Note: Descriptions are shown in the official language in which they were submitted.
CA 02559498 2006-09-06
HYBRID KINETIC DRIVE SYSTEM
BACKGROUND OF THE INVENTION
1. Field of the invention
The invention relates to a drive system, especially suitable for a vehicle but
can also be
used in other kinds of installations. The load is driven by a dual drive
system consisting of a
principle torque generator and a Flywheel-IVT combine (FIC). The principle
torque generator
could be an internal combustion engine (ICE) or an electric motor/generator or
a combination of
both. The FIC contains a flywheel, a reduction gearing a CVT and a planetary
gear set. The
driving force can be provided by either the principle torque generator or the
FIC or by both the
torque generator and the FIC simultaneously. The FIC stores energy and
releases energy when
needed. It also absorbs kinetic energy from the vehicle when braking. Similar
energy recovery
schemes can be envisioned for the other kinds of installations. An essential
element of the
invention is the Internal Tracing Continuously Variable Transmission that
allows the FIC to
release as well as to absorb energy from the load with high capacity and
minimal frictional loss.
2. Description of Prior Art
Concern for the environment has drawn attention to the development of
alternatives for
the internal combustion engine (ICE), gasoline supplement and substitutes, as
well as hybrid
vehicles whereas a vehicle is powered by an electric motor in addition to the
ICE. Efforts have
also been directed at optimizing the power generated by an ICE by means of a
hybrid power
system comprising a flywheel. US Patent 3,886,810 teaches a system in which
the flywheel is
driven by the prime mover such as an internal combustion engine when an excess
of power input
is available from the prime mover. The flywheel would be connected to the
transmission input
shaft, releasing its absorbed energy when the vehicle is to be driven under
heavy load. More
recently Internal Publication WO 2004/000595 describes a more refined system
to accomplish
the storing and release of energy by means of flywheel. As far as we are aware
of all systems
disclosed so far only allow the release of energy from the flywheel to the
driven shaft of the
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vehicles. In reality the occasion where the flywheel can uptake the excess
power generated by
the prime mover is limited to the periods of starting and acceleration,
thereby disparages the
justification for installing the flywheel. On the contrary vehicle operation
involves frequent
periods of slow down followed by periods of picking up speed. This is
particularly true in urban
areas and even more pertinent for vehicles that must make frequent stops such
as buses and
service vehicles (e.g. garbage trucks). It would be greatly economical if the
flywheel can absorb
energy from the driven shaft when the vehicles slows down the flywheel would
release the
absorbed energy during the subsequent acceleration. None of the disclosed
system allows for the
flywheel to absorb energy from the load.
A system that allows two-way transmission of energy between the flywheel and
the
driven shaft requires an Infinitely Variable Transmission (IVT). Infinitely
Variable Transmission
is a subset of the Continuous Variable Transmission (CVT) that was
conceptualized by Leonardo
da Vinci more than 500 years ago and the first CVT patent, of the toroidal
type, was filed in
1886. The technology has been greatly improved and refined and many current
car
manufacturers are designing their power train around CVT of the V-Belt (Honda,
Audi) and Half-
Toroidal (Nissan) types. Significant slipping between the contacting
components, common
known as microslip, is a common occurrence with the above-mentioned types of
CVT. Special
tracing oil is required to reduce damages to the components. Currently the
CVTs are introduced
as alternative to the tradition automatic transmission package. The existing
CVTs are not
suitable for the two-way transfer of energy.
SUMMARY OF THE INVENTION
The following disclosure concentrates on the drive system for a vehicle but it
is clear that
such a drive system can also be used to drive stationary machinery.
An objective of the invention is to maximize the use of energy released by the
principal
torque generator, which can be an internal combustion engine or an electric
motor or a
combination of both, by the means of an assembly comprising a flywheel and an
Infinitely
Variable Transmission, hereafter referred to as the Flywheel-IVT Combine
(FIC). Such a power
plant, comprising of a principal torque generator and the FIC is a Hybrid
Kinetic Drive System
(HKDS).
