Overflow prevention valve

Abstract

By delaying the time from when the valve body begins to move downstream until it seats on the valve seat, malfunctions of the overflow prevention valve in a simulated overflow condition are prevented, and an overflow prevention valve with a simple structure is provided without large fluctuations in the operating flow rate. [Solution] Before the valve body 2 seats on the valve seat 11, the tip of the downstream valve stem protrudes downstream from the valve stem hole of the guide cylinder 20 and is set to collide with a valve stem impact member 1 made of elastic wire, which is provided at a position where it intersects the valve stem hole on the downstream side of the guide cylinder.

Description

Technical Field

[0001] The present invention relates to an overflow prevention valve, particularly an overflow prevention valve that automatically blocks a gas flow path when gas flowing at a flow rate equal to or greater than the operating flow rate flows into a gas plug.

Background Art

[0002] FIG. 10 is a cross-sectional view of a gas plug body (3) incorporating an overflow prevention valve (5). The gas plug body (3) is a hose gas plug without a knob called a gas faucet, and a gas flow path (32) is formed that connects the pipe connection port (30) at the upstream end to the plug cylinder (31) at the downstream end. An overflow prevention valve (5) is inserted at a location in the gas flow path (32) that follows the pipe connection port (30). When a socket (4) of a one-touch coupling method is connected to the plug cylinder (31), a slide valve (34) in a closed valve state within the plug cylinder (31) is pushed upstream against the biasing force of a spring (33), and the gas plug body (3) opens, and gas is sent to a gas device (41) via the pipe connection port (30), the overflow prevention valve (5), the plug cylinder (31), the socket (4), and a gas rubber tube (40).

[0003] A conventional overflow prevention valve (5) has a cylindrical main body (50) through which the 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 (the right end in the drawing) of the cylindrical main body (50), and a valve seat (52) provided on the inner peripheral surface of the cylindrical main body (50) and having the outer peripheral surface of the valve body (51) pressed against it when the valve is closed. When using a gas device (41) with a socket (4) connected to the plug cylinder (31), if the gas rubber tube (40) comes off or is cut, etc., causing an overflow state of gas, and the gas flow rate sent to the gas plug body (3) becomes equal to or greater than the operating flow rate, the valve body (51) pushed by the gas flow moves downstream (the left side in the drawing) 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 overflow prevention valve (5), and the gas flow path (32) of the gas plug body (3) is blocked.

[0004] In the case of LP gas, the supply pressure supplied to the gas valve body (3) via the supply gas piping (45) by a pressure regulator (43) connected to the LP gas cylinder (42) via cylinder piping (44) is set to 2.3 to 3.3 kPa, which is suitable for the use of gas appliances (41). However, when the gas appliance (41) is not in use, if the pressure inside the cylinder piping (44) rises due to exposure to direct sunlight or rising temperatures, a pressure relief safety valve (43a) provided in the pressure regulator (43) is set to prevent the pressure inside the supply gas piping (45) from exceeding 7.5 kPa.

[0005] When the pressure inside the supply gas piping (45) is set to approximately 7.5 kPa by the pressure regulator (43)'s pressure reduction function, it means that the gas pressure (primary pressure) sent to the gas valve body (3) is approximately 7.5 kPa higher than atmospheric pressure. In this state, when a socket (4) connected to a gas appliance (41) is connected to the plug cylinder (31) of the gas valve body (3) via a gas rubber tube (40), the pressure inside the gas rubber tube (40) is atmospheric pressure. Therefore, at the moment of connection, gas exceeding the operating flow rate of the overflow prevention valve (5) may rapidly flow from the supply gas piping (45) into the gas valve body (3), causing the overflow prevention valve (5) to activate and shut off the gas flow path.

[0006] Furthermore, even when the gas valve and gas appliance (41) are connected, if the solenoid valve opens at the start of combustion, a gas flow exceeding the operating flow rate of the overflow prevention valve (5) may occur at that moment, causing the overflow prevention valve (5) to activate as described above.

