JPH09229737A - Apparatus for measuring flow rate of air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an air flow rate measuring apparatus from being corroded or broken and improve the reliability and safety by forming a recess at a module-fixing face and a groove or hole communicating the inside with the outside of the recess. SOLUTION: A mounting fixing face 12 for fixing a base member 13 of a circuit module 10 is formed schematically in the same outside shape as the base member 13. A recess 19 is formed inside the face 12. A plurality of grooves 18 are formed nearly symmetrically to the vicinity of the center of an insertion hole 11 of a wall-like part 16 surrounding the periphery of the insertion hole 11. The recess 19 prevents the member 13 from interfering with the fixing face 12 even if a projection or the like is present at a bottom face of the member 13 or the bottom face is not flat. Even when water enters a gap between the member 13 and fixing face 12 or a body 1 is mounted in an inclined state to a horizontal plane, the water is discharged through the grooves 18 and not left in the recess 19. The corrosion/deterioration of peripheral members such as the member 13, body 1, etc., is lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow rate measuring device which constitutes an intake system of an internal combustion engine and measures a flow rate flowing through an intake air passage thereof, and more particularly to measuring an air flow rate taken into an automobile engine. The present invention relates to an exothermic resistance type air flow rate measuring device suitable for

[0002]

2. Description of the Related Art As a known example of the present invention, Japanese Patent Application No.
-There is an air flow measuring device described in the specification No. 116240,
In order to insert the sub passage into the main passage, the outer wall of the main passage is provided with a hole that communicates the outside with the inside, and when the sub passage is inserted, an O-ring is used to prevent air leakage from the inside to the outside of the main passage. It is hermetically sealed and has a mounting and fixing surface provided on the outer wall of the body for mounting the circuit module. However, since there is no drainage groove or hole as described in the present invention, consideration is given to the reliability when water enters the gap between the circuit module fixing surface of the outer wall of the main body forming the main passage and the bottom surface of the base member. Absent.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to improve the reliability and safety of an air flow rate measuring device sucked into an engine of an automobile or the like, and prevent corrosion and damage of the device.

(1) Water enters the gap between the fixed surface of the circuit module provided on the outer wall of the body and the bottom surface of the base member to collect water, which causes corrosion and deterioration of peripheral members, and the expansion force caused by freezing and the like. It is necessary to prevent the module from being damaged or deformed by applying force to the mounting surface of.

(2) Since the electronic circuit is fixed to the base member, there is a risk that the electronic circuit will be damaged if some object directly contacts the base member and a force is applied. In addition, even if the base member is electrically joined to the electronic circuit by metal, the electronic circuit may be damaged due to an electric factor. Therefore, the fixing surface provided on the outer wall of the body for mounting the circuit module is It is necessary to have a structure that prevents exposure.

[0006]

[Means for Solving the Problems]

(1) A groove or a through hole is provided in a part of the fixed surface of the circuit module so that water that has entered through the gap with the bottom surface of the base member can escape.

(2) The circuit module fixing surface provided on the outer wall of the body has the same shape as the base member or surrounds the base member to prevent the bottom surface of the base member from being exposed.

(3) The water draining grooves and holes are provided at two or more points in opposite directions with respect to the vicinity of the center of the recess.

[0009]

1 is a cross-sectional view of an air flow rate measuring device showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view seen from the left side of FIG. The intake air passes through the main passage 2 and the sub passage 3 formed in the body 1 and is supplied to the engine. A heat generating resistor 4 and a temperature sensitive resistor 5 for measuring an air flow rate are installed inside the sub passage 3, and the heat generating resistor 4 and the temperature sensitive resistor 5 are installed.
Are electrically connected to the support pins 6 and are connected to the electronic circuit 8 via the lead wires 7. The electronic circuit 8 is configured to output a signal related to the air flow rate based on the output signals of the heating resistor 4 and the temperature sensitive resistor 5. The member 9 forming the sub passage 3 is a circuit module 10 for installing an electronic circuit.
Fixed to The body 1 is provided with an insertion hole 11 into which the sub-passage forming member 9 can be inserted, the insertion hole 11 having a size that does not interfere with the insertion, and an attachment fixing surface 12 for attaching the circuit module 10. The sub-passage forming member 9 is inserted into the insertion hole 11 of the body 1, an O-ring 14 is attached to the base member 13 so that the periphery of the insertion hole 11 is sealed, and the base member 13 is screwed to the attachment fixing surface 12 of the body. 1
5 fixed.

