U.S. patent application number 11/832880 was filed with the patent office on 2008-02-07 for feed screw for eccentric screw pump.
Invention is credited to Ulrich Braun, Klaus Gerbl, Helmuth Goschy, Karl-Heinz Grebisz, Markus Rosam, Melanie Wetzel.
Application Number | 20080031758 11/832880 |
Document ID | / |
Family ID | 38535631 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080031758 |
Kind Code |
A1 |
Rosam; Markus ; et
al. |
February 7, 2008 |
Feed Screw For Eccentric Screw Pump
Abstract
The inventions relates to a feed screw for eccentric screw pumps
which, to avoid bridge formation of the medium and optimisation of
the drive power, has a screw, which in the axial region, has
perforations and webs.
Inventors: |
Rosam; Markus; (Aschau am
Inn, DE) ; Grebisz; Karl-Heinz; (Detmold, DE)
; Wetzel; Melanie; (Waldkraiburg, DE) ; Goschy;
Helmuth; (Waldkraiburg, DE) ; Braun; Ulrich;
(Waldkraiburg, DE) ; Gerbl; Klaus; (Schwindegg,
DE) |
Correspondence
Address: |
ST.ONGE STEWARD JOHNSTON & REENS LLC
986 Bedford Street
Stamford
CT
06905-5619
US
|
Family ID: |
38535631 |
Appl. No.: |
11/832880 |
Filed: |
August 2, 2007 |
Current U.S.
Class: |
418/48 |
Current CPC
Class: |
F04C 11/005 20130101;
F04B 19/12 20130101; F04C 2/1071 20130101; F04C 15/0061 20130101;
F04C 2240/60 20130101; F04C 13/001 20130101 |
Class at
Publication: |
418/048 |
International
Class: |
F04C 2/107 20060101
F04C002/107 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2006 |
DE |
10 2006 036 243.8 |
Claims
1. An eccentric screw pump with an eccentrically rotating rotor
which rotates in a stator provided with an additional screw start,
wherein the rotor is connected with a drive via a coupling shaft
and the coupling shaft is surrounded by a feed screw, characterized
in that the feed screw has a screw which, per pitch, has at least
two perforations and that the webs formed between these
perforations are connected with the coupling shaft.
2. The eccentric screw pump according to claim 1, characterized in
that at least four perforations are present per screw pitch.
3. The eccentric screw pump according to claim 1, characterized in
that the coupling shaft has a screw pipe on which strip-shaped pipe
segments are located at one end parallel to the longitudinal axis
of the feed screw which are connected with the screw.
4. The eccentric screw pump according to claim 3, characterized in
that the number of pipe segments corresponds to the number of
perforations.
5. The eccentric screw pump according to claim 1, characterized in
that the height of the perforations corresponds to between 30% and
70% of the height of the screw.
6. The eccentric screw pump according to claim 5, characterized in
that the height of the perforations corresponds to between 20% to
60% of the height of the screw.
7. The eccentric screw pump according to claim 3, characterized in
that the pipe segments in the operational state cover the joint
element/s.
8. The eccentric screw pump according to claim 1, characterized in
that the width of the perforations corresponds to the width of the
webs which are connected with the coupling rod.
9. The eccentric screw pump according to claim 1, characterized in
that the width of the perforations is greater than the width of the
webs.
10. The eccentric screw pump according to claim 1, characterized in
that the width of the webs is greater than the width of the
perforations.
11. The eccentric screw pump according to claim 1, characterized in
that the webs have an inclination opposite to the course of the
screw.
12. The eccentric screw pump according to claim 1, characterized in
that the webs are offset to one another by 30.degree. to
120.degree..
13. The eccentric screw pump according to claims 7, characterized
in that the length of the pipe segments is adapted to the course of
the screw.
14. The eccentric screw pump according to claim 1, characterized in
that the screw consists of several parts.
15. The eccentric screw pump according to claim 2, characterized in
that the coupling shaft has a screw pipe on which strip-shaped pipe
segments are located at one end parallel to the longitudinal axis
of the feed screw which are connected with the screw.
16. The eccentric screw pump according to claim 2, characterized in
that the height of the perforations corresponds to between 30% and
70% of the height of the screw.
17. The eccentric screw pump according to claim 4, characterized in
that the height of the perforations corresponds to between 30% and
70% of the height of the screw.
