JPS5930444Y2 - differential pressure detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential pressure detector that continuously measures the pressure difference between two points, which is a process variable.

For example, when trying to measure the flow rate of fluid in a pipe, an orifice plate is installed in the pipe to act as a fluid resistance, the pressure difference upstream and downstream of this resistance is measured, and the flow rate is derived based on a predetermined calculation formula. It will be done.

For this reason, conventional differential pressure detectors generally apply each measurement pressure to two pressure-receiving diaphragms, and prevent the movement of the internal liquid within the body by electrically controlling the strain of the semiconductor diaphragm that partitions the sealed circuit. It is configured so that it can be output as an output.

In such a configuration, the dimensions, strength, material, etc. of the two pressure-receiving diaphragms can be selected appropriately according to the measurement specifications of the process, but even if sufficient consideration is given to this, excessive loads may be inadvertently applied. , the pressure-receiving diaphragm may deform.

If the pressure-receiving diaphragm is deformed, it is difficult to make highly accurate measurements.To prevent this deformation, the gap between each pressure-receiving side of the body and the pressure-receiving diaphragm is set small, and the pressure-receiving side is made to have the same waveform as the pressure-receiving diaphragm. It is known that a pressure receiving diaphragm that has been formed and subjected to excessive pressure can be backed up without being deformed even if it is pressed against a pressure receiving side surface.

However, even if such a configuration is adopted, if the pressure-receiving diaphragm contacts the pressure-receiving side surface within the measurement span, it causes an error, and highly accurate measurement is still difficult.

Therefore, it is necessary to set the gap between the pressure-receiving side surface and the pressure-receiving diaphragm to be somewhat thick, but on the other hand, there is a problem that the semiconductor diaphragm of the sensor may be damaged if excessive pressure is applied.

The present invention has been developed in view of these conventional drawbacks.The pressure receiving diaphragm is formed of a disc-shaped diaphragm and an annular diaphragm, and one of them is applied to the pressure-receiving side of the body main body to apply a force that applies plastic deformation to the semiconductor diaphragm. With an extremely simple configuration in which pressure is applied with the following force and a bypass is provided that opens on the pressure-receiving side of the opposing pressure side for each sealed circuit on the pressure side, excess pressure applied to the pressure-receiving diaphragm is absorbed and damage to the semiconductor diaphragm is prevented. In addition, the present invention provides a differential pressure detector which is designed to improve measurement accuracy.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Fig. 1 is a longitudinal sectional view showing an embodiment of the differential pressure detector according to the present invention, Fig. 2 is an exploded perspective view of the pressure receiving dianoram shown in Fig. 1, and Fig. 3 is the sensor shown in Fig. 1. FIG.

In these figures, the reference numeral 1 denotes a body which is sealed with an internal liquid 2, and a pressure receiving diaphragm 3°4 is located on both left and right sides of the body, that is, on each receiving/extending surface 1atlb, at its periphery. Covers 5 and 6 are fixed to the main body 1 so as to cover the pressure receiving diaphragms 3 and 4, respectively.

The pressure-receiving diaphragms 3 and 4 are formed identically, and each has a disk-shaped diaphragm A formed in a corrugated shape.
and an annular diaphragm B that surrounds the outer periphery of the disc-shaped diaphragm A, and the annular diaphragm B has its own spring behavior, so that the pressure-receiving sides 1a, 1
b are in pressure contact with each other.

In this case, the pressure contact force of the annular diaphragm B is set to be less than the force that causes plastic deformation to the semiconductor diaphragm, which will be described later, in consideration of the safety factor, and each pressure receiving side surface 1a, lb is formed in the same waveform as the pressure receiving diaphragm 3.4. has been done.

Appropriate gaps are provided between the disc-shaped diaphragm A and each pressure-receiving side surface 1a, lb.

In the figure, the pressure axis PL on the upstream side of the orifice from the hole 1 of the cover 5 is guided to the outer surface of the pressure receiving diaphragm 3 on the left side, and the pressure axis PL on the downstream side of the orifice from the hole 8 of the cover 6 is guided on the outer surface of the pressure receiving diaphragm 3 on the right side. is being guided.

Two sealed circuits 9 and 10 are formed in the body 1, and the upper ends of these sealed circuits 9 and 10 are connected to an upper chamber 12 that is provided in the upper part of the body 1 and sealed by a hermetic seal 11. The lower end is connected to each pressure receiving side surface 1a.

It is opened at a portion of 1b facing the disc-shaped diamondorum A.

In addition, the sealed circuits 9 and 10 are provided with bypasses 13 and 14, respectively, which open at portions of the pressure-receiving sides 1b and 1b facing the annular diaphragm B on the opposite pressure side.

The inner liquid 2 is sealed in the upper chamber 12 and a sensor 15 is disposed therein.

As shown in FIG. 3, this sensor 15 consists of a silicon base 16 placed and fixed on the bottom surface 12a of the upper chamber 12, and a cup-shaped semiconductor diaphragm 17 fixed on the silicon base 16 and having a circular top surface. silicon wafer 1
8, and a strain gauge 19 provided by a diffusion method or the like on the strain-generating portion of the semiconductor diaphragm II and connected with a bridge.
Pressure PH is applied to the upper side of the front sub-semiconductor diaphragm 17 via the encapsulation circuit 9, and pressure PL is applied to the lower end via the encapsulation circuit 10 and the through hole 20 of the silicon base 16.

