JP2003315195A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor that depends less on temperature and excels in pressure detection accuracy and in transient responsiveness to pressure fluctuation, in measuring pressure. <P>SOLUTION: The pressure sensor 1 has a connector housing 30 having a pressure bearing surface 21 with a pressure-sensitive element 20, a sensor housing 40, and a pressure chamber 42 formed between the sensor housing 40 and the connector housing 30 when the connector housing 30 is inserted along a constant insertion axis 33 into the sensor housing 40. The pressure chamber 42 houses the pressure-sensitive element 20. The pressure chamber 42 is fitted with a cover 60 covering the pressure-sensitive element 20. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pressure sensor for measuring pressure by a pressure sensitive element.

[0002]

2. Description of the Related Art A pressure sensor is a sensor using a pressure sensitive element having a strain gauge formed on a silicon substrate and a diaphragm for pressure detection formed by precisely etching the silicon substrate. The pressure sensor measures the strain generated in the diaphragm when the pressure is applied by the strain gauge.

As shown in FIG. 9, a conventional pressure sensor 9 includes a connector housing 930 having a pressure receiving surface 932 on which a pressure sensitive element 920 is arranged, and a seal diaphragm 943.
And a sensor housing 940 having In this pressure sensor 9, the connector housing 930 is inserted into the sensor housing 940 so that the seal diaphragm 943 and the pressure receiving surface 932 face each other in the front and a pressure chamber 942 is formed therebetween. Then, the pressure chamber 942 is filled with a non-compressed fluid such as silicon oil as a pressure transmission medium. When measuring the pressure of the measurement environment 944 by the pressure sensor 9, the pressure introduced to the seal diaphragm 943 side through the pressure introduction hole 941 acts on the pressure sensitive element 20 via the pressure transmission medium. Let

[0004]

However, the conventional pressure sensor 9 has the following problems. That is,
The pressure sensitive element 920 is exposed on the pressure receiving surface 932 of the connector housing 930. Therefore, when the sensor housing 940 and the connector housing 930 are assembled, or when the connector housing 930 with the pressure-sensitive element 920 is stored, the pressure-sensitive element 920, the bonding wire connected to the pressure-sensitive element 920, or the like is used. Trouble is likely to occur. Therefore, when manufacturing the pressure sensor 9, it was difficult to increase the productivity sufficiently.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a pressure sensor having high productivity.

[0006]

According to the present invention, a connector housing having a pressure receiving surface on which a pressure sensitive element is arranged, a sensor housing, and the connector housing are fitted into the sensor housing along a fixed insertion axis. A pressure sensor having a pressure chamber formed between a sensor housing and the connector housing, wherein the pressure chamber contains the pressure-sensitive element, wherein the pressure chamber has the pressure-sensitive element. A pressure sensor is characterized in that a cover is attached so as to cover it (Claim 1).

In the pressure sensor of the present invention, a cover is attached so as to cover the pressure sensitive element. Therefore, in manufacturing the pressure sensor, the pressure-sensitive element and the bonding wire connected to the pressure-sensitive element are not damaged.

As described above, the pressure sensor according to the present invention is
Trouble does not occur in the pressure-sensitive element and the bonding wire connected to the pressure-sensitive element, and the pressure-sensitive element can be manufactured with high productivity.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The cover in the present invention can be made of a material such as PPS resin. The pressure-sensitive element is attached such that an angle formed by a direction of a normal line outward from an element surface of the pressure-sensitive element and an insertion direction of the insertion shaft is in a range of 60 degrees to 100 degrees. Preferably (claim 2). Here, the pressure-sensitive element has a flat plate shape with a thin thickness in the direction normal to the element surface. Therefore, when the pressure-sensitive element is attached so that the angle formed by the direction of the normal line outward from the element surface and the insertion direction of the insertion shaft is in the range of 60 to 100 degrees, It is possible to reduce the area of the projection region that projects the pressure element in the insertion axis direction, that is, the projection area in the axial direction. Further, by suppressing the projected area in the axial direction, the pressure chamber can reduce the cross-sectional area orthogonal to the insertion axis. As a result, the entire pressure sensor having this pressure chamber can be downsized.

On the other hand, if the angle formed by the direction of the normal line outward from the element surface of the pressure sensitive element and the insertion direction of the insertion axis is 60 to 100 degrees, the sensor is The insertion distance of the connector housing with respect to the housing becomes long, and there is a high possibility that trouble will occur during the insertion work.

