Valve device

Abstract

To discharge drains as quickly as possible at a start of an operation.SOLUTION: A drain trap 100 comprises: a casing 1 in which a valve chamber 22 is formed; a first valve mechanism 3 which has a first valve hole 311 formed at the valve chamber 22, and a first valve body 32 accommodated in the valve chamber 22 and opening and closing the first valve hole 311 by being displaced; and a second valve mechanism 4 which has a communication hole 40 formed at the first valve body 32 so as to penetrate it, making the valve chamber 22 and the first valve hole 311 communicate with each other when the first valve mechanism 3 is in a valve-closed state, and having a hole diameter smaller than the first valve hole 311, a second valve body 42 accommodated in the valve chamber 22 and opening and closing the communication hole 40 by being displaced, and a second thermal reactor 43 displacing the second valve body 42 according to a temperature. The first valve mechanism 3 also has a spring 33 for energizing the first valve body 32 in a valve-opening direction, and when the pressure of the valve chamber 22 is lowered to a prescribed value, the first valve body 32 is displaced by an energization force of the spring 33, and the first valve hole 311 is released.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technology of this disclosure relates to a valve device. [Background technology]

[0002] Conventionally, there has been known a thermally responsive drain trap that is installed in a steam system and opens or closes depending on the surrounding temperature. For example, the drain trap disclosed in Patent Document 1 has a valve mechanism having a valve hole, a valve body, and a thermally responsive device. In the valve mechanism, when the surrounding temperature is high, the valve body is displaced by the thermally responsive device to close the valve hole, and when the surrounding temperature is low, the valve body is displaced by the thermally responsive device to open the valve hole. In this way, the drain trap discharges drain below a predetermined temperature, while preventing the discharge of steam above the predetermined temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-151960 A Summary of the Invention [Problem to be solved by the invention]

[0004] When starting up a steam system, it is necessary to drain the remaining drain as quickly as possible in order to prevent water hammer, which may occur when steam mixes with low-temperature drain remaining in the system. However, there are cases where the amount of drain remaining in the system is greater than expected, and in such cases, it becomes difficult to drain the drain as quickly as possible.

[0005] The technique disclosed herein has been made in consideration of the above circumstances, and has an object to provide a valve device that can quickly discharge fluid at the start of operation. [Means for solving the problem]

[0006] The valve device of the present disclosure includes a casing, a first valve mechanism, and a second valve mechanism. The casing is formed with a valve chamber through which a fluid flows. The first valve mechanism includes a first valve hole formed in the valve chamber, and a first valve body housed in the valve chamber and displaced to open and close the first valve hole. The second valve mechanism includes a communication hole formed through the first valve body, which communicates the valve chamber and the first valve hole when the first valve mechanism is in a closed state and has a hole diameter smaller than that of the first valve hole, a second valve body housed in the valve chamber and displaced to open and close the communication hole, and a second thermal actuator that displaces the second valve body in response to temperature. The first valve mechanism further includes a spring that biases the first valve body in an opening direction, and is configured such that when the pressure in the valve chamber drops to a predetermined value, the first valve body is displaced by the biasing force of the spring to open the first valve hole. Effect of the Invention

[0007] The valve device described above allows the fluid to be quickly discharged at the start of operation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a drain trap. [Diagram 2] FIG. 2 is a plan view showing the valve chamber in the casing as viewed from the inlet side. [Diagram 3] FIG. 3 is an enlarged side view showing the first valve mechanism and the second valve mechanism. [Figure 4] FIG. 4 is an enlarged side view of the third valve mechanism. [Diagram 5] FIG. 5 is a cross-sectional view showing the second thermally responsive device and the third thermally responsive device when the valve is open. [Figure 6] FIG. 6 is a view corresponding to FIG. 3, showing one state of the first valve mechanism and the second valve mechanism. [Figure 7] FIG. 7 is a cross-sectional view showing the second thermally responsive device and the third thermally responsive device when the valve is closed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. Fig. 1 is a cross-sectional view of a drain trap 100. Fig. 2 is a plan view showing a valve chamber 22 in a casing 1 as viewed from the inlet 21 side.

[0010] The drain trap 100 is provided in a steam pipe or the like of a steam system, and prevents the outflow of steam while allowing drain to flow out. The drain trap 100 is an example of a valve device, and drain and steam are examples of fluids. The drain trap 100 includes a casing 1 and three valve mechanisms (i.e., a first valve mechanism 3, a second valve mechanism 4, and a third valve mechanism 5). The casing 1 is formed with a flow path 2 through which drain flows. The three valve mechanisms are provided in the flow path 2 and open and close the flow path 2.

[0011] The casing 1 is formed, as part of the flow path 2, with a valve chamber 22 through which the drain flows, an inlet 21 and an outlet 24 for the drain which communicate with the valve chamber 22, and a communication passage 23 which communicates between the valve chamber 22 and the outlet 24. In addition, the valve chamber 22 is formed, as part of the flow path 2, with a communication hole 40 (see FIG. 3) of a first valve body 32 which will be described later.

[0012] The flow path 2 has three flow paths (i.e., a first flow path 2A, a second flow path 2B, and a third flow path 2C) for allowing the drain to flow out. Specifically, the first flow path 2A is formed by an inlet 21, a valve chamber 22, and an outlet 24. The second flow path 2B is formed by the inlet 21, a valve chamber 22, a communication hole 40, and an outlet 24. The third flow path 2C is formed by the inlet 21, the valve chamber 22, a communication passage 23, and an outlet 24.

