GB2219377A

GB2219377A - Control knobs

Info

Publication number: GB2219377A
Application number: GB8812615A
Authority: GB
Inventors: Ian Hollingsworth; Alan Constable
Original assignee: Valor Heating Ltd
Current assignee: Valor Heating Ltd
Priority date: 1988-05-27
Filing date: 1988-05-27
Publication date: 1989-12-06
Also published as: GB8812615D0

Abstract

Control knobs, e.g. on domestic gas or electric appliances, normally project beyond the profile of the appliance, destroying the aesthetics of the appliance, or are set in a recess, and providing a trap for dust etc. The present control knob comprises a main member (3) rotatably seated within a hollow cylindrical housing (1). The main member (3) has a portion (11) which can be gripped by the user and a securing portion (13) which can be attached to a control spindle. A disc-shaped screen member (7) fits around the gripping portion (11) and inside the cylindrical housing (1) and is biassed, e.g. by springs 33, towards a position where it is flush with the end face of the gripping portion (11) and an end edge (19) of the housing (1). Thus the control knob is hidden from view when in the off-position. To turn the knob the screen member (7) is depressed and the main member (3) rotated. <IMAGE>

Description

DESCRIPTION IMPROVEMENTS RELATING TO CONTROL KNOBS.

The present invention relates to a control knob for use on any type of appliance.

In particular the present invention relates to a control knob which can be used on a domestic gas or electric appliance such as, for example, a gas fire.

Such control knobs usually either project upwardly from the outer surface of the appliance, thus destroying the smooth aesthetic profile of the appliance, or are set in a recess to maintain the smooth profile of the overall design. However, when recessed to, for example, eliminate wobble in the connection with spindles running to gas taps and electrical switches, they provide a trap for dust, dirt, etc., which is, in a lot of designs, difficult to keep clean. Further, such recessed arrangements can prove as unsightly as the projecting control knob arrangements.

The aim of the present invention is to provide a control knob which does not affect the aesthetics of a gas or electrical appliance, at least when in the off-position.

According to the present invention there is provided a control knob for an appliance, comprising a main member having a portion which, in use, can be gripped to enable the knob to be rotated, and a screen member which has an aperture formed therein which is complementary with said portion of the main member, said screen member being axially movable along said portion of said main member against spring means, to thus reveal said portion of said main member.

In a preferred embodiment of the present invention the main member has a radially outwardly projecting disc portion which is rotatably seated in a hollow cylindrical housing, with the said portion of-said main member being generally rectangular and extending axially of the said disc portion in one axial direction; a securing portion for attaching the knob to a shaft to be controlled, extending from said disc portion in the other axial direction. Said generally rectangular portion of the main member is dimensioned such that its end face is coplanar with an axial end edge of the cylindrical housing. Further, said screen member is a planar disc with an aperture complementary in shape to the transverse cross-section of said generally rectangular position of the main member, and with a diameter complemenetary to the internal dimension of said cylindrical housing.The axial end edge of the housing, together with the screen member and the end face of the generally rectangular portion of the main member, can form a smooth surface so that when the cylindrical housing is seated flush in the wall of an appliance, the central knob in this position is effectively hidden and does not affect the overall aesthetics of the appliance. To maintain the screen member in this latter position legs extend axially of the disc-shaped screen member and pass through apertures in the disc portion of said main member and are secured to a generally disc-shaped key member located contiguous to the said disc portion of the main member. A coiled spring is located over each leg between the screen member and said disc portion, to thus maintain said latter position of the screen member.In this said latter position of the screen member radial projections on the disc-shaped key member engage in axial slots in the wall of the cylindrical housing, thus locking the control knob in the hidden, off-position. To operate the control knob, the screen member is depressed into the housing, against said springs, to reveal the generally rectangular portion of said main member. This movement also moves the key member axially so that the radial projections of the key member clear the end of said axial slots in the housing.The knob can then be rotated by applying a twisting pressure to said generally rectangular portion of the main member, the radial projections of the key member engaging the other axial end edge of the cylindrical housing so that the screen member is held in the depressed position with the springs compressed, exposing the said generally rectangular portion of the main member whilst the control knob is in other than the fully-off position.

Whilst the main member has a generally rectangular portion in the above preferred embodiment, this latter portion may have any desired transverse cross-section provided the aperture in the screen member is of complementary shape.

The control knob of the present invention may thus be only exposed when operational. Otherwise, the knob is flush with the exterior configuration of the appliance.

The present invention thus provides a visible indication of when the appliance is other than in the OFF position, thereby enhancing safety by a visible warning of possible hazard, when otherwise no indication of the hazard is obvious; for example a gas fire where gas has been extinguished but is still flowing, or any electrical appliance where no visible or audible indication of power supply being on is apparent.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a plan view of a preferred embodiment of the present invention; Fig.2 is a side view of the embodiment of Fig.l; Fig.3 is an axial cross-sectional view of the embodiment of Figs. 1 and 2 when in the off-position; and Fig.4 is an axial cross-sectional view as shown in Fig.3 but with the screen member depressed.

The preferred embodiment of the present invention illustrated in the accompanying drawings comprises a hollow cylindrical housing 1 within which a main member 3, key member 5 and a screen member 7 are located.

