AU746931B2

AU746931B2 - Heat exchanger

Info

Publication number: AU746931B2
Application number: AU65942/98A
Authority: AU
Inventors: Willy Loffler
Original assignee: Guentner Hans GmbH
Current assignee: HANS GUNTNER GmbH
Priority date: 1996-07-31
Filing date: 1998-05-14
Publication date: 2002-05-09
Anticipated expiration: 2018-05-14
Also published as: AU6594298A

Description

F/UU11 2815/91 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: S S S S S. S 55 S S

S

*SS*

Invention Title: HEAT EXCHANGER The following statement is a full description of this invention, including the best method of performing it known to us Hans Giintner GmbH Industriestrasse 14 D-82256 Fiirstenfeldbruck HEAT EXCHANGER FIELD OF THE INVENTION This invention relates to heat exchanging apparatus.

BACKGROUND OF THE INVENTION In assembling a heat exchanger unit, the tubes which extend through heat dissipating fins are often secured within their fins by drawing a tool down the tube to expand it slightly to fit snugly against the periphery of the opening in the fins.

Normally, end walls are located at each end of the fins to provide rigidity, and the tubes 20 are similarly expanded to grip the openings through the end walls.

A problem associated with this method is that the tool which is drawn down the tubes to expand it, requires lubrication and whatever oils are used for this lubrication need to be cleaned out of the tube prior to use. Particularly with the current use of more environmentally friendly refrigerants, the contamination of the refrigerant by the lubrication oils is a problem, and thorough cleaning is required.

Also, with the vibration inherent in the use of a compressor, as well as thermal expansion and contraction of the tubes, the tubes tend to wear at their gripping positions in the end walls, since the end walls are used as the mounting positions for the heat exchanger unit.

OBJECT OF THE INVENTION It is an object of this invention to provide a method and apparatus for at least alleviating the abovementioned difficulties.

SUMMARY OF THE INVENTION In accordance with this invention there is provided a method of assembling a heat exchanger having spaced apart end walls with tubes extending between and through the end walls, comprising locating rigid support tubes through closely fitting holes in the end walls, at positions which substantially maintain the rigidity of the end walls and tubes, and securing the tubes at least at their end wall positions.

Preferably the support tubes are steel tubes secured by spring clips over the ends which protrude from the end walls with the end walls spaced from each other by the thickness of fin plate mountings of fins operatively located between the end walls with the tubes extending therethrough.

Preferably the remainder of the heat exchanger tubes pass through end wall openings 15 with a gap around them, and the remainder of the tubes are held in position relative to each other by their securement in heat exchange relationship in holes through successive *.0 fin plates between end walls.

Preferably the remainder of the tubes are copper.

The invention extends to heat exchanger apparatus comprising a plurality of first tubes located tightly through openings in spaced apart fin plates, a pair of end walls, one at each end of the first tubes with the first tubes passing through openings in the end walls and second rigid tubes extending through the fin plates and extending through and being secured relative to, closely fitting openings in the end walls, the second tubes being located at support positions through the end walls which substantially rigidify the apparatus.

Preferably the first tubes pass through end wall openings with a gap around the tubes.

In accordance with another aspect of the invention there is provided a method of expanding copper tubing in a heat exchanger to grip within an opening of a fin or end wall, comprising drawing a tool down the length of the interior of the tube to expand the tube, with at least a ceramic bearing surface on the tool.

BRIEF DESCRIPTION OF THE DRAWING Embodiments of the invention are described below by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a heat exchanger according to the invention; Figure 2 is an end view of a wall plate of the embodiment of Figure 1; and Figure 3 is a cross-sectional side view illustrating the expansion of a copper tube to fit openings through stacked heat exchange fins.

DETAILES DESCRIPTION OF THE DRAWINGS WITH REFERENCE TO THE DRAWING Referring to Figures 1 and 2, a heat exchange unit has sheet metal end walls at 'each end of a stack of heat exchange fins having aligned openings therethrough fitted with heat exchange tubes The openings in the fins are punched out leaving a drawn annular flange which serves to space the fins apart from each other. The openings in the end walls at three positions are smaller than the remainder of the S" openings The positions are selected to be located around the periphery of the end wall in order to provide spaced apart rigid securing points for the tubes going therethrough. In this case, there are three such positions, one in each comer of one side, and the other on the opposite side in the middle.

