Flywheel drive system

A drive system including at least a pair of flywheels which rotate in opposite directions about a common axis. The flywheels are drivingly coupled by means of rollers and a first of the flywheels is driven by an electric motor or motors mounted thereon and adjacent the periphery thereof. A rotatable output shaft is positioned between the counterrotating flywheels and the motion of the flywheels is transmitted to the output shaft by means of a roller which contacts the facing surfaces of the flywheels and is radially movable with respct to the flywheels.

BACKGROUND OF THE INVENTION: 
1. Field of the Invention 
The present invention relates to enhancing the efficiency of electric drive 
systems and particularly to the provision of a direct current powered 
drive system suited for use in an environment, such as an electrically 
powered vehicle, where operating power is derived from storage batteries 
subject to periodic recharge. More specifically, this invention is 
directed to a flywheel type drive wherein energy for initiating and 
maintaining the rotation of a flywheel mechanism is furnished by an 
electric motor or motors. Accordingly, the general objects of the present 
invention are to provide novel and improved methods and apparatus of such 
character. 
2. Description of the Prior Art 
While not limited thereto in it utility, the present invention is 
particularly well suited for employment in electrically powered vehicles. 
As petroleum and natural gas reserves dwindle, increasing attention is 
being directed to electrically powered vehicles. While electrically 
powered vehicles were at one time widely used, such vehicles drastically 
declined in popularity when the availability of inexpensive petroluem 
products became widespread. Despite renewed interest in the electrically 
powered vehicles in recent years, there has in fact been little progress 
made in developing a practical "electric". Thus, available electrically 
powered vehicles, the conventional golf cart type vehicle presently being 
the most often used variety of such vehicle, are characterized by a number 
of inherent deficiencies. The single deficiency which constitutes the 
principal impediment to widespread usage is lack of range. This lack of 
range results from the rather high power drain imposed on the bank of 
storage batteries which must presently be utilized as the power source. 
This power drain, to a large measure, results from the substantial weight 
of the conventional lead-acid type battery which is employed in the power 
supply. Thus, a cruising range in excess of 25 miles, with a reasonable 
margin of reserve, can not presently be achieved in an electrically 
powered vehicle of accpetable size for everyday use because of the 
excessive demands imposed on the bank of storage batteries largely as a 
consequence of the weight of those batteries. 
In recent years attempts have been made to improve the cruising range of 
electrically powered vehicles through use of lightweight materials in the 
vehicle body and chassis and by resort to aerodynamic styling. These 
efforst have had some limited success. Attempts to develop power sources 
which could be used in place of the conventional heavy lead-acid storage 
battery have to date been totally unsuccessful. As evidenced by the 
present inventor's U.S. Pat. No. 3,562,567, effort has also been devoted 
to improving the efficiency of the drive systems which convert the 
potential energy of the storage batteries to the kinetic energy of the 
drive shaft. Such efforts to improve drive system efficiency, particularly 
techniques which have employed flywheel type drives, have been moderately 
successful. However, since it remains necessary to rely upon heavy storage 
batteries as the power source, further improvements in drive system 
efficiency are required. 
SUMMARY OF THE INVENTION 
The present invention is a novel and improved electric drive system 
characteristic by enhanced efficiency when compared to the prior art. 
Thus, in accordance with the present invention, a "pancake" drive 
including at least a pair of flywheels which rotate about the same axis in 
opposite directions is provided. In accordance with a preferred embodiment 
of the invention, one of the counterrotating flywheels is directly driven 
by one or more electric motors and the motion of this first or drive 
flywheel is coupled, by means of rollers, to the second or driven 
flywheel. The coupling of the counterrotating flywheels to one another is 
accomplished, in the preferred embodiment, without a direct mechanical 
connection, such as a gear train, and the freely rotatable coupling 
rollers preferably contact the two flywheels adjacent their peripheries. 
Also in accordance with the preferred embodiment of the invention, the 
electric motor or motors are mounted directly on the drive flywheel, at 
the periphery thereof, and drivingy engage a ring gear which is coxial 
with the drive flywheel. 
