JPH0850070A - Differential pressure transmitter - Google Patents

Abstract

PURPOSE:To detect an accurate value even when excessive pressure is applied from a process fluid by providing a differential pressure transmitter so that the pressure receiving direction of a center diaphragme is different from the pressure receiving direction of first and second seal diaphragms. CONSTITUTION:When the pressure from a process fluid is applied to a seal diaphragm 6, pressure is transmitted to a semiconductor differential pressure sensor 44 from the seal liquid 15 of a pressure receiving chamber 201 and the isolated chamber 203 between an overload protecting diaphragm 4 and a center metal fitting. Even when pressure is applied to a seal diaphragm 7, in the same way, the pressure is transmitted to the rear surface of the sensor 44 from the seal liquid 16 of a pressure receiving chamber 202 and an insolated chamber 204. Since the diaphragm 4 is arranged in the direction right-angled to the diaphragms 6, 7, even when excessive pressure is applied to measuring fluid pressure receiving chambers 17, 18, the strain of a member generated in the vicinity of the diaphragms 6, 7 becomes hard to transmit to the diaphragm 4 and, therefore, the change of the zero point of the diaphragm or the change of a motion fulcrum is eliminated and accurate differential pressure can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure transmitter, and more particularly to a differential pressure transmitter which prevents a change of a zero point of a center diaphragm and a deformation of a pressure receiving component to accurately detect a differential pressure.

[0002]

2. Description of the Related Art Generally, the structure of a pressure receiving portion of a conventional differential pressure transmitter is, as described in JP-A-60-185131 (see FIG. 2), a pressure receiving member including a main body H and a main body. It is composed of two parts L, and a seal diaphragm is fixed to one surface of the main body H, and a sensor section and a center diaphragm are fixed to the other surface.

The seal diaphragm is fixed to one surface of the body L, and the other surface is welded on the outer periphery of the body H and the body L so that the center diaphragm of the body H is pressed against the seal diaphragm. Further, on both sides of the main body composed of the main bodies H and L, first and second pressure receiving chambers formed by seal diaphragms for receiving the first and second fluids are formed, and the main body H, the sensor assembly, A center diaphragm and a main body L provide first and second isolation chambers, and a pressure guiding path that connects the first pressure receiving portion and the first isolation chamber, and a pressure guiding path that connects the first isolation chamber and the semiconductor differential pressure sensor. , A pressure guiding path connecting the second pressure receiving chamber and the second isolation chamber, and a pressure guiding path connecting the second isolation chamber and the semiconductor differential pressure sensor.

Filling liquid is filled in the first pressure receiving chamber, the first isolation chamber, the semiconductor differential pressure sensor, and the pressure guide path connecting these. Similarly, the second pressure receiving chamber, the second isolation chamber, the semiconductor pressure differential pressure sensor, and the pressure guiding path connecting these are filled with the filled liquid, and the pressure is transmitted to the semiconductor differential pressure sensor.

In the conventional differential pressure transmitter, a flange is attached at a position facing the seal diaphragm, and the main body H,
By tightening and fixing L and the flange with bolts and nuts, the pressure from the process fluid is transmitted to each pressure receiving chamber. When maintaining the differential pressure transmitter, loosen the bolts that fasten the pressure receiving member and the flange to inspect the first and second seal diaphragms that are joined to both sides of the pressure receiving member. After taking out, the seal diaphragm was inspected.

[0006]

In the pressure receiving part of the conventional differential pressure transmitter, the main body member is composed of the main body H and the main body L, and the center diaphragm is sandwiched between the main body H and the main body L to weld and fix them. There is. Therefore, the shape and position of the center diaphragm are determined by the pressing force of the welding of the main body H and the main body L.

The measuring fluid pressure receiving chamber has two main bodies H and L.
It is formed by sandwiching it from both sides with individual flanges and tightening it with bolts and nuts. Since the tightening force of this flange presses the main body H and the main body L from both ends, it affects the shape and position of the center diaphragm, and the tightening force of this flange is applied to the first and second measurement fluid pressure receiving chambers. Even when pressure was applied, it changed according to the pressure.

