JP2001272297A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fitting structure of a stem to a housing suitable for smaller scale, related to a pressure sensor where a stem comprising a diaphragm is fixed to a housing into which a pressure is introduced. SOLUTION: A housing 10, comprising a pressure guiding path 13 for guiding a pressure, comprises within it two hollow cylindrical metal stems 20 provided with, on one end side of a shaft, a diaphragm 21 for detecting a pressure and a sensor ship 30 for outputting electric signal corresponding to the deformation of the diaphragm 21 as well as, on the other end side of the shaft, an opening part 22 to communicate with the pressure guiding path 13. A thread part 24 is formed on outer perimeter of each stem 20, and each stem 20 is screw-coupled to the housing 10 while pressurized toward the other end of the shaft, through the thread part 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor in which a stem having a diaphragm on which a pressure detecting portion is formed is screwed to a housing capable of introducing pressure.
It is suitable for use in detecting a high pressure of about 200 MPa.

[0002]

2. Description of the Related Art As a pressure sensor of this type, the present applicant has proposed a pressure sensor described in Japanese Patent Application No. 11-82180. FIG. 8 shows a schematic cross section of a pressure sensor prototyped by the present inventors based on this prior application. This is, for example, a fuel injection system of an automobile (for example, common rail).
) Can be applied to a high pressure detection sensor for detecting a high pressure (fuel pressure) in the fuel pipe.

In FIG. 8, J1 is a hollow cylindrical metal stem having a thin diaphragm J2 as a closing part at one end of a shaft and an opening J3 at the other end of the shaft. The stem J1 has a pressure detection chip (detection unit) J4 glass-bonded on the diaphragm J2, and the opening J3 communicates with a pressure introduction hole (pressure introduction passage) J6 of the housing J5.

[0004] The stem J1 is provided with a separate screw member J7.
Thus, the end face of the stem J1 on the side of the opening J3 is pressed and sealed by the opening edge of the pressure introducing hole J6 so that airtightness can be maintained even when high pressure is introduced. ing.

In this sensor, the diaphragm J2 is deformed by the pressure introduced from the pressure introducing hole J6,
The distortion is converted into an electric signal by the chip J4, and this signal is output to an external circuit (not shown) (e.g., an ECU of a car) through the wire J8, the circuit board J9, the pin J10, and the connector terminal J11 to detect the pressure. It is supposed to do.

[0006]

However, in the above prototype, a screw member J7 separate from the stem J1 is used.
Is used as a means for fixing the stem J1 to the housing while maintaining airtightness against a high pressure. Therefore, there is a problem that the size of the housing J5 accommodating the stem J1 and the sensor becomes large.

In view of the above problems, it is an object of the present invention to provide a pressure sensor in which a stem having a diaphragm is fixed to a housing capable of introducing pressure, and to provide a structure for fixing the stem to the housing suitable for downsizing the housing. .

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a housing (10) having a pressure introducing passage (13) capable of introducing pressure, a housing (10) housed in the housing, At one end of the shaft, a diaphragm (2) deformable by pressure introduced into the housing
(1) a hollow cylindrical stem (20) having an opening (22) communicating with the pressure introducing passage at the other end of the shaft; and an electric signal provided on the diaphragm and corresponding to the deformation of the diaphragm. A screw portion (24) for screwing the stem to the housing so as to press the stem toward the other end of the shaft on the outer peripheral side surface of the stem. ) Are integrally formed.

Thus, since the stem itself is integrally formed with the screw portion which can be screw-coupled to the housing, the stem can be fixed to the housing without disposing a separate screw member, and is suitable for downsizing the housing. A structure for fixing the stem to the housing can be provided. In addition, the opening at the other end of the stem shaft can be pressed against the pressure introducing passage side of the housing by the axial force of the screw connection to seal the housing, thereby making it suitable for high pressure detection.

In order to enable failure diagnosis of this type of pressure sensor due to electrical disconnection, breakage of a detection unit (for example, a chip) (peeling from a stem, etc.), etc.
Arrange a plurality of stems and chips on one pressure sensor,
It is conceivable to compare output signals from each chip by a circuit in the sensor or an external circuit. Then, by comparing the output signals of the respective chips, it is possible to easily detect an output abnormality occurring in a certain chip.

As described above, in the case where a plurality of stems and chips are arranged on one pressure sensor, the above-described structure in which the stem is fixed to the housing by the separate screw member,
The screw diameter of the screw member needs to be increased, and an increase in the size of the housing is inevitable. A second aspect of the present invention provides a configuration capable of arranging a plurality of detection units (chips or the like) while achieving the above object.

