JPH05157651A - Pressure sensor - Google Patents

Abstract

PURPOSE:To enable detection performance and life to be improved by preventing stress concentration from being generated on a diaphragm. CONSTITUTION:By forming an annular groove 22 at a central part in axial direction of an outer-periphery side of a small-diameter cylindrical part 21 with a length L in axial direction a thin cylindrical diaphragms 23 with the length L in axial direction is formed at an inner-periphery side of the annular groove 22. A smooth circular shape is achieved with a radius dimension R where a center is positioned on a line where upper and lower edge parts 22A and 22B of the annular groove 22 are extended from both edges in axial direction outwardly in radius direction and at the same time a corner part B of a rod insertion hole 25 is separated to a side of a pressure-reception part 24 by a specified dimension Lt from a lower edge of the diaphragm 23. Therefore, even if the pressure-reception part 24 receives an outer pressure and a stress is applied to the diaphragm 23, concentration of the stress near a lower edge (a lower edge part 22B of the annular groove 22) of the diaphragm 23 is prevented, thus enabling a dimension control of a length dimension L in axial direction to be performed accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor suitable for use as a combustion pressure sensor for detecting combustion pressure in, for example, automobile engines.

[0002]

2. Description of the Related Art FIGS. 5 and 6 will be described by taking a combustion pressure sensor for detecting combustion pressure of an engine as an example of a pressure sensor according to the prior art.

In the figure, reference numeral 1 denotes a casing, 2 denotes a casing main body which constitutes the casing 1 together with a small-diameter tubular portion 3 which will be described later, and the casing main body 2 is located at the upper side and is formed in a large-diameter tubular shape. Large-diameter tubular portion 2A and the large-diameter tubular portion 2
It is provided in the lower end side of A, and is formed in a stepped tubular shape from a shoulder portion 2B formed in a tapered shape whose diameter is sequentially reduced downward. The casing body 2 is inserted into the stepped hole so that the shoulder portion 2B abuts the stepped portion (not shown) of the stepped hole formed in the cylinder head of the engine body. ..

Reference numeral 3 denotes a small-diameter cylindrical portion integrally formed on the lower end side of the casing main body 2. The small-diameter cylindrical portion 3 is axially arranged from the tip of the shoulder portion 2B of the casing main body 2 as shown in FIG. Thin-walled cylindrical diaphragm 4 extending downward
And a thick disk-shaped pressure receiving portion 5 provided on the tip side of the diaphragm 4 and facing the combustion chamber (not shown) of the engine,
The upper end side is opened into the casing main body 2, and the lower end side is formed into a bottomed cylindrical shape having a small diameter from a rod insertion hole 6 which is a conical bottom portion 6A reaching the upper end side of the pressure receiving portion 5.
The diaphragm 4 and the pressure receiving portion 5 have the same outer diameter. When the pressure receiving portion 5 receives the pressure (combustion pressure) in the combustion chamber, the small-diameter cylindrical portion 3 bends the diaphragm 4 in the axial direction according to the pressure, and displaces the pressure receiving rod 9 described later in the axial direction. It is what makes them.

Here, the manufacturing method of the small-diameter cylindrical portion 3 is as follows. First, in the outer shape cutting step, the outer peripheral side of the base material to be the small-diameter cylindrical portion 3 is subjected to cutting processing such as lathe processing or grinding processing to form a cylindrical body. (Not shown). Next, in the axial hole drilling process,
The rod insertion hole 6 is drilled from the casing body 2 side in the axial direction of the columnar body formed by the outer shape cutting step, so that the diaphragm 4 having the axial length dimension L on the outer periphery on the upper end side. The small-diameter cylindrical portion 3 in which is formed is manufactured.

Reference numeral 7 denotes a stepped cylindrical upper cover which is fixed to the upper end side of the casing body 2 by means such as laser welding. The upper cover 7 has an upper side projecting upward to the outside of the cylinder head. The reduced diameter portion 7A is formed, and the upper cover 7 is formed.
Is attached to the engine body via a reduced diameter portion 7A loosely fitted to the attachment stay 8.

