Shaft seal arrangement and valve

Abstract

A shaft seal structure (12) having a plurality of V-shaped gaskets (14a to 14c) stacked in multiple layers, each V-shaped gasket being composed of a thick-walled annular top portion (16), a thin-walled inner side skirt portion (18), and a thin-walled outer side skirt portion (20), and a valve employing the same are provided. Adjacent top portions abut against each other, and adjacent inner side skirt portions and adjacent outer side skirt portions do not interfere with each other.

Description

Technical Field

[0001] The present invention relates to a shaft sealing structure disposed on the sliding part of a rod. Background Technology

[0002] It has long been known that a shaft seal consisting of a V-shaped gasket is disposed between a rod operating in liquids or vapors such as pharmaceuticals and the body containing the rod. For example, Japanese Utility Model Application Publication No. 04-049282 describes a structure in which a V-shaped gasket made of fluoropolymer is used to hold a V-shaped gasket made of fluororubber as a valve stem seal for sealing between the valve stem and the valve body. This allows for ensuring a tight seal across a wide range of temperatures, from low to high. These V-shaped gaskets are pressed forcefully against the valve stem and valve body by the reaction force of a spring.

[0003] Furthermore, Japanese Utility Model Application Publication No. 03-096468 describes a structure for a multi-layered V-shaped gasket made of fluororesin, used as a gasket installed between the piston and cylinder head of a fluid pressurization device. In this V-shaped gasket, the thickness of the top is set to be thinner than the other parts, and the inner apex angle is smaller than the front apex angle. If this V-shaped gasket is multi-layered and tightened, the outward protrusion increases, and it is generally believed that a stable leak-proof effect can be achieved.

[0004] However, these multi-layered V-shaped gaskets, with their sealing portions pressed against each other and forcefully pressed against the component, experience significant wear within the sealing portions. Furthermore, all the V-shaped gaskets wear out simultaneously. Therefore, the lifespan of the shaft seal may be shortened. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems.

[0006] The shaft seal structure of this invention is disposed between a rod and a cage. The rod is driven in a specified fluid and is movable in the axial direction. The cage houses the rod. The shaft seal structure has multiple stacked V-shaped gaskets. Each V-shaped gasket consists of a thick-walled annular top, an inner skirt with a thin wall extending obliquely inward from the top, and an outer skirt with a thin wall extending obliquely outward from the top. The inner skirt slides in contact with the outer surface of the rod at its tip, and the outer skirt abuts against the inner surface of the cage at its tip. Adjacent tops abut against each other, while adjacent inner and outer skirts do not interfere with each other.

[0007] Furthermore, the shaft seal structure of the present invention is disposed between a rod and a cage, the rod being driven in a specified fluid and capable of moving in the axial direction, the cage housing the rod, and the shaft seal structure having multiple U-shaped gaskets stacked in layers. Each U-shaped gasket consists of a thick-walled annular top, an inner skirt with a thin wall extending inward and axially from the top, and an outer skirt with a thin wall extending outward and axially from the top. The inner skirt has ribs that slide in contact with the outer surface of the rod, and the outer skirt has ribs that abut against the inner surface of the cage. Adjacent tops abut against each other, while adjacent inner and outer skirts do not interfere with each other.

[0008] According to the aforementioned shaft seal structure, the inner and outer skirts elastically deform under fluid pressure, thereby enabling the V-shaped or U-shaped gaskets to achieve good sealing performance. Furthermore, the wear of multiple V-shaped or U-shaped gaskets does not occur simultaneously, thus ensuring long-term maintenance of good sealing performance.

[0009] The shaft seal structure of this invention comprises multiple V-shaped or U-shaped gaskets consisting of a thick-walled top, a thin-walled inner skirt, and a thin-walled outer skirt, with adjacent inner and outer skirts not interfering with each other. Therefore, good sealing performance can be maintained for a long period.

[0010] The aforementioned objectives, features, and advantages will be readily understood from the following description of the embodiments with reference to the accompanying drawings. Attached Figure Description

[0011] Figure 1 This is an external view of an angle seat valve that employs the shaft sealing structure according to the first embodiment of the present invention.

[0012] Figure 2 It is along Figure 1 A cross-sectional view of the angle seat valve along line II-II.

[0013] Figure 3 yes Figure 2 An enlarged view of the shaft seal structure in an angle seat valve.

[0014] Figure 4 yes Figure 3 A cross-sectional view of the V-shaped gasket in the shaft seal structure.

[0015] Figure 5 yes Figure 1 When the angle seat valve is in the specified operating state, it is in harmony with... Figure 2 The corresponding diagram.

