GB2189938A - Steam-operated switch of liquid heating vessel - Google Patents

Abstract

A liquid heating vessel includes one or more steam vents (13) directing steam to a thermally responsive metal coil operating a switch for the heating means. The plural vents discourage water blockage of the vents by their member and/or by chamfered edges (c). The vessel is of the "jug" type and has a handle located on the side of a plastics body of the vessel. The thermally responsive metal coil is loosely mounted on a pillar and at about 100 DEG C the coil is fully extended to rotate a switch operating finger piece to an "off" position. At low temperatures, the coil is contracted and rests on the forked end of arm (14), which arm is pivotable. <IMAGE>

Description

SPECIFICATION Liquid heating vessel This invention relates to a vessel for heating liquids, the vessel being of a type having a hollow body, an electrical heater, and control means, wherein the hollow body is adapted to contain a liquid to be heated and has a wall upstanding from a bottom of said body; wherein the heater comprises an electrical resistance heating element disposed alongside said bottom; wherein the control means comprises steam responsive means, a switch assembly electrically connected to said element, and a cover; and wherein fastener means secures said heater and switch assembly to said body; and in which the cover comprises a housing secured to or integral with said wall, and a separable closure member releasably secured to the housing so that the housing and closure member define at least part of a main chamber; the steam responsive means comprising a thermally responsive device and a mechanism, which mechanism is arranged to actuate said switch assembly when actuated by the thermally responsive device when the iatter is subjected to steam entering the main chamber from the hollow body (hereinafter referred to as a heating vessel 'of the type specified').

Vessels of the type specified are disclosed in our co-pending G.B, Fatent Application No.

2102205A. These vessels show a thermally responsive element in the form of a bimetal strip which is fixed to a closure member and the thermally responsive element is disposed adjacent to a single steam vent. In vessels of this type it is often necessary to replace the thermally responsive element and, since time is all important to the cost of repair, parts which are the most likely to malfunction and in particular the thermally responsive element should be readily accessible. The vessels shown in our aforementioned application tend to be disadvantageous in that the accessability to and removal of the thermally responsive element, and replacement by a new thermally responsive element tend to require more time, skill and cost than is absolutely necessary and additionally requires the use of tools to remove and replace the element.

It is also known to mount a thermally responsive element in the form of a coil on said mechanism arranged to actuate said switch assembly but the coil and mechanism are carried by the closure member. Moreover, although the coil is loosely mounted it is retained on the mechanism when the closure member is removed from the vessel. In order to replace the coil it is then necessary to dismantle at least part of the mechanism in order to remove the coil and replace it with a new one. The disassembly and reassembly of the mechanism to replace the coil may be more time consuming and require more skill and dexterity than might be immediately apparent and may also require accurate aligning of parts on a 'hit and miss' trial and error basis. Additionally, replacement of the coil by dismantling of the mechanism runs the risk that individual parts may be lost or even broken.

A further problem which arises in vessels of the type specified, and indeed in liquid heating vessels in general which are provided with a steam vent leading to a thermally responsive device, is that of the steam vent becoming blocked by a liquid film or globule, thus obstructing the steam from passing through the vent. When the steam vent is blocked in this manner the thermally responsive device is shielded from the steam and therefore fails to respond to the true temperature of liquid heated in the vessel. This can lead to the thermally responsive device failing to actuate the switch assembly via said mechanism to the 'off' position when the liquid has reached boiling point. Therefore, the liquid continues to boil causing wastage of energy and other obvious inconvenience and disadvantages.Such blovckages can last for considerable periods of time and can occur fairly regularly.

It is an object of the present invention to alleviate at least one of the aforementioned disadvantages.

According to one aspect of the present invention there is provided a vessel of the type specified in which the thermally responsive device is loosely mounted or loosely located on a support member in the main chamber, the support member being formed separately from, and being non-removable with, the closure member and the thermally responsive device being co-operable with an arm of said mechanism to actuate said switch assembly.

By the present invention the thermally responsive device is mounted or located without the use of fastening means, for example rivets or screws. Advantageously, for simplicity of design, the support member may be integrally formed with the housing.

Preferably, guide means is provided on the support member to guide the arm into correct location with the thermally responsive means as the closure member is assembled onto the remainder of the vessel.

