Gate valve

Abstract

To provide a gate valve excellent in adhesiveness of a connection portion between a valve plate and a valve rod.SOLUTION: A connection metal fitting 17 is arranged on a top face of a valve plate 3 so as to stride over a facing portion between a hole front face 14a of a connection hole 14 and a shaft front face 15a of a connection shaft 15, and fixed on the connection shaft 15 with a connecting screw 18. A first adhering mechanism part 22 for making a first inclined face 23 and a second inclined face 24 abut on each other is formed in an abutting portion between the connection metal fixing 17 and the connection shaft 15, a second adhering mechanism part 25 for making a third inclined face 26 and a fourth inclined face 27 abut on each other is formed in an abutting portion between the connection metal fixing 17 and the valve plate 3, a third adhering mechanism part 28 for making a fifth inclined face 29 and a sixth inclined face 30 abut on each other is formed in an abutting portion between a lower end part of the valve plate 3 and a lower end part of the connection shaft 15, and the hole front face 14a of the connection hole 14 and the shaft front face 15a of the connection shaft 15 are entirely adhered to each other by pulling the valve plate 3 and the connection shaft 15 mutually at three upper and lower positions by the three adhering mechanism parts 22, 25 and 28.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a gate valve, and more particularly to a gate valve having improved adhesion at the connecting portion between a valve plate and a valve rod. [Background technology]

[0002] In semiconductor processing equipment, a gate valve is used to open and close a gate formed in a vacuum chamber. This gate valve is configured such that a valve plate attached to the tip of a valve rod is housed in a valve body, and the valve body is attached to a vacuum chamber, and an opening formed in the valve body so as to communicate with the gate is opened and closed by the valve plate. In this case, the opening is closed by pressing a seal member attached to the valve plate against a valve seat around the opening.

[0003] In the gate valve, the sealing member gradually deteriorates due to wear and cracks as it is used, and when it deteriorates, it must be replaced with a new sealing member. In such a case, the conventional gate valve must be removed from the vacuum chamber once, which requires a lot of time and effort to replace the sealing member. In addition, since semiconductor line widths are now becoming narrower and narrower, it is necessary to reduce particles generated during processing (the goal is zero particles), and therefore, how to eliminate friction between the various parts during gate valve operation is an important issue. In particular, if the valve plate and the valve rod are not in close contact at their connection, friction is likely to occur between them, so it is important to improve the contact between the valve plate and the valve rod.

[0004] In response to this, Patent Document 1 discloses a gate valve in which the adhesion of the connecting portion between the valve plate and the valve rod is improved. In this improved gate valve, a connecting plate attached to the upper surface of the valve plate and a valve plate mounting portion of a valve rod that fits into a mounting hole in the valve plate are formed with inclined surfaces that abut against each other, and inclined surfaces that abut against each other are also formed at the lower end of the valve plate and the lower end of the valve plate mounting portion, and the inclined surfaces are pressed against each other to bring the valve plate and the valve plate mounting portion into tight contact with each other by a wedge effect.

[0005] The improved gate valve has better adhesion between the valve plate and the valve plate mounting part than a general gate valve, but since the inclined surfaces for generating a wedge effect are formed at two diagonal positions on the valve plate mounting part, and the opposing surfaces of the valve plate and the valve plate mounting part are pressed against each other at these two positions, it may be difficult to achieve full and uniform adhesion between the opposing surfaces, and there is still room for improvement. In particular, in a gate valve of the type in which a heater is provided inside the valve rod and the valve plate is heated by this heater, it is necessary to maintain good heat transfer between the valve rod and the valve plate, so it is important to increase the adhesion between the valve rod and the valve plate as much as possible. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-225468 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a gate valve having improved adhesion at the connecting portion between the valve plate and the valve rod. [Means for solving the problem]

