JP2008298109A - Backflow prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backflow prevention device capable of preferably maintaining the durability of a valve element using a diagram, and preferably maintaining the durability of a backflow prevention function and the entire device. <P>SOLUTION: A lip 914 is protruded from a lower surface at the inner periphery side of a valve 913 of the diagram 91 to be brought into close contact with the inner periphery side 76a of a valve seat 76 which is an opening edge surface to close the valve. At this time, a doughnut annular portion 111 of a spring receiving member 11 is sandwiched between the valve 913 and a stopper 76b which is the outer periphery side of the valve seat 76, working as a spacer to prevent the diagram 91 from lowering further, thus preventing the further compression deformation of the lip 914. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention applies a primary side pressure to one side of a valve body using a diaphragm and a secondary side pressure to the other side, and opens and closes the secondary side by opening and closing based on a pressure difference between the primary side and the secondary side. The present invention relates to a backflow prevention device used for preventing backflow from a side to a primary side.

  Conventionally, as a backflow prevention device of this type, a diaphragm has been used for the valve body. During normal operation, the pressure on the primary side applied to one side of the valve body is increased to maintain the valve body in a closed state. When the pressure on the secondary side applied to the other side of the body is greater than that on the primary side, the valve is opened and hot water from the secondary side is discharged to prevent backflow from the secondary side to the primary side. What was made is known (for example, refer to Patent Document 1). In this case, in order to prevent the diaphragm from being pushed into the valve seat and biting into the valve seat, the outer circumference of the diaphragm is prevented from locally exceeding the elastic limit of the material of the diaphragm. The support portion is covered and supported by a hard stopper portion, and a receiving portion is formed on the inner surface of the valve housing that abuts against the stopper portion and restricts further downward movement.

JP 2004-324666 A

  However, in the conventional backflow prevention device, the diaphragm lowering is insufficiently regulated due to the deformation of the diaphragm, and as a result, the diaphragm material may be damaged.

  That is, the conventional backflow prevention device employs the following structure. For example, as shown in FIG. 8A, for example, a diaphragm plate 202 is overlapped from above so as to cover the valve portion 201 of the diaphragm 200, while the outer peripheral portion of the valve portion 201 of the diaphragm 200 is covered by a spring receiving member 203. I try to cover it. As the spring receiving member 203, a peripheral wall portion 205 that enters the folded portion 204 of the diaphragm 200, which is the outer peripheral side portion of the valve portion 201, from the bottom to prevent inversion, and a lower end corner portion of the outer periphery of the valve portion 201 from below. It is assumed that a covering corner portion 206 and a spring receiving portion 207 formed on the lower surface are provided, and a stopper step portion 208 with which the corner portion 206 abuts is formed on the inner surface of the housing.

  However, when the primary pressure is applied from above the diaphragm plate 202, the outer peripheral side portion of the valve portion 201 of the diaphragm 200 is connected to the corner portion 206 and the stopper step portion 208 of the spring receiving member 203 as shown in FIG. Although the lowering of the valve portion 201 is restricted by the contact, the inner peripheral side portion of the valve portion 201 may be further displaced downward due to the deflection of the diaphragm plate 202. If it becomes like this, the valve seat 209 bites into the valve part 201 with a considerable strength, and there is a possibility that a situation in which the elastic limit of the material of the diaphragm 200 is exceeded will occur. As a result, the backflow prevention function may be deteriorated or the durability of the whole backflow prevention device may be deteriorated, so that the entire device may be replaced.

  The present invention has been made in view of such circumstances, and the object of the present invention is to maintain the durability of the valve body using the diaphragm well and to prevent the backflow prevention function and the durability of the entire apparatus. An object of the present invention is to provide a backflow prevention device that can be maintained well.

  In order to achieve the above object, according to the present invention, the diaphragm contacts the valve seat based on the differential pressure between the primary pressure acting in the valve closing direction and the secondary pressure acting in the valve opening direction. The following specific matters are provided for the backflow prevention device configured to switch between the drainage passage and the secondary passage to the cut-off state or the communication state by contacting and separating. That is, a lip portion that is formed so as to protrude from the diaphragm toward the valve seat and closes by contacting the valve seat, and when the lip portion contacts the valve seat, A spacer for limiting the compression allowance of the lip portion to a predetermined range by being sandwiched between the diaphragm and the diaphragm is provided (claim 1).

  In order to achieve the above object, in the present invention, the diaphragm built in the housing is based on the differential pressure between the primary pressure acting in the valve closing direction and the secondary pressure acting in the valve opening direction. The following specific matters are provided for a backflow prevention device configured to switch between a drainage passage and a secondary passage to a shut-off state or a communication state by abutting and separating from the valve seat. It was decided. That is, it includes a stopper provided in the vicinity of the outer peripheral side of the valve seat, and a spacer provided at a position on the valve seat side of the diaphragm that can be stopped against the stopper. . When the diaphragm contacts the valve seat and closes as the spacer, the compression margin of the diaphragm pressed against the valve seat by being sandwiched between the diaphragm and the stopper is within a predetermined range. The thickness is set so as to be limited to (Claim 1).

