JP2011089940A - Leakage measurement apparatus of gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage measurement apparatus for accurately measuring the minute quantity of a leakage in a gasket under a high-temperature condition while a pressure loss of an actual usage is reproduced. <P>SOLUTION: Both surfaces of the gasket A are pinched by a supporting member and a pressing member in the thickness direction. While the gasket is heated, a gas is injected from a gas injection path connected to an inner sealed space on the inside diameter side of the gasket, and discharged from a gas discharge path. A flow rate of the gas supplied from the gas injection path is measured by a first mass flowmeter. A flow rate of the leak gas is measured by a second mass flowmeter provided in the leak gas discharge path connected to an outer sealed space. The flow rate of the leak gas is measured by providing a gas pressure setting means for setting a holding pressure on the gas discharge side in the gas discharge path while a pressure in a seal plane corresponding to the pressure loss of the actual usage is reproduced. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a gasket leakage measuring apparatus, and more particularly to an apparatus for measuring gasket leakage under high temperature conditions.

  Conventionally, Patent Literatures 1 to 3 have been proposed as gasket leakage measuring devices. The leak measurement apparatus of Patent Document 1 includes a flange on which a gasket is mounted, a pressurizing unit that applies pressure to the flange, a heating unit that accommodates the flange on which the gasket is mounted and heats it to a predetermined temperature, and a leak test gas in the gasket. A pipe for sending a gas, a gas supply means for leak test for supplying a gas for leak test to the pipe, and at least one mass for measuring a mass flow rate of the gas for leak test outside the heating means and flowing in the pipe A flow meter.

  In this leak measurement apparatus, since the setting portion of the gasket is sealed, the pressure applied to the gasket must be adjusted on the primary side of the gasket. With this device, it is difficult to strictly control the pressure applied to the gasket. Since the bolt is used as the pressurizing means, there is a problem that the fastening force cannot be quantified and the amount of leak cannot be measured while changing the surface pressure applied to the gasket.

  The leak measurement device described in Patent Document 2 arranges an annular test metal gasket between the peripheral portions of the metal flange members arranged opposite to each other, and tightens a plurality of bolts provided along the peripheral portion of the metal flange member. Thus, the test metal gasket is held between the metal flange members with a predetermined tightening force. The metal gasket and the test metal flange member clamped with a predetermined tightening force are heated in a heating furnace at a predetermined temperature for a predetermined time to heat deteriorate the test metal gasket, and at least one of the bolts during the heat deterioration. The reduction of the clamping force is measured by a strain gauge provided on the test piece, and the stress relaxation characteristics of the test metal gasket are evaluated.

  Since this leakage measuring apparatus also uses bolts, the surface pressure applied to the gasket cannot be changed as in Patent Document 1. In addition, since the leakage test is performed after the gasket is once heated and deteriorated, the exact temperature condition is not reproduced under the gasket operating temperature.

  Patent Document 3 discloses an inlet gas constant supply device that continuously supplies gas at a constant flow rate from the inlet side of an object to be inspected during an airtight inspection, and an outlet gas flow rate that measures a passing gas flow rate at the outlet side of the object to be inspected And a gas leak evaluation apparatus for performing an airtight inspection of an object to be inspected with a decrease amount of a passing gas flow rate. The outlet gas flow rate measuring apparatus has a pressurizing device connected to the inspection object outlet side. Using the fact that the internal pressure of the object to be inspected is varied by the pressurizing device and the amount of leakage at that time increases in proportion to the pressure, the outlet flow rate value for this pressure is obtained at two or more points, The leak inspection is performed from the gradient.

  This evaluation apparatus is for quantifying the amount of gas leak at a high temperature of the SOFC cell unit and evaluating the cell performance. In this method, the leak amount is obtained from the gas decrease amount. This is not the actual detection of the leak amount. Therefore, when the leak amount is about 1% or less of the total flow rate, the leak amount detection method using the gas flow reduction amount as in Patent Document 3, Low reliability.

JP 2001-66216 A JP 2002-364749 A JP 2006-170918 A

  An object of the present invention is to provide a leakage measuring apparatus capable of accurately measuring a minute leak amount of a gasket under a high temperature condition while reproducing a pressure loss in actual use.

  In order to achieve the above object, the present invention pressurizes the supporting member for supporting one surface in the thickness direction of the gasket and the other surface in the thickness direction of the gasket to form an inner sealed space on the inner diameter side of the gasket. A pressure member, a heating means for heating the gasket, a gas input path connected to the inner sealed space, and a flow rate of the gas provided in the gas input path and supplied from the gas input path are measured. A first mass flow meter that performs gas flow, a gas discharge path connected to the inner sealed space, a gas pressure setting means that is provided in the gas discharge path and sets a holding pressure on the gas discharge side, and an outside of the gasket An airtight container for forming an outer sealed space sealed on the diameter side, a leak gas discharge path connected to the outer sealed space, and the leak gas discharge path provided in the leak gas discharge path Providing leakage measuring device of the gasket, characterized in that it includes a second mass flow meter for measuring the flow rate of the leak gas flowing through the scan discharge path, the.

