Relief valve

Abstract

To properly reduce pressure rise of a fluid and to improve durability of a relief valve.SOLUTION: A relief valve 10 includes: a casing 1 provided with an inflow passage 11 of a fluid, a valve chest 13, a valve hole 12 for communicating the inflow passage 11 and the valve chest 13, and an outflow passage 14 communicated to the valve chest 13; a valve element 5 disposed in the valve chest 13 to open and close the valve hole 12; and an elastic body 7 for energizing the valve element 5 in a valve closing direction. The relief valve 10 further includes a throttle valve 8 disposed on the inflow passage 11 or the outflow passage 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed herein relates to a relief valve.

Background Art

[0002] Patent Document 1 discloses a relief valve incorporated between a high-pressure chamber and a low-pressure chamber. The relief valve has a valve hole that communicates the high-pressure chamber and the low-pressure chamber, a valve body provided on the low-pressure chamber side that opens and closes the valve hole, and a spring that biases the valve body in the valve-closing direction. When the pressure of the fluid in the high-pressure chamber is low, the valve body closes the valve hole by the biasing force of the spring. When the pressure of the fluid in the high-pressure chamber increases, the valve body is displaced in the valve-opening direction against the biasing force of the spring and opens the valve hole. As a result, the fluid in the high-pressure chamber flows out into the low-pressure chamber through the valve hole, and an increase in the pressure of the fluid in the high-pressure chamber is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above-described relief valve, the pressure of the fluid fluctuates due to factors such as pulsation of the fluid in the high-pressure chamber, and accordingly, the valve body may vibrate. When vibration of the valve body occurs, it becomes a problem in the durability of the relief valve, such as the valve body contacting surrounding objects such as a valve seat and the valve body and the surrounding objects deteriorating.

[0005] The technology disclosed herein has been made in view of such points, and the object thereof is to appropriately reduce the increase in the pressure of the fluid and improve the durability of the relief valve.

Means for Solving the Problems

[0006] The relief valve disclosed herein comprises a casing having a fluid inlet passage, a valve chamber, a valve hole connecting the inlet passage and the valve chamber, and an outlet passage communicating with the valve chamber; a valve body provided in the valve chamber for opening and closing the valve hole; and an elastic body for biasing the valve body in the closing direction, further comprising a throttle valve provided in the inlet passage or the outlet passage. [Effects of the Invention]

[0007] The relief valve can appropriately reduce the pressure rise of the fluid and improve the durability of the relief valve. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a longitudinal cross-sectional view of the relief valve. [Figure 2] Figure 2 is an enlarged cross-sectional view of the valve chamber portion of the relief valve. [Figure 3] Figure 3 is a cross-sectional view taken along the line III-III in Figure 2. [Figure 4] Figure 4 is an enlarged cross-sectional view of the valve chamber portion of the relief valve when it is open. [Figure 5] Figure 5 is an enlarged cross-sectional view of the inlet portion of the relief valve. [Figure 6] Figure 6 is a cross-sectional view along the line VI-VI in Figure 5. [Figure 7] Figure 7 is a cross-sectional view of a modified relief valve. [Modes for carrying out the invention]

[0009] The following describes exemplary embodiments with reference to the drawings. Figure 1 is a longitudinal cross-sectional view of the relief valve 10. The relief valve 10 is installed in a fluid system that controls the flow of fluid. The relief valve 10 automatically opens when the fluid pressure in the fluid system exceeds a set pressure, allowing the fluid to flow out. The relief valve 10 is installed, for example, in the hot water piping 9 of a hot water supply system.

[0010] The relief valve 10 comprises a casing 1 through which a fluid passage is formed, and a valve body 5 and an elastic body 7 housed within the casing 1. The passage includes a fluid inlet passage 11, a valve chamber 13, a valve hole 12 connecting the inlet passage 11 and the valve chamber 13, and an outlet passage 14 communicating with the valve chamber 13. The valve body 5 is provided in the valve chamber 13 and opens and closes the valve hole 12 from the valve chamber 13 side. The elastic body 7 is provided in the valve chamber 13 and biases the valve body 5 in the direction of closing the valve hole 12.

[0011] The casing 1 includes a cylindrical housing member 3 that penetrates axially with a virtual axis X as its center, a valve body receiver 2 attached to one end of the housing member 3 in the axial direction, and an elastic body receiver 4 attached to the other end of the housing member 3 in the axial direction. Hereinafter, the axial direction of the housing member 3, that is, the direction in which axis X extends, will simply be referred to as the "axial direction."

