JP2002098608A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the resistivity of a metal diaphragm fixing part against the stress added by the deformation of the metal diaphragm in an oil seal type pressure sensor. SOLUTION: In a recess part 11 of a connector case 10, a sensor chip 20 is arranged and oil 15 is charged. In housing assembled for the connector case 10, a metal diaphragm 34 parting the recess part 11 and a pressure introduction hole 32 of the housing 30 and sealing the oil 15 is fixed at the periphery. The metal diaphragm 34 is pressed and fixed to the housing 30 by an annular pressing member 35 arranged at the periphery. The pressing member 35 constitutes the outer portion as a contact part 35a contacting the metal diaphragm 34 and constitutes the inner portion, which is in taper shape and thinner than the outer portion, as a non-contact part 35b not contacting the metal diaphragm 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of assembling a first case having a detection element sealed with oil and a second case having a metal diaphragm, and applying a stress generated in the metal diaphragm through the oil. The present invention relates to a pressure sensor that transmits a signal to a detection element, and more particularly to a metal diaphragm for sealing oil and a holding member that supports an O-ring.

[0002]

2. Description of the Related Art A pressure sensor of this type has been proposed in Japanese Patent Application Laid-Open No. 7-243926. This has a first concave portion formed on one surface.
And a pressure detecting element disposed in the concave portion for detecting pressure, oil filled in the concave portion so as to cover the detecting element, and a pressure introducing hole capable of introducing pressure from the outside. And a second case assembled to the first case so as to cover the concave portion.

[0003] The second case is provided with a metal diaphragm which partitions the recess and the pressure introducing hole so as to seal the oil. The metal diaphragm is fixed to the second case by its peripheral portion being sandwiched between the annular pressing member and the second case.

Here, the pressing member and the metal diaphragm are welded to each other at the periphery of the metal diaphragm by welding.
Is integrally joined to the case. The joint by this welding is configured as a metal diaphragm fixing part for fixing the metal diaphragm by the second case and the pressing member.

[0005] An O-ring is provided on the surface of the pressing member opposite to the surface on which the metal diaphragm is pressed. That is, an O-ring is interposed and supported between the first case and the pressing member.
A ring seals between the first case and the holding member.

In a pressure sensor having such a configuration (hereinafter, referred to as an oil-sealed pressure sensor), pressure is introduced from a pressure introduction hole in the second case, and a stress ( (Strain stress) occurs. This stress is transmitted to the detecting element via the oil, and a signal having a level corresponding to the applied stress is generated in the detecting element, and the pressure is detected based on the signal.

[0007]

However, when the present inventors examined the above-mentioned conventional oil-sealed pressure sensor, it was found that the following problems occurred. FIG. 5 is a schematic sectional view of an oil sealing portion in the conventional pressure sensor.

[0008] As shown in FIG.
In the periphery thereof, the second case 30 and the holding member J
1 and joined by welding using laser welding or the like. In FIG. 5, the welded portion 36 is the second case 30
And a pressing member J1 to form a metal diaphragm fixing portion for fixing the metal diaphragm 34.

The introduced diaphragm deforms the metal diaphragm 34 toward the oil side (in the direction of arrow Y1 in FIG. 5). Due to the deformation of the metal diaphragm 34, a stress F is applied to the inner peripheral end of the holding member J1, that is, the constraint point P1 with respect to the metal diaphragm 34, as shown by a white arrow in the drawing. Due to this stress F, a stress is applied to the metal diaphragm fixing portion (welded portion) 36 so as to separate the metal diaphragm 34 and the pressing member J1 from the second case 30.

Heretofore, conventionally, this type of oil-sealed pressure sensor has been used mainly in the range of 0 to 10 MPa in the detection pressure such as the air-conditioner refrigerant pressure and power steering oil pressure of an automobile. However, when this type of pressure sensor is considered to be used for applications such as brake oil pressure and fuel pressure, the detected pressure is in the range of, for example, 0 to 20 MPa, and is used even for detecting higher pressure.

