JPH0619068Y2 - Pressure sensor for high temperature fluids - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a pressure sensor, particularly a pressure sensor used for measuring the pressure of a high temperature fluid.

[Prior Art] Pressure sensors are widely used in various fields to measure the pressure of fluid such as gas or liquid, and in recent years, in particular, they are often used under extremely severe operating environments of high temperature and high pressure. . Therefore, the sensor used for measuring the pressure of such a high temperature fluid is required to have an ability to accurately measure the pressure without being affected by the surrounding environment, particularly the temperature thereof.

For example, when such a pressure sensor is used as a combustion pressure sensor for an internal combustion engine, it is required to have the ability to accurately measure the pressure for a long time without being affected by the combustion gas having a temperature of 1,000 ° C or higher. .

FIG. 2 shows an example of a conventional combustion pressure sensor. This combustion pressure sensor uses the pressure P of the combustion gas acting on the surface of the diaphragm portion 10 as a compression force W via the heat insulator 12. Transmitted to the force conversion element 14,
The pressure P of the combustion gas was measured based on the electric signal output from the.

However, when trying to measure the pressure of the combustion gas having a temperature higher than 1000 ° C., the heat insulator 12 provided between the diaphragm portion 10 and the force conversion element 14 alone is used to heat the heat transmitted to the force conversion element 14. Can not be sufficiently shielded,
The performance of the force conversion element 14 itself deteriorates.

Therefore, conventionally, the block portion 16 is integrally provided on the front surface side of the diaphragm portion 10, and the diaphragm portion 10 is
By absorbing the heat of the combustion gas that has come in the vicinity, it is possible to suppress the temperature rise of the diaphragm portion 10 itself and prevent the heat from being transferred to the force conversion element 14 even when the pressure of the high-temperature and high-pressure combustion gas is measured. It had been.

[Problems to be Solved by the Invention] However, conventionally, the diaphragm portion 10 and the block portion 16
Since and were integrally molded using a press die, there were problems described in detail below.

First Problem When the diaphragm portion 10 and the block portion 16 are integrally formed as in the conventional case, a gap 20 for partitioning the diaphragm portion 10 and the block portion 16 must be formed by cutting or the like in a subsequent step, and the pressure sensor There was a problem that the production efficiency was poor.

Further, when the gap 20 is formed by cutting or the like as in the conventional case, the gap 20 cannot be made smaller than the width of the cutting blade. Therefore, the volume of the combustion gas that enters the gap 20 and directly acts on the surface of the diaphragm portion 10 can be reduced, and the temperature rise of the diaphragm portion 10 cannot be effectively suppressed, and the temperature rise of the diaphragm portion 10 cannot be suppressed. Due to this, there was a problem that creep and the like could not be reduced.

Second Problem Further, in such a combustion pressure sensor, it is preferable that the diaphragm portion 10 is formed of a material having a good spring characteristic at a high temperature, and the block portion 16 has a specific heat,
It is preferable to use a material having a large thermal conductivity.

However, in the conventional sensor, since the diaphragm portion 10 and the block portion 16 are integrally formed, it is not possible to form them using different materials.

For this reason, for example, when the diaphragm portion 10 is required to have spring characteristics at high temperature, the specific heat and the thermal conductivity of the block portion 16 are lowered, and it is necessary to increase the volume of the block portion 16 itself. However, the block portion 16 is not included in the diaphragm portion 1.
Since it is integrally fixed near the center of 0, block 1
When the mass of 6 is increased, the added mass of the diaphragm portion 10 also increases, and the natural frequency of the diaphragm portion 10 decreases. Therefore, when the combustion pressure sensor is attached to a portion of the engine or the like where vibration is large, there is a problem that the pressure detection accuracy is significantly reduced.

Further, when the volume of the block portion 16 is reduced, the temperature of the diaphragm portion 10 rises, which causes a problem that the spring characteristic of the diaphragm portion 10 becomes depressed.

