U.S. patent application number 15/062380 was filed with the patent office on 2016-09-15 for vacuum pump.
This patent application is currently assigned to EBARA CORPORATION. The applicant listed for this patent is EBARA CORPORATION. Invention is credited to Atsushi SHIOKAWA.
Application Number | 20160265532 15/062380 |
Document ID | / |
Family ID | 56886498 |
Filed Date | 2016-09-15 |
United States Patent
Application |
20160265532 |
Kind Code |
A1 |
SHIOKAWA; Atsushi |
September 15, 2016 |
VACUUM PUMP
Abstract
There is provided a vacuum pump capable of preventing foreign
materials from flowing into a gap between rotors or the like and
obtaining low ultimate pressure. The vacuum pump includes two
rotating shafts formed extending in a first axial direction, a
rotor casing, rotors, and a shielding portion. The rotor casing
includes a rotor chamber disposed along the two rotating shafts, a
suction port communicating with the rotor chamber, and an exhaust
port communicating with the rotor chamber. The rotors are mounted
on the two rotating shafts and disposed in the rotor chamber. The
shielding portion is configured to prevent a gas sucked from the
suction port into the rotor chamber from directly flowing into a
gap between the rotors and is disposed between the suction port and
inside the rotor chamber.
Inventors: |
SHIOKAWA; Atsushi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EBARA CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
EBARA CORPORATION
Tokyo
JP
|
Family ID: |
56886498 |
Appl. No.: |
15/062380 |
Filed: |
March 7, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 25/02 20130101;
F04C 23/001 20130101; F04C 18/126 20130101; F04C 18/123 20130101;
F04C 2280/02 20130101; F04C 29/0092 20130101 |
International
Class: |
F04C 27/00 20060101
F04C027/00; F04C 29/12 20060101 F04C029/12; F04C 25/02 20060101
F04C025/02; F04C 23/00 20060101 F04C023/00; F04C 18/12 20060101
F04C018/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2015 |
JP |
2015-046274 |
Feb 2, 2016 |
JP |
2016-018054 |
Claims
1. A vacuum pump comprising: two rotating shafts formed extending
in a first axial direction; a rotor casing including a rotor
chamber disposed along the two rotating shafts, a suction port
communicating with the rotor chamber, and an exhaust port
communicating with the rotor chamber; rotors mounted on the two
rotating shafts and disposed in the rotor chamber; and a shielding
portion configured to prevent a gas sucked from the suction port
into the rotor chamber from directly flowing into a gap between the
rotors and disposed between the suction port and inside the rotor
chamber.
2. The vacuum pump according to claim 1, wherein the rotors are
roots type rotors or claw type rotors.
3. The vacuum pump according to claim 1, wherein when viewed from
the suction port toward inside the rotor chamber, the shielding
portion is disposed in front of a gap between the rotors.
4. The vacuum pump according to claim 1, wherein the shielding
portion is disposed upstream of the rotors and is disposed between
the two rotating shafts when viewed from the suction port toward
inside the rotor chamber.
5. The vacuum pump according to claim 1, wherein the shielding
portion has a tapered shape narrow on an upstream side and wide on
a downstream side.
6. The vacuum pump according to claim 1, wherein the shielding
portion has a curved surface shape protruding toward upstream.
7. The vacuum pump according to claim 1, wherein the rotor chamber
comprises multistage rotor chambers connected to each other through
a gas flow path, the rotors comprise multistage rotors, each
disposed in each of the multistage rotor chambers, and the
shielding portion is disposed between the suction port and inside a
first stage rotor chamber of the multistage rotor chambers.
8. The vacuum pump according to claim 7, further comprising a
foreign material capture unit having at least one of a trap and a
filter disposed in the gas flow path connecting between stages of
the multistage rotor chambers.
9. The vacuum pump according to claim 8, wherein the foreign
material capture unit is disposed in the gas flow path connecting
between the first stage rotor chamber and a next stage rotor
chamber of the multistage rotor chambers.
10. The vacuum pump according to claim 8, wherein the gap between
the rotor casing and the multistage rotors or the gap between the
multistage rotors in each of the multistage rotor chambers
downstream of the foreign material capture unit is formed smaller
than the gap therebetween upstream thereof.
11. The vacuum pump according to claim 8, further comprising a
pressure sensor disposed in the gas flow path upstream of the
foreign material capture unit for detecting a pressure.
12. The vacuum pump according to claim 8, wherein the foreign
material capture unit comprises a reticulated or porous filter.
