DE202014010469U1 - resistance - Google Patents

Abstract

Resistor, preferably a braking, discharging or high-load resistor comprising a wire winding element (22) having a wire resistance winding wound around a support (38), the ends (56, 62) of which can be connected to terminal regions (50, 52), characterized in that a wire section (68) improved in relation to the environment improves thermally insulated, so that in case of failure, the wire winding element (22) in this wire section (68) fails.

Description

The invention relates to a resistor, preferably a braking, discharging or high load resistor according to the preamble of claim 1.

Braking resistors are used, for example, to reduce excess energy, which can not be used for charging a battery or a capacitor arrangement or the like, in electrical drives in the case of recuperation, by converting these energy or voltage peaks into heat.

Braking or discharging resistors may be formed with ceramic PTC resistor elements or wirewound resistor elements. Braking resistors with ceramic PTC resistor elements are for example in the EP 1 225 080 B1 the applicant described. Such braking resistors have a high reliability because of their strong with the temperature increasing resistance characteristic, since they abregel themselves with an overload. The disadvantage is that such PTC braking resistors are relatively expensive.

In less demanding applications braking or discharging resistors - also called load resistors - are usually used, in which the resistance element is designed as a wire wound winding, which surrounds an insulating body. Cartridge-shaped embodiments of such wire resistance elements are for example in the DE 2 228 460 or the DE 37 03 689 C2 disclosed. However, these cartridge-shaped braking resistors have a comparatively complex structure. Significantly more compact are solutions in which the wire resistance element has a wire winding which is wound on a flat support and which is then inserted into a heat sink formed as a hollow profile. Thus, an encapsulated structure for increasing safety is realized.

Such a solution is for example in the EP 1 711 035 A1 the applicant explains. Accordingly, the known braking resistor has the heat sink made of aluminum as a heat sink, in which the wire resistance element is used. Its positional positioning is done by micanite insulating plates, which hold the heating element at a distance from the peripheral wall of the extruded profile. Micanite is the trade name of a mica material, which forms a solid, plate-shaped insulating material. The frontal sealing of the heat sink takes place in each case via a closure, wherein a current supply-side closure is penetrated by two connection lines. Conventionally, these closures are formed in that the extruded profile is first placed on a mounting device and then a micanite plate is inserted or pressed into a frontal recording of the extruded profile. This micanite plate is then cast with silicone or a corresponding sealant, such as sour rice cement, bottom side and cured. After curing, the wire resistance element is placed in the receiving space and filled with MgO, whereby the filling density is increased by shaking. The MgO serves as insulation material and as heat storage. In addition, the MgO fixes the wire resistance element and / or the position of the wire windings. In this case, prior to filling in the receiving space micanite plates are used, which prevent a direct contacting of the wire resistor element with the heat sink and thus ensure the electrical insulation. In turn, a closure is applied and cured on this backfilling.

Since this manufacturing process is relatively expensive due to the two-time curing, is in the DE 10 2011 001 362 A1 proposed, in place of the thermosetting layer next to the filling to insert a small plate in the heat sink, which is sealed by a sealant. Adjacent to the plate is then used, for example, a metallic or ceramic closure plate in the heat sink, which is mechanically connected thereto.

Such a concept can be realized with significantly reduced production times, since the time-consuming and also in terms of warehousing complex curing is eliminated.

In the EP 1 852 878 B1 discloses a solution in which the wire resistance winding with the support and the arranged between the peripheral walls of the heat sink and the wire wound insulation insulating plates are pressed, so that can be dispensed with a filling.

In such a wire-wound resistor elements, the wire winding is usually wound around the two longitudinal legs of a multi-part frame-shaped micanite carrier, this winding extending from a connection side narrow side, then extending along a longitudinal leg of the frame, in the region of another narrow side then to the other, parallel legs goes over and leads from there back to the connection side narrow side. The manufacturing cost of the multi-part carrier and the double-winding is significant.

A disadvantage of all these solutions is that it can lead to overheating of the wire winding in the event of a fault, for example when an excessive voltage occurs, resulting in a Burning through or even lead to a partial melting of the adjacent extruded profile. Wirewound resistor elements are usually provided with a protective circuit which should respond in case of overload - in case of failure, it can still come to an arcing and the associated problems described above. Since this arc jumps from winding to winding as it were, one can not judge in advance at which point this burning takes place.

