Patent Publication Number: US-4921362-A

Title: Bearing assembly with seal

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 012,442, entitled Bearing Assembly, filed on Feb. 9, 1987 and now U.S. Pat. No. 4780001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to bearing assemblies and, more particularly, to a dual bearing assembly with means for automatically compensating for bearing wear and having an improved seal. 
     2. Description of the Prior Art 
     One previously known advertising display such as disclosed in U.S. Pat. No. 3,387,394 comprises a plurality of triangular louvers which are rotatably mounted in a frame and rotatably driven in unison with each other. Thus, different advertising messages are displayed as the louvers are rotatably driven to different rotational positions. These displays are driven by electric motors and a bearing assembly is typically interposed between the electric motor and each louver. The opposite end of each louver is connected by a shaft to the frame. 
     A primary disadvantage of these previously known display assemblies is that the components of the display assembly, and particularly the bearing assembly, are subjected to excessive wear due to their prolonged and continuous operation and as such, have previously required frequent maintenance and part replacement. Furthermore, when the bearing assemblies for these previously known display assemblies begin to wear, shaft wobble results which not only hastens the deterioration of the bearing assembly but also imposes undesirable loads and stresses on the electric motor. These loads not only damage the electric motor but may also necessitate its replacement. 
     A still further disadvantage of these previously known displays is that the shaft which connects the end of the louver opposite from the bearing assembly is typically fastened to the frame by a nut. After prolonged use, the nut frequently becomes loose which causes the display to malfunction. 
     A still further disadvantage of these previously known displays is that moisture, dirt and other contaminants enter into the bearing assembly. These contaminants cause bearing deterioration and, ultimately, malfunction of the display. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a bearing assembly particularly suited for a display assembly which overcomes all of the above-mentioned disadvantages of the previously known devices. 
     In brief, the bearing assembly of the present invention comprises a tubular housing having an elongated shaft extending coaxially through it. A pair of axially spaced bearings are contained within the housing and rotatably mount a drive shaft to the housing. Preferably, each bearing is a tapered roller bearing. 
     A pair of collars are secured to the shaft at axially spaced positions so that the bearings are contained in between the collars and so that one collar abuts against one bearing. A Belleville washer is sandwiched between the other collar and the other bearing assembly which imposes a compressive force between the bearing assemblies and, simultaneously, a tension force on the shaft. 
     An annular seal is coaxially secured to the shaft so that the seal and shaft rotate together. The seal extends across one end of the bearing housing and has an outer lip on the seal which extends around the outer periphery of the bearing housing. This seal effectively prevents contaminants from entering into the bearing assembly thereby protecting the bearings from deterioration. 
     In operation, the Belleville washer preloads the bearings to automatically compensate for bearing wear as well as manufacturing tolerances. In doing so, the bearing assembly automatically eliminates wobbling of the bearing assembly and is capable of prolonged operation without malfunction. 
     In addition, in the preferred embodiment of the invention, the louver shaft opposite from the bearing assembly is fixedly secured to the frame and has a pointed end which faces the louver. This pointed end is received within a bushing on the louver. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompanying drawing, wherein like reference characters refer to like parts throughout the several views, and in which: 
     FIG. 1 is a fragmentary perspective view illustrating a preferred embodiment of the invention as used with a display assembly; 
     FIG. 2 is a longitudinal sectional view of the preferred embodiment of the bearing assembly of the present invention; 
     FIG. 3 is a view similar to FIG. 2 but showing a modification thereof; and 
     FIG. 4 is a fragmentary sectional view showing a portion of the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
     With reference to FIG. 1, a display assembly 10 is thereshown having a rectangular frame 12 which supports a plurality of triangular louvers 14 between its top 15 and bottom 16. A louver shaft 44 (FIG. 2) mounts each louver 14 to the bottom 16 of the frame 12 while an upper shaft 100 (FIG. 4) mounts each louver 14 to the top 15 of the frame 12. An electric motor 18 (FIG. 2) rotatably drives the shafts 44 and their attached louvers 14 through bearing assemblies 20. 
     With reference now to FIG. 2, one bearing assembly 20 is thereshown in greater detail and comprises a tubular and cylindrical housing 22 open at both its top end 24 and its bottom end 26. A mounting flange 28 is secured to the outer periphery 30 of the housing 22 for mounting the housing 22 to the base 12 (FIG. 1). Any conventional means, such as bolts (not shown), can be used to secure the mounting flange 28 to the bottom 16 of the frame 12. 
     Still referring to FIG. 2, a pair of bearings 34 and 36 are contained within the interior of the housing 22 and are axially spaced from each other. Each bearing 34 and 36 includes an outer race 38, an inner race 40 and a plurality of bearing elements 42 rotatably entrapped therebetween. Preferably, the bearing elements 42 are tapered roller bearings so that the axes of the bearing elements 42 on the bearings 34 and 36 angle toward the center of the housing 22 and intersect each other obliquely. In addition, a pair of axially spaced retainer clips 37 are secured to the interior of the housing 22. These clips 37 abut against the outer races 38 of the bearings 34 and 36 and maintain the bearings 34 and 36 spaced apart from each other. 
     The shaft 44 extends axially through the inner races 40 of the bearings 34 and 36 and thus axially through the housing 22 and terminates in a stub end 150. A first collar 46 is secured by a pin 48 to the shaft 44 so that a lower end 152 of the collar 46 abuts against the inner race 40 of the bearing assembly 34. Similarly, a second collar 50 is secured by a pin 52 to the shaft 44 so that the collars 46 and 50 are axially spaced from each other and so that the bearings 34 and 36 are positioned in between the collars 46 and 50. 