Reference numeral 9 denotes a pressure receiving rod which is located in the rod inserting hole 6 and is provided so as to be displaceable in the axial direction. The pressure receiving rod 9 has a spherical surface portion 9A on the lower end side thereof. A lower plate 10 which is in contact with the inner surface side of the pressure receiving portion 5 via a bottom portion 6A thereof and has an upper end side conical portion 9B made of an insulating ceramic material or the like, and a contact portion 13A of a contact plate 13 described later. It is in contact with a piezoelectric body 11 described later via. And the pressure receiving rod 9
When the pressure receiving portion 5 that receives the combustion pressure is displaced in the axial direction,
The piezoelectric body 11 is pressed through the lower plate 10 and the like by the pressing force corresponding to the displacement amount, and the high temperature in the combustion chamber is prevented from being transmitted to the piezoelectric body 11.

Reference numeral 11 denotes a piezoelectric body formed in a cylindrical shape from a piezoelectric material such as lead titanate, which is provided inside the large-diameter cylindrical portion 2A of the casing body 2 and is provided on the upper end side of the conical portion 9B of the pressure receiving rod 9. A sheet-like upper electrode and lower electrode (both not shown) are formed on both end surfaces of the piezoelectric body 11,
The lower electrode is on the plus side, contacts the contact portion 12A of the contact plate 12, and the upper electrode is on the minus side. The upper plate 12 is formed in an annular shape from a conductive metal material, and will be described later. It is grounded to the casing body 2 via a set screw 15. When the pressure receiving portion 5 receives the combustion pressure in the combustion chamber, the piezoelectric body 11 receives
The conical portion 9B of the pressure receiving rod 9 is pressed by the pressing force corresponding to the combustion pressure.
By being pressed by, the electromotive force corresponding to the compression strain at this time is output as a combustion pressure detection signal.

Reference numeral 13 denotes a contact plate made of a conductive material, which is provided inside the large-diameter cylindrical portion 2A of the casing body 2 so as to face the pressure receiving rod 9.
A disk-shaped contact portion 13A is formed on the lower end side of the contact member 3, the lower surface side of the contact portion 13A abuts on the piezoelectric body 11, and the upper end side extends into the reduced diameter portion 7A of the upper cover 7 to form a lead wire. It is fixed to 14 by crimping. Further, the contact plate 13 is insulated from the casing body 2 by the insulating tubes 16 and 17 and the lower plate 10 which will be described later. The contact plate 13 transmits the voltage signal from the piezoelectric body 11 to the control unit (not shown) via the lead wire 14.

Reference numeral 15 denotes a set screw screwed into the large-diameter cylindrical portion 2A of the casing body 2, and the set screw 15 is formed of a conductive metal material into a substantially cylindrical shape. The set screw 15 is connected to the piezoelectric body 11 via the upper plate 12.
Is pressed downward with a predetermined load to apply an initial load to the piezoelectric body 11.

Reference numeral 16 denotes a small-diameter cylindrical upper insulating tube which is provided on the outer peripheral side of the contact plate 13 and insulates the contact plate 13 from the set screw 15.
7 is provided on the outer peripheral side of the contact portion 13A of the contact plate 13, the piezoelectric body 11 and the like.
A, a large-diameter cylindrical lower insulating tube that insulates the piezoelectric body 11 and the like from the casing body 2 is shown. The lower insulating tube 17 surrounds the contact portion 13A, the piezoelectric body 11, the pressure receiving rod 9, and the like. By doing so, these are also positioned.

Reference numeral 18 denotes a seal member fitted and fixed to the upper end side of the reduced diameter portion 7A of the upper cover 7 by means such as caulking. The seal member 18 prevents the lead wire 14 from being pulled out, and prevents external rainwater and the like. The upper cover 7 is prevented from entering.

