GB2383118A

GB2383118A - Automotive heat exchanger

Info

Publication number: GB2383118A
Application number: GB0129766A
Authority: GB
Inventors: Adrian Lionel Frost
Original assignee: Llanelli Radiators Ltd
Current assignee: Marelli Automotive Systems UK Ltd
Priority date: 2001-12-13
Filing date: 2001-12-13
Publication date: 2003-06-18
Anticipated expiration: 2021-12-13
Also published as: GB2383118B; GB0129766D0

Abstract

An automotive heat exchanger comprises cooling tubes 3 which terminate in a header tank 2 constructed of two parts 2a and 2b, and a liquid tank or receiver (7) which is attached to the header tank 2 by means of an end part (9) having collar parts 16 which are clenched around header tank 2 prior to brazing. The heat exchanger may be a condenser for automotive air conditioning and may include a sub-cool region. Tank (7) and header 2 may communicate, to allow fluid flow, via ports defined by sleeves 5 and 6 which may be accommodated within a second end part 8.

Description

Automotive Heat Exchanger The present invention relates to an automotive heat exchanger and in particular to a heat exchanger comprising a header tank and a separate adjacent liquid tank conjoined with header tank (such as a liquid tank conjoined with automotive air conditioning system condenser).

According to the present invention there is provided an automotive heat exchanger comprising a header tank and a separate adjacent liquid tank conjoined with the header tank and in fluid communication therewith, the liquid tank comprising a body portion and at least one end element fitted to an end of the body portion, the end element including a transversely projecting fitment clench formed to mate with the outer profile of the header tank.

Typically the fitment comprises a collar portion, preferably having spaced arms arranged to approach with and accept therebetween external opposed portions of the header tank. The arms are then clenched to mate with the outer profile of the header tank.

Clenching of the fitment to mate with the external profile of the header tank provides a self clamped integrated liquid tank for the condenser or other heat exchanger. Typically the end element is of extruded construction. The body portion of the liquid tank is typically of material clad with a lower melting point fusable material. Use of

aluminium components is prevalent in the automotive industry particularly for manufacture of heat exchangers such as condensers. The present invention provides that the liquid tank body portion may be of conventional construction comprising a core aluminium alloy material clad with brazing alloy material, the end element only being of extruded or impact forged construction. By making the liquid tank body of plural part construction the material used can be optimised and weight savings made. The use of an extrusion for the whole liquid tank body would result in a greater amount of heat being required during brazing in the brazing furnace and the potentially larger mass would increase the risk of producing poor brazed "cold-joints". Use of a non extruded liquid tank body portion (for example seam welded brazing alloy clad tube) means that the brazing alloy cladding can produce a good and efficient brazed connection between the liquid tank body portion and the header tank.

Other prior art alternatives involve the use of TIG welding to tack weld components via jigging prior to furnace brazing. This technique is manually controlled and therefore not consistent, resulting in defective brazing and misalignment of components in certain conditions. The present invention alleviates this. Other prior art techniques rely on tightly tolerance mating parts during the pre-braze assembly. Tolerances required for assembly and manufacture of the heat exchanger according to the present invention are sufficiently liberal to avoid this problem.

It is preferred that the header tank and liquid tank extend longitudinally in side by side relationship. The body portion and also preferably the end element comprises respective tubular components arranged substantially coaxially with one another. The end element may be closed with terminal sealing cap.

The end element and the adjacent portion of the header tank are preferably provided with one or more respective substantially aligned apertures permitting fluid communication between the header tank and the adjacent liquid tank. Particularly for condensers, the arrangement includes a "sub cool" portion in the region of the end element and the adjacent liquid tank portion. In this"sub cool"portion the interior of the header tank preferably includes a dividing element and liquid coolant communication passes through the header tank wall and the wall of the liquid tank in the region of the transverse projecting fitment of the end element, one communication pass being provided on either side of the dividing element. For condensers this ensures that the final pass through the condenser (downstream of dividing element) contains solely liquid refrigerant. This general arrangement is known in prior art condenser technology.

The respective of aligned apertures in the header tank and the adjacent liquid tank locate respective sleeves defining fluid communication conduits between the header tank and the adjacent liquid tank. The respective fluid communication apertures through the wall of the end element

preferably include a large diameter bore portion and a smaller diameter bore portion with a step or shoulder between the two. The step or shoulder serves to aid in accurately locating the relevant sleeve defining the fluid communication passage.

The end element preferably includes an axial bore having a stepped profile including a first bore length to accommodate an end length of the body portion and second bore length of a size smaller than the bore of the first length bore portion. The bore of the liquid tank body is sufficiently large to accommodate the insertion during assembly of a dessicant sack or other dessicant device.

The end of the liquid tank body is received within the larger diameter bore portion of the end element and abuts the step in the internal profile of the end element. The remainder of the internal bore of the end element may be smaller in size than the bore of the liquid tank body portion.

