U.S. patent application number 14/081717 was filed with the patent office on 2015-05-21 for internal gear pump.
This patent application is currently assigned to VIKING PUMP, INC.. The applicant listed for this patent is VIKING PUMP, INC.. Invention is credited to Kelly J. Bohlen, John A. Dutcher, III, John Howard Hall, Jeffrey Scott Meessmann, Mike Ramsey, Joseph P. Thompson.
Application Number | 20150139792 14/081717 |
Document ID | / |
Family ID | 53173489 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150139792 |
Kind Code |
A1 |
Ramsey; Mike ; et
al. |
May 21, 2015 |
Internal Gear Pump
Abstract
An internal gear pump with a field replaceable idler is
disclosed that may be used for sanitary applications. Access to the
idler mainly requires removal of the head. Access to the seal
assembly disposed at the inboard end of the pump chamber is also
fast and easy as removal of the head exposes a fastener that
secures the rotor to the drive shaft. Removal of this fastener
enables the rotor to be removed with a standard rotor pulling tool
thereby exposing the pump chamber seal assembly which may be
cleaned, serviced or replaced as needed.
Inventors: |
Ramsey; Mike; (Evansdale,
IA) ; Hall; John Howard; (Cedar Falls, IA) ;
Meessmann; Jeffrey Scott; (Cedar Falls, IA) ;
Thompson; Joseph P.; (Cedar Falls, IA) ; Dutcher,
III; John A.; (Cedar Falls, IA) ; Bohlen; Kelly
J.; (Shell Rock, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VIKING PUMP, INC. |
Cedar Falls |
IA |
US |
|
|
Assignee: |
VIKING PUMP, INC.
Cedar Falls
IA
|
Family ID: |
53173489 |
Appl. No.: |
14/081717 |
Filed: |
November 15, 2013 |
Current U.S.
Class: |
415/213.1 |
Current CPC
Class: |
F04C 15/0096 20130101;
F04C 13/005 20130101; F04D 29/126 20130101; F04C 2/10 20130101;
F04C 2230/70 20130101; F04C 2240/30 20130101 |
Class at
Publication: |
415/213.1 |
International
Class: |
F04C 15/00 20060101
F04C015/00; F04C 2/08 20060101 F04C002/08; F04D 29/12 20060101
F04D029/12 |
Claims
1. A pump comprising: a bracket including an inboard end, an
outboard end and a through hole extending between the inboard and
outboard ends; the outboard end of the bracket being coupled to an
inboard end of a case, the inboard end of the case including an
opening, the case further including an open outboard end that is
covered by and coupled to a head, the case and head defining a pump
chamber, the inboard end of the case further including an annular
recess that surrounds the opening and that receives a seal
assembly; a shaft including an inboard end and an outboard end, the
shaft passing through the through hole of the bracket, the outboard
end of the shaft passing through the seal assembly and the inboard
end of the case before being detachably coupled to a rotor, the
rotor being received in the pump chamber; the head being sealably
and detachably coupled to a dowel, the dowel being coaxially
received in and coupled to an idler that is disposed in the pump
chamber; whereby removal of the head and rotor providing access to
the seal assembly through the open outboard end of the case and
removal of the head providing access to the idler.
2. The pump of claim 1 wherein the dowel includes an inboard end
disposed axially within the idler and an outboard end that is
coupled to the head with a fastener, the pump further comprising a
seal disposed between the dowel and the head that isolates the
fastener from the pump chamber.
3. The pump of claim 2 wherein the fastener passes through the
head.
4. The pump of claim 1 wherein the dowel includes an inboard end
disposed within the idler and an outboard end that is received
within a recess disposed within the head, the pump further
comprising a seal disposed between the dowel and the head that
isolates the recess from the pump chamber.
5. The pump of claim 2 wherein the seal is an o-ring.
6. The pump of claim 4 wherein the seal is an o-ring.
7. The pump of claim 2 wherein the dowel is coupled to the idler by
a bushing, and wherein the idler, bushing and dowel can be removed
from the pump chamber and from the head by detaching the fastener
from the head.
8. The pump of claim 4 wherein the outboard end of the dowel has an
outboard diameter and the inboard end of the dowel has an inboard
diameter that is larger than the outboard diameter with a shoulder
disposed between the inboard and outboard ends of the dowel, and
wherein the seal is sandwiched between the idler and the
shoulder.
