Bellows-type bearing seal and method of use
FIELD OF THE INVENTION 
     This invention relates to a seal structure of rubber or synthetic rubber composition which can be used in a variety of applications, in machinery such as agricultural equipment, for preventing dirt from penetrating between moving parts of the machinery and preventing escape of grease therefrom. The invention is particularly useful, for example, for protecting bearings of rotary disc-type equipment such as furrow forming discs or marker discs. 
     STATEMENT OF PRIOR ART 
     Applicant is aware of the following U.S. patents, the relevance of which is that they relate to seal structures and the like. None of the patents, however, discloses apparatus having the features of the present invention. 
     U.S. Pat. No. 2,270,519: H. P. Fisher; 1-20-42. 
     U.S. Pat. No. 2,999,699: W. M. Lafferty; 9-12-61. 
     U.S. Pat. No. 3,192,690: D. D. Taylor; 7-6-65. 
     U.S. Pat. No. 3,428,340: H. L. Pelton; 2-18-69. 
     U.S. Pat. No. 3,455,562: W. A. Burtis; 7-15-69. 
     U.S. Pat. No. 3,857,572: Taylor et al.; 12-31-74. 
     U.S. Pat. No. 4,002,818: Kunze; 1-11-77. 
     U.S. Pat. No. 4,067,585: Rode; 1-10-78. 
     U.S. Pat. No. 4,214,759: Douty et al.; 7-29-80. 
     SUMMARY OF THE INVENTION 
     A rubber or rubber-like grease and dirt seal structure in accordance with the invention comprises a generally cylindrical element of bellows or accordian-type construction having a plurality of interconnected annular pockets defined by radially extending interconnecting walls, the structure being resiliently extensible and compressible in an axial direction. The diameter, size, number of annular pockets, and hardness of the rubber affecting the axial resilience of the seal may vary dependent on the application. 
     Seals in accordance with the invention are particularly useful, for example, as grease-retaining and dirt-excluding seals for rotary disc-type agricultural machines in which a disc is rotatably mounted by means of a ball or roller bearing on a spindle, and the seal is compressed between a shoulder on the spindle and a part of the rotary disc, to exclude dirt from the bearing while preventing escape of grease therefrom. 
     These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a side elevational view of a disc assembly of a double-disc furrow opener on a grain drill. 
     FIG. 2 is an enlarged sectional view on line 2--2 of FIG. 1 showing the use of a pair of rubber seals in accordance with the invention. 
     FIG. 3 is a sectional view on line 3--3 of FIG. 2. 
     FIG. 4 is a perspective view of one of the seals. 
     FIG. 5 is a front elevational view of the disc assembly. 
     FIG. 6 is a perspective view of a marker disc assembly having a seal in accordance with the invention. 
     FIG. 7 is an enlarged sectional view on line 7--7 of FIG. 6. 
     FIG. 8 is a perspective view of an alternative form of seal in accordance with the invention. 
     FIG. 9 is a part sectional view of a seal in accordance with the invention opened out axially to show its construction more clearly. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring initially to FIGS. 1 to 5, there is illustrated a disc assembly 10 for a common type of double-disc furrow opener on a grain drill. Thus, the assembly may comprise a cast hanger 12 providing opposed hubs 14, 16 into which are threaded pair of stub shafts 18, 20 rotatably mounting respective oppositely inclined furrowing discs 22, 24. The discs may be screwed or bolted to cup-like end caps 26, 28 journaled on the respective stub shafts by means of roller bearings 30, 32. The end caps may be retained by bolts 35, 37, for example. The hanger is provided with a grease nipple 34 and conduit 36 for supply of grease to the bearings. FIG. 1 also shows grain and fertilizer or like supply tubes 39, 41 for delivering such materials between the discs in known manner. 
     The above-described assembly is typical of those commonly used in known grain grills, and commonly such assemblies are provided with disc-type seals (not shown) positioned around the respective hubs 14, 16 and engaging against the inner surfaces of discs 22, 24. It is found, however, that due to the rather flimsy construction of such seals, dirt tends to roll under the seals thereby requiring frequent greasing of the machine and possibly resulting in premature wear of moving parts of the machine. Therefore, in accordance with the invention, the standard form of disc seals are replaced by novel seal members 38, the construction of which is shown in detail in FIGS. 4 and 9. 
     Each seal member 38 comprises a generally accordian-like cylindrical body of rubber or like resilient material molded to provide an axial series of interconnected pocket-like rings defined by adjacent radially extending walls 40. FIG. 9 shows the seal member opened up axially in order to show its construction more clearly. In use, however, as shown in FIG. 2, seals 38 are positioned with a degree of axial compression between the respective hubs 14, 16 and the inner surfaces of discs 22, 24 when the discs are bolted onto the respective stub shafts. In practice, it is found that the pressure applied to the seal members provides a sealing effect which is superior to that of the prior art seals in exclusion of dirt from the bearings and retention of grease, thereby increasing time between grease applications and prolonging the life of the apparatus. 
     FIGS. 6 and 7 show a like seal member 38a as used in a known form of row marker disc assembly 40 for providing dirt exclusion and grease retention in like manner to the previous embodiment for the disc bearing 42. In the marker disc assembly, disc 44 is attached to a cap 46 journally mounted by bearing 42 on a stub shaft 46 at the end of an arm 48. The arm terminates in a hub-like member 50 carrying the stub shaft, and seal 38a is compressed between member 50 and cap 46 in like manner to the previous embodiment where it is equally effective for dirt exclusion and grease retention. 
     FIG. 8 shows a seal member 38b which is similar to members 38 and 38a previously described, except that it has a lesser number of interconnected rings, showing that seals in accordance with the invention can be made in different lengths to suit different applications. 
     The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.