JP2005283374A - Apparatus for detecting gas flow rate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for detecting the flow rate of a gas, which can be inexpensively manufactured. <P>SOLUTION: A male screw part 11e for use in attachment to a gas pipe is formed on the upstream side end part of a tubular apparatus body 1. A tube body 2 is provided inside the apparatus body 1. A valve seat hole 2f is formed on the inner circumferential surface of the tube body 2. A movable member 3 is provided inside the tube body 2 so as to be capable of moving in the axial direction of the tube body 2. The movable member 3 is energized by a coil spring 6 to the downstream side so as to abut against a stopper member 7. A valve part 3a is provided on the end part at the upstream side from the valve seat hole 2f of the movable member 3. A ring-like spacing R is formed between the outer circumferential surface of the valve part 3a and the inner circumferential surface of the tube body 2. A differential pressure between the upstream side part and the downstream side part with respect to the valve part 3a of the tube body 2 is generated by the flow of the gas in the spacing R. When the differential pressure is larger than a prescribed magnitude, the valve part 3a is seated on the valve seat hole 2f. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas flow rate detection device for detecting whether or not the flow rate of a gas flowing in a gas circuit is a certain amount or more.

  Generally, when detecting whether or not the gas flow rate in a gas circuit is equal to or higher than a certain flow rate, for example, a joint is connected to the piping constituting the gas circuit, and a flow meter is connected to the joint via a rubber tube. To do. And it is made to detect whether the flow volume of the gas which flows through the inside of a gas circuit is more than fixed with a flow meter.

  The conventional detection method has a problem that an expensive flow meter is required. Further, when connecting the flow meter to the gas circuit, it is necessary to connect the joint and connect a gas pipe such as a rubber pipe to the joint, and there is a problem that the connection work is troublesome.

In order to solve the above-mentioned problem, the present invention has a device body in which a through-hole through which gas flows is formed and an attachment portion is provided at one end, and is movable in the gas flow direction in the through-hole. A movable member provided, and a movement blocking means for blocking the movement of the movable member to the downstream side with a blocking force of a predetermined magnitude, and a valve seat is provided inside the through hole, and the movable member A valve portion that is located upstream of the valve seat is provided with a valve portion that moves downstream to close the through hole by seating on the valve seat, and an outer peripheral surface of the valve portion and an inner periphery of the through hole. An annular gap that generates a differential pressure between the upstream portion and the downstream portion of the valve portion in the through-hole is formed between the surface and the gas flowing therein, When the flow rate of the gas flowing through the through hole is equal to or higher than the predetermined flow rate, The valve unit is characterized in that said movable member to be seated on the valve seat is moved to the downstream side against the blocking force of the movement preventing means.
In this case, a cylindrical body that is slidably provided in the through-hole, and in which gas flows inside, and a second movement blocking unit that blocks the downstream movement of the cylindrical body with a blocking force of a predetermined size. The valve seat is provided on the inner peripheral surface of the cylindrical body, the movable member is provided in the cylindrical body, and the annular gap is formed between the outer peripheral surface of the valve portion and the inner peripheral surface of the cylindrical body. And when the pressure of the gas acting on the cylinder and the valve part is not less than a predetermined level in a state where the valve part is seated on the valve seat, the cylinder is Therefore, it is desirable that the second movement blocking means be moved downstream against the blocking force of the second movement blocking means.
It is possible to expand and contract in the axial direction of the through-hole between the upstream end of the cylindrical body and the upstream portion of the apparatus main body, and the outer peripheral surface of the cylindrical body and the through-hole. It is desirable to provide a cylindrical seal member that prevents gas from flowing in between the inner peripheral surface.
As the second movement preventing means, urging means for urging the cylindrical body from the downstream side to the upstream side is used, and the cylindrical body resists the blocking force of the second movement blocking means by the pressure of the gas. It is preferable that the downstream end of the cylindrical body protrudes outward from the downstream end of the apparatus main body.
The movable member has a shaft portion extending from the downstream end face of the valve portion to the downstream side, and the shaft portion is movable in the axial direction at a portion downstream of the valve seat inside the cylindrical body. A guide portion having a guide hole to be inserted into the valve portion, and when the valve portion is seated on the valve seat, a downstream end portion of the shaft portion protrudes outward from a downstream end face of the guide portion. Is desirable.
A first coil spring is used as the movement preventing means, and the first coil spring is inserted into the shaft portion so that the shaft portion can be inserted and removed. It is desirable to be provided between the upstream end surface.
The guide portion is detachably attached to the cylindrical body and can be adjusted in position in the axial direction thereof, and a first coil spring is used as the movement preventing means, and the first coil spring is disposed inside the shaft portion. Is inserted between the end face on the downstream side of the valve part and the end face on the upstream side of the guide part.
A main cylinder portion in which the cylindrical body is movably provided in the through hole; and a mounting cylinder portion that is detachably mounted on the inner periphery of the main cylinder portion and can be removed from the apparatus main body through the through hole. The valve seat and the guide part are provided in the mounting cylinder part, the valve part of the movable member is disposed in the mounting cylinder part, and the annular gap is formed with the inner peripheral surface of the mounting cylinder part. It is desirable to form between the said outer peripheral surfaces of the valve part.
The inner diameter of the inner peripheral surface of the cylinder facing the outer peripheral surface of the valve portion is formed to be large on the upstream side and small on the downstream side so that the annular gap is large on the upstream side and small on the downstream side. It is desirable that it be formed.

