EP0709641A2 - Heat exchanger for vehicles and method for the assembly of a heat exchange matrix - Google Patents

Heat exchanger for vehicles and method for the assembly of a heat exchange matrix Download PDF

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Publication number
EP0709641A2
EP0709641A2 EP95117043A EP95117043A EP0709641A2 EP 0709641 A2 EP0709641 A2 EP 0709641A2 EP 95117043 A EP95117043 A EP 95117043A EP 95117043 A EP95117043 A EP 95117043A EP 0709641 A2 EP0709641 A2 EP 0709641A2
Authority
EP
European Patent Office
Prior art keywords
tube
fins
septum
tubes
transverse section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95117043A
Other languages
German (de)
French (fr)
Other versions
EP0709641A3 (en
Inventor
Maurizio Parrino
Vittorio Bassignana
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Denso Thermal Systems SpA
Original Assignee
Magneti Marelli Climatizzazione SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Magneti Marelli Climatizzazione SpA filed Critical Magneti Marelli Climatizzazione SpA
Publication of EP0709641A2 publication Critical patent/EP0709641A2/en
Publication of EP0709641A3 publication Critical patent/EP0709641A3/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
    • F28F1/24—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely
    • F28F1/32—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely the means having portions engaging further tubular elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D53/00—Making other particular articles
    • B21D53/02—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers
    • B21D53/08—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers of both metal tubes and sheet metal
    • B21D53/085—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers of both metal tubes and sheet metal with fins places on zig-zag tubes or parallel tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/02—Tubular elements of cross-section which is non-circular
    • F28F1/022—Tubular elements of cross-section which is non-circular with multiple channels

Definitions

  • the present invention concerns a heat exchanger for vehicles, in particular a condenser for air-conditioning units.
  • Heat exchangers for motor car use can be divided into two fundamental categories based on the technology used in their production. These categories are:
  • the aforesaid categories refer to the way in which the connection is made between the tubes through which the heat transfer liquid passes and the metal fins which give up heat to the cooling air flow.
  • Brazed condensers are generally formed from flat tubes folded in a serpentine configuration with corrugated or undulating fins fitted between each pair of adjacent branches of the tube.
  • the fins are fixed to the branches of the tube by a brazing process.
  • the heat exchange matrix is formed from a plurality of tubes and a stack of substantially flat fins.
  • the tubes are inserted in corresponding aligned holes in the fins and the tube-fin assembly is achieved by expansion of the tubes after they have been inserted with clearance into the holes in the fins.
  • the present invention specifically concerns heat exchangers of the mechanically assembled type and in particular heat exchangers intended to be used as condensers in vehicle air-conditioning units.
  • Condensers for use in motor vehicles are subject to conditions of use which are much more onerous than for example engine-cooling radiators or heat exchangers for heating the inside of the passenger compartment.
  • the condensers are subjected to pressures from the heat exchange liquid which can reach values in excess of 25 bar and temperatures in excess of 110°c.
  • Supply specifications generally require that the condenser should not suffer permanent distortion in any part from a pressure within the tubes of the order of 40 bar (test pressure), and the condenser should not split even at pressures equal to twice the test pressure (approximately 80 bar).
  • the object of the present invention is to make a heat exchanger intended to be used in particular as a condenser in a motor vehicle air-conditioning unit, using the mechanical assembly technique with tubes of oblong section.
  • the present invention also concerns a method for assembling a heat exchange matrix, the characteristics of which are the subject of Claims 2, 3 and 4.
  • the reference numeral 10 indicates in general a heat exchanger comprising a stack of substantially flat metal fins 12 with holes through which extend a plurality of tubes 14 of oblong, in this case oval, transverse section.
  • oblong transverse section means any non-circular transverse section with a major axis and a minor axis, including oval, ovoid and elliptic transverse sections and also flat sections with two parallel walls and two semi-circular connecting zones.
  • each tube 14 is made from a wall 16 and a stiffening longitudinal septum 18 which extends along the minor axis of the transverse section of the tube 14.
  • the tube 14 is formed by extrusion and is made from easily extrudible metal material, such as for example aluminium or copper.
  • the internal stiffening septum 18 is formed integrally with the wall 16 during the extrusion of the tube.
  • each tube 14 is inserted with slight clearance into a series of aligned holes 20 in the fins 12.
  • the fins 12 each have a collar 22 corresponding to each hole 20 which adheres, upon completion of the assembly, to the external surface of the wall of the tube.
  • the fixing of the tubes 14 to the fins 12 is achieved by causing the permanent deformation of the tube by expansion, so as to close up the clearances existing between the external surface of the tube and the internal surface of the collars 22 and causing an elastic deformation of the fins in the region of the holes 20.
  • the deformation of the tube is achieved by using a mandrel 24 which includes two symmetrical heads 26 carried on a rod 28 which are movable together in the direction indicated by the arrows 30 through the action of an actuator of conventional type (not shown). Each head is inserted in a respective channel of the tube 14 and exerts a deforming force F on the tube along the major axis of the transverse section of the tube 14 (see Figure 3).
  • the deforming force F is applied to the zones 32 of the tube 14 having the least radius of curvature and causes an expansion of the tube from the original shape illustrated by the broken line in Figure 3 to the final shape illustrated in the same Figure by the continuous line.
  • the deforming force F causes a reaction which is transferred to the stiffening septum 18. Given that the reaction forces produced by the two heads 26 are of equal magnitude and are opposing, the septum 18 and the zone of the tube with the greatest radius of curvature are substantially undeformed at the end of the expansion process.
  • the heads 26 have internal reaction surfaces 34 adapted for transferring the reaction forces so as to concentrate them on the connecting zones between the stiffening septum 18 and the walls 16 with the aim of reducing the sliding friction during the expansion phase.
  • a tube made according to the present invention is particularly suitable for the manufacture of condensers, in that it has a strong resistance to high internal pressures. This allows a free choice in the dimensions of the oval section tube in determining the dimensions of the heat exchanger. Due to the stiffening effect of the septum 18, it is possible, all other conditions being equal, to reduce the wall thickness of the tube and therefore reduce the weight. Consequently, due to the thinner tube walls, the expansion process is easier.
  • the fins had a structural function in the sense that they had to contribute to controlling the tendency of the tube to expand under the pressure of the fluid, with the structure according to the present invention it is possible to reduce the costs of the fins, as it is sufficient to use thinner materials with inferior mechanical properties.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Geometry (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