The main member 3 has a disc-shaped portion 9 which is snugly seated within the cylindrical housing 1 so as to be rotatable about the longitudinal axis of the housing 1. A generally rectangular gripping portion 11 extends axially of said disc-shaped portion 9 in one axial direction and a securing portion 13 for attachment to a control shaft (not shown) extends in the other axial direction. Said securing portion 13 has a recess 15 into which the control shaft can be securely engaged.

The screen member 7 is disc-shaped and has a central elongate aperture 17 which is complementary in shape to the transverse cross-section of said generally rectangular gripping portion 11. The disc-shaped screen member 7 is likewise complementary to the inside diameter of the cylindrical housing 1.

Thus, in the position illustrated in Fig.3, the axial end edge 19 of the cylindrical housing 1, the screen member 7 and the end face 21 of the gripping portion 11, together form a flush planar surface, so that with the cylindrical housing 1 secured in an aperture in a wall of an appliance by flexible snap locks 23, the control knob presents a continuous flush surface so that the overall aesthetics of the appliance are maintained.

To maintain the above screen member position, the screen member 7 has two axially depending legs 25, each of which extends through an aperture 27 in the disc-shaped portion 9 of the main member 3. The free end region of each leg 25 is secured in an aperture in the key member 5 by a shoulder 29 and spring clip 31, and a coiled spring 33 is engaged over each leg 25 between the screen member 7 and said disc-shaped portion 9 of the main member 3. The springs 33 thus bias the screen member 7 to the position illustrated in Fig.3, i.e. the off-position of the control knob.

The key member 5 has two diametrically opposed, radially extending projections 35 which, in the off-position of Figs. 2 and 3, engage in open-ended axially extending slots 37 formed in the other axial end edge 39 of the cylindrical housing 1. When the control knob is to be used, i.e. rotated from the off-position, the screen member 7 is first manually depressed to compress springs 33 and reveal the gripping portion 11. This axial movement of the screen member 7 causes the legs 25 to move axially through apertures 27, key member 5 thus also moving axially so that the radial projections 35 move out of the slots 37. The control knob can then be rotated as required by applying a twisting movement to the generally rectangular gripping portion 11.With this rotation the radial projections 35 engage the other axial end edge 39 of the cylindrical housing 1 so that the screen member 7 is maintained in the depressed condition of Fig.4 until the main member 3 is returned to the off-position whence the projections 35 engage on the slots 37 allowing the springs 33 to return the screen member 7 to the flush position of Fig.3.

Besides snap locks 23 which engage behind the lip of an aperture in an appliance, the cylindrical housing 1 has a radial key projection 41 which can engage in a recess in the appliance aperture lip to correctly orientate the control knob on the appliance.

If desired, indicia to indicate the rotational position of the knob, can be provided on the inner wall of the housing 1 so that they are also only exposed when the screen member 7 has been depressed.

Whilst the above described preferred embodiment of the present invention utilises a generally rectangular gripping section 11, having a generally rectangular transverse cross-section (see Fig.l), any transverse cross-section can be used provided the aperture 17 on the screen member 7 is of complementary cross-section.

The present invention thus provides a control knob for an appliance, which, in the off-position at least, presents a smooth continuous profile with the surrounding surface of the appliance, and thus does not detract from the overall aesthetics of the appliance. By omitting the projections 35 on the key member 5, the screen member 7 will always return to the flush position of Fig.3, no matter what the notational setting of the knob.

Claims

1. A control knob for an appliance, comprising a main member having a portion which, in use, can be gripped to enable the knob to be rotated, and a screen member which has an aperture formed therein which is complementary with said portion of the main member, said screen member being axially movable along said portion of said main member against spring means, to thus reveal said portion of said main member.

2. A control knob as claimed in claim 1, in which the main member has a radially outwardly projecting disc portion which is rotatably seated in a hollow cylindrical housing, with the said portion of the main member extending axially of the disc portion and said housing in one direction, and a securing portion for attaching the knob to a shaft to be controlled, extending from the disc portion on the other axial direction.

3. A control knob as claimed in claim 2, in which said portion of the main member has a planar end face which is coplanar with one axial end edge of the cylindrical housing.

4. A control knob as claimed in claim 3, in which the screen member is a planar disc with an aperture complementary in shape to the transverse cross-section of said portion of the main member, and with a diameter complementary to the internal diameter of said cylindrical housing.

5. A control knob as claimed in any one of claims 1 to 4, in which said portion of the main member has a generally rectangular transverse cross-section.

6. A control knob as claimed in claim 3 or 4, in which the screen member has axially extending legs which pass through apertures in the disc portion of the main member and are secured to a generally disc-shaped key member located adjacent to the disc portion of the main member.

7. A control knob as claimed in claim 6, in which a coiled spring is located over each key between the screen member and disc portion of the main member to thus bias the screen member to a position where it is coplanar with the said one axial end edge of the housing.

8. A control knob as claimed in claim 7, in which the disc-shaped key member has radially extending projections which engage in axial slots in the wall of the cylindrical housing when the screen member is coplanar with said one axial end edge of the housing, which move along said slots when the screen member is depressed against said springs, and which can engage the other axial end edge of the cylindrical housing when the main member is rotated.

9. A control knob for an appliance constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.