  In the case of the present invention, when the diaphragm is closed due to the differential pressure, even if the diaphragm is pressed against the valve seat, the diaphragm is sandwiched between the stopper and the diaphragm so that the diaphragm is It will be limited not to be compressed beyond the compression allowance of the range. For this reason, it is possible to reliably avoid the occurrence of a situation in which the diaphragm is subjected to excessive compression and causes a decrease in durability, thereby maintaining the durability of the valve body using the diaphragm well and preventing backflow. The function and durability of the entire apparatus can be maintained well.

  More specifically, the present invention can be broadly divided into the following two types of specific configurations.

  That is, firstly, the diaphragm is provided with a lip portion that is formed so as to protrude from the diaphragm toward the valve seat and is closed by contacting the valve seat, In the valve-closed state, it is possible to adopt a configuration in which the compression allowance of the lip portion is limited to a predetermined range by being sandwiched between the stopper portion and the diaphragm other than the lip portion.

  In this case, when the diaphragm is closed due to differential pressure, the spacer is sandwiched between the stopper and the diaphragm other than the lip even if the lip is pressed against the valve seat. Thus, the lip portion is restricted so as not to be compressed beyond a predetermined range of compression allowance. For this reason, it is possible to reliably avoid the occurrence of a situation in which the lip portion and the diaphragm having the lip portion are subjected to excessive compression and cause a decrease in durability. As a result, as described above, the valve body using the diaphragm Therefore, the backflow prevention function and the durability of the entire apparatus can be maintained well. More preferably, the thickness of the spacer can be set to a dimension obtained by subtracting the allowable compression allowance of the lip portion from the protruding height of the lip portion. By doing in this way, it becomes possible to restrict | limit the compression allowance of a lip | rip part to the range within an allowable compression allowance reliably, and can maintain the durability of a lip | rip part and a diaphragm which has this best. .

  Secondly, the valve seat has a cross-sectional shape protruding toward the diaphragm side, while a portion that contacts the valve seat as the diaphragm is formed on a flat surface, and the valve seat serves as the spacer on the diaphragm. It is possible to adopt a configuration in which the compression allowance for compressing the diaphragm by biting in after contact is limited to a predetermined range.

  In this case, when the diaphragm reaches the valve closing state due to the differential pressure, even if the diaphragm is pressed against the valve seat and the valve seat bites into the flat surface of the diaphragm, the spacer does not move between the stopper and the diaphragm. By being sandwiched between them, the amount of biting is limited, and the diaphragm is limited so as not to be compressed beyond a predetermined range of compression allowance. For this reason, it is possible to reliably avoid the occurrence of a situation in which the diaphragm is subjected to excessive compression and causes a decrease in durability. As a result, the durability of the valve body using the diaphragm is maintained well as described above. Thus, the backflow prevention function and the durability of the entire apparatus can be maintained satisfactorily. More preferably, the thickness of the spacer is set to a dimension obtained by subtracting the allowable compression allowance of the diaphragm based on the protrusion height of the valve seat into the diaphragm from the protruding height of the valve seat. (Claim 5). By doing in this way, it becomes possible to restrict | limit the amount of biting (compression allowance) of a valve seat to the range within the allowable compression allowance of a diaphragm reliably, and can maintain the durability of a diaphragm best. .

  In the above-described backflow prevention device, a spring for urging the diaphragm in the valve opening direction and a spring receiving member assembled to the diaphragm to transmit the urging force from the spring to the diaphragm are provided, and the spacer is a spring. It can comprise by a part of receiving member (Claim 6). By doing so, it becomes possible to provide the spacer specifically and easily, and it is possible to avoid inconveniences such as an increase in the number of parts due to the combined use with the spring receiving member.

  Further, in the above-described backflow prevention device, as the diaphragm, a flat plate-like valve portion opposed to the valve seat, and a displacement of the valve portion in contact with and separating from the valve seat continuous with the outer peripheral side of the valve portion are allowed. A turn-back portion can be provided, and a reversal prevention wall can be integrally formed in the housing, the tip of which is inserted into the turn-up portion to maintain the turn-back shape. By doing in this way, even if the primary side pressure is received and the valve is closed, the folded shape of the folded portion is maintained, so that it is possible to prevent the occurrence of inversion of the folded portion, It is possible to ensure the backflow prevention function by surely realizing the abutment / separation displacement of the diaphragm. Moreover, since the anti-inversion wall is integrally formed with the housing as a support element for preventing the turn-up portion from being reversed, there is no need to provide special parts for the support element, and the number of parts can be reduced and the structure can be reduced. Simplification can also be achieved.

