GB2249161A

GB2249161A - A safety device

Info

Publication number: GB2249161A
Application number: GB9023248A
Authority: GB
Inventors: Robin Baxter
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-10-25
Filing date: 1990-10-25
Publication date: 1992-04-29
Also published as: GB9023248D0

Abstract

A safety device for a control having a rotatable knob 35 arranged to rotate a stem. A first or inner body (20) is securable to the knob 35 preferably by means of a clamp 30, 32. A second or outer body 10 is normally rotatable with respect to the inner body so that the knob cannot be turned. Insertion of a locking means (50) enables the bodies to be locked together so that rotation of the outer body causes the knob to be rotated. The locking means is preferably only removable when the control is in a closed position. As shown for a gas cylinder valve, aligned slots 12, 22 allow a key (50) to enter and turn the inner body (20) on engagement of projections (26). The inner and outer bodies are interconnected by a spiral spring 42 secured at one end to the inner body, its free end acting against a ratchet surface on the outer body. To close the valve, the outer body is rotated and the spring 42 becomes tense and transfers rotation to the inner body and knob 35. When knob 35 resists further rotation, the slots 12, 22 become aligned to allow key withdrawal. The invention may also be applied to a screw cap. <IMAGE>

Description

SAFETY DEVICE This invention relates to a safety device for a rotatable control, such as but not exclusively for a gas valve knob.

It is in the interests of safety that users of gas cylinders, in particular those that may become a hazard when left unattended, are prevented or discouraged from inadvertently leaving such devices in an unsafe condition, particularly when proceeding with another action that may increase the danger of the unattended device. An example of such a situation is in a caravan, in which gas cylinders used for cooking, refrigeration and lighting may cause fires or hazardous gas leakages if they are not turned off before the caravan is moved. These gas cylinders generally have a rotatable control knob which operates the control valve.

It is an object of the invention to provide a safety device which can alert the user to the unsafe condition.

According to the present invention there is provided a safety device for a control having a rotatable knob arranged to rotate a stem comprising a first body securable to the knob or stem and a second body rotatable with respect to the first body wherein the second body may be locked or unlocked to the first body.

The device of the invention can be simply made and the fact that the second body is locked to the first body so that the valve is switchable between an on or unsafe condition and an off position, can be readily indicated to the user.

The safety device of the invention may be designed for use with most types of rotatable knobs which control an operation. One such type of rotatable control knob is used for a portable gas cylinder valve. This is normally turned clockwise to shut the valve against a final closing resistance.

In an embodiment of the invention the closing resistance is used to hold the first body whilst the second body can be rotated in a further clockwise direction to remove a locking means.

The removal of the locking means serves as an indicator to the user that the valve is closed.

In the embodiment of the invention the second body is enabled to be rotated in the further clockwise direction by a ratchet acting between the first and second bodies.

The locking means may be a key which is removable by alignment of apertures in the first and second bodies.

The embodiment of the invention has the first and second bodies formed as concentric cylindrical bodies the outer one of which may be locked or unlocked to the inner one.

The inner body is clamped to a rotatable control knob of a gas valve, such that rotation of the inner body causes rotation of the control knob. The outer body is positioned so as to prevent a user from directly rotating the inner body or the control knob. In order to lock the outer body to the inner body, a locking means, suitably a key, must first be inserted into a key-hole in the safety device. Only then can rotation, by a user, of the outer body cause rotation of the inner body and hence of the gas valve control knob.

This embodiment of the invention is arranged so that the key is prevented from being removed unless the control knob of the valve is in the fully closed position.

In a second embodiment of this invention the key, when removed from the bodies is used to enable a vehicle ignition circuit to be switched on. This provides an additional safety feature to ensure the valve is turned off and is useful for a vehicle arranged to tow a caravan in which the gas cylinder is located.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a safety device according to the invention, Figure 2 is a perspective view of an inner part of the safety device of Fig. 1, the outer part not being shown, Figure 3 is a section through the safety device of Fig. 1, denoted by the line IV-IV of Fig. 4, Figure 4 is a section through the safety device of Fig. 1, denoted by the line III-III of Fig. 3, Figure 5 is a key for the safety device of Fig. 1, Figure 6a is a section through the key of Fig. 5, denoted by the line 6-6 of Fig. 5, and Figure 6b is a section through a different embodiment of the key of Fig. 5, denoted by the line 6-6 of Fig. 5.

