GB2121470A

GB2121470A - Adjustable lock for a rotary element such as a valve

Info

Publication number: GB2121470A
Application number: GB08314776A
Authority: GB
Inventors: Erich Lange
Original assignee: Rheinische Armaturen und Maschinenfabrik Albert Sempell
Current assignee: Sempell GmbH
Priority date: 1982-06-04
Filing date: 1983-05-27
Publication date: 1983-12-21
Also published as: DE3221158A1; GB2121470B; DE3221158C2; GB8314776D0

Abstract

A lock for a rotary element e.g. a valve having a rotary drive, such as a stop valve or gate valve, has means to adjust the locking position and comprises a casing (2) surrounding a locking bush (6) arranged to rotate with the valve drive, and a lockbolt (23) movable by means of a lock cylinder (25) operated by a removable key (31) to engage directly in any one of several radial recesses (9) in the periphery of the locking bush (6). To locate the required locking position the locking bush (6) has an external screwthread (10) which is engaged by a toothed adjusting nut on a screw- threaded spindle (11). The adjusting nut or a part movable axially therewith is formed with a groove in which a projection (22) on the lockbolt (23) can engage only when the lockbolt is able to engage in one of the radial recesses (9). The screw-threaded spindle (11) is adapted to be by means of a special key to move the nut to allow bolt movement into a selected recess. Thereafter the nut will move as the bush rotates and block bolt movement other than into the recess selected. <IMAGE>

Description

SPECIFICATION Adjustable lock for a rotary element such as a valve This invention reiates to an adjustable lock for a rotary element, such as a valve having a rotary drive, for example a stop valve or gate valve. The invention is concerned particularly with locks of the type comprising a locking bush arranged to rotate with the element to be locked and connected either to a rotatable spindle so as to be rotatable but axially immobile, or positively to a screw-threaded bush of a non-rotating spindle, and an adjustable lockbolt to engage the locking bush and movable between two end positions by means of a lock cylinder adapted to be operated by a removable key.

It is known to provide a cylinder lock with a key which can be withdrawn only when the lock is in a required locking position. One of the disadvantages of such a locking arrangement is that the locking positions are predetermined and cannot without extensive alterations be varied subsequently, for instance, so that a valve previously lockable in its open position can now be locked in its closed position or vice versa. Also, the cumulative effect of the various manufacturing tolerances in long-run production means that actual predetermined locking positions may vary considerably from the corresponding reference positions.

It is an object of the invention accordingly to provide an improved adjustable lock of this general type, more particularly for valves or the like, in which the lock bolt can engage directly in the component to be locked, for example, a locking bush which co-rotates with a screwthreaded bush- i.e., it is an object of the invention to provide direct actuation without intermediate elements. The invention is therefore intended to reduce the mechanical stressing, more particularly the shear stressing of the lockbolt, as compared with a construction in which the gear ratio increments between the interposed elements make the shear forces fairly substantial.

The invention also aims to reduce the risk of jamming of the lockbolt in the event of attempted mis-operation. Direct actuation leads to more accurate adjustment of the lock since there is no cumulation of the various manufacturing clearances, something which is unavoidable in locking systems having consecutive transmission elements. Another object is to provide a lock in which relatively simple means can be used to provide an indication either on the valve or at a place remote therefrom whether the valve or fitting or the like is in the locked or unlocked state.

Broadly stated the invention consists in an adjustable lock for a rotary element such as a valve, including a casing, a locking bush connected for rotation with the rotary element, an adjusting nut co-operating with the bush, and an adjustable lockbolt movable between two positions by means of a lock cylinder operated by a removable key and in which the locking bush is formed on its periphery with a number of radial recesses and with an external screw-thread engaged by axial toothing on the adjusting nut, the adjusting nut is mounted on a screw-threaded spindle and is formed with or connected to a part moving axially and having a recess or groove, the screw-threaded spindle is rotatably mounted in a bore in the casing, is held against rotation by at least one spring detent engaging a recess in part of the spindle, and can be turned by means of a special key only after release of this detent, and the lockbolt has a projection which can engage in the recess in the adjusting nut only when the lockbolt is in a position to enter one of the radial recesses in the locking bush.

