U.S. patent application number 09/962446 was filed with the patent office on 2003-02-20 for roots vacuum pump.
Invention is credited to Kim, Deok-Kyeom.
Application Number | 20030035738 09/962446 |
Document ID | / |
Family ID | 19713184 |
Filed Date | 2003-02-20 |
United States Patent
Application |
20030035738 |
Kind Code |
A1 |
Kim, Deok-Kyeom |
February 20, 2003 |
Roots vacuum pump
Abstract
The present invention relates to a roots vacuum pump which is
capable of implementing a good outer appearance and an improved
layout design of a pump by forming a certain path through which a
remaining compression gas is returned to a suction port side of a
roots pump in a housing of a roots pump in the case that a gas
compressed by a roots pump is not fully exhausted by a latter part
pump and remains in an exhaust pot side of the roots pump and is
capable of concurrently operating a roots pump and a latter part
pump. The roots vacuum pump apparatus in which a root pump and a
latter part pump are connected, includes bypass paths formed in at
least one inner surface among the inner surfaces of the front cover
and the rear cover for communicating the suction pot and exhaust
port of the cylinder, and an one-way valve installed in an inlet of
the bypass path contacting with the exhaust port for opening the
bypass path when a pressure of the exhaust port exceeds a certain
level.
Inventors: |
Kim, Deok-Kyeom; (Incheon,
KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
19713184 |
Appl. No.: |
09/962446 |
Filed: |
September 26, 2001 |
Current U.S.
Class: |
417/310 |
Current CPC
Class: |
F04C 23/00 20130101;
F04C 23/005 20130101; F04C 18/126 20130101; F04C 28/26
20130101 |
Class at
Publication: |
417/310 |
International
Class: |
F04B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 2001 |
KR |
2001-48908 |
Claims
What is claimed is:
1. In a roots vacuum pump apparatus in which a suction port and an
exhaust port are formed at both sides of a roots pump cylinder
having a pair of rotors which are supported by a rotary shaft and
are rotated in an engaged state, a front cover and motor fixing
plate are sequentially engaged in one side of the cylinder, and a
rear cover and a gear box are sequentially engaged in the other
side of the same, and an exhaust port is connected with the latter
part pump, a roots vacuum pump apparatus, comprising: bypass paths
formed in at least one inner surface among the inner surfaces of
the front cover and the rear cover for communicating the suction
pot and exhaust port of the cylinder; and an one-way valve
installed in an inlet of the bypass path contacting with the
exhaust port for opening the bypass path when a pressure of the
exhaust port exceeds a certain level.
2. The apparatus of claim 1, wherein said one-way valve includes a
valve guide installed in a wall surface of the cover opposite to
the inlet of the bypass path, a valve member movable based on a
guide of a valve guide for opening and closing the inlet of the
bypass path an opposite direction with respect to the valve guide,
an elastic member disposed between the valve member and the valve
guide for generating a certain elastic force in order for the valve
member to closely contact with the inlet of the bypass path, and an
0-ring formed in a contact surface of the valve member.
3. The apparatus of claim 1, wherein a motor housing is engaged to
one side of the motor fixing plate, and a can housing is engaged in
such a manner that the interior of the motor housing is sealed, and
a stator is installed in the interior of the can housing, and a
motor rotor is fixed in an outer surface of the rotary shaft in
such a manner that the motor rotor is protruded to the outside of
the motor fixing plate for thereby implementing a good sealing
state and an easier attaching and detaching operation of the motor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a roots vacuum pump, and in
particular to an improved roots vacuum pump which is capable of
preventing a pump and motor from being damaged by an exhaust
pressure by implementing a constant exhaust pressure of a roots
pump for thereby significantly decreasing a working time by
concurrently operating a roots pump and a latter part pump.
[0003] 2. Description of the Background Art
[0004] A roots pump apparatus is called as a mechanical booster and
is used for processing a lot of gas at a short time, and an
ultimate pressure is determined based on a latter part pump. The
roots pump is not used lonely.
[0005] Namely, when using the roots vacuum pump
apparatus(hereinafter, the roots vacuum pump apparatus represents a
connection member between the roots pump and the latter part pump),
as shown in FIG. 1, the roots pump and the latter part pump are
connected, and the exhaust rate ratio between the latter part pump
and the roots pump is 1:4-6. When the combined pumps are
concurrently used, the gas sucked and discharged by the roots pump
is not fully exhausted by the latter part pump due to a processing
capacity difference, so that a part of compression gas remains in a
portion between an exhaust port of the rots pump and a suction port
of the latter part pump.
