JP5655761B2 - Vehicle instrument - Google Patents

Description

  The present invention relates to a vehicle instrument.

  2. Description of the Related Art Conventionally, a vehicular instrument is known that includes an instrument panel that displays a vehicle state quantity such as a vehicle speed and a remaining fuel amount, and a control circuit unit that is provided behind the instrument panel and controls display by the instrument panel. In such a control circuit part of a vehicle instrument, heat is generated by Joule's law when a current flows when the vehicle instrument is used. Therefore, the control circuit is generally a dish-shaped cover in which a vent hole is formed. The control circuit section is cooled by natural convection of air entering and exiting the vent hole.

  Now, in the vehicle instrument disclosed in Patent Document 1, the circuit board included in the control circuit unit together with the heat dissipating member is covered with a cover behind the instrument panel, and a plurality of fins facing the tips of the plurality of fins provided on the heat dissipating member are provided. Ventilation holes are formed in the bottom surface of the cover. Here, since the air hole is opposed to the tip of the fin, the distance from the fin to the air hole becomes the shortest, and efficient heat dissipation becomes possible.

JP 2011-2410 A

  By the way, in general, there is a potential difference between wiring patterns such as copper formed on a circuit board, so that, under a high temperature environment, electrons move on or inside a non-metallic medium on the circuit board by an electric field. There is concern about moving electromigration. As described above, since electromigration occurs in a high temperature environment, it is effective to improve the air permeability inside the cover by the heat dissipation structure described in Patent Document 1 as a countermeasure for a vehicle instrument. It is.

  Further, due to the potential difference between the wiring patterns, there is a concern about ion migration that causes the metal components of the wiring pattern to melt and short-circuit the wiring pattern under a high humidity environment. Since ion migration occurs in a high humidity environment, in the structure described in Patent Document 1 in which a heat dissipation member is provided on the circuit board and a vent hole is formed on the bottom of the cover, air containing moisture is Since it enters in the state which has a possibility of touching a wiring pattern, there exists a possibility that ion migration may arise.

  In the vehicular instrument disclosed in Patent Document 1, as described above, there is a concern about the occurrence of ion migration, and therefore it is necessary to reduce the inflow of moisture into the cover covering the circuit board as much as possible.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle instrument ventilation structure capable of efficiently ensuring the heat dissipation structure and suppressing the occurrence of ion migration. There is to do.

According to the first aspect of the present invention, there is provided an instrument panel for displaying a vehicle state quantity, a control circuit part that is provided behind the instrument panel and controls display by the instrument panel, and covers the control circuit part behind the instrument board. The control circuit unit has a circuit board on which a wiring pattern is formed on a mounting surface on which circuit components are mounted, and the plurality of circuit components are hotter than the low-temperature components and the low-temperature components. The cover includes a high-temperature component, the cover includes a low-temperature cover portion that covers the low-temperature component in a sealed state, a high-temperature cover portion that covers the high-temperature component above the low-temperature component so as to allow ventilation, and the low-temperature cover portion A guide recess that guides air is formed by a bottom surface that is recessed toward the vent hole that allows ventilation through the inside and outside formed by the cover portion, and the bottom surface of the guide recess is disposed along the direction of gravity .

  In the invention according to the first aspect, air is generated to some extent in the guide recess formed in the low-temperature cover portion outside the low-temperature cover portion of the dish-like cover due to the heat generated by the low-temperature components forming the control circuit portion. The temperature rises. Here, the guide recess is recessed toward the ventilation hole formed by the upper high-temperature cover part, so that the specific gravity becomes lighter due to the temperature rise and the natural convection air is guided to the ventilation hole by the bottom surface of the guide recess and becomes hot. It flows into the cover part. Furthermore, inflow air that rises greatly in the high temperature cover portion of the dish-shaped cover due to the heat generated by the high temperature component that is higher than the low temperature component by the control circuit portion passes through the ventilation holes formed in the high temperature cover portion. It can be discharged to the outside of the high temperature cover part which is on the low temperature side than the inside. According to these, it is possible to ensure a heat dissipation structure that reliably ventilates the inside and outside of the high-temperature cover portion and enhances the heat dissipation efficiency from the high-temperature components that become high temperature.