[0011] When applied to a higher pressure as described above, the deformation of the metal diaphragm becomes larger,
The stress applied to the metal diaphragm fixing part also increases,
There is a concern that the fixing portion may be broken.

In view of the above problems, an object of the present invention is to improve the resistance of a metal diaphragm fixing portion to a stress applied with the deformation of a metal diaphragm in an oil-sealed pressure sensor.

[0013]

In order to achieve the above object, the present invention has conducted a more detailed study on the stress applied to the metal diaphragm fixing portion due to the deformation of the metal diaphragm. As described above with reference to FIG. 5, due to the deformation of the metal diaphragm 34, a stress F is applied at the inner peripheral end of the annular holding member J1 so as to separate the holding member J1 from the second case 30.

Accordingly, the restraining point P1 of the pressing member J1 with respect to the metal diaphragm 34 is located as far as possible on the outer peripheral side of the metal diaphragm 34, that is, the restraining point (the point where the stress F from the metal diaphragm 34 is applied) P1. By reducing the distance L1 between the metal diaphragm 34 and the metal diaphragm fixing portion 36, the stress applied to the fixing portion 36 due to the deformation of the metal diaphragm 34 was considered to be reduced.

In this case, simply, it is conceivable that the inner diameter is increased without changing the outer diameter of the pressing member J1, and the radial width W1 of the pressing member J1 is shortened. However, on the other hand, as shown in FIG. 5, the pressing member J1 has a role of supporting the O-ring 42 on the surface opposite to the surface on which the metal diaphragm 34 is pressed, so that the diameter of the pressing member J1 is simply determined. If the width W1 in the direction is shortened, the O-ring 42 protrudes from the pressing member J1 and cannot be sufficiently supported.

[0016] From the above, in the holding member, O
It is necessary to shorten the distance between the restraining point for the metal diaphragm and the metal diaphragm fixing portion while sufficiently securing the ring support function. The present invention has been made based on the knowledge obtained as a result of such studies.

That is, according to the first aspect of the present invention, in the oil-sealed pressure sensor, the holding member (35)
Is formed as a contact portion (35a) whose outer peripheral portion is in contact with the metal diaphragm (34), and whose inner peripheral portion is thinner than the outer peripheral portion and does not contact the metal diaphragm. It is characterized in that it is configured as a contact portion (35b).

According to the present invention, the outer peripheral side of the pressing member is a contact portion that contacts the metal diaphragm, and the inner peripheral side of the pressing member is thinner than the outer peripheral side to be a non-contact portion that does not contact the metal diaphragm. As a result, it is possible to reduce the radial width of the surface of the pressing member that is in contact with the metal diaphragm and press it, and it is necessary to reduce the radial width of the surface that supports the O-ring. There is no.

Therefore, the O-ring can be sufficiently supported without impairing the O-ring support function of the holding member, and the restraining point (P2) of the holding member with respect to the metal diaphragm is set to be smaller than the conventional one on the outer peripheral side of the holding member. Can be located at the site.

That is, according to the present invention, the distance (L2) between the constraint point for the metal diaphragm and the metal diaphragm fixing portion (36) can be shortened as compared with the prior art, so that the metal diaphragm is deformed due to the deformation of the metal diaphragm. The stress applied to the diaphragm fixing portion can be reduced.
Therefore, according to the present invention, it is possible to improve the resistance of the metal diaphragm fixing portion to the stress applied due to the deformation of the metal diaphragm.

According to the second aspect of the present invention, the thickness of the non-contact portion (35b) of the pressing member (35) is continuously increased from the contact portion (35a) toward the inner peripheral end of the pressing member. It is characterized in that it is a tapered portion that is thin.

According to this, since the non-contact portion has a tapered shape that is continuously thinned from the contact portion side, the supporting strength of the O-ring in the non-contact portion thinner than the contact portion is stronger. And is preferred.

The invention described in claim 3 is the first invention.
2. The pressure sensor according to claim 1, wherein the concave portion (11) is formed on a surface on one end side of the first case (10), and the second case (30) has an opening (31) on one end side and the other end. The pressing member has a configuration in which the pressure introducing hole (32) is provided on the side and the one end of the first case is inserted into the opening and is assembled to the first case. The configuration is provided.