[0007] As an overflow prevention valve that avoids a pseudo-overflow state in which gas exceeding the operating flow rate flows instantaneously into the overflow prevention valve (5) unintentionally, we have invented the one disclosed in Patent Document 1. In this design, protrusions (53a) and (53b) are provided on the tip of the valve stem (53) to project outwards on both sides. These protrusions pass through wavy notches provided on the opposing side walls of the guide cylinder (54) and oriented in opposite directions, thereby moving the valve stem (53) downstream within the guide cylinder (54). As the protrusions (53a) and (53b) meander along the notches, multiple collisions and friction between the protrusions (53a) and (53b) and the notches delay the time it takes for the valve body (51) to reach the valve seat (52). In other words, even if an overflow of gas occurs instantaneously and the valve body (51) separates from the valve seat (56), the valve body (51) will not seat on the valve seat (52) before the instantaneous overflow is resolved. This prevents the overflow prevention valve (5) from inadvertently closing even when a pseudo-overflow condition occurs. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 10-169814 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, in the above-mentioned Patent Document 1, the structure is complex and assembly is complicated because the projections (53a) and (53b) provided on the valve stem (53) are moved along the wave-shaped notches provided on the opposing side walls of the guide cylinder (54). Furthermore, depending on the degree of collision between the projections (53a) and (53b) and the notches, if snagging occurs between the projections (53a) and (53b) and the notches, the operating flow rate may fluctuate greatly, making it difficult to stabilize the operating flow rate. In particular, if the angle of the notch of the guide cylinder (54) is made close to a right angle with respect to the direction of travel of the valve stem (53), the delay time of the valve body can be increased, but the operating flow rate required to resolve the snagging becomes large, resulting in the problem that the overflow prevention valve does not operate when the amount of gas that should be operating has flowed.

[0010] The present invention aims to prevent the inconvenience of the overflow prevention valve inadvertently operating and closing in a pseudo-overflow state by delaying the time from when the valve body begins to move downstream until it seats on the valve seat, and to provide an overflow prevention valve in which the operating flow rate does not fluctuate significantly. [Means for solving the problem]

[0011] The technical means of the present invention, which were taken to solve the above problems, An overflow prevention valve comprising: a cylindrical body incorporated into a gas flow path; a valve seat formed on the inner circumferential surface of the cylindrical body; a substantially disc-shaped valve body that moves downstream from a state biased in the valve-opening direction to airtightly press against the valve seat when gas overflow occurs; a valve shaft that integrally protrudes at least downstream from the center of the valve body; a valve receiving portion provided at the upstream end of the cylindrical body to receive the valve body when it is biased in the valve-opening direction; and a guide cylinder provided at the downstream end of the cylindrical body having a valve shaft hole in the center through which the valve shaft can be inserted, wherein A valve stem impact member made of elastic wire is positioned downstream of the guide cylinder and intersects with the valve stem hole. The valve is set such that, when the valve body is in operation, the tip of the valve shaft protrudes downstream from the valve shaft hole of the guide cylinder and collides with the valve shaft impact member before the valve body seats on the valve seat.

[0012] The above solution works as follows: If excessive gas leakage occurs due to the rubber hose detaching downstream of the gas valve, and a gas flow exceeding the operating flow rate that allows the valve body to operate is generated from the upstream side of the main cylinder, the valve body will be pushed by the gas from its initial position biased by the valve seat and move downstream toward the valve seat. Before the valve body seats on the valve seat, the tip of the valve stem, which protrudes downstream, extends downstream from the valve stem hole in the guide cylinder and collides with a valve stem impact member located at a position where it intersects the valve stem hole on the downstream side of the guide cylinder. This prevents the movement of the valve body and delays the operating time until the valve body seats on the valve seat by a certain period of time. Since the valve stem impact member is made of elastic wire, when pushed from the upstream side by the tip of the valve stem, it elastically swings in a direction away from the direction of movement of the valve stem. As a result, the valve stem can move downstream beyond the valve stem impact member. At this time, the valve stem does not get caught on the valve stem impact member, so the valve stem can move smoothly and the valve body can be pressed against the valve seat to close the valve. In the case of a pseudo-overflow condition, the overflow condition is momentary and is resolved immediately. In other words, the pseudo-overflow condition is resolved while the tip of the valve stem collides with the valve stem impact member, causing a delay in the operation time of the valve body. As a result, the valve body is returned to its initial state by the biasing force before reaching the valve seat and is maintained in the open state.