In use, steel tubes (10) are located through the narrower openings to be a close fit through the end walls, but which provide a normal fit through the fins The remainder of the tubes are copper tubes which are fitted through the openings to leave an annular gap or tolerance therearound. The copper tubes (11) fit in a neat sliding fit through the fins as is known in the art per se.

The end walls are located relative to the closely fitting steel tubes (10) by means of spring retaining washers (12) over the tube ends which protrude from the end walls. The spring washers serve to push the end walls together and hold the structure tight. The copper tubes in this position are located without bearing on any of the peripheries of their end wall openings, and the normal drawing process enables the copper tubes to be exchanged into a tight heat exchange fit with the peripheries of the fin openings that they pass through.

It is considered that the invention provides a heat exchange apparatus and a method of constructing it, which will have rigidity without the consequent wear and tear on the tubes at the end wall positions, and which is relatively easily performed.

Variations may be made to the above embodiment without departing from the scope of the invention. For example, any suitable means of securing the steel tubes to the end walls may be used. The tube may be expanded to grip the end walls in some way, or other mechanical fixing means may be used. The tubes may be treated in whatever way is required to enable subsequent connection ofjoints, either internally or externally.

In this connection, the following fiUrther embodiments of the heat exchanger apparatus 15 according to the subject invention are advantgeous.

The heat exchanger apparatus can be provided with special support tubes having the same function as the support tubes (10) but being arranged between the heat exchange tubes such that they promote the heat exchange function of these heat exchange S 20 tubes.

Moreover, the support tubes can be provided at their ends with releasable fastening means in order to facilitate dismantling of the apparatus for cleaning or maintenance purposes.

According to a further embodiment of the subject invention and to substantially increase the rigidity of the apparatus the support tubes are not only secured to the end walls but also to further walls distantly arranged between said end walls and parallel thereto within the apparatus.

Moreover, the outer surface of the support tubes may be provided with a special profile promoting the heat exchange of the fluid contacting said surface.

Furthermore, the support tubes can be at least partly solid in a rod-like manner.

Finally, each of the two end walls of the apparatus can be comprised of two parallel walls forming an inside wall and an outside wall wherein the steel tubes are fixed to the outside walls only. Figure 1 shows on the left, part of this structure of the apparatus Referring to Figure 3, a copper tube (20) is shown passing through three fins (21) having annular flanges (22) around their aligned and punched openings A tool in the form of an oval ball (24) is connected to a rod (25) which is drawn through the tube to expand the tube to grip the peripheries of the opening in known manner. The ball however has a ceramic bearing surface (25) which bears upon the inside of the copper tube.

The ceramic bearing surface obviates the necessity for any lubricant, and the consequent use of any lubricant, and thus also the necessity for any subsequent cleaning.

The tool may be partially or of solid ceramic material.

15 It is considered that this aspect of the invention provides a useful and effective method of expanding copper tubing in this application without using lubricants.

Claims

1. A method of assembling a fin-and-tube type heat exchanger, including the steps of: providing a structure including spaced apart end walls and a number of substantially parallel fin plates arranged therebetween; providing a number of heat exchange tubes, each heat exchange tube running between and through the end walls and fin plates, via openings in each of said end walls and said fin plates; wherein the openings associated with the fin plates are sufficiently tight so as to provide a heat exchange relationship between each fin plate and each heat exchange tube; and wherein the fin plates support .i each heat exchange tube; providing a number of rigid support tubes, each support tube running between and through the end walls and fin plates, via openings in each of said end walls and said fin plates; wherein the support tubes run substantially parallel with the heat exchange tubes; wherein the openings associated with the end walls are closely fitting around each support tube; wherein each support tube is positioned such as provide rigidity to the structure; securing each support tube at the end walls; and arranging the support tubes running between the heat exchange tubes in order to promote heat exchange to or from the heat exchange tubes.

