JPH09159563A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability and reliability by outputting a detecting signal of stable pressure undependent on a temperature even when a temperature of a piezoelectric body changes. SOLUTION: A piezoelectric body 23 is provided with respective projecting parts 24 as a pressure receiving part to receive pressure and respective recessed parts 25 as a temperature compensating part to output a voltage signal according to an ambient temperature, and is constituted so that the respective projecting parts 24 and the respective recessed parts 25 are alternately arranged at specific intervals in the circumferential direction. The electrode areas arranged in the respective projecting parts 25 and the respective recessed parts 25 are set in the same, and polarizing shaft of the respective projecting parts 24 and the respective recessed parts 25 are set in the reverse direction, and are electrically connected in parallel to each other.

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 detecting the combustion pressure of, for example, an automobile engine.

[0002]

2. Description of the Related Art An example of detecting a combustion pressure of an engine as a conventional pressure sensor will be described with reference to FIGS.

In the figure, reference numeral 1 denotes a cylinder head of an engine. The cylinder head 1 defines a combustion chamber 2 as a pressure generating source for each cylinder, and a plug screw is attached to a portion communicating with the combustion chamber 2. The hole 3 is formed. Further, the upper surface side of the cylinder head 1 near the plug screwing hole 3 is a seat surface 1A for mounting an ignition plug with which a pressure sensor 5 and the like described later abut.

Reference numeral 4 denotes an ignition plug as a fastening member which is attached to the plug screwing hole 3 of the cylinder head 1. The ignition plug 4 projects toward the inside of the combustion chamber 2 at its tip end and ignites an air-fuel mixture or the like. It has an electrode portion 4A.

Reference numeral 5 denotes a pressure sensor which is fastened between the spark plug 4 and the cylinder head 1. The pressure sensor 5 includes a casing 6, a piezoelectric body 8, a lead plate 11, an upper plate 12 and a lower plate which will be described later. It is generally configured from 13 etc. into a substantially annular shape.

Reference numeral 6 denotes a casing which constitutes the main body of the pressure sensor 5. The casing 6 is formed as a ring-shaped annular body having a substantially square cross section by pressing a thin metal plate material or the like. An insertion hole 6A through which the spark plug 4 is inserted is provided. Further, inside the casing 6, a piezoelectric body 8 and a plate portion 11A of a lead plate 11 described later, an upper plate 12, a lower plate 13 and the like are housed.

Reference numeral 7 denotes a protective tube provided on the outer peripheral side of the casing 6, the protective tube 7 being made of a metal material, the proximal end side being brazed to the outer peripheral surface of the casing 6, and the distal end side being a cylindrical body described later. It extends upward along the line 17. The protective tube 7 protects the lead portion 11B and the like of the lead plate 11 from the outside and also serves as a ground wire for the piezoelectric body 8.

Reference numeral 8 denotes a piezoelectric body located inside the casing 6 and arranged on the plate portion 11A of the lead plate 11. The piezoelectric body 8 is a piezoelectric material such as lead titanate as shown in FIGS. The material is formed as an annular flat plate, and the ground side electrode 9 and the output side electrode 10 are formed on the upper and lower surfaces thereof by means of coating or the like. The piezoelectric body 8 is polarized so that the entire polarization axis is in the same direction with respect to the thickness direction, and the ground-side electrode 9 on the upper surface side includes the upper plate 12, the casing 6, the protective tube 7, and the like. The output side electrode 10 on the lower surface side is connected to the lead plate 11 while being grounded to the outside through the lead plate 11. The piezoelectric body 8 outputs a voltage signal corresponding to the combustion pressure to the lead plate 11 side.

Reference numeral 11 denotes a protective tube 7 from inside the casing 6.
FIG. 5 shows a lead plate provided over the entire length of the lead plate 11. As shown in FIG. 5, the lead plate 11 is located on the lower surface side of the piezoelectric body 8 in the casing 6 and has a plate portion 11A formed as an annular plate body, The plate portion 11A is generally composed of a lead portion 11B extending into the protective tube 7 as shown in FIG. 4, and the plate portion 11A is insulated from a lower plate 13 by an insulating sheet 14 which will be described later. Is connected to a control unit (neither is shown) via a lead wire.