As described above, the welding of the main body H and the main body L and the tightening force of the flange are major factors for changing the shape and position of the center diaphragm, and the main body member is deformed when pressure is applied to fill the inside. This causes the filled liquid to move, deforms the seal diaphragm, and this effect appears as a change in the zero point, which is an obstacle to accurate differential pressure measurement.

In the maintenance of the differential pressure transmitter, the work is difficult because the pressure receiving member and the flange are separated, the pressure receiving member is then taken out, and the seal diaphragm is inspected.

[0010]

In order to solve the above problems, in the differential pressure transmitter of the present invention, when the center diaphragm is provided in the main body member, the pressure is received in the pressure receiving direction of the first and second seal diaphragms. On the other hand, the pressure receiving direction of the pressure of the center diaphragm is set to be different, the fulcrum portion of the center diaphragm is pressed by the pressure receiving member, and the pressure receiving member is firmly joined to the main body member of the pressure receiving unit. It is also.

Further, in the differential pressure transmitter of the present invention, first and second pressure receiving chambers made of the first and second seal diaphragms are provided with the pressure receiving direction of the center diaphragm interposed therebetween, and these pressure receiving chambers are provided. And the first and second isolation chambers formed by the center diaphragm are connected to the pressure guiding path.

Further, the body member constituting the pressure receiving chamber constitutes a measuring fluid pressure receiving chamber for receiving the measuring fluid in the seal diaphragm, and the measuring fluid pressure receiving chamber is provided with an opening portion directly connected to the process pipe.

[0013]

The operation of the differential pressure transmitter according to the present invention will be described below in comparison with the conventional differential pressure transmitter.

In the conventional differential pressure transmitter, since the first and second seal diaphragms, the center diaphragm and the sensor assembly are arranged side by side on the same axis, when joining the members supporting the respective diaphragms. Also, when pressure is applied from the measuring fluid to the member supporting the seal diaphragm, the center diaphragm is distorted in shape and position, resulting in a zero-point change. On the other hand, in the differential pressure transmitter of the present invention, since the pressure receiving direction of the center diaphragm is different from the pressure receiving direction of the first and second seal diaphragms, the seal diaphragm is joined to the pressure receiving member. Even in this case, the strain generated at this time is not transmitted to the center diaphragm, and when the respective diaphragms are joined to the pressure receiving member, the strains at the time of joining are not transmitted to each other.

Further, since the operation fulcrum of the center diaphragm is clarified by the member forming the isolation chamber of the pressure receiving portion, the operation of the center diaphragm is clarified, and the fulcrum does not move at the time of pressure load, and the zero point changes. Does not occur.

Furthermore, since this pressure receiving member is firmly joined and sealed to the main body member of the pressure receiving member by screws or welding, the amount of deformation under pressure load can be reduced and the zero point change can also be reduced. .

When the differential pressure transmitter is used, even if an excessive pressure is applied to the member supporting the seal diaphragm from the measuring fluid chamber, these strains hardly affect the center diaphragm.

Further, since the first and second pressure receiving chambers can be provided close to the first and second isolation chambers, respectively, the path of the pressure guiding path for providing each pressure chamber can be shortened. You can

Further, since the measurement fluid pressure receiving chamber is constituted by the member constituting the pressure receiving chamber and the opening portion which is directly connected to the process pipe is provided in this member, the flange which was conventionally required can be eliminated and maintenance can be performed. Is easy.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The differential pressure transmitter of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the differential pressure transmitter according to the present invention. The differential pressure transmitter mainly comprises a pressure receiving member 20, a sensor unit set 2, seal diaphragms 6, 7, and an overpressure member. Load protection diaphragm 4, first and second pressure receiving chambers 201,
02, first and second isolation chambers 203 and 204.

