; Figure 6b is a plan view of the control mechanism of Figure 6a; and Figure 7 is a view of the locking mechanism, with part broken away, attached to a valve.

Figures la and ib are exploded views showing the components of a locking mechanism for a valve.

The locking mechanism includes a body 2 which is joined to a turning adaptor 4 so as to be rotatable together. The turning adaptor 4 is relieved to co-operate with the yoke (not shown) of a valve to which the locking mechanism is fitted. As shown, the turning adaptor 4 has an internal bore 6 of hexagonal cross-section to co-operate with a yoke of hexagonal cross-section, though other cross-sections may be used. The body 2 and turning adaptor 4 are fixedly joined to the yoke by means of a nut (not shown). Accordingly rotation of the body 2 and turning adaptor 4 about an axis A causes rotation of the yoke to open or to close the valve. The body 2 and turning adaptor 4 may be formed as an integral component, if required.However, manufacturing the body 2 and turning adaptor 4 separately allows a standard body 2 to be produced for all locking mechanisms which can then be joined to a turning adaptor 4 for a specific type of valve.

When the locking mechanism is unlocked, rotation of the body 2 by an operator can be effected by rotation of a handwheel 8 to which handles 10 may be affixed for ease of operation. The handwheel 8 encloses the body 2 totally so that the body 2 and turning adaptor 4 are not otherwise accessible to the operator.

In the unlocked state of the locking mechanism, torque is transmitted from the handwheel 8 to the body 2 via a drive plunger slidably mounted in the handwheel 8 and a pair of drive arms 14a, 14b mounted on the body 2.

A boss 15a, 15b extends from one side of each drive arm 14a, 14b and into a circular recess 16a, 16b in the body 2. Accordingly, while rotation of the drive arm 14a, 14b about the axis of the circular recess 16a, 16b is possible, rotation of the handwheel 8 about the axis A effects rotation of the body 2. Figure 2a is a schematic plan view of the locking mechanism in the unlocked state.

In the locked state of the locking mechanism, the handwheel 8 is disengaged from the body 2 so that rotation of the handwheel does not effect rotation of the body 2.

Figure 2b is a schematic plan view of the locking mechanism in a locked state which might more aptly be called the 'non-operating' or 'free-wheeling' state. As shown in Figure 2b, the drive arms 14a, 14b are retracted radially inward of the drive plunger 12 to disengage rotation of the handwheel 8 from rotation of the body 2.

Figure 2c is a schematic plan view of the locking mechanism in a non-operating or free-wheeling state. Only the drive arm 14b is retracted radially inward of the drive plunger 12. Accordingly, when the handwheel 8 is rotated in the sense indicated by the arrow B, the drive plunger 12 slips over the retracted drive arm 14b. As the handwheel 8 is rotated further, a pair of plunger springs 18a, 18b attached to the plunger 12 allow the plunger 12 to move out radially as the plunger 12 passes around the non-retracted drive arm 14a so that no torque is applied to the body 2. The extreme radially outward position of the drive plunger as it is urged outward by the drive arm 14a is indicated at 12'.

If the drive arms 14a, 14b are moved into the unlocked state, as shown in Figure 2a, then rotation of the handwheel 8 by an operator effects rotation of the body 2 to open or to close the valve. Retraction of the drive arm 14a into the locked position prevents rotation of the body 2 in an anti-clockwise direction (sense C as shown in Figure 2c) whilst retraction of the drive arm 14b into the locked position prevents rotation of the body 2 in a clockwise direction (sense B, as shown in Figure 2c). The locking mechanism will normally be operated when the valve has been rotated to one of its extreme settings - either fully open or fully closed - ie. rotated fully clockwise or rotated fully anti-clockwise. If the body 2 has been rotated to its extreme clockwise state, then retraction of the drive arm 14a prevents rotation of the body 2 totally.Similarily, if the body 2 has been rotated to its extreme anti-clockwise state, then retraction of the drive arm 14b prevents rotation of the body 2 totally. Otherwise, retraction of both drive arms 14a, 14b may be used to lock the body, and hence the valve, in some intermediate state.