[0006] When the gas discharged from the roots pump is not fully
exhausted and remains in the portion between the latter part pump
and the roots pump, as the roots pump is operated, the pressure in
the outlet side of the roots pump is gradually increased. Finally,
the roots pump is over-loaded by a high pressure, so that the parts
of the rotor of the roots pump and the motor are damaged.
[0007] In order to overcome the above problems, a certain work is
processed using the latter pat pump with respect to a pressure
under a vacuum degree of about 10 Torr of the vacuum facility. The
above-described sequential driving method of the pump requires a
long working time since the roots pump and the latter pumps are
concurrently operated, and the structure of the vacuum system is
complicated.
[0008] In another example, the compression gas which is not
exhausted by the latter part pump and remains in a portion near of
the exhaust port of the roots pump is guided to the suction port of
the roots pump through a bypass return line 101 by opening a check
valve 100 in order to enhance an efficiency by concurrently
operating the roots pump and the latter part pump for thereby
preventing an over load.
[0009] However, in the above return method of the remaining
compression gas requires an external bypass return line 101 of the
roots pump, an outer apparance is bad and causes an interference
with another structure of the pump, so that when designing the
system, a layout of the system is limited.
SUMMARY OF THE INVENTION
[0010] Accordingly, it is an object of the present invention to
provide a roots vacuum pump which overcomes the problems
encountered in a conventional cylinder structure.
[0011] It is another object of the present invention to provide a
roots vacuum pump which is capable of implementing a good outer
appearance and an improved layout design of a pump by forming a
certain path through which a remaining compression gas is returned
to a suction port side of a roots pump in a housing of a roots pump
in the case that a gas compressed by a roots pump is not fully
exhausted by a latter part pump and remains in an exhaust pot side
of the roots pump and is capable of concurrently operating a roots
pump and a latter part pump.
[0012] To achieve the above object, there is provided a roots
vacuum pump which includes bypass paths formed in at least one
inner surface among the inner surfaces of the front cover and the
rear cover for communicating the suction pot and exhaust port of
the cylinder, and an one-way valve installed in an inlet of the
bypass path contacting with the exhaust port for opening the bypass
path when a pressure of the exhaust port exceeds a certain level in
the roots vacuum pump apparatus in which a suction port and an
exhaust port are formed at both sides of a roots pump cylinder
having a pair of rotors which are supported by a rotary shaft and
are rotated in an engaged state, a front cover and motor fixing
plate are sequentially engaged in one side of the cylinder, and a
rear cover and a gear box are sequentially engaged in the other
side of the same, and an exhaust port is connected with the latter
part pump.
[0013] The one-way valve includes a valve guide installed in a wall
surface of the cover opposite to the inlet of the bypass path, a
valve member movable based on a guide of a valve guide for opening
and closing the inlet of the bypass path an opposite direction with
respect to the valve guide, an elastic member disposed between the
valve member and the valve guide for generating a certain elastic
force in order for the valve member to closely contact with the
inlet of the bypass path, and an O-ring formed in a contact surface
of the valve member.
[0014] In addition, in the present invention, a motor housing is
engaged to one side of the motor fixing plate, and a can housing is
engaged in such a manner that the interior of the motor housing is
sealed, and a stator is installed in the interior of the can
housing, and a motor rotor is fixed in an outer surface of the
rotary shaft in such a manner that the motor rotor is protruded to
the outside of the motor fixing plate for thereby implementing a
good sealing state and an easier attaching and detaching operation
of the motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will become better understood with
reference to the accompanying drawings which are given only by way
of illustration and thus are not limitative of the present
invention, wherein;
[0016] FIG. 1 is a view illustrating an example of use of a
conventional roots vacuum pump;
[0017] FIG. 2 is a cross-sectional view illustrating a roots vacuum
pump according to the present invention;
[0018] FIG. 3 is a cross-sectional view taken along line A-A of
FIG. 2;
[0019] FIG. 4 is a cross-sectional view taken along line B-B of
FIG. 2;
[0020] FIG. 5 is a cross-sectional view taken along line C-C of
FIG. 2; and
[0021] FIGS. 6 and 7 are views illustrating an operation state of a
valve adapted to a roots vacuum pump according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The embodiments of the present invention will be explained
with reference to the accompanying drawings.