[0013] In the above-described overflow prevention valve, it is preferable that "the valve stem impact member is provided so as to be perpendicular to the central axis of the valve stem hole in the guide cylinder." In this configuration, the center of the tip of the valve stem impacts the valve stem impact member at almost a right angle, so the movement of the valve body can be reliably and temporarily suppressed by the impact.

[0014] In the above-described overflow prevention valve, it is preferable that "the valve stem impact member has a free end on one side." By fixing one end of the valve stem impact member and leaving the other end as a free end, the valve stem impact member becomes swingable on the free end side. For example, by fixing one end of the valve stem impact member to a predetermined location on the main body of the cylinder, and providing the other end, which is the free end, of the valve body impact member so as to intersect with the valve stem hole, the valve body operates in the state of overflow of gas, and the tip of the valve stem collides with the valve stem impact member, thereby reliably delaying the operating speed of the valve body. Further pushing by the tip of the valve stem causes the free end side of the valve stem impact member to swing in a direction away from the direction of movement of the valve stem, with the one end side as the base end, allowing the valve stem to pass through.

[0015] In the above-described overflow prevention valve, it is preferable that "the valve shaft impact member is a rod-shaped portion that is bent and extended in the diametrical direction from at least one open end of the C-shaped ring body," and in this case, it is preferable that "a holding portion for holding the C-shaped ring body is provided on the cylindrical main body downstream of the valve seat." By fitting the C-shaped ring body into a retaining part such as a groove provided on the inside or outside of the main cylindrical body, the valve stem impact member is fixed in place, and the tip of the rod-shaped body extending diametrically from one open end of the C-shaped ring body can swing elastically relative to the C-shaped ring body, thereby functioning as a valve stem impact member.

[0016] In the above-mentioned overflow prevention valve, it is preferable that "the C-shaped ring body is used as a coil spring." In this device, a rod-shaped body is formed by bending one end of a coil spring in the diametrical direction to extend it, and the valve shaft impact member is set so as to intersect the valve shaft hole with the coil spring held by the main cylindrical body, with the valve shaft impact member facing the downstream side. In a state of excessive gas outflow, the valve body moves downstream, and when the valve shaft impact member is pushed from the upstream side by the tip of the valve shaft, the coil spring portion extends axially according to the number of turns of the coil. This increases the time that the valve shaft impact member presses against the valve shaft, thereby delaying the operating speed of the valve body. This ensures that the momentary excessive gas outflow in a simulated excessive gas outflow state is reliably eliminated, and prevents the valve body from closing unintentionally. Furthermore, the valve stem impact member is designed to swing easily due to the presence of a coil spring. When pressed by the tip of the valve stem during actual overflow, it quickly swings elastically, moving the valve stem downstream of the valve stem impact member. This ensures that the valve body is reliably pressed against the valve seat and the valve is closed during actual gas overflow, thus providing a highly safe overflow prevention valve.

[0017] In the above-described overflow prevention valve, it is preferable that "a plurality of valve shaft impact members are provided". For this, for example, it is possible to adopt a configuration in which both ends of a coil spring are bent in the diametrical direction to provide two rod-shaped valve shaft collision members. By holding the coil spring on the cylinder main body on the downstream side of the guide cylinder, it is possible to adopt a configuration in which the valve shaft collision members project so as to intersect the valve shaft hole on the upstream side and the downstream side of the coil spring, respectively. In this case, in the gas overflow state, the tip of the valve shaft that moves to the downstream side together with the valve body collides with the valve shaft collision member twice to elastically swing the valve shaft collision member, so the time taken to delay the operation of the valve body is doubled. Thus, since the operating speed of the valve body can be reliably delayed, the operation of the valve body in the pseudo-overflow state can be more reliably suppressed.