Reference numerals 19 and 19 denote two disc springs disposed between the free end side of the mounting stay 8 and the upper end side of the reduced diameter portion 7A of the upper cover 7, and each disc spring 19 is the spring thereof. The shoulder portion 2B of the casing body 2 is constantly pressed by the force to the step portion of the stepped hole formed in the cylinder head to close the stepped hole, so that the combustion pressure in the combustion chamber passes through the stepped hole and The vibration of the engine main body transmitted through the mounting stay 8 is damped while preventing the vibration from leaking to the outside, and the vibration is prevented from being transmitted to the piezoelectric body 11.

The combustion pressure sensor according to the prior art has the above-mentioned structure, and its operation will be described below.

First, when the air-fuel mixture sucked into the combustion chamber of the engine is ignited and a combustion pressure is generated, the pressure receiving portion 5 which receives this combustion pressure flexes the diaphragm 4 in the axial direction,
The pressure receiving rod 9 is displaced in the axial direction, and the lower plate 10,
The piezoelectric body 11 is pressed via the contact portion 13A of the contact plate 13. As a result, the piezoelectric body 11 is
Charge (voltage) according to the pressure applied from the pressure receiving rod 9
Is generated and is output to the control unit via the contact plate 13 and the lead wire 14 as a combustion pressure detection signal.

[0016]

By the way, according to the above-mentioned prior art, by forming the rod insertion hole 6 in the axial direction in the cylindrical body which becomes the base of the small diameter cylindrical portion 3,
A cylindrical diaphragm 4 having an axial length dimension of L is formed on the outer peripheral side of this columnar body, and the diaphragm 4 is formed on the lower end side.
Since the disk-shaped pressure receiving portion 5 having the same diameter as that of the rod insertion hole 6 is formed, the bottom portion 6A of the rod insertion hole 6 (hereinafter,
The corner portion A) and the lower end of the diaphragm 4 coincide with each other. As a result, when the combustion pressure is received by the pressure receiving portion 5, stress concentration is likely to occur in the vicinity of the corner portion A, and this stress concentration not only makes the detection performance unstable, but the stress at the time of pressure reception also increases the stress at the corner portion. The diaphragm 4 may be damaged by concentrating in the vicinity of the portion A, and there is a problem that reliability and life are significantly reduced.

Further, since the rod insertion hole 6 is formed by drilling or the like, it is difficult to accurately obtain the depth dimension of the rod insertion hole 6, and the length dimension L of the diaphragm 4 in the axial direction varies. Will occur. As a result, there is a problem in that the pressure receiving section 5 cannot be accurately displaced according to the pressure at the time of combustion, the detection performance becomes unstable, and the reliability is significantly reduced.

Further, since the diaphragm 4 is formed between the lower end (outer peripheral side) of the shoulder portion 2B of the casing body 2 and the corner A (inner peripheral side) of the rod insertion hole 6, the parts after fabrication are manufactured. When measuring the axial length dimension L in an inspection or the like, it is necessary to measure from the inner peripheral side and the outer peripheral side of the small diameter cylindrical portion 3, and this measuring method requires a very long time at the time of measurement. However, there is a problem that productivity is significantly reduced.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a pressure sensor capable of preventing stress concentration on the diaphragm and improving detection performance and life. To do.

[0020]

In order to solve the above-mentioned problems, the feature of the configuration adopted by the first invention is that the diaphragm is formed to have a smaller diameter than the pressure receiving portion, and the rod insertion hole has a bottom portion at which the diaphragm is formed. It is formed so as to be separated from the one end by a predetermined dimension toward the pressure receiving portion side.

The feature of the structure adopted by the second invention is that the inner diameter of the diaphragm is formed to be larger than that of the rod insertion hole, and the bottom portion of the rod insertion hole is a predetermined pressure from one end of the diaphragm. It is formed so as to be separated to the side.

