GB2261484A - Adjustable link - Google Patents

Abstract

An operating link for connecting apparatus having a variable distance therebetween comprises telescopic male and female members 43, 38 urged apart by a spring 42, the male member having an indentation 44 and the female member being deformable into permanent engagement with said indentation to lock the link at a fixed length. The link is especially suitable for automated assembly of apparatus having a wide tolerance band, such as domestic appliances, and is shown connected to the flap valve 31 of a flue damper of a gas cooker. The link is adjusted so that the operation of the flap valve is properly coordinated with the opening of a gas tap. <IMAGE>

Description

ACTUATOR LINK This invention relates to an actuator link for a domestic appliance and particularly for a flue damper of a gas cooker.

The ovens of gas cookers require a small throughput of fresh air in order to ensure proper combustion of the fuel gas. Accordingly such ovens are usually provided with a flue to permit venting of combustion products to atmosphere.

The flue must be designed to exhaust combustion products produced throughout the operating range of the gas burners, and accordingly the flue cross-sectional area is chosen to suit the maximum gas consumption rate of the burners, and hence the maximum air throughput required to support complete combustion.

It follows that at less than maximum gas consumption rate, the flue cross sectional area is too large and excessive heat is lost through the flue. Accordingly dampers have been proposed to restrict the flue opening, and these dampers are usually controlled indirectly by the appropriate gas regulating tap. In a combined oven and grill it may for example be arranged for the damper to adopt a first position during oven operation and a second, more closed, position during grill operation.

In a conventional gas cooker the flue is at the back whereas the gas controls are at the front. The manufacturing tolerance build-up between a gas tap and a flue damper can be quite large, possibly as much as 5 mm.

Typically a pressed steel cooker chassis comprises several pressings to which at the back a flue and damper assembly is attached; at the front the gas taps are mounted on a gas rail which is itself supported on the chassis by other components. Providing means to compensate for such manufacturing tolerances is expensive and increases the cooker assembly time. Typically adjustment may be provided by left and right handed threaded rods connected by a turnbuckle and having lock nuts to retain the setting. Such adjustment requires a skilled worker and is not particularly suitable for automated assembly; it also has the disadvantage that the adjuster may work loose in service or may be adjusted by an unskilled person who could dangerously affect proper combustion of the fuel gas.

The same problem of a build up of manufacturing tolerances arises with other appliances, such as washing machines, which are also assembled from pressings.

A further problem with existing flue damper control mechanisms is that hitherto, the operative connection between the gas tap and the flue damper operating rod has been complicated and awkward to assemble. Typically movement of the control rod relies on an interlock mechanism associated with the relevant gas tap but not operated directly thereby.

Accordingly the present invention proposes a simple adjustment device which may be permanently set during assembly of the appliance, which has a wide range of adjustment and which is suitable for automated assembly.

The invention further provides for direct operation of a flue damper control rod by the relevant gas tap.

According to one aspect of the invention there is provided a flue damper for a gas cooker and comprising a flue, a flap valve pivotable in the flue from an open to a closed condition, an actuator, and a link between said flap valve and actuator, said link comprising telescopic members having spring means urging the members apart, the male telescopic member having at least one indentation and the female member being deformable into permanent engagement with said indentation.

Preferably the male member comprises a round steel rod having a plurality of circular indentations, said female member being of aluminum alloy and housing a compression spring to urge the members apart.

In practice the flue and damper are assembled at one side of the cooker, and the gas tap assembled to the other side. The link means is placed in position and the spring ensures that the male and female members are moved to extremes of permissible travel. The female member is then crimped once onto the indented male form giving a secure and permanent connection.

The spring ensures that the link is self adjusting when in a position, thus obviating the need for a skilled operator, and the crimping operation likewise requires no skill and may be readily performed by jaws of a robotic arm.

In a preferred embodiment said actuator is a gas tap having a cam profile for abutment with a free end of said link means; the cam profile may for example by shaped to open said flap valve in a pre-determined manner as the gas supply to the oven is increased.

According to another aspect of the invention there is provided an operating link for apparatus having a large manufacturing tolerance between operative ends of the link, the link comprising telescopic male and female members having a spring to urge the members apart, the male member having an indented form and the female member being deformable into permanent engagement with said indentation.

Such a link is especially useful in domestic appliances which have a large manufacturing tolerance between one side of the appliance and another; the link is also suitable for installation and setting by automated production machinery.

According to yet another aspect of the invention, there is provided apparatus for direct actuation of an operating link for a flue damper of a gas cooker.

Preferably the apparatus comprises a cam adapted for fixed rotation with the spindle of a gas tap, and support means for supporting an operating link in operative engagement with the cam surface of said cam.

In a preferred embodiment said cam surface is between planes generally orthogonal to the axis of said spindle, and said operating link is urged into engagement with said cam surface by spring means.

Such an arrangement gives direct actuation of the flue damper. The apparatus is economical to manufacture and easy to assemble; no setting or interlock mechanism is required, and no lost motion is present.

In combination with the adjustable operating link above mentioned, the direct actuation apparatus provides a simple, economical and reliable mechanism for transferring motion directly from a gas tap to the flue damper of a gas cooker. Such a combination is also suitable for direct actuation in other domestic appliances where wide tolerance bands may be encountered but the need for skilled assembly labour is to be avoided.

