JP2010116926A - Molecular pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a protective wire net arranged in a suction port for checking the inflow of foreign matter from causing a contact accident with a rotor and a moving blade by buckling caused by the thermal expansion by a temperature gradient, in a molecular pump having a structure for arranging the suction port of exhaust gas in close vicinity to the rotor. <P>SOLUTION: A tip part of a wire element 6a of the long side of adjacent rectangles is crossed at a right angle in a T shape with a central part of the wire element 6a of the long side of the respective rectangles composed of a large number of rectangular meshes 6c, The protective wire net 6 having a zigzag mesh pattern is formed by alternately continuously connecting these rectangles. The protective wire net 6 is arranged in a suction port part 5a of a turbo-molecular pump 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molecular pump having a protective wire mesh installed at the inlet of a molecular pump such as a turbo molecular pump or a composite molecular pump that has a rotor that rotates at high speed and is used in a pressure range from medium vacuum to ultra-high vacuum. Concerning structure.

  A longitudinal sectional view of an example of a conventional complex molecular pump is shown in FIG.

  In FIG. 9, the composite molecular pump a is composed of a turbo molecular pump part b and a thread groove vacuum pump part c, where d is an inlet and e is an exhaust outlet.

  That is, the suction port d is connected to the exhausted device side, the rotor f rotates at high speed, the exhaust gas is sucked from the suction port d, and the exhaust gas is discharged from the exhaust port e.

  A protective wire g for preventing the inflow of foreign matter may be installed at the portion of the suction port d.

  This is to prevent foreign matter such as bolts, nuts and metal pieces from flying and colliding with the moving blade portion of the rotor b rotating at high speed, and damaging the moving blade portion and the rotor b.

  The conventional protective metal mesh g of this type has a mesh as shown in FIG. 10 having many square holes having a thickness of about 0.3 mm to 1 mm and a side length of about 1 mm to 5 mm.

  As a method for forming the mesh, there are a method using a plain weave of wires, a method in which a hole is formed in a metal plate by punching or etching, and the like, and it is formed in a flat plate shape.

  For example, Patent Document 1 and Patent Document 2 are examples of using such a protection wire mesh.

Japanese Patent Laid-Open No. 11-330087 (FIG. 2) Japanese Patent Laid-Open No. 11-247790 (FIG. 3)

  Recently, it is necessary to reduce the height of the molecular pump due to the demand for pump downsizing.

  For this reason, the suction port of the molecular pump is arranged close to the front end of the rotor, and the protective wire mesh is installed close to the front end of the rotor.

  Since the device to which the molecular pump is attached often performs a process at a high temperature, the protective metal mesh itself may become high temperature due to the inflow of high temperature gas or radiant heat.

  At this time, the heat transmitted to the protective wire mesh is not uniform, and a temperature gradient occurs in the protective wire mesh immediately after the start of the process, and due to the difference in thermal expansion due to this temperature gradient, local elongation occurs in the protective wire mesh, Since the protective wire mesh is released from this elongation when it is bent in the vertical direction, the protective wire mesh may be buckled. When the buckling of the protection wire mesh occurs downward, the contact between the protection wire mesh and the front end portion of the rotor is short because the distance between the protection wire mesh and the front end portion of the rotor is short. There was a problem that it might cause.

  Since the rotor rotates at a high speed, if a contact accident occurs even for a moment, the protection wire mesh is broken or the rotor is broken.

  An object of the present invention is to solve the above problems and to provide a molecular pump having a protective wire mesh having a structure that prevents a contact accident between the protective wire mesh and the rotor even if a temperature gradient occurs in the protective wire mesh itself. And

  In order to achieve the above-mentioned object, the present invention provides a molecular pump having a structure in which an exhaust suction port is arranged close to a rotor as a first invention, and has a rounded outer peripheral portion and a large number of small holes inside the flange portion. And forming a protective wire mesh having upward stress on the wire mesh portion by drawing the inner periphery of the collar portion by drawing, and the mesh portion protrudes upward due to expansion of the mesh portion. In the molecular pump having the structure in which the protective wire mesh is installed in the suction port portion of the molecular pump, and the exhaust suction port is arranged close to the rotor as a second invention. A protective wire mesh is formed by providing a plurality of punch holes in a composite plate in which a thin plate made of a metal having a low linear expansion coefficient is laminated and bonded to the lower surface of a thin plate made of a metal having a high linear expansion coefficient. Thermal expansion By being deformably formed in a convex shape upwards, characterized in that the protective wire net was placed in the suction port of the molecular pump.