2. A method according to claim 1, wherein the support tubes are composed of steel.

3. A method according to claim 1 or 2, wherein the support tubes are secured at their end wall positions with releasable fastening means.

4. A method according to claim 3, wherein the releasable fastening means are spring clips which are arranged over the ends of the support tubes that protrude from the end walls. A method according to any one of the preceding claims, wherein the support tubes are at least partially solid.

6. A method according to any one of the preceding claims, wherein the distance between the end walls is defined by the thickness of the mountings of the fin plates located between the end walls.

7. A method according to any one of the preceding claims, wherein the openings in the end walls, associated with a number of the heat exchange tubes, are each of such a size as to allow a gap around its associated heat exchange tube; and wherein each associated heat exchange tube is supported in such a position by the fin plates.

8. A method according to any one of the preceding claims, wherein the heat exchange tubes are composed of copper.

9. A method according to any one of the preceding claims, wherein the support tubes each have a profile which promotes heat exchange to or from the heat exchange tubes. A method according to any one of the preceding claims, wherein each end wall consists of two parallel walls.

11. A method according to claim 10, wherein the support tubes are secured to each of said two parallel walls.

12. A method according to claim 10, wherein the support tubes are secured to the outer wall only.

13. A fin-and-tube type heat exchanger, including: a structure including spaced apart end walls and a number of substantially parallel fin plates arranged therebetween; a number of heat exchange tubes, each heat exchange tube arranged between and through the end walls and fin plates, via openings in each of said end walls and said fin plates; wherein the openings associated with the fin plates are sufficiently tight so as to provide a heat exchange relationship between each fin plate and each heat exchange tube; and wherein the fin plates support each heat exchange tube; a number of rigid support tubes, each support tube arranged between and through the end walls and fin plates, via openings in each of said end walls and said fin plates; wherein the support tubes are arranged substantially parallel with the heat exchange tubes; wherein the openings associated with the end walls are closely fitting around each support tube; wherein each support tube is positioned such as provide rigidity to the structure; wherein the support tubes are secured at the end walls; and wherein the support tubes are arranged between the heat exchange tubes in order to promote heat exchange to or from the heat exchange tubes.

14. A fin-and-tube type heat exchanger according to claim 13, wherein the support tubes are composed of steel. A fin-and-tube type heat exchanger according to claim 13 or 14, wherein the support tubes are secured at their end wall positions with releasable fastening means.

16. A fin-and-tube type heat exchanger according to claim 15, wherein the releasable fastening means are spring clips which are arranged over the ends of the support tubes that protruded from the end walls.

17. A fin-and-tube type heat exchanger according to any one of claims 13 to 16, wherein the support tubes are at least partially solid.

18. A fin-and-tube type heat exchanger according to any one of claims 13 to 17, wherein the distance between the end walls is defined by the thickness of the mountings of the fin plates located between the end walls.

19. A fin-and-tube type heat exchanger according to any one of claims 13 to 18, wherein the openings in the end walls, associated with a number of the heat exchange tubes, are each of such a size as to allow a gap around its associated heat exchange tube; and wherein each associated heat exchange tube is supported in such a position by the fin plates. A fin-and-tube type heat exchanger according to any one of claims 13 to 19, wherein the heat exchange tubes are composed of copper.

21. A fin-and-tube type heat exchanger according to any one of claims 13 to wherein the support tubes each have a profile which promotes heat exchange to or from the heat exchange tubes.

22. A fin-and-tube type heat exchanger according to any one of claims 13 to 21, wherein each end wall consists of two parallel walls, which improves the rigidity of the structure.

23. A fin-and-tube type heat exchanger according to claim 22, wherein the support tubes are secured to each of said two parallel walls.

24. A fin-and-tube type heat exchanger according to claim 22, wherein the support tubes are secured to the outer wall only. DATED this 25th day of February 2002 HANS GUNTNER GMBH WATERMARK PATENT TRADE MARK ATTORNEYS UNIT 1 THE VILLAGE RIVERSIDE CORPORATE PARK

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