The operator effects movement of each drive arm 14a, 14b between its locked and unlocked state using a coded key 20a, 20b which can be inserted into a key barrel 22a, 22b. A peg 24a, 24b extends from the inner end of the key barrel 22a, 22b through an arcuate slot 26a, 26b in the top plate 28 of the locking mechanism and through a shaped slot 30a, 30b in the respective drive arm 14a, 14b. Thus, rotation of the respective key barrel 22a, 22b through 1800 using the coded key 20a, 20b causes movement of the drive arm 14a, 14b between its locked and unlocked state.

As indicated previously, the key 20a, 20b can be coded so that only the correct key will operate the drive arm 14a, 14b. A key 20a is inserted into a bore 32a of the key barrel 22a through a hole 34a in a cover 36a of the key barrel 22a. A plurality of slots 38a (four shown) extend radially outward of the bore 32a of the key barrel 22a as shown in Figure 3a. A code clip 40a is provided in each slot 38a, the code clip 40a having a non-operating position in the absence of a key. The code clip 40a is urged into its non-operating position by two resilient circlips 41a. A small protrusion 42a is provided in the code clip 40a. As indicated in Figure 3b, five different axial positions A, B, C, D, E and three different radial settings X, Y, Z of the protrusion 42a are envisaged.The number of code clips 40a provided in each key barrel 22a increases the number of possible permutations of protrusions by which key barrels may be differentiated, and so coded.

Each key 20a (shown in part in Figure 3b) comprises a shaft 44a on which a number of notches (one shown at 46a) are provided. When the key shaft 44a is inserted into the bore 32a of the key barrel 22a, the code clips 40a are urged radially outward against the resilience of the circlips 41a. Indents 48a, 50a in the cover 36a and the key barrel 22a co-operate with a slit 52a (shown in Figure 4) extending the length of the shaft of the key 20a so that the key 20a and the key barrel 22a are radially positioned correctly relative to each other. The key shaft 44a can be inserted a finite and ascertainable depth into the key barrel 22a as defined by the depth of the bore in the key barrel 22a. At this position, an annular groove 54a in which the slit ends coincides with the indent 48a in the cover 36a.

If the correct key 20a is inserted into a key barrel 22a, then the protrusion 42a on each code clip 40a is aligned with a notch 46a on the key shaft 44a. The depth of notch 46a on the key shaft 44a is less than the radial dimension of the protrusion 42a on the code clip 40a. Accordingly, the code clip 40a is urged radially outward a defined distance depending on the relative dimensions of the notch 46a and the protrusion 42a.

As described previously, a cover 36a is provided around the key barrel 22a. In the cover 36a, there is an annular passageway 56a with slots 58a extending radially inward and outward therefrom. A clearer illustration of the cover 36a is provided in Figures 5a and sub.' As shown in Figure 3a, the slot 38a in the key barrel can be aligned with the slot 58a in the cover 36a. With this orientation of the key barrel 22a and the cover 36a, the key 20a can be inserted into the key barrel 22a. The code clip 40a is urged radially outward, , as described previously. If the correct key 20a is inserted, the code clip 40a is displaced radially outward so that an end 60a is rotatable in the annular passageway 56a in the cover 36a.Figure 5b shows the end 60a of the code clip 40a in four possible positions 60a1, 60a2, 60a3, 60a4.

In the position 60a1, either the code clip 40a is in its non-operating position as the key 20a has not been inserted or the notch 46a in the key 20a is too deep and so the end 60a of the code clip 40a is held in the slot 38a and not displaced sufficiently radially outward. In the position 60a2, the end 60a of the code clip 40a has been displaced too far radially outward, because the key 20a is being inserted, the protrusion 42a has not been aligned with a notch 46a and so is abutting a surface of the key 20a not having a notch, or the notch 46a is too shallow. In the position 60a3, the notch 46a on the key 20a has been aligned with the protrusion 42a on the code clip 40a so that the end 60a of the code clip is displaced into the annular passageway 56a of the cover 36a. When the end of the code clip is in the position 60a3, it is rotatable in the annular passageway 56a to a position 60a4 and hence the key 20a and key barrel 22a can be rotated with respect to the cover 36a.