That is, the pressing member (35) in the pressure sensor according to the third aspect has a first shape when viewed in cross section.
And a first portion (351) interposed between the first case and the second case so as to extend in the insertion direction in the insertion portion of the second case, and a metal extending from the first portion by bending. The second portion (352) for sandwiching the diaphragm has an L-shape.
Is a contact portion (35a) and a non-contact portion (35b)
It is characterized by being a part constituting.

In a configuration in which the one end of the first case where the recess is formed is inserted into the opening of the second case and assembled, the holding member is usually attached to the opening of the second case. Pressed and fixed.

At this time, when the pressing member is an annular member having an L-shaped cross section including the first portion and the second portion as in the present invention, the first portion serves as a press-in allowance and the press-in portion is formed. Can increase the contact area. Therefore, it is possible to improve the fixability of the pressing member into the second case by press fitting, which is preferable.

Further, in the annular pressing member (35) having an L-shaped cross section,
It is preferable that the thickness of the second portion (352) is larger than that of the first portion (351).

According to this, since the second portion sandwiching the metal diaphragm can be made thick, the resistance of the metal diaphragm fixing portion to the stress applied due to the deformation of the metal diaphragm can be further improved. In addition, the first case interposed between the first case and the second case
Can be made thin, so that an increase in the sensor size in the radial direction of the holding member can be suppressed.

Here, in the invention described in each of the above-mentioned claims, the contact portion (35)
It is preferable that the thickness of a) is 0.4 mm or more. The stress applied to the metal diaphragm fixing part due to the deformation of the metal diaphragm becomes smaller as the thickness of the holding member becomes thicker in terms of material mechanics, but according to the study of the present inventors,
When the thickness of the contact portion is 0.4 mm or more, the effect of reducing the stress is sufficiently exhibited.

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

[0031]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing the overall configuration of an oil-sealed pressure sensor S1 according to the present embodiment. This pressure sensor S1 is mounted on an automobile and has a refrigerant pressure of an air conditioner and a fuel pressure of a fuel injection system of the automobile. The description will be made assuming that the pressure sensor is applied as a pressure sensor. FIG.
FIG. 2 is an enlarged view of an oil sealing portion in FIG.

10 is a connector case (the first case in the present invention).
Case). In this example, the connector case 10 is made of PPS (polyphenylene sulfide) or PBT.
It is made by molding a resin such as (polybutylene terephthalate) and has a substantially columnar shape. One end surface of the connector case 10 (the lower end surface in FIG. 1).
Is formed with a concave portion 11.

A sensor chip (detection element according to the present invention) 20 as an integrated sensor element for detecting pressure is provided in the recess 11. Sensor chip 20 of this example
Has a diaphragm (not shown) as a pressure receiving surface,
The semiconductor diaphragm type converts a received pressure into an electric signal and outputs the electric signal as a sensor signal.

The sensor chip 20 is integrated with a pedestal 21 made of glass or the like by anodic bonding or the like, and is mounted on the connector case 10 by bonding the pedestal 21 to the bottom surface of the recess 11.

The connector case 10 is provided with a plurality of metal rod-shaped terminals (connector pins) 12 for electrically connecting the sensor chip 20 to an external circuit or the like. In this example, the terminal 12 is made of a material obtained by plating (for example, Ni plating) on brass (brass), and the connector case 10 is formed by insert molding.
It is held in the connector case 10 by being formed integrally with the connector case 10.

One end (lower end in FIG. 1) of each terminal 12 protrudes from the bottom surface of the recess 11 around the mounting area of the sensor chip 20. The distal end surfaces of the protruding portions of the terminals 12 and the sensor chip 20 are connected and electrically connected via wires (bonding wires) 13 formed by wire bonding of gold, aluminum, or the like.