Further, the cross-sectional area of the pressure chamber orthogonal to the insertion axis, that is, the insertion cross-sectional area of the recess of the sensor housing into which the connector housing is inserted becomes small, which makes it difficult to insert the connector housing. Further, when the connector housing is inserted into the sensor housing, the element surface of the pressure sensitive element and the inner wall surface of the sensor housing face each other with a slight gap. Therefore, there is a high possibility that the pressure-sensitive element will be damaged during the insertion work.

Therefore, the pressure sensor has a cover so as to cover the pressure sensitive element. Therefore, even if the insertion cross-sectional area of the sensor housing is small and the distance to insert the connector housing is long as described above, the pressure-sensitive element or the like is not damaged during the insertion work.

On the other hand, if the above-mentioned angle is less than 60 degrees or more than 100 degrees, the effect of reducing the projected area in the axial direction of the pressure sensitive element is not sufficient, so the pressure sensor should be miniaturized sufficiently. May not be possible. for that reason,
More preferably, the above angle is 70 to 90 degrees. The most preferable value of the above angle is 9
It is 0 degrees. In this case, the projected area in the axial direction can be minimized. Then, the pressure sensor can be further miniaturized.

Further, it is preferable that the sensor housing has a seal diaphragm, and a pressure transmitting medium is enclosed in the pressure chamber sealed by the seal diaphragm (claim 3). In this case, the cover occupies a part of the space of the pressure chamber. Therefore, the filling amount of the pressure transmission medium filled in the pressure chamber can be reduced. Therefore, it is possible to suppress the minute volume change that may occur when the pressure transmission medium receives pressure or its temperature fluctuates, and improve performance such as pressure measurement accuracy and responsiveness. .

Further, it is preferable that the cover is configured to form a medium passage for guiding the pressure transmission medium on the element surface of the pressure sensitive element (claim 4). In this case, free circulation of the pressure transmission medium is ensured between the outside of the cover and the element surface side. Therefore, the cover can effectively protect the pressure-sensitive element, the bonding wire connected to the pressure-sensitive element, and the like while maintaining high pressure measurement performance by the pressure sensor.

Further, it is preferable that the connector housing and the cover have engaging portions that engage with each other (claim 5). In this case, when the cover is attached to the connector housing, it can be attached accurately by engaging the engaging portion. Therefore, there is no possibility that the cover will be displaced from the mounting position of this example and the element surface of the pressure-sensitive element will be damaged or the bonding wire connected to the pressure-sensitive element will be cut. Also, if the cover can be attached without using an adhesive or the like, the adverse effects due to the protrusion of the adhesive, such as the adhesive adhering to the pressure sensitive element,
Trouble such as pressing the bonding wire can be prevented.

When the connector housing and the cover are combined, the cross section orthogonal to the insertion axis has a substantially circular shape, and the substantially circular shape,
It is preferable that the cross section of the pressure chamber orthogonal to the insertion axis has substantially the same diameter as the substantially circular shape (claim 6). In this case, when the connector housing is inserted, it can be smoothly inserted into the sensor housing or the sealing material such as the O-ring. Therefore, there is no risk of damaging the inserted surface of the sensor housing or the O-ring. Further, the cover has a cross-sectional shape, which is orthogonal to the insertion axis when combined with the connector housing, substantially the same as the cross-sectional shape of the pressure chamber, thereby efficiently occupying a part of the space in the pressure chamber. can do.

[0018]

EXAMPLES Example 1 A pressure sensor 1 according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 1, the pressure sensor 1 of the present invention includes a connector housing 30 having a pressure receiving surface 32 on which the pressure sensitive element 20 is arranged.
And a sensor housing 40 and the sensor housing 40
On the other hand, the pressure chamber 42 is formed between the sensor housing 40 and the connector housing 30 by fitting the connector housing 30 along the fixed insertion shaft 33. Here, the pressure sensitive element 20 is housed in the pressure chamber 42. A cover 60 is attached to the pressure chamber 42 so as to cover the pressure sensitive element 20. The contents will be described below.

As shown in FIG. 1, the pressure sensor 1 of this embodiment is a sensor assembled by inserting a connector housing 30 having a terminal pin 10 and a pressure sensitive element 20 into a sensor housing 40 having a seal diaphragm 43. . That is, the pressure sensor 1 of this example has the pressure chamber 42 that is isolated from the fluid whose pressure is to be measured. In the pressure sensor 1, the pressure sensitive element 20 detects the fluid pressure acting on the seal diaphragm 43 via the pressure transmission medium sealed in the pressure chamber 42. The pressure-sensitive element 20 is one in which a silicon layer is processed to form a strain gauge, and a silicon substrate is precisely etched to form a sensor diaphragm.

