Fluid coupling for small engine with direct wheel drive

A fluid coupling directly-drive a wheel from a small engine. The fluid coupling is mounted in cantilevered support or two ended bearing support from a small engine and has a small diameter inner driven shaft and a larger diameter out wheel driving shaft for contacting and directly driving a wheel. The inner driven shaft connects to a pump having a relatively larger outer diameter than either the driven or driving shaft. This pump is mounted on the opposite side of the driven wheel from the engine and preferably includes rotating vanes within one half a toroidal path having an attached eccentrically mounted toroidal plug for causing helical rotation of fluid about the plug. A turbine mates to the pump and includes rotating vanes within the other half of the toroidal path, these vanes being shaped around the toroidal plug of the pump. The toroidal plug and toroidal volumes are eccentrically mounted one with respect to another to cause high velocity flow on the outside diameter of the pump and turbine with low velocity flow in the inside diameter of the pump and turbine. Fluid, typically oil, is confined to the pump and turbine by appropriate seals and causes torque conversion between the pump and turbine. In the preferred embodiment, a fuel tank for the engine is mounted overlying the driven wheel so as to shield the interface of the wheel and driving spindle. At the same time, the exterior of the driven pump is supplied with vanes to generate appropriate air cooling at the fluid coupling.

This invention relates to a fluid coupling or torque converter for a small 
engine which finds use with a direct wheel drive. The fluid coupling of 
this invention can be mounted in a cantilevered support from a small 
engine to directly drive the rear wheel of a small scooter or alternately 
to a beam type support in which the outboard bearing of the fluid coupler 
is supported from a strut, such as a plate reinforcing gas tank mounting. 
BACKGROUND OF THE INVENTION 
In U.S. Pat. No. 4,821,832 entitled MOTOR SCOOTER HAVING A FOLDABLE HANDLE 
AND FRICTION DRIVE of Steven J. Patmont Issued Apr. 18, 1989, there is 
disclosed a hydraulic fluid coupling or torque converter. This fluid 
coupling includes an inner motor driven shaft, an outer wheel driving 
shaft, and a fluid couple between the driven and driving shafts for 
producing in a motor scooter a fluid drive. 
In what follows, an improvement on this fluid clutch is disclosed. 
Fluid couplings are known. Particularly, torque converters have been 
utilized in all kinds of machinery, especially automobiles. With these 
torque converters, it is common to include, a driven shaft, a pump, a 
turbine, and a driving shaft. Commonly, these units are aligned serially 
one behind another. Thus, the entire power path from the engine to the 
driven part of the engine consumes a considerable linear distance needed 
for the fluid coupling between the serially aligned driven and driving 
paths. 
SUMMARY OF THE INVENTION 
A fluid coupling is disclosed for the direct drive of a wheel from a small 
engine. The fluid coupling is mounted in cantilevered support or two ended 
bearing support from a small engine and has a small diameter inner driven 
shaft and a larger diameter out wheel driving shaft for contacting and 
directly driving a wheel. The inner driven shaft connects to a pump having 
a relatively larger outer diameter than either the driven or driving 
shaft. This pump is mounted on the opposite side of the driven wheel from 
the engine and preferably includes rotating vanes within one half a 
toroidal path having an attached eccentrically mounted toroidal plug for 
causing helical rotation of fluid about the plug. A turbine mates to the 
pump and includes rotating vanes within the other half of the toroidal 
path, these vanes being shaped around the toroidal plug of the pump. The 
toroidal plug and toroidal volumes are eccentrically mounted one with 
respect to another to cause high velocity flow on the outside diameter of 
the pump and turbine with low velocity flow in the inside diameter of the 
pump and turbine. Fluid, typically oil, is confined to the pump and 
turbine by appropriate seals and causes torque conversion between the pump 
and turbine. In the preferred embodiment, a fuel tank for the engine is 
mounted overlying the driven wheel so as to shield the interface of the 
wheel and driving spindle. At the same time, the exterior of the driven 
pump is supplied with vanes to generate appropriate air cooling at the 
fluid coupling. A preferred embodiment is disclosed wherein the mount of 
the fluid coupler includes a bearing on the outboard end of the fluid 
coupler.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, fluid coupling C is disclosed for the direct 
drive of wheel W from a small engine E. The fluid coupling is mounted in 
cantilevered support from small engine E, FIG.1 showing the engine and 
rear end of the scooter and FIG. 2 showing wheel and engine alone. 
Referring to the exploded view of FIG. 3, fluid coupling C has a small 
diameter inner driven shaft 14 and larger diameter outer wheel driving 
shaft 16 for contacting and directly driving wheel W. Inner driven shaft 
14 connects to pump 18 having a relatively larger outer diameter than 
either the driven shaft 14 or driving shaft 16. Such connection occurs by 
bolt 15 threading to driven shaft 14. Further, it can be seen that regular 
ball bearing 17 and needle bearings 19 provide the necessary rotating 
bearings to assure transfer of the rotation. 
Referring back briefly to FIGS. 1 and 2, it can be seen this pump 18 is 
mounted on the opposite side of the driven wheel W from engine E. 
Referring to FIG. 5, it can be seen that pump 18 includes rotating vanes 
V.sub.p within one half a toroidal path having an attached eccentrically 
mounted toroidal plug P for causing helical rotation of fluid about the 
plug. Turbine T mates to pump 18 and includes rotating vanes V.sub.T 
within the other half of the toroidal path, these vanes being shaped 
around the toroidal plug P of the pump. 
Referring to the section of FIG. 4, toroidal plug P and toroidal volumes 
between vanes V.sub.p and V.sub.T are eccentrically mounted one with 
respect to one another. Such mounting causes high velocity flow on the 
outside diameter 22 of the pump and turbine with low velocity flow in the 
inside diameter 24 of the pump 18 and turbine 20. 
An important note about vanes V.sub.p and V.sub.T. These respective vanes 
have walls that are essentially parallel to the axis of rotation--such 
configuration while adding to the efficiency of the disclosed fluid 
coupling would add undue fabrication expense. This being the case, the 
vanes V.sub.p and V.sub.T have walls that are essentially parallel to the 
axis of rotation of pump 18 and turbine 20. 
Fluid F, typically oil, is confined to the pump and turbine by appropriate 
seals 30, 32 and causes torque conversion between the pump and turbine. 
Returning to FIGS. 1 and 2, it can be seen that in the preferred 
embodiment, a fuel tank 40 for the engine is mounted overlying the driven 
wheel so as to shield the interface of the wheel and driving spindle. At 
the same time, the exterior of the driven pump is supplied with air vanes 
44 to generate appropriate air cooling at the fluid coupling. 
Referring to FIG. 6, it is desirable to cover engine E with a tank T. This 
can be done with the cantilevered embodiment of this invention or 
alternately with a bearing as set forth in FIGS. 7 and 8. 
Referring to FIG. 6, tank T is shown held to the side of the illustrated 
scooter rear wheel W at respective bolts 101, 102, 103 with appropriate 
washers and lock nuts. Referring to FIG. 7, when tank T demounts from 
bolts 101-103, it exposes plate 105. Plate 105 in turn has a bearing mount 
110 medially of the generally triangular plate 105. 
When plate 105 is in turn removed, it exposed bearing mount 110 which 
protrudes into and captures a bearing 120 on the outward, distal end of 
the fluid coupler remote from engine E (see FIG. 8).