U.S. patent application number 11/130609 was filed with the patent office on 2005-11-24 for dry-running reciprocating vacuum pump.
Invention is credited to Conrad, Armin, Losch, Wolfang.
Application Number | 20050260085 11/130609 |
Document ID | / |
Family ID | 34935651 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050260085 |
Kind Code |
A1 |
Conrad, Armin ; et
al. |
November 24, 2005 |
Dry-running reciprocating vacuum pump
Abstract
A dry-running reciprocating vacuum pump includes at least one
pump stage located in the housing and including a cylinder having
at least one gas inlet, a gas outlet, and a piston reciprocating in
the cylinder and controlling the at least one inlet, a drive system
for driving the piston-driving shaft, which is connected by a crank
gear mechanism with the piston, and including a plurality of
permanent magnets arranged on the shaft and stationary electrical
coils surrounding the permanent magnets for producing a rotatable
magnetic field, and a control electronics located in the pump
housing for operating the coils.
Inventors: |
Conrad, Armin; (Herborn,
DE) ; Losch, Wolfang; (Bad Endbach, DE) |
Correspondence
Address: |
DAVID TOREN, ESQ.
ABELMAN FRAYNE & SCHWAB
666 THIRD AVENUE
NEW YORK
NY
10017-5621
US
|
Family ID: |
34935651 |
Appl. No.: |
11/130609 |
Filed: |
May 17, 2005 |
Current U.S.
Class: |
417/415 ;
417/44.1 |
Current CPC
Class: |
F04B 35/04 20130101;
H02K 1/278 20130101; F04B 2201/1208 20130101; F04B 37/14 20130101;
F04B 7/04 20130101; H02K 7/14 20130101 |
Class at
Publication: |
417/415 ;
417/044.1 |
International
Class: |
F04B 017/00; F04B
035/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2004 |
DE |
10 2004 024 562.2 |
Claims
What is claimed is:
1. A dry-running reciprocating vacuum pump, comprising: a housing;
at least one pump stage located in the housing and including a
cylinder having at least one gas inlet, a gas outlet, and a piston
reciprocating in the cylinder, the at least one inlet being
controlled by the piston; a shaft located in the housing for
driving the piston; a crank gear mechanism connecting the shaft
with the piston, a drive system for driving the shaft and having a
plurality of permanent magnets arranged on the shaft, and
stationary electrical coil means surrounding the permanent magnets
for producing a rotatable magnetic field; and a control electronics
located in the housing for operating the coil means.
2. A dry-running reciprocating vacuum pump according to claim 1,
further comprising sensor means for determining a position of the
shaft.
3. A dry-running reciprocating vacuum pump according to claim 2,
wherein the sensor means comprises Hall sensor means.
4. A dry-running reciprocating vacuum pump according to claim 1,
wherein the control electronics is directly connectable with a
supply network.
5. A dry-running reciprocating vacuum pump according to claim 4,
wherein the control electronics is connectable with one- or
multi-phase voltage between 60V and 400V.
6. A dry-running reciprocating vacuum pump according to claim 1,
wherein the control electronics comprises means for recognizing an
applied network voltage and means for switching voltage
regions.
7. A dry-running reciprocating vacuum pump according to claim 1,
wherein the control electronics comprises a power element for
operating the coil means and forming a thermal contact with a wall
of the pump housing.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a dry-running reciprocating
vacuum pump that includes a housing, at least one pump stage
located in the housing and including a cylinder having at least one
gas inlet, a gas outlet, and a piston reciprocating in the
cylinder, with the at least one inlet being controlled by the
piston, a shaft located in the housing for driving the piston, a
crank gear mechanism connecting the shaft with the piston, and
drive means for driving the shaft.
[0003] 2. Description of the Prior Art
[0004] The last several years, dry-running reciprocating vacuum
pumps such as, e.g., disclosed in U.S. Pat. No. 5,921,755, obtained
an increased commercial importance. They are used for producing low
and high vacuum in the fields where the contamination of recipients
with oil deposites, even in minute amounts, cannot be
tolerated.
[0005] The quality of an obtained vacuum depends on the clearance
or sealing between the piston and the cylinder. It also depends, in
a large degree, on the size of a dead volume. Under the dead volume
is understood, e.g., the volume that is left in the compression
chamber after the piston reached, in its movement, the upper cusp
point and, thereby, the ejection point. The dead volume space
results, e.g., from the valve design.
[0006] After the gases have been ejected or expelled, a suction
process follows during which the piston is displaced away from the
upper cusp point, and the compression chamber volume increases. In
the increased volume of the compression chamber, a strong vacuum is
produced. During the start of the pumping-out process, the piston
is displaced against the atmospheric pressure. As a result, the
pressure between the piston bottom and the piston cover drops by
about 1 Bar. This requires an adequate torque at the drive motor
side in order to be able to displace the piston.
[0007] Often the conventional reciprocating vacuum pumps are so
formed that the space with the crank gear mechanism is also
evacuated in the course of pumping the gas out. During a subsequent
course of pumping-out, this pressure difference is reduced and,
thereby, the requirement to the necessary torque of the drive motor
is also reduced. The available torque depends on the power
consumption of the drive motor.
