Rotational transmission device

Abstract

To suppress the thermal effects on the motor in a rotary transmission device. [Solution] The device comprises a shaft extending in a predetermined direction, a rotor provided to surround the shaft around its axis, a housing surrounding the shaft around its axis outside the rotor, a stator surrounding the housing around its axis, a bearing interposed between the outer circumferential surface of a support region on the shaft at the other end from the rotor and the inner circumferential surface of the housing to support the shaft so that it can rotate around its axis relative to the housing, a magnetic fluid seal in a seal region on the shaft at the other end from the bearing to close the internal space surrounded by the housing, and a heat sink surrounding at least the outside of the support region around the housing around its axis.

Description

Technical Field

[0001] The present invention relates to a rotational transmission device that transmits rotation to a rotating object.

Background Art

[0002] Conventionally, in the process of manufacturing semiconductors and the like, processing is carried out while rotating a rotating object in a closed space under reduced pressure. As such a device for transmitting rotation to a rotating object, a rotational transmission device has been proposed in which the end side of a shaft body rotated by a motor is sealed with a magnetic fluid, and a rotating object is attached to the end face of this shaft body (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the process of manufacturing semiconductors, the closed space or the rotating object may be placed in a high - temperature environment. In this case, the heat flowing in via the rotating object is transmitted to the motor through the shaft body, and as a result, there is a problem that the operation of the motor becomes unstable due to the influence of this heat.

[0005] The invention has been made to solve such problems, and its object is to provide a technique for suppressing the influence of heat on a motor in a rotational transmission device.

Means for Solving the Problems

[0006] To solve the above problems, the first phase of the rotational transmission device comprises a shaft extending in a predetermined direction, a rotor provided so as to surround the shaft around its axis and which is driven by the rotation of the shaft around its axis, a cylindrical member surrounding the shaft around its axis outside the rotor and having one end closed while the other end open as a housing, a stator surrounding the housing around its axis and provided in a positional relationship with the rotor in the inward and outward directions and fixed to the housing, and the shaft being further from the rotor The housing comprises: a bearing interposed between the outer circumferential surface of a support region on the other end and the inner circumferential surface of the housing, supporting the shaft so that it can rotate around its axis relative to the housing; a magnetic fluid seal that seals the internal space surrounded by the housing in the seal region by interposing magnetic fluid between the outer circumferential surface of a seal region on the shaft on the other end of the shaft and the inner circumferential surface of the housing; and a heat sink that surrounds at least the outside of the support region around its axis in the housing, promoting heat dissipation from the outer circumferential surface of the housing.

[0007] In this rotational transmission device, heat dissipation is promoted from the support area through the bearings, housing, and heat sink. As a result, heat is less likely to be transferred to the motor (rotor and stator) in the adjacent area, thus suppressing the thermal impact on the motor. This phase can be made as shown in the second phase below. In the second phase, the thermal resistance per unit thickness along the axial direction in the adjacent region adjacent to the support region at one end of the shaft is greater than that of the support region. In this type of rotational transmission device, the difference in thermal resistance suppresses heat conduction from the support region of the shaft to adjacent regions. As a result, heat is less likely to reach the motor (rotor and stator) located closer to the adjacent region, thus reducing the thermal impact on the motor.

[0008] This phase may be as shown in the third and fourth phases below. In the third phase, the shaft has a hole that extends from one end to the adjacent region, and the cross-sectional area intersecting the axis in the adjacent region is smaller than that of the support region.

[0009] In this type of rotational transmission device, a hole extending from one end to an adjacent region makes the cross-sectional area of ​​the adjacent region smaller than that of the support region, thereby increasing the thermal resistance of the adjacent region compared to that of the support region.

[0010] In the fourth phase, the shaft is formed of a material in which at least a portion of the adjacent region has a lower thermal conductivity than the support region.

[0011] In this type of rotational transmission device, the thermal resistance in the adjacent region can be made greater than that of the support region by forming a portion of the adjacent region with a material that has a lower thermal conductivity than the support region.

[0012] This phase may be as shown in the fifth and sixth phases below. In the fourth phase, the shaft is formed of a material with lower thermal conductivity than the support region, at least in the adjacent region, over a predetermined thickness.

[0013] In this type of rotational transmission device, the thermal resistance in the adjacent region can be made greater than that of the support region by forming a region of a predetermined thickness in the adjacent region with a material that has a lower thermal conductivity than the support region.

[0014] In the sixth phase, the shaft body is formed in such a way that the entire adjacent region is made of a material with a lower thermal conductivity than the support region.

