A minimum flow valve

Abstract

The present invention relates to the technical field of fluid control devices, and discloses a minimum flow valve, comprising a valve body, a valve cavity is provided in the middle of the valve body, a valve seat is provided in the middle of the valve cavity, and a valve cage is provided on the top surface of the valve seat; the valve cage is composed of a plurality of annular cage plates which are orderly overlapped into a hollow column, the outer wall of the uppermost cage plate is provided with an annular cavity for fluid to enter the valve cage, each cage plate is provided with a flow channel for axial movement of the fluid, and some cage plates are provided with radial counter-attack grooves for radial movement of the fluid, the upper end of the valve cover passes through the valve cavity, the outer wall of the valve cover is air-tightly connected to the valve body, the upper end of the valve core assembly passes through the valve cover, and the valve core assembly is air-tightly connected to the inner wall of the valve cover, the valve has good air tightness, a large flow area of ​​the flow channel, a simple cross-sectional shape, and controllable machining accuracy, and at the same time, the direction, arrangement and structure of the flow channel can be used to realize the collision, friction and counter-attack of the fluid, so as to meet the minimum flow valve with a complete pressure drop and a large pressure reduction gradient, and has great promotion value and broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of fluid control devices, and in particular to a minimum flow valve. Background Art

[0002] The boiler feed pump delivers water from the deaerator to the boiler. The flow control valve (also known as the boiler feed pump recirculation valve) is installed at the outlet of the feed pump and connected to the deaerator. The system where the valve is located is called the recirculation system. To prevent the feed pump from overheating and cavitation, the minimum flow control valve controls the flow of the feed pump to be greater than a certain specified safety flow, that is, the minimum flow. When the boiler feed water requires a very small flow, such as when the steam turbine trips, the minimum flow control valve must be opened in time to return part of the high-pressure water from the outlet of the feed pump to the deaerator to ensure the safe operation of the feed pump.

[0003] Since the pressure of the feed pump during normal operation is determined by whether it supplies water to the outside, the pressure of the feed pump fluctuates greatly. In many cases, the fluctuation range even exceeds 30MPa. The minimum flow regulating valve of the boiler feed pump must have the ability to avoid flashing and prevent cavitation. In addition, the valve is in a closed state for a long time (at least 90% of the working time), so it is very difficult to close and ensure long-term zero leakage in a high pressure difference environment.

[0004] In current conventional technology, minimum flow valves are available in various forms, especially key component cages, which have styles such as circulation counter-flow type, multi-stage valve core throttling type and labyrinth stacking type. Most of these various minimum flow valves still have a certain throttling effect, but due to the special working conditions, some structural defects, such as small flow area of ​​the flow channel, complex labyrinth shape and low processing accuracy, are ultimately reflected in the working process and product performance, which may lead to cavitation, erosion and flashing of the valve, causing the valve to malfunction in a short time or even be directly damaged. In addition, there are many problems such as incomplete pressure drop, severe cavitation, high noise, large vibration and easy leakage.

[0005] Therefore, the field of fluid control device technology is in urgent need of a minimum flow valve with good air tightness, large flow channel area, simple cross-sectional shape, controllable processing accuracy, and the ability to utilize the direction, arrangement, and structure of the flow channel to achieve fluid collision, friction, and impact, thereby meeting the requirements of complete pressure drop and a large pressure drop gradient. Summary of the invention

[0006] The present invention overcomes the defects of the prior art and provides a minimum flow valve with good air tightness, large flow channel area, simple cross-sectional shape, and controllable processing accuracy. At the same time, it can also utilize the direction, arrangement, and structure of the flow channel to achieve fluid collision, friction, and impact, thereby meeting the requirements of complete pressure drop and a large pressure drop gradient.

[0007] The present invention is achieved through the following technical solutions:

[0008] A minimum flow valve comprises a valve body, a valve cavity is provided in the middle of the valve body, a flow inlet communicated with an inlet pipe is provided on the side wall of the valve cavity, a discharge outlet communicated with an outlet pipe is provided on the bottom of the valve cavity, a valve seat is provided in the middle of the valve cavity, and a valve cage is provided on the top surface of the valve seat; the valve cage is composed of a plurality of annular cage plates stacked in an orderly manner into a hollow cylinder, the outer side wall of the uppermost cage plate is provided with an annular cavity for fluid to enter the valve cage, each of the cage plates is provided with a flow channel for axial movement of the fluid, and some of the cage plates are provided with radial offset grooves for radial movement of the fluid; a valve cover is provided on the top surface of the valve cage, the upper end of the valve cover passes through the valve cavity, the outer side wall of the valve cover is air-tightly connected to the valve body, a valve core assembly is provided in the middle of the valve cage, the upper end of the valve core assembly passes through the valve cover, and the valve core assembly is air-tightly connected to the inner side wall of the valve cover.