[0012] The housing member 3 houses the valve body 5 and the elastic body 7. The housing member 3 is made of a metal such as iron or stainless steel. A female thread 32 is formed on the inner circumferential surface of one axial end of the housing member 3, which connects to the valve body receiver 2. A female thread 33 is formed on the inner circumferential surface of the end of the housing member 3 opposite to the end on which the female thread 32 is formed, which connects to the elastic body receiver 4.

[0013] The valve body receiver 2 receives the valve body 5 housed in the housing member 3. The valve body receiver 2 is made of a metal such as iron or stainless steel. The valve body receiver 2 is formed in a cylindrical shape that penetrates axially. A male thread 23 is formed on the outer circumferential surface of one axial end of the valve body receiver 2. The male thread 23 is screwed into the female thread 32 of the housing member 3. A male thread 22 is formed on the outer circumferential surface of the end of the valve body receiver 2 opposite to the housing member 3 side. The male thread 22 is connected to primary side piping such as hot water piping 9.

[0014] On the side of the receiving member 3 of the valve body receiver 2, a recess 27 is formed. The recess 27 is a bottomed hole coaxial with the receiving member 3. At the bottom of the recess 27, a valve seat 25 on which the valve body 5 seats and disengages is formed. The valve seat 25 is an annular valve seat, and a valve hole 12 is formed on its inner peripheral side. The valve hole 12 is opened and closed when the valve body 5 seats and disengages from the valve seat 25. The valve hole 12 is a hole coaxial with the recess 27. The axial direction of the valve hole 12 coincides with the axial direction.

[0015] An inflow passage 11 is further formed in the valve body receiver 2. The inflow passage 11 extends from the end on the side opposite to the receiving member 3 side of the valve body receiver 2 toward the receiving member 3 side. The inflow passage 11 is a hole coaxial with the valve hole 12. The receiving member 3 side of the inflow passage 11 communicates with the valve hole 12.

[0016] The elastic body receiver 4 is attached to the side of the receiving member 3 opposite to the valve body receiver 2 and receives the elastic body 7 housed in the receiving member 3. The elastic body receiver 4 is made of, for example, a metal such as iron or stainless steel. The elastic body receiver 4 is formed in a cylindrical shape penetrating in the axial direction. On the outer peripheral surface of one end portion in the axial direction of the elastic body receiver 4, a male screw 41 that engages with the female screw 33 of the receiving member 3 is formed. The male screw 41 is screwed into the female screw 33 of the receiving member 3 so that the screwing depth can be changed. Thereby, the elastic body receiver 4 can be attached to the receiving member 3 so as to be axially displaceable.

[0017] On the side of the receiving member 3 of the elastic body receiver 4, a recess 49 is formed. The bottom of the recess 49 forms a support portion 44 that supports the elastic body 7.

[0018] An outflow passage 14 is further formed in the elastic body receiver 4. The outflow passage 14 is a hole coaxial with the recess 49 that extends from the end on the side opposite to the receiving member 3 side of the elastic body receiver 4 toward the receiving member 3 side. On the receiving member 3 side of the outflow passage 14, a communication hole 45 that has a smaller flow path cross-sectional area than the outflow passage 14 and penetrates in the axial direction is formed. The outflow passage 14 communicates with the recess 49 through the communication hole 45. On the inner peripheral surface of the outflow passage 14, a female screw 43 connected to the secondary side piping is formed.

[0019] The valve chamber 13 is partitioned by the recess 27, the housing member 3, and the recess 49. That is, around the axis X of the valve chamber 13, it is formed by the inner peripheral surface 27a of the recess 27, the inner peripheral surface of the housing member 3, and the inner peripheral surface of the recess 49. The inner peripheral surface 27a of the recess 27 is an example of the inner peripheral surface of the valve chamber 13. The valve body 5 and the elastic body 7 are accommodated in the valve chamber 13 in an axially aligned state.

[0020] FIG. 2 is an enlarged cross-sectional view of the valve chamber 13 portion of the relief valve 10. The valve body 5 faces the valve seat 25. In the valve chamber 13, the valve body 5 is displaced axially to separate from and seat on the valve seat 25. The valve body 5 has a base 51 biased by the elastic body 7, and an annular seal member 52 attached to the base 51 and pressed against the valve seat 25 when the valve is closed.

[0021] The base 51 is made of a metal such as iron or stainless steel, for example. An annular groove 58 and a recess 61 located inside the annular groove 58 are formed on the surface of the base 51 on the valve seat 25 side.

[0022] The seal member 52 is fitted into the annular groove 58. The seal member 52 is formed in an annular shape surrounding the valve hole 12 and is arranged to face the valve seat 25. The seal member 52 is formed of a material having a higher elastic modulus than the base 51. Specifically, the seal member 52 is formed of a resin. More specifically, the seal member 52 is formed of a fluororesin.

