EP4145049A1

EP4145049A1 - Oven door and method of cleaning the same

Info

Publication number: EP4145049A1
Application number: EP21195307.0A
Authority: EP
Inventors: Mert KAHYAOGLU; Merve KAHYAOGLU
Original assignee: Vestel Elektronik Sanayi ve Ticaret AS
Current assignee: Vestel Elektronik Sanayi ve Ticaret AS
Priority date: 2021-09-07
Filing date: 2021-09-07
Publication date: 2023-03-08

Abstract

The present invention relates to an oven door (10), which has a window allowing a user to view the contents of an oven during cooking, wherein the window has a two-layer design, comprising a first window element (12), and a second window element (14) which is arranged substantially parallel to and spaced apart from the first window element (12), forming a cavity (16) therebetween. The cavity (16), which contains air, improves the thermal insulation of the window, but the window is liable to become dirty with trapped food particles, spilt cooking liquids and the like, which are accidentally introduced into the cavity (16) via air vents (18a, 18b). In order to solve this problem, the invention provides the oven door (10) with a cleaning member (22) which is movable within the cavity (16) and in contact with the surfaces of the first and second window elements (12, 14) that are inside the cavity (16), to wipe these surfaces clean. The cleaning member (22) is mechanically coupled to a driving mechanism (20), which comprises a substance which expands on heating by the oven and contracts back to its original size on cooling back down. Thus whenever the oven is used for cooking, the substance expands, and the driving mechanism (20) provides a motive force to the cleaning member (22) which is derived from the expansion of the substance. The surfaces of the first and second window elements (12, 14) within the cavity are therefore cleaned by the movement of the cleaning member (22). The invention also provides an oven comprising an oven door having such a cleaning mechanism, and a corresponding method of cleaning an oven door. The invention has the advantage that it requires no source of electrical power, such as a motor, and is caused to operate by the heat of the oven alone.

Description

The present invention relates to an oven door according to claim 1, an oven comprising the same, and a method of cleaning an oven door according to claim 11.

Background of the Invention

Modern domestic ovens usually have a door comprising a window to allow a user to view the contents of the oven during cooking. Such a window is typically made of toughened and heat-resistant glass. On the other hand, in order to reduce the escape of heat from within the oven through the window to the surrounding environment, which would otherwise lower the energy efficiency of the oven and would also present a dangerously hot surface on the exterior of the window to a user, the window usually comprises a first window element, and a second window element arranged substantially parallel to and spaced apart from the first window element, which together provide a cavity between the first and second window elements, in the manner shown in Fig. 1.
In Fig. 1, an example of an oven door 10 comprises a first window element 12, a second window element 14, and a cavity 16 therebetween. In Fig. 1, the thickness of the oven door 10 has been exaggerated for improved clarity. The cavity 16 between the first and second window elements 12, 14 contains air, which, because of its relatively lower thermal conductivity, provides a layer of thermal insulation, thereby reducing the conduction of heat from within the oven through the window to the surrounding environment, improving the energy efficiency of the oven, and presenting an exterior surface to a user of the oven which is at a lower, safer temperature. To prevent the air within the cavity from heating up during cooking, which would otherwise reduce the thermal efficiency and effectiveness of the cavity, the cavity is provided with air vents 18a, 18b along its top and bottom edges. Thus fresh, cooler air can be drawn into the cavity 16 from the environment during cooking via the air vents 18a along the bottom edge of the cavity 16, and by natural convection, warmer air is expelled via the air vents 18b along the top edge of the cavity 16.
However, this two-layer design of oven-door window has a problem, in that the cavity between the first and second window elements often becomes dirty as a result of food particles, cooking liquids and the like entering the cavity via the air vents 18b along the top edge of the cavity 16. Vapour laden with volatile compounds from within the oven may also condense on the surfaces of the first and second window elements which face each other within the cavity, in other words on an outer surface of the interior window element which faces the exterior of the oven and on an inner surface of the exterior window element which faces the interior of the oven. These surfaces therefore need regular cleaning.
A solution to this problem which already exists within the art is to provide the oven door with a user-operable disassembly mechanism, whereby a user may remove at least one of the substantially parallel first and second window elements for cleaning, and/or may gain access to the other of the first and second window elements for cleaning. However, users typically find performing this regular cleaning operation to be time-consuming, difficult and inconvenient, so tend to neglect it. There is therefore a need in the art for an alternative, solution, which does not require regular user intervention, in order to clean the surfaces of window elements within the cavity of a two-layer design of oven-door window.
Other background art may be found in patent publication no. US 2013/0055516 A . This document describes a glass surface cleaning device, operable by heat from the Sun to clean windows on the exterior of a building.