In one embodiment of the invention the recess in the adjusting nut is a peripheral groove positioned substantially at the mid-point in the axial length of the nut. If it is required that there should be no groove in the operative zone of the external screw-thread of the locking bush then the adjusting nut may have round it a sleeve which is open towards the locking bush and is axially movable, but not co-rotatable, with the adjusting nut, and which is formed with a groove engageable by the lockbolt projection.

Conveniently the radial recesses in the locking bush are blind bores and the lockboit projection is a cylindrical pin which can be introduced positively into the selected blind bore.

The radial recesses in the locking bush and the lockbolt projection which engages therein can be of any desired cross-sectional shape, for example, rectangular. The radial recesses may be in the form of tooth spaces of a tooth system, such tooth spaces being engageable by a corresponding adapted wedge-shaped head member of the lockbolt. To lock the screwthreaded spindle and render it tamperproof the device may include a number of spring-biassed detent pins which engage in recesses in the head of the spindle. There may be the same number of recesses as detent pins, or more recesses, and it may be of advantage to use two or more lock cylinders to actuate the lockbolt.

According to another preferred feature of the invention, to give an indication of the position of the adjusting nut an indicator element such as a pointer, visible on the outside of the casing, may be provided, with an inward projection engaging in the groove in either the adjusting nut or the sleeve. The adjusting nut may be extended axially, so as to project outside the casing, and be connected externally to a position indicator or act on an actuating element, for example, an electric contact, of an electrical position indicator. Remote indication can therefore be given of the position of the adjusting nut. As long as the adjustment of the nut on the spindle remains unaltered, this indication is an indication of valve position.Also, a positional indication on the lockbolt can indicate whether the valve is in the locked or unlocked state, something which is often required in safety circuits.

If very accurate fine adjustment is required and the locking bush and screw-threaded bush are not a single component, the groove in the locking bush may be made wider than the associated tongue, so that the tongue and groove can make minor movements relatively to one another. According to another preferred feature of the invention, the locking bush and screwthreaded bush can be combined to form a single component if fine adjustment requirements permit this.

The advantages of the invention are more particularly that the required locking positions can be adopted virtually steplessly and that forces are transmitted directly from the rotary drive of the valve to the lockbolt. Consequently, when an attempt is made to actuate the valve in its locked position the lockbolt is subjected to less shear stressing than in known locking systems where the forces are multiplied by interposed transmission elements such as screw transmission. The novel lock of this invention is therefore less liable to disturbances.

There is a risk with the known locking facilities of cumulative manufacturing clearances in the transmission elements, with the result that it becomes difficult to select and adopt the required locking positions accurately. The direct actuation provided by the invention obviates this disadvantage.

A lock according to the invention is well adapted for long-travel valves or the like which normally require, for instance, 200 handwheel rotations for full actuation. With a single-start screw-thread on the screw-threaded bush, 20 teeth on the adjusting nut and a 1 mm spindle pitch, the adjusting movement of the adjusting nut in the present invention may be for instance, only 20 mm, with the advantage that a lock according to the invention may require minimal space. Since the spindle can be adjusted only by means of a special key, unauthorised alteration of a predetermined locking adjustment is impossible.

The invention may be performed in various different ways and three embodiments will now be described in greater detail with reference to the accompanying drawings, in which: Figure 1 is an axial section through an adjustable locking device for a stop valve having a non-rotating rising spindle; Figure 2 is a cross-section on the line I-I in Figure 1; Figure 3 is a cross-section through the locking device on the line Il-Il of Figure 1; Figure 4 is a cross-section similar to Figure 2 of a variant, and Figure 5 is a cross-section similar to Figure 3 of another variant.

Figure 1 merely shows the drive head of a stop valve but the valve itself is not shown since its construction has no bearing on an understanding of the invention.