Other features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only with reference to the accompanying drawings in which: Fig. 1 is a partial section through a gas oven incorporating the invention; Fig. 2 is a partial isometric view of one end of a link according to the invention; and Fig. 3 is an isometric view of the other end of the link of the invention.

With reference to Fig. 1, a gas cooker has an upper oven ii and a lower oven 12 (partially shown). Each oven has a respective door 13,14. As illustrated the upper oven 11 has an upwardly extending flue 15 having an exhaust opening 16 at the upper end thereof. The lower oven 12 also has a flue similar to flue 15 but not shown in the drawing.

At the front of the cooker is a transversely extending gas rail 21 having a plurality of gas taps mounted thereon at spaced locations. A gas tap 22 for the upper oven is illustrated. The gas tap 22, rail 21 and top of the cooker are covered by a hob pressing 23 on which are mounted the usual burners (not shown). The hob pressing 23 is mounted on an upstanding wall 25 at the rear of the cooker and secured to the front of the cooker by any convenient means.

Gas tap 22 has the usual control knob 24 which may be rotated to control the flow of fuel gas from the gas rail 21 to burners in the upper oven 11.

The flue damper is now described with additional reference to Fig. 2. A flap valve 31 has a spindle 32 journalled in opposite sides of the flue and is pivotable in the flue between open and closed conditions; the flap is secured to the spindle by screws 33. A coiled torsion spring 34 around the spindle 32 has free arms 35,36 secured one against the wall of the flue 15 and one against the flap valve 31, thereby to urge the flap valve to the open condition. The flue wall may incorporate a stop to prevent over-travel of the flap valve from the open condition.

Pivotally secured to the flap valve 31 is a first operating rod 37 having a female free end 38; the rod 37 passes through an aperture 39 of the flue wall and the wall 25 as illustrated. The aperture 39 is elongate to permit the rod 37 to be attached to one of several alternative positions 41 along the flap valve, thereby to permit variation of the location of the gas tap 22 along the gas rail 21.

A light coil spring 42 is provided to fit within the female end of rod 37 and a second operating rod 43 having a series of circular spaced indentations 44 at the adjacent end thereof. The rod 37, spring 42 and rod 43 are shown exploded to facilitate description. The diameter of the coil spring 42 is such that it will urge the rods 37 and 43 apart as is further described below.

With reference to Fig. 3 a conventional gas tap 22 has an outlet pipe 45 for supply of gas to the upper oven 11.

The spindle 46 of the tap carries a cam 47 against which abuts the end of rod 43 remote from the flap valve. The rod 43 is urged against the cam 47 by the flap valve spring 34 in the manner described below and thus rotation of the spindle 46 causes the rod 43 to follow the cam profile, thereby moving the rod 43 back and forth along its longitudinal axis.

On assembly the light spring 42 and rod 43 are inserted into female end 38 and the gas tap 22 and flue assembly secured to the cooker chassis. The torsion spring 34 will hold the flap valve 31 open and the gas tap spindle 46 is placed in the open position.

The light spring 42 urges rods 37 and 43 apart but is insufficiently strong to overcome the pre-load of torsion spring 34. The light spring 42 ensures that the rods 37,43 take up any manufacturing tolerance which might result in the gas tap 22 and flap valve 31 being fixed at slightly different positions on the cooker chassis, or manufacturing tolerances in the cooker chassis itself.

The female member is then crimped onto the male member to permanently secure the rods 37 and 43 in the correct relative positions. To facilitate crimping the rod 37 is preferably of a soft material such as an aluminium alloy whereas the rod 43 is preferably of mild steel.

The invention thus provides a simple and secure method of taking up manufacturing tolerances, which does not require skilled labour for assembly and adjustment, which is self setting, and which is suitable for automation.

Although the invention has been described with setting of rods 37,43 with the flap valve in the open condition, the setting could alternatively be made by moving the flap valve to the closed condition against the effect of torsion spring 34 before crimping the rod 37, the cam 47 having been placed in a position corresponding to a closed gas tap.

Claims (8)

CLATMS:

1. An operating link for connecting apparatus having a variable distance therebetween, said link comprising telescopic male and female members having respective free ends for attachment to said apparatus and a spring operable to urge said members apart, the male member having an indented form and the female member being deformable into permanent engagement with said indentation.

2. A link according to claim 1 wherein said spring is within said female member.

3. A link according to claim 2 wherein said spring is a coil spring operable between the inner end of the female member and the adjacent end of the male member.

4. A link according to any preceding claim wherein the male member is round and has a plurality of circular indentations.

5. A link according to any preceding claim wherein the male member is of steel and the female member is of a deformable aluminum alloy.

6. A domestic appliance incorporating a link according to any of claims 1-5, said appliance having control means mounted at the front thereof, and a mechanism associated with said control means mounted at the rear thereof, said control means and mechanism being operatively connected by said link, one end of said link being movable in the telescoping direction by a cam of said control means.

7. An appliance according to claim 6, the appliance being a gas cooker and said mechanism being a flue damper thereof.

8. An operating link substantially as described herein with reference to the accompanying drawings.