JP6195218B2 - Pressure reducing valve and electric water heater provided with the same - Google Patents

Description

  The present invention relates to a pressure reducing valve and an electric water heater provided with the same.

  The pressure reducing valve is required to make the water pressure in the secondary side flow path lower than the water pressure in the primary side flow path and maintain a constant water pressure. As a mechanism for maintaining the water pressure in the secondary side flow path constant, a mechanism having a diaphragm inside is known.

  For example, a pressure reducing valve described in Patent Document 1 below is controlled by a valve mechanism for adjusting the flow rate of water flowing from a primary side flow path to a secondary side flow path and the water pressure in the secondary side flow path. A diaphragm in which the part is displaced is provided inside. The valve mechanism has a valve body and a valve seat, and changes the flow rate of the passing water when the distance between the valve body and the valve seat changes. The valve body is connected to the diaphragm, and is configured such that the valve body moves in accordance with the displacement (deformation) of the diaphragm.

  For this reason, when a part of the diaphragm is displaced due to a change in the water pressure in the secondary side flow path, the valve body of the valve mechanism moves accordingly, and the water flowing into the secondary side flow path from the primary side flow path is moved. The flow rate changes. Specifically, when the water pressure in the secondary channel increases, the valve body moves so as to approach the valve seat with the displacement of the diaphragm, and the flow rate of water flowing into the secondary channel decreases. On the other hand, when the water pressure in the secondary side flow path becomes low, the valve body moves away from the valve seat with the displacement of the diaphragm, and the flow rate of water flowing into the secondary side flow path increases.

  As described above, the pressure reducing valve described in the following Patent Document 1 makes the water pressure in the secondary side flow path constant only by the mechanical movement of the diaphragm without using any electric driving force or control mechanism. The configuration can be maintained.

  Further, the pressure reducing valve described in Patent Document 1 further includes a protective cover that covers and protects the diaphragm from the outside. A space is formed between the protective cover and the diaphragm. The space functions as a space for storing water or the like so that the water does not flow out to the outside when the diaphragm breaks and water in the space communicating with the secondary-side channel leaks out. .

  In view of the function of preventing water from flowing out to the outside, such a space seems to be desirable to be a sealed space completely cut off from the external space. However, in the case of the sealed space, there may be a problem that the operation of the diaphragm is affected when the water pressure in the secondary side flow path is changed. For example, when the water pressure in the secondary channel increases, the central portion of the diaphragm is displaced toward the sealed space. However, since the atmospheric pressure in the sealed space increases with this, the displacement of the diaphragm is suppressed (compared to the case where the sealed space is not used). As a result, the water pressure in the secondary channel becomes too high.

  In order to prevent such a phenomenon, the pressure reducing valve described in Patent Document 1 described below forms a communication hole in a part of the protective cover, thereby allowing the internal space and the external space of the protective cover to communicate with each other. Yes. With such a configuration, the atmospheric pressure in the internal space of the protective cover is always kept substantially constant (atmospheric pressure).

  In the pressure reducing valve described in Patent Document 1 below, a seal member made of water-swollen rubber is further inserted into the communication hole. In normal times when the diaphragm is not damaged, the internal space of the protective cover and the external space are maintained in communication. On the other hand, when the diaphragm is damaged, the seal member swells (expands) by touching the water flowing out from the damaged portion, and seals the communication hole. For this reason, it is prevented that water continues to flow out from the communication hole.

Registered Utility Model No. 3060222

  As described above, the pressure reducing valve described in Patent Document 1 swells (expands) a water-swelling rubber seal member when the diaphragm is damaged and water leaks out, thereby sealing the communication hole. It is the composition which is done. However, a seal member made of water-swollen rubber requires a long time from when it touches water until it expands. Even if the diaphragm breaks and water starts to leak, the communication hole is not immediately sealed, and it takes more than 10 hours to seal, so water flows out of the communication hole until then. I will continue.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a pressure reducing valve capable of stopping the outflow of water to the outside in a short time when the diaphragm is damaged, and so on. Another object of the present invention is to provide an electric water heater equipped with a pressure reducing valve.

