Title: Diesel engine water pump with improved oil control
Abstract: An improved diesel engine water pump includes three main features that aid in extending the maintenance-free life of the pump. The impeller shaft is carried by tapered roller shaft support bearings of which the impeller bearing has a floating outer race that is urged axially by a preload spring to provide a prescribed axial preload that maintains concentricity of the shaft with the axis and prolongs bearing life. An improved oil seal combines an oil slinger, a stationary deflector and a lip oil seal with a return passage to the engine to more effectively limit oil leakage from the pump. An improved water seal includes pressurized water jets fed from the pump volute that flush wear particles from the water seal surface and increase water seal life. Further details of these features are also disclosed.
Patent Number: 6,929,449 Issued on 08/16/2005 to Zagone, et al.
| Inventors:
|
Zagone; John R. (Westmont, IL);
Duerr; Werner C. (Westchester, IL);
Kane; Thomas J. (Naperville, IL);
Albright; Randal K. (Montgomery, IL)
|
| Assignee:
|
Electro-Motive Diesel, Inc. (LaGrange, IL)
|
| Appl. No.:
|
423361 |
| Filed:
|
April 25, 2003 |
| Current U.S. Class: |
415/206; 415/110; 415/229 |
| Intern'l Class: |
F01D 001/02 |
| Field of Search: |
415/203,206,229,110,111,112
|
References Cited [Referenced By]
U.S. Patent Documents
| 2977042 | Mar., 1961 | Jassinker.
| |
| 3429268 | Feb., 1969 | Camac et al.
| |
| 3796510 | Mar., 1974 | Korrenn et al.
| |
| 3838901 | Oct., 1974 | Sampatacos.
| |
| 4172310 | Oct., 1979 | Mincuzzi.
| |
| 4487557 | Dec., 1984 | Ruyak et al.
| |
| 6099243 | Aug., 2000 | Fiore.
| |
| Foreign Patent Documents |
| 2046372 | Nov., 1980 | GB.
| |
Primary Examiner: Nguyen; Hoang
Attorney, Agent or Firm: Cook, Alex, McFarron, Manzo, Cummings & Mehler, Ltd.
Claims
1. A water pump of the centrifugal type adapted for use in diesel engine cooling
systems, the water pump comprising:
a housing containing a shaft rotatable on an axis extending through the housing,
the shaft mounting a drive member adjacent a drive end of the housing and a fluid
impeller at an opposite impeller end of the housing;
axially spaced drive and impeller bearings mounted in an oil lubricated recess
and supporting the shaft in the housing, each bearing having an inner race fixed
on the shaft and an outer race mounted in the housing, and
an oil control in the lubricated recess and including an oil slinger mounted
on the rotatable shaft adjacent the impeller bearing and operative to centrifugally
direct oil from the impeller bearing into a collector connected with an oil return
passage.
2. A water pump as in claim 1 wherein the oil control further includes a stationary
oil seal having a deflector extending inward from the housing adjacent the oil
slinger and operative to deflect bypassed oil into the return passage and a seal
lip engaging the shaft and blocking the passage of bypassed oil along the shaft
toward the fluid impeller.
3. A water pump as in claim 1 wherein the oil slinger is mounted on the inner
race of the impeller bearing.
4. A water pump as in claim 3 wherein the oil control further includes a stationary
oil seal having a deflector extending inward from the housing adjacent the oil
slinger and operative to deflect bypassed oil into the return passage and a seal
lip engaging the shaft and blocking the passage of bypassed oil along the shaft
toward the fluid impeller.
5. A water pump an in claim 3 wherein:
the bearings are roller bearings;
the outer race of the impeller bearing is axially slidable in the housing; and
a biasing clement is positioned between the housing and the outer race of the
impeller bearing, the biasing element preloading the impeller bearing with a selected
preload force maintained to maximize bearing life and concentric rotation of the
shaft over all operating conditions of the pump.
6. A water pump as in claim 5 wherein the oil control further includes a stationary
oil seal having a deflector extending inward from the housing adjacent the oil
slinger and operative to deflect bypassed oil into the return passage and a seal
lip engaging the shaft and blocking the passage of bypassed oil along the shaft
toward the fluid impeller.
Description
TECHNICAL FIELD
This invention relates to water pumps of the centrifugal impeller type intended
primarily for use in diesel engine cooling systems, especially for railroad locomotives,
but also useful for other purposes.
BACKGROUND OF THE INVENTION
It is known in the art relating to diesel engine cooling systems to provide an
engine with one or more centrifugal water pumps, each having a centrifugal flow
or mixed flow impeller carried on a shaft and driven by a drive gear or other drive
means. The shaft is supported on spaced bearings carried in a housing and lubricated
by oil flow from the associated engine oil system. Both ball and roller bearings
have been used in the past to carry rotary support loads and axial thrust forces
acting on the shaft.
