Excessive outflow prevention valve

Abstract

To provide an excessive outflow prevention valve in a simple construction, which can be reliably reset while preventing a chattering phenomenon by seating a valve element on a valve seat using a stable operation flow rate with sufficient valve element holding force at the time of excessive outflow of gas.SOLUTION: The excessive outflow prevention valve includes a cylinder main body 10, a valve seat 11 formed on the inner peripheral face thereof, and approximately disc shaped valve element 2 to be moved to the downstream side at the time of excessive outflow of gas and pressed against the valve seat 11 in air tightness, the valve seat 11 formed with a tapered face diameter-enlarged toward the upstream side at such a tapered angle that the valve element 2 is not bitten. On the upstream side continuing to the valve seat 11, a flow path restriction cylinder part 12 having a diameter somewhat larger than the outer diameter of the valve element 2, and an operation flow rate setting cylinder part 13 having a larger diameter than the flow path restriction cylinder part 12 and having a valve receiving part 14 at the upstream end are provided, in sequence. The cylinder length of the flow path restriction cylinder part 12 is set to be 30-50% of a movement distance L1 of the valve element 2 and about three times the height of the valve element 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an over-flow prevention valve, and more particularly to an over-flow prevention valve that automatically shuts off a gas flow path when gas flowing at or above an operating flow rate flows into a gas plug.

Background Art

[0002] FIG. 5 is a cross-sectional view of a gas plug body (3) incorporating an over-flow prevention valve (5). The gas plug body (3) is a hose gas plug without a knob called a gas faucet, and a substantially L-shaped gas flow path (32) connecting from a pipe connection port (30) at the upstream end to a plug cylinder (31) at the downstream end is formed. An over-flow prevention valve (5) is inserted upstream of the bent portion of the gas flow path (32). When a one-touch coupling type socket (4) is connected to the plug cylinder (31), the valve shaft (35) in a closed valve state in the plug cylinder (31) and the slide valve (34) are pushed upstream against the biasing force of the spring (33), and the gas plug body (3) opens. Gas is sent to the gas equipment (41) through the pipe connection port (30), the over-flow prevention valve (5), the plug cylinder (31), the socket (4), and the gas rubber tube (40). A reset body (36) capable of pushing in the reset shaft (54) of the over-flow prevention valve (5) after operation is provided protruding on the upstream end face of the slide valve (34) by moving upstream.

[0003] As shown in FIGS. 6(A) and 6(B), a conventional over - flow prevention valve (5) includes a cylindrical main body (50) through which a gas flow path passes, a substantially disc - shaped valve body (51) biased by the biasing force of a spring (55) against a valve receiving portion (56) at the upstream end of the cylindrical main body (50), and a valve seat (52) provided on the inner peripheral surface of the cylindrical main body (50) and in pressure contact with the outer peripheral surface of the valve body (51) when the valve is closed. When a gas equipment (41) with a socket (4) connected to a plug cylinder (31) is in use, if an over - flow state of gas occurs due to the disconnection or cutting of a gas rubber tube (40), and the gas flow rate sent to the gas plug main body (3) exceeds the operating flow rate, as shown in FIG. 6(B), the valve body (51) of the over - flow prevention valve (5) pushed by the gas flow moves downstream against the biasing force of the spring (55), and its outer peripheral surface is pressed against the valve seat (52). This is the closed - valve state of the over - flow prevention valve, and the gas flow path (32) of the gas plug main body (3) is blocked.

