JP2000346737A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an atmospheric pressure introduction part from being blocked by flooding even if a height is set lower in terms of the mounting property of a sensor in the atmospheric pressure introduction type pressure sensor that is mounted on the upper surface of a fuel tank. SOLUTION: In a pressure sensor 100 that is mounted on an upper surface 201 of a fuel tank 200, a detection pressure introduction part 13 for introducing a fuel pressure and an atmospheric pressure introduction part 15 with an atmospheric pressure introduction port 16 that communicates with the atmosphere are formed at a housing 10 for accommodating a sensor element part 20, and further a waterproof cover 60 for preventing water entering the atmospheric pressure introduction port 16 is mounted. A wall part 62 of the waterproof cover 60 covers a part at the outer-periphery side of the sensor 100 out of the surrounding of a gap part 210 where the opening surface of the atmospheric pressure introduction port 16 opposes the upper surface 201 of the fuel tank 200, and a low end part 62a of the wall part 62 opposes the upper surface 201.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric pressure introduction type pressure sensor which is mounted on the upper surface of an object to be detected and detects a pressure difference (relative pressure) between the pressure from the object and the atmospheric pressure. ,
And, regarding the mounting structure of the pressure sensor with the object to be detected,
In particular, it relates to improving the waterproofness of a pressure sensor.

[0002]

2. Description of the Related Art As a pressure sensor of this type, for example,
Some vehicles are mounted on the upper surface of a fuel tank (detected body) of an automobile and detect the pressure (fuel pressure) in the fuel tank. In the past, tanks and sensors were connected by piping, but in recent years, in order to respond to higher accuracy of pressure measurement in the fuel tank,
A mounting structure for directly attaching a pressure sensor to a fuel tank has been studied. FIG. 6 shows a general schematic cross-sectional structure in the direct mounting structure.

The sensor J1 is provided with a case J2 for partitioning the main body of the sensor J1, and a sensor element J3 having a diaphragm is housed in the case J2. Case J
2, a detection pressure introduction portion J5 having an introduction passage J4 is formed, and the detection pressure introduction portion J5 is provided on the upper surface J of the fuel tank J10.
11 is fixed. Then, as shown by the arrow P, the fuel pressure from the fuel tank J10 is introduced into the sensor element J3 on the back side of the diaphragm via the introduction path J4.

The case J2 has an opening J6 communicating with the atmosphere, and an atmospheric pressure introducing portion J7 for introducing atmospheric pressure to the surface of the diaphragm of the sensor element J3. Then, the fuel tank J is detected by the sensor element J3.
The pressure difference (relative pressure) between the fuel pressure from 10 and the atmospheric pressure is detected.

[0005]

As described above, since the pressure in the tank J10 is measured relative to the atmospheric pressure, the sensor J1 is provided with the opening J6 for introducing the atmosphere. As shown in FIG. 6, the opening J6 is open downward (in the direction of gravity) (facing the upper surface J11 of the fuel tank J10) (a pilot hole type).

[0006] When the opening J6 is wet,
When the opening is in the horizontal or upward direction, the direction of gravity is different from that in the direction of gravity, so that water easily stays in the opening. Further, in order to prevent water from stagnating, the tip of the downward opening J6 is made thin as shown in the figure, so that even if the opening J6 is wet, water will be cut off at the tip and fall. It is devised.

[0007] Generally, the fuel tank J10 is
Since it is mounted under the floor of the vehicle, the floor of the vehicle comes directly above the fuel tank J10. Therefore, fuel tank J
In the upper surface (mounting surface) J11 of the sensor 10, the height of the sensor J1 is important. That is, if the height of the sensor J1 is high, the upper surface J11 of the fuel tank J10 needs to be separated from the floor of the vehicle, and for example, the capacity of the tank J10 and the cabin space are reduced accordingly. Therefore, it is necessary to reduce the mounting height of the pressure sensor J1 as much as possible (close to the upper surface J11).

