U.S. patent application number 12/229288 was filed with the patent office on 2008-12-18 for regenerative self propelled vehicles.
Invention is credited to Donald C. Anderson, Edmund S. Lee, III.
Application Number | 20080308335 12/229288 |
Document ID | / |
Family ID | 39711165 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080308335 |
Kind Code |
A1 |
Anderson; Donald C. ; et
al. |
December 18, 2008 |
Regenerative self propelled vehicles
Abstract
An electric motor powered vehicle includes an energy reservoir
provided by a battery-mass flywheel having a diameter approximating
the lateral spacing of the vehicle's wheels. A The flywheel may
include a pair of counter rotating wheels mounted on concentric
shafts and may be enclosed in a containment device. A shoe-rail
electrical connection facilitates transfer of current to and from
the batteries. The flywheel may include fuel cells charged from a
remote hydrogen source. Flywheel, and friction braking may be
controlled by pedal movement. Motive power is preferentially
provided by flywheel energy then battery energy. Energy may be
transferred to the batter mass flywheel independently of vehicle
motor drive. The motor-flywheel drive connections are made through
inputs to a differential gear drive. The fuel cells may charge the
batteries, and a second alternator may recover flywheel energy at
shut-down
Inventors: |
Anderson; Donald C.;
(Moraga, CA) ; Lee, III; Edmund S.; (Terrace Park,
OH) |
Correspondence
Address: |
Edmond S. Lee III
104 Fieldstone Dr.
Terrace Park
OH
45174
US
|
Family ID: |
39711165 |
Appl. No.: |
12/229288 |
Filed: |
August 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10251945 |
Sep 20, 2002 |
7416039 |
|
|
12229288 |
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Current U.S.
Class: |
180/165 |
Current CPC
Class: |
B60K 6/30 20130101; B60K
1/04 20130101; Y02T 10/92 20130101; Y02T 10/70 20130101; B60K 1/00
20130101 |
Class at
Publication: |
180/165 |
International
Class: |
B60L 7/20 20060101
B60L007/20 |
Claims
1. A self propelled vehicle comprising: electric motor means for
powering motive operation of the vehicle; a battery array for
energizing motive operation of the vehicle; a power demand pedal;
means, responsive to displacement of the demand pedal, for
providing a power demand signal, which signal is proportionate to
the extent to which the demand pedal is displaced; a regenerative
braking system, which recaptures energy that would otherwise be
lost in decelerating the vehicle, said regenerative system
including, operator actuated means for invoking deceleration of the
vehicle, means, including a rotatable flywheel on which the battery
means are mounted, for storage of kinetic energy, means, responsive
to the invoking of vehicle deceleration, for transferring vehicle
kinetic energy to the flywheel means, alternator means for
recharging the battery array when the flywheel exceeds a
predetermined rate of rotation; means, operative in response to
initiation of vehicle operation, for utilizing flywheel energy to
power motive operation; and means operative upon the flywheel
energy being insufficient to provide a desired rate of motive
operation, for utilizing battery energy to power motive operation
of the vehicle, whereby the number of battery recharging cycles is
minimized.
2. A self propelled vehicle as in claim 1 wherein the means for
invoking deceleration comprise a pedal moveable through a range of
motion to thereby create a deceleration signal proportionate to the
degree of movement, the rate of deceleration is proportionate to
the strength of the deceleration signal;
Description
[0001] The present application is a continuation application of
copending application Ser. No. 10/251,945, filed Sep. 20, 2002.
[0002] In a general sense the present invention relates to the
reduction of atmospheric pollution by self propelled vehicles. More
specifically, the invention relates broadly to improvements in
regenerative, electric motor powered vehicles, with particular
emphasis on improvements in those motor powered vehicles in which
there is an on board electric energy source, having particular
reference to batteries, as well as fuel cells. The end sought by
these improvements is to make practical the elimination of internal
combustion engines as a power plant, or, at least the sole power
plant, for some significant portion of self propelled vehicles,
viz., automobiles, trucks, etc.
[0003] Battery energized propulsion systems are the most
technologically advanced alternative to the internal combustion
engine and, for the near term, are the most likely non-polluting
substitute. This fact is well recognized and intensive efforts have
been carried out in an attempt to develop economical, commercially
acceptable, battery energized, motor powered vehicles and thereby
satisfy this long felt need for pollution reduction. Also, fuel
cell technology has recently been developed to a point where it has
the potential to provide an acceptable, alternate energy source for
electrical motors employed in powering vehicles.
[0004] The ultimate end sought in the reduction of pollution is the
complete elimination of the products of combustion of fossil based
fuels. To date the most effective results of this development
effort to reduce atmospheric pollution has been a compromise in
which both a battery powered motor and an internal combustion
engine are employed. One presently available, hybrid system has a
highly refined capability of selectively engaging the motor and
engine power source enabling payloads, operating ranges and speeds
comparable with conventional gasoline fueled automobiles, while
achieving gasoline economy in excess of 60 miles to the gallon.
[0005] While improved gas mileages in this order of magnitude are
significant in reducing pollution, there are many congested areas
where the only acceptable solution is an automobile (truck, etc.)
with zero emissions, as would be provided by an automobile powered
solely by battery energy.
[0006] The basic problem with a battery powered vehicle is that the
batteries have a finite quantum of usable energy. That quantum of
energy defines the range/payload capability of the vehicle. Once
that quantum has been expended, the vehicle is unusable until the
batteries are recharged. This is to say that the range/payload of a
vehicle is a direct function of the mass of its batteries.
[0007] Batteries are relatively high in cost, therefore the cost of
a vehicle is significantly increased, in direct proportion to the
mass of its batteries. The working life of batteries can also
seriously impact the economics of a battery powered vehicle, since,
from an economic standpoint, miles per battery replacement cost now
becomes the determining factor. Where batteries are the only energy
source for a vehicle, there is an essentially continual drain of
energy in powering a vehicle for transportation purposes. In one
form of regenerative braking where an alternator is driven by
vehicle kinetic energy, the batteries are recharged, but this is
only temporary, and the drain of battery energy continues upon
reacceleration of the vehicle. Depth of battery discharge is the
defining parameter for range/payload capability. Battery life is
inversely proportional to percent of discharge, at a progressively
increasing rate.
[0008] In recent years, and, in part due to the impetus of seeking
a reduction in vehicle emissions, there have been significant
improvements in battery technology. New battery chemistries, such
as alkaline and lithium, have been developed and perfected.
[0009] Another factor in battery life is the number of
discharge/recharge cycles during the working life of a battery.
Among the features of the invention is the minimization of
discharge/recharge cycles to thereby increase the working life a
battery, as will be later dealt with in greater detail.
[0010] It is to be recognized that the use of an electric motor is
the key to obtaining the desired reduction in atmospheric
pollution. With this in mind, it is to be appreciated that fuel
cells can also provide an alternative to batteries as the energy
source for an electric motor powered car. Simplistically speaking,
a fuel cell is a device that generates direct current energy by
means of a chemical reaction.
[0011] Intertwined with the attempts to improve the efficiency of
propulsion systems in general, are attempts to recover vehicle
energy which is otherwise lost energy. Although there are other
forms of lost energy, almost all efforts in this regard have been
directed toward recovering the energy that is required for
decelerating a vehicle, as is conventionally done through the use
of friction brakes. Such systems are known as regenerative braking
systems and are based on transforming the kinetic energy of vehicle
movement to electrical energy by recharging batteries, as by
drivingly connecting an alternator to the wheels of the vehicle; or
by transferring the kinetic energy of the vehicle to a flywheel and
then returning such rotational energy as a drive input for the
vehicle, or employing this rotational energy to recharge the
batteries. Various combinations of these means for restoring
deceleration energy to the energy available for propulsion of the
vehicle are found in the prior art.
[0012] Flywheels are a well known energy storing device employed in
regenerative braking systems. The approach conventionally taken has
been to add a flywheel device to a drive system which includes
batteries, an electrical motor and the necessary mechanical
connections between the wheels, the motor, the flywheel device and
an alternator to enable deceleration energy to be recovered in a
battery powered vehicle.
[0013] In only one known instance has there been a departure from
this conventional approach, being found in U.S. Pat. No.
3,497,026-Calvert. Calvert teaches the use of a flywheel on which
batteries are mounted. The weight decrement incident to providing a
flywheel is thus minimized as the batteries serve the additional
function of providing needed flywheel mass for the storage of
energy.
[0014] In Calvert the flywheel also functions as an overgrown motor
housing, having field poles mounted on the inner diameter of a
central hub, in surrounding relation to the armature of the motor.
The basic mode of operation is for the armature to be the
relatively fixed component of the motor, with the housing/flywheel
being the rotating component of the motor. The motor
housing/flywheel also serves as the drive input to the driving axle
of the vehicle. The operating characteristics of the motor are such
that a constant speed differential is maintained between central
armature and the housing/flywheel. As the vehicle accelerates, a
mechanical feedback rotates the armature to maintain the constant
speed differential. To illustrate, when the vehicle is stopped, the
housing/flywheel speed would be 500 rpm. When the vehicle is in
motion, the housing/flywheel could be 400 rpm and the
counter-rotating armature would be 100 rpm (making up the constant
500 rpm relative speed). During acceleration, energy is supplied
from the battery to maintain the constant speed differential. When
the vehicle decelerates, the armature decelerates, increasing the
speed differential, the armature and field poles then function as a
generator. In the generation of electricity, an electromagnetic
force is created which tends to decelerate the
housing/flywheel.
[0015] In view of the demand for and governmental pressures to
force acceptance of zero emission vehicles, it is indeed surprising
that the potential of Calvert has not been exploited. This is to
say that, prior to Calvert, the mass of the batteries in a battery
powered vehicle was simply a dead weight that represented a system
decrement and limited the range/load capability of a given vehicle.
Calvert recognizes that when the batteries are mounted on a
flywheel, their mass can serve a regenerative function, in storing
kinetic energy that can be recovered as electric energy or kinetic
energy. To the best of our knowledge there has been no proposal
aside from Calvert, let alone any actual usage of the concept of
battery mass flywheels, where the mass of the batteries serves as
an energy storage device for kinetic energy that is later recovered
and returned for use in powering the vehicle. This is a highly
significant feature in that for a given battery system, energy that
would otherwise be lost, is recovered and thus provides a greater
payload/range capability, a most critical factor in achieving
commercial acceptance.
[0016] A broad object of the present invention is to minimize
atmospheric pollution through the provision of a electric energy,
powered vehicle having operating capabilities that make it a
commercially practical alternative to conventional, gasoline (and
other hydrocarbons) fueled vehicles.
[0017] Another of the broader objects of the present invention is
improve the recovery of energy in regenerative operation of a
electric energy powered vehicle.
[0018] Another object of the present invention is to provide an
electric energy powered vehicle which is of the subcompact type and
particularly suited for use in commuting between residence and work
or residence and a train station.
[0019] Another of the more specific objects of the present
invention is to attain improved regenerative operation of a vehicle
having fuel cells as a primary energy source and battery energy as
a secondary energy source for improved acceleration
characteristics.
[0020] The present invention, in all of its aspects, takes the form
of a electric energy powered vehicle which comprises wheel means
for supporting the vehicle for movement along a surface; motor
means for powering motive operation of the vehicle; an electric
energy source for energizing the motor means and a regenerative
system for recapturing energy that would otherwise be lost in the
operation of the vehicle. In all cases the regenerative system is
provided with flywheel means, including at least one flywheel. The
flywheel means functions as a reservoir, for the temporary storage
of energy that is returned to the overall energy system of the
vehicle.
[0021] In one specific aspect the invention is directed to the use
of batteries as the energy source and the minimization of battery
charging cycles, This end is attained through the provision of a
regenerative braking system which recaptures energy that would
otherwise be lost in decelerating the vehicle. The regenerative
system further includes means, responsive to the invoking of
vehicle deceleration, for transferring vehicle kinetic energy to
the flywheel means, and alternator means for recharging the battery
array in response to the flywheel reaching a predetermined rate of
rotation. Means, operative in response to initiation of vehicle
operation, for utilizing flywheel energy to power motive operation;
and means operative upon the flywheel energy being insufficient to
provide a desired rate of motive operation, for utilizing battery
energy to power motive operation of the vehicle. Preferably the
means for invoking deceleration comprise a pedal moveable through a
range of motion to thereby create a deceleration signal
proportionate to the degree of movement, and the rate of
deceleration is proportionate to the strength of the deceleration
signal.
[0022] The above and other related objects and features of the
invention will be apparent from a reading of the following
description of preferred embodiments of the invention, and the
novelty thereof pointed out in the appended claims.
[0023] In the drawings:
[0024] FIG. 1 is a simplified elevation of an electric car
embodying the present invention, with portions thereof broken
away;
[0025] FIG. 2 is a plan view of the electric car seen in FIG. 1,
also having portions thereof broken away and primarily illustrating
the drive components therefor;
[0026] FIG. 3 is a section, on an enlarged scale, taken generally
on line 3-3 in FIG. 2;
[0027] FIG. 4 is a section, on an enlarged scale, taken generally
on line 4-4 in FIG. 2;
[0028] FIG. 5 is a view, on an enlarged scale, taken generally on
line 5-5 in FIG. 2;
[0029] FIG. 6 is a section, on an enlarged scale, taken generally
on line 6-6 in FIG. 2;
[0030] FIG. 7 is a section, on a further enlarged scale, of
mounting means for flywheels, which are illustrated in FIG. 6;
[0031] FIG. 8 is a section taken on line 8-8 in FIG. 7;
[0032] FIG. 9 is a section taken on line 9-9 in FIG. 7;
[0033] FIG. 10 is a section taken on line 10-10 in FIG. 7;
[0034] FIG. 11 is a plan view, on an enlarged scale of a
containment device seen in FIG. 2, with portions broken away and in
section to show portions of flywheels that are disposed
therein;
[0035] FIG. 12 is a view taken on line 12-12 in FIG. 11;
[0036] FIG. 13 is a view taken on line 13-13 in FIG. 11;
[0037] FIG. 14 is a section taken on line 14-14 in FIG. 11;
[0038] FIG. 15 is a section taken on line 15-15 in FIG. 11;
[0039] FIG. 16 is a fragmentary view, on a greatly enlarged scale,
of a portion of a flywheel and a current transmitting shoe, seen in
FIG. 15;
[0040] FIG. 17 is a schematic view of electrical and control
components for the electric car of the present invention;
[0041] FIGS. 18-23 are schematic views illustrating various
operating modes of the electric car of the present invention;
[0042] FIG. 24 is a plan view, on an enlarged scale, of a portion
of a modified containment device illustrating an alternate mounting
of an alternator employed herein;
[0043] FIG. 25 is a view taken on line 25-25 in FIG. 24;
[0044] FIG. 26 is an elevation, similar to FIG. 6, of a drive train
for this alternate alternator mounting;
[0045] FIGS. 27 is a schematic view illustrating the cruise
operating mode of the embodiment seen in FIG. 24-26;
[0046] FIGS. 28-31 are schematic views illustrating various
operating modes of a regenerative system in which a further form of
alternator is employed;
[0047] FIG. 32 is a simplified view illustrating an alternate
construction of the alternator seen in FIGS. 28-31;
[0048] FIGS. 33-40 are schematic views illustrating various
operating modes of a further embodiment of the invention in which a
motor/generator alternately provides motive power and regenerative
braking;
[0049] FIGS. 41-44 are schematic views illustrating various
operating modes of a modified drive system for the motor/alternator
embodiment;
[0050] FIG. 45 is a schematic view of electrical and control
components for a further embodiment of the invention having both
battery and fuel cell sources of electrical energy;
[0051] FIG. 46 is a view similar to FIG. 7 illustrating the
mounting of flywheels respectively carrying a battery array and a
fuel cell array;
[0052] FIG. 46A is a section of the outer rim portion of a fuel
cell flywheel seen in FIG. 46 and an adjacent portion of a
containment device;
[0053] FIG. 46B is a development, on an enlarged scale, take on
line 46B-46B in FIG. 46;
[0054] FIG. 47 is a section taken on line 47-47 in FIG. 46; and
[0055] FIGS. 48-51 are schematic views illustrating various
operating modes of an electric car powered from a fuel cell energy
source and also from a battery array, energy source.