13. The vacuum pump according to claim 1, wherein the suction port
is connected to a chamber where a gas containing non-sublimated
foreign materials occurs.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Japanese Application
Nos. 2015-046274, filed Mar. 9, 2015 and 2016-018054, filed Feb. 2,
2016, the entire contents of which are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a vacuum pump.
BACKGROUND ART
[0003] In a fabrication process of a semiconductor device and a
liquid crystal device, a dry vacuum pump is connected to a vacuum
chamber to exhaust a process gas introduced into the vacuum chamber
by the vacuum pump. The process gas to be exhausted by the vacuum
pump may include a material solidified by reaction or the like
inside the vacuum chamber or an easily solidified material mixed in
as a foreign material.
[0004] The dry vacuum pump is designed to have a small gap
(clearance) between a rotor and a rotor or between a rotor and a
casing. Accordingly, when solidified materials enter inside the
pump, the solidified materials may be deposited or trapped in a gap
therebetween inside the pump, which may block rotor rotation. For
this reason, a suction port of the dry vacuum pump may include a
trap or a filter to prevent solidified materials from entering
inside the pump.
[0005] [Patent Literature 1] Japanese Patent Laid-Open No.
5-332285.
SUMMARY OF INVENTION
[0006] When a process gas is prevented from entering the suction
port of the dry vacuum pump, the ultimate pressure of the vacuum
chamber connected to the dry vacuum pump will increase. Therefore,
a trap or the like disposed in the suction port of the dry vacuum
pump is configured to comprise a large trap or a plurality of
stages of traps, and such a configuration causes an increase in
size and cost of the fabrication apparatus. In addition, solidified
materials deposited in the trap or the like causing clogging also
prevent the dry vacuum pump from sucking the process gas, which may
often require maintenance such as cleaning and replacement of the
trap or the like.
[0007] In addition, as the dry vacuum pump, there have been known a
screw type vacuum pump, a roots type vacuum pump, and a claw type
vacuum pump. In general, the screw type vacuum pump is less
affected by foreign materials than the roots type vacuum pump and
the claw type vacuum pump. However, particularly in cases where
light gases such as hydrogen are used as the process gas, the roots
type vacuum pump and the claw type vacuum pump can have a lower
ultimate pressure than the screw type vacuum pump.
[0008] In view of the above problems, an embodiment has been made,
and an object of the embodiment is to provide a vacuum pump that
can prevent foreign materials from entering into gaps such as
between rotors and can have low ultimate pressure.
[0009] The vacuum pump of an embodiment includes two rotating
shafts formed extending in a first axial direction; a rotor casing;
rotors; and a shielding portion. The rotor casing includes a rotor
chamber disposed along the two rotating shafts; a suction port
communicating with the rotor chamber; and an exhaust port
communicating with the rotor chamber. The rotors are mounted on the
two rotating shafts and disposed in the rotor chamber. The
shielding portion is configured to prevent a gas sucked from the
suction port into the rotor chamber from directly flowing into a
gap between the rotors and is disposed between the suction port and
inside the rotor chamber.
[0010] According to this vacuum pump, the shielding portion is
disposed between the suction port and inside the rotor chamber.
This shielding portion prevents a gas sucked from the suction port
into the rotor chamber from directly flowing into a gap between
rotors. Thus, foreign materials can be prevented from being
deposited or trapped in gaps between rotors.
[0011] In addition, the rotors may be roots type rotors or claw
type rotors.
[0012] This configuration can achieve low ultimate pressure by the
vacuum pump particularly in cases where light gases such as
hydrogen are used as the process gas.
[0013] In addition, when viewed from the suction port toward inside
the rotor chamber, the shielding portion may be disposed in front
of a gap between the rotors.
[0014] This configuration can prevent foreign materials from
directly flowing into the gap between the rotors.
[0015] In addition, the shielding portion may be disposed upstream
of the rotors and may be disposed between the two rotating shafts
when viewed from the suction port toward inside the rotor
chamber.
[0016] This configuration can prevent foreign materials from
directly flowing into the gap between the rotors.
[0017] In addition, the shielding portion may have a tapered shape
narrow on an upstream side and wide on a downstream side. The
shielding portion may also have a curved surface shape protruding
toward upstream.
[0018] This configuration can effectively prevent foreign materials
from directly flowing into the gap between the rotors.
[0019] In addition, the rotor chamber may comprise multistage rotor
chambers connected to each other through a gas flow path. The
rotors may comprise multistage rotors, each disposed in each of the
multistage rotor chambers. The shielding portion may be disposed
between the suction port and inside a first stage rotor chamber of
the multistage rotor chambers.