FIG. 3 shows a detailed view of the pressure receiving member 20 shown in FIG. The pressure receiving member 20 is composed of a single member, and holes 21 and 22 for symmetrically attaching the seal diaphragms 6 and 7 are provided at both ends of the pressure receiving member 20, and the bottom surface has the same shape as the seal diaphragms 6 and 7. Processed, hole 2
Screw holes 37, 38 having a diameter larger than that of the seal diaphragms 6, 7 for fixing the stoppers 35, 36 to the inlets of the 1, 22.
Is formed.

FIG. 4 is a sectional view taken along line aa of FIG.

The pressure receiving member 20 is provided with a taper screw 28 on the upper side of the hole 22 for mounting the seal diaphragm 7 and a taper screw 30 on the lower side thereof. It is connected. Similarly, in the hole portion 21, taper screws 27 and 29 (not shown) are processed in the upper and lower portions,
They are connected by conducting paths 31 and 33.

Further, on the central axis of the pressure receiving member 20, there are provided sensor part group accommodation holes 23 for accommodating the overload protection diaphragm 4 and the sensor part group 2, and the seal diaphragms 6, 7.
It is provided in the direction perpendicular to. On the small diameter side of the stepped hole 23, a hole 9 for mounting the amplifier is provided, and on the large diameter side, a hole 10 for mounting a fixing metal fitting 8 for fixing the overload protection diaphragm 4 is provided.

A conduction path 2 is formed between the seal diaphragms 6 and 7, the overload protection diaphragm 4, and the sensor unit set 2.
It is connected by 4, 25, 26.

The structure of the first pressure receiving chamber 201, the second pressure receiving chamber 202, the first isolation chamber 203, and the second isolation chamber 204 in the differential pressure transmitter of one embodiment of the present invention will be described with reference to FIG. explain.

In the differential pressure transmitter according to the present embodiment, the pressure receiving member 20 extends from the holes 21 and 22 to the seal diaphragms 6 and 7.
Are assembled and welded so that the surfaces of the seal diaphragms 6 and 7 are parallel to each other to form the first and second pressure receiving chambers 201 and 202.

Next, the plugs 35 and 36 are screwed into the screw holes of the pressure receiving member 20, and the end face portions thereof are joined and sealed by welding to form the measurement fluid pressure receiving chambers 17 and 18.

The sensor unit set 2 is inserted into the sensor unit set housing hole 23 at the center of the pressure receiving member 20 from the direction of the larger diameter, and the conducting path 60 of the sensor unit set 2 and the conducting path 25 of the pressure receiving member 20 are inserted. Are installed so as to conduct electricity, and both ends of the sensor assembly 2 are welded.

After that, the center metal fitting 5 is placed at a position where the conduction path 61 of the center metal fitting 5 and the conduction path 24 of the pressure receiving member 20 are electrically connected to each other, and the surface of the overload protection diaphragm 4 which has been processed into the corrugated shape is overloaded. The protective diaphragm 4 is attached toward the protective diaphragm 4 side, and the excessive / improper protective diaphragm 4 is attached to the pressure receiving member 2
Welded to 0 to form a first isolation chamber 203. At the center of the center metal fitting 5, there is provided a conducting path 63 for transmitting pressure from the overload protection diaphragm 4 to the semiconductor differential pressure sensor 44.

In the fixing metal fitting mounting hole 10, the conductive path 62 of the spacer 80 located on the lower surface of the fixing metal fitting 8 and the pressure receiving member 20.
Of the overload protection diaphragm 4 so that the conduction path 26 is electrically connected, and the surface of the overload protection diaphragm 4 processed to have the same corrugated shape is attached toward the overload protection diaphragm 4 side, and the screw portion formed by the fixing bracket 8 and the pressure receiving member 20 is attached. The threaded portion of the fixing metal fitting 8 is screwed into and the end portion is sealed by welding.
To form 04. Next, the seal diaphragm 6, the overload protection diaphragm 4, the sensor assembly 2, the conductive paths 24, 6
1, 63, the space surrounded by the seal pin 51 of the liquid sealing port is filled with the filled liquid 15, and similarly, the seal diaphragm 7, the overload protection diaphragm 4, the sensor assembly 2, the conductions 25, 26, 60, 62, the space surrounded by the seal bottle 52 of the liquid sealing port is also filled with the enclosed liquid 16.

