U.S. patent application number 12/001908 was filed with the patent office on 2008-06-19 for vacuum pump with a hood.
This patent application is currently assigned to Pfeiffer Vacuum GmbH. Invention is credited to Gernot Bernhardt, Juergen Wagner.
Application Number | 20080145243 12/001908 |
Document ID | / |
Family ID | 39217910 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080145243 |
Kind Code |
A1 |
Bernhardt; Gernot ; et
al. |
June 19, 2008 |
Vacuum pump with a hood
Abstract
A vacuum pump includes a pumping system (30) located in a pump
housing (1) and a hood (1) at least partially surrounding the pump
housing at least in the region of the pumping system to provide for
at least partial dissipation of heat generated in the pumping
system.
Inventors: |
Bernhardt; Gernot;
(Huettenberg, DE) ; Wagner; Juergen;
(Mueschenbach, DE) |
Correspondence
Address: |
ABELMAN, FRAYNE & SCHWAB
666 THIRD AVENUE, 10TH FLOOR
NEW YORK
NY
10017
US
|
Assignee: |
Pfeiffer Vacuum GmbH
|
Family ID: |
39217910 |
Appl. No.: |
12/001908 |
Filed: |
December 12, 2007 |
Current U.S.
Class: |
417/372 |
Current CPC
Class: |
F04C 2220/10 20130101;
F04C 2240/30 20130101; F04C 29/047 20130101; F04C 18/3442 20130101;
F04C 2240/808 20130101 |
Class at
Publication: |
417/372 |
International
Class: |
F04B 39/06 20060101
F04B039/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 13, 2006 |
DE |
10 2006 058 840.1 |
Claims
1. A vacuum pump, comprising a housing having inlet and outlet; a
pumping system located in the housing; a motor for driving the
pumping system and likewise located in the housing; and a hood at
lest partially surrounding the pump housing.
2. A vacuum pump according to claim 1, further comprising an
intermediate member located between the hood and the housing.
3. A vacuum pump according to claim 2, wherein the intermediate
member is formed of a vibration-damping material.
4. A vacuum pump according to claim 3, wherein the
vibration-damping material has heat insulation properties, so that
the intermediate member forms a heat barrier between the pump
housing and the hood.
5. A vacuum pump according to claim 2, wherein the intermediate
member includes elastomeric components.
6. A vacuum pump according to claim 1, wherein the pump housing is
provided with cooling ribs, wherein the vacuum pump further
comprises a fan for generating a cooling blow, and wherein the hood
guides the cooling flow, which is generated by the fan, at least to
a portion of the cooling ribs.
7. A vacuum pump according to claim 6, wherein the fan is arranged
behind the hood.
8. A vacuum pump according to claim 7, wherein the hood has at
least one opening through which air is aspirated by the fan.
9. A vacuum pump, according to claim 1, wherein the pump housing is
formed of a plurality of housing sections, wherein the pump further
comprises control electronics, and wherein the pumping system and
the control electronics are located in different housing
sections.
10. A vacuum pump according to claim 1, wherein the pumping system
includes means for compressing gas from at least one of low and
high vacuum range and for discharging a compressed gas against
atmosphere.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a vacuum pump having a
housing which has inlet and outlet and in which a pumping system
and a motor for driving the pumping system are located.
[0003] 2. Description of the Prior Art
[0004] Vacuum pumps generate heat in their interior as a result of
compression therein of pumped gases. However, the gas compression
is not the only source of heat in the vacuum pumps. In most cases,
the vacuum pumps includes movable parts driven by respective
drives. These drives have all a certain efficiency level so that a
power dissipation takes place which, as a rule, is converted into
heat. Heat is also generated as result of friction in the bearings
and by other sources. The generated heat is released into the
environment and presents a source of danger for a pump user.
[0005] Therefore, there is a need to protect the vacuum pump user.
In state of the art, the pumps are provided with handles which can
be used by a pump user for displacing a pump shortly after start of
the pump operation, i.e., in a heated condition. However, the
handles do not provide protection against a contact with the pump
and are, therefore, not satisfactory. Another solution is suggested
in European Publication EP-A 1 696 132. This solution consists in
enclosing the entire vacuum pump in an external housing that
surrounds the pump housing. This solution is associated with high
costs and presents a problem from the point of view of access to
the operational elements of the pump. Further, there is a danger of
the pump being overheated.
[0006] Accordingly, an object of the present invention is to
provide a vacuum pump with heat insulation means that would not
unfavorably influence the heat balance of the pump.