[0015] In this type of rotational transmission device, the thermal resistance in the adjacent region can be made greater than that of the support region by forming the entire adjacent region with a material that has a lower thermal conductivity than the support region.

[0016] Furthermore, each of the above phases may be as shown in the seventh phase below. In the seventh phase, an inner fitting groove is formed in the support region around the entire circumference of the axis, and the inner ring of the bearing of the shaft is fitted into this inner fitting groove.

[0017] In this type of rotational transmission device, the internal fitting groove formed in the support region increases the contact area between the bearing and the support region, i.e., the shaft, as the bearing's inner surface, as well as one and the other end faces of the bearing's inner ring, engage with the support region. Therefore, heat dissipation from the support region through the bearing, housing, and heat sink can be effectively promoted.

[0018] Furthermore, each of the above phases may be as shown in the eighth phase below. In the eighth phase, an outer fitting groove is formed around the entire circumference of the axis in the region of the inner circumferential surface of the housing that faces the support region and the inner and outer sides, and the bearing outer ring of the bearing is fitted into this outer fitting groove.

[0019] In this type of rotational transmission device, the external fitting groove formed in the housing allows the bearing to engage not only with its outer surface but also with one and the other end faces of the bearing's outer ring, increasing the contact area. Therefore, heat dissipation from the support area through the bearing, housing, and heat sink can be effectively promoted. [Brief explanation of the drawing]

[0020] [Figure 1] Front view of a rotary transmission device and vacuum chamber, which are one embodiment of the present disclosure. [Figure 2] A cross-sectional view (viewed along arrow AA in Figure 1) of a rotary transmission device and vacuum chamber, which are embodiments of the present disclosure, taken along the plane formed by the axial direction and its intersecting direction. [Figure 3] A cross-sectional view (viewed along arrow AA in Figure 1) of a rotary transmission device, which is one embodiment of the present disclosure, taken along the plane formed by the axial direction and its intersecting direction. [Figure 4] A cross-sectional view (viewed along arrow AA in Figure 1) of each of the components of a rotary transmission device, which is one embodiment of the present disclosure, along the plane formed by the axial direction and its intersecting direction. [Figure 5] Cross-sectional view of the main part of the magnetic fluid seal in the rotational transmission device according to an embodiment of the present disclosure, taken along a plane formed by the axial direction and the direction intersecting the axial direction [Figure 6] Cross-sectional view (view taken along the arrow A-A in FIG. 1) (1 / 3) of some components of the rotational transmission device in another embodiment, taken along a plane formed by the axial direction and the direction intersecting the axial direction [Figure 7] Cross-sectional view (view taken along the arrow A-A in FIG. 1) (2 / 3) of some components of the rotational transmission device in another embodiment, taken along a plane formed by the axial direction and the direction intersecting the axial direction [Figure 8] Cross-sectional view (view taken along the arrow A-A in FIG. 1) (3 / 3) of some components of the rotational transmission device in another embodiment, taken along a plane formed by the axial direction and the direction intersecting the axial direction

Embodiments for Carrying out the Invention

[0021] Embodiments of the present invention will be described below with reference to the drawings. (1) Overall configuration (1-1) First embodiment

[0022] The rotational transmission device 1 is attached to a device that processes a rotation object while rotating the rotation object within a decompressed closed space. In the present embodiment, as shown in FIGS. 1 and 2, the rotational transmission device 1 is attached to a vacuum chamber 3 of a semiconductor manufacturing device that processes a turn table 2, which is a rotation object, while rotating the turn table 2 within a decompressed closed space, and an example of the configuration is illustrated.

[0023] As shown in Figure 3, the rotation transmission device 1 comprises a shaft 10 extending in a predetermined direction (up and down in the figure), a rotor 20 surrounding the shaft 10 around an axis 110, a cylindrical housing 30 surrounding the shaft 10 outside the rotor 20 around the axis 110, a stator 40 surrounding the housing 30 around the axis 110, a bearing 50 supporting the shaft 10 so that it can rotate around the axis 110 relative to the housing 30, a magnetic fluid seal 60 sealing the internal space surrounded by the housing 30, a heat sink 70 surrounding the outside of the housing 30 around the axis 110, and a rotation detection unit 80 for detecting the rotation of the shaft 10.

[0024] As shown in Figure 3, the shaft 10 has a mounting surface 11 formed on the other end (upper end in the figure) for attaching the object to be rotated, with one end (lower end in the figure) being housed in the housing 30. In this embodiment, the object to be rotated is screwed to the shaft 10 while positioned along the mounting surface 11 of the shaft 10.

