CONTROLS FOR ELECTRICAL HEATING APPLIANCES

Abstract: An energy regulator having a rotary control member has an integral indicator for indicating visually the state of the heating means in use. The indicator may be provided adjacent the main control housing, or in certain embodiments, in the control member itself. The indicator may also indicate the power setting of the heating means.

Description: Controls for Electrical Heating Appliances The present invention relates to control units in the form of energy regulators or thermostats, for example, for the heating means of electrical heating appliances such as cooker hot plates, hobs, grills and electrical ovens, of a type comprising rotary control members. In electric cookers or hobs it is usual, for reasons of economy, to provide a single neon indicator on the cooker to indicate that one of the hot plates is energised. The indicator remains illuminated whilst any of the hot plates is on and is not extinguished while the hot plates cycle during their normal operation. This is not satisfactory since not only does the indicator give no indication as to which hot plate is energised, but also the electrical wiring of, for example, four separate hot plate control units to a remote indicator is both time consuming and expensive, requiring the provision of two lengths of wire with four push-on connectors for each control unit. More sophisticated appliances may include a separate neon indicator for each hot plate, but there remains the need to wire each indicator to the appropriate control unit during assembly of the appliance and also to mount each indicator separately within the appliance. The present invention seeks to overcome the above problem, and from a first aspect provides a control unit for an electrical heating means, comprising a rotary control member and an indicator, preferably a neon indicator, for indicating visually the state of said heating means in use, the indicator being incorporated in the control unit. Such an arrangement allows separate indicators to be provided for each heating means of an appliance, e.g. for a plurality of cooker hot plates to indicate that a particular hot plate is energised. At the same time, the invention obviates the need for clumsy and relatively expensive electrical wiring between each control unit and a remote single indicator or plurality of indicators in that in accordance with the invention an indicator is an integral part of each control unit and the electrical connections to the indicator are advantageously made during assembly of and within the control unit. Further, since the indicator is incorporated in the control unit, the need for separate means for mounting the indicator within an appliance in addition to the means required in any event for mounting the control unit may be obviated. The control unit may comprise an energy regulator. These devices, which are well known in the art, regulate the power to a load, for example a hot plate, by supplying power to the load over a proportion of a given cycle time determined by the setting of the control member. With such a control unit, the indicator may be connected in parallel with the load through the regulator contacts whereby it will be extinguished whenever the regulator interrupts the power supply to the load. More preferably, however, it is connected in parallel with the load through a separate pair of contacts to those of the regulator, whereby it may remain illuminated while the regulator is cycling, and may be extinguished only when those separate contacts are opened, for example by means operated by the rotary control member when the load is switched off. The invention is not, however, limited to energy regulators, and may also be applied to thermostatic control units, for example, having rotary control members. The indicator may, for example, be mounted within a part of a plastics housing of the control unit. Where, for example the indicator is provided in an energy regulator, a mask may be provided which fits over that part of the regulator housing containing the indicator and which is provided with a window, lens or other light transmission means in a position which indicates visually which hot plate is controlled by the energy regulator concerned. Thus, for example in a cooker where four hot plates are provided in a generally square arrangement, four different masks may be used, each having a window or lens at a respective corner of the square. Alternatively, appropriate masks may be provided which are identical but are installed in different rotational orientations to give the desired different visual indications. The mask may have further much smaller, light transmitting means arranged so as to indicate the positions of the other non-controlled hot plates, for example. In a preferred embodiment the mask is mounted, for example by adhesive, to a lens moulding which is mounted to or forms part of the control unit housing. Preferably the lens moulding is translucent so as to provide improved omni-directional transmission of light through the lens so that the light may be