However, in the pilot hole type described above, as shown in FIG. 6, when the opening J6 of the atmospheric pressure introducing portion J7 is too close to the upper surface J11 of the tank J10, the upper surface J1 is lowered.
Water easily accumulates between the hole 1 and the opening J6, and the accumulated water W closes the opening J6.

On the other hand, as shown in FIG. 7 (a), the opening J6 is moved away from the upper surface J11 of the tank J10 within a range allowable in consideration of the mountability of the vehicle so that water does not accumulate. Then, the opening J6 is closed due to the rebound of water (indicated by the arrow Y in the figure) due to the water being wetted from above.

Conventionally, as shown in FIG. 7 (b) as a schematic sectional configuration, a piping port J7a is extended from an opening 6 of an atmospheric pressure introducing portion J7, and a hose J12 is connected to the piping port 7a. There is also a hose (atmospheric pressure introduction port type) which prevents the opening J6 from being clogged by water by piping the hose J12 to a place where the water is not wetted. However, in this type, a mounting height for connecting the piping is set. Is required, and there is a restriction in reducing the mounting height.

As described above, in the fuel pressure sensor mounted on the upper surface of the fuel tank (object to be detected), a pilot hole type
Both types, the atmospheric pressure introduction port type, have a problem that there is a restriction in reducing the mounting height on the fuel tank. In addition, such a problem is a common problem in the atmospheric pressure introduction type pressure sensor mounted on the upper surface of the detected object when the space above the detected object is limited, in addition to the fuel pressure sensor. It is.

In view of the above-described problems, the present invention provides an atmospheric pressure introduction type pressure sensor mounted on the upper surface of a detection object, even if the height of the pressure sensor needs to be set lower due to the mountability of the sensor. It is an object of the present invention to prevent an atmospheric pressure introduction portion from being blocked by water.

[0013]

According to the first aspect of the present invention, there is provided an atmospheric pressure introducing type pressure sensor mounted on an upper surface (201) of an object to be detected (200). A waterproof cover (60) for surrounding the opening (16) of the portion (15) in a non-contact manner with the opening and preventing the opening from being blocked by water is provided.

According to the present invention, the waterproof cover (60) prevents the opening (16), which is the part for introducing atmospheric pressure, from being wet by water. In addition, it is possible to prevent the atmospheric pressure introduction portion from being blocked by water.

According to the second aspect of the present invention, the opening (16) of the atmospheric pressure introducing section (15) is provided with the object to be detected (200).
And a wall surrounding the waterproof cover (60) at least partially around a gap (210) in which the opening and the upper surface of the detection object face each other. (62).

According to the present invention, by arranging the wall portion (62) in a portion that is easily wetted, the same effect as the pressure sensor according to the first aspect can be obtained. Furthermore, if the wall portion (62) of the waterproof cover (60) surrounds the entire periphery of the void portion (210) as in the invention of claim 3, it is possible to more effectively prevent water from being wet. You can do it.

According to the present invention, a sensor element (21) for detecting a pressure difference between the pressure from the object to be detected (200) and the atmospheric pressure is housed therein.
When a case member (10) constituting the detection pressure introducing section (13) and the atmospheric pressure introducing section (15) is provided, the waterproof cover (60) can be disposed on the case member. Here, the waterproof cover (60) may be formed as a member separate from the case member, or may be formed integrally with the case member.

Further, the invention according to claim 7 relates to a mounting structure in which an atmospheric pressure introducing type pressure sensor (100) is mounted on the upper surface (201) of a detection object (200).
The pressure sensor is provided with a waterproof cover (60) for preventing the opening (16) from being blocked by water, so as to surround the opening in a non-contact manner with the opening.
It is possible to provide a pressure sensor mounting structure having the same functions and effects as the first aspect of the invention.

Further, the pressure sensor (100) of the atmospheric pressure introduction type is connected to the object (20).
In the mounting structure mounted on the upper surface (201) of (0), the object to be detected has an opening (1) of the atmospheric pressure introducing portion (15).
Even when a waterproof cover (65) surrounding the periphery of (6) is provided, it is possible to provide a pressure sensor mounting structure having the same operation and effect as the first aspect of the present invention.

The reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. The pressure sensor according to the present embodiment is mounted on the upper surface of a fuel tank (such as a gasoline tank) as a detection target, and is a type applied to a fuel pressure sensor that detects the pressure (fuel pressure) in the fuel tank. . 1 to 3 show a specific configuration of the pressure sensor 100 and a structure for attaching the pressure sensor 100 to the fuel tank 200. FIG.

FIG. 1 is a top view of the pressure sensor 100 mounted on the upper surface 201 of the fuel tank 200 as viewed from above the upper surface 201, and FIG. 2 is a sectional view taken along line AA in FIG. Pressure sensor 100 including part of tank 200
FIG. 2 is a schematic cross-sectional view showing the overall configuration of FIG. FIG. 3 is FIG.
It is an enlarged view of the sensor element part 20 inside. Here, upper surface 2
For 01, a wall surface of a fuel pump or the like in the fuel tank 200 may be used.

Reference numeral 10 denotes a housing (corresponding to a case member of the present invention), which is formed by molding a resin such as PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide). A recess is formed in the center of the housing 10, and a space in the recess forms a reference pressure chamber 11 into which atmospheric pressure is introduced.
And a measurement pressure chamber 12 into which the fuel pressure (measurement target pressure) from the fuel tank 200 is introduced. Both rooms 1
The sections 1 and 12 are formed by the sensor element section 20 housed and fixed in the recess.

As shown in FIG. 3, the sensor element section 20 comprises a pressure-sensitive element (corresponding to the sensor element of the present invention) 21 made of silicon or the like and a glass pedestal 22 for supporting and fixing the pressure-sensitive element 21. Have been. The pressure-sensitive element 21 has a diaphragm formed on a substrate made of, for example, silicon or the like, and is joined to a glass pedestal 22 having a thermal expansion coefficient similar to that of the pressure-sensitive element 21. The glass pedestal 22 has a through hole, and the pressure-sensitive element 21 detects a differential pressure between the atmospheric pressure introduced from the reference pressure chamber 11 and the fuel pressure introduced from the measurement pressure chamber 12. I have.

The sensor element section 20 is fixed to the housing 10 via a hollow stem 25 having a through hole. The stem 25 is a 42-alloy (Fe: Ni = 58: 4), which is a material having a thermal expansion coefficient similar to that of the glass pedestal 22.
2) is adopted, and the sensor element section 20 and the stem 25 are fixed with an adhesive such as a thermosetting resin.

The stem 25 and the housing 10 are also fixed with an adhesive such as a thermosetting resin. Sensor element 2
By fixing the stem 0 and the stem 25 to the housing 10, the fuel pressure introduced from the measurement pressure chamber 12 can be transmitted to the back surface of the pressure-sensitive element 21 (the surface on the glass pedestal 22 joining side). An adhesive 30 such as a thermosetting resin is provided in the recess of the housing 10 in order to further improve the airtightness of the fixing portion between the sensor element 20 and the stem 25 and the fixing portion between the stem 25 and the housing 10. It is filled, and in order to improve the moisture resistance of the sensor element unit 20,
The silicone gel 31 is filled.

As shown in FIG. 1, a substantially cylindrical detection pressure introducing portion 13 protruding downward is provided below the measurement pressure chamber 12 in the housing 10 (on the side opposite to the reference pressure chamber 11). It is formed as a part of the housing 10.
The detection pressure introduction section 13 is for introducing the fuel pressure into the measurement pressure chamber 12, and has an introduction passage 14 formed therein for communicating the measurement pressure chamber 12 with the outside of the housing 10.

Here, a substantially cylindrical through hole 203 is formed in the upper surface 201 of the fuel tank (detected object) 200 by forming a substantially ring-shaped groove 202 around the periphery thereof. The inside and outside of the tank 200 communicate with each other through 203. Then, the detection pressure introducing unit 13 is connected to the groove 2.
03, the pressure sensor 100 is attached and fixed to the upper surface 201 of the fuel tank 200.