[0009] Furthermore, the flow channel in the uppermost cage plate passes through the bottom surface of the annular cavity and the bottom surface of the cage plate, and the flow channels in each of the cage plates in the lower layer pass through the top and bottom surfaces of the cage plate, and the number of flow channels in each of the cage plates decreases as the distance between the cage plate and the valve cover increases.

[0010] Furthermore, the flow channel includes a water outlet hole located on the bottom surface of the cage plate and a water inlet hole group connected to the water outlet hole, the water inlet hole group includes multiple water inlet holes, the aperture of the water outlet hole is larger than the aperture of the water inlet hole, and the sum of the heights of the water inlet hole and the water outlet hole is equal to the height of the flow channel.

[0011] Furthermore, the plurality of flow channels are arranged into a plurality of concentric circle groups on the cage plate, and some of the cage plates are provided with circumferential connecting grooves, which connect a plurality of water outlet holes located in the same circle group.

[0012] Furthermore, each of the cage plates located in the lower layer is provided with a plurality of radial counter-hedge grooves evenly distributed around the circumference, the centrifugal end of each of the radial counter-hedge grooves is connected to a plurality of flow channels, and the centripetal end of each of the radial counter-hedge grooves is connected to the cylindrical cavity in the middle of the valve cage.

[0013] Furthermore, the valve core assembly includes a valve stem that can be raised and lowered in a controllable manner, and the side wall of the valve stem at one end that extends into the middle cavity of the valve cage is provided with a slot, and the outer side wall of the slot is provided with a split nut with an external thread, and the split nut is composed of two semicircular nut petals, and the outer side thread of the split nut is connected to the piston, and the outer side wall of the lower end of the piston is adapted to the middle cavity of the valve cage.

[0014] Furthermore, the aperture of the middle cavity of the valve seat is smaller than the diameter of the middle cavity of the valve cage, a dynamic sealing ring is provided at the lower edge of the piston, and a fixed sealing ring is provided at the upper edge of the middle cavity of the valve seat, and the dynamic sealing ring and the fixed sealing ring are matched.

[0015] Furthermore, the upper end of the valve cover is provided with an inner side wall of a sealing section with an enlarged diameter, and a first sealing assembly is provided between the inner side wall of the valve cover sealing section and the valve core assembly, and the first sealing assembly includes a first sealing packing located between the inner side wall of the valve cover sealing section and the outer side wall of the valve stem, a first pressure ring is provided on the top of the first sealing packing, a pressure plate is provided on the top of the first pressure ring, a through hole is provided in the middle of the pressure plate for the valve stem to pass through, and a plurality of first fastening elements are passed through the pressure plate near the outer edge, and the lower end of each of the first fastening elements is fixedly connected to the upper end face of the valve cover, and a packing gasket is provided at the bottom of the first sealing packing.

[0016] Furthermore, a second sealing assembly is provided between the outer side wall of the valve cover and the valve body, the second sealing assembly includes a second sealing filler arranged between the outer side wall of the valve cover and the inner side wall of the upper end opening of the valve body, a second pressure ring is provided on the top of the second sealing filler, a pressure plate is provided on the top of the second pressure ring, a plurality of circumferentially evenly distributed second fastening elements are passed through the pressure plate near the outer edge, the lower end of each of the second fastening elements is fixedly connected to the upper end surface of the valve body, and a gap is left between the bottom surface of the pressure plate and the upper end surface of the valve body.

