U.S. patent application number 12/378761 was filed with the patent office on 2009-08-27 for engine-flywheel hybrid.
Invention is credited to Stanley E. Lass.
Application Number | 20090211384 12/378761 |
Document ID | / |
Family ID | 36260295 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090211384 |
Kind Code |
A1 |
Lass; Stanley E. |
August 27, 2009 |
Engine-flywheel hybrid
Abstract
An engine-flywheel hybrid in which the engine power is varied
mainly by the frequency of power cycles, not by the power per power
cycle. The flywheel absorbs the energy from the power cycles and
delivers energy. The rotary stop start mechanism stops and starts a
crankshaft efficiently with minimal energy loss. This is
accomplished by varying the offset of a double crank four bar
linkage. The invention allows an engine's flywheel to be quickly be
brought up to speed in about a half of a revolution, followed by
combustion, expansion, and stopped one revolution after starting.
Further, utilizing offset, the engine crankshaft will turn faster
than the input shaft when the piston is at top dead center,
shortening the time of highest heat transfer, making the engine
more efficient. Also, that when used as an auto engine, the part
load efficiency would be near the maximum efficiency of the engine,
nearly doubling the miles per gallon of the auto.
Inventors: |
Lass; Stanley E.; (Ogden,
IA) |
Correspondence
Address: |
Stanley E. Lass
P.O. Box 308
Ogden
IA
50212
US
|
Family ID: |
36260295 |
Appl. No.: |
12/378761 |
Filed: |
February 19, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10978187 |
Oct 29, 2004 |
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12378761 |
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Current U.S.
Class: |
74/24 |
Current CPC
Class: |
Y10T 74/18392 20150115;
F02N 5/04 20130101; Y02T 10/62 20130101; F02N 11/0814 20130101;
Y10T 74/184 20150115; Y10T 74/18048 20150115; Y10T 74/20 20150115;
Y02T 10/6204 20130101; B60K 6/105 20130101; F16H 21/14
20130101 |
Class at
Publication: |
74/24 |
International
Class: |
F16H 21/18 20060101
F16H021/18 |
Claims
1-6. (canceled)
7. a mechanism driven by an input shaft which stops the output
shaft once per revolution comprising: a. a double crank four bar
linkage, with similar crank radii and coupler length, b. means to
increase the offset of the shafts of said four bar linkage to where
the output shaft crankpin is close to the input shaft axis,
sufficient to substantially stop the output shaft, c. means to
decrease the offset of the shafts of said four bar linkage when the
said output shaft crankpin is away from the input shaft axis,
whereby the output shaft can be stopped once per revolution,
8. The mechanism of claim 7 wherein the said means to increase the
offset and said means to decrease the offset comprises: a. an input
shaft support bracket mounted on a pivot b. said input shaft
support bracket having a first tooth for holding at the minimum
offset and a second tooth for holding at the maximum offset, c. an
eccentric on said input shaft phased to have maximum offset when
the said output shaft crankpin and the said input shaft are
coincident, d. a cyclic hold bracket mounted on a pivot, e. said
cyclic hold bracket having a third tooth for cyclic offset, f. a
link connected from said eccentric to said cyclic hold bracket, g.
a first jaw which may be engaged to said third tooth on said cyclic
hold bracket to change the said input shaft offset cyclically, h. a
second jaw which may be engaged to the said second tooth to hold at
the maximum offset, i. said second jaw which may be engaged to the
said first tooth to hold at the minimum offset, whereby the input
shaft offset can be changed efficiently between minimum and maximum
offset or held at the maximum offset or the minimum offset and the
changeover between a fixed offset and a cyclic offset may be
accomplished when the offset is at an extreme.
9. The mechanism of claim 7 further including a mechanism to
selectively start and stop an attached mechanism comprising the
method of: a. engage the acceleration dog prior to the said output
shaft stopping, b. after the said output shaft starts, engage a
deceleration dog, c. to stop the said attached mechanism, d.
disengage the acceleration dog prior to the said output shaft
stopping, e. after the said output shaft stops, disengage said
deceleration dog,
Description
BACKGROUND TO THE INVENTION
[0001] This invention relates primarily to a mechanism whose input
shaft can be driven by a flywheel and which stops and starts an
output shaft which can drive the crankshaft of an engine.