[Object of the Invention] The present invention has been made in view of the above-described conventional problems, and an object thereof is to solve the above-mentioned conventional problems and to provide a high-pressure fluid pressure capable of accurately measuring a high-temperature fluid pressure for a long time. To provide a sensor.

[Means for Solving the Problems] In order to achieve the above object, the present invention transmits the pressure of a high-temperature fluid acting on the surface of a diaphragm portion as a compressive force to a force converting element and outputs the force converting element. In a pressure sensor that measures the pressure of a high-temperature fluid based on an electric signal that is provided, a heat radiation block portion formed using a material having a higher thermal conductivity than the diaphragm portion, and a heat radiation block portion provided on the back surface side of the heat radiation block portion. A bonding projection and a bonding projection provided near the center of the surface of the diaphragm section, wherein the diaphragm section is formed using a material having good spring characteristics at high temperature, and the bonding projection Is joined and fixed to a joining recess of the heat dissipation block, and the heat dissipation block is formed so as to cover the surface of the diaphragm part in an umbrella shape with a predetermined gap. And

[Operation] The present invention is configured as described above, and its operation will be described below.

In the pressure sensor of the present invention, the block portion and the diaphragm portion are formed separately.

A protrusion for joining is formed near the center of the surface of the diaphragm for the purpose of aligning with the block and not transmitting distortion during joining directly to the thin plate of the diaphragm.

In addition, a concave portion for joining is provided in the central portion of the block portion for the purpose of alignment with the diaphragm portion, and the other portion of the block portion is formed so as to cover the surface of the diaphragm portion like an umbrella. .

Then, the joining concave portion of the block portion is fitted into the joining convex portion provided at the center of the diaphragm portion and, for example, projection welding is performed. As a result, the block portion is attached and fixed to the surface of the diaphragm portion.

Therefore, according to the present invention, if the joining concave portion of the block portion is formed so as not to be expanded inward and the joining convex portion of the diaphragm portion is formed so as not to be expanded first, the block portion and the diaphragm are formed. Since the portion can be easily formed by a press die, the mass productivity of the pressure sensor can be improved and the cost can be reduced.

Also, in the present invention, the gap between the block portion and the diaphragm portion is the convex portion for joining the diaphragm portion,
It is possible to easily narrow the size by adjusting the size of the joining concave portion of the block portion, and it is possible to greatly reduce the volume of the combustion gas entering this gap as compared with the conventional pressure sensor.

Therefore, the amount of heat directly transferred from the combustion gas to the diaphragm portion is greatly reduced, and as a result, the temperature rise of the diaphragm portion can be effectively suppressed, and further, the creep of the diaphragm portion and the like can be reduced.

Further, in the present invention, the block portion attached to the central portion of the surface of the diaphragm portion is formed for the purpose of absorbing the heat of the combustion gas coming near the diaphragm portion and further absorbing the heat received by the diaphragm portion itself. . For this purpose, the temperature of the block side must be lower than that of the diaphragm side.

Therefore, the block portion is required to have characteristics that it has a large specific heat and a large thermal conductivity. In addition, as described above, it is not preferable to form the block portion so large that it does not reduce the natural frequency of the diaphragm portion. In particular, when the compression force sensor of the present invention is used as, for example, a combustion pressure sensor, if the weight of the block part increases and the natural frequency of the diaphragm part decreases, the measurable frequency range becomes narrower, especially in the engine etc. If it is attached to a place where the vibration of the above is large, it becomes difficult to detect a knock signal or the like.

Therefore, the block portion is required to have a smaller specific weight with respect to the diaphragm portion, and the smaller the specific weight, the more improved the detection characteristic.

In order to solve such a problem, in the present invention, the diaphragm part and the block part are formed separately, and the diaphragm part is made of a material having excellent spring characteristics at high temperature (for example, SUS4).
30, material such as Inconel X720),
The block portion is formed using a material having a high thermal conductivity (for example, an Al-based alloy).

