JPH09195813A - Intake air pressure detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any moisture adsorbed on a filter of fine meshes to evaporate to reach an intake air pressure sensor, thereby to prevent the intake air pressure sensor from being frozen when an internal combustion engine is placed in switch off, in an intake air pressure detector to which a filter of fine meshes is applied. SOLUTION: With regard to an intake air pressure detector, a filter part 15 is arranged in the intake air passage 12 of an internal combustion engine and a filter 33 of fine meshes is arranged on the upper end inside the filter case 19 of the filter part 15. The filter part 15 is communicated with the pressure sensing part 27 of an intake air pressure sensor 26 by means of pressure leading passages 48, 49. A bulkhead 37 is formed in the pressure leading passages 48, 49 and two check valves 39, 40 whose mutually allowable directions of flow are different from each other are arranged on the bulkhead 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake pressure detecting device for detecting intake pressure from an intake passage of an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional intake pressure detecting device for an internal combustion engine. The intake passage 12 in the surge tank 11 is communicated with an upstream (right side in FIG. 2) air cleaner, a throttle valve, and a downstream (left side in FIG. 2) intake manifold (none are shown). The pressure detection unit case 18 of the intake pressure detection unit 14 and the filter case 19 of the filter unit 15 are integrally formed vertically, and the pressure detection unit case 18 and the filter case 19 are formed.
The first partition wall 20 is formed between the first and second walls. A pressure introducing port 29 is formed in the central portion of the first partition wall 20 to communicate with the upper and lower sides of the first partition wall 20, and a flange portion 22 is formed on the outer side of the first partition wall 20. A mounting hole 23 is formed in the upper wall of the surge tank 11, the filter portion 15 is inserted into the mounting hole 23, and the flange portion 22 is fixed to the upper wall of the surge tank 11 by bolts 24 or the like. In this way, the filter portion 15 is the space of the intake passage 12 of the surge tank 11.
Placed at 13. An intake pressure sensor 26 is arranged at the upper end of the pressure detection unit case 18, and a pressure sensitive portion 27 of the intake pressure sensor 26 and a pressure introduction port 29 are connected by an airtight pressure guiding passage 28.

On the side surface of the filter case 19, windows 31 through which intake air can flow in and out are formed, and a coarse filter 32 is attached to the entire surfaces of these windows 31. To cover the pressure inlet 29 of the first partition wall 20 of the ceiling of the filter case 19 from below,
A fine fibrous filter 33 is attached to the inner upper end of the filter case 19. A drain hole 35 is formed in the lower bottom wall of the filter case 19, and residual water, oil mist and the like accumulated on the bottom of the filter case 19 are discharged from the drain hole 35. The intake pressure in the intake passage 12 is adjusted by a coarse filter.
It is guided to the pressure sensing section 27 of the intake pressure sensor 26 through the fine fibrous filter 33, the pressure introducing port 29, and the pressure guiding passage 28. Further, since the filter portion 15 is arranged in the space 13 in which the flow of intake air flows, contaminants such as oil mist, soot, sludge, and moisture adsorbed on the surfaces of the coarse filter 32 and the fine filter 33, It is said that it is removed (purged) by the subsequent flow of intake air, and the accumulation of contaminants on the filters 32 and 33 is prevented. Moreover, since it has a two-layer structure of a filter 32 having a coarse mesh and a filter 33 having a fine mesh, it is possible to completely prevent the inflow of contaminants and prevent clogging.

[0004]

In the conventional intake pressure detecting device, the intake air mainly flows across the coarse filter 32 as shown by an arrow A in FIG. 2, and the fine fibrous filter 33 is provided. There is almost no intake air flowing inside. Therefore, contaminants such as water adsorbed and deposited on the fine filter 33 are not easily removed by the flow of intake air. Then, when the temperature in the vicinity of the filter unit 15 is high, immediately after the switch of the internal combustion engine is turned off, the water adsorbed on the fine filter 33 is evaporated to become water vapor, and the water vapor passes through the pressure inlet 29 and the pressure guiding passage 28. It is led to the intake pressure sensor 26 through
Water vapor adheres to the surface of the pressure sensitive portion 27. When the outside air temperature is low, the temperature of the pressure-sensitive portion 27 may be lowered thereafter, and the moisture adhering to the pressure-sensitive portion 27 may freeze, causing malfunction of the intake pressure sensor 26. The present invention, in an intake pressure detection device using a fine filter, prevents moisture adsorbed to the fine filter from evaporating and reaching the intake pressure sensor when the switch of the internal combustion engine is turned off. Therefore, it is an object to prevent the intake pressure sensor from freezing.

