GB2138259A

GB2138259A - Thermostat for combined gas or electric and microwave oven

Info

Publication number: GB2138259A
Application number: GB08407326A
Authority: GB
Inventors: Ruggero Roccari; Arturo Negretti; Walter Zanzani
Original assignee: Industrie Zanussi SpA
Current assignee: Industrie Zanussi SpA
Priority date: 1983-04-07
Filing date: 1984-03-21
Publication date: 1984-10-17
Also published as: FR2544073A3; GB8407326D0; GB2138259B; ES278207U; FR2544073B3; ES278207Y; IT8334017V0; DE8410366U1

Abstract

A thermostat for an oven of domestic combined gas or electric and microwave type, comprises a bulb (2) which is disposed within the muffle of the oven and a capillary member (3) which passes through the wall of the muffle and which is connected on the one hand to the bulb and on the other hand to the switch of the thermostat, the bulb (2) and the portion of the capillary member (3) which is inserted into the muffle being covered with a metal mesh braiding (1) which is closed at one end and fixed at the other end to the wall (11) of the muffle by means of clamping means (5,6, 7) capable of ensuring electrical connection between the braiding (1) and the wall (11). The end (10) at which the braiding (1) is fixed to the wall (11) is turned over and welded or soldered to a screwthreaded ferrule (7) co-operable with a nut (5) for fixing the braiding (1) to the wall (11), preferably with the interposition of a washer (6). <IMAGE>

Description

SPECIFICATION Thermostat for combined gas or electric and microwave oven The present invention relates to a thermostat for an oven, in particular a domestic oven of combined type in which the food is heated and cooked by way of gas or electric means and microwave means.

As is known, domestic ovens are provided with thermostats for controlling the temperature inside the cooking oven compartment. Such thermostats are disposed outside or inside the cooking oven compartment and obviously those which are disposed inside afford a higher degree of operating accuracy.

When however a conventional gas or electric oven is to be equipped with a microwave generator device for converting it into a combined oven, the presence of the thermostat gives rise to the problem of ensuring that the latter does not form an antenna which transmits the microwave radiation to the exterior.

A known solution to that problem comprises providing the thermostat with a hermetically sealed metal sheath which is electrically connected to the metal wall of the oven compartment. That solution is effective but gives rise to a number of disadvantages: firstly, it reduces the sensitivity of the bulb of the thermostat which is no longer directly in contact with the heated airwithin the oven,while mounting the thermostat with a rigid sheath is a difficult operation in particular in the conventional ovens which are to be converted into combined ovens by the installation of the microwave generator device.

According to the present invention, there is provided an oven of combined gas or electric and microwave type, comprising a muffle wall, a bulb which is disposed within the muffle and a capillary member which passes through the wall of the muffle and is connected on the one hand to the bulb and on the other hand to the switch of the thermostat, the bulb and the portion of the capillary member which is inserted into the muffle being covered with a metal mesh braiding which is closed at one end; and clamping means (5, 6, 7) capable of ensuring electrical connection between the braiding (1) and the wall ( 11 ) for fixing atthe other end of the braid to the wall orthe muffle.

As will become apparent from the following description, the invention can provide a thermostat which can be applied easily and conveniently to a conventional oven converted to a combined microwave oven while maintaining the required degree of sensitivity and avoiding causing radiation leaks.

These and other features of the invention will be apparent from the following description given by way of non-limiting example, with reference to the accompanying drawings in which: Figure 1 shows a view in diagrammatic crosssection of part of the thermostat according to the invention, fitted into the muffle of the oven, and Figure 2 shows the details of the fixing of the thermostat in Figure 1 to the wall of the muffle.

According to the invention, the thermostat is fitted into the muffle of the oven by way of a suitable opening provided in the wall 11 and comprises a bulb 2 and a capillary member 3 connected to the bulb 2 and issuing from the muffle to be connected to the switch of the thermostat (not shown).

To prevent the bulb 2 and the capillary member 3, which are of metal, from acting as an antenna and conducting energy to the exterior of the oven when an electromagnetic field is present in the muffle for generating microwaves, it is necessary to protect them without however influencing the characteristic in regard to the thermal performance ofthethermo- stat.

