JP3539473B2 - Control unit for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has a configuration in which a printed circuit board on which components of a control circuit for controlling an internal combustion engine ignition device and a fuel injection device are mounted is housed in an outer case, and is molded with an insulating resin cast in the outer case. The present invention relates to a control unit for an internal combustion engine having the same.
[0002]
[Prior art]
In a control device for an internal combustion engine that controls at least one of an ignition device and a fuel injection device of the internal combustion engine, control is performed using control conditions such as a rotation speed of the internal combustion engine, a throttle opening, an engine temperature, and an exhaust temperature. Recently, atmospheric pressure is often used as a control condition. When the atmospheric pressure is one of the control conditions in the control unit that controls at least one of the internal combustion engine ignition device and the fuel injection device, it is necessary to incorporate an atmospheric pressure sensor into the control unit.
[0003]
4 (A) to 4 (C) show a state where the atmospheric pressure sensor is incorporated in a conventional internal combustion engine control unit of this type incorporating the atmospheric pressure sensor. In this control unit, an atmospheric pressure sensor 1 housed in a sensor case 6 made of a cylindrical body such as aluminum is mounted on a printed circuit board 2 together with other components (not shown) constituting a control circuit. Is fixed to the printed circuit board 2 by bonding or the like.
[0004]
The printed circuit board 2 is housed in the outer case 4 together with the sensor case 6 in which the atmospheric pressure sensor 1 is housed, and is insulated inside the outer case 4 with the other open end of the sensor case 6 exposed to the atmosphere. A resin is cast to form a mold portion 5.
[0005]
A waterproof lid 7 made of an iron plate is attached to the other open end of the sensor case 6 with a screw 9 via a rubber packing 8 in order to prevent water or the like from entering the inside of the sensor case. A tubular projection 701 having a small-diameter ventilation hole 701a (see FIG. 4C) penetrating the waterproof lid and communicating with the atmosphere from the inside of the sensor case is provided on the outer surface of the waterproof lid 7. One end of a flexible waterproof tube 10 is fitted to the projection 701 to prevent water droplets from entering the ventilation hole 701a of the projection 701 or closing the ventilation hole 701a due to freezing of the water droplet. The other end of the waterproof tube is guided to a place where there is no risk of intrusion or freezing of water droplets.
[0006]
[Problems to be solved by the invention]
In the conventional control unit for an internal combustion engine provided with an atmospheric pressure sensor, water enters the sensor case 6 or a small-diameter vent hole 701a for introducing atmospheric pressure into the sensor case is closed by freezing of water droplets. The rubber packing 8, the waterproof lid 7 and the waterproof tube 10 are used to prevent the water leakage. In addition, the waterproof lid 7 is made of a steel plate so that the waterproof lid 7 is not damaged by the vibration of the waterproof tube 10 due to the vibration of the internal combustion engine. Therefore, the conventional control unit of this type has a problem that the number of parts is large and the assembling requires a large number of man-hours, thereby increasing the manufacturing cost.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a control for an internal combustion engine that can be configured with a small number of parts without the possibility of flooding a pressure receiving portion of an atmospheric pressure sensor or blocking a passage for introducing atmospheric pressure to the atmospheric pressure sensor due to freezing. To provide units.
[0008]
[Means for Solving the Problems]
A control unit for an internal combustion engine to be improved by the present invention is a component of a control circuit that controls at least one of an ignition device and a fuel injection device for an internal combustion engine using an atmospheric pressure detected by an atmospheric pressure sensor as one of control conditions. A printed circuit board mounted with an atmospheric pressure sensor, a sensor case fixed to the printed circuit board and housing the atmospheric pressure sensor, and an outer case housing the printed circuit board together with the sensor case. An insulating resin is poured into the case to form a molded part.
[0009]
In the present invention, the sensor case is provided with a part positioned inside the mold part and another part positioned outside the mold part, and an end located outside the mold part is opened to the atmosphere. It consists of a cylindrical body. In the sensor case, a plurality of waterproof walls which are arranged alternately and partition the space in the sensor case in the axial direction are spaced apart in the axial direction and inclined in different directions alternately with respect to the axial direction. The sensor case is provided integrally with the sensor case. Further, an opening is formed at an end of each waterproof wall farther from the atmospheric pressure sensor to communicate the space on both sides of each waterproof wall.