12 is located inside the casing 6 and is a piezoelectric body 8.
The upper plate 12 is an upper plate disposed above, and is formed in an annular shape so as to cover the upper surface of the piezoelectric body 8 from a conductive metal material. Reference numeral 13 denotes an annular lower plate disposed on the lower surface side of the plate portion 11A of the lead plate 11 via an insulating sheet 14, and the lower plate 13 together with the upper plate 12 has a casing 6
The lead plate 11 and the piezoelectric body 8 and the like are clamped from the inside from above and below, and external pressure and vibration are uniformly applied to the entire piezoelectric body 8.

Reference numeral 14 is a plate portion 1 of the lead plate 11.
An insulating sheet 15 is provided between the lower plate 13 and the lower plate 13 to insulate them from each other. The insulating sheet 15 is located on the inner peripheral side of the casing 6 and includes the casing 6 and the upper plate 12 and the plate portion 11A of the lead plate 11. The insulating ring which insulates between is shown.

Reference numeral 16 denotes a washer provided on the upper surface side of the casing 6, and 17 denotes a cylindrical body provided on the washer 16. The cylindrical body 17 surrounds the periphery of the ignition plug 4 and electromagnetically. It is a shield.

The pressure sensor 5 according to the prior art has the above-described structure. First, the casing 6 is arranged on the seat surface 1A of the cylinder head 1, and in this state the washer 1 is placed.
6, the pressure sensor 5 is fixed to the cylinder head 1 by fastening the spark plug 4 to the cylinder head 1 via the casing 6. Further, at this time, by tightening the spark plug 4 with a predetermined tightening load, an initial load is applied to the piezoelectric body 8 via the casing 6 with the cylinder head 1.

The pressure sensor 5 mounted as described above is ignited by the combustion pressure of the engine.
Is pressed toward the side opposite to the combustion chamber 2, the load (pressure) received by the piezoelectric body 8 changes accordingly. Then, due to the change in the load, a voltage signal corresponding to the combustion pressure can be output from the piezoelectric body 8 to the external control unit (not shown) via the lead plate 11.

[0015]

By the way, in the above-mentioned prior art, when the high temperature in the combustion chamber 2 is transmitted to the pressure sensor 5 via the cylinder head 1, the casing 6, etc., the temperature of the piezoelectric body 8 rises. Then, the temperature rise of the piezoelectric body 8 generates electric charge due to the pyroelectric effect, and this electric charge is added to the voltage signal serving as the detection signal, so that the accurate combustion pressure cannot be detected, especially in warm-up operation or the like. When the temperature change of the piezoelectric body 8 is sudden, the voltage signal from the piezoelectric body 8 may drift.

For this reason, in the above-mentioned prior art, a temperature sensor such as a thermocouple or thermistor is provided in the vicinity of the piezoelectric body 8, the ambient temperature of the piezoelectric body 8 is detected by the temperature sensor, and the control unit side or the like is used. The voltage signal from the piezoelectric body 8 is corrected based on this detected temperature.

However, in this case, by additionally providing the temperature sensor, not only the electronic circuit and the correction program on the control unit side become complicated and the cost greatly increases, but also the pressure sensor 5 as a whole is attached by the amount of the temperature sensor installed. However, there is a problem in that the size becomes large and the degree of freedom in mounting decreases, and when the temperature sensor deteriorates over time, accurate correction cannot be performed.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention is effective even when the ambient temperature changes.
Can output stable pressure detection signal without temperature dependence,
An object of the present invention is to provide a pressure sensor which can improve durability and reliability, can be formed in a compact size as a whole, and can increase the degree of freedom in mounting.

[0019]

In order to solve the above-mentioned problems, the present invention provides an annular casing whose inner peripheral side serves as an insertion hole for a fastening member and which is fastened to the pressure source side by the fastening member. The present invention is applied to a pressure sensor including an annular piezoelectric body that is provided in the casing and that outputs a voltage signal by receiving the pressure from the pressure generation source via the casing.

The features of the configuration adopted by the invention of claim 1 are that the piezoelectric body receives a pressure to receive the pressure and outputs a voltage signal, and a temperature that outputs a voltage signal according to the ambient temperature. This is because the compensator is provided.

With this configuration, the pressure receiving section generates a voltage signal due to the pressure from the pressure generating source and the voltage signal due to the temperature change of the piezoelectric body, and the temperature compensating section generates only the voltage signal due to the temperature change of the piezoelectric body. Therefore, by canceling the voltage signal from the temperature compensator from the total voltage signal generated from the pressure receiver, only the voltage signal corresponding to the pressure can be extracted.