That is, in the pressure sensor of the second aspect,
A plurality of stems (20) are provided, and a thread portion (24) for screwing with the housing (10) is formed on the outer peripheral side surface of each stem so as to press the stem toward the other end of the shaft. It is characterized by:

According to this, since each stem has a screw portion, a separate screw member is unnecessary, and the outer diameter of the stem is limited to a size that can be mounted on the detecting portion (chip). Therefore, according to the present invention, it is possible to provide a structure for fixing the stem to the housing, which is suitable for reducing the size of the housing and in which a plurality of detectors (chips and the like) can be arranged.

According to a third aspect of the present invention, in the pressure sensor according to the second aspect, each of the stems (20) includes:
A communication path (16) for communicating the opening (22) with the pressure introduction path (13) is formed in the housing (10). If such a communication path is provided,
Appropriate pressure can be guided to the diaphragm of each stem.

According to a fourth aspect of the present invention, in the pressure sensor according to the second or third aspect, the housing (1)
A screw part (11) that can be screw-coupled to the measured object (K1) is formed on the outer peripheral surface on one end side of 0), and each stem (20) is formed.
The rotation axis of the screw portion (24) is located on one circumference centered on the rotation axis of the screw portion of the housing, and the pressure introduction passage (13) is formed in an opening formed at one end of the housing. It is characterized in that the circle extending from (12) into the housing is formed as a hole having a sectional shape.

According to this, since the screw portion of the housing and the axis of the pressure introduction passage coincide with each other, the pressure introduction passage can be easily formed in the housing, and the cross-sectional area of the pressure introduction passage is made unnecessarily large. In addition, since communication between the pressure introducing passage and each stem can be ensured, it is possible to provide a preferable configuration for downsizing the housing.

The invention described in claim 5 is the first invention.
4. The pressure sensor according to claim 3, wherein a screw portion (11) that can be screw-coupled to the measured object (K1) is formed on an outer peripheral surface on one end side of the housing (10), and the pressure introducing passage (13) is formed in the housing. A hole extending from the opening (12) formed at one end of the housing into the housing, and an end point of the hole in the housing corresponding to a portion of the screw portion to be screw-coupled to the measured object. It is characterized by being located in.

According to this, the portion of the housing in which the pressure introducing passage is formed is supported by being surrounded by the measured object while being screwed to the measured object. Therefore, the concentration of the stress generated in the housing due to the high pressure applied in the pressure introducing passage can be suppressed.

According to the sixth aspect of the present invention, there is provided the second aspect.
Alternatively, in the pressure sensor according to the third aspect, the pressure introduction passage (13) is formed of a plurality of holes provided corresponding to each of the communication passages (16).

By providing a pressure introduction passage for each of the communication passages provided for each of the plurality of stems, the volume occupied by the pressure introduction passage in the housing can be minimized. Therefore, the rigidity of the housing at the portion where the pressure introduction passage is formed can be suitably secured, which is preferable for increasing the pressure resistance of the sensor.

Furthermore, by arranging each hole in the pressure introducing passage (13) closer to the center axis of the housing (10) than the corresponding communication passage (16), as in the invention according to claim 7, The area of the outer peripheral portion of each hole in the housing can be increased.

The outer peripheral portion of each hole in the housing is a portion serving as a seal portion with the measured object (K1) in the sensor. By increasing the area of the outer peripheral portion, the sealing performance with the measured object is improved. Thus, it is possible to realize a pressure sensor suitable for higher withstand pressure.

Further, in the pressure sensor according to the fourth aspect, the pressure introducing passage (13) has a cross section formed by a circle extending into the housing from an opening (12) formed at one end of the housing (10). In the invention according to claim 8, the pressure introducing passage (13) is formed obliquely from the opening (12) toward the inside of the housing (10). It is characterized by.

According to this, the opening of the pressure introducing passage can be suitably reduced, and the outer edge of the opening, that is, the area of the seal portion between the sensor and the measured object (K1) can be increased. . That is, according to the present invention,
It is possible to improve the sealing property with the object to be measured and to realize a pressure sensor suitable for higher withstand pressure.

According to the ninth aspect of the present invention, there is provided the first aspect of the present invention.
The pressure sensor according to any one of claims 8 to 12, wherein a screw is screwed to a screw portion on the outer peripheral side surface of the stem (20) between the diaphragm (21) and the screw portion (24) at the time of screw connection. A surface portion (25) for applying a force is formed. According to this, the stem and the housing can be easily screwed together, which is preferable.

Here, as in the tenth aspect of the present invention,
The surface portion (25) is thicker than a portion of the stem (20) between the surface portion and the diaphragm (21), and the outer peripheral surface of the surface portion is positioned so as to protrude outward from the outer periphery of the diaphragm. Is preferred. .

