Abstract
Systems here include cone shaped turbine caps mounted to a turbo molecular turbine assembly. In some embodiments, the turbo molecular turbine assembly includes a body with a top cavity, a bottom cavity and external fins, the body mounted to a pump rotor. In some embodiments, the turbo molecular turbine assembly and cone shaped turbine cap are configured to fit into a chamber and spun by the mounted pump rotor. In some embodiments, the turbine external fins are configured to pump gasses and suspended particles from the chamber when spun. And in some embodiments, the cone shaped turbine cap includes a vent channel for venting air from the top cavity.
Claims
1. A turbo-molecular pump, comprising: a rotor; a turbine mounted to the rotor and including a recess opposite the rotor; a bolt attached to the rotor through an opening of the turbine and including a portion of the bolt disposed in the recess; and a cap disposed over the recess, wherein the cap includes a vent channel formed through the cap.
2. The turbo-molecular pump of claim 1, wherein the cap includes a convex upper surface.
3. The turbo-molecular pump of claim 1, wherein the cap includes a conically shaped surface oriented away from the recess.
4. The turbo-molecular pump of claim 3, wherein the conically shaped surface includes a central point.
5. The turbo-molecular pump of claim 1, further including a cutout formed in the cap.
6. The turbo-molecular pump of claim 1, wherein the cap is mounted to the turbine by a friction fit O-ring.
7. A turbo-molecular pump, comprising: a rotor; a turbine mounted to the rotor and including a recess oriented away from the rotor, wherein the recess comprises a bottom surface and a side surface within the recess; a cap disposed over the recess, wherein the cap includes a plate member comprising a cutout formed in the plate member; and an o-ring compressed between the cap and the side surface of the recess.
8. The turbo-molecular pump of claim 7, further including a vent channel formed through the cap.
9. The turbo-molecular pump of claim 7, further including a chamber disposed over the cap, wherein the turbo-molecular pump is configured to evacuate molecules from the chamber.
10. The turbo-molecular pump of claim 7, further including a bolt extending through the bottom surface of the recess to attach the turbine to the rotor.
11. The turbo-molecular pump of claim 10, wherein the side surface of the recess is perpendicular to the bottom surface.
12. The turbo-molecular pump of claim 10, wherein friction between the o-ring and the side surface of the recess holds the cap in place on the turbine.
13. A method of making a turbo-molecular pump, comprising: providing a turbine including a recess; mounting the turbine to a rotor with the recess oriented away from the rotor; and disposing a cap over the recess, wherein the cap includes a vent channel.
14. The method of claim 13, wherein the cap includes a convex upper surface.
15. The method of claim 13, wherein the cap includes a conically shaped upper surface.
16. The method of claim 15, wherein the conically shaped upper surface includes a central point.
17. The method of claim 13, wherein the vent extends from the recess to allow evacuation of molecules from the recess.
18. The method of claim 13, further including mounting the cap in the recess using a friction fit O-ring.
19. The method of claim 13, wherein the cap includes a plate member comprising a cutout formed in the plate member.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a cross sectional side view of a conventional turbo-molecular pump according to some embodiments herein.
(2) FIG. 2 is a cross sectional side view of the turbo-molecular pump of the present invention according to some embodiments herein.
(3) FIG. 3A is a cross sectional side view of the cap member with a parabolic shaped upper surface according to some embodiments herein.
(4) FIG. 3B is a cross sectional side view of the cap member with a squared shaped upper surface according to some embodiments herein.
(5) FIG. 3C is a cross sectional side view of the cap member with a rounded shaped upper surface according to some embodiments herein.
(6) FIG. 4A is a cross sectional side view of the cap member with a fin on its upper surface according to some embodiments herein.
(7) FIG. 4B is a cross sectional side view of the cap member with a channel on its upper surface according to some embodiments herein.
(8) FIG. 4C is a cross sectional side view of the cap member with an asymmetric shaped upper surface according to some embodiments herein.
(9) FIG. 5A is a cross sectional side view of the cap member with a vent channel along the center bolt aperture according to some embodiments herein.
(10) FIG. 5B is a cross sectional side view of the cap member with a vent channel extending therethrough according to some embodiments herein.
(11) FIG. 6 is a cross sectional side view of the cap member with a vent channel extending therethrough without a center bold aperture (i.e. for friction fit) according to some embodiments herein.
(12) FIGS. 7-8 are cross sectional side views of a cap member assembly with a compressible o-ring for a sealing friction fit according to some embodiments herein.
(13) FIG. 9 is a cross sectional side view of the cap member with cutouts according to some embodiments herein.
