Interlocking safety handle for a friction drive apparatus

An apparatus for frictionally engaging and driving a rotatable wheel of a lightweight vehicle is disclosed. The apparatus has a pivotable handle which is movable between a first and a second position. In the first position the handle blocks access to a fuel tank while permitting operation of the engine and engagement of a driven friction surface with the rotatable wheel. In the second position of the handle, the engine is inoperable, the fuel tank may be refilled, and the friction surface cannot engage the rotatable wheel. Preferably, the handle provides means for pivoting the engine to and from a position in which the friction surface engages the rotatable wheel and for operationally engaging an electrical switch to control operation of the engine.

The invention relates generally to apparatus for driving light duty or 
light weight vehicles and in particular to apparatus for frictionally 
driving a lightweight vehicle. 
BACKGROUND OF THE INVENTION 
Friction drives have been known in many different applications for many 
years. In particular, it has often been proposed to provide a friction 
drive, using an internal combustion engine as the power source, for 
driving the front or rear wheel of a lightweight vehicle such as a 
bicycle. While these devices are well known, they have not always been 
constructed with both convenience and safety of operation in mind. 
The principle objects of this invention are therefore to provide an 
apparatus for frictionally driving a light weight vehicle which is safe, 
reliable, and low cost, which is convenient to operate, which has a 
convenient means for engaging the drive with and releasing the drive from 
contact with the vehicle wheel, and which provides an interlock safety 
system to insure the safety of the vehicle and its operator, for example, 
while the engine fuel tank is being refilled. 
SUMMARY OF THE INVENTION 
The invention relates to an apparatus for frictionally engaging a rotatable 
wheel of a lightweight vehicle. The apparatus to which the invention 
relates comprises a drive motor having a rotating output shaft, a fuel 
tank for providing fuel to the motor, the tank having a closeable fuel 
receiving opening, and a driven wheel mounted for driven rotation by the 
output shaft of the motor, the driven wheel having a circular friction 
surface for frictionally engaging the rotatable wheel. The apparatus 
further comprises means for releasable engaging the driven wheel friction 
surface with the rotatable wheel. The invention features a pivotable 
handle coupled to the apparatus for selectively operating the motor. The 
handle is pivotable from a first position to a second position. In the 
first position, a protruding portion of the handle substantially blocks 
access to the fuel tank opening thereby preventing the tank from being 
filled. In the second position, the fuel tank opening can be accessed for 
supplying fuel to the tank. In addition, the motor is operable when the 
handle is in the first position; however, the motor is inoperable when the 
handle is in the second position. 
In a first particular aspect of the invention, there is further featured an 
electrical switch in operable engagement with the handle, the handle in 
the first position setting the switch into a first state and the handle in 
the second position setting the switch into a second state, the switch 
being electrically connected to the motor and the motor being inoperable 
when the switch is in the second state. Preferably, the switch is in the 
second state whenever the handle is not in the first position. 
In a second aspect of the invention, the releasable engaging means 
comprises means for pivotally mounting the driven wheel for engaging the 
rotatable wheel. In this aspect, the handle is connected to a top side of 
the apparatus. In addition, means are provided for mechanically coupling 
the handle to the wheel pivoting means for pivoting the driven wheel from 
a driving condition when the handle is in the first position to a 
disengaged condition when the handle is in the second position.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1, the invention is applicable to many different kinds of 
lightweight vehicles, and in the illustrated embodiment, a bicycle 10 of a 
standard design has secured, at a rear portion thereof, a friction driving 
apparatus 12 for providing drive power tending to urge the bicycle 
forward. The friction driving apparatus 12 comprises a drive motor 14, 
typically an air cooled, single cylinder internal combustion engine, a 
driven wheel 16 having a driving friction surface 18 and mounted for 
rotation by a rotating output shaft 20 of the engine. The friction driving 
apparatus 12 further comprises a fuel tank 22 connected for providing fuel 
to the internal combustion engine, the fuel tank having a closeable fuel 
receiving opening 24 securely closed by a fuel tank cap 26 which forms an 
air tight seal with the tank. 
The driven wheel friction surface 18 engages and drives, in the illustrated 
embodiment, a rear rotatable bicycle wheel 30 at least to propel the 
vehicle in a forward direction. The apparatus 12 further comprises means 
for releasably engaging the driven wheel friction surface with the rear 
bicycle wheel. In the illustrated embodiment of the invention, the 
releasable engaging means comprises a structure which pivots the motor and 
its connected driven components, including the output shaft, the driven 
wheel, and if included, a clutch, etc., about a pivot axis 32 from an 
engaged position in which friction surface 18 is in driving contact with 
the bicycle wheel tire to a disengaged position wherein surface 18 is out 
of contact with the bicycle tire. 