Further, as shown in FIG.
A sealant 14 for sealing a gap between the connector case 10 and the terminal 12 is provided around the protrusion. The sealant 14 is made of, for example, a silicon-based resin. With the sealant 14, even if there is a gap on the bottom surface of the concave portion 11 from which the terminal 12 projects, the gap is sealed.

The recess 11 is filled with oil 15 so as to cover the sensor chip (detection element) 20, the terminal 12, the wire 13, and the sealant 14.
The oil 15 is made of fluorine oil or the like, and mainly functions as a pressure transmission medium.

On the other hand, in FIG.
The other end side (the upper end side in FIG. 1) of the terminal 12 is connected to the other end side of the terminal 12 opposite to the protruding portion via an external wiring member (not shown) such as a wire harness. (ECU of the vehicle, etc.). Thus, the signal transmission between the sensor chip 20 and the outside is performed by the wire 13 and the terminal 1.
2 is performed.

Next, in FIG. 1, reference numeral 30 denotes a housing (second case in the present invention), which is made of a metal material such as stainless steel (SUS). This housing 3
0 has an opening 31 on one end side (upper end side in FIG. 1) and externally applies pressure (such as the above-described air-conditioner refrigerant and automobile fuel) on the other end side (lower end side in FIG. 1). pressure)
Has a pressure introduction hole 32 into which the pressure is introduced.

On the outer surface of the other end of the housing 30, a screw portion 33 for fixing the pressure sensor S1 to a suitable place in the automobile (refrigerant pipe of an air conditioner, fuel pipe of the automobile, etc.).
Are formed (see FIG. 1).

Then, as shown in FIG. 1, the connector case 10 is inserted into the opening 31 so that the connector case 10 is inserted into the connector case 10 so that the connector case 10 covers the concave portion 11 at one end (the lower end in FIG. 1). 10 are assembled. Here, an end 30 a on one end side of the housing 30 is caulked and fixed to the connector case 10.

Further, a metal diaphragm 34 made of a thin metal (for example, SUS) is provided on one end side of the housing 30.
And a holding member (ring weld) 35 made of an annular metal (for example, SUS) disposed around the metal diaphragm 34.

In this embodiment, the periphery of the metal diaphragm 34 is welded to the housing 30 together with the pressing member 35 by laser welding or the like, so that the metal diaphragm 3
4. A welding portion 36 in which the holding member 35 and the housing 30 are fused together is formed. Thereby, the welded portion 36 is configured as a fixing portion for fixing the metal diaphragm 34 by the housing 30 and the pressing member 35.

The pressing member 35 fixes the metal diaphragm 34 so as to be sandwiched between the metal diaphragm 34 and the housing 30. The metal diaphragm 34 seals the oil 15 with its peripheral portion fixed to the housing 30. Thus, the recess 11 and the pressure introducing hole 32 are partitioned.

In the case 10 and the housing 30 thus combined, the oil 1 is disposed between the recess 11 of the case 10 and the metal diaphragm 34 of the housing 30.
5 are enclosed. The chamber in which the oil 15 is sealed is configured as a pressure detection chamber 40.

An annular groove (O-ring groove) 41 is formed around the outer periphery of the pressure detection chamber 40.
An O-ring 42 for hermetically sealing the pressure detection chamber 40 is provided. The O-ring 42 is made of an elastic material such as silicon rubber, for example, and is supported between the connector case 10 and the pressing member 35.

The O-ring 42 is sandwiched and pressed between the connector case 10 and the holding member 35, whereby the O-ring 42 is moved together with the metal diaphragm 34 into the pressure detection chamber 40 (that is, the oil in the recess 11). 15).

In this embodiment, a backup ring 43 is provided in the groove 41 on the outer periphery of the O-ring 42. The backup ring 43 is made of, for example, a resin material such as tetrafluoroethylene resin, and prevents the O-ring 42 from entering the gap between the connector case 10 and the pressing member 35 and being damaged when the O-ring 42 spreads. It plays a role such as.

As described above, in the present embodiment, the pressing member 35 serves to press the metal diaphragm 34 on one side (the lower side in FIG. 2) and to support the O-ring 42 on the opposite side. have. The main feature of the present embodiment is that the holding member 35 has the following unique configuration.