[0013] Specifically, the casing 1 has a first member 11 and a second member 12 that are connected to each other in the flow direction of the drain. More specifically, a flange 11a of the first member 11 and a flange 12a of the second member 12 are connected with a gasket 13 sandwiched therebetween. In this example, the flanges 11a and 12a of the first member 11 and the second member 12 are fixed by a clamp 7. An inlet 21 is formed in the first member 11, and a communication passage 23 and an outlet 24 are formed in the second member 12. A valve chamber 22 is formed across the first member 11 and the second member 12. The inlet 21 and the outlet 24 have the same first axis X1, that is, are formed coaxially with each other. In this example, the flow direction of the drain is the same as the direction in which the first axis X1 extends.

[0014] Fig. 3 is an enlarged side view of the first valve mechanism 3 and the second valve mechanism 4. Fig. 4 is an enlarged side view of the third valve mechanism 5. Fig. 5 is a cross-sectional view showing the second thermally responsive device 43 and the third thermally responsive device 53 when the valves are open.

[0015] The first valve mechanism 3 opens and closes the first flow path 2A. That is, the first valve mechanism 3 allows the drain that has flowed into the valve chamber 22 from the inlet 21 to flow out to the outlet 24, while preventing the steam that has flowed into the valve chamber 22 from the inlet 21 from flowing out to the outlet 24. Specifically, the first valve mechanism 3 is provided in the valve chamber 22, and has a first valve seat 31, a first valve body 32, and a spring 33.

[0016] The first valve seat 31 has a first valve hole 311. That is, the first valve hole 311 is formed in the valve chamber 22. The first valve hole 311 communicates the valve chamber 22 with the outlet port 24. More specifically, the first valve hole 311 opens to a first wall surface 12b that defines a part of the valve chamber 22. A second axis X2, which is the axis of the first valve hole 311, is parallel to the first axis X1. That is, the first valve hole 311 opens in the direction in which the drain flows. An annular seat surface 312 that surrounds the first valve hole 311 is formed in the first wall surface 12b.

[0017] The first valve body 32 is housed in the valve chamber 22 and displaces to open and close the first valve hole 311. Specifically, the first valve body 32 is disposed in the valve chamber 22 so as to face the first valve hole 311. The first valve body 32 opens and closes the first valve hole 311 by moving forward and backward to seat and separate from the first valve seat 31. In other words, the first valve body 32 advances into the first valve hole 311 and seats on the seat surface 312 to close the first valve hole 311, and retreats from the first valve hole 311 to separate from the seat surface 312 to open the first valve hole 311.

[0018] More specifically, the first valve body 32 has a columnar portion 321 that opens and closes the first valve hole 311, and a support portion 323 that supports a second thermally responsive device 43 of the second valve mechanism 4 described below. The columnar portion 321 is disposed coaxially with the first valve hole 311 and faces the first valve hole 311. A seal surface 322 that seats on and separates from the seat surface 312 is formed on the end face of the columnar portion 321 on the side facing the first valve hole 311.

[0019] The support portion 323 is a substantially annular plate provided on the outer periphery of the end portion of the cylindrical portion 321 opposite to the first valve hole 311 side. In other words, the support portion 323 is a member extending radially outward from the outer periphery of the cylindrical portion 321. The outer periphery of the support portion 323 is curved toward the opposite side to the first valve hole 311 side, i.e., toward the upstream side in the flow direction of the drainage. The second thermally responsive device 43 is placed on the outer periphery of the support portion 323. In this way, the support portion 323 supports the second thermally responsive device 43.

[0020] The spring 33 biases the first valve body 32 in the valve opening direction, and in this example is formed by a coil spring. One end of the spring 33 is in contact with the first wall surface 12b, more specifically, on the outer side of the seat surface 312 of the first wall surface 12b. In other words, the first wall surface 12b is It is also formed as a spring receiving portion for the spring 33. The other end of the spring 33 contacts the first valve body 32, more specifically, the support portion 323. In this way, the spring 33 supports the first valve body 32 and urges it in the valve opening direction.

[0021] The first valve mechanism 3 is configured to displace the first valve body 32 in response to the pressure in the valve chamber 22 to open and close the first valve hole 311 .

[0022] That is, in the first valve mechanism 3, when the pressure in the valve chamber 22 falls to a predetermined value (in this example, "pressure Pb at the start of operation"), the first valve body 32 is displaced by the biasing force of the spring 33 (i.e., leaves the first valve seat 31) and opens the first valve hole 311. Also, in the first valve mechanism 3, when the pressure in the valve chamber 22 rises to "pressure Pa during operation", the first valve body 32 is displaced against the biasing force of the spring 33 (i.e., seats on the first valve seat 31) and closes the first valve hole 311. In this way, the first valve hole 311 is opened and closed, thereby opening and closing the first flow path 2A.