[0010]
The above control unit may be used with the end of the sensor case open to the atmosphere facing upward, or may be used with the end of the sensor case open to the atmosphere facing downward. Good.
[0011]
When the sensor case is used with the open end of the sensor case facing upward, water drops such as rainwater enter the sensor case through the opening, but the water drops inside the sensor case are arranged alternately. Flowed along the slopes of the plurality of waterproof walls alternately inclined in different directions, and a recess formed between the end of each waterproof wall near the atmospheric pressure sensor and the peripheral wall of the sensor case. Since the water drops accumulate at the place, the water droplets that have entered do not reach the atmospheric pressure sensor.
[0012]
In addition, when the sensor case is used with the opening of the sensor case facing downward, water droplets entering from the sensor case opening are bounced back by hitting a plurality of waterproof walls arranged alternately in a state of being alternately inclined in different directions. Therefore, water does not reach the atmospheric pressure sensor. In this case, water droplets adhering to the waterproof wall flow down along the slope and are discharged to the outside through the opening of the sensor case.
[0013]
With the above configuration, the plurality of waterproof walls can be formed integrally with the sensor case, and a waterproof lid that covers a portion of the sensor case that opens to the atmosphere, a waterproof tube that introduces the atmosphere into the sensor case, and the like are provided. Since there is no need to provide them, the number of parts and the number of assembly steps can be reduced, and the cost can be reduced.
[0014]
Further, the opening formed at the end of the waterproof wall farther from the atmospheric pressure sensor can be formed so as to have a sufficient size without taking measures such as preventing intrusion of water droplets. The opening can be formed to have a sufficient size so as not to be blocked by freezing of the water droplet, so that the atmospheric pressure sensor can always detect the atmospheric pressure without any trouble.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing a main part of a configuration example of a control unit for an internal combustion engine according to the present invention, and FIGS. 2A to 2D show a sensor case used in the unit of FIG. .
[0016]
In FIG. 1, 1 is an atmospheric pressure sensor, 2 is a printed circuit board, 3 is a cylindrical sensor case in which the atmospheric pressure sensor 1 is housed, 4 is an outer case in which the printed circuit board 2 is housed together with the sensor case 3, and 5 is an outer case. This is a molded portion formed by casting an insulating resin into the case 4.
[0017]
In the atmospheric pressure sensor 1 used in this example, a semiconductor strain gauge type sensor element and an amplifier circuit are integrated in one chip and housed in a case 101, and a plurality of leads 103 are derived from a sensor substrate 102. A pressure sensor of an absolute pressure type for atmospheric pressure, in which a case 101 is formed with a ventilation hole 104 for communicating the inside and the outside thereof, and tips of a plurality of leads 103 are soldered to circuit conductors of the printed board 2 and held on the printed board. Have been.
[0018]
On the printed circuit board 2, components (not shown) constituting a control circuit for controlling at least one of the internal combustion engine ignition device and the fuel injection device are mounted together with the atmospheric pressure sensor 1.
[0019]
The sensor case 3 used in the illustrated example is made of a synthetic resin molded product, and the atmospheric pressure sensor 1 is fixed to the inside of one end in the axial direction of the sensor case by bonding. The sensor case 3 is disposed in the mold part 5 with the other end in the axial direction opened to the atmosphere.
[0020]
As shown in FIG. 2, the sensor case 3 has a peripheral wall portion 301 having a rectangular cross section perpendicular to the axial direction thereof, and a plurality (see FIG. 2) of the sensor case 3 so as to partition a space inside the peripheral wall portion in the axial direction. In this example, two waterproof walls 302 and 303 are provided at intervals in the axial direction. The waterproof walls 302 and 303 are provided integrally with the peripheral wall portion 301 in a state of being alternately inclined in different directions with respect to the axial direction, and the distal end of each waterproof wall farther from the atmospheric pressure sensor 1 and the peripheral wall portion 301 are provided. Between them, openings 304 and 305 are formed to communicate the spaces on both sides of each waterproof wall. Also, as shown in FIG. 1, when the openings 304 and 305 of the sensor case 3 are arranged in a state of facing upward, the waterproof wall is opposite to the atmospheric pressure sensor at the end near the atmospheric pressure sensor 1. A recess 11 for storing rainwater that has entered from the outside is formed between the portion located on the side and the peripheral wall portion 301 of the sensor case.