Referring in particular to FIG. 2, the apparatus 12 further comprises 
pivotable handle 40 having a protruding portion 42. Pivotable handle 40 is 
mounted for pivotal movement about a pivot axis 44 from a first position 
in which protruding portion 42 substantially blocks access to the fuel 
tank receiving opening 24 and fuel tank cap 26 to a second position 
(indicated by the position of handle 40 shown in dotted lines in FIG. 2) 
wherein the fuel tank receiving opening can be accessed. In the first 
handle position, therefore, access to the fuel tank opening is made 
sufficiently difficult to prevent the tank from being filled with fuel; 
and when the handle 40 is pivoted to the second position, access to the 
fuel tank opening is obtained and the engine may be refueled. 
The pivotable handle is also connected, in the preferred embodiment, to 
operatively engage an electrical switch 46. In the illustrated embodiment, 
the electrical switch comprises an electrically conductive extension 
element 48, connected between the drive motor assembly and the handle 40, 
and an electrically conductive spring element 50 connected to the ignition 
system of drive motor through a wire 52. The switch operates as follows to 
provide a safety interlock system. Wire 52 is connected to the primary of 
the ignition coil (not shown) of the engine. When handle 40 is in the 
first position wherein protruding portion 42 substantially blocks access 
to fuel receiving opening 24, there is no connection between spring 
element 50 and extension element 48; and the switch 46 is in a first state 
in which the engine can be operated. However, when the handle is pivoted 
to the second position (indicated by the dotted lines in FIG. 2), 
extension element 48 is moved toward and engages spring element 50 to 
electrically ground wire 52. The switch is thus set to a second state in 
which the engine is inoperable because the primary of the ignition coil is 
grounded through grounding of wire 52. Preferably, the switch attains its 
second state whenever the handle is in a position wherein the fuel tank 
can be refueled. It should be obvious that many other configurations of 
switches and switch components can be used in combination with pivoting 
handle 40 to provide the just described interlock feature. In addition, 
the engine may be connected so that it is electrically inoperable in many 
other ways which will be obvious to one skilled in the art. 
In the illustrated embodiment, extension element 48 serves a duel purpose. 
The illustrated element 48 is connected to a structurally fixed portion of 
the driven wheel mounting assembly and has a pivotal connection at pivot 
axis 58 to the handle 40. As a result, when the handle pivots from its 
first to its second position, extension element 48 is urged upward due to 
the offset of its connection at pivot axis 58 with respect to handle 40 
pivot axis 44. Thus, the entire motor drive system is supportingly pivoted 
around pivot axis 32 and, as extension element 48 travels in the upward 
direction, the motor assembly pivots upward (clockwise in FIG. 2) around 
the supporting pivot connection axis 32. As a result, when the handle is 
pivoted to the second position wherein the fuel tank can be refilled, the 
driven wheel friction surface 18 is raised away from the rotatable wheel, 
thereby disengaging it from a driving contact with the vehicle wheel. 
ADVANTAGES OF THE INVENTION 
There is thus described a novel interlocking safety handle for a friction 
drive apparatus which advantageously maintains the apparatus drive motor 
in an inoperative state, an inoperative position, or both, whenever the 
fuel tank is being filled. In this aspect, apparatus according to the 
invention automatically prevents the possibly dangerous condition in which 
an internal combustion engine is refueled while the engine is running. 
Thus, the handle can operationally engage an electrical switch means, 
which is adjustable, so that the ignition system of the drive motor is 
grounded, short circuited, or otherwise rendered inoperable, at a selected 
position of the handle. 
The handle is also conveniently located on top of the friction drive 
apparatus so that when the vehicle is a bicycle, it may be reached by the 
driver of the bicycle from a sitting position to pivot the motor drive 
assembly about its supporting pivot axis whereby the driven wheel friction 
surface is disengaged from the vehicle wheel. This convenience enables the 
bicycle operator to quickly disengage the drive wheel under unexpected or 
otherwise potentially dangerous conditions. Consequently, the friction 
drive apparatus according to the invention is both conveniently mounted 
and provides a safe and reliable drive means. 
Other embodiments of the invention, including additions, subtractions, 
deletions, and modifications of the preferred disclosed embodiment, will 
be obvious to those skilled in the art and are within the scope of the 
following claims.