SUMMARY OF THE INVENTION
[0007] This and other objects of the present invention which will
become apparent hereinafter, are achieved by providing a hood that
at least partially surrounds the pump housing. The hood prevents
contact with heat conducting components of the pump, providing
protection for the pump user. In the region of hot parts of the
pump, there are provided surfaces which can be contacted without
danger to the user. Therefore, the increased costs which are
associated with an unnecessary large hood, are eliminated. The hood
is a simple part, and the access to all of the operational elements
can be insured by forming in the hood recesses and/or openings
which can be economically produced.
[0008] According to one modification of the present invention, an
intermediate member is arranged between the hood and the pump
housing, so that the housing and the hood are not in a surface
contact with each other. This reduces heat transmission to the
hood. In addition, the intermediate member provides spacing between
the pump housing and the hood, providing an intermediate space
filled with air that functions as an isolating air cushion in the
absence of a forced aeration that causes an air exchange.
[0009] According to a further modification of the present
invention, the intermediate member contains material components
that damps mechanical vibrations imparted to the intermediate
member. This prevents transmission of the vibrations to the hood,
which provides for a generally silent operation of the vacuum pump.
Little noise is transmitted to the environment, which is
advantageous for use of the inventive vacuum pump in a laboratory
environment in which operational personnel is always present.
[0010] According to an advantageous embodiment of the present
invention, the intermediate member has material components having
heat insulating properties, so that the intermediate member
functions also as a thermal barrier. This further reduces heat
transmission to the housing.
[0011] The advantages of the provision of the intermediate member,
which were discussed above, are further increased when the
intermediate member includes elastomeric components as they have
both vibration damping properties and heat insulating properties,
which provides for functioning of the intermediate member as both
vibration damping means and a thermal barrier.
[0012] According to a further advantageous embodiment of the
present invention, the hood is so formed and arranged that it
guides the cooling gas flow, which is generated by a fan, at least
to a portion of cooling ribs provided on the housing. This insures
an efficient cooling of the housing, with the hood being also
cooled from inside.
[0013] With the above-mentioned arrangement of the hood, the
aeration of channels between the cooling ribs and the hood is
increased when the fan is located behind the hood.
[0014] According to a still further development of the present
invention, the hood has an opening through which air is aspirated
by the fan to be subsequently delivered in the cooling channels.
The opening provides for an effective suction of air and; at the
same time, provides for freedom in selection of the location of the
fan. E.g., the fan can be arranged very close to the cooling ribs
and needs not to be necessarily located at the hood end.
[0015] The advantages of providing a hood significantly increase
with the vacuum pump the housing of which is formed of several
housing sections, with the pumping system and control electronics
being located in different housing sections. This improves the heat
balance of the pump because the pumping system represents a source
of heat while the control electronics has electronic components
which should be protected from heat, as they aged very rapidly
under heat.
[0016] The advantages of the present invention are particularly
apparent when the pumping system is adapted for compressing gas in
low or high vacuum range and for discharging the compressed gas
against atmosphere.
[0017] 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 preferred embodiment, when read
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The drawings show:
[0019] FIG. 1a a side view of a vacuum pump equipped with a hood
according to the present invention in a disassembled condition;
[0020] FIG. 1b a side view of the vacuum pump with a hood shown in
FIG. 1a in an assembled condition;
[0021] FIG. 2 a cross-sectional view through the intermediate
section and the control section of the inventive vacuum pump;
[0022] FIG. 3 a horizontal cross-sectional view along III-III in
FIG. 2;
[0023] FIG. 4 a vertical cross-sectional view of through the
pump-section and the peripheral section; and
[0024] FIG. 5 a cross-sectional view along line V-V in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] FIG. 1 shows a vacuum pump that is formed of four sections
and is surrounded by a hood 1. The hood 1 is shown in FIG. 1a in a
disassembled or dismounted condition. In FIG. 1b, the hood 1 is
shown in a mounted condition on the vacuum pump and surrounds a
portion of the vacuum pump housing 1'. The vacuum pump itself rests
on a stand 10.
[0026] The sections of the vacuum pump include different functional
units. The control section 2 includes the control electronics that
controls feeding of current from a network to the coils of the pump
drive. In the intermediate section 3, a fan 6 is arranged. The fan
6 aspirates air and delivers it in the space between cooling ribs 8
provided on the housing, whereby cooling of the pump takes place.
The suction and the delivery of air by the fan 6 is shown with the
arrows. The peripheral section 4 includes gas connections, i.e.,
gas inlet 9 and gas outlet. The stand 10 also is arranged at the
peripheral section 10. The stand 10 includes means, e.g., an
elastomeric body which reduces transmission of vibrations between
the vacuum pump and the floor. In the pumping section 5, those
components of the pump are located with which the gas is compressed
to such an extent that it can be discharged against the atmosphere.
These four sections are arranged axially one after another, with
the intermediate section being located between the peripheral and
control sections. The pumping section 5 is provided on a side of
the peripheral section 4 remote from the intermediate section
3.