Oil passing through the impeller end bearing is returned to the engine oil sump
through a drain line or passage in the water pump housing. A lip-type oil seal
is conventionally utilized to prevent oil from passing along the shaft into the
water impeller portion of the pump. Similarly, a conventional cartridge-type carbon
water seal running against an annular seal surface has been used to prevent the
escape of pressurized water from the impeller end of the pump into the oil lubricated portions.
SUMMARY OF THE INVENTION
The present invention provides an improved water pump construction including
multiple features which combine to provide increased operating life for the supporting
and wearing components of the pump.
The bearings utilized for support and thrust loads are preferably tapered roller-type
bearings including a drive bearing at the drive gear end for accepting drive forces
and major thrust loads developed in the impeller. An impeller tapered roller bearing
is mounted in the housing toward the impeller end and includes an inner race spaced
a fixed distance from the inner race of the drive bearing, the outer race of which
is fixed in the pump housing.
The outer race of the impeller bearing is mounted to be axially slidable in the
housing. A spring element, such as a wave spring, is mounted in the housing and
biases the outer race in a direction to provide a controlled preload on the roller
bearings. The spring maintains the bearings in a controlled preload condition which
is sufficient to absorb minor reverse thrust loads which may occur in the pump.
The preload increases bearing life by maintaining shaft concentricity and avoiding
runout, or eccentric rotation of the shaft, which could increase bearing loads
and generate wear problems.
A further feature is the additional of an oil slinger mounted on the inner race
of the impeller bearing and adapted to centrifugally direct oil passing thorough
the adjacent bearing into an annular collector groove. The groove carries the oil
to the internal oil drain passage of the pump. Any oil escaping past the oil slinger
contacts a deflector which also directs oil toward the oil drain passage. The deflector
forms part of an oil seal including a conventional lip seal for preventing any
remaining oil reaching the seal from passing through to the water side of the pump.
Still an additional feature of the improved water pump is a water seal which
includes a stationary seal member mounted in the housing and having an annular
seal surface formed on a radial wall. A rotatable seal member of conventional construction
rotates with the impeller and engages the radial seal surface to prevent water
from behind the impeller from escaping into the oil lubricated portion of the pump.
Seal life is improved by the addition of a seal flush arrangement which receives
high pressure water from the pump volute at the outlet of the impeller and directs
it through angled orifices or nozzles in a cylindrical wall of the stationary seal
member. The nozzles spray pressure water against the outer portion of the seal
surface to flush away particles of debris from seal wear. This reduces the collection
of wear particles remaining on the seal surface and embedding in the seal. Removal
of the wear particles thus increases the wear life of the seal.
These and other features and advantages of the invention will be more fully
understood from the following description of certain specific embodiments of the
invention taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The single FIGURE of the drawing is a cross-sectional view along the longitudinal
axis of the pump and illustrating the various improved features of a water pump
according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in detail, numeral
10 generally indicates
a water pump of the centrifugal type adapted for use in diesel engine cooling systems
or other suitable applications. Pump
10 includes a housing
12 containing
a shaft
14 rotatable on an axis
16 extending through the housing.
The shaft mounts a drive member in the form of a gear
18 that is carried
adjacent a drive end
20 of the housing
12.
A centrifugal impeller
22 is mounted on an opposite end of the shaft adjacent
an impeller end
24 of the housing. The impeller is contained within a volute
26 that is carried on the impeller end of the housing. The volute includes
an axial inlet opening
28 and a radial outlet
30 to direct water
or other coolant into vanes
32 of the impeller. These draw the water axially
into the impeller and expel it radially into the associated volute for discharge
to an external cooling system.
The pump shaft
14 is supported in the housing
12 by a pair of axially-spaced
tapered roller bearings including a drive bearing
34 and an impeller bearing
36. The drive bearing
34 is designed to accept major rotational loads
applied to the gear
18 as well as primary thrust loads resulting primarily
from the axial flow of the water drawn in by the water pump and expelled radially.
Bearing
34 includes an outer race
38 fixed within the housing
12
and an inner race
40 mounted on the shaft
14. The impeller bearing
36 carries primarily centrifugal loads and reverse thrust loads from the
impeller, which are limited in force.
Bearing
36 also has an outer race
42 carried in the housing
and an inner race
44 mounted on the shaft
14. The inner races
40,
44 of the bearings are fixed to the shaft along with the drive gear
18
by a nut
46 threaded on the shaft. The nut clamps the gear against the inner
race
38 of the drive bearing
34 which in turn engages a spacer tube
48 that forces the inner race
44 of the impeller bearing against
a shoulder
50 on the shaft. This fixes the spacing of the bearings and clamps
them solidly in position on the shaft.
In accordance with the invention, the outer race
42 of the impeller bearing
36 is made axially slidable in the housing. A biasing element in the form
of a wave spring
52 is mounted in the housing around the shaft and engages
the housing and the drive end of the outer race
42 of the impeller. The
spring biases race
42 axially toward the impeller and exerts a predetermined
preload force against the outer race
42. This preloads both of the shaft
bearings with a pre-selected axial thrust force.