  In order to solve the above problems, the pressure reducing valve according to the present invention is a pressure reducing valve for lowering the water pressure of the secondary side flow path than the water pressure of the primary side flow path, and is connected to the primary side flow path. And a valve mechanism for adjusting a flow rate of water flowing from the first space into the second space, and a second space connected to the secondary flow path. A diaphragm that is partly displaced by receiving water pressure in the second space and moves the valve body of the valve mechanism; and a protective cover that covers and protects the diaphragm from the outside, A third space defined by the protective cover and the diaphragm is formed at a position adjacent to the second space across the diaphragm, and the protective cover includes the third space and the external space. A communication hole for communication is formed. The communication hole has a breathability, and characterized in that the expansion body formed by members which expand upon absorption of water is inserted.

  In the pressure reducing valve according to the present invention, a first space connected to the primary flow path and a second space connected to the secondary flow path are formed inside, and the first space to the second space are formed. A valve mechanism for adjusting the flow rate of water flowing into the water is provided. Further, a diaphragm is further provided.

  The diaphragm is partially displaced by receiving the water pressure in the second space, and is configured to move the valve body of the valve mechanism by the displacement. For this reason, it becomes possible to change the flow rate of the water passing through the valve mechanism in accordance with the water pressure in the second space, that is, the water pressure in the secondary side flow path, and keep the water pressure in the secondary side flow path substantially constant. ing.

  The pressure reducing valve according to the present invention further includes a protective cover that covers and protects the diaphragm from the outside. A part of the protective cover and the diaphragm are separated from each other, and a third space is defined by these parts. The third space is formed at a position adjacent to the second space across the diaphragm. For this reason, when the diaphragm is damaged and water leaks from the second space, the water flows into the third space. In other words, the third space functions as a space for receiving water leaked from the damaged portion of the diaphragm.

  The protective cover is formed with a communication hole that allows the third space and the external space to communicate with each other. For example, when the temperature of the pressure reducing valve rises and air filling the third space expands, the air is discharged from the communication hole to the external space. In this way, the atmospheric pressure inside the third space is always kept substantially constant (atmospheric pressure), so that the atmospheric pressure inside the third space does not fluctuate and affect the operation of the diaphragm. As a result, the water pressure in the secondary channel is always kept substantially constant.

  An expansion body is inserted into the communication hole. Since the expansion body is formed of a member having air permeability, the expansion body does not hinder the flow of air entering and exiting through the communication hole. Moreover, the expansion body is formed by a member that expands when it absorbs water. For this reason, when the diaphragm is damaged and water leaks from the second space to the third space, the expanding body expands by touching the water and seals the communication hole. For this reason, it is prevented that water continues to flow out from the communication hole.

  Moreover, since the expansion body is formed of a breathable member as described above, water not only touches the surface of the expansion body, but also immediately penetrates the entire interior of the expansion body. For this reason, when the diaphragm breaks and water leaks from the second space to the third space, the expansion body expands at a high speed by touching the water as well as the entire surface, including the inside, for a short time. The communication hole is sealed inside. Thus, in the pressure reducing valve according to the present invention, the outflow of water to the outside when the diaphragm is damaged can be stopped in a short time.

  In the pressure reducing valve according to the present invention, it is also preferable that a position restricting portion for restricting the displacement of the expansion body in the communication hole is formed.

  In this preferable aspect, a position restricting portion for restricting the displacement of the expanding body in the communication hole is formed. Since the positional displacement of the expansion body is restricted by the position restricting portion, for example, the expansion body does not expand in a state of being out of the communication hole. As a result, the outflow of water to the outside when the diaphragm is broken can be reliably stopped.

  In the pressure reducing valve according to the present invention, an elastic body that applies a force against the water pressure in the second space to the diaphragm is disposed in the third space. It is also preferable that an adjustment screw for adjusting the amount of expansion and contraction of the elastic body is inserted, and the expansion body is inserted around the adjustment screw.