For example, when the block portion is formed using an Al-based alloy, the mass thereof is about 1/3 of that of the case where an Fe-based or Ni-based alloy is used. This means that when an Al-based alloy is used, the responsiveness and acceleration sensitivity are almost the same and the heat capacity is tripled even when the volume is three times that of the Fe-based and Ni-based alloys. It means that you can do it.

Further, when the block portion is formed by using an Al-based alloy, the specific heat is about twice and the thermal conductivity is about three times that when using the Fe, Ni-based alloy.

As described above, according to the present invention, the diaphragm portion has good high temperature spring characteristics, such as SUS430 and Inconel X72.
It is formed by using a material such as 0, and the block portion is made of, for example, Al.
By using a system alloy, the specific heat of the block part can be doubled, the thermal conductivity can be tripled, and the specific weight can be set to about 1/3, and the block part of the same volume can be integrated with the diaphragm part. You can expect about 18 times the effect compared with the case made with.

[Advantages of the Invention] As described above, according to the present invention, the diaphragm portion and the block portion are separately formed, and are joined later, so that the mass production of the pressure sensor is increased and the sensor itself. Has the effect that it can be manufactured at low cost.

Further, according to the present invention, the gap between the diaphragm portion and the block portion can be sufficiently narrowed,
The block portion quickly absorbs the heat of the combustion gas coming near the diaphragm portion, and the temperature rise of the diaphragm portion can be effectively suppressed.

Further, according to the present invention, the diaphragm portion can be formed by using a material having good spring characteristics at a high temperature, and the block portion can be formed by using a material having good thermal conductivity. There is an effect that the temperature rise of the diaphragm portion can be suppressed more effectively without damaging the temperature.

[Embodiment] Next, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a preferred embodiment when the present invention is applied to a combustion pressure sensor.

In the combustion pressure sensor of the embodiment, the flange portion 11a of the diaphragm portion 10 is fitted into the tip opening of the sensor case 30 formed in a substantially cylindrical shape, and the fitting is performed so that the combustion gas does not enter the inside of the sensor case 30. Projection welding is performed along the entire circumference of the recess.

The feature of the present invention is that the diaphragm portion 10 and the block portion 16 are separately formed, and the thin plate portion 1 of the diaphragm portion 10 is formed.
1b is joined to a joining convex portion 10a provided near the central portion of the surface portion 1b, and a joining concave portion 16a provided at the central portion of the block portion 16 is joined to the block portion 16 at the central portion of the surface of the diaphragm portion 10.
Is attached and fixed.

In the embodiment, the joining convex portion 10a is formed so that the tip side does not spread forward, and the joining concave portion 16a is adjusted to the size of the joining convex portion 10a so that the inner side does not spread inward. Is formed.

Further, when the block portion 16 is bonded and fixed to the surface of the diaphragm portion 10 in this manner, the surface of the diaphragm portion 10 is covered by the block portion 16 through the gap 20 almost entirely like an umbrella. At this time, the size of the gap 20 can be arbitrarily adjusted by the dimensions of the convex portion 10a and the concave portion 16a, and is formed to be substantially zero in this embodiment.

Further, in the present invention, the block portion 16 is preferably made of a material having a large specific heat and good thermal conductivity, and in the embodiment, it is formed of an Al alloy.

Further, in the present invention, the diaphragm portion 10 is preferably made of a material having a good spring characteristic at a high temperature, and in the embodiment, it is made of a metal material such as SUS430 and Inconel X720.

As described above, in this embodiment, since the diaphragm portion 10 and the block portion 16 are formed by using their respective unique materials, the block portion 16 has a specific heat about twice that of the diaphragm portion 10 and a thermal conductivity. Is about 3 times and the specific weight is about ⅓, and an effect of about 18 times can be expected as compared with the case where the block portion 16 having the same volume is integrally formed with the diaphragm portion 10. Therefore, according to the present embodiment, it is possible to effectively suppress the temperature rise without damaging the characteristics of the diaphragm portion 10.

