U.S. patent application number 11/222822 was filed with the patent office on 2006-03-16 for imbalance compensation element, pump, and method for balancing pumps driven by an electric motor.
This patent application is currently assigned to Pierburg GmbH. Invention is credited to Michael Bonse, Andreas Bumbel.
Application Number | 20060057007 11/222822 |
Document ID | / |
Family ID | 35414582 |
Filed Date | 2006-03-16 |
United States Patent
Application |
20060057007 |
Kind Code |
A1 |
Bumbel; Andreas ; et
al. |
March 16, 2006 |
Imbalance compensation element, pump, and method for balancing
pumps driven by an electric motor
Abstract
The present invention describes an imbalance compensation
element featuring spring arms for fixing onto a shaft, and that
grooves in which an anaerobic adhesive can distribute itself for
fixing the imbalance compensation element on a motor shaft. One
embodiment includes a pump with such an imbalance compensation
element. In a method for balancing such electric pumps, the axial
and radial oscillation accelerations as well as the oscillation
angular position of a running pump are measured. In accordance with
these measurements and the balance class and balance angle values
ascertained therefrom, an imbalance compensation element is fixed
on the shaft. Through this invention the time and cost required for
balancing pumps driven by electric motors can be reduced and the
acoustic emissions can be distinctly reduced when such a pump is
installed on a housing.
Inventors: |
Bumbel; Andreas;
(Castrop-Rauxel, DE) ; Bonse; Michael;
(Dusseldorf, DE) |
Correspondence
Address: |
GRIFFIN & SZIPL, PC
SUITE PH-1
2300 NINTH STREET, SOUTH
ARLINGTON
VA
22204
US
|
Assignee: |
Pierburg GmbH
Neuss
DE
|
Family ID: |
35414582 |
Appl. No.: |
11/222822 |
Filed: |
September 12, 2005 |
Current U.S.
Class: |
417/423.15 ;
417/423.1 |
Current CPC
Class: |
F04D 29/662 20130101;
G01M 1/32 20130101; F16F 15/34 20130101 |
Class at
Publication: |
417/423.15 ;
417/423.1 |
International
Class: |
F04B 17/00 20060101
F04B017/00; F04B 35/04 20060101 F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 11, 2004 |
DE |
10 2004 044 070.0 |
Claims
1. An imbalance compensation element for fixing on one end of a
motor- or pump-shaft, comprising: an inner circumferential surface
coaxial to a central axis, the surface having an inside diameter
corresponding essentially to an outside diameter of the shaft,
wherein the inner circumferential surface has one or more flexible
spring arms in a first section, wherein the one or more spring arms
are disposed so that when in an installed state, the spring arms
produce a frictional connection to the shaft in at least a
circumferential direction.
2. An imbalance compensation element according to claim 1, wherein
said spring arms are embodied as ring segments extending in an
axial direction.
3. An imbalance compensation element according to claim 1, wherein
said inner circumferential surface features a second section having
grooves running in an axial direction.
4. An imbalance compensation element according to claim 1, further
comprising a closed outer circumferential surface, wherein over one
or more first defined angular areas the closed outer
circumferential surface is connected to said inner circumferential
surface with a connection that is essentially completely filled
with material, and wherein in one or more second defined angular
areas, the closed outer circumferential surface is connected to the
inner circumferential surface by one or more individual
bridges.
5. An imbalance compensation element according to claim 1, wherein
the imbalance compensation element comprises one piece made by an
injection molding process.
6. An air injection reactor pump for combustion engines drivable by
an electric motor having a drive shaft, wherein the pump comprises
at least one impeller arranged on a drive shaft of the electric
motor, and wherein when the pump is disposed for driving by the
electric motor, one end of the drive shaft projects beyond the
impeller in a direction facing away from the electric motor so that
an imbalance compensation element according to claim 1 can be fixed
on the one end of the shaft.
7. A pump according to claim 6, further comprising a connection
piece of said pump, coaxial to said drive shaft.
8. A pump according to claim 6, wherein said imbalance compensation
element is fixed on said drive shaft by means of an anaerobic
adhesive.
