EP2182529B1 - Aluminium load resistor - Google Patents

Abstract

The resistor has a resistor coil (1) embedded in a highly compressed insulated package (10). A metal casing pipe (5) is arranged in a hollow chamber (12) of a cooling body (13) made of aluminum alloy. The hollow chamber is adjusted with respect to the cross-section and length of the metal casing pipe. The metal casing pipe is axially fixed by radial fixing elements (20) such that the metal casing pipe is moved in the chamber depending on temperature without changing axial position by the fixing elements. The fixing elements project the cross-sectional profile of the metal casing pipe.

Description

The invention relates to an aluminum load resistor consisting of at least one resistance coil, which is provided with externally accessible connection wires arranged in a metal casing tube and embedded in a highly encapsulated in the metal casing insulating material and wherein the metal casing tube in a both with respect to its cross-section as well as with respect to its length The dimensions of the metal casing tube matched cavity of an existing aluminum alloy heat sink is arranged and is in contact with this jacket surface in thermal contact.

Aluminum load resistors are known. They are used to destroy surplus electrical energy temporarily generated during idle or overrun operation of machines by transforming them into heat and deliver them to the environment in a suitable way. In this case, very high peak loads can occur for a short time, which can lead to high mechanical stresses of the material. For cost reasons, small, compact designs are generally desired. However, these require a high mechanical strength and resilience of the components. A leading to this goal way is the granulated, z. As consisting of MgO, SiO ₂ or quartz sand insulating material in which the resistance coil is embedded high to compress and keep it free of smallest voids or cracks. Another prerequisite is the high strength of the metal shell, which must withstand the thermal expansion forces of the compacted Isolierstoffmasse.

Such aluminum load resistors may also contain a plurality of interconnected or separately switchable resistance coils.

In aluminum load resistors of this type, there is also the technical problem that the metal casing pipes usually compressed in the heat sinks made of aluminum or aluminum alloys at the pulse-wise maximum loads and the resulting temperature-related Gradually move length changes out of the heat sinks or change their axial position in the heat sink strong. For example, one out DE 20 2007 014 360 U1 known aluminum load resistor with heating cartridge of this type has been tried to counter this problem. It has been proposed there to produce the metal jacket tube and the heat sink of materials with the same thermal expansion coefficient. The material is an aluminum alloy, wherein the metal jacket tube and the heat sink may consist of the same or different aluminum alloys.

The heat sink is provided with a through hole in which the load resistance is pressed tightly with such a metal casing pipe.

The heat sink is formed in several parts from at least two housing parts which are pressed or screwed together for fixed recording of the load resistance with its metal casing pipe. In this case, the metal casing tube may have any cross-sectional shape, in particular, this may be formed annular or rectangular. In practice, it has been found that the above-mentioned technical problem can not be solved satisfactorily in this way.

The invention has for its object to provide a heavy duty aluminum load resistor of the type mentioned, in which the axial displacement of the metal casing tube in the heat sink in a simple manner, i. by simple means, is prevented.

This object is achieved by an Aln load resistor according to claim 1, characterized in that the metal casing tube is fixed axially in the cavity of the heat sink by means of at least one radially projecting into or through the cavity and the cross-sectional profile of the metal casing tube fixing such that the metal casing tube move due to temperature in the cavity can, without changing its predetermined by the fixing axial position.

The particular advantage of this solution according to the invention is that the metal sheath tube of the load resistance in the axial direction of the location of the fixing element in the cavity of the heat sink can expand and shorten, while still always in the same place remains. It is immaterial whether the fixing element is arranged in an end region of the metal casing tube or in the middle and is positively or non-positively clamped with the metal shell in engagement. The temperature-related linear expansion can take place from the location of the projection in both axial directions.

But you can also achieve the same advantage, if instead of only one fixing two radially or in the manner of a circular chord projecting into the cavity of the heat sink fixing so arranged that the metal shell of the load resistance can be arranged with axial clearance between them. In this embodiment of the invention, the thermal expansion of the metal shell can be carried out in both axial directions, without its axial position could change beyond the predetermined tolerance within the cavity.