[0023] A retaining portion 62 bent toward the outer peripheral side is formed at the end of the peripheral wall portion of the recess

[61] on the valve seat 25 side. The retaining portion 62 prevents the seal member 52 from falling out of the annular groove <58>. The retaining portion 62 is formed, for example, by inserting a jig into the recess 61 and caulking the peripheral wall portion of the recess 61 with the jig.

[0024] The displacement direction of the valve body 5 is restricted axially by the inner peripheral surface of the valve chamber 13. Specifically, the displacement direction of the valve body 5 is restricted by guiding the outer peripheral surface 53 around the axis X of the base 51 along the inner peripheral surface 27a of the recess 27.

[0025] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. As shown in Figure 3, the cross-sectional shape of the base 51 of the valve body 5 perpendicular to the axial direction is different from the cross-sectional shape of the recess 27 of the valve body receiver 2 perpendicular to the axial direction. Specifically, the cross-sectional shape of the base 51 is approximately rectangular, and the cross-sectional shape of the recess 27 is circular. Each corner of the base 51, which has an approximately rectangular cross-section, forms an arc-shaped contact surface 54. Therefore, when the valve body 5 is displaced in the axial direction, the contact surface 54 slides along the inner circumferential surface 27a of the recess 27.

[0026] The portion of the outer circumferential surface 53 of the base 51 other than the contact surface 54 constitutes a non-contact surface 55 that is spaced apart from the inner circumferential surface 27a of the recess 27. A connecting passage 56 is formed between the non-contact surface 55 and the inner circumferential surface 27a of the recess 27, penetrating in the axial direction. The connecting passage 56 is an example of a second connecting passage. The connecting passage 56 communicates with the outflow passage 14.

[0027] As shown in Figure 1, the elastic body 7 is positioned between the valve body 5 and the elastic body receiver 4 in a compressed state in the axial direction. The elastic body 7 is a coil spring. One axial end of the elastic body 7 is housed in a recess 59 formed on the elastic body receiver 4 side of the valve body 5. The other axial end of the elastic body 7 (the end opposite to the valve body 5 side) is housed in a recess 49 of the elastic body receiver 4 and supported by a support portion 44. The elastic body 7 biases the base 51 (Figure 2) of the valve body 5 toward the valve seat 25 along the axial direction.

[0028] The inlet passage 11 receives, for example, hot water from the hot water pipe 9 as a fluid. When the fluid pressure in the inlet passage 11 is low, the valve body 5 is biased by the elastic body 7 and seats on the valve seat 25 as shown in Figure 2, closing the valve hole 12. Specifically, the sealing member 52 is pressed against the valve seat 25, and the space between the base 51 and the valve seat 25 is sealed by the sealing member 52.

[0029] Figure 4 is a cross-sectional view showing the valve body 5 when the valve is open. When the fluid pressure in the inlet passage 11 increases, the valve body 5 displaces against the biasing force of the elastic body 7 to the side opposite to the valve seat 25, as shown in Figure 4, and separates from the valve seat 25. At this time, due to the pressure of the fluid flowing into the recess 61 of the valve body 5, the contact surface 54 (Figure 3) of the valve body 5 slides axially along the inner circumferential surface 27a of the recess 27 of the valve body receiver 2. As the valve body 5 separates, a gap is formed between the seal member 52 and the valve seat 25, and the valve hole 12 is opened.

[0030] As described above, when the valve body 5 is open, the fluid in the hot water piping 9 flows into the valve chamber 13 via the inlet passage 11 and the valve hole 12. The fluid that flows into the valve chamber 13 passes through the gap between the seal member 52 and the valve seat 25 (Figure 4) and flows into the outlet passage 14 via the valve chamber 13. The fluid that flows into the outlet passage 14 flows out into the secondary piping connected to the elastic receiver 4. In this way, the fluid in the hot water piping 9 flows out through the relief valve 10, which allows the maximum fluid pressure of the fluid system connected to the primary side of the relief valve 10 to be kept constant. Note that the secondary piping does not necessarily have to be connected to the elastic receiver 4. In this case, the fluid is discharged directly into the atmosphere from the outlet passage 14.

[0031] The lift of the valve body 5, that is, the axial distance from the sealing member 52 to the valve seat 25 of the valve body 5 when the valve is open, varies according to the pressure of the fluid in the inlet passage 11. When the pressure of the fluid in the inlet passage 11 is low, the lift of the valve body 5 is small, so the flow rate of fluid flowing out through the relief valve 10 is small. On the other hand, when the pressure of the fluid in the inlet passage 11 is high, the lift of the valve body 5 is large, so the flow rate of fluid flowing out through the relief valve 10 is large. Therefore, in the relief valve 10, the flow rate of fluid flowing out through the relief valve 10 changes according to the pressure of the fluid in the fluid system, and the maximum pressure of the fluid in the fluid system can be kept constant.

