JPH0547837U - Differential pressure measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable differential pressure measuring device that removes dust and does not cause a short circuit of leads. [Structure] A strain-electrical signal conversion element provided in a housing made of metal, a pressure transmission mechanism for transmitting a measurement pressure to the strain-electrical signal conversion element via a sealed liquid, and the strain-electrical signal conversion element In the differential pressure measuring device comprising a lead for extracting an electric signal from the filled liquid from
A cover provided to cover the strain-electrical signal conversion element and the lead, and at least one cover provided on the cover to allow the enclosed liquid to flow in and out and prevent dust from flowing into the cover. A differential pressure measuring device comprising the above holes.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a highly reliable differential pressure measuring device that removes dust and does not cause a lead short circuit or the like.

[0002]

[Prior Art]

 FIG. 3 is a structural explanatory view of a conventional example which has been generally used, and is shown, for example, in Japanese Utility Model Laid-Open No. 60-181642. In the figure, a high-pressure side flange 2 and a low-pressure side flange 3 are fixed to both sides of a housing 1 by welding or the like. The high-pressure fluid inlet 4 of the pressure PH to be measured at both flanges 2 and 3 and the pressure PL An inlet 5 for the low-pressure fluid is provided. A pressure measuring chamber 6 is formed in the housing 1, and a center diaphragm 7 and a silicon diaphragm 8 are provided in the pressure measuring chamber 6.

The center diaphragm 7 and the silicon diaphragm 8 are separately fixed to the wall of the pressure measuring chamber 6, and both the center diaphragm 7 and the silicon diaphragm 8 divide the pressure measuring chamber 6 into two parts. Back plates 6A and 6B are formed on the wall of the pressure measuring chamber 6 facing the center diaphragm 7. The center diaphragm 7 has a peripheral edge welded to the housing 1. The silicon diaphragm 8 is entirely formed of a single crystal silicon substrate.

Impurities such as boron are selectively diffused on one surface of the silicon substrate to form four strain gauges 80, and the other surface is machined and etched to form a diaphragm having an overall concave shape. . The four strain gages 80 are designed so that when the silicon diaphragm 8 bends due to the differential pressure ΔP, two are pulled and two are compressed, and these are connected to the Wheatstone bridge circuit, The resistance change is detected as a change in the differential pressure ΔP. Reference numeral 81 is a lead whose one end is attached to the strain gauge 80. Reference numeral 82 is a hermetic terminal to which the other end of the lead 81 is connected.

The support 9 is provided with a hermetic terminal, and the silicon diaphragm 8 is adhesively fixed to the end face of the support 9 on the pressure measurement chamber 6 side by a method such as low-melting glass connection. Pressure introducing chambers 10 and 11 are formed between the housing 1 and the high pressure side flange 2 and the low pressure side flange 3. Separating diaphragms 12 and 13 are provided in the pressure introducing chambers 10 and 11, respectively, and a back plate having a shape similar to the separating diaphragms 12 and 13 is formed on the walls 10A and 11A of the housing 1 facing the separating diaphragms 12 and 13. -Gato is formed.

The space formed by the diaphragms 12 and 13 and the back plates 10A and 11A and the pressure measuring chamber 6 are in communication with each other through communication holes 14 and 15. Filling liquid 101, 102 such as silicone oil is filled between the separating diaphragms 12, 13, and the filling liquid reaches the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16, 17. Although 102 is divided into two by the center diaphragm 7 and the silicon diaphragm 8, it is arranged so that the amounts thereof are substantially equal.

In the above structure, when pressure acts from the high pressure side, the pressure acting on the diaphragm diaphragm 12 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. On the other hand, when the pressure acts from the low pressure side, the pressure acting on the diaphragm diaphragm 13 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102. As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured.

[0008]

[Problems to be solved by the device]

 However, in such a device, the strain gauge 80, which is a distortion-electric signal conversion element, is taken out as an electric signal, so that the lead 81 provided at the hermetic terminal 82 is taken out as shown in FIG. The signal line is connected to. In addition, the electrical signal leads are also exposed. On the other hand, the housing 1 for accommodating such a sensor is made of metal. Since the housing 1 is complicatedly processed such as screws and holes, there are many burrs and the like. In addition, dust such as spatter due to welding also exists.

In such a situation, the sensor is incorporated, and the filling liquid 101, 102 such as silicon oil is filled therein. At the time of this sealing, such dust may be moved and brought into contact with the electric lead portion 81 of the sensor. In this case, the sensor will not operate due to a short circuit or a drop in resistance. The present invention solves this problem. An object of the present invention is to provide a highly reliable differential pressure measuring device that removes dust and does not cause a lead short circuit or the like.

[0010]

[Means for Solving the Problems]

 In order to achieve this object, the present invention provides a strain-electrical signal conversion element provided in a housing made of metal, and a pressure transmission mechanism for transmitting a measurement pressure to the strain-electrical signal conversion element via an enclosed liquid. And a lead for extracting an electric signal from the strain-electrical signal converting element through the filled liquid, wherein the strain-electrical signal converting element and the lead are provided so as to cover the strain-electrical signal converting element and the lead. And a cover provided with the cover, and at least one or more holes provided in the cover to allow the enclosed liquid to flow in and out and prevent dust from flowing into the cover. It is composed.

