JPH0569649U - Differential pressure sensor unit - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the number of parts in a differential pressure sensor unit and facilitate assembly and disassembly. A differential pressure sensor unit configured such that a fluid pressure is applied to both front and back surfaces of the pressure receiving section 10, and a strain detecting section 11 provided in a strain generating section of the pressure receiving section detects a differential pressure between two fluid pressures. And has two fluid pressure introducing members 1 and 2 for introducing each of the two fluid pressures, and a pressure receiving portion,
The differential pressure detecting member 3 detects the differential pressure in the strain detecting section. The differential pressure detecting member is provided between the two fluid pressure introducing members, and the differential pressure detecting member includes an outer peripheral surface facing one fluid pressure introducing member and the other fluid pressure introducing member. Two sealing members 16 and 19 having an inner peripheral surface facing the inner peripheral surface and contacting the inner peripheral surface and the outer peripheral surface are provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a differential pressure sensor unit, and more particularly to a differential pressure sensor unit having a small number of parts and a structure that is easy to assemble and disassemble.

[0002]

[Prior Art]

 As shown in FIG. 2, the present inventor has previously provided a strain detection unit 52 composed of a plurality of strain gauges on one surface of a thin metal plate-shaped diaphragm 51, and the diaphragm 51. Has proposed a differential pressure sensor unit configured to detect a differential pressure between two fluid pressures by applying a fluid pressure to each of the two front and back surfaces (PCT / JP89 / 00745, WO90 / 01153). In this differential pressure sensor unit, the strain detection portion 52 is covered with a protective film and protected from the pressure fluid. The diaphragm 51 is housed in a concave portion at the bottom of a cylindrical holding block 53, is fixed with an adhesive 62, and is sandwiched between the holding block 53 and a casing 54 having a hole 54a for housing the same. Can be installed with. The casing 54 is, for example, a part of a wall portion of a hydraulic machine or the like in which the differential pressure sensor unit is assembled. The holding block 53 and the casing 54 are formed with a hole 55 through which a first fluid passes and a hole 56 through which a second fluid passes. The holes 55 and 56 guide the first and second fluids to the front and back surfaces of the diaphragm 51. Three seal rings 57 are arranged between the holding block 53 and the casing 54.

A detection signal of the strain detecting section 52 arranged on the upper surface of the diaphragm 51 is taken out by a lead wire 58. The lead wire 58 is drawn upward and extends through the hole formed in the holding block 53 to the upper side of the block 53. A glass hermetic seal 59 is provided in the hole through which the lead wire 58 is wired, so that insulation and airtightness are maintained. An electric circuit unit 60 that amplifies the detection signal output from the strain detection unit 52 is provided on the upper surface of the holding block 53. In the configuration shown, the holding block 53 is fixed to the casing 54 using the screw portion 61.

[0004]

[Problems to be solved by the device]

 The conventional differential pressure sensor unit having the above structure has the following problems in terms of assemblability.

The holding block 53 is provided for assembly after the hermetic seal 59 is completed. Therefore, joining the strain-flexing portion of the diaphragm 51 and the lead wire 58 for taking out a signal becomes an operation that cannot be visually observed, which is very difficult. In addition, such a structure lacks reliability of the connection part.

Furthermore, since two fluid pressure holes are formed in the casing 54, three O-rings 57 for a fluid-sealing reservoir are used. As a result, there is a problem that the number of parts increases. Although not shown in FIG. 2, a screw portion and a holding component are required for use as a differential pressure sensor unit. Therefore, the number of parts is further increased.

In addition, since holes for introducing two fluids are formed in the casing 54, for example, when a nipple having a screw for a tapered pipe is used in the fluid passage 56, the rotational position of the casing 54 is changed. Was not determined, and as a result, the position of the fluid passage 55 was not determined. According to this, it was very inconvenient in the actual differential pressure measurement.

An object of the present invention is to provide a differential pressure sensor unit having a small number of parts and easy to assemble and disassemble.

[0009]

[Means for Solving the Problems]

 The differential pressure sensor unit according to the present invention is configured such that the fluid pressure is applied to both front and back surfaces of the pressure receiving portion, and the strain detecting portion provided in the strain generating portion of the pressure receiving portion detects the differential pressure between the two fluid pressures. And a fluid pressure introducing member for introducing two fluid pressures respectively, and a differential pressure detecting member having a pressure receiving portion for detecting the differential pressure at the strain detecting portion. It is characterized by consisting of.

In the above-mentioned configuration, preferably, a thread portion for attachment is formed on one of the two fluid pressure introducing members.

In the above configuration, preferably, one of the two fluid pressure introducing members is provided with an amplifier that amplifies the detection signal output from the strain detecting section to a predetermined level.