The combustion pressure sensor according to the present embodiment has the diaphragm portion 1
The pressure P of the combustion gas acting from the surface side of 0 is transmitted to the force conversion element 14 fixed inside the sensor case 30 via the thermal insulator 12, and is converted into an electric signal output from the force conversion element 14. On the basis of the pressure P of the combustion gas.

In the present invention, the force conversion element 14 may be any element capable of detecting a compressive force, for example, an element capable of detecting a compressive force by utilizing a piezoresistive effect, or a compressive element utilizing a piezovoltage effect such as a crystal or PZT. An element that detects force may be used.

In the embodiment, the force conversion element 14 has a Si single crystal body 40 formed to have a {110} crystal face as a surface to which a compressive force is applied, and a {11} of the Si single crystal body 40.
Pedestal 42 that is electrostatically bonded to the crystal plane of the 0} plane and uniformly applies the compressive force transmitted through the thermal insulator 12 perpendicularly to the crystal plane, and another crystal plane of the Si single crystal body 40. And a support base 44 for supporting the Si single crystal 40.

The support base 44 is mounted and fixed on a hermetic terminal 46 whose outer periphery is fixed to the inner peripheral surface of the sensor case 30.

In addition, on the crystal plane of the Si single crystal body 40,
A pair of first electrodes (not shown) are provided so as to face each other in a direction of 45 degrees from the 001> direction, and 45 degrees from the <110> direction.
A pair of second electrodes (not shown) are provided facing each other in the direction of the angle. Then, one of the first and second electrodes is used as an output electrode and the other is used as an input electrode.

Further, the hermetic terminal 46 is provided with four lead pins 48 corresponding to the input / output electrodes, and one end sides of these four lead pins 48 are respectively provided with corresponding input / output via a gold wire 50. It is electrically connected to the electrodes. The other end of each of these lead pins 48 is connected to a lead wire 52, which is connected to the sensor case 3.
It is drawn out from the other end side of 0.

In the sensor of the embodiment, in order to prevent the lead wire 52 from coming off, the caulking portion 32 for the lead wire is provided on the other end side, and the pulling force applied to the lead wire 52 is connected to the lead pin 48. It is formed so as not to act on.
Further, the caulking portion 32 of the sensor case 30 is formed so as to be covered with a case cover 34.

Further, in the combustion pressure sensor of the embodiment, a screw groove 36 for mounting and fixing is provided on the outer peripheral portion on one end side of the sensor case 30, and the screw groove 36 is provided on the inner peripheral portion of a predetermined mounting hole (not shown). It is formed so that it can be easily attached to a desired position by being screwed into the provided thread groove.

The present embodiment has the above configuration, and its operation will be described below.

When the combustion pressure is to be measured using the sensor of the embodiment, first, a predetermined current is passed through the input electrode of the Si single crystal body 40, and the diaphragm portion 10 in this state.
Combustion gas is made to act on the surface side of.

At this time, the pressure P of the combustion gas acting on the surface of the diaphragm portion 10 acts perpendicularly to the crystal plane of the (110) plane of the Si single crystal body 40 via the thermal insulator 12 and the pedestal 42, and S
A voltage proportional to the pressure P is output from the output electrode of the i single crystal body 40 by utilizing the piezoresistive effect. Then, the measured voltage is output to the outside via the lead wire 52.

By the way, when the pressure of the combustion gas whose temperature exceeds 1000 ° C. is measured as in the embodiment, the diaphragm portion 1 is used.
The temperature rise of the force conversion element 14 cannot be sufficiently suppressed only by providing the thermal insulator 12 between 0 and the force conversion element 14, and the characteristics of the force conversion element 14 deteriorate as they are. .

Therefore, in the force conversion element of the embodiment, the diaphragm portion 10
The block portion 16 is attached and fixed to the center of the surface of the diaphragm to suppress the temperature rise of the diaphragm portion 10.