  In addition, in a low-temperature cover that covers a low-temperature component that is lower in temperature than the high-temperature component in a sealed state, a constant low humidity can be maintained while suppressing an increase in air temperature. In addition, the air whose temperature has risen due to the heat generated by the high-temperature components in the high-temperature cover part has a low specific gravity, and therefore moves upward when released outside the high-temperature cover part. As a result, the low temperature component covered by the low temperature cover portion below the high temperature cover portion is not easily affected by the heat generated by the high temperature component. According to these, inflow of high humidity and high-temperature air into the low-temperature cover part is restricted, and the occurrence of ion migration can be suppressed between the wiring patterns on the circuit board on which the low-temperature components are mounted.

  According to the above, when securing the heat dissipation structure, it is possible to achieve both suppression of ion migration and limitation to high-temperature components where heat generation is a problem.

Further, according to the invention described in claim 1, in the inside of the guide recess bottom surface along a gravity direction is arranged, the air along the bottom surface to natural convection, through the hot cover of the upper form It becomes easy to be guided to the pores. According to this, it becomes possible to achieve the securing of a heat dissipation structure that increases the heat dissipation efficiency from the high-temperature component to the air in the high-temperature cover portion, while suppressing the ion migration.

According to the second aspect of the present invention, the angle of the bottom surface of the guide recess with respect to the instrument panel is equal to the mounting angle of the instrument panel in the vehicle with respect to the direction of gravity. In such a configuration, when the instrument panel is tilted by an attachment angle with respect to the direction of gravity and attached to the vehicle, the bottom surface of the guide recess whose angle with respect to the instrument board is equal to the attachment angle is a surface that is reliably along the direction of gravity. According to this, with the installation of the instrument panel in the vehicle, it is possible to realize the arrangement of the bottom surface of the guide recess that does not hinder the natural convection of the air, and to secure a highly efficient heat dissipation structure by the guide air on the bottom surface.

According to the third aspect of the present invention, the control circuit unit is mounted on the mounting surface along the direction of gravity, and has a plurality of heat radiation fins that radiate heat of the high temperature component, and the high temperature cover unit has a plurality of heat dissipations. Cover hot parts with fins. In such a configuration, in the high temperature cover portion in which the air guided by the guide recess flows in through the vent hole, the inflow air flows upward while contacting the plurality of radiating fins along the direction of gravity. Heat can be radiated effectively. According to this, since the natural cooling of the high-temperature parts can be promoted, it is possible to achieve the securing of the heat dissipation structure with improved heat dissipation efficiency in the high-temperature cover part while suppressing the ion migration.

According to the invention described in claim 4 , the plurality of vent holes include a lower vent hole provided at a lower portion of the high temperature cover portion and communicating with the guide recess, and an upper vent hole provided at an upper portion of the high temperature cover portion. . In such a configuration, the air whose temperature has risen in the high-temperature cover due to the heat of the high-temperature components naturally convects and moves upward due to the lighter specific gravity. As a result, air is released to the outside through the upper vent hole at the upper part of the high temperature cover part, and at the same time, the guide air in the guide recess easily flows into the inside through the lower vent hole at the lower part of the high temperature cover part. According to this, since the natural cooling of the high-temperature parts can be promoted, it is possible to achieve the securing of the heat dissipation structure with improved heat dissipation efficiency in the high-temperature cover part while suppressing the ion migration.

It is a front view which shows the meter for vehicles by one Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is sectional drawing which expands and shows the characteristic part of FIG. It is a perspective view which shows the cover of FIG. FIG. 3 is a perspective view showing a radiation fin of FIG. 2.

(Basic configuration)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the basic configuration of the vehicle instrument 1 will be described. As shown in FIG. 1, a vehicle instrument 1 according to an embodiment of the present invention is installed as an instrument on an instrument panel in front of a driver's seat in a vehicle. The vehicle instrument 1 is provided with an instrument panel 20, a pointer 21, a first light source 30, a second light source 40, a control circuit unit 50, a case 80, a cover 90, and the like for displaying a vehicle state quantity and causing the driver to visually recognize it. It has been.

  For example, the instrument panel 20 made of a resin such as polycarbonate or acrylic is provided with a scale portion 24 and a number portion 25, and a colored layer is provided in a portion excluding the scale portion 24 and the number portion 25. It has been. In the present embodiment, the scale unit 24 and the number unit 25 are indicators 24 and 25 for indicating the vehicle speed as the vehicle state quantity by the pointer 21, and the light from the second light source 40 is transmitted from behind the instrument panel 20. It is formed to be transmissive.