The mounting and fixing surface 12 has an outer shape that is substantially the same as the outer shape of the base member 13 and has a recessed inside. FIG. 3 shows the shape of the fixing surface 12 when the circuit module 10 is not fixed. The mounting / fixing surface 12 has an outer shape that is substantially the same as that of the circuit module 10, and for fixing the circuit module 10 to the wall-shaped portion 16 that is formed with a recess 19 inside and surrounds the periphery of the insertion hole 11. And a groove 18 provided at three places substantially symmetrically with respect to the vicinity of the center of the insertion hole 11 of the wall-shaped portion 16.

Therefore, even if the bottom surface of the base member 13 has a projection or the like and is not flat, it escapes at the recess 19.
Since interference with the mounting / fixing surface 12 can be prevented, and even if water or the like penetrates into the gap between the base member 13 and the mounting / fixing surface 12, even if the body is mounted tilted with respect to the horizontal line, it escapes from any of the grooves 18, It is possible to reduce corrosion and deterioration of the base member 13 and the body 1 without accumulating in the recesses 19, and also to fill the gap between the base member 13 and the mounting and fixing surface 12 with water and freeze the water. Member 13
It is possible to prevent the base member 13 or the electronic circuit 8 from being damaged or deformed by the expansion force applied to the base member 13.

On the other hand, since the mounting fixing surface is formed in the outer circumferential direction of the circuit module 10, the mounting inclination of the circuit module 10 can be reduced, and the inside and outside of the intake passage can be sealed by the insertion hole 11 portion. Since the sealing member can be downsized and the deterioration of reliability due to the above-mentioned water pool can be prevented without sealing at the outer peripheral portion, the outer peripheral flatness does not have to be strict, and by providing the recesses 19 of the body 1. Since the wall thickness can be made uniform, the deformation of the plastic molded product due to sink marks at the time of molding can be reduced, and the body can be manufactured easily and at low cost. Further, even if the base member 13 is made of metal and is electrically connected to the electronic circuit 8, since the exposure of the base member 13 to the outside is extremely small, the base member is electrically apologized to external devices. It is possible to prevent an abnormality in the electronic circuit due to the connection.

FIG. 4 shows the shape of the mounting and fixing surface of another embodiment.

The mounting and fixing surface 12 is formed closer to the insertion hole than in the embodiment, and the surfaces actually contacting the base member 13 are the four shaded portions in FIG. 4, and the other portions are lowered by one step. . This maintains the flatness of the connection surface of the body 1 with the base member 13 at a limited four points with high accuracy, improves the measurement accuracy of the air flow rate measuring device, and reduces the reliability due to water pools. It is possible to prevent it, and the body itself can be manufactured at low cost. Further, in the present embodiment, the case where there is a body dedicated to the air flow rate measuring device has been described, but it is also possible to use an existing intake system component such as the duct portion of the air cleaner in place of the body.

[0015]

As described above, according to the present invention, it is possible to prevent the device for measuring the flow rate of the air drawn into an automobile engine or the like from being corroded or damaged, and to enhance the reliability and safety of the device.

(1) Water enters through the gap between the circuit module fixing surface provided on the outer wall of the body and the bottom surface of the base member, and water or the like collects in the gap between the circuit module fixing surface and the outer wall of the body to corrode peripheral members. It is possible to prevent the module from being damaged by the force applied to the mounting surface of the circuit module due to the expansion force due to freezing or the like.

(2) It is possible to prevent the electronic circuit from being damaged by the direct contact of some object with the base member and the damage to the electronic circuit, or the damage to the electronic circuit due to a short circuit when the base member is electrically connected with metal. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an air flow measuring device showing an embodiment of the present invention.

FIG. 2 is a side view seen from the left side of FIG.

FIG. 3 is a plan view showing the shape of a mounting and fixing surface.

FIG. 4 is a plan view showing the shape of a mounting and fixing surface according to another embodiment.

