A valve stem connection structure

Abstract

The present invention discloses a valve stem connection structure, which is applied to the valve of a steam turbine, comprising: a two-half connection cone, the two-half connection cone is clamped on the connection of the valve stem; the connection of the valve stem is provided with a smooth transition curved surface; a tapered hole flange, which is sleeved on the two-half connection cone through a tapered hole, and presses the two-half connection cone. The tapered hole flange is also opposite to and connected to the oil motor flange in the valve of the steam turbine. The present invention solves the problem of stress concentration and fatigue fracture at the threaded connection of the valve stem caused by high-temperature high-frequency vibration of the conventional steam turbine valve stem.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbines, and in particular to a valve stem connection structure. Background Art

[0002] The steam flow regulation system of the steam turbine is divided into the main steam valve and the valve. Among them, the valve controls the steam flow entering the turbine by controlling the annular flow area of ​​different sizes formed by the distance between the valve disc and the valve seat. The continuous change of the valve opening, especially in the case of small opening, the high-speed high-temperature steam flow will arouse the high-frequency vibration of the valve stem. Due to the special structure of the valve stem, it needs to pass through the bushing, which makes it impossible to use the structure of the large flange at the end of the valve stem to improve the reliability of the connection. Conventional threaded connection structure can only be used. However, due to the characteristics of the threaded connection structure, there is stress concentration. Due to the existence of the threaded structure, there is no good inspection method for the processing quality of the threaded connection of the valve stem. On the other hand, since the valve stem is in a high-temperature environment, its own performance will also be affected by high temperature. If the conventional steam turbine unit operates in a small flow condition for a long time, or the valve produces severe high-frequency vibration for some reason, the threaded connection of the valve stem will often break. When the valve stem breaks, the steam turbine unit has to shut down for cooling, dismantle the valve for replacement, and the replacement cycle is long, which will cause great downtime losses to the steam turbine unit. Summary of the invention

[0003] The purpose of the present invention is to provide a valve stem connection structure to solve the problem of stress concentration fatigue fracture at the threaded connection of the high-temperature valve stem of a traditional steam turbine due to high-frequency vibration, and not only facilitate the control of the valve stem processing quality, but also facilitate the rapid connection of the valve stem.

[0004] In order to solve the above problems, the present invention is implemented by the following technical solutions:

[0005] A valve stem connection structure, which is applied to the valve of a steam turbine, comprises: a two-half connection cone cylinder, the two-half connection cone cylinder is clamped on the connection of the valve stem; the connection of the valve stem is provided with a smooth transition curved surface; a conical hole flange, which is sleeved on the two-half connection cone cylinder through a conical hole provided therein and presses the two-half connection cone cylinder. The large hole end of the conical hole is arranged closer to the oil motor flange than the small hole end thereof.

[0006] The tapered hole flange is also opposite to and connected to the oil motor flange in the valve of the steam turbine.

[0007] Optionally, the valve stem has a plurality of grooves distributed along the axial direction.

[0008] Optionally, the groove is an X-shaped groove.

[0009] Optionally, the two-half connecting cone is truncated cone-shaped as a whole, and its outer side wall matches the tapered hole of the tapered hole flange to achieve interference connection therewith.

[0010] Optionally, the two halves of the connecting cone are spliced ​​together to form a complete X-shaped inner hole, which matches the X-shaped groove so that the two can be snap-fitted.

[0011] Optionally, a fastening hole is provided on the conical flange, and the conical flange and the oil motor flange are connected by a fastener penetrating the fastening hole.

[0012] Optionally, the fastener is a bolt, and extends along the axial direction of the valve stem.

[0013] Optionally, it also includes: an elastic washer, which is sleeved on the bolt and located between the bolt cap of the bolt and the bottom surface of the conical flange; the elastic washer is used to store elastic force. When the valve shakes, when the tapered hole flange tends to move away from the oil motor flange, the elastic washer releases part of the elastic force to ensure that the tapered hole flange can still return to the state of tightly pressing the two-half connecting cone cylinder.

[0014] Optionally, it also includes: an adjusting gasket, which is arranged between the oil motor piston rod and the valve stem that passes through the oil motor flange, and is used to limit the movement of the valve stem relative to the oil motor piston rod.