18. The eccentric screw pump according to claim 4, characterized in
that the pipe segments in the operational state cover the joint
element/s.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of German patent
application No. 10 2006 036 243.8 filed on Aug. 3, 2006, the
content of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to an eccentric screw pump with a feed
screw which supplies the suction region of the screw rotor mainly
with medium to highly viscous media.
BACKGROUND OF THE INVENTION
[0003] DE 101 60 335 A1 shows an eccentric screw pump in this
regard where a feed screw is arranged in the pump housing before
the pump rotor. The screw is connected with the screw core via its
entire inner contour.
[0004] DE 101 18 071 A1 shows an eccentric screw pump about the
coupling rod of which a hollow screw is arranged. This hollow screw
is connected with a disc on the drive side. The other end in the
suction-side region of the screw rotor has no connection to a joint
or the coupling rod.
[0005] With a mixing device according to DE 1 277 819 dry
substances are mixed with liquid and subsequently delivered by a
pump. To this end, a mixing screw is seated in the region of a
storage vessel, which mixing screw is connected on the one side
with a motor and, on the other side with a screw pump. Liquid
enters the screw region between the storage vessel and the pump.
The feed screw consists of a helical band which is only fastened to
the mixer shaft at one end by means of four braces.
[0006] A mixing and feed device is also shown in DE 43 18 177. The
dry substances enter the region of a mixing screw via a hopper,
while a liquid feed line also leads into the region of said mixing
screw. Following the mixing operation, the mixture is transported
onwards by a screw pump. The mixing screw itself consists of a
region with a solid screw and a region with paddle and web-shaped
mixing elements.
[0007] Each pump is designed for a determined delivery rate. To
this end, adequate medium must always be available for the pump
region on the suction side. The feed screws, which are arranged
upstream of the actual screw or eccentric screw pump, can therefore
deliver a multiple volume of the pump capacity. Because of this, a
back-up effect develops in the so-called stuffing space in the
suction region which is associated with danger of bridge formation
in the hopper above the screw. Because of this stuffing effect,
substantially higher drive power than necessary must be made
available.
[0008] The object of the invention consists in adapting the
stability of the feed screw to the required output while keeping
the drive power constantly low even with different media.
SUMMARY OF THE INVENTION
[0009] This object is solved through the characteristics of claim
1. Further developments of the feed screw according to the
invention are indicated from the characteristics of the
sub-claims.
[0010] The design of a corresponding feed screw between the pump
rotor and the drive has shown that the devices known from the prior
art solve only part problems of the object according to the
invention.
[0011] The design according to the invention is obviously dependent
on which products with which viscosities, and, if applicable,
present solid materials have to be pumped.
[0012] According to the invention the normal embodiment concerns a
feed screw having at least two perforations, wherein the webs
formed between these perforations are connected with their screw
root with the coupling shaft. Depending on which viscosity the
product has it may be practical to increase the number of
perforations to at least four in order to facilitate the return
flow of the medium and ensure more homogenous mixing-through,
through which bridge formation of the medium is already
counteracted on the suction-side end of the pump.
[0013] Through the perforations according to the invention,
low-loss drive power compared with delivery devices from the prior
art, designed to the condition of the medium can be installed.
[0014] In order to obtain the advantage according to the invention
also in the regions of the couplings (joints) the screw also
extends beyond this region for the purpose of which the pipe
employed as coupling rod has strip-shaped pipe segments which are
connected with the screw. If the number of the pipe segments
corresponds to the number of the perforations, a corresponding
number of webs for their fastening is available.
[0015] Since for the return flow of the medium not only the number
of perforations but also their area place a substantial role, it
can be provided according to a version according to the invention
to dimension the perforations between 30% and 70% of the height of
the screw start. With low-viscosity substances the height of the
perforations can be selected in the range from 20% to 60% of the
height of a screw pitch.
[0016] As is shown in an exemplary embodiment the width of the
perforations will correspond to the width of the webs because of
the homogenous return feed and even loading of the screw. With
high-viscosity media the return flow possibility must certainly be
improved wherein the width of the perforations is greater than the
width of the webs. With low viscosity substances the danger of
bridge formation is relatively low so that here the width of the
webs can be greater than that of the perforations.
[0017] To improve the return flow and thus reduce the stagnation
effect the flow along the coupling shaft can be improved in that
the webs have an inclination and thus produce a flow direction
which is opposite to the course of the screw.
