JP2790130B2 - Electronic devices installed in the engine room - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device installed in an engine room. 2. Description of the Related Art Electronic equipment installed in an engine room includes, for example, a thermal air flow meter. As a conventional thermal air flow meter, for example, there is a thermal air flow meter described in JP-A-53-81159. [0003] Since electronic equipment used in an internal combustion engine is installed in an engine room, it is exposed to high temperatures. For this reason, the internal pressure in the case in which the circuit of the electronic device is hermetically sealed increases due to the temperature rise. [0004] However, the above-mentioned prior art has not taken sufficient care to prevent a temperature rise in a case in which a circuit is sealed. An object of the present invention is to provide an electronic device having excellent heat resistance. An object of the present invention is to provide a substrate provided with an electronic circuit, a case in which the substrate is sealed, and a connector for electrically connecting the electronic circuit to the outside. In the electronic device arranged in the engine room, a gel covering the electronic circuit, one end is opened in a direction opposite to the substrate and above the gel, and the other end is opened in the connector portion. And ventilation means for ventilating the inside of the case and the inside of the connector portion. Since the inside of the case for hermetically closing the circuit and the inside of the connector portion for electrically connecting the circuit inside the case to the outside are ventilated by the ventilating means, even if the temperature around the electronic device rises, The internal pressure of the case can be prevented from rising. [0008] The circuit in the case is covered and protected by the gel, but the opening end inside the case of the ventilation means is opened above the gel in the opposite direction to the substrate. As a result , even if the outside of the ventilation means is provided inside the connector, the gel can be prevented from flowing out from the opening inside the case of the ventilation means, and the gel filling amount is not restricted (the circuit is protected). Can be filled with a sufficient amount of gel ). The venting means has a curved portion as in claim 2.
By using pipes, there is a high degree of freedom in connector arrangement.
I can help you. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments shown in the drawings. FIG. 1 is a view schematically showing a heating resistor, and shows a hot wire 1 of the heating resistor which senses the amount of intake air.
Cold wire 2 for sensing air and intake air temperature
In each case, a platinum wire 102 is wound around a bobbin 101 made of alumina having a diameter of about 0.5φ and a length of about 2 mm, and both ends thereof are welded to lead wires 103, and the surface is coated with a glass material 104. It is small.
As shown in FIG. 2, the hot wire 1 and the cold wire 2 having the above-described structure are connected to the main passage 105 through which most of the intake air passes and the bypass passage 1 through which a part of the intake air is diverted.
06 is installed in the bypass passage 106 of the body 107 having the same. The body 107 shown in FIG. 2 has an air main passage 105, a bypass passage 106, and a mounting portion 108 for a module 47 constituting a drive circuit, and is made of aluminum die-cast. FIG. 3 is an exploded perspective view showing the entire structure of the present invention, FIG. 4 is a cross-sectional view of a main part of the module 47, FIG. 5 is its bottom part, and FIGS. 6 and 7 are II and II in FIG. It is a figure which shows the II section. In these figures, the case 48 of the module 47 is formed of a thermoplastic resin having excellent heat resistance such as a glass fiber reinforced unsaturated polyester resin. A preferred embodiment of the present invention will be described below. The metallic pins 49 to 52 and the pins 4
The metal terminals 53 to 56, the power supply terminal 44, the output terminal 45, the ground terminal 46, the pipe 57, and the metal collar 58 welded to the metal case 9 to 52 are formed in the case 4 described above.
8 is integrally formed. Case 48 is 0.8-1mm
It has a box-like shape having a thin bottom surface 95 and a peripheral groove 96 on the outer peripheral wall thereof, and a connector 97 is also integrally formed. Pins 49-52 and terminals 53-5
6 is a hot wire 1 disposed in the bypass passage 106
In addition to holding the cold wire 2, the hot wire 1 and the cold wire 2 are electrically connected to the hybrid IC constituting the drive circuit of the module 47. Also, the pipe 57 is sealed in the case 48.
The inside and the inside of the connector portion are ventilated to prevent the case internal pressure from rising due to the temperature rise inside the case 48.