[0032] When the fluid pressure in the hot water piping 9 decreases and the fluid pressure in the inlet passage 11 also decreases, the valve body 5 is displaced toward the valve seat 25 by the biasing force of the elastic body 7, as shown in Figures 1 and 2, and seats on the valve seat 25. At this time, the direction in which the valve body 5 is displaced is the valve closing direction. Even when the valve body 5 is displaced in the valve closing direction, the contact surface 54 of the valve body 5 slides axially along the inner circumferential surface 27a of the recess 27. As the valve body 5 seats on the valve seat 25, the inlet passage 11 and the valve chamber 13 are no longer in communication (non-communication state).

[0033] The set pressure of the relief valve 10, that is, the fluid pressure at which the valve body 5 begins to open, changes according to the biasing force exerted by the elastic body 7 on the valve seat 25. The biasing force of the elastic body 7 changes according to the axial mounting position of the elastic body receiver 4 relative to the housing member 3. Specifically, the axial position of the elastic body receiver 4 changes according to the screwing depth of the elastic body receiver 4 relative to the housing member 3, that is, the screwing depth of the male thread 41 relative to the female thread 33.

[0034] As the screw-in depth of the elastic body support 4 increases, the axial distance from the support portion 44 to the valve body 5 decreases, and the amount of compression of the elastic body 7, which is compressed axially by the elastic body support 4, increases. As a result, the biasing force that the elastic body 7 exerts on the valve body 5 increases, and the set pressure increases. On the other hand, as the screw-in depth of the elastic body support 4 decreases, the amount of axial compression of the elastic body 7 decreases. As a result, the biasing force that the elastic body 7 exerts on the valve body 5 decreases, and the set pressure decreases.

[0035] The elastic support 4 has the function of contacting the valve body 5 and restricting the maximum lift of the valve body 5. Specifically, the elastic support 4 has a cylindrical stopper 48 at the end on the side of the housing member 3. The stopper 48 forms the peripheral wall portion of the recess 49.

[0036] The stopper 48 faces the base 51 of the valve body 5 in the axial direction. When the valve body 5 is displaced significantly in the direction away from the valve seat 25, i.e., in the valve opening direction, the base 51 comes into contact with the stopper 48. As a result, the base 51 cannot be displaced any further in the valve opening direction, and the maximum lift of the valve body 5 is restricted.

[0037] The stopper 48 has a plurality of notches 47 formed at intervals in the circumferential direction of the elastic body receiver 4. The notches 47 open towards the valve body 5 and penetrate radially through the elastic body receiver 4. When the valve body 5 contacts the stopper 48, the notches 47 are adjacent to and communicate with the communication passage 56. Therefore, when the maximum lift of the valve body 5 is restricted by the stopper 48, the fluid flowing from the valve hole 12 into the communication passage 56 can flow into the recess 49 through the notches 47 and out to the outlet passage 14.

[0038] The axial position of the stopper 48 changes depending on the axial mounting position of the elastic body receiver 4 with respect to the housing member 3. Specifically, increasing the screwing depth of the elastic body receiver 4 into the female thread 33 brings the stopper 48 closer to the valve seat 25 in the axial direction. As a result, the maximum lift of the valve body 5 decreases. On the other hand, decreasing the screwing depth of the elastic body receiver 4 moves the stopper 48 further away from the valve seat 25 in the axial direction. As a result, the maximum lift of the valve body 5 increases.

[0039] Figure 5 is a cross-sectional view of the inlet passage 11 portion of the valve body receiver 2 that constitutes the relief valve 10. A throttle valve 8 is provided inside the inlet passage 11. The inlet passage 11 and the throttle valve 8 will be described in detail below.

[0040] An internal thread 17 is formed on the inner circumferential surface of the inlet passage 11, to which the throttle valve 8 is attached. In other words, the inlet passage 11 is a threaded hole.

[0041] The throttle valve 8 changes the flow rate of the fluid flowing through the valve hole 12. The throttle valve 8 is made of metal, such as iron or stainless steel. The throttle valve 8 has an axially extended shape. The throttle valve 8 has a base portion 81 that is attached to the female screw 17 and a valve portion 82 that changes the opening degree of the valve hole 12.

[0042] Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 5. Note that in Figure 6, the illustration of the female thread 17 is omitted in order to clearly show the shape of the throttle valve 8. The base 81 of the throttle valve 8 has an axially extended shape, and the cross-sectional shape of the base 81 perpendicular to the axial direction is non-circular (a shape with a cut-out circle). Specifically, the cross-sectional shape of the base 81 is composed of two opposing circular arcs and two parallel line segments connecting the ends of these two circular arcs, respectively. The male thread 84 is formed on the arc-shaped portion (arc surface) of the outer circumferential surface of the base 81.