  Both surfaces of the gasket are sandwiched between the support member and the pressure member, and gas is supplied to the inner sealed space formed on the inner diameter side of the gasket through the gas input path. The flow rate of the supplied gas is measured by the first mass flow meter. A part of the supplied gas leaks to the outer sealed space through the gap between the gasket and the support member or the gap between the gasket and the pressure member, and the leaked gas is collected in the outer sealed space. The leak gas passes through the leak gas discharge path connected to the outer sealed space, and the flow rate is measured by the second mass flow meter. The leak rate can be obtained from the measured value of the first mass flow meter and the measured value of the second mass flow meter.

  In Patent Documents 1 and 2, since only the gas inlet (primary side) is provided with respect to the seal space, the in-seal pressure corresponding to the pressure loss during actual use cannot be reproduced. On the other hand, in the present invention, not only the gas input path (primary side) but also the gas discharge path (secondary side) is connected to the inner space of the gasket, and the gas pressure setting means sets the holding pressure on the gas discharge path side. Therefore, by setting the holding pressure in consideration of the pressure loss during actual use, it is possible to reproduce the process of flowing gas through the gasket through the device. As the gas pressure setting means, a member having a pressure loss equivalent to that of an actual device may be used in addition to the pressure adjustment valve. That is, it becomes possible to connect a device to the secondary side, and it is possible to reproduce the seal surface pressure corresponding to the actual pressure loss.

  It is desirable to provide a pressure drive mechanism that is connected to the pressure member, pressurizes the gasket in the thickness direction, and can vary the pressure. In this case, since the surface pressure of the gasket can be continuously adjusted by the pressurization driving mechanism, the minute flow rate of the leak gas can be measured while changing the surface pressure of the gasket.

  It is desirable to provide a heating means for heating the gasket on the support member or its periphery. The heating means may be provided on the pressure member side, but in that case, the surface pressure of the gasket may change due to the influence of thermal deformation of the pressure member. On the other hand, by providing the heating means on the support member side, it is possible to reduce the thermal effect on the pressure member and suppress variations in surface pressure.

  It is desirable to provide a temperature sensor for measuring the temperature applied to the gasket on the support member and the pressure member. Since the temperature of the gasket cannot be directly measured, the temperature in the vicinity of the gasket can be detected by providing a temperature sensor on the support member and the pressure member sandwiching both surfaces of the gasket and measuring the temperature.

  It is desirable to connect the pressure driving mechanism and the pressure member through a universal joint that transmits only the axial load. The pressure drive mechanism and the pressure member may be directly connected, but if the direction of the pressing force of the pressure drive mechanism or the pressure member is inclined, a vertical load cannot be applied to the gasket. Therefore, by connecting the pressure member and the pressure drive mechanism via a universal joint such as a ball joint, even if the perpendicularity of the axis of the pressure member or the pressure drive mechanism with respect to the gasket is not strictly output, Since the pressing surface of the pressurizing member is corrected so as to be parallel to the gasket, the gasket can be uniformly pressed and an appropriate surface pressure can be applied.

  As described above, according to the leakage measuring apparatus of the present invention, the leakage gas from the gasket is collected in the outer sealed space, and the leakage gas flow rate is measured by the second mass flow meter. It can be measured. In addition, not only the gas input path but also the gas discharge path is connected to the inner space of the gasket, and the gas pressure setting means for setting the holding pressure is provided on the gas discharge path side, so that the pressure loss during actual use is reproduced. The leak gas flow rate can be measured with high accuracy.

It is a figure which shows the leak measuring apparatus which concerns on this invention. It is detailed sectional drawing of the main-body part of the leak measuring apparatus which concerns on this invention. It is an expanded sectional view of the principal part of FIG. It is the result of having calculated | required the leak rate from a gasket when changing a gasket surface pressure and changing the pressure loss value of a secondary side. FIG. 5 is a graph of FIG. 4.