[0004] Since the spring (55) is in a compressed state when the valve is closed, a biasing force greater than the initial one acts on the valve body (51). Also, when the valve body (51) suddenly moves and seats on the valve seat (52), pressure vibrations occur on the upstream and downstream sides of the valve body (51). When a force in the direction of separating the valve body (51) from the valve seat (52) acts due to the pressure vibration, and at the same time, the biasing force of the spring (55) described above is added, if the force separating the valve body (51) from the valve seat (52) becomes greater than the force pressing the valve body (51) against the valve seat (52), the valve body (51) separates from the valve seat (52). However, since the over - flow state remains, a force in the direction of the valve seat (52) acts on the valve body (51), and the valve body (51) reaches the valve seat (52). In this way, when a chattering phenomenon occurs in which the valve body (51) repeatedly separates from and comes into pressure contact with the valve seat (52), there is a problem that the gas flow path cannot be reliably blocked.

[0005] In the case of liquefied petroleum gas (LP gas), as shown in FIG. 5, the supply pressure supplied to the gas tap body (3) via the supply gas pipe (45) by the pressure regulator (43) connected to the LP gas cylinder (42) via the cylinder pipe (44) is set to be 2.3 to 3.3 kPa suitable for the use of the gas appliance (41). However, due to direct sunlight irradiation, temperature rise, etc., the pressure in the cylinder pipe (44) may increase. In that case, the safety valve for pressure relief provided in the pressure regulator (43) is set so that the pressure in the supply gas pipe (45) does not exceed 7.5 kPa.

[0006] The state where the pressure in the supply gas pipe (45) is set to about 7.5 kPa by the pressure reducing function of the pressure regulator (43) means that the gas pressure (primary pressure) sent to the gas tap body (3) is about 7.5 kPa higher than the atmospheric pressure. Since the pressure in the gas rubber tube (40) to which the gas appliance (41) is connected is the atmospheric pressure, when the socket (4) of the gas rubber tube (40) connected to the gas appliance (41) is connected to the plug cylinder (31) of the gas tap body (3), at the moment of connection, gas exceeding the operating flow rate of the over-flow prevention valve flows suddenly from the supply gas pipe (45) into the gas tap body (3), and the over-flow prevention valve (5) may operate to block the gas flow path. In this way, when gas exceeding the operating flow rate flows rapidly into the over-flow prevention valve (5) and the valve body (51) is pressed against the valve seat (52) with a strong force, the valve body (51) may bite into the valve seat (52), and in that case, the valve body (51) may not be easily reset. If the angle of the valve seat (52) is increased, it is possible to prevent the valve body (51) from biting into the valve seat (52). However, in that case, chattering is likely to occur when gas overflows due to accidents such as the disconnection or cutting of the gas rubber tube (40) as described above, and the gas flow path cannot be surely blocked.

[0007] In order to prevent the occurrence of chattering when gas exceeding the operating flow rate flows into the over-flow prevention valve (5), the over-flow prevention valves disclosed in Patent Documents 1 - 3 were devised or invented. Patent Document 1 attempted to prevent the chattering phenomenon by making the valve seat of an elastic material to improve the biting of the valve body into the valve seat. In Patent Document 2, an engaging protrusion protruding laterally was provided on the valve shaft extended downstream from the valve body, and a notch into which the engaging protrusion could engage was provided in a wavy shape on the guide cylinder through which the valve shaft was inserted. By moving the valve body downstream while engaging the engaging protrusion with the wavy notch, and in Patent Document 3, by abutting the tip of the valve shaft against a contact before the valve body was crimped to the valve seat to temporarily stop the downstream movement of the valve body, the advancing speed during the operation of the valve body was slowed down to suppress the sudden pressure vibration at the time of valve closing to prevent the chattering phenomenon.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in the case of Patent Document 1, the valve body biting into the valve seat is difficult to reset. In the cases of Patent Documents 2 and 3, the structure for controlling the speed of the valve body is complex. Moreover, in Patent Document 2, it is difficult to stabilize the operating flow rate depending on the engagement condition of the engaging protrusion with the wavy notch, and in Patent Document 3, it may be difficult to stabilize the airtightness between the valve body and the valve seat.

[0010] An object of the present invention is to provide an overflow prevention valve with a simple structure that does not cause the chattering phenomenon at the time of valve closing and can be easily reset.