[0020] This configuration can prevent foreign materials from
directly flowing into the gap between the rotors inside the first
stage rotor chamber.
[0021] In addition, the vacuum pump may further comprise a foreign
material capture unit having at least one of a trap and a filter
disposed in the gas flow path connecting between stages of the
multistage rotor chambers.
[0022] This configuration allows the foreign material capture unit
in the gas flow path to capture foreign materials contained in the
gas. In addition, the foreign material capture unit for capturing
foreign materials is disposed between stages of the multistage
rotor chambers, and hence the foreign material capture unit does
not prevent suction from the vacuum chamber to the first stage
rotor chamber, whereby low ultimate pressure can be obtained. In
addition, the foreign material capture unit is disposed downstream
of the first stage rotor chamber whose pressure is greater than
that of the suction port, thus allowing a simply configured foreign
material capture unit to be used. Furthermore, even if foreign
materials are deposited in the foreign material capture unit, this
little affects the suction of the first stage rotor chamber, thus
reducing frequency of maintenance of the foreign material capture
unit.
[0023] In addition, the foreign material capture unit may be
disposed in the gas flow path connecting between the first stage
rotor chamber and a next stage rotor chamber of the multistage
rotor chambers.
[0024] The gap between the rotor casing and the multistage rotors
or the gap between the multistage rotors in each of the multistage
rotor chambers downstream of the foreign material capture unit may
be formed smaller than the gap therebetween upstream thereof.
[0025] This configuration can prevent foreign materials from being
deposited or trapped upstream than the foreign material capture
unit and allows the vacuum pump to achieve low ultimate
pressure.
[0026] In addition, the vacuum pump may further comprise a pressure
sensor disposed in the gas flow path upstream of the foreign
material capture unit for detecting a pressure.
[0027] This configuration can measure timing of maintenance of the
foreign material capture unit based on the detection of the
pressure sensor.
[0028] In addition, the foreign material capture unit may comprise
a reticulated or porous filter.
[0029] This configuration can suitably capture foreign materials
flowing through the gas flow path.
[0030] In addition, the suction port may be connected to a chamber
where a gas containing non-sublimated foreign materials occurs.
BRIEF DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is a schematic configuration view illustrating a
vacuum pump apparatus according to the present embodiment;
[0032] FIG. 2 is a schematic configuration view of the vacuum pump
apparatus according to the present embodiment;
[0033] FIG. 3 is a sectional view schematically illustrating inside
of a first stage rotor chamber according to the present
embodiment;
[0034] FIG. 4 is a sectional view schematically illustrating inside
of a second stage rotor chamber according to the present
embodiment;
[0035] FIG. 5 is a schematic view illustrating an example of a
foreign material capture unit;
[0036] FIG. 6 is a schematic view illustrating another example of
the foreign material capture unit;
[0037] FIG. 7 is a schematic configuration view illustrating a
vacuum pump apparatus according to a first modification; and
[0038] FIG. 8 is a block diagram schematically illustrating a
vacuum pump apparatus according to a second modification.
DESCRIPTION OF EMBODIMENTS
[0039] FIG. 1 is a schematic configuration view illustrating a
vacuum pump apparatus according to the present embodiment. FIG. 2
is a detailed configuration view of the vacuum pump apparatus
according to the present embodiment. The vacuum pump apparatus
according to the present embodiment is connected, for example, to a
vacuum chamber (unillustrated) where CVD processing is performed
and exhausts gas from the vacuum chamber. The vacuum pump apparatus
according to the present embodiment can be suitably used for a
vacuum chamber where a gas inside the vacuum chamber contains solid
foreign materials, particularly in cases where the solid foreign
materials are non-sublimated, but is not limited to this. In
addition, the vacuum pump apparatus according to the present
embodiment can be suitably used for a vacuum chamber where light
gases such as hydrogen occur, but is not limited to this.
[0040] FIG. 1 illustrates a cross section of a vacuum pump
apparatus 100 including an axial line AR1 of a pump rotor 310 of a
pair of pump rotors 310 and 410. FIG. 2 illustrates a cross section
of the vacuum pump apparatus 100 including axial lines AR1 and AR2
as respective rotational centers of the pair of pump rotors 310 and
410. Note that the pump rotor 310 is omitted from FIG. 1 for ease
of illustration. Note also that FIG. 1 also illustrates a block
diagram of a pressure sensor 620 and a control unit 700
constituting the vacuum pump apparatus 100.