[0002] The invention is the result of seeking a mechanism which
could quickly stop an engine's crankshaft and quickly start an
engine's crankshaft, and do so with minimal energy losses.
[0003] The invention is an alternative to a big starter motor which
can quickly start an engine.
SUMMARY
[0004] The purpose of the invention is to stop and start an output
shaft efficiently with minimal energy loss. The invention enables
an engine-flywheel hybrid in which the power can be controlled by
the frequency of power cycles. Conventional engines control power
at an rpm by throttling and/or the amount of fuel injected per
power cycle.
[0005] Given a double crank four bar linkage and a constant angular
rate on the input shaft, as the offset between the crank shafts is
increased, the angular rate of the output shaft will approach
infinitely fast and infinitely slow (stopped). For the purpose of
the Invention, the infinitely slow angular rate (stopped) is
useful, but the infinitely fast angular rate is not. To stop the
output shaft, the offset is increased as much as is needed to
achieve the infinitely slow angular rate. Away from the output
shaft stopped position, the offset is decreased to avoid an
extremely high output shaft angular rate.
[0006] An engine crankshaft connected to the output shaft can be
stopped by declutching it from the output shaft when the output
shaft is stopped. And to restart, a clutch can engage when the
output shaft is once again stopped.
Objects and Advantages
[0007] A double crank four bar linkage with variable offset when
positioned between the flywheel and output shaft has the advantage
that the kinetic energy from slowing the output shaft to a stop is
transferred into file flywheel, and later, the flywheel kinetic
energy is used to bring the output shaft back up to speed.
[0008] The intended application is to quickly stop and later, to
quickly start an engine's crankshaft. The engine crankshaft would
be run a revolution or two as often as is needed to provide the
desired level of power. In this application, the advantages
are:
[0009] 1) When the mechanism is used to drive the crankshaft of an
engine, e.g. an engine that fires once per crankshaft revolution,
or every other revolution, the combustion and expansion could be
somewhat faster than the flywheel speed. The flywheel would
normally be operated within a fairly narrow speed range. The power
per combustion can be relatively constant. The operating parameters
can be optimized for efficiency and emissions per combustion. This
includes spark ignition, diesel and HCCI (homogenous charge
compression ignition) engines' operation. (During warmup the power
per combustion could be lower. For maximum power, the speed of the
engine could be higher.)
[0010] 2) At low to moderate power levels, some friction and some
pumping losses are avoided by eliminating some cycling of the
piston and crankshaft.
[0011] 3) When used with an engine for a car, the efficiency in
typical usage should be close to the maximum efficiency of the
engine. This is nearly twice the efficiency of conventional car
engines in typical usage. This would nearly double the miles per
gallon.
[0012] 4) The output shaft must turn at a faster rate than the
input shaft to make up for the slowing to a stop during part of the
revolution. The output shaft turns one revolution per input shaft
revolution. By choosing some of that faster rate to be near the
engine's piston(s) top dead center and early expansion, the
duration of combustion and early expansion would be shortened,
lessening the heat loss during that time. Heat energy not lost
through heat transfer during combustion and early expansion remains
in the combustion gas as heat and can do work expanding against the
piston. This increases efficiency as compared to slower operating
designs which lose more heat, (all else equal). This advantage is
gained without an increase in piston speed. However, the peak
piston speed is a little higher.
[0013] 5) The crankshaft would be turning slower than the flywheel
180 degrees after the piston top dead center. In a two cycle
engine, this lengthens the purge time, longer than it would be in a
conventional two cycle engine, i.e. which has the flywheel directly
coupled to the crankshaft. Accordingly, this would allow faster
engine operation and/or reduced port sizes.
[0014] The engine-flywheel combination should be lighter, cheaper
and more efficient than an engine-electric hybrid that uses
batteries for energy storage.
DRAWING FIGURES
[0015] 1. Slowing the output shaft. [0016] 2. Output shaft stopped.
[0017] 3. Accelerating the output shaft. [0018] 4. No clutch
stopped configuration. [0019] 5. Speedup of output shaft. [0020] 6.
Dog clutch. [0021] 7. Eccentric offset change mechanism. [0022] 8.
Output shaft speed variation. [0023] 9. Engine-flywheel hybrid.
[0024] 10. Power cycles as needed.