The screw is tightened by applying a jig to the outer peripheral surface of the surface and rotating the stem. At this time, by projecting the outer peripheral surface of the surface portion outward from the outer periphery of the diaphragm, it is possible to suppress the screw fastening jig from hitting the diaphragm and the detecting portion provided on the diaphragm.

Further, since the surface portion is thicker than the portion of the stem between the surface portion and the diaphragm, it is difficult for the screw tightening force to be transmitted to the diaphragm and the detection portion, which are the sensing portion of the pressure sensor. Thus, according to the tenth aspect of the present invention, damage to the sensing unit can be reduced, which is preferable.

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

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an overall sectional configuration of a pressure sensor 100 according to a first embodiment of the present invention. Pressure sensor 1
Reference numeral 00 denotes a sensor which is attached to a fuel pipe of a fuel injection system (for example, a common rail) of an automobile and detects the pressure (for example, a high pressure of about 200 MPa) of a liquid or gas-liquid mixture as a pressure medium in the fuel pipe. is there.

FIGS. 2A and 2B are configuration diagrams showing a housing part, that is, a main part, excluding a connector part in the present embodiment. FIG. 2A is a view taken in the direction of arrow A in FIG. 1, and FIG. Of B
It is a schematic sectional drawing which followed the -B cross section. FIG. 1 is the same as FIG.
It is an outline sectional view along the CC section in (a).

Reference numeral 10 denotes a metal housing processed by cutting, cold forging, or the like, and a screw portion 11 that can be screw-coupled to the measured object K1 is formed on the outer peripheral surface on one end side. Then, as shown in FIG. 2 (b), the housing 10 is screwed and attached to a screw hole K2 formed in a fuel pipe K1 as an object to be measured by a screw portion 11. Here, the housing 10 and the pipe K1 are sealed by the housing sealing surface 14 located at one end of the housing 10.

At one end of the housing 10, there is formed a hole extending into the housing 10 from an opening 12 formed at one end of the housing 10, and this hole is used to form a pressure at which pressure is introduced from the fuel pipe K1. It is configured as an introduction passage 13. In this example, the cross-sectional shape of the pressure introduction passage 13 forms one circle centered on the rotation axis of the screw portion 11 of the housing 10.

As shown in FIG. 2B, in this example,
End point 13 of pressure introducing passage 13 in housing 10
a is positioned below the height at which the threaded portion 11 of the housing 10 is fixed to the fuel pipe K1 so that the entire pressure introducing passage 13 corresponds to a portion of the threaded portion 11 of the housing 10 which is screw-coupled to the pipe K1. It is configured to be located at the site where it is located.

Reference numeral 20 denotes a metal stem processed into a hollow cylindrical shape, two of which are attached to the other end of the housing 10 and housed in the housing 10. Each stem 20 has a thin-walled diaphragm 21 deformable by pressure introduced into the housing 10 at one end of the shaft, and an opening 22 communicating with the pressure introducing passage 13 at the other end of the shaft.
Having. Here, FIG. 3 is an enlarged perspective view including the cross section of one end side of the shaft of each stem 20.

On the diaphragm 21 of each stem 20,
A pressure sensing sensor chip 30 made of single crystal Si (silicon) is bonded and fixed by the low melting point glass 23. This sensor chip 30 is a bridge circuit (see FIG. 4).
When the diaphragm 21 is deformed by the pressure introduced into the inside of the stem 20 from the opening 22 of the stem 20, a detecting unit (strain gauge) that converts a resistance value change according to the deformation into an electric signal and outputs the electric signal. It functions as. The diaphragm 21 and the sensor chip 30 affect the basic performance of the sensor 100.

On the outer peripheral side surface of each stem 20, a male screw portion (screw portion of the stem in the present invention) for screwing with the housing 10 so as to press the stem 20 toward the other end of the shaft. ) 24 is formed integrally by cutting or the like, and a nut portion 25 having a shape capable of applying a screw tightening force, such as a hexagonal shape, is formed closer to one end of the shaft than the male screw portion 24. The male screw portion 24 is formed with a female screw portion 1 formed in a stem fixing screw hole in the housing 10.
5, the two screw portions 15,
The stem 20 is fixed to the housing 10 by the screw connection of 24.

Further, the nut portion 25 is connected to the diaphragm 21.
It is formed on the side surface of the outer periphery of the stem 20 between the screw portion 24 and the screw portion 24, and is configured as a surface portion for applying a screw tightening force to the male screw portion 24 at the time of the above screw connection.
That is, the screw connection is performed by bringing a jig for screw tightening such as a wrench or a spanner into contact with the outer peripheral surface of the nut portion 25 and rotating the stem 20 around the rotation axis of the male screw portion 24.