In contrast, the present invention seeks to provide a resistor in which the reliability is improved with low device complexity.

This object is achieved by a resistor having the features of claim 1.

Advantageous developments of the invention are the subject of the dependent claims. According to the invention, the resistor, which may be embodied as a braking, discharging or high-load resistor, hereinafter referred to simply as a braking resistor, is designed with a wire winding element which has a wound around an insulating support wire wound winding whose ends are associated with connection elements. According to the invention, a predetermined wire section of the wire winding is better thermally insulated from the environment in comparison to the other wire winding, so that in the event of a fault the wire winding element fails in this wire section.

In this way, can be determined structurally without reducing the wire cross-section, in which area the wire winding burns in the event of a fault, so that with an appropriate design of this area the risk of damage to adjacent components and dangerous electrical contact to the housing, i. a body closure, can be prevented, and an "intrinsically safe disembarkation" of the braking resistor is made possible.

• – Es kommt nicht zu einem Körperschluss, dass heißt einem Durchschlagen des Stroms auf das Gehäuse. In diesem Fall wäre nicht nur das Gehäuse des Bremswiderstandes sondern auch der Motor, auf dem das System elektrisch leitend verschraubt ist unter Spannung gesetzt.
• – Es bleibt ein genügend hoher Isolationswiderstand des Systems erhalten.
• – Es bleibt eine genügend hohe Spannungsfestigkeit des Systems erhalten.
• – Es liegt eine hinreichende thermische Sicherheit vor, also eine Sicherheit gegen Überhitzung des Systems mit einer daraus resultierenden Gefährdung von umliegenden Bauelementen.

This significantly improves the intrinsic safety of the system over conventional solutions. Intrinsic safety is defined by the following characteristics for a wire braking resistor:

• - It does not come to a body closure, that is a penetration of the current to the housing. In this case, not only the housing of the braking resistor but also the motor on which the system is screwed electrically conductive would be under tension.
• - It remains a sufficiently high insulation resistance of the system.
• - It remains a sufficiently high dielectric strength of the system.
• - There is a sufficient thermal safety, so a security against overheating of the system with a resulting threat to surrounding components.

In a preferred embodiment of the invention, this wire section is at least partially surrounded by the carrier or embedded in this.

The structure of the braking resistor is particularly simple if the carrier has two carrier elements, between which the wire section extends, while the remaining wire winding extends around the two carrier elements.

It is furthermore preferred if the wire winding extends away from a connection-side end section of the support toward another end section and is then returned between the support elements to the connection-side end section and is then connected there to a connection element. That In this variant, the wire passage extends between the two support elements.

These are preferably formed plate-shaped, so that this wire return / wire passage between the plates and results in a corresponding sandwich-like structure.

Arcing in the deflection region can be prevented as far as possible when the winding is deflected at a distance from the other end portion of the carrier in the direction of the connection-side end portion. This can be effected relatively easily, in which this deflection takes place along a recess formed in the other end section of the carrier.

A lateral arcing can also be avoided if the wrapped region of the carrier is set back relative to its end sections so that they project beyond the winding on both sides.

In a preferred embodiment of the invention, the support is made of an electrically and thermally insulating material, such as e.g. Mikanit or the like produced.

It is particularly preferred if the wire resistor is formed as a flat wire. The spacing of the wire turns should be more than 1.5 mm in one embodiment. Of course, also round wire can be used, in this case, the distance is less, for example, 0.25 mm.

The distances depend on the required total resistance of the system. A round wire is preferably used in thicknesses between 0.1 mm to 0.45 mm. With such diameters, relatively large resistance values can be realized. If a smaller resistance is required, flat wire is preferred.

The mounting of the braking resistor is particularly easy if the carrier has recesses on the connection-side end section, in which the end sections of the winding can be prefixed.

The braking resistor is preferably formed with a heat sink, which has a receiving space, which accommodates the wire winding element, wherein the connecting lines extend through an end closure of the heat sink.

The electrical insulation with respect to the heat sink is particularly effective when the wire resistance element is embedded in a filling and further insulation elements are arranged between the filling and heat sink.

