U.S. patent application number 15/568846 was filed with the patent office on 2018-04-26 for vacuum pump system.
The applicant listed for this patent is Leybold GmbH. Invention is credited to Thomas Dreifert, Roland Muller, Max Pelikan, Dirk Schiller, Daniel Schneidenbach, Dirk Stratmann.
Application Number | 20180112666 15/568846 |
Document ID | / |
Family ID | 54262130 |
Filed Date | 2018-04-26 |
United States Patent
Application |
20180112666 |
Kind Code |
A1 |
Dreifert; Thomas ; et
al. |
April 26, 2018 |
VACUUM PUMP SYSTEM
Abstract
A vacuum pump system comprising a plurality of vacuum pumps
which are connected to one another in parallel and are each
connected on an inlet side to a chamber, having an outlet line
which is connected on the outlet side of the vacuum pumps, and an
intermediate line which connects the inlet side of at least one
vacuum pump to the outlet line, wherein all the vacuum pumps are
connected in parallel during a pumping-out period and at least one
of the vacuum pumps is connected in parallel with the other vacuum
pumps as a backing pump during an idle period.
Inventors: |
Dreifert; Thomas; (Kerpen,
DE) ; Muller; Roland; (Koln, DE) ; Pelikan;
Max; (Bornheim, DE) ; Schiller; Dirk; (Hurth,
DE) ; Schneidenbach; Daniel; (Koln, DE) ;
Stratmann; Dirk; (Bergheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Leybold GmbH |
Koln |
|
DE |
|
|
Family ID: |
54262130 |
Appl. No.: |
15/568846 |
Filed: |
June 20, 2016 |
PCT Filed: |
June 20, 2016 |
PCT NO: |
PCT/EP2016/064163 |
371 Date: |
October 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 37/14 20130101;
F04C 28/26 20130101; F04B 49/06 20130101; F04B 41/06 20130101; F04C
28/02 20130101; F04C 28/06 20130101; F04C 23/001 20130101; F04C
2240/70 20130101; F04C 25/02 20130101; F04C 28/065 20130101 |
International
Class: |
F04C 28/06 20060101
F04C028/06; F04C 25/02 20060101 F04C025/02; F04C 28/02 20060101
F04C028/02; F04C 28/26 20060101 F04C028/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2015 |
DE |
20 2015 004 596.0 |
Claims
1. A vacuum pump system having a plurality of vacuum pumps which
are connected in parallel with each other and are each connected on
an inlet side with a chamber, having an outlet line which is
connected with the outlet side of said vacuum pumps, and an
intermediate line connecting the inlet side of at least one vacuum
pump with said outlet line, wherein during a pumping-out period all
vacuum pumps are connected in parallel, and during an idle period
the inlet side of at least one of said vacuum pumps is connected
with the outlet side of the remaining vacuum pumps as a backing
pump.
2. The vacuum pump system according to claim 1, wherein during the
idle period the vacuum pump whose inlet side is connected with the
outlet side of the remaining vacuum pumps is connected in series
with the other vacuum pumps.
3. The vacuum pump system according to claim 1, wherein the outlet
side of the vacuum pump is connected with the outlet line via a
check valve.
4. The vacuum pump system according to claim 1, wherein in front of
each of the vacuum pumps a valve is arranged, as well as in
particular another valve is arranged in the intermediate line for
controlling a parallel or series connection of the individual
vacuum pumps with each other.
5. The vacuum pump system according to claim 1, wherein the at
least one of the vacuum pumps whose inlet side is connected with
the outlet side of the remaining vacuum pumps in the idle state and
which is in particular connected in series with the other vacuum
pumps is smaller dimensioned than the other vacuum pumps.
Description
BACKGROUND
1. Field of the Disclosure
[0001] The present disclosure relates to a vacuum pump system for
evacuating a chamber, in particular a process or lock chamber.
2. Discussion of the Background Art
[0002] Vacuum pump systems for regularly evacuating large chambers
are known from prior art, FIG. 1. Frequently, vacuum pumps
operating in a dryly compressing manner are used for this purpose.
As a rule, these are combinations of backing pumps, such as screw
pumps, claw pumps or multi-stage Roots pumps, and
parallel-connected Roots pumps. In large pump systems a plurality
of pumps and a plurality of Roots pumps are connected in
parallel.
