Note: Descriptions are shown in the official language in which they were submitted.
- = . =
CA 022363~1 1998-04-30
W O 97/16842 PCT/G B96/02690
- IMPR~v~M~NlS RELATING TO ELECTRICALLY POWERED
WATER HE~ING APPLIANCES AND CONTROLS TXEREFO~
Field of the Invention:
~his invention concerns improvements relating to
electrically powered water heating appliances and the
like and to controls therefor. Examples of the kind
of water heating appliances to which the present
invention may be 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.
Backqround 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 common~y
referred to as element protection controls. Other
controls are well known which operate to switch off
the appliance (or at least substantially reduce the
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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 ~ailure 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 o~ a modified form of the
element protection control of GB-A-2 194 099 (See Fig.
2 o~ GB-A-2 283 155) in combination with an enclosure
as originally proposed in GB-A-l 143 834, the element
protection control being disposed at a specific
location on the dry side of a generally planar heating
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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 ~ills 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
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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 W0 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 W0
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 W0 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
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manufacturers o~ such appliances.
Obiects and Summarv 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 o~
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 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
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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
manu~acture o~ 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
~lexibility. 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 also extends to an
electrically powered water heating appliance
incorporating a cordless connection system and an
element protection control according to the teachings
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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
10 exemplary embodiments which are illustrated in the
accompanying drawings.
Description of the Drawinqs:
Figure 1 is a perspective view of an element
protection control generally in accordance with the
15 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 W0 94/06185 and specially
20 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
25 protection control and connection system part of
Figure 3;
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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 l;
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
1 0 ;
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
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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 Descri~tion 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 l) 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
lS 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 ~ull 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
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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 o~ 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-
re~erenced 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 W0
94/06185 with reference to Figures 7 to 11 thereof.
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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 W0 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
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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 ~or 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
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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 l 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 W0 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 o~ 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
-
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14
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 o~
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
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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
lS 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
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are possible without departure from the spirit and
scope of the present invention as set forth in the
appended claims. For example, the present invention
is not limited to the herein described kind of element
protection control and is not limited to the herein
described kind of cordless connection system.
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