Means for Solving the Problems

[0011] The technical means of the present invention adopted to solve the above problems include a cylindrical main body incorporated in a gas flow path, a valve seat formed on the inner peripheral surface of the cylindrical main body, and a substantially disk-shaped valve body that moves downstream when gas overflows from a state of being biased in the valve opening direction and presses against the valve seat in an airtight state. In the overflow prevention valve having the above components, the valve seat is formed of a tapered surface that expands in diameter toward the upstream side at a taper angle such that the valve body does not bite into it, on the upstream side following the valve seat, a flow path constriction cylinder portion having an inner diameter slightly larger than the outer diameter of the valve body is provided, on the upstream side following the flow path constriction cylinder portion, an operating flow rate setting cylinder portion having a larger diameter than the flow path constriction cylinder portion and having a valve receiving portion at the upstream end is provided, the cylinder length of the flow path constriction cylinder portion is set to be 30% or more and 50% or less of the moving distance of the valve body and about three times the height of the valve body.

[0012] The above solution operates as follows. When a gas flow exceeding the operating flow rate at which the valve body can operate occurs from the upstream side of the cylindrical main body, the valve body moves from the initial position biased by the valve receiving portion to the closed valve position where it presses against the valve seat through the operating flow rate setting cylinder portion and the flow rate constriction cylinder portion. Since 30% or more and 50% or less of the moving distance of the valve body is set to move within the flow path constriction cylinder portion, in other words, 50% or more of the entire moving distance of the valve body moves within the operating flow rate setting cylinder portion where there is no obstacle to the movement of the valve, and then it is sent to the flow path constriction cylinder portion with a smaller diameter. Since the inner diameter of the flow path constriction cylinder portion is slightly larger than the outer diameter of the valve body, when the valve body moves from the operating flow rate setting cylinder portion to the flow path constriction cylinder portion, the gas flow is constricted, and the valve body seats on the valve seat by the constricted gas flow rate. For this reason, the pressure vibration before and after the valve body is suppressed compared to the case without the flow path constriction cylinder portion, and when the valve body seats on the valve seat, the force acting on the valve body in the upstream direction is smaller compared to the case without the flow path constriction cylinder portion. Also, by setting the cylinder length of the flow path constriction cylinder portion to about three times the height of the valve body, the gas flow is constricted immediately before the valve body reaches the valve seat. Also, even when the valve body is pulled back upstream after seating on the valve seat, in the case of those without the flow rate restricting cylinder portion, a space close to the initial state is formed between the valve body and the valve seat. Therefore, after the valve body reaches the valve seat, if the operation of pulling it back is repeated, a so-called chattering phenomenon occurs. However, in the case where the flow path restricting cylinder portion is provided as described above, since the valve body repeatedly seats and separates within the flow path restricting cylinder portion, the flow rate is restricted each time, and the pressure vibration due to the seating of the valve body on the valve seat is attenuated, and the chattering phenomenon is stopped without continuing. Since the tapered surface constituting the valve seat is set at a taper angle such that the valve body does not bite into it, after the valve body seats on the valve seat and is pushed downstream by the gas, the valve body is held in a close contact state with an appropriate valve body holding force and does not bite into the valve seat.

[0013] In the above over-flow prevention valve, those in which 'the cylinder length of the flow rate restricting cylinder portion is set to be equal to or less than the cylinder length of the operating flow rate setting cylinder portion' or those in which 'the cylinder length of the flow path restricting cylinder portion is set to about 40% of the moving distance of the valve body' are preferable. By setting the cylinder length of the operating flow rate setting cylinder portion to 50% or more of the combined cylinder length of the operating flow rate setting cylinder portion and the flow rate restricting cylinder portion, and further, by setting it to about 60% of the moving distance of the valve body, the operating flow rate of the gas flowing through the operating flow rate setting cylinder portion can be surely stabilized.