[0003] Typically such pump systems are used in lock chambers, for
example loadlock or unloadlock, e. g. in coating plants. In these
plants a chamber must be pumped down from atmospheric pressure to a
transfer pressure of typically approximately 0.1 mbar to 10 mbar
within a short period of time, e. g. a pumping-down period of 20
seconds to 120 seconds. Subsequently, a vacuum pump is separated
from the chamber to be evacuated by a valve on the inlet side and
operates for a certain period of time, typically one to ten times
the pumping-out time, in discharge pressure operation.
[0004] Further typical applications are large process chambers for
heat treatment or refinement of metals. In this case typical
pumping-out periods are 2 to 30 minutes. Thereafter a low gas flow
must continue to be pumped out, which is however considerably
smaller than the gas flow necessary for realizing the pumping-out
period. A typical hold period for this operating pressure amounts
to two to ten times the pumping out period.
[0005] In such applications the vacuum pump system must be very
largely dimensioned for realizing the short pumping-out period.
During an idle period and/or during a hold period large suction
capacities of the pump systems are however not necessary.
Consequently, during an idle and/or during a hold period an
unnecessarily high energy expenditure of the pump is required.
[0006] For reducing a high power consumption of pump systems during
the idle and/or hold period different approaches are known.
[0007] Some pump systems having backing and/or Roots pumps are
temporarily shut down. In this case it is disadvantageous that the
pumps become cold which has a negative effect on the service life
of the components. Further, linings may stick together and block
the rotors. During short idle and/or hold periods the pumps must
frequently be accelerated again which requires more power and very
largely dimensioned motors. It is therefore not common practice to
shut down pumps.
[0008] Further it is known from prior art that on the outlet side
of each backing pump an additional small auxiliary pump is
connected in series, FIG. 3. This may e. g. be an ejector pump or
another smaller backing pump. Parallel to the auxiliary pump a
switch valve or a check valve having an adequate cross section must
normally be arranged in order to avoid too high pressures between
the backing and auxiliary pumps during the pumping-out period.
These solutions are disadvantageous because of the large number of
additional pumps. Moreover, very small auxiliary pumps, such as
ejector pumps, for example, cannot reduce the outlet pressure of
the backing pump rapidly enough for attaining adequate power
savings during short idle and/or hold periods. Further, the
auxiliary pumps require energy for operation.
[0009] Another solution which is known from prior art is that on
the outlet side of the backing pump a small number of further large
backing pumps may be arranged as large auxiliary pumps, FIG. 2.
They are connected in series with the backing pumps via a pipeline
system. In this case, too, at least one valve having an adequate
cross section must normally be arranged parallel to the auxiliary
pump for avoiding high pressures between the backing and auxiliary
pumps during the pumping-out period. This solution is
disadvantageous due to the additional purchase and operating costs
as well as the space required for the auxiliary pumps.
[0010] It is an object of the present disclosure to provide an
improved pump system which consumes less power, in particular
during the idle and hold periods.
SUMMARY
[0011] This object is achieved with a pump system having a
plurality of vacuum pumps which are connected in parallel with each
other and are each connected to a chamber at their inlet side, FIG.
4. The pump system further comprises an outlet line which is
connected to the outlet side of the vacuum pumps. In addition, the
pump system comprises an intermediate line which connects the inlet
side of at least one of the vacuum pumps with the outlet side.
During a pumping-out period all vacuum pumps are connected in
parallel and during an idle and/or hold period at least one of the
vacuum pumps is connected in series with the other vacuum pumps as
a backing pump.
[0012] Due to the parallel connection of all vacuum pumps of a pump
system during the pumping-out period the full suction capacity is
available for the pumping-out process. The vacuum pump system
further comprises switchover means both in connections of the inlet
sides to the chambers and in an intermediate line. These switchover
means may comprise valves, for example. During an idle and/or hold
period thus one of the vacuum pumps can be connected in series with
the other vacuum pumps as a backing pump. This is realized by a
corresponding arrangement of the switchover means such that they
block or release the connection in such a way that the vacuum pumps
are connected in series or in parallel to each other in a different
manner. Thereby the outlet pressure of the vacuum pumps is rapidly
decreased and the power consumption is considerably reduced.
However, the pumps continue to operate such that they can be used
for the next pumping-out cycle without any loss of time.
[0013] Shutting down of certain pumps is thus not necessary such
that the pumps remain warm and continue to be fully operable.
Another advantage results from the drives not having to be designed
for frequent accelerations and no additional pumps being required.
