JP2006288117A - Switching unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching unit which improves compactness and heat dissipation. <P>SOLUTION: The switching unit 10 is surrounded by a casing 20, and includes a unit main body 15 with a switching device 13 mounted on a surface at a side of a circuit board 11 in which the circuit board 11 and a busbar circuit 12 adhere, and a terminal 12A extended outside the casing 20 from the unit main body 15. Moreover, the switching device 13 has a maximum area in the busbar circuit 12, and is connected to a busbar 12M which has a larger area than a projected area of the switching device 13, by which heat generated at the switching device 13 is easily absorbed into the busbar 12M, and the absorbed heat is quickly diffused to a wider region than the projected area of the switching device 13, by which heat generation density is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a switching unit capable of controlling current on / off.

As a conventional switching unit, for example, there is one shown in Patent Document 1. This is, for example, arranged between a power source such as an automobile battery and each electronic device such as a headlamp, and controls each electronic device by switching on / off of a current. In addition, these switching units are provided with connection terminals for connection to the outside, and are used as detachable units for maintenance and the like.
JP 2002-324478 A

By the way, in recent years, comfort and safety required for automobiles are increasing, and the number of electronic devices installed in automobiles to meet these demands tends to increase. If it does so, there existed a problem that the number of switching units, such as a relay for controlling the increased electronic device, also increased, and the space was required by that much. In addition, in the case of a detachable switching unit, the installation location is restricted, such as the mounting location is exposed to the outside, and it must be installed in a detachable location. It becomes prominent. Due to these problems, there has been a desire to make the switching unit as small as possible.
In addition, as the number of electronic devices installed in automobiles increases, the amount of power consumed by the entire vehicle increases, and if it is simply downsized, the heat generation density increases and heat accumulates, which may adversely affect electronic devices. there were.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to provide a switching unit that can be reduced in size and improved in heat dissipation.

  As a means for achieving the above object, an invention according to claim 1 is a switching unit comprising a switching device capable of controlling on / off of current and a connection terminal for connection to the outside. A circuit body formed by connecting the switching device to both the circuit board and the bus bar circuit that are in close contact with each other via a casing, and a casing that houses the circuit body, wherein the connection terminal is an end of the bus bar circuit. The bus bar connected to the switching device is formed so as to have an area larger than that of the other bus bars.

  According to a second aspect of the present invention, there is provided a switching unit comprising a switching device capable of controlling on / off of current and a connection terminal for connection to the outside, and a circuit board and a bus bar which are in close contact with each other via an insulator. A circuit body formed by connecting the switching device to both the circuit, and a casing for housing the circuit body, and the connection terminal extends integrally to an end of the bus bar circuit, and It is characterized in that the area of the bus bar to which the switching device is connected is larger than the projected area of the switching device on the bus bar.

  The invention according to claim 3 is characterized in that, in the apparatus according to claim 1 or 2, heat radiation means for cooling the circuit body is provided in close contact.

<Invention of Claim 1>
Since the circuit board and bus bar circuit are provided inside the switching unit, a complicated circuit that would increase in size when formed with the bus bar circuit is formed with the circuit board, and the input / output circuit and the connection terminal are connected to the bus bar circuit. Therefore, the structure for the internal circuit of the switching unit can be reduced in size.
Further, since the switching device is mounted on the bus bar having a large area, the heat generated in the switching device is easily absorbed by the bus bar and can be diffused over a wide range.
Thereby, in this invention, the heat dissipation can be improved while reducing the size of the entire switching device.

<Invention of Claim 2>
Since the circuit board and bus bar circuit are provided inside the switching unit, a complicated circuit that would increase in size when formed with the bus bar circuit is formed with the circuit board, and the input / output circuit and the connection terminal are connected to the bus bar circuit. Therefore, the structure for the internal circuit of the switching unit can be reduced in size.
In addition, since the bus bar to which the switching device is connected has a larger area than the projected area of the switching device onto the bus bar, the heat generated by the switching device can be quickly diffused to a region larger than the projected area of the switching device. Further, it is possible to reduce the heat generation density and further improve the heat dissipation.
As a result, the switching device can be reduced in size and heat dissipation can be improved.

<Invention of Claim 3>
Since the heat dissipation means for cooling the circuit body is provided, the heat dissipation of the switching unit is further improved.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the switching unit 10 has a unit main body (corresponding to a “circuit body” of the present invention) 15 surrounded by a casing 20, and extends from the unit main body 15 to the outside of the casing 20. The connecting terminal 12A to be connected to the counterpart connection terminal (not shown) is detachably attached to an electrical connection box (not shown) or the like.

The unit body 15 is formed by mounting the switching device 13 on the surface on the circuit board 11 side where the circuit board 11 and the bus bar circuit 12 are in close contact (see FIG. 2).
The switching device 13 is capable of controlling on / off of current, and in this embodiment, a semiconductor switching element is used. In particular, in this embodiment, a power MOSFET portion and an overheat protection function or A control unit having a PWM signal oscillating unit and the like arranged on one chip is used.

