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EP-3754239-B1 - MOUNTING STRUCTURE FOR MOUNTING VALVE PLATE TO VALVE ROD IN GATE VALVE, AND GATE VALVE HAVING MOUNTING STRUCTURE

EP3754239B1EP 3754239 B1EP3754239 B1EP 3754239B1EP-3754239-B1

Inventors

  • SHIMODA, HIROMI
  • OGAWA, HIROSHI
  • NAGAO, TAKASHI
  • OCHI, TSUYOSHI

Dates

Publication Date
20260513
Application Date
20200603

Claims (8)

  1. A mounting structure for mounting a valve plate onto a valve rod in a gate valve, the mounting structure including a valve plate (3) for opening and closing a gate opening (2) formed in a valve box (1) and a valve rod (2) connected to the valve plate (3), wherein the valve plate (3) includes a valve front surface (3a) to which a sealing member (7) for coming into contact with and being separated from a valve seat (1b) disposed around the gate opening (2) is attached, a valve rear surface (3b) positioned on a side opposite to the valve front surface (3a), a valve upper surface (3c), and a valve lower surface (3d), the valve plate (3) has a mounting hole (13) that is formed in the valve lower surface (3d) and into which a mounting portion (14) formed at the end of the valve rod (4) is to be inserted, the valve plate (3) has a screw insertion hole (16) that penetrates the valve plate (3) between the valve upper surface (3c) and the mounting hole (13) and through which a valve-plate fixation screw (20) is to be inserted, the valve plate (3) is attached to the valve rod (4) by the valve-plate fixation screw (20), the mounting hole (13) is defined by a front hole-wall surface (13a) positioned near the valve front surface (3a), a rear hole-wall surface (13b) positioned near the valve rear surface (3b), and a hole end surface (13d) that is a bottom surface of the mounting hole (13), the screw insertion hole (16) opens at the hole end surface (13d), the mounting portion (14) of the valve rod (4) has a rod front surface (14a) that opposes the front hole-wall surface (13a) of the mounting hole (13), a rod rear surface (14b) that opposes the rear hole-wall surface (13b) of the mounting hole (13), and a rod end surface (15) positioned at an end of the mounting portion (14), the rod end surface (15) has a threaded hole (17) formed so as to be screwed with the valve-plate fixation screw (20) to be inserted through the screw insertion hole (16) of the valve plate (3), characterized in that a spacer (30) is provided between the hole end surface (13d) of the mounting hole (13) and the rod end surface (15) of the mounting portion (14), in a state in which the mounting portion (14) of the valve rod (4) is inserted into the mounting hole (13) of the valve plate (3) until the rod end surface (15) abuts a lower surface of the spacer (30) and in a state in which the valve-plate fixation screw (20) is not screwed with the threaded hole (17), a horizontally elongated gap (G2) is formed between the hole end surface (13d) of the mounting hole (13) and an upper surface of the spacer (30), and the gap (G2) opens at a position closer to the rod front surface (14a) of the mounting portion (14) and closes at a position near the rod rear surface (14b) with respect to a central axis (L2) of the threaded hole (17), and by screwing the valve plate fixation screw (20) into the threaded hole (17), a counterclockwise moment (M) in a right side view when viewed from the valve front surface (3a) with the valve plate upper surface (3c) oriented upwards is generated in the valve plate (3) with the center being positioned behind the central axis (L2), said moment (M) slightly deforming the valve plate (3) so as to narrow the gap (G2), and as a result the front hole wall surface (13a) of the valve plate (3) is pressed against the rod front surface (14a) of the valve rod(4).
  2. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 1, wherein the gap (G2) is shaped like a wedge in such a manner that an opening width of the gap (G2) in the up-down direction is gradually narrowed from the rod front surface (14a) toward the rod rear surface (14b).
  3. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 1, wherein the spacer (30) has the upper surface (34) to abut the hole end surface (13d) and the lower surface (35) to abut the rod end surface (15) and also has a through hole (36a) that is formed between the upper surface (34) and the lower surface (35) and through which the valve-plate fixation screw (20) is inserted, the gap (G2) is formed between the upper surface (34) of the spacer (30) and the hole end surface (13d) of the mounting hole (13), and the gap (G2) opens at a position near the rod front surface (14a) of the mounting portion (14) and closes at a position closer to the rod rear surface (14b) with respect to the through hole (36a) when the upper surface (34) of the spacer (30) abuts the hole end surface (13d) of the mounting hole (13).