  In this preferred embodiment, an elastic body that applies a force against the water pressure in the second space to the diaphragm is disposed inside the third space. An adjustment screw for adjusting the amount of expansion and contraction of the elastic body is inserted into the communication hole. By adjusting the expansion / contraction amount of the elastic body with the adjusting screw, the magnitude of the force applied from the elastic body to the diaphragm, that is, the force against the water pressure in the second space is changed, and the secondary side flow path The water pressure can be adjusted. The expansion body is inserted around the adjustment screw in the communication hole.

  It is possible to prevent water from flowing out from the periphery of the adjusting screw, while the water pressure in the secondary side channel can be adjusted from the outside by the adjusting screw.

  In the pressure reducing valve according to the present invention, it is also preferable that the expansion body is formed to have a ring shape that covers the periphery of the adjustment screw.

  In this preferred embodiment, the expansion body is formed in a ring shape that covers the periphery of the adjustment screw. Since the shape of the expansion body is a ring shape, the expansion body can be easily and reliably placed around the adjustment screw by simply inserting the adjustment screw into the communication hole after the expansion body is mounted around the adjustment screw. Can be inserted into.

  Moreover, the pressure reducing valve according to the present invention further includes a water droplet prevention cover that covers the communication hole from the outside, and the water droplet prevention cover prevents the droplet from being applied to the expansion body from the outside. In addition, it is preferable that air flow is allowed between the third space and the external space.

  In this preferable aspect, the water droplet prevention cover which covers a communicating hole from the outer side is further provided. The water droplet prevention cover is for preventing water droplets from being applied to the expansion body from the outside. For this reason, it is possible to prevent the expansion body from expanding and sealing the communication hole even though the diaphragm is not damaged.

  The water droplet prevention cover allows air to flow between the third space and the external space. For this reason, the communication hole is not blocked by the water droplet prevention cover, and the air pressure inside the third space does not fluctuate.

  In the pressure reducing valve according to the present invention, it is also preferable that the expanding body is a non-woven fabric formed of fibers that expand when water is absorbed.

  In this preferred embodiment, the expanded body is a nonwoven fabric formed by fibers that expand when water is absorbed. For this reason, when the diaphragm is damaged and water leaks from the second space to the third space, the water immediately penetrates into the entire inside of the expanded body, which is a nonwoven fabric. As a result, the expansion body expands at a higher speed and seals the communication hole in a short time. Thus, in this preferable aspect, the outflow of water to the outside when the diaphragm is broken can be stopped in a shorter time.

  Further, in the present invention, it is also preferable that the pressure reducing valve is any one of the above-described ones in a flow path for supplying water to the hot water storage tank.

  In this preferred embodiment, the pressure reducing valve is any one of the above-described ones in a flow path for supplying water to the hot water storage tank. Since the water pressure in the hot water storage tank is reduced by the pressure reducing valve, the pressure resistance performance of the hot water storage tank can be lowered. That is, the structure of the hot water storage tank can be simplified and the cost can be reduced.

  In addition, when the diaphragm of the pressure reducing valve is damaged, the outflow of water from the pressure reducing valve to the outside can be stopped in a short time.

  According to the present invention, it is possible to provide a pressure reducing valve capable of stopping the outflow of water to the outside when a diaphragm is damaged, and an electric water heater provided with such a pressure reducing valve. it can.