DETAILED DESCRIPTION
(14) The present invention is an improved turbine 30 as illustrated in FIG. 2. Turbine 30 is mounted to a pump rotor 32 via mounting bolts 34. The turbine 30 includes fins 36 used to pump the gasses and suspended particles from the chamber (not shown). The tops of the bolts 34 are recessed from the top surface of the turbine 30 in a bolt cavity 38 that has an open end. A cap member 40 is mounted over and seals the open end of the bolt cavity 38. The cap member 40 is mounted to the turbine via a center bolt 42 with sufficient force to form a seal between cap member 40 and turbine 30. The cap member 40 serves two important functions. First, it prevents particles from settling into the bolt cavity 38, where they could later be expelled back into the chamber, and/or preventing any particles in bolt cavity 38 from being expelled out into the chamber. Second, cap 40 has a shaped upper surface 40a which deflects particles away from the center of the turbine and toward the turbine's fins, so that they can be more effectively evacuated from the chamber. Surface 40a is preferably cone-shaped (conically shaped), which deflects downwardly moving particles outwardly toward the turbine fins.
(15) The inventive solution can be implemented on existing pumps without having to reconfigure the turbines therein. With the present invention, maintenance intervals can be lengthened due to reduced contamination from the bolt cavity.
(16) Surface 40a could alternately have a shape other than conical to assist in deflecting particles and/or gasses outwardly, such as a parabolic, squared, or rounded, as illustrated in FIGS. 3A-3C, respectively, or any other appropriate convex shape. Additionally, since the cap member 40 is spinning with the turbine 30, particle deflecting features can be formed on the cap's upper surface, such as fins 50, channels 52, or asymmetric convex shapes 54, as illustrated in FIGS. 4a-4C, respectively, to enhance particle deflection as the cap member 40 rotates.
(17) Optionally, the bolt cavity 38 can be vented, to allow the cavity 38 to evacuate to high vacuum during operation in certain applications. The venting can be achieved by an open or closed channel formed in the cap. FIG. 5A illustrates a vent channel 60 as part of the center bolt aperture 46 through the cap member 40. FIG. 5B illustrates a vent channel 62 formed through the cap member 40. FIG. 6 illustrates a vent channel 62, without a center bolt aperture (i.e. secured using a friction fit). With this configuration, cap member 40 can be mounted to turbine 30 via a friction fit instead of by center bolt 42.
(18) FIGS. 7-8 illustrate an example embodiments of cap member 40 with an adjustable friction fit. The cap member 40 includes a plate member 70 (together forming a cap member assembly), where the plate member 70 is dimensioned to fit inside bolt cavity 38. Plate member 70 includes a threaded hole 72 for receiving the center bolt 42. The cap member 40 and plate member 70 have opposing chamfered outer edges 74a and 74b. An o-ring 76 (e.g. made of rubber or other compressible material) is positioned between the cap member 40 and plate member 70. With the bolt 42 loosely engaged between cap member 40 and plate member 70 (e.g. an open position), the plate member 70 is inserted inside bolt cavity 38 until cap member 40 seats on the top surface of turbine 30 (as illustrated in FIG. 8). As the bolt 42 is tightened, the plate 70 is drawn toward cap member 40 to a closed position wherein the chamfered surfaces 74a/74b compress the o-ring 76 against the side surface of the cavity 38. The compressed o-ring 76 forms a seal between cap member 40 and the side surface of the cavity 38, as well as provides a friction fit therebetween to removably secure the cap member 40 to the turbine 30. This design facilities a convenient and reliable way to secure and remove the cap member 40 from turbine 30. This design also avoids the need to use a bolt connection with the turbine 30 (i.e. is compatible with turbines which do not have a threaded hole for engaging with bolt 42).
(19) FIG. 9 illustrates an example embodiment wherein the cap member 40 and plate member 70 include cutouts 96 in various places. These cutouts are shown in exemplary places and depths on both the cap 40 and plate 70 but could be put in at varying depths and angles and places. The example cutouts in FIG. 9 are shown as channels in the cap and plate members, but could be any variation of cutout besides a channel. Such example cutouts may save weight on the cap and plate and make them lighter. Such example cutouts could also be used for balancing the cap member assembly. It is to be understood that such cutouts could be used in any embodiment for weight savings and/or balancing purposes.
(20) In the example embodiment of FIG. 9, the bolt 42 is shown inserted from the bottom of the plate 70 and up into the cap member 40 as an example only. In this example, the hole in the cap 40 is threaded and not the hole in the plate. The plate 70 could include the bolt 42 affixed to it, or as a separate part, as shown in FIG. 9. In either case, the bolt 42 in this example extends up into the cap member's hole, and not down through the cap and also through into the plate.
(21) Thus, in the example embodiment of FIG. 9, there is no bolt hole or recess in the top of the cap member 40. Such an arrangement may provide fewer places for particulates to accumulate when in use. Thus, the cap top in this embodiment is shown with a peak, but could be rounded or squared off, or any kind of shape that would prevent accumulation of particles.
(22) It is to be understood that the present invention is not limited to the embodiment(s) described above and illustrated herein. For example, references to the present invention herein are not intended to limit the scope of any claim or claim term, but instead merely make reference to one or more features that may be covered by one or more claims. Materials, processes and numerical examples described above are exemplary only, and should not be deemed to limit the claims.