[0018] In the above overflow prevention valve, preferably, 'a notch portion is provided in the guide cylinder so as to penetrate the guide cylinder in a direction perpendicular to the axis of the guide cylinder and communicate with the valve shaft hole, the valve shaft collision member is provided so as to intersect the valve shaft hole in a state of being inserted into the notch portion, the radial notch depth of the notch portion is set so that the valve shaft collision member can swing to a position where it comes off the valve shaft hole'. The valve shaft collision member is set so as to be installed in the valve shaft hole in a state of passing through a notch portion provided in the guide cylinder. In the gas overflow state, when the valve shaft collision member is pushed downstream by the tip of the valve shaft, the valve shaft collision member is housed in the notch portion, so the swing in the same direction as the movement direction of the valve shaft is blocked. Therefore, the movement of the valve body can be reliably suppressed, and inadvertent valve closing in the pseudo-overflow state can be prevented. In the actual overflow state, the valve shaft collision member can be elastically swung in the notch depth direction of the notch portion by being pushed by the tip of the valve shaft, so the valve shaft can move downstream beyond the valve shaft collision member, and the valve body can be pressed against the valve seat to close the valve.

[0019] In the above over-flow prevention valve, preferably, "at the latter half of the operation process in which the valve body moves from the initial position to seat on the valve seat during the operation of the valve body, the tip of the valve shaft collides with the valve shaft collision member". In the over-flow state of the gas, the valve body operates in the direction of moving downstream under the pressure of the gas. However, since the tip of the valve shaft collides with the valve shaft collision member at the latter half of this operation process, the time from when the valve body is urged at the valve receiving portion to when the tip of the valve shaft collides with the valve shaft collision member, and the time from when the tip of the valve shaft collides with the valve shaft collision member to when the valve shaft collision member swings are required, so that the time from when the valve body operates to when it seats on the valve seat can be extended. As a result, in the case of a pseudo over-flow state, an instantaneous over-flow state can be surely eliminated, the valve body can be returned to the initial state, and the valve can be maintained in the open state.

Effects of the Invention

[0020] Since the present invention has the above configuration, it has the following specific effects. When the valve body is pushed by a gas with a flow rate greater than the operating flow rate during over-flow and operates in the closing direction of the valve body, by causing the tip of the valve shaft that operates simultaneously with the valve body to collide with the valve shaft collision member first, the time until the valve body is crimped to the valve seat is delayed by a certain time, so that an inadvertent closing operation of the over-flow prevention valve in an instantaneous pseudo over-flow state can be prevented. Particularly, when the valve shaft collision member is positioned perpendicular to the axis of the guide cylinder, a sufficient delay in the operating time of the valve body can be caused, and inadvertent closing in a pseudo over-flow state can be surely prevented. Since the structure for delaying the operation of the valve body utilizes the elastic swing of the valve shaft collision member made of an elastic wire, the number of times the tip of the valve shaft collides with one valve shaft collision member is only once, and there is no snag between the tip of the valve shaft and the valve shaft collision member. As a result, the operating flow rate of the over-flow prevention valve does not fluctuate greatly. In addition, since it is only necessary to provide the valve shaft collision member on the downstream side of the valve shaft, the structure is simple and the assembly work is not complicated.

Brief Description of the Drawings

[0021] [Figure 1] This is a cross-sectional view showing the open state of the overflow prevention valve according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the closed state of the overflow prevention valve according to the first embodiment of the present invention. [Figure 3] This is a plan view of the overflow prevention valve according to the first embodiment of the present invention. [Figure 4] This is a cross-sectional view showing the valve body of the overflow prevention valve of the first embodiment of the present invention in an intermediate state during operation. [Figure 5] This is a cross-sectional view showing the open state of the overflow prevention valve according to the second embodiment of the present invention. [Figure 6] This is a cross-sectional view taken along the line X-X in Figure 5. [Figure 7] This is a cross-sectional view showing an overflow prevention valve according to a third embodiment of the present invention. [Figure 8] This is a cross-sectional view showing an overflow prevention valve according to a fourth embodiment of the present invention. [Figure 9] This is a cross-sectional view showing an overflow prevention valve according to a fifth embodiment of the present invention. [Figure 10] A cross-sectional view of a conventional gas valve equipped with an overflow prevention valve and an explanatory diagram of its use. [Modes for carrying out the invention]

[0022] The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The overflow prevention valve (100) in this embodiment is housed in the body of the gas valve body following the piping connection port, similar to conventional valves. As shown in Figures 1 and 2, it comprises a metal cylindrical body (13), a valve seat (11) formed on the inner circumferential surface of the cylindrical body (13) and having a tapered surface that widens toward the upstream side (downward in the drawings), and a valve body (2) that is pressed against the valve seat (11) from the upstream side to close the overflow prevention valve (100).