In the above structure, preferably, the differential pressure detecting member is provided between the two fluid pressure introducing members, and the differential pressure detecting member faces one of the fluid pressure introducing members. Two sealing members having an outer peripheral surface and an inner peripheral surface facing the other fluid pressure introducing member and contacting the inner peripheral surface and the outer peripheral surface are provided.

In the above-mentioned configuration, preferably, the signal line for extracting the detection signal from the strain detecting section passes through the hermetic seal section provided in the differential pressure detecting member and reaches the signal processing circuit section using the flexible printed circuit. Be withdrawn.

[0014]

[Action]

 According to the present invention, in a differential pressure sensor including a differential pressure detecting member having pressure receiving portions for receiving different fluid pressures on both sides, the differential pressure detecting member and the two fluid pressure introducing members have three different pressure differences. The sensor unit was configured to simplify the configuration, and the differential pressure detection member was provided with a hermetic seal to improve the ease of assembly. Further, the number of O-rings for sealing can be structurally reduced, and the positional relationship of the passage of the fluid to be introduced can be freely set.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the differential pressure sensor unit according to this embodiment is composed of three parts of casings 1 and 2 and a pressure receiving member 3. The outer shapes of the casings 1 and 2 and the pressure receiving member 3 are substantially cylindrical.

A circular recess 4 for accommodating the pressure receiving member 3 is formed on the upper surface of the casing 1, and a groove 6 for accommodating an O-ring 5 as a sealing member is formed on the inner peripheral surface of the circular recess 4. Is formed. A step portion 7 for supporting the pressure receiving member 3 is formed on the inner peripheral surface portion near the bottom surface of the recess 4. On the lower surface of the casing 1, a male screw portion 8 for attaching the differential pressure sensor unit to a predetermined member such as a hydraulic machine is formed. An introduction hole 9 is formed in the center line portion of the casing 1 from the tip of the male screw portion 8 to the bottom surface of the recess 4. The first fluid is introduced through the introduction hole 9.

The pressure receiving member 3 is formed with a pressure receiving portion 10 that is a center line portion and is applied to both end surfaces at one end surface portion. The pressure receiving portion 10 is formed in a thin diaphragm shape and is used to receive different pressures on both sides. When the pressure receiving unit 10 receives the pressure, strain occurs in a predetermined region. This predetermined region acts as a strain-flexing part. That is, when pressure is applied to at least one surface of the pressure receiving portion 10, the pressure receiving portion 10 is deformed and a strain proportional to the applied pressure is generated inside the pressure receiving portion 10. The pressure receiving member 3 is arranged such that the pressure receiving portion 10 is located at the lower position.

A strain detecting unit 11 is provided on the lower surface of the pressure receiving unit 10, particularly corresponding to the strain generating portion. The strain detector 11 detects strain, that is, pressure by forming a Wheatstone bridge circuit by forming a predetermined number of strain gauges in a predetermined array by using, for example, a semiconductor film forming technique. The surface of the pressure receiving portion 10 on which the strain detecting portion 11 is formed comes into contact with the fluid introduced through the introduction hole 9.

Since the diaphragm-shaped pressure receiving portion 10 is formed in the pressure receiving member 3, a circular hole 12 having the other surface of the pressure receiving portion 10 as a bottom surface is formed in the center line portion thereof. As will be described later, the second fluid is introduced to the other surface of the pressure receiving portion 10 and comes into contact with it.

The pressure receiving member 3 having the above structure is provided with at least one hole penetrating one end surface (lower side in the drawing) and the other end surface (upper side in the drawing), and the hermetic seal portion 13 is formed in this through hole. Is formed. The signal line 15 drawn out from the strain detecting section 11 via the wire bonding 14 is inserted into the hermetic seal section 13 and is drawn out to the opposite surface.

The sealing between the pressure receiving member 3 and the casing 1 is performed by the O-ring 16 arranged in the groove 6. The O-ring 16 contacts the outer peripheral surface of the pressure receiving member 3.

The other casing 2 is formed with an introduction hole 17 for introducing the above-mentioned second fluid to the other surface of the pressure receiving portion 10 of the pressure receiving member 3. The inlet portion 17a of the introduction hole 17 is formed on the side surface portion. The outlet of the introduction hole 17 is formed at the tip of the protruding portion 18 formed on the lower surface in the figure. The protruding portion 18 is inserted into the hole 12 formed in the center line portion of the pressure receiving member 3. A groove 20 for accommodating the O-ring 19 is formed on the outer peripheral surface of the protrusion 18. The O-ring 19 seals between the pressure receiving member 3 and the casing 2. The O-ring 19 is in contact with the inner peripheral surface of the pressure receiving member 3. A recess 22 for arranging the amplifier 21 is formed on the upper surface of the casing 2 in the figure. An amplifier 21 is arranged in this recess. At least one hole 23 is formed between one end surface of the casing 2 and the recess 22 to allow them to pass therethrough. The hole 23 is used to draw out the signal line 15 drawn out by utilizing the hermetically sealed portion 13 as described above, and further through the flexible printed circuit (FPC) 24 to the place where the amplifier 21 is arranged. Reference numeral 25 is a holding ring for fixing the amplifier 21. The holding ring 25 has a hole 25a in the center thereof, and the signal line 26 from the amplifier 21 is drawn to the outside through the hole 25a.

