# US 5,704,423 A · Flat tube for heat exchanger > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,704,423 A - Document ID: US5704423A - Status: Granted - Kind: A - Application number: 08/793,245 - Filed: 1997-02-21 - Granted: 1998-01-06 - Earliest claimed: 1995-06-22 - Assignees: Valeo Thermique Moteur - Inventors: Frederic Letrange - Web page: https://patentgrep.com/patent/US5704423A ## CPC - F28D 1/0308: {the conduits being formed by paired plates touching each other (F28D1/0358 takes precedence)} - B21C 37/151: {Making tubes with multiple passages} - F28F 1/022: {with multiple channels} - Y10S 165/906: Reinforcement - Y10T 29/49391: Tube making or reforming - F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general) - B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL - F28F: DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION (water and air traps, air venting F16) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A flat tube for a heat exchanger is disclosed. The flat tube is produced by assembling a main part made of a folded metal strip defining a flat side, two rounded ends and two side portions with two free edges, as well as a secondary part made of a metal strip forming a central portion with two flanged free edges, whereby the secondary part is sandwiched into the main part to form a multichannel tube. The tube may be used in heat exchangers for motor vehicle heating and/or air conditioning systems. ## Claims ### Claim 1 A flat tube for a heat exchanger having two opposed flat sides joined together by two rounded sides and by at least two longitudinal internal partitions to define flow ducts, the tube comprising: a main piece formed from a bent metal strip and constituting a first flat side, the two rounded sides and two lateral segments connected respectively to the two rounded sides in order partially to form the second flat side, the two lateral segments ending respectively at two free edges which are distant from one another and bent toward the first flat side; and a secondary piece formed from a metal strip and constituting a central segment capable partially of forming the second flat side, the central segment ending at two free edges bent on the same side of the said central segment in such a way that the two free edges of the central segment can press against the free edges of the lateral segments to hold the secondary piece sandwiched in the main piece, and that the central segment and the two lateral segments together form the second flat side of the tube. ### Claim 2 (depends on 1) A flat tube according to claim 1, wherein each of the free edges of the main piece is bent at right angles with respect to the corresponding lateral segment and stops some distance from the first flat side leaving a gap of given size. ### Claim 3 (depends on 2) A flat tube according to claim 2, wherein each of the free edges of the secondary piece is bent at right angles with respect to the central segment and ends in a lip which is practically parallel to the central segment and which can be inserted into the gap in the main piece. ### Claim 4 (depends on 2) A flat tube according to claim 2, wherein the size of the gap is substantially equal to the thickness of the metal strip of which the secondary piece is formed. ### Claim 5 (depends on 1) A flat tube according to claim 1, wherein the main piece and the secondary piece are obtained by successive rolling operations. ### Claim 6 (depends on 1) A flat tube according to claim 1, wherein the metal strip of which the main piece is formed is equipped with a plaque of brazing metal on one of its faces which extends outward. ### Claim 7 (depends on 1) A flat tube according to claim 1, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces. ### Claim 8 (depends on 3) A flat tube according to claim 3, wherein the size of the gap is substantially equal to the thickness of the metal strip of which the secondary piece is formed. ### Claim 9 (depends on 2) A flat tube according to claim 2, wherein the main piece and the secondary piece are obtained by successive rolling operations. ### Claim 10 (depends on 3) A flat tube according to claim 3, wherein the main piece and the secondary piece are obtained by successive rolling operations. ### Claim 11 (depends on 4) A flat tube according to claim 4, wherein the main piece and the secondary piece are obtained by successive rolling operations. ### Claim 12 (depends on 2) A flat tube according to claim 2, wherein the metal strip of which the main piece is formed is equipped with a plaque of brazing metal on one of its faces which extends outward. ### Claim 13 (depends on 3) A flat tube according to claim 3, wherein the metal strip of which the main piece is formed is equipped with a plaque of brazing metal on one of its faces which extends outward. ### Claim 14 (depends on 4) A flat tube according to claim 4, wherein the metal strip of which the main piece is formed is equipped with a plaque of brazing metal on one of its faces which extends outward. ### Claim 15 (depends on 5) A flat tube according to claim 5, wherein the metal strip of which the main piece is formed is equipped with a plaque of brazing metal on one of its faces which extends outward. ### Claim 16 (depends on 2) A flat tube according to claim 2, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces. ### Claim 17 (depends on 3) A flat tube according to claim 3, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces. ### Claim 18 (depends on 4) A flat tube according to claim 4, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces. ### Claim 19 (depends on 5) A flat tube according to claim 5, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces. ### Claim 20 (depends on 6) A flat tube according to claim 6, wherein the metal strip of which the secondary piece is formed is equipped with a plaque of brazing metal on both of its faces.