9. A pump according to claim 6, wherein said imbalance compensation
element further comprises an axial outer surface, said pump
impeller comprises a hub having a corresponding surface, and the
axial outer surface of the imbalance compensation element and the
corresponding surface of the hub correspond in their shape.
10. A method for balancing an electric pump comprising the steps
of: (a) providing a pump connected to an electric motor; (b)
starting the electric motor; (c) measuring an oscillation
acceleration to determine acceleration amplitudes in the axial
and/or radial directions together with measuring an oscillation
angular position to determine a balance angle and a balance class;
and (d) placing a classified imbalance compensation element
according to claim 1 in accordance with the determined balance
angle and balance class.
11. A method for balancing electric pumps according to claim 10,
wherein said motor further comprises a drive shaft and said step
(c) further comprises using a light barrier as well as a reflecting
disk connected to the drive shaft with a positive engagement to
measure said oscillation angular position.
12. A method for balancing electric pumps according to claim 10,
further comprising the use of a triax sensor is to measure said
oscillation acceleration.
13. Method for balancing electric pumps according to claim 10,
wherein said measurements are carried out at an operating speed of
the fully assembled pump.
14. Method for balancing electric pumps according to claim 10,
wherein said measurements are carried out at one or more mounts of
said pump to a combustion engine or to a vehicle.
15. Method for balancing electric pumps according to claim 10,
wherein if said oscillation angular positions of said axial and
radial acceleration amplitudes are not equal, said balance angle
and said balance class are calculated by weighting the acceleration
amplitudes taking into consideration the oscillation angular
positions.
16. Method for balancing electric pumps according to claim 10,
further comprising a step of fixing said imbalance compensation
element in a recess of an angular degree disk at a zero position;
step (c) further comprises ascertaining the balance angle to the
zero position; and step (d) further comprises turning said
imbalance compensation element before fixing said element.
Description
[0001] This application claims priority on DE 10 2004 044 070.0
filed Sep. 11, 2004, the entire disclosure of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the invention
[0003] The invention relates to an imbalance compensation element
for fixing on one end of a motor- or pump shaft, whereby the
imbalance compensation element features an inner circumferential
surface coaxial to the central axis whose inside diameter
corresponds essentially to the outside diameter of the shaft, as
well as a pump, in particular an air injection reactor pump for
combustion engines, which pump is driven by an electric motor,
whereby at least one impeller of the pump is arranged on a drive
shaft of the electric motor, as well as a method for balancing such
a pump driven by an electric motor.
[0004] 2. Background Art
[0005] Certain imbalance compensation elements, pumps, and methods
for balancing in such pumps by means of imbalance compensation
elements are known and are described in a number of Applications.
Thus in DE 93 03 470 U1 a fan is described whose impeller is
arranged on a shaft driven by an electric motor, whereby a
balancing weight is placed on the end of the shaft projecting from
a housing aperture in order to balance the fan. The imbalance
compensation element used thereby is a radially divided ring that
can be embodied in different widths and weights. In a described
form of embodiment, the imbalance compensation element is formed by
a Seeger circlip ring, which after the final testing of the fan is
inserted into a circular groove of the shaft by means of Seeger
circlip ring pliers and is oriented according to the determined
imbalance.
[0006] From EP 0 711 924 B1 an electrically driven air pump is
known that features a housing in which both an electric motor and
the pump assembly are arranged, whereby a balancing of the electric
motor with a mounted pump wheel in the installed state is carried
out by placing balance marks on an impeller of the pump wheel
before the pump side is closed.
[0007] As a rule the known methods are iterative methods in which
the measured imbalance is to be minimized at each further step by
repeatedly allowing the electric motor or the pump to run. This can
be carried out for example by means of small holes in the
impellers. Thus these are nonclassified imbalance compensation
elements.
SUMMARY OF THE INVENTION
[0008] The object of the invention is to create a classified
imbalance compensation element that can be mounted on a pump shaft
in a single operation, for which purpose if possible only a single
measurement of the imbalance should be required. The transmission
of acoustic emissions, in particular structure-borne noise, after
installation for example on a combustion engine or a body of a
vehicle is to be minimized.