It is sectional drawing which showed the structure of the pressure-reduction valve which concerns on one Embodiment of this invention. It is the perspective view which showed the specific structure of the adjustment screw among the pressure-reduction valves shown in FIG. It is a figure for demonstrating the function of an expansion body. It is a figure which shows the structure of the electric water heater which equipped the pressure reducing valve shown in FIG. 1 inside.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  FIG. 1 is a sectional view showing the structure of a pressure reducing valve according to an embodiment of the present invention. As shown in FIG. 1, the pressure reducing valve PV includes a primary side connection port 10 in which an internal flow path 11 is formed as a flow path for receiving water from the upstream side, and an internal flow path as a flow path for supplying water to the downstream side. And a secondary side connection port 12 in which a path 13 is formed. For example, an upstream side pipe connected to a water pipe is connected to the primary side connection port 10, and high-pressure water is supplied to the internal flow path 11 from the upstream side pipe. A downstream pipe is connected to the secondary connection port 12, and the decompressed water is supplied from the internal flow path 13 to the downstream pipe.

  A first space R1 that communicates with the internal flow path 11 and a second space R2 that communicates with the internal flow path 13 are formed inside the pressure reducing valve PV, and the first space R1 and the second space R2 A valve mechanism 20 is disposed therebetween. The water that has flowed into the first space R1 from the internal flow path 11 passes through the valve mechanism 20 and flows into the second space R2, and is then supplied from the internal flow path 13 to the downstream inner pipe.

  In this embodiment, the backflow prevention mechanism 200 is built in between the internal flow path 11 and the first space R1, and water flows back from the first space R1 toward the internal flow path 11. Is prevented. For this reason, even if it is a case where water cutoff is performed and the water pressure in a water pipe falls, water does not flow backward toward a water pipe.

  The valve mechanism 20 has a valve seat 21 and a valve body 22, and water that has passed between the two flows into the second space R2. When the valve body 22 moves up and down in the pressure reducing valve PV and the distance between the valve seat 21 and the valve body 22 changes, the flow rate of water passing through the valve mechanism 20 changes accordingly. FIG. 1 shows a state in which the valve body 22 moves up most and is in contact with the valve seat 21. For this reason, in the state shown in FIG. 1, the inflow of water from the first space R1 to the second space R2 is completely stopped.

  The valve body 22 is a horizontally disposed disc, and a lower end of a shaft 23 disposed along the vertical direction is fastened and fixed at the center thereof. The shaft 23 can move up and down together with the valve body 22 along its central axis.

  The second space R2 communicates with the secondary pressure chamber 15 formed above via a connection channel 14 formed so as to extend upward. The upper side of the secondary pressure chamber 15 is covered with a circular diaphragm Dp arranged along a horizontal plane. In other words, the lower surface of the diaphragm Dp partitions the secondary pressure chamber 15 from above. The entire outer periphery of the diaphragm Dp is fixed and supported in a watertight manner with respect to the main body of the pressure reducing valve PV.

  On the lower surface of the diaphragm Dp, the water pressure in the secondary pressure chamber 15, that is, the water pressure in the second space R2, is applied as an upward force, and the diaphragm Dp is deformed by the water pressure. For this reason, the position of the center part of the diaphragm Dp moves up and down according to the water pressure in the second space R2.

  As shown in FIG. 1, a connecting pipe 26 that connects the secondary pressure chamber 15 and the first space R <b> 1 is disposed inside the pressure reducing valve PV. The shaft 23 is disposed so as to penetrate the inside of the connection pipe 26 vertically. A diameter-expanded portion 24 having a diameter larger than that of the other portion is formed in the central portion of the shaft 23 along the vertical direction, and the diameter-expanded portion 24 is disposed inside the cylindrical connection pipe 26. . An O-ring 25 is attached to the outer periphery of the enlarged diameter portion 24, and the O-ring 25 is in contact with the inner wall surface of the enlarged diameter portion 24. With such a configuration, the shaft 23 can move up and down while the secondary pressure chamber 15 and the first space R1 are water-tightly separated by the enlarged diameter portion 24.

  The upper end of the shaft 23 is fastened and fixed at the center of the diaphragm Dp. For this reason, when the position of the center part of the diaphragm Dp moves up and down according to the water pressure in the second space R2, the shaft 23 and the valve body 22 are also moved up and down accordingly. Therefore, when the water pressure in the second space R2 changes, the flow rate of water passing through the valve mechanism 20 changes.