Object of the Invention

It is therefore an object of the invention to provide an improved oven door, an oven comprising the same, and a method of cleaning an oven door.

Description of the Invention

The object of the invention is solved by an oven door according to claim 1. The oven door at least comprises a first window element, and a second window element substantially parallel to and spaced apart from the first window element, providing a cavity between the first and second window elements. The first and second window elements each comprise at least a respective inner surface for facing an interior of an oven and, substantially parallel thereto, a respective outer surface for facing an exterior of the oven. The oven door further comprises a cleaning member movable within said cavity and a driving mechanism. The cleaning member contacts at least one of the outer surface of one of the first and second window elements and the inner surface of the other of the first and second window elements when it moves. The driving mechanism at least comprising a substance which expands on heating by the oven and contracts back to its original size on cooling back down, wherein the driving mechanism is mechanically coupled to the cleaning member and provides a motive force derived from expansion of the substance on heating which moves the cleaning member in a range of movement across said at least one of the outer surface of one of the first and second window elements and the inner surface of the other of the first and second window elements in a wiping action.
This solution is beneficial because when the oven door is heated by the oven during cooking, the substance which expands on heating is caused to expand. This provides a motive force which moves the cleaning member in a range of movement across at least one of the window-element surfaces in the cavity in a wiping action, thereby cleaning it. Moreover, once the oven is switched off and cools back down again, since the same substance contracts back to its original size on cooling back down, the cleaning member can return to its original starting position, ready for another such cleaning operation. Thus there is no need for any user intervention to clean the surfaces of window elements within the cavity of a two-layer design of oven-door window because every time the oven is used for cooking, the surfaces of the window elements within the cavity are cleaned automatically. Preferably, for economy of design and manufacture, both the outer surface of the interior window element and the inner surface of the exterior window element are cleaned by the same action of the same cleaning member. However, the same result may be achieved by separate but similar cleaning members conducting similar cleaning operations on each such surface individually. In such a case, the separate but similar cleaning members may be driven by separate but similar respective driving mechanisms or by a single, combined driving mechanism. The invention has the advantage that it needs no source of electrical power, such as a motor, and operates from the heat of the oven alone.
Advantageous embodiments of the invention may be configured according to any claim and/or part of the following description.
In some embodiments, the range of movement of the cleaning member is at least as great as a linear dimension of one of the first and second window elements. If so, the movement of the cleaning member will have the beneficial effect of cleaning the whole of the window element.
In some embodiments, the cleaning member may have an elongate shape extending across the first and second window elements in a first direction, and movement of the cleaning member across said surfaces when the substance expands on heating is in a second direction substantially perpendicular to the first direction. This solution is beneficial because in such cases, if the wiping action of the cleaning member is from one side edge of the first and second window elements to an opposite side edge of the first and second window elements or from bottom to top or from top to bottom of the first and second window elements, the movement of the cleaning member can clean the whole of the respective window elements in a single linear movement.
In some embodiments, the driving mechanism may be arranged parallel to an edge of the oven door and may be invisible through an exterior one of the first and second window elements. This solution is beneficial because if so, the view of a user through the oven-door window into the oven will not be at least partially obstructed by the driving mechanism.
In some embodiments, the driving mechanism may at least comprise two components arranged in parallel to each other along opposing side edges of the oven door, with the cleaning member extending therebetween. This solution is beneficial because if the driving mechanism and cleaning member are thus arranged, the motive force required to operate the cleaning member, as provided by the substance which expands on heating, is divided in two, so that each of the two components of the driving mechanism only has to provide half the total motive force to the cleaning member. This places less strain on each of the two components of the driving mechanism, in comparison to a single, unified driving mechanism.
In some embodiments, the cleaning member may at least comprise a removable and replaceable cleaning pad and/or blade. This solution is beneficial because it allows the cleaning pad and/or blade to be occasionally removed and replaced by a user, in order to clean it of accumulated dirt, and/or to be substituted with a new one, either by the user or by a service engineer.
In some embodiments, the cleaning member rises upwards when the substance expands on heating and sinks downwards when the substance contracts on cooling back down. Such a solution has the advantage that when the substance contracts, the weight of the cleaning member at least partially contributes to the motion of the cleaning member when returning to its original starting position.
In some embodiments, the driving mechanism may at least comprise a device which multiplies by a factor of greater than 1 a range of movement of the substance which expands on heating into the range of movement of the cleaning member. For example, the device which multiplies by a factor of greater than 1 may be a gear and/or lever mechanism. This solution is beneficial because it allows a smaller range of movement of the substance which expands on heating to be amplified into a larger range of movement of the cleaning member.
