Abstract:
An apparatus for modifying a gear casing used in coal pulverizer mills prevents lubricating oil leaks through worn O-rings by redirecting the oil in a different path which does not come into contact with the O-ring seals. An internal hose connection provides oil directly to a bearing top chamber through a passage in the bearing cartridge. A special connector is used to connect the internal hose to the passage. Several connector embodiments are disclosed.

Description:
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&amp;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&amp;W&#39;s MPS-type mills are one type of coal pulverizer which have been used for approximately the past thirty years. The B&amp;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&amp;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&amp;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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a sectional perspective view of a gear casing used in B&amp;W MPS-type pulverizer mills; 
     FIG. 2 is an enlarged sectional side elevational view of the number  4  and  5  bearing positions of a prior art configuration of the gear casing in FIG. 1; 
     FIG. 3 is an enlarged sectional side elevational view of a portion of the number  4  and  5  bearing positions of the gear casing in FIG. 1 having the oil flow path of the present invention; 
     FIG. 4 is an alternate embodiment of the oil flow path shown in FIG. 3; 
     FIG. 5 is a third embodiment of the oil flow path shown in FIG. 3; 
     FIG. 6 is a fourth embodiment of the oil flow path shown in FIG. 3; and 
     FIG. 7 is a fifth embodiment of the oil flow path shown in FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in which like reference numerals are used to refer to the same or similar elements throughout the several views, FIG. 3 shows bearing positions four and five  20 ,  30  respectively, having an improved oil flow path to prevent leaks through the O-rings  24 ,  34 . Each bearing position  20 ,  30  is provided with a bearing cartridge  29 ,  39  designed to improve the oil flow path in the bearing casing  10  by avoiding the O-rings  24 ,  34 . 
     Bearing cartridges  29 ,  39  are provided with passages  122 ,  132  connecting the bottom edges of the bearing cartridges with the bearing top chambers  22 ,  32 , respectively. Swivel connectors  120 ,  130  are mounted to the bottom edges of the bearing cartridges  29 ,  39  at the ends of the passages  122 ,  132 . Swivel connectors  120 ,  130  are used to attach oil supply hoses and/or pipes, such as hoses  125 ,  135  shown in FIG. 3, to the passages  122 ,  132 . Hoses  125 ,  135  may be connected to a manifold  200  (not shown in FIG.  3 ). 
     At time of assembly and disassembly, the sub-assemblies consisting of bearing cartridges  29 ,  30 , swivel connectors  120 ,  130  and hoses  125 ,  135 , must be able to pass through bores in casing  10 . To accomplish this feature, the swivel connectors  120 ,  130  and hoses  125 ,  135  are turned inward to create an envelope equal to or smaller than the outside diameter of bearing cartridge  29 ,  39 . Once each sub-assembly passes through the bores in casing  10 , each swivel connector  120 ,  130 , with attached hoses  125 ,  135  are turned outward to facilitate assembly. 
     The swivel connectors  120 ,  130  provided at the bottom ends of bearing cartridges  29 ,  39  permit oil to pass from the manifold  200  through the respective hoses  125 ,  135 , swivel connectors  120 ,  130  and passages  122 ,  132  into each of the top chambers  22 ,  32 , where the oil is used to lubricate the bearing. At no time does the oil being conveyed on this path contact the outside of the bearing cartridges  29 ,  39  or O-rings. Thus, pressure against the O-rings  24 ,  34  is reduced, thereby reducing wear on the O-rings  24 ,  34  and the lack of pressure prevents leaks occurring through the O-ring seals. 
     Several alternate embodiments for the swivel connectors  120 ,  130  and hoses  125 ,  135  are envisioned. FIGS. 4-7 display four alternate connections which could be used to provide a path from the manifold  200  to the passages  122 ,  132 . In order to simplify the description of each embodiment, only the bottom portion of one bearing cartridge  29  is shown in each figure, although the same or a different embodiment may easily be used on the second bearing cartridge  39 . The remainder of the bearing cartridge  39  which is not shown in these four figures is the same as that of FIG. 3 in each case, except as noted. 
     FIG. 4 displays an embodiment of the connector in which a swivel connector  120  has a pipe connector  129  which is used to attach a flexible supply hose  126  connected to the manifold  200 . 
     FIG. 5 has a bearing cartridge  50  with a supporting ledge  55  for supporting a pipe  129  connecting the passage  122  to the manifold  200 . The supporting ledge  55  extends from the inner side of the bearing cartridge  50  underneath the passage  122 , thereby creating a substantially right-angle bend at the bottom end of the bearing cartridge  50 . A flexible hose  190  may be attached to the pipe  129  at any convenient point to place the pipe  129  in communication with the manifold  200 . 
     In the embodiment of FIG. 6, the swivel connector  120  is replaced by a stationary block  140  which may be bolted to the bearing cartridge  29 . A hose connector  150  attached to the block  140  provides a fitting for a flexible hose  126  connected to the manifold  200 . 
     Finally, in FIG. 7, the stationary block  140  may be used to support a pipe  128  connected between the passage  122  and the manifold  200 . A flexible hose  190  may connect the pipe  128  to the manifold  200 . 
     It is envisioned that the swivel connectors  120 ,  130  may be mounted to the ends of the passages  122 ,  132  in any known manner which permits oil to flow through the connectors  120 ,  130  into the passages  122 ,  132 . Each swivel connector  120 ,  130  or block  140  must be sized appropriately for the limited space available adjacent the bearing cartridges  29 ,  39  inside the gear casing  10  as well. 
     The improved bearing positions  20 ,  30  permit the oil path to be kept entirely within the casing  10 , thus reducing the likelihood of oil leaks or external forces causing failures of the oil supply lines. Further, the apparatus required to implement this oil path is relatively simple, with fewer parts, easier assembly and, therefore, less likelihood of incorrect implementation in existing bearing positions. 
     While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.