Further, a feature of the constitution adopted by the invention of claim 2 is that the pressure receiving portion is constituted by a plurality of convex portions formed at a constant interval in the circumferential direction of the piezoelectric body, and the temperature compensating portion is It is configured by a plurality of concave portions formed between the convex portions and formed in the piezoelectric body.

With this structure, the temperature compensator can be provided close to the pressure receiver, and the temperatures of the pressure receiver and the temperature compensator can be equalized, so that accurate temperature correction can be performed. Further, even when the temperature distribution is generated in the piezoelectric body, since the pressure receiving portion and the temperature compensating portion are provided in a dispersed manner, the temperature can be compensated without being affected by the temperature distribution.

Further, the feature of the constitution adopted by the invention of claim 3 is that each convex portion and each concave portion of the piezoelectric body are formed such that the electrode areas for outputting the respective voltage signals are equal to each other. Especially.

As a result, since the voltage signals due to the temperature changes generated in the respective convex portions and the respective concave portions can be equalized, the voltage signals due to the pressure and the temperature changes generated in the respective convex portions cancel out the voltage signals of the respective concave portions due to the temperature change. Therefore, accurate temperature compensation can be performed.

Still further, the feature of the structure adopted by the invention of claim 4 is that the convex portions and the concave portions of the piezoelectric body are formed such that the directions of the polarization axes are opposite to each other, and The convex portion and each concave portion are electrically connected in parallel.

With this configuration, it is not necessary to perform an external calculation for canceling the voltage signal generated in each concave portion from the voltage signal generated in each convex portion, and the convex portion and each concave portion can be used. Since it is not necessary to draw out the signal lines separately,
It is possible to reduce the number of high impedance signal line leads that are easily affected by electrical noise.

[0028]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in the embodiment (hereinafter, referred to as an example) of the present invention, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

1 and 2 show a first embodiment of the present invention.

In the figure, reference numeral 21 denotes a pressure sensor used in this embodiment. The pressure sensor 21 is substantially the same as the pressure sensor 5 described in the prior art, and the casing 22 and the piezoelectric body 2 are provided.
3, a lead plate 31, an upper plate 32, a lower plate 33, etc. are generally configured in a substantially annular shape.

Reference numeral 22 denotes a casing which constitutes the main body of the pressure sensor 21, and the casing 22 is formed of a thin metal plate or the like as an annular body having a substantially square cross section, and the ignition plug 4 is inserted into the inner peripheral side thereof. An insertion hole 22A is provided. Further, inside the casing 22, together with the piezoelectric body 23, a plate portion 31 of a lead plate 31 described later is provided.
A, the upper plate 32, the lower plate 33, etc. are accommodated.

Reference numeral 23 denotes a piezoelectric body located inside the casing 22 and disposed on the plate portion 31A of the lead plate 31, and the piezoelectric body 23 is made of a piezoelectric material such as lead titanate as shown in FIG. It is formed in a ring shape.

Here, the piezoelectric body 23 has six convex portions 24, 24, ... Which are pressure-receiving portions protruding in the thickness direction thereof, and a temperature between the convex portions 24 and having a small thickness dimension. Six concave portions 25, 25, ... Which serve as compensating portions are provided, and the convex portions 24 and the concave portions 25 are arranged alternately at equal intervals in the circumferential direction of the piezoelectric body 23. . Further, the area of the projecting end surface of each convex portion 24 and the area of the upper end surface of each concave portion 25 are formed to be the same area. Each convex portion 24 has its polarization axis in the direction P1, while each concave portion 25 has The polarization is performed so that the polarization axis is in the direction P2.

Then, each convex portion 24 is sandwiched between the upper plate 32 and the lower plate 33 via the plate portion 31A of the lead plate 31, and receives the initial load by the ignition plug 4 serving as a fastening member. On the other hand, each recess 25 has a space S (see FIG. 1) between it and the upper plate 32, so that the load is not applied.

26, 26, ... Denote first earth side electrodes provided on the projecting end faces of the respective convex portions 24, and 27, 27, ... Depict second earth side electrodes provided on the upper side end faces of the respective concave portions 25. As shown, the first ground electrodes 26 have the same surface area as the second ground electrodes 27. In addition, a conductive paste 28, which will be described later, is provided between the ground-side electrodes 26 and 27.
Is electrically connected to each other, and each ground electrode 26 is connected to an upper plate 32, which will be described later, in an abutting state and grounded to the outside.

Reference numeral 28 denotes a conductive paste applied between the ground-side electrodes 26 and 27, and the conductive paste 28 connects the ground-side electrodes 26 and 27 to each other.