The substance which expands on heating may comprise any combination of a solid, such as a metal or an alloy, and/or a fluid, such as a liquid and/or a gas. However, in some embodiments, the driving mechanism may at least comprise a piston cylinder and the substance which expands on heating may comprise a fluid contained within said cylinder. In such a case, the fluid contained within said cylinder is preferably inert on heating at temperatures up to about 300 degrees Celsius and safe on contact with food. This solution is beneficial because unlike a solid, which may experience work hardening and/or fatigue as a result of repeated cycles of thermal expansion and contraction, a fluid may be subjected to repeated cycles of thermal expansion and contraction without suffering such effects.
The present invention also relates to an oven comprising an oven door as described herein.
The present invention further relates to a method of cleaning an oven door, wherein the oven door at least comprises a first window element and a second window element substantially parallel to and spaced apart from the first window element, providing a cavity therebetween, wherein the first and second window elements each comprise at least a respective inner surface for facing an interior of an oven and, substantially parallel thereto, a respective outer surface for facing an exterior of the oven. The method at least comprises: providing the oven door with a cleaning member movable within said cavity, wherein the cleaning member contacts at least one of the outer surface of one of the first and second window elements and the inner surface of the other of the first and second window elements when it moves; providing the oven door with a driving mechanism at least comprising a substance which expands on heating by the oven and contracts back to its original size on cooling back down; mechanically coupling the driving mechanism to the cleaning member to provide a motive force derived from expansion of the substance on heating which moves the cleaning member across said at least one of the outer surface of one of the first and second window elements and the inner surface of the other of the first and second window elements in a wiping action; attaching the oven door to an oven; and heating the substance which expands on heating from heat within the oven to move the cleaning member.
Such a method of cleaning an oven door has the advantage that it allows the surfaces of window elements within the cavity of a two-layer design of oven-door window to be cleaned automatically every time the oven is used for cooking and without any user intervention.
In some embodiments, wherein the cleaning member at least comprises a removable and replaceable cleaning pad and/or blade, the method may further comprise, when the oven is at ambient temperature, removing and replacing the cleaning pad and/or blade. This solution is beneficial because the cleaning pad and/or blade may thus be cleaned of accumulated dirt by occasional user intervention.
In such a case, the method may further comprise, when the oven is at ambient temperature, removing at least one of the first and second window elements before removing and replacing the cleaning pad and/or blade, and then replacing the same at least one of the first and second window elements after replacing the cleaning pad and/or blade. In other words, the oven door may comprise a user-operable disassembly mechanism, whereby a user may remove at least one of the substantially parallel first and second window elements for cleaning, and/or may gain access to the cleaning pad and/or blade by doing so.
If the method comprises removing and replacing the cleaning pad and/or blade when the oven is at ambient temperature, the method may further comprise washing the cleaning pad and/or blade between removing and replacing the cleaning pad and/or blade.
In some embodiments, the method may also comprise replenishing the substance which expands on heating when the oven is at ambient temperature. This solution is beneficial because if the substance which expands on heating comprises a fluid contained within a piston cylinder, if the fluid slowly depressurizes as a result of gradual leakage of the fluid, the cylinder may then be repressurized. Alternatively or additionally, if the substance which expands on heating comprises a solid, if the solid is subject to work hardening and/or fatigue as a result of repeated cycles of thermal expansion and contraction, the solid may be replaced.
Further features, goals and advantages of the present invention will now be described in association with the accompanying drawings, in which exemplary components of the invention are illustrated. Components of the devices and methods according to the invention which are at least essentially equivalent to each other with respect to their function can be marked by the same reference numerals, wherein such components do not have to be marked or described in all of the drawings.
In the following description, the invention is described by way of example only with respect to the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is a schematic diagram showing an isometric view of an oven door comprising a two-layer design of window;
Fig. 2 is a schematic diagram showing an isometric view of an embodiment of an oven door;
Fig. 3A is a schematic diagram showing the same isometric view of the embodiment of an oven door as in Fig. 2;
Fig. 3B is a schematic diagram again showing the same isometric view of the embodiment of an oven door as in Fig. 2;
Fig. 4 is a schematic diagram showing an isometric view of an embodiment of a driving mechanism;
Fig. 5 is a schematic diagram showing an isometric view of an embodiment of a device which multiplies a range of movement of the substance which expands on heating;
Fig. 6 is a schematic diagram showing an isometric view of an embodiment of an oven;
Fig. 7 is a flow diagram representing an embodiment of a method of cleaning an oven door; and
Fig. 8 is a flow diagram representing another embodiment of a method of cleaning an oven door.