[0017] Furthermore, a throttling orifice plate, a first-stage pre-pressure reducer, and a second-stage pre-pressure reducer are sequentially arranged in the inlet pipe along the fluid entry direction, and a post-pressure reducer is arranged in the outlet pipe.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] The present invention comprises a valve body, a valve cavity is provided in the middle of the valve body, a valve seat is provided in the middle of the valve cavity, and a valve cage is provided on the top surface of the valve seat; the valve cage is composed of a plurality of annular cage plates which are orderly overlapped into a hollow column, the outer wall of the uppermost cage plate is provided with an annular cavity for fluid to enter the valve cage, each cage plate is provided with a flow channel for axial movement of the fluid, and some cage plates are provided with radial counter-attack grooves for radial movement of the fluid; a valve cover is provided on the top surface of the valve cage, the upper end of the valve cover passes through the valve cavity, the outer wall of the valve cover is air-tightly connected to the valve body, a valve core assembly is provided in the middle of the valve cage, the upper end of the valve core assembly passes through the valve cover, and the valve core assembly is air-tightly connected to the inner wall of the valve cover, has good air tightness, a large flow area of ​​the flow channel and a simple cross-sectional shape, is convenient and simple to process, and is easy to control in precision, and can also utilize the direction, arrangement and structure of the flow channel to realize the collision, friction and counter-attack of the fluid, thereby meeting the demand for complete pressure drop and fluid regulation with a large pressure drop gradient, and has great promotion value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0021] Figure 1 It is a schematic cross-sectional view of the overall structure of the present invention;

[0022] Figure 2 It is a cross-sectional schematic diagram of the valve core assembly of the present invention;

[0023] Figure 3 is a schematic diagram of a valve stem of the present invention;

[0024] Figure 4 It is a top view and a half-section front view of the split nut of the present invention;

[0025] Figure 5 is a schematic diagram of a piston of the present invention;

[0026] Figure 6 It is a schematic diagram of a pressure plate of the present invention;

[0027] Figure 7 is a schematic diagram of the second pressure ring of the present invention;

[0028] Figure 8 is a schematic diagram of a pressing plate of the present invention;

[0029] Fig. 9 is a schematic diagram of a first pressure ring of the present invention;

[0030] Fig.10 is a schematic diagram of a packing gasket of the present invention;

[0031] Fig.11 A schematic diagram of a valve cover and a bushing of the present invention;

[0032] Fig.12 is a schematic diagram of a valve seat of the present invention;

[0033] Fig.13 is a schematic diagram of a valve cover of the present invention;

[0034] Fig.14 is a schematic diagram of a bushing of the present invention;

[0035] Fig.15 is a schematic diagram of a throttling orifice plate of the present invention;

[0036] Fig.16 It is a schematic diagram of a first-stage pre-pressure reducer of the present invention;

[0037] Fig.17 It is a schematic diagram of the two-stage pre-pressure reducer of the present invention;

[0038] Fig.18 It is a schematic diagram of the post-pressure reducer of the present invention;

[0039] Fig.19 is a three-dimensional schematic diagram of a valve cage of the present invention;

[0040] Fig. 20 It is a three-dimensional schematic diagram of a quarter section of the valve cage of the present invention;

[0041] Fig.21 A half-section front view of the valve cage of the present invention;

[0042] Fig. 22 It is a cutaway top view, a half-cutaway front view and a bottom view of the primary cage plate of the present invention;

[0043] Fig.23 It is a top view, a half-section front view and a bottom view of the first secondary cage plate of the present invention;

[0044] Fig.24 It is a top view, a half-section front view and a bottom view of the second secondary cage plate of the present invention;

[0045] Fig.25 It is a top view, a half-section front view and a bottom view of the third secondary cage plate of the present invention;

[0046] Fig.26 The fourth secondary cage plate of the present invention is a top view, a half-section front view and a bottom view;

[0047] Fig. 27 A top view, a half-section front view and a bottom view of the fifth secondary cage plate of the present invention;

[0048] Fig.28 The top view, half-section front view and bottom view of the sixth secondary cage plate of the present invention;

[0049] Fig.29 The top view, half-section front view and bottom view of the seventh secondary cage plate of the present invention;

[0050] Fig.30 1. A top view, a half-section front view and a bottom view of an eighth secondary cage plate of the present invention;

[0051] Fig.31 1 and 2 are a top view, a half-section front view and a bottom view of the ninth secondary cage plate of the present invention.