The outer peripheral side surface of the hole 202 and the introduction path 14
Is sealed by interposing an O-ring 40 made of rubber or the like. O-ring 4
0 is supported by a substantially ring-shaped spacer 41. The upper portion of the reference pressure chamber 11 is closed by a lid (lid) 50 made of a resin such as PBT.
The lid 50 is airtightly fixed by an adhesive 51.

The side portion of the reference pressure chamber 2 in the housing 10 is configured as an atmospheric pressure introduction section 15 for introducing atmospheric pressure into the reference pressure chamber 2. The atmospheric pressure introduction unit 15 includes an air introduction port (corresponding to an opening of the atmospheric pressure introduction unit in the present invention) 16 communicating with the atmosphere, and an air introduction port 1.
6, a water-repellent filter 17 made of resin or the like fixed to the housing 10 by ultrasonic welding or the like.

Here, the opening surface of the air inlet 16 is spaced apart from the upper surface 201 of the fuel tank 200 and faces downward in the direction of gravity so as not to collect water.
Is opened to the atmosphere through the air inlet 16 and has the same pressure as the atmospheric pressure. The water-repellent filter 17 prevents the passage of dust, water, and the like into the reference pressure chamber 11 while allowing the flow of air.

The output terminal of the pressure-sensitive element 21 for outputting a detection signal is connected to a terminal 55 via a bonding wire 56. The terminal 55 can be electrically connected to an external circuit through a wiring member or the like. As described above, the electric signal based on the above-mentioned differential pressure detected by the pressure-sensitive element 21 is external (for example, E
CU, etc.).

The basic operation of the pressure sensor 100 is as follows. As shown by an arrow P in FIG. 2, the fuel pressure from the fuel tank 200 (the vapor pressure of gasoline vapor, etc.)
Introduced into the measurement pressure chamber 12 through the introduction path 14 and the stem 25
Is transmitted from the through hole of the glass pedestal 22 to the back surface of the pressure-sensitive element 21. The fuel pressure transmitted to the pressure-sensitive element 21 is detected as a differential pressure from the atmospheric pressure introduced from the reference pressure chamber 11 in the pressure-sensitive element 21 as described above,
The detection signal is taken out to the outside via the bonding wire 56 and the terminal 55.

Incidentally, the pressure sensor 100 is provided with a waterproof cover 60 for covering the periphery of the air inlet 16 in addition to the above configuration, so that water can be prevented from entering the air inlet 16 from the outside. It has its own configuration. The waterproof cover 60 is formed of, for example, a resin such as PBT, and has a mounting portion 61 mounted on the housing 10 above the air inlet 16 as shown in FIGS. A curved plate-shaped wall portion 62 fixed to the mounting portion 61;

The mounting portion 61 is fixed in a recess above the air inlet 16 in the housing 10 with an adhesive 63. The wall portion 62 covers a portion on the outer peripheral side of the sensor 100, around the gap portion 210 where the opening surface of the air inlet 16 and the upper surface 201 of the fuel tank 200 face each other. In the illustrated example, the lower end surface 62a of the wall portion 62 is
, But may be in contact with each other.

The distance between the opening surface of the air inlet 16 and the upper surface 201 of the fuel tank 200, that is, the width (mounting height) L of the gap 210 is set to the minimum height (3. About 5 mm). If the opening surface of the air inlet 16 is in contact with the upper surface 201, it is not preferable because water easily penetrates even with the waterproof cover 60.

As described above, the distance between the lower end surface 62a of the wall portion 62 and the upper surface 201 is shorter than the width L of the gap portion 210, that is, the lower end surface 62a of the wall portion 62 of the waterproof cover 60 is
When the opening 62 of the air inlet 16 is closer to the upper surface 201 than the opening, the wall 62 of the waterproof cover 60 covers the space 210. Therefore, it is difficult for water to accumulate between the opening surface of the air inlet 16 and the upper surface 201 (that is, the gap 210), and it is possible to prevent the water that has fallen on the upper surface 201 from entering the air inlet 16 due to rebound. .

