AU586108B2 - Vapour vent - Google Patents

Description

"VAPOUR VENT"

Field of Invention

This invention relates to vapour vents for loose lidded vessels such as saucepans and other cooking vessels. Background to Invention

Amongst the perceived shortcomings of saucepans and other loose-lidded cooking vessels, the problems of lid rattling and fluid spluttering (on contents boiling) are most commonly reported, and various measures have been used in the past to offer solutions.

The problems are related and are caused by- steam building up pressure within the vessel which is momentarily released by the lid lifting. A continuing cyclic build up and release of the pressure causes lid rattling. Fluid spluttering is also caused by the cyclic release of pressure where the steam, venting to atmosphere, carries with it accumulated condensate from the rim of the vessel.

The problem is presently met by providing a vent in the lid which is manually opened to selectively control release of steam in place of the cyclic process described above. A permanently open vent would not offer satisfactory vapour containment in the context of current cooking practice.

The main disadvantage of the present manual operation of a steam vent is that the manual task is typically only undertaken after the event, viz the onset of lid rattling and fluid spluttering, in which case the vent is being operated in a hot cooking environment and some fluid (condensate) will have been sprayed about the cooking area. Summary of the Invention

It is an object of the invention to at least reduce the incidence of lid rattling and fluid splattering during use of loose-lidded cooking vessels.

In a first aspect, the invention provides a vapour vent for a loose-lidded vessel such as a saucepan, comprising a body, a tubular valve member slidable in the body, and means responsive to a parameter of a region about or adjacent said body to move said tubular valve member from a first position in which its interior is closed off from said region to a second position in which the interior of the tubular member is open to said region to receive and thereby vent vapour from the region.

Preferably, the tubular member protrudes visibly above a surface portion of said body in said second, open, position but retracts below or flush with said surface portion in said first, closed, position. The responsive means is advantageously responsive to the temperature of the said region, for example to a temperature in the range 70° to 90°C.

In a second aspect, the invention affords in a vessel with a loose lid, a vapour vent comprising valve means and means responsive to a parameter of the interior of the vessel to alter said valve means from a closed condition to a condition in which said valve means is open to vent vapour from the interior of the vessel.

The vapour vent of a vessel according to the second aspect of the invention preferably comprises a vapour vent according to the first aspect. Brief Description of the Drawings The invention will he further described, by way of example only, wi li reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a saucepan incorporating a steam vent according to the invention; Figure 2 is an axial cross-section of the steam vent, shown in the closed position;

Figure 3 is a view similar to Figure 2 but showing the vent in the open position;

Figure 4 is a perspective view of the steam vent, shown separated from the saucepan; and

Figures 5A and 5B are respectively a side elevation of the socket booty forming part of the steam vent, and a cross-section on the line 5B-5B in Figure 5A. Description of Best Modes for Carrying out the Invention

In the illustrated eτnbo_ϊiιmeτι , the steam vent 10 is mounted in an off-centre location in the lid 8 of a loose-lidded cooking vessel in the form of a saucepan 9. Lid 8 is not fastened to the saucepan 9 and simply rests in a complementary peripheral seat 9a on the upper edge of the saucepan. The lid is thus loose and susceptible to being lifted by steam pressure within the saucepan.

Lid 8 includes a central knob 12 for grasping and lifting the lid. The vent 10 is positioned in an aperture 14 in the lid.

Steam vent 10 includes a socket body 16, a cap 18, a slidably mounted open-ended tubular piston 20 and a pair of springs 45, 47. Cap 18 includes a depending annular skirt 19 which is displaced inwardly to define inner and outer shoulders 26a, 26b on the cap and is externally threaded for engaging a complementary internal thread on a cylindrical main part 17 of socket body 16. The assembly is secured to the saucepan lid 8 by projecting skirt.19 through aperture 14 and engaging socket body 16 to clamp the rim of the aperture between outer cap shoulder 26b and the annular end of the socket body.

Socket body 16 further includes a pair of integral depending legs 30, 31 which have curved outer faces 30a, 31a contiguous with the outer face of the cylindrical main part 17 of the socket body. Legs 30, 31 are bridged by an end plate comprising a disc 32 which defines the lowermost extremity of the vent assembly.

Tubular piston 20 has an intermediate external annular rib 34 providing an underneath shoulder 36 and an upper stepped shoulder 38.

The piston is slidable in an aperture 40 in cap 18 between a lower limit (Figure 2) determined by engagement of the lower end of the piston with disc 32, at which limit the chamfered upper end 21 of the piston is flush with the outer face of cap 18, and an upper limit (Figure 3) in which shoulder 38 approaches or engages the inner shoulder 26a of the cap. The bearing interfaces for this sliding motion are provided by the aperture 40 in cap 18 and by peripheral sliding engagement between rib 34 and the inner cylindrical face of skirt 19.

