Motor vehicles – Special wheel base – Rider propulsion with additional source of power – e.g.,...
Reexamination Certificate
2000-10-10
2001-09-18
DePumpo, Daniel G. (Department: 3611)
Motor vehicles
Special wheel base
Rider propulsion with additional source of power, e.g.,...
C180S011000, C180S015000, C180S220000
Reexamination Certificate
active
06290014
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to power assist devices for human powered vehicles, such as bicycles; more particularly it concerns a unique power assist package easily connectible to a bicycle and operable to provide power-assist, when needed or wanted.
There have been many design approaches for coupling a battery-powered power assist device to a bicycle, but so far to my knowledge none has provided, in a convenient, economical way, a complete system add-on device that one can install quickly onto bicycles having various types of tires, brakes, gears, etc. To avoid the complexity of needing to couple somehow to the bicycle drive system (tires, wheels, sprockets, chain, cranks; components with geometry that vary from bicycle to bicycle) the power assist needs to power its own wheel or wheels. Various sidecars towed units have been developed to provide self-contained, add-on drive of an integrated wheel or wheels, but none to my knowledge have been highly successful in the modern marketplace.
The geometry challenge is 1) to have the desired force pressing the wheel to the ground at all times, 2) the device never tangling with the rider's body, legs, or feet, 3) the device not inhibiting parking in a small space or backing up, 4) the device not preventing the rear bicycle rack from carrying packages, basket, or even a passenger, 5) the device not having a significant affect on the vehicle's dynamics, 6) the device combining all the batteries, motor, and drive wheel in a package that can be rolled or carried for recharging or storing; and the device avoiding scrubbing. For a practical battery-powered assist, the batteries, motor, and drive wheel should be part of a single unit.
SUMMARY OF THE INVENTION
It is a major object of the invention to provide an easily operable and reliable power assist package readily connectible to a bicycle or in combination with a bicycle, and overcoming problems and deficiencies as referred to above.
Basically, the package includes:
a) a carrier;
b) a ground engaging drive wheel supported by the carrier, and an electric battery operated drive supported by the carrier to rotate the drive wheel;
c) and connecting arm structure associated with the carrier and projecting for connection to the bicycle frame to position the carrier for up and down pivoted movement in close association with and generally parallel to the bicycle rear wheel, with the drive wheel lowermost extent spaced less than six inches to the rear of the lowermost extent of the bicycle rear wheel, so that neither the drive wheel or the carrier will interfere with operation of the bicycle.
It is another object to provide a package that is positioned “tightly” adjacent the left side of the rear bicycle wheel, with an arm connecting it to a pivot on the bicycle frame in front of the rear wheel axle. The drive wheel may typically contact the ground at a point between about
350
and
550
down from and rearwardly of the pivot, so that drive wheel thrust force is accompanied by a nearly equivalent down force that adds to the unit's weight to keep the drive wheel pressed to the ground and not slipping when powered. The body of the system moves around this pivot point to keep the drive wheel touching the ground, whether the bicycle is banked left or right, or if the road slants sideways.
A further object is to provide a device package having a portion that is movable up and down, but is constrained against any lateral or twisting movement relative to the bicycle. In a preferred embodiment, such constraint is provided by fingers or tabs that slide in slots, for example one at the upper part of the unit, and one at the lower portion of the unit.
Yet another object is to provide for contact of the drive wheel with the ground less than about 6 inches behind the ground contact point of the rear wheel. (If the drive wheel is further back, it tends to scrub as the bicycle turns sharply; and if the drive wheel has a large diameter it projects so far forward as to interfere with the rider's left heel during pedaling.) Solutions to these two problems of scrubbing (by limiting the drive wheel axis position to be not far behind the bicycle rear wheel axis), and rider heel hitting or striking (by limiting the front of the drive diameter wheel to be positioned only slightly in front of the main wheel axis) require use of a relatively small drive wheel. A large wheel can only be used if its axis is so far back that, to avoid scrubbing, it casters when the bicycle goes around a corner. While provision for castering solves the scrubbing problem, it introduces others, beyond just weight cost and complexity: a castering drive wheel that must operate over a wide speed range tends to wobble unless damped; the drive wheel jackknifes when the bike is pushed backwards; and the drive wheel must be moved further out laterally from the bicycle rear wheel to avoid striking it when the bike turns to the right. Such greater lateral distance means the drive wheel must move further up and down relative to the bike as the bicycle banks—complicating the pivoting limits and lateral constraints. Also, when the bike travels over and down a curb, the drive wheel is abruptly driven upward relative to the bike as the bike wheel descends.
A further object is to provide a drive package meeting the following requirements, for use with a standard size bicycle:
1) The unit's weight rests generally on the drive wheel;
2) The motion of the drive wheel/motor/battery assembly or package about the pivot at the front of a connecting arm is constrained laterally near the top and bottom of the unit carrier so that movement of the package is always in a plane parallel to the plane of the bike rear wheel;
3) The drive wheel contacts the ground less than 5 inches to the left of, and less than 6 inches (preferably less than about 4 ½ inches) behind the ground contact point of the main bicycle wheel, i.e. rear wheel; and
4) The front of the drive wheel is less than about 1 inch ahead of the bicycle rear axle.
These latter three requirements have associated related specific lengths or dimensions of the bicycle. These are lengths appropriate for an adult bicycle with the rear wheel being of standard dimension, about 26-27 inch diameter. The fore and aft geometric requirements relate more to the distance between the front and rear wheel axes of the bicycle (typically around 42 inches) than they do to the rear wheel diameter. For 16 or 20 inch diameter bicycle wheels, the avoidance of scrubbing of the drive and like wheels during turns and avoidance of heel hitting is comparable to the situation for a 26 inch wheel diameter bicycle, with the same bicycle wheel base. The power assist may alternatively be attached to other pedaled vehicles, such as tricycles, and the term “bicycle” is intended to refer to such.
An additional object is to provide, for a standard bicycle a combination wherein:
1) the drive wheel axis is less than about 10.5% of the bicycle wheel base behind the bike rear wheel axis; and
2) the drive wheel is spaced to the left of the bicycle rear wheel by an amount that leaves less than 19% of the bicycle rear wheel diameter spacing between the adjacent edges of the tires of the drive wheel and the bicycle rear wheel.
These features are applicable to a battery-powered electric assist unit that incorporates battery, motor, and wheel in one assembly. That assembly is preferably pivoted to 1) have a pivot position such that in normal operation the drive wheel ground contact point is between 35°-55° down from a horizontal line rearward from the pivot, and 2) permit vertical movement of the package in an upright plane parallel to the upright plane of the bike rear wheel, in the direction of travel. The assembly is also constrained from lateral or roll movements relative to the plane of the rear bicycle wheel. This constraint can be accomplished in various ways. One is the fingers/slots mechanism described above and herein. Another is to employ a bearing on or in application with the abov
DePumpo Daniel G.
Haeflier William W.
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