Conveniently, the closure member may extend over the support member and thermally responsive device and the closure member may snap-engage with steam vent means adjacent to the support member and thermally responsive device; disengagement of the closure member clearly exposes the thermally responsive device and support member and the device is adapted to be removed from the vessel by lifting the device off the support.

In one embodiment, the support member comprises a pillar extending upwardly from the housing (which housing may define an opening to accommodate fingers of a users hand and therefore part of a handle of the vessel) over which the thermally responsive element in the form of a metal coil is located, said pillar being straddled by a forked end of the arm which lies underneath the coil, said arm being pivotally mounted on the closure member.

Preferably, the pillar has a lower or base portion on which the coil rests and where guide means is provided as aforesaid said base portion may have guide means which cooperates with the forked end of the arm.

Advantageously, a stop may be provided at the bottom of the pillar, for example on the portion of said housing defining an upper wall of said opening, said stop limiting rotation of the arm and also of a fingerpiece connected to said arm to define an 'off' position for the fingerpiece.

According to a second aspect of the present invention there is provided a liquid heating vessel provided with steam vent means leading to a thermally responsive device in a chamber, and having a mechanism co-operable with the thermally responsive device to interrupt the supply of electricity to an electrical heater for heating liquid in the vessel, the steam vent means being adapted to restrain or prevent liquid films or blockages of said vent means so that the thermally responsive means is not screened from the true temperature of liquid in the vessel when the liquid is boiling, said adaption comprising providing a plurality of vent holes and/or shaping one or more sides of the or each vent hole to resist the formation of a liquid blockage.

The vent hole or holes may be circular, elliptical, generally rectangular or any convenient shape and may be suitably dimensioned to engage snap engagement means on a closure member, which closure member is releasably secured to a housing which at least partly defines said chamber.

One or more sides of the or each vent hole may be chamfered and said chamfered side or sides face the chamber. Preferably, the chamfer angle is 45" + 5 .

An embodiment of a liquid heating vessel in accordance with the present invention will now be described, by way of example only, with reference to the accompanying simplified schematic drawings in which; FIGURE 1 shows a fragmentary vertical sectional view of the upper portion of a hollow handle of the embodiment with the switch assembly actuating mechanism in the 'off' position; FIGURE 2 shows a smaller fragmentary view similar to FIGURE 1 showing in particular the appearance of a thermally responsive device with the mechanism in the 'on' position; FIGURE 3 is a fragmentary plan view showing the thermally responsive device, and FIGURE 4 is a fragmentary view taken generally on line IV-IV but of a modified embodiment of the vessel.

FIGURE 1 shows part of a liquid heating vessel generally designated 1 which is a vessel of the type specified and also of the 'jug' type having a handle 2 located at the side of a hollow moulded plastics body 3 of the vessel.

The electrical heater, switch assembly and portion of the switch assembly actuating mechanism not shown in FIGURE 1 are all as shown and described in relation to FIGURE 4 of our aforementioned co-pending patent application and therefore will not be further described here.

The hollow body 3 has a wall 4 upstanding from a bottom (not shown) of the body 3, which wall 4 is integrally formed with a rearward extension piece or housing 5. The extension piece 5 together with a separable closure member 6 releasably secured thereto constitutes a cover in the form of handle 2. The extension piece 5 defines an opening 7 to accommodate the fingers of a users hand and the handle also defines a main steam chamber 8.

A thermally responsive device in the form of a generally cylindrical metal coil 9 is loosely mounted or loosely located on a generally tubular pillar 10 integral with the extension piece 5. FIGURE 1 shows the coil 9 in an expanded or high temperature state i.e. when the temperature in the chamber 8 is at about 100"C; FIGURE 2 shows the coil 9 in an unexpanded or low temperature state i.e. when the temperature in the chamber is at about 24"C.