According to claim 2, the fixing element or the fixing elements may consist of a substantially radially inwardly directed projection, which may be formed differently.

According to claim 3, this projection can for example consist of a radially pressed into the wall of the cavity cams or from a pressed-in the wall of the cavity bead or which is also deepened and thus positively driven into the metal casing pipe.

Instead of the projection or the bead can be provided according to claim 4, a screwed into the wall of the heat sink or the cavity screw.

As already mentioned, it is also possible to arrange the metal casing pipe or the heating cartridge according to claim 5 between two cam-like, bead-like projections with axial play or according to claim 6 between two radially projecting into the cavity of the heat sink screws, so that the metal casing pipe or ., The heating cartridge can expand due to the predetermined axial clearance in the axial direction due to temperature, without changing its predetermined position.

Fig. 1

einen kompletten Lastwiderstand mit einem Alu- miniumgehäuse als Kühlkörper;

Fig. 2

den Alu-Lastwiderstand der Fig. 1 im Schnitt;

Fig. 3

einen vergrößerten Ausschnitt III aus Fig. 2;

Fig. 3a

den gleichen Ausschnitt wie Fig. 3, jedoch mit einem auf andere Weise Fixierelement;

Fig. 4

den Alu-Lastwiderstand der Fig. 1 mit zwei Fi- xierelementen;

Fig. 4a

einen Ausschnitt aus Fig. 4 mit einem sickenar- tigen Fixierelement;

Fig. 5

den Alu-Lastwiderstand der Fig. 4 im Schnitt;

Fig. 6

einen vergrößerten Ausschnitt VI aus Fig. 5;

Fig. 6a

einen vergrößerten Ausschnitt VI aus Fig. 5, jedoch mit einem anders ausgebildeten Fixier- element;

Fig. 7

in 3D-Darstellung einen kompletten Alu- Lastwiderstand mit einem anderen Kühlkörper und einem anderen Fixierelement;

Fig. 8

ein aus einer Querlasche bestehendes Fixierele- ment als Einzelteil;

Fig. 9

einen Längsschnitt durch den Alu-Lastwiderstand der Fig. 7;

Fig. 10

in vergrößerter Darstellung einen Ausschnitt X aus Fig. 9;

Fig. 11

in 3D-Darstellung den Alu-Lastwiderstand gemäß Fig. 7, jedoch mit zwei anderen Fixierelemen- ten;

Fig. 12

einen Schnitt XII-XII aus Fig. 11;

Fig. 13

ein aus einer Querlasche bestehendes Fixierele- ment aus den Fig. 11 und 12 als Einzelteil;

Fig. 14

den Alu-Lastwiderstand der Fig. 11 im Schnitt;

Fig. 15

in vergrößerter Darstellung einen Ausschnitt XV aus Fig. 14;

Fig. 16

einen zweiteiligen Kühlkörper in 3D- Darstellung;

Fig. 17

den dazugehörigen Lastwiderstand als Einzel- teil;

Fig. 18

den aus den beiden Gehäuseteilen der Fig. 16 und dem Lastwiderstand der Fig. 17 zusammenge- setzten Alu-Lastwiderstand in 3D-Darstellung mit einem einzelnen Fixierelement;

Fig. 19

einen Teilschnitt aus Fig. 18;

Fig. 20

den aus den beiden Gehäuseteilen der Fig. 16 und dem Lastwiderstand der Fig. 17 zusammenge- setzten Alu-Lastwiderstand in 3D-Darstellung mit zwei Fixierelementen und vier Verbindungs- schrauben;

Fig. 21

einen Längsschnitt aus Fig. 20;

Fig. 22

den Alu-Lastwiderstand aus Fig. 20 in 3D- Darstellung mit nur zwei zugleich als Fixier- elemente dienenden Verbindungsschrauben;

Fig. 23

den Alu-Lastwiderstand der Fig. 22 in Schnitt- darstellung.

