WO2012089449A2

WO2012089449A2 - A thermostat used in household appliances

Info

Publication number: WO2012089449A2
Application number: PCT/EP2011/071874
Authority: WO
Inventors: Ihsan Arslantekin; Erol Karaer
Original assignee: Arcelik Anonim Sirketi
Priority date: 2010-12-27
Filing date: 2011-12-06
Publication date: 2012-07-05
Also published as: EP2659324B1; CN103282849A; CN103282849B; WO2012089449A3; EP2659324A2

Abstract

The present invention relates to a thermostat (1) which controls the temperature in household appliances, for example in cooking devices, comprising a thermostat box (2) connected to the temperature adjustment button and containing therein mechanisms providing control of temperature, a sensing tube (3) shaped as a metal tube, detecting the temperature, a capillary tube (4), produced from thin and bendable metal, containing a fluid material therein that expands with heat, one end connected to the thermostat box (2), the other end to the sensing tube (3), transmitting the temperature effect detected by the sensing tube (3) to the thermostat box (2) by changing it to pressure effect and wherein the ends of the capillary tube (4) and the sensing tube (3) are inserted into one another and connected by welding at a joint (5).

Description

A THERMOSTAT USED IN HOUSEHOLD APPLIANCES

The present invention relates to a thermostat used in household appliances and which provides the temperature to be controlled.

In household appliances, for example in cooking devices, the heater is controlled by a thermostat and the cooking process is provided to be performed at the adjusted temperature. The thermostat comprises a thermostat box, connected to the temperature adjustment button, containing therein the mechanisms that provide the heater to be turned on or off so as to provide the desired temperature, a heat sensor or “bulb”, as commonly named formed as a thin tube, providing the temperature to be detected, a capillary tube, with one end connected to the heat sensor, the other end to the thermostat box, containing a fluid therein that expands with heat and transmits the temperature detected by the thermostat to the thermostat box by changing it to pressure effect. The thermostat is supplied from the subsidiary industry, generally in form of the capillary tube wrapped as a coil and one end connected by weld to the heat sensor (bulb). While mounting the thermostat to the cooking devices, the thermostat box is mounted to the rear of the button on the front panel, the heat sensor is pulled together with the capillary tube, whereto it is connected by welding and extended to the rear side of the cooking device and disposed into the oven cavity, meanwhile the windings on the capillary tube coil are unwound. During the said assembly of the thermostat, the welding region connecting the capillary tube with the heat sensor can be strained and cracks may occur which cannot be noticed during the assembly. Due to the damage in the welding region, the fluid in the capillary tube flows out and the thermostat cannot function properly. During the assembly of the thermostat, while the coil is unwound whereto the capillary tube is wound, the sensor is pulled together with the capillary tube and disposed to the rear side of the cooking device, in the meantime the bending, folding, torsion effects occurring in the capillary tube can strain the welding region at the joint of the capillary tube and the sensor. In known embodiments, in order to solve this problem, a tube shaped sleeve is used that wraps around the welding region, preventing the bending motion in the capillary tube from reaching the welding region, however the torsion movement in the capillary tube cannot be prevented from reaching the joint and the welding region is damaged by being strained.

In the state of the art United States Patent No. US4333669, a brazed or soldered joint between the capillary tube and the sensor in a thermostat is explained.

In the state of the art European Patent No. EP0578096, the soldered connection between the capillary tube and the sensing tube in a thermostat is explained.

The aim of the present invention is the realization of a thermostat, used in household appliances for controlling the temperature and wherein the sensor and the capillary tube are prevented from breaking off from the welding region during the assembly thereof.

The thermostat realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, comprises a thermostat box, a metal sensing tube that can detect heat or the bulb as it is widely named, a capillary tube, produced from thin and bendable metal, one end connected to the bulb and a protecting sleeve extending from the bulb to the capillary tube by surrounding the joint at the welded connection and containing slots thereon, through which the capillary tubes are inserted. The edges of the slots on the protecting sleeve, clasp the capillary tube by partially surrounding it, thus holding the inserted capillary tube like clips, pincers or latch, prevents the torsion movement in the capillary tube from reaching the welded joint and damaging the weld during the assembly of the thermostat.