[0025] Furthermore, the shaft body 10 is equipped with a flange 13 that widens to a larger diameter at the other end than the rest of the shaft. This flange 13 is located on one end side of the bearing 50.

[0026] Furthermore, as shown in Figure 4, the shaft body 10 has a support region 15 located on the other end side of the rotor 20, and an adjacent region 17 adjacent to the support region 15 on the one end side. In this case, the entire area on one end side of the support region 15 of the shaft body 10 is the adjacent region 17.

[0027] The shaft 10 is configured such that the thermal resistance per unit thickness along the axis 110 in the adjacent region 17 is greater than that of the support region 15.

[0028] In this embodiment, the shaft 10 has a hole 120 that extends from one end to the adjacent region 17. This hole 120 makes the cross-sectional area where it intersects the axis 110 in the adjacent region 17 smaller than that of the support region 15, thereby increasing the thermal resistance in the adjacent region 17 compared to the support region 15. In this embodiment, the hole 120 extends from one end of the shaft 10 to the boundary between the support region 15 and the adjacent region 17.

[0029] The rotor 20 is provided so as to surround the shaft body 10 around the axis 110 and is driven by the rotation of the shaft body 10 around the axis 110. In this embodiment, the rotor 20 is provided along the outer circumference of the shaft body 10 at a position on one end side of the flange 13 along the axis 110.

[0030] The housing 30 is a cylindrical member that surrounds the shaft 10 around the axis 110, outside the rotor 20. One end of this member is closed, while the other end is open. The housing 30 is made of a non-magnetic material.

[0031] The stator 40 surrounds the housing 30 around the axis 110 and is positioned opposite the rotor 20 in the inward and outward directions, and is fixed to the housing 30. In this embodiment, the stator 40 surrounds the shaft 10 on the outside of the housing 30 and is fixed to the outer surface of the housing 30 in a position where it is positioned opposite the rotor 20 in the inward and outward directions, with a partition wall in the housing 30 in between.

[0032] The bearing 50 is interposed between the outer circumferential surface of the support region 15 on the shaft 10 and the inner circumferential surface of the housing 30, and supports the shaft 10 so that it can rotate around the axis 110 relative to the housing 30. In this embodiment, a ball bearing is used as the bearing 50.

[0033] Here, an inner fitting groove 15a is formed in the support region 15 of the shaft body 10, extending around the entire circumference of the axis 110, and the inner bearing ring 51 of the bearing 50 is fitted into this inner fitting groove 15a. In addition, an outer fitting groove 31 is formed in the inner circumferential surface of the housing 30, extending around the entire circumference of the axis 110 in the region facing the support region 15, and the outer bearing ring 53 of the bearing 50 is fitted into this outer fitting groove 31.

[0034] The magnetic fluid seal 60 seals the internal space surrounded by the housing 30 in the sealing region 19 by interposing magnetic fluid 63 between the outer circumferential surface of the sealing region 19 located on the other end of the shaft 10 beyond the bearing 50 and the inner circumferential surface of the housing 30.

[0035] As shown in Figure 5, the magnetic fluid seal 60 comprises a pair of magnetic poles 61 that protrude from either the shaft 10 or the housing 30 toward the other in the sealing region 19, and a magnetic fluid 63 interposed between the tip of the magnetic pole 61 and the other of the shaft 10 or the housing 30. In this embodiment, the magnetic poles 61 are provided to protrude from the shaft 10 in the sealing region 19.

[0036] Each of these magnetic poles 61 has a permanent magnet 65 sandwiched at its end, and by forming a magnetic circuit (see dashed line in the figure) located between its tip and the other side of the shaft 10 and housing 30, it magnetically holds the magnetic fluid 63 between the shaft 10 and the housing 30.

[0037] The heat sink 70 is a block that surrounds at least the outside of the support area 15 of the housing 30 around the axis 110, and is intended to promote heat dissipation from the outer surface of the housing 30. The heat sink 70 is equipped with a coolant inlet 71 and outlet 73 provided on the sides, and a flow path 75 connecting one of them to the other. The flow path 75 is arranged to circulate around the axis 110 within the housing 30 and the stator 40.

[0038] The rotation detection unit 80 is a magnetic encoder positioned on one end of the shaft 10, closer to the rotor 20, and includes a magnet piece 81 that rotates around the axis 110 in accordance with the shaft 10, and a magnetic sensor 83 that detects the change in the magnetic field accompanying the rotation of the magnet piece 81 as the rotation of the shaft 10.