  The pointer 21 is rotatably provided along the front surface of the instrument panel 20. The pointer 21 indicates the indices 24 and 25 by the tip portion 21b according to the rotation position around the rotation center O.

  The first light source 30 and the second light source 40 are made of chip-type light emitting diodes, and a plurality of the first light source 30 and the second light source 40 are arranged behind the instrument panel 20. Here, each first light source 30 faces the base end portion 21a of the pointer 21 through a through hole (not shown) of the instrument panel 20, and emits white light when energized, so that light enters the base end portion 21a. As a result, the incident light on the base end portion 21a is guided through the pointer 21 toward the distal end portion 21b, so that the pointer 21 emits light. On the other hand, each of the second light sources 40 faces a circumferential portion of the instrument panel 20 where the indicators 24 and 25 are arranged, and emits white light when energized so that light enters the indicators 24 and 25. As a result, the indicators 24 and 25 are lit and displayed by transmission of incident light.

  The control circuit unit 50 includes a wiring pattern 52 on a mounting surface 51 a on which a circuit component 53 is mounted in the circuit board 51, and is provided behind the instrument panel 20. The control circuit unit 50 controls the driving of the first light source 30 and the second light source 40 and the driving of the pointer 21.

  The case 80 is formed of a resin such as polypropylene, for example, and is provided behind the instrument panel 20. The case 80 is fixed with an instrument panel 20, a circuit board 51, a cover 90 described later, and the like. Since the case 80 separately surrounds the first light source 30 and the second light source 40, the indicators 24 and 25 and the pointer 21 can concentrate and transmit light without leaking light to the outside of the enclosure. Is possible.

  The cover 90 is formed in a dish shape using, for example, a resin such as polypropylene, and is provided so as to cover the circuit board 51, the wiring pattern 52, and the circuit component 53 behind the instrument panel 20.

(Feature)
Next, features of the vehicle instrument 1 will be described in detail. As shown in FIG. 2, the instrument board 20 is attached to the vehicle in an inclined state with respect to the direction of gravity by an angle θ, and a circuit board 51 is disposed substantially parallel to the instrument board 20.

  As shown in FIGS. 2 and 3, the control circuit unit 50 includes a plurality of circuit components 53 as electrical components or electronic components for driving the pointer 21 and the light sources 30 and 40. Each circuit component 53 mounted on the mounting surface 51 a of the circuit board 51 is electrically connected to the wiring pattern 52 formed on the mounting surface 51 a and is energized for driving the pointer 21 and the light sources 30 and 40. Fever. Each circuit component 53 is classified into a high-temperature component 53a and a low-temperature component 53b according to the heat generation temperature.

  In the present embodiment, the low temperature component 53b of the circuit component 53 includes a stepping motor, a microcomputer, and the like that drive the pointer 21. The low temperature component 53b is a circuit component 53 whose power consumption when driving the vehicle meter 1 is smaller than that of the high temperature component 53a, and generates less heat due to conversion of power consumption into Joule heat. Thereby, the heat generation temperature of the low temperature component 53b becomes a relatively low temperature of, for example, 100 ° C. or less. The low-temperature component 53b is disposed in a portion of the mounting surface 51a of the circuit board 51 excluding the upper portion, that is, in a region extending from the middle portion to the lower portion in the gravity direction.

  In the present embodiment, the high-temperature component 53a among the circuit components 53 includes a regulator or the like that drives the winker of the vehicle. The high temperature component 53a is a circuit component 53 whose power consumption when driving the vehicle meter 1 is larger than that of the low temperature component 53b, and generates a large amount of heat due to conversion of power consumption into Joule heat. Thereby, the high temperature component 53a has a higher temperature than the low temperature component 53b, for example, a temperature of 100 ° C. or more. The high temperature component 53a is disposed with a plurality of heat radiation fins 54 on the upper surface of the mounting surface 51a of the circuit board 51, that is, above the low temperature component 53b.