  4. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 3, wherein the upper surface (34) and the lower surface (35) of the spacer (30) are flat surfaces, the spacer (30) has a flat plate portion (36) between the upper surface (34) and the lower surface (35), a front edge (31) near the rod front surface (14a), and a rear edge (32) near the rod rear surface (14b), the flat plate portion (36) is shaped like a wedge in such a manner that a thickness between the upper surface (34) and the lower surface (35) gradually increases from the front edge (31) toward the rear edge (32), and the gap (G2) is shaped like a wedge in such a manner that the gap (G2) gradually becomes narrower from the front edge (31) toward the rear edge (32).
  5. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 4, wherein the spacer (30) has an engagement protrusion (37) formed at the rear edge (32) so as to protrude downward, the engagement protrusion (37) has a first surface (37a) extending downward from the rear edge (32) and a second surface (37b) extending downward from a rear end of the lower surface (35), the engagement protrusion (37) is shaped like a wedge in such a manner that a width of the engagement protrusion (37) in a front-rear direction gradually decreases toward a lower end thereof, the rod end surface (15) of the mounting portion (14) has an uninclined surface portion (15a) that extends from a front edge of the mounting portion (14) toward a rear edge thereof so as to orthogonally intersects the central axis (L2), and an inclined surface portion (15b) that extends from a rear end of the uninclined surface portion (15a) toward a base end of the mounting portion (14) and declines such that a width of the mounting portion (14) in the front-rear direction increases gradually, and in the state in which the valve-plate fixation screw (20) is screwed tightly with the threaded hole (17) and the valve plate (3) is thereby fixedly mounted on the mounting portion (14) of the valve rod (4), the engagement protrusion (37) of the spacer (30) is pressed in between the rear hole-wall surface (13b) of the mounting hole (13) and the inclined surface portion (15b) of the rod end surface (15), which causes the first surface (37a) of the engagement protrusion (37) to press the rear hole-wall surface (13b) and also causes the second surface (37b) of the engagement protrusion (37) to press the inclined surface portion (15b).
  6. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 5, wherein in the spacer (30), the first surface (37a) of the engagement protrusion (37) forms an acute angle with the upper surface (34) of the flat plate portion (36) and also forms a right angle with the lower surface (35) of the flat plate portion (36).
  7. The mounting structure for mounting the valve plate onto the valve rod in the gate valve according to Claim 3, wherein the valve-plate fixation screw h(20) as a screw body (21) to be screwed with the threaded hole (17) and a manipulation-purpose screw head (22) connected to a base end of the screw body (21), the screw body (21) has an external thread portion (21a) having a thread formed on a circumferential surface thereof and a column-like shaft (21b) formed closer to the base end of the screw body (21) with respect to the external thread portion (21a), the threaded hole (17) is formed of an internal thread section (17a) in which a thread to be screwed with the external thread portion (21a) is formed on an inner peripheral surface of the threaded hole (17) and also formed of a cylindrical section (17b) that has a circular cross section and is positioned closer to the rod end surface w(15) ith respect to the internal thread section (17a), a thread to be screwed with the external thread portion of the valve-plate fixation screw (20) is formed on an inner peripheral surface of the through hole (36a) of the spacer (30), and in a direction of the central axis (L2), a length (S1) of the external thread portion (21a) of the valve-plate fixation screw (20) is made shorter than a length (S3) of the cylindrical section (17b) of the threaded hole (17).
  8. A gate valve configured such that a valve plate (3) attached to an end of the valve rod (4) that extends in an up-down direction is accommodated in a valve box (1) and the valve plate (3) opens and closes a gate opening (2) formed in a side wall of the valve box (1), wherein the valve plate (3) is mounted on the valve rod (2) by using the mounting structure according to Claim 1.

