Core unit of heat exchanger having electric heater

• US 6,178,292 B1
• Filed: 12/13/1999
• Issued: 01/23/2001
• Est. Priority Date: 02/06/1997
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sato, Hiroyuki, Ohara, Toshio, Nakamura, Mitsugu, Fukuoka, Mikio, Naruse, Shinji, Yamamoto, Michiyasu, Kuroyanagi, Isao, Kamiya, Sadayuki, Aki, Yoshifumi
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): CAMPBELL, THOR S
• Application Number:
  US09/459,867
• Time in Patent Office: 407 Days
• Field of Search: 165/153, 165/152, 165/177, 165/175, 165/181, 219/630, 219/208, 392/377, 392/465, 392/485
• US Class Current: 392/485
• CPC Class Codes: F24H 1/009 for vehicle systems
• CPC Class Codes: F24H 3/0405 using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between F24H3/06, F24H3/08, F24H3/10 take precedence
• CPC Class Codes: F24H 3/0429 For vehicles
• CPC Class Codes: F24H 3/0435 Structures comprising heat spreading elements in the form of fins
• CPC Class Codes: F24H 3/0441 Interfaces between the electrodes of a resistive heating element and the power supply means
• CPC Class Codes: F24H 3/0452 Frame constructions
• CPC Class Codes: F24H 3/047 Multiple-piece frames assembled on their four or more edges
• CPC Class Codes: F24H 3/0476 Means for putting the electric heaters in the frame under strain, e.g. with springs
• CPC Class Codes: F24H 3/082 The tubes being an electrical isolator containing the heater
• CPC Class Codes: F24H 3/085 The tubes containing an electrically heated intermediate fluid, e.g. water
• CPC Class Codes: F24H 9/1872 PTC
• CPC Class Codes: F28D 2021/0096 for space heating for air-conditioning in vehicles B60H1/00321
• CPC Class Codes: F28F 9/002 with fastening means for other structures

Abstract

A core unit of a heat exchanger is composed of a plurality of parallel flat tubes, a plurality of corrugated fins, a support member disposed between two of the corrugated fins and an electric heater disposed inside the support member. The support member has a pair of parallel plates bonded to the corrugated fins at the summits of corrugation of the corrugated fins. The electric heater is composed of a heating element and an insulation member inserted between the heating element and the parallel plates.

Claims

1. A core unit of a heat exchanger including an inlet tank and an outlet tank for a heat carrier, said core comprising:

a plurality of corrugated fins disposed in parallel with each other;

a plurality of parallel flat tubes each of which is disposed in contact with first adjacent corrugated fins and connected to said inlet and outlet tanks to conduct said heat carrier; and

a heater support member in contact with second adjacent corrugated fins in parallel with said plurality of flat tubes, said heater support member including a pair of plates parallelly extending along said flat tubes and an electric heater held between said pair of plates to generate heat when said heater is energized, thereby heating air flowing through said second adjacent corrugated fins, said electric heater being electrically insulated from said plurality of fins.

2. A core unit as claimed in claim 1, wherein

said flat tubes, said corrugated fins and said support plates are made of aluminum and soldered with each other.

3. A core unit as claimed in claim 1, wherein

said electric heater further comprises a plus electrode, a minus electrode and an insulating cover surrounding said two electrodes, and

said electric heater is inserted between said pair of plates.

4. A core unit as claimed in claim 3, wherein

each of said plus electrode and said minus electrode has a connecting terminal integrally formed thereon.

5. A core unit as claimed in claim 4, wherein

each of said connecting terminals projects from corresponding one of said plus electrode and said minus electrode in a direction of thickness of said core unit.

6. A core unit as claimed in claim 4 further comprising means for holding said electric heater under pressure between said pair of plates.

7. A core unit as claimed in claim 1, wherein

said electric heater has a positive temperature characteristic sharply changing resistance thereof at a set temperature,

said electric heater is electrically insulated from said plurality of fins, and

said electric heater heats portions of said fins adjacent to said flat tubes at a temperature equal to temperature of said heat carrier in said flat tubes if a temperature of said heat carrier is equal to or higher than 60°

C. and temperature of air to be heated is equal to or lower than 0°

C.

8. A core unit as claimed in claim 1, wherein

said electric heater has a positive temperature characteristic sharply changing resistance thereof at a set temperature,

said electric heater is electrically insulated from said plurality of fins,

said fins have summits disposed between two of said flat tubes,

said fins have a height between 3.9 mm and 5 mm, and

said set temperature of said electric heater is between 85°

C. and 120°

C.

25. The core unit as claimed in claim 1, wherein said heater support member comprises a U-shaped support plate having a U-shaped closing portion located at the air inlet side of said core unit.

26. The core unit as claimed in claim 1, further comprising a fastening member for applying fastening force to said core unit so that said electric heater can be tightly held in said support member.

27. The core unit as claimed in claim 26, wherein

said fastening member has a pair of hook portions at opposite ends thereof and a band portion between said hook portions, and

said band portion is narrower than said hook portions to reduce draft resistance of air passing through said core unit.

28. The core unit as claimed in claim 27, wherein said band portion has a bend projecting forward from said core unit.

29. The core unit as claimed in claim 26, further comprising an upper side plate disposed on upper side of said core unit and a lower side plate disposed under a lower side of said core unit, wherein

each of said upper and lower side plates has a plurality of reinforcement ribs and at least one groove between said ribs, and

said hook portions are engaged with said groove of said upper and lower side plates.

30. The core unit as claimed in claim 29, wherein said hook portions respectively have members for applying fastening force to one of said ribs.

9. A core unit of a heat exchanger core having an air inlet side and an air outlet side, said core comprising:

a plurality of parallelly disposed flat tubes which conduct heat carrier;

a plurality of corrugated fins disposed in contact with said flat tubes;

a support member having a pair of plates parallelly extending along said flat tubes, an opening end portion and a U-shaped closing end portion, said support member disposed between summits of corrugation of adjacent two of said corrugated fins, said U-shaped closing end portion is disposed at said air inlet side, each of said plates being bonded to one of said corrugated fins at summits of corrugation; and

an electric heater disposed between said support plates and insulated from said support member.

10. A core unit as claimed in claim 9, wherein

said opening end portion projects from an end of said electric heater.

11. A core unit as claimed in claim 9, wherein

said opening end portion spreads in a skirt-shape.

12. A core unit as claimed in claim 9, wherein

said support member has the same thickness as said core unit in the air flow direction, and

said electric heater has smaller thickness in the direction of core thickness than said support member, and

said support member comprises means for positioning said electric heater therein.

13. A core unit as claimed in claim 12, wherein

said means for positioning comprises a stopper projecting inside from at least one of said two plates.

14. A core unit for a heater as claimed in claim 13, wherein one of said plates has a reinforcement rib disposed between said stopper and said closing end portion.

15. A core unit as claimed in claim 13, wherein

said means for positioning comprises a stopper member disposed between said electric heater and said closing end portion.

16. A core unit as claimed in any one of claim 9, wherein

each of said flat tubes, corrugated fins and support member is made of aluminum and soldered to each other.

17. A core unit as claimed in claim 9, wherein

said electric heater comprises a plus electrode, a minus electrode, a heating element disposed between said two electrodes, and an insulating cover member covering said two electrodes, and

said cover member is pressed fitted between said plates to hold said electric heater therein.

18. A core unit as claimed in claim 17, wherein

each of said plus electrode and said minus electrode has a connecting terminals projecting therefrom.

19. A core unit as claimed in claim 9 further comprising

a fastening member, disposed on said air outlet side of said core unit, said for holding said electric heater in said support member.

20. A core unit of a heat exchanger including an inlet tank and an outlet tank for a heat carrier, said core unit comprising:

a plurality of parallelly disposed flat tubes which conduct said heat carrier;

a plurality of corrugated fins having summits disposed in contact with said plurality of flat tubes; and

an electric heater disposed between two of said plurality of corrugations in parallel with said plurality of flat tubes, said electric heater having a positive temperature characteristic sharply changing resistance thereof at a set temperature, said electric heater being electrically insulated from said plurality of fins, wherein

said electric heater with said set temperature heats portions of said fins adjacent to said flat tubes at a temperature equal to temperature of said heat carrier in said flat tubes if a temperature of said heat carrier is equal to or higher than 60°

C. and temperature of air to be heated is equal to or lower than 0°

C.

22. A core unit as claimed in claim 20, wherein

said core unit is made of aluminum alloy,

said electric heater is a three-layered sandwich structure composed of an electric heater element and two flat electrodes on opposite sides of said electric heater element and is inserted between said corrugated fins and said two electrodes, and

said two electrodes are pressed fitted to said summits of the corrugation.

23. A core unit as claimed in claim 22, wherein

said heater element has a positive temperature characteristic sharply changing resistance thereof at a set temperature which is between 120°

C. and 170°

C.

21. A core unit of a heat exchanger including an inlet tank and an outlet tank for a heat carrier, said core unit comprising:

a plurality of parallelly disposed flat tubes which connect said inlet and outlet tanks to said heat carrier;

a plurality of corrugated fins each of which is disposed between two of said flat tubes;

an electric heater disposed at a portion of said heat exchanger core in parallel with said flat tubes, said electric heater having a positive temperature characteristic sharply changing resistance thereof at a set temperature, said electric heater being electrically insulated from said plurality of fins, wherein

said fins have summits disposed between two of said flat tubes, said fins have a height between 3.9 mm and 5 mm, and

said set temperature of said electric heater is between 85°

C. and 120°

C.

24. A method of manufacturing a core unit of a heat exchanger to be assembled with an inlet tank and an outlet tank, said core unit being composed of a plurality of parallelly disposed flat tubes, corrugated fins having summits, a pair of support plates and an electric heater, said method comprising steps of:

stacking a portion of said flat tubes of said heat exchanger core and said corrugated fins alternately;

stacking said pair of support plates in the same manner as said flat tubes between said summits of corrugation at a portion where said electric heater is to be disposed;

soldering said flat tubes, said corrugated fins and said support plates into a unit; and

inserting said electric heater between said two plates such that said electric heater is electrically insulated from said plurality of fins.

31. A core unit of a heat exchanger comprising:

a plurality of cooling fins disposed in parallel with each other;

a plurality of parallel tubes each of which is disposed in contact with first adjacent one of said cooling fins;

a heater support member in contact with second adjacent one of said cooling fins in parallel with said plurality of tubes, said heater support member extending along said tubes;

an electric heater held by said heater support member, said electric heater being electrically insulated from said plurality of fins; and

a fastening member for applying fastening force to said core unit so that said electric heater can be tightly held in said support member, said fastening member having a pair of hook portions at opposite ends thereof and a band portion between said hook portions, said band portion having longitudinal draft opening to reduce draft resistance of air passing through said core unit.

32. The core unit as claimed in claim 31, wherein said band portion has a bend projecting forward from said core unit.

33. The core unit as claimed in claim 31, further comprising an upper side plate disposed on upper side of said core unit and a lower side plate disposed under a lower side of said core unit, wherein

each of said upper and lower side plates has a plurality of reinforcement ribs and at least one groove between said ribs, and

said hook portions are engaged with said groove of said upper and lower side plates.

34. The core unit as claimed in claim 33, wherein said hook portions respectively have members for applying fastening force to one of said ribs.

35. The core unit as claimed in claim 33, wherein

each of said hook portions has an arc-shaped portion.

36. The core unit as claimed in claim 31, wherein one of said pair of hook portions has an inwardly extending nail portion, and

the other of said pair of hook portions has an inward projection and a guide portion.

37. The core unit as claimed in claim 31, wherein

each of said plurality of tubes is a flat tube,

each of said plurality of cooling fins is a corrugated fin having a plurality of summits,

said heater support member comprise a U-shaped member disposed between said summits.