[0023] A guide cylinder portion (20) is provided at the downstream end (upper end in the drawing) of the cylindrical body (13) to restrict the downstream movement of the valve body (2), and a valve receiving portion (12) is integrally provided at the upstream end (lower end in the drawing) of the cylindrical body (13) to receive the valve body (2) which is biased upstream by the biasing force of a spring (23) interposed between it and the guide cylinder portion (20). Figure 1 shows the open state of the overflow prevention valve (100), where the valve body (2) is in its initial position, biased against the valve receiving portion (12) by the biasing force of the spring (23).

[0024] The valve body (2) is roughly disc-shaped, with an outer peripheral wall (2a) having a circular arc cross-section that decreases in diameter towards the downstream side projecting from its periphery, and is formed in a spinning top shape with valve stems protruding both upward and downward from the center. The first valve stem (21) protruding downstream is inserted into the valve stem hole (20a) of the guide cylinder (20) so as to be able to move back and forth, and the second valve stem (22) protruding upstream is inserted into the central hole (12a) of the valve seat (12) so as to be able to move back and forth. As a result, the valve body (2) can move back and forth along its central axis from the valve seat (12) to the valve seat (11).

[0025] In the overflow prevention valve (100) of the above structure, if an overflow of gas occurs due to an accident such as the gas rubber hose coming loose or being cut, and more gas than the operating flow rate flows into the cylindrical body (13), the valve body (2), which is biased to the valve receiving part (12) in its initial position, is pushed by the gas flow and moves downstream against the biasing force of the spring (23), and as shown in Figure 2, the outer surface of the outer wall (2a) of the valve body (2) is pressed against the valve seat (11), which is made of a tapered surface. This is the closed state of the overflow prevention valve (100), and the gas flow path of the gas valve body is shut off.

[0026] In this embodiment, in order to avoid the inconvenience of the overflow prevention valve (100) inadvertently closing when a pseudo-overflow condition occurs, such as when there is a pressure difference between the gas rubber tube connected to the gas appliance and the supply gas piping connected to the gas valve body, or when the solenoid valve opens at the start of combustion, a valve shaft impact member (1) is provided at the downstream open end of the valve shaft hole (20a) of the guide cylinder (20) so as to be perpendicular to the central axis of the valve shaft hole (20a).

[0027] As shown in Figure 3, the valve stem impact member (1) is a straight rod-shaped portion bent diametrically from one end of an open end of a C-shaped ring body (10) made of elastic wire. As shown in Figures 1 and 2, the C-shaped ring body (10) is inserted into a cylindrical body (13) located downstream of the downstream end of the guide cylinder (20) while reducing its diameter, and is elastically returned to a position corresponding to a groove (13a) formed over the entire circumferential surface of the inner circumference of the cylindrical body (13), thereby fitting into and fixing it in the groove (13a). As a result, the base end of the valve stem impact member (1), which is the boundary portion with the C-shaped ring body (10), is fixed to the cylindrical body (13). In this embodiment, the groove (13a) functions as the holding portion of the specific features of the invention.

[0028] When a gas flow rate exceeding the operating flow rate flows into the cylindrical body (13) of the overflow prevention valve (100), the valve body (2) operates as described above and moves downstream toward the valve seat (11) pushed by the gas flow. As shown in Figure 4, in the latter half of this operation process, the dimensional relationship between the components is set such that the tip of the first valve stem (21) collides with the valve stem impact member (1) from the upstream side before the outer peripheral wall (2a) of the valve body (2) presses against the valve seat (11). Since the valve stem impact member (1) is provided on the downstream side of the guide cylinder (20) so as to be perpendicular to the valve stem hole (20a), the tip of the first valve stem (21) can collide with the valve stem impact member (1), thereby temporarily and reliably preventing the first valve stem (21) from moving downstream.

[0029] In other words, in a state of excessive gas outflow, when the valve body (2) moves downstream from its initial position biased against the valve seat (12) due to the gas, the tip of the first valve shaft (22) collides with the valve shaft impact member (1), temporarily suppressing the operation of the valve body (2). As a result, the time until the valve body (2) seats on the valve seat (11) is delayed by a certain period of time.