Denoted by 29, 29, ... are output side electrodes provided on the lower surface side of each convex portion 24, and each output side electrode 29 is connected to the plate portion 31A of the lead plate 31 in a contacting state, and the piezoelectric body is formed. A voltage signal corresponding to the load applied to the wire 23 is output to the lead plate 31 described later.

Reference numerals 30, 30, ... Show the output side electrodes provided on the lower surface side of the respective recesses 25. The output side electrodes 30 contact the plate portion 31A of the lead plate 31 like the output side electrodes 29. The output-side electrodes 30 are connected in contact with each other and output a voltage signal according to the temperature of the piezoelectric body 23 to a lead plate 31 described later.

Numeral 31 designates a protective tube 7 from the inside of the casing 6.
The lead plate 31 is provided over the plate portion 31. The lead plate 31 is located on the lower surface side of the piezoelectric body 23 in the casing 22 and is formed as an annular flat plate, as in the prior art, and the plate portion 31A. The plate portion 31A is generally composed of a lead portion (not shown) extending from 31A into the protection tube 7.
Is insulated from the lower plate 33.

Reference numeral 32 denotes an annular upper plate made of a conductive metal material so as to cover the upper surface of the piezoelectric body 23. The upper plate 32 is located inside the casing 22 and is located on each convex portion 24. It is arranged in contact with the ground side electrode 26 with a conductive paste 28 in between, and each recess 2
A space portion S is formed between the upper end surface of 5 and the upper end surface.

33 is the plate portion 3 of the lead plate 31.
1A shows an annular lower plate 33 disposed on the lower surface side of 1A via an insulating sheet 34, and the lower plate 33, together with the upper plate 32, holds the lead plate 31, the piezoelectric body 23 and the like inside the casing 22. , It is clamped from below, and the pressure and the vibration from the outside are uniformly applied to the entire piezoelectric body 23.

34 is the plate portion 3 of the lead plate 31.
An insulating sheet 35, which is provided between 1A and the lower plate 33 and insulates the two from each other, is located on the inner peripheral side in the casing 22, and includes the casing 22, the upper plate 32, and the plate portion 31A of the lead plate 31. The insulating ring which insulates between is shown.

The pressure sensor 21 according to this embodiment has the above-mentioned structure, and its operation will be described below.

The pressure sensor 21 is a conventional pressure sensor 5.
Similarly to the above, it is fixed to the cylinder head 1 by the ignition plug 4, and a predetermined initial load is applied to the piezoelectric body 23 by the ignition plug 4. When the ignition plug 4 is pressed toward the side opposite to the combustion chamber 2 by the combustion pressure of the engine, the pressure sensor 21 causes the load or pressure received by each convex portion 24 of the piezoelectric body 23. Change. for that reason,
A voltage signal proportional to the changed load and corresponding to the combustion pressure is output from each convex portion 24.

On the other hand, since each recess 25 has a space S between the upper end surface and the upper plate 32 and the load is not applied, each recess 25 generates a voltage signal corresponding to the combustion pressure. There is nothing to do.

However, when the heat from the combustion chamber 2 is transmitted to the pressure sensor 21 and the temperature of the piezoelectric body 23 changes, the voltage signal due to the temperature change proportional to each electrode area is applied to each of the convex portions 24 and the concave portions 25. Occurs. At this time, the direction P1 of the polarization axis of each convex portion 24 is opposite to the direction P2 of the polarization axis of each concave portion 25, and each convex portion 24 and each concave portion 25 is electrically connected by the conductive paste 28 or the like. Since they are connected in parallel, the voltage signals due to the temperature change are canceled. Then, only the voltage signal corresponding to the combustion pressure is output from the lead plate 31.

Thus, according to this embodiment, the piezoelectric body 23
Is provided with each convex portion 24 as a pressure receiving portion for receiving a pressure and each concave portion 25 as a temperature compensating portion for outputting a voltage signal according to the ambient temperature, and each convex portion 24 and each concave portion 25 is provided.
Since the and are alternately arranged in the circumferential direction at regular intervals, a voltage signal due to the pressure of the combustion chamber 2 and a voltage signal due to the temperature change are generated at each convex portion 24, while each concave portion 2 is provided.
At 5, a voltage signal is generated due to a temperature change. Accordingly, the voltage signal due to the temperature change generated in each convex portion 24 can be canceled by the voltage signal of each concave portion 25.