[0009] This object is achieved in that the inner circumferential
surface of the imbalance compensation element features flexible
spring arms in a first section, which spring arms are embodied such
that in the installed state, the spring arms produce a frictional
connection to the shaft at least in the circumferential direction.
By these means it is possible to place the imbalance compensation
element with positive engagement on one end of a motor shaft or on
a hub of a pump at a measured balance angle. In spite of the
unequal weight of the body, an unintentional twisting is
precluded.
[0010] In a preferred form of embodiment the spring arms are
embodied as ring segments extending in the axial direction, so that
as a result the component can be produced cost-effectively and its
shape is simple.
[0011] In a further embodiment of the invention the inner
circumferential surface features grooves in a second rigid section
that run in the axial direction, so that the positive engagement
connection forces are also greater in this rigid section due to the
smaller mounting surface and when fixed by means of adhesive,
sufficient adhesive can be deposited in the grooves to create a
firm, cohesive connection between the shaft or hub of the pump and
the imbalance compensation element.
[0012] In a further form of embodiment of the invention the
imbalance compensation element features a closed outer
circumferential surface wherein over one or more first defined
angular areas the closed outer circumferential surface is connected
to said inner circumferential surface with a connection that is
essentially completely filled with material, and wherein in one or
more second defined angular areas, the closed outer circumferential
surface is connected to the inner circumferential surface by one or
more individual bridges. In this manner a counterweight to the
imbalance present is created, since the center of gravity in the
axial direction of this imbalance compensation element does not lie
in the center. Moreover the embodiment with the individual bridges
between the circumferential surfaces still guarantees adequate
strength in the otherwise hollow area.
[0013] In a preferred form of embodiment the imbalance compensation
element is produced as one piece using the injection molding
process, by means of which time and production costs are
minimized.
[0014] Moreover the above-described object is achieved by a pump in
which the drive shaft projects beyond the impeller of the pump in
the direction facing away from the electric motor so that an
imbalance compensation element according to the invention can be
fixed on the projecting end of the shaft. Thus no further changes
need to be undertaken to existing components of the pump such as
the impellers for imbalance compensation. The arrangement of such
an imbalance compensation element on the shaft end is to be carried
out in one operation.
[0015] In a preferred form of embodiment a connection piece of the
pump runs coaxially to the drive shaft so that in the completely
assembled state, the pump can be tested and balanced.
[0016] In a further form of embodiment the imbalance compensation
element is fixed on the drive shaft by means of an anaerobic
adhesive with which the impellers can also be fixed on the drive
shaft. Such an adhesive dries only when air has been excluded, so
that an intermediate bearing of the pumps before the balancing is
possible and the residual amount of adhesive on the shaft from the
fixing of the impellers is sufficient to fix the imbalance
compensation element.
[0017] In a further form of embodiment of the pump, the axial outer
surfaces of the imbalance compensation element and of a hub of the
pump impeller facing one another correspond in their shape, so that
a clearly defined stop of the imbalance compensation element on the
hub of the pump impeller is present and an exclusion of air is
ensured.
[0018] The above-mentioned object is furthermore achieved by a
method for balancing electric pumps of the invention by
single-level balancing with the following steps: [0019] (a)
providing a pump connected to an electric motor; [0020] (b)
starting the electric motor; [0021] (c) measuring an oscillation
acceleration to determine acceleration amplitudes in the axial
and/or radial directions together with measuring an oscillation
angular position to determine a balance angle and a balance class;
and [0022] (d) placing a classified imbalance compensation element
according in accordance with the determined balance angle and
balance class.
[0023] With such a method a single measurement suffices to
compensate for the imbalance present.
[0024] To measure the oscillation angular position, it is
preferable to use a light barrier as well as a reflecting disk
connected to the drive shaft with positive engagement, which is
simple to dismantle again after the measurement has taken
place.
[0025] To measure the oscillation acceleration, it is preferable to
use a triax sensor with which both the axial and the radial
oscillation acceleration is measured at the pump.
[0026] It is preferable to carry out the measurements at the
operating speed of the fully assembled pump, so that the imbalances
actually occurring during the operation of the pump are also
identified.