Accordingly, in a manufacturing method, the wire resistor is first passed from the terminal side between the two parts of the carrier and deflected at the opposite end portion of the carrier. As a result, the carrier is then wrapped with the resistance wire, the winding direction extending to the terminal-side end portion of the carrier.

In a variant of the invention, the wire winding element can also be pressed with the heat sink, wherein between the wire winding element and the heat sink electrically insulating plates are provided as insulation body. In such a variant can be dispensed with the described filling.

Alternatively, the wire winding element can also be encapsulated with an electrically insulating material which forms a heat storage and heat transfer element. The cured block can then be inserted into the receiving space of the heat sink. In principle, it is also possible to shed the wire winding element directly in the heat sink.

Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. Show it:

1 a three-dimensional view of a brake resistor according to the invention;

2 the braking resistor off 1 with removed top surface;

3 a view of a wire winding element of the braking resistor according to the 1 and 2 ;

4 a graphically broken view of the wire winding element according to 3 ;

5 an individual representation of the wire winding of the wire winding element according to the 3 and 4 and

6 a sectional view of a variant of a braking resistor.

1 shows a three-dimensional representation of a braking resistor according to the invention 1 ,

The invention will be explained with reference to a resistor (braking, discharging or high load resistance). In principle, however, the inventive concept can also be used as a heating resistor in a heater.

Accordingly, this has a designed as an aluminum extruded profile heatsink 2 , in which in the following explained in more detail recording space (see 2 ) a wire winding element is received. The contacting of this wire winding element via two connecting cables 4 . 6 which has a connection-side closure 8th push through. The heat sink 2 serves as a heat storage, which absorbs the heat generated at the wire winding element. The heated heat sink is then in heat exchange with the environment.

The heat sink is with the heat exchange surface increasing cooling fins 10 executed and has recesses in the corner areas 12 attaching the heat sink 2 on a housing or the like. At the of the connection lines 4 . 6 removed end portion of the heat sink 2 is, as explained in more detail below, formed a bottom-side closure. At the in 1 illustrated embodiment, the cooling fins 10 only in an upper cover wall, in the following deck surface 14 called, trained, of course, these can also in the underlying deck surface 16 be formed. These top surfaces survive the main body of the heat sink 2 laterally, leaving side walls 18 . 20 formed as a U-profile. Additional elements such as temperature sensors or limiters can be mounted in this U-profile. Other geometries are possible.

2 shows the braking resistor according to 1 with removed top surface 14 , so that the mentioned wire winding element 22 is visible. The illustrated layer structure of this braking resistor 1 is in principle from the aforementioned prior art according to the DE 10 2011 001 362 A1 known, so that only the essential elements for understanding the invention are described here. The wire winding element 22 is in a recording room 24 of the heat sink 2 used. This recording room 24 is through the two U-shaped side walls 18 . 20 , the two top walls or top surfaces 14 . 16 (Cover surface 14 in the illustration according to 2 removed), the connection-side shutter 8th and the mentioned further bottom-side closure 26 limited. The two plate-shaped closures 8th . 26 For example, may be made of metal, ceramic or glass and are preferably with the heat sink 2 caulked.

In the distance to the lock 26 is a mikanite tile 28 arranged, which is fixed in position by means of a potting compound or the like, not shown. Also a pressing in of the Mikanit plate 28 is possible. This tile 28 adjoins two long side micanite insulating panels 30 . 32 on, leading to two connection-side plates 34 . 36 extend. These are in turn at a distance to the shutter 8th arranged and held by means of a sealant. Like in the DE 10 2011 001 362 A1 explained, these two have platelets 34 . 36 mutually formed recesses, which in the assembled state to bushings for the two connecting lines 4 . 6 complement, these bushings embrace the circumference of the lines. Corresponding bushings 37a . 37b are also in the lock 8th educated.

In the area between the wire winding element 22 and the lower deck area 16 as well as in 2 removed upper deck area 14 of the heat sink 2 are still per side at least one micanite floor panels provided, between which then the wire winding element 22 is arranged. Accordingly, these two micanite floor panels, the longitudinally arranged insulating panels 30 . 32 and the front side arranged platelets 28 . 34 . 36 a closed insulating body, the wire winding element 22 engages in a box shape. The recording room 24 is filled with a sand filling, which is partially solidified by shaking, so that the wire winding element 22 reliable in the recording room 24 positionally positioned and also effectively thermally coupled to the heat sink. In this case, the wire is positioned position.