[0016] Figure 6 This indicates that the shaft seal structure according to the second embodiment of the present invention is equivalent to Figure 3 The image.

[0017] Figure 7 yes Figure 6 A cross-sectional view of the U-shaped gasket in the shaft seal structure.

[0018] Figure 8 This is a cross-sectional view of the shaft seal structure of the reference example. Detailed Implementation

[0019] In the following description, when terms related to up and down directions are used, they refer to the directions shown in the attached diagram. This includes the meaning of "slanting up" which is simply called "up" in mainland China, and the meaning of "slanting down" which is simply called "down" in mainland China.

[0020] (First Implementation)

[0021] Reference Figures 1-5 The shaft sealing structure 12 according to the first embodiment of the present invention will be described. Figure 1 and Figure 2 An angle seat valve 10 employing a shaft seal structure 12 is shown. The angle seat valve 10 is used to control the flow of fluids (hereinafter referred to as "fluids"), such as pharmaceutical solutions used for cleaning beverage containers or steam used for steam sterilization of medical equipment. The angle seat valve 10 is particularly suitable for controlling large flow rates. The angle seat valve 10 consists of a valve mechanism and an actuation mechanism. The valve mechanism includes a valve body 38 and a valve stem 32. The actuation mechanism includes a cylinder 56 and a piston 58.

[0022] The valve body 38 has a straight tubular main pipe section 40 and an inclined pipe section 42. The main pipe section 40 has an internal fluid passage 40a, and the inclined pipe section 42 intersects the main pipe section 40 at an angle. The inclined pipe section 42 is integrally formed with the main pipe section 40. The axis CL2 of the inclined pipe section 42 intersects the axis CL1 of the main pipe section 40 at a predetermined angle (e.g., 45 degrees). One end of the main pipe section 40 has an inlet port 40b, and the other end has an outlet port 40c. The interior of the inclined pipe section 42 is connected to the fluid passage 40a of the main pipe section 40.

[0023] The bottom wall of the main pipe section 40 has a raised portion 40d protruding toward the inclined pipe section 42. The valve body 38, extending from the portion where the main pipe section 40 and the inclined pipe section 42 intersect at an obtuse angle, has an annular valve seat 40e extending from the raised portion 40d to the inner wall of the valve core 38. The valve seat 40e forms an annular sealing surface perpendicular to the axis CL2 of the inclined pipe section 42.

[0024] A bottomed cylindrical retainer 34 is mounted on the upper part of the inclined tube section 42. Specifically, a large-diameter hole 42b with internal threads is formed on the upper inner circumference of the inclined tube section 42 via a stepped portion 42a. On the lower outer circumference of the retainer 34, a large-diameter portion 34b is formed via a first stepped portion 34a (see reference). Figure 3The retainer 34 is fitted into the large-diameter bore 42b of the inclined tube 42 until the large-diameter portion 34b of the retainer 34 abuts against the stepped portion 42a of the inclined tube 42. Then, a threaded fixing cylinder 54 is inserted from the upper side of the inclined tube 42 between the retainer 34 and the inclined tube 42. The fixing cylinder 54 is screwed into the inclined tube 42, and the top end of the fixing cylinder 54 abuts against the first stepped portion 34a of the retainer 34, thereby fixing the retainer 34 to the inclined tube 42. A sealing material 36a is installed on the large-diameter portion 34b of the retainer 34, abutting against the wall surface of the large-diameter bore 42b of the inclined tube 42.

[0025] The upper part of the retainer 34 extends upward from the inclined tube portion 42, and a rod cap 66 (described later) is installed at the end of the retainer 34. A first guide bushing 24 and a second guide bushing 26 are installed on the inner circumference of the retainer 34. The first guide bushing 24 and the second guide bushing 26 guide the valve stem 32 to be axially movable. A pressing plate 28 is installed at the lower end of the retainer 34. A scraper 30 and a plurality of V-shaped gaskets 14a to 14c are installed between the pressing plate 28 and the first guide bushing 24. An auxiliary gasket 22 is installed between the first guide bushing 24 and the second guide bushing 26. Details of these shaft sealing structures 12 will be described later.