[0043] The male thread 84 of the base 81 is screwed into the female thread 17 in a manner that allows for adjustment of the screwing depth. The direction of screwing the base 81 into the female thread 17 coincides with the axial direction. The position of the throttle valve 8 in the axial direction changes according to the screwing depth of the base 81 into the female thread 17.

[0044] A fitting groove 88 is formed at the end of the base portion 81 opposite to the valve portion 82. A tool such as a screwdriver for rotating the throttle valve 8 can be fitted into the fitting groove 88.

[0045] A spaced portion 85 is formed on the outer circumferential surface of the base portion 81, excluding the arcuate surface. The spaced portion 85 is the portion spaced apart from the female thread 17 of the valve body receiver 2 (i.e., the inner circumferential surface of the inflow passage 11). A connecting passage 86 is formed between the spaced portion 85 and the female thread 17, penetrating in the axial direction. The connecting passage 86 is an example of a first connecting passage. The connecting passage 86 communicates with the valve hole 12.

[0046] As shown in Figure 5, the valve portion 82 has a shape that protrudes from the base portion 81 toward the valve hole 12. The valve portion 82 is formed in a substantially cylindrical shape that extends in the axial direction. An annular tapered surface 87 is formed on the periphery of the end portion 82 toward the valve hole 12. Due to the tapered surface 87, the diameter of the valve portion 82 gradually decreases toward the end face 89.

[0047] The fluid that flows into the inlet passage 11 passes through the communication passage 86. When the valve body 5 is open, the fluid flows out into the valve chamber 13 by passing between the tapered surface 87 and the valve hole 12.

[0048] To change the flow rate of the fluid flowing through the valve hole 12, the user can, for example, fit a tool into the fitting groove 88 and rotate the throttle valve 8 around axis X using the tool to change the screw depth of the throttle valve 8 relative to the female thread 17. When the screw depth of the throttle valve 8 increases, the distance between the tapered surface 87 and the end 12a of the valve hole 12 decreases, and the opening of the valve hole 12 decreases. As a result, the flow rate passing through the valve hole 12 when the valve body 5 is open decreases. On the other hand, when the screw depth of the throttle valve 8 decreases, the distance between the tapered surface 87 and the end 12a of the valve hole 12 increases, and the opening of the valve hole 12 increases. As a result, the flow rate of the fluid passing through the valve hole 12 when the valve body 5 is open increases. Note that when the distance between the tapered surface 87 and the end 12a of the valve hole 12 exceeds a predetermined distance, the fluid flow rate does not increase and remains constant.

[0049] The relief valve 10 having the above configuration allows for adjustment of the fluid flow rate through the relief valve 10 by operating the throttle valve 8 to change the fluid flow rate passing through the valve hole 12. Therefore, the fluid flow rate through the relief valve 10 can be set to an appropriate value according to the equipment such as a hot water supply system, thereby achieving both protection of the equipment from fluid pressure rise and improved durability of the relief valve 10.

[0050] In other words, in order to properly protect equipment such as hot water heaters from pressure increases in the fluid, it is necessary to ensure a sufficient flow rate of fluid through the relief valve 10 when it is open. This flow rate varies depending on the equipment, for example, depending on the performance of the hot water heater and the pressure of the water supplied to the hot water heater. On the other hand, in order to reduce the vibration of the valve body 5 when fluid pressure fluctuations occur due to fluid pulsation in the equipment, it is necessary to reduce the flow rate of fluid that can flow through the relief valve 10 and reduce fluctuations in the fluid flow rate in the relief valve 10. In the relief valve 10 disclosed in this application, the flow rate of the fluid can be adjusted so that an appropriate amount of fluid flows out of the relief valve 10 when the fluid pressure in the equipment increases, and so that the amount of fluid flowing through the relief valve 10 decreases when the fluid pulsates. By adjusting the flow rate of the fluid flowing through the relief valve 10 in this way, when the fluid pressure in the equipment increases, the maximum fluid pressure in the equipment can be kept constant while ensuring a sufficient amount of fluid is released, thereby protecting the equipment. In addition, when fluid pulsation causes pressure fluctuations in the equipment, the relief valve 10 prevents all the fluid flowing into it from directly acting on the valve body 5, thereby reducing vibration of the valve body 5. As a result, it is possible to prevent the valve body 5 from vibrating and coming into contact with surrounding objects such as the valve seat 25, thereby reducing deterioration and damage to the valve body 5 and surrounding objects.