[0027] The sections of the vacuum pump are at least partially
surrounded by the hood 1. In the embodiment shown in the drawings,
the hood 1 is so formed that it covers the lower portion of the
vacuum pump. Lower portion means a portion of the vacuum pump
adjacent to the stand 10, i.e., in the direction of the floor. The
shape of the hood 1 is such that the control and intermediate
sections 2 and 3 are completely covered by the hood 1. The hood is
somewhat short in the region of the pumping section, covering only
the lower part of the pumping section. The cooling ribs 8 are
provided in the lower part of the pumping section 5. However, the
cooling ribs can also be formed in the upper part of the pumping
section 5. The hood 1 covers at least a portion of the cooling ribs
8, forming channels that are limited by the hood 1, the pump
housing, and the cooling ribs 8. For the purpose of protection, it
can be sufficient to cover only the lower portion of the pump
because it is in the lower portions of the pumping and peripheral
sections 4 and 5 that the heat-carrying elements such as lubricant
and coils are provided. When shaping a hood, design consideration
can naturally play a certain role. The hood 1 also covers the fan
6.
[0028] In order for the fan to be able to aspirate the air and to
deliver it into the channels, the hood has an opening. In the shown
embodiment, the opening is formed as a plurality of aeration slots
7. The number and the shape of the slots 7 can vary for different
pumps and are dependent on the requirements to the cooling gas
flow.
[0029] FIG. 2 shows the design of the control and intermediate
sections 2 and 3. The control section 2 has a closed housing with
cooling ribs 11. The cooling ribs 11 insure cooling by a free
convection. Within the control section 2, there are located
electronic components which form control electronics and are
mounted on a printed circuit board. The electronic components
convert a supply voltage in such a way that feeding of voltage and
current in a suitable form to the drive coils to provide for
rotation of the drive shaft is insured. The supply voltage source
can be a conventional network voltage of 220 V and 50 Hz or any
contemporary industrial voltage such as 48V. Those components of
the control electronics, which generate a certain amount of heat,
can be so arranged that they would contact the inner wall of the
housing of the control electronics. Advantageously, the contact
takes place in the region of the cooling ribs 11. Likewise, it is
possible to embed the control electronics in a filling compound
partially or completely. This would also insure a high mechanical
stability.
[0030] The intermediate section 3 contains several components in
its housing. A switch 15 serves for turning the vacuum pump on and
off. Further switches can be also arranged in the intermediate
section housing. The further switches can include, e.g., a standby
switch or a speed selection switch. Here, likewise, a socket 16, to
which the power supply is connected, is arranged. This power is
transmitted to the control electronics, on one hand, and on the
other hand, it is transmitted to a small panel that is connected by
suitable conductors with an auxiliary electronics 18, supplying it
with power. The auxiliary electronics serves for converting the
switching condition of the switch 15 in a control signal that is
transmitted over suitable conductors to the control electronics.
The auxiliary electronics has also means that insures feeding
voltage to the fan motor 6a and that controls switching the fan
motor 6a on and off. A seal 14 is provided between the housings of
the intermediate section 3 and the control section 2. The seal 14
serves, on one hand, for sealing the inner space against the
moisture and dust. On the other hand, the seal 14 functions as a
thermal barrier, making the transmission of heat from the
intermediate section to the control section more difficult. A
similar seal is also provided between the intermediate section 3
and the peripheral section 4, making the transmission of heat
therebetween also more difficult. In a portion of the intermediate
section 3, a support 19 supports the fan 6 that includes the motor
6a and a fan blade 6b. The dash arrows show the cooling gas flow
that is aspirated by the fan 6. The air is aspirated and flows
between the cooling ribs 8.
[0031] FIG. 3 shows a cross-sectional view of the control and
intermediate sections 2 and 3 and a portion of the peripheral
sections 4. In this view, cooling ribs 11, which are provided on a
control section-side, end side of the vacuum pump, are shown in
cross-section. The longitudinal axis of the ribs 11 is oriented in
direction of the gravity force in order to optimize the free
convection. Advantageously, the cooling ribs of the control section
are not covered by the hood 1 in order not to obstruct the air flow
of the free convection. The feeding electrical conductors from the
control section 2 pass to the peripheral section 4 through a cable
channel provided in the intermediate section 3. Two channel seals
21 and 22 protect the cable channel from moisture and dust. In
particular, on a side of the motor control, a cable leadthrough 27
is provided. Inside the peripheral section 4, there are provided
coils 26 of the pump drive.
