JPS5926892B2 - absolute pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention detects the difference between the pressure to be measured and the vacuum, that is, the absolute pressure, by differentially extracting the displacement of the pressure receiving plate to which the pressure to be measured is applied. Regarding sensors.

If the displacement of the pressure receiving plate is differentially detected as an electric signal by disposing detection sections on both sides of the pressure receiving plate, even a small displacement can be detected as a relatively large signal.

A so-called differential pressure sensor is well known as a sensor that differentially detects the displacement of the pressure receiving plate by disposing detection sections on both sides of the pressure receiving plate in order to detect the pressure difference applied to both sides of the pressure receiving plate.

Absolute pressure can be detected by applying a vacuum pressure to one pressure receiving plate in a differential pressure sensor and applying a measured pressure to the other.

However, in this case, since the detection part is placed on the vacuum pressure side, there is a risk that the degree of vacuum will decrease, and the detection part must be designed so that it can be replaced or repaired and inspected, and the structure must maintain a sufficient degree of vacuum. was difficult.

From this point of view, conventional absolute pressure sensors that differentially detect the displacement of a pressure receiving plate have not been put to practical use.

In other words, the conventional absolute pressure sensor detects the displacement of the pressure receiving plate from only one side, and cannot extract the displacement as a large signal.

The purpose of the present invention is to provide an absolute pressure sensor that can differentially detect the displacement of a pressure receiving plate, that makes it difficult for the degree of vacuum to decrease, and that allows easy replacement and repair/inspection of the detection part. be.

According to this invention, a pressure to be measured is applied inside the body, a pressure receiving plate is arranged inside the body, one end of the vacuum chamber is connected to one surface of the pressure receiving plate, and the other end is fixed to the body.

The vacuum chamber has a cylindrical shape, the axis of which passes through the center of the pressure receiving plate, and the vacuum chamber can expand and contract in a direction perpendicular to the pressure receiving plate.

The space surrounded by the vacuum chamber serves as an auxiliary pressurization chamber, and the pressure to be measured is applied to the inside of the auxiliary pressurization chamber.

A detection section is held by the body in opposition to the pressure receiving plate within this auxiliary pressurizing chamber, and a detection section is also provided on the other surface of the pressure receiving plate to face it.

These rain detection units differentially detect the displacement of the pressure receiving plate as an electric signal.

The pressure to be measured is applied to the entire surface of one side of the pressure receiving plate, but the pressure to be measured is also applied to a part of the other side, so the effective pressure is the difference between the areas where the pressure to be measured is applied on both sides. become a part.

In this way, the detection part is not placed in the vacuum chamber.
Can be placed on both sides of the pressure plate.

Next, an embodiment of the absolute pressure sensor according to the present invention will be described with reference to the drawings.

In the figure, numeral 1 indicates a cylindrical body, and a pressure to be measured is applied within the body 11.

For example, a pressure to be measured inlet 13 is formed on the circumferential surface of one end plate 12 of the body 11, and the inlet 13 communicates with the inside of the body 11 through a branch passage 14 near the inner circumferential wall surface of the body 11.

A pressure receiving plate 15 is disposed at a central portion ζ in the body 11, and the pressure receiving plate 15 is held by the body 11 so as to be able to be displaced perpendicularly to the axis of the body 11.

One side of the body 11 is connected to one end, and the other end is connected to the body 11.
A cylindrical vacuum chamber 16 is provided by connecting the cylinders.

The axis of the vacuum chamber 16 is located on the center of the pressure receiving plate 15, and is made to be able to expand and contract in a direction perpendicular to the pressure receiving plate 15.

For example, one end of the outer bellows 17 is connected to the peripheral edge of the pressure receiving plate 17, and the other end of the outer bellows 17 is fixed to the peripheral edge of the end plate 12.

However, a branch passage 14 is located between the bellows 17 and the peripheral wall of the body 11.

Inner bellows 1 coaxially with outer bellows 17 and inside thereof.
8 are arranged, and both ends of the inner bellows 18 are fixed to the end plate 12 and the pressure receiving plate 15, respectively.

These bellows 17 and 18 are fixed to the end plate 12 and the pressure receiving plate 15 in an airtight manner.
A vacuum chamber 16 is formed by being surrounded by the pressure receiving plate 15 and the pressure receiving plate 15 .

Further, the pressure receiving plate 15 is held through this vacuum chamber 16.

Vacuum intake passage 1 reaching the vacuum chamber 16 from the peripheral surface of the end plate 12
9 is formed through which the inside of the vacuum chamber 16 is maintained at a vacuum.

An auxiliary pressurizing chamber 21 is provided surrounded by the vacuum chamber 16 .

A detection section 22 is held by the body 11 in the auxiliary pressurization chamber 21, facing the pressure receiving plate 15.

In this example, the detection section 22 is taken out to the outside and the auxiliary pressurization chamber 2 is
A stopper 23 is provided to prevent the vacuum chamber 16 from being reduced too much when the inside of the vacuum chamber 16 becomes atmospheric pressure.

For example, a center hole 24 is formed in the end plate 12, and the center hole 24 is formed in the end plate 12.
A cylindrical stopper 23 is fitted into the inside of the cylindrical stopper 4 .

A flange 25 is integrally formed on the outer end of the stopper 23,
This is fixed in contact with the bottom surface of a shallow recess 26 formed on the outer end surface of the end plate 12, for example, with a screw.

The inner end surface of the stopper 23 is close to the pressure receiving plate 15 within a range where the pressure receiving plate 15 can be displaced based on the measured pressure.

