ZA200808959B

ZA200808959B - Control wheel

Info

Publication number: ZA200808959B
Application number: ZA200808959A
Authority: ZA
Inventors: Lewthwaite John Edward
Original assignee: Lewthwaite John Edward
Priority date: 2007-10-24
Filing date: 2008-10-20
Publication date: 2009-11-25

Description

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CONTROL WHEEL | IK

FIELD OF THE INVENTION

This invention relates to a control wheel. : BACKGROUND TO THE INVENTION

In the field of fluid control, particularly cryogenic fluid control, operating spindles and shafts are often over tightened in either an open or closed position causing damage to equipment such as flow control valves.

OBJECT OF THE INVENTION

It is accordingly an object of the present invention to provide a novel control wheel, which it is believed, will overcome or at least alleviate the above mentioned problem.

SUMMARY OF THE INVENTION

: According to the invention there is provided a control wheel comprising:

- an inner hub which is adapted to be coupled to a shaft; - an annular outer rim located co-axially in cooperation with the outer periphery of the inner hub; and - coupling means for coupling the inner hub to the outer rim when a predetermined rotational torque on the outer rim is exceeded.

The coupling means may include a cam profile and a plurality of follower : members including biasing means for engaging the cam profile and which are biased towards the cam profile so that upon the predetermined rotational torque on the outer rim being exceeded, the follower members move along the cam profile against the action of the biasing means.

The cam profile may include a olurality of pocket formations, which are each adapted to receive a head formation of each of the follower members.

The pocket formations may be defined by the inner surface of the outer rim structure and the follower members may be radially disposed in the inner hub.

Alternatively, the pocket formations may be disposed on the outer surface of : the inner hub and the follower members may be directed radially inwardly from the outer rim.

BRIEF DESCRIPTION OF THE DRAWINGS :

The invention will now be described further by way of a non-limiting example with reference to the accompanying drawings wherein:

Figure 1 is a sectioned exploded view of a control wheel in accordance with a preferred embodiment of the invention;

Figure 2 is a schematic partially assembled representation of the control wheel in Figure 1;

Figure 3 is a schematic plan view of the control wheel in Figure 1 in an assembled condition without a cover plate;

Figure 4 is a schematic plan view of the control wheel in Figure 1 in an assembled condition without the cover plate, indicating slippage between an inner hub and an outer annular rim of the : 20 control wheel; and .

Figure 5 is a schematic perspective view of the control wheel in Figure 1

$£2008 /08959 ; in an assembled condition.

DETAILED DESCRIPTION OF DRAWINGS

The control wheel in accordance to the present invention is adapted to be operated manually, however, the invention is equally applicable to control wheels which could be driven mechanically by suitable means such as motors, gears, and the like, which are not shown.

The control wheel of the invention comprises an inner hub 10 which is designed to be secured co-axially to an operating spindle, shaft or the like, (not shown), which in turn operates a valve or other mechanism (also not shown). An outer annular rim 11 is mounted on the outer periphery of the inner hub 10 and it is co-axially rotatable relative to the innerhub 10. In use, the outer rim 11 will be rotated manually and may include gripping formations such as spokes 11a, an outer gripping structure 11b and the like, to aid in gripping and rotating the outer rim 11.

The inner surface of the outer annular rim 11 defines a cam profile 12 which is engaged by a plurality of follower members 13, which radiate outwardly : from the inner hub 10 and which are biased towards the cam profile 12 by biasing means, such as a compression spring 14. In the arrangement illustrated, the cam profile 12 includes a plurality of indentations or pocket formations 12a, which each receive an end or head section 13a of a follower member 13. Further, in the arrangement illustrated the follower members 13 are in the form of tubular capsules which each terminates in a head formation 13a and which each defines a bore 13b within which one of the compression springs 14 is disposed. Each compression spring 14 has a predetermined compressive force so that the capsule 13 is urged radially outwardly with a predetermined force.

The depth of the pocket formations 12a, the angles of the side walls 12¢ thereof, and the strength of the compression springs 14 will determine the angular torque which can be applied to the outer rim 12 before the latter is able to rotate relative to the inner hub. These can therefore be varied and adjusted in accordance with the requirements of any particular control wheel.

It will be understood that in a different arrangement, which is also included within the scope of the invention, the cam formation 12 could be defined on the outer surface of the inner hub 10 and the follower members 13 disposed in the outer rim 11 and directed radially inwardly to engage the cam formation 12.

A further feature of the invention provides for the provision of a cover plate 15 which is adapted to cover the follower members 13 and the cam formation

+ 2008 /08959 i ; 12 to prevent tampering therewith.

The cover plate 15 is fixed to the inner hub 10 by means of threaded fasteners 16, which engage threaded apertures 17 in the hub 10. The fasteners 16 comprise a threaded shank 16b, a shoulder formation 16a adapted to engage the cover plate 15, and a drive formation 16c adapted to rotate the fastener 16, the arrangement being one wherein the drive formation 16¢c is removable from the shoulder formation 16a by means of cutting, grinding, or the like to prevent removal of the fastener 16 from the hub 10. With such an arrangement therefore the fastener 16 can only be removed from its position in the hub by a machining operation such as drilling.

A central aperture 16d which remains after removal of drive formations 16c¢ will indicate the position of the fastener 16. : Doubtless variations of the invention exist without departing from the orinciples set out in the appended claims and it is intended that these should all fall within the scope of this disclosure.

Claims

Clim CLAIMS

1. A control wheel comprising an inner hub which is adapted to be coupled to a shaft; an annular outer rim located co-axially in cooperation with the outer periphery of the inner hub; and coupling means for coupling the inner hub to the outer rim when a predetermined rotational torque on the outer rim is exceeded.

2. A control wheel according to claim 1 wherein the coupling means includes a cam profile and a plurality of follower members including biasing means for engaging the cam profile and which are biased towards the cam profile so that upon the predetermined rotational torque on the outer rim being exceeded, the follower members move along the cam profile against the action of the biasing means.

3. A control wheel according to claim 2 wherein the cam profile includes a plurality of pocket formations, which are each adapted to receive a head formation of each of the follower members.

4. A control wheel according to claim 3 wherein the pocket formations are defined by the inner surface of the outer rim structure and the follower members are radially disposed in the inner hub. :

5. A control wheel according to claim 3 wherein the pocket formations are disposed on the outer surface of the inner hub and the follower members are directed radially inwardly from the outer rim.

6. A control wheel substantially as herein described with reference to the accompanying figures. Dated this 35 day of OAs 200% Patent Ny / Agent for the Applicant