  Specifically, when the water pressure in the second space R2 increases, the valve body 22 moves closer to the valve seat 21 as the central portion of the diaphragm Dp moves upward, and the first space R1 The flow rate of water flowing into the second space R2 decreases. As a result, the water pressure in the second space R2 decreases. On the other hand, when the water pressure in the second space R2 decreases, the valve body 22 moves away from the valve seat 21 as the central portion of the diaphragm Dp moves downward, and the second space R2 is moved from the first space R1. The flow rate of water flowing into is increased. As a result, the water pressure in the second space R2 increases.

  In this way, the pressure reducing valve PV can maintain the water pressure in the second space R2 constant only by the mechanical movement of the diaphragm Dp without using any electrical driving force or control mechanism. ing.

  A protective cover 40 is attached further above the diaphragm Dp. The protective cover 40 is for covering and protecting the diaphragm Dp from the outside. The protective cover 40 is formed in a substantially cylindrical shape as a whole, and has an inclined portion 41 formed so that its inner diameter becomes narrower toward the upper side, and a portion on the upper side of the inclined portion 41, the inner diameter of which is And a cylindrical portion 42 formed to be constant regardless of the height. Since the protective cover 40 has such a shape, a third space R3 partitioned by the protective cover 40 and the diaphragm Dp is formed. It can also be said that the third space R3 is formed at a position adjacent to the secondary pressure chamber 15 (a space communicating with the second space R2) across the diaphragm Dp. The lower end of the protective cover 40 is watertightly attached to the entire outer periphery of the diaphragm Dp.

  A substantially columnar adjusting screw 30 is disposed inside the cylindrical portion 42 of the protective cover 40. A female screw is formed on the inner surface side of the cylindrical portion 42, and a male screw is formed on the outer surface of the adjustment screw 30.

  In the third space R3, a spring Sp is disposed between the lower surface of the adjusting screw 30 and the upper surface of the diaphragm Dp. The upper surface of the diaphragm Dp is urged downward by the spring Sp. Therefore, a downward force due to the spring Sp and an upward force due to the pressure in the secondary pressure chamber 15 are applied to the center portion of the diaphragm Dp.

  A groove Gr is formed on the upper surface of the adjustment screw 30. By inserting the tip of a screwdriver or the like into the groove Gr and rotating the adjustment screw 30 along the horizontal plane, the position of the adjustment screw 30 can be changed up and down to adjust the amount of expansion and contraction of the spring Sp. That is, the magnitude of the force applied to the diaphragm Dp by the spring Sp can be changed.

  For example, when the adjustment screw 30 is moved upward, the magnitude of the force applied to the diaphragm Dp by the spring Sp becomes weaker. The central portion of the diaphragm Dp moves upward, and the valve body 22 also moves upward accordingly. Since the distance between the valve seat 21 and the valve body 22 is reduced and the amount of water passing through the valve mechanism 20 and flowing into the second space R2 is reduced, the water pressure in the second space R2 is reduced.

  Conversely, when the adjustment screw 30 is moved downward, the magnitude of the force applied to the diaphragm Dp by the spring Sp increases. The central portion of the diaphragm Dp moves downward, and the valve body 22 also moves downward accordingly. Since the distance between the valve seat 21 and the valve body 22 is increased and the amount of water flowing through the valve mechanism 20 and flowing into the second space R2 increases, the water pressure in the second space R2 increases.

  Thus, by rotating the adjustment screw 30 and changing its position, it is possible to adjust the water pressure in the second space R2 (water pressure after being reduced by the pressure reducing valve PV).

  By the way, when the diaphragm Dp is damaged due to deterioration or the like, water leaks from the secondary pressure chamber 15 through the damaged portion and flows into the third space. From the viewpoint of preventing such water from flowing out of the pressure reducing valve PV, it seems that the third space R3 is preferably a sealed space.

