JP2007516372A - Rotor blade for turbomolecular pump - Google Patents

Abstract

  The rotor blade for a turbomolecular pump of the present invention has a hub and a plurality of blades attached to the hub. The blade is formed from a strip of polymer material reinforced with fibers or particles.

Description

  The present invention relates to a rotor blade for a turbomolecular pump, and relates to a pump that is usually used to create a vacuum environment in semiconductor manufacturing.

  Standard turbomolecular pumps have rotor blades that are arranged at high speeds, for example, blades that are normally angled to rotate 60,000 revolutions per minute, alternately between rows of stationary blades in the stator. ing. In general, the blades of the statuser are inclined in a direction facing the rotor blades.

In a turbomolecular pump, gas is typically taken from a high vacuum chamber, compressed and passed to a backing pump, such as a multistage rotary pump. This backing pump is required when turbomolecular pumps operate at exhaust pressures up to about 10 ^-1 mbar, and by using a backing pump, the exhaust pressure in this region is increased and driven by the pump. Gas is released into the atmosphere.

  The pumping capacity of the turbomolecular pump is highly dependent on the rotational speed of the blade. This speed is limited by the allowable stress in the blade material of the rotor blade. Usually, the hub and blade of a rotor blade for a turbomolecular pump are machined from a single piece of lightweight metal, such as aluminum or an alloy thereof.

  The present invention provides a material and a manufacturing method of a rotor blade for a turbomolecular pump.

  The present invention provides a turbomolecular pump rotor blade having a hub, a plurality of blades made of reinforced polymer material, and means for attaching the blade to the hub.

  The use of a reinforced polymer material instead of the metal material conventionally used for rotor blades provides several advantages. The first advantage is that the ratio of strength to weight is superior to the weight reduction of the blade and the blade made of metal. From this point of view, high speed rotation is achieved, thus improving pump performance. A second advantage is that reinforced polymer material rotors have reduced rotational inertia compared to rotor blades having metal blades. This increases the safety of the environment around the pump during use when less energy on the rotor blades is applied to the pump's stator.

  In a preferred embodiment, the polymeric material is reinforced with either fibers or particles. Preferably, these fibers or particles are aligned in direction and provide maximum strength in the highest load area and / or direction on the blade during use of the rotor blades. For example, the majority of the fibers or particles, for example 75% -85% of the fibers or particles, are aligned from the root of the blade to the tip.

  The polymer material is reinforced with fibers or particles formed from carbon fibers, glass or ceramic materials, synthetic fibers such as para-amid fibers, Kevlar® fibers. The polymeric material may be a matrix, an epoxy, for example a polyetheretherketone.

  The blade takes the form of a strip of reinforced polymer material that is attached to the hub of the rotor blade by, for example, pins. These strips can be attached to the hub using a variety of techniques.

  In one technique, the strip is bent to provide a pair of rotor blades, where the bend of the strip is placed around a retaining pin that is attached to the hub. As an option, the strip (before bending) has two equally sized and parallel aligned end portions that are joined by a central portion, the central portion being the two end portions. Inclined with respect to the section to provide a dog-leg bend for the strip. In this configuration, the strip is bent along the central portion to provide a pair of rotor blades.

  In another embodiment of the invention, each blade is formed from a strip and the attachment means is located at or in one direction of the strip. Various attachment means will be apparent to those skilled in the art. One general example is described below.

  In one embodiment of the invention, the pin passes through a hole formed at one end of the strip. This end of the strip is thickened or reinforced in the area surrounding the hole. For example, each blade has a pair of reinforcing plates that sandwich one end of the strip, and pins pass through holes formed in the plates. These holes are machined, for example, at an acute angle with respect to the normal of the blade surface. This angle corresponds to an angle at which the blade is preferably inclined with respect to the rotating surface of the rotor blade. Thus, when the pin is inserted in a direction perpendicular to the plane of rotation of the hub, the blade is positioned at an angle relative to that plane.

  By arranging a plurality of blades in the same blade row with one locking pin, a more compact rotor design is possible. Alternatively or additionally, the pin may secure a plurality of blades in different rows to the hub.

  In another embodiment, the end of each blade may be configured to have a dovetail shape or similar shape. The dovetail shape is preferably configured to fit snugly within a similarly shaped slot in the hub. The dovetail shape may be formed by stacking layers of blade material. Alternatively, dovetail shapes of different materials may be coupled to the blade. If the tail shape of the dove is formed from another material, this other material may be bonded or fixed to the end of the blade.

  Alternatively, a generally flat blade may be coupled or secured in a slot that is pre-machined in the hub.

  Any of the blades described above may further include a coating layer (eg, metal) selected to not react with chemicals passing through the pump in use.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1-7 illustrate various techniques for providing a rotor blade having a blade formed from a polymer material reinforced with fibers or particles attached to the hub of the rotor blade. In the embodiment shown here, each blade is formed from a strip of reinforced polymer material attached to a hub.

  In this strip, the majority of the blade particles or continuous fibers are aligned in direction along the line from the root to the tip of each of the two blades. This causes a tensile load in the fiber alignment direction. As a result, the fiber safely holds this tensile load at the required operating speed of the turbomolecular pump.