LIST OF REFERENCE NUMERALS
[0024] [0025] 12. input shaft [0026] 14. input shaft crankarm
[0027] 16. input shaft crankpin [0028] 18. coupler [0029] 20.
output shaft crankpin [0030] 22. output shaft crankarm [0031] 24.
output shaft [0032] 26. output shaft stop tooth [0033] 28. output
shaft jaw [0034] 30. rotary mechanism shaft [0035] 32. deceleration
dog (engaged position) [0036] 34. deceleration dog (disengaged
position) [0037] 36. tooth on rotary mechanism shaft [0038] 38.
acceleration dog (disengaged position) [0039] 40. acceleration dog
(engaged position) [0040] 42. rotary tooth [0041] 44. rotary jaw
[0042] 50. pivot on input shaft support bracket [0043] 52. input
shaft support bracket [0044] 54. input shaft [0045] 56. eccentric
on input shaft [0046] 58. tooth for minimum offset [0047] 60. jaw
for minimum and maximum offset [0048] 62. tooth for maximum offset
[0049] 64. jaw for cyclic offset [0050] 66. tooth for cyclic offset
[0051] 68. link to cyclic hold bracket [0052] 70. cyclic hold
bracket [0053] 72. pivot for cyclic hold bracket
DESCRIPTION
Definitions
[0054] A crank's radius is the distance from the crankshaft axis to
the crankpin axis. A coupler connects the crankpins of a double
crank four bar linkage. The offset is the distance between the
shafts of a double crank four bar linkage.
[0055] Consider a double crank four bar linkage with the same
dimension on the input shaft crank radii and the coupler length.
The input shaft would have a constant angular rate. As the offset
between the crank shafts is increased, the angular rate of the
output shaft will become infinitely fast and infinitely slow
(stopped), once per input shaft revolution. For the purpose of the
invention, the infinitely slow angular rate (stopped) is useful,
but the finitely fast angular rate is not.
[0056] Away from the vicinity of the stopped position, the offset
is lessened to avoid an extremely high output shaft angular
rate.
[0057] With some offset, there will be an output shaft angle where
the output shaft axis, the input shaft axis and the input shaft
crankpin axis line up. The input shaft angle where the output shaft
is stopped can reasonably be about 45 degrees past the lined up
angle. Regarding the force needed to stop the output shaft and
anything connected to the output shaft, the force is transmitted
through the output shaft crank, through the coupler to the input
shaft crank. For less than about 30 degrees, the forces on the
bearings would be unduly multiplied by the linkage involved. FIG. 1
shows the double crank four bar linkage slowing the output
shaft.
[0058] FIG. 2 shows the output shaft stopped. The inward movement
of the offset shaft tends to backup the output shaft. The turning
of the input shaft tends to pull the output shaft forward. When
these two cancel each other out, the output shaft is stopped.
[0059] FIG. 3 shows the output shaft being accelerated.
[0060] FIG. 7 shows an eccentric 56 on the input shaft which moves
the input shaft 12 cyclically between the offset needed for
stopping the output shaft and a lesser or no offset needed to
achieve the desired speed through the maximum speedup. The input
shaft 54 is mounted on a bracket 52 which is mounted on a pivot 50.
The phase of the eccentric 56 needs to be such that the maximum
offset occurs near the stopping point of the output shaft 24. FIG.
7 eccentric offset change mechanism provides three modes of
operation, cycle between the minimum and maximum offset, stay at
the minimum offset and stay at the maximum offset. The latter is
only used by the FIG. 4 no clutch stopped configuration.
[0061] Different means could be used to change the offset. Cams are
another way to vary the offset, including desmodromic cams which
provide positive movement in both directions. Also, an actuator of
some kind could vary the offset, e.g. a hydraulic cylinder.
[0062] When the offset is varied substantially harmonically, the
offset needed for the output shaft to come to a stop is slightly
less then the coupler length. The motion of the input shaft due to
the decreasing offset plus the motion of the input shaft crankpin
due to the input shaft rotation together produce the crankpin
motion. When the instantaneous center of this crankpin motion is
lined up with the coupler endpoints, the crankpin motion does not
move the output shaft crankpin, i.e. the output shaft is stopped.
Call this the output shaft stopped angle.