That is, as shown in FIG.
Reference numeral 5 designates a contact portion 35a whose outer peripheral portion is in contact with the metal diaphragm 34, and whose inner peripheral portion has a smaller thickness than the outer peripheral portion (the contact portion 35a) and is in contact with the metal diaphragm 34. It is configured as a non-contact portion 35b that does not.

Such an annular pressing member 35 can be easily formed by subjecting a metal material to press working or the like. In particular, in this example, the non-contact portion 35
b is a tapered portion whose thickness is continuously reduced from the contact portion 35a toward the inner peripheral end of the pressing member 35.

In this embodiment, as shown in FIG. 2, the pressing member 35 has an L-shape when viewed in cross section (radial cross section). That is, a first portion 351 interposed between the connector case 10 and the housing 30 so as to extend in the insertion direction at the insertion portion of the connector case 10 and the housing 30, and a metal extending and bending from the first portion 351. The second portion 352 that sandwiches the diaphragm 34 forms an L-shape.

That is, in this example, the second portion 352 of the holding member 35 is formed by the contact portion 35a and the non-contact portion 3a.
5b. Then, in the holding member 35, the second portion 35 is larger than the first portion 351.
2 has a larger wall thickness. For example, the thickness of the first portion 351 can be 0.3 mm, and the thickness of the contact portion 35a in the second portion 352 can be 0.4 mm or more.

Next, a method of manufacturing the pressure sensor S1 will be described. The connector case 10 in which the terminal 12 is insert-molded is prepared. The sensor chip 20 is bonded and fixed to the recess 11 of the connector case 10 via the pedestal 21 by using an adhesive made of a silicon resin or the like.

Then, the sealant 14 is injected into the concave portion 11, and the sealant 14 is spread around each terminal 12 and then cured. Next, by performing wire bonding, the tip surface of the protruding portion of each terminal 12 and the sensor chip 20 are connected with the wire 13.

Then, the connector case 10 is arranged with the sensor chip 20 side up, and a fixed amount of oil 15 made of fluorine oil or the like is injected into the recess 11 from above the connector case 10 by a dispenser or the like.

Subsequently, a metal diaphragm 34 is provided at one end.
And a housing 30 in which the holding member 35 is welded all around. The opening 31 of the housing 30 is connected to the connector case 10 while keeping the housing 30 horizontal from above.
Lower so that it fits into This state is put in a vacuum chamber, and the air is evacuated to remove excess air in the pressure detection chamber 40.

After that, the connector case 10 and the pressing member 35 are pressed until they are sufficiently in contact with each other, and the metal diaphragm 3 is pressed.
4 and a pressure detection chamber 40 sealed by an O-ring 42. Next, the housing 30 and the connector case 10 are integrated by caulking the end 30a of the housing 30 to the connector case 10. Thus, the combination of the connector case 10 and the housing 30 is fixed.
The pressure sensor S1 shown in FIG. 1 is completed.

The basic pressure detecting operation of the pressure sensor S1 will be described. The pressure sensor S <b> 1 is attached to an appropriate position of the vehicle via, for example, the screw portion 33 of the housing 30. Then, an external pressure (the above-described pressure of the refrigerant of the air conditioner or the fuel of the vehicle) is introduced into the pressure sensor S <b> 1 through the pressure introduction hole 32 of the housing 30.

Then, the introduced pressure is applied to the metal diaphragm 34, and a stress (strain stress) is generated in the metal diaphragm 34. This stress is applied to the pressure detection chamber 40
The oil is transmitted to the sensor chip 20 via the oil 15 therein, and is applied to the pressure receiving surface of the sensor chip 20.

Then, an electric signal corresponding to the applied pressure is output from the sensor chip 20 as a sensor signal. This sensor signal is sent from the sensor chip 20 to the wire 1
3. The signal is transmitted to the external circuit through the terminal 12. The above is the basic pressure detecting operation in the pressure sensor S1.