Referring to FIGURES 1 to 3, the pillar 10 extends vertically upwardly from the wall 11 of the extension piece 5 which defines the upper wall of opening 7 and the coil 9 is mounted axially on the pillar. The pillar 10 has a generally cylindrical portion 10a and the outer diameter of portion 10a is slightly smaller than the inner diameter of the coil 9 so that the coil is freely movable axially on portion 10a. The pillar 10 extends upwardly as far as an inner top 12 of closure member 6, the inner top having a bead 1 2a which snapengages under the upper wall 13a of a generally rectangular centrally located steam vent 13, The bottom edge of vent 13 is chamfered at 45Q and said bottom edge faces chamber 8. The chamfered edge helps to prevent the vent 13 from becoming blocked by a globule of water.

The pillar 10 has a larger diameter partcircular base portion 10b on which the coil 9 rests; the part-circular base portion 10b defines opposed straight edges 10c, 10d and the forked end 14a of arm 14 straddles the base portion 10b as shown in FIGURE 3. Arm 14 is part of the mechanism 15 mounted on the closure member 6 which is arranged to actuate the switch assembly (not shown) when actuated by the coil 9 when the latter is subjected to steam entering chamber 8 through vent 13 from the hollow body 3.

As shown the coil 9 also rests on the forked end 1 4a disposed thereunder when the finger piece 16 is in the 'off' position as shown in FIGURE 1. In an alternative embodiment (not shown) the arm 14 does not engage the thermally responsive means when the finger piece 16 is in the 'off' position but is merely disposed below it. The finger piece 16 is pivotally mounted at X in known manner on closure member 6 and the mechanism 15 is known except for the arm 14. Advantageously, the wall 11 also acts as a stop for the forked end 1 4a so that the finger piece can be correctly located in the 'off' position.

When the closure member 6 is disengaged from the remainder of the vessel 1 the arm moves out from underneath the coil 9 leaving the coil solely supported by the pillar 10 resting on base portion 10b. The coil 9 is clearly accessible, readily visible and can be removed merely by lifting it upwardly axially beyond the pillar. It is a simple matter to remove the coil 9 and replace it with a new one.

When the closure member 6 is re-engaged on the vessel the forked end 14a is automatically guided into position underneath the coil 9 by the straight edges 10c, 10d acting as guide edges. Any alternative co-operative guide configuration of the pillar 10 or other support and arm 14 may be employed.

FIGURE 2 shows the position of the forked end 14a of arm 14 when the fingerpiece 16 has been moved to the 'on' position and the coil is in an unexpanded state. When the fingerpiece 16 is first moved to the 'on' position mechanism 15 actuates the switch assembly (not shown) in known manner to supply electric current to the electric heater (not shown) to heat liquid in the hollow body 3. Steam eventually issues through vent 13 and the coil expands axially and rotates the arm 14 downwardly about pivot axis X until spring S of mechanism 15 is forced over centre to switch 'off' the switch assembly and interrupt the supply of electricity to the heater; the forked end 14a then abuts wall 11 preventing further rotation of arm 14 or of fingerpiece 16 in the same rotational sense and the fingerpiece 16 is in the 'off' position.The fingerpiece is set to the 'on' or 'off' position simply by moving the fingerpiece with a thumb of one hand.

As shown in FIGURES 1 to 3 one vent hole 13 is provided but the vessel may be modified as shown in FIGURE 4.

FIGURE 4 shows two generally rectangular vent holes 13' and 13" which replace the single vent 13. The provision of a plurality of vent holes reduces the risk of the coil being screened from the steam in the vessel by a water blockage because even though one vent hole may possibly become blocked by a water globule the risk of two holes becoming blocked (or indeed more holes if provided) is far less.

Additionally, the vertical and lower sides are chamfered at 45" and the chamfered sides C1-C6 face the steam chamber 8. The form of the edges also helps to prevent the vent holes 13' and 13" from becoming blocked.

The upper edge of each of the vent holes 13', 13" is left square to allow for the advantageous snap-engagement of bead formations (shown in dotted lines in FIGURE 4) on the inner top, which formations are similar to bead 1 2a shown in FIGURE 1. The chamfer angle is preferably 45" + 5 but may vary as appropriate.

The snap-engagement of the closure member 6 with a vent or vent holes is considered advantageous since the closure member 6 may be removed quickly and represents an improvement which is particularly convenient where a support and thermally responsive means located loosely thereon is provided adjacent to the snap-engagement. Such an arrangement allows the closure member to be removed more quickly to expose the thermally responsive element than if individual fasteners such as screws have to first be removed.