[0014] In the above over-flow prevention valve, preferably, 'the flow path restricting cylinder portion has a tapered surface that expands in diameter toward the upstream side'. During the operation of the over-flow prevention valve, since the valve body moves within the flow path restricting cylinder portion where the flow path gradually narrows toward the downstream side, the valve body can be accurately seated on the valve seat without shifting with respect to the valve seat. Also, regardless of the orientation of the cylinder main body, the valve body can be surely and accurately seated on the valve seat, and stable airtightness can be obtained.

[0015] In the above over-flow prevention valve, preferably, 'the taper angle of the tapered surface constituting the valve seat is set to 17.5 degrees or more'. By setting the taper angle to 17.5 degrees or more, the valve body crimped to the valve seat can be reliably reset. Also, even if the valve body is forcibly pushed into the downstream side, if there is no differential pressure between the downstream side and the upstream side of the valve body, the valve body can be returned to the initial position by the biasing force acting on the valve body.

Effect of the Invention

[0016] Since the present invention has the above configuration, it has the following specific effects. When the valve body is pushed by gas with a flow rate equal to or greater than the operating flow rate during over-flow and moves toward the valve seat, the valve body moves within the operating flow rate setting cylinder portion where there is no obstacle to the movement of the valve for 50% or more of the entire movement distance. Therefore, the valve body can be reliably moved at a stable operating flow rate. The valve body moves gently in a state where the gas flow is restricted within the following flow rate restricting cylinder portion, so that the repulsive force received by the valve body from the valve seat at the time of seating becomes small and sudden pressure vibrations are also unlikely to occur. Therefore, the valve body does not inadvertently separate from the valve seat when closing the valve. Thus, it is possible to prevent the chattering phenomenon in which the valve body repeatedly separates from and crimps to the valve seat when closing the valve, so that the valve body can be reliably held on the valve seat and the valve can be reliably closed to block the gas flow path. Also, by setting the movement distance of the valve body at the restricted gas flow rate to about three times the valve height, the gas flow is restricted immediately before the valve body reaches the valve seat. Therefore, the valve body can be moved downstream without hindrance in a stable posture and seated on the valve seat, and pressure vibrations can be attenuated while ensuring the operating flow rate. Since the valve seat has a tapered surface that tapers toward the downstream side, the valve body comes into close contact with the valve seat as it moves downstream, and the valve body holding force at the valve seat increases. Therefore, the closed valve state by the valve body is maintained, and the over-flow state can be reliably stopped. Note that since the tapered surface constituting the valve seat is set at a taper angle such that the valve body does not bite, the valve body in the closed valve state can be easily and reliably reset by normal reset means, and no reset failure occurs. The valve seat formed on the inner peripheral surface of the cylinder body is a tapered surface at a predetermined angle, and a flow path throttle cylinder portion having a diameter slightly larger than the outer diameter of the valve body is provided on the upstream side thereof. Therefore, the structure is simple and the assembly work is not complicated.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. The overflow prevention valve (1) of this embodiment is housed in the body portion following the pipe connection port (30) of the gas plug body (3), similar to the conventional one shown in FIG. 5. As shown in FIGS. 1 to 3, it has a metal cylinder body (10), a valve seat (11) formed on the inner peripheral surface of the cylinder body (10) and consisting of a tapered surface that expands in diameter toward the upstream side (downward in the drawing), and a valve body (2) that is pressure-bonded to the valve seat (11) from the upstream side to close the overflow prevention valve (1).

[0019] At the downstream end (the upper end in the drawing) of the cylinder main body (10), a guide cylinder portion (20) that restricts the downstream movement of the valve body (2) is provided. At the upstream end (the lower end in the drawing) of the cylinder main body (10), a valve receiving portion (14) that receives the valve body (2) biased upstream by the biasing force of a spring (23) interposed between it and the guide cylinder portion (20) is integrally provided. Figure 1 shows the valve opening state, and the valve body (2) is in its initial position biased by the biasing force of the spring (23) against the valve receiving portion (14).