The header tank preferably includes an external profile having a step or shoulder, the collar portion of the transversely projecting fitment of the end element of the liquid tank being formed or clenched to mate around the step or shoulder of the external profile of the header tank.

A second end element is preferably fitted to the opposed end of the body portion of the liquid tank. The second element also includes a transversely projecting fitment

clench formed to mate about the outer profile of the header tank.

The header tank is preferably of two part construction and comprises a first tube plate shell element and a second shell element mating therewith about a common brazing seam line extending about the header tank. The sides of the shell elements preferably overlap to form a step or shoulder in the external profile of the header tank.

According to a second aspect, the invention provides an automotive heat exchanger (particularly a condenser) comprising a header tank and a separate adjacent liquid tank conjoined with the header tank and in fluid communication therewith, the liquid tank comprising a body portion of aluminium material clad with brazing alloy and at least one end element of extruded or forged aluminium construction, the end element including a transversely projecting fitment being clenched or formed to mate with the outer profile of the header tank.

According to a further aspect, the invention provides a method of manufacturing an automotive heat exchanger (particularly a condenser) the method comprising: assembling heat exchange components including; (a) a header tank arrangement; and (b) a liquid tank arranged adjacent the header tank, the liquid tank assembly including fitting at least one end element to a body portion of the liquid tank and clenching a transversely

projecting fitment of the end element about the external profile of the header tank arrangement; and bonding the assembly in a fusion bonding process.

The invention will now be further described in specific embodiments by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic side view of a heat exchanger (a condenser) in accordance with the invention; Figure 2 is a schematic plan view of a header tank of the heat exchanger of Figure 1; Figure 3 is a schematic plan view of a header tank and adjacent liquid tank prior to clenching of the transverse fitment to the header tank; Figure 4 is a view similar to Figure 3 of the arrangement subsequent to clenching or deformation of the transverse fitment; Figure 5 is a plan view of an alternative arrangement of a header tank and liquid tank prior to clenching of the transverse fitment.

Referring to the drawings and specifically to Figure 1, an automotive condenser 101 for a vehicle air conditioning system is generally of brazed aluminium construction and

comprises first a second header tanks 1,2 and extending therebetween a plurality of parallel, spaced condenser tubes 3 in a conventional manner. Mounted adjacent header tank 2 is a liquid tank 4 which is in fluid communication with header tank 2 via sub cool entry/exit sleeves 5,6 as will be explained in detail hereafter.

The liquid tank 4 comprises a tubular body portion 7 of seam welded aluminium tube clad with brazing alloy.

Respective sub cool end piece 8 and sealing end piece 9 are fitted to opposed ends of the tubular body portion 7.

Sub cool end piece 8 comprises an extruded aluminium body having a central bore 10 which is closed with an end cap 11. The lower terminal portion of the liquid tank tubular body portion 7 is received within a larger diameter bore portion of sub cool end piece 8, and abuts against a shoulder 12 at a step to a narrower bore portion of sub cool end piece 8.

The header tank 2 is of plural part construction comprising a tube plate shell 2a and an arcuate shell 2b. Both tube plate shell 2a and arcuate shell 2b are of aluminium core material clad with brazing alloy. Shells 2a and 2b mate and overlap to form a bonded seam when brazed. The marginal portions of arcuate shell 2b are received within the marginal portions of tube plate shell 2a. Tube plate shell 2a is formed with a shoulder 13 standing proud at the external surface to accommodate the respective tubes 3 and provide the required degree of overlap at its marginal portion with the internally received arcuate shell portion 2b.

Sub cool end piece 8 includes a transversely projecting fitment 15 shaped and dimensioned to abut the near-side external profile of header shell 2b and extend past the overlapping terminal ends of tube plate element 2a of the header tank 2.

As shown in Figure 3 a collar portion of the fitment 15 includes transversely extending arms-16 one on either-side of the header tank 2. These are initially formed to allow the sub cool end piece 8 to be brought into approachment with the header tank 2 which is received therein without being secured thereto.

Subsequently in a clenching operation the terminal portions of arms 16 are deformed relatively towards one another about shoulder 13 to matingly or clenchingly engage the sub cool end collar 8 with header tank 2 (the condition shown in Figure 4).

The sub cool entry/exit sleeves 5,6 are received in bores provided through the wall of header tank shell 2b and sub cool end piece 8. The bore through sub cool end piece 8 comprises a large diameter bore communicating through the header tank shell 2b and small diameter bore communicating to the interior of the sub cool end collar main bore 10. The step/shoulder between the large and small bores ensures accurate secure fitment of the liquid communication sleeves between the header tank 2 and the internal bore 10 of the sub cool end piece 8.