[0063] FIG. 9 shows a way a second double crank four bar mechanism
used to connect the input shaft to a flywheel. The crank radii on
the second double crank could be longer so that angular rates,
flywheel to input shaft, wouldn't vary much due to the second
double crank. This design would allow both the output shaft axle
and the flywheel axle to not move relative to each other. The input
shaft axle would move relative to both of the preceding. By having
the crank arms on both ends of the input shaft phased the same, the
side forces coupled into the input shaft bearings tend to be
minimize i.e. the forces that would tend to move the input shaft
support bracket 52 about it's pivot. However, the twisting forces
would remain.
[0064] A rotary mechanism connected to the output shaft, e.g. an
engine's crankshaft, can be stopped by declutching it from the
output shaft when the output shaft is stopped. And to restart, a
clutch can engage when the output shaft is once again stopped.
[0065] FIG. 6 shows a way to implement the clutch such that the
clutch function is implemented by an acceleration dog 40 which can
accelerate the rotary mechanism and a deceleration dog 32 which can
decelerate the rotary mechanism. When both dogs are engaged, the
output shaft is firmly coupled to the rotary mechanism.
[0066] With this clutch, the timing of clutch dogs
engagement/disengagement is not critical. The movement of the dogs
into the engaged position can occur over tens of degrees prior to
engagement and similarly for disengagement. There should be minimal
shock loading on the dogs because the shaft speeds are matched,
albeit briefly.
[0067] The engagement disengagement of dogs could be by a cam that
is moved into position which then engages/disengages the dogs as
the input shaft reaches the cam profile that causes
engagement/disengagement of the dogs.
[0068] With the output shaft clutched into an engine's crankshaft,
the minimum offset could be chosen to optimize the angular rate
over time. FIG. 5 shows the speedup of the output shaft 24. Also,
with the phase between the engine crankshaft and the output shaft
such that there is a significant speedup near the engine's
piston(s) top dead center and early expansion, the time of highest
heat transfer is shortened. This increases the efficiency of the
engine. The rotary mechanism, e.g. engine crankshaft, would always
be stopped at the same angle, including at mechanism rest, e.g.
engine shutdown. This is needed so that the preceding dog clutches
take up smoothly and the phase relationship is maintained.
[0069] For a four cycle single cylinder engine, the offset could be
varied over two crankshaft revolutions, e.g. by using a 1:2 gear
reduction to drive an eccentric or a cam.
Operation
[0070] FIG. 7 shows the jaw for cyclic offset 64 engaged. The
offset is varied substantially harmonically. The rotation of the
eccentric on the input shaft 56 causes the input shaft support
bracket to oscillate 52. With this design, the offset needed for
the output shaft to come to a stop is slightly less then the
coupler length. The motion of the input shaft due to the decreasing
offset plus the motion of the input shaft crankpin due to the input
shaft rotation together produce the crankpin motion. When the
instantaneous center of this crankpin motion is lined up with the
coupler endpoints, the motion does not move the output shaft
crankpin, i.e. the output shaft is stopped. Call this the output
shaft stopped angle. See FIG. 2.
[0071] Away from the vicinity of the stopped position, the
substantially harmonic drive lessens the offset to avoid an
extremely high output shaft angular rate.
[0072] FIG. 8 shows a plot of output shaft speed variation for the
offset fixed at the minimum offset and for the offset varying
harmonically between the maximum, 96.5% of the coupler length
(also, the crank radii) and the minimum 33.3% of the coupler
length.
[0073] A rotary mechanism connected to the output shaft, e.g. an
engine's crankshaft, can be stopped by declutching it from the
output shaft when the output shaft is stopped. And to restart, a
clutch can engage when the output shaft is once again stopped.
[0074] To stop the rotary mechanism 30, when the output shaft 24 is
being slowed to a stop by the deceleration dog 32, the acceleration
dog 34 is disengaged prior to the output shaft 24 stopping. During
the slowing, the acceleration dog 34 will not be transmitting any
force and would be easy to disengage. Then after the rotary
mechanism 30 is stopped, the deceleration dog 32 is disengaged.
This leaves the output rotary mechanism stopped. At this point, the
rotary mechanism would be prevented from angularly drifting by a
rotary 44 hold jaw engaged to rotary tooth 44. Note that the
preceding jaw and tooth are between the dog clutch and the rotary
mechanism, out of the way of the dog clutch.