The nut portion (surface portion) 25 is shown in FIG.
, And will be described in more detail. FIG. 4 is a detailed configuration diagram of the stem 20 alone, (a) is an axial cross-sectional view, and (b)
(A) is a top view. As shown in FIG. 4, in this example, the nut portion 25 has a hexagonal shape, is thicker than a portion of the stem 20 between the nut portion 25 and the diaphragm 21, and has an outer peripheral surface of the nut portion 25. Are protruded outward from the outer periphery of the diaphragm 21.

The housing 10 is provided with a communication passage 16 for communicating the opening 22 and the pressure introduction passage 13 for each stem 20. Here, the stem 2 is connected by the screw connection of the two screw portions 15 and 24 described above.
0, a pressing force is applied in the direction of the other end of the shaft (on the side of the opening 22).
The end face on the side of the opening 22 and the opening edge of the communication passage 16 of the housing 10 are sealed. Thus, the pressure in the fuel pipe K1 is introduced from the pressure introduction passage 13 into the stem 20 via the communication passage 16.

Further, in this embodiment, as described above, the cross-sectional shape of the pressure introducing passage 13 has a shape corresponding to one circle centered on the rotation axis of the screw portion 11 of the housing 10. The rotation axis of the male screw portion 24 of each stem 20 is located on this circumference. In other words, the concentric circle of the screw portion 11 of the housing 10 forms the cross-sectional shape of the pressure introduction passage 13, and the rotation axis of the male screw portion 24 of each stem 20 is located on the concentric circumference.

Here, the metal material constituting the stem 20 has a high strength because it is subjected to an ultra-high pressure.
Since the sensor chip 30 made of Si is joined by the glass 23, it is required to have a low coefficient of thermal expansion. Specifically, Fe, Ni, Co or Fe, Ni is mainly used,
Ti, Nb, Al or Ti, N as precipitation strengthening material
The material to which b is added can be selected and formed by pressing, cutting, cold forging, or the like.

As described above, the housing 10 is fixed to the fuel pipe (fuel pipe) K1 (ultra high pressure seal and mechanical holding), and the stem 20 is fixed (ultra high pressure seal and mechanical holding). And the function of fixing (sealing and mechanically holding) the connector case 70 described later.

Therefore, the required quality of the housing 10 is to maintain the corrosion resistance from the pressure medium and the actual vehicle environment, and to maintain the axial force for generating a high sealing surface pressure in the sealing portion between the stem 20 and the end face on the opening 22 side. Screw strength. From these required qualities, the material of the housing 10 is a carbon steel (for example, S15C or the like) having both high corrosion resistance and high strength.
Plated, corrosion-resistant XM7, SUS
430, SUS304, SUS630 and the like can be adopted.

Reference numeral 40 denotes a ceramic substrate (circuit board)
The ceramic substrate 40 is adhered to a spacer 50 provided on the outer periphery of the stem 20 inside the housing 10. The spacer 50 allows the substrate 40
Are arranged at the same height as the diaphragm 21 of the stem 20. Then, as shown in FIG. 2A, terminals of each sensor chip 30 and substrate 40 (four in the illustrated example, corresponding to terminals T1 to T4 in FIG. 5 described later) 42
Is a bonding wire 4 made of aluminum (Al) or the like.
4 and are electrically connected.

On the wire bonding surface of the ceramic substrate 40 with the sensor chip 30, pins (three in the illustrated example) 46 for electrically connecting to the connector terminal 60 are joined by silver solder or the like. An amplifier (Am) for amplifying the output of each sensor chip 30 is provided on the surface of the ceramic substrate 40 opposite to the wire bonding surface.
p) The IC chip 48 and the characteristic adjustment IC chip 48 are bonded. These IC chips 48 are electrically connected to the pins 46 by through holes and the like formed in the substrate 40.

The connector terminal 60 is connected to the terminal 6
Reference numeral 2 denotes an assembly (ASSY) formed by insert molding the resin 64. The terminal 62 and the ceramic substrate 40 are joined to the pins 46 by laser welding. The connector terminal 60 is connected to the housing 10.
By crimping the other end 17 of the connector case 70 to the connector case 70, the terminal case 62 is fixedly held by the connector case 70 and the spacer 50, and the terminal 62 can be electrically connected to an ECU or the like of the automobile via a wiring member.