[0056] With reference to FIGS. 1 and 2, the present invention is
illustrated in a sub-compact car embodiment which would be
particularly suited for commuting usage, where a small space
envelope minimizes highway and parking space requirements. This
car, identified generally by reference character 30, comprises the
basic components of an automobile, namely, laterally spaced front
and rear wheels, 32, 34, a driver's seat 36 and passenger seat 38.
Direction of movement of the car 30 is controlled by a steering
wheel 40, which controls the angular positioning of the front
wheels 34, through any of the many conventional linkage systems
that serve this purpose.
[0057] The car 30 is powered by an electric motor 42 and a
regenerative braking system, which can best be understood by next
referencing FIG. 18. The motor 42 is provided with a drive
connection 43 to a differential gear 44, which drive shafts 46 for
the front wheels 34. Battery means for energizing the motor 40
comprise battery arrays 48, 50, carried, respectively, on flywheels
52, 54. In operating the car 30, a foot controlled, power demand
pedal 56 is depressed to provide an energizing connection from the
battery arrays, 48, 50 to the motor 40. The car 30 may be
decelerated by depression of a brake pedal 57 (seen in later Figs.
illustrating its use).
[0058] As discussed above, a regenerative braking system restores
to the vehicle's energy system, energy that would otherwise be lost
in decelerating the car. The ?present invention is based on the use
of flywheels 52, 54 that serve as a reservoir to which kinetic is
transferred in decelerating the car and from which kinetic energy
is provided for subsequent, powered operation of the car.
Additional regeneration is provided through the use of alternator
means both as a deceleration means and as an energy recapture
means, through recharging the battery means to return deceleration
energy to the car's electrical energy system. To these ends, the
regenerative system includes a power train 58 adapted to connect
the flywheels 52, 54 with the differential 44. The power train 58
includes a clutch 60, the rotor (not illustrated in FIG. 18) of an
alternator 62, a clutch 64 and a variable drive transmission 66.
The mode of operation of the regenerative braking system will be
later described.
[0059] A sub-compact car, as herein referenced, as well as the many
other vehicles in which the present regenerative braking system
could be embodied, can include a host of sub-systems and related
features, which are necessary, or desirable for operation of a
vehicle, but are unaffected by and/or wholly unrelated to the
regenerative system itself, except as specifically stated herein.
In the present disclosure, many such conventional subsystems are
omitted, and some are shown in the drawings without specifically
being referenced in the description. On the other hand, a chassis,
or structural framework, which is a load carrying member found in
all vehicles, has relevance to the present invention in a fashion
that will be discussed in detail.
[0060] The flywheels 52, 54 are preferably formed with a diameter
which is maximized in order to maximize the energy capacity of the
flywheels, viz., the mass of the battery arrays 48, 50, and
minimize the centrifugal forces on the batteries. Consistent with
recognized design parameters of a sub-compact car, the lateral
spacing between the wheels 32, 34, approximates at least four feet
and the flywheel diameter approximates that spacing, herein being
48 inches, for a point of reference.
[0061] Even at the rates of rotation contemplated by the present
invention, centrifugal forces on the flywheels 52, 54 are
significant. Considering further that the electrolytic components
of the battery arrays will most likely be hazardous, in one fashion
or another, it is highly likely that precautions will need to be
taken to minimize spread of contamination in the event of a
structure failure of the flywheels. While the details of the
battery arrays are later described, it can be noted at this point
that lead acid-batteries are the most cost effective form of
battery chemistry currently available. The hazards of the original
lead-acid battery can be greatly minimized by the use of absorbed
glass mat (AGM) technology, which essentially eliminates free
liquid acid. By using AGM battery arrays (48, 50), there will be
little or no spread of liquid acid in the event that a structural
failure of the flywheel should occur. Even so, it is preferred that
a containment device 68 be provided in surrounding relation to the
flywheels 52, 54, in order to minimize, if not eliminate,
uncontrolled dispersion of lead fragments and/or acid bearing glass
mats (or other electrolytic cell components).
[0062] The containment device 68 comprises an annular casing 70 and
upper and lower covers 72, 74 (FIGS. 1, 2, 6 and 11-15). These
primary components of the containment device may be high
strength-to-weight constructions to minimize the weight penalty in
protecting against structural failure of the flywheels. Thus the
annular casing 70 can be advantageously formed as a filament
reinforced resinous construction. The covers 72, 74 are each formed
as basically thin walled constructions, having reinforcing ribs,
and thickened portions where required for functional purposes. A
light weight metal, such as an aluminum alloy can be used as the
material for the covers 72, 74. Thus, it will be seen that the
covers 72, 74 are defined by thickened, annular rim portions 76 and
annular flanges 78 (see also FIG. 12), which are telescoped over
the shell 70 and are held in assembled relation by screws 80.
[0063] Advantageously, the containment device 68 actually becomes a
load bearing portion of the automobile's chassis. Thus, brackets 82
and a cross bar 84 (FIGS. 1, 2 and 11) are mounted on flanges 78 of
the containment device covers 72, 74 by the bolts 80, which are
also serving the function of holding the covers in assembled
relation on the casing 70. The brackets 82 and cross bar 84 are
connected to spring suspension systems 88, which interact with
bearing systems 90 for the rear wheels 32.
[0064] The load bearing structure (chassis) of the car also
includes brackets 92 (FIGS. 1-3 and 6), attached to the top and
bottom containment device covers 72, 74, being mounted in assembled
relationship by other of the screws 80. The brackets 92, on each
side of the containment device, are joined by a vertical portion
94. The chassis also includes a U-shaped bracket comprising (as a
simplified showing) a bridge 96, at the forward end of the car, and
rearwardly projecting legs 98, attached to the containment device
brackets 92. These chassis portions (96, 98) transmit the weight of
the vehicle to mountings 100 for the front wheels 34 through
conventional suspension systems (not illustrated).
[0065] Constructional details of the flywheels 52, 54 will next be
described with reference to FIGS. 7-16. The flywheels 52, 54 serve
as carriers for the battery arrays 48, 50, previously referenced in
describing FIG. 18. From a constructional standpoint, these
flywheels may be identical, except for the central, hub portions
thereof. Thus, each flywheel may comprise outer disc portions 102,
104 interconnected by an outer, annular rim portion 106 and an
intermediate annular band 108. The flywheel structure is further
reinforced by radial vanes 110 that also interconnect the disc
portions 102, 104. A central hub 111 then joins the central
portions of the disc portions 102, 104. The vanes 110, rim 106 and
band portion 108 define a plurality of battery compartments 112,
114 in the flywheels 52, 54 in which the battery arrays 48, 50 are
respectively carried.
[0066] The described portions of the flywheels 52, 54 are
advantageously formed of a fiber reinforced resin, such as a
glass-fiber reinforced, epoxy resin. This provides a high strength
to weight ratio, which minimizes the weight of the structural
portions of the flywheels, which are subject to substantial
loadings during rotation of the flywheels. As will later be
discussed, the greater the mass of the voltaic cells, as a
percentage of total of flywheel weight, the greater the increase in
payload range capability.
[0067] The battery mass of the flywheel is also maximized ba wound
band 116 (FIGS. 15 and 16) of high strength filaments, graphite
filaments having a diameter in the order of 0.001 being
illustrative of a suitable filament material. When the flywheels
are rotating, high centrifugal forces will be generated in the
outer rims 106 of the flywheels.
[0068] By using the wound filament reinforcement, these centrifugal
loadings will be taken in tension by the filaments. Since such
filaments have extremely high tensile strengths and minimal
elongation, the rims 106 may be light in weight and highly stable
at all operating speeds, while permitting maximization of the
volume/energy capacity of the battery arrays. The load carrying
capacity of the filament band is enhanced by forming the band with
a cylindrical surface and by progressively increasing the thickness
of the band toward its central section, as illustrated.
[0069] Referencing FIGS. 7-11, the flywheels 52, 54 are mounted for
counter-rotation within the containment device 68, with the lower
flywheel 52 being mounted on a central shaft 118 and the upper
flywheel 54 being mounted on a concentric tubular shaft 120.
?(claim) The resinous portions of the two flywheels, as previously
mentioned, may be identical, with each having a central, splined
bore 122. The bore 122 of the lower flywheel 52 then receives a
correspondingly splined, metal hub 124. The upper flywheel 54 is
similarly configured with a correspondingly splined metal hub 126
being received in the bore 122. Preferably the metal hubs 124, 126
are bonded into the resinous hubs 111 of the respective flywheels
52, 54. The inner diameter of the hub 126 is splined and engages a
corresponding spline on the tubular shaft 120, while the inner
diameter of the hub 124 is splined and engages a corresponding
spline on the central shaft 118. The provision of the separate,
metal hubs minimizes the weight of the flywheels, while at the same
time, through the splined interfaces, provides sufficient strength
to withstand the shear loadings between the shafts 118, 120 and the
resinous hub portion 111 of the flywheels 52, 54, during transfer
of kinetic energy to and from the flywheels, as will be further
apparent from a later description of the mode of operation of the
present regenerative braking system.
[0070] The lower end of the central shaft 118 is journaled relative
to the lower containment device cover 74 by a ball bearing 128,
which is vertically positioned relative to the bottom cover 74 by a
snap ring 130. The central shaft 118 extends through and to the
upper end of the tubular shaft 120 and is journaled relative
thereto by an upper ball bearing 132 and a lower ball bearing 134.
The bearing 132 is supported by a shoulder 136, which projects into
the interior of the shaft 120. The bearing 134 is supported
relative to the shaft 120 by a snap ring 138 mounted on the
interior of the shaft 120. The tubular shaft 120 is then journaled
relative to the upper, containment device cover 72 by a ball
bearing 140. The weight of the lower flywheel 52 is carried by a
snap ring 142, affixed to the central shaft 118, then by way of a
snap ring 144 at the upper end of the shaft 118, though the ball
bearing 132, to the tubular shaft 120 and then by way of a snap
ring 146, through the bearing 140 to the top cover 72. The upper
flywheel 54 is supported by a snap ring 148, on the tubular shaft
120, so that the weight of both flywheels, is carried through the
tubular shaft to the snap ring 146 and bearing 140 to the top
containment device cover 72. As previously described, the
containment device is part of the load carrying, chassis sub-system
of the electric car 30, so that the weight of the flywheels is thus
integrated into and carried by the chassis or load carrying
structure of the electric car 30.
[0071] The bearings 128, 132, and 140 may serve the function of
providing a seal between the shafts 118, 120 and the stationary
components of the containment device 68. The flywheels and the
electrical components thereon (later described) are thus protected
from dirt, dust, road splash, as well as oil from the overlying
lubrication chamber. Additionally, this sealed containment device
chamber may be evacuated by vacuum pump means (not illustrated) in
order to minimize windage losses of the flywheels, which attain
relatively high peripheral velocities, due to their large
diameters, even though the flywheels have relatively low rates of
rotation. The containment device must be of substantial dimensions
and weight in order to perform its containment function. The weight
penalty incident thereto is partially offset, since the strength of
its components then has the capability of withstanding the stresses
involved where the interior of the containment device is evacuated
to minimize windage losses.
[0072] Reference is next made to FIG. 17 for a description of the
electrical components of the flywheels 52, 54. The battery arrays,
48, 50 each comprise a plurality of voltaic cells 150, which are
mounted in the compartments 112, 114 of the flywheels 52, 54. It
has been shown that operating at high voltage levels yields
superior performance characteristics, particularly in providing
greater power output for a given weight of electric motor. To this
end it is preferable that the voltaic cells in each of the
compartments, 112, 114 be connected in series, and then the cells
of each compartment 112, 114 are connected in series by conductors
152, 153. The electric circuit for the flywheel 52 comprises
conductors 154, 156 across which the potential of the battery array
48 is generated. The electric circuit for the flywheel 54 then
comprises conductors 158, 160 across which the potential of the
battery array 50 is generated. The battery arrays 48, 50 are then
connected in series (by means later described) to the end of
providing a voltage potential across conductors 154 and 162, which
is the sum of the several voltaic cells on the flywheels 52, 54.
?(claim)
[0073] The voltaic cells can take many different forms. Essentially
any voltaic cell chemistry can be employed. Conventional lead-acid
cells are suitable. In today's state of technology development, the
absorbed glass mat form of lead-acid battery offers the advantage
of eliminating acid in its free liquid form, as above discussed.
The absorbed glass mat battery has the further advantage of there
being preexisting facilities for the controlled disposal of spent,
lead based batteries in a manner that guards against pollution.
Present state of the art batteries, representatively nickel-metal
hydride give superior performance, providing superior performance,
i.e., more storage capacity and kilowatt output per pound of
battery weight than the lead acid type, but are not yet seen as
being economically competitive. Although presently quite expensive,
lithium polymer batteries give promise of even better performance,
and also eliminate the disadvantage of a liquid electrolyte, which
complicates the challenge of containment in a high G environment.
The point is that any improvement in voltaic cell technology should
be capable of use in the counter-rotating flywheels of the present
invention.
[0074] It has been demonstrated that alternating current motors and
alternating current generators (alternators) provide better
efficiencies than their direct current counterparts. This fact
dictated the selection of the alternator 62 as a current generator
and the selection an alternating current motor 42.
[0075] An inverter/rectifier 164 provides a current conducting
interface between these alternate current components and the direct
current battery arrays 48, 50. This component, when functioning as
a means to provide an alternating current source, is referenced as
inverter 164. The same component, when functioning to provide
direct current in recharging the battery arrays 48, 50, is referred
to as rectifier 164. The motor 42 is connected to the
inverter/rectifier 164 so that the direct current potential of the
battery arrays 48, 50 may be converted to an alternating current
input that powers the motor 42. Similarly, the alternating current
output of the alternator 62 is converted into a direct current
input for recharging the battery arrays 48, 50.
[0076] The components for conducting current between the
motor/alternator/inverter and the flywheel battery arrays, include
an interconnected, negatively biased, grounding circuit comprising
a motor grounding conductor 166, an alternator grounding connector
168 and an inverter/rectifier grounding conductor 170. Similarly,
the motor 42 has a positive input connector 172 which is connected
to the alternating current output of the inverter 164. The
alternator 62 has a positive conductor 174 providing a positive
input to the rectifier 164. The inverter/rectifier 164 has a
positive output/input conductor 176. The battery arrays 48, 50 are
then connected across the negative terminal conductor 170 and its
positive terminal conductor 176 in the fashion now to be
described.