[0023] When the steam system is operating, the pressure in the valve chest 22 rises to the "operating pressure Pa". On the other hand, when the operation starts (i.e., when the operation is started up), the pressure in the valve chest 22 does not rise immediately, and therefore the pressure in the valve chest 22 becomes the "operating pressure Pb" which is lower than the operating pressure Pa. A valve closing force (a force that causes the first valve body 32 to close) acts on the first valve body 32 due to the operating pressure Pa and the operating pressure Pb. Naturally, the valve closing force of the first valve body 32 due to the operating pressure Pb is smaller than the valve closing force of the first valve body 32 due to the operating pressure Pa.

[0024] The biasing force of the spring 33 is set to be larger than the valve closing force of the first valve body 32 due to the pressure Pb at the start of operation. Also, the biasing force of the spring 33 is set to be smaller than the valve closing force of the first valve body 32 due to the pressure Pa during operation. Therefore, the first valve mechanism 3 opens at the start of operation because the pressure in the valve chamber 22 drops to the pressure Pb at the start of operation, and closes during the subsequent operation because the pressure in the valve chamber 22 rises to the pressure Pa during operation.

[0025] The second valve mechanism 4 opens and closes the second flow path 2B. In other words, the second valve mechanism 4 allows the drain that has flowed into the valve chamber 22 from the inlet 21 to flow out to the outlet 24 via the communication hole 40 of the first valve body 32, while preventing the steam that has flowed into the valve chamber 22 from the inlet 21 from flowing out to the outlet 24. Specifically, the second valve mechanism 4 is provided in the valve chamber 22, and has the communication hole 40, a second valve seat 41, a second valve body 42, and a second thermally responsive actuator 43.

[0026] The communication hole 40 communicates between the valve chamber 22 and the first valve hole 311 when the first valve mechanism 3 is in a closed state. The communication hole 40 is formed penetrating the first valve body 32. More specifically, the communication hole 40 penetrates the cylindrical portion 321 in the direction of its axis and is formed coaxially with the cylindrical portion 321. In this example, the communication hole 40 has a large diameter portion on the first valve hole 311 side and a small diameter portion on the opposite side to the first valve hole 311 side. The small diameter portion has a hole diameter smaller than that of the first valve hole 311. The small diameter portion is formed as a second valve hole 411 described later.

[0027] The second valve seat 41 is formed in the first valve body 32, more specifically, in the cylindrical portion 321. As described above, the second valve seat 41 has the second valve hole 411, which is the small diameter portion of the communication hole 40. That is, the second valve hole 411 opens to the end face of the cylindrical portion 321 on the side where the support portion 323 is provided. When the first valve mechanism 3 is in the valve closed state, the second valve hole 411 communicates between the valve chamber 22 and the communication hole 40 (more specifically, the large diameter portion of the communication hole 40). The second valve hole 411 is formed coaxially with the first valve hole 311. An annular seat surface 412 surrounding the second valve hole 411 is formed on the end face of the cylindrical portion 321 where the second valve hole 411 opens.

[0028] In this way, the first valve body 32 functions as a valve body for the first valve mechanism 3, and also functions as a valve seat for the second valve mechanism 4. Therefore, the number of parts in the first valve mechanism 3 and the second valve mechanism 4 is reduced.

[0029] The second valve body 42 is accommodated in the valve chamber 22 and opens and closes the second valve hole 411 by displacing to open and close the communication hole 40. Specifically, the second valve body 42 is disposed in the valve chamber 22 so as to face the second valve hole 411. The second valve body 42 opens and closes the second valve hole 411 by moving forward and backward to seat and separate from the second valve seat 41. That is, the second valve body 42 closes the second valve hole 411 by advancing into the second valve hole 411 and seating on the seat surface 412, and opens the second valve hole 411 by retreating from the second valve hole 411 and separating from the seat surface 412. A seal surface 421 that seats and separates from the seat surface 412 is formed on the surface of the second valve body 42 facing the second valve hole 411 (see FIG. 5).

[0030] The second thermally responsive device 43 displaces the second valve body 42 in response to temperature. That is, the second thermally responsive device 43 causes the second valve body 42 to seat and unseat on the second valve seat 41, thereby causing the second valve body 42 to open and close the second valve hole 411. As shown in FIG. 5 , the second thermally responsive device 43 has a base 61, a support member 62, a first diaphragm 63, a second diaphragm 64, an expansion medium 65, and a contact portion 66.

[0031] The first diaphragm 63 forms an accommodation chamber S1 between itself and the base 61. Specifically, the first diaphragm 63 is formed in a substantially disk shape. The first diaphragm 63 is deformable so that its central portion is displaced in the direction of the second axis X2. In other words, the first diaphragm 63 is provided coaxially with the second valve hole 411. The base 61 is formed in a substantially disk shape. The base 61 has substantially the same outer diameter as the first diaphragm 63 and faces the first diaphragm 63.

[0032] The expansion medium 65 is accommodated in the accommodation chamber S1, and expands and contracts according to temperature to deform the first diaphragm 63. For example, the expansion medium 65 is a liquid having a boiling point lower than that of water. The expansion medium 65 may be water, or a mixture of water and a liquid having a boiling point lower than that of water.

[0033] The storage chamber S1 is a sealed space. In the storage chamber S1, the first diaphragm 63 is deformed by the expansion and contraction of the expansion medium 65. Specifically, when the expansion medium 65 expands, the first diaphragm 63 is deformed so that the center of the first diaphragm 63 moves away from the base 61, that is, the storage chamber S1 expands. On the other hand, when the expansion medium 65 contracts, the first diaphragm 63 is deformed so that the center of the first diaphragm 63 moves closer to the base 61, that is, the storage chamber S1 shrinks.