Detailed Description

Fig. 2 shows a first embodiment of an oven door 10. In Fig. 2, the thickness of the oven door 10 has been exaggerated for improved clarity. Like the oven door 10 shown in Fig. 1, the oven door 10 of Fig. 2 comprises a first window element 12, a second window element 14, and a cavity 16 therebetween, which contains air. In addition, however, the oven door 10 of Fig. 2 comprises a driving mechanism 20 and a cleaning member 22. The driving mechanism 20 comprises two components 20a, 20b, which are arranged in parallel to each other alongside opposing side edges 101, 102 of the oven door 10. The cleaning member 22 extends between the two components 20a, 20b of the driving mechanism 20. The two components 20a, 20b are arranged parallel to each respective edge 101, 102 of the oven door 10 such that they are invisible through an exterior one 14 of the first and second window elements 12, 14. The cleaning member 22, which is movable within the cavity 16, comprises a pair of removable and replaceable cleaning blades 24a, 24b. One of these two cleaning blades 24a contacts the outer surface 12b (see Fig. 3A) of an interior one 12 of the first and second window elements 12, 14, and the other of these two cleaning blades 24b contacts the inner surface 14a (see Fig. 3B) of the exterior one 14 of the first and second window elements 12, 14. Whereas in the embodiment shown in Fig. 2, the cleaning member 22 comprises two such cleaning blades 24a, 24b, in other possible embodiments, the cleaning member 22 may instead comprise a single cleaning pad and/or blade, which contacts both the outer surface of an interior one 12 and the inner surface of the exterior one 14 of the first and second window elements 12, 14.
Turning now to Figs. 3A and 3B, it may be seen that the cleaning member 22 has an elongate shape and extends across the first and second window elements 12, 14 in a first direction, A-A'. The cleaning member 22 is mechanically coupled at each end to the driving mechanism 20. The two components 20a, 20b of the driving mechanism 20 each comprise a piston cylinder containing a substance, such as an inert gas, which expands on heating and contracts back to its original size on cooling back down. When this substance in the piston cylinders is heated by the oven, it expands, and expansion of the substance causes the two components 20a, 20b to rise in the direction indicated in Fig. 3A by the upwardly pointing arrows on each of the two components 20a, 20b. This in turn provides a motive force to the cleaning member 22, which moves the cleaning member 22 in the direction indicated in Fig. 3A by the arrow B. In contrast, when the oven is switched back off again, the substance in the piston cylinders cools back down again, causing it to contract, and contraction of the substance causes the two components 20a, 20b to sink in the direction indicated in Fig. 3B by the downwardly pointing arrows on each of the two components 20a, 20b. This in turn causes the cleaning member 22 to sink back down again under its own weight, back to its original starting position, in the direction indicated in Fig. 3B by the arrow B'. The arrows B-B' define a second direction, which is substantially perpendicular to the first direction, A-A'.
In Fig. 3A, the total range of movement of the cleaning member 22 from its initial starting position to its highest point and back again is represented by a bracket labelled r, and a linear dimension of the first and second window elements 12, 14 is represented by a bracket labelled h. As can be seen from Fig. 3A, therefore, the range of movement, r, of the cleaning member 22 is greater than the height, h, of the first and second window elements 12,14. The whole of the outer surface 12b of the interior one 12 and the inner surface 14a of the exterior one 14 of the first and second window elements 12, 14 are therefore cleaned by the cleaning member 22 in a wiping action from its initial starting position to its highest point and back again.