The bulb 2 and the caplillary member 3 are thus enclosed in a metal mesh braiding 1 which is closed at one end 4 and which is suitably connected electrically to the wall 11 of the muffle, as will be seen hereinafter.

The mesh braiding 1 permits air to pass from the cooking compartment of the oven into contact with the bulb, thus ensuring the required sensitivity on the part of the thermostat.

The braiding 1 which passes through the wall 11 of the muffle is fixed to the wall 11 by means of a ferrule 7, a nut 5 and possibly a toother washer 6, all those components being of metal.

The end of the braiding 1 which extends out of the muffle is turned over so as to form a collar 10 which is fixed in any known manner (welding, soldering, adhesive, etc) to the ferrule 7.

The arrangement is very simple to assemble. The bulb 2 and the capillary member 3 are threaded into the braiding 1. The braiding 1 is then fitted into the ferrule 7 and the end 10 of the braiding is turned over, fixing it to the ferrule 7. After the washer 6 has possibly fitted, the braiding 1 is inserted through the opening formed in the wall 11 of the oven until the screwthreaded end of the ferrule 7 projects into the oven.

The arrangement is very simple to assemble. The bulb 2 and the capillary member 3 are threaded into the braiding 1. The braiding 1 is then fitted into the ferrule 7 and the end 10 of the braiding is turned over, fixing it to the ferrule 7. After the washer 6 has possibly been fitted, the braiding 1 is inserted through the opening formed in the wall 11 of the oven until the screwthreaded end of the ferrule 7 projects into the oven.

The arrangement is easy to insert, simply having to be oriented along the curvature of the capillary member 3 and the braiding 1. the nut 5 is then fitted by sliding it over the braiding 1, bringing it into a position to be screwed onto the screwthreaded end of the ferrule 7. The braiding 1 is made of metal material (for example copper) in order to be a good conductor of both heat and electricity.

Electrical contact is ensured by the fixing elements (5, 6, 7) even in the situation where the wall 11 of the oven is enamelled or painted, as in many domestic ovens.