[Explanation of reference numerals] 1 ... Body, 2 ... Main passage, 3 ... Sub passage, 4 ... Heating resistor, 5 ... Temperature sensitive resistor, 6 ... Support pin, 7 ... Lead wire, 8
... electronic circuit, 9 ... auxiliary passage constituting member, 10 ... circuit module, 11 ... insertion hole, 12 ... circuit module, 13 ... base member, 14 ... sealing member.

Claims (8)

[Claims] 1. A module in which a heating resistor for measuring an air flow rate and a temperature sensing resistor for temperature compensation are integrated with an electronic circuit, and the heating resistor and the temperature sensing resistor are provided inside an intake passage of an internal combustion engine. In the air flow rate measuring device in which the module is fixed to the outer wall surface of the intake passage so that the heating resistor and the temperature sensitive resistor are located inside the intake passage. A hole communicating between the outside and the inside of the intake passage for inserting from the outside, and a fixing surface for fixing the module to the outer wall surface of the intake passage,
An air flow rate measuring device having an outer wall structure of an intake passage, wherein a groove is formed in the fixed surface and a groove or hole communicating between the inside and the outside of the recess is provided. 2. The air flow rate according to claim 1, wherein an outer shape of the fixed surface provided on the outer wall surface of the intake passage is substantially the same as an outer shape of a portion of the module facing the intake passage or a shape surrounding the module. measuring device. 3. A module in which a heating resistor for measuring an air flow rate and a temperature sensing resistor for temperature compensation are integrated with an electronic circuit, and the heating resistor and the temperature sensing resistor are provided inside an intake passage of an internal combustion engine. In the air flow rate measuring device in which the module is fixed to the outer wall surface of the intake passage so that the heating resistor and the temperature sensitive resistor are located inside the intake passage. And a hole such as an O-ring that seals the inside and the outside of the intake passage when a part of the module is inserted into the communication hole. A fixing surface that is in contact with the module and is formed on the outer wall surface of the intake passage in the outer peripheral direction of the sealing portion, and the fixing surface is formed so that water or the like does not collect between the sealing portion and the fixing surface. Is in the outer peripheral direction Air flow rate measuring device, characterized in that forming the opening portion. 4. A module in which an electronic circuit is fixed to the upper surface of a metal base member, and the heating resistor and the temperature sensitive resistor are fixed to the lower surface of the metal base in an intake passage of an internal combustion engine. In an air flow rate measuring device in which the module is fixed to an outer wall surface of the intake passage so that the heat generating resistor and the temperature sensitive resistor are located in the A hole communicating between the inside and the outside of the intake passage for inserting from the outside to the inside of the passage, a fixing surface on the outer wall surface of the intake passage where the module is fixed in contact with the metal base, and the fixing surface An air flow measuring device comprising an intake passage having a groove or a hole which forms a recess so as to partially contact the metal base and communicates the inside and the outside of the recess. 5. The fixing surface formed on the outer wall surface of the intake passage according to claim 4, wherein the fixing surface is substantially the same as the outer shape of the metal base or a shape surrounding the metal base, and the metal base is fixed to the intake passage. The air flow rate measuring device in which a portion exposed in a closed state is made small, and further, the fixing surface is formed as a recess having an outer wall and a groove or a hole communicating between the inside and the outside of the recess is provided. 6. The method of claim 1, 2, 3, 4, or 5,
An outer wall surface of the intake passage is formed in a wall shape surrounding an outer peripheral direction of a hole that communicates the outside and the inside of the intake passage, and an upper surface thereof does not come into contact with a portion in contact with a surface of the module that contacts the outer wall of the intake passage. An air flow rate measuring device having a module fixing portion having a stepped portion as described above and further having a groove or hole communicating the inside and the outside of the wall-shaped portion. 7. The groove or hole communicating between the inside and the outside of the recessed portion according to claim 1, 2, 3, 4, 5 or 6, at a plurality of locations opposite to the vicinity of the center of the recessed portion. Air flow rate measuring device installed in. 8. A component constituting an intake passage of an internal combustion engine having an outer wall portion having the shape of the module mounting portion according to claim 1, 2, 3, 4, 5, 6 or 7.