JP2001083034A - Variable-volume apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a variable-volume apparatus by which the volume of a voluminous body to be measured can be measured and a leakage tester can be calibrated with high accuracy and efficiently by a method wherein a piston inserted into a cylinder is moved freely between two stop positions to obtain a volume change of a prescribed amount. SOLUTION: A piston 120 is stopped in a stop position I with reference to a cylinder 110. Compressed air under the known same pressure P0 is supplied to a voluminous body 10, to be measured, and a reference volume body 20. Then, the volume V0 of the voluminous body 10 to be measured becomes a value obtained by adding a volume between the piston 120 and the cylinder 110 to the volume of a connection passage 111. Then, when the piston 120 is moved to a stop position II, the volume between the cylinder 110 and the piston 120 is increased by ΔV, and the pressure of the voluminous body 10 to be measured is changed to P0-ΔP, and its volume is changed to V0+ΔV. Then, when the volume V0 is known, a gas-pressure change amount ΔP is found based on the volume V0, the pressure P0 and the volume change amount ΔV, and a differential pressure gage 30 is calibrated. On the contrary, when the volume V0 is unknow, the volume V0 is found based on the known voluminous body pressure P0, the volume change amount ΔV and the gas-pressure change amount ΔP which is read out from the differential pressure gage 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable volume device used for measuring the volume of a volume to be measured and for calibrating a leak tester for detecting leakage from the volume to be measured.

[0002]

[Prior Art] In daily life, in various industrial fields, etc.,
A gas or liquid sealed in a container or the like, for example, gas, water, oil, or the like is often used. Since such leakage of gas or liquid (such as gas leakage) leads to an accident, leakage (or leakage amount) from a container or the like that stores them is strictly controlled. As a method for detecting such a leak (leak) from a container or the like (volume), a leak tester has been conventionally used. Although various leak testers have been developed, a typical one is a differential pressure type leak tester disclosed in Japanese Patent Application Laid-Open No. 48-87557.

[0003] The principle will be briefly described with reference to FIG. The differential pressure type leak tester is provided with a pressure gauge (differential pressure gauge) that reacts according to the pressure difference between the gas in the reference volume and the gas in the volume to be measured. If there is a leak from the volume to be measured, That amount appears as a differential pressure (pressure decrease),
It is detected by a pressure gauge (differential pressure gauge). In addition,
The pressure of the volume to be added may be not only a positive pressure but also a negative pressure. In the case of a positive pressure, compressed air or the like may be supplied from a compression source such as a compressor. When a negative pressure is applied, the gas in the volume may be evacuated from a pressure source such as a vacuum pump.

When the amount of leak is to be detected from the reading of the differential pressure gauge, it is necessary to measure the volume of the volume to be measured in advance. In addition, in order to properly maintain the accuracy of the differential pressure gauge of the leak tester, it is necessary to calibrate the differential pressure gauge in advance. Japanese Patent Laid-Open No. Sho 4
JP-A-8-89575 also describes a method for measuring the volume of a volume to be measured and a method for calibrating a leak tester (differential pressure gauge).

The principle will be briefly described as follows. Here, for simplicity, the working fluid is air,
The temperature was also constant. In addition, high-order minute amounts are ignored. From Boyle's law, ΔV / V ₀ = −ΔP
/ P ₀ is obtained and is transformed to obtain V ₀ = − (P ₀ / ΔP) × ΔV (Formula 1) ΔP = − (P ₀ / V ₀ ) × ΔV (Formula 2) Here, V ₀ is the volume of the volume to be measured, P ₀
Is the initial gas pressure in the volume to be measured, ΔV is the volume change of the volume to be measured (volume change in the variable volume device), and ΔP is the gas pressure change in the volume to be measured.

The "volume of the volume to be measured" refers to the volume of the volume to be measured alone, and the volume of the volume to be measured alone, the volume in the volume variable device, and the volume of the passage connecting them. Refuse to refer to the sum of However, although it depends on the volume of the volume to be measured, usually, the volume in the volume variable device and the passage volume are very small, and even if the two are not strictly distinguished, a large error occurs in the volume of the volume to be measured. It does not happen. In addition, needless to say, the above description merely describes the principle of measurement and calculation for understanding the present invention.
Correction may be required.

When the initial gas pressure P ₀ , the gas pressure change amount ΔP, and the volume change amount ΔV are known from Expression 1, the volume V ₀ of the volume to be measured can be obtained. From Equation 2, the initial gas pressure P ₀ ,
When the volume V ₀ and the volume change ΔV are known, the gas pressure change ΔP in the volume to be measured is known, and the calibration of the differential pressure gauge becomes possible. At the time of calibration, a volume having a known volume V ₀ (a reference volume or the like) is used. As described above, in order to measure the volume V ₀ of the volume to be measured and to calibrate the differential pressure gauge, it is necessary to give a known volume change ΔV to the volume to be measured.

FIG. 6 shows a conventional volume changing device 600 for giving the volume change amount ΔV. The upper half of FIG. 6 is a cross-sectional view, and the lower half is an external view thereof. The variable volume device 600 is provided with a cylinder 610 connected to the volume to be measured via an internal passage 611, a piston 620 airtightly housed in the cylinder 610, and a sleeve 680 extending from the cylinder 610. A thimble 690 can rotate the piston 620 by rotating.