The connector housing 30 is integrally molded of PPS resin and has an insertion portion 35 and a brim-shaped flange portion 31 having a diameter larger than that of the insertion portion 35. Further, the insertion portion 35 is connected to the brim portion 31, a base portion 351 is connected to the base portion 351, and a seal insertion portion 352 that forms a sealing surface with the sensor housing 40, and the seal insertion portion 352. And a disposing portion 353 having a substantially semicircular cross section, which is provided with a pressure receiving surface 32 that is substantially parallel to the insertion shaft 33. In addition, a tip end surface 354 facing the seal diaphragm 43 is formed at the tip of the disposing portion 353.

As shown in FIG. 2, the pressure receiving surface 32 of the disposing portion 353 is provided with a recess 36 for disposing the terminal pin 10 and the pressure sensitive element 20. Then, in the concave portion 36, a normal line 3 extending outward from the element surface 21 of the pressure sensitive element 20.
The pressure sensitive element 20 is arranged so that the angle R formed by the direction 4 and the insertion direction of the insertion shaft 33 is 90 degrees. Further, in the recess 36, the three terminal pins 10 that are insert-molded for power supply, ground, and signal output are exposed.

The terminal pins 10 are electrically connected to each other by a pressure sensitive element 20 and a bonding wire 22, as shown in FIG. 3 showing the AA cross section in FIG. The recess 36 is filled with a silicone-based sealing material to form the sealing layer 12. The sealing layer 12 sufficiently seals the space between the terminal pin 10 and the connector housing 30 to enhance the airtightness of the pressure chamber 42.

Further, a cover 60 is bonded to the pressure receiving surface 32 of the above-mentioned arrangement portion 353 with a silicone adhesive so as to cover the pressure sensitive element 20. The cover 60 is shown in FIG.
4 showing the B-view shape in FIG. 3 and C in FIG.
As shown in FIG. 5, which shows the visual shape, the outer shape is such that a substantially cylindrical shape is cut by a plane parallel to the axial direction.

As shown in FIG. 1, the cover 60 is formed so that the insertion portion 35 has a substantially cylindrical shape when attached to the pressure receiving surface 32. On the surface facing the pressure receiving surface 32, as shown in FIGS.
A recess 62 for avoiding interference with 0 or the bonding wire 22 is formed. Further, as shown in FIG. 5, a side surface of the cover 60, which is substantially the same as the tip end surface 354 when attached to the pressure receiving surface 32, serves as a passage for a pressure transmitting medium, and an oil passage 61. Has been drilled. The oil passage 61 is a passage for ensuring free circulation of the pressure transmission medium between the seal diaphragm 43 side and the element surface 21 side in the pressure chamber 42.

The sensor housing 40 is made of stainless steel, and as shown in FIG. 1, the first recess 45 into which the insertion portion 35 is inserted, and the flange portion 3 are provided on the connector housing 30 side of the seal diaphragm 43.
It has a second concave portion 47 into which 1 is inserted and a crimp portion 41 which engages with the brim portion 31 in a state where the brim portion 31 is inserted into the second concave portion 47. Further, the first recess 45 has a pressure chamber forming portion 452 into which the disposing portion 353 of the connector housing 30 is inserted to form the pressure chamber 42, and a connector housing 30 into which the seal inserting portion 352 and the base portion 351 are inserted. Has a receiving portion 451 which forms a sealing surface.

In addition, the sensor housing 40 is provided on the side of the measured environment 44 of the seal diaphragm 43, and the measured environment 4
4 has a pressure introduction hole 441 for introducing the fluid, gas, etc. to the seal diaphragm 43 side, and a threaded portion 442 for attaching the pressure sensor 1 to a pipe or the like forming the measurement environment 44. .

As shown in FIG. 1, the pressure sensor 1 manufactured by assembling the connector housing 30 and the sensor housing 40 configured as described above has the caulking portion 4 of the sensor housing 40 into which the connector housing 30 is inserted.
1 is deformed in the inner diameter direction and is engaged with the brim portion 31, so that the connector housing 30 and the sensor housing 40
It is assembled by fixing and.