[0075] To restart, the acceleration dog 40 is engaged prior to when
the output shaft 24 stops. The acceleration dog makes contact at
the output shaft stopped angle. Then as the output shaft is
accelerated out of the stopped position by the acceleration dog,
the rotary mechanism is also accelerated. The deceleration dog 32
is engaged as the rotary mechanism is accelerated. With both dogs
now engaged, the output shaft is firmly coupled to the rotary
mechanism.
Higher Speed Operation
[0076] For faster engine operation, the input shaft could be held
at the minimum offset by the FIG. 7 offset change mechanism. This
would be useful when it was desired to operate the engine faster
for more power. To transition to holding the input shaft at the
minimum offset, when the input shaft is at the minimum offset,
disengage the jaw for cyclic offset 64 and engage the jaw for
minimum and maximum offset 62. To transition back to cyclic offset
variation, wait until the jaw for cyclic offset and the tooth for
cyclic offset lineup, and then disengage the jaw for minimum and
maximum offset 62 and engage the cyclic dog 64.
[0077] In both the minimum and maximum offset hold positions, the
input shaft support bracket 52 is held steady while the link 68
moves the cyclic hold bracket 70 back and forth.
Starting the Engine
[0078] To start the engine, a starter motor could speed up the
flywheel connected to the input shaft. When the flywheel has enough
energy to cycle the engine, the clutch is engaged and the engine is
started and runs until the flywheel is turning faster. This allows
a less powerful starter motor.
Engine Flywheel Hybrid Operation
[0079] For an engine-flywheel hybrid, the predicted flywheel speed
a revolution or two ahead would be estimated. The engine crankshaft
would be stopped until the predicted flywheel speed slowed to below
a threshold, and then the engine would be started by engaging the
clutch at the next opportunity. Then the engine would run until the
predicted flywheel speed is faster than a second higher threshold,
and then stop. This keeps the flywheel in a fairly narrow speed
range. This is somewhat similar to the hit and miss engines of
about a century ago. FIG. 10 shows the power cycles as needed
behavior.
[0080] For more power than the preceding would provide, the higher
speed operation mode could be used.
[0081] For alternate firing of cylinders in a four cycle two
cylinder engine, one cylinder would be part way into it's exhaust
stroke and the other cylinder would be part way into it's
compression stroke. This is for a double crank where the input
shaft crank angle is ahead of the output shaft crank angle.
[0082] Note that when combustion and expansion occurs, the power
flows out of the crankshaft, through the double crank to the input
shaft, perhaps through a second double crank, to the flywheel.
DESCRIPTION AND OPERATION
Alternative Embodiments
[0083] In this alternative embodiment, the coupler length, the
input shaft crank radius and output shaft crank radius have same
dimension.
[0084] To stop the output shaft and keep it stopped, the offset
would reach coupler length at around 45 degrees after the output
shaft, the input shaft and the input shaft crankpin are all lined
up, in that order.
[0085] Then the input shaft crankpin will spin the coupler around
the stationary output shaft crankpin. In this output shaft stopped
configuration, an output shaftjaw 28 engaged to output shaft stop
tooth 26 would keep it from drifting angularly. Also, the offset
must be held steady. FIG. 7 shows the eccentric offset change
mechanism. To hold the offset steady, engage the jaw for minimum
and maximum offset 62 with the tooth for maximum offset 62 while
disengaging the cyclic dog 64. Note that no clutch is needed to
stop the output shaft.
[0086] To transition out of the output shaft stopped configuration,
the offset is decreased, beginning at the input shaft angle when
maximum offset occurs. This is also when the jaw for cyclic offset
64 and the tooth for cyclic offset 66 lineup, and then disengage
the jaw for minimum and maximum offset 62 and engage the cyclic dog
64.
[0087] Higher speed operation would be as in the first version.
[0088] Alternative to the dogs clutches of FIG. 6 is to use a right
hand one way jaw clutch plus a left band one way jaw clutch, one
concentric to the other. The engagement/disengagement could
function similarly to the dog clutch.
CONCLUSION, RAMIFICATIONS AND SCOPE
[0089] Applicant submits that the rotary start stop mechanism can
be used to make an engine-flywheel hybrid which would be more
efficient, lighter and cheaper than an engine-electric hybrid that
uses batteries for energy storage. Further, that when used as an
auto engine, the part load efficiency would be near the maximum
efficiency of the engine, nearly doubling the miles per gallon of
the auto.
[0090] Many modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims, the
invention may be practised otherwise than specifically
described.
* * * * *