[0077] Current flow to and from the flywheel mounted, battery
arrays is provided by circumferential "rails" on the flywheels 52,
54, which are engaged by "shoes" that are mounted on the
containment device casing 70 (structurally shown in FIGS. 11-16).
In a broader sense, the "shoes" are relatively fixed conductors
that conduct current to and from the rotating, conductive "rails".
These components comprise a portion of common conductor means
employed in energizing the motor 42 as well as in recharging the
battery arrays 48, 50. Thus the electrical circuit between the
inverter/rectifier 164 and the battery arrays 48, 50, comprises the
ground conductor 170, which electrically connects to the lower
flywheel 52 by way of a conductive shoe 178, riding on a rail 180.
The electrical circuit continues, by way of conductor 154, to the
battery array 48. Conductor 156, having a potential which is the
sum of the several voltaic cells in battery array 48, then connects
to a rail 182 which is also mounted on the lower flywheel 52.
[0078] The battery array 48 is then placed in series with the
battery array 50, by way of conductive shoe 184, which rides on the
rail 182. The electrical circuit continues to the upper flywheel 54
by way of a conductor 186 to a shoe 188 which engages a rail 190
that is disposed circumferentially of the upper flywheel 54; then
to conductor 158, through the battery array 50 to conductor 162,
rail 192 and shoe 194 to complete the circuit to the positive side
of the in put/output conductor 176.
[0079] The structure of the shoe and rail connections to the
flywheels 52, 54 will be further described with reference to FIGS.
11-16. Each of the shoes is mounted, respectively, in radial
alignment (relative to the flywheel) with the conductive rail which
it engages. Each shoe has a circumferentially elongated, rail
engaging portion a (FIGS. 11, 15) and a stem portion b which is
slidably mounted in a dielectric tube 196, which, in turn, is
mounted on a plate 198. Openings 200 are provided in the
containment device casing 70 for each of the shoes. The openings
200 are angularly and vertically offset to minimize the diminution
of strength caused by the openings. The conductive shoes are
positioned to engage the respective rails, by the plates 198 which
are secured to the casing 70 by screws 202. The shoes are
yieldingly maintained in engagement with the respective rails by
springs 204 acting between the outer end of the stems b and a cap
206 threaded on the outer end of each of the tubes 196. The tubes
196 are provided with flanges 208, which capture the spring loaded
shoes in the space between the plates 198 and the flywheels.
Additional means, not shown, can be provided to prevent rotation of
the shoes and thus maintain the elongated portions a in alignment
with the rails.
[0080] The described use of relatively fixed shoes engaging
rotating rails enables current to be efficiently conducted to and
from the flywheel mounted battery packs 48, 50, with a minimum of
losses due to generation of extraneous eddy currents. This
advantage is primarily attributed to the minimization of rotating,
flywheel carried conductors which could interact with stationary
conductive components to generate eddy currents which would
represent system energy losses. More important, the minimization of
flywheel conductors minimizes the generation of eddy current losses
by reason of their counter rotational, relative movement.
[0081] Excepting FIG. 16, showing the connection between conductor
162 and rail 192 and the illustrations of the shoes and rails in
several Figs., the electrical connections to and from the battery
means carried by the flywheels are shown only diagrammatically in
the drawings. The inverter/rectifier 164, in theory, could be
located in many different locations on the chassis of the car 30,
since it requires only electrical conductor connections to the
conductive shoes on the containment casing 70 and to the motor 42
and the alternator 62 as well as control signal means that will
later be described.
[0082] However, the inverter/rectifier can most advantageously be
mounted beneath one of the seats of the car, preferably the right,
passenger seat 38 (FIGS. 1-3). To this end a compartment 210 is
defined in part by a bracket 212 secured to the containment device
68 by bolts 80 that also secure the flange 78 of the upper cover
72. The compartment 210 is also defined by a lower plate 214 that
is supported on the upper surface of the flange 78 of the lower
cover 74, as well as by the upper surface of the chassis bar 98.
The plate 214 may extend forwardly to form the floor board of the
occupant compartment. A plate 216, also supported by the chassis
bar 98, as well as by the plate 214, and secured to the containment
device 68 by screws 218, defines the forward portion of the
compartment 210, as well as the rear of the occupant compartment,
beneath the right hand seat 38. The upper extent of the compartment
210 is defined by a plate 220 supported by the plate 216 and the
bracket 212. The compartment is closed by a side plate 222 that is
secured by screws or other readily removable means to provide
access to the inverter/rectifier 164 for maintenance and repair or
to set proper timing for signal generating parameters that are
later discussed.
[0083] Even though the battery means employed in powering the
electric car 30 are constantly being recharged (either during
regenerative braking, or at external recharging stations), they
have a finite operating life. The operating life can be extended by
establishing vehicle operating cycles that minimize the extent to
which the battery is discharged (preferably maintaining the charge
above 50% of the total battery capacity). Even so, the battery
arrays 48, 50 will ultimately require replacement.
[0084] To facilitate such replacement, the flywheels are mounted in
a fashion which enables them to be readily removed and
replaced.
[0085] The first step would be for the car 30 to be elevated on a
lift, or otherwise positioned to provide ready access to the lower
portions of the containment device 68. As a preliminary to removing
the flywheels 52, 54, the four conductive shoe (178, 184, 188, 192)
assemblies are freed by first removing the screws 202 so that the
plates 198 can be freed from the casing 70 and the shoes withdrawn
through the respective openings 200.
[0086] The next step would be to remove all of the several bolts 80
that secure the bottom cover 74 to the casing 70, as well as the
lower two bolts 218 (FIG. 6), which secure the lower end of the
vertical plate 216. It is to be noted that the removed bolts 80,
also secure brackets 82, 84, and 92 to the containment device 68.
These brackets are connected by vertical portions that interconnect
them to corresponding bracket portions that are also connected to
the containment device 68 by other bolts 80 that connect the casing
70 to the upper cover 72. Since there are no dynamic stresses on
the auto during the changing of the flywheels, this partial
disconnection of chassis components does not adversely impact the
structural integrity of the car 30. (When these components are
later reconnected, the car is restored to full functional
strength.) The lower containment device cover 74 can now be removed
(it is simply slid off the bottom of shaft 118, as the cover is
lowered from the casing 70) to provide access to the interior of
the containment device and to the flywheel support components.
[0087] Power assists, or leverage devices will normally be required
to assist in removal and reinstallation of the flywheels 52, 54
inasmuch as each, advantageously weighs in the order of 300 pounds,
or more. This is to point out that it is an object of the invention
to carry all of the car's battery mass on the flywheels, in order
to obtain as much advantage as possible from the energy storage
capability of the flywheels. In order to maximize the battery mass
and the load carrying capacity/operating range of the car it is
desirable to maximize the weight of the batteries. This end also
involves employing a flywheel diameter that approximates the
lateral spacing between the car's wheels, which has the further
advantage of minimizing the "G" forces on the battery cells.
[0088] To digress for a moment, the preferred automobile
configuration for a two seated, commuter service cycle has a
flywheel diameter which approximates a four foot diameter, such
being the approximate lateral spacing between the rear wheels of
this type of car. It is also desirable, in a sub-compact
configuration, for the length and height dimensions be minimized,
in order to minimize gross vehicle weight, as well to minimize the
foot print (floor space) of the car, thereby permitting a greater
number of cars to be parked in a given area and permitting a
greater number of cars to travel on a given stretch of highway. The
compact configuration also enables the drag coefficient to be
reduced and thereby contribute to the overall efficiency of the
car.
[0089] These ends are facilitated by a containment device height
which enables the seats 36, 38 overlie, in part, the forward
portion of the containment device (or the forward portion of the
flywheels, should it develop that a containment device was not
required). It has been found that a flywheel height in the order of
5.5 inches can be employed in accomplishing these ends, which, in
turn, provides sufficient battery mass to provide a range/load
capacity capability which is at least comparable to today's battery
driven vehicles.
[0090] At this point, it will also be noted that the disposition of
the drive train 58, connecting the flywheels and the front wheels
34, overlying the containment device and extending between the
seats 36, 38 also contributes to the compactness of the car 30,
particularly in connection with its length, making possible a wheel
base length in the order of 76 inches.
[0091] Back to the task of replacing flywheels, their weight is
such that power assists will be required. Removal of the bottom
cover 74 provides the room necessary for use of power assists in
removal and replacement. Thus lifting means can be deployed to
raise the flywheel 52 (FIG. 7) so that the snap ring 142 can be
removed. The flywheel 52 is then removed by lowering it beneath the
containment device casing 70 so that it can be carried away on a
dolly or through the use of other appropriate means. Next, the
power assist means can be used to raise the flywheel 54 sufficient
for the ready removal of snap ring 148. The flywheel 54 can then be
lowered in a controlled fashion (by power assist means) downwardly
from the splined shaft 120, beneath the level of the casing 70 and
then laterally, on a dolly or the like. A new flywheel 54 can then
be mounted on the shaft 120, again being support by the snap ring
142. Similarly, a new flywheel 52 can be mounted on the lower,
splined end of the central shaft 118 and the snap ring 142 put back
in place to support the flywheel 52 in its operative position. The
removed bolts 80 and 218 can then be reused to return the
containment device/chassis components to their initial, assembled
relation.
[0092] Next to be described in additional detail is the power train
58, that is adapted to connect the battery mass flywheels 52, 54,
with the differential 44 and the drive wheels 34, having further
reference to FIGS. 6 and 7. Bevel gears 224, 226 are secured,
respectively, to the upper ends of the flywheel shafts 118, 120 and
mesh with a gear 228, that is mounted on a flywheel input/output
shaft 230. The shaft 230 is journaled on a pillow block 231. This
miter gear set is disposed in a sealed lubrication chamber defined
by a cylindrical housing 232, which is sealingly mounted in a
groove formed on an upper surface of the containment device's upper
cover 72. Clamping means (not shown) are provided to maintain the
housing 232 in place so that the integrity of this lubrication
chamber will be maintained during operation of the car 30. The
described flywheel shafts 118, 120 and miter gear set (224, 226,
228) and the journals therefor, provide means for rotating the
flywheels 52, 54 in opposite directions about a common vertical
axis. In addition to the ease of removal and reinstallation of the
flywheels 52, 54, the described construction has the further
advantage of facilitating operation of the miter gear set in a
closed, lubricating atmosphere, as lubrication provide within this
chamber is maintained therein to provide continuous lubrication for
the miter gear set at all times. In this connection, note that the
bearing 140, for the shaft 120, is of the grease sealing variety
and that the outer race of the bearing 140 is in sealing engagement
with the upper cover 72, so that there won't be any escape of
lubrication through or around the bearing 140.
[0093] The described shaft and gearing arrangement has the further
advantage of enabling ready replacement of these components. The
lubricating chamber housing 232 may removed to provide access to
the miter gear set. Note that this gear set and the housing 232 are
conveniently disposed in the cargo space immediately behind the
seats of the car. It will also be seen that a floor board 234, for
supporting items in the cargo space, need not be removed in order
to gain access to the miter gear set. Once access is had to the
miter gear set, a taper pin 236 may be removed to permit the upper
bevel gear 224 to be lifted off the shaft 118. A taper pin 238 can
then be removed, permitting gear 228 to be slid on its shaft 230,
outwardly of the vertical outline of the bevel gear 226. A set
screw 240 is then loosened, permitting the gear 226 to be removed
from the shaft 120. Thus it is possible to access the miter gear
set and repair or replace the miter gears, 224, 226 or 228 as the
need may arise.
[0094] Also, if the flywheels 52, 54 have been removed in the
fashion above described, the shafts 118, 120 and bearings 132, 134
can then be lifted as a unit from the top containment device cover
72. It will also be seen that, once the tapered pin 236 and set
screw 240 are removed, snap ring 146 can be removed, to permit the
assembly comprising shafts 118, 120 to be dropped through the
bottom of the containment device.
[0095] As an alternate to the previously described method of
removing the flywheels 52, 54, the lower containment cover 74 can
be removed as above as indicated. Then the shafts 118, 120 can be
freed from the gears 224, 226 by removal of the tapered pin 236 and
set screw 240. Once this is done, removal of the snap ring 146
frees the entire flywheel assembly, so it can be dropped from the
bottom of the containment device as a unit.
[0096] As discussed above, the bearing and its associated mounting
means function as a seal to prevent escape of lubricant from the
lubrication chamber for the miter gear set. This seal may be
enhanced by further sealing means to provide a hermetic seal at the
top of the containment device. Similarly the bearing 128 and its
associated mounting means alone or in combination with ancillary
provides a hermetic seal at the lower end of the containment
device. The containment device is thus a sealed chamber that is
maintained free of foreign matter and which may be effectively
evacuated to minimize windage losses.
[0097] Continuing with a description of the power train 58, the
variable transmission 66, mounted on the upper surface of the top
containment device cover 72, includes, at one end, a drive
connection with the input/output shaft 230 and, at its opposite
end, a drive connection with a second input/output shaft 242 that
is journaled on a pillow block 244. The shafts 230, 242 always
rotate in the same direction (either clockwise, or
counterclockwise). The shaft 242 will be the driving, or input
shaft to the transmission 66, when energy is transferred from the
wheels 34, through differential 44 to the flywheels 52, 54, in
order to decelerate the car. The shaft 230 becomes the driving
shaft providing a power input to the transmission 66, when energy
from the flywheels 52, 54 is being used to provide motive power for
the car and/or to drive the alternator 62.
[0098] The transmission 66 can take different forms, employing
various combinations of planetary gear/fluid transmissions,
variable pitch cone pulley drives and other variable speed forms of
power transmission. The transmission 66 is characterized by means
for varying the internal gearing and coupling means so that the
input shaft (230 or 242) speed will always be such that torque will
be transmitted to the output (230 or 242), as energy is transferred
to or from the flywheels. The transmission 66 needs also to be
characterized by means for selectively establishing either the
shaft 230, or the shaft 242, as the input shaft. In furtherance of
this last end, conductors 246, 248, connect control means in the
transmission 66 with a signal generator 250. The control means in
the transmission 66 is responsive to an energy recovery signal on
conductor 246 (also energy recovery signal 246) to shift the speed
ratios between the transmission shafts 230, 242 so as to establish
the shaft 230 as the drive shaft to the transmission when energy
from the flywheels is recaptured either by accelerating the car, or
by recharging the battery arrays 48, 50. The transmission 66 is
then responsive to a demand signal on conductor 248 to shift the
speed ratios between the transmission shafts 230, 242 so as to
establish the shaft 242 as the driving shaft of the transmission,
when energy is transferred to the flywheels in decelerating the
car. It is also preferable that the control means for the
transmission 66, establish a speed differential, between the input
and output shaft of the transmission, which is proportional to the
strength of the energy recovery signal 246, or the strength of the
demand signal 248, as the case may be. The last mentioned
capability enables the rates of acceleration and deceleration to be
under an operator's control, as will be later discussed.