[0041] As illustrated in FIGS. 1 and 2, the vacuum pump apparatus
100 includes a pair of main shafts (two rotating shafts) 300 and
400; a pair of pump rotors 310 and 410; a motor 200; a casing 500;
a foreign material capture unit 600; a pressure sensor 620; and a
control unit 700.
[0042] The main shafts 300 and 400 are formed extending in a
direction of the axial lines AR1 and AR2, respectively. The main
shafts 300 and 400 are pivotally supported to the casing 500 by
bearings 302 and 402, respectively. A pair of timing gears 380 and
480 is mounted on the main shafts 300 and 400, respectively. The
main shafts 300 and 400 are rotated in synchronism with power from
the motor 200. The pump rotors 310 and 410 are mounted on the main
shafts 300 and 400 so as to rotate integrally with rotation of the
main shafts 300 and 400, respectively.
[0043] The pair of pump rotors 310 and 410 constitutes a plurality
of compression stages. The pump rotor 310 includes a first stage
rotor (initial stage rotor) 312, a second stage rotor (next stage
rotor) 314, and a third stage rotor 316 (last stage rotor), which
are mounted, spaced apart, on the main shaft 300. In addition, the
pump rotor 410 includes a first stage rotor (initial stage rotor)
412, a second stage rotor (next stage rotor) 414, and a third stage
rotor (last stage rotor) 416, which are mounted, spaced apart, on
the main shaft 400.
[0044] The casing 500 includes a multistage rotor chamber 520, a
suction port 510, an exhaust port 540, and gas flow paths 530 and
532. The casing 500 also includes a shielding portion 580 disposed
between the suction port 510 and inside the first stage rotor
chamber 522, namely, upstream of the first stage rotors 312 and
412.
[0045] The multistage rotor chamber 520 includes a first stage
rotor chamber (initial stage rotor chamber) 522, a second stage
rotor chamber (next stage rotor chamber) 524, and a third stage
rotor chamber (last stage rotor chamber) 526. The first stage rotor
chamber 522, the second stage rotor chamber 524, and the third
stage rotor chamber 526 store the first stage rotors 312 and 412,
the second stage rotors 314 and 414, and the third stage rotors 316
and 416 of the pump rotors 310 and 410, respectively. The first
stage rotor chamber 522 communicates with the suction port 510
connected to a vacuum chamber (unillustrated), and the third stage
rotor chamber 526 communicates with the exhaust port 540. In
addition, the first stage rotor chamber 522 is connected to the
second stage rotor chamber 524 through the gas flow path 530
disposed on an outer peripheral side of the rotor chamber 520.
Likewise, the second stage rotor chamber 524 is connected to the
third stage rotor chamber 526 through the gas flow path 532
disposed on the outer peripheral side of the rotor chamber 520.
According to such a configuration, when a process gas is introduced
from the suction port 510 into the first stage rotor chamber 522,
then the process gas is passed through the gas flow path 530, the
second stage rotor chamber 524, the gas flow path 532, the third
stage rotor chamber 526, in that order, and finally exhausted
outside from the exhaust port 540.
[0046] FIG. 3 is a sectional view schematically illustrating the
inside of the first stage rotor chamber according to the present
embodiment. FIG. 3 illustrates a cross section perpendicular to the
axial lines AR1 and AR2 inside the first stage rotor chamber 522.
The first stage rotors 312 and 412 are disposed to face each other
inside the first stage rotor chamber 522. Minute gaps CF1 and CF2
are formed between the first stage rotors 312 and 412 and between
the first stage rotors 312 and 412 and an inner surface of the
casing 500, respectively. As the main shafts 300 and 400 rotate,
the first stage rotors 312 and 412 rotate in opposite directions to
each other to pump the gas flowed in from the suction port 510. At
this time, the gas is pumped so as to pass through between the
first stage rotors 312 and 412 and the inner surface of the casing
500 without passing through between the first stage rotors 312 and
412 (see bold arrows in FIG. 3).
[0047] A gas inlet to the first stage rotors 312 and 412 includes a
shielding portion 580. When viewed from the suction port 510 to a
gas outlet of the first stage rotor chamber 522 (viewed along a
direction AD in FIG. 3), the shielding portion 580 is disposed so
as to cover a gap CF1 (seal portion) between the first stage rotors
312 and 412. In other words, when viewed from the suction port 510
to the gas outlet of the first stage rotor chamber 522, the
shielding portion 580 is disposed between the main shafts 300 and
400. The shielding portion 580 is preferably formed so that a
boundary between the first stage rotors 312 and 412 is invisible
when viewed from the suction port 510 to the gas outlet of the
first stage rotor chamber 522. The shielding portion 580 may be
formed integrally with the casing 500, or the shielding portion 580
may be made of materials different from those of the casing 500 and
assembled into the casing 500.
