JP2009188054A - Electric junction box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric junction box capable of suppressing local high heat generation inside its casing. <P>SOLUTION: An electric junction box comprises a casing 13, a circuit board 14 provided in the casing 13, a plurality of first switching elements 49 mounted on the circuit board 14 to feed electric power and shut off electric power to a plurality of long-term loads 45 which are used continuously for a comparatively long time period, and a plurality of second switching elements 50 provided next to the first switching elements 49 on the circuit board 14 to feed electric power and shut off electric power to a plurality of short-term loads 48 which are used for a comparatively short time period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrical junction box that accommodates a circuit board.

  Conventionally, the thing of patent document 1 is known as an electrical junction box. The electrical junction box includes a casing, a circuit board accommodated in the casing, and a switching element mounted on the circuit board. The electrical junction box is mounted on a vehicle and performs energization and disconnection of the in-vehicle electrical components.

When energization of the in-vehicle electrical component is performed, heat is generated from the switching element. After this heat is dissipated around the switching element, it is transferred to the casing and is dissipated from the casing to the outside.
JP 2003-164039 A

  In recent years, miniaturization is required for electrical junction boxes. When the electrical junction box is downsized, it is necessary to reduce the space for accommodating the switching element. This increases the mounting density of the switching elements. Then, there is a concern that the heat generated from the switching element when energization is performed on the vehicle-mounted electrical component is trapped around the switching element and locally becomes high temperature.

  The above-mentioned in-vehicle electrical components include a long-term load that is continuously used for a relatively long time and a short-term load that is used for a relatively short time. A switching element that performs energization and disconnection of a long-term load generates a larger amount of heat than a switching element that performs energization and disconnection of a short-term load. For this reason, there is a concern that the vicinity of the switching element connected to the long-term load may be locally high.

  This invention is completed based on the above situations, Comprising: It aims at providing the electrical junction box by which the inside of the casing was suppressed from becoming high temperature locally.

  The present invention is an electrical junction box, a casing, a circuit board accommodated in the casing, and a plurality of long-term loads mounted on the circuit board and continuously used for a relatively long time. A plurality of first switching elements that perform energization and disconnection, and a plurality of short-term loads that are mounted on the circuit board adjacent to the first switching elements and are used for a relatively short time. A plurality of second switching elements that perform energization and power interruption.

  The long-term load includes one that continues to be energized from the start of use until it is stopped. Further, the long-term load includes, for example, PWM control in which energization and disconnection are repeated intermittently by a pulse signal from the start of use until it is stopped.

  When energization of the long-term load and the short-term load is performed, heat is generated from the first switching element and the second switching element. At this time, the long-term load is continuously used for a relatively long time, whereas the short-term load is used only for a relatively short time. Therefore, the first switching element is compared with the second switching element. The calorific value is large.

  According to the present invention, the second switching element is mounted at a position adjacent to the first switching element. Thereby, the heat generated from the first switching element is dissipated to the substrate pattern and the space on the second switching element side. As a result, it is possible to suppress heat from being trapped in the vicinity of the first switching element. Thereby, it can suppress that the vicinity of the 1st switching element becomes high temperature locally.

Moreover, as an embodiment of this invention, the following structures are preferable.
A plurality of fuse side terminal fittings connectable to fuses are concentrated on the circuit board, and the first switching element and the second switching element may be arranged in the vicinity of the fuse side terminal fittings. Good.

  According to said structure, the fuse which can be connected with a fuse side terminal metal fitting is concentratedly arrange | positioned in an electrical-connection box. As a result, maintainability at the time of fuse replacement is improved as compared with the case where the fuses are distributed and arranged.

  Of the wall portions constituting the casing, at least one of the wall portions facing the plate surface of the circuit board is a heat radiating wall portion, and heat conduction is performed between the heat radiating wall portion and the circuit board than air. A filler with a large rate may be filled.

  According to the above configuration, the heat generated from the first switching element and the second switching element is transferred from the circuit board to the filler. The heat transferred to the filler is soaked by diffusing into the filler. Thereby, it can further suppress that the vicinity of the 1st switching element becomes high temperature locally.

  Furthermore, the heat transferred to the filler is transferred from the filler to the heat radiating wall, and then dissipated from the heat radiating wall to the outside of the electrical junction box. Thereby, the heat dissipation of an electrical junction box can be improved.

  The filler may be in contact with the first switching element and the second switching element.

  According to said structure, since the heat | fever generate | occur | produced from the 1st switching element and the 2nd switching element is directly transmitted to a filler, soaking | uniform-heating property can be improved further.

