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Continuous Variable Transmission (CVT) Special Patent

The principle goal of the transmission outlined in US patent #5,603,240 (2/18/97) is to provide a

(1.) Cam-Driven Transmission that is a mechanical transmission that is continuously variable from

       Forward to Reverse

(2.) Energy Management System that smoothly converts kinetic energy to and from a potential energy

      device, such as a fly wheel.

As discussed in the Technical Field of Invention including:

i.)         Transmission capable of receiving power into its input in the form of rotational torque

and velocity, and exporting power from its output in the form of rotational torque and velocity

capable of being different then received.

ii.)        Transmissions capable o continuously varying the exported rotational velocity between a

maximum value in a clockwise direction.

iii.)       Mechanical transmission that converts rotary motion into oscillatory linear motion and

then selectively convert such motion back into rotary motion.

iv.)       CVT having low vibration. The technical field of the present invention does not encompass

CVT using belts and pulleys, v-belts, or hydraulic pumps as that being used in current\present

available Technology.

Given that 80-90% of the capacity of most internal combustion engines (ICE’s) is for the purpose of

acceleration only. It is a wise use of the transmission’s energy management capabilities would

allow for the design of vehicles containing much smaller ICE’s, yet provide for equivalent, if not

superior, acceleration for most driving modes. This CVT System is very flexible, although the base

design uses

a four cam design, it can be built as a two, three, or six cam design. The four cam design

optimizes the opposing force loads to mitigate vibrations to balance the design. The other

operating designs can help use different rpm values resulting in an increased transmission speed

and physically smaller unit delivering different power levels.

The Challenges for this CVT System include:

(1.) Vehicle Integration current and future.

(2.) Combination of Controllers to work with this CVT. (3.) Manufacturing Tolerances and Costs.

(4.) Few situations like Continuous 20 miles Distance all up hill ( There may be a slowing down of

the vehicle)

(5.) Discovery of full potential uses and configurations changes for building various models for

this CVT Optimization (i.e, one example: Utilizing usage of Electrorheological or

Magnetorheological Technology and another example: Using this CVT as an Energy Management System

with Flywheel)

By fly wheel it does not mean an ordinary fly wheel, but a light weight device designed to store a

tremendous amount of potential energy. Additionally, the transmission has potential applications

in hybrid vehicles, and even in all electric vehicles. The main claims of the patent refer to the

energy management capabilities since the CVT capabilities, including going from forward continuous

and into reverse continuous, combining the linear portions of multiple cams, and even balancing the motions

of members such as cam followers with opposition motions of similar members have been used in

previous patents.

The first patent brought forward for comparison was for a windmill comparison. A CVT is desirable

in a windmill application because it can be controlled in such as way that the output shaft runs at

a constant speed, thereby modulating the used to turn an armature through a magnetic field. It

used a cam system with similar characteristics to provide CVT capabilities.

The second patent brought forward for comparison was from a 1945 French patent by an inventor named

Schultz. That patent seemed to be directed towards the use of a similar CVT for the purpose of

moving large, heavy vehicles, such as those used for military applications (ie – tank). That design

relied on a one way clutch at the output shaft as a means of combining the contributions of each

cam while providing a release mechanism for any slight mismatches in velocity between cams. As a

result of the one-way clutch, it had no capability of sending energy back through the transmission

through a potential energy storage device.

In order to provide that capability, the use of “caliper-like” devices are used in the current

transmission to allow for energy to go both ways. Furthermore, it was deemed advantageous to have

the transmission continuously engaged. Hence, the cams were designed so that there would be a time

of overlap, where two cams are simultaneously engaged. Although there have been CVT designs that

have relied on cam profiles that are not linear in Theta (turning of the cam), any non-linearity

during the time of simultaneous engagement of the cams will cause the cams to pull against each

other in a way that is undesirable and inefficient. Each cam has a profile with a portion that is

linear in Theta covers 90% plus enough angle to provide sufficient overlap. When ICE drives the

transmission the high RPM is geared down at a constant ratio (maybe future technology will allow

that step to be eliminated) to a lower RPM used to drive an input shaft. The cams convert the

rotation of the input shaft into displacements. Those displacements are put through the physical

equivalent of a dot product in order to scale the displacements to any value between -1 and 1. The

“caliper-like” devices are designed to reconstruct the scaled output by engaging the flanges

connected to the rack-and-pinion

only during the portion where the corresponding input cam is linear in Theta. When it is desired

for the vehicle to slow down, the kinetic energy is converted to potential energy instead of

dissipated. A change in the gear ratio alone can send the energy back through the transmission to

an overriding potential energy storage device. The same energy used to slow the vehicle down can

be used to accelerate it again. While a vehicle is warming up, energy can be placed into the

potential energy storage device to enable initial acceleration.

There are several advantages to this CVT:

1.) Reduction in engine and transmission sizes.

2.) Better fuel economy.

3.) Lower fuel consumption resulting in reduced emissions for pollution control.

4.) Higher efficiency in horse power per engine volume.

5.) Less vehicle weight.

6.) Direct regenerative braking.

7.) Multiple configurations for design. (i.e. four electric motors, one/tire eliminates

differentials resulting in better handling characteristics)

8.) Flexibility in design for all types of engines and vehicle weight classes.

The Best applications of this Type of a CVT is for :

-     All types of I.C.E’s (High Mass Vehicles including: Tractors/ Military Trucks/Civilian

Trucks,Heavy/Medium Vehicles, Three-Wheeler Taxi’s (Rickshaw, Alibaba).

-     Hybrid Vehicles.

-     Electric Vehicles.

Note that the patent does not mention several of the innovative ways to use the transmission,

including having one at each wheel in conjunction with four electric motors. The energy recovery

and management capabilities of the transmission are its key selling points. They enable the use of

a smaller engine that will produce results that are equivalent to that of a larger engine for nearly

all driving modes. Most of the horsepower required for most automobiles is for acceleration. In

city driving most of the energy used for acceleration will be captured while stopping. The

transmission can also handle large torque situations, such as required for tractors and large

trucks. Regenerative braking on buses in Europe using generators have been around since before

this patent, but even in those situations, the regeneration has not been at optimal torque

conditions. Also, the transmission enables the smooth release of stored energy. There is great

confidence that the transmission will work quite efficiently. A Proof of Concept should be pursued to eliminate the main concerns having

more to do with the costs of achieving certain manufacturing tolerances and the possibility that

other economic manufacturing factors could prevent its adoption. An in depth study for feasibility

and marketability in the World Market should be introduced. Hopefully the advantages of this design

for the world economies will out weight any issues and obstacles encountered in the effort to bring

this technology to mass production for the world markets.

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