  According to the present invention, the protective metal mesh installed at the suction port of the molecular pump does not bend or buckle and protrude toward the nearest rotor, thus preventing foreign matter from flowing into the rotor. In addition, the protective wire mesh and the rotor can be prevented from coming into contact with each other.

1 is a longitudinal sectional view of a turbo molecular pump of Example 1. FIG. It is a top view of the partial protection wire mesh of the said Example 1. FIG. It is explanatory drawing of an effect | action of the protection wire mesh of the said Example 1. FIG. It is a partial perspective view of the partial protection metal mesh of the turbo-molecular pump of Example 2. It is explanatory drawing of an effect | action of the protection wire mesh of the said Example 2. FIG. 6 is a plan view of a partially protective wire mesh of a turbo molecular pump of Example 3. FIG. FIG. 7 is a cross-sectional view taken along line AA in FIG. 6 of the protective wire mesh of Example 3. It is 1 part longitudinal cross-sectional view of the protection wire mesh of Example 4. It is a longitudinal cross-sectional view of an example of the conventional complex molecular pump. It is a top view of an example of the conventional protection wire mesh.

  Examples of the present invention are shown below.

  FIG. 1 is a longitudinal sectional view of a turbo molecular pump 1 according to an embodiment of the first invention. Reference numeral 4 denotes a rotor, and a large number of rotor blades 4 a are radially arranged in multiple stages on the outer periphery of the rotor 4.

  Reference numeral 5 denotes a casing, which has an exhaust suction port 5a at the upper end of the casing 5 and is connected to a device on the side where exhaust is performed at the suction port 5a.

  In the present embodiment, the suction port 5a is disposed close to the first stage moving blade 4a of the rotor 4 so that the total length of the molecular pump 1 is shortened.

  6 is a protective wire mesh, and the protective wire mesh 6 has a function of preventing foreign matter such as bolts, nuts, and metal pieces from jumping in and damaging the rotor 4 and the moving blade 4a. It is inserted and installed.

  In addition, 5b is an exhaust outlet and this exhaust outlet 5b is installed in the lower part of the said casing 5. FIG.

  A plan view showing the structure of the protective wire mesh 6 is shown in FIG.

  That is, the protective wire mesh 6 is formed by connecting rectangular meshes 6c composed of short wire elements 6a alternately vertically and horizontally to form a lightning-like mesh pattern, and the long side of the rectangle of each mesh 6c. In the central part, the front end part of the rectangular long side of the adjacent mesh 6c is orthogonal to the T-shape.

  The protective wire mesh 6 is locked by fitting the outer flange portion 6d into the suction port portion 5a.

  Next, the operation and effect of the protective metal mesh 6 of this embodiment will be described.

  The protective wire mesh 6 is provided at the suction port 5d of the turbo molecular pump 1 and serves to prevent foreign matter from jumping into the rotor 4 side.

  The protective wire mesh 6 has a short length of vertical and horizontal line elements 6a constituting the mesh 6c, so that the absolute amount of thermal expansion in each line element is small, and the elongation due to the thermal expansion crosses each line element 6a in a T-shape. The long side of the mesh can be deformed into a “<” shape as shown in FIG. 3 to escape, so that the protective metal mesh 6 as a whole hardly deforms in the vertical direction.

  In this way, the protective wire mesh 6 does not bulge out so as to come into contact with the rotor 4 or the moving blade 4a, which is safe.

  FIG. 4 is a perspective view of a part of the protective wire mesh 7 installed at the suction port of the turbo molecular pump according to the embodiment of the second invention.