Further, since each convex portion 24 and each concave portion 25 are provided close to each other in the circumferential direction of the piezoelectric body 23, the temperature of each convex portion 24 and each concave portion 25 can be made equal, and accurate temperature compensation is possible. Become. Further, even when the temperature distribution is generated in the piezoelectric body, since the respective convex portions 24 and the respective concave portions 25 are provided evenly distributed in the circumferential direction, the temperature can be compensated without being affected by the temperature distribution.

Further, since the respective convex portions 24 and the respective concave portions 25 are configured so that their electrode areas are equal to each other, each convex portion 2
4 and each concave portion 25 can be made equal in voltage signal (charge amount) due to temperature change, and the voltage signal due to temperature change generated in each convex portion 24 can be removed more accurately.

Furthermore, the direction P of the polarization axis of each convex portion 24
Since 1 and the direction P2 of the polarization axis of each recess 25 are set in opposite directions and are electrically connected in parallel, the voltage signals generated in each projection 24 and each recess 25 are reversed. The piezoelectric body 23 as a whole can reliably cancel the voltage signal corresponding to the temperature change, and can prevent the lead plate 31 from outputting the voltage signal due to the temperature change.

As a result, it is not necessary to cancel the voltage signals generated in the convex portions 24 and the concave portions 25 by a special external calculation, and the signal lines are separately drawn from the convex portions 24 and the concave portions 25. Since it is not necessary and the number of high impedance signal lines can be reduced, it is possible to prevent electrical noise or the like from being added to the detected voltage signal, and the pressure sensor 21
Can be configured simply and compactly.

Therefore, in this embodiment, even if the ambient temperature changes, the voltage signals due to the temperature changes are canceled by the convex portions 24 and the concave portions 25, and only the voltage signal proportional to the pressure can be output from the lead plate 31. A stable pressure detection signal having no temperature dependence can be output, and the combustion pressure in the combustion chamber 2 can be detected with high accuracy. Further, since a temperature sensor or the like as a separate member is not necessary, the durability and reliability of the pressure sensor 21 as a whole can be improved, and the entire structure can be simply and compactly formed, and the degree of freedom in mounting can be increased. .

Further, since the piezoelectric body 23 including the convex portions 24 and the concave portions 25 can be replaced with the piezoelectric body 8 according to the conventional technique, the casing 22 and the lead plate 3 are formed.
1, the upper plate 32, the lower plate 33, etc. can be used as common parts with the conventional technology (current product),
The piezoelectric body 23 can be processed without special processing on these members.
It is possible to provide a pressure sensor that can easily perform temperature compensation simply by replacing the pressure sensor.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do. However, the feature of this embodiment resides in that the piezoelectric body 41 is composed of two convex portions 42 and two concave portions 43. Here, the piezoelectric body 41 is formed in an annular shape from a piezoelectric material such as lead titanate like the piezoelectric body 23 according to the first embodiment, and the piezoelectric body 41 has convex portions protruding in the thickness direction. Four
While the two are provided at equal intervals in the circumferential direction, each convex portion 42
Each recess 43 having a small thickness dimension is provided therebetween.
Ground electrodes 44 and 45 having the same area are provided on the upper surfaces of the convex portions 42 and the concave portions 43, respectively.
The polarization is applied so that the direction P1 of the polarization axis of each convex portion 42 and the direction P2 of the polarization axis of each concave portion 43 are opposite to each other.
Further, output electrodes 46 and 47 are provided on the lower surface sides of the respective convex portions 42 and the respective concave portions 43.

Thus, in this embodiment having such a structure, it is possible to obtain substantially the same effects as the first embodiment, and in particular, in this embodiment, each convex portion 42 serving as a pressure receiving portion is obtained.
Since it is possible to reduce the number of the concave portions 43 serving as the temperature compensating portion, it is possible to simplify the formation of the piezoelectric body 41 as a whole,
The forming process and the like can be simplified.

In each of the above-mentioned embodiments, each convex portion 24 (4
Although the polarization axis of 2) is set to the direction P1 and the polarization axis of each recess 25 (43) is set to the direction P2, the present invention is not limited to this, and the polarization axis of each projection 24 (42) is set to the direction P1. On P2,
Polarization may be performed so that the polarization axis of each recess 25 (43) is in the direction P1.

In each of the above embodiments, the case where the pressure sensor is used as the combustion pressure sensor of the engine has been described as an example. However, the present invention is not limited to this, and gas such as air, industrial gas, or the like can be used. It can also be applied to a pressure sensor that detects the pressure of a liquid such as fuel or water. On the other hand, it may be used for a knocking sensor that detects knocking of a vehicle.