Description

[Technical Field] The present invention relates to a mounting structure for mounting a valve plate onto an end of a valve rod in a gate valve and also relates to the gate valve having the mounting structure for mounting the valve plate. [Background Art] A gate valve is used in a microchip processing apparatus to open and close an opening that communicates with a vacuum chamber. The gate valve is configured such that a valve plate attached to an end of the valve rod is accommodated in a valve box mounted on a vacuum chamber and the valve plate opens and closes the opening formed in a side wall of the valve box. The opening is closed by pressing a sealing member attached to the valve plate against a valve seat formed around the opening. For example, a gate valve disclosed in JP 2005-291221 A is configured such that an upper wall is detachably mounted on a valve box and a valve plate is fixed with screws to the top end of a valve rod in the axial direction thereof. This enables the valve plate to be detached from the valve rod by operation outside the valve box, which facilitates gate valve maintenance. In the gate valve, the valve plate is attached to the valve rod so as to rotate about the axis of the valve rod. Accordingly, when the valve plate is pressed against the valve seat, the valve plate rotates so as to follow the valve seat, which enables a sealing face (sealing member) of the valve plate to press the valve seat evenly. Recent trend of miniaturization and higher integration of microchips accelerates the reduction in the line width of microchip. It is strongly demanded to reduce particle generation in microchip processing as much as possible to a level close to zero. The gate valve disclosed in JP 2005-291221 A, however, has a problem that the valve plate is rubbed against the valve rod or against the valve seat and particles tend to be generated when the gate valve is in operation. To suppress particle generation, it is necessary to fix the valve plate to the valve rod securely and accurately. A mounting structure for mounting the valve plate on the valve rod according to the preamble of claim 1 is known from US 2011/0108750 A1. This mounting uses a cross member extending transversely with respect to the valve rod. The cross member is connected at a central connecting point to the valve rod and is connected at least at two lateral connecting points, which are situated on both sides of the central connecting point, to the valve plate. The valve rod is inserted from below into a mounting hole provided in the cross member and is fixed therein by means of a connection screw screwed into a threaded drill hole. [Summary of Invention] [Technical Problem] In the present invention, a technical problem is to suppress particle generation during gate valve operation by fixing a valve plate to a valve rod reliably and accurately. [Solution to Problem] To solve the above problem, the present invention provides a mounting structure for mounting a valve plate onto a valve rod in a gate valve comprising the features of claim 1. The gate valve is configured such that the valve plate attached to an end of the valve rod that extends in an up-down direction is accommodated in a valve box and the valve plate opens and closes a gate opening formed in a side wall of the valve box. In the mounting structure, the valve plate includes a valve front surface to which a sealing member for coming into contact with and being separated from a valve seat disposed around the gate opening is attached, a valve rear surface positioned on a side opposite to the valve front surface, a valve upper surface, and a valve lower surface. The valve plate has a mounting hole that is formed in the valve lower surface and into which a mounting portion formed at the end of the valve rod is to be inserted. The valve plate also has a screw insertion hole that penetrates the valve plate between the valve upper surface and the mounting hole and through which a valve-plate fixation screw is to be inserted. In addition, the valve plate is attached to the valve rod by the valve-plate fixation screw. The mounting hole is defined by a front hole-wall surface positioned near the valve front surface, a rear hole-wall surface positioned near the valve rear surface, and a hole end surface that is a bottom surface of the mounting hole. The screw insertion hole opens at the hole end surface. The mounting portion of the valve rod has a rod front surface that opposes the front hole-wall surface of the mounting hole, a rod rear surface that opposes the rear hole-wall surface of the mounting hole, and a rod end surface positioned at an end of the mounting portion. The rod end surface has a threaded hole formed so as to be screwed with the valve-plate fixation screw to be inserted through the screw insertion hole of the valve plate. In a state in which the mounting portion of the valve rod is inserted into the mounting hole of the valve plate until the rod end surface