GB2172749A

GB2172749A - Thermostat

Info

Publication number: GB2172749A
Application number: GB08606491A
Authority: GB
Inventors: Jean Serigny
Original assignee: Cotherm SA
Current assignee: Cotherm SA
Priority date: 1985-03-18
Filing date: 1986-03-17
Publication date: 1986-09-24
Also published as: FR2579013B1; GB8606491D0; GB2172749B; IT1236574B; IT8647771A0; FR2579013A1

Abstract

In order to be able to fix a rod and tube actuator 2 of a thermostat to a plastics base 1 and in order to be able to provide a safety device for cutting off the supply of heat if the temperature rises too high, the tube 3 is fastened in a bore 6a of a boss 6 of a heat conductive dish 5 by force fitting a sleeve 7 in the end of the tube 3. The dish 5 comprises two vertical tabs 10,9 which engage in slots 11,12 in the base 1, parts of the tabs 10,9 being folded down against shoulders in the slots 11,12 to secure the dish 5 to the base 1. A reversible concave washer 14 is disposed in the dish 5 and cooperates with a slide block 15 capable of cutting off the supply current when too high a temperature is communicated to this washer 14. <IMAGE>

Description

SPECIFICATION Immersion tube thermostat The present invention relates to improvements in or relating to thermostats incorporating an immersion tube.

Thermostats of the type in question comprise a base which is more and more frequently made of an appropriate plastics material such as a polyester compound. It is therefore necessary to provide a particular mode of fixing the immersion tube with respect to this base to take into account the particular qualities of strength of this plastics material. Moreover, it will be readily appreciated that a thermostat must comprise a safety device adapted to cut off supply of heating to the enclosure in which its immersion tube is disposed, in the event of untimely rise in the temperature of this enclosure.

It is an object of the improvements according to the present invention to produce a particularly appropriate connection of the cylindrical casing of the immersion tube, said connection being associated with means for actuating cut-off switches ensuring operational safety.

To this end, the end of the metallic cylindrical casing of the immersion tube is connected to the base of the thermostat by a good heatconducting dish of which the centre is provided with a boss in the bore of which said end is fastened, said dish abutting against one of the faces of the base, whilst it is provided with two tabs which pass therethrough and are adapted to be folded down at least partially against its opposite face.

The dish comprises a peripheral flange against which rests a reversible concave washer which is deformed under the action of a determined temperature of said dish with a view to actuating a slide block of which the displacement provokes cut-off of the heating circuit of the enclosure in which the immersion tube of the thermostat is disposed.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Figure 1 is a transverse section through an immersion tube thermostat comprising the improvements according to the invention.

Figure 2 is a view in perspective with parts torn away of part of the base of the thermostat according to the invention.

Figure 3 is a view in perspective of the dish to which the end of the cylindrical casing of the immersion tube is fastened.

Figure 4 is a view similar to that of Fig. 2, but in which the dish of Fig. 3 has been shown after assembly with the base.

Referring now to the drawings, the thermostat illustrated in Fig. 1 essentially comprises a base 1 made of a plastics material such as a polyester compound, and which supports, on the one hand, the mechanism controlling the supply circuit of a heating system and, on the other hand, an immersion tube 2. The latter is composed of a metallic cylindrical casing 3 enclosing a rod 4 made of a non-dilatable material such as a ferronickel with 36% of nickel.

The free ends of the cylindrical casing and of the rod are associated in conventional manner by hammering or welding.

In accordance with the invention, the opposite end of the metal casing 3 is fastened to a metal dish 5 illustrated in Fig. 3. Said dish comprises a central boss 6 in the bore 6a of which the tube is engaged with snug sliding fit, whilst a tubular sleeve 7 is engaged by force in the end in question of the casing 3 so that said end is sandwiched between the outside of this sleeve and the bore 6a. An excellent assembly of the casing and of the dish 5 is thus effected.

The presence is observed of two diametrically opposite tabs upstanding perpendicularly to the peripheral flange 8 of the dish 5. Tab referenced 9 comprises a base 9a and a head 9b in the form of a perforated diamond in its centre. The other tab 10 comprises a vertical extension 10a of which the base is adjacent two wings 10b, 10c oriented in the same direction as the extension 10a and separated therefrom by two notches 10d, 10e.

In base 1 are made a slot 11 (Fig. 2) through which tab 10 passes and a passage 12 in which tab 9 engages.

Passage 12 comprises a horizontal shoulder 1 2a against which head 9b of tab 9 is flattened as illustrated in Fig. 4 so as to retain dish 5 axially with respect to the base 1.

Similarly, slot 11 is provided with a shoulder determining two faces 11 a and 11 b oriented horizontally and against which the two wings 10b and 10c of tab 10 are folded down in order to constitute a second fixation of dish 5 with respect to base 1. It is observed in Fig. 1 that extension 10a of tab 10 passes beyond the base 1 in order to serve as articulation for one of the ends of a pivoting blade 13 actuated by the rod 4 during variations in temperature prevailing within the enclosure in which the immersion tube 2 is disposed.

According to another feature of the invention, a reversible concave washer 14 is disposed inside the dish 5, its periphery resting on the flange 8 thereof. Above the washer is a slide block 15 traversed by rod 4 and which may move vertically in reciprocal motion in an appropriate opening 16 made transversely in the base 1. The washer is, of course, pierced so that the rod 4 can also traverse it. If the temperature of the metal casing 3 rises above a determined threshold, the temperature of dish 5 is established at a very similar temperature. The heat stored by the dish is transmitted to washer 14 whose structure is such that a rise in temperature causes it to blister, i.e. change it curvature, with the result that, being upwardly concave in the normal state, it becomes downwardly concave (as illustrated in discontinuous lines in Fig. 1) when its temperature exceeds a certain limit. Upward deformation of washer 14 brings about a displacement in the same direction of slide block 15. Its upper face which lies inside the casing 17 of the thermostat rises and opens the circuit for supplying and/or controlling heating of the enclosure in which the immersion tube 2 is disposed.

It must, moreover, be understood that the foregoing description has been given only by way of example and that it in no way limits the domain of the invention which would not be exceeded by replacing the details of execution described by any other equivalents.

Claims

1. A thermostat incorporating an immersion tube, wherein the end of the metallic cylindrical casing of this tube is connected to the base of this thermostat by a good heatconducting dish of which the centre is provided with a boss in the bore of which said end is fastened, said dish abutting against one of the faces of the base, and it is provided with two tabs which pass therethrough and are adapted to be folded down at least partially against its opposite face.

2. A thermostat as claimed in Claim 1, wherein one of the tabs of the dish constitutes an articulation for the pivoting blade of the mechanism of the thermostat.

3. A thermostat as claimed in Claim 1, wherein the end of the cylindrical casing connected to the base is sandwiched between the bore of the boss of the dish and a metal inner sleeve.

4. A thermostat as claimed in Claim 1, wherein one of the tabs of the dish takes the form of a perforated polygon and this tab is engaged in a passage in the base in order to be flattened against a shoulder of this passage.

5. A thermostat as claimed in Claim 2, wherein one tab of the dish comprises two wings which are folded down against the bottom of the lateral extensions of a slot in the base which said tab traverses, and it constitutes an articulation for the blade.

6. A thermostat as claimed in any one of the preceding Claims, wherein a reversible concave washer rests against a peripheral flange of the dish so that it deforms under the action of a rise in temperature above a determined threshold of said dish with a view to actuating a slide block whose displacement provokes cut-off of the heating circuit of the enclosure in which the immersion tube is disposed.

7. A thermostat, substantially as herein described with reference to, and as shown in, the accompanying drawings.