[0048] The shielding portion 580 guides the gas sucked from the
suction port 510 into the first stage rotor chamber 522 in a
direction away from the gap CF1 between the first stage rotors 312
and 412. The materials and shape of the shielding portion 580 may
be designed so as to suitably guide the gas. For example, the
shielding portion 580 may be made of a tapered shaped member narrow
on the upstream side and wide on the downstream or may be made of a
curved surface shaped member protruding toward upstream. The thus
made shielding portion 580 can prevent the gas sucked from the
suction port 510 into the first stage rotor chamber 522 from
directly flowing into the gap CF1 between the first stage rotors
312 and 412. If foreign materials are trapped in the gap CF1
between the first stage rotors 312 and 412 which should not be a
gas passage, the first stage rotors 312 and 412 are pushed in a
direction away from each other, resulting in that the first stage
rotors 312 and 412 may contact the casing 500. In contrast to this,
according to the present embodiment, the shielding portion 580 can
prevent foreign materials from being trapped in the gap CF1 between
the first stage rotors 312 and 412 and thus can improve durability
of the vacuum pump apparatus 100.
[0049] FIG. 4 is a sectional view schematically illustrating the
inside of the second stage rotor chamber according to the present
embodiment. Note that FIG. 1 is a sectional view along line I-I of
FIGS. 3 and 4. As illustrated in FIGS. 3 and 4, the second stage
rotors 314 and 414 are disposed to face each other in the second
stage rotor chamber 524 in the same manner as in the first stage
rotor chamber 522. In addition, minute gaps CL1 and CL2 are formed
between the second stage rotors 314 and 414, and between the second
stage rotors 314 and 414 and the inner surface of the casing
500.
[0050] Here, according to the present embodiment, the gap CL1
between the second stage rotors 314 and 414 in the second stage
rotor chamber 524 is smaller than the gap CF1 between the first
stage rotors 312 and 412 in the first stage rotor chamber 522. In
other words, the gap CF1 between the first stage rotors 312 and 412
is formed larger than the gap CL1 between the second stage rotors
314 and 414. The reason for this is to prevent foreign materials
from being trapped in the gap CF1 between the first stage rotors
312 and 412 which should not be a gas passage in the same manner as
the shielding portion 580. The reason for this is also based on
findings that even a larger gap CF1 of the first stage rotor
chamber 522 to be connected to the vacuum chamber little affects
the performance of the vacuum pump apparatus 100. Therefore, the
above described configuration can secure the performance of the
vacuum pump apparatus 100 and can further prevent foreign materials
from being deposited or trapped in the gap CF1 between the first
stage rotors 312 and 412.
[0051] Further, according to the present embodiment, the gap CL2
between the second stage rotors 314 and 414 and the inner surface
of the casing 500 in the second stage rotor chamber 524 is smaller
than the gap CF2 between the first stage rotors 312 and 412 and the
casing 500 in the first stage rotor chamber 522. In other words,
the gap CF2 between the first stage rotors 312 and 412 and the
casing 500 is formed larger than the gap CL2 between the second
stage rotors 314 and 414 and the casing 500. The above described
configuration can secure the performance of the vacuum pump
apparatus 100 and can remarkably prevent foreign materials from
being deposited or trapped in the first stage rotor chamber 522.
Note that according to the present embodiment, a gap in the third
stage rotor chamber 526 located downstream from the foreign
material capture unit 600 is also formed smaller than the gaps CF1
and CF2 in the first stage rotor chamber 522 in the same manner as
the gaps CL1 and CL2 in the second stage rotor chamber 524.
[0052] Now, refer back to FIG. 1. The foreign material capture unit
600 captures foreign materials (for example, solidified materials)
contained in the process gas. As illustrated in FIG. 1, the foreign
material capture unit 600 is disposed in the gas flow path 530
connecting the first stage rotor chamber 522 and the second stage
rotor chamber 524. More specifically, the gas exhausted from the
first stage rotor chamber 522 is passed through the foreign
material capture unit 600 and flowed into the second stage rotor
chamber 524.