The structure including the thimble 690 and the sleeve 680 is similar to a known micrometer.
That is, the thimble 69 which is screwed with the sleeve 680
By relatively rotating 0, for example, by moving the piston 620 forward and backward with an accuracy of about 0.01 mm,
The volume formed between the cylinder 610 and the piston 620 can be freely changed. This volume change amount ΔV
Can be determined by multiplying the known area of the piston 620 by the amount of movement of the piston 620 from the initial position. By converting the volume change amount ΔV in advance and engraving the corresponding scale on the sleeve 680 and the thimble 690, the calculation of the volume change amount ΔV can be omitted.

[0010] Given this known volume change amount ΔV to the volume body to be measured, the volume V ₀ which the measured volume body from Equation 1 Motomeri, gas pressure variation ΔP of the measured volume body is obtained from the formula 2. Thereby, the measurement of the volume V ₀ and the calibration of the differential pressure gauge can be performed.

[0011]

By the way, when measuring the volume of the volume to be measured or calibrating the leak tester, the measurement is repeated many times in order to improve the accuracy of the measurement result and confirm the reliability. Statistical processing of the measurement result is generally performed. For this reason, it is necessary to give the volume change amount ΔV to the volume to be measured every time measurement is performed.

However, in the case of the conventional variable volume device 600, when the thimble 690 is rotated in a certain direction to obtain the volume change ΔV, it is necessary to rotate the thimble 690 in the opposite direction to return to the initial state. is there. For this reason, even if the volume change amount ΔV is constant, when trying to collect a plurality of data at once, it is necessary to repeat this operation for each measurement, which is very troublesome and places an excessive burden on the measurer. Had been given. In particular, when the measurer obtains the volume change amount ΔV, or conversely, when returning to the initial state, the measurer must adjust the scale and read each time,
The burden is large, the measurement takes time, and it is not efficient.

[0013] In addition, although it is desired to provide a constant volume change amount ΔV with high accuracy, the volume change amount ΔV can be varied by performing the scale adjustment once and giving the volume change amount ΔV. High in nature. In this, measurement errors accumulate, faded significance of multiple measurements, it is difficult to seek such volume V ₀ which accurately measured volume thereof.

A variable volume device having a structure different from that of the variable volume device 600 and capable of efficiently providing a constant volume change amount ΔV has also been developed. This variable volume device
The piston inserted into the cylinder is driven by a separately provided drive source (motor, compressed air source, etc.) to obtain the volume change ΔV by moving the piston, or to return to the initial state. According to this variable volume device, the burden on the measurer can be reduced.

However, since this variable volume device requires a separate piston drive source, the structure becomes complicated and the device becomes large. In addition, since it is difficult to directly attach the variable volume device itself to the volume to be measured, it is necessary to connect a pipe from the volume to be measured with a flexible pipe or the like. Therefore, correspondingly, man-hours relates to redundant and also the volume of the connection pipe or the like becomes to be newly added to the volume body to be measured, also a cause for the error in the volume V ₀ which the measured volume bodies obtained.

The present invention has been made in view of such circumstances, and has been developed to efficiently measure the volume of a volume to be measured, calibrate a leak tester, and the like, and to improve the accuracy and the accuracy. It is an object of the present invention to provide a variable volume device having a relatively simple structure that can be easily performed.

[0017]

The inventor of the present invention has made intensive studies to solve this problem, and as a result, has accomplished the present invention. That is, the piston inserted into the cylinder can be freely moved between the first stop position and the second stop position without providing a drive source or the like separately, and a constant volume change amount ΔV can be efficiently achieved. The present invention has devised a variable volume device which can be obtained easily and simply.

That is, the variable volume device of the present invention includes a cylinder having a passage communicating with the inside of the volume to be measured and a connection portion detachably connected to the volume to be measured, and a cylinder which is hermetically inserted into the cylinder. A piston movable between a first stop position and a second stop position, biasing means for biasing the piston from the first stop position toward the second stop position, and a biasing force of the biasing means First stop means for stopping the piston at the first stop position against the first stop position, second stop means for stopping the piston at the second stop position when the first stop means is released, A second volume formed between the piston and the cylinder when the piston is at the second stop position; a first volume formed between the piston and the cylinder when the piston is at the first stop position; Return means for returning the piston to a volume state. And wherein the Rukoto.

In the variable volume device according to the present invention, a variable volume is formed by a cylinder and a piston inserted in the cylinder in an airtight state. The connection portion of the cylinder is connected to the volume to be measured, and the inside of the volume to be measured and the variable volume thereof communicate with each other via the passage. Therefore, when the volume formed by the cylinder and piston changes,
The pressure inside the volume to be measured changes. Also,
The connection portion of the cylinder is detachable from the volume to be measured, and the variable volume device of the present invention can be directly attached to the volume to be measured. In addition, since the passage is shortened, the dead volume is reduced, and the volume and the like of the volume to be measured can be accurately obtained.

