GB2140260A

GB2140260A - Heating apparatus for switchgear cabinets

Info

Publication number: GB2140260A
Application number: GB08406117A
Authority: GB
Inventors: Hans Wagener
Original assignee: Rittal Werk Rudolf Loh GmbH and Co KG
Current assignee: Rittal Werk Rudolf Loh GmbH and Co KG
Priority date: 1983-03-12
Filing date: 1984-03-08
Publication date: 1984-11-21
Also published as: SE8400987L; DE8307274U1; NL191970B; SE8400987D0; NL191970C; GB2140260B; SE452648B; NL8400603A; FR2542554B1; GB8406117D0; FR2542554A1

Abstract

A heating apparatus for switchgear cabinets having heating elements inserted, in a thermally conducting manner, in a metallic member (10), wherein the member has a plurality of longitudinally extending surfaces, outwardly directed, longitudinally extending radiation ribs (11, 12, 13) being formed on all but one of the longitudinal surfaces of the member (10), the heating components being in blind holes formed in the unribbed longitudinal surface and an axial fan (40) which covers the end surface of the member (10) including the radiation ribs (11, 12, 13) being provided on one end face of the contact member. <IMAGE>

Description

SPECIFICATION A Heating Apparatus The present invention relates to a heating apparatus which is chiefly, but not essentially, intended for use in switchgear cabinets. Such an apparatus includes heater elements which are inserted, in a heat-conducting manner, in suitable receiver means formed in a metallic contact member. The contact member has external, longitudinally extending radiation ribs formed thereon.

A heating apparatus of this general type is disclosed in German Gebrauchsmuster No.

80 26 584. In such arrangement, the heater component utilised is a PCT component which is disposed in a thermally conducting relationship with the contact member and thus heats the contact member. The heated contact member radiates some of the heat which is received and heats the interior of a switchgear cabinet. The radiation ribs formed on the contact therefore increase the surface area of the contact member from which heat can be radiated.

If the heater components inserted in the contact member have only a limited heating capacity, it takes a considerable period of time to heat the interior of the switchgear cabinet to a desired temperature. However, once such temperature has been attained, the heating capacity of the heater components is adequate to compensate for the heat losses. Nevertheless, to keep the warm-up time within reasonable limits, the heating capacity and size of known heating apparatuses is usually greatly in excess of normal requirements.

The present invention seeks to provide a heating apparatus which is generally of the above-mentioned type but in which the time for warming-up is considerably shortened whilst still using a heater having a smaller heating capacity than has hitherto been used without increasing, to any significant extent, the overall dimensions of the heater device.

According to the present invention, there is provided a heating apparatus for switchgear cabinets having heating elements inserted, in a thermally conducting manner, in receiver means associated with a metallic contact member, wherein the contact member has a plurality of longitudinally extending surfaces, outwardly directed, longitudinally extending radiation ribs being formed on all but one of the longitudinal surfaces of the contact member, the receiving means for receiving the heating components being in the form of blind holes formed in the unribbed longitudinal surface and an axial fan which covers the end surface of the contact member including the radiation ribs being provided on one end face of the contact member.

By utilising small axial fan of appropriate dimensions, the heat radiation is substantially improved by the provision of radiation ribs on the contact member. Accordingly the heat required for heating the interior of the switchgear cabinet is available in a substantially shorter period of time than has hitherto been possible. The heating capacity of the apparatus can, therefore, be adapted, to the size of the switchgear cabinet in a more optimum manner than hitherto and does not need to be excessively large.

The wiring and connection of the heating elements inserted in the contact member is facilitated if the contact member is parallelepiped in shape and the unribbed longitudinal surface extends along the radiation ribs provided on the adjacent longitudinal surfaces of the contact member vertically extending boundary walls being formed in the end region of the unribbed surfaces, the wall defining groove-like receiver means, the boundary walls being provided, on their externaily facing surfaces, with radiation ribs. The receiver means can accommodate the necessary connection components and a thermostat.

In a preferred embodiment, the connection between the axial fan and the contact member is achieved if the parallelepiped contact member and the radiation ribs formed on the longitudinally extending surfaces thereof-define a square end face, and the radiation ribs extending to the corners of the square having thickened outer end portions, receiver and securing means being provided on such thickened outer end portions. In such an arrangement, the square disposition of the connecting points is advantageous because the axial fan can be mounted on or attached to the contact member in each of its four positions offset by 90 .