In the oil-sealed pressure sensor S1 of the present embodiment, the outer peripheral portion of the annular pressing member 35 is formed as a contact portion 35a that contacts the metal diaphragm 34, and the inner peripheral portion is formed. It is characterized in that it is formed as a non-contact portion 35b which is thinner than the portion on the outer peripheral side and does not contact the metal diaphragm 34.

Pressing member 35 adopting such a configuration
The effect and the like will be specifically described with reference to the schematic diagram of FIG. 3 in comparison with the conventional pressing member J1 shown in FIG. First, in the conventional holding member J1, the O-ring 4
2 is the same width W1 in the radial direction of the surface that supports and the surface that contacts and presses the metal diaphragm 34.

On the other hand, the holding member 3 of the present embodiment
In FIG. 5, as shown in FIG. 3, with respect to the surface supporting the O-ring 42, the surface to be pressed against the metal diaphragm 34 while maintaining the radial width at the same width W1 as the conventional one is smaller than the conventional one. The radial width can be the short width W2.

For this reason, as shown in FIG. 3, the restraining point P2 of the holding member 35 with respect to the metal diaphragm 34 is changed from the contact portion 35a to the non-contact portion while securing a sufficient function of supporting the O-ring 42 in the holding member 35. By setting the boundary with 35b, it can be located at a position on the outer peripheral side of the pressing member 35 with respect to the conventional constraint point P1 (see FIG. 5).

That is, according to this embodiment, the constraint point P2 for the metal diaphragm 34 can be brought closer to the welded portion (metal diaphragm fixing portion) 36, and the constraint point P2
The distance L2 between the metal diaphragm 2 and the metal diaphragm fixing part is set to the distance L1 between the conventional constraint point and the metal diaphragm fixing part (see FIG. 5).
) Can be shortened.

Therefore, the stress F of the metal diaphragm 34 is applied to the constraint point P2 with the deformation of the metal diaphragm 34.
(Open arrows in FIG. 3), the influence of the stress F on the welded portion (metal diaphragm fixing portion) 36 can be reduced as compared with the conventional case. Therefore, according to the present embodiment, it is possible to improve the resistance of the metal diaphragm fixing portion to the stress applied due to the deformation of the metal diaphragm 34.

In this embodiment, the non-contact portion 35b of the pressing member 35 is a tapered portion whose thickness continuously decreases from the contact portion 35a toward the inner peripheral end of the pressing member 35. Here, the non-contact portion 35b does not have to be a tapered portion.
5b, the thickness of the non-contact portion 35b may be discontinuously reduced with respect to the contact portion 35a.

However, as in the present embodiment, the non-contact portion 35b has a tapered shape that is continuously thinned from the contact portion 35a side, so that the non-contact portion 35b has a smaller thickness than the contact portion 35a. The supporting strength of the O-ring 42 in the non-contact portion 35b having a small thickness can be further increased,
preferable.

The tapered portion also improves the displacement characteristics of the metal diaphragm 34 toward the oil side. That is, as compared with the conventional configuration shown in FIG. 5, the displacement point (constraint point) of the metal diaphragm 34 is
Can be moved closer to the outside, so that the amount of displacement can be increased.

The metal diaphragm 34 is oil 1
It is necessary to prevent the tapered portion (non-contact portion) from coming into contact with the metal diaphragm 34 when displaced to the fifth side. Therefore, the angle of the tapered portion, that is, the angle θ between the interface where the contact portion 35a contacts the metal diaphragm 34 and the tapered portion shown in FIG.
4 or more (for example, 16 °).

Further, as described above, the holding member 3 of this embodiment
5 has an L-shape including a first portion 351 and a second portion 352 when viewed in cross section (radial cross section), and the second portion 352 includes the contact portion 35a and the non-contact portion. It is a part constituting the contact part 35b (see FIG. 2).

As in the present embodiment, in the case where one end of the connector case 10 in which the recess 11 is formed is inserted into the opening 31 on one end of the housing 30 and assembled, the holding member 35 is connected to the opening of the housing 30. The method of fixing to the part 31 is usually performed by press fitting.