[0052] Marks and corresponding parts names in the attached drawings:

[0053] 1-valve body, 11-valve cavity, 12-inlet pipe, 13-outlet pipe, 2-valve seat, 21-fixed sealing ring, 22-first ring groove, 23-second ring groove, 3-valve cage, 31-primary cage plate, 32-secondary cage plate, 321-first secondary cage plate, 322-second secondary cage plate, 323-third secondary cage plate, 324-fourth secondary cage plate, 325-fifth secondary cage plate, 326-sixth secondary cage plate, 327-seventh secondary cage plate, 328-eighth secondary cage plate, 329-ninth secondary cage plate, 33-ring cavity, 34-pressure equalizing hole, 35-water inlet hole group, 36-water outlet hole, 37-circumferential connecting groove, 38-radial counter-attack groove, 4-valve cover, 41-bushing, 5-valve core assembly, 51-valve stem, 52- Slot, 53-half-nut, 54-piston, 55-pressure-equalizing groove, 56-dynamic sealing ring, 6-first sealing assembly, 61-first sealing packing, 62-first pressure ring, 63-pressure plate, 64-first fastening element, 65-packing gasket, 7-pressure plate, 8-second sealing assembly, 81-second sealing packing, 82-second pressure ring, 83-second fastening element, 91-throttling orifice, 92-first-stage pre-pressure reducer, 93-rear-stage pressure reducer, 94-second-stage pre-pressure reducer. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0055] A minimum flow valve comprises a valve body 1, a valve cavity 11 is provided in the middle of the valve body 1, a flow inlet communicating with an inlet pipe 12 is provided on the side wall of the valve cavity 11, a discharge outlet communicating with an outlet pipe 13 is provided at the bottom of the valve cavity 11, a valve seat 2 is provided in the middle of the valve cavity 11, and a valve cage 3 is provided on the top surface of the valve seat 2; the valve cage 3 is composed of a plurality of annular cage plates stacked in an orderly manner into a hollow column, an annular cavity 33 for fluid to enter the valve cage 3 is provided on the outer wall of the uppermost cage plate, a flow channel for axial movement of the fluid is provided in each cage plate, and radial offset grooves 38 for radial movement of the fluid are provided in some cage plates; a valve cover 4 is provided on the top surface of the valve cage 3, the upper end of the valve cover 4 passes through the valve cavity 11, the outer wall of the valve cover 4 is air-tightly connected to the valve body 1, a valve core assembly 5 is provided in the middle of the valve cage 3, the upper end of the valve core assembly 5 passes through the valve cover 4, and the valve core assembly 5 is air-tightly connected to the inner wall of the valve cover 4.

[0056] It should be noted that the so-called "orderly stacking" is mainly reflected in two aspects. First, the cage plates of different levels need to be placed in order from large to small according to the flow channel area, and second, the flow channels of adjacent cage plates need to correspond to each other up and down. The flow channel area is gradually reduced to ensure that the fluid can be effectively depressurized to the required value when the valve cage 3 and the valve core have different openings. That is, when the valve core is at the lower part of the hollow cavity of the valve cage 3, the area of ​​fluid leakage is small and the pressure is high, but the fluid needs to flow through more levels of valve plates to completely flow out of the valve cage 3. When the valve core is at the higher part of the middle cavity of the valve cage 3, the area of ​​fluid leakage is large and the pressure is low, but most of the fluid is discharged after passing through fewer levels of valve plates, which generally ensures the stability of pressure reduction.

[0057] It can be understood that the number of secondary cage plates can be reasonably selected under different working conditions, for example, it is usually set to three to twelve levels to adapt to different pressure reduction requirements. In the actual implementation of the present technical solution, the secondary cage plates are set to nine levels, and together with the primary cage plate 31, they form a ten-level valve cage, forming an optimal valve cage 3 structure. The nine-level secondary cage plates include a first secondary cage plate 321, a second secondary cage plate 322, a third secondary cage plate 323, a fourth secondary cage plate 324, a fifth secondary cage plate 325, a sixth secondary cage plate 326, a seventh secondary cage plate 327, an eighth secondary cage plate 328, and a ninth secondary cage plate 329. The fluid enters the valve cage 3 from the annular cavity 33 of the primary cage plate 31. Every time it passes through a valve plate, the size and direction of the flow channel cross-section change, forming a layer-by-layer pressure reduction structure.