[0027] To further improve the results, the measurement of the
oscillation acceleration is carried out at the mounts of the pump
to the combustion engine or to the vehicle. After the pump is
installed, this leads to distinctly reduced transmission of
structure-borne noise to the engine housing or to the body.
[0028] If the oscillation angular position of the axial and radial
acceleration amplitudes are not equal, the balance angle and the
balance class are preferably calculated by weighting the
acceleration amplitudes taking into consideration the oscillation
angles. Through such a procedure, as a rule a balance process
remains sufficient to achieve good results.
[0029] In a further operational step, the classified imbalance
compensation element is fixed in a recess of an angular degree disk
before being fixed on the shaft, so that after the balance angle to
the zero position has been ascertained, the imbalance compensation
element can be turned into the correct position to the shaft by
turning the angular degree disk to the ascertained balance angle,
can be pushed onto the shaft, and fixed. This leads to an exact
fixing of the imbalance compensation element in accordance with the
measured data. The number of measurements needed and assembly steps
is reduced by such a method in comparison with other known
methods.
[0030] Thus an imbalance compensation element is created that is
simple to produce and mount and through which a high-quality
balancing is produced with a single measurement. Accordingly a
low-oscillation running of a pump equipped with such a balance
element is ensured. The method for balancing such a pump with an
imbalance compensation element according to the invention contains
a distinctly reduced number of assembly steps in comparison with
known methods. Thus a largely oscillation-free pump can be produced
and assembled with a reduction in cost and time. After installation
in the engine, acoustic emissions are reduced.
[0031] An imbalance compensation element according to the invention
and a pump equipped with such an imbalance compensation element are
shown in the drawings, whereby the method according to the
invention for balancing such pumps is also described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 shows an imbalance compensation element according to
the invention in cross-section in side view.
[0033] FIG. 2 shows the imbalance compensation element from FIG. 1
in perspective view.
[0034] FIG. 3 shows a cross-section representation of a pump
according to the invention using an air injection reactor pump as
an example, in side view.
DETAILED DESCRIPTION OF THE INVENTION
[0035] The imbalance compensation element 1 shown in FIGS. 1 and 2
comprises a body that features an aperture 2 running axially, which
aperture is limited by an inner circumferential surface 3. This
inner circumferential surface 3 is divided into a first section 4
formed by flexible spring arms 5, and a second section 6 in which
the aperture 2 features grooves 7. This second section 6 is
immediately adjacent to the first section 4. The flexible spring
arms 5 are formed such that recesses 8 running axially are arranged
in this first section 4 and the imbalance compensation element 1
features a second aperture 9 whose diameter is greater than the
diameter of the aperture 2. This aperture 9 extends up to the start
of the first section 4 and continues in the form of a groove and
coaxially in the section lying outside the axis. Accordingly the
flexible spring arms 5 remain between this larger diameter of the
second aperture 9 and the smaller diameter of the aperture 2. It
must also be pointed out that these flexible spring arms 5, which
are essentially formed by small ring segments, are slightly bent
towards the axis in comparison with the diameter of the aperture 2,
so that a spring force is exerted by them on a shaft, not shown
here, that features a corresponding outside diameter.
[0036] Axially outwards the imbalance compensation element 1 is
limited by an outer circumferential surface 10, which likewise runs
essentially coaxially to the axis. In order to be able to undertake
an appropriate imbalance compensation, the cavity forming between
the inner circumferential surface 3 and the outer circumferential
surface 10 is filled with material over certain angular areas, so
that a connection 11 running over this angular area between the
inner circumferential surface 3 and the outer circumferential
surface 10 is ensured. In another radial angular area a connection
between the circumferential surfaces 3, 10 is produced only by
bridges 12 in order to ensure a fixing of the imbalance cap, and
thus to be able to embody the walls of the circumferential surfaces
13 as thin as possible.
[0037] Depending on the desired balance class, the angular area
filled with material can be selected larger or smaller. Different
classified imbalance compensation elements are correspondingly
available. The fill level along the axis can also be changed if
necessary.