[0026] A valve core 44, capable of abutting against a valve seat 40e, is connected to the lower end of the valve stem 32. Specifically, the valve core 44 has an upward-opening, bottomed bore 44a and a pair of pin holes 44b. The bore 44a extends along the axis CL2 of the valve core 44 (the same axis as the inclined tube portion 42). Each pin hole 44b extends in a direction orthogonal to the axis CL2 of the valve core 44 and opens on the wall of the bore 44a and the side of the valve core 44. On the other hand, the lower end of the valve stem 32 has a pin hole 32a. The pin hole 32a extends in a direction orthogonal to the axis CL2 of the valve stem 32 and extends laterally through the valve stem 32. The valve core 44 is fixed to the valve stem 32 by inserting the lower end of the valve stem 32 into the bore 44a of the valve core 44 and pressing a connecting pin 48 into the pair of pin holes 44b of the valve core 44 and the pin hole 32a of the valve stem 32.

[0027] The valve core 44 is disposed inside the inclined tube portion 42. When the valve core 44 moves together with the valve stem 32 to its lowest point, the sealing member 46 mounted on the valve core 44 abuts against the valve seat 40e, cutting off the communication between the inlet port 40b and the outlet port 40c. The direction of movement of the valve core 44 is inclined at a predetermined angle relative to the direction in which the fluid flows from the inlet port 40b toward the outlet port 40c. Furthermore, the components shown with reference to numerals 50 and 52 are nuts and washers used to secure the sealing member 46 to the valve core 44.

[0028] The valve stem 32 is inserted through the first guide bushing 24 and the second guide bushing 26, and extends upward from the retainer 34. The upper end of the valve stem 32 is reduced in diameter to form a small-diameter portion 32b with external threads at the top. The piston 58 is mounted on the upper end of the valve stem 32 by inserting the reinforcing plate 74, the piston 58, and the washer 76 through the small-diameter portion 32b of the valve stem 32, and by screwing the connecting rod 78 into the small-diameter portion 32b from the outside of the small-diameter portion 32b.

[0029] A piston 58 is disposed inside a cylindrical cylinder 56. The upper end of the cylinder 56 is closed by a head cover 62 and a cap 64. The lower end of the cylinder 56 is closed by a rod cap 66. A pressure chamber 70, capable of introducing air pressure, exists between the piston 58 and the rod cap 66. Air is supplied to and discharged from the pressure chamber 70 via the supply and discharge ports 66a of the rod cap 66. Furthermore, reference numeral 67a indicates a port for discharging air, etc., present in the chamber 67 between the piston 58 and the head cover 62.

[0030] A set of springs 72a and 72b are arranged between the piston 58 and the head cover 62 to apply downward force to the piston 58. A piston gasket 60 is installed on the outer periphery of the piston 58 to slide in contact with the cylinder 56. In addition, a sealing material 36b abuts against the rod cover 66 and a sealing material 36c slides in contact with the valve stem 32 are installed on the retainer 34. Through these sealing materials, the pressure chamber 70 is kept airtight from the outside and also airtight from the internal space of the retainer 34.

[0031] When air is introduced into pressure chamber 70, piston 58 is driven upward against the force of springs 72a and 72b, thereby moving valve stem 32 and valve core 44 upward. Conversely, when air is expelled from pressure chamber 70, piston 58 is driven downward by the force of springs 72a and 72b, thereby moving valve stem 32 and valve core 44 downward. By adjusting the pressure of the air introduced into pressure chamber 70, the position of piston 58 can be changed, thereby adjusting the opening degree of valve core 44.

[0032] (Details of shaft seal structure 12)

[0033] V-shaped gaskets 14a-14c are made of fluororesin, exhibiting excellent chemical and vapor resistance. For example... Figure 4As shown, the V-shaped gaskets 14a-14c with a V-shaped cross-section have: a thick-walled top 16, a thin-walled inner skirt 18 extending obliquely inward from the top 16, and a thin-walled outer skirt 20 extending obliquely outward from the top 16. The top 16 has an annular protrusion 16a projecting toward the side opposite to the inner skirt 18 and the outer skirt 20. The plurality of V-shaped gaskets 14a-14c are arranged such that their respective tops 16 are located on the side away from the valve core 44 and are stacked in the direction of the axis CL2 of the valve stem 32 (which is the same as the axis of the inclined tube portion 42).

[0034] The tops 16 of adjacent V-shaped gaskets 14a-14c abut against each other via a protrusion 16a of one gasket against the back surface 16b of the top 16 of the other gasket. On the other hand, the inner skirts 18 and outer skirts 20 of adjacent V-shaped gaskets 14a-14c are positioned opposite each other with a gap, without interfering with each other. The inner skirt 18 of the V-shaped gasket 14a-14c slides in contact with the outer surface of the valve stem 32 at its top inner periphery 18a. Furthermore, the outer skirt 20 of the V-shaped gasket 14a-14c abuts against the inner surface of the retainer 34 at its top outer periphery 20a.