A heat exchanger for vehicles, in particular a condenser for air-conditioning units. The exchanger comprises a stack of substantially flat fins (12) and a plurality of tubes (14) fixed to the fins (12) by means of mechanical expansion. Each tube (14) has an oblong transverse section and a stiffening septum (18) which extends along the minor axis of the transverse section of the tube (14) and which is formed integrally with the wall of the tube (14).

Description

  • The present invention concerns a heat exchanger for vehicles, in particular a condenser for air-conditioning units.
  • Heat exchangers for motor car use can be divided into two fundamental categories based on the technology used in their production. These categories are:
    • brazed heat exchangers, and
    • expanded car mechanically eassembled heat exchangers.
  • The aforesaid categories refer to the way in which the connection is made between the tubes through which the heat transfer liquid passes and the metal fins which give up heat to the cooling air flow.
  • Brazed condensers are generally formed from flat tubes folded in a serpentine configuration with corrugated or undulating fins fitted between each pair of adjacent branches of the tube. The fins are fixed to the branches of the tube by a brazing process.
  • In expanded or mechanically assembled condensers the heat exchange matrix is formed from a plurality of tubes and a stack of substantially flat fins. The tubes are inserted in corresponding aligned holes in the fins and the tube-fin assembly is achieved by expansion of the tubes after they have been inserted with clearance into the holes in the fins.
  • The present invention specifically concerns heat exchangers of the mechanically assembled type and in particular heat exchangers intended to be used as condensers in vehicle air-conditioning units.
  • Condensers for use in motor vehicles are subject to conditions of use which are much more onerous than for example engine-cooling radiators or heat exchangers for heating the inside of the passenger compartment.
  • In particular, the condensers are subjected to pressures from the heat exchange liquid which can reach values in excess of 25 bar and temperatures in excess of 110°c. Supply specifications generally require that the condenser should not suffer permanent distortion in any part from a pressure within the tubes of the order of 40 bar (test pressure), and the condenser should not split even at pressures equal to twice the test pressure (approximately 80 bar).
  • Such onerous conditions of use impose many limits on the choice of the tube section, and in the general dimensions of the heat exchange matrix. In particular, it can be seen that it is very difficult to make mechanically assembled condensers using tubes with oblong section, which would enable a more efficient heat exchange to be obtained than tubes with circular section.
  • The object of the present invention is to make a heat exchanger intended to be used in particular as a condenser in a motor vehicle air-conditioning unit, using the mechanical assembly technique with tubes of oblong section.
  • According to the present invention, this is achieved by making a heat exchanger having the characteristics which form the subject of Claim 1.
  • The present invention also concerns a method for assembling a heat exchange matrix, the characteristics of which are the subject of Claims 2, 3 and 4.
  • Further characteristics and advantages of the present invention will become evident from the following detailed description, given by way of non-limitative example, with reference to the accompanying drawings, in which:
    • Figure 1 is a schematic perspective view of a heat exchanger according to the present invention;
    • Figure 2 is a schematic perspective view illustrating an expansion tool used in the method according to the invention, and;
    • Figure 3 is a schematic plan view in the direction of the arrow III of Figure 2.
  • Referring initially to Figure 1, the reference numeral 10 indicates in general a heat exchanger comprising a stack of substantially flat metal fins 12 with holes through which extend a plurality of tubes 14 of oblong, in this case oval, transverse section. In the following description and in the Claims, "oblong" transverse section means any non-circular transverse section with a major axis and a minor axis, including oval, ovoid and elliptic transverse sections and also flat sections with two parallel walls and two semi-circular connecting zones.
  • Referring to Figures 2 and 3, each tube 14 is made from a wall 16 and a stiffening longitudinal septum 18 which extends along the minor axis of the transverse section of the tube 14. The tube 14 is formed by extrusion and is made from easily extrudible metal material, such as for example aluminium or copper. The internal stiffening septum 18 is formed integrally with the wall 16 during the extrusion of the tube.
  • Each tube 14 is inserted with slight clearance into a series of aligned holes 20 in the fins 12. Preferably, the fins 12 each have a collar 22 corresponding to each hole 20 which adheres, upon completion of the assembly, to the external surface of the wall of the tube.