clearly observed by a user over a wide angular range, for example as a user moves around a kitchen. Preferably the lens is formed as a projection in the upper surface of the lens moulding and the mask is adapted to fit over the projection to be located in position. Preferably the lens moulding is adapted so as to be mountable to the control unit in different rotational orientations so as to permit one moulding to be used to give a number of different visual indications. The masks may be provided directly on the control unit housing, or mounted directly or indirectly thereto for example via a lens moulding as described above. Alternatively, they may be provided in or mounted to the appliance e.g. cooker fascia. In either case, the arrangement is advantageous in that the same construction of control unit may be used for each hot plate with only the mask needing to be adapted to display which hot plate each control unit is associated with. From a second aspect, therefore, the invention provides an electrical appliance comprising a plurality of heating means, each controlled by a respective control unit in accordance with the first aspect of the invention, said appliance having mask means arranged over respective said control units, each mask means comprising means for transmitting the light produced by an indicator of a respective control unit through a selected part of the mask which indicates graphically which heating means is controlled by the control unit underlying that mask. The mask may have the preferred features as described above. Furthermore, a lens housing mounting a mask as described above may be mounted to the appliance, rather than to the control unit. The indicator may conveniently be located in a housing part which is integral with and extends to one side of a main control unit housing such that the indicator is adapted to be positioned next to a control knob for the unit in use which knob will be in front of the main housing. In a different arrangement, however, the indicator may be mounted within the rotary control member itself. In one embodiment, therefore, the control member may be in the form of a hollow spindle, with the indicator arranged at least partly within the spindle. The indicator may rotate with the spindle, but most preferably it is fixedly mounted, for example to a journal mounting the spindle. In another, preferred arrangement, the indicator is mounted on a fixed support member extending through the spindle. An operating knob is attached to the spindle in use and the light from the indicator may shine through at least a desired portion of the knob to indicate to a user that the heating load is being energised. To this end, the knob may be fully or partly translucent, for example. It may also comprise light guide means, to transmit light to the desired portion of the knob. Preferably the indicator extends beyond the open end of the hollow spindle so as to extend in use into the knob. This is advantageous, for example when using neon indicators, where light is emitted laterally rather than axially. In another arrangement, the spindle may itself be transparent or translucent to allow light to be transmitted laterally to the control knob. Locating the indicator within the spindle and behind the knob provides a particularly compact and visually attractive arrangement. The wiring for the indicator may conveniently be threaded through the base of the spindle and through at least part of its length. Preferably the indicator and its associated wiring is mounted in position on the journal, and the spindle then passed thereover. Preferably, means are provided for varying the degree of illumination of the knob to represent the setting of the control. For example it may represent the temperature set by a thermostatic control or a nominal power setting for a hot plate. This itself is a significant departure from known arrangements, and from a further aspect, therefore the invention provides an electrical control comprising a rotary control member such as a knob and means associated with the control member for varying the illumination thereof in response to its rotation. Several means of achieving this can be envisaged. For example, a mechanical element may be coupled to rotate with the control member such that in response to rotation of the control member, the mechanical element moves selectively to facilitate or prevent illumination of selected parts of the control member. An iris arrangement could be employed to increase the illuminated area of the knob as the power setting or set temperature is increased. The iris will be mechanically coupled to the knob or spindle so as to be opened or closed as the knob is turned. Alternatively a shutter may be associated with the knob such that the power setting or temperature could be indicated on the knob in the manner of a pie chart, or a clock face with individual numbers or spots of light which increase as the power setting increases. In a presently preferred arrangement, a shutter selectively transmits and blocks light to desired portions of the knob, for example a peripheral