[0030] This delay time is sufficient to eliminate the instantaneous overflow of gas in the pseudo-overflow state, and the pseudo-overflow state is resolved by the time the valve body (2) reaches the valve seat (11). After the pseudo-overflow state is resolved, the valve body (2) is biased by the biasing force of the spring (23) towards the valve seat (12), as shown in Figure 1, and returns to the initial position maintained in the open state.

[0031] If an accident such as the gas rubber hose coming loose or being cut causes an overflow of gas, and more gas than the operating flow rate flows into the main cylinder (13), the tip of the first valve stem (21) will collide with the valve stem impact member (1) at a right angle, and the valve body (2) will be pushed further downstream, causing the first valve stem (21) to also move downstream, and the valve stem impact member (1) will be pushed downstream by the first valve stem (21). Since the valve stem impact member (1) is made of elastic wire, when pushed from the upstream side at the tip of the first valve stem (21), it elastically swings slightly upward of the first valve stem (21) around the base end on the C-shaped ring body (10) side, and then swings laterally away from the first valve stem (21) as shown by the dashed line in Figure 3. As a result, the valve stem (2) advances downstream from the downstream open end of the valve stem hole (20a) of the guide cylinder (20) beyond the valve stem impact member (1), as shown in Figure 2, and the valve body (2) presses against the valve seat (11), thereby closing the overflow prevention valve (100).

[0032] Figure 5 is a longitudinal cross-sectional view of the overflow prevention valve of the second embodiment, and Figure 6 is a cross-sectional view of XX in Figure 5. The overflow prevention valve (100) of this embodiment has a basic structure similar to the overflow prevention valve used in the first embodiment described above. The valve shaft impact member (1) is a rod-shaped portion that extends linearly from one open end toward the center of a C-shaped ring body (10) made of elastic wire. The base end of the C-shaped ring body (10) is fixed by fitting it into a groove (13a) provided at a predetermined location on the inner circumferential surface of the cylindrical main body (13), while the free end is pivotable.

[0033] As shown in Figure 5, the guide cylinder (20) is set to a height that protrudes downstream of the groove (13a) provided in the main cylinder body (13). At a location corresponding to the height of the groove (13a), the guide cylinder (20) is cut out so as to cross perpendicular to the axis of the guide cylinder (20), forming a roughly semicircular notch (24). The inside of the notch (24) communicates with the valve stem hole (20a), and the outside of the notch (24) is cut out so as to open along a roughly semicircular part of the outer circumferential surface of the guide cylinder (20).

[0034] In this device, as shown in Figure 6, the valve stem impact member (1) is elastically deformed so that it is positioned on the outer surface side of the guide cylinder (20) where the notch (24) is open, and the C-shaped ring body (10) is inserted into the main cylinder body (13) while reducing its diameter. When the C-shaped ring body (10) reaches the groove (13a), it elastically returns to its original shape and is fitted into a retaining state, and at the same time, the valve stem impact member (1) is inserted into the notch (24) from the outer open part of the guide cylinder (20) by its elastic returning force and is set to be mounted on the valve stem hole (20a).

[0035] In a gas overflow condition, when the valve body (2) is pushed downstream, the downstream end of the first valve stem (21) collides with the valve stem impact member (1), and the valve stem impact member (1) is pushed downstream. However, since the valve stem impact member (1) is positioned within the notch (24), the downstream movement of the first valve stem (21) is reliably suppressed, and the movement of the valve body can be delayed. Therefore, it is possible to prevent the overflow prevention valve (100) from unintentionally closing in a simulated overflow state.

[0036] In actual overflow conditions, the valve stem impact member (1) is further pushed by the tip of the first valve stem (21), causing it to elastically swing within the notch (24) toward the outer opening, as shown by the dashed line in Figure 6, thereby moving the first valve stem (21) downstream beyond the valve stem impact member (1). This allows the valve body (2) to be pressed against the valve seat (11), thereby closing the overflow prevention valve (100). Furthermore, in this case, it is desirable to set the notch area of ​​the notch portion (24) so ​​that the valve shaft impact member (1) is positioned offset to the outside of the center of the valve shaft hole (20a) so that the first valve shaft (21) can swing smoothly to the outer opening portion.