Referring to the drawings, an embodiment of a safety device for a valve of a gas cylinder is shown in Figs.

1-4 and an embodiment of a key is shown in Figs. 5 and 6a. A second device, possibly a protective unit for a vehicle ignition system, may be used in conjunction with the safety device. The precise form of the second device is unimportant and is not illustrated, its function being that of a simple lock or other such key or identification controlled system that opens and closes switches on and off, connects and disconnects a circuit, engages and disengages a mechanism, or performs some other such operation when controlled by the correct key or means of identification.

The safety device comprises an outer drum 10 and an inner drum 20, the drums being concentric and able to rotate relative to each other. A mechanism, shown here comprising clamp arms 30 with joints 34 allowing the arms 30 to be hooked over a control knob 35 of a gas cylinder valve, and a screw 32, allow the knob 35 to be clamped to the inner drum 20 so that the inner drum 20 and the knob 35 are unable to rotate relative to each other. The screw 32 can be reached through holes 14 and 24 in the outer and inner drums respectively.A coiled spring 42 in a channel 40 between the inner drum 20 and outer drum 10 has one end 41 affixed to one of the drums 10 or 20 and the other end 43 free but engaging a ratcheted surface 44 so that the outer drum 10 may be rotated freely relative to the inner drum 20 in one direction, but when rotated in the opposite direction the free end 43 of the spring 42 soon engages one of the teeth of the ratcheted surface 44 causing the spring 42 to become tense. When this tension in the spring 42 is sufficient further rotation of the outer drum 10 tends to cause corresponding rotation in the inner drum 20.

Figure 4 shows the fixed end 41 of the spring 42 mounted to the inner drum 20, the free end 43 engaging the ratcheted inner surface 44 of the outer drum 10 and the teeth of the ratcheted surface 44 arranged so as to allow the outer drum 10 to rotate freely in an anticlockwise direction relative to the inner drum 20. This description is based on this arrangement, but similar arrangements are possible with the ratcheted surface 44 being on the outer surface of the inner drum 20 and the fixed end 43 of the spring 42 being mounted on the inside surface of the outer drum 10, and the arrangement of the teeth of the ratcheted surface 44 can be changed to allow different rotation characteristics of the drums 10 and 20 relative to each other, if the device is to be used for a different type of rotatable control.

In order to use this safety device on a standard gas cylinder whose control knob is rotated anticlockwise to open the gas valve, the safety device is clamped onto the knob 35 when the knob is in its extreme clockwise position, the valve then being shut. Thus, with the arrangement of drums 10 and 20, spring 42 and ratcheted surface 44 of the previous paragraph, the outer drum 10 can be rotated freely in direction A while having no effect on the inner drum 20 and consequently no effect on the knob 35 of the gas valve. Rotation in direction B causes the free end 43 of the spring to engage a tooth of the ratcheted surface 44, then tension to be built up in the spring, which acts only to force the knob 35 to close the valve more firmly.

To open the valve, a key 50 is inserted through an opening in the outer drum 10, made up of a slot 12 and a hole 14, and through an opening in the inner drum 20, made up of a slot 22 and a hole 24. The shape of these openings need not be as shown in the drawings, particularly if greater security is required. The key 50 is fully inserted, this being achieved when the collar 52 abuts the outer surface of the outer drum 10. An outer member 54 of the key 50 is therefore positioned in the slot 12 and an inner member 56 of the key 50, having passed through slot 22, is positioned inside the inner drum 20. On rotation of the outer drum 10 in direction A, the key 50, being positioned with member 54 in slot 12, also rotates in direction A.Member 56, rotating as part of the key 50, eventually engages a protrusion 26 mounted on the inside surface of the inner drum 20, and thus causes the inner drum 20, and consequently the knob 35 of the gas valve, to rotate in direction A. The valve can thus be opened only when the key 50 is inserted.

The member 56 of the key 50 must be aligned with the slot 22 for the key 50 to be removed. Having engaged the protrusions 26, the member 56 is unable to reach a second position of alignment with slot 22 by rotating in direction A with the outer drum 10. The key 50 thus cannot be removed at this stage.