The structure of the wire winding element 22 opens up from the 3 to 5 , The 3 and 4 show an individual representation of the wire winding element 22 according to 2 , The wire winding element 22 has a carrier made of micanite 38 , which according to the broken-line illustration in 4 in principle, two micanite carrier elements 40 . 42 exists, of which in the illustration according to 3 only the carrier element 42 is visible. This covers the in 4 overhead support element 40 ,

The two substantially congruent support elements 40 . 42 have a connection-side end section 44 and an end portion remote therefrom 46 , which on both sides against a winding section arranged therebetween 48 are widened. At the connection-side end section 44 are two connection areas 50 . 52 provided, each formed by a welding bridge, to which the two connecting lines 4 . 6 dotted or otherwise tethered. The carrier 38 carries the actual wire winding. The resistance wire used here 54 is formed in the illustrated embodiment as a flat wire with a rectangular cross section and is made of a Heizdrahtlegierung. The winding pitch W is preferably more than 0.5 mm. As explained above, instead of a flat wire and a round wire can be used. In this case, the wire diameters are usually in the range between 0.1 mm to 0.45 mm.

When winding can in a first step, first in 3 below and in 4 overhead end 56 of the wire 54 with the connection area 52 the connection line 4 be contacted. In a subsequent operation then the wire 54 between the two support elements 42 . 44 through to one on the other end portion 46 of the carrier 38 trained recess 58 guided and redirected there. This deflection area of the wire is in 4 with the reference number 60 Mistake. From this diversion area 60 becomes the wire 54 then to the adjacent area of the winding section 48 guided and then the carrier 38 wrapped until the wire 54 again the connection-side end portion 44 reached. The corresponding end 62 The wire is then connected to the connection area 50 and thus with the connecting cable 6 contacted. A prefixing of the wire winding is possible in that the respective ends 56 . 62 in two recesses 64 . 66 be clamped so that then after mounting the contact with the connecting cables 4 . 6 can be done.

The between the two support elements 40 . 42 passed wire section 68 is opposite to the outer winding through the two plate-shaped micanite support elements 40 . 42 thermally insulated. In case of error, the between the support elements 40 . 42 lying wire section 68 significantly more heat than the outside, from the heat sink 2 cooled winding, so that accordingly also the burn-through in the region of this passage. The burn-through takes place in such a way that immediately forms an interruption point, which is so far that a forming arc is quickly interrupted. This makes the element intrinsically safe, in particular, a physical connection (electrical connection to the housing) is impossible.

Damage to other components by thermal overheating is thus reliably excluded.

5 shows an individual representation of the wound wire 54 , It can be seen between the two support elements 40 and 42 extending wire section 68 which extends through the interior of the winding and with its end 56 with the connection 52 will be contacted. This somewhat obliquely to the winding axis extending wire section 68 is in the field of diversion 60 diverted; the actual winding then extends back to the right in 5 and ends in the slightly sloping end 62 that with the further connection 50 can be contacted.

In the embodiment described above, the wire winding element 22 with the one insulating body forming Mikanitplatten in the receiving space 24 of the insulating body 2 used, wherein the remaining cavity is filled with a filler, such as MgO, to the wire winding element 22 in the recording room 24 to position. This backfilling is relatively expensive. 6 shows an embodiment in which the wire winding element according to the invention 22 with internal feedback and the surrounding micanite insulation panels, of which here the longitudinally arranged insulating panels 30 . 32 and the two bottom plates 70 . 72 are visible in the recording room 24 used and then as in the EP 1 852 878 B1 be described pressed together. In this pressing are the side walls shown 74 . 76 retracted inwardly in the manner shown, so that the wire winding element 22 Reliable positionally positioned with the associated insulating body. In this compression, the windings of the wire in the carrier 38 and / or the floor panels 70 . 72 pressed in, so that a very good heat transfer is ensured. Furthermore, the intimate contacting of the wire with the carrier 38 and the electrically insulating plates of the insulator causes a good heat storage capacity.