  As described above, according to the backflow prevention device of any one of claims 1 to 7, even if the diaphragm is pressed against the valve seat when the diaphragm reaches the valve closing state due to the differential pressure, Since the spacer is sandwiched between the stopper and the diaphragm, the diaphragm can be restricted so as not to be compressed beyond a predetermined range of compression allowance. For this reason, it is possible to reliably avoid the occurrence of a situation in which the diaphragm is subjected to excessive compression and causes a decrease in durability, thereby maintaining the durability of the valve body using the diaphragm well and preventing the backflow. And the durability of the entire apparatus can be maintained satisfactorily.

  In particular, according to claim 2 or claim 3, when the lip portion is pressed against the valve seat when the diaphragm reaches the valve closing state due to the differential pressure, the spacer is not the stopper portion and the lip portion. By being sandwiched between the diaphragm and the diaphragm, the lip portion can be restricted so as not to be compressed beyond a predetermined range of compression allowance. For this reason, it is possible to reliably avoid the occurrence of a situation in which the lip portion and the diaphragm having the lip portion are subjected to excessive compression and cause a decrease in durability, and as described above, the valve body using the diaphragm can be prevented. The durability can be maintained well, and the backflow prevention function and the durability of the entire apparatus can be well maintained. According to claim 3, the compression margin of the lip portion can be surely limited to a range within the allowable compression margin, and the durability of the lip portion and the diaphragm having the lip portion can be best maintained. become.

  According to claim 4 or claim 5, when the diaphragm is closed due to the differential pressure, even if the diaphragm is pressed against the valve seat and the valve seat bites into the flat surface of the diaphragm, the spacer does not touch. By being sandwiched between the stop portion and the diaphragm, it is possible to limit the amount of biting so that the diaphragm is not compressed beyond a predetermined range of compression allowance. For this reason, as described above, it is possible to reliably avoid the occurrence of a situation in which the diaphragm is excessively compressed and the durability is deteriorated, thereby maintaining the durability of the valve body using the diaphragm well. Thus, the backflow prevention function and the durability of the entire apparatus can be maintained satisfactorily. According to the fifth aspect, the amount of biting (compression allowance) of the valve seat can be surely limited to a range within the allowable compression allowance of the diaphragm, and the durability of the diaphragm can be maintained best. become.

  According to the sixth aspect of the present invention, the spacer is configured by a part of the spring receiving member, so that the spacer can be provided specifically and easily, and the number of parts can be increased by using the spring receiving member. Inconvenience can be avoided.

  Further, according to the seventh aspect, even if the valve is closed due to the primary pressure, the reversal prevention wall can prevent the folding portion from reversing, and the diaphragm can be prevented from coming into contact or separated. The displacement can be reliably realized and the backflow prevention function can be secured. In addition, since the inversion prevention wall is formed integrally with the housing, the number of parts can be reduced and the structure can be simplified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a composite heat source device having a hot water supply function, a hot water filling function, and a reheating function as an example to which the backflow prevention device according to the embodiment of the present invention is applied. The target to which the backflow prevention device of the present invention is applied is not limited to that illustrated in FIG. 1, and may be a fluid device including a primary side flow path and a secondary side flow path.

  1 includes a hot water supply circuit 2, a recirculation circuit 3 that replenishes hot water in the bathtub 61, and a recirculation circuit 3 that replenishes hot water in the hot water supply circuit 2 to fill the bathtub 61. And a can 5 containing a combustion burner 51 to heat and heat the hot water in the hot water supply circuit 2 and the recirculation circuit 3. .

  The hot water supply circuit 2 heat-exchanges and heats the water introduced into the hot water supply heat exchanger 22 from the water inlet 21 connected to the water pipe by the combustion heat of the combustion burner 51, and supplies the heated hot water to the hot water outlet 23. Thus, hot water is supplied to the hot-water tap 62 at the downstream end. A bypass passage 24 that bypasses the heat exchanger 22 is provided between the water inlet passage 21 and the hot water outlet passage 23, and the mixing ratio of water to the hot water from the hot water outlet passage 23 is adjusted by adjusting the opening degree of the bypass control valve 24a. Is adjusted and the temperature of the hot-water tap 62 can be adjusted.

  An incoming water flow rate sensor 25 and an incoming water temperature sensor 26 are disposed in the water inlet channel 21, while hot water is discharged from the can 5 at a position near the outlet of the heat exchanger 22. A can body temperature sensor 27 for detecting the temperature of the hot water immediately after, a hot water supply flow rate control valve 28, and a hot water supply temperature sensor 29 for detecting the temperature of hot water supplied to the hot water tap 62 or the pouring channel 41 described later are disposed. Has been.