[0039] Of these, the magnet piece 81 has multiple opposing magnetic poles (south poles and north poles) arranged alternately next to each other around the axis 110. The magnetic sensor 83 is a Hall element that detects changes in magnetic poles along the axis 110.

[0040] In the rotation transmission device 1 configured in this way, with the object to be rotated attached to the other end of the shaft 10, the shaft 10 is rotated together with the rotor 20 by energizing the stator 40, thereby transmitting this rotation to the object to be rotated.

[0041] (1-2) Second Embodiment The rotary transmission device 1 of this embodiment differs from the first embodiment in that at least a portion of the adjacent region 17 of the shaft body 10 is formed of a material with lower thermal conductivity than the support region 15.

[0042] As an example of such a rotational transmission device 1, a region extending over a predetermined thickness in the adjacent region 17 can be formed from a material with lower thermal conductivity than the support region 15. Specifically, as shown in Figure 6, the other end face of the adjacent region 17 can be made of a sheet member 17a made of a material (e.g., resin material) with lower thermal conductivity than the support region 15. In this case, the parts of the adjacent region 17 other than the sheet member 17a can be made of a metal material or the like with higher thermal conductivity than the sheet member 17a. Each region can be fastened with screws in the direction of the axis 110.

[0043] Furthermore, in this embodiment of the rotation transmission device 1, it is conceivable to form the entire adjacent region 17 with a material having a lower thermal conductivity than the support region 15. Specifically, as shown in Figure 7, the entire adjacent region 17 may be constructed from a material (for example, a resin material) having a lower thermal conductivity than the support region 15. Here, the support region 15 may be constructed from a metal material or the like with a higher thermal conductivity than the adjacent region 17. Each region can be fastened with screws in the direction of the axis 110.

[0044] Furthermore, in the rotary transmission device 1 of this embodiment, it is conceivable to provide a portion of the adjacent region 17 made of a material with low thermal conductivity. Specifically, as shown in Figure 8, a cylindrical void 130 extending in the direction of the axis 110 can be provided in the adjacent region 17, and this can be filled with a material (for example, a resin material) that has lower thermal conductivity than other regions to form a filled portion 131. Here, the support region 15 and the adjacent region 17 may be made of a metal material or the like that has higher thermal conductivity than the adjacent region 17.

[0045] (2) Variant Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited in any way to the above embodiments and can take various forms as long as they fall within the technical scope of the present invention.

[0046] For example, in the above embodiment, a configuration was illustrated in which a hole 120 is formed extending from one end of the shaft 10 to the adjacent region 17. However, this hole 120 does not necessarily have to extend from one end of the shaft 10, as long as the cross-sectional area in the adjacent region 17 is smaller than that of the support region 15.

[0047] Furthermore, in the above embodiment, the rotor 20 is provided on the outer circumference of the shaft 10 and integrated with the shaft 10 so that the rotor 20 is driven by the rotation of the shaft 10 around the axis 110. However, the rotor 20 only needs to be configured to be driven by the rotation of the shaft 10 around the axis 110, and does not necessarily need to be integrated with the shaft 10. Specifically, it is conceivable to have a hole such as the gap 130 in the second embodiment above.

[0048] Furthermore, in the above embodiment, a configuration was illustrated in which the stator 40 surrounds the shaft 10 on the outside of the housing 30 and is fixed to the outer circumferential surface of the housing 30. However, the stator 40 may also surround the shaft 10 on the inside of the housing 30 and be fixed to the inner circumferential surface of the housing 30.

[0049] Furthermore, in the above embodiment, a configuration was illustrated in which the magnetic pole 61 of the magnetic fluid seal 60 is provided on the shaft body 10 side. However, the magnetic pole 61 may also be provided on the housing 30 side.

[0050] Furthermore, in the above embodiment, a configuration in which a magnetic encoder is used as the rotation detection unit 80 was illustrated. However, a configuration in which an optical or electromagnetic induction encoder is used as the rotation detection unit 80 is also possible.

[0051] (3) Action, effect In the rotary transmission device 1 of the above embodiment, heat dissipation is promoted from the support region 15 through the bearing 50, housing 30, and heat sink 70. In addition, in the rotary transmission device 1 of the above embodiment, the conduction of heat from the support region 15 of the shaft 10 to the adjacent region 17 is suppressed due to the difference in thermal resistance.