At this time, as in this example, the holding member 35
Is an annular member having an L-shaped cross section composed of the first portion 351 and the second portion 352, the first portion 351 serves as a press-in allowance and can increase the contact area of the press-fit portion. Therefore, the fixing property by press-fitting the pressing member 35 into the opening 31 of the housing 30 can be improved, which is preferable.

Further, an annular pressing member 3 having an L-shaped cross section
In 5, the thickness of the second portion 352 is preferably larger than that of the first portion 351 as in this example.
This is for the following reason.

First, since the second portion 352 sandwiching the metal diaphragm 34 can be made thicker, the resistance of the metal diaphragm fixing portion to the stress applied due to the deformation of the metal diaphragm 34 can be further improved. Further, since the first portion 351 interposed between the connector case 10 and the housing 30 can be made thin, it is possible to suppress an increase in the sensor size of the pressing member 35 in the radial direction.

Here, as described above, the pressing member 35
In this case, it is preferable that the thickness of the contact portion 35a be 0.4 mm or more. The stress applied to the welded portion (metal diaphragm fixed portion) 36 due to the deformation of the metal diaphragm 34 becomes smaller as the plate thickness (wall thickness) of the holding member 35 becomes thicker in terms of material mechanics. Specifically, the stress is inversely proportional to the square of the thickness of the pressing member 35.

From this, the present inventors calculated the relationship between the plate thickness of the contact portion 35a of the holding member 35 and the stress applied to the welded portion 36 when the load applied to the holding member 35 was within the working pressure range. Determined by FIG. 4 shows the results. FIG. 4 shows that when the thickness of the contact portion 35a is 0.4 mm or more, the stress applied to the welded portion 36 can be reliably suppressed to the yield stress (for example, 280 MPa) of the pressing member 35 or less.

As shown in FIGS. 2 and 3, in this embodiment, the boundary between the contact portion 35a and the non-contact portion 35b of the holding member 35 is a constraint point P2 for the metal diaphragm 34. However, also in the housing 30, at the boundary between the contact portion and the non-contact portion with the metal diaphragm 34, a constraint point P3 for the metal diaphragm 34 is formed.
Exists (see FIG. 2).

Here, it is preferable to shift the positions of the restraining point P2 on the holding member 35 side and the restraining point P3 on the housing 30 side so as not to overlap. In this example, as shown in FIG. 2, the restraining point P3 on the housing 30 side is
It is located on the outer peripheral side of the metal diaphragm 34 from the side constraint point P2.

At the time of pressure detection, the metal diaphragm 34 is displaced toward the oil 15 side. However, in a high-temperature environment, the oil 15 expands at the time of non-detection, and the metal diaphragm 34 moves to the housing 30 side (the pressure introduction hole 32 side). May be displaced.

In this case, if the above two constraint points P2,
If the positions of P3 overlap and coincide, the metal diaphragm 34 will be displaced in directions opposite to each other with the same position as a fulcrum. Then, the metal diaphragm 3
Since the bending stress is repeatedly applied to the same position of No. 4, it is not preferable from the viewpoint of the durability of the metal diaphragm 34.

At this point, by shifting the positions of the two constraint points P2 and P3 so that they do not overlap with each other, the bending stress due to the displacement in the opposite direction is not applied to the same position of the metal diaphragm 34. It is preferable from the viewpoint of durability. In the example shown in FIG.
The 0-side constraint point P3 is at the center of the width of the O-ring 42,
The O-ring 42 is located inside a diameter obtained by adding the inner diameter and the outer diameter of the O-ring 42 and dividing the sum by two.

(Other Embodiments) The pressing member 35
Need not be an annular member having an L-shaped cross section composed of the first portion 351 and the second portion 352 described above. When the cross-sectional shape is viewed, the first portion 351 is not present, and the second portion 352 is not provided. It may be an annular member consisting only of the above. Further, the metal diaphragm fixing portion may be formed by bonding or the like other than welding.