In the variable volume device according to the present invention, the piston can be stopped at the first stop position by the first stop means. At this time, the cylinder and piston make the first
The volume is obtained. On the other hand, the piston can be stopped at the second stop position by the second stop means. At this time, a second volume is obtained by the cylinder and the piston. Here, the piston is urged by the urging means from the first stop position toward the second stop position. Therefore, if the first stopping means that stops the piston at the first stop position against the urging force is released, the piston moves to the second stop position, and the second volume is moved from the first volume state to the second volume position. Easy transition to state. Therefore, the volume change amount ΔV can be obtained simply and efficiently.

The volume variable device of the present invention further comprises:
Since the return means is provided, the state of the second volume can be easily returned to the state of the first volume. Then, when the first stopping means is released, the same volume change amount ΔV as the previous time can be obtained again. As described above, a constant volume change amount ΔV can be provided to the volume to be measured very easily, and efficient measurement can be performed. In addition, the volume change amount ΔV is determined based on the predetermined first and second stop positions,
Even if the measurement is repeated many times, the volume change amount ΔV hardly fluctuates, so that measurement accuracy and data reliability are high.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments of a variable volume device of the present invention. (Components of Variable Volume Device) (1) Cylinder A cylinder forms a wall with a piston inserted therein. As long as the piston can be moved in an airtight state, its shape is not particularly limited, such as a cylindrical shape or a rectangular cylindrical shape. It is advantageous that the dimensions of the cylinder have a cross-sectional area that facilitates calculation of the volume change amount.

Also, the cylinder has a passage communicating with the inside of the volume to be measured. Through this passage, it communicates with the inside of the volume to be measured. The shape of the passage is not particularly limited, but processing is easy if it is a circular hole. Also,
If the size and length are set to the minimum necessary, the volume and the like of the volume to be measured can be accurately obtained.

Further, the cylinder has a connecting portion for connecting the passage of the cylinder and the inside of the volume to be measured in an airtight manner. The connecting portion may be separable from the cylinder body, or may be integral with the cylinder body. In addition, a taper screw for pipe or a parallel screw for pipe may be used for the connection portion, or a connector having a well-known one-touch type socket may be used. In any case, any material can be used as long as the sealing property can be ensured. Further, the connection portion may be, for example, a screw portion provided on an outer peripheral portion of the cylinder main body, or a connection portion provided with a screw portion on a convex portion protruding from the cylinder main body.

(2) Piston The piston is inserted into the cylinder and forms a movable container wall. Since the piston is movable, a volume change amount ΔV can be obtained. The shape of the piston is not limited as long as it is airtight with respect to the cylinder. Further, the material of the piston may be made of a softer material than that of the cylinder to maintain airtightness between the sliding surfaces thereof, or a seal member such as an O-ring or a piston ring may be separately added to the piston. Further, in order to obtain smooth sliding and airtightness, a thin lubricant such as grease or oil may be applied between the sliding surfaces of the piston and the cylinder.

(3) Urging Means The urging means urges the piston from the first stop position toward the second stop position. As the urging means, for example, an elastic body (urging member) such as a spring can be used. The position where the urging member is provided may be any position. For example, it may be provided in a volume space between the piston and the cylinder, or may be provided outside the space. When provided outside the volume space, there is no need to consider the volume occupied by the urging member, and the measurement of the volume change amount becomes easy.

The biasing direction may be any direction from the first stop position to the second stop position, and the biasing force acting on the piston may be a pressing force or a traction force. For example, the biasing member may be a compression spring or a tension spring. Further, the direction from the first stop position to the second stop position may be a direction in which the volume change amount ΔV <0 or a direction in which the volume change amount ΔV> 0. In addition to the urging means, instead of using an urging member, a biasing force may be applied to the piston by applying a differential pressure to the piston. For example, if the volume to be measured is a positive pressure higher than the atmospheric pressure, the positive pressure is acting on one end of the piston, and the pressure less than the atmospheric pressure is acting on the other end of the piston, There is no need to separately provide an urging member. In this case, the pressure difference acting on the piston serves as the urging means.

(4) First Stop Means The first stop means is provided by a biasing means for moving the second stop means from the first stop position.
The piston urged toward the stop position is stopped at the first stop position. At this time, the volume formed by the cylinder and the piston becomes the first volume. The first stopping means may be any as long as it can stop and release the piston. For example, a locking member composed of a combination of a locking groove, a locking hole, a locking projection, a locking surface, and the like on the piston side and a locking piece that can be locked and released with them. The first
In order for the stopping means to always stop the piston at the determined first stop position, it is preferable that the locking member and the like eliminate rattling and improve accuracy.

Further, it is more preferable to provide an automatic stop means for automatically stopping the piston at the first stop position when the return means returns the piston from the second stop position to the first stop position. Further, it is more preferable that the first stopping means has a one-touch releasing means which can release the stop of the piston with one touch. The volume change amount ΔV can be easily given to the volume to be measured, and the load on the measurer can be remarkably reduced in the case of repeated measurement.

(5) Second Stop Means When the first stop means is released, the first stop means
The piston urged from the stop position toward the second stop position is stopped at the second stop position. At this time, the volume formed by the cylinder and the piston becomes the second volume.