[0099] Continuing with a description of the power train 58, it
progresses from the transmission 66 to a gear train 253 comprising
gears 254, 256 and 258 (see also FIG. 3). The primary function of
this gear train is to permit the alternator 62 to be disposed at a
lower level and thereby minimize the intrusion of the regenerative
system components into the passenger compartment of the car 30. The
gear 254 is mounted on the transmission shaft 242, idler gear 256
is journaled by a shaft 260 on a bracket 262, that is secured to
the containment device 68. The lower gear 258 is mounted on a shaft
263 on the rear side of the clutch 64, which shaft is also
journaled on the bracket 262. The gear train 253 is enclosed in a
lubrication chamber defined in part by covers 268, 270. The forward
side of the clutch 64 is connected to the rotor 271 of the
alternator 62. The rotor 271, or the shaft therefor, is a load
carrying member of the power train between the differential 44 and
the flywheels 52, 54. The forward end of the alternator rotor shaft
271 is connected to the rear side of the clutch 60. The forward
side of the clutch 60 is then connected to a pinion 272 that meshes
with a bevel ring gear 274 of the differential 44.
[0100] The lower portions of the clutches 64, 60 and the alternator
62 may be partially extended through an opening 276 formed in the
floorboard 214, again for the purpose of minimizing the intrusion
of these components into the occupant compartment. The clutches 60,
64 and alternator 62 would also be appropriately supported from the
chassis of the car 30 by means not illustrated. A dust pan 278
underlies the floorboard 214 to seal the opening 276. A sound
absorbing shield 280 overlies the clutches and alternator to
minimize the noise level in the passenger compartment.
[0101] A controlling factor with respect to the dimensions of the
alternator is that it is desirable to maximize its diameter in
order that significant electrical generation can be had at
relatively low speeds. The end of maximizing electricity generation
is also facilitated by stepping the speed of rotation up from the
ring gear 274 to the pinion 272. The gear train 258, 256, 254 can
have the further function of stepping the input speed to the
transmission 66 to a lower level in order to minimize the velocity
ratios across the transmission 66 in maintaining the operating
speed of the battery mass flywheels 52, 54 at a safe, relatively
low level.
[0102] The drive connection (43) from the motor 42 to the
differential 44 is made by way of a pinion 282 (FIG. 5), on the
motor's output shaft, which meshes with a circumferential helical
gear 284 on the periphery of the ring gear 274 of the differential.
With this arrangement, a drive input from the flywheels and a drive
input from the motor 42 may be integrated in providing a power
output to the front wheels 34. Power from the motor and/or the from
the flywheels can thus be delivered to the wheels 34 in essentially
the same fashion as conventional front wheel drives presently known
in the automobile art, with a substantial increase in peak
acceleration.
[0103] The invention will now be further explained by a description
of the various operating modes of the electric car 30, looking
first to FIG. 17 in order to complete a description of the means
for generating signals that control energizing of the motor 42 and
flow of energy to and from the flywheels 52, 54 in the regenerative
braking of the car 30.
[0104] The power demand pedal 56, when depressed, transmits a
demand signal, either mechanical or electrical) through line a 286
(also reference as a power demand signal 286) to the signal
generator 250. This demand input provides the previously referenced
energy recovery signal that is transmitted through line 246 (also
signal 246) to the transmission 66 and establishes shaft 230 as the
driving shaft for transmission of kinetic energy from the flywheels
52, 54 through the alternator 62 and then to the differential 44,
in providing motive power input to the front wheels 34, when there
is rotational energy in the flywheels 52, 54. The demand signal 286
to the signal generator 250 also results in the generation of an
energizing signal that is carried on line 288 to a motor controller
290, which, in turn, energizes the motor 42 from the alternating
current provided through inverter 146 and provides a power input to
the differential 44. There are thus two potential sources of motive
power for operation of the car, namely battery power from the
arrays 48, 50 and, when available, motive power from the flywheels
52, 54.
[0105] The brake pedal 57, when depressed, provides a braking
demand signal, that is transmitted through line 292 (also signal
292), to the signal generator 250. The signal generator then
generates a flywheel braking signal that is transmitted through
line 248 (also signal 248) to the transmission 66. In response to
this braking signal, the shaft 242 becomes the driving shaft for
the transmission 66 so that the energy can be transmitted to the
flywheels 52, 54 from the differential 44 and the front wheels 34,
to thereby decelerate the car 30.
[0106] The clutches 60, 64, which are normally disengaged, may be
engaged in response to a signals that are transmitted from the
signal generator 250, by way of lines 294, 296, respectively. These
clutching signals are generated in response to operating conditions
that will be referenced in the following description of the several
operating modes of the car 30.
[0107] Initial, or cruise, operation of the car 30 is illustrated
in FIG. 18, at a time when the flywheels are at rest. Motive
operation of the car is initiated and maintained by
depression/pivoting of the power demand pedal 56 from its rest
position (indicated by broken lines). Such displacement results in
a power demand signal being transmitted to the signal generator 250
by way of line 286 (for sake of convenience, signals may simply be
referenced by the reference character which, more precisely
designates the line or conductor transmitting the signal). This, in
turn, generates an output signal 288 the strength of which is
proportional to the degree to which the pedal 56 is displaced. The
signal on line 288 actuates the controller 290 to the end of
energizing the motor 42 (from the inverter 164) at a power level
which is proportionate to the extent to which the pedal 56 is
displaced.
[0108] If operator pressure on the pedal 56 is released, it returns
to its rest position, thereby terminating the power demand signal
to the signal generator 250. Whereupon the energizing circuit for
the motor 42 will be terminated. The car is then essentially in a
freewheeling state and will begin to decelerate, assuming that it
is not on a down grade.
[0109] The initial state of controlled deceleration may be
initiated by a first incremental depression of the brake pedal 57
from its rest position (illustrated in broken lines), reference
FIG. 19. At this point it will be noted that there is a flywheel
speed signal input 308 to the signal generator 250. Whenever
flywheel speed is below a predetermined value (indicating that
there is little or no energy in the flywheel) signal 308 causes a
flywheel braking signal 248 to set the transmission 66 for the
transfer of energy to the flywheels 52, 54. Thus in sequencing from
the cruising state of FIG. 18 to the flywheel braking state of FIG.
19, flywheel braking is invoked, when energizing signals 294, 296
(generated in response to brake signal 292) cause clutches 60, 64
to be engaged. The power train 58 from the differential 44 to the
flywheels 52, 54 is thus established so that there is a transfer of
kinetic energy to the flywheels 52, 54 to thereby effect the
initial deceleration of the auto 30.
[0110] Further depression of the brake pedal 57, beyond an initial
increment of movement, indicates a demand for more rapid
deceleration, and causes generation of a field excitation signal
297 (FIG. 20) for the alternator 62, to the end that kinetic energy
of the car's movement is also transformed into electrical energy,
as the current generated by the alternator is fed by way of
conductor 174 to rectifier 164 then employed to recharge the
battery arrays 48, 50.
[0111] The flywheels 52, 54 are, in fact, an energy reservoir. They
have a finite, energy storage capacity, which is defined by their
mass and physical dimensions, and more important, by their maximum,
safe rotational speed. Once that speed has been reached, further
deceleration energy cannot be transferred to the flywheels, without
incurring an increased risk and ultimately, a certainty of the
structural failure of the flywheels. Once the maximum safe speed
has been reached, further deceleration of the car 30 must be had by
means of alternator braking or friction braking.
[0112] The flywheel speed signal 308 (FIG. 20A), as indicated
above, is provided as an input to the signal generator 250.
Responsive to the signal 308 indicating that the flywheels 52, 54
have reached their maximum safe operating speed, the energizing
signal 296 for clutch 64 is terminated. The clutch 64 is disengaged
so that there can be no further transfer of kinetic energy to the
flywheels. When the flywheels reach their maximum safe operating
speed brake pedal 57 is, of course, depressed and clutch 60 remains
in its engaged state so that the alternator 62 continues to be
drivingly connected to the differential 44. At the same time (if it
has not already occurred by depression of the pedal 57 beyond its
initial increment of movement) a field excitation signal 297 will
be provided by the signal generator to energize the alternator 62
so that regenerative braking is then provided, as kinetic energy is
transformed to electrical energy by recharging the battery arrays
48, 50. There can thus be a seamless changeover from flywheel
braking to alternator braking. If, at the time the maximum safe
operating speed for the flywheels is reached, flywheel/alternator
braking (FIG. 20) has been invoked, the alternator braking will be
continued, but, with the loss of flywheel braking, it is likely
that the desired rate of deceleration will not be achieved.
Increasing pressure on and displacement of the brake pedal, will
then invoke friction braking in the fashion next to be
described.
[0113] Reference is made to FIG. 21 for a description of the
friction braking means of the present invention. The friction
braking elements, which may be of conventional design and
construction, are diagrammatically illustrated by a brake shoe 298
which is engageable with a brake drum 300 (there being braking
elements for each wheel in the usual vehicle). A hydraulic control
system 302 is adapted to be responsive to displacement of the brake
pedal 57 to bring the brake shoe 298 into frictional engagement
with the drum 300.
[0114] When the rate of deceleration provided by
flywheel/alternator deceleration is insufficient, particularly
illustrated by the necessity for a panic stop, continued
displacement of the brake pedal 57 brings it to an extreme position
in which a switch 304 is engaged. This engagement provides a signal
input, on line 306 which actuates the hydraulic control system 302.
Thus there can also be a seamless transition from flywheel,
alternator braking to friction braking. At any time, either of
these regenerative forms of braking fails to provide a desired rate
of deceleration, there will be an intuitive continued pressure on
the pedal 57 which will result in closure of the switch 304 and
actuation of the friction braking system.
[0115] In response to actuation of the friction braking system, the
signal on line 294 is terminated, thereby disengaging the clutch
64. The friction braking system and the alternator braking system
thus combine to decelerate the car. Once the hydraulic system is
actuated, the pressure of the braking pad 298 on the drum 300 is
directly proportional to the degree of displacement of the pedal
57, in response to a signal input by way of line 311, to the
hydraulic system 302. In the event of the need for a panic stop, a
person's reflexes will maintain the pedal in its position of
maximum displacement and the car will literally come to a
screeching halt. Otherwise, pressure on the brake pedal will be
reduced, reducing the extent to which the pedal is displaced,
resulting in a reduced pressure on the pad 298 to obtain
deceleration a desired, controlled rate rather than initiating a
panic stop. The transition from flywheel braking to friction
braking can thus be essential seamless.
[0116] It is to be noted that once friction braking has been
invoked, it is preferable that this mode of braking be maintained
in effect until the brake pedal is released to its rest position,
indicating at least a temporary end of the need for reducing the
velocity of the car. To this end, a feedback signal is provided
through line 312, to the signal generator 250, indicating that the
friction braking mode is in operation. The signal generator
includes means, for generating a hydraulic lock-in signal 310 for
continuing actuation of the hydraulic control system 302. Release
of the brake pedal 57 transmits a signal by way of line 292 to the
signal generator 250, to indicate termination of a demand for
deceleration of the car.
[0117] If, when friction braking is terminated (by release of pedal
57), flywheel speed is too high to permit transfer of a significant
quantum of energy thereto, friction braking is maintained as the
primary braking mode. The maximum flywheel speed at which flywheel
braking can be invoked is arbitrarily set at say 90% of maximum
safe operating speed. Thus, if at the time of a brake signal 292 is
terminated, there is a flywheel speed signal 308 indicating a
flywheel speed in excess of 90% of maximum safe operating speed,
the signal generator 250 will maintain the hydraulic lock-in signal
310. The hydraulic system 302 will then be responsive to any
subsequent displacement of the brake pedal 57 to invoke friction
braking.
[0118] After release of the brake pedal 57, the hydraulic lock-in
signal 310 will be terminated whenever the flywheel speed signal
indicates to the signal generator 250 that flywheel speed has
dropped below 90% of maximum safe operating speed or whatever speed
is selected as being sufficient to permit significant flywheel
braking capability.
[0119] The flywheel braking structure and alternator braking
structure provide a large degree of flexibility in the returning of
braking energy to the overall energy system of a car. As described,
when friction braking is invoked, alternator braking is maintained
in effect and a portion of braking energy continues to be
recaptured through recharging of the battery arrays 48, 50.
Alternatively, the signal generator 250 can be programed to be
responsive to a flywheel overspe ed signal 308 to prevent further
transfer of energy to the flywheels by terminating the signal 294
to disengage the clutch 60. Thus, during friction braking, flywheel
energy can be recaptured as chemical energy by maintaining the
engaging signal 296 for the clutch 64 and the excitation signal 297
thereby to recharge the battery arrays 48, 50.
[0120] It is preferred that braking energy, transferred to the
flywheels 52, 54, be returned to the energy system of the car 30 in
response to the next subsequent power demand signal 286, as is
illustrated in FIGS. 22 and 23. The availability of flywheel energy
is indicated by the speed signal 308 to the signal generator 250,
which then provides an energy recovery signal 246 to the
transmission 66. When the power demand pedal 56 is depressed, the
signal generator 250, in response to demand signal 286, sets the
strength of the signal 246 proportionate to the extent to which the
pedal 56 is displaced, thereby setting the speed ratio of the
transmission in proportionate fashion. Energization signals 294,
296 also cause the clutches 60, 64 to be engaged. Note, that shaft
230 may already have been set as the drive shaft and clutch 64
engaged, by reason of a prior invoking of friction braking, as
discussed above. Simultaneously the signal generator 250 provides
an energizing signal on line 294, causing the clutch 60 to be
engaged. There is thus provided a motive power input from the
flywheels to the differential 44 and the drive wheels 34, thereby
returning the stored braking energy as motive power for the
car.
[0121] FIG. 23 illustrates the more likely mode of flywheel energy
recovery wherein both flywheel energy and battery energy are
employed in reaccelerating the car 30. In this fashion more rapid
rates of acceleration can be attained, thereby making this
alternative energy source more commercially attractive.
Additionally, the flywheel power assist minimizes the rate of
current drain from the batteries and thereby decreases the rate of
battery discharge and contributes to longer battery life.
[0122] The mode of flywheel reacceleration illustrated in FIG. 22
is initiated by a first incremental displacement of the power
demand pedal 56. In FIG. 23, the pedal 56 has been displaced beyond
that first increment of movement. In response thereto, the signal
generator 250 provides an output signal (288) actuating the motor
control 290 and energizing the motor 80 to provide a power input to
the differential 44. The flywheels are also drivingly connected to
the differential 44 as before described. The differential 44 then
acts as a mechanical integrator to combine the power inputs from
the flywheels and the motor in reaccelerating the car 30.
[0123] When all, or substantially all of the kinetic energy has
been recaptured in powering the car, as reflected by the flywheel
speed signal (308), the signal generator 250 has means, responsive
thereto, for canceling the clutch energizing signals (294, 296)
whereupon the clutches 60, 64 disengage and operation of the car
reverts to the cruising mode illustrated and discussed in
connection with FIG. 18.
[0124] The described regenerative system is optimized to first
convert car kinetic energy to flywheel rotational energy and then
to recapture flywheel energy as motive energy. Secondarily car
kinetic energy is converted to electrical energy. In recapturing
braking energy it is likewise preferred to recapture flywheel
energy by using it to power motive operation of the car. When the
car goes out of service, i.e., the "ignition" is turned off, any
energy remaining in the flywheels is employed to recharge the
batteries, as will be later be described in connection with a
further embodiment of the invention.
[0125] These priorities ?(claim) minimize the number and extent of
battery charging-discharging cycles, and thus significantly prolong
battery life of lead-acid batteries, all to the end of making
battery powered cars more economically attractive. Another factor
that leads to the preference of transferring kinetic energy to the
flywheels and then recovering this braking energy in powering the
car, is that the rate of recovery of energy by recharging lead-acid
is relatively limited, particularly in that the amount of energy
that can be recovered in a given length of time is limited by the
nature of the chemical process that is involved.