On the casing of the valve is mounted a drive head 1, to which is attached a casing 2, in the present case by four screw-threaded bolts 3. The spindle 4 of the valve has an external screwthread which fits in an internal screw-thread of a tapped bush 5 mounted in the casing 2 so as to be rotatable but axially immobile.

A locking bush 6 extends around and corotates with the bush 5. In the illustrated embodiment the operative connection for rotation is provided by a tongue 7 of a tongue-and-groove connection. The bush 6 is so mounted in the casing 2 as to be rotatable but axially immobile, and is joined to a handwheel 8 outside the casing.

The bush 6 is formed on its outer periphery with a screw-thread 10 and with a number of radial blind bores 9 distributed uniformly around the periphery.

Mounted in a bore 2a in the casing 2, at the level of the screw-thread 10, the latter bore extending at right-angles to the main axis of the casing, is a screw-threaded spindle 11 having a guide pin 12 at one end, a screw-thread 13 along its central length and a head 14 at its other end.

The spindle 11 is retained in position in the casing 2 against axial movements by means of the head 14 and a screw-threaded ring 15. The ring 15 is screwed into an internal screw-thread and fixed, for example, by riveting.

On the outer periphery of the head 14 are a number of recesses 16 in which detent pins 17 engage when the head 14 is in an appropriate position. A special key is required to press the detent pins 17, against the force of a spring 1 8 acting on the inner end of each spring, out of the recesses 1 6 into the casing far enough to enable thy head 14 and therefore the spindle 11 to be turned.

An adjusting nut 1 9 runs on the spindle 11 in the bore 2a and has external straight teeth 20 which mesh with the screw-thread 10 of the bush 6. Consequently, any rotation of the bush 6 results in lesser rotation of the nut 1 9 and, therefore, axial movement thereof on the spindle 11. The teeth 20 are interrupted approximately at mid-point by a peripheral groove 21 in which a projection 22 of a lockbolt 23 can engage, but only when the nut 19 is in a particular desired position.

The lockbolt 23 is guided for longitudinal movement in another bore 2b of the casing 2, extending radially of the main axis thereof and perpendicularly to the bore 2a and at the level of the blind bores 9. The lockbolt 23 has on its end face a cylindrical pin 24 which can engage positively in any of the blind bores 9 and which when in the engaged position locks the bush 6 and, therefore, the valve.

The lockbolt 23 also carries a projection 22, such that the lockbolt can be introduced into one of the blind bores 9 only if at the same time the projection 22 is able to engage in the peripheral groove 21 in the adjusting nut 1 9. The lock cylinder 25 is located positively and'without provision for movement in a blind bore 2c in the casing 2, by means of a screw-threaded pin 28 which is riveted in position to prevent accidental detachment. The cylindrical head 29 of the lock cylinder 25 extends into a recess 30 in lockbolt 23 and thus secures the same against rotation while also limiting its axial travel. The lock cylinder 25 has a pin 26 which extends into a groove 27 in the lockbolt 23 and thus controls the movement thereof.The lock cylinder pin 26, because of its eccentric position, converts rotation of the lock cylinder 25 into an axial movement of the lockbolt 23.

A key 31 is so arranged and constructed that it can be withdrawn only when the lockbolt 23 is in a required position-the locked position in this embodiment.

To indicate and display the position of the adjusting nut 1 9 a position indicator is provided in the form of a pointer 32 which has an inwardly extending projection 33 engaging in the groove 21 of the nut 19. The pointer is held from above by a disc 34 which is rigidly attached to the bush 6 and is marked with the position of the bores 9. The pointer 32 follows the axial movements of the nut 1 9 and therefore shows, in relation to markings on disc 34, when the lockbolt 23 can be introduced into one of the bores 9i.e., when the valve is in a position to be locked.