9. The pump of claim 7 wherein the outboard end of the dowel has an
outboard diameter and the inboard end of the dowel has an inboard
diameter that is larger than the outboard diameter with a shoulder
disposed between the inboard and outboard ends of the dowel, the
outboard end of the dowel being disposed within a recess disposed
in the head, the fastener being coaxial with the dowel and the
recess, and wherein the seal is disposed between the idler, the
bushing and the shoulder.
10. The pump of claim 1 wherein the dowel includes an outboard end
having an outboard diameter and an inboard end having an inboard
diameter that is larger than the outboard diameter with a shoulder
disposed between the inboard and outboard ends of the dowel, the
outboard end of the dowel being disposed within a recess disposed
in an inboard side of the head, the inboard end of the head further
including a slot that encircles the recess; the pump further
comprising a seal disposed in the slot that isolates the outboard
end of the dowel from the pump chamber.
11. The pump of claim 2 further including a bushing disposed
between the idler and the dowel, and the bushing being press-fit
onto the dowel and the idler being press-fit onto the bushing.
12. The pump of claim 10 wherein the idler is polymeric.
13. The pump of claim 11 wherein the bushing is ceramic.
14. The pump of claim 1 further comprising a tube that extends
between the case and the bracket and about an axis of the shaft;
and wherein the tube is in communication with a source of heat
transfer fluid.
15. A pump comprising: a bracket including an inboard end, an
outboard end and a through hole extending between the inboard and
outboard ends; the outboard end of the bracket being coupled to an
inboard end of a case, the inboard end of the case including an
opening, the case further including an open outboard end that is
covered by and coupled to a head, the case and head defining a pump
chamber, the inboard end of the case further including an annular
recess that surrounds the opening and that receives a seal
assembly; a shaft including an inboard end and an outboard end, the
shaft passing through the through hole of the bracket, the outboard
end of the shaft passing through the seal assembly and the inboard
end of the case before being detachably coupled to a rotor, the
rotor being received in the pump chamber; at least one of the case
and/or bracket including a peripheral channel that accommodates a
tube that extends about a central axis of the through hole, shaft
and seal assembly, the tube being in communication with a supply of
heat transfer fluid; a dowel coaxially received in and coupled to
an idler that is disposed in the pump chamber; removal of the head
and rotor providing access to the seal assembly through the open
outboard end of the case; the dowel including an inboard end
disposed axially within the idler and an outboard end that is
received within a recess disposed in the head, the outboard end of
the dowel being detachably coupled to the head by a fastener; and
the pump further comprising a seal disposed between the dowel and
the head that isolates the fastener from the pump chamber.
16. The pump of claim 15 wherein the seal is an o-ring.
17. The pump of claim 15 wherein the dowel is coupled to the idler
by a bushing; and wherein the idler, bushing and dowel can be
removed from the chamber and head by detaching the fastener from
the head.
18. The pump of claim 15 wherein the outboard end of the dowel has
an outboard diameter and the inboard end of the dowel has an
inboard diameter that is larger than the outboard diameter with a
shoulder disposed between the inboard and outboard ends of the
dowel, and wherein the seal is sandwiched between the idler and the
shoulder.
19. The pump of claim 15 wherein the outboard end of the dowel has
an outboard diameter and the inboard end of the dowel has an
inboard diameter that is larger than the outboard diameter with a
shoulder disposed between the inboard and outboard ends of the
dowel, the outboard end of the dowel being disposed within a recess
disposed in an inboard side of the head, the inboard side of the
head further including a slot that encircles the recess; the pump
further comprising a seal disposed in the slot that isolates the
outboard end of the dowel from the pump chamber.