[0015] The present invention has at least the following technical effects:

[0016] The valve stem connection structure provided by the present invention can realize the quick connection of the valve stem, that is, realize the quick installation of the valve. Since the threaded connection is no longer used at the valve stem connection, stress concentration and fatigue fracture at the threaded connection when the valve stem vibrates at high frequency is avoided. Moreover, since the valve stem connection of this structure adopts a smooth transition curved surface, it is more conducive to flaw detection after the valve stem is processed, thereby ensuring the quality of the valve stem and further improving the life of the valve stem connection.

[0017] The present invention adopts a special two-half connecting cone cylinder with an X-shaped inner hole and a conical outer circumference, and uses a conical hole flange to achieve the convenience of valve stem connection and even realize online operation of valve stem connection.

[0018] That is, the present invention solves the problem of stress concentration fatigue fracture of the threaded connection of the traditional high-temperature valve stem of the steam turbine due to high-frequency vibration. The unique structural design not only facilitates the control of the valve stem processing quality, but also facilitates the rapid connection of the valve stem. It provides a new solution to the high-frequency vibration fracture of the high-temperature valve stem of the steam turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A schematic diagram of a longitudinal cross-sectional structure of a valve stem connection structure provided by an embodiment of the present invention;

[0020] Figure 2 An exploded view of a valve stem connection structure provided in one embodiment of the present invention;

[0021] Figure 3 and Figure 4 Each of them is a schematic diagram of a longitudinal cross-sectional structure of a valve stem provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the longitudinal cross-sectional structure of a two-half connected cone provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0023] The valve stem connection structure proposed in the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0024] Combination Figure 1 and Figure 2 As shown, this embodiment provides a valve stem connection structure, which is applied to the valve of the steam turbine, including: a two-half connection cone cylinder 2, the two-half connection cone cylinder 2 is clamped on the connection of the valve stem 1; the connection of the valve stem 1 is provided with a smooth transition curved surface; a tapered hole flange 3, which is sleeved on the two-half connection cone cylinder 2 through a tapered hole provided therein, and presses the two-half connection cone cylinder 2. The tapered hole flange 3 is also opposite to and connected to the oil motor flange 6 in the valve of the steam turbine.

[0025] The valve stem connection structure provided in this embodiment can realize the rapid connection of the valve stem, that is, the quick installation of the valve. Since the threaded connection is no longer used at the valve stem connection, stress concentration and fatigue fracture at the threaded connection during high-frequency vibration of the valve stem are avoided. Moreover, since the valve stem connection of this structure adopts a smooth transition curved surface, it is more conducive to flaw detection after valve stem processing, ensuring the quality of the valve stem and further improving the life of the valve stem connection. That is, this embodiment not only solves the stress concentration problem at the threaded connection of the valve stem, but also the special structure is simple to operate and convenient for quality inspection. Moreover, the transformation of the new solution can be realized on the existing units by replacing only a few local parts. It is of great help to the high-reliability operation of the unit.

[0026] It is understandable that the valve mentioned in this embodiment is a valve of typical structure, the valve stem head is in the valve housing, used to adjust the airflow, the valve stem needs to pass through the valve cover to the outside, used to connect to the oil motor, and can be operated. A bushing is used where the valve cover is passed to reduce the gap between the valve stem and the valve cover to reduce the amount of air leakage. At the same time, the bushing is made of wear-resistant material to prevent the valve from being worn or stuck after long-term use.

[0027] In this embodiment, if Figure 3 As shown, the valve stem 1 has a plurality of grooves 10 distributed along the axial direction.

[0028] In this embodiment, please continue to refer to Figure 3 As shown, the groove 10 is an X-shaped groove, that is, Figure 3 As shown by the dotted line, from the longitudinal section of the valve stem 1, the groove 10 is X-shaped. One or more X-shaped groove features provided on the valve stem 1 can be used to connect the spare structure. When the connection at the outer end is accidentally broken, the connection structure can be moved downward to achieve rapid replacement of the spare structure and avoid downtime for replacement of the valve stem.