[0051] In addition, by forming an axially penetrating passage 86 between the separated portion 85 of the throttle valve 8 and the female thread 17, the throttle valve 8 can be installed in the casing 1 using the female thread 17. Furthermore, if a male thread 22 is formed on the outer circumference of the valve body receiver 2, the female thread 17 can be formed on the inner circumference of the valve body receiver 2 at a position that overlaps with the male thread 22 in the same axial direction. Therefore, the axial increase in the size of the casing 1 caused by providing the female thread 17 can be avoided.

[0052] Furthermore, by forming a communication passage 56 between the outer circumferential surface 53 of the valve body 5 and the inner circumferential surface of the valve chamber 13, the displacement direction of the valve body 5 can be restricted by utilizing the inner circumferential surface of the valve chamber 13.

[0053] Furthermore, by making the valve body receiver 2, which has the valve seat 25, and the housing member 3, which houses the valve body 5 and elastic body 7, separate components, the valve body receiver 2 can be machined with the housing member 3 removed from the valve body receiver 2. Therefore, the housing member 3 does not get in the way during machining of the valve body receiver 2, making machining of the valve body receiver 2 easier. In particular, when the housing member 3 is attached to the valve body receiver 2, it is difficult to machine the valve seat 25 with high precision because it is surrounded by the housing member 3, but by removing the housing member 3 from the valve body receiver 2, it can be machined with high precision. Therefore, the airtightness when the valve body 5 closes the valve seat 25 can be improved. In addition, when inspecting the valve seat 25 after machining, the housing member 3 does not get in the way, making inspection easier.

[0054] Furthermore, by changing the axial mounting position of the elastic body support 4 with respect to the housing member 3, the position in which the elastic body support 4 supports the elastic body 7 can be changed, thereby changing the amount of axial compression of the elastic body 7. In other words, by changing the mounting position of the elastic body support 4, the biasing force with which the elastic body 7 biases the valve body 5 can be changed, and the set pressure of the relief valve 10 can be changed. Therefore, the set pressure of the relief valve 10 can be appropriately adjusted according to the fluid pressure, which differs for each piece of equipment, and the equipment can be appropriately protected from increases in fluid pressure. In particular, when the set pressure of the relief valve 10 is lowered, the valve body 5 is more susceptible to displacement by the fluid, but even in this case, vibration of the valve body 5 can be reduced by appropriately setting the flow rate of the fluid flowing through the relief valve 10 using the throttle valve 8.

[0055] Furthermore, the elastic support 4 contacts the valve body 5 and restricts the maximum lift of the valve body 5. Therefore, the maximum lift of the valve body 5 can be adjusted by changing the axial mounting position of the elastic support 4 with respect to the housing member 3. Thus, the maximum flow rate of the fluid flowing through the relief valve 10 when the valve is open can be appropriately set according to the equipment, etc.

[0056] Figure 7 is a longitudinal cross-sectional view of a modified relief valve 10A. This relief valve 10A differs from the relief valve 10 in that the throttle valve 8A is located in the outflow passage 14 instead of the inflow passage 11. The following explanation will focus on the differences between the relief valve 10A and the relief valve 10A.

[0057] The throttle valve 8A changes the flow rate of the fluid flowing through the communication hole 45 of the elastic body receiver 4. Although not shown in the figure, the cross-sectional shape of the base 81A of the throttle valve 8A perpendicular to the axial direction is non-circular (a shape with a cut-out circle), similar to the cross-sectional shape of the base 81A perpendicular to the axial direction shown in Figure 6. A male thread is formed on the outer circumferential surface of the base 81A. The male thread is screwed into the female thread 43 of the outflow passage 14 so that the screwing depth can be changed. A communication passage 86A is formed between the outer circumferential surface of the base 81A and the inner circumferential surface of the female thread 43, penetrating in the axial direction. The communication passage 86A is an example of a first communication passage. The communication passage 86A communicates with the communication hole 45.

[0058] The valve portion 82A has a shape that protrudes from the base portion 81A toward the communication hole 45. An annular tapered surface 87A is formed on the periphery of the end portion 82A toward the communication hole 45. Due to the tapered surface 87A, the diameter of the valve portion 82A gradually decreases toward the end face 89A.

[0059] When the valve body 5 is open, the fluid that flows into the valve chamber 13 from the valve hole 12 passes between the tapered surface 87A and the communication hole 45, and flows out through the communication passage 86A to the outlet passage 14.