Once the key 20a has been rotated with respect to the cover 36a, the engagement of an indent 50a in the cover 36a with the annular groove 54a in the key 20a prevents the key 20a from being removed from the cover 36a.

It is an advantage to provide some indication of the setting of the valve and, in particular, if the valve is fully open or fully closed. A control mechanism which assists in providing such an indication comprises a plurality of components shown in Figures 6a and 6b as follows: a Geneva wheel 70 which is driven by rotation of the body 2, one revolution of the body 2 producing one rotation of the Geneva wheel 70 by 1200; one or more single toothed gears 72, 74 which are held in position by a retaining screw 76 and rotate with the Geneva wheel 70 so that three rotations of the Geneva wheel each by 1200 and hence three revolutions the body 2 produces one rotation of the single toothed gears 72, 74; a multi-toothed gear hub 78 which has an opening 80 extending along its length;; one or more multi-toothed gears 82, 84 which co-operate with the single toothed gears 72, 74, each rotation of a single toothed gear causing movement of the multi-toothed gear by one tooth; a leaf spring 86 adjacent the multi-toothed gears 82, 84; a locking shaft 88 with a boss 90 which extends through respective bores in the multi-toothed gears 82, 84 and the multi-toothed gear hub 78; and a locking pin 92 which is mounted on the body 2 to be slidable in a recess defined by the opening 80 of the gear hub 78, dimples 94, 96 provided in the internal surface of the multi-toothed gears 82, 84 and a dimple 98 provided in the boss 90 of the locking shaft 88.

The locking pin 92 and the various dimples 94, 96, 98 are dimensioned so that the locking shaft 88 cannot be rotated if the multi-toothed gears 82, 84 are moved away from a datum position in which all the dimples 94, 96, 98 are aligned. The control mechanisms are arranged so that this datum position occurs when the valve is fully opened or fully closed (or at some other setting of interest).

If the locking pin 92 is positioned in the dimples 94, 96 of the multi-toothed gears 82, 84, then the locking shaft 88 is rotatable within the bores of the multi-toothed gears 82, 84. If the multi-toothed gears 82, 84 are moved away from this datum position, the internal surfaces of the multi-toothed gears 82, 84 urge the locking pin towards the dimple 98 in the locking shaft 88, so preventing rotation of the locking shaft 88 with respect to the multi-toothed gears 82, 84.

As outlined previously, a peg 24a, 24b from the key barrel 22a, 22b extends through slots 26a, 26b, 30a, 30b in the cover 28 and the drive arms 14a, 14b. The peg 24a, 24b further extends into a recess 100 in the locking shaft 88. Accordingly, the key barrel 22a, 22b is rotatable with the locking shaft 88 so that if the locking shaft 88 cannot be rotated then neither can the key barrel 22a, 22b.

The key barrel 22a, 22b has a defined position in which the key 20a, 20b can be inserted or removed. When the key 20a, 20b is inserted into the key barrel 22a, 22b, the key and key barrel can be rotated to operate the drive arm 14a, 14b. Once the body 2 has been rotated so that the multi-toothed gears 82, 84 have been rotated away from the datum position, the locking shaft 90 cannot be rotated and accordingly the key barrel 22a, 22b cannot be rotated to release the key 20a, 20b. In this way, the presence of keys 20a, 20b which cannot be removed in the locking mechanism provides an indication that the valve is not in its fully opened or fully closed setting. If only one of the keys 20a, 20b is in the locking mechanism and cannot be removed, this shows that the valve is in one of its fully opened and fully closed settings and further indicates which of these settings.

