Electric heating system for a motor vehicle

• US 20040112884A1
• Filed: 10/14/2003
• Published: 06/17/2004
• Est. Priority Date: 01/17/2001
• Status: Active Grant

• 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, Gunther
• Granted Patent: US 6,875,962 B2
• Time in Patent Office: Days
• US Class Current: 219/202
• 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 pattern for applying drops or paste H05K2203/0545
• 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

The invention describes an electric heating system for motor vehicles with the following characteristics:

The heating system has one or several electric heating elements (3);

a control circuit is provided for controlling the power dissipated by the heating elements (3);

the control circuit comprises one or several power semiconductors (5) arranged on a circuit board (6);

the circuit board (6) is by means of a solid matter connection connected by the side facing away from the power semiconductors (5) (hereinafter referred to as its underside), to a metal plate (7) intended to be mass potential;

the metal plate (7) is electrically insulated from conductor paths located on the underside of the circuit board (6) and intended to carry a voltage in relation to the ground potential;

the control circuit is arranged in a housing (8);

one or several heat sinks (4a) are provided outside the housing (8);

the metal plate (7), located in the housing (8), is connected with the heat sinks (4a) arranged outside the housing (8) by thermally conductive connectors (2).

Claims

1. Electric heating system for motor vehicles with the following characteristics:

The heating system has one or several electric heating elements (3);

a control circuit is provided for controlling the power dissipated by the heating elements (3);

the control circuit comprises one or several power semiconductors (5) arranged on a circuit board (6);

the circuit board (6) is by means of a solid matter connection connected by the side facing away from the power semiconductors (5) (hereinafter referred to as its underside), to a metal plate (7) intended to be lying on ground potential;

the metal plate (7) is electrically insulated from conductor paths located on the underside of the circuit board (6) and intended to carry a voltage in relation to the ground potential;

the control circuit is arranged in a housing (8);

one or several heat sinks (4a) are provided outside the housing (8);

the metal plate (7), located in the housing (8), is connected with the heat sinks (4a) arranged outside the housing (8) by thermally conductive connectors (2).

2. The heating system as defined in claim 1, characterized in that the metal plate (7) consists of metal which conducts heat well, especially aluminum or copper, or of alloys of such metals.

3. The heating system as defined in claim 1 or claim 2, characterized in that the metal plate (7) carries on its surface facing the circuit board (6) a thin, electrically insulating layer, especially a synthetic resin varnish or an oxide layer, which preferably is anodically reinforced.

4. The heating system as defined in any of the preceding claims, characterized in that the metal plate (7) is glued to the circuit board (6).

5. The heating system as defined in claim 4, characterized in that the glue layer (15) provided between the metal sheet (7) and the circuit board (6) has a thermal conductivity of at least 0.6 W/(m×

K), preferably at least 0.9 W/(m×

K).

6. The heating system as defined in claim 4 or claim 5, characterized in that the glue is a cross-linked two-component silicon elastomer.

7. The heating system as defined in any of the preceding claims, characterized in that the metal plate (7) is approximately as big as the circuit board (6).

8. The heating system as defined in any of the preceding claims, characterized in that the metal plate (7) has approximately the same contour as the circuit board (6).

9. The heating system as defined in any of the preceding claims, characterized in that the glue layer (15) has a thickness of maximally 0.2 mm.

10. The heating system as defined in any of the preceding claims, characterized in that the glue layer (15) has a thickness of maximally 0.15 mm.

11. The heating system as defined in any of the preceding claims, characterized in that rigid spacers (12) are provided between the metal plate (7) and the circuit board (6), which guarantee a small distance between the metal plate (7) and the circuit board (6).

12. The heating system as defined in claim 11, characterized in that the spacers (12) take the form of bumps provided on the metal plate (7) in areas opposite to the underside of the circuit board (6) where no conductor paths (13) are arranged.

13. The heating system as defined in claim 11 or claim 12, characterized in that the spacers are formed by embossing of the metal plate (7).