Further, the feature of the configuration adopted by the third invention is that the outer diameter of the diaphragm is formed smaller than the pressure receiving portion, and the inner diameter is formed larger than the rod insertion hole.
The rod insertion hole is formed so that its bottom portion is separated from one end of the diaphragm by a predetermined dimension toward the pressure receiving portion side.

[0023]

With the above construction, even if the pressure receiving portion receives pressure and bends the diaphragm, the stress at this time is prevented from concentrating on the lower end portion of the diaphragm, and the outer peripheral side or inner peripheral side of the diaphragm is prevented. Therefore, by checking the processing state of the diaphragm, it is possible to accurately control the dimension of the diaphragm.

[0024]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4 by taking a combustion pressure sensor as an example of a pressure sensor.

First, FIGS. 1 and 2 show an embodiment according to the first invention. In this embodiment, the same components as those of the prior art shown in FIGS. 5 and 6 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a small-diameter tubular portion according to this embodiment, which is located on the lower end side of the shoulder portion 2B of the casing body 2 in the same manner as the small-diameter tubular portion 3 described in the prior art. Diaphragm 2 which will be described later and is integrally formed.
3, the pressure receiving portion 24, and the rod insertion hole 25 form a bottomed cylindrical body having a small diameter, but an annular groove 22 is formed on the outer peripheral side of the small diameter cylindrical portion 21 at an axially intermediate portion thereof. Has been formed.

Here, the small-diameter cylindrical portion 21 has an annular groove 22 having an axial length dimension L at an axially intermediate portion on the outer peripheral side thereof.
The small-diameter cylindrical portion 2 is formed by recessing the
A thin cylindrical diaphragm 23 having an axial length dimension of L is formed at an axially intermediate portion of 1. In addition, the axial upper and lower end portions 22A and 22B of the annular groove 22 prevent stress due to the pressure from concentrating on the end portions 22A and 22B when pressure is applied from the outside. The diaphragm 23 is formed in a smooth arc shape with a radial dimension R whose center is located on a line extending outward in the radial direction from both ends in the axial direction of the diaphragm 23.

Reference numeral 24 denotes a disc-shaped pressure receiving portion provided on the lower end side of the diaphragm 23, and 25 denotes a rod insertion hole according to the present embodiment formed by extending the inside of the diaphragm 23 in the axial direction. The hole 25 has a conical bottom portion 25A on the lower end side thereof, similar to the rod insertion hole 6 described in the prior art. However, the rod insertion hole 25 has an upper end portion (hereinafter referred to as a corner corner) of the bottom portion 25A. The portion B) is deeply formed on the pressure receiving portion 24 side so as to be separated from the lower end of the diaphragm 23 by a predetermined dimension Lt.

Next, a method of manufacturing the small diameter cylindrical portion 21 will be described.

First, in the outer shape cutting step, the small-diameter cylindrical portion 21 is later.
By cutting or grinding such as lathe processing on the outer peripheral side of the base material to be formed, as shown in FIG. 2, an annular groove 22 having an axial length dimension L is formed in the axially intermediate portion on the outer peripheral side. The upper and lower ends 22A and 22B form a stepped columnar body 26 having a radius R and formed in an arc shape. Next, in the axial hole drilling process, drilling or the like is performed from the casing body 2 side in the axial direction of the stepped columnar body 26 formed by the outer shape cutting process, and the corner portion B is the lower end of the diaphragm 23. By forming the rod insertion hole 25 as a deep hole so as to be separated from the pressure receiving portion 24 side by a predetermined dimension Lt, the small diameter cylindrical portion 21 as shown in FIG. 1 is manufactured.

The combustion pressure sensor according to this embodiment has the above-mentioned structure, and its basic operation is not different from that of the prior art.