  According to the present invention, it is suppressed that the inside of an electric junction box becomes high temperature locally.

  An embodiment in which the present invention is applied to an electric junction box 10 for a vehicle will be described with reference to FIGS. As shown in FIG. 6, the electrical connection box 10 is connected between a battery 11 and an in-vehicle electrical component 12 such as a headlight and a horn, and executes energization and disconnection of various in-vehicle electrical components 12.

  In the following description, the upper side in FIG. 2 is the upper side, and the lower side is the lower side. Further, the right side in FIG. 2 is the right side, and the left side is the left side. Further, a front side in the penetration direction of the paper surface in FIG. 2 is a front side, and a back side in the penetration direction of the paper surface is a back side.

(Casing 13)
As shown in FIG. 3, the electrical junction box 10 is configured by housing a circuit board 14 in a flat casing 13. The casing 13 includes a synthetic resin case body 15 having an opening on the front side (right side in FIG. 3) and a synthetic resin cover 16 that closes the opening of the case body 15.

  As shown in FIG. 3, the case main body 15 has a shallow container shape. The case body 15 includes a back wall 17 (corresponding to a heat radiating wall portion) located on the back side (left side in FIG. 3), an upper wall 18 located on the upper side, and a lower wall 19 located on the lower side. As shown in FIG. 4, the case main body 15 includes a pair of side walls 20 that protrude from the back wall 17 to the front side (direction penetrating the paper surface in FIG. 4) on both the left and right sides of the back wall 17.

  As shown in FIG. 3, the cover 16 has a shallow container shape. The cover 16 has a front wall 51 located on the front side (the right side in FIG. 3). The cover 16 has a plurality of lock portions 21 (see FIG. 4) provided on the outer surface of the side wall 20 of the case body 15 and a plurality of lock receiving portions 22 provided at positions corresponding to the lock portion 21 in the cover 16. (Refer to FIG. 1 and FIG. 2) is elastically engaged with the case body 15 and attached to the case body 15.

(Circuit board 14)
A conductive path (not shown) is formed on the circuit board 14 by a printed wiring technique. As shown in FIG. 3, on the surface of the circuit board 14 (the right side surface in FIG. 3), the switching element 23 is disposed in the above-described conductive path by, for example, soldering. The lead terminal 24 of the switching element 23 is electrically connected to a conductive path formed on the circuit board 14. As the circuit board 14, for example, a thick film board formed by laminating insulating boards on which conductive paths are formed may be used.

  The back wall 17 of the case body 15 is provided with a support boss 25 that protrudes to the front side (right side in FIG. 3) and supports the circuit board 14 from the back side (left side in FIG. 3). The circuit board 14 abuts against the support boss 25 from the front side (right side in FIG. 3), and is arranged so as to overlap the back wall 17 with a clearance from the back wall 17 of the case body 15. The circuit board 14 and the case body 15 are fixed by screwing bolts 26 </ b> A to the support bosses 25 via the circuit board 14.

  In a position near the lower end of the circuit board 14 in FIG. 3, a connector housing 27 made of a synthetic resin and having a horizontally long shape is disposed. In the present embodiment, the connector housing 27 is a board connector that is used by being attached to the circuit board 14. The connector housing 27 includes a hood portion 28 that opens downward in FIG. 3 and can be fitted to a mating connector (not shown). A connector terminal 29 that penetrates in the vertical direction in FIG. 3 and protrudes into the hood portion 28 is disposed on the back wall of the hood portion 28.

  As shown in FIG. 3, the connector housing 27 is provided with a bolt receiving portion 30 into which a bolt 26 </ b> B penetrating the circuit board 14 is screwed from the back side (left side in FIG. 3) of the circuit board 14. The connector housing 27 is fixed to the circuit board 14 by screwing the bolt 26 </ b> B into the bolt receiving portion 30.

  A housing recess 31 for housing the connector housing 27 is formed in the lower wall 19 of the case body 15 so as to be recessed toward the back wall 17. A connector housing 27 is housed in the housing recess 31. A groove portion 33 for accommodating the packing 32 is formed at a position facing the accommodating recess 31 in the connector housing 27. The packing 32 is accommodated in the groove 33, and the packing 32 comes into close contact between the inner surface of the groove 33 and the accommodating recess 31, whereby the case body 15 and the connector housing 27 are sealed.

  As shown in FIG. 3, a portion of the connector terminal 29 that protrudes upward from the connector housing 27 in FIG. 3 is bent at a substantially right angle toward the circuit board 14 and is inserted into a through hole 34 </ b> A formed in the circuit board 14. For example, it is electrically connected to the conductive path of the circuit board 14 by being soldered. The connector terminals 29 are arranged in two stages in the front and back direction (left and right direction in FIG. 3), and a plurality of connector terminals 29 are arranged in the left and right direction (direction passing through the paper surface in FIG. 3).