[0008] The state-of-the art reciprocating vacuum pumps are driven
by alternating current electrical motors. These motors have a low
rotational speed and, correspondingly, a low torque. Therefore,
these motors should be very large, much more powerful than it is
necessary for continuous duty. This results in high operational
costs due to a large but unnecessary energy consumption.
[0009] Further, the over dimension leads to a need in a large space
requirement. However, contrary to this, there is a tendency to form
the pumps as small as possible. Also, the large size of the
electric motor causes an increased vibration of the pump which at
present is tolerated less and less in modern pump stands and plant
equipped with sensitive measuring apparatuses. In many cases, it is
desirable to be able to control the suction capacity of a pump. To
this end, control electronics is needed which further increases
manufacturing costs.
[0010] Accordingly, an object of the invention is a dry-running
reciprocating vacuum pump in which the drawbacks of the
state-of-art pump are eliminated.
SUMMARY OF THE INVENTION
[0011] This and other objects of the present invention, which will
become apparent hereinafter, are achieved by providing a
dry-running reciprocating vacuum pump the drive means of which
includes a plurality of permanent magnets arranged on the pump
shaft and stationary electrical coil means surrounding the
permanent magnets for producing a rotatable magnetic field, and
control electronics located in the housing for operating the coil
means. The inventive reciprocating vacuum pump is driven by a
brushless direct-current motor which is formed by the permanent
magnets, which are secured on the pump, and stationary electrical
coils which produce a rotatable magnetic field. The coils are
controlled and are supplied with current by the control
electronics. The advantage of the inventive motor in comparison
with motors, which are used in conventional pumps, consists in
smaller dimensions of the motor because brushless direct current
motors have a high torque already at a low rotational speed. They
are characterized by a smaller power consumption which reduces
heating of the pump and its vibration. The control electronics,
which powers and controls the coils, can be so formed that it would
control the rotational speed and, thereby, the suction capacity of
the pump.
[0012] The novel features of the present invention, which are
considered as characteristic for the invention, are set forth in
the appended claims. The invention itself, however, both as to its
construction and its mode of operation, together with additional
advantages and objects thereof, will be best understood from the
following detailed description of the preferred embodiment, when
read with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the Drawings:
[0014] Single FIGURE shows a schematic view of a reciprocating
vacuum pump according to the present invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT
[0015] A reciprocating vacuum pump 1 according to the present
invention, which is shown in the drawing, has a housing 2 in which
there is located a shaft 12 supported in bearings 13. On the shaft
12, there is arranged a plurality of permanent magnets 14 which are
surrounded by coils 10 that generates a rotatable magnetic field.
The rotation is produced by an electronic commutation. For
generation of a commutation signal, there is provided control
electronics 8 having a power element 9 for operating the coils 10.
Position sensors 16 permit the control electronic 8 to determine
the shaft angular position. The position sensor 16 can be formed,
e.g., as Hall sensors. The control electronics 8 is located in a
removable housing part and, in addition to the power element 9, has
a control element. The pump 1 can be connected with a voltage
source. As a voltage source, e.g., an industrial voltage network
(24V or 48V), an alternating voltage network of 230V, or any other
conventional supply network can be used. Via a crank gear
mechanism, the shaft 12 drives a piston 20, periodically changing
the volume of a compression chamber 26. The compression chamber 26
is formed by a cylinder in a head of which there are provided a gas
inlet 22 and a gas outlet 24 which are equipped with appropriate
valves. In the lower portion of the cylinder, there is provided a
further gas inlet 23, opening and closing of which is controlled by
the piston 20. The further gas inlet 23 is open only when the
piston 20 reaches the lower cusp point.
[0016] According to an advantageous embodiment of the present
invention, the control electronics 8 is so formed that the
reciprocating vacuum pump 1 can be driven with different rotational
speeds. According to one of the embodiment of the present
invention, the inventive reciprocating vacuum pump is formed as a
multistage reciprocating vacuum pump.
[0017] According to a further embodiment of the present invention,
the control electronic 8 can operate with one- or multi-phase
network voltage between 60V and 400V. A selector switch permits to
select a respective voltage. It is advantageous when the control
electronics 8 is provided with means that automatically recognizes
the supply voltage which is applied. The foregoing means insure
that the inventive dry-running reciprocating vacuum pump can
operate with all voltages used throughout the world. As a result,
high mounting costs can be spared as the pump need not be adapted
to special local conditions. Instead, standard components can be
used for a pump that can operate worldwide.
[0018] As it has already been discussed above, the control
electronics 8 contains a power element 9 for operating the coils
10. It is advantageous when the power element 9 forms a thermal
contact with the wall of the housing 2. In this case, the heat from
the pump 1 is removed by thermal convection, which permits to
eliminate additional cooling means.
[0019] According to one of the embodiment of the invention, the
housing part, which contains the control electronics 8, forms part
of the pump housing 2.
[0020] Though the present invention was shown and described with
references to the preferred embodiment, such is merely illustrative
of the present invention and are not to be construed as a
limitation thereof and various modifications of the present
invention will be apparent to those skilled in the art. It is
therefore not intended that the present invention be limited to the
disclosed embodiment or details thereof, and the present invention
includes all variations and/or alternative embodiments within the
spirit and scope of the present invention as defined by the
appended claims.
* * * * *