Accordingly, the control mechanism is arranged to provide a strategic release of a key at the extreme settings of the valve (ie. the fully opened and fully closed positions) or at any other predetermined intermediate position. The number of teeth on the multi-toothed gears is chosen so that the total number of revolutions of the handwheel required to turn the valve from its fully opened position to its fully closed position (or vice a versa) does not exceed the number of revolutions of the handwheel required to turn the multi-toothed gear one complete revolution. If only a sixteen toothed gear is used, for example, then forty-eight revolutions of the handwheel are possible before the multi-toothed gear makes one complete revolution.Such a gearing system would therefore be used if the number of handwheel revolutions required to open and close the valve does not exceed forty-eight and so the keys can only be released at respective unique positions of the locking mechanism. If the number of valve handwheel revolutions required to open and close the valve exceeds forty-eight, in the specific example, then there would be more than one position of the valve in which the locking pin 92 could be fully urged into the dimples in the multi-toothed gear and so more than one position in which the key could be released. Accordingly, if the number of handwheel revolutions required to open and close the valve exceeds òrty-eight, a second multi-toothed gear can be provided on top of the sixteen tooth gear.The combination of a fifteen tooth gear with a sixteen tooth gear will provide seven hundred and twenty revolutions between alignments of the dimples in the multi-toothed gears and the locking shaft 88.

When the locking mechanism is being mounted on a valve, the locking mechanism is operated on the valve to a required position in which the key is to be released. The multi-toothed gears are then manually rotated so that their dimples all align.

From the foregoing, it will be appreciated that a control mechanism is provided for each key 20a, 20b.

However, for ease of illustration of the component parts, only a part of the control mechanism has been shown for each key 20a, 20b in Figures la and ib.

An indication of an intermediate setting of the valve can be provided by counting the number of revolutions of the handwheel 8 and hence the body 2 required from one of the extreme settings to the intermediate setting of interest.

To prevent unauthorised or inadvertent removal of the locking mechanism from a valve, an anchor ring 106 is provided. As shown in Figure 7, anchor bars 108, 110 are threaded through annular extensions 112, 114 on the anchor ring 106 and around fixed arms 116, 118 of the valve 120.

The free ends of each anchor bar 108, 110 are joined together by shear bolts which are sheared off to prevent removal of the locking mechanism. (The anchor ring 106 fits entirely within the handwheel 8 and so is not visible in Figure 7.) As described previously, the body 2 and turning adaptor 4 of the locking mechanism are secured to the valve 120 by a standard nut 122. The turning adaptor 4 is relieved to fit around the yoke 124.

It will be appreciated that the anchor ring 106 cannot be rotated relative to the arms 116, 118 of the valve 120. A ball race 126 is positioned between an external annular groove 128 of the anchor ring and an internal annular groove 110 of the handwheel 8 to permit relative rotation of the handwheel 8 and the anchor ring 106 during normal operation of the locking mechanism.

However, there may be circumstances in which the locking mechanism is in its locked state but access to the valve is required urgently. In such circumstances, the anchor bars can be broken to permit removal of the locking mechanism so that the valve yoke can be rotated using a spanner or similar wrench.

Advantageously, a ring of notches 132 are provided in the anchor ring 106 to co-operate with pegs 134a, 134b on the drive arms 14a, 14b. When the drive arms 14a, 14b are in the unlocked or driving position, as shown in Figure 2a, then there is no inter-engagement of the pegs 134a, 134b and the notches 132. However, when the drive arms 14a, 14b are in the unlocked position, the pegs 134a, 134b can engage with the notches 132 in the anchor ring 106. The pegs 134a, 134b are effective as ratchets in the ring of notches of 132. If the handwheel 8 is "free wheeling" correctly so that rotation of the handwheel 8 does not impart a torque to the drive arm 14b (in the position shown in Figure 2c), the peg 134b easily moves in and out of the notches 132 because of its configuration.

(The sound of the relative movement of the pegs 134a, 134b with the notches 132 provides an indication that the handwheel 8 is free-wheeling and not operating the valve.) However, should some torque be transmitted from the handwheel 8 and plunger 12 to the drive arm 14b, eg.

because the adjacent surfaces of the plunger 12 and drive arm 14b are binding due to the presence of grease or dirt, the configuration of the peg 134b assists in preventing rotation of the drive arm 14b and body 2 with respect to the anchor ring 106.