[0126] It is to be recognized that the same basic, series related
components, i.e., flywheels, a bi-directional, variable
transmission, a first clutch, an alternator, a second clutch, and a
car transmission connection (differential 44) could be otherwise
programmed to minimize the transmission of power to and from the
flywheels. Such an approach would be attractive when using
batteries that could be more efficiently recharged. Super
capacitors hold promise for the more effective recharging of
lead-acid batteries. Also other battery chemistries have the
potential for more efficient recharging that could lead to a
greater reliance on recapturing braking energy in the
batteries.
[0127] To accomplish this alternate end first using the batteries
as the primary reservoir for braking energy, the clutch 60 would be
first engaged to drive the alternator. Alternator braking would
thus be the first form of regenerative braking. The clutch 64 would
be secondarily engaged to provide additional regenerative braking
by transferring energy to the flywheels. Further, the alternator 62
would be maintained in an energized state whenever possible, to
convert the maximum possible amount of flywheel energy to
electrical energy, rather than attempting to return it to the
system as motive power. ?(claim)
[0128] Another option would be to program the signal generator 250
so that only a portion of flywheel energy would be employed in the
reacceleration of the car. This has the disadvantage of reducing
the energy reservoir of the flywheels that would be available for a
subsequent braking action. But by reserving energy in the
flywheels, it is possible to assure that there will be a
substantial power assist for the motor 42 should there be a need
for a subsequent reacceleration before additional braking energy
has been transferred to the flywheels. The need for, and
desirability of, a flywheel power assist goes to the fact that
there is a limitation on the rate at which current can be drawn
from the battery arrays 48, 50 to power the motor. Additionally,
battery life is adversely impacted as the rate of battery discharge
is increased to power acceleration of a car a rate sufficient for
safety purposes, as well as sufficient to satisfy demands of the
market place. Thus having the ability to supplement acceleration of
the car by means of flywheel energy is desirable as frequently as
possible.
[0129] It will be apparent that the foregoing described flywheels
and alternator and the manner in which they cooperate in
decelerating the vehicle, function as a regenerative system for
recovering energy that would otherwise be lost if reliance were had
solely on friction braking for deceleration. It will also be
apparent to those skilled in the art that such a regenerative
system can recover other energy that is normally lost in the
operation of a vehicle. This point is exemplified by regenerative
systems that recover energy that is normally lost in shock
absorbers by converting such energy into electrical energy.
Illustrative of such regenerative systems are U.S. Pat. Nos.
3,861,487 and 4,387,781. Another use of such a regenerative system
would be in a fork lift vehicle where the energy of resisting
lowering of a load could be converted to flywheel wheel energy and
electrical energy.
[0130] Reference is next made to FIGS. 24-32 for a description of
alternate embodiments of the invention in which the alternator, for
recharging the battery arrays and transforming flywheel energy into
electrical energy, is directly coupled to the flywheels to the end
that only a single clutch is employed, as opposed to the two
clutches of the previous embodiment. These alternate embodiments
have the further advantage of simplifying the drive train (58')
between the differential 44 and the flywheels 52, 54, thereby
enabling the use of a shorter wheel base and/or a larger flywheel
diameter. Additionally the intrusion of regenerative system
components into the passenger chamber is minimized.
[0131] FIG. 27 provides a diagrammatic representation of the first
of these alternate embodiments, in which an alternator 62' is
adapted to be driven from the upper flywheel 54 of a car 30'. A
modified power train 58' differs from the power train 58 in the
omission of an alternator and the provision of only a single clutch
314 between the transmission 66 and the differential 44.
[0132] FIGS. 24 and 25 illustrate structure that may be employed in
providing a flywheel driven alternator. The alternator 62' may be
conveniently located in the right rear quadrant of the containment
device 68', being mounted on a bar 316, which, in turn, is mounted
on a modified rim 76' of the upper cover 72' of the containment
device. The rotor shaft 318 of this alternator extends through a
hole 320 in the bar 316 and then through a larger hole 322 in the
peripheral rim 76', which has also been modified, along with the
adjacent portion of the containment device casing 70' to provide
clearance for a roller 326. The roller 326 is secured to the lower
end of alternator shaft 318 and is drivingly engaged with a groove
327 in a circumferential rim 328 mounted on the upper surface of
the flywheel 54 for rotation therewith. The alternator 62' is thus
driven directly from the flywheel 54 at all times.
[0133] The alternator 62' is responsive to a field excitation
signal 329 from the signal generator 250 to generate electricity,
which is fed to the rectifier 164 by way of conductor 174 and
employed to recharge the battery arrays 48, 50 in the same fashion
as the alternator 62' (FIG. 27).
[0134] The alternator mounting bar 316 (FIGS. 23 and 24) rests on
the rim 76' and is pivotally secured thereto, at one end, by a
shoulder screw 330. The opposite end of the bar 316 is secured to
the rim 76' by a screw 332, which extends through a slot 334 in the
bar 316 and is threaded into the cover rim 76'. With this
arrangement the bar 316 can be angularly positioned relative to the
top cover 72' to bring the roller 326 into and out of driven
engagement with the flywheel rim 328. Additionally, the roller 326
can be swung clear of the rim 328 to allow the flywheels to be
removed downwardly for maintenance and repair, as described above
in connection with the first embodiment. Also the alternator 62'
can be removed for maintenance and repair simply by removal of the
screws 330, 332. The opening 322 is large enough for the roller 326
to pass through it so that the alternator 62' can may be
independently removed for replacement or repair. It is noted that
the top cover 72' and the casing 70' are the only components of the
containment device housing 68' that require modification in order
for the generator to be driven from the flywheel system.
[0135] Reference is made to FIG. 26 for a further description of
the power train 58'. Where there had formerly been two clutches and
an alternator between the flywheel containment device 58 and the
differential 44, there is now but the single clutch 314. When the
clutch 314 is engaged, braking energy can be transferred to the
flywheels 52, 54 or returned as motive energy to the differential
44 through pinion 272, dependent on the control signals (246, 248)
to the variable ratio transmission 66, as previously described.
[0136] The modified power train 58' reduces intrusion of the
regenerative system into the occupant compartment of the car. This
is to point out that, with only the need to protect the single
clutch 314, the profile of the shield 280' may be lowered.
[0137] Other than the described changes incident relocating the
alternator so that it is directly driven from the flywheel 54, car
60' may include the several features described in connection with
car 30 of the first embodiment.
[0138] FIGS. 28-31 illustrate a variation in which the alternator
means are integrated with the flywheel means of a car 30''. In this
embodiment, alternator 62'' comprise a magnetic component 338
mounted on the upper flywheel 54 and a field component 340 mounted
on the top cover 72 of the containment device 68. Whenever there is
rotation of the flywheels, there will be relative rotation between
the components 338, 340. A field excitation signal 329 may be
selectively provided from the signal generator 250 to the field
component 340 to generate electricity, which may then be fed to the
rectifier 164, for the purpose of recharging the battery arrays 48,
50 in the same fashion as the alternators 62 and 62'.
[0139] FIG. 32 illustrates a variation of the last described
embodiment. In this embodiment, alternator 62''' likewise comprises
a magnet component 338 mounted on the upper flywheel 54, but
differs in that field coil component 340' is in circumferential,
outwardly spaced relation to the magnet 338. As with alternators
62'' and 62''', a field excitation signal 329 is selectively
generated when it is desired to actuate the alternator and generate
current which is then fed by conductor 174 to the rectifier 174 for
purposes of recharging the battery arrays 48, 50. As presently
contemplated, the circumferential spacing of FIG. 32 is preferred
in that the spacing is less subject to variation because of the
jolting to which the flywheels will be subjected when the car hits
a pot hole or the like. Therefore the alternator 62''' can operate
with a relatively high efficiency.
[0140] From a structural standpoint, the regenerative braking
system of car 30'' may be the same as for car 30' differing only in
the changes incident to eliminating the alternator as a separate
component and then incorporating the alternator functions into the
upper flywheel 54 and the containment device 68'.
[0141] The flywheel driven (FIG. 27) and flywheel integrated (FIGS.
28, 32) alternators have the advantage of being driven, or
operating from a relatively large radius so that a relatively high
efficiency can be obtained with a minimum of alternator component
weight. Even at relatively low flywheel speeds, the alternator
speed will be sufficiently high for efficient generation of
electricity. While the multiplication factor of flywheel rim
diameter to roller diameter is absent from the flywheel integrated
alternators (62'' 62''') nonetheless the working diameter of the
generating elements approximates 48 inches and greatly enhances the
efficiency of electrical generation.
[0142] The high peripheral speeds of the flywheel mounted magnet
component 338, as well as the high rotor speeds of the flywheel
driven alternator lead to the advantageous provision of multiple
field winding components for the alternator. FIG. 29A illustrates
this feature. The alternator 62'' is provided with a second field
winding component 340a, which cooperates with a second, flywheel
mounted magnetic component 338a (a single flywheel mounted magnetic
component could suffice). At relatively low flywheel speeds, a
second field excitation signal 329a can be provided to the field
winding component 340a to more efficiently generate electricity,
which is fed by conductor 149a to the rectifier 164 and recharge
the battery arrays 48, 50. The field winding component 338a, when
actuated, also increases the rate at which kinetic energy is
transformed into electrical energy and may be actuated for that
purpose to provide an increased deceleration affect, and/or to more
rapidly restore the flywheels' capacity to provide a braking
action.
[0143] Third and fourth field winding components could be employed
in the same way to further enhance the efficiency of electrical
generation over the wide range of peripheral speeds of the
flywheels. The flywheel driven alternator 62' (FIG. 27) could
similarly provided with multiple, independently actuated field
windings, or the equivalent effect could be obtained by the
provision of one, or more, additional, flywheel driven alternators,
which could be independently actuated.
[0144] The flywheel driven alternator 62' and the flywheel
integrated alternator (62'' or 62''') function in the same fashion,
in that electricity is generated only when there is rotation of the
flywheels and a field excitation signal is provided thereto.
Therefore, the power train 58' from the flywheels to the
differential can be the same for all of these embodiments. The
alternators 62', 62'' and 62''' are functionally identical, each
being responsive to a field excitation 329 to generate electricity
that then recharges the battery arrays, as previously described.
With this in mind the following description of FIGS. 27-32 will
suffice for a full understanding of the method of operation of each
of the three embodiments.
[0145] This functional equivalency is demonstrated by FIGS. 27 and
28, which, respectively, illustrate the cruising mode of operation
for cars 30' and 30'', in which electrical energy is recaptured by
alternators 62' and 62''. In the cruising mode, the demand pedal 56
is depressed to generate a demand signal input 286 to signal
generator 250' and a resultant signal 288 to the controller 290 for
the motor 42 whereby motor 42 is energized from the battery arrays
48, 50. The clutch 314 is disengaged and the flywheels (52, 54) are
at rest when these cars are first set into operation, this cruising
mode is the simplest form of operation. The alternator (62', 62''
or 62''') is at rest and there is no electrical input on line 174
to the rectifier 164. Cruise operation is simply the powering of
the car by the battery means (48, 50) physically located on the
flywheels, in the same fashion as in FIG. 18.
[0146] FIG. 29 illustrates flywheel/alternator braking modes in
which kinetic energy is transferred from the auto 30'' to the
battery arrays 48, 50 in the form of electrical energy and/or to
the flywheels in the form of rotative kinetic energy. Consistent
with the objective of minimizing battery discharge/recharge cycles,
the first invoked mode of regenerative braking would be flywheel
braking. This braking mode may be initiated by a depression of
brake pedal 57, to provide a braking signal 292 to the signal
generator 250 and a braking signal output 344, which causes
engagement of the clutch 314. Simultaneously, there is a flywheel
braking signal by way of line 248, which establishes shaft 242 as
the driving shaft for the transmission 66. The speed ratio (and
rate of power transmission) across the transmission 66 may be
proportionate to the extent of displacement of the brake pedal
57.
[0147] As in the first embodiment, a flywheel speed signal input
308 is provided to the signal generator 250''. As in the first
embodiment, it is desirable to increase the regenerative recapture
of energy by invoking alternator braking after flywheel braking has
transferred some substantial quantum of braking energy to the
flywheels. Thus at an intermediate flywheel speed, say 50% of
maximum safe flywheel speed, the speed signal 308 causes the signal
generator to provide a field excitation signal 329 to the
alternator 62', 62'' or 62'''. It will also be appreciated that, if
the flywheel speed signal 308, indicates such an intermediate (50%)
speed at the time the brake pedal is displaced, then signals 329
and 314 will both be provided by the signal generator 250' to
simultaneously invoke flywheel braking and alternator braking, as
depicted in FIG. 29.
[0148] The speed signal 308, when flywheel speed further approaches
maximum safe operating speed, say 75% of maximum safe operating
speed, can also be used to generate a further field excitation
signal 329a (FIG. 29A) to increase alternator braking to thereby
further increase alternator braking energy so that a greater extent
of regenerative braking can be had before the maximum safe
operating speed is reached.
[0149] It is to be appreciated that alternator braking is provided
in the car 30' in a fully equivalent fashion by the alternator 62'.
The signal generators of the cars 30' and 30'' may be essentially,
if not fully identical. Thus, in FIG. 27 the signal generator would
be responsive to flywheel speed signal inputs (308) to generate a
field excitation signal (329) so as to generate electricity that
flows through line 174 and rectifier 164 to recharge battery arrays
48, 50. Similarly, signal generator 250' would function in FIG. 27
to engage and disengage clutch 314 in the same fashion described in
connection with FIG. 29. This further demonstrates the functional
equivalency of alternators 62' and 62'',
[0150] Operation in the described fashion results in initial
regenerative braking being strictly the mechanical transfer of the
kinetic energy of car movement to flywheel rotation. Then, when
flywheel speed has reached a point where there has been a transfer
of some significant quantum of energy alternator braking is
additionally invoked to maximize the total regenerative recovery of
braking energy. Advantageously alternator braking would be invoked
when flywheel speed has reached a point where there is sufficient
flywheel energy to provided a meaningful energy assist for a
subsequent reacceleration of the car 30', 30'' (see above
discussion of maintaining an energy reserve for purpose of
assisting reacceleration).
[0151] If and when a higher rate of deceleration is desired,
through normal reflex reaction, the driver will depress the brake
further to a position where switch 304 will be closed to actuate
the friction braking mode illustrated in FIG. 30. The friction
braking mode of this embodiment may be essentially the same as, if
not identical with, the friction braking system described in
connection with the first embodiment. Accordingly the description
of FIG. 30 will be abbreviated.
[0152] Closure of switch 304, provides signal 306 that actuates the
hydraulic system 302. The position of the brake pedal 57, through
line 311, controls the rate of deceleration, through the amount of
pressure of brake pad 298 on brake drum 300.
[0153] Also, at the time the friction braking mode is actuated,
clutch signal 344 is terminated to the end that clutch 314 is
disengaged so that deceleration is solely through the friction
braking means. Also, as in the first embodiment, line 312 provides
a signal to hold-in circuit in the signal generator 250' that
results in a hydraulic actuation signal 310, which is maintained
until the brake pedal 57 returns to its rest position. Means are
also provided for preventing a subsequent clutch engagement signal
(344) until the brake pedal is released.
