Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1998-01-20
2001-05-08
Bucci, David A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06227712
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of coal pulverizer mills and in particular to lubrication of internal bearings located in a gear box of a coal pulverizer mill, especially a B&W MPS-type mill.
2. Description of the Related Art
Coal pulverizer mills are used to grind coal for combustion in industrial power plants. B&W's MPS-type mills are one type of coal pulverizer which have been used for approximately the past thirty years. The B&W MPS mills use a rotating grinding mechanism to crush coal chunks into finer particles for combustion.
The coal grinding mechanism is driven by an electric motor through a gear reducer contained in a gear casing. The bearings inside the gear casing must be lubricated to prevent lock-ups and excessive wear on the bearing surfaces. Lubricating oil is used for this purpose. However, oil leaks at two bearing locations in the gear casing are a recurring problem with these gear casings.
As seen in
FIG. 1
, a bearing casing
10
has several bearing positions, two of which are known as bearing position four
30
and bearing position five
20
. The oil leaks which occur in these types of bearing casings
10
occur at bearing positions four and five
30
,
20
.
FIG. 2
shows a prior art gear casing configuration of the bearing positions
20
,
30
from the side and helps to explain how the oil leaks occur. Each bearing position
20
,
30
has a bearing cartridge
28
,
38
with an annular groove
26
,
36
around its circumference. Oil is supplied to each groove
26
,
36
through oil tube
40
located between the bearing positions
20
,
30
. Oil moves from the grooves
26
,
36
through an opening in the bearing cartridges
28
,
38
into bearing top chambers
22
,
32
of each bearing position
20
,
30
, respectively. To prevent oil from leaking out the top of the gear casing
10
, an O-ring
24
,
34
is provided around the top of each bearing cartridge
28
,
38
above the annular grooves. Unfortunately, over time these O-rings
24
,
34
harden and lose their seal between the gear casing
10
and bearing cartridges
28
,
38
.
Conventionally, this oil leak problem has been solved by stopping oil flow to annular grooves
26
,
36
, redirecting the oil flow from a manifold
200
(not shown in
FIG. 2
) through a pair of external hoses, connected to covers
21
,
31
and into bearing top chambers
22
,
32
. Several parts are required to effect this alteration to the oil flow path. This solution is not entirely satisfactory since external hoses present in an industrial setting, such as a power plant, are subject to being cut, corroded, crimped or otherwise damaged. Further, due to the complexity of the alteration of the oil flow path involved, it is not uncommon for the alteration to be made incorrectly, which can lead to continued oil leaks and failure of the bearings.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved oil flow path for gear casings of B&W MPS-type pulverizer mills which eliminates many of the disadvantages of the prior solution for preventing oil leaks.
It is a further object of the invention to provide an improved oil flow path which is simplified, located inside the gear casing and eliminates operating oil pressure against O-ring seals, thereby eliminating the possibility of leaks through these seals.
A further object of the invention is to make manufacture of bearing cartridges holding the gear shafts in place simpler by eliminating some machining on the bearing cartridges.
Accordingly, an improved oil flow path is provided through the gear casing of a B&W MPS-type pulverizer mill for the numbers
4
and
5
bearing positions. The improved flow path has bearing cartridges for each bearing position with passageways through the body for delivering oil from an internal supply hose and/or pipe to the bearing top chamber of each bearing position. A swivel fitting is connected to the bottom of each passageway for making the connection to the supply hose and/or pipe.
Alternatively, a simple block connector mounted to the bottom of each passageway may be used in place of the swivel fitting.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.
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Bucci David A.
Edwards Robert J.
Hansen Colby
Kalka Daniel S.
Marich Eric
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