transparent or translucent ring provided in the knob. Preferably the shutter comprises a number of segments which are selectively raised and lower in response to rotation of the knob to transmit or block light. Each segment preferably is provided with a cam follower which engages with a cam ring which is fixedly mounted on the appliance. The respective cam followers are most conveniently provided at different radii of the knob, for engagement with their respective rings. A yet further arrangement would be one in which the knob is provided with an elongate stalk, the power setting being indicated by the length of the stalk which is illuminated. Two indicators may be provided to indicate different conditions. Where the invention is applied to an oven thermostat, for example, it may be desirable to provide two indicators: a first which shows whether the oven heating element is on or off, and preferably also the oven temperature setting, and a second which is illuminated while the oven is heating to temperature, but goes out when the set temperature is attained. At least one and preferably both these indicators are incorporated in the thermostatic control unit. In an arrangement as described above with a rotary spindle, both indicators may be provided in the spindle to illuminate the control knob. The indicators could be of different colours. Furthermore, the area of illumination of the oven heating indicator is preferably small compared to the temperature setting indicator. In one arrangement the oven heating indicator may illuminate a central portion of the knob, for example appearing as a relatively small central spot, while the oven temperature indicator may illuminate an area around the central spot. As in the embodiments described above an iris or shutter arrangement may be employed to indicate the set temperature. Since a relatively small area of illuminations required for the oven heating indicator, an LED may be employed rather than a neon. Preferably, however, only the oven temperature indicator is provided within the hollow spindle, and the oven heating indicator is mounted separately, for example in a housing provided to one side of the control unit. Such double indicator arrangements can be applied also to applications other than thermostats. Some preferred embodiments of this invention will now be described by way of example only, with reference to the following drawings in which: Fig. 1 shows schematically certain parts of an energy regulator in accordance with a first embodiment of the invention; Fig. 2 shows a mask suitable for use with the embodiment of Fig. 1; Fig. 3 shows a lens housing and mask for use in the invention; Fig. 4 shows, schematically, a second embodiment of an energy regulator in accordance with the invention; Fig. 5 shows, schematically, a section through a further energy regulator in accordance with the invention; Fig. 6 shows the components of Fig. 5 in an exploded view; Fig. 7 shows, schematically, part of a yet further embodiment of the invention; Fig. 8 shows a prospective view of one component of the embodiment of Fig. 7; and Fig. 9 shows a schematic section through line IX-IX of Fig. 8. Referring to Fig. 1, there is shown a bottom moulded plastics housing 1 of a control unit in the form of an energy regulator for a cooker hot plate. A microswitch assembly (not shown) is arranged between a line in tab 2, and a line out tab 3 to control the supply to the cooker hot plate in dependence upon the operating point of the microswitch set by a rotary control knob via suitable cam means as is traditional. A lid (not shown) closes the top of the bottom housing 1. A neutral line out tab 4 is mounted in the housing 1, as is a neon line member 5 extending from the line in tab 2. A neon indicator 6 and a resistor 7 are connected in series between the neon line member 5 and the neutral tab 4 by wiring 8. The neon indicator 6 is thus connected in parallel with the heating load but not through the microswitch. The neon indicator 6 and resistor 7 are mounted in a neon indicator housing part 9 which is a lateral extension of the main housing 1, the wires 8 passing through slots 10 in the dividing wall 11 between the housing 1 and the neon indicator housing part 9. A switch (not shown) is arranged between the line in tab 2 and the neon line member 5 such that when the regulator is switched off the neon indicator 6 is extinguished. In a simple construction, the line member 5 may be deflected downwardly away from a contact surface provided on the line-in tab 2 by a tooth provided on the cam of the rotary control member (shown in dotted lines) . The neon indicator 6 will not be extinguished while the regulator cycles during normal operation since it is not connected in the control circuit in parallel with the heating load through the microswitch. At least a portion of the lid over the neon housing is transparent or translucent so that the neon indicator can be observed from outside. With reference to Fig. 2, a mask 20, which may be mounted to the housing l, or to a cooker panel comprises a plate member 21 with a