[0005]

According to the present invention, a filter section is arranged in an intake passage of an internal combustion engine, and a fine filter is arranged at an upper end of a filter case of the filter section. In the intake pressure detecting device in which the pressure sensing portion is communicated with the pressure guiding passage, a partition wall is formed in the pressure guiding passage, and two check valves having mutually different flow directions are arranged in the partition wall. The configuration.
In the above configuration, the two check valves are umbrella check valves, a plurality of communication holes penetrating the partition wall are formed, and the valve seat of each umbrella check valve is formed by the opening of the communication hole and the surface of the partition wall. The umbrella-type valve body of each umbrella check valve may be configured such that the umbrella check valve is opened and closed by coming into contact with or leaving the umbrella seat.
In the above two configurations, a window through which intake air can flow in and out is formed on a side surface of the filter case of the filter portion, and a coarse filter is attached to the entire surface of the window so that the intake air flows across the coarse filter. be able to.

[0006]

1 (a) is a sectional view showing an embodiment of an intake pressure detecting device of the present invention, and FIG. 1 (b) is a second embodiment.
Partition wall 37, first check valve 39, second check valve 40
3 is a plan view showing the upper surface of FIG. In FIG. 1 (a), the same members as those in the conventional example of FIG. 2 are designated by the same reference numerals as those in FIG. 2, and the description thereof will be omitted. In the embodiment of the present invention, the pressure guiding passage 28 of the pressure detecting portion case 18 is made longer (the distance between the first partition wall 20 and the pressure sensing portion 27 is made longer) as compared with the conventional example of FIG.
Thus, the second partition 37 is formed in the pressure guiding passage 28. The pressure guiding passage 28 is divided into two by the second partition wall 37, and a passage between the first partition wall 20 and the second partition wall 37 is referred to as a first pressure guiding passage 48.
The passage between the pressure sensing portion 27 and the pressure sensing portion 27 will be referred to as a second pressure guiding passage 49. A first check valve 39 and a second check valve 40 are arranged in the second partition wall 37, and the first check valve 39 only allows one-way fluid flow from the first pressure passage 48 to the second pressure passage 49. The second check valve 40 and the second pressure guide passage 49.
From the first to the first pressure guiding passage 48, allowing only one direction of fluid flow and blocking the opposite direction of flow. The first check valve 39 and the second check valve 40 shown in the figure are both umbrella check valves, and the umbrella check valve reliably functions as a check valve even if the pressure difference is low.

The first check valve 39 and the second check valve 40 include umbrella type valve bodies 41, 42, a valve seat and a communication hole 4
There are 5 and 46, and the umbrella type valve bodies 41 and 42 are flexible. A plurality of communication holes 45 and 46 penetrating the second partition wall 37 are formed, the surface of the second partition wall 37 and the openings of the communication holes 45 and 46 serve as valve seats, and the umbrella portion of the umbrella type valve body is mounted on the valve seat. Contact and leave. The rod-shaped portions (handles) of the umbrella-type valve bodies 41, 42 are maintained by being inserted through the insertion holes formed in the second partition wall 37, and the center of the umbrella portion of the umbrella-type valve bodies 41, 42 does not move, but the umbrella portion. Parts other than the center of can be moved up and down. The umbrella portion of the umbrella-type valve bodies 41, 42 includes a first pressure guide passage 48.
And a portion of the communication holes 45 and 46 (valve seats) other than the center move up and down so that the opening angle of the rain umbrella changes due to the force due to the pressure difference between the second pressure guiding passage 49 and the second pressure guiding passage 49. Open and close with respect to.

The pressure in the first pressure guiding passage 48 is equal to the pressure in the second pressure guiding passage 49.
When the pressure is higher than the internal pressure, the umbrella-shaped portion of the umbrella-type valve body 41 of the first check valve 39 separates from the opening of the communication hole 45 and the fluid from the first pressure passage 48 to the second pressure passage 49 flows. The flow is allowed, and at the same time, the umbrella-shaped portion of the umbrella-type valve body 42 of the second check valve 40 is pressed against the opening of the communication hole 46, so that the fluid flows from the first pressure passage 48 to the second pressure passage 49. Prevent. When the pressure in the second pressure guiding passage 49 is higher than the pressure in the first pressure guiding passage 48, the umbrella-shaped portion of the umbrella type valve body 41 of the first check valve 39 presses against the opening of the communication hole 45. The second pressure guide passage 49 to the first pressure guide passage.
The flow of the fluid to 48 is prevented, and the umbrella-shaped portion of the umbrella-type valve body 42 of the second check valve 40 is separated from the opening of the communication hole 46 to the second pressure passage 49 to the first pressure passage 48. Allow fluid flow.