  The recirculation circuit 3 includes a circulation path 31, a circulation pump 32, and a reheating heat exchanger 33. The circulation path 31 operates the circulation pump 32 to return the hot water in the bathtub 61 to the heat exchanger 33 and the hot water heated by the heat exchanger 33 by the combustion heat of the common combustion burner 51. It is comprised from the outgoing path 31b supplied to the bathtub 61. FIG. The return path 31a includes, in order from the upstream side in the circulating direction of the circulating hot water, the circulating pump 32, the water flow switch 34 that outputs an ON command when the circulating flow passes, and the hot water in the bathtub 61 by detecting the temperature of the circulating hot water. And a bath temperature sensor 35 for detecting the temperature (bath temperature).

  Further, between the hot water supply path 23 of the hot water supply circuit 2 and the circulation path 31, pouring hot water from the hot water supply path 23 into the circulation path 31 to pour the hot water into the bathtub 61 and fill it with hot water. A runway 41 is provided. The pouring passage 41 has an upstream end branched from a hot water supply passage 23 at a downstream position of the hot water supply temperature sensor 29, and a downstream end communicated with, for example, a return passage 31 a of the circulation passage 31. In the pouring channel 41, a pouring flow rate sensor 42 that detects the pouring flow rate, a pouring electromagnetic valve 43 that switches between filling and stopping by open / close control, and reverse flow into the hot water supply circuit 2 side are prevented. Two-stage check valves 44, 44 are provided for this purpose.

  When the pouring electromagnetic valve 43 is opened and pouring is started, hot water from the hot water supply passage 23 is supplied to the return passage 31a through the pouring passage 41, and the supplied hot water reaches the bathtub 61 through the return passage 31a and the like. The hot water filling of the bathtub 61 is performed after pouring. The flow path of the hot water supply circuit 2 extending from the water inlet path 21 to the hot water outlet path 23 constitutes a primary side flow path (or simply “primary side”), branches from the hot water outlet path 23 on the upstream side, and the pouring path 41. The flow path from the return path 31a (or the circulation path 31 including the forward path 31b) to the bathtub 61, which is the most downstream side, constitutes a secondary flow path (or simply “secondary side”).

  And the backflow prevention apparatus 7 is assembled | attached to said pouring circuit 4. FIG. The backflow prevention device 7 is connected so that the secondary side connection port 71 (see, for example, FIG. 2) communicates with the pouring channel 41 at the intermediate position between the check valves 44, 44, and the primary side connection port 72. (For example, see FIG. 2) is connected to the water inlet 21 of the hot water supply circuit 2 via the pressure guide path 72a so that the water pressure can be introduced, and the drain connection port 73 (for example, see FIG. 2) is connected to the drain path. The heat source machine case 1a is extended through 73a.

<First Embodiment>
Hereinafter, the backflow prevention device 7 according to the first embodiment will be described in detail with reference to FIG. 2 and subsequent drawings. In the following description, the vertical direction of the drawing is described as the vertical direction, or the horizontal direction of the drawing is described as the horizontal direction. However, the actual usage of the backflow prevention device 7 is not limited to the state shown in the drawing, but is laid down. Needless to say, various arrangements such as a tilted state and a vertically reversed state may be employed. This also applies to the second and subsequent embodiments.

  The backflow prevention device 7 according to the first embodiment includes a housing 8, a valve body 9 including a diaphragm 91 and a diaphragm plate 92, a spring (for example, a coil spring) 10 that biases the valve body 9 to the open side, and the spring. 10 is provided with a spring receiving member 11 that supports one end of 10 and transmits the urging force thereof to the valve body 9.

  In the present embodiment, the housing 8 is formed by joining two divided housing portions 81 and 82 to each other, but the number of divisions and the like can be appropriately selected. The housing 8 has a secondary side passage 74 extending from the secondary side connection port 71 and a drainage connection port 73 extending in a direction perpendicular to the secondary side passage 74 and projecting into the secondary side passage 74. The primary side pressure operation that extends so as to face the valve seat 76 formed by the drainage passage 75 opened in the state and the opening end face of the drainage passage 75 and communicated with the primary side connection port 72 so that the primary side internal pressure can be introduced. A chamber 77 is formed. Then, the valve body 9 is installed so as to partition the primary pressure working chamber 77 and the valve seat 76, and the opening of the valve seat 76 is closed when the valve body 9 contacts the valve seat 76 (see FIG. 2). The secondary side passage 74 and the drainage passage 75 are blocked from each other, and the valve body 9 is separated from the valve seat 76 upward in the drawing, so that the opening of the valve seat 76 is opened. The secondary side passage 74 and the drainage passage 75 are communicated with each other.