The connector case 70 forms the outer shape of the connector terminal 60, and has the other end 17 of the housing 10.
Is caulked to the connector case 70 to form a package integrally with the housing 10, and protects the sensor chip 30, various ICs, and electrical connection portions inside the package from moisture and mechanical external force. The caulked portion between the connector case 70 and the case 10 is made of a sealing material 18.
Sealed by As a material of the connector case 70, for example, PPS (polyphenylene sulfide) or the like having high hydrolyzability can be adopted.

A method for assembling the pressure sensor 100 having such a configuration will be described. First, each stem 20 to which the sensor chip 30 is joined by the glass 23 is screw-coupled to the housing 10 via a nut 25, and the stem 20 is fixed to the housing 10. Next, the spacer 50 is put into the housing 10 and the ceramic substrate 40 is bonded to the spacer 50.

Next, each sensor chip 30 and the terminal 42 of the ceramic substrate 40 are connected by wire bonding, and are electrically connected. Next, the connector terminal 60
And the pin 46 are joined by laser welding (YAG laser welding or the like). Then, connect the connector case 70 to the housing 1.
The connector case 70 and the housing 10 are fixed by assembling the connector case 70 and crimping the other end 17 of the housing 10 and disposing the sealing material 18. Thus, the pressure sensor 100 shown in FIG. 1 is completed.

The pressure sensor 100 includes the housing 1
By directly connecting and attaching the 0 screw portion 11 to a screw hole K2 formed in the fuel pipe (measured object) K1, the fuel pipe K1 is connected and fixed to the fuel pipe K1.

Then, when the fuel pressure (pressure medium) in the fuel pipe K1 is introduced from the pressure introduction passage 13 through each communication passage 16 to the inside (hollow portion) of the stem 20 from the opening 22 of each stem 20. Then, the diaphragm 21 is deformed by the pressure. This deformation is applied to sensor chip 30
To convert the signal into an electric signal and perform pressure detection. Then, fuel injection control is performed by the ECU or the like based on the detected pressure (fuel pressure).

In this embodiment, each output signal from the two sensor chips 30 is converted into a ceramic substrate 40 constituting a processing circuit of the sensor or an external circuit such as an ECU (ceramic substrate 40 in this example). Compare with. Thereby, if there is an abnormality in one output signal, this abnormality is
It can be easily detected by comparison with the other normal signal.
Thus, the failure diagnosis of the sensor is facilitated.

As described above, according to the present embodiment, the screw portion 24 for screwing with the housing 10 so as to press the stem 20 toward the other end of the shaft is integrally formed on the outer peripheral side surface of the two stems 20. Since it is formed, the stem 20 can be fixed to the housing 10 without disposing a separate screw member. Also, the opening 22 on the other end of the shaft is formed by the axial force of the screw connection.
Can be pressed against the pressure introduction passage 13 side of the housing 10 (opening edge of the communication passage 16) to seal the housing 10, thereby making it suitable for high pressure detection.

Therefore, according to this embodiment, a separate screw member is not required, and the outer diameter of the stem 20 is limited to a size that allows the sensor chip 30 to be mounted. It is possible to provide a structure for fixing the stem to the housing, which is suitable for a plurality of chips and in which a plurality of chips can be arranged. Further, in the present embodiment, since the communication passage 16 is provided for each stem 20, pressure can be appropriately guided to the diaphragm 21 of each stem 20.

According to the present embodiment, the rotation axis of the screw portion 24 of each stem 20 is used as the rotation axis of the screw portion 11 (the center axis of the housing) formed on the outer peripheral surface on one end side of the housing 10. It is characterized in that it is located on one circumference centered on the center, and that the cross-sectional shape of the pressure introduction passage 13 is configured as a circular shape corresponding to the circle.

Thus, the screw portion 1 of the housing 10
Since the axis of the pressure introduction passage 13 coincides with the axis of the pressure introduction passage 13, the pressure introduction passage 13 can be easily formed in the housing 10 by cutting, cold forging, or the like. In addition, by positioning the rotation axes of the threaded portions 24 of the stems 20 on the same circumference, the passage cross-sectional area of the pressure introduction passage 13 does not become unnecessarily large, which is preferable for downsizing the housing 19. .

By the way, if one of the stems 2
When the rotation axis of the zero screw portion 24 is displaced from the circumference of the pressure introduction passage 13, the cross-sectional shape of the pressure introduction passage 13 becomes a circle eccentric with respect to the center axis of the housing. Therefore, the housing 10 at the opening 12 of the passage 13
Is uneven, the area of the housing seal surface 14 is also uneven, which is not preferable.

Further, according to this embodiment, in the pressure introducing passage 13 which is a hole extending from the opening 12 into the housing 10, the end point 13 a of the hole in the housing 10 is set to the screw portion 11 of the housing 10. The fuel pipe (measured object) K1 is located at a portion corresponding to a portion to be screw-connected.