[0154] It will be appreciated that, when friction braking is
invoked, the field excitation signal 329 (and 329a) may be
maintained so that the alternator (62', 62'', or 62''') remain
energized and will continue to recapture flywheel energy by
recharging the battery arrays 48, 50. The signal generator may be
responsive to the speed signal 308 indicating that flywheel speed
is below an intermediate speed (reflecting a meaningful energy
reservoir, say 25% of maximum safe operating speed) to terminate
the field excitation signal 329 (and 329a). Thus, once there has
been some measure of friction braking, there will normally be a
reservoir of flywheel energy available to assist in reacceleration
of the car. This is a further option of flexibility provided by the
structure of the present invention, which is also available in
other embodiments herein.
[0155] Also, as in the first embodiment, the friction braking mode
will be actuated when the flywheels reach a speed where transfer of
further deceleration energy thereto would cause them to exceed a
safe operating speed. Thus the signal generator is also responsive
to signal 308, indicating that the flywheel speed has reached a
maximum safe operating speed, to generate a hydraulic system
actuation signal 310, whereby friction braking becomes effective,
in the fashion described above. At the same time the clutch
energizing signal 334 is terminated. Recovery of flywheel energy by
maintaining the field excitation signal 329 (and 329a) in effect,
is also provided for in the fashion above described. Again, there
is a hold-in signal 312 which maintains the friction braking mode
in effect until the brake pedal 57 is released to its rest
position.
[0156] These alternate embodiments of the alternator means (30',
30'', and 30''') also have an operating mode for recapturing
flywheel kinetic energy by using it to power the car (FIG. 31).
This mode is also essentially the same as described in connection
with the first embodiment. Thus, if the demand pedal 56 is
depressed when the flywheels are rotating, this flywheel energy
will be employed to provide a power assist for reacceleration of
the car. The existence of available flywheel energy is indicated to
the signal generator 250 by the speed signal 308. In response
thereto, a signal will be provided to line 246 of the transmission,
establishing shaft 230 as the drive input shaft for the
transmission 66. Also a clutch energization signal 344 will be
generated to cause the clutch 314 to be engaged, thereby providing
a motive power input from the fly wheels to the differential
44.
[0157] When the flywheel supplied power is insufficient, or
exhausted, signal generator 250' will generate signal 288 to
initiate energization of the motor 42, and the eventual return to a
straight cruising mode of operation, as the clutch 314 is
disengaged in response to the flywheel speed signal 308 being
reduced to a zero value, or a minimum operating speed value.
[0158] Reference is next made to FIGS. 33-40 for a description of a
car 30.sub.M/A which is further embodiment of the invention that
also enhances the reliance on kinetic energy interchange in a
regenerative braking system. Car 30.sub.M/A has many components
which may be the same as in previous embodiments and are identified
by like reference characters, without repeated, detailed
description.
[0159] Mobile support for the structural components of the car is
again provided by rear wheels 32 and front wheels 34. Battery
arrays 48, 50 are mounted on flywheels 52, 54 and are then
connected to inverter/rectifier 164 by a conductor 176.
[0160] A motor/alternator 350 has a bi-directional drive connection
352 to a mechanical integrator 354, which in turn has a drive
connection 356 to the differential 44 and then to the axles 46 and
the front wheels 34. (When the electrodynamic component 350 is its
motor mode, it will be referred to as motor 350 and, when in its
alternator mode, as alternator 350.) A flywheel drive connection
358 extends from the integrator 354 to one side of clutch 314. When
the clutch 314 is engaged, connection with the flywheels is then
made through power train 58'', which comprises the rotor of a
secondary alternator 62.sub.c, input/output shaft 242, variable
transmission 66 and input/output shaft 230 and then the geared
connection to the flywheels 52, 54. There is thus provided a
bidirectional drive connection between the flywheels 52, 54 and the
mechanical integrator 354.
[0161] The mechanical integrator 354 may take the form of
interconnected sun gear drives and infinitely variable drive means
which are selectively controlled so as to direct mechanical power
bidirectionally of each of the drive connections 352, 356 and 358.
The operative state of the mechanical integrator 354 is controlled
by a control signal input 360 from a mode signal generator 362. The
signal generator 362 receives a power delivery signal (364) or a
braking mode signal (365, 365' or 365'') from a signal generator
250'', which is responsive to signal inputs from the power demand
pedal 56 and the brake pedal 57 to control operation of the
mechanical integrator in the fashion now to be described.
[0162] Initial operation of car 30.sub.M/A is illustrated in FIG.
33. Displacement of the demand pedal 56 from its rest position,
provides a power demand signal 286 to the signal generator 250'',
which then provides three signal outputs: (a) a motor mode signal
368 to the motor/alternator 350 placing it in its motor mode of
operation; (b) an energizing signal 288 to controller switch 290,
thereby powering the motor 350 from the output of inverter 164; and
(c) a power delivery signal 364 to the integrator mode signal
generator 362. The resultant control signal 360 then places the
mechanical integrator in a mode of operation wherein power from the
motor 350 is directed through connections 352, mechanical
integrator 354 and drive connection 356 to the differential 44 to
provide motive power to the wheels for operation of the car
30.sub.M/A. The signal 288 may be proportional to the degree to
which the demand pedal 56 is displaced thus controlling the power
output of the motor 350 to achieve a desired speed. The car
30.sub.M/A in this initial state of operation is powered solely by
electrical energy from the flywheel mounted battery arrays 48,
50.
[0163] As in the previous embodiments, flywheel braking may be the
first form of braking to be invoked. When the energy storage
capacity of the flywheels, or the rate of energy transfer thereto
is insufficient to meet the desired rate of deceleration, the
alternator 350 then functions as a second regenerative braking
mechanism. When flywheel braking and alternator braking fail to
provide a desired rate of deceleration, then friction braking is
invoked.
[0164] FIG. 34 next illustrates flywheel braking. This deceleration
mode may be initiated by depression of the brake pedal 57 through a
first range of movement to provide a brake signal input 292 to the
signal generator 250''. This signal input terminates the motor mode
signal 368 to the motor 350 and the energizing signal 288 to the
controller switch 290. The signal generator 250'' is also
responsive to a brake signal input 292 to generate: (a) a
regenerative braking signal 365 which results in the flywheel drive
connection 358 of mechanical integrator 354 being driven by
differential drive connection 356; (b) an energizing signal 344 for
engaging the clutch 314; and (c) a flywheel braking signal 248
which sets the shaft 242 as the input drive shaft and shifts the
speed ratios of the transmission 66 to transmit power to the
flywheels at a rate proportionate to the degree to which the brake
pedal 57 is displaced. Thereupon, kinetic energy of forward motion
of the car 54 is transferred to the flywheels, and stored as
rotational energy, as the car 30.sub.M/A is decelerated.
[0165] The flywheels 52, 54 are reservoirs for the storage of
energy, and, as previously discussed, have a finite capacity, which
is defined by the maximum safe operating speed of the flywheels.
When this maximum safe operating speed is reached, deceleration
energy can no longer by safely transferred to the flywheels and
further regenerative braking is then obtained by alternator
braking.
[0166] These ends are obtained through the provision of a flywheel
speed signal generator 376 (FIG. 35) which may be mechanically
driven from the flywheel 52 to provide a flywheel speed signal
input 308 to the signal generator 250''. The signal generator 250''
may be responsive to the signal 308 reflecting a maximum safe
operating speed, to terminate the clutch energizing signal 344. The
clutch 314 returns to its disengaged condition as the flywheel
system is isolated from the drive system for the car. The energy of
deceleration is thus stored in the rotating flywheels 52, 54.
[0167] Assuming that the brake pedal 57 remains depressed
(indicating the need for further braking action) when the flywheels
reach a maximum safe speed, there will be a seamless transition to
alternator braking. To this end, the signal generator 250'' is also
responsive to a maximum safe operating speed signal 308 to generate
an alternator mode signal 369, which actuates the alternator mode
of the motor/alternator 350. At the same time, a modified,
regenerative braking signal 365' shifts the integrator 354 to an
operative state wherein alternator drive connection 352 is driven
by the differential connection 356 (FIG. 35). The alternator 350
thus serves to provide a braking function as kinetic energy of car
movement is transformed into electrical energy by powering the
alternator 350. The alternating current generated by the alternator
350 is carried by conductor 371 to the rectifier 164, and converted
to direct current and then returned to the energy system of the car
by being employed to recharge the battery arrays 48, 50.
[0168] Also in response to speed signal 308 indicating a maximum
allowable flywheel speed, the signal generator 250'' may terminate
the flywheel braking signal (248) input to the transmission 66 and
provide an energy recovery signal 246, which shifts the
transmission to an energy recovery mode in which power flow is
reversed. The flywheel system is thus placed in readiness for
recovery of deceleration energy stored in the flywheels.
[0169] When the need for deceleration terminates, the brake pedal
is released and returns to its rest position. The car is then in a
free wheeling state that can continue until one or the other of the
pedals 56, 57 is depressed.
[0170] Provision may also be made for a stronger, regenerative
braking action where flywheel braking and alternator braking are
combined to provide a maximized rate of regenerative deceleration.
This combined braking action (FIG. 36) may be initiated by
depression of the brake pedal 57 beyond the initial range of motion
(which initiated flywheel braking). Such displacement is sensed by
the signal generator 250'' through the signal 292 and results in
transmission of alternator mode signal 369, which switches the
motor/alternator 350 to its alternator mode of operation. At the
same time the signal generator 250 generates a modified braking
signal 365'' to provide a control signal 360 which causes the
integrator 354 to split the power from the differential drive
connection 356 between the alternator drive connection 352 and the
flywheel drive connection 358. The mode signal generator 362 may
have a flywheel speed signal input 388 (from signal generator 376).
Similarly an alternator speed signal input 392 (from an alternator
speed signal generator 290) may also be provided to the mode signal
generator 362. These speed signals modify the control signal 360 to
the end of assuring that there will be an effective and efficient
division of power input to the alternator 350 and to the flywheels
52, 54.
[0171] Thus, in addition to kinetic energy of car movement being
transferred to the flywheels, it is also transformed into
electrical energy as the alternator 350 is driven to generate
electricity, which is then fed back to rectifier means 164 by way
of conductor 371 thereby recharging the battery arrays 48, 50.
[0172] In order to maximize regenerative recapture of braking
energy, alternator braking can be additionally invoked after there
has been a substantial transfer of energy to the flywheels 52, 54.
This is to say that combined alternator/flywheel braking can be
automatically initiated after there has been a predetermined
transfer of braking energy to the flywheels. Thus, when the
flywheel speed signal 308 reaches a predetermined level, say 75% of
maximum safe operating speed (or that speed exists at the time the
brake pedal is depressed), the signal generator 250'' will transmit
the modified mode signal 365'', and initiate the alternator mode
signal 369, as the operative components of the system are brought
to the state illustrated in FIG. 36. In this fashion, the flywheels
52, 54 will first accumulate a relatively high quantum of energy
which can substantially assist in a subsequent reacceleration of
the car 30.sub.M/A, as is later explained in connection with FIG.
38. As the maximum safe operating speed is approached, speed inputs
388 and 392, to the mode signal generator 362 will enable a greater
proportion of braking energy to be transferred to the alternator
connection 352 so as to maximize the quantum of braking energy that
is recaptured.
[0173] If at any time during flywheel/alternator braking (FIG. 36),
the flywheels reach their safe maximum operating speed, the signal
input 308 to the signal generator 250'' will result in the flywheel
system being isolated from the drive system, as the signal 344 is
terminated and the clutch 314 is disengaged. Thereupon the signal
generator is response to provide the modified braking signal 350'
as alternator braking is invoked. In most cases, it is to be
expected that friction braking will also be required. This mode of
braking is next described with reference to FIG. 37.
[0174] When it is no longer possible to obtain a desired rate of
deceleration by way of alternator/flywheel braking, or in a panic
braking situation, continued pressure on the brake pedal 57 will
invoke friction braking in essentially the same fashion and using
the same components described in connection with the previous
embodiments of the invention.
[0175] Brake pedal 57 will engage and cause closure of switch 304,
providing a signal input, on line 306 which actuates the hydraulic
control system 302. Once the hydraulic system is actuated, the
pressure of the braking pad 298 on the drum 300 is directly
proportional to the degree of displacement of the pedal 57, in
response to a signal input by way of line 311, to the hydraulic
system 302.
[0176] In response to actuation of the friction braking system, the
signal on line 344 is terminated (if it has not already been
terminated), thereby disengaging the clutch 314, so that flywheel
braking, if otherwise available, is not relied upon in a panic
braking situation. However, in this embodiment, alternator braking
can be maintained during frictional deceleration, as the signal
input 365'' maintains the mechanical integrator 354 in a mode
wherein the drive connection 356, from the differential 44', is
directed to the connection 352, to provide a drive input for the
alternator 350. Thus, recapture of deceleration energy can be
maintained right up to the point where the car is brought to a
complete halt.
[0177] As before described, a feedback signal may be provided
through line 312, to the signal generator 250'', indicating that
the friction braking mode is in operation. The signal generator
includes means, for generating a signal 310 for continuing
actuation of the hydraulic control system 302. Release of the brake
pedal 57 transmits a signal by way of line 292 to the signal
generator 250'', to indicate termination of a demand for
deceleration of the car.
[0178] When the brake pedal 57 is released to its rest position the
brake signal 292 is terminated, the brake hold in signal 312 is
terminated and the system is reset for further powered operation.
However, if, when friction braking is terminated, the flywheel
speed is too high (say in excess of 90% of the maximum safe
operating speed) to permit transfer of a significant quantum of
braking energy thereto, subsequent depression of the brake pedal
invokes alternator braking as described in connection with FIG. 35,
with reliance being had on friction braking (FIG. 37) if more rapid
deceleration is required.
[0179] To the extent possible, it is preferred that the
deceleration energy stored in the flywheels 52, 54 be returned to
the energy system of the car as motive power. This recapture of
energy is illustrated in FIG. 38, which illustrates operation of
the car 30.sub.M/A in its flywheel acceleration/powered mode. This
mode of operation is invoked by displacement of the pedal 56 to
generate a power demand signal 286 input to the signal generator
250''. The availability of flywheel energy is sensed by the signal
generator 250'' through the speed signal (308) input from the
flywheel speed signal generator 376. With a speed signal 308 input,
the signal generator generates (or maintains) signal 246 placing
the transmission 66 in its energy recovery mode. The strength of
the signal 246 may be proportionate to the strength of the power
demand signal 292 (reflecting the degree of displacement of the
pedal 56), in establishing the power ratio across the transmission
66, to the end of matching the power input to the differential to
the rate of acceleration desired.
[0180] Also there is a flywheel speed signal input 388 to the mode
signal generator 362. With both a flywheel signal input (308) and a
power demand signal (286) the signal generator provides a modified
power delivery signal 364' to the mode signal generator 362. The
resultant output signal 360 causes the integrator 354 to direct
power from the flywheel drive connection 358 to the differential
drive connection 356.
[0181] When the energy in the flywheels is insufficient to power
the car 30.sub.M/A at a desired rate (as reflected by the degree of
displacement of the pedal 56) additional motive power may be
provided by the motor 350, reference FIG. 39. To this end motor
mode signal 368 will be generated when the speed of the car is less
than the demand for speed that is reflected by the degree to which
the pedal 56 is displaced.