[0053] For example, as illustrated in FIG. 5, the foreign material
capture unit 600 includes a cylindrical casing 640 and a filter 650
stored in the casing 640. The filter 650 may be made of porous or
reticulated materials. The filter 650 may be designed so that
foreign materials contained in the process gas are suitably
captured and the resistance in passing through the filter 650 is in
an acceptable range. For example, the filter 650 may be made of
porous materials having holes smaller than foreign materials based
on the foreign materials contained in the process gas. In addition,
the foreign material capture unit 600 may include a plurality of
stages of filters with small resistance so as to reduce the
resistance of the process gas passing therethrough. In addition, as
illustrated in FIG. 6, the foreign material capture unit 600 may
include a casing 640 and a plurality of filters 660 each having a
hole 662. In the example illustrated in FIG. 6, the filters 660 are
stored in the cylindrical casing 640 so that each hole 662 is
disposed at different positions with respect to the flow direction
of the process gas. In the example illustrated in FIG. 6, one hole
662 is formed for each filter 660, but two or more holes 662 may be
formed. In this case, for example, each filter 660 may be stored in
the cylindrical casing 640 so that each hole 662 is disposed at
different positions between adjacent filters 660 with respect to
the flow direction of the process gas.
[0054] The pressure sensor 620 is disposed upstream of the foreign
material capture unit 600 to detect a pressure of the gas flow path
530. More specifically, the pressure sensor 620 is disposed between
the first stage rotor chamber 522 and the foreign material capture
unit 600. The pressure sensor 620 is configured to detect an
exhaust pressure of the first stage rotor chamber 522 and a suction
pressure of the foreign material capture unit 600. The pressure
sensor 620 sends the detected pressure signal of the gas flow path
530 to the control unit 700.
[0055] The control unit 700 not only controls the overall operation
of the vacuum pump apparatus 100 but also functions as a data
storage unit 710, a data analysis unit 720, and a notification unit
730. According to the present embodiment, the control unit 700 is
configured as an information processing apparatus having a CPU and
a memory; and when the CPU executes programs stored in the memory,
the control unit 700 performs the required functions. Note that at
least some of the functions of the control unit 700 may be
implemented by a dedicated hardware circuit. Note also that each
function of the control unit 700 may be distributed across two or
more devices.
[0056] The data storage unit 710 receives a detection signal from
the pressure sensor 620 and stores the detection signal for a
predetermined period of time. The data storage unit 710 stores an
initial value of a pressure detected by the pressure sensor 620.
The initial value is a value actually detected by the pressure
sensor 620 during rated operation while the vacuum pump apparatus
100 is operating in a state in which there is no foreign material
inside the foreign material capture unit 600, or at a time of
replacement or maintenance of the foreign material capture unit
600. The initial value may be measured or stored before the vacuum
pump apparatus 100 is shipped or after the vacuum pump apparatus
100 is installed at a location to be used (for example at a test
operation). Note that the initial value may be a predesigned
value.
[0057] Based on the detection signal from the pressure sensor 620,
the data analysis unit 720 analyzes the deposition state of foreign
materials in the foreign material capture unit 600. According to
the present embodiment, the data analysis unit 720 determines
whether or not a pressure detection value stored for a
predetermined period of time (for example, one hour) in the data
storage unit 710 is different by a predetermined degree from the
initial value stored in the data storage unit 710. If a
determination is made that at least one of the pressure detection
values is different by the predetermined degree from the initial
value, the data analysis unit 720 determines that the foreign
material capture unit 600 needs to be replaced or maintained. Note
that the data analysis unit 720 may use an average value instead of
or in addition to an instantaneous value for analysis.
[0058] The notification unit 730 notifies of the analysis results
by the data analysis unit 720. The notification may be performed by
any method such that the control unit 700 itself may issue an alarm
by sound or screen display or may send an alarm signal to a central
control room. The user of the vacuum pump apparatus 100 can measure
the timing of replacement or maintenance of the foreign material
capture unit 600 based on the notification of the notification unit
730.
[0059] In the vacuum pump apparatus 100, when the motor 200 is
driven, the timing gear 380 and the pump rotor 310 are rotatably
driven. When the timing gears 380 and 480 are engaged with each
other, the pump rotor 410 is also rotatably driven. The pair of
pump rotors 310 and 410 is rotated synchronously in opposite
directions in non-contact by maintaining a minute gap with the
inner surface of the rotor chamber 520, and between the first stage
rotors 312 and 412, between the second stage rotors 314 and 414,
and between the third stage rotors 316 and 416. As the pair of pump
rotors 310 and 410 rotates, the process gas introduced from the
suction port 510 is pumped and sent by the first stage rotors 312
and 412, the second stage rotors 314 and 414, and the third stage
rotors 316 and 416, and then is exhausted from the exhaust port
540.