According to this, the portion of the housing 10 where the pressure introduction passage 13 is formed is supported by the pipe K1 on the outer periphery thereof when attached to the pipe K1, so that the high pressure applied to the pressure introduction passage 13 Accordingly, concentration of stress generated in the housing 10 can be suppressed.

According to the present embodiment, the IC chip 48 is arranged on the surface of the ceramic substrate (circuit board) 40 opposite to the wire bonding surface, so that the housing 1
The space inside the space is effectively used, contributing to downsizing of the sensor.

According to the present embodiment, the stem 2 between the diaphragm 21 and the male screw portion (screw portion) 24 is formed.
Since the nut portion (surface portion) 25 for applying a screw tightening force to the male screw portion 24 at the time of screw connection is formed on the outer peripheral side surface of the stem 0, the stem 20 and the housing 10 can be easily screw-connected. Can be preferred. The nut 25
Is not limited to a hexagonal shape, that is, a hexagonal shape as long as it has at least two surfaces facing each other at a certain angle so that screws can be tightened.

Here, in the present embodiment, as a preferred embodiment, as shown in FIG.
The stem 20 is thicker than a portion between the nut portion 25 and the diaphragm 21, and the outer peripheral surface of the nut portion 25 is positioned so as to protrude outward from the outer periphery of the diaphragm 21.

The screw between the stem 20 and the housing 10 is tightened by rotating the stem 20 with a jig for screw tightening on the outer peripheral surface of the nut 25 as described above.
At this time, by making the outer peripheral surface of the nut portion 25 protrude outward from the outer periphery of the diaphragm 21, the jig for tightening the screw is formed by the diaphragm 21 and the sensor chip (detector).
30 can be suppressed.

Further, since the nut portion 25 is made thicker than the portion of the stem 20 between the nut portion 25 and the diaphragm 21, the screw tightening force is applied to the diaphragm 21 as the sensing portion of the pressure sensor and the sensor chip. 30 will not be easily transmitted. Thus, according to the preferred embodiment of the present embodiment, it is possible to reduce damage to the sensing unit.

In the present embodiment, since the stem 20 is screw-connected, the sensor chip 30 is positioned with respect to the normal arrangement in the step of wire-bonding each sensor chip 30 and the terminal 42 of the ceramic substrate 40. The position may be shifted around the rotation axis of the screw portion 24 of the stem 20 (stem rotation axis), which may cause problems such as difficulty in wire bonding and the need to correct the position of the ceramic substrate 40. In the present embodiment, this problem is solved by devising the arrangement of the pads on the sensor chip 30, as shown in FIG.

FIG. 5 is a schematic diagram showing an example of a connection configuration of the ceramic substrate 40 and the sensor chip 30 by the wires 44 in the present embodiment (a diagram viewed from the stem rotation axis direction).
It is. In FIG. 5, (a) shows a case where the chip 30 is at a regular position, (b) shows a case where the chip 30 is rotated 22.5 ° counterclockwise from the regular position, and (c) shows a case where the chip 30 is rotated.
Is rotated 45 ° counterclockwise from the normal position.

As shown in FIG. 5, the sensor chip 30 includes:
Pads P1 to P4 for wire bonding are formed by vapor deposition of Al (aluminum) or the like. In FIG. 5, each of the pads P1, P2, P3, P4
, Is indicated. In this example, the four pads P1 to P4 are set as a set of pads, and the order of the pads in each set is set to P1 in a counterclockwise direction with respect to the stem rotation axis around the chip 30 having a rectangular plate shape. , P2, P3, and P4, the sets of the pads are arranged one by one.

Here, each pad P1, P
Reference numerals 2, P3, and P4 denote a power terminal pad and an output (-) terminal pad of the bridge circuit 31 of the chip 30, respectively.
These correspond to power supply terminal pads and output (+) terminal pads. The power supply terminal pad P1 and the output (-)
The terminal pad P2, the power supply terminal pad P3, and the output (+) terminal pad P4 are located at regular positions shown in FIG. ) The terminal T2, the power supply terminal T3, and the output (+) terminal T4 are connected by wires 44, and the bridge circuit 31 of the chip 30 is in a connected state as shown.

In the state of misalignment of the degree shown in FIG. 5B, the connection state at the normal position can be maintained using the set (first set) of pads P1 to P4 connected at the normal position. Wire bonding. However, FIG.
In the state shown in (c), since the displacement is large,
If an attempt is made to connect only the first set, the wires are too long in the first set of pads P1 and P2. For this reason, problems such as disconnection of the wire and deterioration of the bondability due to resonance at the time of wire bonding occur, and the connection is substantially impossible.