[0058] Furthermore, the flow channel in the uppermost cage plate passes through the bottom surface of the annular cavity 33 and the bottom surface of the cage plate, and the flow channels in each cage plate in the lower layer pass through the top and bottom surfaces of the cage plate, and the number of flow channels in each cage plate decreases as the distance between the cage plate and the valve cover 4 increases. Furthermore, the flow channel includes a water outlet 36 located on the bottom surface of the cage plate and a water inlet hole group 35 communicating with the water outlet 36, the water inlet hole group 35 includes a plurality of water inlet holes, the aperture of the water outlet 36 is larger than the aperture of the water inlet hole, and the sum of the heights of the water inlet hole and the water outlet 36 is equal to the height of the flow channel. It can be understood that the water inlet hole group 35 is a plurality of small holes. In the actual implementation process, three small holes are set in the technical solution, and the three small holes are not evenly distributed around the circumference, but are around the end of the radial counter-attack groove 38, so that the high-pressure fluid flowing out of the two holes separated on the left and right can impact each other and reduce pressure, and surrounding the counter-attack groove can also facilitate the fluid to enter the counter-attack groove smoothly. Obviously, the aperture of the small water inlet hole in the water inlet hole group 35 is smaller than the aperture of the water outlet hole 36. When the fluid passes out, the pressure is reduced due to the sudden increase in the cross-section. In actual implementation, the diameter of the water inlet hole is set to 1 / 4 of the diameter of the water outlet hole, which can not only ensure a sufficiently good pressure reduction effect, but also leave enough width between each water inlet hole to ensure structural strength.

[0059] Furthermore, multiple flow channels are arranged into several concentric circle groups on the cage plate, and some cage plates are provided with circumferential connecting grooves 37, which connect several water outlets 36 located in the same circle group. It can be understood that the provision of circumferential connecting grooves 37 can make the water outlets 36 in the same circle group communicate with each other, and the fluid distribution is more uniform, avoiding stress concentration on one side or one place, thereby improving the stability of the pressure drop, and can also increase the centrifugal force of the fluid and the stability of the valve cage and achieve the pressure drop.

[0060] Furthermore, each cage plate located at the lower layer is provided with a plurality of radial counter-impact grooves 38 evenly distributed around the circumference, the centrifugal end of each radial counter-impact groove 38 is communicated with a plurality of flow channels, and the centripetal end of each radial counter-impact groove 38 is communicated with the cylindrical cavity in the middle of the valve cage 3. It can be understood that the radial counter-impact grooves 38 can be provided to achieve collision and counter-impact of the fluid, thereby achieving pressure reduction.

[0061] Furthermore, the valve core assembly 5 includes a valve stem 51 that can be raised and lowered in a controlled manner. The side wall of the valve stem 51 that extends into the middle cavity of the valve cage 3 is provided with a slot 52. A split nut 53 with an external thread is set on the outer wall of the slot 52. The split nut 53 is composed of two semicircular nut petals. The outer thread of the split nut 53 is connected to the piston 54. The lower outer wall of the piston 54 is adapted to the middle cavity of the valve cage 3. It can be understood that the conventional method of directly sleeve and fix the piston 54 will make the piston 54 lose its axial mobility. The technical solution sets a slot 52 at the lower end of the valve stem 51 to realize the installation of the piston 54 in a plate-fixed manner. However, the diameter of the slot 52 is small, and ordinary nuts cannot be sleeved. Therefore, a special externally threaded split nut 53 is used to achieve the connection of the piston 54, while retaining the axial activity space of the piston 54.

[0062] Furthermore, the aperture of the cavity in the middle of the valve seat 2 is smaller than the diameter of the cavity in the middle of the valve cage 3, a dynamic sealing ring 56 is provided at the lower edge of the piston 54, and a fixed sealing ring 21 is provided at the upper edge of the cavity in the middle of the valve seat 2, and the dynamic sealing ring 56 is matched with the fixed sealing ring 21. It should be noted that the fixed sealing ring 21 and the dynamic sealing ring 56 in the technical solution are both clad with cobalt-based alloy at the edges by cladding process, and then ground and matched, and when the valve core assembly 5 is in a closed state, the sealing is achieved by using a very high degree of fit.