  1 to 3 show a first embodiment of a leakage measurement apparatus for gasket A according to the present invention. The leak measurement apparatus of the present embodiment includes an airtight container 1 composed of a pair of upper and lower cases 1a and 1b. By fastening the flange portions of the upper and lower cases 1a and 1b with fastening members 2 such as bolts, An outer sealed space 3 is formed inside the airtight container 1. The outer side means that the outer side is seen from the gasket A. Thus, the airtight container 1 has a structure that can be divided while ensuring airtightness. A support member 4 that supports the upper surface of the gasket A is fixed to the inner surface of the ceiling portion of the airtight container 1. A heating device 5 equipped with a heater 6 is attached to the outer surface of the upper case 1a, and the heat of the heating device 5 is conducted to the support member 4 through the upper case 1a. Therefore, the gasket A and its peripheral part can be heated to an arbitrary temperature from room temperature to 1000 ° C. The gas input path 7 and the gas discharge path 8 are connected so as to pass through the heating device 5, the upper case 1 a, and the support member 4 and open to the lower surface of the support member 4.

  A gas (for example, He gas) is supplied from a gas cylinder 9 to the gas input path (primary side) 7 and its primary pressure is adjusted by a pressure adjusting valve 10 such as a regulator. The primary pressure is detected by the pressure gauge 11. Further, the input gas amount is adjusted by the flow rate adjusting valve 12, and the flow rate is detected by the first mass flow meter 13.

  The end of the gas discharge path (secondary side) 8 is open to the atmosphere. The gas discharge path 8 is provided with a pressure gauge 14 for detecting a secondary pressure (pressure loss) and a pressure adjusting valve 15 for adjusting an internal pressure applied to the gasket A on the downstream side thereof. Instead of the pressure regulating valve 15, a member having a pressure loss assuming an actual machine (device) may be attached to the secondary side. Thus, the gas introduced into the internal space of the gasket A is continuously introduced by being introduced from the gas introduction path 7 (primary side) and released to the atmosphere through the gas discharge path 8 (secondary side). Can be flushed.

  Inside the hermetic container 1, a pressurizing member 20 is disposed so as to be movable up and down, and a gasket A to be measured is disposed between the upper surface of the pressurizing member 20 and the lower surface of the support member 4. Therefore, as shown in FIG. 3, an inner sealed space 21 is formed on the inner diameter side of the gasket A. The length of the pressure member 20 is sufficiently longer than the height reached by the heating device 5, and the lower end thereof extends to the lower case 1 b and is supported by the connection member 22. The shaft portion 22a of the connecting member 22 penetrates the bottom portion of the lower case 1b so as to be slidable. By providing an O-ring 23 on the sliding portion, the connecting member 22 moves up and down while ensuring airtightness of the airtight container 1. Can be slid. Since the connecting member 22 is away from the heating device 5, the connecting member 22 and the O-ring 23 can be installed in an environment below the heat resistant temperature. The connecting member 22 is provided with a joint 24 such as a ball joint. Even when the direction of the pushing force of the shaft portion 22a is not perpendicular to the seal surface of the gasket A, the upper surface of the pressurizing member 20 is supported by the joint 24. Since the correction is automatically made to be parallel to the seal surface, the seal surface can be pressed evenly.

  A shaft 25a of a pressure driving mechanism 25 such as an air cylinder is connected to the shaft portion 22a of the connection member 22 protruding outside the airtight container 1. Therefore, when the pressure driving mechanism 25 is operated, the pressure can press the gasket A as a vertical load via the connection member 22 and the pressure member 20. The pressure driving mechanism 25 can arbitrarily adjust the surface pressure applied to the gasket A from, for example, 10 kPa to 100 kPa by adjusting the supply pressure to the cylinder.

  Thermocouples 26 and 27 are attached to the support member 4 and the pressure member 20, respectively, and these thermocouples are provided outside the apparatus via external terminals 28 and 29 provided on the side wall of the airtight container 1. It is connected to a regulator (not shown). The temperature near the gasket A can be set to a desired temperature by detecting the temperature near the gasket A with the thermocouples 26 and 27 and adjusting the output to the heating device 5 via the output regulator. A leak gas discharge path 30 for opening the outer sealed space 3 to the atmosphere is connected to the lower side surface of the hermetic container 1 that is not affected by heat from the heating device 5. A second mass flow meter 31 for measuring the flow rate of the leak gas flowing through the path is provided. The accuracy of the first and second mass flowmeters 13 and 31 is preferably about 1% full scale.

  Here, the operation of the leakage measuring apparatus having the above-described configuration will be described. First, before the measurement, a correlation between the pressing pressure of the pressure driving mechanism 25 and the surface pressure applied to the gasket A is obtained. Therefore, a load detector (not shown) such as a load cell is set between the support member 4 and the pressurizing member 20 at room temperature, and the detection data of the load detector is read while operating the pressurization drive mechanism 25. . After obtaining the correlation between the pressing pressure of the pressure drive mechanism 25 and the surface pressure of the gasket A, the load detector is removed.