[0023] In the drawings, reference numeral 1 represents a cylinder
of a roots pump, and a suction port 11 and an exhaust port 12 are
formed in the upper and lower sides of the cylinder 1, and a pair
of rotors 13 are installed in the interior of the cylinder 1 and
are supported by a rotary shaft 56.
[0024] As the rotors 13 are engaged each other and are rotated, a
gas is sucked from a vacuum facility through the suction port 11
and is exhausted to the side of the exhaust port 12.
[0025] In a canned motor 51, a motor rotor 55 is fixed at an outer
surface of the rotary shaft 56 protruded to an outer portion of a
motor fixing plate 5, and a sealed can housing 53 is formed in the
inner side of a motor housing 52. A stator 54 is fixed in the
interior of the can housing 53, so that the canned motor 51 is
easily engaged by engaging the motor housing 52 to the motor fixing
plate 5.
[0026] Since the can housing 53 and the motor housing 52 are
module-engaged, the motor housing 52 is engaged to the motor fixing
plate 5 using a bolt for thereby completing an engagement of the
motor. It is possible to easily disassembly the motor by separating
the motor housing 52 from the motor fixing plate 5.
[0027] In addition, a cooling fan 58 is formed in the latter part
of the motor housing 52 for preventing an over-heating of the
motor, so that even when the canned motor 51 is operated for a long
time, it is not over-headed and damaged. A cylindrical can 75
sealingly separates the stator 54 and the motor rotor 55 for
thereby implementing a sealed state in the pump.
[0028] A rear cover 3 and a gear box 4 are sequentially installed
in the other side of the cylinder 1. A gear apparatus is installed
in the interior of the gear box 4 for thereby uniformly supplying a
driving force to the rotors 13.
[0029] In the present invention, as a unit for preventing the gas
pressure in the side of the exhaust port 12 of the cylinder 1 from
being over-increased, a bypass path is formed in either a front
cover 2 or the rear cover 3. In this embodiment of the present
invention, first and second bypass paths 21 and 31 are formed in
the front cover 2 and the rear cover 3, respectively.
[0030] The first bypass path 21 is formed in the interior of the
front cover 2 for connecting the suction port 11 and the exhaust
port 12, and an inlet 22 of the first bypass path 21 communicates
with an outlet 12 of the cylinder 1, and the outlet 23 of the first
bypass path 21 communicates with the suction port 11 of the
cylinder 1.
[0031] In addition, the second bypass path 31 is formed in the
interior of the rear cover 3 for connecting the suction port 11 and
the exhaust port 12, and an inlet 32 of the second bypass path 21
communicates with the exhaust port 12, and the outlet 33 of the
same communicates with the suction port 11 of the cylinder 1.
[0032] One-way valves 60 and 62 are formed in the inlets 22 and 32
of the bypass paths 21 and 31, and a valve guide 62 is installed in
a wall surface of the front cover 2 and the rear cover 3 opposite
to the inlets 22 and 32 of the first and second bypass paths 21 and
31, and an opening and closing valve member 63 which is moved along
the valve guide 62 is formed in a portion opposite to the valve
guide 62. An elastic member 64 is installed between the valve
member 63 and the valve guide 62 for applying a certain elastic
force thereto, so that the valve member 63 blocks the inlets 22 and
32 of the bypass paths 21 and 31 by an elastic force of the elastic
member 64.
[0033] An O-ring 65 is installed in a sealed surface of the valve
member 63, namely, in the wall surface of the inlets 22 and 32.
Therefore, when the valve member 63 blocks the inlets 22 and 32, a
sealing ratio is significantly increased by the O-ring 65.
[0034] A filter 71 is formed in the upper wall surface of the gear
box 4 for filtering a foreign substance from the oil and gas. An
outlet of the filter 71 is connected with the second bypass path
21, and a communication hole 74 is formed in the contact surface
between the gear box 4 and the rear cover 3. A connection path 74
which connects the interior of the gear box 4 and the interior of
the motor fixing plate 5 is formed in an inner wall surface of the
cylinder 1 as shown in FIG. 3. A nozzle hole 72 having a certain
size which connects the interior of the gear box 4 and the filter
71 is formed in the wall surface of the gear box 4.