An additional expenditure for the pump system according to the
disclosure is merely limited to relatively small dimensioned
pipelines and switchover means, for example valves, as well as
modifications to a pump control unit.
[0014] Due to the reduced energy expenditure of the pump system the
pumps are operated in a relatively cold state such that the service
life of normal wear parts is significantly increased, for example
oil, bearings, seals, power electronics in the drive unit. Further,
due to this reduced energy expenditure attributable to reduced
waste heat the costs for air-conditioning of the installation site
and cooling of the pumps are reduced. Due to the reduced pressure
in the outlet during operation condensation of vapors in the pumps
is also avoided, whereby damage caused by corrosion can be
reduced.
[0015] In the case where at least one vacuum pump can be connected
in series as a backing pump a very low discharge and/or operating
pressure can be attained.
[0016] Thus particular process steps can be made possible without
any additional pumps. For example, leak detection in the plant
prior to the actual process operation is thus possible since a leak
detection normally requires a low operating pressure. During an
idle and/or hold period realized according to the disclosure, the
sound level of a pump system decreases since most of the pumps have
a lower noise emission at a reduced load.
[0017] The pump system according to the disclosure allows for a
high redundancy since even if individual pumps in such a group fail
the process is allowed to be continued. Thus all pumps can fulfill
their tasks even without any auxiliary pumps. In addition, a
plurality of pumps may be incorporated in such a way that they can
be used as an auxiliary pump. Besides a reduction of the power
consumption and thus reduced operating costs, the CO.sub.2
footprint for such an application according to the disclosure is
improved.
[0018] For the operation according to the disclosure it is
particularly preferred that the vacuum pumps which are to be
connected in series as backing pumps meet certain technical
requirements. It is particularly preferred that these vacuum pumps
are sealed such that they can reliably operate at strongly reduced
outlet pressures without any gas or oil leakage. Particularly
preferred are outlet pressures of the backing pumps during idle
and/or hold operation in a range of 10 mbar to 500 mbar. Further,
it is particularly preferred that the thermal behavior of the pumps
reliably allows for operation at a strongly reduced outlet
pressure. This aspect relates in particular to the gap heights, the
oil viscosity and the lubrication of bearings.
[0019] In addition, it is particularly preferred that
oil-lubricated spaces are sealed towards a working space such that
even at very rapid cycles no strong oil spreading takes place. In
addition, shaft seals are preferably to be configured such that
they do not prematurely suffer from wear caused by rapidly changing
pressure differences. One possibility in this respect is the use of
compensation lines between oil-lubricated spaces and the working
space which comprise an oil separator.
[0020] Further advantageous configurations and modifications are
shown in the following figures. However, the respective resultant
features are not limited to the individual figures or
configurations. Rather, one or more features of the above
description can be combined with individual or a plurality of
features of the figures for providing further modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In the figures:
[0022] FIGS. 1 to 3 show embodiments according to examples of prior
art, and
[0023] FIGS. 4 to 6 show exemplary embodiments according to the
disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] FIG. 1 shows a vacuum pump system 1 having a lock chamber 10
and parallel-connected pumps P1-P5 each of which is connected on
its inlet side with the lock chamber. In addition, the vacuum pump
system 1 comprises valves V1-V5, by means of which the connection
from the pump inlets of the pumps P1-P5 to the lock chamber 10 can
be disconnected. The illustrated vacuum pump system is known from
prior art. During a pumping-out period the valves V1-V5 are open.
The pumps P1-P5 consume a lot of power during the pumping-out
period and operate at full speed. The pressure in the lock chamber
decreases continuously.
[0025] During an idle period the valves V1-V5 are dosed and the
pumps P1-P5 operate at full speed, wherein the power consumption
essentially corresponds to that of the operation at a discharge
pressure and continues to be relatively high. The pressure in the
lock chamber is equal to a transfer pressure.
[0026] During a hold period the valves V1-V5 are open and the pumps
P1-P5 operate at a low operating pressure.
[0027] The vacuum pump system illustrated in FIG. 2 is known from
prior art. The pump system is extended by a relatively largely
dimensioned auxiliary pump P26 as well as by the check valves
CV1-CV5.
[0028] The parallel-connected pumps P21-P25 are connected with a
chamber 20. During a pumping-out period both the valves V21-V25 and
the check valves CV21-CV25 are open. The inlet pressure of the
additional auxiliary pump P26 is approximately equal to the outlet
pressure of the auxiliary pump.