[0020] The valve body (2) is substantially disc-shaped, and an outer peripheral wall (2a) with a circular arc-shaped cross-section that tapers towards the downstream side protrudes from its peripheral edge. It is formed in a diabolo shape with shafts protruding vertically from the center. The first valve shaft (21) protruding downstream is slidably inserted into the through-hole (20a) of the guide cylinder portion (20), and the second valve shaft (22) protruding upstream is slidably inserted into the central hole (14a) of the valve receiving portion (14). As a result, as shown in Figure 2, the valve body (2) can move forward and backward along the central axis without shifting left and right or being obliquely distorted over the movement distance (L1) from the valve receiving portion (14) to the valve seat (11).

[0021] Figure 2 shows the valve closing state where the outer peripheral surface of the outer peripheral wall (2a) is in pressure contact with the valve seat (11) consisting of a tapered surface. Note that the taper angle of the valve seat (11) is set to 17.5 degrees. This angle is such that when the valve body (2) is in pressure contact with the valve seat (20), the valve body (2) does not bite into the valve seat (20).

[0022] On the upstream side of the valve seat (11), a flow path throttle cylinder portion (12) with an inner diameter slightly larger than the outer diameter of the valve body (2) is provided, and further upstream of it, an operating flow rate setting cylinder portion (13) with an inner diameter larger than the inner diameter of the flow path throttle cylinder portion (12) is provided. The cylinder length (L2) of the flow path throttle cylinder portion (12) shown in Figure 1 is set to be approximately 40% of the above-mentioned movement distance (L1) of the valve body (2) and approximately three times the valve height (H2) of the valve body (2). Further, the cylinder length (L3) of the operating flow rate setting cylinder portion (13) is set to be equal to or greater than the cylinder length (L2) of the flow path throttle cylinder portion (12).

[0023] When the valve body (2) shown in FIG. 1 opens, if a gas flow exceeding the operating flow rate at which the valve body (2) can operate occurs from the upstream side of the cylinder main body (10), the valve body (2) resists the biasing force of the spring (23) and moves away from the valve seat portion (14) from the initial position biased by the spring (23) to move within the operating flow rate setting cylinder portion (13). Since the inner diameter of the operating flow rate setting cylinder portion (13) is set larger than the outer diameter of the valve body (2) and its cylinder length (L3) is about 60% of the total movement distance (L1) of the valve body (2), the operating flow rate flowing into the overflow prevention valve (1) becomes stable. Further, since there is nothing that obstructs the movement of the valve body (2) in the operating flow rate setting cylinder portion (13), the valve body (2) can move downstream in the flow rate setting cylinder portion (13) at a stable operating flow rate.

[0024] Thereafter, as shown in FIG. 3, when the valve body (2) enters the flow path throttle cylinder portion (12) having an inner diameter slightly larger than the outer diameter of the valve body (2) from the operating flow rate setting cylinder portion (13), the gas flow is throttled, and in this state, the valve body (2) seats on the valve seat (11). Therefore, the pressure vibration before and after the valve body (2) at this time becomes smaller than that without the flow rate throttle cylinder portion.

[0025] Note that FIG. 4 shows an overflow prevention valve (1a) of another embodiment, in which the flow path throttle cylinder portion (12a) is formed in a tapered cylinder shape that is slightly larger in diameter toward the upstream side. In this case, as the valve body (2) moves downstream in the flow rate throttle cylinder portion (12a), the inner diameter gradually becomes narrower, so that the valve body (2) can accurately seat the tapered outer peripheral surface of the outer peripheral wall (2a) of the valve body (2) on the tapered valve seat (11) without being distorted or displaced. Further, even when the orientation of the overflow prevention valve (1) is horizontal, the valve body (2) can be accurately seated on the tapered valve seat (11).