In a desirable embodiment, the connecting points are formed on the contact member without limiting the radiation ribs. This is achieved by providing that the contact member has a rectangular cross-section having two longer and two shorter sides, the ribs being provided on each of the longer sides and on the one of the shorter sides, the ends of the ribs on each of the longer sides terminating in a vertical plane, the ribs on each of the two longer sides adjacent the unribbed, shorter, longitudinal face terminating flush with such face and having thickened outer end portions, the thickened end portions being provided with the securing and receiving means radiation ribs which each extend at an angle of substantially 1 350 relative to the adjacent longitudinal surfaces being provided in the transitional regions between each of the longer longitudinal surfaces and the ribbed, shorter longitudinal surface of the contact member, said angled radiation ribs also having thickened end portions and such end portions being provided with securing and receiver means the radiation ribs extending at an angle of 1350 being provided on their surfaces with gradually reducing radiation ribs and the ends of such reduced length ribs all terminating at the periphery of the square defined by the contact member and the radiation ribs.

In an advantageous embodiment, the thickened end portions of the ribs protrude beyond the radiation ribs adjacent thereto and the protruding portions thereof are provided with longitudinally extending grooves for receiving cover plates. By so doing the air flow of the axial fan can be conducted in an appropriate manner through the covered channels between the radiation ribs.

The air stream can be further improved if an axial fan is provided at each of the contact member, one fan being a suction fan and the other being a blower fan.

In order to accommodate the connecting components required for the wiring and connection of the heating elements and a thermostat and to permit such components to be connected to the contact member, a preferred embodiment provides that the unribbed longitudinal surface of the contact member carries longitudinally extending double securing webs which are located between the vertical boundary walls.

Preferably, a thermostat and connecting terminals are secured to the double securing webs of the contact member the connecting cables of the heating elements and of the thermostat being secured to the terminals.

In order to cover the connecting components in a contact-safe manner, a further advantageous embodiment provides that the receiver means defined by the unribbed longitudinal surface of the contact member and the boundary walls is covered by a U-shaped cover plate, the end regions of the boundary walls being provided, on their facing internal surfaces, with shoulder portions on which the U-shaped cover plate is mounted. Moreover, if, as in a yet further preferred embodiment the disposition is such that the central arm of the U-shaped cover plate is provided with securing flanges which protrude beyond the boundary walls of the contact member and carries fixing projection members for the non-rotatable securement of the U-shaped cover plate to the boundary walls.The heating apparatus can thus be secured to the U-shaped cover plate and the fixing projection members ensure non-rotatable retention or support between the contact member and the cover plate.

In order to secure the U-shaped cover plate to the contact member, it is desirable if the lateral arms of the U-shaped cover plate are provided with securing and receiving means which are aligned with the double securing webs of the contact member, one of the lateral arms of the plate being provided with a cable receiving bore.

A further advantage of the heating apparatus according to the invention resides in the fact that the heating capacity can be increased in a simple manner. For this purpose, a plurality of such apparatuses are combined to form a larger heating unit because their heating elements on the contact members are series-connected on the ends thereof. If the air stream is not sufficient to convey the heat radiation from the radiation ribs, then a further embodiment provides that a plurality of such apparatuses can be interconnected by connecting the contact members through the intermediary of axial fans.

One embodiment of the present invention will be further described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is an exploded perspective view of the component parts of a heating apparatus according to the present invention; and Fig. 2 is a view on an enlarged scale relative to Fig. 1, of receiver means for receiving connecting components and a thermostat and which forms part of the apparatus shown in Fig. 1.

As shown in Fig. 1 , the contact member 10 of the heating apparatus is a profiled section which has a basically rectangular cross-section.

Longitudinally extending radiation ribs 11, 1 2 and 13 are provided on two wider longitudinal wall surfaces and on one of the narrow longitudinal wall surfaces of the section. The other narrower longitudinal wall surface of the contact member 10 has no radiation ribs formed thereon. The respective ribs 11 and 13 adjacent the unribbed wall effectively widen such wall because they terminate flush therewith.

At the junction of each of the wider walls with the narrower ribbed wall junction ribs, extending at an angle of 1350 relative to each of the two adjacent walls are provided. The external surfaces of these angled ribs carry shortened radiation ribs 11, 12 and 13, so that a substantially square shape is defined jointly by the contact member 10 and the radiation ribs 11, 1 2 and 1 3.