[0029] like Figure 4 As shown, when the groove 10 is an X-shaped groove, the angle a between the surface of the groove 10 and the vertical direction can be changed according to actual needs, for example, the angle a is an acute angle, preferably, it can be 5° to 10°. While ensuring that the stress on the valve stem meets the valve stem connection requirements, it also ensures that the service life of the connection is improved within a reasonable range.

[0030] Please continue to refer to Figure 1 As shown, in this embodiment, the outer circumference of the two-half connecting cone 2 is in a truncated cone shape as a whole, and its outer circumference matches the tapered hole of the tapered hole flange 2 to achieve interference connection therewith.

[0031] In this embodiment, if Figure 5As shown, the two halves of the connecting cone 2 are spliced ​​together to form a complete X-shaped inner hole 20, which matches the X-shaped groove to achieve the clamping connection with the valve stem 1. The X-shape of the X-shaped inner hole 20 can refer to Figure 5 As shown by the dotted line, the inner wall of the X-shaped inner hole 20 is also smooth and fits closely with the outer wall of the X-shaped groove.

[0032] This embodiment adopts a special two-half connecting cone cylinder with an X-shaped inner hole and a conical outer circumference, and uses a tapered hole flange to achieve convenience in valve stem connection and even realize online operation of valve stem connection.

[0033] The two-half connecting cone 2 is manufactured as a whole and then cut into two to ensure the uniformity of the size of the entire circle, thereby improving the uniformity of the contact stress during connection. The X-shaped angle of the connecting cone is strictly designed to ensure that the stress on the contact ring meets the valve stem connection requirements while also ensuring that it is within a reasonable range to increase the service life of the connection.

[0034] In this embodiment, the large hole end of the tapered hole is arranged closer to the oil motor flange 6 than the small hole end thereof.

[0035] In this embodiment, the conical flange 3 is provided with a fastening hole 40, and the conical flange 3 and the hydraulic motor flange 6 are connected by a fastener 4 penetrating the fastening hole 40. There are multiple fastening holes 40, which are evenly spaced along the circumference of the conical flange 3. Preferably, there are 4 fastening holes 40, but the present invention is not limited thereto.

[0036] In this embodiment, the fastener 4 is a bolt, and extends along the axial direction of the valve stem 1 .

[0037] In this embodiment, it also includes: an elastic washer 8, which is sleeved on the fastener 4 and located between the fastener 4, such as the bolt cap of the bolt, and the bottom surface of the tapered flange 3; the elastic washer 8 is used to store elastic force, and when the valve shakes and the tapered hole flange 3 tends to move downward, the elastic washer 8 releases part of the elastic force to ensure that the tapered hole flange 3 can still return to the state of tightly pressing the two-half connecting cone 2. In this embodiment, the number of the elastic washers 8 is the same as the number of the fasteners 4.

[0038] Please continue to refer to Figure 1 As shown, in this embodiment, it also includes: an adjusting gasket 5, which is arranged between the oil motor piston rod 7 passing through the oil motor flange 6 and the valve stem 1, and is used to limit the movement of the valve stem 1 relative to the oil motor piston rod 7.

[0039] It can be understood that the oil motor piston rod 7 is a part of the oil motor, and the oil motor flange 6 is used to connect the oil motor piston rod 7 with the valve stem 1. In order to transmit the force generated by the oil motor to the valve stem 1, the valve stem 1 is moved according to the control requirements.

[0040] The connection process of the valve stem connection structure of this embodiment is as follows: one or more X-shaped groove features on the valve stem 1, the two-half connection cone 2 is stuck on the valve stem 1, the tapered hole flange 3 is sleeved on the two-half connection cone 2, and under the action of the connecting fastener 4, it moves along the axial direction of the valve stem 1 close to the oil motor flange 6. The adjustment gasket 5 installed between the oil motor piston rod 7 and the valve stem 1 limits the movement of the valve stem 1 relative to the oil motor piston rod 7. When the preload force of the fastener 4 when installed on the oil motor flange 6 reaches the design requirement, the high elastic gasket 8 stores elastic force. When the valve shakes, when the tapered hole flange 3 has a tendency to move toward the oil motor flange 6, the high elastic gasket 8 will release part of the elastic force to ensure that the tapered hole flange 3 can still return to the state of pressing the two-half connection cone 2, so as to ensure that there is no vibration loosening at the connection, avoid the loss of the connection surface, and thus cause the problem of stress concentration.