The second stopping means only needs to be able to stop the piston at the second stopping position. For example, the second stopping means may be a projection or a locking piece with which the back surface of the piston abuts. If the cylinder has a bottomed cylindrical shape, the piston may be stopped at the second stop position by bringing the back of the piston into contact with the bottom. In this case, the bottom (stop surface) serves as the second stop means. As in the case of the first stopping means, in order to always stop the piston at the determined second stop position, it is preferable that the locking member and the like eliminate rattling and increase accuracy. When the piston is stopped at the second stop position by abutting, it is preferable to abut a rigid member or a stop surface.

Further, it is more preferable that the second stopping means includes a position adjusting means capable of adjusting the second stopping position so as to adjust the second volume. The position adjusting means can adjust the second stop position, which is the stop position of the piston. By providing the position adjusting means, the second volume can be adjusted according to the measured volume of the volume to be measured and the differential pressure to be generated.

The position adjusting means is provided, for example, on a suitable extension of the cylinder with projections and locking pieces which can be selectively changed at a plurality of positions, so that the rear surface of the piston comes into contact with these projections and locking pieces. It may be something that has been done. By adjusting the positions of the projections and the locking pieces, the second stop position of the piston can be appropriately adjusted. Further, on the extension of the cylinder, a multi-stage bottomed cylindrical member that can be sequentially extended may be provided. If necessary, the position of the bottom (stop surface) where the rear surface of the piston abuts is changed by stretching it, and the second position of the piston is changed.
The stop position is appropriately adjusted, and a desired second volume can be obtained.

It is more preferable that the position adjusting means is a position continuous variable means capable of continuously changing the second stop position so as to continuously change the second volume. The second volume can be continuously changed by continuously changing the second stop position by providing the position continuously changing means. Thereby, the second volume can be adjusted freely and finely. Also, the change amount of the second volume and the change amount of the differential pressure gauge of the leak tester can be continuously observed. Therefore, the measurable (operable) range and the detection sensitivity of the leak tester can also be measured.

The position continuous variable means is capable of rotating relative to the sleeve extending from the cylinder and the sleeve, and continuously moving the piston to the second stop position by moving forward and backward in accordance with the relative rotation amount with respect to the sleeve. It is preferable that the spindle comprises:

Since the relative rotation of the spindle can be converted into the advance and retreat of the spindle, a delicate change can be made when the second stop position is continuously changed.
Therefore, the accurate setting of the volume change amount ΔV can be easily performed. For example, as in the case of the structure of the micrometer, if a screwing relationship is provided between the sleeve and the spindle, the continuously variable position means can be easily obtained. In particular, if a high-grade screw is provided between them and the pitch is made fine, the second volume can be adjusted with precision and fineness. The relative rotation of the spindle may be performed manually, or may be performed using a drive source such as a small motor incorporated in the spindle or the sleeve.

(6) Returning means The returning means returns the piston from the second stop position to the first stop position, and returns the volume formed between the piston and the cylinder from the second volume to the first volume state. It is to let. For example, the piston is moved from the second stop position to the first stop position by manually pushing or pulling the extension member extending from the back surface of the piston, and the variable volume device of the present invention moves from the second volume to the first stop position. It easily returns to its volume state. Of course, a drive source such as a small motor may be incorporated in the return means, and the measurement may be automatically repeated by controlling the first stop means and the return means from a separately provided control unit.

This return means is not restricted by the second stop means. That is, the piston can be moved (returned) from the second stop position to the first stop position without changing the second stop position. Therefore, even if the piston is returned and the second volume is formed again, the second volume does not change, and a constant volume change amount ΔV can be given to the volume to be measured. As described above, since the volume variable device of the present invention has the return means, it is extremely simple to repeatedly apply a constant volume change amount ΔV to the volume to be measured.

(7) Volume to be Measured The volume to be measured to which the variable volume device of the present invention is mounted is not limited at all, and the contents thereof are not limited to gas such as air. However, it is sufficient to use air as long as the volume of the volume to be measured is measured or the leak tester is calibrated. Further, it is not always necessary to pressurize the air in the volume to be measured, and the air pressure may be maintained as long as airtightness is maintained. For example, if an urging member is provided as the above-mentioned return means, even if the initial pressure P _{0 in the} volume to be measured is the atmospheric pressure,
This is because the piston moves from the first stop position to the second stop position, and the volume change amount ΔV is generated, and the pressure change amount ΔP can be detected.

It is not always necessary to provide a reference volume in addition to the volume to be measured. A pressure gauge that can detect subtle pressure changes in the volume to be measured is directly attached to the volume to be measured, and the pressure change ΔP when the volume change ΔV is given is measured to obtain the volume of the volume to be measured. May be.

(Embodiment of Variable Volume Apparatus and Concept of Its Operation) FIG. 1 shows a variable volume apparatus 100 according to an embodiment of the present invention. FIG. 3A shows the case where the piston is at the first stop position I, and FIG. 3B shows the case where the piston is at the second stop position II.

(1) Variable Volume Device 100 The variable volume device 100 includes a cylinder 110 having a connection portion 111 connected to a connection port of the volume to be measured 10, a piston having a seal member 121 and a locking groove 122. 120
, An urging member 130 constituting an urging means, a lock member 140 constituting a first stopping means, a stopper 150 constituting a second stopping means, and a pressing member 160 constituting a returning means. One connection port of the volume 10 to be measured is connected to the connection portion 111 of the cylinder 110, and the other connection port is connected to the differential pressure gauge 30 placed between the volume 10 to be measured and the reference volume 20. The other end of the pressure gauge 30 is the reference volume 20
Are hermetically screwed together with a pipe taper screw or the like.