[0034] An opening 61a for injecting the expansion medium 65 into the storage chamber S1 is formed in the center of the base 61. The opening 61a is sealed by a plug 67. The plug 67 is fixed to the base 61 by, for example, welding.

[0035] The second diaphragm 64 is formed in a substantially disk shape. The second diaphragm 64 has substantially the same outer diameter as the first diaphragm 63. The first diaphragm 63 and the second diaphragm 64 face each other. More specifically, the second diaphragm 64 faces the surface of the first diaphragm 63 opposite the base 61. In other words, the second diaphragm 64 is provided outside the accommodation chamber S1. The second diaphragm 64 is deformable so that its central portion is displaced in the direction of the second axis X2.

[0036] The support member 62 sandwiches the first diaphragm 63 and the second diaphragm 64 between the support member 62 and the base 61. Specifically, the support member 62 is formed in a substantially disk shape. The support member 62 has substantially the same outer diameter as the base 61, and faces the surface of the second diaphragm 64 on the opposite side to the first diaphragm 63.

[0037] The contact portion 66 transmits the deformation of the first diaphragm 63 to the second diaphragm 64. Specifically, the contact portion 66 is disposed in the space S2 between the first diaphragm 63 and the second diaphragm 64. The contact portion 66 is attached to a surface of the second diaphragm 64 that faces the first diaphragm 63. The contact portion 66 transmits the deformation of the first diaphragm 63 to the second diaphragm 64 by coming into contact with the first diaphragm 63 when the expansion medium 65 expands.

[0038] The second thermally responsive device 43 holds the second valve body 42 and displaces (more specifically, advances and retreats) the second valve body 42 by deformation of the first diaphragm 63. Specifically, the second thermally responsive device 43 holds the second valve body 42 between the support member 62 and the second diaphragm 64. The second thermally responsive device 43 advances and retreats the second valve body 42 through an opening 62a formed in the support member 62.

[0039] Specifically, the second valve body 42 is provided on the surface of the second diaphragm 64 opposite to the first diaphragm 63. The second valve body 42 is welded in a state in which the central portion of the second diaphragm 64 is sandwiched between the second valve body 42 and the contact portion 66. The second valve body 42 is displaced integrally with the central portion of the second diaphragm 64 in response to deformation of the second diaphragm 64.

[0040] The opening 62a is formed in the center of the support member 62. A part of the second valve body 42 can protrude from the opening 62a toward the opposite side to the first diaphragm 63. The second valve body 42 advances and retreats through the opening 62a relative to the second valve hole 411. Furthermore, the support member 62 is formed with a plurality of openings 62c surrounding the opening 62a. The drainage that has flowed into the valve chamber 22 can flow into the space between the support member 62 and the second diaphragm 64 through the openings 62a and 62c.

[0041] The second diaphragm 64 and the second valve body 42 are formed with a through hole 422 penetrating the second diaphragm 64 and the second valve body 42. Specifically, holes are formed in the second diaphragm 64 and the second valve body 42, and these holes are continuously connected to form the through hole 422. The through hole 422 communicates the space S2 with the second valve hole 411 when the valve is closed. A hole 66a connected to the through hole 422 is formed in the center of the contact portion 66. Furthermore, the contact portion 66 is formed with a communication passage 66b that communicates the space S2 with the hole 66a.

[0042] In the second valve mechanism 4, the second valve body 42 is displaced in response to temperature to open and close the second valve hole 411. Specifically, when the temperature of the valve chamber 22 decreases, the expansion medium 65 contracts and deforms the first diaphragm 63, causing the second valve body 42 to move back and separate from the second valve seat 41. This opens the second valve hole 411. On the other hand, when the temperature of the valve chamber 22 increases, the expansion medium 65 expands and deforms the first diaphragm 63, causing the second valve body 42 to move forward and seat on the second valve seat 41. This closes the second valve hole 411. In this way, the second valve hole 411 is opened and closed, thereby opening and closing the second flow path 2B.

[0043] As described above, the second thermally responsive device 43 is supported by the support portion 323 of the first valve body 32. The support portion 323 supports the second thermally responsive device 43 so that the distance between the communication hole 40 and the second valve body 42, more specifically, the distance between the second valve hole 411 and the second valve body 42, is a predetermined value. This predetermined value is set based on the displacement amount of the second valve body 42 when the second valve body 42 is displaced toward the second valve hole 411 due to the deformation of the first diaphragm 63, and the required outflow amount of the drain when the valve is opened. When the predetermined value is small, the second valve body 42 is easily seated on the second valve seat 41, but the required outflow amount is low. When the predetermined value is large, the required outflow amount is high, but the second valve body 42 is difficult to seat on the second valve seat 41.

[0044] In this way, the support portion 323 also has a positioning function for determining the relative position of the second valve body 42 with respect to the second valve seat 41. Since the second thermally responsive actuator 43 is supported by the support portion 323 of the first valve body 32, it displaces integrally with the first valve body 32. Therefore, even if the first valve body 32 displaces, the relative position of the second valve body 42 with respect to the second valve seat 41 is kept constant.