  Here, each radiating fin 54 is formed in a plate shape having a relatively large surface area as shown in FIG. 5 by using a metal having a low thermal resistance, such as aluminum or copper, and is integrated as one heat sink. The inner surface and outer surface of each radiating fin 54 are arranged in a form along the direction of gravity.

  As shown in FIGS. 2 to 4, the cover 90 has a plurality of cover portions 90 a and 90 b each formed in an individual dish shape. The peripheral edge portion of the high temperature cover 90 a is airtightly fixed to the upper portion of the mounting surface 51 a of the circuit board 51 where the high temperature components 53 a and the radiation fins 54 are provided. The high temperature cover part 90a has a plurality of vent holes 91 for ventilating inside and outside. Of the ventilation holes 91, a plurality of lower ventilation holes 91b are formed at the lower corners of the bottom wall of the high temperature cover part 90a, and each penetrates the high temperature cover part 90a in a slit shape. Of the vent holes 91, a plurality of upper vent holes 91a are formed at the upper corners of the bottom wall of the high-temperature cover portion 90a, and the high-temperature cover portions 90a are slit at locations that do not overlap with the lower vent holes 91b in the direction of gravity. It penetrates in a shape. With the above configuration, the high temperature cover portion 90a covers the high temperature component 53a and the heat radiation fin 54 above the low temperature component 53b in a state in which the inside and outside can be ventilated by the respective vent holes 91a and 91b.

  On the other hand, the peripheral edge portion of the low-temperature cover 90b is fixed to a region of the mounting surface 51a of the circuit board 51 where the low-temperature component 53b is provided, thereby covering the low-temperature component 53b in a sealed state. The low-temperature cover part 90b forms a guide concave part 92 that is recessed toward the lower ventilation hole 91b of the high-temperature cover part 90a positioned above. In the guide recess 92, a bottom surface 92a that is recessed from the bottom wall of the low temperature cover portion 90b toward the front circuit board 51 is exposed to the inside of the guide recess 92 out of the low temperature cover portion 90b, and the bottom surface 92a is the present embodiment. Is formed in a flat surface shape and is inclined with respect to the circuit board 51 by an angle equal to the mounting angle θ of the instrument panel 20 in the vehicle. As a result, in the inside of the guide recess 92 in which the bottom surface 92a is arranged along the direction of gravity, the air heated by the heat generated by the low temperature component 53b in the low temperature cover portion 90b is as shown by the white arrow in FIG. The bottom 92a guides the upper lower vent 91b.

  According to the vehicle instrument 1 described above, the temperature of the air rises to some extent inside the guide recess 92 formed in the low temperature cover portion 90b outside the low temperature cover portion 90b due to heat generated by the low temperature component 53b. Here, since the guide recess 92 is recessed toward the lower ventilation hole 91b formed by the upper high-temperature cover 90a, the air having a reduced specific gravity due to the temperature rise and the natural convection flows through the bottom 92a of the guide recess 92. It is guided to the air holes 91b and flows into the high temperature cover portion 90a. Further, the inflowing air that rises greatly in the high temperature cover portion 90a due to the heat generated by the high temperature component 53a that is higher in temperature than the low temperature component 53b passes through the upper and lower vent holes 91a and 91b formed in the high temperature cover portion 90a. It can be discharged out of the high temperature cover portion 90a, which is on the lower temperature side than in the high temperature cover portion 90a. According to these, the inside and outside of the high-temperature cover part 90a can be surely ventilated to ensure a heat dissipation structure with improved heat dissipation efficiency from the high-temperature component 53a that becomes high temperature.

  In addition, in the low temperature cover portion 90b that covers the low temperature component 53b that is lower in temperature than the high temperature component 53a in a sealed state, a constant low humidity can be maintained while suppressing an increase in the temperature of the air. Moreover, the air whose temperature has risen in the high temperature cover portion 90a due to the heat generated by the high temperature component 53a has a low specific gravity, and therefore moves upward when released from the high temperature cover portion 90a. As a result, the low temperature component 53b covered by the low temperature cover portion 90b below the high temperature cover portion 90a is not easily affected by the heat generated by the high temperature component 53a. According to these, since the flow of high humidity and high temperature air into the low temperature cover part 90b is restricted, the occurrence of ion migration can be suppressed between the wiring patterns 52 on the circuit board 51 on which the low temperature component 53b is mounted. is there.