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In a gas powered vehicle equipped with an internal combustion engine, without
the FIC,
the engine speed increases after ignition while the vehicle remains at rest,
all energy released by
the engine is wasted. As the vehicle accelerates after being put in motion,
the engine continues to
release more energy than can be transmitted to the driven shaft, resulting in
engine roaring and
more waste of energy. A vehicle equipped with a HKDS affords efficacy from the
time of
ignition and throughout the running cycles.
In battery operated vehicles acceleration is a major concern. A compact car
needs about
60 kw to achieve acceptable acceleration. This requires a heavy and expensive
battery. With
HKDS, the FIC provides sufficient power for acceleration to allow minimizing
the required
battery power as well as the internal loss.
An embodiment of the invention allows the energy released by the engine,
beginning at
ignition, be absorbed into the flywheel until the vehicle is put in motion.
The engine can be cut
of less than a minute after ignition to allow the flywheel assembly releases
its stored (absorbed)
energy to accelerate and maintain the speed of the vehicle. While the vehicle
accelerates any
energy released by the engine in excess of what can be transmitted to the
driven shaft continues
to be absorbed by the flywheel. The flywheel assembly can be designed to
absorb a great amount
of energy to allow the vehicle to be put in motion with a"jump start" as is
desirable in racing
cars.
The HKDS allows for the vehicle to be mobilized, maintained a desired speed or
accelerated, by the energy released from the flywheel assembly or the engine,
or both. This
possibility permits an optimal design of the engine resulting in improved fuel
economy. In
addition to enabling the vehicle to be accelerated and maintained in constant
speed as described
above, the flywheel assembly affords the possibility of recuperating energy
when the vehicle
decelerates. If the brake is applied while the vehicle is in motion, proper
gearing allows the rpm
of the flywheel to increase thus recuperates the kinetic energy of the moving
vehicle. It is clear
that the flywheel assembly affords high fuel efficiency, particularly for
vehicles that must make
frequent stops and starts such as buses and service vehicles. It is recognized
that even with the
energy conservation during breaking, maintaining the motion of the vehicle
still reduces the rpm
of the flywheel and the principal torque generator must be restarted at
certain time. The HKDS
allows the power from principal torque generator to be applied to the load
with or without
passing across the FIC. Form rest to about 50 km/hr, the principal torque
generator operates from
time to time, supplying energy to the load through the FIC. At speeds higher
than 50 km/hr, the
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principal torque generator operates continuously; power from principal torque
generator is
geared to the load without passing across the FIC. That improves the life time
of the CVT as
well as the efficiency of the system. These are situations where the vehicle
runs with the energy
released by both the flywheel assembly and the principal torque generator. It
is obvious that the
vehicle would require a principal torque generator smaller than that of a
comparable conventional
vehicle equipped only with an internal combustion engine. It is also clear
that innovative gearing
and transmission is necessary.
Figure 01 presents a block diagram of a Hybrid Kinetic Drive System. A
principal torque
generator 01 delivers the driving energy to the load through the gearing unit
06 and clutch 08.
The flywheel 03 is connected a speed reduction gearing unit 04 which is
engaged to the Internal
Tracing Continuously Variable Transmission (ITCVT) 02. Clutch 07 provides the
connection
between the torque generator and the FIC. In concert with the ITCVT planetary
gear set 05
allows the energy of the flywheel to drive the load as well as the reverse
flow of energy so that
the flywheel can absorb the energy from the load. Planetary gear set 05 also
permits an
enlargement of the gear ratio span to perform a smooth start and to serve as
the reverse gear.
Fig. 02 presents a further development whereas an electric motor/generator is
installed in
addition to the internal combustion engine. The motor/generator also connects
to the output of
gearing unit 04. More details of this development are illustrated in Fig. 09
to be discussed later.
The Internal Tracing Continuously Variable Transmission (ITCVT) is the
essential
component of the innovative flywheel assembly. In one embodiment, as shown in
Fig. 03, an
ITCVT comprises of a number (n) of truncated open cones 201 that are mounted
on an axis with
provision for varying the distance between them. There is a number (n-1) of
rings 202 mounting
inside a drum with provision for varying the distance between them also. The
drum 203 is
supported by carrier 204 by means of roller bearings 205. A ring gear 206
transfers the
movement from the rings to the gear 207. The carrier 204 is mounted on the
housing of the
ITCVT by means of journals 208 that have their axis on the same line with axis
of gear 207. This
arrangement allows carrier 204 to turn around the center to effect a variation
of the distance
between the center lines of cones 201 and that of rings 202. A hydraulic
cylinder 209 actuates
the movement of carrier 204 thereby controls the distance between the center
lines of cones 201
and that of rings 202.