These angled radiation ribs extending at an angle of 1350, are thickened at their outer ends 20 and carry receiver means 23 in their end regions. The radiation ribs 11 and 13 which terminate flush with the narrow, unribbed longitudinal surface of the contact member 1 0 are also thickened'at their outer ends 24 and provided, in such thickened outer end regions, with further receiver means 26. These receiver means 23 and 26 may be threaded or unthreaded blind bores into which self-tapping threaded screws 48 are inserted. An axial fan 40 is connected to the end of the contact member 1 0 by means of these screws 48. The axial fan 40 has a square surface which covers the end face of the contact member 10 including the radiation ribs 11, 12 and 13. A connecting plate 41 forming part of the fan housing has apertures 42 formed therein which are aligned with the bores 23 and 26. The housing of the fan also includes a sealing plate 43 which has apertures 44 formed therein. The plate 43 is covered by a grid 45 which has eyelet openings 46 and 47 formed therein. Screws 49 are passed through the opening 46 and 47 into the apertures 44. Since the connecting plate 41 and the sealing plate 43 are constructed identically the axial fan 40 can be connected either to a compressed-air outlet or to a compressed-air suction inlet and also to the contact member 10.

The thickened ends 20 and 24 of the radiation ribs protrude slightly beyond the adjacent radiation ribs 11 and 13, 11 and 12 or 12 and 13, respectively and have longitudinal grooves 21,22 and 25 formed in their protruding regions. By means of these grooves, cover plates 27,28 and 29 can be mounted on the contact member 10.

On the three ribbed longitudinal surfaces, therefore, the radiation ribs 11, 12 and 1 3 can be covered so that closed channels are produced between the ribs 11, 12 and 13. The air stream of the axial fan 40 can therefore be blown or sucked through the channels. If the two ends of the contact member 10 are made identical to one another, two axial fans 40 can be mounted on the contact member 10. In such a case, the fans 40 are mounted so that one fan functions as a blower fan whilst the other functions as a suction fan.

The two axial fans 40 then support the air stream which is guided through the channels between the ribs and conducts heat more rapidly away from the radiation ribs 11, 12 and 13. The receiver means that is to say, the bores 23 and 26 formed the contact member 10 may also be used to be connected, in a series arrangement, a plurality of contact members 10 either directly or through the intermediary of axial fans 40.

The unribbed longitudinal surface of the contact member 10, which extends along the radiation ribs 11 and 13, has vertically extending boundary walls 14 and 16 formed in its end regions. These define a groove-like receiver means for receiving connecting components and a thermostat. Such boundary walls 14 and 1 6 are provided with shorter longitudinally extending radiation ribs 15 and 17 on their external surfaces, such that the ribs 1 5 and 1 7 terminate in common planes with the ribs 11 and 13 respectively.Two double securing webs 1 8 and 1 9 are formed on the underside of the contact member 10 between the boundary walls 14 and 1 6. Self-tapping screws may be inserted directly between the two individual webs of the securing web 1 8 or 1 9 to secure connecting components thereto as can be seen in Fig. 2. In such case, the screws 65 and 66 secure two connecting terminals 63 and 64 respectively to the contact member 10. Two heating components 53 and 56, in the form of heating cartridges including a PCT component, are connected, in a heat-conducting manner, to the contact member 10 by means of receiver means 52 and 55 which are, effectively blind bores.The receiver means 52 and 55 are inserted into the unribbed longitudinal surface of the contact member 10 between the double securing webs 18 and 19. The thermostat 58 is mounted on the double securing web 1 9 by means of a screw 59. A screw 60 can therefore be provided to set the disconnection temperature.

The connecting cables or wires 61 and 62 for the thermostat 58 and the connecting cables or wires 54 and 57 for the heating components 53 and 56 can be clamped securely to the connecting terminals 63 and 64.

On the ends of the facing internal surfaces, the boundary walls 14 and 1 6 carry shoulder portions 50 and 51 which accommodate and support a Ushaped cover plate 30. The lateral arms 31 and 32 of the plate are provided with receiver means 34 by means of which the cover plate 30 can be tightly screwed to the double securing webs 1 8 and 1 9. In addition, the lateral arm 32 carries a cable receiving bore 33, through which the mains connection cable for the heating apparatus can be inserted and connected to the connecting terminals 63 and 64. Fixing projection members 38 and 39 are mounted on the central web of the U-shaped cover plate 30 and accommodate, in a non-rotatable manner, the boundary walls 14 and 1 6 together with their respective radiation ribs 1 5 and 17. The position of the cover plate 30 on the contact member 10 is therefore clearly fixed. The central arm of the U-shaped cover plate 30 is provided with lateral securing flanges 35 and 36 which protrude beyond the boundary walls 1 4 and 16 and their radiation ribs 15 and 1 7 respectively. The flanges 36 and 37 are provided with securing bores 37 so that the heating apparatus can be mounted directly on a wall or on a securing bracket which permits the heating apparatus to be securely locked in position on a rail or bar.