  A circumferential groove 78 in which an outer peripheral fastening edge 911 (see FIG. 3A) of the diaphragm 91 is fitted and held in an airtight state in a peripheral wall portion of the housing 8 that defines the primary pressure working chamber 77, A peripheral wall 79 is formed as an inversion prevention wall for preventing inversion by being inserted into the folding portion 912 from below to maintain the folded shape of the folded portion 912 of the diaphragm 91. Further, the inner surface of the housing 8 that defines the primary pressure working chamber 77 is in contact with the flange portion 923 of the diaphragm plate 92 of the valve body 9 in the valve-opened state (see FIG. 3B). A stopper portion 771 that restricts movement toward the separation side (the valve opening direction; the upper side of the drawing) is formed.

  The valve body 9 includes a diaphragm 91 (see FIG. 3A) and a diaphragm plate 92 superimposed on the upper side of the diaphragm 91 (the side on which the primary pressure from the primary side connection port 72 acts). ing. The diaphragm 91 includes an outer peripheral fastening edge 911 formed at the outer peripheral edge position, a relatively thin folded portion 912 at the inner peripheral side position, and a relatively thick and flat plate portion at the center position. 913. The diaphragm plate 92 is formed in a flat plate shape and is in close contact with the valve portion 913, a peripheral wall 922 rising from the periphery of the bottom wall 921, a flange portion 923 protruding from the upper end of the peripheral wall 922 to the outer peripheral side, An engagement convex portion 924 that hangs down from the center position of the bottom wall 921 is provided.

  The valve portion 913 is set to have a sufficiently larger diameter than the valve seat 76, and an endless annular lip so as to abut on the inner peripheral side portion of the valve seat 76 from the lower surface (the surface opposite to the valve seat 76). A portion 914 is formed to protrude. The lip portion 914 is set to have a cross-sectional shape such as an inverted triangle so that the tip end side is sharp and can come into contact with the valve seat 76 by line contact. The engagement projection 924 is pressed into the through hole at the center position of the valve portion 921 so that the diaphragm plate 92 and the diaphragm 91 are integrally assembled so as not to drop off.

  As shown in FIG. 4, the spring receiving member 11 includes a donut ring portion 111 as a spacer having a predetermined plate thickness, and a return edge portion 112 bent at a right angle from the outer peripheral edge of the donut ring portion. It consists of The inner diameter of the return edge portion 112 is set to be larger than the outer diameter of the spring 10 so that the upper end which is one end of the spring 10 is held inside. Further, the inner diameter of the donut ring portion 111 is set to be larger than the outer diameter of the lip portion 914 and smaller than the outer diameter of the cylindrical portion 75 a that protrudes into the secondary side passage 74 and constitutes the drainage passage 75. The outer diameter of the donut ring portion 111 is set to be substantially the same as that of the valve portion 913. As a result, the donut ring portion 111 of the spring receiving member 111 abuts and supports the lower surface of the valve portion 913 of the diaphragm 91 in contact with the lower surface of the outer peripheral side than the lip portion 914 of the diaphragm 91, while the valve bottom is particularly closed It is made to contact | abut to the outer peripheral side site | part of the valve seat 76 in the below-mentioned crimping | compression-bonding state which is a state.

In the backflow prevention device 7 described above, if the water supply side equipment or the like for the heat source unit 1 (see FIG. 1) is normal, the hot water supply circuit 2 of the hot water supply circuit 2 serves as the primary side pressure in the primary side pressure working chamber 77 through the primary side connection port 72. A feed water pressure is introduced from the uppermost stream of the water inlet 21, and the feed water pressure always acts on the valve body 9. On the other hand, in the state where the bathtub 61 is not used and the hot water filling using the pouring circuit 4 (see FIG. 1) is not performed (the pouring electromagnetic valve 43 is closed), the secondary side pressure in the secondary side passage 74 is set. Becomes almost atmospheric pressure and becomes smaller than the primary pressure, and the hot water solenoid valve 43 is opened, and hot water in the hot water supply circuit 2 is poured from the hot water supply passage 23 through the hot water supply circuit 4 to fill the hot water. Even in this state, since the supply water pressure on the most upstream side is subjected to various flow path resistances, the secondary side pressure acting on the secondary side passage 74 based on the pouring is smaller than the primary side pressure. For this reason, the valve body 9 has a primary side pressure P ₁ (see FIG. 2) from the primary side pressure working chamber 77 across the valve body 9 and a secondary side pressure P ₂ from the secondary side passage 74. Based on the differential pressure, it is pressed against the valve seat 76, and the valve is closed and the secondary passage 74 and the drainage passage 75 are blocked. The valve closed state is a contact state in which the distal end portion of the lip portion 914 of the diaphragm 91 constituting the valve body 9 is in contact with the valve seat 76 in a line contact state depending on the above-described differential pressure (FIG. 3 ( From the state shown in a) to the pressure-bonded state (the state shown in FIG. 5) in which the lip portion 914 is slightly compressed and deformed and is brought into a surface contact state with the valve seat 76 by being further strongly pressed to the valve seat 76 side. .