[0063] Furthermore, the upper end of the valve cover 4 is provided with an inner side wall of the sealing section with an enlarged diameter, and a first sealing assembly 6 is provided between the inner side wall of the sealing section of the valve cover 4 and the valve core assembly 5. The first sealing assembly 6 includes a first sealing packing 61 located between the inner side wall of the sealing section of the valve cover 4 and the outer side wall of the valve stem 51, a first pressing ring 62 is provided at the top of the first sealing packing 61, a pressing plate 63 is provided at the top of the first pressing ring 62, a through hole for the valve stem 51 to pass through is provided in the middle of the pressing plate 63, and a plurality of first fastening elements 64 are penetrated near the outer edge of the pressing plate 63, and the lower end of each first fastening element 64 is fixedly connected to the upper end face of the valve cover 4, and a packing gasket 65 is provided at the bottom of the first sealing packing 61. It can be understood that the first sealing assembly 6 ensures the sealing requirements between the inner wall of the valve cover 4 and the valve stem 51, and a packing gasket 65 is provided at the bottom of the first sealing packing 61, and the top surface of the packing gasket 65 is inclined, so that the first sealing packing 61 can be squeezed against the valve stem 51 when subjected to pressure, thereby improving the sealing reliability.

[0064] Furthermore, a second sealing assembly 8 is provided between the outer wall of the valve cover 4 and the valve body 1. The second sealing assembly 8 includes a second sealing filler 81 provided between the outer wall of the valve cover 4 and the inner wall of the upper opening of the valve body 1. A second pressure ring 82 is provided on the top of the second sealing filler 81. A pressure plate 7 is provided on the top of the second pressure ring 82. A plurality of second fastening elements 83 evenly distributed around the circumference are penetrated near the outer edge of the pressure plate 7. The lower end of each second fastening element 83 is fixedly connected to the upper end face of the valve body 1. A gap is left between the bottom surface of the pressure plate 7 and the upper end face of the valve body 1. It can be understood that the second sealing assembly 8 can achieve the sealing between the outer side of the valve cover 4 and the valve body 1. A gap is left between the bottom surface of the pressure plate 7 and the upper end face of the valve body 1, so that the pre-tightening force of the second fastening element 83 can be completely placed on the second pressure ring 82 and the second sealing filler 81, thereby ensuring the reliability of the second sealing assembly 8.

[0065] Furthermore, a throttling orifice plate 91, a first-stage pre-pressurizer, and a second-stage pre-pressure reducer 94 are sequentially arranged in the inlet pipe 12 along the fluid entry direction, and a post-pressure reducer 93 is arranged in the outlet pipe 13. It can be understood that the throttling orifice plate 91, the first-stage pre-pressurizer, and the second-stage pre-pressure reducer 94 are arranged in the inlet pipe 12 to achieve pressure reduction and reduce the fluid turbulence and unstable flow phenomena such as eddy current inside the channel of the valve body 1. The pre-pressure reducer can be designed with multiple small holes to filter impurities and prevent impurities from entering the inner cavity of the valve body 1 and damaging the valve. The pre-pressure reducer and the post-pressure reducer can bear 5%-10% of the total pressure drop to achieve the purpose of graded pressure reduction.

[0066] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0067] It should be understood that the terms “longitudinal”, “lateral”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the components or mechanisms referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0068] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a preferred implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A minimum flow valve, comprising a valve body (1), characterized in that: A valve cavity (11) is provided in the middle of the valve body (1), a side wall of the valve cavity (11) is provided with an inlet port communicating with an inlet pipe (12), a bottom of the valve cavity (11) is provided with an outlet port communicating with an outlet pipe (13), a valve seat (2) is provided in the middle of the valve cavity (11), and a valve cage (3) is provided on the top surface of the valve seat (2); The valve cage (3) is composed of a plurality of annular cage plates stacked in an orderly manner into a hollow cylindrical shape, the outer side wall of the uppermost cage plate is provided with an annular cavity (33) for fluid to enter the valve cage (3), each of the cage plates is provided with a flow channel for axial movement of the fluid, and some of the cage plates are provided with radial hedging grooves (38) for radial movement of the fluid; A valve cover (4) is provided on the top surface of the valve cage (3), the upper end of the valve cover (4) passes through the valve cavity (11), the outer wall of the valve cover (4) is air-tightly connected to the valve body (1), a valve core assembly (5) is provided in the middle of the valve cage (3), the upper end of the valve core assembly (5) passes through the valve cover (4), and the valve core assembly (5) is air-tightly connected to the inner wall of the valve cover (4); The flow channel in the uppermost cage plate passes through the bottom surface of the annular cavity (33) and the bottom surface of the cage plate, and the flow channels in each of the cage plates in the lower layer pass through the top surface and the bottom surface of the cage plate, and the number of flow channels in each of the cage plates decreases as the distance between the cage plate and the valve cover (4) increases; The flow channel comprises a water outlet hole (36) located on the bottom surface of the cage plate and a water inlet hole group (35) communicating with the water outlet hole (36); the water inlet hole group (35) comprises a plurality of water inlet holes; the diameter of the water outlet hole (36) is larger than the diameter of the water inlet hole; and the sum of the heights of the water inlet hole and the water outlet hole (36) is equal to the height of the flow channel; The plurality of flow channels are arranged on the cage plate into a plurality of concentric circle groups, and some of the cage plates are provided with circumferential connecting grooves (37), and the circumferential connecting grooves (37) connect a plurality of water outlet holes (36) located in the same concentric circle group; Each of the cage plates located at the lower layer is provided with a plurality of radial counter-attack grooves (38) uniformly distributed around the circumference, the centrifugal end of each of the radial counter-attack grooves (38) being communicated with a plurality of flow channels, and the centripetal end of each of the radial counter-attack grooves (38) being communicated with a cylindrical cavity in the middle of the valve cage (3).