  • The fixing of the tubes 14 to the fins 12 is achieved by causing the permanent deformation of the tube by expansion, so as to close up the clearances existing between the external surface of the tube and the internal surface of the collars 22 and causing an elastic deformation of the fins in the region of the holes 20. The deformation of the tube is achieved by using a mandrel 24 which includes two symmetrical heads 26 carried on a rod 28 which are movable together in the direction indicated by the arrows 30 through the action of an actuator of conventional type (not shown). Each head is inserted in a respective channel of the tube 14 and exerts a deforming force F on the tube along the major axis of the transverse section of the tube 14 (see Figure 3).
  • The deforming force F is applied to the zones 32 of the tube 14 having the least radius of curvature and causes an expansion of the tube from the original shape illustrated by the broken line in Figure 3 to the final shape illustrated in the same Figure by the continuous line. The deforming force F causes a reaction which is transferred to the stiffening septum 18. Given that the reaction forces produced by the two heads 26 are of equal magnitude and are opposing, the septum 18 and the zone of the tube with the greatest radius of curvature are substantially undeformed at the end of the expansion process.
  • The heads 26 have internal reaction surfaces 34 adapted for transferring the reaction forces so as to concentrate them on the connecting zones between the stiffening septum 18 and the walls 16 with the aim of reducing the sliding friction during the expansion phase.
  • A tube made according to the present invention is particularly suitable for the manufacture of condensers, in that it has a strong resistance to high internal pressures. This allows a free choice in the dimensions of the oval section tube in determining the dimensions of the heat exchanger. Due to the stiffening effect of the septum 18, it is possible, all other conditions being equal, to reduce the wall thickness of the tube and therefore reduce the weight. Consequently, due to the thinner tube walls, the expansion process is easier.
  • Also, while in the conventional condensers the fins had a structural function in the sense that they had to contribute to controlling the tendency of the tube to expand under the pressure of the fluid, with the structure according to the present invention it is possible to reduce the costs of the fins, as it is sufficient to use thinner materials with inferior mechanical properties.

Claims (4)

  1. A heat exchanger for vehicles, in particular a condenser for air-conditioning units, comprising a stack of substantially flat fins (12) and a plurality of tubes (14) each of which is inserted into a series of aligned holes (20) in the fins (12), in which the assembly of tube (14) to fin (12) is achieved by expansion of the tubes (14) after they have been inserted with clearance into the holes (20) in the fins (12), wherein each tube (14) has on oblong transverse section and a longitudinal stiffening septum (18) which extends along the minor axis of the transverse section of the tube and is formed integrally with the wall (16) of the tube (14), characterised in that said expansion involves the whole cross-section of the tube (14) with the exception of the portion thereof adjacent the stiffening septum (18).
  2. A method for the assembly of a heat exchanger matrix including a stack of substantially flat fins (12) and a plurality of tubes (14) each of which is inserted into a series of aligned holes (20) in the fins (12) and fixed to the stack of fins (12) by mechanical expansion, characterised in that:
    - a plurality of tubes (14) with oblong transverse section is provided, each having a longitudinal stiffening septum (18) which extends along the minor axis of the transverse section of the tube and which is formed integrally with the wall (16) of the tube (14),
    - the tubes (14) are inserted with clearance into a series of aligned holes (20) in the fins (12), and
    - a plastic deforming force (F) is exerted on the tubes (14) which is concentrated along the major axis of the transverse section of each tube and applied between the stiffening septum (18) and the two zones (32) of the tube (14) with the least radius of curvature.
  3. A method according to Claim 2, characterised in that the plastic deforming force (F) on each tube (14) is applied by an expansion tool (24) having two symmetrical heads (26) which move together in respective channels of the tube (14) separated by the said septum (18).
  4. A method according to Claim 3, characterised in that each of the said heads (26) of the expansion tool (24) exerts a reaction force on the said septum (18) which is concentrated on the connecting zones between the said septum (18) and the wall (16) of the tube (14).
EP95117043A 1994-10-31 1995-10-30 Heat exchanger for vehicles and method for the assembly of a heat exchange matrix Withdrawn EP0709641A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT94TO000872A IT1267480B1 (en) 1994-10-31 1994-10-31 HEAT EXCHANGER FOR VEHICLES AND PROCEDURE FOR ASSEMBLY OF A HEAT EXCHANGER NETWORK.
ITTO940872 1994-10-31