  In addition, in the vehicle instrument 1, when the instrument plate 20 is tilted by the attachment angle θ with respect to the direction of gravity and attached to the vehicle, the bottom surface 92 a of the guide recess 92 whose angle with respect to the instrument plate 20 is equal to the attachment angle θ The surface is surely along the direction. According to this, with the mounting of the instrument panel 20 in the vehicle, the arrangement of the bottom surface 92a that does not inhibit the natural convection of air is realized, and in the subsequent mounting state, the inside of the guide recess 92 is caused by the natural convection along the bottom surface 92a. Is easily guided to the upper lower vent hole 91b. Therefore, it is possible to secure a highly efficient heat dissipation structure by the guide air on the bottom surface 92a.

  In addition, in the high temperature cover portion 90a in which the air guided by the guide recess 92 flows in through the respective lower vent holes 91b, the inflow air comes into contact with the plurality of radiating fins 54 along the direction of gravity and the high temperature component 53a It flows upward while receiving heat. As a result, the air whose temperature has risen in the high temperature cover portion 90a naturally convects due to the lighter specific gravity, and moves upward so that it can be released from each upper vent 91a to the outside of the high temperature cover portion 90a. . At the same time, the guide air in the guide recess 92 can easily flow into the high temperature cover portion 90a through the lower vent holes 91b, so that the air permeability inside and outside the high temperature cover portion 90a is enhanced. According to the above, since the heat of the high temperature component 53a can be effectively radiated to promote natural cooling, ensuring the heat dissipation structure with improved heat dissipation efficiency in the high temperature cover 90a is compatible with the suppression of ion migration. Can be achieved.

  Therefore, according to the vehicular instrument 1 described so far, when the heat dissipation structure is ensured, it is possible to limit the ion migration to a high temperature component 53a where heat generation is a problem.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not construed as being limited to the embodiment, and can be applied to various embodiments without departing from the gist of the present invention. it can.

  Specifically, the upper ventilation hole 91a and the lower ventilation hole 91b of the above embodiment may be provided one by one, may be provided to overlap each other in the direction of gravity, or only one may be provided. Also good. Moreover, it is good also as a structure which does not provide about the radiation fin 54 of the said embodiment.

DESCRIPTION OF SYMBOLS 1 Vehicle instrument, 20 Instrument panel, 21 Pointer, 30 1st light source, 40 2nd light source, 50 Control circuit part, 51 Circuit board, 51a Mounting surface, 52 Wiring pattern, 53 Circuit component, 53a High temperature component, 53b Low temperature component , 53c Drive source, 54 Radiation fin, 90 cover, 90a High temperature cover, 90b Low temperature cover, 91 Vent, 91a Upper vent, 91b Lower vent, 92 Guide recess, 92a Bottom

Claims (4)

An instrument panel displaying the vehicle state quantity;
A control circuit unit provided behind the instrument panel to control display by the instrument panel;
A cover that covers the control circuit unit behind the instrument panel;
The control circuit unit has a circuit board on which a wiring pattern is formed on a mounting surface on which circuit components are mounted,
The plurality of circuit components include a low temperature component and a high temperature component that is hotter than the low temperature component,
The cover has a low-temperature cover portion that covers the low-temperature component in a sealed state;
A high-temperature cover portion that covers the high-temperature component in a breathable manner above the low-temperature component; and
The low temperature cover part forms a guide concave part that is recessed toward the ventilation hole that can ventilate the inside and outside formed by the upper high temperature cover part and guides air by the bottom surface ,
The vehicle instrument according to claim 1, wherein the bottom surface of the guide recess is disposed along a direction of gravity . The vehicle instrument according to claim 1, wherein an angle of the bottom surface of the guide recess with respect to the instrument panel is equal to a mounting angle of the instrument panel in a vehicle with respect to a direction of gravity. The control circuit unit is mounted on the mounting surface along the direction of gravity, and has a plurality of radiating fins that radiate heat of the high-temperature component,
The hot cover portion, a vehicle meter according to claim 1 or 2, characterized in that with a plurality of the radiating fins to cover the hot parts. A plurality of vent holes provided in a lower portion of the high temperature cover portion and communicating with the guide recess;
The vehicular instrument according to any one of claims 1 to 3, further comprising an upper ventilation hole provided in an upper part of the high temperature cover part.

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