  FIG. 1 shows a strip 10 of reinforced polymeric material material with fibers or particles used to form adjacent blades 12, 14 of a turbomolecular pump rotor blade. In this embodiment, the rectangular strip 10 is folded along dotted line 16 (FIG. 1a), thereby forming a U-shaped blade pair configuration 18 (FIG. 1b).

  FIG. 2 shows an embodiment similar to FIG. In this embodiment, the strip 20 is not rectangular but has a dock leg bend 22 at the center. Similar to the first embodiment, the strip 20 is bent across the dock leg bend 22 along the dotted line 24 to provide a generally U-shaped blade pair configuration. This configuration has the following advantages over that of FIG. The blade pair configuration formed from the strip 20 is lower in height than the configuration of FIG. 1b formed from the rectangular strip 10.

  FIG. 3 is a cross-sectional view showing how the blade pair configuration described above is attached to the hub 26. The hub 26 includes a recess 28 in the circumferential direction. An opening 32 passes through the wall 30 surrounding the recess 28 and houses the coupling pin 34. A bending portion 36 of the blade pair configuration 18 extends around the coupling pin 34. The opening 32 and the coupling pin 34 are arranged with respect to the recess 28 and the blade pair configuration 18 so that the blade pair configuration 18 abuts against the inner circumferential surface 38 of the hub 26 and is pinned.

  4-6 show an embodiment in which the blades 40, 50, 60, 70 are formed from a single strip.

  In the embodiment of FIG. 4, a pair of reinforcing plates 42 are fixed or attached to one end of the blade 40. The two through holes 44 are slightly inclined with respect to the surface of the widest surface of the blade 40 and are drilled through the reinforced portion of the blade 40. This inclination angle corresponds to a desired inclination angle of the blade 40 with respect to the rotating surface of the rotor blade. The through hole 44 is formed to receive a fixing pin 46, and the fixing pin 46 passes through the through hole of the hub during use. This is similar to the coupling pin 34 of FIG.

  The plate 42 is made of metal, such as high-quality aluminum or titanium, but other materials can be used. This plate material is capable of withstanding the reaction force of the fixed pin 46 against the blade 40 when the rotor blades are rotating at the speed required for the turbomolecular pump, or a tensile load or compression concentrated on the reinforced portion of the blade 40. Selected to withstand the load. As an alternative to the reinforcing plate, the blade 40 may simply be thickened in the region of the through hole 44.

  As an option, the plurality of blade rows may be arranged so that a plurality of parallel blades in different rows are arranged using a single fixing pin 46.

  In the embodiment of FIG. 5, a pair of locking plates 48 are fixed or attached to one end of the blade 50. For example, during manufacture of the blade 50, the locking plate 48 may be placed in a mold tool in which the blade 50 is solidified.

  The locking plate 48 has the dual function of strengthening the blade 50 at its root and providing locking means for mounting the blade 50 in the hub. In the illustrated embodiment, the locking plate 48 has a substantially dovetail shape, but the plate 48 can take any other shape. For example, it is a shape having a portion where the vicinity of the end of the blade is widened. The material of the locking plate 48 and its dimensions are selected to withstand the tensile and compressive forces concentrated on the reinforced portion of the blade 50 when the rotor blades are rotating at the operating speed required for the turbomolecular pump. For example, the locking plate 48 can be formed of a metallic material (eg, high quality aluminum or titanium) or a non-metallic material, eg, a layer of the same material from which the blade 50 is formed. Thus, the centrifugal force is evenly distributed throughout the locking plate 48, which can be formed in a mirror image with each other.

  In order to attach the blades 50 to the hubs, the hubs are provided with machined keyholes that are configured to accommodate the dovetail ends of the respective blades 50. The blade 50 may be friction bonded or coupled to these key holes or key holes. Bonding may be performed by chemical means (eg, adhesive) or physical means (eg, welding).

  In the embodiment shown in FIG. 6, the end of the blade 60 simply fits within a slot 62 formed in the hub 64. Hubs 64 are cut away as indicated at 66 at locations adjacent to the root of blade 60 and both sides of slot 62 to reduce expansion of slot 62. This is the case when the hub 64 thermally expands while rotating at the normal operating speed of the turbomolecular pump. Furthermore, the overall weight of the rotor blade is reduced.

  FIG. 7 shows a developed state of the embodiment of FIG. A plurality of blades 70 are arranged in parallel with each other around the hub 71, and adjacent blades overlap in a vertical plane. A plurality of pins 72 extend vertically through holes 74 in the hub 71, each pin passing through two blades. Thus, each blade is fixed at two ends, and each pin fixes two blades, thereby increasing the safety of the blade.