[0182] A motor speed signal generator 390 generates a motor speed
signal 392 input to the mode signal generator 362. The flywheel
speed signal generator 376 continues to provide a signal input 388
to the mode signal generator. These speed signal inputs modify the
control signal 360 to the end of dynamically adjusting the
integrator to combine the flywheel drive connection 358 and the
motor drive connection 352 in proper proportions to drive the
differential connection 356 up to the point where the energy
remaining in the flywheels can no longer be efficiently used to
power the car 30.sub.M/A. When that point is reached, as may be
indicated by the flywheel speed signal 308, the clutch actuation
signal 344 is terminated and the clutch 314 is disengaged.
Operation of the car 30.sub.M/A then continues in the fashion
illustrated in FIG. 33.
[0183] From the foregoing it will appreciated that, in normal
operation, there is a continuing interchange of kinetic energy to
and from the flywheels 52, 54. As the car is decelerated by
flywheel braking action, flywheel speed increases up to the point
of maximum safe operating speed. Additional deceleration is
obtained through alternator braking action and, if need be, through
friction braking. The energy of alternator braking is recaptured in
recharging the battery arrays 48, 50. The flywheel braking energy
remains stored in the rotating flywheels and is usually recaptured
as motive power for the car 30.sub.M/A. Only the energy of friction
brake is a total loss. ? broaden coverage beyond flywheel mounted
energy source?
[0184] In the normal course of operation, an automobile will be
accelerated, then braked, and then reaccelerated to accommodate
traffic and road conditions. There will be occasions where there
can be repeated braking functions, but these occasions will be
followed, eventually by reacceleration of the automobile. The point
being made is that under essentially all duty cycles for most, if
not all types of vehicles, there will be no reason for recovery of
flywheel energy other than by employing this energy for motive
power purposes. The large mass and the large diameter of the
flywheels contributes to their ability to provide a very large,
energy storage capacity. These factors lead to the preference of
recapture of flywheel energy through recharging of the battery
arrays 48, 50 only when the car 30, has completed a duty cycle and
is to be shut down.
[0185] Recovery of flywheel energy when the car is shut down will
now be described with reference to FIG. 40 and an "ignition" switch
396, in a conductor 398. When the car 30.sub.M/A is initially put
in service, switch 396 is closed to energize signal generator 250''
from the battery arrays 48, 50 (FIGS. 33-39). When the switch 396
is opened to "turn off the ignition", an appropriate hold-in
circuit 397 (FIG. 40) will be energized by the signal generator so
long as there is a signal 308, indicating that there is rotational
energy in the flywheels 52, 54. In response to opening of switch
396, signal generator 250'' will provide a field excitation signal
372 to the secondary alternator 62c. Additionally a power recovery
signal will set or maintain the shaft 230 as the drive shaft for
the transmission 66. The clutch 314 is disengaged, so that the
rotational energy in the flywheels drives the alternator 62.sub.c,
generating current that is fed by conductor 374 to rectifier 164
and then through conductor 174 176 to recharge the battery arrays
48, 50. When the flywheels come to a stop, or when they reduce in
speed below that at which current can be effectively generated, as
reflected by the speed signal 308, the hold in circuit 397 is
opened and the signal generator 250'' deenergized. The alternator
62C may be sized so as to provide a "trickle" rate recharging to
the battery arrays 48, 50. Thereby maximizing the recovery of
flywheel energy as electrical energy, and at the same time
recharging at an optimal rate for batteries, such as lead-acid
batteries, which are adversely affected by being recharged at a
rapid rate.
[0186] The use of the mechanical integrator 354 also permits
recovery of flywheel energy by recharging the battery means. This
is to point out that when the "ignition" is turned off, as above
described, the signal generator would generate a signal 344 to
engage the clutch 314; a power recovery signal 246, to transmission
66, would be generated; an alternator mode signal 369 would go to
the motor alternator 350; and a further modified signal to mode
signal generator 362 would also be generated so as to set the
mechanical integrator in a battery recharging mode. The hold in
circuit 397 would maintain this battery recharging mode until most,
if not all, of the energy of the flywheels had been recovered in
recharging the battery arrays 48, 50. When the battery arrays 48,
50 are recharged in this fashion, it is no longer necessary to
provided the secondary alternator 62c. ?claim?
[0187] From the foregoing, it will again be apparent that the
described system minimizes battery charge discharge cycles in that
all deceleration energy that is transferred to the flywheels, is
returned the car's energy system as motive power for operation of
the car. The sole exception being that energy that remains in the
flywheels, when operation of the car is to be terminated for some
indefinite period of time, as just described. There are, of course,
battery charge-discharge cycles inherent in the use of the
alternator 350 to provide a braking function. Nonetheless, the
increases in range/payload that are obtained by so recapturing
braking energy more than offset the shortening of battery life that
is incident to additional battery charging at other than a "trickle
rate".
[0188] The mode of operation in which flywheel energy is
preferentially employed as motive power is particularly suited to
the operating characteristics of lead-acid batteries. It is to be
appreciated that the described use of a separate mechanical
integrator 354 to direct power between the motor/alternator 350,
the flywheels 52, 54 and the transmission 44, provides a capability
that would accommodate other modes of operation of the types
earlier discussed.
[0189] Reference is next made to FIGS. 41-44 for a description of a
simplified motor/alternator car 30.sub.M/A' which is an
amalgamation of features found in previously described embodiments,
that have been optimized for the mode of operation describe in
connection with FIGS. 36-40, wherein the return of flywheel energy
may be maximized in the form of motive power input. Components in
common with earlier described embodiments are identified by like
reference characters without further description unless
required.
[0190] The car 30.sub.M/A' comprises a motor/alternator 350 having
a bidirectional connection 43' with differential gear set 44. A
flywheel power train 58'' also includes a bidirectional drive
connection 358' with the differential gear set 44, along with
clutch 314, power train 58'' and transmission 66. In a sense, the
motor alternator 350 has been substituted for the motor 42 in the
embodiment of FIGS. 1-23 while the differential gear set 44 again
functions as a mechanical integrator. Again there is provided a
bidirectional drive between the flywheels 52, 54 and the front
wheels 34 and a bidirectional drive connection between the front
wheels 34 and the motor/alternator 350.
[0191] A secondary alternator 62'.sub.c, which serves the same
functions as the secondary alternator of the previous embodiment,
is a separate, relatively small alternator which is mechanically
driven by a pulley-belt drive 400 from drive train 58'', and
selectively energized by a field excitation signal 372. The car
30.sub.M/A' otherwise comprises components previously described in
connection with FIGS. 18-23 or FIGS. 33-39, which will be
referenced in connection with operational modes of this embodiment,
as they are now to be described.
[0192] FIG. 41 illustrates the cruising mode of operation of the
car 30.sub.M/A', corresponding to the operational state illustrated
in FIG. 33. Power demand pedal 56 is depressed, providing a demand
signal 286 to the signal generator 250'''. This then produces a
motor mode signal 368 and an energizing signal 288 to the actuation
switch 290, whereby the motor 350 provides a power input to the
differential 44 which is proportional to the degree to which the
pedal 56 is displaced.
[0193] As in the last described embodiment, when decelerating, it
is preferred to first employ flywheel braking, as illustrated in
FIG. 42. Initial depression of the brake pedal 57 provides a signal
input 292 to signal generator 250''' which results in an energizing
signal 344 to thereby engage the clutch 314. Also flywheel braking
signal 248 is generated to set the transmission 66 for transfer of
energy from the wheels 34 and transmission 44 to the flywheels 52,
54 at a rate proportional to displacement of the brake pedal
57.
[0194] When flywheel braking is insufficient to provide a desired
rate of deceleration, continued displacement of the brake pedal 57
will invoke a combination of flywheel braking and alternator
braking, as the change in braking signal 292 results in an
alternator mode signal 369 (FIG. 42). The alternator 350 is thus
energized and further decelerates the car 30.sub.M/A' as the
alternator 350 converts motive energy to electricity, which is then
fed by way of conductor 371 to the rectifier 164 and employed to
recharge the battery packs 48, 50. A flywheel speed signal input
308 may also be provided to the signal generator 250''' for
purposes of terminating flywheel braking when a maximum safe
operating speed is reached, and/or for purposes of invoking
alternator braking when flywheel speed approaches a maximum safe
operating speed, in the same fashion as described in connection
with FIG. 36.
[0195] Friction braking would also be provided for purposes of
decelerating the car 30.sub.M/A', when flywheel and/or alternator
braking are insufficient or unavailable for such purpose. Those
skilled in the art will appreciate from FIG. 37 and its
description, the manner in which friction braking would be
incorporated in the car 30.sub.M/A'.
[0196] FIG. 44 illustrates the manner in which flywheel energy is
recaptured as motive power in essentially the same fashion shown
and described in connection with FIG. 39. This mode of operation
may be invoked, when there is some useful quantum of energy in the
rotating flywheels 52, 54, such state being indicated by a speed
signal input 308 to the signal generator 250''', when the power
demand pedal is depressed. As described in greater detail in
connection with FIGS. 38 and 39, transmission signal 246 sets the
transmission 66 for the transmission of energy from the flywheels
52, 54 to the differential 44. At the same time, motor mode signal
368 actuates the motor 350 to provide a power input, through
connection 43', to the differential 44, which integrates this input
with the flywheel power input from connection 358' to power the car
30.sub.M/A' through the axles 46.
[0197] The car 30.sub.M/A' may also be provided with means for
recovering flywheel energy when it is to be parked and out of
service for some extended period of time. FIG. 41 also illustrates
this recovery mode, which is essentially the same as described in
connection with the car 30.sub.M/A, with particular reference to
FIG. 40. Thus an "ignition" switch 396 is provided in the conductor
398, which energizes the signal generator 250'''. As previously
described, when the ignition switch 397 is shut off (opened), and
there is a flywheel speed signal input to the signal generator
250''', a hold-in switch 397 is closed to temporarily maintain
energization of the signal generator 250'''. Also a field
energization signal 372 is provided to the alternator 62'.sub.c.
Transmission signal 246 is actuated to transmit flywheel energy to
the alternator 62'.sub.c. The electricity thus generated is fed
through conductor 374 to rectifier 164 and then employed to
recharge the battery arrays 48, 50. When the speed signal 308
indicated that there is little or no energy remaining in the
flywheels, switch 397 opens the control system for the car is at
rest.
[0198] Reference is next made to FIGS. 45-51 for a description of
an embodiment of the invention in which fuel cells provide the
energy for steady state operation of a car designated 30.sub.FC.
Rechargeable batteries provide a supplemental energy source which
enables the car 30.sub.FC to accelerate at a more rapid rate.
[0199] Looking first to the schematic shown in FIG. 45, it will be
seen that the upper flywheel 54 may be essentially the same as in
the other embodiments, having mounted thereon battery array 50. The
lower flywheel 52' differs from the lower flywheel in previous
embodiments in that it has a fuel cell array 410, which is
comprised of a plurality of individual fuel cells 412, which
function as the primary source of energy for operation of the car
30.sub.FC.
[0200] The individual fuel cells 412, like the voltaic cells 150,
may be disposed in the several compartments 112 of the lower
flywheel 52' and connected in series to generate an output
potential across conductors 154, 156. The voltaic cells of the
battery array 50, as before, may be disposed in the compartments
114 of the upper flywheel 54 and are connected in series to
generate an output potential across conductors 158, 162.
[0201] Excepting for certain modifications seen and described in
connection with FIGS. 46 and 47, the structure of the flywheels;
the mechanical connections thereto; and the electrical conductors
employed therewith, as well as the containment device 68, may be
essential identical to what has previously been described,
particularly in connection with FIGS. 7-16. Such structure will be
identified by like reference characters in this embodiment with the
understanding that such previous descriptions are likewise
applicable.
[0202] The output potentials of the battery array 50 and the fuel
cell array 410 are connected as separate inputs to an
inverter/rectifier 164', which corresponds in function to the
inverter/rectifier 169, previously described. The fuel cell array
circuit comprises an inverter grounding conductor 170, which is
connected to stationary shoe 178, with that shoe being in sliding
contact with the flywheel mounted rail 180, to which the conductor
154 is connected. The positive conductor 156 is connected to the
upper rail 182 of the flywheel 52' and the electric circuit to the
inverter 164' completed through shoe 184 and conductor 176'. The
battery array 50 is connected across the inverter by a circuit from
grounding conductor 170', stationary shoe 188, flywheel rail 190 to
conductor 158. The positive side of the battery array 50 goes from
conductor 162, flywheel rail 192, shoe 194 and conductor 176. A
voltage regulator 414 is then connected across the positive output
conductors 176, 176'.
[0203] FIG. 45 additionally illustrates the control signals
connections for a motor/generator 350 and a secondary alternator
62'c as are also found in FIGS. 41-44 and need no further
description at this point.
[0204] Reference is next made to FIGS. 46, 47 for a description of
the modifications made in providing the fuel cell array. While the
present invention is not necessarily limited to the use of any one
type of fuel cell technology, the present state of the art makes
desirable the use of proton exchange membrane (PEM) fuel cells.
This type of fuel cell has operating characteristics compatible
with operation of a self propelled vehicle, particularly its
operating temperature of 176.degree. F., which is much lower than
that of most other fuel cells. This factor, plus a relatively low
cost, set the PEM apart as the most likely alternative energy
source for electric motor powered vehicles.
[0205] The PEM fuel cell is based on a reaction between hydrogen
and oxygen, with a platinum catalyst. Atmospheric oxygen is
suitable and readily available for use in a PEM fuel cell. Hydrogen
for a PEM fuel cell is more of a problem. At the present time,
"reformers" have been developed which derive hydrogen from
hydrocarbon and alcohol based fuels. While other gasses are also
generated by reformers, these pollutants are minuscule in
comparison to the pollutants exhausted from internal combustion
engines. In fact, the characteristics of reformer emissions are
such that they fall within the allowable limits of a "zero
emission" vehicle, as defined by at least one leading, governmental
regulatory agency. Additionally, it is understood that alternative,
"reformer" technology will totally eliminate noxious emissions. It
is to be anticipated that a hydrogen supply infrastructure will be
developed in the future so that a car can "fill up" with hydrogen
in the same fashion as in now done with gasoline. This type of fuel
cell requires gaseous hydrogen and oxygen and produces water as a
waste product. Hydrogen may be directed to flywheel 52 by way of a
hose 416 which extends to an on-board hydrogen source. This
hydrogen source may be a pressurized storage tank, or a hydrogen
generating reformer. Atmospheric oxygen suffices as the source of
that component of the fuel cell reaction.
[0206] The hose 416 is connected to a stationary housing 418, which
is mounted on top of the gear set housing 232. The central flywheel
shaft 118' extends upwardly through the housing 232, into the
housing 418, with a fluid seal 419 being provided to provide a
sealed chamber at the upper end of the shaft 118'. The lower
flywheel 52' is basically the same as the flywheel 52 previously
described in that it comprises a plurality of compartments 112
which are defined by outer disc portions 102, 104 interconnected by
an outer, annular rim portion 106 (not seen in FIGS. 46, 47) and an
intermediate annular band 108. The flywheel structure is further
reinforced by radial vanes 110, which define the compartments 112.