[0008] In order to achieve the above object, a gate valve of the present invention comprises a valve plate which opens and closes an opening of a valve body, and a valve rod connected to the valve plate, the valve plate having a valve front surface facing the opening, a valve rear surface opposite the valve front surface, a valve upper surface and a valve lower surface, and a connecting hole which penetrates the valve plate from top to bottom, the valve rod has a connecting shaft inserted into the connecting hole, the connecting hole having a hole front surface and a hole rear surface, the connecting shaft having a shaft front surface and a shaft rear surface, the hole front surface faces the shaft front surface and the hole rear surface faces the shaft rear surface, a connecting metal fitting which connects the valve plate and the valve rod is disposed on the upper surface of the valve plate, and the connecting metal fitting is disposed in a state of abutment against a part of the connecting shaft and a part of the valve plate by screwing a connecting screw through a screw insertion hole of the connecting metal fitting and into a screw hole at the tip of the connecting shaft. A first contact mechanism is formed at the portion where the connecting fitting contacts the connecting shaft, where a first inclined surface of the connecting fitting contacts the second inclined surface of the connecting shaft, and a second contact mechanism is formed at the portion where the connecting fitting contacts the valve plate, where a third inclined surface of the connecting fitting contacts the fourth inclined surface of the valve plate. When the connecting screw is tightened so that the first inclined surface is pressed against the second inclined surface and the third inclined surface is pressed against the fourth inclined surface, the first and second contact mechanisms generate a component force at the upper end of the connecting shaft and the upper end of the valve plate in a direction that brings the shaft front surface of the connecting shaft and the hole front surface of the connecting hole into close contact with each other. Further, a third contact mechanism is formed at a portion where the lower end of the valve plate contacts the protruding wall portion at the lower end of the shaft front surface of the connecting shaft, where a fifth inclined surface of the valve plate and a sixth inclined surface of the connecting shaft contact each other, and the third contact mechanism contacts the fifth inclined surface of the valve plate and a sixth inclined surface of the connecting shaft when the connecting screw is tightened to press the fifth inclined surface against the sixth inclined surface. The connecting hole A component force is generated in a direction that brings the front surface of the hole into close contact with the front surface of the connecting shaft.

[0009] In the present invention, the first adhesion mechanism and the second adhesion mechanism are located on opposite sides of a central axis passing through the center of the screw hole, and the inclination directions of the first inclined surface and the second inclined surface and the inclination directions of the third inclined surface and the fourth inclined surface are opposite to each other and gradually approach the central axis as they go upward. The inclination angles of the first and second inclined surfaces with respect to the central axis are smaller than the inclination angles of the third and fourth inclined surfaces with respect to the central axis.

[0010] In the present invention, the connecting fitting does not come into contact with the valve plate and the valve rod at any portion other than the first and second contact mechanisms. The connecting fitting is accommodated in a recess formed in the upper surface of the valve plate so as not to protrude above the upper surface of the valve plate.

[0011] In the present invention, the fourth inclined surface and the fifth inclined surface may be formed on a first auxiliary fitting and a second auxiliary fitting fixedly attached to the valve plate, and the second inclined surface may be formed on an axis auxiliary fitting fixed to the connecting shaft of the valve rod.

[0012] In the present invention, a heater hole may be formed inside the valve rod so as to extend to the inside of the connecting shaft, and a heater may be accommodated inside the heater hole. Effect of the Invention

[0013] According to the present invention, the hole front surface of the connecting hole in the valve plate and the axial front surface of the connecting shaft of the valve rod are pressed against each other at three locations above and below the valve plate and the connecting shaft by the first to third sealing mechanism parts whose inclined surfaces abut against each other, so that the hole front surface of the connecting hole and the axial front surface of the connecting shaft can be reliably sealed over the entire opposing surfaces. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a front view of a gate valve according to the present invention. [Diagram 2]FIG. 2 is an enlarged cross-sectional view in which a main part of FIG. 1 is broken away. [Diagram 3] FIG. 2 is a cross-sectional view showing the basic structure of the connection between the valve plate and the valve rod. [Figure 4] FIG. 2 is a perspective view of a first connecting structure that connects a valve plate and a valve rod. [Diagram 5] FIG. 5 is an exploded view of FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 4 is a plan view of the first auxiliary fitting. [Figure 14] FIG. 4 is a rear view of the first auxiliary fitting. [Figure 15] FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. [Figure 16] FIG. 4 is a plan view of a second auxiliary fitting. [Figure 17] FIG. 13 is a rear view of the second auxiliary fitting. [Figure 18] FIG. 17 is a cross-sectional view taken along line XVIII-XVIII in FIG. 16. [Figure 19] FIG. 11 is a perspective view of a second connecting structure that connects the valve plate and the valve rod. [Figure 20] FIG. 20 is an exploded view of FIG. 19. [Figure 21] FIG. 11 is a perspective view of a third connecting structure that connects the valve plate and the valve rod. [Figure 22] FIG. 22 is an exploded view of FIG. 21. [Diagram 23] FIG. 13 is a perspective view of a fourth connecting structure that connects the valve plate and the valve rod. [Figure 24]FIG. 24 is an exploded view of FIG. 23. [Diagram 25] FIG. 24 is a cross-sectional view of FIG. 23. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A gate valve according to the present invention is shown in Figures 1 and 2. This gate valve is used by being attached to a vacuum chamber (not shown), and comprises a valve box 1 having an opening 2 leading to the gate of the vacuum chamber, a valve plate 3 housed inside the valve box 1 and opening and closing the opening 2, a valve rod 4 connected to the valve plate 3, and an operating unit 5 that opens and closes the valve plate 3 via the valve rod 4. The operating unit 5 displaces the valve plate 3 between an open position where the opening 2 is fully opened, and a closed position where the opening 2 is closed.