[0060] To change the flow rate of the fluid flowing through the communication hole 45, the user fits a tool into the fitting groove 88A of the base 81A and rotates the throttle valve 8A around axis X using the tool to change the screwing depth of the throttle valve 8A into the female thread 43. When the screwing depth of the throttle valve 8A increases, the distance between the tapered surface 87A and the end 45a of the communication hole 45 decreases, and the opening of the communication hole 45 decreases. As a result, the flow rate passing through the communication hole 45 when the valve body 5 is open decreases, and consequently, the flow rate of the fluid passing through the valve hole 12 also decreases. On the other hand, when the screwing depth of the throttle valve 8A decreases, the distance between the tapered surface 87A and the end 45a of the communication hole 45 increases, and the opening of the communication hole 45 increases. As a result, the flow rate of the fluid passing through the communication hole 45 when the valve body 5 is open increases, and the flow rate of the fluid passing through the valve hole 12 also increases. Furthermore, when the distance between the tapered surface 87A and the end portion 45a of the communication hole 45 exceeds a predetermined distance, the fluid flow rate does not increase and remains constant.

[0061] As described above, the relief valves 10, 10A relating to the first aspect of the technology of this disclosure are relief valves comprising a casing 1 having a fluid inlet passage 11, a valve chamber 13, a valve hole 12 connecting the inlet passage 11 and the valve chamber 13, and an outlet passage 14 communicating with the valve chamber 13, a valve body 5 provided in the valve chamber 13 for opening and closing the valve hole 12, and an elastic body 7 for biasing the valve body 5 in the closing direction, and further comprising throttle valves 8, 8A provided in the inlet passage 11 or the outlet passage 14.

[0062] With this configuration, the flow rate of fluid flowing through the relief valves 10 and 10A can be adjusted by operating the throttle valves 8 and 8A to change the flow rate of fluid passing through the valve hole 12. Therefore, the flow rate of fluid flowing through the relief valves 10 and 10A can be set to an appropriate value depending on the equipment, thereby achieving both protection of the equipment from fluid pressure rise and improved durability of the relief valves 10 and 10A.

[0063] Furthermore, in the relief valve 10 of the second aspect of the technology of this disclosure, in the relief valve 10 of the first aspect, the throttle valve 8 is provided inside the inlet passage 11, an internal thread 17 is formed in the inlet passage 11, the throttle valve 8 is screwed into the internal thread 17 so as to be able to change the screwing depth, the opening of the valve hole 12 is changed according to the screwing depth, and a communication passage 86 (first communication passage) is formed between the outer circumferential surface of the throttle valve 8 and the internal thread 17, penetrating in the screwing direction of the throttle valve 8.

[0064] With this configuration, the throttle valve 8 can be installed inside the casing 1 using the female thread 17.

[0065] Furthermore, in the relief valves 10, 10A of the third aspect of the technology of this disclosure, in the relief valves 10, 10A of the first or second aspect, the valve body 5 opens and closes the valve hole 12 by sliding its outer peripheral surface along the inner peripheral surface of the valve chamber 13 in the axial direction of the valve hole 12, and a communication passage 56 (second communication passage) is formed between the outer peripheral surface 53 of the valve body 5 and the inner peripheral surface of the valve chamber 13, penetrating in the axial direction of the valve hole 12 and communicating with the outflow passage 14.

[0066] With this configuration, the inner circumferential surface of the valve chamber 13 can be used to restrict the displacement direction of the valve body 5 to the axial direction of the valve hole 12.

[0067] Furthermore, in the relief valves 10, 10A of the fourth aspect of the technology of this disclosure, in any one of the relief valves 10, 10A of the first to third aspects, the casing 1 has a cylindrical housing member 3 that houses a valve body 5 and an elastic body 7, and a valve body receiver 2 attached to one end of the housing member 3 in the axial direction, which has a valve seat 25 on which the valve body 5 sits and unseats, and a valve hole 12 that is opened and closed by the valve body 5 sitting and unseats on the valve seat 25.

[0068] In this configuration, the valve body receiver 2 having the valve seat 25 and the housing member 3 that houses the valve body 5 and elastic body 7 are separate components. Therefore, the valve body receiver 2 can be machined with the housing member 3 removed from the valve body receiver 2. As a result, the valve body receiver 2 does not get in the way during machining, making it easier to machine the valve body receiver 2. In particular, the surface of the valve seat 25 on which the valve body 5 sits is surrounded by the housing member 3 when the housing member 3 is attached to the valve body receiver 2, making it difficult to machine with high precision. However, by removing the housing member 3 from the valve body receiver 2, it can be machined with high precision. As a result, the airtightness when the valve body 5 closes the valve seat 25 can be improved.

[0069] Furthermore, in the relief valves 10, 10A of the fifth aspect of the technology of this disclosure, in the relief valves 10, 10A of the fourth aspect, the valve body 5 seats to and from the valve seat 25 by being displaced in the axial direction of the housing member 3, the elastic body 7 biases the valve body 5 in the axial direction of the housing member 3, and the casing 1 further has an elastic body receiver 4 attached to the opposite side of the housing member 3 from the valve body receiver 2 side to support the elastic body 7, the elastic body receiver 4 is attached to the housing member 3 so as to be displaceable in the axial direction of the housing member 3.

