GB2046906A

GB2046906A - Thermally expandible element

Info

Publication number: GB2046906A
Application number: GB8008251A
Authority: GB
Original assignee: Friedrich Grohe Armaturenfabrik GmbH and Co
Current assignee: Grohe Water Technology AG and Co KG
Priority date: 1979-04-04
Filing date: 1980-03-11
Publication date: 1980-11-19
Also published as: GB2046906B; IT1140833B; IT8021158A0; DK545679A; DE2913425A1; FR2456943A1; SE8002196L; DE2913425C2

Abstract

A thermally expandible element for use, for example, in valves for mixing hot and cold water in sanitary fittings, comprises a housing including a relatively rigid plate-like housing member (1) to which is mounted a corrugated pipe (3). The interiors of the housing member (1) and the pipe (3) intercommunicate and are filled with a thermally expandible operating material, for example, a fluorohydrocarbon. Changes in the volume of the operating material upon temperature variations cause corresponding changes (deflections) in the corrugated pipe. An alternative embodiment comprises two pipes each with an integral housing plate by which they are mounted to each other end-to-end (Fig. 4, not shown). Methods of manufacturing the elements are also disclosed. <IMAGE>

Description

SPECIFICATION Thermally expandible element This invention relates to a thermally expandible element, particularly but not exclusively for use in valves for mixing hot and cold water in sanitary fittings and a method of producing such an element.

A number of expandible elements are known for the regulation of mixer valves. In the main, a differentiation can be made into three main groups: 1. Wax elements with a displacement pis ton 2. Metal bellows filled with liquid 3. Bimetallic elements Nevertheless, these known devices do not completely meet the requirements made of a mixer valve for use in the sanitary engineering field, in particular, in regard of rapid response sensitivity, constant functionability over a long period of time, and a relatively high actuating force produced by the element.

The wax elements commercially obtainable have a dispacement piston by means of which the set volume is dispensed. For sealing purposes, a rubber transfer element is provided between the displacement piston and the expandible material. Apart from a relatively sluggish time response (high time constant), the elements exhibit hysteresis and deflection losses in their function after a longer period of time in use.

In the case of metal bellows filled with liquid, an unfavourable response behaviour is manifested which is caused to a large extent by their relatively high volume. In addition, the use of liquid-filled metal bellows as a rule requires a relatively high installed height of the valve.

Although bimetallic elements exhibit very quick response to changes in temperature, they can only produce low actuating forces because of their low rigidity.

The present invention is based upon the need to create an expandible element which responds rapidly to changes in temperature, functions over a long period of time without hysteresis and deflection losses, and generates a relatively high actuating force, and also to specify a process for the manufacture of the expandible element.

According to one aspect of the present invention there is provided a thermally expandible element including a predetermined volume of a thermally expandible operating material arranged within a sealed housing comprising a rigid plate-like member to which is mounted at least one corrugated pipe such that changes in the volume of the operating material with variations in temperature are accommodated by corresponding changes in the dimensions of the corrugated pipe.

According to another aspect of the present invention there is provided a method of manufacturing a thermally expandible element including the step of connecting the individual components of the housing together in a leaktight manner whilst immersed in a bath of the thermally expandible operating material which is in a liquid state.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows the individual components of an expandible element in longitudinal section; Figure 2 shows a plan view of the expandible element of Fig. 1 partially cut-away; Figure 3 shows a filled and welded expandible element of Fig. 1 in longitudinal section; and Figure 4 shows another expandible element in longitudinal section, two deep-drawn sections being shown in the left-hand half and a finished, filled and welded expandible element being shown in the right-hand half.

The expandible element shown in Figs. 1 to 3 is axisymmetrical in structure and consists in the main of a rigid, plate-like housing 1, formed by a bottom part 1 a and a cover 2, indentations 4 being formed on the end faces thereof to increase the rigidity and extend the surface area. The cover 2 and the bottom part 1 a are in intimate, when assembled, via an outer flange 5 of the bottom part 1 a.

In addition, a cylindrical indentation 6 is formed centrally in the cover 2, apertures 7 being provided therein to allow an expandible operating material to pass through, and, when assembled, the end face of which identation 6 rests upon the bottom part 1 a. A further (inner) flange 8 is formed on the outside of the cover 2 concentrically to the cylindrical indentation 6, a corrugated pipe 3 being attachable to the same by its flange 11. The expandible element is made by first welding the bottom part 1 a to the cover 2 at the end face of the cylindrical indentation 6. Thereafter, the external enclosing flange 5 of the bottom part 1 a and the cover 2 are welded.

The partial housing which results is filled with a liquid fluorohydrocarbon, which does not conduct electricity, comprising the expandible operating material and is leak-tight welded to the corrugated pipe 3, which is closed at one end and also filled with the liquid hydrocarbon at the flanges 8 and 11 in a bath of the liquid hydrocarbon. The expandible operating material 10, hermetically sealed by the annular welding points 9 in the casing 1, and shown in particular in Fig. 3, has the effect that, upon any change in the ambient temperature, the change in temperature sensed is directly transferred into a deflection or change in length of the corrugated pipe 3. The deflection can be summated by combining a number of expandible elements in accordance with the invention such that a very long stroke can be obtained with relatively high actuating force.

Of course, the leak-tight connections required at the housing of the expandible element can also be provided by crimp-flanging, edging, etc. In so doing, an expandible operating material which conducts electricity can also be employed.

Another example of an embodiment of an expandible element is shown in Fig. 4.