14. The heating system as defined in any of claims 11 to 13, characterized in that the metal plate (7) is connected with one conductor path (13) of the circuit board (6), which is intended to be connected to ground potential, by one or more spacers (12).

15. The heating system as defined in any of the preceding claims, characterized in that the circuit board (6) has a high density of electrical current paths (9) in those areas where the power semiconductors (5) are provided, which current paths lead from the upper surface of the circuit board (6) and through the circuit board (6) to its underside.

16. The heating system as defined in claim 15, characterized in that the current paths (9) are inside bores filled with metal, especially copper or tin-lead solder.

17. The heating system as defined in claim 15 or claim 16, characterized in that the current paths connect a metal surface (20) on the upper surface of the circuit board (6) with a metal surface (21) on the underside of the circuit board (6).

18. The heating system as defined in claim 17, characterized in that the metal surfaces (20, 21) are approximately as big as the base surface of the respective power semiconductor (5).

19. The heating system as defined in any of the preceding claims, characterized in that the connector (2) is detachably connected with the metal plate (7) and/or the one or more heat sinks (4a).

20. The heating system as defined in claim 19, characterized in that the connection between the connector (2) and the meal plate (7) and/or the heat sinks (4a) is a plug-in connection.

21. The heating system as defined in claim 19 or claim 20, characterized in that the connector (2) has a rigid configuration and is preferably a rod or a hollow rod.

22. The heating system as defined in claim 20 or 21, characterized in that tongues (14) arranged in pairs one opposite the other, are cut out from the metal plate (7) and are bent off from the plane of the metal plate (7), the distance between such reeds being smaller than the thickness of the rigid connector (2) that can be introduced between any pair of such tongues (14).

23. The heating system as defined in any of the preceding claims, characterized in that the heat sinks (4a) are metal sheets.

24. The heating system as defined in any of the preceding claims, characterized in that the heat sinks (4a) connect the connectors (2) one to the other.

25. The heating system as defined in claim 24, characterized in that the heat sinks (4a) are pushed onto the connectors (2).

26. The heating system as defined in claim 25, characterized in that the heat sinks (4a) are held on the connectors (2) in force-locking engagement.

27. The heating system as defined in any of the preceding claims, characterized in that the heating elements (3) dissipate the heat generated by them via heat-dissipating means (4) which, when mounted in a vehicle in the intended way, come to lie in a channel that can be passed by air for the purpose of heating up the passenger compartment of the vehicle.

28. The heating system as defined in claim 27, characterized in that the heat sinks (4a) are positioned in the neighbourhood of the heat-dissipating means (4) of the heating elements (3).

29. The heating system as defined in claim 28, characterized in that the heat sinks (4a) are arranged between the heat-dissipating means (4) for the heating elements (3) and the housing (8), though at a distance from the housing (8).

30. The heating system as defined in any of the preceding claims, characterized in that the heating elements (3) are contained in heating rods which simultaneously serve as connectors (2) between the metal sheet (7) and the heat sinks (4a).

31. The heating system as defined in claims 27 and 28, characterized in that the heat-dissipating means (4) and the heat sinks (4a) are designed identically or in a conforming fashion.

32. The heating system as defined in claim 30 or claim 31, characterized in that the heating rods (2) do not have any heating elements (3) on a section following the housing (8), where the heat sinks (4a) are provided.

33. The heating system as defined in any of the preceding claims, characterized in that the connectors (2) extend from an area which is close to the power semiconductors (5).

34. The heating system as defined in any of the preceding claims, characterized in that the one or more potential-carrying supply lines (16) to the one or more heating elements (3) is/are connected to the power output of the respective power semiconductor (5) by a plug-in-connector (17) provided on the circuit board (6).

35. The heating system as defined in claims 30 and 34, characterized in that the supply line (16) is rigidly connected with the heating rod (2) and the plug-in direction of the plug-in connector (17) coincides with the longitudinal direction of the heating rod (2).

36. The heating system as defined in claim 34 or claim 35, characterized in that the plug-in connector (17) is arranged on the surface of the circuit board (6) that faces away from the metal plate (7), and is accessible for the supply line (16) through a hole in the circuit board.