Therefore, according to the present embodiment, the waterproof cover 60 prevents the air inlet 16 from being wet by water.
Even if the height L is set to be low due to the mountability of the sensor, it is possible to prevent the atmospheric pressure introduction port 16 from being blocked by water. According to the present pressure sensor 100, FIG.
As in the case of the atmospheric pressure introduction port type shown in (b), a piping port or the like for piping is not required in the atmospheric pressure introduction section 15, and the height of the sensor itself can be reduced accordingly.
The height including the sensor 100 on the upper surface 201 of the 00 can be suitably reduced.

The wall portion 62 covers a portion of the periphery of the gap portion 210 on the outer peripheral side of the sensor 100, because the outer peripheral side of the sensor 100 is easily wetted. Note that the wall portion 62 does not have to surround a part of the gap portion 210 but may surround the entire circumference. That is,
As shown by the shape obtained by adding the broken line K to the solid line in FIGS. 1 and 2, if the entire periphery of the gap portion 210 is covered in a cylindrical shape, it is possible to more effectively prevent water from being wet.

Here, the effects of the waterproof cover 60 will be described more specifically based on test results. FIG. 4 shows the height from the upper surface (mounting surface) 201 of the fuel tank 200 (corresponding to the width of the gap 210) for the case without the waterproof cover 60 (the product without the cover) and the case with the waterproof cover 60 (the product with the cover). This shows the presence or absence of blockage of the air introduction port 16 when a water spray test (based on JIS0203) is performed while changing L.

The dimensions of the height L are 3.5 mm, 10 mm,
It was changed to 20 mm, 30 mm, and 40 mm. In the table in FIG. 4, for example, 3/4 indicates that the number of tests was four, and that three of the air inlets 16 were closed.
4, the height of the air inlet 16 from the upper surface 201 is required to be 30 mm or more in order to prevent the air inlet 16 from being blocked in the product without the cover, while in the product with the cover, the height from the upper surface 201 to the air is higher. The height of the inlet 16 is 3.5 mm
The air inlet 16 was not blocked even when approached. (Other Embodiments) In the above embodiment, the air inlet 16 of the atmospheric pressure inlet 15 is connected to the upper surface 2 of the fuel tank 200.
Although the air inlet 16 faces downward in the direction of gravity while being separated from the upper surface 01, the opening surface of the air inlet 16 does not have to face the upper surface 201 and may be inclined downward. Even in that case,
A similar effect can be obtained by covering the periphery of the air inlet 16 with the wall 62 of the waterproof cover 60.

The waterproof cover 60 is not limited to resin, but may be any material such as metal as long as it can be formed into a plate shape, such as the wall portion 62. Further, the waterproof cover 60 does not need to be separate from the housing (case member) 10. The shape of the waterproof cover 60 may be added to a mold, and the waterproof cover 60 may be integrally formed when the housing 10 is molded.

Further, in the above mounting structure, the waterproof cover 6 for preventing water from entering the air inlet 16 is provided.
0 is provided on the housing 10 of the pressure sensor 100, but such a waterproof cover does not necessarily need to be installed on the pressure sensor body, and as shown in FIG.
It may be installed on the fuel tank 200 side.

The waterproof cover 6 in the mounting structure shown in FIG.
Numeral 5 is made of, for example, resin, and is joined to the upper surface 201 of the fuel tank 200 with an adhesive or the like, or
It is integrally molded with. This waterproof cover 65 also
It forms a wall shape that covers the periphery of the air inlet 16,
Like the waterproof cover 60 shown in FIGS. 1 and 2, it is possible to prevent water from entering the air inlet 16. Therefore, also in the mounting structure shown in FIG. 5, the mounting height of the sensor can be reduced while preventing the atmospheric pressure introduction portion from being clogged by water.

It is preferable that the waterproof cover 60 shown in FIGS. 1 and 2 and the waterproof cover 65 shown in FIG. 5 be transparent, since the appearance of the air inlet 16 can be seen. Further, the pressure sensor 100 is not limited to a fuel pressure sensor, and may be applied to, for example, a sensor mounted on the upper surface of a gas tank of a high-pressure gas device and measuring the gas pressure in the tank as a relative pressure to the atmospheric pressure. it can. In this case, reducing the mounting height can contribute to downsizing of the gas device.