However, in this embodiment, the annular groove 2 is provided with the axial length dimension L at the axially intermediate portion on the outer peripheral side of the small diameter tubular portion 21.
2 is formed, a thin cylindrical diaphragm 23 having an axial length L is formed on the inner peripheral side of the annular groove 22, and each end 22A, 22B of the annular groove 22 is formed with a radial dimension R. And a corner portion B of the rod insertion hole 25 is separated from the lower end of the diaphragm 23 toward the pressure receiving portion 24 by a predetermined dimension Lt. Therefore, even if the pressure receiving portion 24 receives the combustion pressure and the stress acts on the diaphragm 23, the stress can be prevented from being concentrated near the lower end of the diaphragm 23 (the lower end portion 22B of the annular groove 22). it can.

Further, since the diaphragm 23 is formed by cutting or grinding such as lathe processing, its axial length dimension L can be accurately and easily obtained.
It is possible to prevent variations in dimensional accuracy during machining such as drilling.

Thus, according to this embodiment, it is possible to prevent the stress due to the combustion pressure from concentrating on the lower end of the diaphragm 23, effectively prevent the variation in the detection performance due to the stress concentration, and greatly improve the reliability. In addition, the diaphragm 23 can be prevented from being damaged due to stress concentration, and the life can be greatly improved.

Further, since the axial length dimension L of the diaphragm 23 can be accurately and easily obtained, it is possible to prevent the detection performance from becoming unstable due to the variation of the axial length dimension L of the diaphragm 23, It is possible to stabilize the detection performance and further improve the reliability.

Further, also in the inspection of the parts after fabrication, the axial length dimension L of the diaphragm 23 can be measured and inspected from one side (outer side), and the dimension control of the axial length dimension L can be accurately and accurately performed. Since it can be easily performed, it is possible to shorten the part inspection time and significantly improve the productivity.

Next, FIG. 3 shows an embodiment according to the second invention. In the embodiments, the same components as those of the conventional technique shown in FIGS. 5 and 6 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 31 denotes a small-diameter cylindrical portion according to this embodiment, which is located on the lower end side of the shoulder portion 2B of the casing body 2 in the same manner as the small-diameter cylindrical portion 3 described in the prior art. Diaphragm 3 which will be described later and is integrally formed.
3, the pressure receiving portion 34, and the rod insertion hole 35 form a bottomed cylindrical body having a small diameter, but the annular groove 32 is located on the inner peripheral side of the small diameter cylindrical portion 31 at an axially intermediate portion thereof. Are formed.

Here, the small-diameter cylindrical portion 31 has an annular groove 32 with an axial length dimension L in the axially intermediate portion on the inner peripheral side thereof.
Is formed so as to be dented outward in the radial direction, so that a thin cylindrical diaphragm 33 having an axial length dimension L is formed in the axially intermediate portion of the small diameter tubular portion 31. Also, the upper and lower ends 32A of the annular groove 32 in the axial direction,
32B has a radial dimension R whose center is located on a line extending radially inward from both axial ends of the diaphragm 33, similarly to the upper and lower ends 22A and 22B according to the above-described first embodiment of the invention. It is formed in a smooth arc shape.

Reference numeral 34 denotes a disc-shaped pressure receiving portion provided on the lower end side of the diaphragm 33, and reference numeral 35 denotes a rod insertion hole according to the present embodiment formed by extending the inside of the diaphragm 33 in the axial direction. Like the rod insertion hole 25 according to the first embodiment of the present invention, the hole 35 has a conical bottom portion 35A formed on the lower end side thereof so that the pressure receiving portion 34 is separated from the lower end of the diaphragm 33 by a predetermined dimension Lt. It is deeply drilled on the side.

Thus, the operation and effect of this embodiment thus constructed are the same as those of the above-described first embodiment of the invention.

