Motorcycle circuit breaker ignition advance

#This is an automatic advance unit as applied to the circuit breaker ignition of motorcycles, notably such as are utilized in the Harley-Davidson ignition system dated from the year 1970 to the present. The objective herein is to permit motorcycle users to obtain many additional miles of riding pleasure out of their motorcycles, without advance unit replacement, in accordance with the preferred system of the invention.

#In the ignition circuit breaker advance unit of the invention, flyweight roll-pins are not set in the flyweights, per se but they are mounted in the advance unit backing plate, ensuring that the flyweights are moveable in perfect horizontal position, whereas in the prior art device, the flyweights on the advance unit set the roll-pins in the flyweights, per se, causing severe wear when centrifugal spinning of the advance unit is occurring. Thus in the instance of the prior art, the generated centrifugal force causes the flyweights to wear catty-cornered, which will allow them to rub against the timing plate, wearing them out in a shorter period of time than in the present ignition control system. The bottom of the flyweights of this invention ride in contiguous contact with the timing plate, a lubricant providing the only intermediate for surface to surface contact.

#The centrifugally activated flyweights of this invention are mounted in such a manner that they may perform for a life of well over 5,000 miles without replacement. There is, to accomplish the present objective, a breaker cam with substantially shorter flyweight engaging slots and thus less tolerance between elements, reducing wear as opposed to existing competitive advance units. Advance units of prior art devices must be replaced at approximately every 1,000 miles because of excess flyweight wear occasioned by the design of the original issue advance unit. Other advantages of the invention include maintaining the compression springs holding the flyweights together as a unit, to function with the baseplate. Since the flyweights do not wear nearly as fast as in prior art assemblage, the invention herein yields more dependable and lengthy service. In the present system, shafts from the flyweights engage holes on the advance assembly baseplate per se, ant the breaker cam herein is of a unique dimension, as is the advance assembly shift. Likewise, the cut-out slot in the breaker cam herein is shorter, presenting less operative tolerance, therefore sustaining less wear than occurs in existing units.

#FIG. 1 is an exploded view in perspective, illustrating complete details of an automatic advance unit of a Prior Art circuit breaker system.

#FIG. 1A is a partial view in perspective of the Prior Art advance unit of FIG. 1, wherein specific details of the components, which are the subject of invention are depicted.

#FIG. 2 is an exploded view of essential details of invention, depicting relative to FIG. 1A, the new counterpart automatic advance and illustrating the improved relationship between the correlative parts for a circuit breaker system of the same motorcycle, the advance herein being adapted to the same associated parts of the FIGS. 1 and 1A assemblages.

#The prior art illustrated in FIG. 1 comprises in exploded detail, circuit breaker cover screws 1, securing circuit breaker cover 2 against the circuit breaker cover gasket 3, there being a wire terminal and wier 4 not shown; the circuit breaker cam bolt 5, not shown and the breaker plate screws 6, engaging breaker plate screw lock washers 7. The condenser is illustrated at 15. The breaker plate assembly 8 includes breaker contact screw 11, not shown, breaker contact assembly 12, breaker plate 13, condenser screw, lock washer 14 and condenser 15, each not shown. The advance assembly 10 of the prior art device includes breaker cam 9, also it comprises dual flyweight springs 16, dual flyweights 17 and flyweight roll pins 18. Roll pins 18 are each set into the flyweights 17, per se. A cam stop roll pin 19 is set in the baseplate 23, together with a register roll pin 20 each not shown in this FIG. 1. There is also illustrated cam shaft seal 21, gear case cover 22 and gear cam 24. Measurements of the parts, especially of the breaker cam, are critical. At the base of the breaker cam 9, respective trigger rotor cutouts are dimensionally 3/16" wide and 7/16" long.

#The primed numbers appearing herein define new parts of the invention, FIGS. 2, 4, 6 and 8, that are related to like numbered parts of the prior art assembly, FIGS. 1, 1A, 3, 5 and 7. Contrasting the aforesaid automatic advance circuit breaker unit with the prior art: is the invention defined in FIGS. 2, 4, 6 and 8, as follows. Breaker plate assembly 8' and associated elements 4'-7' and 11'-15', as well as elements 1'-6' are not shown as they are the same as the conventional prior art elements of FIG. 1.

#The essential elements of the present invention comprise advance assembly 10'. A side-by-side contrast of elements is reflected in FIGS. 1A and 2. They include: baseplate 23' in addition to the conventional elements, aforesaid. The breaker cam 9' is limitedly rotateable relative to the baseplate of advance assembly 10', see spot pin 9", FIGS. 2 and 8. Lans and grooves are machined into the interior wall of cam 9', to facilitate its lubrication during operation of the advance unit of the invention. The advance assembly further consists of expansion-compression springs 16', engageable with opposed ends of respective flyweights 17', the flyweights being centrifugally slideable, relative to baseplate 23'. The baseplate per se mounts the flyweight roll pins 18' which are press fitted into the baseplate and disposed in-line with the upstanding baseplate journal 23", upon which the breaker cam 9' is rotateably mounted. The dimensions of the breaker cam 9' are critical. The circumference at the top thereof is 1/2" and the elongate distance between the top and the first shelf is 21/32"; whereas the top shelf has a circumference of 19/32" which is the same as the elongate distance between the shelf and the bottom of the breaker cam 9', itself. Advance unit intime pin 20' is 3/32" in diameter. As suggested, the interior barrel of the breaker cam 9' is scored to form lans and grooves for retention of lubricant. See phantom lines of FIG. 6.