hole 22 allowing for the passage of a rotary spindle of a control knob. A panel 23 to one side of the hole 22 displays graphically the layout of the hot plates on the cooker. A lens 24 of say 3mm diameter is provided in the position corresponding to the position of the hot plate which is being controlled by the respective regulator, in this case the top left hot-plate. The rest of the panel 23 is opaque apart from three much smaller lens or openings 26, 27, 28. The panel 23 overlies the neon indicator housing part 9 such that when the neon indicator 6 is illuminated, light is transmitted through the lens 24 to indicate that the hot plate is on. Furthermore, light is transmitted through the lenses/openings 26, 27, 28 to show the relative positions of the other hot plates. A similar mask will be provided for the top right hand hot plate, except that the lens will be provided at position 25, and so on for the other hot plates. Rather than changing the complete mask 21 for each different hot plate, only the panel 23 thereof need be changed. The desired visual indication may be given by installing the panel 23, which could itself merely be an adhesive mask, for example, in different rotational orientations. A further embodiment of the invention is shown in Fig. 3. In this arrangement, a mask 41 is mounted to a lens housing 40 which is itself mountable to either the control unit housing or the appliance so as to overlie the indicator, by means of one or more spring tangs 42. The housing 40 is a translucent moulding and is provided with lens forming projections 43, 44, 45, 46 arranged within a recess 52 on its upper surface, bounded by a flange 47. The mask 41 which is suitably opaque has corresponding apertures 48, 49, 50, 51 sized and arranged so as to fit over the projections 43-46. The mask 41 then sits in the recess 52 and is secured therein. To this end the lower surface of the mask 41 may be adhesive coated. As in the embodiment of Fig. 2, the larger aperture will indicate the hot plate being controlled while the smaller apertures merely indicate the positions of the other hot plates. The desired visual indication for each control is obtained by mounting the lens moulding 40 on the control unit or the appliance in a desired rotational orientation. Furthermore light will be transmitted through the flange 47 to illuminate the border around the mask 41 visually to delimit the mask 41. ' Fig. 4 shows an alternative arrangement in which a neon indicator 30 is mounted within a spindle 31 rotatably mounted in the regulator housing 32. The electrical connection to the neon indicator 30 are the same as in the embodiment of Fig. 4 except that the wiring extends through the lower part of the spindle. The neon indicator 30 and its wiring may be installed in the housing 32 first, and the spindle 31 then mounted thereover as shown. A control knob (not shown) is keyed to the spindle so as to rotate therewith. The neon indicator 30 extends beyond the end of the spindle 31 so that light may be transmitted effectively to the knob. When the neon indicator 30 is illuminated, the knob will be illuminated to indicate that the hot-plate in question is on. Fig. 5 shows a section through further energy regulator in accordance with the invention, Fig. 6 showing the components in an exploded view. The energy regulator is formed with a plastics housing having an upstanding hollow pillar 40. Over the pillar 40 is arranged a hollow generally cylindrical spindle 41, integrally formed with a cam 42 for controlling the operation of the energy regulator. The spindle 41 extends out of the top of the regulator through an aperture 42. A neon indicator 44 is mounted atop a hollow insert 45, inside which runs wires 46 leading to the indicator 44 and a bias resistor 47. The wires are connected to the terminals of the energy regulator such that as the energy regulator is switched on, the neon is illuminated. The insert 44 is inserted into the hollow pillar 40 from below and is suitably secured thereto, for example by a 'click 1 fit. When assembled, as shown in Fig. 5, the neon indicator 44 extends beyond the end of the spindle 41, and is surrounded by a transparent or translucent cover 48 mounted to the top of the spindle 41. A knob 49 is also mounted to the top of the spindle 41. The knob comprises three parts, a base part 50, a light conducting part or guide 51 and a cover part 52. The base part 50 is keyed to the spindle via key means 52 and itself mounts the light guide 51. The light guide 51 is a generally conical member of a transparent or translucent material having locating spigots 54 which engage in bores 55 in the base part 50, so as to cause the light guide to rotate with the base part, and also having an upstanding rim 56 which may be polished or matt finished. It is formed with a bore 57 which as can be seen from Fig. 5, is arranged closely to the outer surface of the transparent cover 48, to receive the light emitted transversely by the neon indicator. The cover part 52 which is of an opaque material and which may for example be printed with nominal power settings