EP0858672B1

EP0858672B1 - Electrically powered water heating appliances

Info

Publication number: EP0858672B1
Application number: EP96935159A
Authority: EP
Inventors: Robert Andrew O'neill; Ian Geoffrey White; Stephen Roger Brook; Nigel Harby; Antonio Martin Gaeta; Kevin Edwin John; Robert Henry Hadfield
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 1995-11-03
Filing date: 1996-11-04
Publication date: 2000-07-26
Anticipated expiration: 2016-11-04
Also published as: GB9522594D0; WO1997016842A1; HK1014615A1; GB2306801B; AU7323496A; NZ320495A; EP0858672A1; AU728528B2; CN1205799A; CN1114221C; DE69609518T2; DE69609518D1; GB2306801A

Description

Field of the Invention:

This invention concerns to cordless electrically powered water heating appliances. Examples of the kind of water heating appliances to which the present invention is applied are electric kettles and hot water jugs, urns, pans, laboratory equipment etc., and in the following the invention will be described with particular reference to electric kettles and hot water jugs though it is to be understood that the invention is not limited to such an application.

Background of the Invention:

Controls for electrically powered water heating appliances such as kettles and hot water jugs are well known which operate to switch off the appliance in the event of an overtemperature condition arising at the heating element of the appliance, for example because of the appliance having been switched on empty or being allowed to boil dry; such controls are commonly referred to as element protection controls. Other controls are well known which operate to switch off the appliance (or at least substantially reduce the supply of power to the appliance heating element) when water being heated in the appliance comes to the boil; such controls commonly operate by sensing the generation of steam in the appliance and are commonly referred to as steam sensor controls. Both element protection controls and steam sensor controls generally incorporate their own thermal sensors, commonly a bimetallic element, and element protection controls are known which include some form of secondary or back-up protection arranged to operate in the event, however unlikely, of failure of the primary control.

An exemplary element protection control is described in GB-A-2 194 099 with reference to Figs. 3A, 3B and 3C thereof and a modified form of such control is described in GB-A-2 248 724. An exemplary steam sensor control is described in GB-A-2 212 664 with reference particularly to Figs. 3A to 3M thereof.

In GB-A- 2 283 155 there is described a single sensor combined element protection and steam sensor control which makes use of a modified form of the element protection control of GB-A-2 194 099 (See Fig. 2 of GB-A-2 283 155) in combination with an enclosure as originally proposed in GB-A-1 143 834, the element protection control being disposed at a specific location on the dry side of a generally planar heating element located in the bottom of a water heating vessel and the enclosure being located on the wet side of the element opposite to the location of the element protection control. The enclosure has openings so that it fills with water when the vessel is filled, and is arranged so that when water boils in the vessel the steam that is generated expels the water from the enclosure thus giving rise to a local element overtemperature condition sensible by the element protection control. By virtue of this arrangement the two functions of element overtemperature protection and steam sensing can be performed by means of a single control.

Whilst electric kettles and other water heating appliances have conventionally been corded, that is to say arranged to be connected to an electric socket outlet by means of an electric cord (or cable) terminated with appropriate plug-and-socket type terminations, in recent years so-called cordless appliances have been popular in which power is supplied to the appliance proper via a base unit coupled to the electrical supply, the appliance proper and the base unit having complementary electrical connector parts adapted to provide appropriate electrical connections through the base unit to the heating element in the appliance proper when the latter is seated on the base. In GB-A-2 241 390 and GB-A-2 236 220 there are described exemplary connection systems for cordless electrical appliances, and in WO 94/06185 there is described a particularly advantageous connection system for cordless appliances which avoids the requirement arising with the systems of GB-A-2 241 390 and GB-A-2 236 220 that the appliance proper has to be particularly orientated relative to the base before the connector parts can be engaged with each other. The connection system of WO 94/06185 provides for mating interconnection of the appliance proper with its base throughout a full 360°, or almost a full 360°, of relative rotation of the two connector parts.

Disclosed in WO 94/06185 with reference to Figs. 7 to 11 thereof is a connection system for a cordless electrical appliance in which a plug part of the connection system, shown in Fig. 8B, is integrally formed with an element protection control in accordance with the teachings of GB-A-2 194 099. The problem with such an arrangement, however, is that it suffers from a lack of flexibility, the integration of the element protection control with the connector plug part limiting the ability of the appliance designer to design appliances with freedom and furthermore imposing severe tolerance constraints upon the manufacturers of such appliances.