[0016] The operating unit 5 has two air cylinders 6, 6 arranged parallel to each other on both the left and right sides of the valve rod 4, and these air cylinders 6, 6 open and close the valve plate 3 via the valve rod 4. However, since such a configuration and operation of the operating unit 5 is well known, a description thereof will be omitted here.

[0017] The valve box 1 is in the shape of a rectangular box that is elongated from side to side and has a front wall 1a and a rear wall 1b. The front wall 1a, which is connected to a vacuum chamber, is formed with the laterally elongated rectangular opening 2 and a planar valve sheet 2a surrounding the opening 2. The opening 2 is closed by pressing a seal member 7 attached to the valve front surface 3a of the valve plate 3 against the valve sheet 2a. A rear opening 8 larger than the opening 2 is also formed in the rear wall 1 b of the valve box 1 , but this rear opening 8 is not opened or closed by the valve plate 3 . In the following description, the front-rear direction, the up-down direction, and the left-right direction of the valve box 1 and the front-rear direction, the up-down direction, and the left-right direction of the other parts are the same directions.

[0018] A window 9 is formed on the upper surface of the valve box 1, and a lid 10 is detachably attached to this window 9 by a plurality of lid mounting screws 11. By removing the lid 10, the window 9 is opened so that the valve plate 3 can be removed from the valve rod 4 and taken out to the outside. However, it is also possible to install and remove the valve plate 3 through the rear opening 8 without providing the window 9 and lid 10 on the upper surface of the valve box 1.

[0019] As can be seen from Figures 2 and 4, the valve plate 3 has a horizontally elongated rectangular plate shape, and has a valve front surface 3a to which the seal member 7 is attached, a valve rear surface 3b on the opposite side of the valve front surface 3a, a valve upper surface 3c, and a valve lower surface 3d, and the valve front surface 3a and the valve rear surface 3b are planes parallel to each other. The valve plate 3 is connected to the upper end of the valve rod 4 so as to be detachable from above the valve plate 3. The connection between the valve plate 3 and the valve rod 4 will be described below, but before describing the first connection structure shown in Figures 4 to 18, the connection between the valve plate 3 and the valve rod 4 will be described in principle based on the basic structure shown in Figure 3.

[0020] As shown in FIG. 3, the valve plate 3 has a connecting hole 14 that penetrates the valve plate 3 from top to bottom, and the valve rod 4 has a connecting shaft 15 that fits into the connecting hole 14 at the tip of the cylindrical rod body 4a.

[0021] The connecting hole 14 has a cross-sectional shape of an elongated hole extending in the longitudinal direction (left-right direction) of the valve plate 3, and has a hole front surface 14a located on the valve front surface 3a side, a hole rear surface 14b located on the valve rear surface 3b side, and left and right hole side surfaces 14c, 14c (see FIG. 5). The hole front surface 14a and the hole rear surface 14b are flat surfaces parallel to each other, and the hole side surfaces 14c, 14c are concave surfaces having a circular arc shape.

[0022] On the other hand, the connecting shaft 15 has a shape as if the front and rear surfaces of a cylinder have been cut by two parallel planes, and has a shaft front surface 15a facing the hole front surface 14a of the connecting hole 14, a shaft rear surface 15b facing the hole rear surface 14b of the connecting hole 14, and left and right shaft side surfaces 15c, 15c (see FIG. 5) facing the left and right hole side surfaces 14c, 14c of the connecting hole 14. The shaft front surface 15a and shaft rear surface 15b are planes parallel to each other, and the left and right shaft side surfaces 15c, 15c are arc-shaped convex curved surfaces.