[0035] When the vacuum pump apparatus is operated, the air or gas
in the interiors of the motor fixing plate 5 and the gear box 4 is
supplied to the filter 71 through the nozzle hole 72 based on a
suction force, and the gas or gas which passes through the filter
71 is exhausted to the second bypass path 31 through the
communication hole 74, so that the interiors of the gear box 4 and
the motor fixing plate 5 maintain a certain vacuum state, whereby
an oil lubricating various friction parts is prevented from being
polluted by a foreign substance for thereby decreasing an abrasion
ratio of the friction parts.
[0036] In the drawings, reference numeral 57 represents a bearing
which rotatably supports the rotary shaft 56.
[0037] The operation of the present invention will be
explained.
[0038] When a power is supplied to a root vacuum pump apparatus,
and the canned motor 51 is driven, the rotor 13 is rotated, and the
gas is sucked from the vacuum facility through the suction port 11
and is exhausted to the side of the exhaust port 12. The gas
exhausted to the exhaust port 12 is sucked by a latter part
pump(not shown) and compressed and exhausted to the outside.
[0039] At this time, at an initial operation stage of the
apparatus, the gas exhausted to the exhaust port 12 is not fully
supplied to the latter part pump side due to a large processing
capacity difference between the roots pump and the latter part
pump, but remains between the exhaust port 12 and the latter part
pump.
[0040] As the gas is gradually gathered in the exhaust port 12, the
gas pressure is increased. At the time when the pressure of the gas
exceeds the elastic force of the elastic member 64 which
elastically supports the valve member 63, the valve member 63
compresses the elastic member 64 and moves for thereby opening the
inlets 22 and 32 of the first and second bypass paths 21 and
31.
[0041] As shown in FIG. 7, the inlets 22 and 32 are opened, the gas
in the exhaust port 12 is bypassed to the suction port 11 of the
cylinder 1 through the bypass paths 21 and 31 and is recirculated
for thereby decreasing the gas pressure in the side of the exhaust
port 12.
[0042] When the gas pressure in the side of the exhaust port 12 is
decreased, the valve member 63 is forwardly moved by an elastic
force of the elastic member 64 for thereby blocking the inlets 21
and 31 of the first and second bypass paths 21 and 31 as shown in
FIG. 6.
[0043] When the valve member 63 blocks the inlets 21 and 31, since
the O-ring 65 closely contacts with the inlets 21 and 31 for
thereby implementing a good sealing state.
[0044] As the gas is gathered in the side of the exhaust port 12,
whenever the gas pressure is increased, the valve member 63 is
opened, and the gas is recirculated in the direction of the suction
port 11. Therefore, the gas pressure in the side of the exhaust
port 12 of the cylinder 1 maintains a certain pressure for thereby
preventing a certain damage of the pump and motor. In addition,
since the roots vacuum pump and latter part pump are concurrently
operated, it is possible to decrease the working time.
[0045] In addition, since the bypass paths are formed in the
interiors of the front cover and rear cover, respectively, an outer
appearance of the roots vacuum pump is good, and the size of the
pump is decreased.
[0046] As described above, in the present invention, the bypass
paths are formed in the interiors of the front cover and the rear
cover for connecting the suction port side and the exhaust port
side of the roots pump cylinder. An one-way valve which is
automatically opened and closed when an exhaust pressure in the
side of the exhaust of the cylinder exceeds a certain reference
value is formed in the inlet of the bypass path, so that it is
possible to prevent a certain dampage of the pump apparatus and the
motor due to the over load by bypassing the remaining compression
gas which is not processed by the latter part pump to the side of
the roots pump suction port. In addition, in the present invention,
since the roots pump and the latter pat pump which have a large
capacity difference are concurrently processed, it is possible to
significantly decrease the working time, and since the bypass paths
are formed in the pump housing, not in the outside of the system,
an outer appearance looks good, and the layout of the design is not
limited.
[0047] As the present invention may be embodied in several forms
without departing from the spirit or essential characteristics
thereof, it should also be understood that the above-described
embodiments are not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be
construed broadly within its spirit and scope as defined in the
appended claims, and therefore all changes and modifications that
fall within the meets and bounds of the claims, or equivalences of
such meets and bounds are therefore intended to be embraced by the
appended claims.
* * * * *