Electrical load resistance

Abstract

An electrical load resistance includes a housing having at least one U-shaped receiving pocket, in which at least one PTC heating element is accommodated. The PTC heating element includes at least one PTC element and at least one contact plate electrically conductively connected to the PTC element for energizing the PTC element. The contact plate has a terminal lug for plug contacting the PTC element, and the PTC heating element abuts at least on opposite main side surfaces of the receiving pocket in a heat-conducting manner and projects beyond the terminal lug of the receiving pocket. The housing of the electrical load resistance is closed, and thus has no inlet or outlet openings for a medium to be heated. Also provided is a device with an electrical load resistance for reducing the starting time of an internal combustion engine, a method for reducing the starting time of an internal combustion engine, and a use of a PTC heating device as an electrical load resistance for reducing the starting time of an internal combustion engine.

Claims

1. An electrical load resistance comprising: a closed housing having at least one U-shaped receiving pocket in which at least one PTC heating element is accommodated, the PTC heating element comprising at least one PTC element and at least one contact plate that is electrically conductively connected to the PTC element for energizing the PTC element, wherein the contact plate has a terminal lug for plug contacting the PTC element, wherein the PTC heating element abuts at least on opposite main side surfaces of the receiving pocket in a heat-conducting manner, wherein the terminal lug projects above the receiving pocket, and wherein the closed housing is configured such that no medium can circulate through the closed housing.

2. The electrical load resistance according to claim 1, wherein outer surfaces of the housing form the only boundary surfaces of the electrical load resistance for dissipating heat.

3. The electrical load resistance according to claim 1, wherein the receiving pocket is exposed as a cooling fin on an outer side of the housing.

4. The electrical load resistance according to claim 3, wherein at least one indentation of an outer wall of the housing is provided between two cooling fins.

5. The electrical load resistance according to claim 1, further comprising a housing cover which has a web for secondary locking of the plug connection of the PTC element.

6. The electrical load resistance according to claim 1, further comprising a cable for connection to the PTC heating element, wherein the cable is led through the housing in a sealing manner.

7. The electrical load resistance according to claim 1, wherein the PTC element is electrically conductively connected to the housing, and wherein the housing forms a ground potential for the PTC element.

8. The electrical load resistance according to claim 1, wherein the housing is made of a material having a specific heat capacity of at least 800 J/(K.Math.Kg) at a material temperature of 20° C., and wherein the housing has a weight of at least 500 g.

9. A device for reducing the starting time of an internal combustion engine, the device comprising: an electrical load resistance with at least one PTC heating element accommodated in a housing, wherein the electrical load resistance is connected to a generator driven by the internal combustion engine, wherein the housing is mounted on a vehicle comprising the internal combustion engine such that heat generated by the device is exclusively and directly dissipated to the environment or stored in the housing, and wherein the housing is a closed housing that is configured such that no medium can circulate therein.

10. A method for reducing the starting time of an internal combustion engine, comprising: measuring a temperature of the combustion engine; operating a load resistance connected to a generator driven by the combustion engine until the measured temperature of the combustion engine reaches a predetermined temperature, wherein the load resistance comprises at least PTC heating element, and wherein the heat generated by the at least one PTC heating element is not transferred onto a guided medium flow.

11. The method according to claim 10, wherein the load resistance is operated cyclically, and wherein one cycle includes a power phase and a rest phase.

12. The method according to claim 11, wherein the one cycle lasts between 30 and 120s and/or wherein the rest phase is 2 to 5 times longer than the power phase.

13. The electrical load resistance according to claim 1, wherein the closed housing lacks any openings for the inlet or outlet of a medium.

14. The device according to claim 9, wherein the closed housing lacks any openings for the inlet or outlet of a medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the present invention can be derived from the following description of a preferred embodiment in connection with the drawing. Therein:

(2) FIG. 1 shows a perspective side view of an electrical load resistance of the embodiment,

(3) FIG. 2 shows a longitudinal section view of the electrical load resistance of the embodiment,

(4) FIG. 3 shows a perspective side view of components of the embodiment,

(5) FIG. 4 shows a top view of the electrical load resistance of the embodiment with omitted housing cover, and

(6) FIG. 5 shows a sectional view of a PTC heating unit of the embodiment.

DETAILED DESCRIPTION

(7) The electrical load resistance 2 shown in FIG. 1 has an essentially cuboid housing 4 made of aluminum. The housing 4 is covered with a plastic housing cover 6 which closes a connection chamber. The housing cover 6 is screwed to the housing 4 by means of screws 8. A through-hole 10 of the housing 4 (see FIG. 4) is the only opening of the housing 4 to the connection chamber apart from the opening of the housing 4 closed by the housing cover 6. A sealant 12 is provided in the through-hole 10. The sealant 12 abuts the outside of the housing 4 with a seal 14 around the through-hole and is sealed against it by means of screws 16. An electrical connecting cable 18 is led through the sealant 12 in a sealing manner. The electrical connecting cable 18 comprises several strands 20 which are contacted with their end outside the housing by a plug 22. A second end 24 of the connecting cable is contacted with a separate plug 26. The electrical load resistance 2 has fasteners 28 for fixing the cable 18, wherein one of the fasteners 28 is provided on the housing cover.