(2) First Stop Position I In the initial state shown in FIG. 1 (a), the compressed air source 40 is connected to both the volume to be measured 10 and the reference volume 20 through valves 41 and 42 in a communicating state. Compressed air at the same pressure P ₀ (known) is supplied. At this time, since the internal pressures of the measured volume body 10 and the reference volume body 20 are the same pressure P ₀ , the differential pressure gauge 3
A pointer of 0 indicates 0. The volume V ₀ of the volume 10 to be measured includes the volume of the volume 10 to be measured and the piston 12.
0 and the volume formed between the cylinder 110 and the volume of the passage of the connection portion 111 are included.

In this state, the valves 41 and 42 are closed, and the supply of compressed air from the compressed air source 40 is shut off. At this time, the locking portion 149 of the lock member 140 is
, The piston 120 is stopped at the first stop position I with respect to the cylinder 110. The lock member 140 in the shape of a “<” is rotatably attached to the cylinder 110 at the center thereof, and the locking portion 149 is formed by the torsion coil spring 145 so that the locking portion 149 of the piston 120 is locked. It is urged to lock on.

(3) Second Stop Position II Next, as shown in FIG. 1B, when the release lever 147 of the lock member 140 is pressed, the locking portion 149 of the lock member 140 is locked by the locking groove of the piston 120. 122 (one-touch release means). And the compression coil spring 13
The piston 120 urged by 0 smoothly moves from the first stop position I to the second stop position II. At this time, the back surface of the piston 120 and the pressing member 160 are
70, the pressing member 160 contacts the stopper 150, and the piston 120
It will stop at the stop position II.

Then, the volume between the cylinder 110 and the piston 120 of the variable volume device 100 increases by the volume change amount ΔV. The pressure of the volume 10 to be measured is P
_{At 0-} ΔP, the volume changes to V ₀ + ΔV. The pointer of the differential pressure gauge 30 touches the minus side according to this ΔP.

If V ₀ is known, ΔP is obtained by substituting it into Equation 2 together with the known P ₀ and ΔV, and the differential pressure gauge 30 can be calibrated. vice versa,
If V ₀ is unknown, ΔP is read from the pointer of the differential pressure gauge 30 and substituted into Equation 1 together with the known P ₀ and ΔV to determine V ₀ .

(4) Reset In order to reduce errors due to measurement, it is necessary to repeat this measurement and calculation. By pressing the pressing member 160 of the variable volume device 100 in the state of FIG.
The piston 120 is pushed back from the second stop position II to the first stop position I via 70, and is easily reset (returned) to the state shown in FIG. At this time, it is preferable that a portion of the locking portion 149 which comes into contact with the top surface (the left side surface in FIG. 1) of the piston 120 and the like be a smooth curved surface (automatic stop (locking)
means). The contact between the top surface (left side surface in FIG. 1) of the piston 120 and the locking portion 149 is smoothly performed, and the piston 12
In response to the return movement of 0, the lock member 140 automatically moves up. When the piston 120 reaches the first stop position I, the locking member 1 is inserted into the locking groove 122 of the piston 120.
The 40 locking portions 149 are automatically locked. Then, the piston 120 stops again at the first stop position I.

Thereafter, the operation of releasing the lock member 140 to move the piston 120 to the second stop position and the operation of returning the piston 120 to the first stop position I by the pressing member 160 are repeated, thereby obtaining the measured object. Measurement of the volume V ₀ of the volume body 10 and calibration of the differential pressure gauge 30 can be performed easily and efficiently. When the volume change amount ΔV is changed, the mounting position of the stopper 150 may be changed. For example, cylinder 110
A plurality of grooves may be provided on the inner peripheral surface of the sleeve 180 extending from the groove, and a detachable snap ring or the like may be used as the stopper 150 in the groove. Then, by appropriately changing the position of the snap ring, the volume change amount ΔV can be changed.

In the above-described variable volume device 100, the case where the volume change amount ΔV> 0 has been described, but the case where ΔV <0 may be employed. Further, the pressure P ₀ between the measured volume 10 and the reference volume 20 need not necessarily be a positive pressure, and may be an atmospheric pressure or a negative pressure as long as a differential pressure can be detected.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific examples of a variable volume device. (1) First Embodiment FIG. 2 shows a variable volume device 200 according to a first embodiment of the present invention. The upper half of the figure shows the variable volume device 2 in the initial state.
00 is a sectional view, and the lower half is an external view thereof. The variable volume device 200 includes a cylinder 210 and a piston 2
20, a compression coil spring 230, a sleeve 280,
It comprises a lock member 240 and a pressing member 260.

The cylinder 210 is a stepped cylindrical member having a small diameter portion and a large diameter portion. The small-diameter portion forms the connection part 211. The outside is connected to the connection port of the volume to be measured by a tapered pipe thread. A small-diameter connection passage 212 is squeezed inside the connection portion 211 to communicate the inside of the volume to be measured with the inside of the cylinder 210.