around its periphery is suitably located on the upper surface of the light guide. As can be seen most clearly from Fig. 5, the rim 56 of the light guide 51 extends around the periphery of the cover part 52, such that in use, when the neon is illuminated, an illuminated ring will appear around the periphery of the cover part. Fig. 7 shows a partial sectional view through a further embodiment of the invention in which means are provided associated with the knob to vary the degree of illumination of the knob, to represent a nominal setting of the control. In this embodiment, the light guide 51 of the embodiment of Figs. 5 and 6 has been split into two concentric members, an inner guide member 60 and an outer ring 61. Arranged below the inner guide 60 is a shutter 62 which is arranged to rotate with the knob. The shutter is shown in more detail in Figs. 8 and 9. The shutter 62 is made of a resilient material, such as .2mm spring steel, and comprises a number of segments 63 separated by a number of slots 64. Each segment is provided with an upstanding peripheral rim 65. In its rest condition, the shutter assumes a domed configuration, as shown schematically as solid lines in Fig. 9, this doming being accommodated by the slots 64. When all segments are raised, the shutter assumes the configuration as shown in Fig. 8. Each segment 63 is provided with a cam follower 66, in the form of a tongue released downwardly from the segment, although a completely separate follower may be provided and mounted to the segment. The cam followers are equispaced and generally aligned with the centre of the shutter and as can be seen in Fig. 8, are formed on progressively larger pitch circles ranging from R^ to MAX in a clockwise direction. The base part 67 of the knob is formed with a series of apertures 68 through which the respective cam followers 66 extend. The cam followers 66 engage in a series of concentric, circular cam rings 69 formed on the same radii as the respective cam followers 66. The rings 69 are formed in a cam body 70 which is, in use, mounted to or provided in a fascia panel of an appliance, for example an electric cooker, and whose edge is covered by a shroud 71 of the base part 67 of the knob. Each cam ring 69 is provided with a profile having a 'high' portion 69' and a 'low' portion 69". The angular extent of the 'high' portion decreases for those rings corresponding to higher power settings. As will be described further below when the cam follower 66 engages in a "low" portion of the ring 69, the segment assumes its rest position, as shown in dotted lines in Fig. 7. This allows light to be transmitted to the adjacent portion of the outer ring 61, which will then appear illuminated. When the cam follower 66 engages a "high" portion of the cam ring, however, as shown in solid lines in Fig. 7, its segment is deflected upwards to cause the rim 65 thereof to move into the space between the inner guide 60 and outer ring 61, so cutting off the light to the adjacent portion of the outer ring 61 which then appears dark. The number of segments 63 corresponds to the number of nominal power settings of the control, in thus embodiment six. In the 'off condition of the control, the shutter 62 has all its segments 63 deflected upwardly so that none of the outer ring 61 is illuminated. As the knob is turned to its first setting, the radially outermost cam follower moves from a 'high' to a 'low' portion of its corresponding cam ring 69, to allow that segment 63 of the shutter 62 to drop to illuminate the adjacent portion of the outer ring 61 of the knob. Thus say 60° of the knob periphery will be illuminated, representing a power setting of •1'. As the knob is turned further, the radially next outermost cam follower moves to a 'low' portion of its cam ring 69 to cause its segment 63 to drop also to illuminate a further 60° of the know periphery, to represent a power setting of '2' while the first section of the outer ring 61 also remains illuminated. This continues until all the cam followers are in 'low' portions of their corresponding cam rings 69, when the shutter will have all its segments lowered so as to illuminate the whole knob periphery. The respective cam rings 69 thus have, starting from the radially innermost, progressively longer 'low' portions, and shorter 'high' portions whereby the associated portions of the outer ring 61 of the knob will remain illuminated over a greater proportion of the rotation of the knob. The particular angular extent of the respective 'high' and 'low' portions of each cam ring 69 can be chosen so that a desired angular rotation of the knob corresponds to a maximum power setting of the control, to illuminate the complete outer ring 61. The cover part 72 of the knob may have the power settings printed adjacent the respective portions of the outer ring 61, if a numerical, as well as a graphical illustration of the power setting is required. The outer ring 61 may be continuous, or to move clearly delimit adjacent areas, may be formed as a number of transparent or translucent segments separated by opaque regions.