In this pressure sensor 1, the diaphragm space formed by the front end surface 354 of the connector housing 30 and the seal diaphragm 43 of the sensor housing 40 facing each other and the pressure receiving surface 32 of the connector housing 30 are the pressure chambers of the sensor housing 40. It has a pressure chamber 42 formed of an element space facing the inner peripheral surface of the forming portion 452.

Here, most of the element space of the pressure chamber 42 is configured to be occupied by the cover 60. The space not occupied by the cover 60 is filled with silicone oil as the pressure transmitting medium. The pressure chamber 42 is sealed by an O ring 50 and a backup ring 51 arranged between the seal insertion portion 352 and the receiving portion 451. The O-ring 50 is held by a backup ring 51 that is pressed in the insertion direction by the base 351 of the connector housing 30 and is configured to withstand high pressure.

The pressure sensor 1 includes a sensor housing 4
It is configured so that it can be attached to a piping pipe or the like that forms the measurement environment 44 by the screw portion 442 provided at 0. The pressure introduced from the measured environment 44 to the seal diaphragm 43 side via the pressure introduction hole 441 is transmitted to the sensor diaphragm of the pressure sensitive element 20 via the silicone oil filled in the pressure chamber 42. Configured.

As described above, in the pressure sensor 1 of this example, the direction of the normal line 34 extending outward from the element surface 21 and
The pressure sensitive element 20 is arranged so that the angle R with the insertion direction of the insertion shaft 33 is 90 degrees. Therefore, the element surface 21
20. A pressure-sensitive element 20 having a flat plate shape whose thickness is thin in the normal direction of
In this case, the projected area in the axial direction of the insertion shaft 33 becomes small. Therefore, the pressure chamber 42 accommodating the pressure sensitive element 20 is
Can reduce the cross-sectional area orthogonal to the insertion axis 33. Therefore, the entire pressure sensor 1 including the pressure chamber 42 can be downsized.

Further, in the pressure sensor 1 of this embodiment, since the pressure sensitive element 20 is covered with the cover 60, the pressure sensitive element 20 and the bonding wire 22 connected to the pressure sensitive element 20 are produced in the manufacturing process thereof. Trouble can be prevented in advance. In addition, the cross-sectional shape of the above-mentioned disposing portion 353 with the cover 60 attached is orthogonal to the insertion shaft 33.
It has substantially the same shape as the cross-sectional shape of the seal insertion portion 352. Therefore, the connector housing 30 can be smoothly inserted into the O-ring 50 and the backup ring 51, which are sealing members. Therefore, when assembling the connector housing 30 and the sensor housing 40, it is possible to avoid troubles such as breakage of the O-ring and to perform the work with good productivity.

Here, in the pressure chamber 42 of the pressure sensor 1 in which the pressure sensitive element 20 is arranged without directly facing the seal diaphragm 43 as described above, the element surface 21 of the pressure sensitive element 20 and the seal diaphragm 43 face each other. The volume of the pressure chamber 42 tends to be larger than that of the type pressure sensor. That is, in the pressure chamber 42 of the pressure sensor 1 of the present example, the pressure receiving surface 32 and the inner periphery of the pressure chamber forming portion 452 are provided in the diaphragm space formed by the sealing diaphragm 43 and the tip surface 354 facing each other. The space is a combination of the element spaces formed facing each other.

This element space is a space which is generated due to the fact that the element surface 21 of the pressure-sensitive element 20 is arranged so as to be substantially orthogonal to the seal diaphragm 43, and it is difficult to eliminate it due to the arrangement. The volume of this element space is a volume that does not contribute to pressure measurement in the pressure sensor 1 of this example, and only increases the filling amount of the pressure transmission medium.

In this example, the cover 60 attached to the pressure receiving surface 32 of the connector housing 30 can occupy most of the volume of the element space. Therefore, in the pressure sensor 1 of this example, the filling amount of the pressure transmission medium filled in the pressure chamber 42 is close to the volume of the diaphragm space. Therefore, the pressure sensor 1 can further suppress the minute volume change of the pressure transmission medium due to the pressure or the temperature, and can accurately perform the pressure measurement.

As described above, the pressure sensor 1 of this example is a compact and low-cost, high-performance sensor, and has high productivity. Further, in the pressure sensor 1 of this example, fluorine oil may be applied instead of the silicone oil sealed in the pressure chamber 42.

In this example, the cover 60 and the connector housing 30 are joined by the silicone adhesive, but other various adhesives can be applied. Further, the connector housing 30 and the cover 60 may not be adhered. This is because the cover 60 can fix its position when assembled to the sensor housing 40 together with the connector housing 30.