[0060] According to the vacuum pump apparatus 100 of the above
described present embodiment, the reticulated or porous foreign
material capture unit 600 for capturing foreign materials contained
in the process gas is disposed in the gas flow path 530 between the
first stage rotor chamber 522 and the second stage rotor chamber
524. Thus, the foreign material capture unit 600 does not prevent
suction from the vacuum chamber to the first stage rotor chamber
522. Therefore, the vacuum pump apparatus 100 can reduce the
ultimate pressure inside the vacuum chamber. In addition, the
foreign material capture unit 600 is disposed downstream of the
first stage rotor chamber 522 whose pressure is greater than that
of the suction port 510, thus allowing a simply configured foreign
material capture unit 600 to be used. Furthermore, even if foreign
materials are deposited in the foreign material capture unit 600,
this little affects the suction of the first stage rotor chamber
522, thus reducing frequency of maintenance of the foreign material
capture unit 600.
[0061] In addition, according to the vacuum pump apparatus 100 of
the present embodiment, the foreign material capture unit 600 is
disposed in the gas flow path 530 connecting the multistage rotor
chamber 520 along the two rotating shafts. Thus, for example, a
system for connecting a main pump at a subsequent stage of a
booster pump can reduce the number of elements constituting the
system in comparison with a system for providing the foreign
material capture unit 600 between the booster pump and the main
pump. Therefore, the present embodiment can provide a simplified
configuration including the control system and thus can provide an
inexpensive and compact configuration.
[0062] Furthermore, according to the vacuum pump apparatus 100 of
the present embodiment, the pressure sensor 620 is disposed between
the foreign material capture unit 600 and the first stage rotor
chamber 522, and hence the timing of maintenance of the foreign
material capture unit 600 can be measured based on the detection of
the pressure sensor 620.
[0063] In addition, the vacuum pump apparatus 100 of the present
embodiment includes the shielding portion 580 which covers the gap
between the first stage rotors 312 and 412 when viewed from the
suction port 510 to a gas outlet (exhaust port) of the first stage
rotor chamber 522. Thus, the shielding portion 580 can prevent
foreign materials from directly flowing into the gap CF1 between
the first stage rotors 312 and 412 and can improve durability of
the vacuum pump apparatus 100.
[0064] The vacuum pump apparatus 100 of the above embodiment has
been described as a roots type vacuum pump apparatus, but may be a
claw type vacuum pump apparatus. In addition, the vacuum pump
apparatus 100 has been described to have three compression stages
but may be a multistage vacuum pump apparatus having two or four or
more compression stages, or may be a vacuum pump apparatus having a
single compression stage instead of a plurality of compression
stages.
[0065] The vacuum pump apparatus 100 of the above embodiment has
been described to provide the foreign material capture unit 600 in
the gas flow path 530 between the first stage rotor chamber 522 and
the second stage rotor chamber 524. However, the foreign material
capture unit 600 may be disposed in a gas flow path connecting
between the stages in the multistage rotor chamber 520. For
example, as illustrated by a vacuum pump apparatus 100A of a
modification in FIG. 7, a foreign material capture unit 600A may be
disposed in the gas flow path 532 between the second stage rotor
chamber 524 and the third stage rotor chamber 526. The reason for
this is based on findings that even an increase in gap upstream
near the vacuum chamber between the casing 500 and the pump rotors
310 and 410 in the rotor chamber 520 or a gap between the pump
rotors 310 and 410 little affects the performance of the pump
apparatus 100A. Therefore, the design may be such that the foreign
material capture unit 600A is disposed in the gas flow path between
the stages in the multistage rotor chamber 520, and thereby foreign
materials little affect the upstream side from the foreign material
capture unit 600A and may secure the performance of the pump
apparatus 100A on the downstream side.
[0066] The vacuum pump apparatus 100 of the above embodiment has
been described, focusing on the multistage pump rotors 310 and 410
and the rotor chamber 520 along the two main shafts 300 and 400.
However, the foreign material capture unit 600 may be disposed in a
vacuum pump system having a plurality of compression stages for
vacuum pumping the vacuum chamber. FIG. 8 is a block diagram
schematically illustrating a vacuum pump system according to
another modification. As illustrated in FIG. 8, a vacuum pump
system 100B includes a plurality of compression stages 20 for
vacuum pumping the vacuum chamber 10. The foreign material capture
unit 600 is disposed in a gas flow path 40 between a first
compression stage 20A and a next compression stage 20B connected to
the vacuum chamber 10. Here, the first compression stage 20A may be
a first pump apparatus (for example, a booster pump), and the
compression stage following the next stage may be a second pump
apparatus (for example, a main pump) having a plurality of
compression stages. The above configuration can also exert similar
effects to the above described embodiments.