The protecting sleeve has a C-shaped cross-section, that is shaped as a not-entirely-closed tube, produced by rounding and bending a thin sheet-metal strip, and two slots are disposed on its edges facing each other, made by cutting-out the edges, one close to the joint and the other away from the joint. The slots are preferably eccentrically aligned and provide the capillary tube to form a partial helical winding outside the protecting sleeve.

In an embodiment of the present invention, T shaped slots are disposed on the protecting sleeve that provide the capillary tube to be clasped better.

In another embodiment of the present invention, a support protrusion is disposed inside the protecting sleeve, against which the end of the bulb bears, preventing the capillary tube from bending inside the protecting sleeve.

The protecting sleeve prevents the bulb and the capillary tube from breaking off from the joint where the bulb and the capillary tube are connected by welding and hence prevents the thermostat from becoming unfunctional while still at the assembly phase, and the thermostat related malfunctions in the household appliance, for example in the cooking device wherein the thermostat is used are decreased.

The thermostat realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

Figure 1 - is the perspective view of a thermostat.

Figure 2 - is the perspective view of the thermostat mounted to a cooking device.

Figure 3 - is the perspective view of a protecting sleeve.

Figure 4 - is the front view of the protecting sleeve mounted to the joint of the sensing tube and the capillary tube.

Figure 5 - is the perspective view of the protecting sleeve mounted to the joint of the sensing tube and the capillary tube.

Figure 6 - is the perspective view of the protecting sleeve mounted to the joint of the sensing tube and the capillary tube from another angle.

The elements illustrated in the figures are numbered as follows:

Thermostat
Thermostat box
Sensing tube
Capillary tube
Joint
Protecting sleeve
Slot
Support protrusion

The thermostat (1) which controls the temperature, suitable for use in household appliances, for example in cooking devices, refrigerators and washers, comprises a thermostat box (2) connected to the temperature adjustment button and containing therein mechanisms providing control of temperature, a metal sensing tube (3) detecting the temperature or the bulb, with its widely used name, a capillary tube (4), produced from thin and bendable metal, containing a fluid material therein that expands with heat, one end connected to the thermostat box (2), the other end to the sensing tube (3), transmitting the temperature effect detected by the sensing tube (3) to the thermostat box (2) by changing it to pressure effect and the diameter of which is less than the diameter of the sensing tube (3), a joint (5) wherein the ends of the capillary tube (4) and the sensing tube (3) are inserted into one another and connected by welding.

The thermostat (1) of the present invention comprises a protecting sleeve (6), shaped by rounding and bending a thin sheet-metal strip, with C shaped cross-section, formed as a longitudinally open or closed tube, mounted to the sensing tube (3), extending from the sensing tube (3) to the capillary tube (4) by surrounding the joint (5) and more than one slot (7, 107) disposed on the protecting sleeve (6), through which the capillary tube (4) is inserted, the sides of which clasp the capillary tube (4) by partially surrounding, thus holding the capillary tube (4) inserted therethrough like clips, pincers or latch and preventing the torsion movement in the capillary tube (4) from reaching the joint (5) during the assembly of the thermostat (1).

The diameter of the sensing tube (3) is greater than the diameter of the capillary tube (4) and the capillary tube (4) is connected to the sensing tube (3) by welding or soldering at the joint (5). The protecting sleeve (6) is fixed by being snap-fitted on the end of the sensing tube (3) that extends to the joint (5), and surrounds the joint (5) and the end of the capillary tube (4) that extends to the joint (5). Since the diameter of the capillary tube (4) is very small (for example 1 mm), it extends inside the protecting sleeve (6) with a clearance. The end of the capillary tube (4) extending to the joint (5) passes through the slots (7, 107) and partially extends over the outer surface of the protecting sleeve (6). During assembly, after the protecting sleeve (6) is mounted, the capillary tube (4) is inserted through the first slot (7) behind the joint (5) and taken outside the protecting sleeve (6), and after partially surrounding the outer surface of the protecting sleeve (6), is inserted through the second slot (107) to be taken inside the protecting sleeve (6) again and is taken outside from the end of the protecting sleeve (6). The edges of the slots (7, 107) clasp the capillary tube (4) passing therethrough and prevent the torsion movement in the capillary tube (4) from reaching the joint (5) and straining the welded place during the assembly process.