[0045] The second valve mechanism 4 also has a snap ring 44. The snap ring 44 is provided in the valve chamber 22. More specifically, the snap ring 44 is provided upstream of the second thermally responsive device 43 in the direction of drain flow. The snap ring 44 regulates the upstream position of the second thermally responsive device 43 in the direction of drain flow. The valve chamber 22 is provided with a guide 12d that guides the displacement of the first valve body 32 and the second thermally responsive device 43.

[0046] The third valve mechanism 5 opens and closes the third flow path 2C. In other words, the third valve mechanism 5 allows the drain that has flowed into the valve chamber 22 from the inlet 21 to flow out to the outlet 24 via the communication passage 23, while preventing the steam that has flowed into the valve chamber 22 from the inlet 21 from flowing out to the outlet 24. As also shown in Fig. 4, the third valve mechanism 5 is provided in the valve chamber 22, and has a third valve seat 51, a third valve body 52, and a third thermally responsive actuator 53.

[0047] The third valve seat 51 has a third valve hole 511 which is an opening of the communication passage 23 on the valve chamber 22 side. That is, the third valve hole 511 is formed in the valve chamber 22. The third valve hole 511 communicates the valve chamber 22 and the communication passage 23. More specifically, the third valve hole 511 opens to the second wall surface 12c which defines a part of the valve chamber 22. The third axis X3 which is the axis of the third valve hole 511 is parallel to the second axis X2. That is, the third axis X3 opens in the direction in which the drain flows. The third axis X3 is shifted from the second axis X2 in a direction perpendicular to the second axis X2. The second wall surface 12c is formed with an annular seat surface 512 which surrounds the third valve hole 511.

[0048] In this example, the opening position of the third valve hole 511 in the flow direction of the drain is upstream of the opening position of the communication hole 40 (more specifically, the second valve hole 411). In other words, in the extending direction of the second axis X2 and the third axis X3, the position of the second wall surface 12c is closer to the inlet 21 than the position of the cylindrical portion 321 of the first valve body 32.

[0049] The third valve body 52 is housed in the valve chamber 22 and displaces to open and close the third valve hole 511. Specifically, the third valve body 52 is disposed in the valve chamber 22 so as to face the third valve hole 511. The third valve body 52 opens and closes the third valve hole 511 by moving forward and backward to seat and separate from the third valve seat 51. That is, the third valve body 52 advances into the third valve hole 511 and seats on the seat surface 512 to close the third valve hole 511, and retreats from the third valve hole 511 to separate from the seat surface 512 to open the third valve hole 511. A seal surface 521 that seats and separates from the seat surface 512 is formed on the surface of the third valve body 52 facing the third valve hole 511 (see FIG. 5).

[0050] The third thermally responsive device 53 displaces the third valve body 52 in response to temperature. That is, the third thermally responsive device 53 causes the third valve body 52 to seat and unseat on the third valve seat 51, and causes the third valve body 52 to open and close the third valve hole 511. As shown in FIG. 5, the third thermally responsive device 53 has a similar configuration to the second thermally responsive device 43. That is, the third thermally responsive device 53 also has a base 61, a support member 62, a first diaphragm 63, a second diaphragm 64, an expansion medium 65, and a contact portion 66.

[0051] In the third thermally responsive actuator 53, the first diaphragm 63 is deformable such that its central portion is displaced in the direction of the third axis X3. Also, the second diaphragm 64 is deformable such that its central portion is displaced in the direction of the third axis X3.

[0052] In the third valve mechanism 5, the third valve body 52 is displaced in response to temperature to open and close the third valve hole 511. Specifically, when the temperature of the valve chamber 22 decreases, the expansion medium 65 contracts to deform the first diaphragm 63, causing the third valve body 52 to move back and separate from the third valve seat 51. This opens the third valve hole 511. On the other hand, when the temperature of the valve chamber 22 increases, the expansion medium 65 expands to deform the first diaphragm 63, causing the third valve body 52 to move forward and seat on the third valve seat 51. This closes the third valve hole 511. In this way, the third valve hole 511 is opened and closed, thereby opening and closing the third flow path 2C.

[0053] As shown in FIG. 4, the third thermally responsive device 53 is placed and supported on a step 12e provided in the valve chamber 22. In the valve chamber 22, the step 12e is located closer to the inlet 21 than the second wall surface 12c. The step 12e supports the third thermally responsive device 53 so that the distance between the third valve hole 511 and the third valve body 52 is a predetermined value. This predetermined value is set based on the displacement amount of the second valve body 42 when the second valve body 42 is displaced toward the second valve hole 411 due to the deformation of the first diaphragm 63, as well as the required outflow amount of drain when the valve is opened. The step 12e also has a positioning function for determining the relative position of the third valve body 52 with respect to the third valve seat 51.

[0054] Similarly to the second valve mechanism 4, the third valve mechanism 5 has a snap ring 54. The snap ring 54 is provided in the valve chamber 22. More specifically, the snap ring 54 is provided upstream of the third thermally responsive device 53 in the direction of drainage flow. The snap ring 54 regulates the upstream position of the third thermally responsive device 53 in the direction of drainage flow.

[0055] <Operation at start of operation> The operation of the drain trap 100 described above when the steam system starts operating (when starting up operation) will be described. When operation starts, low-temperature, low-pressure drain remains in the piping of the steam system, and the pressure and temperature of the valve chest 22 are low. In other words, the pressure of the valve chest 22 drops to the pressure Pb at the start of operation.