[0021]
The outer case 4 is formed in a cup shape as shown in FIG. 1, and the assembly of the atmospheric pressure sensor 1, the sensor case 3, and the printed board 2 positions the printed board 2 on the bottom side of the outer case 4. In this state, it is housed in the outer case. An insulating resin is cast into the outer case 4 with the other end of the sensor case 3 in the axial direction opened to the atmosphere, and a molded portion 5 is formed from the resin.
[0022]
In the above-described control unit for an internal combustion engine, the opening 304 on the tip side of the waterproof wall 302 from the end of the sensor case 3 opened to the atmosphere, the space 306 between the waterproof wall 302 and the waterproof wall 303, The atmospheric pressure is applied to the pressure receiving surface of the atmospheric pressure sensor 1 through the opening 305 on the tip side of the wall 303, the space 307 between the waterproof wall 303 and the atmospheric pressure sensor 1, and the ventilation hole 104 of the atmospheric pressure sensor 1. Therefore, the atmospheric pressure can be detected by the atmospheric pressure sensor.
[0023]
When the above-described control unit is used in a state where the openings 304 and 305 of the sensor case 3 are directed upward, water drops such as rainwater enter the sensor case 3 from the end of the sensor case 3 that opens to the atmosphere. As shown by the dashed arrows in FIG. 1, the water droplets that have entered the sensor case hit the waterproof walls 302 and 303 that are alternately arranged and inclined in different directions, and flow along the slopes of the waterproof walls, It accumulates in the recess 11 on the opposite side of the atmospheric pressure sensor at the end of each waterproof wall closer to the atmospheric pressure sensor 1. Therefore, the water droplet does not reach the atmospheric pressure sensor 1, and the detection operation of the atmospheric pressure sensor is not hindered by the water droplet.
[0024]
When the above-described control unit is used with the openings 304 and 305 of the sensor case 3 facing downward, the water droplets that have entered from the openings 304 and 305 of the sensor case are alternately inclined in different directions. The water does not reach the atmospheric pressure sensor 1 because the water is repelled by hitting the waterproof walls 302 and 303 arranged in the area. In this case, the water droplets attached to the waterproof walls 302 and 303 flow down along the slopes and are discharged to the outside through the openings 304 and 305 of the sensor case.
[0025]
As described above, in the present invention, the water that has entered the sensor case is stored in the recess 11 formed near the end of the waterproof walls 302 and 303 near the atmospheric pressure sensor, so that the water is supplied to the atmospheric pressure sensor. The openings 304 and 305 formed at the distal ends of the waterproof walls 302 and 303, respectively, are formed so as to have a sufficient size without taking into consideration the prevention of water intrusion. can do. Therefore, the opening on the tip side of each waterproof wall is formed large enough not to be blocked by the freezing of water droplets, thereby preventing the detection operation of the atmospheric pressure sensor 1 from being impaired by the freezing of water droplets. it can.
[0026]
Further, in the present invention, a plurality of waterproof walls 302 and 303 can be formed integrally with the sensor case, and a waterproof lid, a tube for introducing the atmosphere into the sensor case, and the like are provided at the end of the sensor case 1 that opens into the atmosphere. Since it is not necessary to provide the components, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced.
[0027]
In the example shown in FIGS. 1 and 2, the openings 304 and 305 formed on the distal ends of the waterproof walls 302 and 303 of the sensor case 3 farther from the atmospheric pressure sensor 1 are different in width from each waterproof wall. Although the openings 304 and 305 are formed so as to cover the entire direction, the shapes of the openings 304 and 305 are not limited to those shown in FIG. 2, for example, as shown in FIGS. 3A to 3D. Only a part of the distal ends of the waterproof walls 302 and 303 remote from the atmospheric pressure sensor is cut out to form openings 304 and 305, and the other ends of the waterproof walls are connected to the peripheral wall 301. It may be. Also in this case, the size of the openings 304 and 305 can be selected to a size such that the openings are not blocked by freezing of water droplets.