The sealing end piece 9 includes an internal bore fitted to the opposed end of the liquid tank body portion 7. This can be formed as an extrusion in a similar manner to the sub cool end piece 8. End piece 9 is closed by a removable sealing cap (not shown), the cap being retained by a'C' clip. Removability of the cap allows servicing of the desiccant assembly in the tank body portion 7. In either embodiment the sealing end portion 9 includes a transversely projecting fitment corresponding to fitment 15 including the clenching arms 16. During assembly one end of the extruded sub cool end piece 8 is pressed onto the liquid tank body portion. The sealing end piece 9 is then pressed onto the other end of the liquid tank body portion.

These operations are typically carried out via a jig assembly to ensure accurate alignment of lower and upper components 8,9. The sub assembly comprising the liquid tank body and now fitted end portions 8,9 are then approached to the header tank 2 such that the external header tank shell 2b is accepted by the respective projecting fitment 15 of end pieces 8,9 respectively. Arms 16 of the respective fitments 15 of end pieces 8,9 are then deformed around respective shoulders 13 to effectively hold the liquid tank assembly securely to the header tank ready for brazing.

The present invention provides advantages in terms of ease of assembly and sub assembly of components ready for brazing. A high degree of efficiency in use of materials is enabled in that the mass of extruded components is minimised and the main body of the liquid tank 7 can

comprise non extruded or forced components such as seam welded aluminium tubes, which is particularly advantageous when brazing alloy clad. This has the added benefit of ensuring good brazing efficiency.

Claims

CLAIMS: 1. An automotive heat exchanger comprising a header tank and a separate adjacent liquid tank conjoined with the header tank and in fluid communication therewith, the liquid tank comprising a body portion and at least one end element fitted to an end of the body portion, the end element including a transversely projecting fitment clench formed about the outer profile of the header tank.
2. A heat exchanger according to claim 1, wherein the heat exchanger comprises a condenser for an automotive air conditioning system.
3. A heat exchanger according to claim 1 or claim 2, wherein the header tank and liquid tank extend longitudinally in side by side relationship.
4. A heat exchanger according to any preceding claim, wherein the body portion comprises a tubular element.
5. A heat exchanger according to any preceding claim, wherein the end element comprises a tubular element arranged substantially coaxially with the body portion.
6. A heat exchanger according to any preceding claim, wherein the end element is closed with a terminal sealing cap.

<Desc/Clms Page number 12>
7. A heat exchanger according to any preceding claim, wherein the end element and the adjacent portion of the header tank are provided with one or more respective substantially aligned apertures permitting fluid communication between the header tank and the adjacent liquid tank.
8. A heat exchanger according to claim 7, wherein the respective aligned apertures locate respective sleeves defining fluid communication conduits between the header tank and the adjacent liquid tank.
9. A heat exchanger according to claim 8, wherein respective fluid communication aperture through the wall of the end element includes a larger diameter bore portion and a smaller diameter bore portion with a step/shoulder between the two.
10. A heat exchanger according to any preceding claim, wherein the end element includes a bore having a stepped profile including a first bore length to accommodate an end length of the body portion and a second bore length of a bore size smaller than the bore of the first bore length.
11. A heat exchanger according to any preceding claim, wherein the transversely projecting fitment of the end element of the liquid tank includes a collar portion (preferably housing spaced arms) clenched about the external profile of the header tank.

<Desc/Clms Page number 13>
12. A heat exchanger according to any preceding claim, wherein the header tank includes an external profile having a step or shoulder, the transversely projecting fitment of the end element being formed to clench mate about the step or shoulder.
13. A heat exchanger according to any preceding claim, wherein the liquid tank comprises a second end element fitted to the opposed end of the body portion, the second end element also including a transversely projecting fitment formed to mate with the outer profile of the header tank.
14. A heat exchanger according to claim 13, wherein the transversely projecting fitment includes a collar portion (preferably being spaced arms) formed to mate with the outer profile of the header tank.
15. A heat exchanger according to any preceding claim, wherein the first and/or second end elements comprise aluminium extruded components, the header tank being of aluminium construction (preferably non-extended aluminium construction).
16. A heat exchanger according to any preceding claim, wherein the header tank is of two part construction comprising a first tube plate shell element and a second shell element mating therewith about a common brazing seam line extending substantially about the entire header tank, a step or shoulder being formed in the external profile of the header tank.

<Desc/Clms Page number 14>
17. A heat exchanger according to any preceding claim, comprising a condenser for a vehicle automotive cooling system, the condenser header including a sub cool portion in the region of the first end piece of the adjacent liquid tank; the interior of the header tank including a dividing element and communication passes being provided through the header tank wall and the wall of the liquid tank in the region of the transverse projecting fitment, a communication pass positional on either side of the dividing element.
18. A method of manufacturing an automotive heat exchanger including: (a) assembly of heat exchanger components including: (i) a header tank arrangement; and (ii) a liquid tank arranged adjacent the header tank, the assembly including fitting at least one end element to a body portion of the liquid tank and clenching a collar portion of a transversely projecting fitment of the end element about the external profile of the header tank arrangement; (b) bonding the assembly in a fusion bonding process.

\'"