Claims: Claims 1. A control unit for an electrical heating means, comprising a rotary control member and an indicator, for indicating visually the state of said heating means in use, the indicator being incorporated in the control unit. 2. A control unit as claimed in claim 1 wherein said indicator is a neon indicator. 3. A control unit as claimed in claim 1 or 2 wherein said control unit is an energy regulator for a multi-hot plate cooking apparatus. 4. A control unit as claimed in claim 3 wherein said indicator is mounted within a part of a plastics housing of the control unit. 5. A control unit as claimed in claim 4 wherein a mask is provided which fits over that part of the regulator housing containing the indicator and which is provided with a window, lens or other light transmission means in a position which indicates visually which hot plate is controlled by the energy regulator. 6. A control unit as claimed in claim 5 wherein the mask comprises further much smaller, light transmitting means arranged so as to indicate the positions of the other non-controlled hot plates. 7. A control unit as claimed in claim 5 or 6 wherein the mask is mounted to a lens moulding which is mounted to or forms part of the control unit housing. 8. A control unit as claimed in claim 7 wherein the lens is translucent. 9. A control unit as claimed in any of claims 5 to 8 wherein the lens is formed as a projection in the upper surface of a lens moulding and the mask is adapted to fit over the projection to be located in position. 10. A control unit as claimed in claim 9 wherein the lens moulding is adapted so as to be mountable to the control unit in different rotational orientations so as to permit one moulding to be used to give a number of different visual indications. 11. A control unit as claimed in any of claims 4 to 10 wherein the indicator is located in a housing part which is integral with and extends to one side of a main control unit housing such that the indicator is adapted to be positioned next to a control knob for the unit in use which knob will be in front of the main housing. 12. A control unit as claimed in any of claims 1 to 3 wherein the indicator is mounted within or on the rotary control member itself. 13. A control unit as claimed in claim 12 wherein the control member comprises a hollow spindle, with the indicator arranged at least partly within the spindle. 14. A control unit as claimed in claim 13 wherein the indicator is mounted on a fixed support member extending through the spindle. 15. A control unit as claimed in claim 13 or 14 wherein the indicator extends beyond the open end of the hollow spindle. 16. A control unit as claimed in claim 13, 14 or 15 wherein a knob is mounted to said spindle. 17. A control unit as claimed in claim 16 wherein said knob contains light guide means. 18. A control unit as claimed in claim 16 or 17 wherein means are provided for varying the degree of illumination associated with the knob to represent the setting of the control. 19. An electrical control comprising a rotary control member such as a knob and means associated with the control member for varying the illumination thereof in response to its rotation, to represent the setting of the control. 20. A control or control unit as claimed in claim 18 or 19 comprising an iris arranged within the knob or control member. 21. A control or control unit as claimed in claim 18 or 19 comprising a shutter selectively for illuminating different portions of the knob. 22. A control or control unit as claimed in claim 21 wherein a peripheral portion of the knob is illuminated. 23. A control or control unit as claimed in claim 21 or 22 wherein said shutter comprises a number of resilient segments selectively raised and lowered in response to rotation of the knob or control member. 24. An electrical appliance comprising a control or control unit as claimed in claim 23 and cam means for selectively deflecting said shutter segments. 25. An appliance as claimed in claim 24 wherein said cam means comprises a plurality of concentric cam rings. 26. A control unit as claimed in claim 18 or 19 wherein the degree of illumination of a stalk of the knob is varied. 27. A control unit as claimed in any preceding claim wherein two indicators are provided. 28. A control unit as claimed in claim 27 wherein both indicators are provided within the knob. 29. A control unit as claimed in claim 28 wherein a first indicator illuminates a central portion of the knob and a second indicator illuminates a region of the knob therearound. 30. An electrical appliance comprising a control or control unit as claimed in any of claims 1 to 28 or 26 to 29. 31. An electrical appliance comprising a plurality of heating means, each controlled by a respective control unit as claimed in claim 1 or 2, said appliance having mask means arranged over respective said control units, each mask means comprising means for transmitting the light produced by an indicator of a respective control unit through a selected part of the mask which indicates graphically which heating means is controlled by the control unit underlying that mask. 32. A mask for use in a control unit or electrical appliance as claimed in any of claims 5 to 31.

Inventors: TAYLOR JOHN CRAWSHAW, TAYLOR, JOHN, CRAWSHAW
Applicants: STRIX LTD, TAYLOR JOHN C, STRIX LIMITED
Application year: 1993
Main classification: H01H19
IPC codes: H01H9, H01H19, H01H21