[0018] Depending on which design of the screw is required, the webs
can be offset to one another by 30.degree. to 120.degree. per screw
start. In order for the feed screw to be stabilised about its
entire length through the coupling shaft the length of the pipe
segments is adapted to the course of the feed screw.
[0019] Easier affixing of the feed screw to the coupling shaft is
obtained in that the feed screw consists of several parts which
enable better handling during the mostly employed welding
operation.
[0020] The invention is exemplarily described in the following by
means of exemplary embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 lateral view of the feed screw;
[0022] FIG. 2 a three-dimensional representation of the feed
screw;
[0023] FIG. 3 a cross section of the feed screw;
[0024] FIG. 4 feed screw with joint part on both sides;
[0025] FIG. 5 lateral view of the feed screw according to FIG.
4;
[0026] FIG. 6 cross section of a feed screw;
[0027] FIG. 7 screw cross section with 6 perforations;
[0028] FIG. 8 screw cross section with 4 perforations; and
[0029] FIG. 9 screw cross section with various perforation
distances from the coupling rod.
DETAILED DESCRIPTION OF THE INVENTION
[0030] FIG. 1 shows a design possibility of a feed screw 10 with a
screw pipe 12. A screw 14 is welded on to the circumferential
surface of the screw pipe 12. On both ends 16, 18 of the screw pipe
12, pipe segments 20 for fastening the screw 14 are provided. Each
of the pipe segments 20 ends at the point at which the screw 14
ends in axial direction. In the region of the pipe elements 20,
couplings 22 for the joints not shown are provided at both ends.
The screw 14 is manufactured from flat band-shaped material.
[0031] The design of the screw 14 can be more clearly seen in FIG.
2. From the perspective representation it becomes evident that the
screw 14 is provided with perforations 24 and webs 26. Each screw
root 34 of the webs 26 is connected with the pipe segment 20 or the
coupling shaft 32 for example through a welding operation. While
the medium in axial direction flows from the rotor region back to
the pump inlet through the perforations of the feed screw closely
along the screw pipe, the screw 14 with its end faces 28 transports
the medium in the direction towards the pump rotor. The pump rotor,
through a joint which is not completely shown, and which joint is
fastened to the coupling 22, is in positive contact with the feed
screw.
[0032] FIG. 3 shows the embodiment and arrangement of the
perforations 24 and webs 26 for a feed screw for highly viscous
media. Here, the large free areas of the perforations 24 enable
very good return flow possibilities for the medium in order to
adapt the stagnation pressure in the stuffing space to the pump
output. Here, dehydration of the medium and increased tendency
toward bridge formation is prevented and undesirably high drive
power avoided.
[0033] The perforations 24 according to this exemplary embodiment
are wider than the webs 26. The middle of the perforations in each
case is located on the midperpendicular and is thus offset by
90.degree. relative to one another which produces 4 perforations 24
and 4 webs 26 per screw pitch. The height of the perforations
corresponds to approximately 50% of the screw height.
[0034] A feed screw 10 is also shown in FIG. 4 and FIG. 5. Here, a
coupling shaft 32 is provided as drive component. A screw 14 is
welded on to the coupling shaft 32 in the region between the joint
components 30 which, as with all other exemplary embodiments,
consists of individual screw segments. This embodiment of the screw
14 is employed for instance with low-viscosity media. By way of the
large face areas 28 compared with the areas of the perforations 24,
more medium enters the rotor region while the smaller dimensioned
perforations nevertheless prevent an increased need for drive
power.
[0035] The arrangement of the perforations 24 and their size of the
feed screw 10 shown in FIGS. 4 and 5 is shown in FIG. 6. Per screw
pitch, three perforations each offset by 120.degree. are provided
in the screw 14.
[0036] Additional exemplary embodiments for the screw design for
one winding each are shown in FIGS. 7, 8, 9.
[0037] FIG. 7 represents an even distribution of 6 perforations 24
and webs 26. The height HD of the perforations is 50% compared with
the height HS of the screw 14. The width BD of the perforations
corresponds to the width BS of the webs.
[0038] In FIG. 8 the screw 14 has four perforations 24 and four
webs 26 while the width BD of the perforations is greater than the
width BS of the webs. The height HD of the perforations 24 is 50%
of the height HS of the screw 14.
[0039] The interrupted lines of FIG. 9 shows different size
relationships with regard to the height HD of the perforations to
the height HD of the screw 14, while three perforations 24 are
shown with a division by 120.
* * * * *