Other ways of forming the fixing or fixing elements are in the dependent claims 7 to 12 indicated. Reference to the drawings, the invention is explained in more detail below. It shows:

Fig. 1

a complete load resistor with an aluminum housing as a heat sink;

Fig. 2

the aluminum load resistance of the Fig. 1 on average;

Fig. 3

an enlarged section III Fig. 2 ;

Fig. 3a

the same section as Fig. 3 but with a fixing element of another type;

Fig. 4

the aluminum load resistance of the Fig. 1 with two fixing elements;

Fig. 4a

a section from Fig. 4 with a bead-like fixing element;

Fig. 5

the aluminum load resistance of the Fig. 4 on average;

Fig. 6

an enlarged section VI Fig. 5 ;

Fig. 6a

an enlarged section VI Fig. 5 , but with a different fixing element;

Fig. 7

in 3D representation a complete aluminum load resistor with another heat sink and another fixing element;

Fig. 8

a Fixierele- consisting of a cross-tab as a single part;

Fig. 9

a longitudinal section through the aluminum load resistor of Fig. 7 ;

Fig. 10

in an enlarged view a section X from Fig. 9 ;

Fig. 11

in 3D representation the aluminum load resistance according to Fig. 7 but with two other fixation elements;

Fig. 12

a section XII-XII off Fig. 11 ;

Fig. 13

a fixing element consisting of a cross-link FIGS. 11 and 12 as a single item;

Fig. 14

the aluminum load resistance of the Fig. 11 on average;

Fig. 15

in an enlarged view a section XV Fig. 14 ;

Fig. 16

a two-part heat sink in 3D representation;

Fig. 17

the associated load resistance as a single part;

Fig. 18

from the two housing parts of the Fig. 16 and the load resistance of the Fig. 17 assembled aluminum load resistor in 3D representation with a single fixing element;

Fig. 19

a partial section Fig. 18 ;

Fig. 20

from the two housing parts of the Fig. 16 and the load resistance of the Fig. 17 assembled aluminum load resistor in 3D with two fixing elements and four connecting screws;

Fig. 21

a longitudinal section Fig. 20 ;

Fig. 22

the aluminum load resistor Fig. 20 in 3D representation with only two connecting screws serving as fixing elements at the same time;

Fig. 23

the aluminum load resistance of the Fig. 22 in sectional view.

The in the Fig. 1 to 3 illustrated aluminum load resistor consists of a resistance coil 1, which is wound on a winding core 2 consisting of insulating raw material and is provided with connecting conductors 3 and 4. The winding core 2 with the resistance coil 1 is in a coaxial position in a cylindrical metal casing tube 5, which is provided at one end with a fixed base 6 and at the other end with a cover plate 7. The cover plate consists of electrical insulating material and it has two axial bores 8 and 9, through which the connection conductors 3 and 4 are led to the outside. The wound on the winding core 2 resistance coil 1 is embedded in a high density Isolierstoffpackung 10, which may consist of quartz sand, magnesium oxide, silica or the like. The object of this insulating material 10 is, on the one hand electrically to isolate the resistance coil relative to the metal jacket tube 5 and on the other hand forward the heat generated by the resistance coil with the least possible time delay to the metal jacket tube 5.

In order to ensure a high load capacity of the load resistor 11, the metal casing pipe 5 is made of stainless steel made, which has a relatively small coefficient of thermal expansion, which is advantageous in that as well as in the heated state, the high degree of compression of the insulating material package can be maintained.

In addition, there is also the possibility of accommodating two or more resistance coils in the metal jacket tube 5 instead of just one resistance coil 1, and to switch them as needed so that they best correspond to the respective requirements.

The thus constructed load resistor 11 is inserted into a, the diameter of the metal casing tube 5 adapted cylindrical cavity 12 of a metal, preferably made of aluminum or an aluminum alloy heat sink 13 so that the load resistor 11 with its metal jacket tube mantelflächig in thermal contact with the wall 17 of the Cavity 12. As in particular from Fig. 1 can be seen, the heat sink 13 a plurality of air chambers 14, through which an enlarged surface is achieved, via which the heat is dissipated to the environment.

How out Fig. 2 can be seen, the heat sink 13 has a greater axial axial length s than the load resistance or its metal jacket tube 5 with the length s1, but this is not necessarily the case and in other embodiments of the invention described below is not the case.