Piston 20 is biased to its lower limit by a helical spring 45 disposed within skirt 19 and acting between shoulders 26a and 38 as shown. At this lower limit, the interior of piston 20 is closed off from the interior of the saucepan adjacent the vent. A helical second spring 47 of SMA (i.e. shape memory alloy) material is disposed about the piston, acting between disc 32 and shoulder 36. This spring is a tin coated copper/zinc/aluminium alloy selected so that the spring will expand at about 80°C to overcome the force of spring 45 and raise the piston to its upper limit (Figure 3). Steam within the saucepan is then able to flow between the coils of spring 47 and be received by the interior 21 of tubular piston 20 and thereby be vented to the exterior of the saucepan. The piston 20 is now protruding above the end-surface of cap 18 and the outer surface of the lid to provide a visible indication to the cook that this temperature has been reached and that he/she should lower the heat imparted by the stove flame or hotplate under the saucepan. It is found that if the vent is opened at about 80°C, the steam level in the saucepan will not yet be high enough to cause the aforedescribed lid rattling and consequent fluid spluttering, yet the temperature is then sufficiently high for venting without adversely affecting the heating or cooking process. It will be noted that spring 47 is exposed to the interior of the saucepan and is therefore directly sensitive to the temperature of a region adjacent socket body 16 within the saucepan. Spring 47 is further selected so that when the saucepan is removed from the stove and the temperature of its interior drops below about 70°C, the spring force of spring 47 will become less than that of spring 45, which will therefore lower piston 20 and close the vent. A temperature of 70°C is thought to be a satisfactory serving temperature and thus the falling of the piston from its raised position provides a visible sign to the cook that the contents of the saucepan are ready to serve. In an alternative embodiment (not illustrated), the steam vent may take the form of a pivoted flap. An SMA spring, or other thermally sensitive actuator such as a bi-metallic spring or wax element, may be arranged to operate the flap by lifting it to release steam. The protruding flap provides a visible indication as before that the vent is open: in any embodiment this indication may be audible, e.g. by way of a click or vapour whistle. The steam vent may alternatively be incorporated into the lifting handle of the vessel or lid. The handle may then include suitable steam channels and openings to communicate the temperature of the vessel interior to the thermally sensitive actuator. It will be understood that the temperature at which vent operation occurs may be regulated in the case of the SMA spring by selection of the alloy composition of metal employed. The differential between the opening and closing temperature for the vent, which differential arises from hysteresis in the SMA spring, may in turn be controlled by selection of the return biasing spring. This enables optimum choice of the vent opening and closing temperatures.

Claims

1. A vapour vent for a loose-lidded vessel such as a saucepan, comprising a body, a tubular valve member slidable in the body, and means responsive to a parameter of a region about or adjacent said body to move said tubular valve member from a first position in which its interior is closed off from said region to a second position in which the interior of the tubular member is open to said region to receive and thereby vent vapour from the region.

2. A vapour vent according to claim 1 wherein the tubular member protrudes visibly above a surface portion of said body in said second, open, position but retracts below or flush with said surface portion in said first, closed, position.

3. A vapour vent according to claim 1 or 2 wherein said responsive means is responsive to the temperature of said region.

4. A vapour vent according to claim 3 wherein said responsive means is a SMA spring disposed about the tubular member.

5. A vapour vent according to claim 4 including a further spring biasing the tubular member to its first position.

6. A vapour vent according to any preceding claim, wherein the temperature at which said responsive means moves said tubular member is in the range 70° to 90°C.

7. A vapour vent according to any one of claims 3 to 6 wherein said responsive means is arranged such that said tubular member returns to its first position at a temperature lower than that which caused it to move to its second position.

8. A vapour vent according to any preceding claim wherein said body comprises a main part of generally cylindrical configuration and an end plate bridged to the main part by leg means extending longitudinally with respect to the main part, said tubular member abutting the end plate in its first position.

9. A vapour vent according to claim 8 wherein said tubular member is open-ended at both ends.

10. A vapour vent according to any preceding claim wherein said body further includes means for securing the vent within an aperture in a vessel lid such that said region is under the lid.

11. A loose lid for a vessel such as a saucepan including means for grasping and lifting the lid, an aperture spaced from said grasping and lifting means, and, secured in said aperture, a vapour vent according to any preceding claim.

12. A loose-lidden vessel including an aperture spaced for said grasping and lifting means, and, secured in said aperture, a vapour vent according to any one of claims 1 to 10.

13. In a vessel with a loose lid, a vapour vent comprising valve means and means responsive to a parameter of the interior of the vessel to alter said valve means from a closed condition to a condition in which said valve means is open to vent vapour from the interior of the vessel.

14. A vessel according to claim 13 wherein said valve means includes an indication visible at the exterior of the vessel that it is in its open condition.

15. A vessel according to claim 13 or 14 wherein said vapour vent comprises a body secured in an aperture in the vessel or lid and said valve means comprises a tubular valve member slidable in said body, said responsive means being adapted to respond to said parameter by moving the tubular valve member from a first position in which its interior is closed off from the interior of the vessel to a second position in which the interior of the tubular member is open to the interior of the vessel to receive and thereby vent vapour from the vessel.

16. A vessel according to claim 15 wherein the tubular member protrudes visibly above a surface portion of the vessel in said open position but retracts below or flush with said surface position in its closed position.

17. A vessel according to claim 15 or 16 where said responsive means is responsive to the temperature of the interior of the vessel.

18. A vessel according to claim 17 wherein said responsive means is arranged such that said tubular member returns to its first position at a temperature lower than that which caused it to move to its second position.

19. A vessel according to any one of claims 1 to 17, wherein said body comprises a main part of generally cylindrical configuration and an end plate bridged to the main part by leg means extending longitudinally with respect to the main part, said tubular member abutting the end plate in its first position.

20. A vessel according to claim 19, wherein said tubular member is open-ended at both ends.

21. A vessel according to any one of claims 13 to 20, wherein said vessel is a saucepan or other cooking vessel.