The inside of the large-diameter portion of the cylinder 210 has a smooth cylindrical inner surface, and forms a variable volume together with the piston 220 inserted in an airtight state. On the outside thereof, there are provided two parallel surfaces 215 corresponding to the two surface widths of the spanner used when attaching and detaching the cylinder 210 to and from the volume to be measured. Further, a female screw 228 for screwing and fixing the sleeve 280 is provided inside the other end of the large diameter portion (opposite to the small diameter portion). In the following, for convenience, the side where the cylinder 210 is attached to the volume to be measured is the tip side,
The opposite side is called the rear end.

The piston 220 is a substantially columnar member, and is inserted inside the large diameter portion of the cylinder 210.
In the center of the tip end surface of the piston 220, a cylindrical concave portion 22 is provided.
5, and a compression coil spring 230 as an urging means is provided in the concave portion 225 thereof. The compression coil spring 230 urges the piston 220 from the first stop position to the second stop position. Also, piston 2
An O-ring groove 223 for mounting an O-ring 221 as a seal member is provided on the outer peripheral portion on the distal end side of 20. The O-ring 221 keeps the space between the cylinder 210 and the piston 220 airtight. In addition,
The material of the O-ring 221 is appropriately selected depending on the type of gas or the like in the volume to be measured.

An annular locking groove 222 is formed in the outer peripheral portion on the rear end side of the piston 220. When the piston 220 is in the first stop position, the locking groove 222
Then, a locking ball 290 described later is locked. Lock groove 222
Is annular, so that there is no need to position the piston 220 in the circumferential direction, which is particularly advantageous when a plurality of locking balls 290 are arranged. Further, a female screw 226 for attaching the pressing member 260 is formed at the center of the rear end surface of the piston 220.

The sleeve 280 is a cylindrical member with a step and a bottom, and a male screw 288 is formed outside the small diameter portion on the tip side. This male screw 288 is the cylinder 210
The sleeve 280 is fixed to the cylinder 210 by being screwed with the female screw 228 of FIG. Further, a cylindrical portion 284 extends from the male screw 288 on the rear end side of the small diameter portion. At a substantially central portion of the cylindrical portion 284, a holding hole 282 for holding the locking ball 290 is formed. The holding hole 282 is
It is a conical hole having a conical surface whose diameter decreases from the outside to the inside of the cylindrical portion 284. The large diameter is larger than the diameter of the locking ball 290, and the small diameter is slightly smaller than the diameter of the locking ball 290.

Further, a large diameter portion continues from the cylindrical portion 284 to the rear end side. The large diameter portion has a bottomed cylindrical shape having a stop surface 250 constituting the second stop means at the bottom. On the outside thereof, there are provided two parallel surfaces 285 corresponding to the two surface widths of a spanner used when attaching and detaching the sleeve 280 to and from the cylinder 210. Further, an insertion hole 286 through which the pressing member 260 is inserted is provided at the center of the stop surface 250 corresponding to the rear end surface of the large diameter portion. The inside of the sleeve 280 forms the same cylindrical inner surface where both the small-diameter portion and the large-diameter portion are smooth, and is smoothly connected to the large-diameter portion of the cylinder 210. The piston 220 is inserted and movable across the inner surfaces of the cylinder 210 and the sleeve 280.

The locking member 240 includes a locking ball 290
Together with the first stopping means. The lock member 240 is a thin, substantially cylindrical member. Lock member 2
A release protrusion 247 (one-touch release means) that protrudes in a ring shape is provided on the rear end side of the outer peripheral portion of 40. Inside the lock member 240, a first inner peripheral part 241, a second inner peripheral part 242, and a third inner peripheral part 243 are provided in order from the distal end side. The inner diameter of the first inner peripheral portion 241 is substantially equal to (outer diameter of piston 220) + (outer diameter of locking ball 290) × 2.
As a result, the release projection 247 is moved to the rear end side to
When the stopping means is released, the locking ball 290 can be retracted in the annular space formed between the first inner peripheral portion 241 and the outer peripheral portion of the piston 220.

The operation when the first stop means is released by moving the release projection 247 to the rear end side is as follows. First, when the piston 220 attempts to move toward the second stop position, the locking ball 290 slightly locked in the locking groove 222 has the locking groove 22 expanded in diameter toward the outer peripheral portion.
An outer peripheral side force acts along the side wall of the holding hole 282 having the second side wall and the conical surface. Here, the lock member 24
When the lock ball 290 is moved to the rear end side via the release protrusion 247, the locking ball 290 starts to move to an annular space formed between the outer peripheral portion of the piston 220 and the first inner peripheral portion 241. The engagement with the locking groove 222 is released. When the first stop means is released in this way, the piston 220 starts moving from the first stop position to the second stop position.

The second inner peripheral portion 242 smoothly continuing from the first inner peripheral portion 241 is slidably inscribed on the outer peripheral portion of the cylindrical portion 284 of the sleeve 280. When the first stopping means is not released, the second inner peripheral portion 242 is
90 is pushed inward, and the locking ball 290 is
The locking grooves 222 are engaged with the locking grooves 222.

The third inner peripheral portion 243 following the second inner peripheral portion 242
Is slidably inscribed in the large diameter portion of the sleeve 280. An annular space formed between the third inner peripheral portion 243 and the small-diameter portion of the sleeve 280 includes a compression coil spring 24.
5 has been inserted. The distal end side of the compression coil spring 245 is in contact with a step formed between the second inner peripheral portion 242 and the third inner peripheral portion 243, and the rear end side of the compression coil spring 245 is a small-diameter portion of the sleeve 280. And a step formed between the large diameter portion.

The lock member 240 is constantly urged in the direction toward the distal end by the compression coil spring 245. First
When releasing the stopping means, it is necessary to press the release protrusion 247 of the lock member 240 toward the rear end. However, when the piston 220 is returned to the first stop position, the locking groove 222 of the piston 220 and the holding hole 28
2 and the first inner peripheral portion 2 of the lock member 240
The connection between the first inner peripheral portion 242 and the second inner peripheral portion 242 is
Is pressed inwardly to automatically lock the locking ball 290 in the locking groove 222 of the piston 220 (automatic locking means). In addition, since the lock member 240 is constantly urged toward the distal end, the first stop means is not inadvertently released.

Here, one locking ball 290 is used.
The locking member 240 has a plurality of locking balls 290 and locking grooves 22 at corresponding positions.
2. A holding hole 282 may be provided.

The pressing member 260 is a substantially rod-shaped member constituting a return means, and is inserted through the insertion hole 286 of the stop surface 250. On the tip side of the pressing member 260, the piston 22
A male screw 266 that is screwed into the female screw 226 is formed.
0 is attached. Since the rear end surface of the pressing member 260 is processed into a smooth curved surface, no burden is placed on the operator when returning the piston 220 to the first stop position. Further, the outer peripheral portion of the pressing member 260 is subjected to knurling for preventing slippage. Incidentally, since only a pressing force is applied between the pressing member 260 and the piston 220 without requiring airtightness, it is sufficient to rotate the pressing member 260 by an operator's hand and attach it to the piston 220.

(2) Second Embodiment FIG. 3 shows a volume changing device 300 according to a second embodiment of the present invention. The upper half of the figure shows the volume variable device 3 in the initial state.
00 is a sectional view, and the lower half is an external view thereof. The variable volume device 300 includes a variable volume device 200 and its configuration,
Although the operation is similar, an auxiliary piston 370 has been newly added, so that the description will be made focusing on the difference. The piston 320 is a stepped cylindrical member, and an O-ring serving as a seal member is provided on a large diameter portion, as in the first embodiment. A male screw 326 is formed on the rear end side of the small diameter portion connected to the large diameter portion.

The auxiliary piston 370 is a substantially cylindrical member having a step on its inner peripheral portion, is inserted into a sleeve 380 attached to the cylinder 310, and is arranged so as to surround a small diameter portion of the piston 320. Have been. The auxiliary piston 370 has an inner peripheral portion 371 and a female screw 376 formed therein from the distal end side, and the female screw 376 and the male screw 326 are screwed together to form the auxiliary piston 37.
0 is connected to the piston 320.

The inner peripheral portion 371 of the auxiliary piston 370
A compression coil spring 330 constituting urging means is arranged in an annular space formed between the piston and the small diameter portion of the piston 320. The distal end side of the compression coil spring 330 is in contact with a regulating ring 379 fastened between the cylinder 310 and the sleeve 380. Also, the compression coil spring 330
The rear end side is in contact with an annular step formed between the inner peripheral portion 371 and the female screw 376. This compression coil spring 3
30 urges the piston 320 from the first stop position to the second stop position via the auxiliary piston 370.

An engaging groove 322 similar to the engaging groove 222 of the first embodiment is provided on the outer periphery of the auxiliary piston 370. By providing the same first stop means as in the first embodiment, the piston 320 can be stopped at the first stop position. Further, a pressing member 360 similar to that of the first embodiment is connected to the rear end side of the auxiliary piston 370. The pressing member 360 may be provided integrally with the auxiliary piston 370, or they may be screwed together as in the first embodiment. The contact surface 375 of the auxiliary piston 370
Abuts against the stop surface 350 (second stop means) at the bottom of the sleeve 380, so that the auxiliary piston 370 stops at the second stop position.

(3) Third Embodiment FIG. 4 shows a volume changing device 400 according to a third embodiment of the present invention. The variable volume device 400 is obtained by adding a continuous position variable device as a position adjusting device to the rear end side of the variable volume device 300 according to the second embodiment. FIG.
The upper side (I) of FIG. 4 shows when the piston 420 is in the first stop position, and the lower side (II) of FIG.
0 is in the second stop position. The continuous position changing means includes a scale sleeve 880, a spindle 490, and a thimble 498.

The scale sleeve 880 is a cylindrical member connected and fixed to the rear end of the sleeve 480. A male screw 889 screwed to the female screw 489 of the sleeve 480 is formed on the outer peripheral portion on the distal end side of the scale sleeve 880. The sleeve 480 is a member corresponding to the sleeve 380 of the second embodiment, and has a shape in which a bottom portion on the rear end side of the sleeve 380 is opened and a female screw 489 is provided there. A scale 888 is engraved on the outer peripheral surface at a substantially central portion of the scale sleeve 880. The scale 888 is obtained by engraving the amount of change in the volume between the cylinder 410 and the piston 420 when the thimble 498 makes one rotation from the front end to the rear end.

Also, on the inner periphery of the scale sleeve 880,
A precision female screw 885 is formed.
Is a precision male screw 49 provided on the outer periphery of the spindle 490.
5 is screwed. The spindle 490 is a substantially cylindrical member that moves relatively to the scale sleeve 880. The relative movement amount between the spindle 490 and the scale sleeve 880 is
The pitch between the precision male screw 495 and the precision female screw 885 between them and the amount of rotation of the spindle 490 can be adjusted as needed.

A stop surface 491 with which the contact surface 475 of the auxiliary piston 470 comes into contact protrudes annularly from the distal end side of the spindle 490. Further, a cylindrical guide 497 is provided on the inner peripheral portion on the rear end side of the spindle 490 to insert a pressing member 460 extending from the auxiliary piston 470 to the rear end side. Further, a tapered surface 496 is formed on the outer peripheral portion on the rear end side of the spindle 490. Further, a female screw 494 is formed on the rear end surface of the spindle 490.

The thimble 498 is a substantially bottomed cylindrical member that rotates together with the spindle 490. A hole having a tapered surface 493 inside is formed in the bottomed portion on the rear end side. Then, the tapered surface 496 of the spindle 490
The thimble 498 from the rear end side of the spindle 490 so that the and the tapered surface 493 of the thimble 498 are in contact with each other.
It is mounted by mounting bolts 499. The outer peripheral portion on the rear end side of the thimble 498 is knurled to prevent slippage. The tip side of the thimble 498 has a thin cylindrical shape, and the inner peripheral portion thereof has a scale sleeve 8.
80 is in contact with the outer periphery. The scale on the outer peripheral surface on the tip side of the thimble 498 is also circumferentially cut. This scale is obtained by dividing the amount of change in volume when the thimble 498 makes one rotation by 50. Of course, the numerical value of the scale changes depending on the diameter (bottom area) of the piston 420 and the pitch between the precision male screw 495 and the precision female screw 885.

The variable volume device 400 is provided with the continuous position variable means constituted by such members, so that the second volume formed between the cylinder 410 and the piston 420 can be freely and delicately changed. it can. For example, when it is desired to reduce the second volume, the thimble 498 is used.
Is rotated to move the stop surface 491 of the spindle 490 toward the distal end, whereby the auxiliary piston 470 having the contact surface 475 abutting on the stop surface 491 is further restricted in the movable range to the distal end. Becomes The movement of the piston 420 integrated with the auxiliary piston 470 is also limited by the same amount. Thereby, the second volume is further reduced. Moreover, since the rotation amount of the thimble 498 can be adjusted steplessly, the second volume can be adjusted freely and finely. Conversely, if you want to increase the second volume, rotate thimble 498 in the opposite direction.
You can do the same.

After determining the second volume, the thimble 4
In order to fix the rotation of 98, a fixing means such as a clamp used for a well-known micrometer or the like may be provided. Thus, even when the measurement is repeated, the thimble does not rotate carelessly, and stable measurement can be performed while the second volume is kept constant.

[0076]

According to the variable volume apparatus of the present invention, the measurement of the volume of the volume to be measured and the calibration (calibration) of a leak tester for detecting leakage from the volume to be measured can be performed easily and efficiently. It can be carried out. In particular, it is effective for repeated measurement.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a variable volume device according to the present invention, wherein FIG. 1A shows an initial state in which a piston is at a first stop position, and FIG. Indicates when the vehicle is at the stop position.

FIG. 2 is a view showing a variable volume device according to a first embodiment of the present invention.

FIG. 3 is a view showing a variable volume device according to a second embodiment of the present invention.

FIG. 4 is a view showing a volume changing device according to a third embodiment of the present invention.

FIG. 5 shows a conceptual diagram of a general leak tester.

FIG. 6 is a view showing a conventional variable volume device.

[Explanation of symbols]

 110 Cylinder 120 Piston 130 Compression coil spring (biasing means) 140 Lock member (first stop means) 150 Stopper (second stop means) 160 Pressing member (return means)

Claims (4)

[Claims] 1. A cylinder having a passage communicating with the inside of a volume to be measured and a connection portion detachably connected to the volume to be measured, a first stop position inserted in the cylinder in an airtight state, and a second stop position.
A piston movable between a stop position, an urging means for urging the piston from the first stop position toward the second stop position, and a piston which opposes an urging force of the urging means. First stop means for stopping at the first stop position, second stop means for stopping the piston at the second stop position when the first stop means is released, and the second stop means for stopping the piston at the second stop position. The piston from a second volume state formed with the cylinder when in the first position to a first volume state formed with the cylinder when in the first stop position. A variable volume device comprising: a return unit for returning the volume. 2. The variable volume apparatus according to claim 1, wherein said second stop means includes a position adjusting means capable of adjusting said second stop position to adjust said second volume. 3. The variable volume device according to claim 2, wherein said position adjusting means is a position continuous variable means capable of continuously changing said second stop position so as to continuously change said second volume. . 4. The position continuous varying means includes: a sleeve extending from the cylinder; and a rotatable relative to the sleeve. The volume variable device according to claim 3, comprising: a spindle that continuously changes a stop position.