The casing 2Q here is formed by two identical dished parts 21. Each dished part 21 is formed of one piece and can, to good advantage, be produced from one sheet bar by the deep-drawing process, an extension 22 being produced in the centre by stretching (cf, lefthand half of Fig. 5) which can be formed thereafter into a corrugated pipe 3. The end faces 24 are dished inwards in a dome fashion in order that the housing 20 can exhibit the required rigidity.

On assembly, the two dished sections 21 are first filled with liquid expandible operating material and then joined leak-tight at the flanges 23 by means of an annular welding seam 9 in a bath of liquid expandible operat- ing material.

By means of the thermally expandible element of the invention, it is brought about that the expansion of a relatively high expandible operating material volume in a plate-like housing is transferred to an intrinsically flexible corrugated pipe of considerably smaller diameter. The high transmission ratio thus produced is obtained both by the diameter and the volume ratio between the housing and the corrugated pipe. The plate-like housing is rigid in form in order that the expansion of the expandible operating material is transferred only to the corrugated pipe designed and intended for this purpose on changes in temperature. The low height to diameter ratio of the plate-like housing not only results in favourably large surfaces to absorb changes in temperature but also relatively short temperature transmission paths within the expandible operating material. These two aspects combined produce rapid reaction on changes in temperature.

By this means, an expandible element of small structure is obtained which is distinguished by its high work capacity in conjunction with uniform properties throughout its service life without hysteresis or stroke losses.

By means of the manufacturing process, the expandible element can be filled with expandible operating material safely and in costfavourable manner, and closed.

Claims

1. A thermally expandible element including a predetermined volume of a thermally expandible operating material arranged within a sealed housing comprising a rigid plate-like housing member to which is mounted at least one corrugated pipe such that changes in the volume of the operating material with variations in temperature are accommodated by corresponding changes in the dimensions of the corrugated pipe.

2. A thermally expandible element as claimed in claim 1, wherein the corrugated pipe is mounted to an end face of the housing member, and wherein the installed height of the housing member is low relative to the overall dimensions of the expandible element.

3. A thermally expandible element as claimed in claim 2, wherein the housing member consists of a bottom part and a cover, the cover having a continuation forming the corrugated pipe, and wherein the end faces of the cover and the bottom part are provided with indentations serving as reinforcing ribs.

4. A thermally expandible element as claimed in claim 3, wherein the housing member is axisymmetrical and the cover has a coaxial, cylindrical indentation which is connected at its end face to the bottom part, apertures being provided in the culindrical wall of the indentation for communication with the interior of the pipe.

5. A thermally expandible element as claimed in claim 4, wherein the bottom part and the cover are inseparably and leak-tight connected with each other by an outer flange and at the end face of the indentation, and wherein the corrugated pipe is inseparably and leak-tight connected to the cover at an inner flange concentrically with the identation.

6. A thermally expandible element as claimed in claim 2, wherein the housing member consists of two identical, dished parts on each of which there is an extension formed as a corrugated pipe, and wherein the two dished sections are inseparably connected with each other at circumferential flanges thereof.

7. A thermally expandible element as claimed in claim 6, wherein the dished parts are dished inwards at the end faces in a dome fashion.

8. A thermally expandible element as claimed in claim 6 or 7, wherein each dished part is formed of a single piece.

9. A thermally expandible element as claimed in any one of claims 5, 6, 7, or 8, wherein the individual components comprising the element are welded together.

1 0. A thermally expandible element as claimed in any one of claims 5, 6, 7, or 8, wherein the individual components comprising the element are connected together by flanging or similar means.

11. A thermally expandible element as claimed in any one of the preceding claims, wherein thermally expandible operating material is a fluorohydrocarbon which is not electrically conducting.

12. A method of manufacturing a ther mally expandible element as claimed in any one of the proceeding claims, including the step of connecting the individual components of the housing together in a leak-tight manner whilst immersed in a bath of the thermally expandible operating material which is in a liquid state.

1 3. A method as claimed in claim 1 2 as appendant to claim 5, wherein the end face of the cylindrical indentation on the cover is first welded to the bottom part followed by welding of the outer flange, wherein the partial housing thus produced is thereafter filled with liquid expandible operating material and then the corrugated pipe which is also filled with expandible operating material, is welded in a leak-tight manner to the partial housing at the inner flange whilst immersed in the bath of expandible operating material in the liquid state.

14. A method as claimed in claim 12 as appendant to claim 6, wherein the dished parts are produced from one plate bar by the deep drawing process, the extension which is produced in the centre by stretching is formed into the corrugated pipe, and wherein two such dished parts, filled with liquid expandible operating material, are welded in a leak-tight manner at the flanges thereof whilst immersed in the bath of liquid expandible operating material to form one sealed housing.

1 5. A method of manufacturing a thermally expandible element substantially as herein described with reference to Figs. 1 to 3 or Fig. 4 of the accompanying drawings.

1 6. A thermally expandible element made by a method as claimed in any one of claims 12, 13, 14 or

15.

17, A thermally expandible device comprising a plurality of thermally expandible elements as claimed in any one of claims 1 to 11 and 16 combined to form a column such that temperature-related deflections of the individual elements are sum mated.

1 8. A thermally expandible element substantially as herein described with reference to and as illustrated in Figs. 1 to 3 or Fig. 4 of the accompanying drawings.

1 9. A hot-and-cold-fluid mixing device in which the temperature of the mixed fluids is regulated by an element or device according to any preceding claim.