  On the other hand, in the state where the hot water is poured through the hot water pouring circuit 4 and the hot water is filled, for example, the water supply pressure from the water supply source to the hot water supplying circuit 2 (the water intake channel 21) decreases due to a power failure or the like. In the event that a tendency occurs, the primary pressure introduced into the primary pressure working chamber 77 also decreases or tends to be negative. In this case, the secondary side pressure introduced through the secondary side passage 74 becomes higher than the primary side pressure, and the valve body 9 is opened to communicate with the pouring channel 41. The passage 74 and the drainage passage 75 are in communication with each other (see FIG. 3B). For this reason, for example, even if the check valve 44 has an abnormality such as a foreign object biting and a reverse flow occurs through the pouring channel 41, the reverse flow is drained through the secondary side passage 44 and the drainage passage 75 and is on the primary side. Backflow to the hot water supply circuit 2 side can be reliably prevented.

  Here, in the crimped state, as shown in detail in FIG. 5B, the donut ring portion 111 of the spring receiving member 11 is between the valve portion 913 of the diaphragm 91 and the outer peripheral side portion 76 b of the valve seat 76. The donut ring portion 111 is sandwiched between the two and the role of the spacer so that the lowering of the valve body 9 (movement toward the side pressed against the valve seat 76) is restricted. become. By this lowering restriction, compression deformation of the lip portion 914 can be restricted / prevented beyond a certain amount, and in particular, the lip portion 914 itself or the diaphragm 91 having the lip portion 914 exceeds the elastic limit. It is possible to prevent occurrence of a situation in which durability is lowered by reliably preventing occurrence of such a situation. Thereby, durability of the valve body 9 using the diaphragm 91 can be maintained favorably.

In such a structure, the inner peripheral side portion 76a of the valve seat 76 functions as an original valve seat that maintains a closed state due to close contact with the lip portion 914, and the outer peripheral side portion 76b contacts the donut annular portion 111. The outer peripheral side portion 76b constitutes a stopper portion that functions as a stopper portion that serves as a stopper that stops and restricts the compression deformation (compression allowance) of the lip portion 914 to a certain amount. Further, the donut ring part 111 covers and closely adheres to the lower surface of the diaphragm 91 in the range from the outer peripheral side of the lip part 914 to the outer peripheral side position of the valve part 913, and maintains the diaphragm 91 in that range in a flat state. since the support, and it is possible to maintain the valve unit 913 also receives the primary pressure P ₁ to ensure flat state, it is possible to maintain a stable closed state. In short, while the lip portion 914 can reliably shut off the valve closed state, the donut ring portion 111 increases the durability of the lip portion 914 while reliably maintaining the valve portion 913 in a flat plate state. Can be stably maintained or reproduced repeatedly.

  For example, as shown in FIG. 3A, if the allowable compression deformation amount (allowable compression allowance) is S with respect to the protrusion height H of the lip portion 914, the donut ring portion 111 of the donut ring portion 111 can be obtained. E = HS is set as the thickness E. By setting the wall thickness E in this manner, the compression allowance of the lip portion 914 can be surely limited to the allowable compression allowance, and the durability of the lip portion 914 and the diaphragm 91 having the lip portion 914 can be best maintained. Will be able to. Here, if the wall thickness E is made larger, the amount of compressive deformation S of the lip 914 becomes smaller and the contact range with respect to the valve seat 76 becomes smaller, and if the wall thickness E is made smaller, the compression of the lip 914 is reduced. The deformation amount S becomes larger and the contact range with respect to the valve seat 76 becomes larger. Accordingly, the allowable compression deformation amount S is set in consideration of the elasticity and valve closing function of the material of the diaphragm 91, and the wall thickness E of the donut ring portion 111 of the spring receiving member 11 is set based on the allowable compression deformation amount S. Should be set.

Further, in the above valve closed state, since the peripheral wall 79 of the housing 8 enters the inside of the folded portion 912 of the diaphragm 91, even if the crimped state is received by receiving the primary side pressure P ₁ , It is possible to prevent the occurrence of inversion. Moreover, since the peripheral wall 79 is integrally formed with the housing 8 as a support element for supporting the folded portion 912 in the folded state to prevent the reversal, it is necessary to provide a special part for the support element. In addition, the number of parts can be reduced and the structure can be simplified.

  In the above embodiment, the spacer is constituted by the donut ring portion 111 which is a part of the spring receiving member 11. However, the present invention is not limited to this, and the spacer may be provided separately from the spring receiving member. Good.