[0037] The third embodiment shown in Figure 7 is a modified example of the valve stem impact member (1), in which a substantially U-shaped extension wire (15) is extended diametrically from one of the open ends of the C-shaped ring body (10), and the rod-shaped portion from the bent part (16) to the free end functions as the valve stem impact member (1). Furthermore, a groove (13a) into which a C-shaped ring body (10) can be fitted is formed on the inner circumferential surface of the cylindrical body (13), and a notch (24) is formed in the guide cylinder (20) that communicates with the valve stem hole (20a) and penetrates across the guide cylinder (20), similar to the second embodiment described above.

[0038] In this design, the wire portion (15a) of the extension wire (15) from one open end of the C-shaped ring body (10) to the bent portion (16) is brought into contact with the outer surface of the guide cylinder (20) on the side where the notch (24) is not open, and the C-shaped ring body (10) is fitted into the groove (13a) of the main cylinder body (13) so that the valve stem impact member (1) from the bent portion (16) to the free end is positioned within the notch (24). This ensures that the valve stem impact member (1) is positioned downstream of the valve stem hole (20a), and the tip of the first valve stem (21) can be reliably struck by the valve stem impact member (1).

[0039] Furthermore, since the valve stem impact member (1) within the notch (24) is configured to swing with the bent portion (16) as its base end, its swing range is narrower and it is less prone to swinging compared to one with the open end of the C-shaped ring body (10) as its base end. Therefore, in a gas overflow state, when the tip of the first valve stem (21) collides with the valve stem impact member (1) from the upstream side as the valve body (2) moves, it takes a little time to swing the valve stem impact member (1) and cause the first valve stem (21) to protrude downstream from the valve stem hole (20a), thereby reliably delaying the movement of the valve body (2). Therefore, it is possible to reliably prevent the overflow prevention valve (100) from closing unintentionally in a pseudo-overflow state.

[0040] In an actual overflow state, the valve stem impact member (1) is further pushed by the tip of the first valve stem (21), allowing it to elastically swing outward within the notch (24) with the bent portion (16) as the pivot point, as shown by the dashed line in Figure 7. This allows the first valve stem (21) to move downstream beyond the valve stem impact member (1), pressing the valve body (2) against the valve seat and closing the valve.

[0041] In the fourth embodiment shown in Figure 8, the C-shaped ring body (10) is made into a coil spring (10a), which is fitted onto a cylindrical main body (13) that extends downstream of the guide cylinder (20), and the downstream end edge of the coil spring (10a) is bent and extended toward approximately the center so that it functions as a valve stem impact member (1).

[0042] By positioning the valve stem impact member (1) so as to intersect the valve stem hole (20a) of the guide cylinder (20) downstream, in the event of excessive gas outflow, the first valve stem (21) moves downstream together with the valve body (2), and the tip of the first valve stem (21) pushes the valve stem impact member (1) from the upstream side. However, the coil spring (10a) constituting the C-shaped ring body (10) stretches axially according to the number of turns of the coil. This increases the time that the valve stem impact member (1) presses against the first valve stem (21), thereby delaying the operation of the valve body (2). Therefore, the instantaneous excessive gas outflow in the pseudo-excessive gas outflow state can be reliably eliminated, and valve closing due to unintentional movement of the valve body (2) can be prevented. Furthermore, because the valve stem impact member (1) has a coil spring (10a) portion, it is easily oscillated. Therefore, in an actual overflow situation, when the valve stem impact member (1) is pushed by the tip of the first valve stem (21), it oscillates quickly, moving the first valve stem (21) downstream beyond the valve stem impact member (1) and pressing the valve body (2) against the valve seat (11). In this way, the overflow prevention valve (100) can be reliably closed in the event of an actual gas overflow, thus improving safety.

[0043] In the fifth embodiment shown in Figure 9, the C-shaped ring body (10) is also used as a coil spring (10a), but it is fitted inside a cylindrical body (13) that extends downstream of the guide cylinder (20), and both the upstream and downstream edges of the coil spring (10a) are bent and extended toward approximately the center so that they protrude and intersect downstream of the valve stem hole (20a). This results in a configuration in which two valve stem impact members (1a) and (1b) are provided.