Objects and Summary of the Invention:

The present invention has as its object the solution or at least substantial reduction of the aforementioned problem arising with integrated element protection controls and cordless connection systems.

According to the present invention, in one of its aspects, a combined element protection control and cordless connection system for a water heating appliance or the like is provided in which the element protection control and the appliance connector part of the cordless connection system are formed as separate items having electrical connector parts adapted to couple together, the electrical connector parts preferably being such as to enable effective interconnection of the two items within a range of relative positions thereof.

In an exemplary embodiment of the present invention as thus defined, the socket part of a cordless connection system according to the teachings of WO 94/06185, forming the base of the preamble of claim 1, and an element protection control according to the teachings of GB-A-2 194 099 are provided with interconnectable electrical connector parts adapted to be plugged together, a pair of spade terminals (plugs) being provided on one of the two and accommodating receptacles (sockets) being provided on the other. The receptacles (sockets) preferably incorporate spring terminals designed to enable satisfactory electrical interconnection to be established even when the connector socket part and the element protection control are somewhat out of proper alignment with each other or otherwise somewhat improperly positioned relative to each other, for example as the result of tolerances arising in the manufacture of the accompanying appliance.

Described hereinafter in detail are variants of the abovementioned embodiment which provide for the mounting of the element protection control on top of the socket part of the cordless connection system or side-by-side with the socket part, such variants accommodating different appliance designs and providing the appliance designer with increased flexibility. The electrical connector parts that are provided on the socket part of the cordless connection system and/or on the element protection control may be such as to enable the respective items to be used selectively in one or other of the on top and side-by-side variants.

The present invention extends to an electrically powered water heating appliance incorporating a cordless connection system and an element protection control according to the teachings hereof. The invention is particularly, though not exclusively, applicable to water heating appliances wherein the electrical heating element of the appliance is of the planar type, for example as is described in GB-A-2 283 155.

The above and further features of the present invention are set forth with particularity in the appended claims and will become clear from consideration of the following detailed description of exemplary embodiments which are illustrated in the accompanying drawings.

Description of the Drawings:

Figure 1 is a perspective view of an element protection control generally in accordance with the teachings of GB-A-2 194 099 and GB-A-2 248 724 and specially configured for the present invention;

Figure 2 is a perspective view of one part of a cordless connection system generally in accordance with the teachings of WO 94/06185 and specially configured for the present invention;

Figure 3 is a perspective view showing the element protection control of Figure 1 connected to the top of the connection system part of Figure 2;

Figure 4 is a plan view of the combined element protection control and connection system part of Figure 3;

Figure 5 is an underplan view of the Figure 3 combination;

Figure 6 is a part sectional side elevation view showing how the element protection control of Figure 1 and the connector system part of Figure 2 are adapted to be interconnected;

Figure 7 is an enlarged showing of part of Figure 6;

Figure 8 is a perspective view of a modified form of the element protection control of Figure 1;

Figure 9 is a perspective view of a modified form of the connection system part of Figure 2;

Figure 10 is a perspective view showing the element protection control of Figure 8 connected to the connector system part of Figure 9 in a side-by-side configuration;

Figure 11 is a plan view of the combined element protection control and connector system part of Figure 10;

Figure 12 is an underplan view of the Figure 10 combination;

Figure 13 is a part sectional side elevation view showing how the element protection control of Figure 8 and the connector system part of Figure 9 are adapted to be interconnected;

Figure 14 is an enlarged showing of part of Figure 13;

Figures 15 and 16 are views similar to Figures 2 and 6 showing a modified form of the embodiment of Figures 1 to 7; and

Figures 17 and 18 are views similar to Figures 9 and 13 showing a modified form of the embodiment of Figures 8 to 14.

Detailed Description of the Embodiments:

Referring first to Figures 1 to 7 of the accompanying drawings, these illustrate a first embodiment of the present invention. An element protection control 1 (Figure 1) is a modified form of the control that is described in GB-A-2 194 099 with reference to Figures 3A, 3B and 3C thereof, or a modified form of the control that is described in GB-A-2 248 724, or a modified form of the controls that are described in GB-A-2 283 155 and GB-A-2 283 156. Reference should be had to the referenced specifications for a full understanding of all aspects and advantages of the subject control which will be described only briefly in the following.