FIG. 6 is a detailed view of the overload protection diaphragm 4, the pressure receiving member, and the fixing metal fitting 8 portion of FIG. The overload protection diaphragm 4 is welded and joined to the pressure receiving member, and when the fixing metal fitting is screwed into the pressure receiving member 20 by the protrusion 681 of the spacer 81, the inside of the welded portion is brought into contact with the end surface of the fixing metal fitting and pressed. The fixing fitting 8 is welded and sealed with an argon arc at the pressure receiving member 20 and its end face portion. Therefore, since the motion fulcrum of the center diaphragm is pressed firmly, there is no influence of strain, and the motion fulcrum is always clarified. Further, when a pressure is applied, a large pressure difference is generated between the isolation chamber 204 and the end surface (atmosphere side) of the fixing metal fitting, and the fixing metal fitting 8 is elastically deformed, and the deformation may move the enclosed liquid to change the zero point. However, since the length of the screw joint portion 683 of the fixing member 8 is sufficiently secured, the amount of deformation thereof is very small. Therefore, the influence of the zero point is small.

The sensor assembly 2 includes a semiconductor differential pressure sensor 44 and a hermetic seal bin 45, and the FPC 46 is soldered to the atmospheric pressure release side of the hermetic seal bin 45, which is required in the conventional differential pressure transmitter. The pressure receiving member 20 need not be provided with a hole for taking out a sensor signal.

The amplifier case 47 is inserted into the amplifier mounting hole 9, the metal 14 is inserted into the groove formed by the pressure receiving member 20 and the amplifier case 47, and the amplifier case 47 is connected to the pressure receiving member 20 by metal flow bonding. Fixed to.

The differential pressure detecting operation of the differential pressure transmitter having such a structure will be described with reference to FIG. When the first pressure from the process fluid is applied to the seal diaphragm 6, the first pressure of the measurement fluid is transmitted to the sealed liquid 15 in the first pressure receiving chamber 201 on the back side of the seal diaphragm 6 through the seal diaphragm 6. Further, this first pressure is applied to the conduit 24,
It is transmitted to the first isolation chamber 203 formed between the overload protection diaphragm 4 and the center metal fitting 5 through 61, and further transmitted to the semiconductor differential pressure sensor 44 through the conducting path 63 of the center metal fitting 4. Also, when the second pressure from the process fluid is applied to the seal diaphragm 7, the second pressure of the measurement fluid is similarly transmitted to the enclosed liquid 16 in the second pressure receiving chamber 202 via the seal diaphragm 7, and this second pressure is transmitted. The second pressure is the second isolation chamber 204 formed between the overload protection diaphragm 4 and the fixture 8 by the passages 25 and 26.
Is transmitted to the back surface of the sensor through the conduction path 60. In this way, the semiconductor differential pressure sensor 44 detects the first and second pressures of the measured fluid transmitted to the front and back of the center diaphragm, and the output of the semiconductor differential pressure sensor 44 is taken out from the hermetic seal pin 45 to the atmosphere open side. And is transmitted to the amplifier via the FPC 46.

The measurement fluid pressure receiving chambers 17 and 18 are composed of the pressure receiving member 2.
Since it is formed within 0, a flange and bolts and nuts for tightening the flange are not particularly required unlike the conventional example. That is, it is only necessary to provide the plugs 35 and 36 to form the measurement fluid pressure receiving chambers 17 and 18.