[0056] In the first valve mechanism 3, the biasing force of the spring 33 is greater than the closing force of the first valve body 32 due to the pressure Pb at the start of operation, so that the first valve body 32 is lifted off the first valve seat 31 and the first valve hole 311 is open, as shown in Fig. 3. In the third valve mechanism 5, the temperature of the valve chamber 22 is low, so that the third valve body 52 is lifted off the third valve seat 51 and the third valve hole 511 is open, as shown in Fig. 5. In the second valve mechanism 4, the temperature of the valve chamber 22 is low, so that the second valve body 42 is lifted off the second valve seat 41 and the second valve hole 411 is open, as shown in Fig. 5. In other words, all of the first valve mechanism 3, the second valve mechanism 4, and the third valve mechanism 5 are open.

[0057] At the start of operation, residual drain in the steam system flows into the drain trap 100. In the drain trap 100, the drain that flows into the valve chamber 22 from the inlet 21 flows out to the outlet 24 via the first valve hole 311. The drain is discharged from the outlet 24 to the outside of the casing 1. In this manner, in the drain trap 100, residual drain is discharged through the first flow path 2A. Here, since the first valve hole 311 has a larger hole diameter than the second valve hole 411, a large amount of drain is discharged quickly.

[0058] Furthermore, when there is a very large amount of residual drain in the steam system, some of the drain that has flowed from the inlet 21 into the valve chest 22 may flow through the third valve hole 511 into the communicating passage 23 and then out to the outlet 24. Furthermore, some of the drain that has flowed from the inlet 21 into the valve chest 22 may flow through the second valve hole 411 into the communicating hole 40 and then out to the outlet 24. In this way, in the drain trap 100, the residual drain is also discharged through the second flow path 2B and the third flow path 2C. Therefore, even when there is a very large amount of residual drain, the residual drain is quickly discharged.

[0059] Furthermore, in the second valve mechanism 4, even if the first valve mechanism 3 is opened, i.e., even if the first valve body 32 is displaced, the relative position of the second valve body 42 with respect to the second valve seat 41 is maintained. Therefore, an appropriate amount of drainage is ensured in the second flow path 2B.

[0060] In this way, the drain trap 100 quickly discharges a large amount of low-temperature drain remaining in the steam system at the start of operation.

[0061] <Operation during operation> The operation of the drain trap 100 during operation of the steam system will now be described. During operation, high-pressure drain generated in the piping of the steam system flows into the drain trap 100, and the pressure in the valve chest 22 becomes high. In other words, the pressure in the valve chest 22 rises to the pressure Pa during operation.

[0062] Fig. 6 is a view equivalent to Fig. 3 showing one state of the first valve mechanism 3 and the second valve mechanism 4. In the first valve mechanism 3, the biasing force of the spring 33 is smaller than the closing force of the first valve body 32 caused by the pressure Pa during operation, so that as shown in Fig. 6, the first valve body 32 is seated on the first valve seat 31, and the first valve hole 311 is closed by the first valve body 32. In other words, the first valve mechanism 3 is in a closed state during operation.

[0063] The drain that has flowed into the drain trap 100 flows to and is stored in the portion of the valve chamber 22 on the second valve mechanism 4 side. That is, since the opening position of the communication hole 40 (more specifically, the second valve hole 411) is downstream of the opening position of the third valve hole 511, the drain flows in the valve chamber 22 to the second valve mechanism 4 side, not to the third valve mechanism 5 side.

[0064] The temperature of the drain flowing into the drain trap 100 during operation is somewhat high, but not as high as the temperature of the steam. Therefore, basically, as long as drain, not steam, flows into the drain trap 100, the temperature of the valve chamber 22, more specifically, the ambient temperature of the second valve mechanism 4, does not become very high. Therefore, in the second valve mechanism 4, the volume of the expansion medium 65 (i.e., the degree of expansion) is small, so that the second valve body 42 remains separated from the second valve seat 41 as shown in FIG. 6. In other words, the second valve mechanism 4 remains in an open state. Therefore, the drain that flows into the drain trap 100 flows out of the casing 1 via the second valve mechanism 4, i.e., via the second flow path 2B.

[0065] When the amount of drainage in the drain trap 100 increases and becomes greater than the amount of drainage outflow by the second valve mechanism 4, the drainage accumulates in the entire valve chamber 22. That is, the drainage in the valve chamber 22 extends not only around the second valve mechanism 4 but also around the third valve mechanism 5. Then, in the third valve mechanism 5, as in the second valve mechanism 4, the volume of the expansion medium 65 is small, so that the third valve body 52 remains separated from the third valve seat 51 as shown in FIG. 4. That is, the third valve mechanism 5 remains in an open state. Therefore, the drainage that has flowed into the drain trap 100 flows out of the casing 1 through not only the second valve mechanism 4 but also the third valve mechanism 5, that is, through not only the second flow path 2B but also the third flow path 2C.

[0066] Thus, in the drain trap 100 during operation, the first valve mechanism 3 is closed but the second valve mechanism 4 and the third valve mechanism 5 are open, so that the drain can be appropriately discharged. Moreover, when the amount of drain flowing into the drain trap 100 is not that much, the drain is discharged only by the second valve mechanism 4. When the amount of drain flowing into the drain trap 100 is large, the drain is discharged by both the second valve mechanism 4 and the third valve mechanism 5. In other words, in the drain trap 100 during operation, the drain discharge capacity changes depending on the amount of drain flowing in.