The element protector control 1 provides for the supply of electric current through the control to the heating element of an electrically powered water heating vessel or the like to which the control is affixed, subject to the condition of a bimetallic blade 2 of the control. The bimetallic blade 2 is held in close thermal contact with the heating element and in response to an element overtemperature condition is arranged to open a set of switching contacts within the control thereby to interrupt the supply of electric current through the control. The bimetallic blade 2 is snap-acting in its operation and acts upon a push-rod to open the switching contacts. A secondary level of protection is afforded by mounting the bimetallic blade 2 on a carrier 3 which is formed of a plastics material having a predetermined melting temperature, the carrier being under spring pressure in use of the control and being arranged so that in the event, however unlikely, of the bimetallic blade 1 failing to operate so that the heating element temperature continues to rise the carrier will being to soften and will deform under its spring pressure so enabling a set of spring contacts to open within the control. Further details of the general construction and operation of the control 1 will become clear from consideration of the above-referenced specifications.

Figure 2 shows the socket or appliance connector inlet part 4 of a plug-and-socket type cordless connection system substantially as described in WO 94/06185 with reference to Figures 7 to 11 thereof. More particularly, the appliance connector inlet part 4 is similar in its construction to the part 130 shown in Figure 8B of the drawings of WO 94/06185 and is adapted to be mated with a complementary plug or appliance connector part substantially as shown in Figure 9, the appliance connector and appliance connector inlet parts being configured to enable relative rotation between the two parts throughout a full 360° of rotation. The appliance connector inlet part 4 comprises a generally cylindrical cup-shaped member 5 formed of moulded plastics material and having a central pillar 6 formed with a central opening 7 (see Figure 5). An earth or ground terminal 8 is provided centrally of the opening 7, a neutral terminal 9 is provided in the side wall of the opening 7 and a live terminal 10 is provided on the outside wall of the pillar 6. As shown in Figure 2 which shows the cup-shaped appliance connector inlet part 4 in inverted position, the earth, neutral and

live terminals

8, 9 and 10 are connected to respective spade or

tab terminals

11, 12 and 13, the neutral and

live tab terminals

12 and 13 extending upwardly from the part 4.

The element protector control 1 of Figure 1 is adapted and arranged to be plugged onto the appliance connector inlet part 4 of Figure 2 in the manner shown in Figure 3 and in more detail in Figures 6 and 7. As can be seen most clearly in Figures 6 and 7, the element protector control 1 is formed with a pair of recesses 15 in each of which there is provided a looped spring metal part 16. An opening 17 is provided in the bottom of each recess 15 for admitting thereto a respective one of the neutral and

live terminals

12, 13 of the appliance connector inlet part 4 when the control 1 and the appliance connector inlet part 4 are juxtaposed as shown in Figure 3, and with the

terminals

12, 13 thus received in the recesses electrical connection is made between the

terminals

12,13 and the looped spring metal parts 16 which bear against the terminals with a substantial force. By virtue of these connections, electric current is enabled to flow from the connector part 4 through the

tab terminals

12,13 and the spring metal parts 16 into the control.

The form of the spring metal parts 16, the size of the recess 15 and of the openings 17, and the relative size of the

terminal parts

12 and 13 are such as to enable the element protector control 1 and the appliance connector inlet part 4 to be successfully mated with each other throughout a range of relative positions and relative orientations of the two parts. As mentioned hereinbefore, this is advantageous in that it enables the inevitable manufacturing tolerances that arise with water heating vessels and the like to be accommodated with ease. With the mated appliance connector inlet part 4 and element protector control 1 affixed to the heating element of a water heating vessel, for example, the appliance connector inlet part 4 is able to be mated with an appliance connector part as shown in Figure 8A of WO 94/06185.

Referring now to Figures 8 to 14 of the accompanying drawings, shown therein is an alternative embodiment of the present invention which is the same as the above-described embodiment except that the appliance connector inlet part and the element protection control are adapted to be interconnected in side-by-side relationship thus providing a lower overall height than the "on top" first embodiment. The same reference numerals are used in Figures 8 to 14 as are used to designate like parts and functionally similar parts in the first embodiment, and it will be seen that in Figure 9 the neutral and

live terminals

12 and 13 extend horizontally, whereas they extend vertically in Figure 2, and in Figures 13 and 14 that the

terminals

12 and 13 of the appliance connector inlet part 4 access the springs 16 of the element protection control 1 via openings 17 in the side of the control rather than underneath the control as in Figures 6 and 7. In all other respects the embodiment of Figures 8 to 14 is the same as the embodiment of Figures 1 to 7.