Second Embodiment
FIG. 6 shows a backflow prevention device according to the second embodiment. As shown in FIG. 6 (a), this backflow prevention device omits the lip portion 914 in the first embodiment from the valve portion 913 of the diaphragm 91a to form a lower surface on a flat surface, and constitutes a drainage passage 75. The valve seat 76c having a substantially triangular cross-sectional shape is formed on the inner peripheral portion of the opening end surface of the cylindrical portion 75a to project toward the diaphragm 91a, and the donut ring of the spring receiving member 11 is formed with the outer peripheral portion being a flat surface. A stop portion 76d is formed in which the portion (spacer) 111 comes into contact and is stopped. Except for these differences, the other configurations are the same as those of the first embodiment, and the same reference numerals as those of the first embodiment are attached to the same components as those of the first embodiment, and the detailed description is repeated. Omitted.

  In the valve closing state in this case, from the contact state in which the tip of the valve seat 76c is in contact with the lower surface of the valve portion 913 of the diaphragm 91a in a substantially line contact state (the state indicated by the one-dot chain line in FIG. 6B), Further, the valve body 9 descends due to a larger differential pressure and reaches a pressure-bonded state (a state indicated by a solid line in FIG. 6B) where a part of the valve seat 76c bites into the valve portion 913 and stops.

  In this crimped state, the donut ring portion 111 is sandwiched between the valve portion 913 and the stopper portion 76d and serves as a spacer, so that the valve seat 76c is prevented from further biting into the valve portion 913.・ It will be regulated. For this reason, it is possible to reliably avoid a decrease in the durability of the diaphragm 91a due to excessive biting of the valve seat 76c.

  In order to achieve such an effect, the relationship between the protruding height H of the valve seat 76c and the thickness E of the donut annular portion 111 as a spacer may be as follows. That is, the allowable bite amount (allowable compression allowance) S to the valve portion 913 is set out of the protruding height H of the valve seat 76c from the stop portion 76d, and S is subtracted from H to decrement the donut ring portion 111. The wall thickness E (E = HS) may be set. As a result, the compression amount of the diaphragm 91a can be reliably limited to a range within the allowable compression allowance.

<Another aspect 1 of the second embodiment>
In FIG. 7A, the valve seat 76c is formed by projecting toward the diaphragm 91a on the inner peripheral side portion of the opening end surface of the cylindrical portion 75a constituting the drainage passage 75, and the lower surface of the valve portion 913 is flat. Although it is the same as said 2nd Embodiment in the point made into a surface, the inclined surface which becomes a downward gradient toward an outer peripheral side is formed in an outer peripheral side site | part, and this inclined surface is made into the donut ring part 111 of the spring receiving member 11. However, it is different in that it is a stop portion 76e that stops. Other configurations are the same as those in the second embodiment.

  In this case, when the contact state (the state indicated by the solid line in FIG. 7A) reaches the crimped state (the state indicated by the alternate long and short dash line in the same figure), the inner peripheral edge of the donut ring portion 111 is When it stops at 76e, further lowering of the valve portion 913 of the diaphragm 91a is prevented and restricted, and further biting into the valve portion 913 of the valve seat 76c can be avoided.

<Other aspect 2 of 2nd Embodiment>
In FIG. 7B, the valve seat 76c is formed by projecting toward the diaphragm 91a on the inner peripheral side portion of the opening end surface of the cylindrical portion 75a constituting the drainage passage 75, and the lower surface of the valve portion 913 is flat. Although it is the same as said 2nd Embodiment in the point made into a surface, the stop part which forms a recessed step part in an outer peripheral side site | part, and the donut ring part 111 of the spring receiving member 11 contacts this recessed step part It is different in that it is 76f. Other configurations are the same as those in the second embodiment.

  In this case, when the contact state (the state indicated by the solid line in FIG. 7B) reaches the pressure-bonded state (the state indicated by the alternate long and short dash line in FIG. 7), the inner peripheral edge of the donut ring portion 111 is When it stops at 76f, further lowering of the valve portion 913 of the diaphragm 91a is prevented and restricted, and further biting into the valve portion 913 of the valve seat 76c can be avoided.

<Other aspect 3 of 2nd Embodiment>
8A shows that the valve seat 76c is formed by projecting toward the diaphragm 91a on the opening end surface of the cylindrical portion 75a 'constituting the drainage passage 75, and that the lower surface of the valve portion 913 is made flat. Are the same as those of the second embodiment described above, except that longitudinal ribs 75c, 75c,... (See also FIG. 8B) are formed on the outer peripheral surface of the cylindrical portion 75a ′. The difference is that the upper end surface of the vertical rib 75c is a stop portion 76g that the donut ring portion 111 of the spring receiving member 11 stops. Other configurations are the same as those in the second embodiment.