Since the ventilation means is constituted by the pipe 57, even a complicated shape (for example, having a plurality of bent portions) can be formed in the resin case 48, and the degree of freedom in the arrangement of the connectors can be increased. After molding the case 48, the hot wire 1 and the cold wire 2 are
3 are welded to the pins 49 to 52, respectively. The pins 49 to 52 on the bottom surface of the case 48 are arranged at the vertices of a rectangle. Further, a metallic base 89 made of a metal plate has a hole 92 for receiving the terminals 53 to 56 formed integrally with the case 48. Here, Terminal 5
Reference numerals 3 to 56 denote bent portions of the connection portions of the terminals 53 to 56 with the drive circuit 63 and the connection portions of the pins 49 to 52 with the hot wires 1 and the cold wires 2 such that the positions projected on the circuit formation surface of the drive circuit 63 are shifted. Part. The following effects can be achieved by adopting such a configuration. Since the terminals 53 to 56 are plate-shaped, electrical connection with the drive circuit is easy. The terminals are connected to the drive circuit of the terminal and the hot wires 1 and the cold wires 2 of the pins.
The metal base 89 has a bent portion such that the projected portion of the connection portion of the drive circuit 63 on the circuit formation surface is shifted.
Is provided with holes 92 for receiving the terminals 53 to 56, the circuit configuration and the installation position of the drive circuit 63 are not restricted by the hot wire 1 and the cold wire 2, and the entire thermal flow meter is made compact. it can. Furthermore, pins 49 to 52 for electrically connecting the hot wire 1 and the drive circuit 63 and a terminal 53
Since the terminals 56 to 56 are molded with a synthetic resin and the terminals are plate-shaped, even if vibration of the vehicle is transmitted, poor contact between the pins and the terminals does not occur, and high vibration resistance can be secured. Further, the bent portions 59 provided in the terminals 53 to 56 and the holes 6 provided in the case 48 are provided.
There is also an effect that the insert fitting such as the terminal 53 can be accurately held in the mold when the case 48 is formed. The hybrid IC 63 includes a resistor such as a resistor 11 constituting a drive circuit and conductor patterns 64 to 68.
Semiconductor elements such as the operational amplifier chip 70 and the chip capacitors 42 and 43
, Etc., and pads 70 to 83 for connecting the inside of the ceramic substrate 69 and external elements and external circuits.
Is soldered. The insulating plate 88 is formed by depositing dangsten on a part 87 of a ceramic substrate 86 having a thickness of about 0.3 to 0.4 mm, which is thinner than the ceramic substrate 69, and then performing nickel plating. The power transistor chip 7 and the pad 84 are soldered to 88. A metal base 89 made of a metal plate has a wall 90 on its outer periphery, a projection 91 on a part of the wall 90, and a hole 92 on the bottom surface for receiving terminals 53 to 56 integrally formed with the case 48. And ceramic substrate 69, insulating plate 8
8 and a stepped portion 9 at one end.
The pad 85 is soldered to the stepped portion 94. A ceramic substrate 69 and an insulating plate 88 are adhered and fixed at predetermined positions on the metallic base 89 with a soft adhesive such as a silicone rubber. The above-described metallic base 89 is provided in the case 48.
Is fixedly attached to the bottom surface 95 of the case at a predetermined position in the inside. Between the terminals, that is, the hybrid IC 6
3 are connected to terminals 53 and 54 to which the hot wire 1 is connected.
3 are terminals 55, 56 to which the cold wires 2 arranged on both sides of the terminals 53, 54 are connected (contrary to the embodiment, the terminals 55, 56 of the cold wires 2).
May be arranged inside), and the pad 74
Is a pad 84 to which the connector of the power transistor 7 is connected, a pad 75 is a base, a pad 76 is an emitter, a pad 77 is a power supply terminal 44, a pad 78 is an output terminal 45, a pad 79 is a ground terminal 46, Pad 79
The pad 80 is electrically connected to a pad 85 on a metallic base 89 by a conductor pattern, and the pad 82 is electrically connected to the pads 81 and 83 by a metal wire such as an aluminum wire. By connecting the pad 80 and the pad 85, the metallic base 89 is set to the ground potential. Here, a power supply terminal 44, an output terminal 45, a ground terminal 46, and a hybrid I connected thereto.