Referring now to Figures 15 and 16 and Figures 17 and 18 these show respectively modifications of the first and second embodiments described in the foregoing and again the same reference numerals are used in Figures 15 to 18 as were used to designate like parts in Figures 1 to 14. A comparison of Figures 15 and 16 with Figures 2 and 6 will show that the modifications comprise the use of push-fit terminal members for defining the neutral and

live terminals

12 and 13, the push-fit terminal members being separate components which push-fit onto neutral and live spade or tab terminal parts, similar to the earth terminal 11, which are provided on the appliance connector inlet part 4, and the use of a differently shaped spring 16 within the element protection control 1. In the modified embodiment of Figures 17 and 18, differently shaped push-fit terminal members are provided on the neutral and live tab terminals. The basic appliance connector inlet part 4 is the same in Figure 15 as in Figure 17 and the use of differently shaped push-fit terminal members enables "on top" and "side-by-side" configurations to be accommodated using the same element protection control 1 and the same basic appliance connector inlet part 4.

It will be seen from the foregoing explanations that the described arrangements accommodate relative movements between the appliance connector inlet part and the element protection control, such movements being achieved by sliding contact between the tab terminals of the appliance connector inlet part and the springs of the element protection control and/or by flexing of one or both of the tabs and the springs. The two necessary interconnections, neutral and live, can move independently to provide any necessary angular movement. The earth terminal tab of the appliance connector inlet part may be attached to the appliance by means of a flexible lead or directly to the appliance, as by riveting for example, and electrical connections between the element protection control and the heating element may be made with flexible leads coupled to the tab terminals 20 of the control 1 by means of quick connect receptacles or, with the control appropriately modified as described in GB-A-2 285 156 for example, by means of spring connections. Connections to a steam control may be similarly made.

Having thus described the present invention by reference to particular embodiments, it is to be well appreciated that modifications and variations thereto are possible without departure from the scope of the present invention as set forth in the appended claims.

Claims

A cordless electrically powered water heating appliance comprising an appliance proper provided with a heating element for heating water in the appliance proper, a base unit for supplying electricity to the heating element in the appliance proper when the appliance proper is seated on the base unit, there being complementary electrical connector parts (4) on the appliance proper and on the base unit which are adapted to engage with each other when the appliance proper is seated on the base, and an element protection control (1) in the appliance proper which is adapted to switch off the power supply to the heating element in response to a heating element overtemperature condition, characterized in that the element protection control (1) and the connector part (4) on the appliance proper are formed as separate items having electrical connector parts (16; 12, 13) adapted to be directly coupled together.
The appliance of claim 1 wherein said electrical connector parts (16; 12, 13) comprise male terminal parts (12, 13) on one of said items and female terminal parts (16) on the other.
The appliance of claim 2 wherein tab terminals (12, 13) on one of said items are adapted to be received in terminal recesses (15) in the other.
The appliance of claim 3 wherein terminal springs (16) are provided in said recesses.
The appliance of any preceding claim wherein said electrical connector parts (16; 12, 13) are such as to enable effective interconnection of the two items within a range of relative positions thereof.
The appliance of any preceding claim wherein said element protection control (1) comprises a bimetal (2) mounted in or on a thermally collapsible carrier (3) and the action of the bimetal (2) is arranged to provide a primary control function and the thermally-induced collapse of the carrier (3) is arranged to provide a secondary or back-up control function.
The appliance of any preceding claim wherein the connector part (4) on the appliance proper is adapted for engagement with a complementary base connector part enabling engagement of the two connector parts substantially irrespective of the relative rotational orientation thereof in the plane transverse to the engagement direction of the parts.
The appliance of claim 7 wherein said appliance connector part (4) and said base connector part are generally coaxially arranged.
The appliance of any preceding claim wherein said electric heating element comprises a generally planar heating element having said element protection control (1) and said connector part (4) on the appliance proper affixed to one side thereof.