1. An oven of combined gas or electric and microwave type, comprising a muffle wall, a bulb

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Thermostat for combined gas or electric and microwave oven The present invention relates to a thermostat for an oven, in particular a domestic oven of combined type in which the food is heated and cooked by way of gas or electric means and microwave means. As is known, domestic ovens are provided with thermostats for controlling the temperature inside the cooking oven compartment. Such thermostats are disposed outside or inside the cooking oven compartment and obviously those which are disposed inside afford a higher degree of operating accuracy. When however a conventional gas or electric oven is to be equipped with a microwave generator device for converting it into a combined oven, the presence of the thermostat gives rise to the problem of ensuring that the latter does not form an antenna which transmits the microwave radiation to the exterior. A known solution to that problem comprises providing the thermostat with a hermetically sealed metal sheath which is electrically connected to the metal wall of the oven compartment. That solution is effective but gives rise to a number of disadvantages: firstly, it reduces the sensitivity of the bulb of the thermostat which is no longer directly in contact with the heated airwithin the oven,while mounting the thermostat with a rigid sheath is a difficult operation in particular in the conventional ovens which are to be converted into combined ovens by the installation of the microwave generator device. According to the present invention, there is provided an oven of combined gas or electric and microwave type, comprising a muffle wall, a bulb which is disposed within the muffle and a capillary member which passes through the wall of the muffle and is connected on the one hand to the bulb and on the other hand to the switch of the thermostat, the bulb and the portion of the capillary member which is inserted into the muffle being covered with a metal mesh braiding which is closed at one end; and clamping means (5, 6, 7) capable of ensuring electrical connection between the braiding (1) and the wall ( 11 ) for fixing atthe other end of the braid to the wall orthe muffle. As will become apparent from the following description, the invention can provide a thermostat which can be applied easily and conveniently to a conventional oven converted to a combined microwave oven while maintaining the required degree of sensitivity and avoiding causing radiation leaks. These and other features of the invention will be apparent from the following description given by way of non-limiting example, with reference to the accompanying drawings in which: Figure 1 shows a view in diagrammatic crosssection of part of the thermostat according to the invention, fitted into the muffle of the oven, and Figure 2 shows the details of the fixing of the thermostat in Figure 1 to the wall of the muffle. According to the invention, the thermostat is fitted into the muffle of the oven by way of a suitable opening provided in the wall 11 and comprises a bulb 2 and a capillary member 3 connected to the bulb 2 and issuing from the muffle to be connected to the switch of the thermostat (not shown). To prevent the bulb 2 and the capillary member 3, which are of metal, from acting as an antenna and conducting energy to the exterior of the oven when an electromagnetic field is present in the muffle for generating microwaves, it is necessary to protect them without however influencing the characteristic in regard to the thermal performance ofthethermo- stat. The bulb 2 and the caplillary member 3 are thus enclosed in a metal mesh braiding 1 which is closed at one end 4 and which is suitably connected electrically to the wall 11 of the muffle, as will be seen hereinafter. The mesh braiding 1 permits air to pass from the cooking compartment of the oven into contact with the bulb, thus ensuring the required sensitivity on the part of the thermostat. The braiding 1 which passes through the wall 11 of the muffle is fixed to the wall 11 by means of a ferrule 7, a nut 5 and possibly a toother washer 6, all those components being of metal. The end of the braiding 1 which extends out of the muffle is turned over so as to form a collar 10 which is fixed in any known manner (welding, soldering, adhesive, etc) to the ferrule 7. The arrangement is very simple to assemble. The bulb 2 and the capillary member 3 are threaded into the braiding 1. The braiding 1 is then fitted into the ferrule 7 and the end 10 of the braiding is turned over, fixing it to the ferrule 7. After the washer 6 has possibly fitted, the braiding 1 is inserted through the opening formed in the wall 11 of the oven until the screwthreaded end of the ferrule 7 projects into the oven. The arrangement is very simple to assemble. The bulb 2 and the capillary member 3 are threaded into the braiding 1. The braiding 1 is then fitted into the ferrule 7 and the end 10 of the braiding is turned over, fixing it to the ferrule 7. After the washer 6 has possibly been fitted, the braiding 1 is inserted through the opening formed in the wall 11 of the oven until the screwthreaded end of the ferrule 7 projects into the oven. The arrangement is easy to insert, simply having to be oriented along the curvature of the capillary member 3 and the braiding 1. the nut 5 is then fitted by sliding it over the braiding 1, bringing it into a position to be screwed onto the screwthreaded end of the ferrule 7. The braiding 1 is made of metal material (for example copper) in order to be a good conductor of both heat and electricity. Electrical contact is ensured by the fixing elements (5, 6, 7) even in the situation where the wall 11 of the oven is enamelled or painted, as in many domestic ovens. CLAIMS

1. An oven of combined gas or electric and microwave type, comprising a muffle wall, a bulb which is disposed within the muffle and a capillary member which passes through the wall of the muffle and which is connected on the one hand to the bulb ad on the other hand to the switch of the thermostat, the bulb and the portion of the capillary member which is inserted into the muffle being covered with a metal mesh braiding which is closed at one end; and clamping means (5, 6, 7) capable of ensuring electrical connection between the braiding (1) and wall (11) for fixing at the other end of the braid to the wall of the muffle.

2. Athermostatfor an oven according to claim 1 wherein the end at which the braiding is, in use, fixed to the wall is turned over and welded or soldered to a screwthreaded ferrule co-operable with a nutforfixing the braiding to the wall.

3. An oven of combined gas or electric and microwave type, comprising a muffle wall and a bulb which is disposed within the muffle and a capillary member which passes through the wall of the muffle and which is connected on the one hand to the bulb and on the other hand to the switch of the thermostat, the bulb and the portion of the capillary member which is inserted into the muffle being covered with a metal mesh braiding which is closed at one end and fixed at the other end to the wall of the muffle by means of clamping means capable of ensuring electrical connection between the braiding and the wall.

4. A thermostat constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

5. An oven incorporating a thermostat according to any one of claims 1,2 and 4.