  The connector terminal 29 penetrates through the through hole 34 </ b> A and protrudes to the back side of the circuit board 14. In the back wall 17 of the case main body 15, a relief recess 35 is formed in a position corresponding to the connector terminal 29, which is recessed on the back side (left side in FIG. 3) and escapes from the tip of the connector terminal 29.

  As shown by a two-dot chain line in FIG. 3, a space surrounded by the back wall 17, the side wall 20, the upper wall 18, the lower wall 19, and the connector housing 27 of the case body 15 is, for example, a synthetic resin material. And is filled with a filler 36 having a higher thermal conductivity than air. The filler 36 is filled in the clearance recess 35 of the case body 15 and in a gap formed between the circuit board 14 and the back wall 17 of the case body 15. Further, the surface of the circuit board 14 is covered with a filler 36, and the filler 36 is in contact with the switching element 23.

  A plurality of fuse-side terminal fittings 37 are arranged on the circuit board 14 at positions near the upper end in FIG. As shown in FIG. 4, the fuse-side terminal fittings 37 are concentratedly arranged in a state of being aligned in the left-right direction along the upper edge of the circuit board 14. The plurality of fuse-side terminal fittings 37 are held in a posture aligned with a synthetic resin holder 38.

  The fuse-side terminal fitting 37 is generally L-shaped. One end of the fuse side terminal fitting 37 is held by the holder 38 in a posture facing the back side. One end of the fuse-side terminal metal fitting 37 is soldered in a state of being inserted into a through hole 34B formed in the circuit board 14 and electrically connected to the conductive path of the circuit board 14.

  The other end of the fuse-side terminal fitting 37 is held by the holder 38 in a posture facing upward. The other end of the fuse-side terminal fitting 37 is connected to a fuse 39 described later.

  As shown in FIGS. 3 and 4, the upper end portion (the other end portion) of the fuse-side terminal fitting 37 is accommodated in each of a plurality of fuse mounting portions 40 that open in the vertical direction on the upper wall 18 of the case body 15. Is done. A fuse 39 is accommodated in the fuse mounting portion 40 so that it can be inserted and removed. By inserting the fuse 39 into the fuse mounting portion 40, the fuse 39 and the fuse-side terminal fitting 37 are electrically connected.

(Switching element 23)
FIG. 6 is a block diagram showing an electrical connection structure of the electrical junction box 10 according to the present embodiment. In the figure, the battery 11 shown at the left end and the power terminal 41 of the electrical junction box 10 are connected. The power supply terminal 41 is connected to a conductive path in the electrical junction box 10. The conductive path is branched into a plurality (seven in this embodiment), and each branch 42 is connected to a plurality (seven in this embodiment) of switching elements 23.

  Among the switching elements 23, the three switching elements 23 from the top in FIG. 6 are constituted by semiconductor relays 54. The semiconductor relay 54 includes a pair of power terminals 43 that are connected to the power supply terminal 41 and constitute a power circuit. One of the power terminals 43 is connected to the branch path 42, and the other is connected to a wire harness 44 outside the electrical connection box 10 via the fuse 39. The wire harness 44 is connected to a plurality of long-term loads 45 that are continuously used for a relatively long time. Further, the semiconductor relay 54 includes a control terminal 46 for controlling the on / off of the semiconductor relay 54. The control terminal 46 is connected to an external circuit of the electrical junction box 10 and is connected to the ground via the switch 47. The long-term load 45 is disposed outside the casing 13 in the vehicle.

  The long-term load 45 includes one that continues to be energized from the start of use until it is stopped. Further, the long-term load 45 includes, for example, PWM control, in which energization and disconnection are repeated intermittently by a pulse signal from the start of use until it is stopped. Examples of the long-term load 45 include a headlight, an EFI power source, a fuel pump motor, a cooling fan, and an air conditioner magnet clutch. These long-term loads 45 are continuously used for a relatively long time after a driver or a CPU (not shown) instructs the long-term load 45 to start using the long-term load 45. It has become.

  The headlight is continuously used, for example, from when the driver turns on the lighting switch 47 to when the driver turns it off. In particular, when traveling at night, the light is kept on for a relatively long time. Further, in recent years, there are cases where the lights are turned on even in the daytime (so-called DRL, daytime running lights). In this case, the headlights are turned on for a relatively long time even during daytime running. During daytime lighting, there are some devices that are driven by high-speed on / off switching at several tens to several hundreds of hertz by PWM control, thereby supplying power to the headlights. The case where the headlight is turned on by PWM control as described above is also included in the case of continuous use.