In this configuration, during normal pressure measurement, a differential pressure P H- is applied to the pressure receiving diaphragms 3 and 4 via the inner liquid 2.
A force corresponding to p L is applied to the right in the figure, and this force is guided to the sensor 15 in the upper chamber 12 through the enclosed circuits 9 and 10.

Therefore, the semiconductor diaphragm 17 deforms as shown by the two-dot chain line in response to the differential pressure PH-pL, and this deformation is electrically extracted by the strain gauge 19 and amplified by the angle intensifier 21 shown in FIG. After that, it is displayed on the instrument or transmitted remotely.

Next, for example, if excessive pressure occurs upstream of the orifice,
Since the disk-shaped diaphragm A of the pressure-receiving diaphragm 3 is pressed in the opposite direction and deflects, this excess pressure is transmitted to the semiconductor diaphragm 11 via the sealed liquid 2 in the sealed circuit 9 and passes through the bypass 13 to receive the pressure. It is transmitted to the annular diaphragm B of the diaphragm 4.

In this case, since the annular diaphragm B has a smaller spring behavior than the plastic deformation of the semiconductor diaphragm 1T as described above, the annular diaphragm B is pushed to the right by the excess pressure to open the bypass 13.

Therefore, the sealed liquid 2 in the sealed circuit 9 flows between the pressure receiving side surface 1b and the pressure receiving diaphragm 4 through the bypass 13, and the excess pressure is released to the downstream side of the orifice. Absorbed by the PL side.

After the excess pressure on the PH side is absorbed into the pL side in this way, the internal pressure that has moved excessively into the gap between the pressure receiving 11fiI 1 b and the pressure receiving diaphragm 4 due to the spring behavior of the annular diaphragm B of the pressure receiving diaphragm 4 is The sealing liquid 2 is returned to the enclosure circuit 9 side via the bypass 13, allowing a normal pressure side bed within the measurement span.

On the other hand, if excessive pressure occurs downstream of the orifice,
As the pressure receiving diaphragm 4A moves to the left (the sealed liquid 2 in the sealed circuit 10 is guided through the bypass 14 and presses the annular diaphragm B of the pressure receiving diaphragm 3, the same process as described above occurs in this case as well) Said annular diaphragm B
The excess pressure generated on the downstream side due to the deformation of is absorbed on the upstream side of the orifice.

Thus, with such an arrangement, excess pressure can be released to the opposing pressure side via the bypass 13,14 provided in the enclosed circuit on each pressure side, so that the semiconductor diaphragm 17
It is possible to perform good and highly accurate differential pressure measurements without the risk of damage.

In addition, the structure is simple, and the annular diaphragm B makes it relatively compact.

FIG. 4 is a sectional view of a main part showing another embodiment of the present invention.

In this embodiment, the disk-shaped diaphragm A of each pressure-receiving diaphragm 3, 4 is given a spring behavior less than the force that causes plastic deformation to the semiconductor diaphragm, and each pressure-receiving side surface 1a, I
b, the annular diaphragm B and each pressure-receiving side surface 1a,
It differs from the above embodiment in that an appropriate gap is provided between it and 1b.

Even in such a configuration, when excessive pressure occurs, the pressure receiving diaphragm 3 or 4 is pressed to the right or left and flexes, releasing the excess pressure to the opposing pressure side, so that the semiconductor diaphragm is protected as in the above embodiment. It should be obvious that you can.

As explained above, according to the differential pressure detector according to the present invention, the pressure receiving diaphragm is formed of a disk-shaped diaphragm and an annular diaphragm, and either one of the pressure-receiving diaphragms is provided with a spring having a force that is less than or equal to the force that applies plastic deformation to the semiconductor diaphragm. In addition to applying pressure to the pressure-receiving side, counter pressure M is applied to the enclosed circuit on each pressure side.
By-passes opening on each surface of llOll are provided so that excess pressure applied to the pressure-receiving diaphragm is released to the opposing pressure side 1, which prevents damage to the semiconductor diaphragm and enables highly accurate measurement. The durability of the co-moxibustion device itself can be improved, and the effect is very large.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the differential pressure detector according to the present invention, Fig. 2 is an exploded perspective view of the pressure receiving diaphragm shown in Fig. 1, and Fig. 3 is the sensor shown in Fig. 1. FIG. 4 is a sectional view of a main part showing another embodiment of the present invention. 1...Body main body, 2...Inner sealing liquid, 3
, 4... Pressure receiving diaphragm 9, 10...
... Enclosed circuit, 13゜14 ... Bypass, 15
...Sensor, 17...Semiconductor diaphragm, A...Disc-shaped diaphragm, B...
...Annular diaphragm.

Claims (1)

[Scope of utility model registration request] In a differential pressure detector, each measurement pressure is applied to two pressure-receiving dianorams, and the movement of the liquid sealed inside the body is extracted as an electrical output by straining a semiconductor diaphragm that partitions the sealed circuit. , the pressure receiving diaphragm is formed of a disc-shaped diaphragm formed in a corrugated shape and an annular diaphragm surrounding the outer periphery of the cylindrical diaphragm, each pressure receiving side surface of the body main body is formed in the same waveform as the pressure receiving diaphragm, Either one of the disk-shaped diaphragm and the annular diaphragm is pressed against the pressure-receiving side surface with a force that is less than the force that causes plastic deformation of the semiconductor diaphragm, and the pressure-receiving side surface on the pressure side opposite to the sealed circuit on each pressure side is in contact with the pressure-receiving side surface. A differential pressure detector characterized by being provided with a bypass.