In an embodiment of the present invention, the thermostat (1) comprises two eccentrically aligned slots (7, 107) bored by inwardly cutting-out the edges of the protecting sleeve (6) facing each other, one near the joint (5), the other away from the joint (5).

In an embodiment of the present invention, the thermostat (1) comprises T shaped slots (7, 107) bored on the edges of the protecting sleeve (6) facing each other. Thus, the edges of the slots (7, 107) clasp and tightly hold the capillary tube (4) and the torsion movement in the capillary tube (4) is prevented from reaching the joint (5).

In another embodiment of the present invention, the thermostat (1) comprises a support protrusion (8), disposed inside the protecting sleeve (6), bearing against the end of the sensing tube (3) extending to the joint (5), keeping the distance of the capillary tube (4) fixed between the joint (5) and the slot (7, 107) where through it passes, thus preventing the capillary tube (4) from bending near the joint (5) inside the protecting sleeve (6) and damaging the welded place.

The thermostat (1) breaking off from the joint (5) where the sensing tube (3) and the capillary tube (4) are joined by welding is prevented by means of the protecting sleeve (6). The protecting sleeve (6), by means of the slots (7, 107) disposed thereon and through which the capillary tube (4) is inserted, prevents the torsion movements created in the capillary tube (4) during the assembly from reaching the joint (5) and damaging the welded connection there.

It is to be understood that the present invention is not limited by the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection disclosed by the claims of the present invention.

Claims

A thermostat (1) suitable for use in household appliances, comprising a thermostat box (2), a metal sensing tube (3) shaped as a metal tube, detecting the temperature, a capillary tube (4), produced from thin and bendable metal, one end connected to the thermostat box (2), the other end to the sensing tube (3), a joint (5) where the ends of the capillary tube (4) and the sensing tube (3) are inserted into one another and connected by welding, characterized in that a protecting sleeve (6), mounted to the sensing tube (3) and extending from the sensing tube (3) to the capillary tube (4) by surrounding the joint (5) and more than one slot (7, 107) disposed on the protecting sleeve (6), through which the capillary tube (4) is inserted, the sides of which clasp the capillary tube (4) by partially surrounding, thus preventing the torsion movement in the capillary tube (4) from reaching the joint (5) during the assembly.
A thermostat (1) as in Claim 1, characterized in that the protecting sleeve (6) shaped by rounding and bending a thin sheet-metal strip so that the cross-section thereof is C shaped.
A thermostat (1) as in Claim 1 or 2, characterized in that two slots (7, 107) bored by inwardly cutting-out the edges of the protecting sleeve (6) facing each other, one near the joint (5), the other away from the joint (5).
A thermostat (1) as in any one of the above Claims, characterized in that two eccentrically aligned slots (7, 107) on the protecting sleeve (6).
A thermostat (1) as in any one of the above Claims, characterized in that two T shaped slots (7, 107) bored on the edges of the protecting sleeve (6) facing each other.
A thermostat (1) as in any one of the above Claims, characterized in that a support protrusion (8), disposed inside the protecting sleeve (6), bearing against the end of the sensing tube (3) extending to the joint (5) and preventing the capillary tube (4) from bending near the joint (5) inside the protecting sleeve (6).
A cooking device characterized in that a thermostat (1) as in any one of the above Claims, comprising the protecting sleeve (6) containing slots (7, 107) thereon.
A refrigerator characterized in that a thermostat (1) as in any one of the Claims 1 to 6, comprising the protecting sleeve (6) containing slots (7, 107) thereon.