Claims

1. A heating apparatus for switchgear cabinets having heating elements inserted, in a thermally conducting manner, in receiver means associated with a metallic contact member, wherein the contact member has a plurality of longitudinally extending surfaces, outwardly directed, longitudinally extending radiation ribs being formed on all but one of the longitudinal surfaces of the contact member, the receiver means for receiving the heating components being in the form of blind holes formed in the unribbed longitudinal surface and an axial fan which covers the end surface of the contact member including the radiation ribs being provided on one end face of the contact member.

2. A heating apparatus as claimed in claim 1, in which the contact member is parallelepiped in shape and the unribbed longitudinal surface extends along the radiation ribs provided on the adjacent longitudinal surfaces of the contact member, vertically extending boundary walls being formed in the end region of the unribbed surfaces, the wall defining groove-like receiver means, the boundary walls being provided, on their externally facing surfaces, with radiation ribs.

3. A heating apparatus as claimed in claim 1 or 2, in which the parallelepiped contact member and the radiation ribs formed on the longitudinally extending surfaces thereof define a square end face, and the radiation ribs extending to the corners of the square having thickened outer end portions, receiver and securing means being provided on such thickened outer end portions.

4. A heating apparatus as claimed in any one of claims 1 to 3, in which the contact member has a rectangular cross-section having two longer and two shorter sides, the ribs being provided on each of the longer sides and on the one of the shorter sides, the ends of the ribs on each of the longer sides terminating in a vertical plane, the ribs on each of the two longer sides adjacent the unribbed, shorter, longitudinal face terminating flush with such face and having thickened outer end portions, the thickened end portions being provided with the securing and receiving means; radiation ribs which each extend at an angle of substantially 1 35C relative to the adjacent longitudinal surfaces being provided in the transitional regions between each of the longer longitudinal surfaces and the ribbed, shorter longitudinal surface of the contact member, said angled radiation ribs also having thickened end portions and such end portions being provided with securing and receiver means, the radiation ribs extending at an angle of 1 35C being provided on their surfaces with gradually reducing radiation ribs and the ends of such reduced length ribs all terminating at the periphery of the square defined by the contact member and the radiation ribs.

5. A heating apparatus as claimed in any preceding claim, in which the thickened end portions of the ribs protrude beyond the radiation ribs adjacent thereto and the protruding portions thereof are provided with longitudinally extending grooves for receiving cover plates.

6. A heating apparatus as claimed in any preceding claim, in which an axial fan is provided at each end of the contact member, one fan being a suction fan and the other being a blower fan.

7. A heating apparatus as claimed in any preceding claim, in which the unribbed longitudinal surface of the contact member carries longitudinally extending double securing webs which are located between the vertical boundary walls.

8. A heating apparatus as claimed in any preceding claim, in which the receiver means defined by the unribbed longitudinal surface of the contact member, and the boundary walls is covered by a U-shaped cover plate, the end regions of the boundary walls being provided, on their facing internal surfaces, with shoulder portions on which the U-shaped cover plate is mounted.

9. A heating apparatus as claimed in claim 8, in which the central arm of the U-shaped cover plate is provided with securing flanges which protrude beyond the boundary walls of the contact member and carries fixing projection members for the non-rotatable securement of the U-shaped cover plate to the boundary walls.

10. A heating apparatus as claimed in claim 8 or 9, in which the lateral arms of the U-shaped cover plate are provided with securing and receiving means which are aligned with the double securing webs of the contact member, one of the lateral arms of the plate being provided with a cable receiving bore.

11. A heating apparatus as claimed in any preceding claim, in which a thermostat and connecting terminals are secured to the double securing webs of the contact member the connecting cables of the heating elements and of the thermostat being secured to the terminals.

1 2. A heating arrangement comprising a plurality of apparatuses as claimed in one of claims 1 to 11, the heating elements of each apparatus being connected in series with one another.

13. A heating arrangement comprising a plurality of apparatuses as claimed in one of claims 1 to 11, the heating elements of each apparatus being interconnected through the intermediary of axial fan.

14. A heating apparatus as claimed in claim 1 constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in' the accompanying drawings.