Also in accordance with a preferred embodiment of the invention, the power 
take off for the drive system is located between the counterrotating 
flywheels. The power take off mechanism includes power-take-off roller 
which is radially movable with respect to the axis of rotation of the 
flywheels, along a rotatable output shaft, in both directions with respect 
to said axis of rotation. The power-take-off roller is drivingly coupled 
to the output shaft and will contact both flywheels. Depending upon the 
position of the roller with respect to the axis of rotation of the 
flywheels, the output shaft will be driven in the clockwise or 
counterclockwise direction. The drive system will be in neutral and the 
output shaft will not rotate when the power-take-off roller is centered on 
the axis of rotation of the flywheels.

DESCRIPTION OF THE PREFERRED EMBODIMENT: 
With reference now to the drawing, and considering jointly FIGS. 1 and 2, a 
drive system in accordance with a preferred embodiment of the present 
invention includes a housing which has been indicated generally at 10. 
While housing 10 has been shown as being cylindrical in cross-section, it 
will be understood that any convenient shape which will accommodate the 
drive system components to be described below may be utilized. The top 
cover 12 of housing 10, which may be removable attached to the remainder 
of the housing by any suitable means to enable servicing, has been removed 
in FIG. 1 to facilitate understanding of the invention. Housing 10 is 
provided, on its interior sidewall, with an inwardly extending flange 14 
which defines a circular opening. Flange 14 will typically be integral 
with housing 10. In the disclosed embodiment a ring gear 16 is provided on 
the upper surface of flange 14. It will, of course, be understood that 
ring gear 16 may be integral with flange 14 or a separate element attached 
to the flange by any suitable means. In the usual case, where flange 14 is 
integral with the housing, ring gear 16 will be a separate element 
removably attached to the flange so as to permit replacement of the ring 
gear in the unlikely event that gear teeth become chipped or broken. 
The drive and power conversion system positioned within housing 10 includes 
a pair of counterrotating flywheels 18 and 20. Flywheels 18 and 20 are 
supported, in the manner to be described below, so as to rotate about a 
common axis. In the disclosed embodiment flywheel 18 is the drive flywheel 
and is caused to rotate, as will become apparent from the following 
description, by an electric motor or motors. Flywheel 20, the driven 
flywheel, is coupled to flywheel 18 by a plurality of rollers 22. Rollers 
22, which preferably have rubber flywheel contacting portions, are freely 
rotatable by means of being keyed to short shafts which are mounted in 
bearing housings, such as housings 24, affixed to the inner sidewall of 
housing 10. Rollers 22 firmly contact the facing surfaces of flywheels 18 
and 20. 
Flywheel 20 is supported from the bottom of housing 10. The support means 
consist of a pedestal 26 affixed to the bottom of the housing. Pedestal 26 
is provided with an opening through which passes an extension 28 of the 
shaft on which flywheel 20 rotates. A bearing 30, typically a tapered 
roller bearing, is located within pedestal 26 and secured to the bottom of 
housing 10. A thrust bearing 32 and a further tapered roller bearing 34 
are mounted on a support washer 36 which is positioned on the top of 
pedestal 26. Undesirable movement of bearing 30 and bearings 32 an 34 is 
prevented in the customary manner; the bearing outer races being located 
within a housing or housings which are respectively secured to the bottom 
of housing 10 and pedestal 26. 
The drive flywheel 18 is supported on ring gear 16 and is keyed to a shaft 
38 which is rotatable in a bearing 40 attached to the cover plate 12 of 
housing 10. Drive flywheel 18, in the preferred embodiment, has a 
plurality of electric drive motors 42, 44 and 46 mounted on its upper 
surface. The drive motors, as best shown in the case of motor 46 in FIG. 
2, are mounted in brackets, such as bracket 48, and are located adjacent 
the periphery of flywheel 18 so as to have the motor output shafts 
extending outwardly from the periphery of the flywheel. Drive gears 50 are 
keyed to the output shafts of motors 42, 44 and 46 and mesh with the teeth 
of the ring gear 16. 