[0067] The vacuum pump apparatus 100 of the above embodiment has
been described such that the foreign material capture unit 600 has
the reticulated or porous filter 650. However, the foreign material
capture unit 600 is not limited to the above embodiment, but may
have at least one of a trap and a filter. In addition, the foreign
material capture unit 600 may be made of a material such as a
nonwoven fabric having irregularly formed holes.
[0068] The vacuum pump apparatus 100 of the above embodiment has
been described such that the control unit 700 notifies of the
timing of maintenance of the foreign material capture unit 600
based on the detection signal from the pressure sensor 620, but
only the detection value of the pressure sensor 620 may be stored
or notified of. Alternatively, instead of providing the pressure
sensor 620, the timing of maintenance of the foreign material
capture unit 600 may be analyzed based on the ultimate pressure of
the vacuum chamber or the like. Still alternatively, the
maintenance of the foreign material capture unit 600 may be
performed for each predetermined period of time.
[0069] The vacuum pump apparatus 100 of the above embodiment has
been described such that the shielding portion 580 is disposed
upstream of the first stage rotors 312 and 314, but the shielding
portion 580 may not be disposed. In addition, the shielding portion
580 may be applied to a single stage vacuum pump apparatus. In
addition, the shielding portion 580 may be disposed only between
the suction port 510 and the inside of the first stage rotor
chamber 522, or may be disposed upstream of the multistage rotor
chamber 520, for example, as illustrated in FIG. 7. Furthermore, as
illustrated in FIG. 7, the shielding portion 580 is disposed in the
rotor chamber 520 located upstream from the foreign material
capture unit 600 (see the shielding portions 580 and 580A), but may
not be disposed in the rotor chamber 520 downstream.
[0070] The vacuum pump apparatus 100 of the above embodiment has
been described such that the gap CL1 between the second stage
rotors 314 and 414 is smaller than the gap CF1 between the first
stage rotors 312 and 412. In addition, in the radial direction of
the pump rotors 310 and 410 (in the direction perpendicular to the
axial lines AR1 and AR2 of the main shafts 300 and 400), the gap
CL2 between the second stage rotors 314 and 414 and the casing 500
is smaller than the gap CF2 between the first stage rotors 312 and
412 and the casing 500. However, the configuration is not limited
to this embodiment. For example, the gap CL2 between the second
stage rotors 314 and 414 and the casing 500 in a direction of the
axial lines AR1 and AR2 of the main shafts 300 and 400 may be
smaller than the gap CF2 between the first stage rotors 312 and 412
and the casing 500 (see FIG. 2). In addition, at least one of the
gap CF1 between the first stage rotors 312 and 412, and the gap CF2
between the first stage rotors 312 and 412 and casing 500 may be
larger than the gap CL1 between the second stage rotors 314 and 414
and the gap CL2 between the second stage rotors 314 and 414 and the
casing 500. The above configuration can also exert similar effects
to the vacuum pump apparatus 100 of the above embodiments.
[0071] Hereinbefore, the embodiments of the present invention have
been described. The embodiments of the invention described above
are intended to facilitate understanding of the present invention,
but not to limit the present invention. It is readily understood
that the present invention can be modified or improved without
departing from the spirit thereof, and that the present invention
encompasses equivalents thereof. It should be noted that within a
range capable of solving at least some of the above described
problems or within a range of exerting at least some of the
effects, any combination of embodiments and modifications can be
used and any combination of the components described in the scope
of claims and the description can be used or can be omitted.
REFERENCE SIGNS LIST
[0072] 10 vacuum chamber [0073] 20 plurality of compression stages
[0074] 20A first compression stage [0075] 20B next compression
stage [0076] 40 gas flow path [0077] 100 vacuum pump [0078] 300,
400 main shaft [0079] 310, 410 pump rotor [0080] 312, 412 first
stage rotor [0081] 314, 414 second stage rotor [0082] 316, 416
third stage rotor [0083] 500 casing [0084] 510 suction port [0085]
520 rotor chamber [0086] 522 first stage rotor chamber [0087] 524
second stage rotor chamber [0088] 526 third stage rotor chamber
[0089] 530, 532 gas flow path [0090] 540 exhaust port [0091] 580
shielding portion [0092] 600 foreign material capture unit [0093]
620 pressure sensor [0094] 640 casing [0095] 650 filter [0096] 660
filter [0097] 662 hole [0098] 700 control unit
* * * * *