  The above description relates to one embodiment of the present invention, and those skilled in the art can consider various modifications of the present invention, all of which are included in the technical scope of the present invention. The

The top view showing the 1st Example of the strip which forms the blade for rotor blades for turbomolecular pumps. FIG. 1b represents the strip of FIG. 1a folded to form a blade. The top view of 2nd Example of the strip which forms the blade | wing of a rotary blade. FIG. 2 shows a technique for attaching the blade of FIG. 1b to the hub of a rotor blade. The perspective view of 3rd Example of the blade for rotary blades. The perspective view of 4th Example of the blade for rotary blades. The figure showing the technique which fixes the braid | blade of 5th Example to the hub of a rotary blade. The figure showing the Example which each pin fixes a some braid | blade to the hub of a rotary blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Strip 12, 14 Blade 18 Blade pair structure 20 Strip 22 Dock leg bending part 26 Hub 28 Recess 30 Wall 32 Opening 34 Connection pin 36 Bending part 38 Inner circumferential surface 40, 50, 60, 70 Blade 44 Through-hole 46 Fixing pin 48 Locking plate 62 Slot 64 Hub 71 Hub 72 Pin 74 Hole

Claims (34)

In the rotor blade for a turbomolecular pump, the rotor blade is:
A hub,
A plurality of blades made of reinforced polymer material;
Means for attaching the blade to the hub;
A rotor blade for a turbo pump characterized by comprising:   The rotor blade according to claim 1, wherein the polymer material is reinforced by one of fibers or particles.   3. A rotor blade according to claim 2, wherein the fibers or particles are aligned in direction and provide maximum strength in a region and / or direction of maximum load on the blade during use of the rotor blade.   The rotor blade according to claim 3, wherein most of the fibers or particles are aligned from the root of the blade toward the tip.   The rotor blade according to claim 4, wherein most of the fibers or particles are present in a range of 75% to 85% of the fibers or particles in the blade.   The rotor blade according to claim 2, wherein the polymer material is reinforced by a carbon fiber.   The rotor blade according to claim 2, wherein the polymer material is reinforced by fibers or particles formed of glass or a ceramic material.   The rotor blade according to claim 2, wherein the polymer material is reinforced with a synthetic fiber.   The rotor blade according to claim 8, wherein the synthetic fiber includes para-amid fibers.   The rotor blade according to claim 1, wherein the polymer material is epoxy.   The rotor blade according to claim 10, wherein the polymer material is polyetheretherketone.   The rotating blade according to any one of claims 1 to 11, wherein the attachment means is disposed at an end portion of each blade or in an end portion direction.   A rotor blade according to any preceding claim, wherein each blade comprises a strip of reinforced polymer material.   The rotor blade of claim 13, wherein the pair of adjacent blades is formed from a single strip of reinforced polymer material.   The rotor blade of claim 14, wherein the strip is bent to form an adjacent blade. The unbent strip has two equally sized and parallel aligned end portions that are joined at the central portion;
The central portion is inclined with respect to the two end portions to provide a dog-leg bend to the strip;
The rotor blade of claim 15, wherein the strip is bent along a central portion.   The rotor blade according to any one of claims 13 to 16, wherein the attachment means includes a pin for attaching the strip to the hub.   18. A rotor blade according to claim 17, wherein the strip bending is in the vicinity of the pin when claim 15 or 16 is cited.   The rotor blade according to claim 17, wherein the pin passes through a hole formed at one end of the strip.   20. A rotor blade according to claim 19, wherein one end of the strip is locally thickened or reinforced.   21. The rotor blade according to claim 20, wherein each blade has a pair of reinforcing plates sandwiching one end of the strip, and the pins penetrate through a through hole formed in the reinforcing plate.   The rotor blade according to any one of claims 19 to 21, wherein a longitudinal axis of the pin forms an acute angle with a normal line of a blade surface.   23. A rotor blade according to any one of claims 17-22, comprising a plurality of blade rows aligned in parallel, wherein the pin attaches a plurality of blades in different rows to the hub.   The rotor blade according to claim 12, wherein the attachment means has a plurality of slots formed in a hub, and each slot accommodates a respective end portion of a blade.   25. A rotor blade according to claim 24, wherein each blade has a dovetail shape and the slot is configured to receive an end of the dovetail shape of the blade.   The rotor blade according to claim 25, wherein the tail shape of the pigeon is formed from a member attached to an end of each blade.   27. The rotor blade according to claim 26, wherein the dovetail shape is formed by a metal plate attached to a blade.   The rotor blade according to claim 27, wherein the plate is made of aluminum or an aluminum alloy.   29. A rotor blade according to any of claims 24-28, wherein an end of the blade is secured or coupled within a slot.   30. A rotor blade according to any of claims 24-29, wherein the hub is cut off at a location adjacent to the slot.   31. A rotor blade according to any of claims 1-30, wherein the reinforced polymer material is selected to have mechanical properties to withstand stresses experienced when the rotational speed of the tip of the blade is at a sonic level.   32. A rotor blade according to any preceding claim, wherein the blade comprises a coating layer selected so as not to react with chemicals passing through the pump in use.   The rotor blade according to claim 32, wherein the coating layer is made of metal. In a rotor blade for a turbomolecular pump, the rotor blade is:
A hub,
A plurality of blades formed from strips of reinforced polymer material attached to the hub;
A rotor blade for a turbomolecular pump, comprising:

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