[0041] That is, the valve stem connection structure of this embodiment clamps the X-shaped groove of the valve stem through the special X-shaped inner hole of the two-half connection cone, and then clamps the two-half connection cone through the tapered hole flange. When the bolt stretches the tapered hole flange along the axial direction of the valve stem and slightly moves, the two-half connection cone will tightly clamp the valve stem, thereby realizing the connection between the valve stem and the oil motor. A high-elastic gasket is arranged between the bolt and the tapered hole flange, so that the connection structure can still maintain a tight connection even under high-frequency vibration, avoiding loosening of the connection structure and causing damage to the active friction of the connection surface.

[0042] That is, the valve stem connection structure of this embodiment is simple to install and operate. It only requires moving the tapered hole flange down a certain distance, inserting the two-half connecting cone cylinder, and pulling back the tapered hole flange to achieve the connection of the valve stem. In addition, due to the compact structure, a spare connection groove can be realized. Even if the connection structure is accidentally damaged, a spare connection can be quickly achieved.

[0043] In summary, this embodiment solves the problem of stress concentration fatigue fracture of the traditional high-temperature valve stem of steam turbine due to high-frequency vibration at the threaded connection. The unique structural design not only facilitates the control of the valve stem processing quality, but also facilitates the rapid connection of the valve stem. It provides a new solution for the high-frequency vibration fracture of the high-temperature valve stem of the steam turbine.

[0044] It should be noted that, in this article, the terms "include", "comprises" or any other variations 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. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0045] In the description of the present invention, it should be understood that the terms "center", "height", "thickness", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0046] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A valve stem connection structure, which is applied to a valve of a steam turbine, characterized in that: include: A two-half connecting cone, wherein the two-half connecting cone is clamped on the connection of the valve stem; The connection of the valve stem is provided with a smooth transition curved surface; A tapered hole flange is sleeved on the two-half connecting cone cylinder through a tapered hole and presses the two-half connecting cone cylinder; The large hole end of the tapered hole is arranged closer to the hydraulic motor flange than the small hole end thereof; The tapered hole flange is also opposite to and connected to the oil motor flange in the valve of the steam turbine.

2. The valve stem connection structure according to claim 1, characterized in that: The valve stem is provided with a plurality of grooves distributed along the axial direction.

3. The valve stem connection structure according to claim 2, characterized in that: The groove is an X-shaped groove.

4. The valve stem connection structure according to claim 1, characterized in that: The two-half connecting cone is in a truncated cone shape as a whole, and its outer side wall matches the tapered hole of the tapered hole flange to achieve interference connection therewith.

5. The valve stem connection structure according to claim 3, characterized in that: The two halves of the connecting cone are spliced ​​together to form a complete X-shaped inner hole, which matches the X-shaped groove so that the two can be snap-fitted.

6. The valve stem connection structure according to claim 1, characterized in that: The conical flange is provided with a fastening hole, and the conical flange and the oil motor flange are connected by a fastener penetrating the fastening hole.

7. The valve stem connection structure according to claim 6, characterized in that: The fastener is a bolt, and extends along the axial direction of the valve stem.

8. The valve stem connection structure according to claim 7, characterized in that: Also includes: An elastic washer, which is sleeved on the bolt and located between the bolt cap of the bolt and the bottom surface of the conical flange; The elastic gasket is used to store elastic force. When the valve shakes, when the tapered hole flange tends to move away from the oil motor flange, the elastic gasket releases part of the elastic force to ensure that the tapered hole flange can still return to the state of tightly pressing the two-half connecting cone cylinder.

9. The valve stem connection structure according to claim 1, characterized in that: It also includes: an adjusting gasket, which is arranged between the oil motor piston rod and the valve stem that penetrates the oil motor flange, and is used to limit the movement of the valve stem relative to the oil motor piston rod.

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