20. A pump comprising: a bracket including an inboard end, an
outboard end and a through hole extending between the inboard and
outboard ends; the outboard end of the bracket being coupled to an
inboard end of a case, the inboard end of the case including an
opening, the case further including an open outboard end that is
covered by and coupled to a head, the case and head defining a pump
chamber, the inboard end of the case further including an annular
recess that surrounds the opening and that receives a seal
assembly; a shaft including an inboard end and an outboard end, the
shaft passing through the through hole of the bracket, the outboard
end of the shaft passing through the seal assembly and the inboard
end of the case before being detachably coupled to a rotor, the
rotor being received in the pump chamber; a dowel coaxially
received in and press fitted into a polymeric idler with a ceramic
bushing annularly disposed between the dowel and idler, the idler
being disposed in the pump chamber; removal of the head and rotor
providing access to the seal assembly through the open outboard end
of the case; the dowel including an inboard end disposed axially
and within the idler and an outboard end that is received within a
recess disposed in the head, the outboard end of the dowel being
detachably coupled to the head by a fastener; and the pump further
comprising a seal disposed between the dowel and the head that
isolates the fastener from the pump chamber.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] This disclosure relates generally to internal gear pumps.
More specifically, this disclosure relates to internal gear pumps
including: a field replaceable idler; a heating/cooling tube for
maintaining proper pumping temperature; a seal assembly for the
pump chamber that may be replaced, cleaned or serviced without
removing the drive shaft; and an improved idler assembly that
includes a polymeric idler, a ceramic bushing, and a dowel that are
press-fit together.
[0003] 2. Description of the Related Art
[0004] A positive displacement pump causes fluid to move by
trapping fluid and then forcing or displacing the trapped fluid
through an outlet. Positive displacement rotary pumps are pumps
that move fluid using the principles of rotation. At the inlet to
the pump, the rotation captures and draws the fluid into the pump
chamber before trapping the fluid and passing it through the
outlet. Various types of rotary pumps are available, including, but
not limited to internal and external gear pumps, screw pumps,
flexible vane or sliding vane pumps, liquid ring vacuum pumps,
circumferential piston pumps, rotary lobe pumps, etc. While this
disclosure uses internal gear pumps as primary examples, one
skilled in the art will realize that the principles disclosed
herein are applicable to other types of rotary pumps as well.
[0005] Among the applications for rotary positive displacement
pumps are sanitary applications. These include pharmaceutical,
biomedical, food, personal care, cosmetics and the like. Only a few
types of rotary sanitary pumps serve these markets. One type is
rotary lobe pump, which may include an external gearbox. The
gearbox is used to time or position the pump rotors (or lobes) such
that they rotate in correct relationship with one another within
the pump chamber. The rotors are typically non-contacting but in
close tolerance to each other. A variation on the rotary lobe pump
is the circumferential piston pump, where the lobe-type rotors are
replaced with circumferential piston-type rotors. In either case,
these pumps are expensive by virtue of their complexity and
extensive and robust construction requirements.
[0006] Sanitary rotary positive displacement pumps, regardless of
type, share common characteristics. First, such pumps must be
designed such that they can be quickly and easily disassembled for
easy and thorough inspection and cleaning of the fluid pathway.
Typically, the pump components are made from stainless steel to
protect against contamination of the fluid and corrosion of the
contact surfaces. Because the seals that isolate the pump chamber
are periodically replaced, the seal structures are typically simple
in design. Sanitary rotary positive displacement pumps should be
able to operate at low speeds (RPMs) for gentle liquid handling and
they should be able to operate at both high and low temperatures
with liquids having high or low viscosities. Finally, sanitary
rotary positive displacement pumps must conform to recognized
sanitary standards which may vary depending upon the specific
application.
[0007] Notably absent from sanitary rotary positive displacement
pump types are gear pumps. This may be true because the fluid
pathway of most gear pumps is not easily accessible for cleaning,
even though the components of gear pumps may be fabricated from
materials appropriate for sanitary use, such as stainless steel.
Further, external gear pumps are unsuitable for sanitary service
because the bearings, which support the two gear shafts, are
usually internal to the pump and in contact with the liquid being
pumped. Most bearing materials cannot come into contact with
sanitary liquids. Further, the bearings are not easy to access and
clean, which is necessary for a sanitary application.
[0008] In the case of an internal gear pump, the European Hygienic
Engineering and Design Group (EHEDG) guidelines do not permit the
idler pin of an internal gear pump to be press-fit onto its head
because EHEDG guidelines do not allow for a press-fit between any
two metal components disposed in a sanitary pump chamber or that
come into contact with the fluid being pumped. Press-fit
connections must be sealed by a gasket that is replaceable.
