GB2309766A

GB2309766A - Shape memory activation of steam vents

Info

Publication number: GB2309766A
Application number: GB9602172A
Authority: GB
Inventors: Crenner Lup Hin Kwok
Original assignee: Sunderland Holdings Ltd
Current assignee: Sunderland Holdings Ltd
Priority date: 1996-02-02
Filing date: 1996-02-02
Publication date: 1997-08-06
Anticipated expiration: 2016-02-02
Also published as: GB9602172D0; GB2309766B

Abstract

A steam vent arrangement for a cooking utensil includes an aperture 10 in a lid 11 of the utensil. The aperture is closed off by a circular plate 12 that in use is rotated by an activator 19 when the boiling point of contents of the utensil is approached to allow steam to vent to atmosphere. The activator 19 is in the form of a coiled element formed of shape memory material. Alternatively, a shape memory element (26, figure 5) may push a cylinder (23) upwards so that an aperture (22) therein is exposed to atmosphere to vent the cooking utensil. An indicator may be provided to indicate the degree of opening of the vent.

Description

STEAM VENTS FOR COOKWARE The invention relates to steam vents for cookware.

It is already known to provide adjustable steam vents which are conveniently mounted on a top lid of a cooking utensil.

The effective size of a vent or aperture is controlled by partially closing off the aperture using a movable plate.

The plate is manually adjustable relative to the aperture and remains in a chosen position so that the aperture is open or closed off as required. The vent is open or closed when cooking commences, and manually adjusted if necessary as cooking proceeds requiring close supervision and attendance by the user.

It is an object of the invention to at least reduce or overcome this problem.

According to the invention there is provided a steam vent arrangement for a closable cooking utensil comprising an aperture in a lid of the utensil, a flap mounted to the lid which is arranged to move progressively to uncover the aperture to increase its effective size, and an activator formed of shape memory material which is mounted adjacent the flap and arranged to move the flap to open the vent incrementally over a chosen range of temperatures close to the boiling point of contents inside the utensil.

The aperture may have a generally oblong cross-section extending lengthwise along a radial arc of a central axis and the flap formed by a circular plate mounted for rotation about the central axis having a cut-away sector that sweeps over the aperture when the plate rotates to expose the aperture to atmosphere outside the utensil.

The activator may be in the form of a coiled element mounted in an opposing cut-away sector of the plate and arranged to press on one end of the opposing section when it expands to rotate the plate.

A conventional resilient spring may be mounted in tandem with the activator and arranged to bias the plate in an opposite direction to its direction of movement caused by expansion of the activator.

The steam vent arrangement may be mounted in a central handle of a lid of the cooking utensil.

Steam vent arrangements for cooking utensils according to the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional side view of one steam vent arrangement with the vent in a closed position; Figure 2 is a plan view of the steam vent arrangement of Figure 1 with a lid handle part removed; Figure 3 is a cross section view of the one steam vent arrangement with the vent, in an open position; Figure 4 is a plan view of Figure 3 with the handle part removed; and Figure 5, 6 and 7 are each different cross-sectional views of another steam vent arrangement.

Referring to the drawings, in Figures 1 and 2 the vent arrangement comprises an aperture 10 formed in a lid 11 of a cooking utensil (not shown?. A flap for the aperture consists of a circular plate 12 formed with a relatively small cut-away sector 13 and a larger opposing cut-away sector 14. The plate 12 has an upstanding tongue 15 that slides in a groove 16 formed in a lid handle part 17. The plate 12 is slidable between the lid 11 and the handle part 17 and rotatable about a central axis of a stud 18 that holds the handle part 17 to the lid 11.

The aperture 10 has an oblong cross-section that extends lengthwise along a radial arc of the central axis of the stud 18. The plate 12 can rotate clockwise from the position shown in Figure 2, to allow the aperture 10 to be progressively more exposed by the sector 13 to allow steam to escape from inside the utensil to atmospheric. The steam is directed sideways (see Figure 3) so as not to be directed directly on to a user's hand when he picks up the lid by the handle part 17.

An activator 19 for the vent consists of a coiled element formed of shape memory material mounted in one half of the sector 14. When the activator 19 lengthens, it pushes between one end of the sector and a fixed post 20 mounted to the handle part 17. As a result, the plate 12 is rotated clockwise. A conventional coil spring element 21 is also mounted in the sector 14, effectively in tandem with the activator 19, which biasses the plate in an anticlockwise direction.

In practice, the aperture will be normally fully closed when cooking first commences. Water vapour and steam will be released within the utensil as the temperature of the contents warm up and generally approach boiling point. The activator 19 is set in this example to remain unaffected by rising temperatures until its own temperature reaches approximately 60 C. Thereafter, the activator expands to a maximum length when its temperature reaches 750C. This temperature range, which can be changed somewhat for different utensils or as required, correspond to a range of temperatures close to the boiling points of contents inside the utensil. Thus, the aperture 10 is automatically and incremental exposed to atmosphere as boiling point is approached and the aperture fully exposed when required as shown in Figures 3 and 4. When the temperature falls, the activator 19 will contract and the spring 21 rotates the plate anti-clockwise to close off the aperture 10. If the spring 21 is not present, the user can if necessary manually rotate the plate 12 to close off the aperture.