[0028]
In each of the above examples, two waterproof walls are provided on the sensor case. However, in a state where the sensor case is spaced apart in the axial direction of the sensor case and alternately tilted in different directions with respect to the axial direction, 3 At least one waterproof wall may be provided, and an opening for communicating the space on both sides of each waterproof wall may be formed at the distal end side of each waterproof wall farther from the atmospheric pressure sensor.
[0029]
In the example shown in FIG. 1, one end in the axial direction of the sensor case 3 is bonded to the case 101 of the atmospheric pressure sensor 1, and the tips of the leads 103 of the atmospheric pressure sensor 1 are soldered to a printed circuit board. By attaching the sensor case 3, the sensor case 3 is fixed to the printed circuit board 2. However, as shown in the conventional example shown in FIG. 4, one end of the sensor case in the axial direction is directly connected to the printed circuit board 2. 2, the sensor case may be fixed to the printed circuit board.
[0030]
【The invention's effect】
As described above, according to the present invention, a plurality of waterproof walls provided alternately in a cylindrical sensor case accommodating the atmospheric pressure sensor and inclined in different directions alternately with respect to the axial direction are provided. By forming an opening at the end of each waterproof wall farther from the atmospheric pressure sensor and communicating with the space on both sides of each waterproof wall, water droplets entering the sensor case are prevented from reaching the atmospheric pressure sensor Therefore, parts such as a waterproof lid for covering the opening of the sensor case and a waterproof tube connected to the ventilation hole provided on the waterproof lid are omitted, and the waterproof structure of the sensor case for accommodating the atmospheric pressure sensor is simplified. Can be achieved. Therefore, the cost of the control unit for the internal combustion engine can be reduced by reducing the number of parts and the number of assembly steps.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a main part of a configuration example of a control unit according to the present invention.
FIGS. 2A and 2B show a sensor case used in the control unit of FIG. 1, wherein FIG. 2A is a top view, FIG. 2B is a side view, FIG. 2C is a bottom view, and FIG. It is a D line sectional view.
3A and 3B show different examples of a sensor case used in a control unit according to the present invention, wherein FIG. 3A is a top view, FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A, and FIG. (B) is a cross-sectional view taken along line CC, and (D) is a cross-sectional view taken along line DD in (B).
4A is a cross-sectional view showing a main part of a structure of a conventional example, FIG. 4B is a cross-sectional view taken along line BB of FIG. 4A, and FIG. 4C is an enlarged view of a C part of FIG. is there.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Atmospheric pressure sensor 2 Printed circuit board 3 Sensor case 301 Peripheral wall part 302,303 Waterproof wall 304,305 Opening part 4 Outer case 5 Mold part

Claims (1)

A printed circuit board mounted with a component of a control circuit for controlling at least one of an internal combustion engine ignition device and a fuel injection device together with the atmospheric pressure sensor, using the atmospheric pressure detected by an atmospheric pressure sensor as one of the control conditions; and A sensor case fixed to the housing and housing the atmospheric pressure sensor therein, and an outer case housing the printed circuit board together with the sensor case, wherein an insulating resin is poured into the outer case and a molded part is formed. In the formed control unit for the internal combustion engine,
The sensor case is provided in a state where a part is located in the mold part and another part is located outside the mold part, and an end located outside the mold part is open to the atmosphere. Consisting of body,
In the sensor case, a plurality of waterproof walls which are arranged alternately and partition the space in the sensor case in the axial direction are spaced apart in the axial direction, and are inclined in different directions alternately with respect to the axial direction. In this state, it is provided integrally with the sensor case,
An internal combustion engine control unit, wherein an opening is formed at an end of each of the waterproof walls farther from the atmospheric pressure sensor to connect spaces on both sides of each of the waterproof walls.

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