  However, when the third space R3 is a sealed space, the pressure inside the third space R3 varies depending on the temperature, which may affect the operation of the diaphragm Dp. For example, when the temperature of the pressure reducing valve PV main body rises, the atmospheric pressure in the third space R3 increases. Such a state is equal to a state in which the force by the spring Sp is increased. For this reason, the water pressure in the second space R2 is increased. On the contrary, when the temperature of the pressure reducing valve PV main body decreases, the water pressure in the second space R2 becomes low. Thus, the water pressure in the second space R2 varies with temperature.

  Therefore, in the present embodiment, the upper end of the cylindrical portion 42 is opened toward the external space, and the third space R3 is configured not to be a sealed space. In other words, the cylindrical portion 42 that opens toward the external space can be said to be a communication hole for communicating the third space R3 and the external space. The adjustment screw 30 is disposed inside the cylindrical portion 42 (inside the communication hole) as described above. However, since a gap is formed between the adjustment screw 30 and the inner surface of the cylindrical portion 42, the third space R3 is not sealed by the adjustment screw 30.

  A specific configuration of the adjusting screw 30 will be described with reference to FIG. FIG. 2 is a perspective view showing a specific configuration of the adjusting screw 30. As shown in FIG. 2, the adjusting screw 30 is formed in a substantially cylindrical shape, but a cut surface 31 is formed by cutting a part of the side surface along a direction parallel to the central axis. Yes. Since a large gap is formed between the inner surface of the cylindrical portion 42 and the cut surface 31, air flow between the third space R3 and the outer space is not hindered by the adjustment screw 30. .

  A cylindrical small diameter portion 32 is formed in the lower portion of the adjustment screw 30. The diameter of the small diameter portion 32 is slightly smaller than the diameter of the other portion of the adjustment screw 30. The central axis of the small diameter portion 32 is the same as the central axis of the other part of the adjustment screw 30.

  An expansion body Ep formed in a ring shape is attached to the small diameter portion 32 so as to cover the entire outer surface. The expansion body Ep is formed by forming a non-woven fabric formed of fibers made of a water-absorbing polymer into a ring shape having a rectangular cross section as shown in FIG. For this reason, the expansion body Ep has air permeability.

  The function of the expansion body Ep will be described with reference to FIG. FIG. 3A shows an enlarged portion near the adjustment screw 30 in the pressure reducing valve PV shown in FIG. As shown in FIG. 3A, the expansion body Ep is inserted in the gap between the outer side surface of the adjustment screw 30 and the inner side surface of the cylindrical portion 42. However, since the expansion body Ep has air permeability as described above, the expansion body Ep does not hinder the air flow between the third space R3 and the external space. In FIG. 3A, the flow of air when the water pressure in the second space R2 becomes high is indicated by arrows. At this time, the volume of the third space R3 decreases as the central portion of the diaphragm Dp moves upward, but the air in the third space R3 passes through the inside of the expansion body Ep, and the inside of the cylindrical portion 42 It passes between the side surface and the cut surface 31 and flows out to the external space of the protective cover 40. For this reason, the atmospheric pressure in the third space R3 does not rise.

  When the diaphragm Dp is damaged due to deterioration or the like, water leaks from the secondary pressure chamber 15 through the damaged portion and flows into the third space R3. As a result, the third space R3 is filled with water, and the water begins to flow out through the inside of the expansion body Ep. At this time, the fiber which forms the expansion body Ep will be in the state which the whole touched water. FIG. 3B shows an enlarged portion near the adjustment screw 30 in such a state.

  Since the fiber forming the expansion body Ep is a water-absorbing polymer, it expands (swells) when it comes into contact with water. The entire ring-shaped expansion body Ep expands, and as shown in FIG. 3B, the entire gap between the adjustment screw 30 and the cylindrical portion 42 is sealed.