Next, an actual leakage measurement procedure will be described.
(1) The gasket A is set between the support member 4 and the pressure member 20, and the airtight container 1 is sealed.
(2) The heating device 5 is set, and the gasket A and its surroundings are heated to a predetermined temperature (for example, 800 ° C.) by the heating device 5.
(3) Based on the correlation between the pressing pressure and the surface pressure obtained in advance, the pressing pressure of the pressure drive mechanism 25 is adjusted so that the surface pressure of the gasket A becomes a predetermined value (for example, 10 kPa).
(4) Gas is supplied from the gas input path (primary side) 7 to the inner sealed space 21. Then, the pressure loss on the secondary side is changed to, for example, 0 to 30 kPa by the pressure adjusting valve 15. The pressure loss is measured with a secondary pressure gauge 14.
(5) The primary mass flow meter 13 measures the primary input flow rate, and the second mass flow meter 31 measures the leak gas flow rate. Since the gas leaking from the gasket A is collected in the outer sealed space 3, the flow rate of the leak gas can be directly measured by the second mass flow meter 31. Since the accuracy of the first and second mass flowmeters 13 and 31 is about full scale ± 1%, even when the leak amount is about 1% or less of the total flow rate, it can be measured with high accuracy.
(6) Repeat steps (3) to (5) in the same way for gasket surface pressures of 30, 50 and 70 kPa.

Next, an experiment in which the leakage amount of the gasket was measured using the leakage measurement apparatus having the above-described configuration will be described. The experimental conditions are as follows.
・ Gas type: He
-Input gas volume: 5 NL / min (NL: normal liter: volume at standard condition (0 ° C, 1 atm))
・ Heating temperature: 800 ℃
・ Gasket-Material: Vermiculite (thickness: 0.5mm, inner diameter 80mm, outer diameter 90mm)
・ Full scale of the first mass flow meter: 20LM (LM: l / min)
・ Full scale of the second mass flow meter: 200 CCM (CCM: ml / min)

FIG. 4 shows a case where the pressure loss value on the secondary side is changed to 0 to 30 kPa under the conditions where the surface pressure is 1.02E-05, 3.059E-05, 5.099E-05, and 7.138E-05 Pa. The leak rate (%) from the gasket was obtained. The leak rate was calculated by the following formula.
Leak rate = J value / L value x 100
J value: Measurement value of the first mass flow meter
L value: Measurement value of the second mass flow meter

  As is clear from FIG. 4, the amount of leak in a state where the seal surface pressure and the pressure loss were changed could be accurately measured. That is, it was possible to detect even a leak rate of 1% or less of the supply gas amount in a state where the conditions concerning the actual leak portion were strictly reproduced.

  FIG. 5 is a graph of FIG. A surface pressure of 1.02E-05 Pa corresponds to a surface pressure of 1 kgf. As can be seen from FIG. 5, when this gasket is used at 800 ° C. and the leak rate is 1% or less, the seal surface pressure needs to be 3 kgf or more.

A Gasket 1 Airtight container 3 Outer sealed space 4 Support member 5 Heating device 7 Gas supply path (primary side)
8 Gas discharge route (secondary side)
DESCRIPTION OF SYMBOLS 10 Pressure regulating valve 11 Pressure gauge 12 Flow regulating valve 13 1st mass flow meter 14 Pressure gauge 15 Pressure regulating valve (gas pressure setting means)
20 Pressurizing member 21 Inner sealed space 24 Joint 25 Pressurizing drive mechanism 26, 27 Thermocouple 30 Leak gas discharge path 31 Second mass flow meter

Claims (5)

A support member that supports one surface of the gasket in the thickness direction;
A pressure member that pressurizes the other surface in the thickness direction of the gasket to form an inner sealed space on the inner diameter side of the gasket;
Heating means for heating the gasket;
A gas input path connected to the inner sealed space;
A first mass flow meter provided in the gas input path for measuring the flow rate of the gas supplied from the gas input path;
A gas discharge path connected to the inner sealed space;
A gas pressure setting means provided in the gas discharge path for setting a holding pressure on the gas discharge side;
An airtight container for forming an outer sealed space sealed on the outer diameter side of the gasket;
A leak gas discharge path connected to the outer sealed space;
A gasket leakage measurement apparatus comprising: a second mass flow meter provided in the leak gas discharge path and measuring a flow rate of the leak gas flowing through the leak gas discharge path.   The gasket leakage measurement device according to claim 1, further comprising a pressure drive mechanism connected to the pressure member and configured to pressurize the gasket in a thickness direction and change a pressure.   The gasket leakage measuring apparatus according to claim 1 or 2, wherein the heating means is provided on or around the support member.   4. The gasket leakage measuring device according to claim 1, wherein a temperature sensor for measuring a heating temperature applied to the gasket is provided on the support member and the pressure member.   The gasket leakage measurement apparatus according to any one of claims 1 to 4, wherein the pressure driving mechanism and the pressure member are connected via a universal joint that transmits only an axial load.

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