  As shown in FIG. 1, the circuit board 11 includes a printed circuit in which a conductive path is formed on a substantially rectangular insulating substrate by screen printing or the like, and a through hole 11 </ b> A is formed at a predetermined position. The electronic device mounted on the surface of the switching device 13 or other resistor or other circuit board 11 is connected directly to the bus bar circuit 12 described below through this through hole 11A (see FIG. 2). ). In this embodiment, the switching device 13 is mounted on one side (the right side in FIG. 1) of the circuit board 11, and a control system circuit is arranged on the opposite side (the left side in FIG. 1) (not shown in detail). Has been established.

The bus bar circuit 12 is formed in a predetermined circuit shape by a plurality of bus bars formed by punching a metal flat plate (see a broken line in FIG. 1). The bus bar circuit 12 has a substantially rectangular shape similar to that of the circuit board 11, and the strength of the unit main body 15 can be secured by supporting the almost entire area of the circuit board 11 with the bus bar circuit 12. ing.
Further, the bus bar constituting the bus bar circuit 12 is integrally formed with a connection terminal 12A extending from the unit body 15, and the connection terminal 12A is fitted to a mating connection terminal such as an electric connection box (not shown). It is possible. In the present embodiment, as shown in FIG. 1, five connection terminals 12A are provided. Of these, the left three in FIG. 1 are used as control system terminals, and the right two terminals are power systems. Used as a terminal. Moreover, the front-end | tip part of the control system terminal (three terminals on the left side of FIG. 1) is formed thinner than the power system terminals (two terminals on the right side of FIG. 1) by press working.

  As shown in FIG. 2, a heat radiating plate (corresponding to “heat radiating means” of the present invention) 25 is provided below the unit main body 15. The heat radiating plate 25 is an aluminum metal plate and is bonded to the lower surface of the bus bar of the unit body 15 by applying an adhesive (for example, a silicone-based adhesive or an epoxy-based adhesive) or an adhesive sheet (for example, an adhesive on both sides of the insulating sheet). The heat generated in the unit main body 15 is transferred through the bus bar circuit 12 and released to the outside. These adhesives can further improve heat conductivity by using a material containing a material having high thermal conductivity such as alumina filler.

The casing 20 has a substantially rectangular parallelepiped shape as a whole, and a lower part of the surface of the main body 21 on the side from which the connection terminal 12A is led out (left side in FIG. 2) can be closed with a separate lid body 22. .
The cover 22 has a groove 22A formed at a position where the connection terminal 12A is led out, and the connection terminal 12A can be led out from the casing 20 without a gap by fitting the connection terminal 12A into the groove 22A (see FIG. 3).
In addition, the casing 20 has an opening 20A on the surface corresponding to the heat sink 25 attached to the unit body 15 (the lower side in FIG. 2), and the heat sink 25 is exposed to the outside through the opening 20A. It is designed to increase heat dissipation.

Moreover, the insulating member 30 is arrange | positioned between the heat sink 25 in the base end part from the unit main body 15 of 12 A of connection terminals (refer FIG. 2).
The insulating member 30 is formed in a substantially prismatic shape with an insulating resin, and is fitted into a notch 26 formed at the end of the radiator plate 25 on the connection terminal 12A side (left side in FIG. 2). ing. The notch 26 is formed by cutting into a substantially prismatic shape in accordance with the shape of the insulating member 30 over the width direction of the heat radiating plate 25, and by fitting the insulating member 30, the upper surface (bus bar) The attachment surface of the circuit 12 is substantially flush with the upper surface of the insulating member 30. As a result, even when the upper surface of the heat radiating plate 25 and the lower surface of the bus bar circuit 12 are bonded, the bonding can be reliably performed without causing a step or the like. Even when a current flows through the connection terminal 12A, the insulating member 30 is interposed between the base end portion of the connection terminal 12A and the heat sink 25, so that the connection terminal 12A and the heat sink 25 are interposed between them. A short circuit or the like does not occur.

Now, in the switching unit 10 according to the present embodiment, as shown in FIG. 4, the bus bar 12M to which the switching device 13 is connected (shown by a one-dot chain line in FIG. 4) is shown by a two-dot chain line in FIG. The switching device 13 is formed so as to have a larger area than the projected area of the bus bar circuit 12 with respect to the bus bar circuit 12, and is formed so as to have a larger area than the other bus bars. It is formed so as to have the largest area in the bus bar to be configured.
As a result, the heat generated in the switching device 13 is absorbed by the bus bar 12M, which is a metal, and can be transferred to a region wider than the projected area of the switching device 13.

Then, the switching unit 10 configured as described above is detachably assembled to an electrical connection box (not shown), receives a predetermined electrical signal from the control system terminal, and operates the switching device 13 to generate power. The current input from the input side of the system terminal is appropriately adjusted and output from the output side of the power system terminal to operate the electronic device (not shown).
Note that the switching unit 10 can be removed during maintenance of an electrical connection box (not shown) or the like, and can be replaced and used as necessary.

