Lubrication – Systems – Gearing
Reexamination Certificate
1999-02-23
2001-02-27
Fenstermacher, David (Department: 3682)
Lubrication
Systems
Gearing
C074S425000, C074S427000, C384S472000
Reexamination Certificate
active
06193014
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a pre-spinning and lubricating system for worm drive power transmissions and a new bearing assembly and components thereof.
2. Description of the Related Art
Conventional worm gear sets employ a worm screw and fixed tooth or roller tooth gear wheel. Although such worm gear sets are successful drive mechanisms at low speeds, their efficiencies are limited due to the rubbing or skidding contact between the teeth of the gear wheel and the screw thread of the worm screw.
Although the roller pin design is significantly more efficient than the solid tooth arrangement, further improvement in efficiency can be realized by a spray mist, pre-spin, lubricating system in place of the conventional method of an oil reservoir dip system. Submerging the roller pins in a lubricant at the bottom of the gear wheel cycle stops any spinning rotation of the roller pins that was gained from exiting the screw path causing a skidding action when re-entering the screw thread path. The Brackett U.S. Pat. No. 3,820,423 shows a solid roller pin design.
The Brackett patents employ separate bearing races supporting the front and the back bearings of the roller pins. The design has a limited capacity to withstand torque loads between the roller pins and the screw thread contact.
SUMMARY OF INVENTION
The problems and disadvantages of the prior art described above are overcome in accordance with the present invention by providing a bearing assembly that will carry significant heavier loads of conventional single bearing races and a pre-spin lubricating system that eliminates the skidding action of present roller pin designs and improve the efficiencies of conventional designs. The new bearing design includes a roller pin with a protruding cone projection to mate with the screw thread surface of the worm screw. The pin body is cored out leaving a wall thickness sufficient to withstand the prescribed loads and to reduce weight for pre-spinning. To regain the spinning action of the roller pin, to eliminate the skidding action on entry with the screw thread, a spiral shaped object is fitted and secured into the cored out center of the roller pin. The spiral shaped object acts as a turbine when a spray of mist of compressed air and lubricant is jetted through the opening in the roller pin. In the case of multiple roller pins on each side of the roller wheel the system is devised with a separate air flow hole for each pin that connects to the cored out center of the roller pins. A stationary valve plate is secured to the output shaft mounting plate with an air fitting hole drilled through to a rotary groove that lines up with at least three of the air flow holes of the roller pins. The rotary groove is positioned to service a jet of compressed air and lubricant to a span of at least two or three air holes of the roller pins as the worm wheel is rotating to regain the spinning action of the roller pins just before they enter the screw thread path.
The second important unit of the roller pin design would be the solid hardened outer bearing race that has a length equal to the length of the roller pin minus the length of the cone shaped protruding projection that mates with the screw thread surface. The outer bearing has grooves on the inside diameter that mate perfectly with the grooves of the roller pin to accept a compliment of needle bearings in the front and ball bearings in the rear. The rear groove are deeper facing the rear of the assembly to effect a thrust condition when torque is applied to the roller pin. This eliminates the necessity of a conventional thrust bearing to absorb the load when the torque is applied to the roller wheel.
In order to hold the roller pin and bearing race assembly in place in the roller wheel a threaded locking pin is screwed into a threaded hole in the roller wheel at a 90 degree angle from the center of the outer bearing race. A mating hole is drilled into the outer bearing race slightly larger than the diameter of the locking pin just off the center of the threaded hole so that locking pin bears up against the rear of the hole to hold the bearing assembly snugly against the spring washer and the hardened backup plate. The slightly larger diameter leaves a space to the front of the hole that allows the bearing assembly to slide forward and back and still remain locked in the pocket. The locking pin also prevents the outer bearing race from rotating while the roller pin is free to spin.
The new bearing design utilizes a single solid hardened outer ring with a compliment of preloaded ball bearings or needle bearings circulating in an inner groove at both ends of the solid hardened ring. The roller pin is supported by the same compliment of bearings mating with outer groove on both ends of the pin body. The roller pin serves as the inner race of a standard bearing incasement that creates a smaller diameter of the outer ring race. The solid hardened outer ring race creates a rigidity for the bearing assembly and significantly improves the load carrying capacity of a standard single bearing race utilized in the Brackett design. A further feature of the solid ring concept is that it unites the roller pin and outer race into a one piece assembly that enables the design to utilize a slide fit in the receptacle pocket bored in the worm wheel. A locking screw pin is threaded into the worm wheel ring at 90 degrees from the outer ring. A receiving hole is drilled into the outer ring that is slightly larger than the diameter of the locking pin. This allows the total assembly to slide a controlled distance against a spring washer of calculated pressure in the bottom of the receiving pocket and still remain trapped in the pocket. The locking screw pin enables the outer race to remain circularly motionless while the roller pin is free to spin.
REFERENCES:
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patent: 1273533 (1918-07-01), Pfahler
patent: 1317232 (1919-09-01), Spillman
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patent: 5341901 (1994-08-01), Mueller et al.
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patent: 5592852 (1997-01-01), Parsons
patent: 5901611 (1999-05-01), Brackett
patent: 1239038 (1988-07-01), None
patent: 15654 (1906-07-01), None
patent: 237252 (1926-09-01), None
patent: 358676 (1931-10-01), None
patent: 1538612 (1979-01-01), None
patent: 670758 (1979-06-01), None
Chupa & Alberti P.C.
Fenstermacher David
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