[0067] FIG. 7 is a cross-sectional view showing the second thermally responsive device 43 and the third thermally responsive device 53 when the valve is closed. When high-temperature and high-pressure steam flows into the valve chamber 22 from the inlet 21, the temperature and pressure of the valve chamber 22 become high. Therefore, the pressure of the valve chamber 22 remains at the pressure Pa during operation, and the first valve mechanism 3 remains in a closed state. On the other hand, in the second valve mechanism 4, since the temperature of the valve chamber 22 becomes high, the second valve body 42 is seated on the second valve seat 41 due to the deformation of the first diaphragm 63 as shown in FIG. 7. This closes the second valve hole 411. Similarly, in the third valve mechanism 5, the third valve body 52 is seated on the third valve seat 51 due to the deformation of the first diaphragm 63 as shown in FIG. 7. This closes the third valve hole 511. In this way, the first flow path 2A, the second flow path 2B, and the third flow path 2C are closed, and the steam that has flowed into the drain trap 100 is prevented from flowing out.

[0068] In this manner, during operation, the drain trap 100 allows drain to flow out while preventing the outflow of steam.

[0069] Next, the fail-open function of the second valve mechanism 4 (third valve mechanism 5) will be described. The fail-open function in this example is a function that automatically opens the second valve hole 411 (third valve hole 511) when at least one of the first diaphragm 63 and the second diaphragm 64 is broken during valve closing. For example, when the first diaphragm 63 is broken, the expansion medium 65 leaks from the accommodation chamber S1 to the space S2. The expansion medium 65 leaked into the space S2 flows out to the second valve hole 411 (third valve hole 511) through the communication passage 66b, the hole 66a, and the through hole 422 (through hole 522). The first diaphragm 63 is deformed such that its center is displaced to the opposite side to the second diaphragm 64 due to the leakage of the expansion medium 65. The second diaphragm 64 is released from the pressure of the first diaphragm 63 and deformed such that its center is displaced toward the first diaphragm 63. In response to this, the second valve body 42 (third valve body 52) leaves the second valve seat 41 (third valve seat 51), and the second valve hole 411 (third valve hole 511) is opened. As a result, the fluid in the valve chamber 22 flows out from the second valve hole 411 (third valve hole 511).

[0070] As described above, the drain trap 100 includes the casing 1, the first valve mechanism 3, and the second valve mechanism 4. The casing 1 is formed with the valve chamber 22 through which the drain flows. The first valve mechanism 3 includes a first valve hole 311 formed in the valve chamber 22, and a first valve body 32 housed in the valve chamber 22 and displaced to open and close the first valve hole 311. The second valve mechanism 4 includes a communication hole 40 formed through the first valve body 32, which communicates the valve chamber 22 and the first valve hole 311 when the first valve mechanism 3 is in a closed state and has a hole diameter smaller than that of the first valve hole 311, a second valve body 42 housed in the valve chamber 22 and displaced to open and close the communication hole 40, and a second thermally responsive actuator 43 which displaces the second valve body 42 in response to temperature. The first valve mechanism 3 further has a spring 33 that biases the first valve body 32 in the valve opening direction, and is configured so that when the pressure in the valve chamber 22 drops to a predetermined value, the first valve body 32 is displaced by the biasing force of the spring 33 to open the first valve hole 311.

[0071] According to this configuration, at the start of operation, the pressure in the valve chamber 22 is low, so that not only the second valve mechanism 4 but also the first valve mechanism 3 opens. The hole diameter of the first valve hole 311 of the first valve mechanism 3 is larger than the hole diameter of the second valve hole 411 of the second valve mechanism 4. Therefore, at the start of operation, a large amount of drain remaining in the steam system can be quickly discharged. This makes it possible to prevent water hammer, which can occur when low-temperature drain mixes with steam.

[0072] Furthermore, since the communication hole 40 through which the second valve body 42 opens and closes is formed in the first valve body 32, the first valve body 32 functions as a valve body for the first valve mechanism 3 and also functions as a valve seat for the second valve mechanism 4. This makes it possible to reduce the number of parts in the first valve mechanism 3 and the second valve mechanism 4. Also, the first valve mechanism 3 and the second valve mechanism 4 can be made more compact.

[0073] In the drain trap 100, the second thermally responsive device 43 holds the second valve body 42. The first valve body 32 has a support portion 323 that supports the second thermally responsive device 43 so that the distance between the communication hole 40 and the second valve body 42 is a predetermined value.

[0074] According to this configuration, the second thermally responsive element 43 is supported so that the distance between the communication hole 40 and the second valve body 42 (more specifically, the distance between the second valve hole 411 and the second valve body 42) is a predetermined value, so that even if the first valve body 32 is displaced, the relative position of the second valve body 42 with respect to the communication hole 40 can be maintained. Therefore, the amount of drainage discharged by the second valve mechanism 4 can be appropriately ensured.

[0075] The drain trap 100 also includes a third valve mechanism 5 having a third valve hole 511 formed in the valve chamber 22, a third valve body 52 housed in the valve chamber 22 and displaced to open and close the third valve hole 511, and a third thermally responsive device 53 that displaces the third valve body 52 in response to temperature.