2. A minimum flow valve according to claim 1, characterized in that: The valve core assembly (5) includes a valve stem (51) that can be raised and lowered in a controllable manner. The side wall of one end of the valve stem (51) that extends into the cylindrical cavity in the middle of the valve cage (3) is provided with a slot (52). A split nut (53) with an external thread is mounted in the slot (52). The split nut (53) is composed of two semicircular nut petals. The outer side of the split nut (53) is threadedly connected to a piston (54). The outer side wall of the lower end of the piston (54) is adapted to the cylindrical cavity in the middle of the valve cage (3).

3. A minimum flow valve according to claim 2, characterized in that: The aperture of the central cavity of the valve seat (2) is smaller than the diameter of the central cylindrical cavity of the valve cage (3); a dynamic sealing ring (56) is provided at the lower edge of the piston (54); a fixed sealing ring (21) is provided at the upper edge of the central cavity of the valve seat (2); the dynamic sealing ring (56) and the fixed sealing ring (21) are matched.

4. A minimum flow valve according to claim 2, characterized in that: The upper end of the valve cover (4) is provided with an inner side wall of a sealing section with an enlarged diameter, and a first sealing assembly (6) is provided between the inner side wall of the sealing section of the valve cover (4) and the valve core assembly (5). The first sealing assembly (6) includes a first sealing packing (61) located between the inner side wall of the sealing section of the valve cover (4) and the outer side wall of the valve stem (51). A first pressure ring (62) is provided on the top of the first sealing packing (61), and a pressure plate (63) is provided on the top of the first pressure ring (62). A through hole is provided in the middle of the pressure plate (63) for the valve stem (51) to pass through. A plurality of first fastening elements (64) are penetrated near the outer edge of the pressure plate (63), and the lower end of each of the first fastening elements (64) is fixedly connected to the upper end face of the valve cover (4). A packing gasket (65) is provided at the bottom of the first sealing packing (61).

5. A minimum flow valve according to claim 1, characterized in that: A second sealing component (8) is provided between the outer wall of the valve cover (4) and the valve body (1), and the second sealing component (8) includes a second sealing filler (81) provided between the outer wall of the valve cover (4) and the inner wall of the upper opening of the valve body (1), a second pressure ring (82) is provided on the top of the second sealing filler (81), a pressure plate (7) is provided on the top of the second pressure ring (82), and a plurality of second fastening elements (83) evenly distributed around the circumference of the pressure plate (7) are penetrated near the outer edge, and the lower end of each of the second fastening elements (83) is fixedly connected to the upper end surface of the valve body (1), and a gap is left between the bottom surface of the pressure plate (7) and the upper end surface of the valve body (1).

6. A minimum flow valve according to claim 1, characterized in that: A throttling orifice plate (91), a first-stage pre-pressure reducer (92), and a second-stage pre-pressure reducer (94) are sequentially arranged in the inlet pipe (12) along the fluid entry direction, and a post-pressure reducer (93) is arranged in the outlet pipe (13).

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