In addition, the present invention relates to an atmospheric pressure introduction type pressure sensor mounted on the upper surface of a detection object, when the mounting height is restricted, such as when the space above the detection object is limited. It is suitable for use.

[Brief description of the drawings]

FIG. 1 is a top view in a mounted state of a pressure sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is an enlarged view of a sensor element unit in FIG.

FIG. 4 is a view showing the results of a test on the effect of the presence or absence of a waterproof cover according to the present invention.

FIG. 5 is a schematic cross-sectional view showing an attachment structure in which a waterproof cover is provided on a detection target side.

FIG. 6 is a schematic sectional view showing a mounting structure of a conventional general pressure sensor.

7A is a schematic cross-sectional view illustrating closure of an opening due to rebound of water in the mounting structure shown in FIG. 6, and FIG.
It is a schematic sectional drawing which shows the mounting structure of the conventional atmospheric pressure introduction port type pressure sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Housing, 13 ... Detection pressure introduction part, 15 ... Atmospheric pressure introduction part, 16 ... Atmospheric introduction port, 21 ... Pressure sensitive element, 60, 6
5: waterproof cover, 62: wall, 100: pressure sensor, 2
00: fuel tank, 201: upper surface of fuel tank, 210
... voids.

Continued on the front page (72) Inventor Masaki Takakuwa 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 2F055 BB03 BB05 CC02 DD05 EE11 FF38 GG25 HH05 HH11

Claims (8)

[Claims] 1. A detection pressure introduction part (13) mounted on an upper surface (201) of a detection target (200) for introducing pressure from the detection target, and an opening (16) communicating with the atmosphere. A pressure sensor having an atmospheric pressure introducing section (15) for introducing atmospheric pressure, wherein the pressure sensor detects a pressure difference between the pressure from the object to be detected and the atmospheric pressure. A pressure sensor having a waterproof cover (60) that surrounds the periphery thereof in a non-contact manner with an opening and prevents the opening from being blocked by water. 2. The opening (16) of the atmospheric pressure introducing section (15) is connected to the upper surface (20) of the object to be detected (200).
The waterproof cover (60) surrounds at least a part of a periphery of a gap (210) where the opening and the upper surface of the detection object face each other. The pressure sensor according to claim 1, wherein the pressure sensor has (62). 3. The gap (21) is formed by the wall (62).
The pressure sensor according to claim 2, wherein the pressure sensor surrounds the entire circumference of (0). 4. A case member (10) containing a sensor element (21) for detecting the differential pressure therein and constituting the detection pressure introduction section (13) and the atmospheric pressure introduction section (15). The waterproof cover (60) is disposed on the case member, and the waterproof cover (60) is provided on the case member.
4. The pressure sensor according to any one of the above. 5. The pressure sensor according to claim 4, wherein the waterproof cover (60) is made of a member separate from the case member (10) and is joined to the case member. 6. The pressure sensor according to claim 4, wherein the waterproof cover (60) is formed integrally with the case member (10). 7. A detection pressure introducing section (13) for introducing pressure from an object to be detected (200) and an atmospheric pressure introduction having an opening (16) communicating with the atmosphere for introducing atmospheric pressure. A pressure sensor (100) including a portion (15) for detecting a differential pressure between the pressure from the detected object and the atmospheric pressure.
Is mounted on the upper surface (201) of the detection object, wherein the pressure sensor includes a waterproof cover (60) for preventing the opening from being blocked by water. The pressure sensor mounting structure is provided so as to surround the periphery of the pressure sensor without contact with the opening. 8. A detection pressure introducing section (13) for introducing pressure from a detection target (200) and an atmospheric pressure introduction having an opening (16) communicating with the atmosphere for introducing atmospheric pressure. A pressure sensor (100) including a portion (15) for detecting a differential pressure between the pressure from the detected object and the atmospheric pressure.
Is mounted on the upper surface (201) of the object to be detected, wherein the object to be detected is provided with a waterproof cover (65) surrounding the periphery of the opening. Pressure sensor mounting structure.