The pads 77, 78 and 79 on the C63 are arranged so that the ground terminal 46 and the pad 79 to which the ground terminal 46 is connected are located between other terminals. The chip capacitors 42 and 43 for removing external surge and noise are provided with pads 77 and 7.
It is arranged in the immediate vicinity of 8,79 via a short conductor pattern. The above-described module sub-assembly is mounted on the module mounting portion 108 of the body 107 with the screw 97 sandwiching the sealing O-ring 96, and the resistors 13, 15, 27, 30 shown in FIG. The output voltage for the air flow rate is adjusted by trimming. After the output voltage is adjusted, the metal plate cover 98 is coated so as to cover the hybrid IC 63, the power transistor 7, and the terminals 53 to 56 so as to be in contact with the wall 90 of the metal base 89. 8
Nine protrusions 91 are welded. In order to protect the hybrid IC 63 from moisture and the like from the small holes 99 provided in the cover 98, a soft resin 100 (generally a gel) such as a silicone rubber is placed in the case 48 to a height that does not block the end face of the ventilation pipe 57. filling,
Is cured. As shown in the figure, the ventilation pipe 57 is formed so as to extend upward in the direction opposite to the substrate.
The gel can be prevented from flowing out from the opening of the ventilation means, and the amount of gel filling is not restricted by the position of the opening end of the ventilation means. Thereafter, a cap 109 made of the same material as the case 47 is bonded to the case 47 in such a manner that the rib 110 is fitted into the groove 96 of the case 47. A ground terminal 46 which is a ground for the drive circuit section
Alternatively, the electrical connection between the metallic base 89 and the metallic body 107 can be arbitrarily determined as necessary. In the thermal type flow meter configured as described above, the hot wire 1 and the cold wire 2 which constitute a part of the drive circuit (the cold wire 2 detects the temperature of the air, (If the temperature is almost the same or high accuracy is not required, it can be installed in the module.) It is necessary to arrange the module in the air passage outside the module. Despite its complexity, it holds a hot wire and a cold wire and integrates a support for electrical conductors that electrically connects the hot wire, the cold wire and the drive circuit to a synthetic resin case that houses the drive circuit. Therefore, it has a simple structure, is small, lightweight, and has remarkably excellent productivity. Further, since the case 48 has a box-shaped structure with the bottom portion 95, the resin 100 filled for maintaining the water resistance of the drive circuit portion does not leak and has excellent water resistance. Further, the pins 49 to 52, which are features of the present invention,
Since the terminals 53 and 56 can be arranged relatively freely in the mold of the case 48,
There is an effect that the connection terminals 53 to 56 for connecting to the drive circuit unit can be arranged in a form less restricted by the arrangement of the cold wire 2. According to the present invention, an increase in the internal pressure of the case due to an increase in temperature can be prevented, so that the electronic device can be installed in a high-temperature environment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view schematically showing a heating resistor used in the present invention. FIG. 2 is a view showing a longitudinal section of a main part of a thermal air flow meter according to the present invention. FIG. 3 is an exploded perspective view of the module. FIG. 4 is a cross-sectional view of a main part of the module. FIG. 5 is a bottom view of the module shown in FIG. FIG. 6 is a sectional view taken along line II of FIG. 4; FIG. 7 is a sectional view taken along line II-II of FIG. [Description of Signs] 1, 2 ... Heating resistor, 48: Case, 63: Hybrid IC (drive circuit), 89: Metallic base.

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Claims (1)

(57) [Claims] An electronic device installed in an engine room, comprising: a substrate on which an electronic circuit is provided; a case in which the substrate is sealed; and a connector unit for electrically connecting the electronic circuit to the outside. A gel covering the circuit, and a vent means for opening one end in a direction opposite to the substrate above the gel and opening the other end to the connector part, and for ventilating the inside of the case and the inside of the connector part. An electronic device installed in an engine room, comprising: 2. In Claim 1, the ventilation means is constituted by a pipe having a curved portion.
Electronic machine installed in an engine room characterized by the following:
vessel.