The profile of the heat sink 13 with the air chambers 14 is preferably made in the compression molding process, so that it can be cut off from a long contiguous strand in each case in a suitable length as the heat sink 13. That in the embodiment of the Fig. 1 to 5 the ends of the heat sink 13 are each cut obliquely, is justified by a particular application of the embodiment. Of course, the heat sink 13 may also be provided with plane front ends.

In order to secure the load resistor 11 with its metal casing tube 5 in the heat sink 13 so that the metal casing tube 5 can move axially in the cavity 12 due to temperature, without changing its predetermined axial position, are Fixing elements are provided in all embodiments, which project radially into or through the cavity 12 and the cross-sectional profile of the metal casing tube 5, but can be designed differently.

In the embodiment of the Fig. 1 to 3a only one such fixing element in the form of a radially inwardly directed projection 20 is provided, which is formed from a radially in the wall 17 of the cavity 12 and thus at the same time in the top wall 17 'of the heat sink 13 from above pressed cam 20, which also deepening and thus positively driven into the metal casing tube 5 and the outside forms a blind hole 21. In the metal casing pipe is thereby formed by the cam 20 a matching recess 20 '.

How out Fig. 3a it can be seen, in the metal casing tube 5, the cam-like recess 20 'are also produced by means of a screw 21/1, which is a threaded hole 19' of the top wall 19 is screwed.

It should be mentioned here that the individually applied fixing element, for example formed as a cam 20 or screw 21/1, in principle at each point of the metal casing pipe 5, in particular in the longitudinal center, may be arranged.

In the embodiment of the Fig. 4a instead of the cam or projection 20 produced by a cylindrical punch, a bead-like projection 22 is provided.

In the embodiment of the 4, 5 and 6 are the upper side in the middle of the heat sink 13 are two cam-like projections 20 is provided whose axial distance a is larger than the length s1 of the metal jacket tube 5. The distance a is selected so that the load resistor 11 due to the temperature, with its metal casing 5 between these two cams 20 in the cavity 12 can expand sufficiently, if a corresponding heating takes place, without changing its fixed by the two cams 20 axial position.

Instead of the cam 20 can according to Fig. 6a each one screw 23 may be provided which is screwed into the top wall 19 and has a cylindrical pin 23 'as a fixing element.

As Fig. 5 as well as the FIGS. 6 and 6a show, between the cams 20 and the screws 23 and the end faces of the metal casing tube 5 an axial clearance b1 + b2.

The cams 20 which are each arranged outside the ends of the metal jacket tube 5 as fixing elements represent cross-sectional constrictions of the cavity 12. It is within the range of possible variations to realize the cross-sectional constrictions by simply radial impressions of the wall 17 of the cavity 12. This impressions of the cavity wall 17 can be made in sections or in full.

In the embodiment of the Fig. 7 to 14 the load resistor 11 is inserted with its cylindrical metal casing tube 5 in a heat sink 13/1. This heat sink 13/1 consists of an extruded hollow body with a rectangular cross-sectional profile and two air chambers 14/1, which are arranged symmetrically to a coaxial, cylindrical cavity 12/1. In this cavity 12/1, which is formed by a cylindrical wall 15, there is the load resistor 11 with its cylindrical metal casing tube 5. Here, the diameter of the cavity 12/1 in turn so on the outer diameter of the metal casing tube 5 tuned that a good heat transfer from the load resistor 11 can be made to the heat sink 13/1.

While the flat bottom 16 of the heat sink 13/1 is arranged outside the cylindrical wall 15 and forms a closed surface, the top wall 19/1 has a step 17 with two horizontal bearing surfaces 18. In this case, this gradation 17 is chosen so that the two bearing surfaces 18 lie in a horizontal plane which intersects the otherwise cylindrical cavity 12/1 in the manner of a chord and that the metal casing tube 5 projects beyond these two bearing surfaces 18 upwards with a portion of its cross section.