[0070] With this configuration, by displacing the mounting position of the elastic body receiver 4 with respect to the housing member 3 in the axial direction of the housing member 3, and changing the position in which the elastic body receiver 4 supports the elastic body 7, the biasing force with which the elastic body 7 biases the valve body 5 can be changed, and the set pressure of the relief valves 10 and 10A can be changed. Therefore, the set pressure of the relief valves 10 and 10A can be appropriately adjusted according to the fluid pressure which differs for each piece of equipment, and the equipment can be adequately protected from fluid pressure increases.

[0071] Other embodiments As described above, the embodiments described herein have been presented as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments above to create new embodiments. In addition, the components described in the attached drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology. Therefore, the mere presence of such non-essential components in the attached drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential.

[0072] For example, relief valves 10 and 10A may be installed in devices other than hot water supply equipment, such as water supply systems, pressure vessels, or boilers. The target fluid for relief valves 10 and 10A is not limited to water, but may be other liquids or gases. The mounting target for relief valves 10 and 10A is not limited to piping, but may also be tanks, etc.

[0073] The number of members forming the casing 1 is not limited to three. The casing 1 may be formed from only one, only two, or four or more members. For example, the casing 1 may be formed from two members: a member in which the valve body receiver 2 and the housing member 3 are integrally formed, and an elastic body receiver 4. The materials and shapes of the valve body receiver 2, the housing member 3, and the elastic body receiver 4 are not limited.

[0074] The valve body 5 is formed from two components, a base 51 and a sealing member 52, but it may also be formed from a single component. For example, the valve body 5 may be formed solely from a metal component such as iron or stainless steel. The materials of the base 51 and the sealing member 52 are not limited. For example, the base 51 may be formed from a metal other than iron or stainless steel, or from a material other than metal. The sealing member 52 may be formed from a resin other than fluororesin, or from a metal such as iron or stainless steel.

[0075] The elastic body 7 is not limited to a coil spring. The elastic body 7 may be a spring other than a coil spring, or it may be rubber.

[0076] The material, shape, and size of the throttle valves 8 and 8A are not limited. The throttle valves 8 and 8A are not limited to those mounted on the female threads 17 and 43, as long as they can adjust the flow rate of the fluid flowing through the valve bore 12. [Explanation of symbols]

[0077] 10,10A Relief Valve 1 Casing 11 Inflow channel 12 valve holes 13 valve chambers 14 Outflow channel 17 Female thread 2 Valve body receiver 25 valve seats 3. Housing Member 4 Elastic support 5 Valve body 56th Concourse (Second Concourse) 7 Elastic body 8,8A throttle valve 86th Concourse (First Concourse)

Claims

1. A casing having a fluid inlet passage, a valve chamber, a valve opening connecting the inlet passage and the valve chamber, and an outlet passage communicating with the valve chamber, A valve body provided in the valve chamber for opening and closing the valve hole, A relief valve comprising an elastic body that biases the valve body in the closing direction, The inlet passage is further equipped with a throttle valve, The inlet passage has a female thread formed therein. The throttle valve is screwed into the female thread so as to be able to change the screwing depth, and the opening of the valve hole is changed according to the screwing depth. A relief valve having a first connecting passage formed between the outer circumferential surface of the throttle valve and the female thread, which penetrates in the screwing direction of the throttle valve.

2. In the relief valve according to claim 1, The valve body opens and closes the valve hole by sliding its outer circumferential surface along the inner circumferential surface of the valve chamber in the axial direction of the valve hole. A relief valve having a second communication passage formed between the outer circumferential surface of the valve body and the inner circumferential surface of the valve chamber, which penetrates in the axial direction of the valve hole and communicates with the outflow passage.

3. In the relief valve according to claim 1, The aforementioned casing is A cylindrical housing member that houses the valve body and the elastic body, A relief valve having a valve seat attached to one end of the housing member in the axial direction, and having a valve seat on which the valve body sits and unseats, and a valve hole that is opened and closed by the valve body sitting and unseats on the valve seat.

4. In the relief valve according to claim 3, The valve body moves away from and sits on the valve seat by being displaced in the axial direction of the housing member. The elastic body biases the valve body in the axial direction of the housing member, The casing further includes an elastic body receiver attached to the opposite side of the housing member from the valve body receiving side to support the elastic body, The elastic support is a relief valve mounted to the housing member so as to be displaceable in the axial direction of the housing member.

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