[Action]

 In the above configuration, when pressure is applied from the high pressure side, the pressure applied to the diaphragm is transmitted to the silicon diaphragm by the enclosed liquid. On the other hand, when pressure acts from the low pressure side, the pressure acting on the diaphragm is transmitted to the silicon diaphragm by the sealing liquid. As a result, the silicon diaphragm is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically taken out by the strain gauge, and the differential pressure is measured.

Thus, most of the dust present in the housing portion has magnetism because most of it undergoes machining and welding operations. When a filled liquid such as silicone oil flows into the housing, some of these magnetic debris move due to the flow of the filled liquid and try to flow into the sensor along with the filled liquid. The liquid is allowed to flow in and out and is blocked by at least one or more holes that prevent dirt from flowing into the cover. Hereinafter, detailed description will be given based on examples.

[0012]

【Example】

 FIG. 1 is an explanatory view of the main configuration of an embodiment of the present invention. In the figure, the same symbols as those in FIG. 3 represent the same functions. Only parts different from FIG. 3 will be described below. Reference numeral 21 is a cover provided to cover the strain gauge 80 and the lead 81. Reference numeral 22 denotes at least one hole which is provided in the cover 21 and through which the enclosed liquid 102 can flow in and out and which prevents dust from flowing into the cover 21. In this case, a single body or a composite body in which the tubular portion is made of sintered metal is used. Note that a filter such as resin or paper may be used instead of the sintered metal.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the diaphragm diaphragm 12 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101. On the other hand, when the pressure acts from the low pressure side, the pressure acting on the diaphragm diaphragm 13 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102. As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured.

Thus, most of the dust present in the housing 1 is magnetized because most of it has undergone machining or welding. When the enclosed liquid 102 such as silicon oil flows into the housing 1, some of these magnetic dust moves due to the flow of the enclosed liquid 102 and tries to flow into the sensor unit together with the enclosed liquid 102. The sealed liquid 102 is allowed to flow in and out of the cover 21 and is blocked by at least one or more holes 22 that prevent dust from flowing into the cover 21 and does not reach the sensor unit. It

As a result, even if conductive dust is moved when the sensor is incorporated in the housing 1 and the encapsulating liquid 102 such as silicon oil is enclosed therein, the electrically conductive portion 81 of the sensor is electrically conductive. No contact with sex dust. Therefore, the sensor does not become inoperable due to the short circuit of the sensor or the reduction of the resistance. FIG. 2 is an explanatory view of the essential structure of another embodiment of the present invention. In this embodiment, a protective cover 31 having only passages and no fine holes is covered with a cover 21 having at least one fine hole made of sintered metal. In the above-mentioned embodiment, the sensor has been described as a semiconductor sensor. However, the sensor is not limited to this, and in short, a signal may be taken out using a lead. Further, it goes without saying that the structure of the housing 1 is not limited to this.

[0016]

[Effect of the device]

 As described above, the present invention provides a strain-electrical signal conversion element provided in a housing made of metal, and a pressure transmission mechanism for transmitting a measured pressure to the strain-electrical signal conversion element via a sealed liquid. A differential pressure measuring device comprising a lead for extracting an electric signal from the strain-electrical signal converting element through the filled liquid, wherein the strain-electrical signal converting element and the lead are provided so as to cover the strain-electrical signal converting element and the lead. A differential pressure measuring device comprising: a cover; and at least one hole which is provided on the cover and allows the enclosed liquid to flow in and out and prevent dust from flowing into the cover. did.

As a result, even if the conductive dust is moved when the sensor is built in the housing and the filling liquid such as silicon oil is filled in the housing, the conductive dust remains in the electric lead portion of the sensor. There is no contact. Therefore, the sensor does not become inoperable due to a short circuit of the sensor or a decrease in resistance. Therefore, according to the present invention, it is possible to realize a highly reliable differential pressure measuring device that removes dust and does not cause a lead short circuit or the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an explanatory view of a main part configuration of another embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a conventional example that is generally used in the past.

[Explanation of symbols]

 1 ... Housing 2 ... High-pressure side flange 3 ... Low-pressure side flange 4 ... Inlet port 5 ... Inlet port 6 ... Pressure measurement chamber 6A ... Back plate 6B ... Back plate 7 ... Center diaphragm 8 ... Silicon diaphragm 9 ... Support 10 ... Pressure introducing chamber 11 ... Pressure introducing chamber 10A ... Back plate 11A ... Back plate 12 ... Separating diaphragm 13 ... Separating diaphragm 14 ... Communication hole 15 ... Communication hole 16 ... Communication hole 21 ... Cover 22 ... Cover 22 ... Hole 31 ... Protective cover 80 ... Strain gauge 81 ... Lead 82 ... Hermetic terminal 101 ... Filled liquid 102 ... Filled liquid

Claims (1)

[Scope of utility model registration request] 1. A strain-electrical signal conversion element provided in a housing made of metal, a pressure transmission mechanism for transmitting a measured pressure to the strain-electrical signal conversion element via a sealed liquid, and the strain-electrical signal. A differential pressure measuring device comprising a lead for extracting an electric signal from a conversion element through the filled liquid, a cover provided to cover the strain-electrical signal conversion element and the lead, and the cover. A differential pressure measuring device, comprising: at least one hole which is provided in the inside of the cover to allow the enclosed liquid to flow in and out and prevent dust from flowing into the cover.