In the embodiment of the Fig. 7 is provided as a fixing a transverse tab 25 which is fastened by means of two screws 26 on the support surfaces 18 in such a way that it clamps the axial position of the load resistor 11 and the metal casing tube 5 in the axial direction, ie non-positively fixed. To adapt to the cylindrical shape of the load resistor 11 and its metal jacket tube 5, the transverse flap 25 is provided on the underside with a circular arc-shaped recess 27.

Even with this type of fixation it is ensured that the metal casing tube 5 or the entire load resistor 11 in the cavity 12/1 of the heat sink 13/1 can expand or shorten in the longitudinal direction due to temperature, without its predetermined axial position within the heat sink 13/1 to change.

In the embodiment of the Fig. 11 to 15 is a heat sink 13/2 provided, extending from the heat sink 13/1 of FIGS. 7, 9 and 12 only differs in that it has a greater length s2 than the load resistor 11 and its metal jacket tube 5 with the length sl. In addition, instead of the one transverse lug 25 in this embodiment, two transverse lugs 25/1 are provided, each at the ends of the heat sink 13/2 on the bearing surfaces 18 at a distance a (FIG. Fig. 14 ) are arranged so that they receive the metal sheath tube 5 of the load resistor 11 with axial play b1 + b2 between them. Thus, there is also the possibility that the load resistor 11 with its metal casing tube 5 between them two fixing elements 25/1 temperature-induced axial expansion without changing its predetermined by the two transverse straps 25/1 axial position.

In this case, the two transverse straps 25/1 designed somewhat narrower than the cross-tab 25. Their respective facing each other, acting as abutment surfaces for the ends of the metal casing tube 5 side surfaces 28 and 28 'protrude segmentally or chord-like the cavity 12/1.

In the in the Fig. 16 to 23 illustrated embodiments, the heat sink 13/3 consists of two plates 30 and 31, which have on a flat side of a plurality of longitudinal grooves 32, 33, 34 and 35 and a coupling rib 36 existing cross-sectional profile. In this case, the profile is designed so that the congruent joining of these two plates 30 and 31, the coupling ribs each come to lie in the groove formed as a pass groove 35. The two matching grooves 32 form a rectangular cavity 37 and the grooves 33 and 34 respectively ventilation chambers 38 and 39. The cavity 37 serves to accommodate a cross-section adapted rectangular load resistor 11/1, which is constructed analogously to the load resistor 11 and is provided with two frontally outstanding connection conductors 3 and 4. To fix the load resistor 11/1 its metal tube 5/1 rectangular in cross-section, for example, in the end portion of the two connection conductors 3 and 4 on the upper side with a round recess 40 is provided. As a fixing in this case a screw 43 is provided, from which the lower end of its screw shank 41 protrudes positively into this recess 40. The screw 43 is screwed into a threaded bore 42 of the upper plate 30. The screw head 43 is seated in a cylindrical recess 44 of the plate 30. The operation of this fixing element is the same as that of the cam-like projection 20th

With a corresponding shape of the interlocking coupling rib 36 and the associated receiving groove 35, the two plates 30 and 31 may be connected to each other by pressing. But there is also, as in the embodiment of FIGS. 20, 22 and 23 , the possibility of the two plates 30 and 31 by screws 45th or 49 and 50 to connect. In this case, the screws 45 may each be disposed in the corners of the heat sink 13/3 forming plates 30 and 31, as in Fig. 20 represented, or as in the embodiment of FIGS. 22 and 23 in which they are arranged in the longitudinal center.

In both cases, the heat sink 13/3 or the two heat sink 13/3 forming plates 30 and 31 are each provided with a length s which is greater than the length s1 of the load resistor 11/1, so that this with the required axial clearance between the cavity 37 in the vertical direction centrally projecting fixing in the form of dowel pins 47 and 48 or in the form of connecting screws 49 and 50 can be arranged.

While in the embodiment of FIGS. 20 and 21 the two dowel pins 47 and 48 serve exclusively as fixing elements for the intermediate load resistor 11/1 are in the embodiment of FIGS. 22 and 23 the two connecting screws 49 and 50 not only used as fixing in the sense mentioned above, but also used to connect the two plates 30 and 31 together.