Further, in place of the pressure chamber 42 isolated from the outside in the pressure sensor 1 of this example, the seal diaphragm 43 may be eliminated and the pressure chamber 42 opened to the outside may be used. In this case, the fluid whose pressure is to be measured directly acts on the sensor diaphragm of the pressure sensitive element 20.

(Embodiment 2) This embodiment is an example in which the method of attaching the connector housing 30 and the cover 60 of Embodiment 1 is replaced with a fitting type attachment method. In this example, as shown in FIGS. 6 and 7, the cover 60 is provided with convex engaging portions 63 and 64. Also,
As shown in FIG. 8, the connector housing 30 is provided with corresponding engaging portions 33 and 34 having concave shapes.

Then, the engaging portions 63, 64 of the cover 60
Are the engaging portions 33, 3 of the connector housing 30, respectively.
By fitting it into the cover 4, the cover 60
Can be accurately attached to the connector housing 30.

As described above, in the pressure sensor 1 of this embodiment, no adhesive is used when the cover 60 is attached to the connector housing 30. Therefore, at the time of joining the cover 60 and the connector housing 30, the excess adhesive does not overflow and flow toward the pressure sensitive element 20. Therefore, for example, it is possible to prevent troubles such as the adhesive pressing the bonding wire 22 connected to the pressure sensitive element 20 and breaking the wire.

The rest of the configuration and effects are the same as in the first embodiment.

[Brief description of drawings]

FIG. 1 is a sectional view showing a pressure sensor according to a first embodiment.

FIG. 2 is a front view showing the pressure receiving surface of the connector housing in the first embodiment.

FIG. 3 is a sectional view taken along the line AA in FIG. 2 in the first embodiment.

FIG. 4 is a top view of the cover according to the first embodiment.

FIG. 5 is a side view of the cover according to the first embodiment.

FIG. 6 is a top view of the cover according to the second embodiment.

FIG. 7 is a side view of the cover according to the second embodiment.

FIG. 8 is a front view showing a pressure receiving surface of a connector housing in the second embodiment.

FIG. 9 is a cross-sectional view showing a pressure sensor according to a conventional technique.

[Explanation of symbols]

1. ． ． Pressure sensor, 10. ． ． Terminal pin, 20. ． ． Pressure sensitive element, 21. ． ． Element surface, 22. ． ． Bonding wire, 30. ． ． Connector housing, 32. ． ． Pressure receiving surface, 33. ． ． Insertion axis, 34. ． ． Element surface normal, 35. ． ． Insert, 351. ． ． base, 352. ． ． Seal insertion part, 353. ． ． Placement section, 40. ． ． Sensor housing, 42. ． ． Pressure chamber, 43. ． ． Seal diaphragm, 50. ． ． O-ring, 60. ． ． cover, 61. ． ． Oil passage,

Claims (6)

[Claims] 1. A connector housing having a pressure receiving surface on which a pressure sensitive element is arranged, a sensor housing, and the sensor housing and the connector by fitting the connector housing into the sensor housing along a fixed insertion axis. A pressure sensor having a pressure chamber formed between the pressure chamber and a housing, wherein the pressure chamber houses the pressure sensitive element, and the pressure chamber is covered so as to cover the pressure sensitive element. A pressure sensor characterized by being attached. 2. The pressure-sensitive element according to claim 1, wherein an angle formed by a direction of a normal line outward from an element surface of the pressure-sensitive element and an insertion direction of the insertion shaft is 60 degrees to 100 degrees. A pressure sensor characterized in that the pressure sensor is attached so as to be within the range of. 3. The sensor housing according to claim 1, wherein the sensor housing has a seal diaphragm, and a pressure transmission medium is enclosed in the pressure chamber sealed by the seal diaphragm. Pressure sensor. 4. The method according to claim 1, wherein
The pressure sensor, wherein the cover is configured to form a medium passage for guiding the pressure transmission medium on the element surface of the pressure sensitive element. 5. The method according to any one of claims 1 to 4,
The pressure sensor, wherein the connector housing and the cover have engaging portions that engage with each other. 6. The method according to any one of claims 1 to 5,
When the connector housing and the cover are combined, the cross section orthogonal to the insertion axis is substantially circular, and the cross section of the pressure chamber perpendicular to the insertion axis is substantially circular. A pressure sensor having the same diameter as a circular shape.