[0035] This embodiment includes a lower V-shaped pad 14a, a middle V-shaped pad 14b, and an upper V-shaped pad 14c, totaling three V-shaped pads 14a to 14c, but the number of V-shaped pads is not limited to this.

[0036] The auxiliary gasket 22 is made of rubber such as FKM, providing excellent sealing performance. The auxiliary gasket 22, having a U-shaped cross-section, includes: an annular plate portion 22a, an inner cylindrical portion 22b extending from the inner periphery of the annular plate portion 22a, and an outer cylindrical portion 22c extending from the outer periphery of the annular plate portion 22a. The inner cylindrical portion 22b of the auxiliary gasket 22 slides in contact with the outer surface of the valve stem 32 at its inner periphery. The outer cylindrical portion 22c of the auxiliary gasket 22 abuts against the inner surface of the retainer 34 at its outer periphery.

[0037] The first guide bushing 24, made of resin such as PPS, is positioned by engaging with the second stepped portion 34c on the inner periphery of the retainer 34. The first guide bushing 24 has a recess 24a that accommodates the upper V-shaped pad 14c, and the bottom surface of the recess 24a abuts against the protrusion 16a of the upper V-shaped pad 14c. In addition, the first guide bushing 24 has a protrusion 24b that enters between the inner cylindrical portion 22b and the outer cylindrical portion 22c of the auxiliary pad 22.

[0038] A second guide bushing 26, made of resin such as PPS, is positioned by engaging a third step 34d on the inner periphery of the retainer 34. The lower end face of the second guide bushing 26 abuts against the annular plate portion 22a of the auxiliary pad 22. A scraper 30 for removing foreign matter is made of resin such as PEEK and is positioned by a pressing plate 28. The top of the scraper 30 abuts against the back side 16b of the top 16 of the lower V-shaped pad 14a. A plurality of V-shaped pads 14a to 14c are clamped between the scraper 30 and the first guide bushing 24, with adjacent tops 16 pressed against each other.

[0039] The angle seat valve 10 has the structure described above. The angle seat valve 10 includes a shaft seal structure 12, which comprises multiple V-shaped gaskets 14a-14c and an auxiliary gasket 22. Its function will now be explained.

[0040] like Figure 2 As shown, the initial state is defined by the sealing member 46 of the valve core 44 abutting against the valve seat 40e. In this initial state, no air is introduced into the pressure chamber 70, and the piston 58 is located at its lowest point due to the force of the springs 72a and 72b. Here, when fluid is supplied to the inlet port 40b of the valve body 38, the fluid pressure acts on the lower end face of the valve core 44. However, since the force of the springs 72a and 72b is greater than the force that the fluid pressure would exert on the valve core 44, the valve core 44 does not move.

[0041] In this state, the switching valve (not shown) is operated to supply air to the pressure chamber 70 from the supply / discharge port 66a. As a result, due to the air pressure acting on piston 58, the force pushing piston 58 upward exceeds the force of springs 72a and 72b, causing piston 58 to move upward. Piston 58 moves until it reaches a position where the force pushing piston 58 upward due to the air pressure stored in pressure chamber 70 balances the force pushing piston 58 downward due to the reaction force of the compressed springs 72a and 72b (see reference). Figure 5 Furthermore, strictly speaking, the force that pushes the piston 58 upward includes the force obtained by multiplying the pressure of the fluid acting on the valve core 44 by the cross-sectional area of ​​the valve stem 32.

[0042] Thus, the valve core 44 separates from the valve seat 40e, and the fluid supplied from the inlet port 40b is discharged from the outlet port 40c at a flow rate corresponding to the distance of separation between the valve core 44 and the valve seat 40e. Then, the switching valve is operated to discharge the air in the pressure chamber 70 to the outside through the supply / discharge port 66a. Consequently, the piston 58 moves to its lowest position under the force of the springs 72a and 72b, causing the sealing element 46 of the valve core 44 to abut against the valve seat 40e. This cuts off the connection between the inlet port 40b and the outlet port 40c, stopping the discharge of fluid from the outlet port 40c.

[0043] Fluid supplied from inlet port 40b fills the inclined tube section 42 each time the valve core 44 separates from the valve seat 40e. The shaft seal structure 12, which includes multiple V-shaped gaskets 14a-14c and auxiliary gasket 22, prevents fluid in the inclined tube section 42 from leaking to the outside.