Otherwise, the joint must be permanently welded or soldered. All of
these alternatives would significantly add to the cost of an
internal gear pump so it could be used in sanitary
applications.
[0009] Another problem associated with the use of gear pumps for
sanitary applications is the need for heating or cooling of the
fluid being pumped. Normally, a gear pump is heated or cooled with
either a jacket or a resistance heating system. However, in
sanitary applications, the outboard end or head of the pump case
must be exposed or easily accessible to satisfy sanitary
regulations. As a result, traditional heating/cooling methods are
rendered inefficient because of air gaps between the
heating/cooling system and the head.
[0010] Thus, because of the limitations of rotary gear pumps when
used in sanitary applications or applications where purity is
important, there is a need for improved rotary gear pumps, which
satisfy and meet the requirements for sanitary service, such as
easy and fast tear down for easy cleaning and inspection as well as
the use of corrosion resistant construction materials.
SUMMARY OF THE DISCLOSURE
[0011] In one aspect, a pump is disclosed that includes a bracket
having an inboard end and an outboard end. A through hole extends
through the bracket between the inboard and the outboard ends. For
purposes of this disclosure, the inboard end of the pump or a pump
component is the end that is closest to the motor while the
outboard end is directed away from the motor, towards or past the
pump chamber. The outboard end of the bracket may be coupled to an
inboard end of a case. The inboard end of the case may include an
opening. The case may further include an open outboard end that is
covered by and coupled to a head. The case and the head may define
a pump chamber. The inboard end of the case may further include an
annular recess that surrounds the opening and that receives a seal
assembly. The pump may further include a shaft that has an inboard
end and an outboard end. The shaft may pass through the through
hole of the bracket. The outboard end of the shaft may pass through
the seal assembly and the inboard end of the case before the
outboard end of the shaft is detachably coupled to a rotor. The
rotor may be received in the pump chamber. The head may be sealably
and detachably coupled to a dowel. The dowel may be coaxially
received in and coupled to an idler. The idler may also be disposed
in the pump chamber. As a result, removal of the head provides
access to the idler and removal of the rotor from the shaft
provides access to the seal assembly through the open outboard end
of the case and removal of the head from the case.
[0012] In another aspect, a pump is disclosed that also includes a
bracket having an inboard end and an outboard end as well as a
through hole that extends between the inboard and outboard ends of
the bracket. The outboard end of the bracket may be coupled to an
inboard end of the case. The inboard end of the case may include an
opening. The case may further include an open outboard end that is
covered by and coupled to a head. The case and head may define a
pump chamber. The inboard end of the case may further include a
recess that surrounds the opening and that receives a seal
assembly. The pump may further include a shaft having an inboard
end and outboard end. The shaft may pass through the through hole
of the bracket with the outboard end of the shaft passing through
the seal assembly and the inboard end of the case before being
detachably coupled to a rotor. The rotor may be received in the
pump chamber. At least one of the case and/or the bracket may
include a peripheral channel that accommodates a tube that extends
about a central axis of the through hole, shaft and seal assembly.
The tube may be in communication with a supply of heat transfer
fluid for either heating or cooling the pump. The pump may further
include a dowel that is coaxially received and coupled to an idler
that may be disposed in the pump chamber. Removal of the head and
rotor may provide access to the seal assembly through the open
outboard end of the case. Further, the dowel may include an inboard
end disposed axially within the idler and an outboard end that is
received within a recess disposed in the head. The outboard end of
the dowel may be detachably coupled to the head by a fastener. The
pump may further include a seal disposed between the dowel and the
head that isolates the fastener from the pump chamber.
[0013] In yet another aspect, another pump is disclosed that also
includes a bracket having an inboard end and an outboard end and a
through hole extending between the inboard and outboard ends. The
outboard end of the bracket may be coupled to an inboard end of a
case. The inboard end of the case may include an opening. The case
may further include an open outboard end that is covered by and
coupled to a head. The case and head may define a pump chamber. The
inboard end of the case may further include an annular recess that
surrounds the opening and that receives a seal assembly. The pump
may further include a shaft with an inboard end and an outboard
end. The shaft may pass through the through hole of the bracket.