  According to this invention having the above-described characteristic configuration, it is possible to detect whether or not the gas flow rate is equal to or greater than a certain amount based on whether or not the valve portion of the movable member is seated on the valve seat. When detecting the gas flow rate, it is only necessary to attach the attachment portion to the gas circuit.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1 to 7 show a first embodiment of the present invention. As shown in FIGS. 1 to 5, the gas flow rate detection device A of this embodiment includes a device main body 1, a cylindrical body 2, and a movable member 3.

  The apparatus main body 1 includes a main portion 11 and a holding cylinder portion 12 that is screwed and fixed to a downstream end portion (lower end portion in FIG. 3) of the main portion 11. The main portion 11 has a cylindrical shape by forming a through-hole 11a penetrating from the upstream end surface to the downstream end surface in the central portion. The through-hole 11a has an upstream small-diameter hole portion 11b and a downstream large-diameter hole portion 11c, and the small-diameter hole portion 11b and the large-diameter hole portion 11c face the downstream side. A contact surface 11d is formed. A male screw portion (attachment portion) 11 e is formed at the upstream end portion of the outer peripheral surface of the main portion 11. For example, as shown in FIG. 7, a nut N that is rotatably provided in the opening of the gas pipe G so as to be prevented from being detached is screwed into the male screw portion 11 e. Then, by tightening the nut N, the upstream end surface of the main portion 11 is pressed and fixed to the end surface of the gas pipe G via the packing P. As a result, the apparatus main body 1 is attached to the gas pipe G, and consequently the flow rate detection apparatus A is attached to the gas pipe G. In a state where the apparatus main body 1 is attached to the gas pipe G, gas is supplied from the gas pipe G to the upstream end of the through hole 11a. A tool hook portion 11 f for engaging a rotary operation tool such as a spanner is formed at an intermediate portion of the outer peripheral surface of the main portion 11. The tool hook portion 11f is formed in a hexagonal cross section, but may have an octagonal cross section or other shapes.

  The holding cylinder portion 12 has an upstream end screwed and fixed to a downstream end portion of the outer peripheral surface of the main portion 11, and a downstream end portion of the holding cylinder portion 12 is located downstream of the main portion 11. It protrudes from the end face toward the downstream side. An annular projecting portion 12 a projecting radially inward is formed on the inner peripheral surface of the downstream end portion of the holding cylinder portion 12 projecting downstream from the main portion 11. The inner diameter of the annular projecting portion 12a is set to be smaller than the inner diameter of the large-diameter hole portion 11c. In this embodiment, the inner diameter is set to be substantially the same as the inner diameter of the small-diameter hole portion 11b.

  The cylindrical body 2 has a short large-diameter portion 2a formed at the upstream end thereof, a small-diameter portion 2b formed at the remaining portion, and a step facing the downstream side between the large-diameter portion 2a and the small-diameter portion 2b. Surface 2c is formed. The large diameter portion 2a is slidably fitted to the upstream end portion of the large diameter hole portion 11c. A bellows-like bellows (seal member) that can extend and contract with little resistance in the axial direction of the through-hole 11a between the upstream edge of the through-hole 11a of the main portion 11 and the upper end surface of the cylindrical body 2 4 is provided. Therefore, the gas supplied from the gas pipe G to the through hole 11 a is actually supplied into the bellows 4. Since the gas supplied into the bellows 4 has one end of the bellows 4 hermetically fixed to the upper end edge of the through hole 11a and the other end is airtightly fixed to the upper end surface of the cylinder portion 2, the cylinder 2 The gas does not enter between the outer peripheral surface and the inner peripheral surface of the through-hole 11a, and the gas does not leak to the outside through them. All the gas supplied into the bellows 4 enters the cylinder 2.

  The downstream end of the small-diameter portion 2 b of the cylindrical body 2 protrudes downstream from the main portion 11 and is slidably fitted to the annular protruding portion 12 a of the holding cylinder portion 12. As a result, between the apparatus main body 1 and the cylindrical body 2, the inner peripheral surface of the large-diameter hole portion 11 c of the main portion 11, the inner peripheral surface of the holding cylindrical portion 12 and the annular projecting portion 12 a, and the small diameter of the cylindrical body 2. An annular space S is formed by the portion 2b and the contact surface 2c. In this space S, a coil spring (second blocking means; biasing means) 5 is accommodated. The coil spring 5 is accommodated in a compressed state, one end of which abuts against the annular protrusion 12a and the other end abuts against the step surface 2c. As a result, the cylindrical body 2 is urged upstream by the coil spring 5 and is abutted against the abutting surface 11d with an urging force (blocking force) having a predetermined magnitude. Therefore, the cylindrical body 2 is maintained in a state where it abuts against the contact surface 11d unless a force larger than the urging force of the coil spring 5 acts toward the downstream side. In a state where the upstream end surface of the cylindrical body 2 abuts against the contact surface 11 d, the downstream end surface of the cylindrical body 2 is positioned on the same plane as the downstream end surface of the holding cylindrical portion 12. Therefore, when the cylindrical body 2 moves downstream against the urging force of the coil spring 5, the downstream end of the cylindrical body 2 protrudes from the downstream end face of the holding cylindrical portion 12 to the outside.

  From the upper edge of the inner peripheral surface of the cylindrical body 2 toward the downstream side from the upstream edge, the straight hole portion 2d, the tapered hole portion 2e having a smaller diameter toward the downstream side, and the tapered hole portion 2e Valve seat holes (valve seats) 2f having small taper angles are sequentially formed. The valve seat hole 2f is connected to the downstream edge of the tapered hole 2e, and the inner diameter of the downstream edge of the tapered hole 2e and the inner diameter of the upper edge of the valve seat hole 2f are set to be the same. Has been. A support wall portion (guide portion) 2 g is formed in a portion slightly downstream from the central portion inside the cylindrical body 2. A through hole 2h is formed in the support wall 2g. Therefore, the support wall portion 2g does not hinder the gas flow in the cylindrical body 2. A protruding portion (guide portion) 2i is formed at the central portion of the downstream end face of the support wall portion 2g. The downstream end face of the projecting portion 2i is positioned on the same plane as the downstream end face of the holding cylinder portion 12 in a state where the cylindrical body 2 abuts against the contact surface 11d. A guide hole 2j penetrating from the upstream end face of the support wall 2g to the downstream end face of the protrusion 2i is formed at the center of the support wall 2g and the protrusion 2i.

  The movable member 3 includes a disc-shaped valve portion 3a and a shaft portion 3b extending from the central portion on the downstream side of the valve portion 3a toward the downstream side. The valve portion 3a is accommodated in the cylindrical body 2 upstream of the valve seat hole 2f in the cylindrical body 2 so as to be movable in the axial direction thereof. The shaft portion 3b is slidably inserted into the guide hole 2j. Therefore, the movable member 3 is movable in the axial direction (gas flow direction) of the cylindrical body 2. A coil spring (movement blocking means: first coil spring) 6 is provided between the downstream end surface of the valve portion 3a and the upstream end surface of the support wall portion 2g. The shaft portion 3b is inserted into the coil spring 6 so as to be detachable. The coil spring 6 is provided in a compressed state, one end of which abuts against the support wall 2g and the other end abuts against the valve 3a. Therefore, the movable member 3 is urged upstream by the coil spring 6, and the urging force causes the valve portion 3 a to be fixed to the stopper member 7 that is mounted at the upstream end of the tapered hole portion 2 e. It has been hit. Therefore, the movable member 3 is maintained in a state in which the valve portion 3a hits the stopper member 7 unless a force larger than the biasing force (blocking force) of the coil spring 6 acts on the movable member 3 toward the downstream side. Hereinafter, the position of the movable member 3 and the valve portion 3a at this time is referred to as an initial position. In a state where the movable member 3 is located at the initial position, the downstream end surface of the shaft portion 3b is located slightly upstream from the downstream end surface of the protruding portion 2i. The downstream end surface of the shaft portion 3b may be positioned on the same plane as the downstream end surface of the protruding portion 2i when the movable member 3 is positioned at the initial position. When the movable member 3 is located at the initial position, the outer peripheral surface of the valve portion 3a faces the inner peripheral surface on the upstream side of the tapered hole portion 2e.

  The outer peripheral surface of the valve portion 3a is formed by a tapered surface having the same taper angle as the tapered surface forming the valve seat hole 2f. The outer peripheral surface has a dimension that the valve portion 3a is in relation to the valve seat hole 2f. It is formed in the same dimension as the inner peripheral surface of the downstream end of the valve seat hole 2f so as to be seated at the downstream end. Therefore, the dimension of the outer peripheral surface of the valve part 3a is smaller than the dimension of the inner peripheral surface of the taper hole 2e. Therefore, when the movable member 3 is located at the initial position, an annular gap R is formed between the outer peripheral surface of the valve portion 3a and the inner peripheral surface of the tapered hole portion 2e. The gas that has flowed into the upstream end portion inside the cylinder 2 flows downstream through the gap R. When the gas flows in the gap R, due to the flow resistance of the gap R, the pressure of the gas in the portion downstream of the valve portion 3a in the cylinder 2 causes the gas pressure in the portion of the cylinder 2 upstream of the valve portion 3a. Lower than pressure. The valve portion 3a is pressed downstream by this differential pressure.

Here, when the movable member 3 is located at the initial position, the pressure that causes the differential pressure to push the valve portion 3a downstream is F1, and the urging force of the coil spring 6 is F2. When the flow rate of the flowing gas is equal to or higher than the predetermined flow rate,
F1> F2
Is established, the size of the gap R when the movable member 3 is located at the initial position, that is, the flow area of the gap R is set. Therefore, when the flow rate of the gas flowing inside the apparatus main body 1 (in the gas passage) is equal to or lower than the predetermined flow rate, the movable member 3 is maintained at the initial position by the coil spring 6, but when the flow rate is higher than the predetermined flow rate, It is moved downward from the initial position. When the valve portion 3a moves from the initial position to the seating position, the outer peripheral surface of the valve portion 3a sequentially faces the inner peripheral surface of the tapered hole portion 2e and the valve seat hole 2f. The inner diameter of the hole 2f decreases toward the downstream side. Accordingly, when the valve portion 3a starts to move from the initial position to the downstream side, the size of the gap R decreases accordingly, and the differential pressure gradually increases. The increase amount of the differential pressure is larger than the increase amount of the urging force of the coil spring 6 that increases as the valve portion 3a moves downstream. Therefore, the movable member 3 that has started to move downstream from the initial position momentarily moves downstream until the valve portion 3a is seated in the valve seat hole 2f.

  When the valve portion 3a is seated in the valve seat hole 2f, the tip end portion (downstream end portion) of the shaft portion 3b of the movable member 3 protrudes to the outside from the downstream end face of the protruding portion 2i. By measuring the protruding amount of the shaft portion 3b from the protruding portion 2i, it is confirmed whether or not the valve portion 3a is seated in the valve seat hole 2f, and it is confirmed that the gas flow rate is equal to or higher than a predetermined flow rate. be able to. In this case, for example, the outer peripheral surface of the intermediate portion of the shaft portion 3b is colored so that the valve portion 3a is seated in the valve seat hole 2f, and the valve seat 3a is seated in the valve seat hole 2f. Sometimes, if the colored portion protrudes from the protruding portion 2i by a predetermined length, for example, 1 mm, the valve portion 3a can be visually inserted into the valve seat hole 2f without measuring the protruding length of the shaft portion 3b. You can confirm that you are seated. Other marks may be provided instead of coloring.

  When the valve portion 3a is seated in the valve seat hole 2f, the inside (gas passage) of the cylindrical body 2 is closed. As a result, the static pressure of the gas existing upstream of the valve portion 3a acts on the cylinder 2 and the valve portion 3a. When this static pressure is larger than a predetermined pressure set by the coil spring 5, the cylindrical body 2 moves downstream against the urging force of the coil spring 5. In addition, even if the cylinder 2 moves, the valve part 3a maintains the state seated in the valve seat hole 2f. The cylindrical body 2 stops at a position where the pressing force to the downstream side due to the static pressure acting on the cylindrical body 2 and the valve portion 3 a balances the urging force of the coil spring 5. When the cylindrical body 2 moves downstream, the downstream end portion of the cylindrical body 2 protrudes from the downstream end face of the holding member 12 to the outside. By visually observing that the holding member 12 protrudes from the downstream end of the cylindrical body 2, it can be confirmed that the static pressure of the gas is equal to or higher than a predetermined pressure. In addition, as shown in FIG. 1, a plurality of scale lines L are formed at the downstream end of the outer peripheral surface of the cylindrical body 2, and the downstream end face of the holding member 12 and the scale lines L allow gas to flow. Static pressure can be measured numerically.

  As shown in FIGS. 6 and 7, for example, as shown in FIGS. 6 and 7, the gas flow rate detection device A configured as described above is configured by screwing and tightening a nut N provided at an end of the gas pipe G to a male screw portion 11e. , Attached to the gas pipe G. In this state, the flow rate of the gas flowing through the gas pipe G can be detected. Therefore, it is not necessary to perform a connecting operation such as a gas pipe, and the labor required for detecting the gas flow rate can be reduced accordingly.

  When the gas stopper K provided in the gas pipe G is opened after the flow rate detector A is attached, gas flows from the gas pipe G into the bellows 4 and then flows into the cylinder 2. The gas that has flowed into the cylindrical body 2 leaks outside through the opening R on the downstream side of the cylindrical body 2 through the gap R. If the flow rate of the gas flowing through the gap R is greater than or equal to a predetermined flow rate, the valve portion 3a immediately sits in the valve seat hole 2f. As a result, the downstream end of the shaft 3b protrudes downstream from the lower end of the protrusion 2i. By visually observing this, it can be confirmed that the flow rate of the gas flowing in the gas pipe G is equal to or higher than a predetermined flow rate. Moreover, the valve portion 3a is seated in the valve seat hole 2f almost simultaneously with the opening of the gas stopper K. Therefore, gas hardly leaks. Conversely, if the shaft portion 3b does not protrude from the protruding portion 2i even when the gas stopper K is opened, it can be seen that the flow rate of the gas flowing through the gas pipe G has not reached the predetermined flow rate. In that case, the gas stopper K is immediately closed, and it is examined whether or not there is a defect such as clogging in the pipe upstream of the gas stopper G.

  When the valve portion 3a is seated in the valve seat hole 2f, as described above, the static pressure of the gas existing on the upstream side of the cylinder body 2 and the valve portion 3a acts. When the static pressure of the gas is equal to or higher than a predetermined pressure, the cylinder 2 protrudes from the downstream end face of the apparatus main body 1. Thereby, it turns out that the static pressure of gas is more than predetermined pressure. Moreover, the magnitude of the static pressure is also known by the scale line L. As described above, according to the flow rate detection device A of this embodiment, not only the flow rate of gas but also the static pressure of gas can be measured. Therefore, even when the flow rate and static pressure of gas are detected. It is sufficient to have only the flow rate detection device A, and there is no need to carry the flow meter and pressure gauge. Therefore, worker fatigue can be reduced.

  Next, another embodiment of the present invention will be described. However, regarding the embodiment described below, only the configuration different from the above-described embodiment will be described, and the same components are denoted by the same reference numerals and the description thereof will be omitted.

  FIG. 8 shows a second embodiment of the present invention. In the gas flow rate detection device B of this embodiment, the support wall part (guide part) 2g and the protruding part (guide part) 2i of the cylinder 2 are formed separately from the other parts of the cylinder 2. ing. However, the support wall 2g and the protrusion 2i are integrally formed. The support wall 2g can be inserted into and removed from the opening on the downstream side of the small-diameter portion 2b, and the outer peripheral surface of the support wall 2g is screwed to the intermediate portion of the inner peripheral surface of the small-diameter portion 2b. Therefore, the position of the support wall 2g in the gas flow direction (the axial direction of the cylinder 2) can be adjusted as appropriate, and thereby the biasing force of the coil spring 6 against the movable member 3 can be adjusted. Further, the coil spring 6 can be replaced by extracting the support wall 2g from the cylindrical body 2 to the downstream side.

  FIG. 9 shows a third embodiment of the present invention. In the gas flow rate detection device C of this embodiment, the cylinder 2 is composed of a main cylinder portion 2A and a mounting cylinder portion 2B. The main cylinder portion 2A is slidably provided in the large-diameter hole portion 11c of the main portion 11, and is abutted against the contact surface 11d by the coil spring 5. A bellows 4 is provided between the upper end portion of the main cylinder portion 2A and the upper end portion of the through hole 11a. The mounting tube portion 2B is inserted into the inner peripheral surface of the main tube portion 2A from the opening on the upstream side thereof, and reaches the portion slightly downstream from the center from the upstream edge of the inner peripheral surface of the main tube portion 2A. The range is detachably fitted and fixed. Moreover, the mounting cylinder portion 2B can be extracted from the apparatus main body 1 to the upstream side through the inside of the bellows 4. The space between the inner peripheral surface of the main cylinder portion 2A and the outer peripheral surface of the mounting cylinder portion 2B is hermetically sealed by a seal member 8 such as an O-ring.

  Inside the mounting cylinder 2B, a straight hole 2d, a tapered hole 2f, a valve seat hole 2e, a contact wall 2g, a through hole 2h, a protrusion 2i, and a guide hole 2j are provided. Therefore, the mounting cylinder portion 2B is provided with the movable member 3, the coil spring 5, and the stopper member 7.

  According to the flow rate detection device C configured as described above, since the members necessary for detecting the gas flow rate are provided in the mounting cylinder portion 2B and unitized, the flow rate detection device C is used for gas circuits having different gas flow rates. Cases can be dealt with by exchanging the unit bodies.

  10 to 12 show a fourth embodiment of the present invention. In the gas flow rate detection device D of this embodiment, the movable member 3 has its own weight as a movement preventing means for preventing the movable member 3 from moving from the upstream side to the downstream side with a predetermined amount of blocking force. It has been adopted. Similarly, the weights of the cylindrical body 2 and the movable member 3 are employed as second movement blocking means for blocking the cylindrical body 2 from moving from the upstream side to the downstream side with a blocking force of a predetermined magnitude. Therefore, according to the flow rate detection device D, the coil springs 5 and 6 are not required, and the manufacturing cost can be reduced accordingly. However, since the weights of the movable member 3 and the cylindrical body 2 are used as the movement blocking means and the second movement blocking means, respectively, when using the flow rate detection device D, the upstream side is positioned on the lower side. It is necessary to use it so that its downstream side is positioned on the upper side. Note that when the cylindrical body 2 is moved downstream by the static pressure of the gas, the stepped surface 2c stops when it abuts against the annular projecting portion 12a of the holding cylindrical portion 12.

  13 and 14 show a fifth embodiment of the present invention. The gas flow rate detection device E of this embodiment is a modification of the flow rate detection device D, and a small diameter portion 11g is formed at the upstream end of the outer peripheral surface of the main portion 11 instead of the male screw portion 11e. ing. A ring body 9 made of an elastic material such as rubber is fitted and fixed to the outer peripheral surface of the small diameter portion 11g. The outer peripheral surface of the ring body 9 is formed as a tapered surface having a smaller diameter from the upstream side toward the downstream side. As shown in FIG. 14, the outer diameter of the upstream edge of the ring body 9 is slightly smaller than the inner diameter of the gas pipe G to which the flow rate detection device E is attached. The outer diameter at the downstream edge of the ring body 9 is larger than the inner diameter of the gas pipe G. Therefore, when the small diameter portion 11g and the ring body 9 are inserted into the inner periphery of the gas pipe G, at least the downstream end of the ring body 9 is fitted into the inner peripheral surface of the gas pipe G in a press-fit state. As a result, the flow rate detection device E is attached to the gas pipe G. As will be apparent, in this flow rate detection device E, the small diameter portion 11g and the ring body 9 constitute an attachment portion. The point which comprises an attaching part by the small diameter part 11g and a ring body is applicable also to the flow volume detection apparatuses AC which are the said 1st-3rd embodiment.

In addition, this invention is not limited to said embodiment, In the range which does not deviate from the summary, it can change suitably.
For example, in the above embodiment, the coil spring 6 or its own weight is employed as the movement preventing means for the movable member 3, but the friction resistance between the outer peripheral surface of the shaft portion 3b and the inner peripheral surface of the guide hole 2j. And the frictional resistance may be employed as the movement preventing means. The same applies to the cylindrical body 2, and a frictional resistance is generated between the outer peripheral surface of the cylindrical body 2 and the inner peripheral surface of the through hole 11 a of the main portion 11, and the frictional resistance is prevented from moving to the second position. It may be adopted as a means. ,

It is a front view which shows 1st Embodiment of this invention in the state which the movable member and the cylinder moved to the downstream side. It is a top view of the embodiment. It is sectional drawing which follows the XX line of FIG. 2 shown in the state in which the movable member was located in the initial position. It is sectional drawing similar to FIG. 3 shown in the state which the valve part of the movable member seated on the valve seat. FIG. 4 is a cross-sectional view similar to FIG. 3, showing a state in which the cylindrical body has moved downstream. It is a front view which shows the attachment condition to the gas pipe of the embodiment. It is an expanded sectional view which follows the XX line of FIG. It is sectional drawing similar to FIG. 3 which shows 2nd Embodiment of this invention. It is sectional drawing similar to FIG. 3 which shows 3rd Embodiment of this invention. It is sectional drawing similar to FIG. 3 which shows 4th Embodiment of this invention. It is sectional drawing similar to FIG. 10 shown in the state which the valve part of the movable member seated on the valve seat. It is sectional drawing similar to FIG. 10 shown in the state which the cylinder of the movable member moved to the downstream side. It is sectional drawing similar to FIG. 3 which shows 5th Embodiment of this invention. It is sectional drawing similar to FIG. 13 which shows the attachment condition to the gas pipe of the embodiment.

Explanation of symbols

A Gas flow detection device B Gas flow detection device C Gas flow detection device D Gas flow detection device E Gas flow detection device R Gap 1 Device body 2 Cylindrical body 2f Valve seat hole (valve seat)
2g Support wall (guide part)
2i Protruding part (guide part)
2j Guide hole 3 Movable member 3A Main cylinder part 3B Mounting cylinder part 3a Valve part 3b Shaft part 4 Bellows (seal member)
5 Coil spring (second movement prevention means; biasing means)
6 Coil spring (movement blocking means; first coil spring)
9 Ring body (mounting part)
11a Through-hole 11e Male thread part (mounting part)
11g Small diameter part (mounting part)

Claims (9)

An apparatus main body having a through-hole through which gas flows and an attachment portion provided at one end, a movable member provided in the through-hole so as to be movable in the gas flow direction, and a downstream side of the movable member A movement blocking means for blocking the movement of the movable member with a predetermined amount of blocking force, a valve seat is provided inside the through-hole, and a portion upstream of the valve seat of the movable member is provided downstream. A valve portion is provided that closes the through hole by moving to the side and seating on the valve seat, and gas flows between the outer peripheral surface of the valve portion and the inner peripheral surface of the through hole. As a result, an annular gap for generating a differential pressure is formed between the upstream portion and the downstream portion of the valve portion in the through hole, and the flow rate of the gas flowing in the through hole is equal to or higher than a predetermined flow rate. In this case, the pressure difference is allowed until the valve portion is seated on the valve seat due to the differential pressure. Member the gas of the flow rate detecting apparatus characterized by being moved to the downstream side against the blocking force of the movement preventing means. A cylindrical body that is slidably provided in the through-hole and through which gas flows; and a second movement blocking means for blocking the downstream movement of the cylindrical body with a blocking force of a predetermined size, The valve seat is provided on the inner peripheral surface of the cylindrical body, the movable member is provided inside the cylindrical body, and the annular gap is provided between the outer peripheral surface of the valve portion and the inner peripheral surface of the cylindrical body. When the pressure of the gas acting on the cylinder and the valve portion is not less than a predetermined level in a state where the valve portion is seated on the valve seat, the cylinder is 2. The gas flow rate detection device according to claim 1, wherein the gas flow rate detection device is moved downstream against the blocking force of the movement blocking means. It is possible to expand and contract in the axial direction of the through-hole between the upstream end of the cylindrical body and the upstream portion of the apparatus main body, and the outer peripheral surface of the cylindrical body and the through-hole. The gas flow rate detection device according to claim 2, wherein a cylindrical seal member that prevents gas from flowing in is provided between the inner peripheral surface and the inner peripheral surface. As the second movement blocking means, a biasing means for biasing the cylindrical body from the downstream side to the upstream side is used, and the cylindrical body resists the blocking force of the second movement blocking means by the pressure of the gas. 4. The gas flow rate detection according to claim 2, wherein the downstream end portion of the cylindrical body protrudes outward from the downstream end portion of the apparatus main body when moved to the downstream side. apparatus. The movable member has a shaft portion extending from the downstream end face of the valve portion to the downstream side, and the shaft portion is movable in the axial direction at a portion downstream of the valve seat inside the cylindrical body. A guide portion having a guide hole to be inserted into the valve portion, and when the valve portion is seated on the valve seat, a downstream end portion of the shaft portion protrudes outward from a downstream end face of the guide portion. The gas flow rate detection device according to any one of claims 2 to 4. A first coil spring is used as the movement blocking means, and the first coil spring is inserted into the shaft portion so that the shaft portion can be inserted and removed. The gas flow rate detection device according to claim 5, wherein the gas flow rate detection device is provided between the upstream end surface and the upstream end surface. The guide portion is detachably attached to the cylindrical body and can be adjusted in position in the axial direction thereof, and a first coil spring is used as the movement preventing means, and the first coil spring is disposed inside the shaft portion. The gas flow rate according to claim 5, wherein the gas flow rate is disposed between an end face on the downstream side of the valve portion and an end face on the upstream side of the guide portion in a state where is inserted in a removable manner. Detection device.   A main cylinder portion in which the cylindrical body is movably provided in the through hole; and a mounting cylinder portion that is detachably mounted on the inner periphery of the main cylinder portion and can be removed from the apparatus main body through the through hole. The valve seat and the guide part are provided in the mounting cylinder part, the valve part of the movable member is disposed in the mounting cylinder part, and the annular gap is formed with the inner peripheral surface of the mounting cylinder part. The gas flow rate detection device according to claim 6, wherein the gas flow rate detection device is formed between the valve portion and an outer peripheral surface of the valve portion.   The inner diameter of the inner peripheral surface of the cylinder facing the outer peripheral surface of the valve portion is formed to be large on the upstream side and small on the downstream side so that the annular gap is large on the upstream side and small on the downstream side. The gas flow rate detection device according to claim 1, wherein the gas flow rate detection device is formed.

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