[0044] Specifically, the lower V-shaped gasket 14a is subjected to the pressure of the fluid within the inclined tube 42, causing the inner skirt 18 of the thin wall to elastically deform, increasing the pressure between its inner circumference at the top 18a and the outer surface of the valve stem 32. Additionally, the outer skirt 20 of the thin wall undergoes elastic deformation, increasing the pressure between its outer circumference at the top 20a and the inner surface of the retainer 34. Thus, the lower V-shaped gasket 14a provides a high level of sealing, effectively preventing fluid from passing through the inclined tube 42. In the event of a small amount of fluid passing through the lower V-shaped gasket 14a, the auxiliary gasket 22 prevents leakage to the outside.

[0045] When the angle seat valve 10 has been used for a certain period of time, the wear of the lower V-shaped gasket 14a intensifies, rendering it unable to fully perform its sealing function and thus ceasing its operation. Consequently, the middle V-shaped gasket 14b, subjected to the pressure of the fluid within the inclined pipe section 42, replaces the lower V-shaped gasket 14a and performs the sealing function. Furthermore, when the angle seat valve 10 has been used for a certain period of time, the wear of the middle V-shaped gasket 14b intensifies, and the upper V-shaped gasket 14c replaces it and performs the sealing function. Thus, the sealing effect continues sequentially from the lower V-shaped gasket to the upper V-shaped gasket. Moreover, the wear of the V-shaped gaskets 14a to 14c occurs particularly at the inner periphery 18a of the top of the inner skirt 18, which repeatedly slides in contact with the reciprocating valve stem 32.

[0046] The inner skirt 18 and outer skirt 20 of the V-shaped gaskets 14a-14c are thin-walled, making them prone to elastic deformation under the pressure of the fluid within the inclined pipe section 42, thus achieving good sealing performance. Furthermore, adjacent V-shaped gaskets 14a-14c abut against each other at their thick-walled and highly rigid tops 16, reliably maintaining the gap between the inner skirt 18 and outer skirt 20 of adjacent V-shaped gaskets 14a-14c. Moreover, the inner skirt 18 and outer skirt 20 of adjacent V-shaped gaskets 14a-14c do not interfere with each other, preventing simultaneous wear of multiple V-shaped gaskets 14a-14c and ensuring long-term maintenance of good sealing performance.

[0047] According to the shaft seal structure 12 of this embodiment, there are multiple V-shaped gaskets 14a to 14c, which are composed of a thick-walled top 16, a thin-walled inner skirt 18, and a thin-walled outer skirt 20. Furthermore, the adjacent inner skirts 18 and outer skirts 20 do not interfere with each other, thus enabling good sealing performance to be maintained for a long time.

[0048] In this embodiment, although the V-shaped gaskets 14a to 14c are made of fluororesin, they can also be made of resins other than fluororesin, rubber, elastomers, etc., as long as the material has the specified elasticity. Furthermore, when the V-shaped gaskets 14a to 14c are made of fluororesin, the rubber auxiliary gasket 22 is useful for improving the sealing performance. For example, when the V-shaped gaskets 14a to 14c are made of rubber, the auxiliary gasket 22 may not be required. In describing the shaft seal structure 12 according to this embodiment, an example of an angle seat valve used for handling fluids such as liquids and vapors was used, but it can be applied to various devices (valves) that handle fluids such as compressed air.

[0049] (Second Implementation)

[0050] Next, refer to Figure 6 and Figure 7 The shaft seal structure 80 according to the second embodiment of the present invention will be described. Furthermore, the shaft seal structure 80 will be described as a component applied to the same angle seat valve 10 as in the first embodiment. Additionally, structures that are the same as or equivalent to the shaft seal structure 12 of the first embodiment will be marked with the same reference numerals, and detailed descriptions will be omitted.

[0051] The shaft seal structure 80 has multiple U-shaped gaskets 82a to 82c made of fluororesin. For example... Figure 7 As shown, the U-shaped gaskets 82a-82c with a U-shaped cross-section have: a thick-walled top 84, an inner skirt 86 with a thin wall extending inward and axially from the top 84, and an outer skirt 88 with a thin wall extending outward and axially from the top 84. Furthermore, "axial" here refers to a direction parallel to the central axis of the U-shaped gaskets 82a-82c, which coincides with the axis CL2 of the valve stem 32.

[0052] Multiple U-shaped gaskets 82a-82c are configured such that their respective tops 84 are located on the side away from the valve core 44 and are stacked in the direction of the axis CL2 of the valve stem 32. In this embodiment, as... Figure 6 As shown, there are a total of three U-shaped pads 82a to 82c, including a lower U-shaped pad 82a, a middle U-shaped pad 82b, and an upper U-shaped pad 82c, but the number of U-shaped pads is not limited to this.