Next, FIG. 4 shows an embodiment according to the third invention. In the embodiments, the same components as those of the conventional technique shown in FIGS. 5 and 6 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 41 denotes a small-diameter cylindrical portion according to this embodiment, which is located on the lower end side of the shoulder portion 2B of the casing main body 2 in the same manner as the small-diameter cylindrical portion 3 described in the prior art. Diaphragm 4 which will be described later and is integrally formed.
Although it is a bottomed cylindrical body having a small diameter from 4, the pressure receiving portion 45 and the rod insertion hole 46, it is located on the outer peripheral side and the inner peripheral side of the small diameter cylindrical portion 41 at the intermediate portion in the axial direction. An outer annular groove 42 and an inner annular groove 43 are formed.

Here, the small-diameter tubular portion 41 has an outer annular groove 4 having an axial length dimension L at an axially intermediate portion on the outer peripheral side thereof.
2 is recessed so as to be recessed, and an inner annular groove 43 corresponding to the axial position and the axial length dimension L of the annular groove 42 is recessed radially outwardly on the inner peripheral side. As a result, a thin-walled cylindrical diaphragm 44 having an axial length dimension of L is formed in the axially intermediate portion of the small diameter tubular portion 41. The axial upper ends 42A, 43A and the lower ends 42B, 43B of the annular grooves 42, 43 are stressed by the pressure when pressure is applied from the outside. , 43B, each of them is formed in a smooth arc shape with a radial dimension R whose center is located on a line extending radially from both axial ends of the diaphragm 44.

Reference numeral 45 denotes a disc-shaped pressure receiving portion provided on the lower end side of the diaphragm 44, and 46 denotes a rod insertion hole according to the present embodiment formed by extending the inside of the diaphragm 44 in the axial direction. Similar to the rod insertion hole 25 described in the first embodiment of the invention, the hole 46 has a pressure receiving portion 45 such that the conical bottom portion 46A on the lower end side thereof is separated from the lower end of the diaphragm 44 by a predetermined dimension Lt. It is deeply drilled on the side.

Thus, also in the present embodiment having such a configuration, the manufacturing method, the operation and the effect are the same as those of the above-mentioned first embodiment of the invention.

In each of the above embodiments, the rod insertion hole 2
Although it has been described that the holes 5, 35, 46 are formed deeper on the pressure receiving portions 24, 34, 45 side than the rod insertion hole 9 described in the prior art, in this case, the shape of the lower end side of the casing main body 2 is formed. Also, the length of the pressure receiving rod 9 is appropriately changed.

Further, in each of the above embodiments, the small-diameter cylindrical portion 21,
Although the manufacturing method of 31 and 41 is described as performing the axial hole drilling step after performing the external shape cutting step, the present invention is not limited to this, and the axial hole drilling step and the external shape cutting step are performed in this order. Or these steps may proceed simultaneously.

Furthermore, in each of the above-mentioned embodiments, the combustion pressure sensor has been described as an example of the pressure sensor. However, instead of this, the pressure of gas such as air, industrial gas, etc., fuel, liquid such as water, etc. It can also be applied to a pressure sensor for detecting. Further, it may be used as a knock sensor for detecting knocking of the engine.

[0050]

As described in detail above, according to the pressure sensor of each invention, the outer peripheral side of the diaphragm is formed to have a smaller diameter than the pressure receiving portion, and the inner peripheral side is formed to have a larger diameter than the rod insertion hole. Since the bottom portion of the rod insertion hole is separated from one end of the diaphragm toward the pressure receiving portion by a predetermined dimension, even if the pressure receiving portion receives pressure and bends the diaphragm, the stress due to this pressure causes It is possible to prevent concentration on the lower end of the diaphragm. As a result, it is possible to effectively prevent the detection performance from varying due to stress concentration, improve the detection accuracy, and effectively prevent the diaphragm from being damaged to improve the reliability of the pressure sensor. And life can be improved.
The dimensional control of the diaphragm can be accurately and easily performed from the outer peripheral side or the inner peripheral side of the diaphragm, and the dimensional inspection time can be shortened to improve the productivity.

[Brief description of drawings]

FIG. 1 is an enlarged vertical sectional view showing a small diameter cylindrical portion according to an embodiment of the first invention.