The highest point attainable by the cleaning member 22 may be defined by one or more buffers (not shown). In addition, on contact with such buffers, the cleaning blades 24a, 24b may be caused to rotate axially about the first direction, A-A', in order to deposit any dirt collected from the respective surfaces of the first and second window elements 12, 14 into a receptacle or tray also provided in the oven door 10 (also not shown). Such a receptacle or tray may be removable and replaceable by a user, in order to be emptied of the collected dirt. Furthermore, the cleaning blades 24a, 24b are also removable and replaceable by a user so that they may be cleaned to remove any accumulated dirt from them. However, the frequency with which a user may have to carry out such a cleaning operation is considerably less than the frequency with which a user would otherwise have to clean the respective surfaces of the first and second window elements 12, 14 themselves in the absence of such a cleaning member 22.
Whereas in the embodiment shown in Figs. 2 to 3B, the wiping action of the cleaning member 22 is show as being from bottom to top and then from top to bottom of the first and second window elements 12, 14, in other possible embodiments, the cleaning member 22 may instead be oriented substantially vertically, rather than substantially horizontally. In such a case, the wiping action of the cleaning member 22 would be from one side edge of the first and second window elements 12, 14 to an opposite side edge of the first and second window elements 12, 14 instead. Such an embodiment would allow dirt collected from the respective surfaces of the first and second window elements 12,14 to fall under gravity from the cleaning blades 24a, 24b into a receptacle or tray provided in the oven door 10, without any need to axially rotate the cleaning blades 24a, 24b, as just described.
The structure and operation of an embodiment of the driving mechanism 20 may be better understood by reference to Fig. 4. In Fig. 4, it may be seen that the driving mechanism 20 comprises a piston cylinder 200 and a mechanical coupling 23. The piston cylinder 200 in turn comprises a cylinder 201, which contains the substance which expands on heating, and a piston 202, which engages in the cylinder 201 in a gas-tight seal and is able to journal within the cylinder 202. The cylinder 201 is fixedly attached to the oven door 10, whereas the piston 202 is able to move relative to the oven door 10. When the substance within the cylinder 201 is cooled and contracts, only a small portion of the piston 202 protrudes from the cylinder 201. However, when the substance within the cylinder 201 is heated and expands, the piston 202 protrudes from the cylinder 201 to a greater extent. The motion of the piston 202 relative to the oven door 10 which is thus engendered is conveyed to the cleaning member 22 via the mechanical coupling 23. Whereas Fig. 4 shows an embodiment of the driving mechanism 20 wherein the substance which expands on heating comprises a fluid, in other possible embodiments, the substance which expands on heating may alternatively or additionally comprise a solid, such as a bimetallic strip.
Fig. 5 shows an embodiment of a device 30, whereby a range of movement of the substance which expands on heating may be multiplied by a factor of greater than 1 if the range of movement of the substance which expands on heating is less than the desired range of movement of the cleaning member 22 represented in Fig. 3A by the bracket labelled r. As shown in Fig. 5, the device 30 comprises a first member 301, which may be fixedly attached to the driving mechanism 20, a second member 302, which may be fixedly attached to the cleaning member 22, and a gear mechanism 303. When the substance which expands on heating expands, the first member 301 moves in the direction indicated in Fig. 5 by the vertical arrow alongside the first member 301. The motion is transmitted by the gear mechanism 303 to the second member 302, which therefore moves in the direction indicated in Fig. 5 by the vertical arrow alongside the second member 302. However, because of the gearing provided by gear mechanism 303, the range of movement, d₁, of the first member 301 is multiplied by a factor of greater than 1 to give the range of movement, d₂, of the second member 302. Whereas Fig. 5 shows an embodiment of the device 30 wherein this multiplication is provided by a gear mechanism 303, in other possible embodiments, the device 30 may alternatively or additionally comprise a lever mechanism to provide the same multiplication.