[0052] For example, in a configuration in which a hole 120 is formed from one end to an adjacent region 17, the thermal resistance in the adjacent region 17 can be made greater than that of the support region 15 by making the cross-sectional area of ​​the adjacent region 17 smaller than that of the support region 15. Also, in a configuration in which part or all of the adjacent region 17 is formed of a material with lower thermal conductivity than that of the support region 15, the presence of this material can make the thermal resistance in the adjacent region 17 greater than that of the support region 15.

[0053] Thus, in the above-described rotation transmission device 1, heat is less likely to be transferred to the motor (rotor 20 and stator 40) located in the adjacent region 17, thereby suppressing the thermal effects on the motor.

[0054] Furthermore, in the above embodiment of the rotational transmission device 1, the inner fitting groove 15a formed in the support region 15 allows the bearing 50 to engage not only with its inner circumferential surface, but also with one end face and the other end face of the bearing inner ring 51, thereby increasing the contact area with the support region 15, i.e., the shaft 10. Therefore, heat dissipation from the support region 15 through the bearing 50, housing 30, and heat sink 70 can be effectively promoted.

[0055] Furthermore, in the above embodiment of the rotary transmission device 1, the outer fitting groove 31 formed in the housing 30 allows the bearing 50 to fit not only its outer surface but also one end face and the other end face of the bearing outer ring 53 with the housing 30, thereby increasing the contact area. As a result, heat dissipation from the support area 15 through the bearing 50, housing 30, and heat sink 70 can be effectively promoted. [Explanation of Symbols]

[0056] 1...Rotation transmission device, 2...Turntable, 3...Vacuum chamber, 10...Shaft body, 11...Mounting surface, 13...Flange, 15...Support area, 15a...Inner fitting groove, 17...Adjacent area, 17a...Sheet member, 19...Seal area, 20...Rotor, 30...Housing, 31...Outer fitting groove, 40...Stator, 50...Bearing, 51...Inner ring of bearing, 53...Outer ring of bearing, 60...Magnetic fluid seal, 61...Magnetic pole, 63...Magnetic fluid, 65...Permanent magnet, 70...Heat sink, 71...Inlet, 73...Outlet, 75...Flow path, 80...Rotation detection unit, 81...Magnet piece, 83...Magnetic sensor, 110...Axis, 120...Hole, 130...Gap, 131...Filling section.

Claims

1. A shaft extending in a predetermined direction, A rotor is provided so as to surround the shaft body around its axis and is driven by the rotation of the shaft body around its axis, A cylindrical member that surrounds the shaft body around its axis, outside the rotor, and having one end closed while the other end open, A stator is provided that surrounds the housing around its axis and is positioned in a position opposite to the rotor in the inward and outward directions, and is fixed to the housing, A bearing interposed between the outer circumferential surface of a support region on the other end of the shaft body, which is located beyond the rotor, and the inner circumferential surface of the housing, supports the shaft body so that it can rotate around its axis relative to the housing, By interposing a magnetic fluid between the outer circumferential surface of the sealing region on the other end of the shaft body, and the inner circumferential surface of the housing, a magnetic fluid seal is formed that seals the internal space surrounded by the housing in the sealing region. The housing comprises a heat sink that surrounds at least the outside of the support area around its axis and promotes heat dissipation from the outer surface of the housing, Rotational transmission device.

2. The aforementioned shaft has a thermal resistance per unit thickness along the axial direction in an adjacent region adjacent to the support region at one end, which is greater than that of the support region. The rotational transmission device according to claim 1.

3. The shaft has a hole formed in it that extends from one end to the adjacent region, and the cross-sectional area intersecting the axis in the adjacent region is smaller than that of the support region. The rotational transmission device according to claim 2.

4. The shaft body is formed of a material with a lower thermal conductivity than the support region, at least in a portion of the adjacent region. The rotational transmission device according to claim 2.

5. The shaft body is formed such that at least the adjacent region, over a predetermined thickness, is made of a material with lower thermal conductivity than the support region. The rotational transmission device according to claim 4.

6. The shaft body is formed such that the entire adjacent region is made of a material with a lower thermal conductivity than the support region. The rotational transmission device according to claim 4.

7. An inner fitting groove is formed in the support region around the entire circumference of the axis, and the inner ring of the bearing of the shaft is fitted into this inner fitting groove. A rotational transmission device according to any one of claims 2 to 6.

8. On the inner circumferential surface of the housing, an outer fitting groove is formed around the entire circumference of the axis in the region facing the support area and the inner and outer sides, and the outer ring of the bearing of the bearing is fitted into this outer fitting groove. The rotational transmission device according to claim 7.

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