A columnar support 27 is inserted into the stopper 23 from its outer end, and the detection section 22 is attached to the inner end of the support 27.

A mounting plate 28 is integrally formed at the outer end of the support body 27, and the mounting plate 28 is in contact with the outer surface of the flange 25 and is fixed thereto, for example, by screws.

The recess 26 of the end plate 12 is covered with a lid 29 if necessary.

A branch passage 30 is formed in the end plate 12G to communicate the pressure to be measured inlet 13 and the auxiliary pressurizing chamber 21, and the pressure to be measured ζ is maintained in the auxiliary pressurizing chamber 21 through the branch passage 30.

Although not shown in the figure, a lead wire connected to the detection part 22 passes through the support body 27 and is led out from the recess 26 through a small hole formed in the peripheral wall thereof.

01J rings 31 and 32 are interposed between the stopper 23, the end plate 12, and the support body 27, respectively, to form the auxiliary pressurizing chamber 21.
and the outside are hermetically sealed off.

The detection unit 3 faces the surface of the pressure receiving plate 15 opposite to the vacuum chamber 16.
3 is placed.

That is, the circular hole 3 formed in the other end plate 34 of the body 11
A cylindrical support body 35 is fitted into the inside of the support body 5 , and the detection section 33 is attached to the inner end of the support body 35 .

A collar portion at the outer end of the support body 35 is screwed to the end plate 34, for example.

An 01J ring 36 is interposed within the end plate 34 and the support body 35 to airtightly isolate the inside and outside of the body.

A cover 37 for covering the support body 35 is attached to the outside of the end plate 34 as required.

In this example, the pressure-receiving plate 15 can be stably supported and its center position can be adjusted, that is, the pressure-receiving plate 15 can be adjusted to the center of the detection sections 22 and 33.

For this reason, the diameter of the inner peripheral surface of the body 11 on the side of the end plate 34 is set as a dog, and a rotary ring 38 is rotatably disposed in contact with the inner peripheral surface of the large diameter portion.

A thread is cut on the inner peripheral surface of the rotating ring 38, and a support ring 39 having a thread on the outer peripheral surface that is threadedly engaged with the thread is provided.

The support body 35 is loosely inserted into the support ring 39.

Both ends of the bellows 49 are fixed to the support ring 39 and the pressure receiving plate 15, respectively.

A common hole 4 is provided in the support ring 39 on the outside of the bellows 41.
2 is formed, through which a further ring 39 and a support 3 are formed.
The pressure to be measured in the body 11 is measured through the interval 5 of the bellows 4.
1, that is, applied to the pressure receiving plate 15.

When the rotation ring 38 is rotated, the support ring 39 screwed therewith moves parallel to the axis, allowing the position of the pressure receiving plate 15 to be adjusted.

When the rotating ring 38 is held down by the end plate 34, an 01J ring 43 is interposed between the two ends.

Various types of detection parts 22 and 33 can be used.For example, the pressure receiving plate 15 is made of a non-magnetic material, ferromagnetic material is protruded from both sides of the center thereof, and coils are attached to the supports 27 and 35, respectively. , the inductance values of these coils are made to vary differentially in response to the displacement of the pressure receiving plate 15.

As described above, according to the absolute pressure sensor according to the present invention, the measured flow pressure applied in the body 11 is detected on both sides of the pressure receiving plate 15. is applied to

The measured flow pressure applied to the difference between the area of the pressure receiving plate 15 inside the bellows 18 and the area of the pressure receiving plate 15 inside the bellows 41 acts as an effective pressure.

The pressure receiving plate 15 is displaced in accordance with this effective pressure, and this displacement is differentially detected by the detection units 22.33.

Since the detection units 22 and 33 are both placed outside the vacuum chamber 16, no parts are placed inside the vacuum chamber 16, and there is no fear that the degree of vacuum inside the vacuum chamber 16 will deteriorate.

Therefore, Il can be determined more accurately.

Further, by removing the support body 27, the detection section 22 can be repaired and inspected, and this can be done independently of the vacuum chamber 16.

When the support body 27 is removed, the pressure receiving plate 15 is held by the stopper 23 to prevent the vacuum chamber 16 from being unnecessarily reduced in size.

[Brief explanation of the drawing]

The figure is a sectional view showing an example of an absolute pressure sensor according to the present invention. 11: Body, 13: Measured pressure inlet, 15: Pressure receiving plate,
16: Vacuum chamber, 17.1B, 41: Bellows, 19: Vacuum chamber outlet, 21: Auxiliary pressurization chamber, 22.33: Detection section,
27, 35: Support body, 23: Stotsuno person 38: Rotating ring, 39: Support ring one

Claims (1)

[Claims] 1 A body to which the pressure to be measured is applied, a pressure receiving plate disposed within the body and held so that it can be displaced in a direction perpendicular to the plate surface, and a pressure receiving plate attached to the body facing one surface of the pressure receiving plate. , a first detection part that obtains an electric signal corresponding to the distance between the pressure receiving plate and the other surface of the pressure receiving plate is connected at one end, the other end is fixed to the body, and the center of the pressure receiving plate coincides with the center of the pressure receiving plate. A cylindrical vacuum chamber having an axis and capable of expanding and contracting in a direction perpendicular to the pressure receiving plate; an auxiliary pressurizing chamber surrounded by the cylindrical vacuum chamber and to which the pressure to be measured is applied; Do not install it on the above body facing the other side.
An absolute pressure sensor comprising a second detection section that obtains an electrical signal corresponding to the distance from the pressure receiving plate.