A central resinous hub 111' then joins the central portions of the
disc portions 102, 104. A splined, metal hub 124' is bonded to a
corresponding spline on the interior of the resinous hub 111', as
before. The flywheel 52' is then joined to the shaft 118' by a
spline formed on an enlarged diameter 421 of that shaft. The spline
on the enlarged diameter 421 then engages a corresponding spline on
the metal hub 124'. Again the flywheel 52' is axially positioned on
the shaft 118' by resting on a snap ring 142', which is fastened to
the enlarged diameter 421.
[0207] Assembly and disassembly of the modified flywheels is
essentially the same as before. Note that gear box cover can be
readily removed by lifting it vertically off of the shaft 118'. The
means (screw 236') for fastening the gear 224 to shaft 118' and the
means (screw 240) for securing the gear 226 to the tubular shaft
120 can be readily removed. Then the several snap rings can be
removed, as previously described to free the flywheels for removal
from the containment device 68.
[0208] Hydrogen may be provided to the fuel cell array 410 by way
of the tube 416, into housing 418, and then downwardly of the shaft
118', through an axial hole 420, and then outwardly through radial
passageways 422 The passageways extend through the enlarged
diameter 421 of shaft 118', the metal hub 124' the resinous hub
111' and then to and through the annular band 108', to enter
compartments 112, in which the fuel cells 412 are disposed. Two,
diametrically opposed, radial passageways 422 may be employed, with
circumferential passageways 424 being provided to distribute
hydrogen to all of the compartments 112 by way of appropriate
opening through the annular band 108.
[0209] Water, which is the waste product of the fuel cells' voltaic
reactions, is drained from each of the compartments 112, through
appropriate openings in the annular band 108', circumferential
passageways 426 and a pair of radial passageways 428, which extend
through the resinous hub 111', the metal hub 124' and the enlarged,
diameter of shaft 118'. The waste water may then be discharged from
the car 30.sub.FC through an axial passageway 430 in the lower end
of the shaft 118'. A check valve 432 is provided in the drain
passage 432 to prevent entry of foreign matter into the fuel cell
energy generating system.
[0210] At this point it will be noted that, as in other embodiments
of invention, most, if not all, of the braking energy stored in the
flywheels, can be returned to the car's energy system as motive
energy in reaccelerating the car 30.sub.FC. This means that there
will be extended periods of time where the flywheels 52', 54 will
be either stationary or rotating at very slow speeds. Thus there
will be an absence or very substantial minimization of centrifugal
forces that tend to prevent flow of water toward the central drain
passage 430.
[0211] A secondary water drainage system is also provided disposal
of water at times when the flywheel 52' is rotating at speeds which
would prevent drainage through the axial passageway 430. To this
end a gutter 440 (FIG. 46A) may be formed peripherally of the lower
surface of the flywheel 52'. Passageways 442 extend from the lower,
outer (radially) portion of each compartment 112 to the gutter 440,
which is provided with an outer circumferential rim 444. A water
retriever 446 is mounted on a tube 448, which in turn in mounted on
the wall 70 of the containment device casing 70. The tube extends
to the suction side of a vacuum pump 450. A passageway extends
centrally of the water retriever 446 opens into the gutter 440 and
communicates, through the tube 448 with the vacuum pump 450. See
also FIG. 46B.
[0212] Thus, water generated by the fuel cells 412, during high
speed rotation of the flywheel 52', is discharged into the gutter
440, being retained therein by the rim 444, until suctioned off
through the water retriever 446 and then discharged from the pump
450. In most circumstances it will be acceptable to simply
discharge water from the pump directly into the environment. It
will also appreciated that the pump 450 serves a dual function in
that it also creates a negative pressure in the interior of the
containment device and thereby minimizes windage losses incident to
the high peripheral speeds of the flywheels 52', 54.
[0213] When the car 30.sub.FC is out of service, the pump 450 will
be shut down. The passageway in and leading from the fuel cell
compartments 112 are sloped so that any further water, generated
while the pump 450 is shut down, will flow to and be discharged
from the containment device by way of the axial passage 432.
[0214] Reference is next made to FIGS. 48-51 for a description of
the operating modes of the fuel cell powered car 30.sub.FC. These
schematics employ the same method of illustrating operating modes
as used in describing previous embodiments, and differ from FIGS.
41-44, describing car 30.sub.M/A', primarily in the substitution of
fuel cell array 410 for the battery array 48 in the lower flywheel
52'. As in FIGS. 41-44, a motor/alternator 350 is employed to
provide the function of a prime mover, and also to provide
regenerative braking.
[0215] FIG. 48 illustrates the cruising mode of operation in which
the power demand pedal 56 is displaced and provides a power demand
signal 286 to the signal generator 250.sub.FC. This results in a
motor mode signal 368 which places the motor/alternator 350 in its
motor mode of operation. Also an energizing signal 288 actuates the
motor controller 290, connecting the output of inverter 164', by
way of conductor 172, with motor 350 to thereby power car 30.sub.FC
FIG. 48 illustrates operation of the car 30.sub.FC in normal,
steady state operation, requiring less than the maximum power
capacity of the fuel cell array 410. Under these conditions, the
fuel cell array, which has a nominally higher potential than the
battery array 50, recharges the battery array as current flows
through the voltage regulator 414. The voltage regulator functions
in customary fashion to shut off recharging current flow when the
battery array is fully charged. The battery array may thus be
maintained in a with a desired state of charge at all times, in
readiness to provide a maximized supplemental power assist during
acceleration of the car 30.sub.FC
[0216] FIG. 49 illustrates the battery assisted acceleration mode
of operation of the car 30.sub.FC, where the battery array 50
provides auxiliary energy in powering operation of the motor 350 to
thereby increase the rate of acceleration. To attain this end a car
velocity signal 434 may be generated from the differential gear set
44 and provided as an input to the signal generator 250.sub.FC. The
signal generator may then compare the speed signal to the strength
of the power demand signal 286 and to generate an acceleration
demand signal 436 to the signal to inverter 164'. In response to
this acceleration demand signal, the inverter 146' then places the
output of the battery array 50 in parallel with the fuel cell array
410, thereby increasing the energy available for accelerating the
car 30.sub.FC. Once the desired vehicle speed is reached, the
acceleration demand signal is nulled out, or reduced below a preset
difference value. In either event, the inverter 164' may comprise
means responsive to the acceleration demand signal 436 falling
below a predetermined value for terminating flow of battery energy
to the motor 350, whereupon the vehicle is powered solely by fuel
cell energy.
[0217] The fuel cell powered car 30.sub.FC may be provided with
regenerative braking in essentially the same fashion as in the
previously described car 30.sub.MA' as will be seen from FIG. 50.
FIG. 50 illustrates the simultaneous application of both flywheel
braking and alternator braking, in response to depression of the
brake pedal 57 to a point where the signal 292 has a strength
sufficient to generate both a flywheel braking signal 248 and a
clutch energizing signal 344 as well as an alternator mode signal
369. In this state of operation, clutch 314 is engaged to provide a
mechanical connection from the vehicle wheels 34, through the
differential 44, the clutch 314, transmission 66 (signal 248 having
provided for transmission of power to the flywheels), to the
flywheels 52', 54 and thus transferring vehicle kinetic energy into
kinetic energy in the rotating flywheels 52', 54. Various
refinements in the control of power flow through the transmission,
as previously discussed in connection with prior embodiments are
also applicable to this embodiment.
[0218] As before, in this dual regenerative braking mode,
alternator 350 generates current, which is conducted to rectifier
164' by conductor 317, converted to direct current and then
recaptured as chemical energy by recharging the battery array
50.
[0219] In the previous embodiments, batteries provided the sole
energy source for powering the car. While regenerative braking did
enable the batteries to be recharged, there was, nonetheless, a
continual discharge of energy from the batteries. In other words,
the braking energy that was returned to the batteries, in one
fashion or another, was energy that had originated from the
batteries by way of accelerating the car. Thus the limiting factor,
where batteries are the sole energy source, is the depth of battery
discharge that is to be permitted before an outside energy source
will be employed to fully recharge them. Available energy and
battery life are both seriously degraded in direct proportion to
the depth to which a battery is discharged. A battery powered car's
useful pay/load range is also defined by the usable energy that is
available when its batteries are charged, because, once they have
been discharged to their design depth of discharge, the car will be
out of service for a considerable amount of time to be recharged--a
matter or hours for lead-acid batteries.
[0220] Many of the shortcomings of batteries are overcome when used
in combination with a fuel cell electric energy source. Thus, there
is no depth of discharge factor that would impact the length of
service life of fuel cells. Fuel cells do not require an extended
"recharging" time. Instead, available energy can be readily renewed
("recharged") by simply refilling the onboard hydrogen container,
or the fuel tank that supplies the reformer for producing hydrogen.
The ready renewal of the fuel cell energy source permits the use of
a portion of the electricity generated by the fuel cells to be used
in maintaining the batteries (48, 50) in a maximized state of
charge so that there will be a highly effective level of battery
energy assist in the acceleration of the car 30.sub.FC. In this way
depth of discharge of the batteries can be minimized to the end
that their service life is substantially enhanced.
[0221] However, it is not necessarily desirable to utilize fuel
cell energy to fully recharge the batteries (FIG. 49). Instead, the
batteries should be recharged to a point approaching, but below a
fully charge state in order that the electricity generated by
alternator braking will be able to be recaptured as
chemical/electrical energy. Ultracapacitors could be employed as an
energy storage device in recapturing alternator generated
electricity, to thereby permit further maximization of the percent
to which fuel cell energy is employed to recharge the batteries
(48, 50). Thus braking energy stored on ultracapacitors could later
be returned as motive energy to the motor 350. The final
determination of the extent to which the batteries are recharged
(FIG. 49) will in most cases be determined by the anticipated duty
cycle for a given car design.
[0222] The fuel cell powered car 30.sub.FC may be provided with
friction braking capability in the same fashion as described in
connection with car 30.sub.M/A having particular reference to FIG.
37. Likewise considerations for invoking friction braking in lieu
of alternator braking and/or flywheel braking, are equally
applicable to the present embodiment and need not be repeated in
detail.
[0223] Recovery of flywheel braking energy is also the same as in
other embodiments, in that it is used in as an auxiliary power
source in a subsequent reacceleratioin of the car 30.sub.FC. Thus
in addition to invoking fuel cell energization of the motor 350 as
described in connection with FIG. 48 and supplemental battery
energization of the motor 350 as described in connection with FIG.
49, flywheel energy is also employed in the reacceleration of the
car 30.sub.FC. To this last end, flywheel speed signal 308 (FIG.
51) is fed to the signal generator 250.sub.FC to provide an input
indicating the availability and strength of flywheel energy. Under
this circumstance, when there is a power demand signal input 286
(as a result of depression of pedal 56), transmission signal 246
sets the transmission for delivery of power from the flywheels 52',
54. Additionally, signal 344 is generated to engage the clutch 314
and thereby provide for the delivery of flywheel energy to the
differential gear set 44 to further power motive operation of the
car 30.sub.FC.
[0224] Thus, there can be three energy sources for powering the car
30.sub.FC, namely flywheel energy, battery energy and fuel cell
energy. Through the provision of appropriate signal generating
means in the signal generator 250.sub.FC, these energy sources may
be employed singly or in combination to power motive operation of
the car 30.sub.FC. In the usual case it would be preferable to
employ flywheel energy as the first employed energy source, when
there is a power demand signal 286 input to the signal generator
250.sub.FC, in which case the transmission signal 246 would set the
transmission 66 for delivery of power from the flywheels 52', 54
and signal 344 would be generated to engage clutch 314 for delivery
of flywheel energy to drive the front wheels 34. At the same time,
the strength of the demand signal 286 and the vehicle speed signal
434 would be compared to generate a differential control signal 436
to the inverter 164'. The strength of this differential signal
(which indicates that a faster rate of acceleration is desired by
reason of the extent to which the demand pedal is displaced) can
then initiate signal 288 for motor controller 290 and thus initiate
flow of current to motor 350, (motor mode signal 358 is actuated
contemporaneously). If the strength of the differential signal 436
is sufficiently large, means within the inverter 164' are
responsive to place the battery array 50 in parallel with the fuel
cell array 176 to provide a third energy source for more rapid
acceleration of the car 30.sub.FC.
[0225] As flywheel energy and rate of rotation are reduced in
providing propulsion energy, the previously described control means
will adjust the differential gear transmission 66, in order that
most, if not all of the flywheel energy is returned to the vehicle
energy system, as motive power. Further as the energy input from
the flywheels is reduced, means within the inverter 164' may be
responsive to any resultant increase in the differential signal
436, to increase the flow of battery current, in order to maximize
the rate of vehicle acceleration. When it is no longer practical,
or efficient, to recapture flywheel energy, as can be indicated by
the strength of the flywheel speed signal 308, clutch energizing
signal 344 will be terminated and clutch 314 will be automatically
disengaged.
[0226] It will be noted that secondary alternator 62.sub.c is
provided in this embodiment and is adapted to be actuated for the
recovery of flywheel energy in the same fashion as described in
connection with FIG. 41. Thus, flywheel energy is transformed into
chemical energy through recharging the battery array 50, when the
car 30.sub.FC is taken out of service.
[0227] In summary, the present invention provides significant
improvements in the state of the art of vehicles powered by
electric motors all to the end of reducing atmospheric pollution.
Certain features of the invention have unique applicability to
compact cars employed for commuting purposes, but the majority of
features will find utility in all sizes and types of vehicles
including large scale polluters as trucks and busses.
[0228] While the embodiments herein described are based on the use
of batteries as the electric energy source, it is to be recognized
that many of the advantages of the invention can be realized using
alternate, electric energy sources, having particularly in mind
proton exchange membrane fuel cells with, or without, an ancillary
reformer and fuel tank, all of which could be mounted on one or
both of the flywheels 52, 54. Continuing in the same vein, it will
be pointed out that proton exchange membrane (PEM) fuel cells
differ from batteries in that regenerative energy cannot be
returned to the energy source. In other words, these fuel cells
cannot be recharged in the sense that batteries can be recharged.
Thus, it is preferable to provide a flywheel mounted battery
regenerative braking system in combination with a fuel cell powered
car.
[0229] Where appropriate in the claims, the term "electric energy
source" or "direct current source" will be employed to denote
aspects of the invention which are not necessarily limited to use
of batteries as the energy source.
[0230] It will also be repeated that a primary focus of the
invention is to exploit the advantages that flow from mounting
batteries on flywheels, so that the battery mass forms a
significant, if not the major portion of the flywheel mass, as it
performs its regenerative function of storing energy so that it can
be recovered. While certain aspects of the invention go to the use
of battery means comprising a plurality of voltaic cells and the
specific manner in which they are mounted on the flywheels, many
aspects of the invention are not so limited. Thus in these broader
aspects other sources of electric energy or direct current, could
well be employed, and the terms "mounted on" or "carried by" or
similar terms are to be understood as denoting that the electric
energy source rotates with and as a part or component of the
rotating flywheel.
[0231] In several aspects of the invention, the novel concepts
involve a combination of known means for effecting a desired
sequence of results, particularly with respects to the generation
of signals and the end results consequent to the generation of such
signals. Those skilled in the art will recognize that the
recitation of such signals and end results implicitly specifies the
provision of such known means.
[0232] Likewise, many deviations from the described embodiments
will occur to those skilled in the art, within the spirit and scope
of the present invention and will fall within the purview of the
following claims.
* * * * *