  In this embodiment, since the expansion body Ep has air permeability, water not only touches the surface of the expansion body Ep but also immediately penetrates the entire interior of the expansion body Ep. For this reason, the expansion body Ep not only the surface but also the whole including the inside touches water and expands at a high speed, and seals the gap in a short time. Thus, in the pressure reducing valve PV according to the present embodiment, it is possible to stop the outflow of water to the outside when the diaphragm Dp is damaged in a short time.

  Further, in the pressure reducing valve PV according to the present embodiment, the expansion body Ep is sandwiched between the outer surface of the small diameter portion 32 and the inner surface of the cylindrical portion 42, and thereby the expansion body Ep in the cylindrical portion 42. Misalignment is regulated. For this reason, for example, the expansion body Ep does not expand in a state where it is detached from the cylindrical portion 42. As a result, it is possible to reliably stop the outflow of water when the diaphragm Dp is damaged.

  In addition, the expansion body Ep is formed to have a ring shape that covers the periphery of the small diameter portion 32 of the adjustment screw 30. Since the shape of the expansion body Ep is a ring shape, the expansion body Ep is first attached to the periphery of the small-diameter portion 32, and then the expansion body Ep is simply adjusted by inserting the adjustment screw 30 into the cylindrical portion 42. It can be easily and reliably inserted around 30.

  As shown in FIG. 3A and the like, the pressure reducing valve PV includes a water droplet prevention cover 50 that covers the upper end portion of the cylindrical portion 42 from the outside. The water droplet prevention cover 50 prevents the water droplets from being applied to the expansion body Ep from the outside. For this reason, it is prevented that the expansion body Ep expand | swells and the 3rd space R3 becomes a sealed space, although the diaphragm Dp is not damaged.

  As shown in FIG. 3A, a large gap is provided between the water droplet prevention cover 50 and the upper end portion of the cylindrical portion 42. In other words, the water droplet prevention cover 50 is configured to allow air to flow between the third space R3 and the external space. For this reason, the third space R3 does not become a sealed space by the water droplet prevention cover 50, and the air pressure inside the third space R3 does not fluctuate.

  Subsequently, an example in which the pressure reducing valve PV is disposed inside the electric water heater will be described with reference to FIG. FIG. 4 is a diagram illustrating a configuration of the electric water heater 100 including the pressure reducing valve PV therein. The electric water heater 100 is a so-called “first stop type” electric water heater, and includes a water supply pipe 101, a hot water storage tank 120, and a hot water supply pipe 102.

  The water supply pipe 101 is a pipe that receives supply of water from a water pipe (not shown). The water supplied from the water pipe flows into the hot water storage tank 120 from below through the water supply pipe 101 and is stored in the hot water storage tank 120. As shown in FIG. 4, the pressure reducing valve PV is arranged in the middle of the water supply pipe 101. For this reason, the water pressure on the downstream side (hot water storage tank 120 side) of the pressure reducing valve PV in the water supply pipe 101 is lower than the high water pressure in the water pipe. As a result, the water pressure inside the hot water storage tank 120 (equal to the second space R2) is also low.

  A heater 121 is disposed inside the hot water storage tank 120, and the water stored in the hot water storage tank 120 is heated by the heater 121. The amount of heating by the heater 121 is controlled by a control device (not shown), and the temperature of water (hot water) stored in the hot water storage tank 120 is maintained at a predetermined temperature.

  The hot water discharge pipe 102 is a pipe for supplying hot water stored in the hot water storage tank 120 to the outside. A first faucet (not shown) is attached to the downstream side of the tap water pipe 102. When the first tap is opened, the hot water flowing through the tap water pipe 102 is discharged from the first tap.

  Further, a water discharge pipe 110 is branched and connected to a portion of the water supply pipe 101 on the downstream side of the pressure reducing valve PV. A second faucet (not shown) is attached to the downstream side of the water outlet pipe 110. When the second faucet is opened, the water flowing through the water outlet pipe 110 is discharged from the second faucet.