  The complex molecular pump has the same structure as the complex molecular pump 1 except that a protective wire mesh 7 is used instead of the protective wire mesh 6 of the complex molecular pump 1 in Example 1.

  The protective wire mesh 7 has a structure comprising a rectangular mesh 7b formed by connecting plate-like surrounding walls 7a intersecting each other at a predetermined pitch and having a height 7a2 of the surrounding wall higher than the wall thickness 7a1 of the surrounding wall 7a. The outer peripheral portion was surrounded by a round rib portion 7c to form a circle.

  Since the protective mesh 7 has a structure having strong rigidity in the height direction of the mesh 7b, buckling in the height direction is unlikely to occur, and the expansion due to the thermal expansion of the surrounding wall 7a is caused by the surrounding wall 7a as shown in FIG. It can be deformed into a letter shape and escape.

  In this way, the protective wire mesh 7 of this embodiment does not bulge out so as to come into contact with the rotor 4 or the moving blade 4a, so that it is safe.

  An embodiment of the third invention will be described with reference to FIGS.

  FIG. 6 is a plan view of the protective wire mesh 8 of Example 3, and FIG. 7 shows a cross-sectional view of the protective wire mesh 8 taken along line AA.

  As shown in FIG. 7, the protective wire mesh 8 is formed by integrally forming the outer peripheral round edge portion 8a and the inner mesh portion 8b of the collar portion 8a by etching or the like, and then drawing the inner circumference 8c of the collar portion 8a. The mesh portion 8b is bent upwards to generate upward stress and bulge, and the central portion is formed in a shape swelled in an arc shape upwards.

  The protective wire mesh 8 can also be used in place of the protective wire mesh 6 of the turbo molecular pump 1 in the first embodiment.

  Since the mesh portion 8b of the protective wire mesh 8 is always stressed upward, the buckling caused by the difference in the amount of thermal expansion of the mesh portion 8b is urged by the upward stress and always protrudes upward. Will happen in the direction of.

  Thus, the protective wire mesh 8 is safe without approaching the rotor 4 or the moving blade 4a.

  An embodiment of the fourth invention will be described with reference to FIG.

  The protective wire mesh 9 of this embodiment is provided with a number of punch holes 9c in a composite plate in which a thin plate 9b made of a metal having a low linear expansion coefficient is laminated and bonded to the lower surface of a thin plate 9a made of a metal having a high linear expansion coefficient. Is formed.

The shape of the protective wire mesh 9 may have a square hole as shown in FIG.

  When the protective wire mesh 9 is used for the turbo molecular pump 1, the expansion due to heating always expands in a convex manner toward the upper surface side metal having a large linear expansion coefficient. Therefore, the protective wire mesh 9 is connected to the rotor 4 and the rotor blade 4a. It is safe without approaching.

  In addition, although the said Example showed the case of the turbo molecular pump, this may be a composite molecular pump.

  The present invention is effective for molecular pumps such as turbo molecular pumps and complex molecular pumps, particularly for molecular pumps having a structure in which an exhaust inlet is disposed close to the rotor because of the demand for downsizing.

1 Turbo molecular pump 4 Rotor 5a Suction port 6, 7, 8, 9 Protective wire mesh

Claims (2)

  In a molecular pump having a structure in which an exhaust suction port is arranged close to a rotor, it is composed of an outer peripheral round brim part and a mesh part having a large number of small holes inside the brim part. A protective wire mesh having upward stress is formed on the wire mesh portion by bending upwards by processing, and the mesh portion is formed to be deformable upward by expansion of the mesh portion, and the protective wire mesh is formed into the molecular pump. A molecular pump characterized in that it is installed at the suction port.   In a molecular pump with a structure in which an exhaust suction port is arranged close to the rotor, a number of punches are attached to a composite plate in which a thin plate made of a metal having a low linear expansion coefficient is laminated on the lower surface of a thin plate made of a metal having a high linear expansion coefficient. A protective wire mesh is formed by providing a hole, and the protective wire mesh is formed so as to be deformable upwardly by thermal expansion of the protective wire mesh, and the protective wire mesh is installed at the suction port portion of the molecular pump. Molecular pump to do.

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