[0038] Moreover it can be seen in particular from FIG. 3 that the
imbalance compensation element 1 features an axially limiting outer
surface 13 whose shape corresponds to a hub 14 of an impeller 15 of
an air injection reactor pump 16. This air injection reactor pump
16 is driven by an electric motor 17, whereby two impellers 15, 18
are arranged directly behind one another axially on a shaft 19,
which shaft is embodied simultaneously as pump- and motor shaft
19.
[0039] When such an air injection reactor pump is being balanced,
an imbalance compensation element 1 classified according to the
balance class ascertained is pushed on to the motor shaft 19 at the
balance angle ascertained. For this purpose, one end 20 of the
shaft 19 is embodied lengthened. In order to be able to attach such
an imbalance compensation element 1 when the pump 16 is completely
assembled, a connection piece 21 is arranged coaxially to the shaft
axis, whereby the connection piece 21 is embodied on a cover 22 of
the pump 16 and is axially accessible. During the assembly of the
air injection reactor pump 16, this cover 22 is mounted on a
housing 23 in which the electric motor 17 is also fixed with
intermediate layers of elastomer rings 24. This housing 23 is again
closed by a second cover 25 at the end facing away from the side of
the pump.
[0040] In the present case this is an air injection reactor pump 16
that is embodied as a two-stage radial fan. Electrical contacts 26
to connect the motor 17 to an external power source are led out of
the housing 23. In addition, mounts 27 are embodied on the housing
23, to which mounts the air injection reactor pump 16 can be fixed
during installation in a combustion engine or on the body of a
vehicle.
[0041] A balancing of such an electric air injection reactor pump
16 is performed by first inserting the air injection reactor pump
16 into a holding device with an intermediate layer of elastomer
rings. In the area of the mounts 27 a triax sensor is arranged that
records the axial and radial accelerations arising due to a
possibly present imbalance. Since no imbalance compensation element
1 has yet been arranged on the shaft 19 at this point in time, a
reflecting disk is arranged at this location that interacts with a
light barrier that is part of the holding device, through which the
oscillation angular position can be measured in a known manner
during operation. The completely assembled pump, which is now
situated in the holding device, receives the electrical connections
and is started. The values measured at the operating speed of the
pump are decisive for the results of the triax sensor or the light
barrier to be evaluated. In accordance with these measured values,
a balance class and a balance angle are calculated, whereupon a
corresponding classified imbalance compensation element 1 is pushed
onto the shaft 19. This is done by placing the imbalance
compensation element 1 in a recess of an angular degree disk and
fixing it there in a zero position. After the balance angle to the
zero position has been ascertained, the imbalance compensation
element can be turned to the correct angle to the motor shaft 19 by
turning the angular degree disk and can be pushed onto the motor
shaft. The impellers 15, 18 of these pumps 16 are customarily fixed
by means of an anaerobic adhesive, so that additional fixing means
for the imbalance compensation element 1 are not necessary, since
the residual adhesive present on the shaft suffices to fix the
imbalance compensation element 1, which has been pre-fixed by the
spring arms 5, finally on the shaft 19. The adhesive amount
remaining from the fixing of the impellers 15, 18 of the pump 16
can distribute itself uniformly in the grooves 7, without the
entire amount of adhesive being pushed from the shaft 19 during the
placing. This anaerobic adhesive can then cure in a short time due
to the exclusion of air between the inner circumferential surface 3
of the imbalance compensation element 1 and the outer surface of a
shaft 19.
[0042] If the oscillation angular position of the axial and the
radial measured accelerations are not the same, the balance angle
is calculated by weighting the acceleration amplitudes taking the
respective oscillation angles into consideration.
[0043] Thus a distinctly reduced oscillation load of the air
injection reactor pump can be achieved by means of a single
measurement at operating speed of the pump and measurement of the
accelerations at the actual mounts as well as measurement of the
oscillation angles of the air injection reactor pump, as a result
of which in particular acoustic emissions in the vehicle are
reduced to a particularly great extent. The imbalance compensation
element to be arranged on a pump for this purpose can be produced
simply and cost-effectively and can be pre-fixed by the spring
arms. A great reduction in cost and time with a simultaneously
optimized imbalance compensation is formed by such an embodiment of
the imbalance compensation element or such a method for the
production of an imbalance compensation on a pump.
* * * * *