FIG. 2 is a vertical cross-sectional view showing a stepped columnar body before forming a rod accommodating hole.

FIG. 3 is an enlarged vertical cross-sectional view showing a small-diameter cylindrical portion according to an embodiment of the second invention.

FIG. 4 is an enlarged vertical cross-sectional view showing a small-diameter cylindrical portion according to an embodiment of the third invention.

FIG. 5 is a vertical sectional view showing a combustion pressure sensor according to a conventional technique.

FIG. 6 is an enlarged vertical sectional view showing a small-diameter cylindrical portion and the like in FIG.

[Explanation of symbols]

 2 Casing body 9 Pressure receiving rod 11 Piezoelectric body 22, 32, 42, 43 Annular groove 23, 33, 44 Diaphragm 24, 34, 45 Pressure receiving part 25, 35, 46 Rod insertion hole 25A, 35A, 46A Bottom part

Claims (3)

[Claims] 1. A large-diameter tubular casing, a tubular diaphragm provided axially extending from one end side of the casing, and an external pressure provided on one end side of the diaphragm. A plate-shaped pressure receiving portion, a rod insertion hole that is formed in the diaphragm in the axial direction and has one end side that is a bottom portion that reaches the pressure receiving portion, and the other end side that opens into the casing, and one end side that contacts the pressure receiving portion. A pressure receiving rod that is inserted into the rod insertion hole and is axially displaced according to the displacement of the pressure receiving portion; and a pressure receiving rod that is located inside the casing and is provided on the other end side of the pressure receiving rod. In a pressure sensor including a piezoelectric body that outputs the transmitted displacement of the pressure receiving portion as a voltage signal according to the pressure,
The pressure sensor, wherein the diaphragm is formed to have a smaller diameter than the pressure receiving portion, and the rod insertion hole is formed so that a bottom portion thereof is separated from one end of the diaphragm by a predetermined dimension toward the pressure receiving portion. 2. A large-diameter tubular casing, a tubular diaphragm axially extended from one end of the casing, and an external pressure provided on one end of the diaphragm. A plate-shaped pressure receiving portion, a rod insertion hole that is formed in the diaphragm in the axial direction and has one end side that is a bottom portion that reaches the pressure receiving portion, and the other end side that opens into the casing, and one end side that contacts the pressure receiving portion. A pressure receiving rod that is inserted into the rod insertion hole and is axially displaced according to the displacement of the pressure receiving portion; and a pressure receiving rod that is located inside the casing and is provided on the other end side of the pressure receiving rod. In a pressure sensor including a piezoelectric body that outputs the transmitted displacement of the pressure receiving portion as a voltage signal according to the pressure,
The diaphragm has an inner diameter larger than that of the rod insertion hole, and the rod insertion hole is formed such that a bottom portion thereof is separated from one end of the diaphragm by a predetermined dimension toward the pressure receiving portion. Sensor. 3. A large-diameter tubular casing, a tubular diaphragm axially extended from one end of the casing, and an external pressure provided on one end of the diaphragm. A plate-shaped pressure receiving portion, a rod insertion hole that is formed in the diaphragm in the axial direction and has one end side that is a bottom portion that reaches the pressure receiving portion, and the other end side that opens into the casing, and one end side that contacts the pressure receiving portion. A pressure receiving rod that is inserted into the rod insertion hole and is axially displaced according to the displacement of the pressure receiving portion; and a pressure receiving rod that is located inside the casing and is provided on the other end side of the pressure receiving rod. In a pressure sensor including a piezoelectric body that outputs the transmitted displacement of the pressure receiving portion as a voltage signal according to the pressure,
The diaphragm has an outer diameter smaller than that of the pressure receiving portion and an inner diameter larger than that of the rod insertion hole, and the bottom portion of the rod insertion hole has a predetermined dimension from one end of the diaphragm. A pressure sensor characterized in that it is formed so as to be spaced apart from the side.