Thus, the activator 19 serves to automatically control venting of the utensil as required. The use of a memory effect material, which have significant non-linear expansion characteristics when compared to temperature changes, enables the aperture 10 to remain fully closed until required only when and as boiling point approaches.

The automation of venting clearly means such control no longer requires supervision or manual operation at appropriate times. However, in practice the automatic control also serves to provide better cooking conditions.

This is believed due to the aperture 10 remaining fully closed off during warm up of the utensil contents and to the opening and as well as the degree of opening of the aperture 10 being carefully matched to ideal conditions by the activator. In practice for example, a steady escape flow of steam can be maintained, in somewhat otherwise fluctuating circumstances if necessary, totally automatically by steam vent arrangements of the present invention.

The plate 12 may be arranged with markings or colouring that are visible or made visible by providing a viewing panel in the handle part 17. Such markings are indicators for the user to observe and show that the aperture is fully closed, partly closed, fully open and so on.

In Figures 5, 6 and 7, the steam vent arrangement is shown in three respective conditions corresponding to temperature of the contents being below 900C, and at or near 900C, and at or near 1000C respectively.

An aperture 22, which corresponds to the aperture 10 is Figure 1, is formed at the top of a hollow cylinder 23 slidable in a chamber 24. Normally, at temperatures below about 1000C, the aperture 22 is not exposed to atmosphere.

The aperture 22 is only, as seen in Figure 7, exposed when the aperture 22 is above the end of the cylinder 23. In that position the inside of the cooking utensil is exposed via the aperture 22 to atmosphere. In other respects, the operation of this vent arrangement is the same as described with reference to Figures 1 to 4.

The chamber 24 is fitted to a lid 25 of a utensil. An activator 26 comprises a shape memory element that is exposed to water vapour and steam that rises up from inside the cooking utensil and passes through holes 27 during use.

At temperatures above 90cm, the activator 26 expands and pushes the cylinder 23 upwards, see Figures 6 and 7. At the top of the cylinder 23 there are three different coloured bands 29, 30 and 31, which are used to indicate that the aperture 22 is opening or is open fully open to atmosphere as appropriate.

Claims

1. A steam vent arrangement for a closable cooking utensil comprising an aperture in a lid of the utensil, a flap mounted to the lid which is arranged to move progressively to uncover the aperture to increase its effective size, and an activator formed of shape memory material which is mounted adjacent the flap and arranged to move the flap to open the vent incrementally over a chosen range of temperatures close to the boiling point of contents inside the utensil.

2. A steam vent arrangement according to claim 1, in which the aperture has a generally oblong cross-section extending lengthwise along on radial arc of a central axis and the flap formed by a circular plate mounted for rotation about the central axis having a cut-away sector that sweeps over the aperture when the plate rotates to expose the aperture to atmosphere outside the utensil.

3. A steam vent arrangement according to claim 2, in which the activator is in the form of a coiled element mounted in an opposing cut-away sector of the plate and is arranged to press on one end of the opposing section when it expands to rotate the plate.

4. A steam vent arrangement according to any one of the claims 1 to 3, which is mounted in a central handle of a lid of a cooking utensil,

5. Steam vent arrangements substantially as hereinbefore described with reference to the accompanying drawings.

4. A steam vent arrangement according to claim 3, including a conventional resilient spring mounted in tandem with the activator and arranged to bias the plate in an opposite direction to its direction of movement caused by expansion of the activator.

5. A steam vent arrangement according to any one of the claims 1 to 4, which is mounted in a central handle of a lid of a cooking utensil.

6. Steam vent arrangements substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows 1. A steam vent arrangement for a closable cooking utensil comprising an aperture in a lid of the utensil; a flap mounted to the lid which is arranged to move progressively to uncover the aperture to increase its effective size, and an activator formed of shape memory material which is mounted adjacent the flap and arranged to move the flap to open the vent incrementally over a chosen range of temperatures close to the boiling point of contents inside the utensil, in which the aperture has a generally oblong cross-section extending lengthwise along on radial arc of a central axis and the flap formed by a circular plate mounted for rotation about the central axis having a cut-away sector that sweeps over the aperture when the plate rotates to expose the aperture to atmosphere outside the utensil.

2. A steam vent arrangement according to claim 1, in which the activator is in the form of a coiled element mounted in an opposing cut-away sector of the plate and is arranged to press on one end of the opposing section when it expands to rotate the plate, 3. A steam vent arrangement according to claim 2, including a conventional resilient spring mounted in tandem with the activator and arranged to bias the plate in an opposite direction to its direction of movement caused by expansion of the activator.