However, according to the present embodiment, FIG.
In the sensor chip 30, even if the position shift is large as shown in FIG.
Pads (P2 and P2) in the set (second set) are located at positions where wire bonding can be performed with the terminals T1 and T2 of the ceramic substrate 40.

Then, as shown in FIG. 5C, if the terminals T1 to T4 of the ceramic substrate 40 and the pads P1 to P4 of the sensor chip 30 are wire-bonded, it is possible to perform wire bonding at a regular position. Circuit characteristics can be maintained. That is, in all the bridge circuits 31 of FIGS. 5A to 5C, the resistance change direction between T1 and T4 and the resistance change direction between T2 and T3 both increase, and the equivalent circuit characteristics are maintained. I have.

Although not shown in FIG. 5, when the sensor chip 30 is rotated 90 ° counterclockwise from its normal position, the second set of pads P1 to P4 is replaced with the first set. Thus, wire bonding with each of the terminals T1 to T4 of the ceramic substrate 40 is possible so as to maintain the circuit characteristics at the regular positions. Also, when the sensor chip 40 is displaced clockwise with respect to the stem rotation axis, it is needless to say that the same effect is obtained as in the case of counterclockwise rotation.

As described above, in the present embodiment, the chip 30
When the power supply terminal pads P1 and P3 and the output terminal pads P2 and P4 of the bridge circuit 31 in the chip 30 in the normal position are placed in a predetermined order around the rotation axis of the screw connection in the stem (stem rotation axis). , The bonding wires 44 can be connected so as to maintain the same circuit characteristics as when the chip 30 is at the normal position.

Therefore, according to the present embodiment, the chip 30
In this case, wire bonding can be easily performed even if the position shift about the stem rotation axis occurs, and the position of the ceramic substrate 40 is not corrected. Then, the ceramic substrate 40
Subsequent assembling of the sensor is performed based on the substrate 40, so that in the present sensor 100, it is possible to prevent the displacement of the chip 30 from affecting the workability of the assembling.

As described above, in the present embodiment, each of the two stems 20
A main feature is that a screw portion 24 is formed on the outer peripheral side surface of each of the stems, and each stem 20 is screw-connected to the housing 10 via the screw portion 24 so as to be pressed toward the other end of the shaft. . In the above example, an example in which two stems are provided has been described. However, as shown in FIG. 2A, there is an empty space in the housing 10 where another stem can be arranged. That is, in FIG. 2A, it is sufficient to arrange the three stems so that a triangle is formed by the rotation axes of the three stems. Further, if possible, four or more stems may be arranged.

As a modified example of this embodiment, as shown in FIG. 6, in the pressure sensor 100, the pressure introducing passage 13 is constituted by a plurality of holes provided corresponding to each communication passage 16. May be.

By providing the pressure introducing passage 13 for each of the communication passages 16 provided for each of the plurality of stems 20, each communication passage 1 as shown in FIG.
6, the volume occupied by the pressure introduction passage 13 in the housing 10 can be minimized, as compared with the case where one pressure introduction passage 13 is provided corresponding to 6. Therefore, the rigidity of the housing 10 at the portion where the pressure introduction passage 13 is formed can be suitably secured, which is preferable for increasing the pressure resistance of the sensor.

Further, as shown in FIG.
By arranging each hole in 3 nearer to the center axis of the housing 10 than the corresponding communication path 16, the area of the outer peripheral portion of each hole in the housing 10 can be increased.

The outer peripheral portion of each hole in the housing 10
This is a housing seal surface 14 for sealing with the measured object K1 in the sensor described above. By increasing the area of the sealed surface 14, the sealing performance with the measured object K1 is improved, and it is more suitable for higher pressure resistance. A pressure sensor can be realized.

In the pressure sensor 100,
The pressure introducing passage 13 is a hole having a cross section formed by a circle extending into the housing 10 from the opening 12 formed at one end of the housing 10. As another modified example of the present embodiment, FIG. As shown in (1), it is preferable to form the pressure introducing passage 13 obliquely from the opening 12 into the housing 10 by cutting or molding.

According to this, the opening 12 of the pressure introducing passage 13 can be suitably reduced, and the outer peripheral portion of the opening 12, that is, the housing sealing surface 14 which is a sealing portion with the measured object K1 in the sensor is formed. The area can be increased. That is, it is possible to improve the sealing performance with the measured object K1 and to realize a pressure sensor suitable for higher withstand pressure.