In this embodiment, the block portion 16 is formed separately from the diaphragm portion 10, and the joint recess 16a provided in the central portion of the block portion 16 is fitted with the joint convex portion 10a provided in the center portion of the surface of the diaphragm portion 10. In this state, the block portion 16 is attached and fixed to the central portion of the surface of the diaphragm portion 10.

Therefore, the gap 20 between the block portion 16 and the diaphragm portion 10 is set to the protrusion 10a for joining and the recess 16 for joining.
It can be made approximately zero by adjusting the size of a. Therefore, the volume of the combustion gas that directly acts on the surface of the diaphragm portion 10 through the gap 20 is significantly reduced, and the temperature rise of the diaphragm portion 10 can be effectively suppressed.

When the gap 20 becomes smaller, the heat directly transferred from the combustion gas to the diaphragm portion 10 is mainly in the peripheral portion (flange portion 11a) of the diaphragm portion 10, but the heat in this portion is connected to the sensor case 30 to mount the sensor. The temperature rise in the peripheral portion of the diaphragm portion 10 is suppressed.

Further, according to the present embodiment, the block portion 16 is formed by using an Al alloy having high specific heat and high thermal conductivity. Therefore,
The heat in the vicinity of the center of the surface of the diaphragm portion 10 (the center of the thin plate portion 11b) has a larger specific heat than that of the diaphragm portion 10,
It escapes to the block part 16 side with good thermal conductivity by heat conduction,
It is also possible to suppress a temperature rise near the central portion of the surface of the diaphragm portion 10.

As described above, the combustion pressure sensor of the present embodiment can effectively suppress the temperature rise of the diaphragm portion 10 on which the high temperature combustion gas acts, so that the temperature rise of the force conversion element 14 in the sensor case 30 is suppressed. It becomes possible to accurately measure small, high temperature, high pressure combustion gas for a long time.

Further, in the present embodiment, the diaphragm portion 10
The joining convex portion 10a is formed so as not to spread forward, and the joining concave portion 16a of the block portion 16 is formed so as not to spread inside. Therefore, the diaphragm portion 10 and the block portion 16 can be easily manufactured by press molding or the like, and moreover, the joining convex portion 10a and the joining concave portion 16a can be joined only by joining them. The manufacturing process is simpler than that of the conventional sensor, and the mass productivity can be improved.

The present invention is not limited to the above embodiment,
Various modifications can be made within the scope of the present invention.

For example, in the above embodiment, the case where the pressure sensor of the present invention is used as a combustion pressure sensor has been described as an example.
The present invention is not limited to this, and can be widely used as a pressure sensor for various high temperature fluids other than this.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a preferred example when the pressure sensor according to the present invention is formed as a combustion pressure sensor, and FIG. 2 is an explanatory view of a conventional combustion pressure sensor. DESCRIPTION OF SYMBOLS 10 ... Diaphragm part 10a ... Convex part for joining 14 ... Force conversion element 16 ... Block part 16a ... Recessed part for joining

Continuation of the front page (56) Bibliographic references Sho 63-27845 (JP, U) US Patent 3857287 (US, A)

Claims (2)

[Scope of utility model registration request] 1. A pressure sensor for transmitting a pressure of a high temperature fluid acting on a surface of a diaphragm portion to a force conversion element as a compression force and measuring the pressure of the high temperature fluid based on an electric signal output from the force conversion element, A heat dissipation block part formed of a material having a heat conductivity higher than that of the diaphragm part, a bonding recess provided on the back surface side of the heat dissipation block part, and a vicinity of the center part of the front surface of the diaphragm part. A joint convex portion; and the diaphragm portion is formed of a material having good spring characteristics at a high temperature, and the joint convex portion is jointly fixed to a joint concave portion of the heat dissipation block portion, The pressure sensor for high-temperature fluid, wherein the block portion is formed so as to cover the surface of the diaphragm portion with a predetermined gap in an umbrella shape. 2. The pressure sensor for a high temperature fluid according to claim 1, wherein the pressure of a thermally burned gas is measured as the high temperature fluid.