  A drainage pipe 111 is branched and connected to a portion of the water supply pipe 101 downstream of the pressure reducing valve PV. The drainage pipe 111 is a pipe for discharging hot water stored in the hot water storage tank 120 during maintenance or the like. Under normal conditions, the drain pipe 111 is closed by a shut-off valve (not shown).

  An expansion water discharge pipe 130 is branched and connected in the middle of the hot water supply pipe 102. In addition, a relief valve EV is disposed in the expanded water discharge pipe 130. The relief valve EV is normally closed, but is configured to be opened when the water pressure in the hot water storage tank 120 rises above a predetermined pressure. Since such a relief valve EV is disposed, the hot water storage tank 120 will not be damaged even if the water pressure in the hot water storage tank 120 increases due to, for example, the expansion of water.

  As described above, the electric water heater 100 includes the pressure reducing valve PV in the water supply pipe 101 that supplies water to the hot water storage tank 120. Since the water pressure in the hot water storage tank 120 is reduced by the pressure reducing valve PV, the pressure resistance performance of the hot water storage tank 120 can be lowered. That is, the structure of the hot water storage tank 120 can be simplified and the cost can be reduced.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10: Primary side connection port 11: Internal flow path 12: Secondary side connection port 13: Internal flow path 14: Connection flow path 15: Secondary pressure chamber 20: Valve mechanism 21: Valve seat 22: Valve body 23: Shaft 24 : Expanded portion 25: Ring 26: Connection pipe 30: Adjustment screw 31: Cut surface 32: Small diameter portion 40: Protective cover 41: Inclined portion 42: Cylindrical portion 50: Water droplet prevention cover 100: Electric water heater 101: Water supply pipe 102 : Hot water piping 110: Hot water piping 120: Hot water storage tank 121: Heater 111: Drainage piping 130: Expansion water discharge piping 200: Backflow prevention mechanism Dp: Diaphragm Ep: Expansion body EV: Valve Gr: Groove PV: Pressure reducing valve R1: First Space R2: Second space R3: Third space Sp: Spring

Claims (6)

A pressure reducing valve for lowering the water pressure in the secondary side flow path than the water pressure in the primary side flow path,
A first space connected to the primary channel,
A second space connected to the secondary flow path is formed inside,
A valve mechanism for adjusting the flow rate of water flowing from the first space into the second space;
A diaphragm that is partially displaced by receiving water pressure in the second space and configured to move the valve body of the valve mechanism;
A protective cover that covers and protects the diaphragm from the outside,
A third space defined by the protective cover and the diaphragm is formed at a position adjacent to the second space across the diaphragm;
The protective cover is formed with a communication hole for communicating the third space and the external space,
In the communication hole, there is inserted an expansion body formed of a member having air permeability and expanding when absorbing water ,
A position restricting portion for restricting the displacement of the expansion body in the communication hole is formed,
The position restricting portion is composed of the protective cover and an adjustment screw provided in the protective cover,
The pressure-reducing valve according to claim 1, wherein the position of the expansion body is regulated while being in contact with the protective cover and the adjusting screw . Inside the third space, an elastic body that applies a force against the water pressure in the second space to the diaphragm is disposed,
An adjustment screw for adjusting the amount of expansion / contraction of the elastic body is inserted into the communication hole,
The pressure reducing valve according to claim 1 , wherein the expansion body is inserted around the adjustment screw. The pressure reducing valve according to claim 2 , wherein the expansion body is formed to have a ring shape that covers the periphery of the adjustment screw. A water droplet prevention cover that covers the communication hole from the outside;
The water droplet prevention cover is for preventing water droplets from being applied to the expansion body from the outside, and allows air to flow between the third space and the external space. The pressure reducing valve according to any one of claims 1 to 3 . The inflatable body, characterized in that water is a nonwoven fabric made of fibers which expands upon absorption of pressure reducing valve according to any one of claims 1 to 4. A first-stop electric water heater with a hot water storage tank,
An electric water heater comprising the pressure reducing valve according to any one of claims 1 to 5 disposed in a flow path for supplying water to the hot water storage tank.

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