     A resilient member 54, such as a Belleville washer, is sandwiched in between the collar 50 and the inner race 40 of the bearing 36 so that the resilient member 54 is in a state of compression. The spring member 54 thus compressively urges the inner races 40 of the bearings 34 and 36 together and against their retaining clips 37. Simultaneously, the spring member 54 exerts a tension force on the shaft 44 equal in magnitude to the compressive force exerted on the bearings 34 and 36. 
     Still referring to FIG. 2, a bevel gear 60 is detachably secured to one end of the shaft 44 by a collar 62 and set screw 64 which abuts against a notch in a key 63. This bevel gear 60 meshes with a bevel gear 61 from the motor 18 to rotatably drive the shaft 44. 
     Preferably, a grease fitting 66 is mounted to the housing 22 so that its inner end is open to a tubular cylindrical chamber 68 formed between the housing 22, shaft 44 and bearings 34 and 36. The fitting 66 allows grease or other lubricant to be introduced into the chamber 68 in order to lubricate the bearings 34 and 36. A seal 154 also preferably closes the end 24 of the housing 22 in order to minimize the introduction of contaminants into the bearing assembly 20. 
     Still referring to FIG. 2, the thin-walled annular seal 154 has a central opening 155 which is positioned over the stub end 150 of the shaft 44 so that the shaft 44 extends through the opening 155. In doing so, a central portion 156 of the seal 154 abuts against an upper axial end of the collar 46. 
     The seal 154 extends across and covers the open upper end 24 of the housing 22 and includes an outer annular lip 158 which extends around the outer periphery of the housing 22 adjacent its upper end 24. The seal 154 is dimensioned so that the lip 158 is generally tubular and cylindrical in shape and so that the lip 158 resiliently compressibly engages the outside of the housing 22. 
     A drive member 162 is secured to the stub end 150 of the shaft 44 by a screw 164 and brass slug 166. Prior to tightening the screw 164, however, the drive member 162 is compressed against the central portion 156 of the seal 154 so that the seal 154 is tightly sandwiched between the drive member 162 and the collar 46. Consequently, once the screw 164 is tightened, the seal 154 is secured to and rotates in unison with the shaft 44. 
     A seal 170 is sandwiched between the collar 46 and the inner race of the bearing assembly 20. An outer resilient portion of the seal 170 contacts both the inner periphery of the housing 22 as well as the upper end of the outer race of the bearing 20 to protect the bearing assembly 20 from contaminants. Preferably, the seal 170 is like that shown in U.S. Pat. No. 4,043,620. 
     In operation, the resilient member 54 resiliently urges the bearings 34 and 36 together. As the bearing members 42 and/or the bearing races 38 and 40 begin to wear, the resilient member 54 expands to maintain the bearing members 42 in a state of compression between the races 38 and 40 due to the inclined axes of the bearing members 42 with respect to the axis of the shaft 44. Consequently, the resilient member 54 automatically compensates for any bearing wear thereby eliminating shaft wobble. The spring member 54 also compensates for manufacturing tolerances in the attachment between the collars 46 and 50 to the shaft 44. 
     Although in the preferred form of the invention, the bearings are resiliently compressed toward each other while the shaft is in a state of tension, alternatively the bearings can be placed in a state of tension and the shaft in a state of compression to eliminate any play in the bearings. 
     As previously described, the seal 154 rotates in unison with the shaft 44. Thus as the shaft 44 rotates, the outer lip 158 wipes along the outer periphery of the housing 22 and effectively prevents moisture, dirt and other contaminants from entering into the open upper end 24 of the housing 22. A lower resilient seal 172 also prevents the introduction of contaminants into the lower end 26 of the housing 22. 
     With reference now to FIG. 3, a modification of the present invention is thereshown in which a ball bearing assembly 80 replaces the louver roller bearing assembly 36 of the FIG. 2 embodiment. The ball bearing assembly 80 includes an outer race 82, inner race 84 and ball bearing elements 86 between the races 82 and 84. The clip 37 locks the outer race 82 against movement to the housing 22 while the inner race 84 abuts against an enlarged diameter portion 88 on the shaft 44. 
     The FIG. 3 embodiment further differs from the FIG. 2 embodiment in that the collars 50 and 46 are secured to the shaft 44 by the pins 48 and 52 so that the bearing assemblies 34 and 80 are compressed in between the collars 46 and 50. Thus, as the bearing assemblies wear after prolonged use, any play in the bearing is eliminated by the compression exerted on the bearing assemblies by the collars 46 and 50. 
     With reference now to FIG. 4, a still further feature of the display assembly is thereshown in which the shafts 100 rotatably mount the upper ends of the louvers 14 to the top 15 of the frame 12. Each shaft 100 is fixedly secured to the frame by welds 102 or the like so that the shafts are aligned with the axis of the louvers 14. In addition, each shaft 100 includes a pointed end 105 which points toward the bottom 16 of the frame 12. 
     Each louver 14 includes a bushing 104 at its upper end which is adapted to receive the shaft 100 therethrough. The bushing 104 includes a ball 110 having a throughbore 112 adapted to receive the shaft 100 therethrough. The ball 110 is rotatably mounted in a sleeve 114 and can pivot from the position shown in phantom line, which facilitates insertion of the shaft end 105, and to the position shown in solid line. In order to mount the louver to its shaft 100, the pointed end of the shaft 100 is first inserted into the ball 110 in the bushing 104 as shown in phantom line and then moved to the position shown in solid line. 
     From the foregoing, it can be seen that the bearing assembly as well as the shaft assembly of FIG. 4 of the present invention provides an inexpensive bearing assembly particularly suited for advertising displays which are capable of prolonged operation without failure. 
     Having described my invention, however, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims.