JP5528309B2 - Backfire prevention device - Google Patents

Description

  The present invention is applied to a device for supplying a flammable gas such as hydrogen gas that may explode, a supply passage for piping, etc., and reliably shuts off the flammable gas when a backfire occurs on the gas lead-out side. In addition, the present invention relates to a backfire prevention device that can prevent a sudden return.

Conventionally, for example, as a backfire preventer capable of stopping the backfire generated on the gas outlet path side where the torch or the like is located and shutting off the flammable gas, a dry backfire preventer as shown in Patent Document 1 is available. It is disclosed.
This dry backfire preventer has a shut-off valve body constituted by a spool valve fitted in a gas supply passage formed in a shut-off valve holder in a case member so as to be movable back and forth. A check valve body biased by a check valve spring is brought into contact with a check valve seat formed on the lead-out side end).

The tip of the leg of the shut-off valve body (on the gas introduction path side) is attached to the shut-off valve holder, and protrudes from the case member to the outside during the flashback operation.
In addition, a ball that is in contact with the peripheral surface of the leg of the shut-off valve body is mounted on the movement path of the leg part of the shut-off valve body so that the contact pressure can be changed by the operating pressure adjusting mechanism, A recess for receiving a ball on the case member side during backfire operation is formed in the leg surface of the valve body.
With this configuration, at the time of backfire operation, the shut-off valve body is fixed in a state where the gas supply path in the case member is shut off by the ball fitted in the recess of the peripheral surface of the leg portion of the shut-off valve body. The introduction of combustible gas is forcibly cut off.

Japanese Patent Laid-Open No. 2005-240840

  By the way, in the backfire preventer shown in the above-mentioned Patent Document 1, since the case member-side ball is in a structure in which the ball is in contact with the leg portion peripheral surface of the shut-off valve body, that is, the ball is a rollable structure, Even if the contact pressure is adjusted by the adjusting screw of the operating pressure adjusting mechanism, there is a possibility of malfunction due to looseness of the screw.

  Specifically, for example, when the adjustment screw of the operating pressure adjustment mechanism is loosened, the supply pressure of the flammable gas is reduced, and the check valve body is turned off by the biasing force of the check valve spring. If it comes into contact with the check valve seat, the pressure is transmitted to the shut-off valve body, and the shut-off valve body may malfunction.

  Also, for example, in the case of hydrogen gas or a mixed gas containing a large amount of hydrogen, after the explosive combustion at the torch side during backfire, the pressure before the explosion is negative, so it becomes negative pressure. If the adjustment is not sufficient, the backfire preventer may automatically return to both the check valve and the shutoff valve due to the pressure drop after the backfire.

  Further, the backfire preventer described in Patent Document 1 is a shut-off valve body when the adjusting screw of the operating pressure adjusting mechanism is excessively tightened and the explosive force during backfire on the torch side is small. May not operate normally, and the supply of combustible gas may not be shut off.

  In addition to the cited document 1, there is also disclosed a technique of pressing the shut-off valve body with a lock pin and releasing the locked state with the shut-off valve body by pushing up the lock pin when backfire occurs. In the configuration, there is a possibility that the unlocking operation of the lock pin may vary depending on the explosion state and size of the backfire, and there is a possibility that sufficient reliability cannot be ensured.

  In order to eliminate the malfunction of the shut-off valve body of the backfire preventer as described above and improve the reliability, it operates only after the desired pressure is applied, and once it is activated, it remains in the shut-off state Thus, there has been a strong technical demand for a shut-off mechanism that can prevent an unexpected return.

  The present invention has been made in view of the circumstances described above, and even when the supply pressure of the combustible gas is reduced and the explosive power of the backfire on the gas outlet side is small, the combustible gas can be reliably shut off. And it aims at providing the backfire prevention device which can prevent an unexpected reset.

In order to solve the above problems, the present invention proposes the following means.
The invention according to claim 1 includes a case member having a hollow portion connected to a gas introduction path to which a combustible gas is supplied and a gas lead-out path from which the combustible gas is derived, A check that is provided so as to be movable in the axial direction of the hollow portion and that is biased toward the gas introduction path and moves to the side that closes the gas introduction path when the gas introduction pressure is relatively lowered. A backfire prevention mechanism that is provided in a hollow part in the case member and moves to the side that closes the check valve by a pressure caused by explosion from the gas lead-out path, The backfire prevention mechanism is provided so as to be movable in the axial direction of the hollow portion, and when receiving a pressure due to an explosion during backfire, a pressure sensor that moves toward the gas introduction path, and an axis of the hollow portion It can be moved freely in the direction and When the child moves to the gas introduction path side, it moves in the axial direction of the hollow portion between the rod that is pressed by the pressure sensitive element and moves to the gas introduction path side, and the rod and the check valve A mover that is freely provided and moves the check valve toward the gas introduction path when the rod is pressed, and closes the gas introduction path; A rolling member that can roll while being in contact with the moving element between an inner circumferential surface of the member and an outer circumferential surface of the rod, and a blocking spring that biases the rolling member toward the gas introduction path A step portion is formed on the inner peripheral surface of the case member for locking the rolling member and restricting the urging force of the blocking spring from being transmitted to the moving element during normal operation. In addition, a backfire occurs on the outer peripheral surface of the rod, and the rod There when moving to the gas introducing path side, wherein the groove for locking the rolling member is formed with releasing the engagement by the stepped portion of the rolling member.

According to the backfire preventer according to the present invention, when backfire occurs on the gas outlet side, the pressure sensor moves with the pressure of backfire, and the movement of the pressure sensor is transmitted to the rod. When the rod moves, the rolling member fits into the groove of the rod, the rolling member and the rod locked to the stepped portion become movable in the axial direction, and the urging force of the blocking spring moves via the rolling member. A backfire prevention mechanism is actuated by being transmitted to the child and the check valve.
As a result, unless a backfire pressure is applied, the backfire prevention mechanism does not operate, and even if the supply pressure of the combustible gas decreases, the check valve malfunction due to vibration or the like is prevented.
Further, according to the flashback preventive device, since the rolling member is normally locked to the step formed on the inner peripheral surface of the case member, an explosion due to flashback occurs and a pressure higher than a predetermined level is applied. The rolling member is released from the stepped portion, and the shut-off spring is extended only when the pressure sensor moves to the position where the rolling member fits into the groove of the rod. The check valve closes the gas introduction path and the rod is held in that position.
As a result, when the pressure of the explosion due to backfire does not reach a predetermined pressure, the backfire prevention mechanism does not operate, so that the malfunction is suppressed, and the held rod and check valve are fixed in the reverse direction. Unless the force is loaded, the gas does not move to the gas outlet side, so that the interruption is prevented from returning unexpectedly.

  The invention according to claim 2 is the flashback prevention device according to claim 1, wherein the rolling member is a sphere.

  According to the backfire preventer according to the present invention, since the rolling member is a sphere, it rolls stably, and as a result, the operational reliability as the backfire preventer can be improved.

According to the backfire preventer according to the present invention, when an explosion due to backfire occurs, the supply of combustible gas can be reliably shut off, and the shutoff state can be reliably maintained after the shutoff.
As a result, the reliability of the backfire preventer can be improved.

It is a front sectional view showing a backfire preventer in a normal state. It is a front sectional view showing a backfire preventer during backfire. It is a front sectional view showing a backfire preventer when a reset bar for returning from a backfire state to a normal state is inserted.

A backfire preventer according to an embodiment of the present invention will be described with reference to FIGS.
A backfire preventer according to an embodiment is provided in a path for supplying a combustible gas (for example, hydrogen gas) to a gas cutting machine. In FIG. 1 is a cap coupled to the right end of FIG. 1, numeral 3 is a filter receiver for holding a rod 23 and a pressure sensor 24 (described later) provided in the valve body 1, and numeral 4 is a valve body. The sintered metal provided between the cap 2 and the filter receiving member 3 in 1 is shown.
The case member 100 includes a valve main body 1, a cap 2, a filter receiving member 3, and a sintered metal 4. A nut 5 for connecting to a pipe or a pressure reducing valve (not shown) is screwed to the right end portion of the cap 2 in the drawing.

  A hollow portion 10 serving as a gas supply path for combustible gas is formed along the axis A inside the valve main body portion 1, the cap 2, and the filter receiving member 3 constituting the case member 100. A gas introduction path 11 is formed at the right end in the figure, and a gas outlet path 12 is formed at the left end in the figure.

In the hollow portion 10, a check valve 20, a mover 21, a stainless ball (rolling member) 22, a rod 23, and a pressure sensor are provided along the gas supply direction (arrow a direction) of the combustible gas along the axis A. 24 are sequentially arranged.
The check valve 20, the moving element 21, the stainless ball 22, the rod 23, and the pressure sensitive element 24 are provided so as to be movable along the axis A in the directions of arrows ab.

The check valve 20 is urged in a direction indicated by an arrow b opposite to the gas supply direction a by a check valve spring 25 including a compression spring disposed between the checker 20 and the arrow a. When the flammable gas supply pressure to the valve 2 decreases, the urging force of the check valve spring 25 makes contact with the check valve seat 2A on the cap 2.
Further, an O-ring 20A is provided on the gas introduction path 11 side of the check valve 20, and when the check valve 20 moves in the direction of the arrow b, the O-ring 20A is attached to the check valve seat 2A on the cap 2. The gas introduction path 11 is closed by abutting and intimate contact.

The mover 21 is formed in a U-shaped body in a cross-sectional view. One end portion 23A of the rod 23 is inserted into the recessed portion 21A of the U-shaped body, and the rod 23 moves in the direction of the arrow b. It comes into contact with the bottom.
The rod 23 has a smooth peripheral surface 23B in the vicinity of one end 23A on the arrow b side, and a groove 23C is formed in the middle of the peripheral surface 23B. The stainless ball 22 is fitted into the groove 23C. It is like that.

  The stainless steel ball 22 is provided between the peripheral surface 23B of the rod 23 and the inner peripheral surface of the filter receiving member 3 so as to be able to roll in the direction of the arrow ab. It fits into the step 3A formed on the inner peripheral surface of the receiving member 3, and when it rolls in the direction of the arrow b, it fits into the groove 23C of the rod 23.

  In addition, the stainless steel ball 22 is normally fitted into the stepped portion 3A of the filter receiving member 3 and is in contact with the peripheral surface 23B of the rod 23, and during backfire (moves in the direction of arrow b). After fitting into the groove 23C of the rod 23, the rod 23 rides on the smooth portion 3B connected to the step portion 3A from the step portion 3A of the filter receiving member 3 and rolls.

A washer 26 that contacts the stainless steel ball 22 is provided on the outer periphery of the rod 23 in the hollow portion 10.
The washer 26 holds the rod spring 27 between the spring fixing portion 23D of the rod 23 located in the vicinity of the pressure sensor 24, and the other end 23E of the rod 23 is pressed against the pressure sensor 24 by the rod spring 27. It has become.

Further, between the rib 3C located on the arrow a side of the filter receiving member 3 and the washer 26, a blocking spring 28 for biasing the stainless ball 22 in the arrow b direction is provided via the washer 26. ing.
In this embodiment, for example, the rod spring 27 and the cutoff spring 28 are both compression springs, and the spring force of the cutoff spring 28 is set stronger than that of the rod spring 27.

  The pressure sensor 24 is held by the filter receiving member 3 through the O-ring 29 and is in contact with the other end 23E of the rod 23. The pressure sensor 24 is structured to receive the explosion pressure at the time of backfire on the gas outlet 12 side such as a torch at the pressure receiving surface 24A while allowing gas movement from the gas inlet 11 to the gas outlet 12. When receiving pressure, it moves in the direction of arrow b (FIG. 2).

  In the configuration as described above, the backfire prevention mechanism 101 is configured by the moving element 21, the stainless ball 22, the rod 23, the pressure sensor 24, the washer 26, the rod spring 27, and the shut-off spring 28.

Next, in the flashback prevention device shown in the present embodiment, the operation when flashback occurs will be described with reference to FIG.
In a normal state, the check valve 20 is urged in the direction of arrow b opposite to the gas supply direction a by a check valve spring 25 disposed between the checker 20 and the moving element 21 as shown in FIG. Yes.
When the gas supply direction of the combustible gas is supplied in the direction of the arrow a along the axis A, the check valve 20 is opened against the urging force of the check valve spring 25 by the supply pressure (see FIG. 1).
At this time, if the supply pressure of the combustible gas is “F1” and the biasing force of the check valve spring 25 is “F2”, the relationship “F1> F2” is established.

Next, in the flashback prevention device shown in this embodiment, the operation when flashback occurs will be described with reference to FIGS. 1 and 2. In these drawings, FIG. 1 shows a normal state before a backfire occurs, and FIG. 2 shows a backfire state.
In the normal state shown in FIG. 1, the stainless steel ball 22 is in a state of being locked to the step portion 3A of the filter receiving member 3 and positioned on the peripheral surface 23B of the rod 23. Even if it is biased in the b direction, the movement in the same direction is restricted by the step 3A.

(1) When the pressure sensor 24 having a wide pressure-receiving surface receives the pressure due to the explosion caused by the backfire applied from the outlet side of the gas outlet path 12, the pressure sensor 24 is pushed, and the direction of the arrow b on the gas introduction path 11 side Move to.

(2) As the pressure sensor 24 moves in the direction of arrow b, the rod 23 in contact with the pressure sensor 24 also moves in the same direction.

(3) When the rod 23 moves in a predetermined amount (for example, 1.1 mm) in the direction of the arrow b, the stainless ball 22 between the peripheral surface 23B of the rod 23 and the step portion 3A of the filter receiving member 3 is used. However, it fits into the groove part 23C formed in the peripheral surface 23B of the rod 23, and the stainless steel ball 22 comes off from the step part 3A.
When fitted into the groove 23C, the stainless ball 22 removed from the stepped portion 3A of the filter receiving member 3 rides on the smooth portion 3B of the filter receiving member 3 and can roll on the smooth portion 3B.

(4) The rod 23 in which the stainless ball 22 is fitted in the groove 23C is pushed by the blocking spring 28 and moves in the arrow b direction. At this time, the stainless ball 22 fitted in the groove 23 </ b> C of the rod 23 rolls on the smooth portion 3 </ b> B of the filter receiving member 3.

(5) Thereafter, after the rod 23 comes into contact with the recess 21 </ b> A of the moving element 21, the rod 21 is moved until the O-ring 20 </ b> A of the check valve 20 comes into contact with the check valve seat 2 </ b> A of the cap 2. This is moved in the direction of arrow b, thereby blocking the inflow of combustible gas from the gas introduction path 11.
At this time, the urging force of the cutoff spring 28 is always applied to the check valve 20 so that the cutoff can be reliably maintained. With this operation, the pressure of the explosion due to the backfire is increased in the case of hydrogen gas. Even when it is small, the gas can be shut off reliably, and the check valve 20 can be fixed with a strong force.

The backfire prevention mechanism 101 is
The force in the opening direction of the check valve due to the supply pressure of the combustible gas is “F1”, the biasing force of the check valve spring 25 is “F2”, the biasing force of the rod spring 27 is “F3”, and the biasing force of the cutoff spring 28 Is “F4”, and the force acting on the pressure sensor 24 by backfire is “F5”.
Until the backfire occurs, the stainless ball 22 is locked to the stepped portion 3A. Therefore, the check valve 20 is opened when the relationship of F1> F2 is established, and the check valve 20 is closed when the relationship is not established. Is done. It is sufficient that the urging force “F2” of the check valve spring 25 is set to a slight force corresponding to less than the minimum operating pressure of the combustible gas. As a result, even if the supply pressure of the combustible gas on the gas introduction path 11 side decreases, the combustible gas is maintained in the open state of the check valve 20 when the combustible gas is in the operating pressure range. Can be used stably.
And when a backfire arises and the relationship of F1 <F4 + F5-F2-F3 is materialized, the non-return valve 20 is closed.
Once the check valve 20 is closed, the check valve 20 is kept closed as long as the relationship of F1 <F4-F2-F3 is established even if the pressure due to the backfire disappears and F5 becomes zero. .

  In addition, when the above-described backfire is stopped and the backfire prevention mechanism 101 is returned to the initial state (the state shown in FIG. 1), as shown in FIG. Insert the rod 30. At this time, when the reset bar 30 is pushed in the direction of arrow a with a force stronger than “F2 + F3 + F4”, the rod 23 also moves in the same direction, and the stainless ball 22 fitted in the groove 23C of the rod 23 also rolls. Move in the same direction.

  At this time, the stainless steel ball 22 moves until it fits into the stepped portion 3A on the filter receiving member 3 side. When the stainless ball 22 fits into the stepped portion 3A, it rides on the peripheral surface 23B of the rod 23 from the groove 23C of the rod 23. In this state, the rod 23 further moves in the direction of the arrow a until the pressure sensor 24 comes into contact with the end portion 3D of the filter receiving member 3, thereby resetting to the initial state shown in FIG.

  According to the backfire preventer according to the present embodiment, when the gas introduction pressure is relatively lowered, the check valve 20 provided in the hollow portion 10 of the case member 100 is attached to the gas introduction path 11 side. As a result, the gas introduction path 11 is closed, and the backflow of the combustible gas is prevented.

  Further, at normal time, the stainless steel ball 22 is locked to the stepped portion 3A formed on the inner peripheral surface of the case member 100, so that the urging force of the cutoff spring 28 is prevented from being transmitted to the moving element 21. The check valve 20 does not move through the mover 21, and the combustible gas flows stably.

On the other hand, when backfire occurs on the gas lead-out path 12 side, the pressure sensor 24 receives the pressure due to the explosion during backfire, and the pressure sensor 24 and the rod 23 pressed by the pressure sensor 24 move in the direction of arrow b. Moving.
As a result, the stainless ball 22 is unlocked at the step portion 3A and is locked in the groove portion 23C, and the check valve 20 is connected to the check valve seat 2A via the moving element 21 by the biasing of the cutoff spring 28. It moves to the side and the gas introduction path 11 is interrupted | blocked.

  According to the backfire preventer according to the embodiment, the backfire prevention mechanism 101 is transmitted only when the pressure sensitive element 24 is transmitted to the stainless steel ball 22 via the cutoff spring 25 biased in the axial direction, and the stainless steel ball 22 moves. Therefore, even if the supply pressure of the combustible gas is reduced, the check valve 20 is prevented from malfunctioning due to vibration or the like.

  Further, since the stainless steel ball 22 is locked to the step portion 3A formed on the inner peripheral surface of the case member 100 at normal times, an explosion due to a backfire occurs and a pressure higher than a predetermined level is applied to the pressure sensor 24. The stainless steel ball 22 is released from the stepped portion 3A and moved to the gas introduction path 11 side and the rod 23 only when a predetermined force or more transmitted to the stainless steel ball 22 is applied via the blocking spring 28. The check valve 20 closes the gas introduction path 11 and the rod 23 is held at that position.

  Further, since the held rod 23 and the check valve 20 do not move to the gas outlet side unless a predetermined force is applied in the reverse direction, the interruption is prevented from being unexpectedly restored.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, in the above embodiment, the case where the rolling member is the stainless ball 22 has been described. However, when the flashback occurs, the rod outer circumferential surface from the step portion 3A for restricting transmission of the urging force of the cutoff spring 28 is described. If it is possible to transfer to the groove 23C, a polyhedron may be used instead of the ball, or a member made of a part of the ball, polyhedron, or the like may be used. Moreover, when it is a ball | bowl, it is not limited to stainless steel, and it cannot be overemphasized that other materials, such as ceramics, can be applied.

  Further, the other end 23E of the rod 23 is pressed against the pressure sensor 24 by the rod spring 27, but the biasing means for pressing the other end 23E of the rod 23 against the pressure sensor 24 is the rod spring 27. For example, a tension spring may be disposed between the rod 23 and the pressure sensor 24.

  In the above embodiment, the case where the combustible gas is hydrogen gas has been described. For example, a mixed gas in which hydrogen and a hydrocarbon such as propane are mixed, and a combustion-supporting gas such as hydrogen and oxygen are used. In addition to a mixed gas mixed with a mixed gas, hydrogen, hydrocarbon, and combustion-supporting gas, the present invention can also be applied to a single hydrocarbon gas such as acetylene.

  INDUSTRIAL APPLICABILITY The present invention is applied to an apparatus for supplying a flammable gas such as hydrogen, a supply path for piping, etc., and can stop the backfire generated on the gas outlet path side and shut off the flammable gas. Is possible.

DESCRIPTION OF SYMBOLS 10 Hollow part 11 Gas introduction path 12 Gas lead-out path 21 Mover 22 Stainless steel ball (rolling member)
23 Rod 24 Pressure sensor 28 Isolation spring 100 Case member 101 Backfire prevention mechanism A Axis

Claims (2)

A case member having inside a hollow portion connected to a gas introduction path to which a combustible gas is supplied and a gas lead-out path from which the combustible gas is derived;
The side that is provided so as to be movable in the axial direction of the hollow portion in the case member and that is biased toward the gas introduction path to close the gas introduction path when the gas introduction pressure is relatively lowered. A check valve that moves to
A backfire prevention mechanism that is provided in a hollow portion in the case member, and that moves to the side that closes the check valve by pressure due to an explosion at the time of backfire from the gas lead-out path,
The backfire prevention mechanism is
A pressure sensor that is provided so as to be movable in the axial direction of the hollow portion, and that moves to the gas introduction path side when subjected to pressure due to explosion at the time of flashback;
A rod that is provided so as to be movable in the axial direction of the hollow portion, and when the pressure sensitive element moves to the gas introduction path side by backfire, a rod that is pressed by the pressure sensitive element and moves to the gas introduction path side;
Between the rod and the check valve, provided so as to be movable in the axial direction of the hollow portion, when pressed by the rod, the check valve is moved to the gas introduction path side to A moving member for closing the gas introduction path,
In the hollow portion, a rolling member that can roll while being in contact with the moving element between an inner circumferential surface of the case member and an outer circumferential surface of the rod, and the rolling member is disposed in the gas. A shut-off spring that biases toward the introduction path side is arranged,
On the inner peripheral surface of the case member, a step portion is formed that normally locks the rolling member and restricts the urging force of the blocking spring from being transmitted to the moving element.
In addition, when backfire occurs on the outer peripheral surface of the rod and the rod moves to the gas introduction path side, the rolling member is unlocked and the rolling member is locked. A backfire preventer having a groove formed therein. The backfire preventer according to claim 1,
The backfire preventer, wherein the rolling member is a sphere.

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