Fig. 6 shows an embodiment of an oven 1, of a type which may comprise an oven door 10, such as is described herein. As shown in Fig. 6, the oven 1 has a front facia, which comprises a control panel 2 and a door 10. The door 10 in turn comprises a handle 4, which allows a user to open and close the oven door 10, and a two-layer design of oven-door window as described above, an exterior window element 14 of which can be seen in Fig. 6.
Fig. 7 is a flow diagram of an embodiment of a method 1000a of cleaning an oven door 10, of the type shown and described above in relation to Figs. 2, 3A and 3B. The method 1000a comprises: providing 1001 the oven door 10 with a cleaning member 22 of the type shown and described above in relation to Figs. 2, 3A and 3B, providing 1002 the oven door 10 with a driving mechanism 20 of the type shown and described above in relation to Figs. 2 to 4, mechanically coupling 1003 the driving mechanism 20 to the cleaning member 22, for example using the device 30 shown and described above in relation to Fig. 5, attaching 1004 the oven door 10 to an oven 1, such as that shown in Fig. 6, and heating 1005 the substance which expands on heating from heat within the oven 1, in orderto move the cleaning member 22.
Fig. 8 is a flow diagram of another embodiment of a method 1000b of cleaning an oven door 10. The method 1000b comprises all the same operations as the method 1000a of Fig. 7. However, the method 1000b further comprises one or more additional operations, as follows. When the oven 1 is at ambient temperature, removing 1006a and replacing 1006b at least one of the cleaning blades 24a, 24b. Replacing 1006b at least one of the cleaning blades 24a, 24b may comprise washing 1008 the removed at least one cleaning blade 24a, 24b before replacing it or it may comprise replacing the removed at least one cleaning blade 24a, 24b with a respective new cleaning blade of the same type. This may be carried out either by a user or by a service engineer. Depending on the construction of the oven door 10, the method 1000b may further comprise removing 1007a at least one of the first and second window elements 12, 14 when the oven 1 is at ambient temperature, before removing and replacing the cleaning blade 24a, 24b, and replacing 1007b the same at least one of the first and second window elements 12,14 after replacing the cleaning blade 24a, 24b. For example, if the oven door 10 comprises a user-operable disassembly mechanism, whereby a user may remove at least one of the first and second window elements 12, 14, this may be carried out either by a user or by a service engineer. Alternatively, if the oven door 10 lacks such a user-operable disassembly mechanism, this may be carried out by a service engineer. The method 1000b may alternatively or additionally comprise replenishing the substance which expands on heating when the oven 1 is at ambient temperature. For example, this may be carried out by a service engineer. Depending on the construction of the oven door 10, this may entail firstly removing 1007a at least one of the first and second window elements 12, 14 before replenishing the substance which expands on heating, and replacing 1007b the same at least one of the first and second window elements 12, 14 after replenishing the substance which expands on heating. Alternatively, it may be possible for the substance which expands on heating to be replenished, for example via an inlet valve located on an exterior of the oven 1, without disassembling the oven door 10.