[0044] In this embodiment, when there is an overflow of gas, the tip of the first valve stem (21), which moves downstream together with the valve body (2), first collides with the valve stem impact member (1a) located upstream, causing the valve stem impact member (1a) to swing elastically, and after passing through the valve stem impact member (1a), it then collides with the valve stem impact member (1b) located downstream. In this way, the first valve stem (21) is held down twice by the two valve stem impact members (1a) and (1b), so the time for the first valve stem (21) to elastically swing the valve stem impact members (1a) and (1b) is also doubled. Therefore, the operating speed of the valve body (2) can be further delayed, the momentary overflow condition in the pseudo-overflow state can be reliably eliminated, and the inadvertent closing of the overflow prevention valve (100) can be reliably prevented.

[0045] Furthermore, in order to further delay the operating speed of the valve body (2) in the pseudo-overflow state, although not shown in the diagram, it is also conceivable to make the first valve stem (21) tapered, becoming thicker towards the upstream side, and gradually increase the frictional force when the first valve stem (21) is inserted through the valve stem hole (20a) of the guide cylinder (20).

[0046] In each of the above embodiments, the valve stem impact member (1) is a rod-shaped portion that is linearly extended from the open end of the C-shaped ring body (10), resulting in a simple structure and easy manufacturing. Furthermore, the first valve stem (21) can elastically swing the valve stem impact member (1) and allow it to pass smoothly, so there is no catching between it and the first valve stem (2), and the operating flow rate does not fluctuate significantly. [Explanation of Symbols]

[0047] (100) ······Overflow prevention valve (1) ·······Valve shaft impact member (2) ······· Valve body (11)·······Valve seat (12)·······Valve receiving section (13) · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · (20)·······Guide tube (20a) ... Valve stem hole (21)... Valve stem (1st valve stem)

Claims

1. An overflow prevention valve comprising: a cylindrical body incorporated into a gas flow path; a valve seat formed on the inner circumferential surface of the cylindrical body; a substantially disc-shaped valve body that moves downstream from a state biased in the valve-opening direction to airtightly press against the valve seat when gas overflow occurs; a valve shaft that integrally protrudes at least downstream from the center of the valve body; a valve receiving portion provided at the upstream end of the cylindrical body to receive the valve body when it is biased in the valve-opening direction; and a guide cylinder provided at the downstream end of the cylindrical body having a valve shaft hole in the center through which the valve shaft can be inserted, wherein A valve stem impact member made of elastic wire is positioned downstream of the guide cylinder and intersects with the valve stem hole. An overflow prevention valve configured such that, when the valve body is operated, the tip of the valve shaft protrudes downstream from the valve shaft hole of the guide cylinder and collides with the valve shaft impact member before the valve body seats on the valve seat.

2. An overflow prevention valve according to claim 1, wherein the valve shaft impact member is provided so as to be perpendicular to the central axis of the valve shaft hole of the guide cylinder.

3. An overflow prevention valve according to claim 1, wherein the valve shaft impact member has a free end on one side.

4. An overflow prevention valve according to claim 1, wherein the valve shaft impact member is a rod-shaped portion that is bent and extended in the diametrical direction from at least one open end of a C-shaped ring body.

5. An overflow prevention valve according to claim 4, wherein a holding portion for holding the C-shaped ring body is provided on the cylindrical main body downstream of the valve seat.

6. An overflow prevention valve according to claim 4, wherein the C-shaped ring body is a coil spring.

7. An overflow prevention valve according to claim 1, wherein a plurality of valve shaft impact members are provided.

8. In the overflow prevention valve according to claim 1, the guide cylinder is provided with a notch that communicates with the valve shaft hole and penetrates the guide cylinder in a direction perpendicular to the axis of the guide cylinder, The valve stem impact member is provided so as to intersect the valve stem hole when inserted into the notch, An overflow prevention valve in which the radial notch depth of the notch is set such that the valve shaft impact member can swing to a position away from the valve shaft hole.

9. An overflow prevention valve according to any one of claims 1 to 8, wherein, during the operation of the valve body, the tip of the valve shaft collides with the valve shaft impact member in the latter half of the operation process in which the valve body moves from its initial position until it sits on the valve seat.

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