To close the valve, the outer drum 10 is rotated in direction B which causes the free end 43 of the spring to engage one of the teeth of the ratcheted surface 44. The spring 42 becomes tense and transfers this rotation to the inner drum 20 which thus rotates in direction B and keeps the slot 22 ahead of and out of alignment with the member 56 of the key 50. As the inner drum 20 rotates in direction B, the knob 35 rotates with it towards its closed position. When the valve is closed, the knob 35 of the valve resists further rotation in direction B and allows the tension in the spring 42 to build up, since the inner drum 20 cannot follow the rotation of the outer drum 10. The member 56 of the key 50 can then reach alignment with the slot 22 allowing the key 50 to be withdrawn and applied to another operation or used otherwise as required.The key 50 can thus only be removed when the valve is in the fully closed position.

Other embodiments of this invention have key 50 and corresponding slots 12 and 22 shaped differently for increased security to prevent use by unauthorised users.

These are not illustrated.

Further embodiments of this invention have a key and correspondingly slots 12 and 22 shaped differently to prevent accidental misuse. The key 50 illustrated in Figs. 5 and 6a has a spacer 58 between members 54 and 56 positioned so that if the key 50 is only partly inserted so that member 56 is positioned within slot 22, instead of being inserted through slot 22, the member 54 does not engage the slot 12 of the outer drum 10, thus avoiding the situation whereby the key 50 locks the two slots 12 and 22 in alignment, thus allowing the key 50 to be removed even when the valve is open. Another embodiment of a key 50 is shown also by Fig. 5 but has a cross-section as shown in Fig. 6b.The shape of the member 57 is designed so as to move out of the slot 22 towards the correctly functioning position within the inner drum 20 if an attempt is made to operate the valve when the key 50 is only partly inserted. Other embodiments of this invention provide similar precautionary measures by different positioning and shape of the key parts 52, 54, 56, 57 and 58, of the slots 12 and 22, of the holes 14 and 24 and of the protrusions 26.

The collar 52 of the key may be spring loaded so that the key would partially eject itself once the slots 12 and 22 were aligned.

The uses of this safety device are not intended to be limited to the situations described earlier. Many other types of valves, knobs, handles or taps may benefit from similar protection, and a version of this safety device, possibly with an adapted clamping mechanism, and possibly designed to allow and disallow different rotation characteristics of the knob, may be designed for use on most if not all types of turnable control knobs, not solely on fluid containers.

The device of the invention may be used in certain circumstances to prevent a knob from being turned from a position intermediate between the extremes of its movement. For example where a valve is set for a particular flow the device can be used to prevent this setting from being changed. The device of the invention could also be construed as part of the control knobitself, rather than being clamped onto it. The device of the invention could also be incorporated within the scew cap of a bottle, or other container, to discourage or prevent unauthorised opening.

Claims

1. a safety device for a control having a rotatable knob arranged to rotate a stem, comprising a first body securable to the knob or stem and a second body rotatable with respect to the first body, wherein the second body may be locked to and unlocked from the first body.

2. A safety device as claimed in claim 1 wherein the first and second bodies are formed as concentric cylindrical bodies, the outer one of which may be locked to or unlocked from the inner body.

3. A safety device as claimed in claim 2 wherein the inner body is enabled to be clamped to a rotatable control knob such that rotation of the inner body causes rotation of the control knob.

4. A safety device as claimed in claim 2 or 3 wherein the outer body encloses the inner body such that a user is prevented from directly rotating the inner body.

5. A safety device as claimed in any one of claims 2 to 4 wherein an aperture is provided in the outer body and a corresponding aperture in the inner body through both of which holes a locking means can be inserted and removed by alignment of the apertures.

6. A safety device as claimed in claim 5 wherein the locking means can only be removed when the control is in a closed position.

7. A safety device as claimed in any one of claims 1 to 6 wherein a ratchet arrangement is provided between the first and second bodies.

8. A safety device as claimed in claim 7 wherein the ratchet arrangement comprises a ratchet on the second body and a resilient means on the first body which engages with the ratchet to rotate the stem in a valve closing direction.

9. A safety device for a control having a rotatable knob arranged to rotate a stem, substantially as described with reference to the accompanying drawings.