The outboard end of the shaft may pass through the seal assembly
and the inboard end of the case before being detachably coupled to
a rotor. The rotor may be received in the pump chamber. A dowel may
be coaxially received in and press-fitted into a polymeric idler
with a ceramic bushing annularly disposed between the dowel and the
idler. The idler may be disposed in the pump chamber. Removal of
the head and the rotor may provide access to the seal assembly
through the open outboard end of the case. The dowel may further
include an inboard end disposed axially within the idler and an
outboard end that is received within a recess disposed in the head.
The outboard end of the dowel may be detachably coupled to the head
by a fastener. The pump may further include a seal disposed between
the dowel and the head that isolates the fastener from the pump
chamber.
[0014] In any one or more of the embodiments described above, the
fastener may pass through the head.
[0015] In any one or more of the embodiments described above, the
seal disposed between the dowel and the head that isolates either
the recess from the pump chamber or the fastener from the pump
chamber may be an o-ring.
[0016] In any one or more of the embodiments described above, the
dowel may be coupled to the idler by a bushing and wherein the
idler, bushing and dowel can be removed from the pump chamber and
from the head by detaching the fastener from the head.
[0017] In any one or more of the embodiments described above, the
outboard end of the dowel has an outboard diameter and the inboard
end of the dowel has an inboard diameter that is larger than the
outboard diameter and the dowel may also include a shoulder
disposed between the inboard and outboard ends of the dowel. The
pump may further include a seal sandwiched between the idler and
the shoulder. In a further refinement of this concept, a fastener
may be used to secure the dowel to the head wherein the fastener is
coaxial with the dowel and the recess in the head. In still yet a
further refinement, the seal may be disposed between the idler, the
bushing and the shoulder.
[0018] In yet a further refinement, the head may further include a
slot that encircles the recess in the head that receives the
outboard end of the dowel. The seal may be disposed in the
slot.
[0019] In any one or more of the embodiments described above, a
bushing may be disposed between the idler and the dowel and the
bushing may be press-fit onto the dowel and the idler may be
press-fit onto the bushing.
[0020] In any one or more of the embodiments described above, the
idler may be polymeric. While a variety of polymers may be
employed, one suitable polymer is polyoxymethylene.
[0021] In any one or more of the embodiments described above, the
bushing may be ceramic. While a variety of ceramic materials may be
utilized, carbon graphite and silicon carbide are two such ceramic
materials that are suitable for use for the bushing.
[0022] In any one or more of the embodiments described above, the
pump further includes a tube that extends between the case and the
bracket and about the axis of the shaft. The tube may be in
communication with the source of heat transfer fluid.
[0023] Other advantages and features will be apparent from the
following detailed description when read in conjunction with the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] For a more complete understanding of the disclosed methods
and apparatuses, reference should not be made to the embodiment
illustrated in greater detail on the accompanying drawings,
wherein:
[0025] FIG. 1 is a perspective view of a disclosed pump.
[0026] FIG. 2 is a side plan view of the pump shown in FIG. 1.
[0027] FIG. 3 is an end view of the pump shown in FIGS. 1-2.
[0028] FIG. 4 is a sectional view taken substantially along line
4-4 of FIG. 2.
[0029] FIG. 5 is a partial sectional view taken substantially along
the line 5-5 of FIG. 3.
[0030] FIG. 6 is an enlarged view of the seal assembly shown in
FIGS. 4-5.
[0031] FIG. 7 is an enlarged partial sectional view of the head,
fastener, dowel, bushing and idler of the pump as shown in FIG.
4.
[0032] It should be understood that the drawings are not
necessarily to scale and that the disclosed embodiments are
sometimes illustrated diagrammatically and in partial views. In
certain instances, details which are not necessary for an
understanding of the disclosed methods and apparatuses or which
render other details difficult to perceive may have been omitted.
It should be understood, of course, that this disclosure is not
limited to the particular embodiments illustrated herein.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0033] In FIG. 1, a pump 10 is disclosed that includes a bracket 11
that may be coupled to a case 12. As also shown in FIG. 2, the
bracket 11 includes an inboard end 13 and an outboard end 14.