As for the process pipe, as shown in FIG. 5, the adapter 43 and the gasket 48 are fastened by bolts 50 to one of the connection ports of the pressure receiving member 20. Piping 41
Is screwed into the adapter 43 for use. The drain / vent plug 3 is attached to the other connection port of the pressure receiving member 20.
9, the process pipe connection and the drain / vent plug 39 can be connected both vertically and at right angles.
Although the adapter 43 is used to connect the pipe 41 and the pressure receiving member 20 in the drawing, the pipe 41 can be directly joined by cutting a taper screw on the pressure member 20.

As described above, according to the differential pressure transmitter of the present invention, by arranging the pressure receiving direction of the seal diaphragm in the direction perpendicular to the pressure receiving direction of the first and second seal diaphragms, the center diaphragm and the pressure receiving direction are arranged. Since the welding position with the member 20 can be provided at a position where strain is not transmitted as compared with the conventional example in which diaphragms are arranged on the same axis, no strain occurs in the shape and position of the seal diaphragm.

Further, by arranging in the right angle direction, even when an excessive pressure is applied to the measurement fluid pressure receiving chambers 17 and 18 from the process fluid, the strain of the member generated in the vicinity of the seal diaphragm is less likely to be transmitted to the center diaphragm as strain. Therefore, the change of the zero point of the overload protection diaphragm and the change of its fulcrum of movement are eliminated, and the differential pressure can be accurately measured.

Further, according to the differential pressure transmitter of the present invention, since the measurement fluid pressure receiving chambers 17 and 18 can be formed in the pressure pressure receiving member 20, the pressure receiving member 20 can be constructed as a single component, and the measurement fluid pressure receiving chamber 17 can be formed. No flanges, bolts or nuts are needed to form the. Therefore, since there is no change in the shape of the pressure receiving member 20 due to the tightening of the bolts and nuts and no deformation of the pressure receiving member main body when one-sided pressure or excessive static pressure is applied to the measurement fluid pressure receiving chambers 17 and 18, the overload protection diaphragm The differential pressure can be measured more accurately by eliminating the change in the zero point and the change in the support point.

A modification of the mounting of the fixing fitting is shown in FIGS.

In FIG. 7, a protrusion 781 for clarifying the motion fulcrum of the overload protection diaphragm 4 is provided in the fixing member 8, and the pressure receiving member and the fixing member 8 are provided in the center diaphragm 4.
Is welded at a position very close to (a position close to the isolation chamber on the fitted circumferential surface).
The welding depth of this weld is a welding method (electron beam welding, etc.) that can ensure sufficient strength against the working pressure of the differential pressure transmitter.
Can be realized by According to this structure, the number of pressure receiving members is reduced and the space in the circumferential direction of the fixing fitting can be eliminated, so that the amount of enclosed liquid can be reduced and further miniaturization can be achieved. Further, when pressure is applied, no pressure acts on the cylindrical surface of the hole 10 (FIG. 3) of the pressure receiving member, so that there is no deformation. Therefore, the zero point change due to the deformation can be further suppressed, and the accurate differential pressure can be measured.

FIG. 8 shows a case where the fixing member is composed of two members 83 and 84. The member 83 has a convex portion 881 for clarifying the fulcrum portion of the center diaphragm 4, and further the isolation chamber 204. Has a space to form. Further, the circumferential portion is welded and joined by the same method as in the embodiment of FIG. Next, the member 84 is screwed into the threaded portion of the pressure receiving member 20 through the groove 884 with a predetermined torque, so that the initial strain is applied to the member 83, so that the deformation is suppressed when the pressure is applied. You can The member 8
4 has its end sealed by welding. With this configuration, the zero point error caused by the deformation of the pressure receiving member can be further reduced, and the welded portion, which requires reliability, is not exposed, so that the reliability is improved.