[0023] A connecting fitting 17 that connects the valve plate 3 and the valve rod 4 is disposed on the upper surfaces of the valve plate 3 and the connecting shaft 15. This connecting fitting 17 is disposed in a recess 16 formed in the upper surface of the valve plate 3 so as to straddle the opposing portion between the hole front surface 14a of the valve plate 3 and the shaft front surface 15a of the connecting shaft 15, and is fixed to the connecting shaft 15 by screwing a connecting screw 18 into a screw hole 20 formed in the upper end of the connecting shaft 15 through a screw insertion hole 19 formed in the connecting fitting 17. At this time, the front and rear ends of the connecting fitting 17 abut against parts of the valve plate 3 and the connecting shaft 15. The connecting fitting 17 is formed from a metal material that is not easily deformed when fastened by the connecting screw 18, and is disposed within the recess 16 so as not to protrude upward therefrom.

[0024] The inner diameter of the screw insertion hole 19 is large enough to allow the connecting screw 18 to be inserted therethrough with ease, so the connecting fitting 17 can be slightly displaced in a direction perpendicular to the connecting screw 18 when the connecting screw 18 is tightened. In addition, a seat bore 19a is formed at the upper end of the screw insertion hole 19, and the head 18a of the connecting screw 18 is accommodated within this seat bore 19a so as not to protrude significantly upward from the connecting fitting 17. The portion marked with the symbol 21 in the figure is an exhaust hole, which is a hole for allowing the air inside the screw hole 20 to escape into the gap G1 between the hole rear surface 14b and the shaft rear surface 15b when the connecting screw 18 is screwed into the screw hole 20.

[0025] A first inclined surface 23 is formed at the portion where the rear end of the connecting fitting 17 abuts against the connecting shaft 15, and this first inclined surface 23 abuts against a second inclined surface 24 formed on the upper end of the rear axial surface 15b of the connecting shaft 15, and these first inclined surface 23 and second inclined surface 24 form a first adhesion mechanism portion 22.

[0026] In addition, a third inclined surface 26 is formed at the portion where the front end of the connecting fitting 17 abuts against the valve plate 3, and this third inclined surface 26 abuts against a fourth inclined surface 27 formed at a position closer to the valve front surface 3a than the hole front surface 14a at the upper end of the valve plate 3, and these third inclined surface 26 and fourth inclined surface 27 form a second sealing mechanism part 25.

[0027] Furthermore, a fifth inclined surface 29 is formed at the lower end of the valve front surface 3a of the valve plate 3, and this fifth inclined surface 29 abuts against a sixth inclined surface 30 of a protruding wall portion 31 formed at the lower end of the shaft front surface 15a of the connecting shaft 15, and the fifth inclined surface 29 and the sixth inclined surface 30 form a third sealing mechanism portion 28.

[0028] The first inclined surface 23 and the second inclined surface 24 of the first contact mechanism 22 are inclined in a direction gradually approaching the central axis L passing through the center of the screw hole 20 as they go upward, and the third inclined surface 26 and the fourth inclined surface 27 of the second contact mechanism 25 are also inclined in a direction gradually approaching the central axis L as they go upward. In this case, since the first contact mechanism 22 and the second contact mechanism 25 are located on opposite sides to each other with respect to the central axis L, the inclination direction of the first inclined surface 23 and the second inclined surface 24 and the inclination direction of the third inclined surface 26 and the fourth inclined surface 27 are opposite to each other.

[0029] On the other hand, the fifth inclined surface 29 and the sixth inclined surface 30 of the third adhesion mechanism 28 are gradually inclined in a direction away from the central axis L as they proceed upward, and the inclination direction is opposite to the inclination direction of the third inclined surface 26 and the fourth inclined surface 27 of the second adhesion mechanism 25.

[0030] Further, the inclination angle α of the first inclined surface 23 and the second inclined surface 24 with respect to the central axis L is smaller than the inclination angle β of the third inclined surface 26 and the fourth inclined surface 27 with respect to the central axis L. However, the two inclined surfaces may have the same angle, or the inclination angle α may be larger than the inclination angle β. Furthermore, the second contact mechanism 25 is disposed on the upper surface side of the valve plate 3 relative to the first contact mechanism 22, but the two may be located at the same vertical position.

[0031] In this way, the first contact mechanism 22 and the second contact mechanism 25 are formed at the portions where the connecting fitting 17 abuts against the upper end of the valve plate 3 and the upper end of the connecting shaft 15, respectively, and the third contact mechanism 28 is formed at the portion where the lower end of the valve plate 3 abuts against the lower end of the connecting shaft 15. Therefore, when the connecting screw 18 is tightened, in the first contact mechanism 22, the first inclined surface 23 is strongly pressed against the second inclined surface 24, so that a component force acts on the connecting shaft 15 via the second inclined surface 24 in a direction pressing the shaft front surface 15a against the hole front surface 14a, and in the second contact mechanism 25, the third inclined surface 26 is strongly pressed against the fourth inclined surface 27, so that a component force acts on the valve plate 3 via the fourth inclined surface 27 in a direction pressing the hole front surface 14a against the shaft front surface 15a. Therefore, the valve plate 3 and the connecting shaft 15 are attracted to each other by the connecting fitting 17 in a direction in which the shaft front surface 15a and the hole front surface 14a come into close contact with each other.