Further, the case 12 also may include an inboard end 15 and an open
outboard end 16 that may be coupled to a head 17. The head 17 may
be sandwiched between the open outboard end 16 of the case 12 in a
cover 18. The case 12 may further include inlet and outlet ports
21, 22. Referring to FIGS. 1-3 together, a tube 23 may encircle a
central axis of the pump 10 between the case 12 and the bracket 11.
As discussed in greater detail below and shown schematically in
FIG. 3, the tube 23 may be in communication with a fluid reservoir
24 which, in turn, may be in communication with a pump 25 that is
also in communication with the tube 23. The tube 23 may carry heat
transfer fluid around the pump for purposes of maintaining a proper
temperature for pumping. The cover 18 may be coupled to the case 12
and head 17 by one or more fasteners 26 that extend through the
cover 18, head 17 and into the case 12 as shown in FIG. 4. Further,
the cover 18, head 17 and case 12 may be secured to the brackets
with a plurality of studs 27 that extend through the cover 18, the
head 17, the case 12 and into the outboard end 14 of the bracket 11
as shown in the sectional view of FIG. 5.
[0034] Turning to FIG. 4, a sectional view of the pump 10 is shown
that illustrates a through hole 28 that extends through the bracket
11 and that may accommodate a drive shaft 31 that also has an
inboard end 32 that may be coupled to a motor (not shown) and
outboard end 33 that may be coupled to a rotor 34. The shaft 31 may
pass through bearing assembly 35 that may include a bearing housing
36, bearings 37, both of which may be held in place in the inboard
end 13 of the bracket 11 by a locknut 38. The inboard end 13 of the
bracket 11 may include and opening or enlargement of the through
hole 28 as well as a recess 41 for accommodating the bearing
assembly 35. While the bearing assembly 35 supports the inboard end
32 of the shaft 31, an additional bearing assembly 41 may support
the outboard end 33 of the shaft 31 and may be accommodated in a
recess 42 disposed in the outboard end 14 of the bracket 11 as
shown in FIG. 4.
[0035] FIG. 4 also illustrates the cooling/heating tube 23, which
is in close proximity to the bearing assembly 41 and the seal
assembly 43. The seal assembly 43 isolates the bearing assembly 41
from the pump chamber 45 that is defined by the case 12 and head
17. The pump chamber may accommodate the rotor 34 as well as the
idler 46. The idler 46 may be coupled to the head 17 by a fastener
47 and a dowel 48. The idler 46 slides over the dowel 48 and
bushing 51 as shown in FIG. 7. To isolate the fastener 47 from the
pump chamber, a seal 52 may be disposed between the dowel 48 and
head 17 as shown in FIG. 7. More specifically, the dowel 48 may
include a wider inboard end 53 and a narrower outboard end 54 that
is received within a recess 55 disposed in the head 17 as shown in
FIG. 7. The seal 52 may isolate the recess 55, fastener 47, and
anti-rotation pin 56 from the pump chamber 45.
[0036] The seal assembly 43 is illustrated in greater detail in
FIG. 6. The seal assembly 43 is secured to the case 12 by a
fastener 58 and an anti-rotation washer 59. A shim 61 may be
employed to provide the correct amount of pressure between the seal
element 62 and the washer 63 disposed within a recess 64 that is
disposed in the inboard end 65 of the rotor 34. Because the seal
assembly 43 is secured to the case 12, removal of the cover 18 and
head 17 followed by detachment of the rotor 34 from the outboard
end 33 of the shaft 31 provides easy access to the seal assembly 43
for cleaning, servicing, removal and/or replacement.
[0037] As shown in FIG. 5 the rotor 34 is detachably connected to
the shaft 31 or, more specifically, the outboard end 33 of the
shaft 31 by the fastener 67. The fastener 67 is exposed by removing
the cover 18 and head 17 because the head 17 is coupled to the
idler 46 by way of the fastener 47, dowel 48, and bushing 51. Thus,
because the idler 46 may be easily removed from the head 17,
replacement of the idler 46 is a fast and easy maintenance task.
Similarly, because removal of the cover 18, head 17 and idler 46
exposes the fastener 67 that secures the rotor 34 to the shaft 31,
the rotor 34 may be easily removed from the pump chamber 45 using a
simple tool after the fastener 67 has been decoupled from the shaft
31 and the rotor 34.