Assembly of the differential pressure sensor unit having the above-described configuration is as follows. The pressure receiving member 3 including the strain detecting portion 11, the hermetic seal portion 13, the bonding wire 14, and the signal wire 15 is incorporated into the circular recess 4 of the casing 1 with the O-ring 16 arranged in the groove 6. After that, the FPC 24 is connected to one end of the signal line 15 protruding from the upper surface of the pressure receiving member 3. Next, the casing 2 provided with the amplifier 21 is attached to the upper side of the casing 1 with the FPC 24 inserted into the hole 23 and with the O-ring 19 provided between the FPC 24 and the pressure receiving member 3. Next, the two casings 1 and 2 are connected using a predetermined number of bolts 27 to integrate the entire differential pressure sensor unit.

According to the above configuration, the differential pressure sensor unit is made up of three parts, which are the two casings 1 and 2 and the pressure receiving member 3. Therefore, a signal extraction method that is easy to assemble and highly reliable can be implemented.

Further, the fluid to be measured can be sealed by the two O-rings 16 and 19 provided between each of the casings 1 and 2 and the pressure receiving member 3. After the casing 1 is attached to a predetermined member via the O-ring 28, the casing 2 is set by adjusting the positional relationship of the inlet portion 17a of the introduction hole 17 for introducing the pressure fluid to the object to be measured, and bolts. It can be fixed at 27 at any position.

In the example of FIG. 1, the mounting screw portion 8 of the casing 1 is a parallel pipe thread using an O-ring 28. However, a tapered taper thread may be used instead. The formation position of the inlet portion 17a for introducing the fluid in the casing 2 is different from the position of the amplifier 21, but it may be a position in the vicinity or a position in the opposite direction.

[0028]

[Effect of the device]

 As is clear from the above description, according to the present invention, the number of constituent parts can be reduced, the assembling can be facilitated, and the reliability can be improved. Only two O-rings for sealing provided inside the differential pressure sensor unit are needed, which also contributes to simplification of the structure. The position of the inlet of the hole for introducing the fluid in one of the casings can be arbitrarily set, and the degree of freedom can be increased.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the internal structure of a differential pressure sensor unit according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the internal structure of a conventional differential pressure sensor unit.

[Explanation of symbols]

 1, 2 ... Casing 3 ... Pressure receiving member 9, 17 ... Introducing hole 10 ... Pressure receiving portion 11 ... Strain detecting portion 13 ... Hermetic seal portion

Front page continuation (72) Inventor Yukio Sakamoto 650 Jinrachicho, Tsuchiura City, Ibaraki Prefecture Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. in the factory

Claims (5)

[Scope of utility model registration request] 1. A differential pressure configured to apply a fluid pressure to both front and back surfaces of a pressure receiving portion, and to detect a differential pressure between the two fluid pressures by a strain detecting portion provided in a strain-generating portion of the pressure receiving portion. The sensor unit includes two fluid pressure introducing members for introducing each of the two fluid pressures, and a differential pressure detecting member having the pressure receiving portion and detecting the differential pressure by the strain detecting portion. A differential pressure sensor unit characterized by the above. 2. The differential pressure sensor unit according to claim 1, wherein a threaded portion for attachment is formed on one of the two fluid pressure introducing members. 3. The differential pressure sensor unit according to claim 1, wherein one of the two fluid pressure introducing members is provided with an amplifier that amplifies a detection signal output from the strain detection unit to a predetermined level. Characteristic differential pressure sensor unit. 4. The differential pressure sensor unit according to claim 1, wherein the differential pressure detecting member is provided between the two fluid pressure introducing members, and the differential pressure detecting member is one of the fluids. Two sealing members having an outer peripheral surface facing the pressure introducing member and an inner peripheral surface facing the other fluid pressure introducing member and contacting each of the inner peripheral surface and the outer peripheral surface are provided. A differential pressure sensor unit characterized by the above. 5. The differential pressure sensor unit according to claim 1, wherein a signal line for extracting a detection signal from the strain detection unit passes through a hermetic seal portion provided on the differential pressure detection member and uses a flexible printed circuit. The differential pressure sensor unit is characterized in that it is pulled out to the signal processing circuit section.