Thus, according to the switching unit 10 of the present embodiment, the circuit board 11 and the bus bar circuit 12 are provided inside the switching unit 10. As a result, a complicated circuit such as a control system circuit that would increase in size when formed by the bus bar circuit 12 is formed on the circuit board 11, and a circuit for input / output and the connection terminal 12 </ b> A are integrated by the bus bar circuit 11. Since it forms, the structure for the circuit inside the switching unit 10 can be reduced in size.
Further, the switching device 13 is connected to the bus bar 12M having the largest area in the bus bar circuit 12 and having an area larger than the projected area of the switching device 13. Thereby, the heat generated in the switching device 13 is easily absorbed by the bus bar 12M, and the absorbed heat can be quickly diffused to a region wider than the projected area of the switching device 13, thereby reducing the heat generation density.
Therefore, in the switching unit 10 of the present embodiment, it is possible to improve heat dissipation while reducing the size of the entire switching unit 10.

  Further, in the present embodiment, since the heat radiating plate 25 is provided in close contact with the unit main body 15 and the heat radiating plate 25 is exposed to the outside from the opening 20A of the casing 20, the heat dissipation can be further improved.

  In addition, regarding the unit main body 15, for example, in the process before the mounting of the heat sink 25 in the manufacturing process, the strength is insufficient only by the circuit board 11, but in the unit main body 15 of the present embodiment, the circuit board 12 is almost entirely. Since the bus bar circuit 12 is pasted, sufficient strength can be ensured with the unit body 15 alone.

  In the present embodiment, since a semiconductor switching element is used for the switching device 13, operation noise generated when the contact is turned on / off is not generated in a so-called mechanical relay.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) Although the switching unit is housed in the box-shaped casing 20 in the above embodiment, the present invention is not limited to this. For example, the switching unit may include a casing integrally formed by molding. Further, in this case, the casing 20 and the insulating member 30 may be integrally molded. According to such a case, the number of parts can be reduced and the manufacturing process can be shortened, so that the manufacturing efficiency can be improved. Further improvement.
In this case, the molded casing 20 has a structure in which one surface of the heat radiating means (heat radiating plate) is a wall surface of the switching unit, or a structure in which the entire surface of the heat radiating plate is enclosed with a mold resin. Moreover, the structure which used the multiple surfaces of the heat sink as the wall surface may be sufficient.
(2) Moreover, the heat dissipation of the whole casing 20 may be improved by using resin which added fillers, such as an alumina, to resin which comprises a casing.
(3) In the said embodiment, although the heat sink 25 was exposed outside the casing 20, it is not restricted to this, You may accommodate a heat sink in the inside of a casing. In such a thing, among the inner walls of the casing 20, the inner wall with which the heat sink abuts may be made thinner than others. Thereby, heat dissipation can be improved.
(4) Although the heat radiating plate 25 is provided in the above embodiment, the present invention is not limited thereto, and the heat radiating means such as the heat radiating plate 25 may not be provided.
(5) In the above embodiment, the switching unit 10 mounts a semiconductor switching element on the switching device 13, but the present invention is not limited to this, and an IC or the like may be mounted, for example.
(6) In the above embodiment, an IC, a microcomputer or the like may be mounted on the control system circuit.
(7) In the said embodiment, in order to increase a thermal radiation area further, the thing of the structure which adds thermal radiation means, such as a thermal radiation fin, to a thermal radiation plate may be used.
(8) Although the semiconductor switching element is used for the switching device 13 in the above embodiment, the present invention is not limited thereto, and a bare chip or the like may be mounted.
(9) Although the casing 20 is made of resin in the above embodiment, it may be made of metal, for example. In this case, for example, it is desirable that the insulation between the casing and the unit body is achieved by forming an insulating film on the surface of the metal casing.

Plan sectional view of the switching unit of Embodiment 1 Vertical section of switching unit A plan view of the switching unit viewed from the terminal fitting lead-out direction Plan view of circuit board and busbar circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Switching unit 11 ... Circuit board 12 ... Bus bar circuit 12A ... Connection terminal 12M ... Bus bar 13 ... Switching device 15 ... Unit main body (circuit body)
20 ... casing 25 ... heat sink (heat dissipating means)

Claims (3)

In a switching unit comprising a switching device capable of controlling on / off of current and a connection terminal for connection to the outside,
A circuit body in which the switching device is connected to both the circuit board and the bus bar circuit which are in close contact with each other via an insulator;
A casing for housing the circuit body,
The connection terminal is integrally extended to the end of the bus bar circuit,
The switching unit is characterized in that the bus bar to which the switching device is connected is formed to have a larger area than other bus bars. In a switching unit comprising a switching device capable of controlling on / off of current and a connection terminal for connection to the outside,
A circuit body in which the switching device is connected to both the circuit board and the bus bar circuit which are in close contact with each other via an insulator;
A casing for housing the circuit body,
The connection terminal is integrally extended to the end of the bus bar circuit,
An area of a bus bar to which the switching device is connected is larger than a projected area of the switching device on the bus bar. The switching unit according to claim 1, further comprising a heat dissipating unit for cooling the circuit body.

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