In summary, therefore, the present invention relates to an oven door which has a window allowing a user to view the contents of an oven during cooking, wherein the window has a two-layer design, comprising a first window element, and a second window element which is arranged substantially parallel to and spaced apart from the first window element, forming a cavity therebetween. The cavity, which contains air, improves the thermal insulation of the window, but the window is liable to become dirty with trapped food particles, spilt cooking liquids and the like, which are accidentally introduced into the cavity via air vents. In order to solve this problem, the invention provides the oven door with a cleaning member which is movable within the cavity and in contact with the surfaces of the first and second window elements that are inside the cavity, to wipe these surfaces clean. The cleaning member is mechanically coupled to a driving mechanism, which comprises a substance which expands on heating by the oven and contracts back to its original size on cooling back down. Thus whenever the oven is used for cooking, the substance is heated and expands, and the driving mechanism provides a motive force to the cleaning member which is derived from the expansion of the substance. The surfaces of the first and second window elements within the cavity are therefore cleaned by the movement of the cleaning member. The invention also provides an oven comprising an oven door having such a cleaning mechanism, and a corresponding method of cleaning an oven door. The invention has the advantage that it requires no source of electrical power, such as a motor, and operates from the heat of the oven alone.

Reference Numerals:

1	Oven	30	Device to multiply range of movement
2	Control panel
4	Handle	101, 102
10	Oven door		Side edges of oven door
12	First (interior) window element	200	Piston cylinder
		201	Cylinder
12a, 12b	Inner and outer surfaces of first window element	202	Piston
12a, 12b	Inner and outer surfaces of first window element	301	First member
14	Second (exterior) window element	302	Second member
14	Second (exterior) window element	303	Gear mechanism
14a, 14b		1000a, 1000b
	Inner and outer surfaces of second window element		Method of cleaning an oven door
18a	Lower air vents	1001	Provide oven door with cleaning member
18b	Upper air vents	1002	Provide oven door with driving mechanism
20	Driving mechanism	1002	Provide oven door with driving mechanism
20a, 20b	Components of driving mechanism	1003	Couple driving mechanism to cleaning member
20a, 20b	Components of driving mechanism	1004	Attach oven door to oven
22	Cleaning member	1005	Heat from oven to move cleaning member
23	Mechanical coupling	1005	Heat from oven to move cleaning member
24a, 24b		1006a,1006b
	Cleaning blades		Remove and replace the cleaning pad and/or blade
1007a, 1007b	Remove and replace at least one of the first and second window elements
1008	Wash the cleaning pad and/or blade
1009	Replenishing the substance which expands on heating
A-A'	First direction
B-B'	Second direction
d₁	Range of movement of first member
d₂	Range of movement of second member
r	Range of movement of cleaning member
h	Linear dimension of first and/or second window elements

Claims

An oven door (10) at least comprising:
a first window element (12);

a second window element (14) substantially parallel to and spaced apart from the first window element (12), providing a cavity (16) between the first and second window elements (12, 14);

wherein the first and second window elements (12, 14) each comprise at least a respective inner surface (12a, 14a) for facing an interior of an oven (1) and, substantially parallel thereto, a respective outer surface (12b, 14b) for facing an exterior of the oven (1);

a cleaning member (22) movable within said cavity (16), wherein the cleaning member (22) contacts at least one of the outer surface (12b) of one of the first and second window elements and the inner surface (14a) of the other of the first and second window elements when it moves; and