[0053] The inner skirt 86 of the U-shaped gaskets 82a-82c has multiple annular ribs 86a protruding inward. The outer skirt 88 of the U-shaped gaskets 82a-82c has multiple annular ribs 88a protruding outward. The thin-walled inner skirt 86 and outer skirt 88 elastically deform under the pressure of the fluid in the inclined pipe section 42. Furthermore, the inner skirt 86 slides in contact with the outer surface of the valve stem 32 at the tips of the multiple ribs 86a. In addition, the outer skirt 88 abuts against the inner surface of the retainer 34 at the tips of the multiple ribs 88a. As a result, a specified surface pressure and contact area can be ensured at the contact points, thus achieving good sealing performance.

[0054] Furthermore, the end face 84a and the back face 84b of the top 84 of the U-shaped pads 82a-82c are both flat surfaces. The top 84 of adjacent U-shaped pads 82a-82c abut against each other in such a way that the end face 84a of one top 84 and the back face 84b of the other top 84 are pressed together between the flat surfaces. As a result, the central axis of the stacked U-shaped pads 82a-82c is stably kept in a consistent state.

[0055] Furthermore, the axial length of the top 84 of the U-shaped pads 82a-82c is longer than the distance from the back surface 84b of the top 84 to the top of the inner skirt 86 or the top of the outer skirt 88. In other words, the thickness T of the top 84 is greater than the depth D of the recess formed by the inner skirt 86 and the outer skirt 88. As a result, the inner skirt 86 and the outer skirt 88 of adjacent U-shaped pads 82a-82c do not interfere with each other.

[0056] When the angle seat valve 10 has been used for a certain period of time, the wear of the lower U-shaped gasket 82a intensifies, rendering it unable to fully perform its sealing function and thus ceasing its operation. Consequently, the middle U-shaped gasket 82b, under the pressure of the fluid within the inclined pipe section 42, begins to provide a seal. Furthermore, as the angle seat valve 10 continues to be used for a certain period, the wear of the middle U-shaped gasket 82b intensifies, causing the upper U-shaped gasket 82c to perform its sealing function. In this way, the sealing effect continues sequentially from the lower U-shaped gasket to the upper U-shaped gasket, and the wear of multiple U-shaped gaskets 82a to 82c does not occur simultaneously.

[0057] According to the shaft seal structure 80 of this embodiment, there are multiple U-shaped gaskets 82a to 82c, which are composed of a thick-walled top 84, a thin-walled inner skirt 86, and a thin-walled outer skirt 88. Furthermore, the adjacent inner skirts 86 and outer skirts 88 do not interfere with each other, thus enabling good sealing performance to be maintained for a long time.

[0058] In this embodiment, although the U-shaped pads 82a to 82c are made of fluororesin, the U-shaped pads can also be made of resins other than fluororesin, rubber, elastomers, etc., as long as the material has the specified elasticity.

[0059] (Example for reference)

[0060] Figure 8 A shaft seal structure 90 is shown as a reference example. This shaft seal structure 90 differs from the shaft seal structure 12 of the first embodiment in that it only has one V-shaped gasket. Furthermore, structures identical or equivalent to the shaft seal structure 12 of the first embodiment are labeled with the same reference numerals. The shaft seal structure 90 will be described below.

[0061] A first guide bushing 24 and a second guide bushing 26 are mounted on the inner circumference of the retainer 34. The first guide bushing 24 and the second guide bushing 26 guide the valve stem 32 to be axially movable. A pressing plate 28 is mounted at the lower end of the retainer 34. A scraper 30 and a single V-shaped gasket 14 are mounted between the pressing plate 28 and the first guide bushing 24. A rubber sealing gasket 22 is mounted between the first guide bushing 24 and the second guide bushing 26.

[0062] The V-shaped gasket 14 is made of fluoropolymers such as PTFE or PFA, exhibiting excellent chemical resistance, heat resistance, and vapor resistance. The V-shaped gasket 14, with a V-shaped cross-section, comprises: a top 16, an inner skirt 18 with a thin wall extending obliquely inward from the top 16, and an outer skirt 20 with a thin wall extending obliquely outward from the top 16. The top 16 has an annular protrusion 16a projecting towards the side opposite to the inner skirt 18 and the outer skirt 20. The inner skirt 18 of the V-shaped gasket 14 slides in contact with the outer surface of the valve stem 32 at its top inner periphery 18a. The outer skirt 20 of the V-shaped gasket 14 abuts against the inner surface of the retainer 34 at its top outer periphery 20a.