  The EFI power supply and the fuel pump motor are continuously used from when the driver turns on the ignition switch until it is turned off. That is, the EFI power supply and the fuel pump motor are used for a relatively long time while the vehicle is running.

  The cooling fan is driven by the CPU when the CPU acquires the water temperature of the engine cooling water from a sensor (not shown) and the CPU detects that the water temperature is equal to or higher than a predetermined temperature. This cooling fan is continuously used until the CPU obtains a signal that the water temperature has become a predetermined temperature or less from the sensor and the CPU transmits an off command. This cooling fan is used for a relatively long period of time, for example, during a traffic jam in summer.

  The air conditioner magnet clutch is continuously used, for example, from when the driver turns on the air conditioner to when the driver turns it off. For example, in the summer, the air conditioner is used for a relatively long time while the vehicle is running. Even in winter, it may be turned on to suppress fogging inside the window, and it is used for a relatively long time.

  On the other hand, among the switching elements 23, the four switching elements 23 from the bottom in FIG. 6 are configured by mechanical relays 53. The mechanical relay 53 is connected to a branch path 42 branched from the power supply terminal 41 via a fuse 39.

  The mechanical relay 53 includes a pair of power terminals 43 that are connected to the power supply terminal 41 to form a power circuit. One of the power terminals 43 is connected to the branch path 42, and the other is connected to the wire harness 44 outside the electrical connection box 10. Of the wire harness 44, the one described at the bottom is connected to the long-term load 45 described above. The other wire harness 44 is connected to a plurality of short-term loads 48 that are used only for a relatively short time.

  The mechanical relay 53 includes a pair of coil terminals 52 connected to a coil (not shown) accommodated therein, and one of the coil terminals 52 is connected to an external circuit of the electrical connection box 10. And connected to the switch 47.

  Examples of the short-term load 48 include a horn, a security horn, an ABS (anti-lock brake system) motor, and the like. These short-term loads 48 are used only for a relatively short time after the driver or the CPU instructs the short-term load 48 to start using the short-term loads 48. The short-term load 48 is disposed outside the casing 13 in the vehicle.

  The horn is quickly turned off by the urging means after the driver turns on the horn switch disposed on the steering wheel, for example, and is used only for a relatively short time.

  The security horn is sounded by the CPU when the CPU acquires a signal from a sensor (not shown) that detects an abnormal state of the vehicle. And when CPU acquires the signal from which the abnormal condition was cancelled | released from the sensor, blowing is stopped by CPU. This security horn is used only for a relatively short time from when an abnormal state occurs until it is released.

  The ABS motor is driven by the CPU when the CPU acquires a signal from a sensor (not shown) that detects that tire slip has occurred. And when CPU acquires the signal which shows the completion | finish condition of an ABS motor from a sensor, it is stopped by CPU. This ABS motor is used for a relatively short time at least while the driver is stepping on the brakes.

  Among the switching elements 23, the one that is connected to the long-term load 45 and executes energization and disconnection of the long-term load 45 is a first switching element 49. Of the switching elements 23, the second switching element 50 is connected to the short-term load 48 and performs energization and disconnection of the short-term load 48.

(Arrangement of switching element 23)
FIG. 5 shows the arrangement of the first switching element 49 and the second switching element 50 on the circuit board 14. As described above, a plurality of through holes 34 </ b> B into which one end of the fuse-side terminal fitting 37 is inserted are formed at positions near the upper edge of the circuit board 14. In the vicinity of the through hole 34B and below the through hole 34B, a plurality of switching elements 23 are arranged in a substantially horizontal direction.

  On the surface of the circuit board 14, the second switching element 50, the first switching element 49, the second switching element 50, the first switching element 49, the first switching element 49, and the second switching are sequentially arranged from the left to the right in FIG. An element 50 and a first switching element 49 are provided. Thus, in the present embodiment, the second switching element 50 is disposed at a position adjacent to the first switching element 49.

  Then, the effect | action and effect of this embodiment are demonstrated. When the driver or the CPU turns on the switch 47, the first switching element 49 or the second switching element 50 is energized and the long-term load 45 or the short-term load 48 is energized. Then, the first switching element 49 or the second switching element 50 generates heat.

  The heat generated from the first switching element 49 or the second switching element 50 is directly transferred to the filler 36 in contact with the first switching element 49 and the second switching element 50.