Drive motors 42, 44 and 46 may be either AC or DC motors. If AC motors are 
employed, a solid state static inverter will be utilized to convert the 
direct current power derived from the batteries to alternating current. 
Both AC and DC drive systems have attributes and disadvantages. In the 
interest of system simplicity and minimizing the number of components 
employed, a DC drive is generally preferred. Electrical power is delivered 
to the motors in the conventional manner and, in the interest of 
facilitating understanding of the invention, the currnt transmitting means 
has been omitted from the drawing. Considering a DC drive, a commutator 
assembly may be incorporated on shaft 38 with the stator of the commutator 
assembly being supported from cover plate 12. 
The power take-off for the drive system of the present invention includes 
an output or drive shaft 52. Shaft 52 is supported on bearings, not shown, 
in the sidewall of housing 10 at diametrically opposed points. Drive shaft 
52 is positioned between flywheels 18 and 20 and is coupled to both 
flywheels by a drive or power-take-off wheel 54. The coupling of drive 
wheel 54 to shaft 52 is via a spline type connection, as may be seen from 
FIG. 2, whereby drive wheel 54 may be repositioned along shaft 52 by means 
not shown but well known in the art. The position of drive wheel 54 along 
shaft 52 relative to the axis of rotation of the flywheels determines the 
speed and direction of rotation of output shaft 52. Flywheels 18 and 20 
are provided, coaxial with their axis of rotation, with recessed areas on 
their facing surfaces; such a recessed surface area being indicated at 56 
in FIG. 1 and clearly visible in FIG. 2. With drive wheel 54 positioned 
within the axial recessed area, the drive will be in neutral and drive 
shaft 52 will not rotate. Drive shaft 52 may be coupled to an output 
mechanism such as, for example, the drive wheels of a motor vehicle. 
In operation, current will be delivered to drive motors 42, 44 and 46 
causing the output shafts thereof to rotate. Because of the direct drive 
between the motors and ring rear 16, energization of the drive motors will 
cause the drive flywheel 18 to rotate. Rotation of the drive flywheel 18 
will be coupled, via rollers 22, to the driven flywheel 20 which will 
thereupon rotate about the same axis as but in the opposite direction to 
flywheel 18. The rotation of flywheels 18 and 20 will, when the drive 
wheel 54 is moved out of the neutral position, be coupled to drive shaft 
52 via the friction connection between both flywheels and the drive wheel 
54. Movement of drive wheel 54 along shaft 52 will allow the control of 
both speed and direction of rotation of drive shaft 52. Once the flywheels 
18 and 20 have reached a desired speed, this speed may be automatically 
maintained by sensing the speed of rotation of the flywheels with a 
tachometer and employing conventional control circuitry to adjust the 
delivery of current to the electric motors. Under normal circumstances 
only a comparatively small amount of input power will be required to 
maintain the desired rotational speed of the flywheels once this speed has 
been reached. This attribute, in part a result of the additional mass 
provided by the "pancake" drive consisting of two counterrotating 
flywheels, enhances the efficiency of the electrical drive system of the 
present invention. In the environment of a motor vehicle, when operating 
on very hilly terrain, it may be necessary to adjust both the speed of 
rotation of the flywheels and the positioning of drive wheel 54 to achieve 
the desired operating characteristics. 
As will be obvious to those skilled in the art, since the present invention 
is essentially a continuous motion system, efficiency can be enhanced by 
adding weight to the periphery of the flywheels. The added peripheral 
mounted weight could consist of properly designed batteries located 
adjacent the periphery of the flywheels whereby the batteries would serve 
the dual purposes of energizing the drive motors and adding weight. 
While a preferred embodiment has been shown and described, various 
modifications and substitutions may be made thereto without departing from 
the spirit and scope of the invention. Thus, by way of example, any number 
of electric drive motors can be employed. If a single motor is desired, a 
counterbalancing weight will be added to the drive flywheel 18. Thus, it 
will be understood that the present invention has been described by way of 
illustration and not limitation.