Figure 03 shows the ITCVT in a position to produce a speed ratio of 1:1
between the
cones and the ring while Fig. 04 shows a position to produce a speed ratio of
2.4:1.
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In the embodiment presented in Fig. 03 and Fig. 04 the clamping force between
cones 201
and ring 202 is provided by hydraulic pressure applied to the end face of the
first cone.
In the embodiment presented in Fig. 03 and Fig. 04 the speed ratio can vary
continuously
from 1:1 to 2.4:1. This embodiment is designated as the Open-Cone
Configuration. It is also
clear that truncated cones 201 can be made to allow speed ratio higher than
2.4:1.
Fig. 05 shows ring 202 in detail. The ring is designated as the Plain-Ring
Configuration.
Fig. 06 shows ring 202 in another combination designated as the Flexible-Ring
Configuration. In the figure, folded ribbon 2021 is mounted inside the ring
202. A retaining ring
2022 is used to keep ribbon 2021 in place. The folded form of ribbon 2021
confers flexibility to
reduce the micro slip between its contacting surfaces and the cones.
Another embodiment is designated as the Closed-Cone Configuration. As
illustrated in
Fig.07 the embodiment comprises of three closed cones 201 and two rings 202.
It is clear that the
number of cones and rings may vary. The rings are mounted on shaft 203 with
provision for
varying the distance between them. The shaft 203 is supported by carrier 204
by means of
bearings 205. A gear 206 transfers the movement from the rings to the gear
207. The carrier 204
is mounted on the housing of the ITCVT by means of journals (not shown) that
have their axis on
the same line with axis of gear 207. This arrangement allows carrier 204 to
turn around the
center to effect a variation of the distance between the center lines of cones
201 and that of rings
202.
Further illustration of the block diagram is given below. In Fig. 08, gearing
06 is
mounted on the engine. The output of this gearing connects to main shaft 11.
Clutch 08 connects
the main shaft to driving sprocket 12 of the chain assembly. The power from
driven sprocket 13
goes through the drive and reverse gearing 09 and then to the differential 10.
Clutch 07 connects
main shaft 11 to gear 14 that is meshed to gear 15. From gear 14, power flows
in two directions:
in one direction power passes gear 15, the CVT, gears 16 and 17 and then to
sun gear 18 of the
planetary gear set 05; in the other direction power passes motor /generator
23, clutch 21,
reduction gearing 04, and then to the flywheel 03. One-way clutch 22 operates
in parallel with
clutch 21; it transfers energy from the load to the flywheel only. This
arrangement allows the
flywheel to automatically disconnect from the load in case of an emergency
brake.
Planetary gear set has 3 components; the first component is sun gear 18 that
connects to
the output of the CVT (gear 17), as mentioned. The second component is carrier
19 that connects
to gear 14. The third one, ring gear 20, is that connects to driving sprocket
04.
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Fig. 09 presents a combination of an ICE and an electric motor/generator. With
reference
to Fig. 08 an electric motor/generator is 23 added with connection to main
shaft 11. Electric
motor/generator 23 is used to start the engine, recharge the battery and to
run the vehicle during
engine shut-off. The drive and reverse gearing unit is not necessary. Reverse
gear is achieved
with the electric motor or by enlarging the gear ratio span at the FIC.
LIST OF FIGURES
Fig. 01 Hybrid Kinetic Drive System
Fig. 02 Hybrid Kinetic Drive System with an Electric Motor/Generator
Fig. 03 ITCVT (Internal Tracing Continuously Variable Transmission)
Fig. 04 ITCVT at Speed Ration 2.4:1
Fig. 05 Plain Ring
Fig.06 Flexible Ring
Fig. 07 ITCVT with Closed Cones
Fig. 08 Typical Design
Fig.09 A system including an Electric Motor/Generator
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