Also in the embodiment of FIGS. 22 and 23 are the two connecting screws 49 and 50, which also serve as fixing elements, arranged at a distance a from each other, that the load resistance 11/1 temperature-related unhindered can expand between, without changing its predetermined axial position.

Claims (12)

1. An aluminium load resistor comprising at least one resistor coil (1) which is provided with connecting conductors (3, 4) accessible from the outside and which is arranged in a metallic casing tube (5) and which is embedded in a highly compressed insulator material packing (10), and wherein the metallic casing tube (5) is arranged in a cavity (12) - adapted both with respect to its cross-section and with respect to its length to the dimensions of the metallic casing tube (5) - of a cooling member (13, 13/1, 13/2, 13/3) consisting of an aluminium alloy and is in thermal contact with the latter on its outer surface, characterized in that the metallic casing tube (5) is fixed axially in the cavity (12) of the cooling member (13, 13/1, 13/2, 13/3) by means of at least one fixing element (20, 23, 25, 25/1, 47, 48, 49, 50) projecting radially into or through the cavity (12) and the cross-sectional profile of the metallic casing tube (5), in such a way that the metallic casing tube (5) can move in the cavity (12) in a manner dependent upon the temperature, without changing the axial position thereof which is pre-set by the fixing element (20, 23, 25, 25/1, 47, 48, 49, 50).
2. An aluminium load resistor according to claim 1, characterized in that the metallic casing tube (5) consists of a metal with a low coefficient of thermal expansion, in particular of high-grade steel.
3. An aluminium load resistor according to claim 1, characterized in that the fixing element comprises a projection (20) directed substantially radially inwards.
4. An aluminium load resistor according to claim 1, characterized in that the projection (20) comprises a cam (20) which is pressed radially into the wall of the cavity (12) and which is also driven into the metallic casing tube (5) in a digging in and thus positively locking manner.
5. An aluminium load resistor according to claim 2, characterized in that the projection comprises a screw (23) screwed into the wall (19) of the cooling member (13).
6. An aluminium load resistor according to claim 1 or 2, characterized in that the metallic casing tube (5) is arranged with axial clearance between two cam-like, bead-like or rib-like projections (20, 22).
7. An aluminium load resistor according to claim 2, characterized in that the metallic casing tube (5) of the load resistor (11) is arranged with axial clearance (b1 + b2) between two screws (23) projecting radially into the cavity (12) of the cooling member (13).
8. An aluminium load resistor according to claim 1, characterized in that the fixing element comprises a radial pressure member (25) which rests on the metallic casing tube (5) of the load resistor (11) in a manner fixing it in a non-positively locking manner by means of one or more screws (26).
9. An aluminium load resistor according to claim 1, characterized in that the fixing elements used are in the form of two transverse plates (25/1) which receive between themselves the metallic casing tube (5) of the load resistor (11) in the cavity (12) of the cooling member (13/2) and which are arranged at an axial distance (a) from each other on the cooling member (13/2), which axial distance (a) is greater by at least the temperature-dependent degree of expansion of the metallic casing tube (5) than the length (s1) thereof.
10. An aluminium load resistor according to claim 1, characterized in that the fixing elements provided are in the form of two transverse pins (47, 48) which receive between themselves the metallic casing tube (5) of the load resistor (11) in the cavity (12) of the cooling member (13/3) with axial clearance (b1 + b2) and which, extending in a diametric or chord-like manner, project through the cavity (12) and are fastened in respectively coaxial bores in the cavity wall (17).
11. An aluminium load resistor according to claim 1 with a cooling member comprising two housing parts (30, 31), characterized in that the two housing parts (30, 31) are connected to each other including the load resistor (11) by screws (49, 50) which project through the cavity (12), in which the load resistor (11) is situated, at an axial distance (a) from each other which is greater by at least the temperature-dependent degree of expansion of the metallic casing tube than the length (s1) thereof.
12. An aluminium load resistor according to claim 1, characterized in that the metallic casing tube (5) is arranged between two cross-sectional constrictions of the wall (17) of the cavity (12) with axial clearance.

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