[0058]

As described in detail above, according to the first aspect of the invention, the pressure receiving portion that receives the pressure of the piezoelectric body and outputs the voltage signal, and the temperature compensation that outputs the voltage signal according to the ambient temperature. Since it is composed of the section, the pressure receiving section generates a voltage signal due to the pressure from the pressure generation source and the voltage signal due to the temperature change of the piezoelectric body, and the temperature compensating section can generate only the voltage signal due to the temperature change of the piezoelectric body, By canceling the voltage signal from the temperature compensating unit from the total voltage signal generated in the pressure receiving unit, only the voltage signal corresponding to the pressure can be stably extracted. Therefore, a temperature sensor or the like as a separate member is not required, durability and reliability can be improved, and the entire structure can be made compact, so that the degree of freedom in mounting can be increased.

Further, in the invention according to claim 2, the pressure receiving portion is constituted by a plurality of convex portions formed at a constant interval in the circumferential direction of the piezoelectric body, and the temperature compensating portion is located between the respective convex portions. Since it is composed of a plurality of recesses formed in the piezoelectric body,
The temperature compensating portion can be provided in the vicinity of the pressure receiving portion in the circumferential direction of the piezoelectric body, and even when the temperature distribution is generated in the piezoelectric body, accurate temperature compensation can be performed without being affected by the temperature distribution. .

Further, according to the invention described in claim 3, since each convex portion and each concave portion of the piezoelectric body are formed so that the electrode areas for outputting each voltage signal are equal to each other, It is possible to equalize the voltage signals due to the temperature change generated in each concave portion, and to cancel the voltage signal due to the temperature change in each concave portion from the voltage signal generated in each convex portion and the voltage signal due to the temperature change, thereby enabling accurate temperature compensation.

Furthermore, in the invention described in claim 4,
Since each convex portion and each concave portion of the piezoelectric body are formed so that the directions of the polarization axes are opposite to each other, and the convex portion and each concave portion are electrically connected in parallel, It is not necessary to separately lead out the signal lines from the portion and the respective concave portions, and it is possible to reduce the lead-out of the high-impedance signal lines that are easily affected by electrical noise. In addition, the entire pressure sensor can be formed compactly. Furthermore, it is possible to provide a pressure sensor that can easily perform temperature compensation simply by replacing the piezoelectric body.

[Brief description of the drawings]

FIG. 1 is an enlarged half sectional view showing a pressure sensor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a piezoelectric body and the like in FIG.

FIG. 3 is a perspective view showing a piezoelectric body and the like of a pressure sensor according to a second embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing a cylinder head, a spark plug, a pressure sensor and the like according to a conventional technique.

5 is a half cross-sectional view showing the pressure sensor in FIG. 4 in an enlarged manner.

6 is a perspective view showing a piezoelectric body and the like in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Combustion chamber (pressure generation source) 4 Spark plug (fastening member) 21 Pressure sensor (pressure sensor) 22 Casing 22A Insertion hole 23,41 Piezoelectric body 24,42 Convex part (pressure receiving part) 25,43 Recessed part ( Temperature compensation part) 26, 27, 44, 45 Ground side electrode 29, 30, 46, 47 Output side electrode 28 Conductive paste S Space part

Claims (4)

[Claims] 1. An annular casing, the inner peripheral side of which serves as an insertion hole for a fastening member and which is fastened to the pressure generation source side by the fastening member, and the pressure generation provided through the casing. In a pressure sensor including an annular piezoelectric body that outputs a voltage signal by receiving a pressure from a source, the piezoelectric body includes a pressure receiving portion that receives the pressure and outputs a voltage signal, and an ambient temperature. And a temperature compensating section for outputting a voltage signal. 2. The pressure receiving portion is composed of a plurality of convex portions formed at regular intervals in the circumferential direction of the piezoelectric body, and the temperature compensating portion is formed between the convex portions and is formed on the piezoelectric body. The pressure sensor according to claim 1, wherein the pressure sensor is formed by a plurality of recessed portions. 3. The pressure sensor according to claim 2, wherein the convex portions and the concave portions of the piezoelectric body are formed such that the electrode areas for outputting the voltage signals are equal to each other. 4. The structure in which the respective convex portions and the respective concave portions of the piezoelectric body are formed such that the directions of the polarization axes are opposite to each other, and the respective convex portions and the respective concave portions are electrically connected in parallel. The pressure sensor according to claim 2 or 3, wherein