FIG. 9 shows that the plugs 35 and 36 have fine holes 935 and
936 is provided, and the shape is changed to have a minute space so that the other pressure receiving chambers 921 and 922 can be formed on the opposing surfaces of the pressure receiving chambers 201 and 202. Such a configuration is used in process instrumentation to measure the liquid level and density in a tank, which is widely used for measuring the liquid level and density in a tank. It can be easily applied to (equipment example of the provided parts). This plug, when assembled, has the above-mentioned plugs 35, 3
Since it only needs to be replaced by 6 and assembled, it has excellent assemblability and expandability. Further, in the pressure receiving portion of the diaphragm replacer type differential pressure transmitter, the screw hole of the pressure introducing port shown in FIG. 1 is not necessary at all, which is excellent in economy.

<< Additional Part >> FIG. 9 shows the pressure receiving portion of the present invention applied to a diaphragm-replacer type differential pressure transmitter which is widely used for measuring the pressure, liquid level and density in a tank in process measurement. FIG. 10 shows the configuration when applied, and FIG. 10 shows the configuration of the tip portion of the diaphragm-replacer type differential pressure transmitter.

In the conventional diaphragm-replacer-type differential pressure transmitter, when attaching the tip of the diaphragm-replacer-type differential pressure transmitter to the pressure-receiving portion, it is necessary to join them through a special member. Since the strain at that time affects the pressure characteristic of the basic pressure receiving part, the characteristic has changed. Further, the cost is inevitably increased because the special component is required.

On the other hand, the diaphragm replacer type differential pressure transmitter of the present invention has a basic pressure receiving portion structure shown in FIG. 1, and a structure for transmitting the pressure from the diaphragm replacer portion to this pressure receiving portion. It employs a structure in which a member is added, and it is joined and sealed to the pressure receiving part.

According to the present invention, in the basic pressure receiving portion construction, a diaphragm replacer type differential pressure transmitter can be constructed only by changing the construction of the plugs 35 and 36 to the member shapes shown in FIG.

Fine holes 935, 936 are formed in the stoppers 35, 36.
Is further provided, and the other pressure receiving chambers 921 and 922 are formed on the opposing surfaces of the pressure receiving chambers 201 and 202, and the shape is changed to have a fine space.

Micro-holes 935, 936 are formed on the other end surfaces of the plugs 35, 36 by joining and sealing constituent members for transmitting pressure with the diaphragm replacer portion.
The pressure from the diaphragm replacer portion is transmitted via the.

FIG. 10 shows an example of the configuration of the portion of the diaphragm replacer type differential pressure transmitter that directly receives the process fluid.

The process connection diaphragm 952 is joined and sealed to the process connection member 953 by welding,
A pressure receiving chamber 260 is formed between 53 and 53. Further, since this connecting member 953 is attached to a process pipe, a flange of a tank or the like, it is fixed and integrated with a bolt 955 through a process connecting flange 954 that matches the shape of the process side. Further, a component member 951 for transmitting process pressure to the stoppers 35, 36 is attached on the outer periphery of the process connecting member 953. Silicon oil is enclosed in the space created in this configuration, and the pressure of each process is the diaphragm 952, the pressure receiving chamber 260, the pressure guiding paths 958 and 951, and the plugs 35 and 36.
The pressure difference is transmitted to the semiconductor differential pressure sensor 44 via and the differential pressure can be detected.

With such a structure, the diaphragm replacer type pressure receiving chamber can be changed by simply changing the plugs 35, 36 forming the basic pressure receiving portion as shown in the figure, and additional parts are provided on the pressure receiving portion side. It can be configured without any need.

Further, it is excellent in expandability without impairing the basic differential pressure detection characteristic of the pressure receiving portion.

[0056]

According to the differential pressure transmitter of the present invention, the generated strain does not affect the center diaphragm even when the center diaphragm is joined to the pressure receiving member main body and when an excessive pressure is applied from the process fluid. Since there is no change in its shape and position and it does not affect the zero point, and because the zero point error due to deformation of the pressure receiving part member during pressure load can be reduced, there is an effect that accurate differential pressure can be detected and the transmitter as a whole. Can be made smaller.