  In this case, when the contact state (the state indicated by the one-dot chain line in FIG. 9B) reaches the pressure-bonded state (the state indicated by the solid line in FIG. 9B), the inner peripheral edge of the donut ring portion 111 is When it stops at 76g, further lowering of the valve portion 913 of the diaphragm 91a is prevented and restricted, and further biting into the valve portion 913 of the valve seat 76c can be avoided.

It is a mimetic diagram of a heat source machine to which an embodiment of the present invention is applied. It is sectional drawing of the backflow prevention apparatus of 1st Embodiment. 3A shows the valve closed state in the contact state as a partially enlarged view of FIG. 2, and FIG. 3B shows the valve open state. It is a disassembled perspective view of a spring receiving member, a spring, and a valve seat. FIG. 5 (a) is a view corresponding to FIG. 3 (a) showing the valve closing state in the crimped state, and FIG. 5 (b) is a partially enlarged view of FIG. 5 (a). FIG. 6A is a view corresponding to FIG. 3A of the second embodiment, and FIG. 6B is a partial cross-sectional view showing a valve closing state in a crimped state by a partially enlarged state of FIG. 6A. is there. FIG. 7A is a partial cross-sectional view showing another aspect 1 of the second embodiment by a partially enlarged state of FIG. 3A, and FIG. 7B shows another aspect 2. FIG. FIG. FIG. 8 (a) is a view corresponding to FIG. 6 (a) showing another aspect 3 of the second embodiment, and FIG. 8 (b) is a cross-sectional explanatory view taken along the line AA of FIG. 8 (a). FIG. 9 is a diagram corresponding to FIG. 6B showing a part of FIG. FIG. 10 (a) is a view corresponding to FIG. 3 (a) for showing the conventional problems, and FIG. 10 (b) is a view of FIG. 10 (a) showing a state where the state of FIG. FIG.

Explanation of symbols

7 Backflow prevention device 8 Housing 9 Valve body 10 Spring 11 Spring receiving member 76 Valve seat 76a Inner peripheral side portion (valve seat)
76b Outer peripheral part (stopping part)
76c Valve seat 76d, 76e, 76f, 76g Stopping part 79 Perimeter wall (inversion prevention wall)
91 Diaphragm 111 Donut ring part (spacer)
912 Folding part 913 Valve part 914 Lip part E Thickness of donut ring part (spacer thickness)
S Allowable compression allowance H Projected height of lip or projecting height of valve seat

Claims (7)

Based on the differential pressure between the primary pressure acting in the valve closing direction and the secondary pressure acting in the valve opening direction, the diaphragm built in the housing abuts and separates from the valve seat, In the backflow prevention device configured to switch between the drainage passage and the secondary side passage to a cut-off state or a communication state,
A stopper provided at a position near the outer peripheral side of the valve seat, and a spacer provided at a position that is a valve seat side position of the diaphragm and can be stopped against the stopper,
The spacer restricts the compression allowance of the diaphragm pressed against the valve seat to a predetermined range by being sandwiched between the diaphragm and the stopper when the diaphragm contacts the valve seat and closes. The backflow prevention device is characterized in that the thickness is set so as to. The backflow prevention device according to claim 1,
The diaphragm includes a lip portion that is formed so as to protrude from the diaphragm toward the valve seat and is closed by contacting the valve seat.
The spacer is configured to restrict a compression allowance of the lip portion to a predetermined range by being sandwiched between the stopper portion and a diaphragm other than the lip portion in a valve-closed state. The backflow prevention device according to claim 2,
The backflow prevention device, wherein the thickness of the spacer is set to a dimension obtained by subtracting the allowable compression allowance of the lip portion from the protruding height of the lip portion. The backflow prevention device according to claim 1,
While the valve seat has a cross-sectional shape protruding to the diaphragm side, the diaphragm is formed as a flat surface at the portion that contacts the valve seat,
The backflow prevention device, wherein the spacer is configured to limit a compression allowance for compressing the diaphragm by biting in after the valve seat comes into contact with the diaphragm to a predetermined range. The backflow prevention device according to claim 4,
The backflow prevention device, wherein the thickness of the spacer is set to a dimension obtained by subtracting a permissible compression allowance of the diaphragm based on biting into the diaphragm of the valve seat from the protruding height of the valve seat from the stopper. The backflow prevention device according to any one of claims 1 to 5,
A spring for urging the diaphragm in the valve opening direction, and a spring receiving member assembled to the diaphragm to transmit the urging force from the spring to the diaphragm;
The said spacer is a backflow prevention apparatus comprised by a part of spring receiving member. The backflow prevention device according to any one of claims 1 to 6,
The diaphragm includes a flat plate-like valve portion opposed to the valve seat, and a folded portion that is continuous with the outer peripheral side of the valve portion and allows the displacement of the valve portion to contact and separate from the valve seat,
A backflow prevention device, wherein a tip is inserted into the folded portion and an inversion preventing wall is formed integrally with the housing to maintain the folded shape.

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