[0032] On the other hand, at the lower end side of the valve plate 3, in the third sealing mechanism portion 28, the valve plate 3 is pressed downward by the connecting fitting 17 and the lower end of the valve plate 3 is pressed against the protruding wall portion 31, so that the fifth inclined surface 29 is strongly pressed against the sixth inclined surface 30, and a component force in a direction pressing the hole front surface 14a against the shaft front surface 15a acts on the lower part of the valve plate 3 via the fifth inclined surface 29, and this component force causes the lower portion of the hole front surface 14a to be sealed against the lower portion of the shaft front surface 15a.

[0033] As a result, the hole front surface 14a of the connecting hole 14 of the valve plate 3 and the shaft front surface 15a of the connecting shaft 15 come into even close contact over the entire surfaces that face each other. On the other hand, the hole rear surface 14b of the connecting hole 14 and the shaft rear surface 15b of the connecting shaft 15 are not in contact with each other, and the gap G1 is formed therebetween.

[0034] At this time, as described above, the connecting fitting 17 does not come into contact with the valve plate 3 or the valve rod 4, except that its rear end abuts against the connecting shaft 15 in the first contact mechanism part 22 and its front end abuts against the valve plate 3 in the second contact mechanism part 25, and is fixed to the connecting shaft 15 while maintaining a gap G2 between itself and the upper surface of the connecting shaft 15. The connecting screw 18 and the screw hole 20 may each be provided one on the central axis L, or as shown in FIG. 4, two of them may be provided at positions facing each other across the central axis L.

[0035] Next, a first connecting structure for connecting the valve plate 3 and the valve rod 4 will be described with reference to Figures 4 to 18. This first connecting structure is a connecting structure in which a heater 34 is built into the valve rod 4 as shown in Figure 9, and enhances the adhesion between the valve plate 3 and the valve rod 4 based on the same principle as the basic structure shown in Figure 3.

[0036] The heater 34 is a cartridge heater that is housed inside a heater hole 35 that penetrates the center of the valve rod 4, and the upper end of the heater 34 extends to the inside of the connecting shaft 15. A thermocouple is disposed at the upper end of the heater 34 as a sensor 36, and the temperature is detected by a temperature detection portion at the tip of the thermocouple. The sensor 36 is housed inside a sensor cover 36a made of aluminum, which has excellent heat conductivity, and the upper end of the heater hole 35 is covered with a lid 35a made of stainless steel, which has excellent strength. The lid 35a is welded to the mounting shaft 15, which is also made of stainless steel. However, the sensor cover 36a and the lid 35a may be integrally formed from stainless steel and welded to the mounting shaft 15.

[0037] The main difference between the first connecting structure and the basic structure is that the fourth inclined surface 27 of the second contact mechanism part 25 and the fifth inclined surface 29 of the third contact mechanism part 28 are not formed directly on the valve plate 3, but are formed on the first auxiliary fitting 37 and the second auxiliary fitting 38 fixedly attached to the valve plate 3, and points related to the configuration for providing these first auxiliary fitting 37 and second auxiliary fitting 38; the other configurations and functions are generally similar to those of the basic structure.

[0038] Therefore, in the following description, the same symbols as those used in the basic structure may be used for parts of the first connecting structure that have the same configuration and function as those in the basic structure, and the symbols used in the basic structure may be used for parts that have the same configuration as those in the basic structure, and their descriptions may be omitted.

[0039] As shown in Figures 4 to 9, the recess 16 formed in the valve upper surface 3c of the valve plate 3 is open to the outside at the valve rear surface 3b side of the valve plate 3 and closed at the valve front surface 3a side of the valve plate 3, and has a first recess 16a extending in the front-rear and left-right directions across the connecting hole 14, and a second recess 16b formed between the connecting hole 14 and the valve rear surface 3b. The left-right length of the second recess 16b is approximately the same as the left-right length of the connecting hole 14, and the depth of the second recess 16b from the valve upper surface 3c is greater than the depth of the first recess 16a from the valve upper surface 3c. In addition, the first recess 16a is formed with metal fitting locking holes 39, 39 each having a rectangular shape in a plan view at a position near the valve front surface 3a on both the left and right outer sides of the connecting hole 14.