Further, since the measuring fluid pressure receiving chamber is composed of the pressure receiving member, the flange is not required, and the pressure receiving member is composed of a single component of the pressure receiving member and the plug, thereby enabling further miniaturization.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a differential pressure transmitter of the present invention.

FIG. 2 is a vertical sectional view of a conventional differential pressure transmitter.

3 is a longitudinal sectional view of the pressure receiving member of FIG.

4 is a cross-sectional view taken along the line aa of FIG.

FIG. 5 is a vertical sectional view showing an example of piping of the differential pressure transmitter of the present invention.

FIG. 6 is an enlarged view of a center diaphragm mounting portion and a fixing bracket mounting portion.

FIG. 7 is a cross-sectional view of another embodiment of mounting the center diaphragm.

FIG. 8 is a sectional view of another embodiment of mounting the center diaphragm.

FIG. 9 is a cross-sectional view of an embodiment of a diaphragm replacer type pressure receiving portion.

FIG. 10: Diaphragm replacer tip.

[Explanation of symbols]

2 ... Sensor assembly, 4 ... Overload protection diaphragm, 5 ... Center fitting, 6, 7 ... Seal diaphragm, 8 ... Fixing fitting, 9 ... Amplifier mounting hole, 10 ... Fixing fitting mounting hole, 14 ...
Metal, 15, 16 ... Enclosed liquid, 17, 18 ... Measuring fluid pressure receiving chamber, 20 ... Pressure receiving member 21, 22 ... Seal diaphragm mounting hole portion, 23 ... Sensor unit assembly storing hole portion, 24, 2
5,26,31,32,33,34,60,61,6
2, 63 ... Conducting path, 27, 28, 29, 30 ... Tapered female screw, 35, 36 ... Plug, 37, 38 ... Screw hole, 39 ...
Drain / vent plug, 41 ... Piping, 43 ... Adapter, 44 ... Semiconductor differential pressure sensor, 45 ... Hermetic seal bin, 46 ... FPC, 47 ... Amplifier case, 48 ... Gasket, 50 ... Bolt, 51, 52 ... Seal pin, 5
3, 54 ... Liquid sealing port, 81 ... Spacer, 83, 84 ... Modification of fixing metal fitting, 101 ... Main body H, 102 ... Sensor assembly,
103 ... Center fitting, 104 ... Overload protection diaphragm, 105 ... Main body L, 106, 107 ... Seal diaphragm, 108, 109 ... Flange, 110, 111 ... Gasket, 112 ... Bolt, 113 ... Nut, 114 ... Connection fitting, 115 , 116 ... Isolation chamber, 117, 118 ... Measuring fluid pressure receiving chamber, 144 ... Semiconductor differential pressure sensor, 201 ... First pressure receiving chamber, 202 ... Second pressure receiving chamber, 203 ... First isolation chamber, 204 ... Second Isolation room.

Front Page Continuation (72) Inventor Yoshimi Yamamoto 882 Ichige, Katsuta City, Ibaraki Prefecture Hitachi Ltd. Measuring Instruments Division

Claims (10)