Figure 4 illustrates an alternative embodiment of the adjusting nut. In this case the nut 19a has no peripheral groove and is lengthened at its end 35 remote from the head of the screw-threaded spindle. The nut end 35 extends into a casing having a microswitch 36 which is operated by the nut end 35 at a predetermined position. Also there is a sleeve 37 which extends around the nut 1 9a and can move axially with the nut 1 9a but is not rotatable, and which is open towards the bush 6, the sleeve 37 being formed with a groove engaged by the lockbolt projection 22. At the ends of the sleeve 37 are inward projections 38 each engaging in a peripheral groove 39 in the nut 19a. The grooves 39 are spaced from the central zone of the nut 19a, in which zone the axial teeth 20 engage with the screw-thread 10 of the bush 6. This feature obviates any reduction in thickness of the axial teeth 20 where it engages with the screw-thread 10.

Figure 5 illustrates another modification wherein a second lock cylinder 25a is provided, for actuation of the lockbolt 23, on the side opposite from the first lock cylinder 25; each lock cylinder 25, 25a is operated by a different key.

Also, this embodiment includes a microswitch 40 which is actuated when the lockbolt 23 is in its open position. The microswitch can be used, for instance, for remote transmission of the indication of lockbolt position.

Claims

1. An adjustable lock for a rotary element such as a valve, including a casing, a locking bush connected for rotation with the rotary element, an adjusting nut co-operating with the bush, and an adjustable lockbolt moveable between two positions by means of a lock cylinder operated by a removable key, and in which the locking bush is formed on its periphery with a number of radial recesses and with an external screw-thread engaged by axial toothing on the adjusting nut, the adjusting nut is mounted on a screw-threaded spindle and is formed with or connected to a part moving axially and having a recess or groove, the screw-threaded spindle is rotatably mounted in a bore in the casing, is held against rotation by at least one spring detent engaging a recess in part of the spindle, and can be turned by means of a special key only after release of this detent, and the lockbolt has a projection which can engage in the recess in the adjusting nut only when the lockbolt is in a position to enter one of the radial recesses in the locking bush.

2. A lock according to claim 1, in which the axial toothing of the adjusting nut is interrupted substantially at its mid-point by a peripheral groove.

3. A lock according to claim 1, in which the adjusting nut is surrounded by a sleeve which is partly open towards the locking bush and which is axially movable, but not rotatably connected with the adjusting nut and which is formed with a groove engageable by the lockbolt projection.

4. A lock according to any of claims 1 to 3, in which'the radial recesses in the locking bush are blind bores and the lockbolt projection is a cylindrical pin.

5. A lock according to any of claims 1 to 3; in which the radial recesses in the locking bush are perpendicular grooves and the lockbolt projection engaging in them is of rectangular section.

6. A lock according to any of claims 1 to 3, in which the radial recesses in the locking bush are spaces in the toothing and the lockbolt projection which engages in the spaces has a wedge-spaced head.

7. A lock according to any of claims 1 to 6, in which the external screw-thread of the spindle is a multi-start thread.

8. A lock according to any of claims 1 to 7, including at least three spring detents to engage selectively in at least three recesses in the head of the spindle.

9. A lock according to any of claims 1 to 7, in which the number of recesses in the spindle head differs from the number of spring detents.

10. A lock according to any of claims 1 to 9, in which two or more lock cylinders engage in a corresponding number of grooves in the lockbolt.

11. A lock according to any of claims 1 to 1 (J, including an indicator element, or pointer visible externally of the casing, which engages in the groove in the adjusting nut or sleeve to indicate position.

12. A lock according to any of claims 1 to 11, in which the adjusting nut is extended axially, and projects outside the casing and is connected externally to a position indicator.

13. A lock according to claim 12, in which the lockbolt end which extends out of the casing acts on an actuating element such as an electric contact of an electrical position indicator.

14. A lock according to any of claims 1 to 13, in which the groove in the locking bush is wider than the associated tongue.

1 5. A lock according to any of claims 1 to 13, in which the locking bush and screw-threaded bush are combined to form a single component.

1 6. An adjustable lock for an adjustable valve, substantially as described with reference to the accompanying drawings.