[0038] Thus, the pump 10 includes important improvements in terms
of maintenance and service. The rotor 34 is easily exposed by
removing the cover 18 and head 17 as the idler 46 is removed from
the pump chamber 45 when the head 17 is removed. This exposes the
fastener 67 and the plate 71, which secure the rotor 34 to the
shaft 31. Removal of the fastener 67 enables an easy removal of the
rotor 34 which exposes the seal assembly 43 for service,
maintenance or replacement. With the rotor 34 removed, the entire
pump chamber 45 may be easily cleaned and/or sanitized.
[0039] The idler 46 may be fabricated from a polymeric material.
One suitable material is polyoxymethylene, also known as acetal,
polyacetal and polyformaldehyde. Other suitable thermoplastic
materials for use in such precision parts are available as will be
apparent to those skilled in the art. A bushing 51 may be disposed
between the dowel 48 and the idler 46. The bushing 51 may be made
from a ceramic material, with two possibilities being carbon
graphite and silicon carbide. Other suitable ceramic materials for
a bushing disposed between a polymeric idler 46 and a metallic
dowel 47 will be apparent to those skilled in the art.
[0040] Finally, returning to FIG. 5, the fastener 67 that secures
the shaft 31 to the rotor 34 passes through a washer or plate 71. A
seal 72 may be disposed between the plate 71 and the rotor 34 and
an additional seal 73 may be disposed between the fastener 67 and
the plate 71 to further ensure that contaminants cannot migrate in
an outboard direction and enter the pump chamber 45.
INDUSTRIAL APPLICABILITY
[0041] An improved internal gear pump is disclosed that is suitable
for sanitary applications and/or applications were purity of the
pumped product is important. As opposed to prior art pumps which
require removal of the drive shaft to replace the seal assembly
that seals the pump chamber from the bearing assembly that supports
the drive shaft, the seal assembly of the disclosed pump may be
serviced, cleaned and/or replaced with very few steps. The cover
and head plate are removed. Removal of the head plate also results
in removal of the idler as the idler is detachably secured to the
head. With the idler removed, a fastener that detachably secures
the rotor to the outboard end of the shaft is exposed. Removal of
this fastener enables the rotor to be removed from the pump chamber
with the use of a conventional rotor pulling tool. With the rotor
removed, the seal assembly is exposed and the entire pump chamber
and seal assembly may be cleaned. Further, the seal assembly may be
removed or serviced. Reassembly of the pump is also fast and easy
as the rotor is secured back on to the outboard end of the shaft
with the fastener.
[0042] The idler may also be easily replaced as the idler is
secured to the head with a single fastener. The idler may be a
polymeric material that may be press-fitted on to a dowel with a
bushing disposed therebetween. A single fastener may be used to
secure the idler to the head. Rotation of the dowel may be
prevented with a pin.
[0043] Thus, an internal gear pump with separate shaft and rotor
elements is disclosed. Because the shaft does not need to be
removed to service the seal assembly that seals the inboard end of
the pump chamber from the bearings, the seal assembly may be
serviced without the need to reset the pump end clearance. Thus,
the seal assembly of the disclosed internal gear pump may be
replaced from the outboard end or head end of the pump with minimal
disassembly. The disclosed internal gear pump does not require
resetting the end clearance after replacement or servicing of the
seal and/or cleaning behind the rotor. Thus, the pump may be
cleaned and maintained without risk to the operating efficiency of
the pump. Specifically, resetting the end clearance of an internal
gear pump requires skill and time. If the end clearance is not set
correctly, the pump can be damaged or operate less efficiently.
[0044] Further, the disclosed internal gear pump is a positive
displacement pump equipped with a field replaceable idler that
meets the EHEDG criteria because the seal is disposed between the
idler and the head thereby isolating the fastener that secures the
idler to the head from the pump chamber. The disclosed pump also
has an effective heating and cooling system with a tube that
extends about the axis of the shaft between the bracket and case
for maintaining the shaft support bearing assembly and the pump
chamber seal assembly at the proper pumping temperature.
[0045] While only certain embodiments have been set forth,
alternatives and modifications will be apparent from the above
description to those skilled in the art. These and other
alternatives are considered equivalents and within the spirit and
scope of this disclosure and the appended claims.
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