[0076] According to this configuration, the amount of drain discharged can be increased because the third valve mechanism 5 is provided. In particular, at the start of operation, a larger amount of residual drain can be quickly discharged.

[0077] In the drain trap 100, the communication hole 40 and the third valve hole 511 open in the flow direction of the drain in the valve chamber 22. The opening position of the third valve hole 511 in the flow direction is upstream of the opening position of the communication hole 40.

[0078] According to this configuration, the drain discharge capacity can be changed according to the amount of drain inflow during operation. That is, when the amount of drain inflow into the drain trap 100 is not so large, the drain can be discharged only by the second valve mechanism 4. When the amount of drain inflow into the drain trap 100 is large, the drain can be discharged by both the second valve mechanism 4 and the third valve mechanism 5. This makes it possible to suppress the outflow of steam, for example, compared to when the opening position of the communication hole 40 and the opening position of the third valve hole 511 are the same in the flow direction of the drain. When the opening position of the communication hole 40 and the opening position of the third valve hole 511 are the same as described above, the drain is discharged by both the second valve mechanism 4 and the third valve mechanism 5, even when the amount of drain inflow is small. In this case, the drain is discharged all at once, which may cause the steam to flow out as well. In this example, such a risk can be suppressed.

[0079] Furthermore, compared to the case where the opening position of the communication hole 40 and the opening position of the third valve hole 511 are the same as described above, the drain discharge operation during operation can be started more quickly. Because the opening position of the communication hole 40 is downstream of the opening position of the third valve hole 511, the drain flows to the second valve mechanism 4 side in the valve chest 22 and is stored there. Therefore, even if the amount of drain flowing in is small, the ambient temperature of the second valve mechanism 4 can be quickly made to be equivalent to the temperature of the drain. This allows the second valve mechanism 4 to be opened quickly, so that the drain discharge operation by the second valve mechanism 4 can be started quickly.

[0080] Furthermore, as in the above embodiment, by making the opening position of the communicating hole 40 and the opening position of the third valve hole 511 different in the flow direction of the drain, the second thermal responsive device 43 and the third thermal responsive device 53 can be positioned while suppressing an increase in size in the direction perpendicular to the flow direction of the drain.

[0081] (Other embodiments) As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. are appropriately performed. In addition, it is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings and detailed description should not immediately be taken to mean that these non-essential components are essential.

[0082] For example, the third valve mechanism 5 may be omitted.

[0083] Furthermore, the opening position of the third valve hole 511 in the flow direction of the drain may be substantially the same as the opening position of the communication hole 40, or may be downstream of the opening position of the communication hole 40.

[0084] Moreover, the first valve body 32 may be configured to omit the support portion 323. In that case, by providing a mechanism for making the second thermally responsive device 43 follow the displacement of the first valve body 32, the relative position of the second valve body 42 with respect to the communication hole 40 can be maintained.

[0085] Furthermore, the drain trap 100 is not limited to a so-called steam trap that prevents the outflow of steam, but may be an air trap that prevents the outflow of air, or a gas trap that prevents the outflow of gas.

[0086] Furthermore, in the above embodiment, the drain trap 100 that handles drain as the fluid has been described, but the valve device of the present disclosure can also be applied to those that handle fluids other than drain. [Industrial Applicability]

[0087] As described above, the technology of the present disclosure is useful for a valve device. [Explanation of symbols]

[0088] 100 Drain trap (valve device) 1 Casing 22 Valve chamber 3 First valve mechanism 311 First valve hole 32 First valve body 323 Support part 33 Spring 4. Second valve mechanism 40 Communication hole 42 Second valve body 43 Second heat responsive device 5. Third valve mechanism 511 3rd valve hole 52 Third valve body 53 Third heat actuator

Claims

1. a casing having a valve chamber through which a fluid flows; a first valve mechanism including a first valve hole formed in the valve chest and a first valve body accommodated in the valve chest and displacing to open and close the first valve hole; a communication hole formed through the first valve body, communicating between the valve chest and the first valve hole when the first valve mechanism is in a closed state and having a hole diameter smaller than that of the first valve hole, a second valve body housed in the valve chest and displacing to open and close the communication hole, and a second valve mechanism having a second thermal actuator that displaces the second valve body in response to temperature, The first valve mechanism further includes a spring that biases the first valve body in a valve opening direction, and is configured such that, when the pressure in the valve chamber falls to a predetermined value, the first valve body is displaced by the biasing force of the spring to open the first valve hole. A valve device characterized in that

2. 2. The valve device according to claim 1, the second thermally responsive device holds the second valve body, The first valve body has a support portion that supports the second thermally responsive device so that the distance between the communication hole and the second valve body is a predetermined value. A valve device characterized in that

3. 2. The valve device according to claim 1, The valve mechanism further includes a third valve hole formed in the valve chamber, a third valve body accommodated in the valve chamber and displaced to open and close the third valve hole, and a third thermal actuator displaces the third valve body in response to temperature. A valve device characterized in that

4. The valve device according to claim 3, the communication hole and the third valve hole are open in a direction in which a fluid flows through the valve chamber, The opening position of the third valve hole in the flow direction is upstream of the opening position of the communication hole. A valve device characterized in that

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