[0063] The rubber sealing gasket 22 is made of rubber such as NBR, HNBR, EPDM, FKM, or silicone, and has excellent sealing performance. The rubber sealing gasket 22, having a U-shaped cross-section, includes: an annular plate portion 22a, an inner cylindrical portion 22b extending from the inner periphery of the annular plate portion 22a, and an outer cylindrical portion 22c extending from the outer periphery of the annular plate portion 22a. The inner cylindrical portion 22b of the rubber sealing gasket 22 slides in contact with the outer surface of the valve stem 32 at its inner periphery. The outer cylindrical portion 22c of the rubber sealing gasket 22 abuts against the inner surface of the retainer 34 at its outer periphery.

[0064] The first guide bushing 24 is made of a super engineering plastic material with high mechanical strength, high sliding properties, heat resistance, and low wear. Specific examples of super engineering plastic materials include PPS, PVDF, PA, PC, PE, POM, PEI, PPO, PET, PTFE, PEEK, PAI, PI, and PBI. The first guide bushing 24 is engaged with a second stepped portion 34c on the inner periphery of the retainer 34. The first guide bushing 24 has a recess 24a for receiving a V-shaped gasket 14, and the bottom surface of the recess 24a abuts against the protrusion 16a of the V-shaped gasket 14. The first guide bushing 24 has a protrusion 24b that enters between the inner cylindrical portion 22b and the outer cylindrical portion 22c of the rubber sealing gasket 22.

[0065] The first guide bushing 24 has a plurality of first grease reservoirs 24c opening at the bottom surface of the recess 24a and an annular second grease reservoir 24d opening toward the rubber sealing gasket 22. The plurality of first grease reservoirs 24c are evenly arranged circumferentially. Grease stored in the plurality of first grease reservoirs 24c is supplied to the V-shaped gasket 14. Grease stored in the second grease reservoirs 24d is supplied to the rubber sealing gasket 22. The first guide bushing 24 is positioned above the V-shaped gasket 14 and is therefore protected from fluid by the V-shaped gasket 14, thereby improving durability.

[0066] The second guide bushing 26 is made of a super engineering plastic material with high mechanical strength, high sliding properties, heat resistance, and low wear. The second guide bushing 26 is engaged with the third step 34d on the inner circumference of the retainer 34. The lower end face of the second guide bushing 26 abuts against the annular plate portion 22a of the rubber sealing gasket 22. The second guide bushing 26 has a grease reservoir 26a on its inner circumferential surface opposite the valve stem 32. The valve stem 32 is supported for a sufficient length by the first guide bushing 24 and the second guide bushing 26, thus improving support stability.

[0067] The scraper 30 is made of a super engineering plastic material with heat resistance, steam resistance, chemical resistance, high mechanical strength, high sliding properties, and low wear. The scraper 30 prevents foreign matter such as sludge adhering to the fluid on the valve stem 32 from entering the interior of the shaft seal structure 90. The scraper 30 is positioned by the pressing plate 28. The upper end of the scraper 30 abuts against the back side 16b of the top 16 of the V-shaped gasket 14.

[0068] V-shaped gasket 14 is disposed between the first guide bushing 24 and the scraper 30. The top 16 of the V-shaped gasket 14 is sandwiched between the bottom surface of the recess 24a of the first guide bushing 24 and the upper end of the scraper 30. The inner skirt 18 and the outer skirt 20 of the V-shaped gasket 14 can deform freely within the space formed between the first guide bushing 24 and the scraper 30. The inner skirt 18 and the outer skirt 20 of the V-shaped gasket 14 are formed as thin walls, so they can easily undergo elastic deformation under fluid pressure, thereby achieving good sealing performance.

[0069] The shaft seal structure 90 has only one V-shaped gasket 14, and therefore its sealing continuity is slightly inferior to that of the aforementioned shaft seal structure 12, which has multiple V-shaped gaskets 14a to 14c. However, the structure including the first guide bushing 24 and the scraper 30 is just as useful as the shaft seal structure 12 described above, and is practical considering cost-effectiveness.

[0070] The present invention is not limited to the embodiments described above, and various structures can be adopted without departing from the spirit of the present invention.