Publications (2)

Publication Number Publication Date
EP0709641A2 true EP0709641A2 (en) 1996-05-01
EP0709641A3 EP0709641A3 (en) 1997-06-18

Family

ID=11412866

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95117043A Withdrawn EP0709641A3 (en) 1994-10-31 1995-10-30 Heat exchanger for vehicles and method for the assembly of a heat exchange matrix

Country Status (2)

Country Link
EP (1) EP0709641A3 (en)
IT (1) IT1267480B1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1561524A1 (en) * 2004-02-03 2005-08-10 Denso Corporation Jig for expanding opening of heat exchanger tube
EP2006038A2 (en) * 2006-04-13 2008-12-24 Showa Denko K.K. Method of joining members together
EP2312254A1 (en) * 2008-06-19 2011-04-20 Mitsubishi Electric Corporation Heat exchanger and air conditioner having the heat exchanger

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3603384A (en) * 1969-04-08 1971-09-07 Modine Mfg Co Expandable tube, and heat exchanger
FR2402850A1 (en) * 1977-09-09 1979-04-06 Ferodo Sa FINNED TUBE DEVICE FOR A HEAT EXCHANGER, IN PARTICULAR FOR A MOTOR VEHICLE RADIATOR, AND THE MANUFACTURING PROCESS
DE3432073A1 (en) * 1984-08-31 1986-03-06 Dirk Dipl.-Wirtsch.-Ing. 3500 Kassel Pietzcker HEAT EXCHANGER, ESPECIALLY FOR MOTOR VEHICLES, AND DEVICE AND METHOD FOR CONNECTING ITS PIPES AND LAMPS
US4570317A (en) * 1985-01-18 1986-02-18 Ford Motor Company Method of attaching a tube to a fin
JPS61268985A (en) * 1985-05-24 1986-11-28 Matsushita Refrig Co Heat exchanger
JPH02290666A (en) * 1989-02-21 1990-11-30 Toyo Radiator Co Ltd Manufacture of heat exchanger
DE3910357A1 (en) * 1989-03-30 1990-10-04 Autokuehler Gmbh & Co Kg GUIDE PLATE FOR A HEAT EXCHANGER AND A HEAT EXCHANGER MADE THEREOF
IT1250321B (en) * 1991-10-24 1995-04-07 Borletti Climatizzazione SYSTEM FOR FASTENING THROUGH COOLING FINS TO TUBES OF A HEAT EXCHANGER.
DE9315296U1 (en) * 1992-10-30 1994-03-03 Autokuehler Gmbh & Co Kg Heat exchangers, in particular air / air heat exchangers
DE4332768C2 (en) * 1993-09-25 2000-05-31 Behr Gmbh & Co Method and tool for expanding metal tubes with an oval cross-section

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1561524A1 (en) * 2004-02-03 2005-08-10 Denso Corporation Jig for expanding opening of heat exchanger tube
EP2006038A2 (en) * 2006-04-13 2008-12-24 Showa Denko K.K. Method of joining members together
EP2006038A4 (en) * 2006-04-13 2010-05-05 Showa Denko Kk Method of joining members together
US8266782B2 (en) 2006-04-13 2012-09-18 Showa Denko K.K. Method of joining members together
EP2312254A1 (en) * 2008-06-19 2011-04-20 Mitsubishi Electric Corporation Heat exchanger and air conditioner having the heat exchanger
US20110094258A1 (en) * 2008-06-19 2011-04-28 Mitsubishi Electric Corporation Heat exchanger and air conditioner provided with heat exchanger
EP2312254A4 (en) * 2008-06-19 2014-04-02 Mitsubishi Electric Corp Heat exchanger and air conditioner having the heat exchanger
US9322602B2 (en) 2008-06-19 2016-04-26 Mitsubishi Electric Corporation Heat exchanger having a plurality of plate-like fins and a plurality of flat-shaped heat transfer pipes orthogonal to the plate-like fins

Also Published As

Publication number Publication date
ITTO940872A1 (en) 1996-05-01
EP0709641A3 (en) 1997-06-18
ITTO940872A0 (en) 1994-10-31
IT1267480B1 (en) 1997-02-05

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