FI78190C - Device in a choke or in a transformer to effect the so-called cooling - Google Patents

Description

1 78190

A device in a choke or transformer to enhance its cooling. - Anordning i en chossel eller i en transformator för att effektivera dess kylning.

The invention relates to an apparatus in a choke or transformer for enhancing cooling, the choke or transformer comprising a core plate pack, a coil whose ends come outside the core plate pack, a jacket surrounding the core plate pack, a base plate with side edges attached to the side edges and metal end plates, and to the ends of the housing formed by the base plate, and which abut against the end of the coil through a thin insulating layer.

It is known that the ends of the winding of a choke or transformer must be protected against contact by hand in such a way as to prevent the risk of electric shock. Shields made of plastic or other insulating material are usually used for this purpose. The disadvantage of such insulating sheets is that they prevent the ends of the winding from cooling, because it is known that the insulating materials conduct heat very poorly. To avoid overheating, the choke or transformer must be made of a certain size in relation to its nominal VA volume or power. The increase in size, in turn, causes an increase in material costs and an increased need for space, which must be taken into account, for example, when dimensioning luminaires.

It is an object of the invention to provide an apparatus for enhancing the cooling of a choke or transformer so that the physical size of the choke or transformer in relation to its amount or power can be reduced and thus save on material costs and space requirements.

This object is achieved according to the invention in that the end plates are provided with bent or cast ribs placed in the free space between the winding end sides and the end of the core plate stack at a distance from the core plate stack so that cooling air 2 78190 can circulate from both ends of the end plate. the lower edge is located at a small clearance from the base plate, or there are holes or notches at the bottom of the end plate, and there are openings or notches at the top of the end plate or associated sheath edge that open into the spaces between the rib portions and the end of the core plate.

The cooling fins arranged according to the invention do not increase the maximum dimensions of the choke or transformer. Air circulation is also enhanced along the inner surface of the metal plate.

Thus, the invention has realized that, especially if the size of the choke or transformer is greater than about 100 VA (100 W), the additional cost of cooling-enhancing metal plate is remarkably small compared to the amount of winding and magnet material savings that can be achieved with significantly increased cooling area. Preferably, the heat sink is made of aluminum.

In a preferred embodiment of the invention, the cooling fins are made in such a way that the edges of the metal plate are profiled with grooves which increase its surface area. In the arrangement of these grooves, the free spaces on both sides of the end of the coil between the jacket and the side surface of the end part of the coil can be utilized.

In carrying out the invention, the "width / height" dimension of the choke can be increased without the flow rate on both sides of the winding end (chimney effect). At the same time, the air flowing inside the heat sink also cools the windings directly and, above all, the formation of a hot, standing air layer characteristic of the known solutions in the space between the end of the winding and the end insulation is prevented.

With the heat sink structure according to the invention, the cooling efficiency is improved so substantially that the size of the choke or transformer can be decisively reduced, even by tens of percent, compared to the current practice. The reduction in the size of the choke also provides additional savings due to the reduction in the dimensions of the luminaire.

In the following, an embodiment of the invention will be illustrated with reference to the accompanying drawing, in which Fig. 1 shows a vertical longitudinal section of a choke equipped with a device according to the invention, Fig. 2 shows a horizontal section of the same choke and Fig. 3 shows a vertical cross section of the same choke.

Figure 4 shows an alternative embodiment of a choke according to the invention.

The core plate pack of the choke shown consists of E-plates 1 and I-plates 2. The coil 6 is placed between the E-branches and both ends of the coil 6 protrude outside the ends of the core plate pack because the coil has to be wound around the middle E-branch. Regardless of the shape of the plates, the core plate pack is assembled, the structure is characterized by the protrusion of the ends of the coil outside the core plate pack.

The core plate pack with its windings is placed on the base plate 3. At the ends of the base plate 3 there are holes 13 through which the ballast can be fastened to the luminaire body, for example.

A sheath 4 made of a thinner metal plate surrounds the core plate pack with its windings. The edges of the base plate 3 have hook-like bends 3a to which the bends 4a at the edges of the sheath plate 4 adhere.

The ends of the coil 6 must be provided with protective insulation to prevent manual contact. In the invention, however, this protective insulation is implemented in an exceptional manner in connection with the heat sinks of the 4,781,190 stable units, which are described in more detail below.

Attached to the ends of the housing formed by the sheath 4 and the base plate 3 are metal plates 5 which rest against the ends of the winding 6 so that there is only a thin insulating layer in between. This insulating layer may be a separate strip of insulating material or it may be an insulating coating formed on the inner surface of the metal plate 5.

Grooves 7 are profiled at the edges of the metal plate 5, which increase the cooling surface area of the metal plate 5. The grooves 7 do not increase the size of the choke because they are located in the free spaces on both sides of the end of the coil between the side surface of the jacket 4 and the end part of the coil 6. At the same time, the outer edge of the groove 7 can act as a fastening member for fastening to the end edge of the sheath 4. This fastening can take place in many different ways, e.g. by bending one edge around the other, spot welding the opposing surfaces together or mechanically shaping the opposing edge surfaces.

In the non-sheathed embodiment of Figure 4, the heat sink may be attached to a coil body or core plate pack or glued to a coil.

An air circulation opening or openings 9 are provided between the lower edge of the metal plate 5 and the base plate 3, and an air circulation opening or openings 8 are provided between the upper edge of the metal plate 5 and the end edge of the sheath 4. In this case, air flows around the ends of the coil. is the height dimension B of the choke in relation to its width A. The opening or openings 9 can be made by placing the lower edge of the metal plate 5 at a small clearance from the base plate 3 or by making holes or notches in the lower edge of the metal plate 5. Correspondingly, openings or notches 8 are made in the upper edge of the metal plate 5 or in the associated edge of the sheath 4.

s 78190

Figure 4 shows alternative profiles 7 1, 7 "and 7 '" of cooling fins.

Claims (2)

6,78190 An apparatus in a choke or transformer for enhancing cooling, the choke or transformer comprising a core plate pack (1, 2), a coil (6) having ends outside the core plate pack, a jacket (4) surrounding the core plate pack, a base plate ( 3), to the side edges (3a) of which the edges (4a) of the sheath are attached and metal end plates (5) fixed to the ends of the housing formed by the sheath (4) and the base plate (3) and resting against the end of the coil (6) in a thin insulating layer ( 10), characterized in that the end plates (5) are provided with bent or cast rib sections (7) placed in the free space between the end sides of the coil and the end of the core plate stack at the end of the core plate stack (1, 2) so that cooling air can circulate on both sides of the end plate, for which the lower edge of the end plate (5) is located at a small clearance (9) from the base plate (3) or there are holes or notches (9) in the lower edge of the end plate (5) and the end plate (5) the upper edge or the associated edge of the jacket (4) has openings or notches (8) which open into the spaces between the rib parts (7) and the end of the core plate stack (1, 2). Device according to Claim 1, characterized in that the cooling fins are grooves (7) profiled at the edges of the end plate (5), which increase the surface area of the plate and are located in free spaces on either side of the end of the coil (6) and the coil (6). ) between the side surface of the end part and the outer edges of the grooves (7) of which are bent parallel to the casing (4) and fixed to the inner surface of the casing.