[Claims] 1. A first pressure receiving chamber formed by a first diaphragm and containing a first detection fluid, and a second pressure chamber formed by a second diaphragm and containing a second detection fluid. A pressure-receiving chamber, the pressure of the first measurement fluid is applied to the first diaphragm, the pressure of the second measurement fluid is applied to the second diaphragm, and the difference between the two pressures is detected by a differential pressure detection sensor. In the differential pressure transmitter, a first isolation chamber that is in communication with the first pressure receiving chamber and a second isolation chamber that is in communication with the second pressure receiving chamber are provided in different directions from the first and second diaphragms. A third diaphragm disposed in the first and second isolation chambers is applied to the differential pressure detection sensor, and the first diaphragm is connected to the first diaphragm. Place it on the first end face of the pressure receiving member body of the differential pressure transmitter, and A second diaphragm disposed on the second end surface of the pressure receiving member body opposed to said first end surface,
The pressure receiving direction of the first diaphragm and the pressure receiving direction of the second diaphragm are coaxial, and the first diaphragm and the pressure receiving direction of the second diaphragm are positioned at right angles. A third diaphragm is arranged, one surface of the third diaphragm is joined to a pressure receiving member constituting the differential pressure transmitter to form the first isolation chamber, and the other surface of the third diaphragm is formed. The diaphragm is pressed and hermetically joined to form the second isolation chamber,
A semiconductor differential pressure sensor having a pressure detection diaphragm as the differential pressure detection sensor is provided, and the pressure detection direction of the pressure detection diaphragm and the pressure reception direction of the third diaphragm are configured to be the same direction, and the semiconductor differential pressure sensor The sensor is held by a seal fitting, and the joint between the pressure receiving member that constitutes the differential pressure transmitter and the seal fitting has a joint diameter that decreases along the atmospheric pressure direction. A differential pressure transmitter comprising a single member having a junction with an amplifier for normalizing an output. 2. The differential pressure transmitter according to claim 1, wherein a pressure receiving member of the differential pressure transmitter that forms the first pressure receiving chamber controls the pressure of the first measurement fluid to the first diaphragm. The pressure of the second measurement fluid is guided to the second diaphragm by the pressure receiving member of the differential pressure transmitter that constitutes the first measurement fluid pressure receiving chamber that guides the pressure to the second diaphragm. First and second pressure guide ports that constitute a second measurement fluid pressure receiving chamber to be pressed and that are joined to the pipes that transmit the first and second measurement fluid pressures to the first and second measurement fluid pressure receiving chambers. A differential pressure transmitter characterized by being provided with. 3. The differential pressure transmitter according to claim 1, wherein the pressure receiving member forming the first and second measurement fluid pressure receiving chambers is provided with at least one opening different from the pressure guide port. Characteristic differential pressure transmitter. 4. The differential pressure transmitter according to claim 3, wherein the opening is provided at a position facing the first and second diaphragms. 5. The differential pressure transmitter according to claim 4, wherein the opening is provided at a position facing the pressure guide port. 6. The differential pressure transmitter according to claim 1, wherein a portion other than a joint portion of the third diaphragm is pressed by a member different from a member forming the isolation chamber, and the member is isolated. A differential pressure transmitter characterized in that it is pressed by a member that forms a chamber, is fixed to the pressure receiving member body by screwing, and its end is sealed by welding. 7. The differential pressure transmitter according to claim 1, wherein a portion other than the joint portion of the third diaphragm is pressed by a member that forms the isolation chamber, and the peripheral surface of the pressure receiving member main body is pressed. Differential pressure transmitter characterized by being fixed and sealed by welding. 8. The differential pressure transmitter according to claim 1, wherein a portion other than a joint portion of the third diaphragm is pressed by a member forming the isolation chamber, and the peripheral surface of the pressure receiving member main body is pressed. It is fixed and sealed by welding, and has another member that presses the member on its coaxial extension. The member is fixed to the pressure receiving member main body by screw joining and the end portion is sealed by welding. The differential pressure transmitter characterized in that 9. The differential pressure transmitter according to claim 2, wherein the first and second measurement fluid pressure receiving chambers for introducing pressure to the first and second diaphragms are provided with a pressure receiving member body of the differential pressure transmitter and a screw. A differential pressure transmitter, which is formed by being joined with a member having a joining portion and sealed by welding at an end thereof. 10. The differential pressure transmitter according to claim 9, wherein said member has a minute space portion forming third and fourth pressure receiving chambers on the side opposite to said first and second pressure receiving chambers. Formed by being joined by a pressure-receiving member main body of the differential pressure transmitter and a member having a screw joint portion, and having a micro-hole communicating with the space portion, and being sealed by welding at an end thereof. A differential pressure transmitter characterized in that