It will be further noted that rotation of the Geneva wheel 70 as the body 2 rotates is effected by a pin (not shown) affixed to the anchor ring 106. The Geneva wheel 70, and hence the body 2 of the locking mechanism, can be rotated three revolutions for movement of the multi-toothed gears 82, 84 by one tooth. Accordingly, even when the valve is in its fully opened or fully closed setting, as indicated by release of the respective keys 20a, 20b, three revolutions of the handwheel 8 are still possible before rotation of the handwheel 8 is prevented by the locking mechanism. These three revolutions permit the valve yoke to be rotated and the valve tightened should an operator notice some seepage of fluid through the valve. However, the locking mechanism prevents further rotation of the handwheel 8 to operate the valve further.

Modifications to the embodiment described within the scope of the present invention will be apparent to those skilled in the art.

Claims

1. A key mechanism comprising a body selectively rotatable with respect to a sleeve wherein one of the body and the sleeve includes an annular passageway having a slot extending radially of the annular passageway, the other of the body and the sleeve having a code member, at least part of the code member being dimensioned to be movable radially in said slot, in use, a defined radial displacement of the code member enabling said at least part of the code member to be positioned in the annular passageway permitting relative rotation of the body and the sleeve.

2. A key mechanism according to Claim 1 wherein the code number is an elongate member extending axially of the key mechanism.

3. A key mechanism according to Claims 1 or 2 wherein the code member has a surface for co-operation with a surface of a key, said surface of the code member being non-planar.

4. A key mechanism according to Claim 3 wherein said surface of the code member is non-uniform.

5. A key mechanism according to Claim 4 wherein said surface of the code member includes a protrusion.

6. A key mechanism according to Claim 5 wherein the protrusion has a defined radial dimension.

7. A key mechanism according to Claims 4 or 5 wherein the protrusion has a defined axial position.

8. A key mechanism according to any one of Claims 3 to 7, the code member being an elongate member, wherein a part of said surface of the code member is non-planar, and said at least part of the code member dimensioned to be movable radially in said slot is axially displaced from the non-planar part of said surface.

9. A key mechanism according to Claim 8 wherein the annular passageway is positioned in a part of said one of the body and the sleeve beyond an end of said other of the body and the sleeve having a code member and the slot extends radially inward and outward of the annular passageway.

10. A key mechanism according to any one of the preceding claims wherein the sleeve includes the annular passageway and the body includes the code member.

11. A key mechanism according to Claim 10 wherein the body includes an axial bore for receiving a key.

12. A key mechanism according to any one of the preceding claims including a plurality of slots and code members.

13. A key mechanism substantially as hereinbefore described with reference to any one of the accompanying drawings.

14. A key for use with the key mechanism of any one of the preceding claims.

15. The combination of a key-mechanism according to any one of Claims 1 to 9 and the key of Claim 14.

16. A locking mechanism for a valve, the valve being operable by movement of a first element relative to a second element, the locking mechanism including a first member for mounting on the first element, a second member, means for selectively preventing relative movement of said first member and said second member and means for fixedly connecting said second member of the locking mechanism to said second element, whereby prevention of relative movement of said first and said second members of the locking mechanism locks the valve, wherein said connecting means are configured to be accessible from the exterior of the locking mechanism when fixed in position on the valve and may be broken so that the valve can be operated.

17. A locking mechanism according to Claim 16 wherein said connecting means includes at least two elongate members.

18. A locking mechanism according to Claim 17 wherein the elongate members can be threaded through a part of said second member.

19. A locking mechanism according to Claim 18 wherein said second member includes a ring for each elongate member, the ring being fixed to an exterior surface of said second member.

20. A locking mechanism for a valve substantially as hereinbefore described with reference to any one of the accompanying drawings.

21. The combination of a valve and a locking mechanism according to any one of Claims 16 to 20.

22. The combination of a locking mechanism according to any one of Claims 17 to 20 and a valve, wherein the elongate members can be passed through a part of the valve body.