Claims

1. A shaft seal structure disposed between a rod (32) and a cage (34), the rod being driven in a specified fluid to be movable in an axial direction, the cage receiving the rod, the shaft seal structure (12) having a plurality of stacked V-shaped gaskets (14a-14c), wherein, The plurality of V-shaped pads are each composed of a thick-walled annular top (16), a thin-walled inner skirt (18) extending obliquely inward from the top, and a thin-walled outer skirt (20) extending obliquely outward from the top. The inner skirt slides in contact with the outer surface of the rod at its top end, and the outer skirt abuts against the inner surface of the cage at its top end. The top of one adjacent V-shaped pad abuts against the top of another V-shaped pad. The inner skirts of one V-shaped pad and the inner skirts of the other V-shaped pad do not interfere with each other. The outer skirts of one adjacent V-shaped pad and the outer skirts of the other V-shaped pad do not interfere with each other. The shaft seal structure (12) further includes a first guide bushing (24) and a second guide bushing (26), which are mounted on the cage and guide the rod to be axially movable. The top has a protrusion (16a) that protrudes toward a side opposite to the inner skirt and the outer skirt. The first guide bushing (24) has a recess (24a) that receives the upper V-shaped gasket and abuts against the protrusion of the upper V-shaped gasket on the bottom surface of the recess. Its features are, An auxiliary gasket (22) is installed between the first guide bushing and the second guide bushing. The auxiliary pad (22) has a U-shaped cross section and has an annular plate portion (22a), an inner cylindrical portion (22b) extending from the inner periphery of the annular plate portion, and an outer cylindrical portion (22c) extending from the outer periphery of the annular plate portion. The inner cylindrical portion (22b) slides in contact with the outer surface of the rod, and the outer cylindrical portion abuts against the inner surface of the cage on its outer periphery. The first guide bushing has a protrusion (24b) that enters between the inner cylindrical portion and the outer cylindrical portion of the auxiliary pad.

2. The shaft seal structure according to claim 1, characterized in that, The V-shaped gasket is made of fluororesin, and the auxiliary gasket is made of rubber.

3. The shaft seal structure according to claim 1, characterized in that, A scraper (30) is installed between the pressing plate (28) mounted on the retainer and the first guide bushing, and a plurality of the V-shaped pads are installed between the pressing plate and the first guide bushing.

4. A shaft seal structure disposed between a rod (32) and a cage (34), the rod being driven in a specified fluid to be movable in an axial direction, the cage receiving the rod, the shaft seal structure (80) having a plurality of U-shaped gaskets (82a-82c) stacked in multiple layers, wherein, The plurality of U-shaped pads are each composed of a thick-walled annular top (84), an inner skirt (86) of thin walls extending inward and axially from the top, and an outer skirt (88) of thin walls extending outward and axially from the top. The top of one adjacent U-shaped pad abuts against the top of another U-shaped pad. The inner skirts of one U-shaped pad do not interfere with each other, and the outer skirts of one U-shaped pad do not interfere with each other. The shaft seal structure (80) further includes a first guide bushing (24) and a second guide bushing (26), which are mounted on the cage and guide the rod to be movable along the axial direction. The top end face (84a) and the back face (84b) are flat surfaces. The first guide bushing has a recess (24a) that receives the upper U-shaped gasket, and the bottom surface of the recess abuts against the flat surface of the end face of the upper U-shaped gasket. Its features are, The inner skirt has a rib (86a) that slides in contact with the outer surface of the rod, and the outer skirt has a rib (88a) that abuts against the inner surface of the cage. An auxiliary gasket (22) is installed between the first guide bushing and the second guide bushing. The auxiliary pad has a U-shaped cross section and has an annular plate portion (22a), an inner cylindrical portion (22b) extending from the inner periphery of the annular plate portion, and an outer cylindrical portion (22c) extending from the outer periphery of the annular plate portion. The inner cylindrical portion slides in contact with the outer surface of the rod, and the outer cylindrical portion abuts against the inner surface of the cage on its outer periphery. The first guide bushing has a protrusion (24b) that enters between the inner cylindrical portion and the outer cylindrical portion of the auxiliary pad.

5. The shaft seal structure according to claim 4, characterized in that, The thickness of the top is greater than the depth of the recess formed by the inner skirt and the outer skirt.

6. The shaft seal structure according to claim 4, characterized in that, The U-shaped gasket is made of fluororesin, and the auxiliary gasket is made of rubber.

7. The shaft seal structure according to claim 4, characterized in that, A scraper (30) is installed between the pressing plate (28) mounted on the retainer and the first guide bushing, and a plurality of the U-shaped pads are installed between the pressing plate and the first guide bushing.

8. A valve (10), characterized in that, The shaft seal structure described in claim 1 or 4 is adopted.

Images