In short, the present invention is characterized in that an oil-sealed pressure sensor is characterized in that an annular pressing member supporting a metal diaphragm and an O-ring is provided with the above-mentioned contact portion and non-contact portion. Therefore, the other parts can be appropriately changed in design.

The pressure sensor according to the present invention has a detection pressure of, for example, 0 to 20 M in addition to a vehicle pressure sensor for detecting a refrigerant pressure of an air conditioner and a fuel pressure of a fuel injection system of the vehicle.
It is suitable for use in a pressure sensor used for detecting pressure in a high range such as Pa, but its use is not limited.

[Brief description of the drawings]

FIG. 1 is an overall schematic cross-sectional view of a pressure sensor according to an embodiment.

FIG. 2 is an enlarged view of an oil sealing portion in FIG.

FIG. 3 is a schematic diagram for explaining the operation and effect of the present invention.

FIG. 4 is a diagram illustrating a relationship between a plate thickness of a pressing member and a stress applied to a welded portion.

FIG. 5 is a schematic sectional view of an oil sealing portion in a conventional pressure sensor.

[Explanation of symbols]

10 ... connector case, 11 ... recess of connector case,
15: Oil, 20: Sensor chip, 30: Housing, 31: Opening of housing, 32: Pressure introduction hole, 3
4: Metal diaphragm, 35: Holding member, 35a ...
Contact portion of the pressing member, 35b ... non-contact portion of the pressing member,
351, a first portion of the pressing member, 352, a second portion of the pressing member, 42, an O-ring.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Seiichiro Otake 1-1-1, Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (Reference) 2F055 AA40 BB20 CC02 DD04 EE13 FF07 FF38 GG22 HH08 4M112 AA01 CA01 EA14 GA01

Claims (5)

[Claims] 1. A first case (10) having a concave portion (11) formed on one surface, and a pressure detecting element (20) disposed in the concave portion.
An oil (15) filled in the recess so as to cover the detection element, and a pressure introduction hole (32) through which pressure can be introduced from outside,
A second case (30) assembled to the first case so as to cover the concave portion, and the concave portion so as to seal the oil while a peripheral portion is fixed to the second case. A metal diaphragm (34) for partitioning the pressure introduction hole, and an annular pressing member (35) disposed around the metal diaphragm and fixed to sandwich the metal diaphragm between the second case and the second case. ), And an O-ring (42) interposed and supported between the first case and the holding member, wherein the stress generated in the metal diaphragm by the pressure introduced from the pressure introduction hole is In the pressure sensor configured to transmit the oil to the detection element via oil, the pressing member has a contact portion (3) in which a portion on an outer peripheral side thereof contacts the metal diaphragm. Is configured as a),
A non-contact portion (35) whose inner peripheral portion is thinner than the outer peripheral portion and does not contact the metal diaphragm.
b) A pressure sensor characterized by being configured as b). 2. The non-contact portion (35b) is a tapered portion whose thickness is continuously reduced from the contact portion (35a) toward the inner peripheral end of the pressing member (35). The pressure sensor according to claim 1, wherein: 3. The recess (11) is formed on a surface of one end of the first case (10), and the second case (30) is formed with an opening (31) on one end.
And having the pressure introduction hole (32) on the other end side, and being assembled to the first case with the one end side of the first case inserted into the opening. The pressing member, when viewed in its cross-sectional shape, is the first member.
And a first portion (351) interposed between the first case and the second case so as to extend in the insertion direction in the insertion portion of the second case, and bend from the first portion. An L-shaped portion comprising a second portion (352) extending and sandwiching the metal diaphragm, wherein the second portion of the holding member comprises the contact portion (35a) and the non-contact portion (35b). The pressure sensor according to claim 1, wherein the pressure sensor comprises: 4. The holding member (35) has a second portion (352) rather than the first portion (351).
4. The pressure sensor according to claim 3, wherein the thickness is larger. 5. The thickness of the contact portion (35a) is 0.4
The pressure sensor according to any one of claims 1 to 4, wherein the pressure sensor is not less than mm.