[0032] The control electronics 12 provides for feeding power to the
coils 26. A rotationally symmetrical separation member 23 is
arranged between the coils 26 hermetically separating them from the
inner space of the separation member 23. An end of a shaft 24, on
which permanent magnets 25 are secured, projects into the inner
space of the separation member 23. The cooling gas flow, which is
generated by the fan 6, is again shown with dash arrows. The
suction is effected through the aeration slots 7, and the air is
delivered in the direction of the peripheral section 4. According
to a further modification of the vacuum pump, such aeration slots
are formed in the pump bottom. The stand then needs to be
sufficiently spaced from the pump bottom in order to provide a
clearance through which the air can be aspirated.
[0033] FIG. 4 shows a cross-sectional view of the peripheral and
pumping section 4 and 5. The embodiment of the vacuum pump shown in
the drawings represents a one-stage, lubricant-tight vane rotary
vacuum pump. The vacuum pump shown in FIG. 4 has a pumping system
30 located in the pumping section 5. The pumping system 30 has its
end side connected with the peripheral section 4 along a large
surface, whereby a good heat transmission is insured.
[0034] The housing of the pumping section 5 has good
heat-conducting characteristics, so that the heat of the peripheral
section 4 is transmitted to a large-surface body. The shaft 24
eccentrically extends through a cylindrical bore formed in the
pumping section 5. The shaft 24 can be formed of one or several
pieces and is supported by first and second slide bearings 31 and
32 which are lubricated by a lubricant. The lubricant is supplied
from a lubricant reservoir 35 that surrounds the pumping system 30.
A vane 33 is rotatably supported in the cylindrical bore of the
pumping section 5, with a compression chamber 34 being formed
between the wall of the cylindrical bore and the vane 33. The
permanent magnets 25 are secured, as it has already been discussed
above, on the end of the shaft 24 that projects into the peripheral
section 4 in which the coils 26 are located. Cooperation of the
magnets 25 with coils 26 provides for ration of the shaft 24, with
the coils 26 and permanent magnets 26 forming an electric motor.
Here, there is provided a brushless D.C. motor. Though the
advantages of the present invention are particularly apparent with
this type of an electric motor, the invention is not limited to
this type of a drive motor. The lubricant, primarily oil, serves,
in addition to lubrication of the bearings, also for lubrication
and sealing of the vane 33.
[0035] FIG. 5 shows a vertical cross-sectional view of the pumping
section 5. FIG. 5 illustrates in particular the eccentric position
of the shaft 24 and the position of vane 33. Between the vane 33
and the shaft 24, there is provided a spring, not shown. The
pumping section housing has the cooling ribs 8. The hood 1 covers
the cooling ribs 8, forming flow channels 42. The cooling gas flow,
which is generated by the fan 6, flows through the flow channels
42, which can be connected with each other, absorbs the heat of the
housing and carries the heat away from the housing. The heat is
produced in the pumping system 30 and is transmitted to the housing
by the lubricant reservoir 36.
[0036] Preferably, the hood 1 is so shaped that the channels are
open at their ends. This can be managed very easily as the hood 1
does not cover the pumping section-side, end side of the inventive
vacuum pump. Between the hood 1 and the housing, there is provided
an intermediate element 40 that, e.g., has highly elastomeric
components. Preferably, the intermediate element 40 is provided at
that location between the hood 1 and the housing at which the hood
1 and the housing are connected with each other. The location and
material selection take care of both thermal insulation and
reduction of transmission of vibration from the pumping housing to
the hood 1. The hood 1 is fixed with attachment means, e.g., with
screws 41.
[0037] The embodiment of the vacuum pump shown in the drawings has
a favorable heat balance. A first source of an extensive heat is
the heat of compression in the pumping section 5. A further source
of an extensive heat is the peripheral section 4 because it is
there that the drive coils, in which the power dissipation is
converted into heat, are located. In addition, the heat to the
peripheral section 4 is transmitted by the end side of the pumping
system 30 which contact the peripheral section 4 along a large
surface. These heat sources are isolated from the control section
by the intermediate section. In view of the serial connection of
the pump sections, this distance is maximized. Also, the thermal
resistance of the seals, which are provided between the
intermediate section and the adjacent sections, contributes to
isolation of the heat sources from the control section 2. These
passive measures provide for a very favorable heat balance. The
active cooling with a fan also contributes to the favorable heat
balance. By locating the fan in the intermediate section, the
sections; which generate most of the heat, are subjected to the
action of the cooling air. The hood serves, on one hand, as a
convection protector and, on the other hand, guides the cooling air
flow, which is generated by the fan, in optimal manner to the heat
sources of the pumping and peripheral sections. In those regions,
where no air movement takes place, under the hood, the air acts as
an air cushion and isolates the environmental heat from the bottom
parts, e.g., of the control section. In sum, the cooling of the
inventive vacuum pump is noticeably improved in comparison with the
state of the art.
[0038] Though the present invention was shown and described with
references to the preferred embodiment, such is merely illustrative
of the present invention and is 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.
* * * * *