As described above, the second pressure guiding passage 49 having the pressure sensing portion 27 is provided.
The first check valve 39 intakes air to the first pressure guide passage 48, and the second check valve 40 exhausts air from the second pressure guide passage 49 to the first pressure guide passage 48. The first check valve 39 and the second check valve 40 are not limited to umbrella check valves, and may be poppet-type check valves or speaking-type (swing-type) check valves as long as the opening pressure is low. Other configurations of the embodiment of the intake pressure detecting device of the present invention are similar to those of the conventional example of FIG.

The operation of the embodiment of the intake pressure detecting device of the present invention will be described. When the switch of the internal combustion engine is turned on to operate the internal combustion engine, the intake pressure in the intake passage 12 changes, and the pressure difference between the first pressure passage 48 and the second pressure passage 49 also changes. . The intake pressure in the intake passage 12 is
The pressure sensitive portion of the intake pressure sensor 26 is transmitted to the second pressure guiding passage 49 through the coarse filter 32, the fine filtering 33, the pressure introducing port 29, the first pressure guiding passage 48, and the first check valve 39.
Guided by 27. The gas in the second pressure guiding passage 49 passes through the second check valve 40, the first pressure guiding passage 48, the pressure introducing port 29, the fine filter 33, and the coarse filter 32, and the intake passage.
Exhausted into 12. In this way, the fine filter 33
The first check valve 39 and the second check valve 40 suck and exhaust between the pressure sensing portion 27 and the pressure sensing portion 27.

Next, when the operation of the internal combustion engine is stopped by turning off the switch of the internal combustion engine, the pressures in the first pressure guiding passage 48 and the second pressure guiding passage 49 are substantially atmospheric pressure. 1
The check valve 39 and the second check valve 40 are closed. Therefore, immediately after turning off the switch of the internal combustion engine because the temperature in the vicinity of the filter unit 15 is high, the moisture adsorbed on the fine filter 33 is evaporated to become water vapor, and the water vapor passes through the pressure introduction port 29 and the first pressure guiding passageway. Even when entering 48, since the first check valve 39 and the second check valve 40 are closed,
The water vapor cannot reach the pressure sensitive portion 27 of the intake pressure sensor 26.

[0012]

In the intake pressure detecting device of the present invention, a partition wall is formed in the pressure guiding passage, and two check valves having mutually different flow directions are arranged in the partition wall. Therefore, when the operation of the internal combustion engine is stopped by turning off the switch of the internal combustion engine, the operation of the internal combustion engine is stopped even if water adsorbed on the fine filter evaporates due to high temperature near the filter section. When this is done, the pressure in the vicinity of the two check valves is almost atmospheric pressure, so the two check valves are closed. Therefore, the flow of water vapor is blocked by the two check valves, and it is prevented that the water vapor reaches the pressure sensitive portion of the intake pressure sensor, and the moisture does not adhere to the pressure sensitive portion. Will not freeze.

[Brief description of the drawings]

FIG. 1 (a) is a sectional view showing an embodiment of an intake pressure detecting device of the present invention, and FIG. 1 (b) is a plan view showing an upper surface of a main part of FIG. 1 (a). .

FIG. 2 is a sectional view showing a conventional intake pressure detection device.

[Explanation of symbols]

 12 Intake passage 15 Filter section 19 Filter case 26 Intake pressure sensor 27 Pressure sensing section 33 Fine filter 37 Second partition wall 39 First check valve 40 Second check valve 48 First pressure passage 49 Second pressure passage

Claims (3)

[Claims] 1. A filter section is arranged in an intake passage of an internal combustion engine, a fine filter is arranged at an upper end of a filter case of the filter section, and the filter section and a pressure sensing section of an intake pressure sensor are pressure guiding passages. In the intake pressure detecting device communicated with each other, a partition is formed in the pressure guiding passage, and two check valves having mutually different flow directions are arranged in the partition. 2. The two check valves are umbrella check valves, a plurality of communication holes penetrating the partition wall are formed, and the valve seat of each umbrella check valve is constituted by the opening of the communication hole and the surface of the partition wall. 2. The intake pressure detecting device according to claim 1, wherein the umbrella check valve is opened and closed by contacting or leaving the umbrella-shaped valve body of each umbrella check valve with or away from the valve seat. 3. A window through which intake air can flow in and out is formed on a side surface of the filter case of the filter portion, and a coarse filter is attached to the entire surface of the window so that the intake air flows across the coarse filter. The intake pressure detecting device according to claim 1.