[0040] The connecting fitting 17 is accommodated in the recess 16 via the first auxiliary fitting 37, and two connecting screws 18, 18 are screwed into two screw holes 20, 20 formed on the upper surface of the connecting shaft 15 of the valve rod 4 through the two screw insertion holes 19, 19 formed in the connecting fitting 17 and the two screw insertion holes 40, 40 formed in the first auxiliary fitting 37, thereby positioning the first auxiliary fitting 37 in a substantially fixed state relative to the valve plate 3, and the connecting fitting 17 is attached to the upper end of the connecting shaft 15 with partial abutment against the connecting shaft 15 and the first auxiliary fitting 37 from above the first auxiliary fitting 37.

[0041] 10 to 12, the connecting fitting 17 has a plate-shaped main body 17a having a rectangular shape in a plan view, a rear wall 17b extending downward from the rear end center of the main body 17a, and a front wall 17c extending downward from the front surface of the main body 17a. A first inclined surface 23 of the first contact mechanism 22 is formed at the front lower end of the rear wall 17b, and a third inclined surface 26 of the second contact mechanism 25 is formed at the rear surface of the front wall 17c. As shown in FIG. 8, the first inclined surface 23 abuts against a second inclined surface 24 formed at the upper end of the shaft rear surface 15b of the connecting shaft 15, and the third inclined surface 26 abuts against a fourth inclined surface 27 formed on the first auxiliary fitting 37.

[0042] On the other hand, the first auxiliary fitting 37 is a fitting for forming the fourth inclined surface 27 of the second sealing mechanism portion 25, and as shown in Figures 13-15, has a plate-shaped main body portion 37a having a rectangular shape in a plan view, and two locking protrusions 37b, 37b formed at positions near both the left and right ends of the underside of the main body portion 37a, and is arranged in a substantially fixed state relative to the valve plate 3 by fitting and locking the locking protrusions 37b, 37b into the fitting locking holes 39, 39 of the valve plate 3.

[0043] However, since the screw insertion hole 40 formed in the first auxiliary fitting 37 has the same diameter as or slightly larger than the screw insertion hole 19 formed in the connecting fitting 17, the first auxiliary fitting 37 can be slightly displaced relative to the connecting fitting 17 in the forward / backward direction of the valve plate 3 when the connecting screw 18 is tightened.

[0044] The left-right length of the first auxiliary fitting 37 is slightly shorter than the left-right length of the first recess 16a, and the front-rear length of the first auxiliary fitting 37 is such that the rear end of the first auxiliary fitting 37 extends to the shaft rear surface 15b side beyond the screw hole 20. Inclined surfaces are formed on the front and rear surfaces of the main body portion 37a, and the inclined surface formed on the front surface is the fourth inclined surface 27.

[0045] Here, since the first auxiliary fitting 37 is fixedly disposed relative to the valve plate 3 and thereby forms part of the valve plate 3, it can be said that the fourth inclined surface 27 is formed on part of the valve plate 3. For this reason, in the present invention, the fourth inclined surface 27 is treated as being formed on the valve plate 3 both when it is directly formed on the valve plate 3 and when it is indirectly formed on the valve plate 3 via the first auxiliary fitting 37. This concept is similar to other inclined surfaces, and in particular is similar to the fifth inclined surface 29 described below and the second inclined surface 24 in Figure 25.

[0046] The second auxiliary fitting 38 is fixed to the center of the lower end of the valve front surface 3a of the valve plate 3 by a plurality of fitting fixing screws 41, and the fifth inclined surface 29 of the third sealing mechanism part 28 is formed on this second auxiliary fitting 38, and this fifth inclined surface 29 abuts against the sixth inclined surface 30 of the connecting shaft 15.

[0047] As shown in Figures 16-18, the second auxiliary fitting 38 has a main body portion 38a which is rectangular in plan view, a locking wall 38b which protrudes upward from the front end of the main body portion 38a, and abutment wall 38c which protrudes downward from the main body portion 38a, and screw insertion holes 38d for inserting the fitting fixing screws 41 are formed at both left and right ends of the main body portion 38a. The engaging wall 38b is formed over the entire length of the main body portion 38a and is engaged with the lower end portion of the valve plate 3, and the abutment wall 38c is partially formed in the central portion of the longitudinal direction (left-right direction) of the main body portion 38a, and the left-right length of the abutment wall 38c is slightly longer than the left-right length of the protruding wall portion 31 on the valve rod 4, and the fifth inclined surface 29 is formed on this abutment wall 38c.