The number of stems 20 may be one. In this case, although not shown, for example, the screw portion 1 of the housing 10
The stem 20 may be arranged so that one rotation axis coincides with the rotation axis of the screw portion 24 of one stem 20.
In this case, the communication passage 16 is unnecessary, and the cross-sectional area of the pressure introduction passage 13 can be made smaller than that in the case of two.

The detecting unit provided on the diaphragm and outputting an electric signal according to the deformation of the diaphragm is not limited to the above-mentioned sensor chip. A gauge may be used as the detection unit.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an entire configuration of a pressure sensor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a main part of the pressure sensor shown in FIG.

FIG. 3 is an enlarged view of one end of a shaft of a stem.

FIG. 4 is a configuration diagram of a stem alone.

FIG. 5 is a schematic diagram illustrating details of connection between a ceramic substrate and a sensor chip.

FIG. 6 is a schematic sectional view showing a modification of the embodiment.

FIG. 7 is a schematic sectional view showing another modified example of the embodiment.

FIG. 8 is a schematic sectional view showing a pressure sensor as a prototype of the inventor.

[Explanation of symbols]

10 ... housing, 11 ... screw part of housing, 12 ...
Opening of the housing, 13 ... pressure introduction passage, 13a ... end point of pressure introduction passage, 16 ... communication passage, 20 ... stem, 21
... diaphragm, 22 ... stem opening, 24 ... stem screw, 25 ... nut, 30 ... sensor chip.

Claims (10)

[Claims] 1. A housing (10) having a pressure introducing passage (13) capable of introducing pressure, and a diaphragm (21) housed in the housing and deformable at one end of a shaft by a pressure introduced into the housing. And a hollow cylindrical stem (2) having an opening (22) communicating with the pressure introduction passage at the other end of the shaft.
0), and a detection unit (30) provided on the diaphragm and outputting an electric signal according to the deformation of the diaphragm, wherein the stem is provided on a side surface of an outer periphery of the stem. A pressure sensor characterized in that a screw portion (24) for screw-connecting with the housing is integrally formed so as to be pressed toward the other end of the shaft. 2. A housing (10) having a pressure introduction passage (13) capable of introducing pressure, and a diaphragm (21) housed in the housing and deformable at one end of a shaft by a pressure introduced into the housing. And a hollow cylindrical stem (2) having an opening (22) communicating with the pressure introduction passage at the other end of the shaft.
0), and a detection unit (30) provided on the diaphragm and outputting an electric signal according to the deformation of the diaphragm, wherein a plurality of the stems are provided. The pressure sensor according to claim 1, wherein a screw portion (24) for screw-connecting the housing to the housing is formed on a side surface of an outer periphery of the stem so as to press the stem toward the other end of the shaft. 3. A communication passage (16) for communicating the opening (22) with the pressure introduction passage (13) for each of the stems (20).
The pressure sensor according to claim 2, wherein the pressure sensor is formed as follows. 4. An outer peripheral surface on one end side of the housing (10) is formed with a screw portion (11) that can be screw-coupled to a measured object, and the screw portion (11) of each of the stems (20). The rotation shaft of 24) is located on one circumference centered on the rotation axis of the screw portion of the housing, and the pressure introduction passage (13) is formed in an opening formed at one end of the housing. The pressure sensor according to claim 2, wherein the pressure sensor is a hole having a cross-sectional shape formed by extending the circle into the housing from (12). 5. A screw portion (11) that can be screw-coupled to a measured object is formed on an outer peripheral surface on one end side of the housing (10), and the pressure introduction passage (13) is formed in the housing. A hole extending into the housing with an opening (22) formed at one end as a starting point, wherein an end point (13a) of the hole in the housing is screw-coupled to the object to be measured in the screw portion; The pressure sensor according to any one of claims 1 to 3, wherein the pressure sensor is located at a site corresponding to (i). 6. The pressure introducing passage (13) is constituted by a plurality of holes provided corresponding to each of the communication passages (16). Pressure sensor. 7. The pressure sensor according to claim 6, wherein each of the holes is disposed closer to the center axis of the housing than the corresponding communication passage. 8. The device according to claim 4, wherein the pressure introducing passage is formed obliquely from the opening to the inside of the housing. Pressure sensor. 9. A side surface of an outer periphery of the stem (20) between the diaphragm (21) and the screw portion (24) for applying a screw tightening force to the screw portion during the screw connection. The pressure sensor according to any one of claims 1 to 8, wherein the surface portion (25) is formed. 10. The stem (2) is provided on the stem (2).
0) is thicker than a portion between the surface portion and the diaphragm (21), and the outer peripheral surface of the surface portion is positioned so as to protrude outward from the outer periphery of the diaphragm. The pressure sensor according to claim 9.