The preload force is adequate to offset any reverse thrust forces which may be
applied against the impeller bearing while the major thrust forces are taken up
by the drive bearing
34 as previously described. The preload wave spring
52 thus provides a minimum thrust loading on the bearings which is adequate
to avoid the development of any looseness or clearance in the bearing set and thus
maintains the shaft in concentric rotation around the axis
16 within the
housing
12. The development of any centrifugal forces on the bearings due
to eccentric rotation of the shaft is thereby prevented so that bearing life is extended.
Bearings
34,
36 are lubricated within the housing by oil delivered
through a feed passage
54. The passage receives lubricating oil from a lubricated
portion of an associated engine on which the pump is mounted and directs the oil
into an annular chamber or enclosure
56 from which it may lubricate both
bearings. The impeller bearing
34 may also be lubricated by oil splash from
the adjacent engine system which can also enter the enclosure
56 to lubricate
the impeller bearing
36. Excess oil in the enclosure can escape either by
passing through the drive bearing
34 into the adjacent engine enclosure,
not shown, or by passing through the impeller bearing
36 into an annular
collector groove
58. The groove
58 connects with a drain line or
passage
60 that carries oil from the collector groove back to the associated
engine oil system for return to the engine sump.
An oil control
61 is provided in order to prevent oil from escaping from
the bearing enclosure
56 into the water side of the pump housing. The control
may include a conventional lip seal
62 mounted in the housing for engagement
of the seal lip with a seal surface of the shaft. To improve the operation of the
seal, the invention includes a radial deflector
64 extending from the body
of the lip seal and adapted to intercept oil splashed from the bearings and direct
the oil downward into the oil collector groove
58 for draining to the engine system.
In addition, the pump oil control
61 includes a radial oil slinger
66
mounted on the impeller end of the impeller bearing inner race
44. The oil
slinger
66 is positioned to centrifugally throw oil passing the bearing
36 and engaging the slinger into the collector groove
58, from which
it is directed through passage
60 to the engine lubrication system.
The combination of the three elements provided by the oil control
61 provides
a three fold arrangement for control of oil flow from the impeller bearing to the
collector and out through the drain passage
60. The conventional lip seal
forms a back up to limit the passage of any oil passing the first two elements,
that is the oil slinger
66 and the deflector
64, from escaping into
the water side of the pump.
In accordance with the invention, pump
10 includes an additional feature
comprising an improved water seal assembly
68. Assembly
68 includes
a stationary water seal member
70 which is mounted behind the impeller in
the impeller end of the housing. Member
70 includes a cylindrical wall
72
closed at one end by a radial wall
74 having a radial seal surface
76
surrounding the shaft and facing toward the impeller end of the housing.
Within the stationary member
70, a rotatable water seal member
78
is mounted on the shaft
14. Member
78 includes a shaft seal
80
adjacent to a rotatable seal ring
82 that rotates with the impeller. The
seal ring
82 has an end engaging the seal surface
76 for preventing
water flow from the water side of the pump into the oil lubricated areas at the
drive end of the housing. A conventional coil spring
84 extends between
the impeller
22 and the shaft seal
80 and biases the seal ring
82
against the seal surface
76 to maintain a positive seal against leakage.
In accordance with the invention, pressurized water from the volute
26
is delivered, such as through passages
86 and
88 in the volute and
housing respectively, to an annular groove or plenum
90. The plenum
90
connects with angled orifices or nozzles
92 extending thorough the cylindrical
wall
72 of the stationary water seal member
70. The nozzles
92
are aimed in the direction of the radial seal surface
76.
In operation of the pump, rotation of the seal ring
82 against the water
seal surface
76 causes wear particles of the ring to be dislodged from time
to time and collect adjacent the ring
82 on the seal surface. The particles
are dislodged and carried away from the seal surface by high pressure water spray
which is directed from the volute supply source to the annular groove or plenum
90 and through the nozzles
92 against the seal surface surrounding
the ring
82. The seal surface
76 is thereby maintained clear of wear
particles which would otherwise collect around the surface and impair the wear
life of the seal ring. Accordingly, the life of the seal ring is extended and longer
maintenance-free operation of the water seal is provided.
In similar fashion, the oil control
61 of the pump, including the oil
slinger
66, deflector
64 and lip seal
62, provides superior oil control
which avoids the escape of lubricating oil into the water side of the pump. This
extends the life of the lip oil seal to prevent leakage.
Finally, the wave spring
52, providing a predetermined thrust preload
on the shaft support and thrust bearings
34,
36, maintains the shaft
in fully concentric operation on its axis and thereby improves bearing life. As
a result, a water pump having an extended operating life with reduced need for
repair is provided by the present invention.
While the invention has been described by reference to certain preferred embodiments,
it should be understood that numerous changes could be made within the spirit and
scope of the inventive concepts described. Accordingly, it is intended that the
invention not be limited to the disclosed embodiments, but that it have the full
scope permitted by the language of the following claims.
*