[0048] Since the first connecting structure is configured as described above, similarly to the basic structure, when the connecting screw 18 is tightened, the first contact mechanism 22, the second contact mechanism 25 and the third contact mechanism 28 cooperate to connect the valve plate 3 and the valve rod 4 in a state where the hole front surface 14a of the connecting hole 14 and the shaft front surface 15a of the connecting shaft 15 are in full contact with each other. As a result, heat from the heater 34 is efficiently transferred from the valve rod 4 to the valve plate 3.

[0049] 19 and 20 show a second connecting structure that connects the valve plate 3 and the valve rod 4. The main differences between this second connecting structure and the first connecting structure are that the first auxiliary fitting 37 is fixed to the valve plate 3 with two fitting fixing screws 45, 45, that the second inclined surface 24 at the upper end of the connecting shaft 15 is divided into two left and right surface portions 24a, 24a, and that the first inclined surface 23 of the connecting fitting 17 is also divided into two left and right surface portions 23a, 23a. Other configurations and functions are substantially the same as those of the first connecting structure.

[0050] Therefore, the main differences between the second connecting structure and the first connecting structure will be described below. As shown in Figures 19 and 20, the valve plate 3 has metal fitting screw holes 46, 46 at positions on both the left and right outer sides of the connecting hole 14 in the recess 16, and the first auxiliary fitting 37 has screw insertion holes 47, 47 at positions near both left and right ends thereof, and the first auxiliary fitting 37 is fixed to the valve plate 3 by screwing metal fitting fixing screws 45, 45 inserted into the screw insertion holes 47, 47 into the metal fitting screw holes 46, 46.

[0051] The connecting fitting 17 has a left-right length substantially equal to that of the connecting shaft 15, and has two left and right rear wall portions 17b, 17b at its rear end, and two surface portions 23a, 23a constituting the first inclined surface 23 are formed at the front lower end of the rear wall portions 17b, 17b. The connecting fitting 17 is fixed to the connecting shaft 15 via the first auxiliary fitting 37 by screwing the connecting screws 18, 18 through the screw insertion holes 19, 19 and the screw insertion holes 40, 40 of the first auxiliary fitting 37 into the screw holes 20, 20 at the upper end of the connecting shaft 15 of the valve rod 4, and the two surface portions 23a, 23a constituting the first inclined surface 23 of the connecting fitting 17 abut against the two surface portions 24a, 24a constituting the second inclined surface 24 of the connecting shaft 15, respectively.

[0052] 21 and 22 show a third connecting structure that connects the valve plate 3 and the valve rod 4. The main differences between this third connecting structure and the second connecting structure are that the two surface portions 24a, 24a constituting the second inclined surface 24 at the upper end of the connecting shaft 15 of the valve rod 4 protrude upward from the portion where the screw holes 20, 20 and the heater hole 35 are formed, and that the rear wall portion 17b of the connecting fitting 17 is formed continuously over the entire left-right direction (length direction) of the main body portion 17a, and its height is lower than the height of the rear wall portion 17b of the connecting fitting 17 in the second connecting structure. Other configurations and functions of the third connecting structure are substantially the same as those of the second connecting structure.

[0053] 23, 24 and 25 show a fourth connecting structure that connects the valve plate 3 and the valve rod 4. The main difference between this fourth connecting structure and the third connecting structure is that the second inclined surface 24 at the upper end of the connecting shaft 15 of the valve rod 4 is formed as one surface on the shaft auxiliary fitting 50 fixedly disposed at the upper end of the connecting shaft 15, and other configurations and functions are substantially the same as those of the third connecting structure.

[0054] The shaft auxiliary fitting 50 has a plate-like main body 50a having a rectangular shape in a plan view, and an abutment wall 50b rising from the rear end of the main body 50a. The main body 50a is formed with two screw insertion holes 51, 51 through which the two connecting screws 18, 18 are inserted, a locking edge 50c that locks with the upper end of the shaft rear surface 15b of the connecting shaft 15 is formed on the lower surface of the abutment wall 50b, and the second inclined surface 24 is formed on the upper end of the abutment wall 50b. The shaft auxiliary fitting 50 is positioned below the first auxiliary fitting 37 and is fixed to the upper end of the connecting shaft 15 by the connecting screws 18, 18, and the first inclined surface 23 of the connecting fitting 17 abuts against the second inclined surface 24.