(8) The sectional view shown in FIG. 2 illustrates the internal structure of the electrical load resistance 2. The housing 4 forms four U-shaped receiving pockets 30, in each of which a PTC heating element 32 is arranged. The PTC heating elements 32 in the receiving pockets 30 are in heat-conducting contact with the housing 4. The outer side of the receiving pockets 30 at least partially forms an outer wall of the housing 4. At least one indentation 34 of the housing is provided between two receiving pockets 30. The indentations 34 are also essentially U-shaped and aligned antiparallel to the receiving pockets 30. The receiving pockets 30 thus form cooling fins which are at least partially exposed on the outside of the housing 4 so that the housing 4 itself is configured as a heat sink.

(9) A plastic frame 36 of the PTC heating units 32 protrudes from the receiving pockets 30, in which several PTC elements 58 and a contact plate 60, which is in electrically conductive contact with the PTC elements 58, are held (see FIG. 5). Furthermore, a terminal lug 38 of the contact plate protrudes from the receiving pocket 30. The terminal lug 38 is electrically connected to a plug element 40. Within the receiving pocket 30, the contact plate is usually electrically insulated from the housing by an insulating layer 62. On the side opposite the contact plate 60, the PTC elements 58 abut the housing 4 in an electrically conductive manner.

(10) The plug element 40 has a crimp connection 42 with one of the strands 20 of the connecting cable 18 which are connected to the positive/ground terminal. Inside, the housing 4 forms a column-shaped ground terminal 44, which is electrically connected to a ground strand 20e of the connecting cable 18. The housing 4 thus forms a ground potential for the PTC heating elements 32 and is part of a circuit that is supplied by the 12V vehicle electrical system.

(11) When the current is passed through the PTC heating elements 32, they heat up, which emit the heat to the housing 4 through heat-conducting abutment in the receiving pockets 30. The receiving pockets 30, designed as cooling fins, then radiate the heat to the surroundings. From the housing cover 6, webs 46 extend column-like into the interior of the housing 4. These webs 46 are made in one piece with the housing cover 6 and are made of plastic. The webs 46 extend in elongation of the receiving pockets 30, wherein the tip of the webs 46 pointing to the openings of the receiving pockets 30 has a U-shaped recess to which the crimp connection 42 abuts. By fixing the housing cover 6 to the housing 4 by means of the screws 8, the webs 46 exert a certain pressure on the plug elements 40 and thus also on the PTC heating elements 32 in the direction of the receiving pocket 30. This ensures that the plug contacts are secured and that the PTC heating elements 32 always abut the housing 4 in a thermally conductive manner in the receiving pockets 30. In addition, the webs 46 each form a form fit for the PTC heating elements 32 in the direction of the opening of the receiving pockets 30 so that it is prevented that the PTC heating elements 32 can lift out of the receiving pockets 30, for example, due to vibration, or that the plug element 40 comes loose from the terminal lug 38.

(12) FIG. 3 shows the components of the electrical load resistance excluding the housing 4. For example, FIG. 3 shows that the housing cover 6 is attached to the housing 4 by means of an intermediate layer of an insert seal 48. The sealing element 12, which is also not shown in FIG. 3, is also sealed against the housing 4 with the interposition of an O-ring 50 which forms the seal 14. The strands 20 of the connecting cable 18 have 10 single strand seals 52 at the height of the through-hole. The plastic frame 36 of the PTC heating units 32 holds a wedge element 54 which, in a manner known per se, ensures a thermally conductive abutment of the PTC heating unit 32 in the receiving pocket 30; cf. EP 1 872 986 A1.

(13) As can be seen from FIG. 4, the individual strands 20 of the connecting cable 18 are each led through a channel 56 of the sealing element 12. In these channels 56, the single strand seals 52 are provided which are elastically pressed in radial direction by the channels. Thus, the through-hole 10 is closed in a fluid-tight manner by the sealing element 12 and the seal 14.

(14) FIG. 5 shows the PTC heating unit 32 in detail. In the plastic frame 36 of the PTC heating unit 32, four PTC elements 58 are arranged one above the other in a row. On the left-hand side in FIG. 5, a contact plate 60 abuts the main side surfaces of the PTC elements 58 in an electrically conductive manner. The contact plate 60 forms the terminal lug 38, which protrudes over the plastic frame 36 and thus also the receiving pocket 30 and is exposed in the connection chamber The contact plate 60 is insulated from the housing 4 by means of an insulating layer 62 which lies on the outside of the contact plate 60. A sliding plate 64 is provided on the outside of the insulating layer 62, on the outside of which the wedge element 54 abuts. The wedge element 54 is shown in a holding position in which it is located in an insertion opening 66 of the plastic frame 36. When the wedge element 54 is fully inserted into the plastic frame 36, it causes a heat-conducting abutment between the PTC heating element 32 and the receiving pocket 30. On the side of the PTC elements 58 opposite the contact plate 60, an electrically conductive ground plate 68 abuts the main side surfaces of the PTC elements 58. On its outer side, the ground plate 68 abuts electrically and heat-conductively against an inner side of the receiving pocket 30. At the end protruding from the terminal lug 38, the plastic frame 36 forms a stop 70 which abuts the housing 4 around the opening to the receiving pocket 30.

(15) The PTC elements 58 are held and positioned between the ground plate 68 and the wedge element 54 in the plastic frame 36. This allows the PTC heating element 32 to be prefabricated and handled as a unit.