  Further, heat generated from the first switching element 49 or the second switching element 50 is transmitted to the lead terminal 24, the circuit board 14, and the filler 36.

  The heat transmitted to the filler 36 is dispersed inside the filler 36 and is soaked. Thereafter, the heat is transferred from the filler 36 to the back wall 17 and is dissipated from the back wall 17 to the outside of the electrical junction box 10.

  Since the first switching element 49 that performs energization and disconnection of the long-term load 45 has a longer energization time than the second switching element 50 that performs energization and disconnection of the short-term load 48, the amount of heat generation increases. . For this reason, in particular, there is a concern that the vicinity of the first switching element 49 connected to the long-term load 45 may be locally hot.

  In view of the above, in the present embodiment, the second switching element 50 is configured to be mounted next to the first switching element 49. Thereby, the heat generated from the first switching element 49 is dissipated to the substrate pattern and the space on the second switching element 50 side. As a result, it is possible to suppress heat from being trapped in the vicinity of the first switching element 49. Thereby, it can suppress that the vicinity of the 1st switching element 49 becomes high temperature locally.

  Further, in the present embodiment, a filler 36 having a thermal conductivity higher than that of air is filled between the back wall 17 and the circuit board 14. Thereby, the heat generated from the first switching element 49 and the second switching element 50 is transferred from the circuit board 14 to the filler 36. The heat transmitted to the filler 36 is soaked by diffusing into the filler 36. Thereby, it can further suppress that the vicinity of the 1st switching element 49 becomes high temperature locally.

  In addition, the heat transferred to the filler 36 is transferred from the filler 36 to the heat radiating wall and then dissipated from the heat radiating wall to the outside of the electrical junction box 10. Thereby, the heat dissipation of the electrical junction box 10 can be improved.

  In the present embodiment, the filler 36 is in contact with the first switching element 49 and the second switching element 50. Thereby, the heat generated from the first switching element 49 and the second switching element 50 is directly transmitted to the filler 36, so that the thermal uniformity can be further improved.

  In the present embodiment, a plurality of fuse-side terminal fittings 37 that can be connected to the fuses 39 are concentrated on the circuit board 14, and the first switching element 49 and the second switching element 50 are composed of the fuse-side terminal fittings. 37 is disposed in the vicinity. As a result, the fuses 39 that can be connected to the fuse-side terminal fitting 37 are centrally arranged in the electrical connection box 10. As a result, the maintainability when replacing the fuses 39 is improved as compared to the case where the fuses 39 are distributed.

<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.

(1) In the present embodiment, the heat radiating wall portion is only the back wall 17. However, the present invention is not limited to this, and the filling material 36 is also filled between the circuit board 14 and the front wall 51 of the cover 16. Both the front wall 51 and the back wall 17 may be heat radiating walls.
(2) In the present embodiment, the second switching element 50 is the mechanical relay 53, but the present invention is not limited to this, and the second switching element 50 may be configured by the semiconductor relay 54.
(3) In this embodiment, the filler 36 is a synthetic resin material. However, the present invention is not limited to this.

The perspective view which shows the electrical junction box which concerns on embodiment of this invention Front view showing the electrical junction box III-III sectional view in FIG. Partially cutaway front view of electrical junction box with cover removed Front view showing a state in which switching elements are arranged on the surface of the circuit board Block diagram showing the electrical connection of the electrical junction box

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electrical junction box 13 ... Casing 14 ... Circuit board 17 ... Back wall (heat radiation wall part)
36 ... Filler 37 ... Fuse-side terminal fitting 39 ... Fuse 45 ... Long-term load 48 ... Short-term load 49 ... First switching element 50 ... Second switching element

Claims (4)

A plurality of casings, a circuit board housed in the casing, and a plurality of long-term loads mounted on the circuit board and continuously used for a relatively long time. A plurality of second switching elements and a plurality of second switching elements that are mounted at positions adjacent to the first switching elements on the circuit board and that are used for a plurality of short-term loads that are used only for a relatively short time. An electrical junction box comprising a switching element. A plurality of fuse-side terminal fittings that can be connected to fuses are concentrated on the circuit board, and the first switching element and the second switching element are arranged in the vicinity of the fuse-side terminal fitting. Item 3. An electrical junction box according to Item 1. Of the wall portions constituting the casing, at least one of the wall portions facing the plate surface of the circuit board is a heat radiating wall portion, and heat conduction is performed between the heat radiating wall portion and the circuit board than air. The electrical junction box according to claim 1 or 2, wherein a high-rate filler is filled. The electrical connection box according to claim 3, wherein the filler is in contact with the first switching element and the second switching element.

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