Another possibility to dispense with a production-technically complicated filling, is the executed according to the invention with an internal return wire winding element 22 To shed with a heat storage and transmission element. That is, wire winding element 22 is cast with a thermosetting material, which may for example consist of a mixture of MgO and water glass and cures under protective gas atmosphere and temperature. This electrically insulating potting material surrounds the wire winding element 22 making this a "block" in the recording room 24 of the heat sink 2 can be inserted. The attachment can be done for example by pressing or pressing. In principle, it is also possible the wire winding element directly in the receiving space 24 to shed, so that this practically acts as a casting mold. In this case, even the insulating Mikanitplättchen could be dispensed with.

Disclosed is a resistor, preferably a braking, discharging or high-load resistor and a method for producing such a resistor, in which a wire section of a wire winding is thermally insulated from the other wire winding, so that fails in the case of failure, the wire section.

LIST OF REFERENCE NUMBERS

1

 braking resistor

2

 heatsink

4

 connecting cable

6

 connecting cable

8th

 Connection-side closure

10

 cooling fins

12

 recess

14

 cover surface

16

 cover surface

18

 sidewall

20

 sidewall

22

 Wire winding element

24

 accommodation space

26

 shutter

28

 Tile

30

 insulation

32

 insulation

34

 Tile

36

 Tile

37a

 execution

37b

 execution

38

 carrier

40

 support element

42

 support element

44

 end

46

 end

48

 winding section

50

 terminal area

52

 terminal area

54

 resistance wire

56

 The End

58

 recess

60

 deflection region

62

 The End

64

 recess

66

 recess

68

 wire section

70

 baseplate

72

 baseplate

74

 sidewall

76

 sidewall

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1225080 B1 [0003]
• DE 2228460 [0004]
• DE 3703689 C2 [0004]
• EP 1711035 A1 [0005]
• DE 102011001362 A1 [0006, 0042, 0043]
• EP 1852878 B1 [0008, 0051]

Claims (14)

Resistance, preferably braking, discharging or high-load resistance with a wire winding element ( 22 ), the one around a carrier ( 38 ) has wound wire resistance winding whose ends ( 56 . 62 ) with connection areas ( 50 . 52 ) are connectable, characterized in that a wire section ( 68 ) is thermally insulated compared to the other wire winding in relation to the environment, so that in the event of a fault the wire winding element ( 22 ) in this wire section ( 68 ) failed. A resistor according to claim 1, wherein the wire portion ( 68 ) at least in sections from the carrier ( 38 ) is surrounded. Resistor according to claim 1 or 2, wherein the support ( 38 ) two carrier elements ( 40 . 42 ), between which the wire section ( 68 ), while the remaining wire winding substantially around the support elements ( 40 . 42 ) runs. A resistor according to claim 3, wherein the wire winding extends from a terminal side end portion (16). 44 ) of the carrier ( 38 ) away to another end section ( 46 ) and between the support elements ( 40 . 42 ) to the terminal-side end portion ( 44 ) is passed. Resistor according to claim 3 or 4, wherein the support elements ( 40 . 42 ) are plate-shaped. A resistor according to claim 4 or 5, wherein the passage is spaced from the other end portion (Fig. 46 ) of the carrier ( 38 ) towards the connection-side end portion ( 44 ) or is deflected to the winding. Resistor according to Claim 6, in which the deflection ( 60 ) along one in the other end portion ( 46 ) formed recess ( 58 ) he follows. Resistor according to one of the preceding claims, wherein a winding section ( 48 ) of the carrier ( 38 ) opposite the end sections ( 44 . 46 ) is reset. Resistor according to one of the preceding claims, in which the support ( 38 ) consists of micanite or the like.  Resistor according to one of the preceding claims, wherein the wire is formed as a flat wire.  Resistor according to one of claims 1 to 9, wherein the wire is designed as a round wire. Resistor according to one of the preceding claims, in which the support ( 38 ) at the terminal-side end portion ( 44 ) Recesses ( 64 . 66 ) for prefixing the ends ( 56 . 62 ) Has. Resistor according to one of the preceding claims, comprising a heat sink ( 2 ), one of the wire winding element ( 22 ) receiving space ( 24 ), whereby the connection lines ( 4 . 6 ) through a closure ( 8th ) extend therethrough. Resistor according to claim 13, wherein the wire winding element ( 22 ) is embedded in an insulating filling or is pressed with the heat sink or is poured into a heat transfer and storage element.

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