[0026] In the overflow prevention valve (1) with the above-described structure, in the event of an accident such as the disconnection or cutting of the gas rubber tube, when the gas is in an overflow state and gas flowing into the cylinder main body (10) exceeds the operating flow rate, the valve body (2) biased against the valve receiving portion (14) at the initial position is pushed by the gas flow and moves downstream in the operating flow rate setting cylinder portion (13) at a stable operating flow rate against the biasing force of the spring (23). After that, when the gas flow is restricted upon entering the flow restrictor cylinder portion (12), the valve body (2) advances a distance three times the valve height (H2) within the flow restrictor cylinder portion (12) formed of a tapered surface and seats on the valve seat (11).

[0027] Since the flow rate is thus restricted and the valve body (2) seats on the valve seat (11), the sudden pressure vibrations acting on the valve body (2) from both the upper and lower sides during valve closure are suppressed, preventing the occurrence of a chattering phenomenon in which the valve body (2) repeatedly separates from and presses against the valve seat (11) during valve closure, and enabling the gas flow path to be reliably blocked by the valve body (2).

[0028] Also, since the outer peripheral surface of the outer peripheral wall (2a) of the valve body (2) is also a tapered surface similar to the valve seat (11), after the valve body (2) seats on the valve seat (11), the valve body (2) can be held in close contact with the valve seat (11) with sufficient valve body holding force by being further pushed downstream by the gas pressure. However, by setting the taper angle of the valve seat (11) to 17.5 degrees or more, which is a taper angle at which the valve body (2) does not bite, the valve body (2) will not bite even when pressed against the valve seat (11). Therefore, although not shown, by pushing the first valve body (21) upstream by a reset mechanism similar to the conventional one, the valve body (2) can be easily separated from the valve seat (11) and returned to the initial position.

Explanation of Reference Numerals

[0029] (1) ·······Overflow prevention valve (2) ·······Valve body (10)·······Cylinder main body (11)·······Valve seat (12) ······ Flow path throttle cylinder part (13) ······ Operating flow rate setting cylinder part (14) ······ Valve receiving part (L1) ······ Movement distance of valve body (L2) ······ Cylinder length of flow path throttle cylinder part (H2) ······ Height of valve body

Claims

1. In an over - flow prevention valve having a cylindrical main body incorporated in a gas flow path, a valve seat formed on the inner peripheral surface of the cylindrical main body, and a substantially disc - shaped valve body that moves downstream when gas over - flows from a state biased in the valve - opening direction and presses against the valve seat in an airtight state, the valve seat is composed of a tapered surface that expands in diameter toward the upstream side at a taper angle such that the valve body does not bite, on the upstream side following the valve seat, a flow - path constriction cylinder portion having an inner diameter slightly larger than the outer diameter of the valve body is provided, on the upstream side following the flow - path constriction cylinder portion, an operating - flow - rate setting cylinder portion having a larger diameter than the flow - path constriction cylinder portion and having a valve receiving portion at the upstream end is provided, the cylinder length of the flow - path constriction cylinder portion is set to be 30% or more and 50% or less of the moving distance of the valve body and about three times the height of the valve body, in the over - flow prevention valve.

2. The over - flow prevention valve according to claim 1, wherein the cylinder length of the flow - rate constriction cylinder portion is set to be equal to or less than the cylinder length of the operating - flow - rate setting cylinder portion.

3. The over - flow prevention valve according to claim 1 or 2, wherein the cylinder length of the flow - path constriction cylinder portion is about 40% of the moving distance of the valve body.

4. The over - flow prevention valve according to claim 1 or 2, wherein the flow - path constriction cylinder portion has a tapered surface that expands in diameter toward the upstream side.

5. The over - flow prevention valve according to claim 1 or 2, wherein the taper angle of the tapered surface constituting the valve seat is 17.5 degrees or more.

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