[0055] In the basic structure shown in FIG. 3, a heater is not housed inside the valve rod 4, but a heater can also be housed inside the valve rod 4, similar to the first to fourth connecting structures. In addition, the first, second, third and fourth connection structures can also be applied to a case where a heater is not built into the valve rod 4 as in the basic structure. [Explanation of symbols]

[0056] 1 Valve box 2 aperture 3 Valve plate 3a Valve front 3b Posterior valve surface 3c Valve top 3d valve bottom surface 14 Connection hole 14a Hole front 14b Posterior side of foramen 15 Connecting shaft 15a Axis front 15b rear shaft 16 Recess 17 Connecting fittings 18 Connecting screw 19 Screw insertion hole 20 Screw hole 22 First Adhesion Mechanism Section 23 1st slope 24 Second slope 25 Second Adhesion Mechanism Section 26 Third slope 27 4th slope 28 Third Adhesion Mechanism Section 29 5th slope 30 6th slope 34 Heater 35 Heater hole 37 First auxiliary fitting 38 Second Auxiliary Fitting 50 Axis auxiliary bracket L center axis α,β Tilt angle

Claims

1. The valve includes a valve plate that opens and closes an opening of the valve body, and a valve rod that is connected to the valve plate. the valve plate has a valve front surface facing the opening side, a valve rear surface opposite to the valve front surface, a valve upper surface and a valve lower surface, and a connecting hole vertically penetrating the valve plate, the valve rod has a connecting shaft inserted into the connecting hole, the connecting hole has a hole front surface and a hole rear surface, the connecting shaft has a shaft front surface and a shaft rear surface, the hole front surface and the shaft front surface face each other, and the hole rear surface and the shaft rear surface face each other, A connecting metal fitting is disposed on an upper surface of the valve plate for connecting the valve plate and the valve rod, and the connecting metal fitting is disposed in contact with a part of the connecting shaft and a part of the valve plate by screwing a connecting screw into a screw hole at the tip of the connecting shaft through a screw insertion hole of the connecting metal fitting, a first contact mechanism is formed at a portion where the connecting fitting contacts the connecting shaft, where a first inclined surface of the connecting fitting contacts a second inclined surface of the connecting shaft; and a second contact mechanism is formed at a portion where the connecting fitting contacts the valve plate, where a third inclined surface of the connecting fitting contacts a fourth inclined surface of the valve plate; when the connecting screw is tightened so that the first inclined surface is pressed against the second inclined surface and the third inclined surface is pressed against the fourth inclined surface, the first and second contact mechanisms generate a component force at an upper end of the connecting shaft and an upper end of the valve plate in a direction that brings a shaft front surface of the connecting shaft and a hole front surface of the connecting hole into close contact with each other, a third contact mechanism is formed at a portion where the lower end of the valve plate contacts the protruding wall portion at the lower end of the shaft front surface of the connecting shaft, where a fifth inclined surface of the valve plate and a sixth inclined surface of the connecting shaft contact each other; the third contact mechanism generates, at a lower end of the valve plate, a component force in a direction that brings a hole front surface of the connecting hole into contact with a shaft front surface of the connecting shaft when the fifth inclined surface is pressed against the sixth inclined surface by tightening the connecting screw. A gate valve characterized by:

2. The gate valve described in claim 1, characterized in that the first and second contact mechanisms are located on opposite sides of a central axis passing through the center of the screw hole, and the inclination directions of the first and second inclined surfaces and the inclination directions of the third and fourth inclined surfaces are opposite to each other and gradually approach the central axis as they go upward.

3. 3. The gate valve according to claim 1, wherein the connecting fitting does not contact the valve plate and the valve rod at any portion other than the first contact mechanism portion and the second contact mechanism portion.

4. 4. The gate valve according to claim 1, wherein the connecting fitting is accommodated in a recess formed in an upper surface of the valve plate so as not to protrude above the upper surface of the valve plate.

5. 5. The gate valve according to claim 1, wherein the fourth inclined surface and the fifth inclined surface are formed on a first auxiliary fitting and a second auxiliary fitting fixedly attached to the valve plate.

6. 6. The gate valve according to claim 1, wherein the second inclined surface is formed on a shaft auxiliary fitting fixed to a connecting shaft of the valve rod.

7. 7. The gate valve according to claim 1, wherein a heater hole is formed inside the valve rod so as to extend to the inside of the connecting shaft, and a heater is housed inside the heater hole.

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