[0029] During an idle period the valves V21-V25 are closed.
Subsequently, the check valves CV21-CV25 are also closed. During
this operation the inlet pressure of the auxiliary pump P26 is
considerably lower than the outlet pressure of the auxiliary pump
P26.
[0030] FIG. 3 shows a prior art configuration of a vacuum pump
system for a lock chamber 30 having small auxiliary pumps P33 and
P34. An ejector pump may be selected as the auxiliary pump, for
example.
[0031] During a pumping out period the valves V31 and V32 as well
as the check valves CV31 and CV32 are open. The inlet pressures of
the auxiliary pumps P33 and P34 are approximately equal to the
outlet pressures of the auxiliary pumps P33 and P34.
[0032] During an idle period of the pump system 3 the valves V31
and V32 are closed.
[0033] The check valves CV31 and CV32 are also closed during an
idle period. The outlet pressures of the auxiliary pumps P33 and
P34 are substantially larger than the inlet pressures of these
auxiliary pumps P33 and P34 during the idle period.
[0034] FIGS. 4 to 6 show configurations of the vacuum pump system
according to the disclosure.
[0035] The vacuum pump system shown in FIG. 4 comprises five
parallel-connected vacuum pumps P41, P42, P43, P44, P45. The inlets
of the vacuum pumps P41, P42, P43, P44, P45 are connected with a
vacuum chamber 40. Between the respective vacuum pumps P41, P42,
P43, P44, P45 a valve V41, V42, V43, V44, V45 is provided. The
outlet sides of the pumps P41, P42, P43, P44, P45 are connected
with a common outlet 41 via check valves CV41 CV42, CV43 CV44,
CV45.
[0036] In a connecting line 42 in which a valve V46 is arranged the
pump P41 can be connected in series with the pumps P42, P43, P44,
P45 in the exemplary embodiment of the vacuum pump system of FIG.
4.
[0037] The vacuum pump P41 which is to be used as a backing or as
an auxiliary pump can generally be smaller designed than the other
vacuum pumps. Thus the power consumption during the idle and/or
hold operation is further reduced. FIG. 4 shows a vacuum pump
system where the valves V41-V45 are open and the valve V46 is
closed during a pumping-out period. In addition, the check valves
CV41-CV45 are open during the pumping-out period.
[0038] During the idle period the valves V41-V45 are closed, V46 is
open. The check valve CV41 is also open during this operation as
long as the pump system is evacuated by the pump P41. Thereafter it
is closed. The check valves CV42-CV45 are closed during the idle
operation. The reduction of the power consumption in the idle state
amounts to up to 40% in some exemplary embodiments. In particular,
the described series connection of the vacuum pump as a backing
pump can also be used for improving the feed of light gases. In
addition, this pump connection can also be used for regulating the
chamber pressure or the process flow. The auxiliary pump ensures
that the operating pressure range is reliably reached. The backing
pumps can then be reliably regulated in a very large speed
range.
[0039] FIG. 5 illustrates a minimal configuration for lock chambers
in the exemplary embodiment of FIG. 5 a pump system merely having
two vacuum pumps P51, P52 is selected as an example. They comprise
a common inlet line which is connected with a vacuum chamber 50 via
a valve V52. Merely the outlet of the vacuum pump P52 is connected
with the common outlet 51 via a check valve CV51. The outlet of the
pump P51 is directly connected with the common outlet 51. Via an
additional line 52 in which a valve V51 is arranged and which
extends from the outlet of the pump P52 to the inlet of the pump
P51 the pump P51 can evacuate the other pump P52 from both sides
during the idle period. In the example of FIG. 5 the pumps P51 and
P52 can however not be connected in series.
[0040] Similar to FIG. 5, FIG. 6 shows a minimal configuration for
process chambers. During the hold period V61 is open such that P62
and P61 are evacuated from both sides. During the pumping-out
period V6 is closed such that the process chamber can be evacuated
within a short period of time. In both configurations of the vacuum
pump systems 5 and 6 further pumps can be connected in parallel
with the pumps P52 and P62 and operated accordingly.
[0041] The solutions described here can be realized for
combinations with two or more backing pumps. The respective number
and size of the pumps can be freely adapted to the application. The
Roots pumps connected in series with the backing pumps have
generally no influence on the solutions. Therefore they have net
been illustrated in the examples.
* * * * *