a driving mechanism (20) at least comprising a substance which expands on heating by the oven (1) and contracts back to its original size on cooling back down, wherein the driving mechanism (20) is mechanically coupled to the cleaning member (22) and provides a motive force derived from expansion of the substance on heating which moves the cleaning member (22) in a range of movement across said at least one of the outer surface (12b) of one of the first and second window elements and the inner surface (14a) of the other of the first and second window elements in a wiping action.
An oven door according to claim 1, wherein the range of movement (r) of the cleaning member (22) is at least as great as a linear dimension (h) of at least one of the first and second window elements (12, 14).
An oven door according to claim 1 or claim 2, wherein the cleaning member (22) has an elongate shape extending across the first and second window elements (12, 14) in a first direction (A-A'), and movement of the cleaning member (22) across said surfaces (12b, 14a) when the substance expands on heating is in a second direction (B-B') substantially perpendicular to the first direction (A-A').
An oven door according to any one of the preceding claims, wherein the driving mechanism (20) is arranged parallel to an edge (101, 102) of the oven door (10) and is invisible through an exterior one (14) of the first and second window elements (12, 14).
An oven door according to any one of the preceding claims, wherein the driving mechanism (20) at least comprises two components (20a, 20b) arranged in parallel to each other alongside opposing side edges (101, 102) of the oven door (10), and the cleaning member (22) extends therebetween.
An oven door according to any one of the preceding claims, wherein the cleaning member (22) at least comprises a removable and replaceable cleaning pad and/or blade (24a, 24b).
An oven door according to any one of the preceding claims, wherein the cleaning member (22) rises upwards (B) when the substance expands on heating and sinks downwards (B') when the substance contracts on cooling back down.
An oven door according to any one of the preceding claims, wherein the driving mechanism (20) at least comprises a device (30) which multiplies by a factor of greater than 1 a range of movement (d₁) of the substance which expands on heating into the range of movement (d₂) of the cleaning member (22).
An oven door according to any one of the preceding claims, wherein the driving mechanism (20) at least comprises a piston cylinder (200) and the substance which expands on heating comprises a fluid contained within said cylinder (200).
An oven (1) comprising an oven door (10) according to any one of the preceding claims.
A method (1000a, 1000b) of cleaning an oven door (10), wherein the oven door (10) at least comprises a first window element (12) and a second window element (14) substantially parallel to and spaced apart from the first window element (12), providing a cavity (16) therebetween, wherein the first and second window elements (12, 14) each comprise at least a respective inner surface (12a, 14a) for facing an interior of an oven (1) and, substantially parallel thereto, a respective outer surface (12b, 14b) for facing an exterior of the oven (1), the method at least comprising:
providing (1001) the oven door (10) with a cleaning member (22) movable within said cavity (16), wherein the cleaning member (22) contacts at least one of the outer surface (12b) of one of the first and second window elements and the inner surface (14a) of the other of the first and second window elements when it moves;

providing (1002) the oven door (10) with a driving mechanism (20) at least comprising a substance which expands on heating by the oven (1) and contracts back to its original size on cooling back down;

mechanically coupling (1003) the driving mechanism (20) to the cleaning member (22) to provide a motive force derived from expansion of the substance on heating which moves the cleaning member (22) across said at least one of the outer surface (12b) of one of the first and second window elements and the inner surface (14a) of the other of the first and second window elements in a wiping action;

attaching (1004) the oven door (10) to an oven (1); and

heating (1005) the substance which expands on heating from heat within the oven (1) to move the cleaning member (22).
A method according to claim 11, wherein the cleaning member (22) at least comprises a removable and replaceable cleaning pad and/or blade (24a, 24b), and the method further comprises, when the oven (1) is at ambient temperature:
removing (1006a) the cleaning pad and/or blade; and

replacing (1006b) the cleaning pad and/or blade.
A method according to claim 12, further comprising, when the oven (1) is at ambient temperature:
removing (1007a) at least one of the first and second window elements (12, 14) before removing and replacing the cleaning pad and/or blade (24a, 24b); and

replacing (1007b) the same at least one of the first and second window elements (12, 14) after replacing the cleaning pad and/or blade (24a, 24b).
A method according to claim 12 or claim 13, further comprising washing (1008) the cleaning pad and/or blade (24a, 24b) between removing and replacing (1006a, 1006b) the cleaning pad and/or blade (24a, 24b).
A method according to any one of claims 11 to 14, further comprising, when the oven (1) is at ambient temperature, replenishing (1009) the substance which expands on heating.