Additionally, the support for the thermally responsive means need not necessarily extend from a horizontal wall of the housing. For example, referring to FIGURE 1, the support in the form of pillar 10 could extend from wall 4 above wall 11 and be angled upwardly if necessary to support the thermally responsive means.

The scope of the first aspect of the present invention may possibly extend to the provision of a thermally responsive device being loosely mounted or loosely located on a support anywhere in the steam chamber even if the device is actually removable with the seperable closure member.

However, in such a case clear access to the device without having to dismantle said mechanism to any extent is required.

It is to be understood that the choice of particular terminology used herein to describe features and function should not be construed as unnecessarily limiting and that the scope of such features and function includes suitable or obvious generic replacements.

Claims (6)

1. A vessel of the type specified in which the thermally responsive device is loosely mounted or loosely located on a support member in the main chamber, the support member being formed separately from, and being non-removable with, the closure member and the thermally responsive device being co-operable with an arm of said mechanism to actuate said switch assembly.

2. A vessel as claimed in Claim 1 in which the support member is integrally formed with the housing.

3. A vessel as claimed in Claim 1 or Claim 2 in which guide means is provided on the support member to guide the arm into correct location with the therm ally responsive device as the closure member is assembled onto the remainder of the vessel.

4. A vessel as claimed in any one of the preceding claims in which the closure member extends over the support member and thermally responsive device.

5. A vessel as claimed in Claim 4 in which the closure mem ber snapengages with steam vent means adjacent to the support member and thermally responsive device.

6. A vessel as claimed in Claim 1 in which the steam vent means is substantially as described and illustrated with reference to Figures 1 to 3 or substantially as modified in accordance with Figure 4, of the accompanying drawings.

(c) Claims 10-13 above have been re-numbered as 1-4 and their appendancies corrected.

(d) Claim 14 above has been renumbered as 5.

6. A vessel as claimed in any one of the preceding claims in which the support member comprises a pillar extending upwardly from the housing over which the thermally responsive device in the form of a metal coil is located, said pillar being straddled by a forked end of the arm which lies underneath the coil, said arm being pivotally mounted on the closure member.

7. A vessel as claimed in Claim 6 in which the pillar has a lower or base portion on which the coil rests with the forked end straddling the lower or base portion.

8. A vessel as claimed in Claim 7 when dependent from Claim 3 in w hich the lower or base portion has the guide means which co-operate with the forked end of the arm.

9. A vessel as claimed in any one of Claims 6 to 8 in which a stop is provided at the bottom of the pillar, said stop limiting rotation of the arm and also of a fingerpiece connected to said arm to define an "off" position for the fingerpiece.

10. A liquid heating vessel provided with steam vent means leading to a thermally responsive device in a chamber, and having a mechanism cooperable with the therm ally responsive device to interrupt the supply of electricity to an electrical heater for heating liquid in the vessel, the steam vent means being adapted to restrain or prevent liquid films or blockages of said vent means so that the thermally responsive means is not screened from the true temperature of liquid in the vessel when the liquid is boiling, said adaption comprising providing a- plurality of vent holes and/or shaping one or more sides of the or each vent hole to resist the formation of a liquid film or blockage.

11. A vessel as claim ed in Claim 10 in which the vent hole or holes is/are circular, ellipticai or generally rectangular.

12. A vessel as claimed in Claim 10 or 11 in which the vent hole or holes is/are dimensioned to engage snap engagement means on a closure member, which closure member is releasably secured to a housing which at least partly defines said chamber.

13. A vessel as claimed in any one of Claims 10 to 12 in which one or more sides of the or each vent hole is/are chamfered and said chamfered side or sides face the chamfer.

14. A vessel as claimed in Claim 13 in which the chamfer angle is 45" + 5 .

15. A vessel as claimed in Claim 1 in which the handle is substantially as described and illustrated with reference to FIGURES 1 to 3, or substantially as modified in accordance with FIGURE 4, of the accompanying drawings.

16. A vessel as claimed in Claim 10 in which the steam vent means is substantially as herein described and illustrated with reference to FIGURE 4 of the accompanying drawings.

CLAIMS Amendments to the claims have been filed, and have the following effect: (a) Claims 1-9, 15, 16 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: