Electric heating system for a motor vehicle

• US 6,875,962 B2
• Filed: 01/17/2002
• Issued: 04/05/2005
• Est. Priority Date: 01/17/2001
• Status: Expired due to Fees

• Current Assignee: Borgwarner BERU Systems GmbH (BorgWarner Incorporated)
• Original Assignee: Beru Aktiengesellschaft (BorgWarner Incorporated), Eichenauer Heizelemente GmbH & Co. KG
• Inventors: Giffels, Thomas, Riether, Mike, Hamburger, Andreas, Alban, Thomas, Geiger, Steffen, Wenske, Dirk, Uhl, Günther
• Primary Examiner(s): Evans, Robin O.
• Assistant Examiner(s): PATEL, VINOD D
• Application Number:
  US10/466,750
• Publication Number:
  US 20040112884A1
• Time in Patent Office: 1,174 Days
• Field of Search: 219/530, 219/540, 219/202, 219/203, 392/347
• US Class Current: 219/530
• CPC Class Codes: B60H 1/034 from the cooling liquid of the propulsion plant and from an electric heating device
• CPC Class Codes: B60H 1/2225 arrangements of electric heaters for heating air
• CPC Class Codes: F24H 3/0441 Interfaces between the electrodes of a resistive heating element and the power supply means
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 2201/0305 Solder used for other purposes than connections between PCB or components, e.g. for filling vias or for programmable patterns
• CPC Class Codes: H05K 2201/0382 Continuously deformed conductors
• CPC Class Codes: H05K 2201/10166 Transistor
• CPC Class Codes: H05K 2201/2036 Permanent spacer or stand-off in a printed circuit or printed circuit assembly
• CPC Class Codes: H05K 2203/0315 Oxidising metal
• CPC Class Codes: H05K 3/0061 onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: H05K 3/4038 Through-connections; Vertical interconnect access [VIA] connections H05K3/403, H05K3/42 take precedence

Abstract

An electric heating system for motor vehicles including one or several electric heating elements; a control circuit provided for controlling the power dissipated by the heating elements; the control circuit including one or several power semiconductors arranged on a circuit board; the circuit board is by means of a solid matter connection connected by the side facing away from the power semiconductors to a metal plate intended to be mass potential; the metal plate being electrically insulated from conductor paths located on the underside of the circuit board and intended to carry a voltage in relation to the ground potential; the control circuit being arranged in a housing. One or several heat sinks are provided outside the housing. The metal plate is connected with the heat sinks arranged outside the housing by thermally conductive connectors.

Claims

1. An electric heating system for motor vehicles comprising:

at least one electric heating element;

a control circuit to control the power dissipated by the at least one electric heating element;

the control circuit including at least one power semiconductor arranged on a circuit board;

wherein an underside of the circuit board, opposite the side that the at least one power semiconductor is arranged on, is connected to an electrically grounded metal plate by a solid matter connection;

wherein the metal plate is electrically insulated from conductor paths located on the underside of the circuit board and carrying a voltage in relation to the grounded electric potential;

wherein the control circuit is arranged in a housing;

wherein at least one heat sink is provided outside the housing; and

wherein the metal plate is connected by thermally conductive connectors to the at least one heat sink.

2. The heating system as defined in claim 1, wherein the material of the metal plate is selected from the group consisting of aluminum, copper, aluminum alloys and copper alloys.

3. The heating system as defined in claim 1 wherein a surface of the metal plate facing the circuit board carries a thin, electrically insulating layer.

4. The heating system as defined in claim 3 wherein said electrically insulating layer is a synthetic resin varnish.

5. The heating system as defined in claim 3 wherein said electrically insulating layer is on oxide layer.

6. The heating system as defined in claim 3 wherein said electrically insulating layer is anodically reinforced.

7. The heating system as defined in claim 1, wherein a glue layer is provided to attach the metal plate to the circuit board.

8. The heating system as defined in claim 7, wherein the glue layer is provided between the metal plate and the circuit board and has a thermal conductivity of at least 0.8 W/(m×

K).

9. The heating system as defined in claim 7, wherein the glue layer is provided between the metal plate and the circuit board and has a conductivity of at least 0.9 W/(m×

K).

10. The heating system as defined in claim 7, wherein the glue layer is a cross-linked two-component silicon elastomer.

11. The heating system as defined in claim 7, wherein the thickness of the glue layer is less than 0.2 mm.

12. The heating system as defined in claim 7, wherein the thickness of the glue layer is less than 0.15 mm.

13. The heating system as defined in claim 1, wherein the metal plate is approximately as big as the circuit board.

14. The heating system as defined in claim 1, wherein the metal plate has approximately the same contour as the circuit board.

15. The heating system as defined in claim 1, wherein at least one rigid spacer is provided between the metal plate and the circuit board, to provide a small gap between the metal plate and the circuit board.

16. The heating system as defined in claim 15, wherein the at least one spacer takes the form of bumps provided on the metal plate in areas opposite to the underside of the circuit board where no conductor paths are arranged.

17. The heating system as defined in claim 15, wherein the at least one spacer is formed by embossing of the metal plate.

18. The heating system as defined in any of claim 15, wherein the metal plate is connected with a conductor path of the circuit board, which is connected to the grounded potential, by at least one spacer.

19. The heating system as defined in claim 1, wherein the circuit board has a high density of electrical current paths in those areas where the power semiconductors are provided, and the current paths lead from the upper surface of the circuit board, through the circuit board, to the underside of the circuit board.

20. The heating system as defined in claim 19, wherein the current paths are inside bores filled with metal.

21. The heating system as defined in claim 20, wherein the metal filled in the inside bores is selected from the group consisting of copper and tin-lead solder.

22. The heating system as defined in claim 19, wherein the current paths connect a metal surface on an upper surface of the circuit board with a metal surface on the underside of the circuit board.

23. The heating system as defined in claim 22, wherein the metal surfaces are approximately the size of a base surface of a respective power semiconductor.

24. The heating system as defined in claim 1, wherein the connectors are detachably connected with at least one of the metal plate and at least one heat sink.

25. The heating system as defined in claim 24, wherein the connection between the connectors and at least one of the metal plate and at least one heat sink is a plug-in connection.

26. The heating system as defined in claim 25, wherein tongues arranged in pairs one opposite the other, are cut out from the metal plate and are bent off from the plane of the metal plate, the distance between such tongues being smaller than the thickness of the rigid connector that can be introduced between any pair of tongues.

27. The heating system as defined in claim 24, wherein the connectors have a rigid configuration.

28. The heating system as defined in claim 24, wherein the connectors are configured as a rod.

29. The heating system as defined in claim 24, wherein the connectors are configured as a hollow rod.

30. The heating system as defined in claim 1, wherein the at least one heat sink is a metal sheet.

31. The heating system as defined in claim 1, wherein the at least one heat sink connects the connectors one to the other.

32. The heating system as defined in claim 31, wherein the at least one the heat sink is pushed onto the connectors.

33. The heating system as defined in claim 32, wherein the at least one heat sink is held on the connectors in force-locking engagement.

34. The heating system as defined in claim 1, wherein the at least one electric heating element dissipates the heat generated via a heat-dissipating means which, when mounted in a vehicle in the intended way, lie in a channel that can be passed by air for the purpose of heating up the passenger compartment of the vehicle.

35. The heating system as defined in claim 34, wherein the at least one heat sink is positioned proximate to the heat-dissipating means of the at least one electric heating element.

36. The heating system as defined in claim 35, wherein the at least one heat sink is arranged between the heat-dissipating means and the housing, though at a distance from the housing.

37. The heating system as defined in claim 34, wherein the heat-dissipating means and the at least one heat sink are designed identically or in a conforming fashion.

38. The heating system as defined in claim 1, wherein the at least one electric heating element is contained in heating rods which simultaneously serve as connectors between the metal plate and the at least one heat sink.

39. The heating system as defined in claim 38, wherein the heating rods do not have any heating elements on a section following the housing, where the at least one heat sink is provided.

40. The heating system as defined in claim 1, wherein the connectors extend from an area which is close to the at least one power semiconductor.

41. The heating system as defined in claim 1, wherein at least one potential-carrying supply line to the at least one electric heating element is connected to a power output of a respective power semiconductor by a plug-in-connector provided on the circuit board.

42. The heating system as defined in claim 41, wherein the at least one supply line is rigidly connected with the at least one electric heating element and the plug-in direction of the plug-in connector coincides with the longitudinal direction of the at least one electric heating element.

43. The heating system as defined in claim 41, wherein the plug-in connector is arranged on a surface of the circuit board that faces away from the metal plate, and is accessible for the supply line through a hole in the circuit board.