Note: Descriptions are shown in the official language in which they were submitted.
2~68~07
RNGINE WITH A~ OFFSET ~SHAFT
BACK~ OE` THE, I~ ~ION
PIEI.D OF THE INVENTION
Thi~ in~ention relates generally to internal combust~on
engines, and more particularly to an engine with an off~et
crankshaft.
S The intexnal combu8 ion engine is well known in the pr~or
art. Examples of prior art refe~nces are Campbell U. S. Pat.
No. 1,091,62g; Pulm~n U. S. Pat. No~ 1,201,098; Penning U. S.
Pat. ~o. 1,317,939; Swensen U. S. Pat. No. 2,236,738; and
Sanchez Great Britain Pat. No. 24,568.
Campbell U. S. Pat. No. 1,091,629 disclo~es a four cycle
engine using two pi~tons in the 8~m~ cylinder, connected with the
crank shaft by an impro~ed 6ystem of roda and rock-arms or crank~
hav-~ng a ~mall number of parts adapted to effic~ently tran8m~t
th~ forces to which they are.sub~ected, whereby one pi~ton ef-
fects the suction of the charge at a relatively 810w rat~, and
the ~caven~ing of the cylinder, ~he other piston serving to com-
pres8 the charge at a relatively rapid rate and execute the power
stroke. The objecti~e of th~ arrangement of crankshaft6 i8 to
allow for driving th~ two pi~tons in opposition and provide a
stro~Q of.the piston~ for every 360 re~olution of the crank-
shaft. Th~ power ~troke is no more than 90 of rotation of the
crankshaft .
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Pulman U. S. Pat. No. 1,201,098 di~closes an engine of
the k~nd or cla3~ in which the working pres6ure is ~xerted be-
tween two p~stons moving in oppogite directions in the working
cylinder, and operating a single crank. Thi~ Patent claLmed the
comb~nation of two oppositely-moving piston~, a single cros~-head
operated b~ the joint action of said two pi~on~, and mo~ing in
the same directlon a8 one of the pi~ons, and a crank driven from
such cross-head and comm~n to the two pi8ton~ ~ in an ~nternal
co~bust~on engine.
Penning U. S. Pat. No. 1,317,939 discloses a combu8tion
engine wherein the cylinder~ are arranged in pai~s, each cylinder
having two pistons, between which the explosion occurs, the move-
ment o the pi~tons belng t~an~mitted to a single crank shaft by
means of rocker8 and connecting rods. The power ~troke ~ 8 no
lS more than 180 in thi~ engine. The ob~ect of this in~ention was
to provide improvements more e~pecially applisable to two cycle
Qngines, and also various improvements ~n details of con~truction
and oiling, whether of the type employing carburetor~ for forming
the explosiv~ charge, or of the Diesel or semi-Diesel types.
S~en~en U. S. Pat. No.. 2,236 "38 discloses a novel power
transmigsion mechanism whereby ~he reciproca~ing movement of t~e
cylinder-and-piaton engine will be converted into rotary motion,
or conversely, rotary ~otion of the pow~r-driven shaft may be
con~erted into reciprocating movement in a cylinder-and-pi~ton
machine, ~uch a6 a pump or air co~pres~or. The power stroke i~
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no more than 180 in this engine. That invention may be employ~d
in connection with a single cylinder-and-pi~ton englne or in con
nection with a multi-cylinder-and-pi~ton engine. However, the
pr~ferred embodiment employed a plurality of such engines in con-
nection with a rotary shaft having a plurality of oblique cran~g
set in such a way that ths endwise thru~t on the rotary ~haft
w~ll be neutralized.
Sanchez Great Britaln Pat. No. 24,568 di~closes an engine
of the rotary type in which the cyl~nders are arrang~d in the
orm o a ~tar, ~uch a~ were intended for a~iation in 1914. The
invention i8 a ~leeve-valve engine. The power stroke i8 no more
than 180 ~n this engine.
~h~ present invention i8 di~tinguiehed over the prior art
in yeneral, and ~hese patent8 in particular, by a new and u~eul
imp~o~ement to intern~l combu~t~on engines which i8 an engine
with an off~et crank6haft. When the crank~haft i8 rotated in a
clockwi~ direction, the di~tance the pi~ton travels rom the top
of the 8troke (piston at max~mum ~ra~el) to the bottom of the
8troke ~pi8ton at the bottom of its travel) i8 greater than the
diameter o~ She crankshaft rotation. The angle through which the
crankshaft move6 during the downstroke i8 greater than 180. The
engine therefore has a longer tLme power stroke than exhau~t
~troke. The intake cycle i8 longer in time than the Qxhaust
cycle w~ich impro~es aspiration o~ the engine. This concept can
be applied to otto cycle engine~, Diesel engines, two stroke en-
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2068~07
gine~, and may b~ applied to co~pressor~. When used in ~ompres-
sors, the intake 6troke is extended which Lmprove~ a3piration.
SUMMA~Y OF ~HE INVEN~ION
It i9 therefore an object o$ the pre~ent invention to
prov~de an engine with an off~et crankshaft.
It i8 another object of this invention to provide an
engine ha~ing a downstroke longer than the doun~troke in a
standard engin~ for an equal diameter crankshaft.
Anoth~r object of thi~ invention i~ to provid~ an engine
in which the crankshaft moves through an angle greater than 180
during the downstroke.
Another object of thi~ invention i~ to pro~ide an engine
in which She power stroke i~ longer in time ~han the compres8ion
8troke.
Another ob~ect of thi~ invention ~6 to provide an engin~
~n which the inta~e ~troke ~8 longer in time than the exhaust
8tro~e.
A further o~ect of thi~ invention is to provide an en-
gine hav$ng improved aspiration.
A gtill further ob~ect of this invention ~ to prov~de an
engine that applies power through a greater rotation of the
crankshaft than a standard engine.
- Other objects of the invention will become apparent from
time to t~me throughout the Rpecification and claims as hereinaf-
ter rel-t~d.
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The above noted ob~ect~i and oth~r ob~ects of the in-
vention are accomplished ~y a ne~ and useful improvem~nt to in^
ternal combustion engines which is an engine with an offset
crank~haft. ~hen the crank~haft i5 rotated in a clockwise dir-
ection, the d~itance the p~ston tra~el~ from the ~op of the
stroke ~piston at maximum.trav~l~ tO the bottom of the stroke
(piston at the bottom of it0i travel) i~ greater than th~ diameter
of the crankshaft rotation. The angle through ~hich the crank-
shaft moves during the downstroke i~i greater than 180. The en-
gine therefore has a longer time power stroke than exhaust
stroke. The intake c~cle is longer in tim~ than the exhaust
cycle which improves aspiration of the engine. Thi~i concept can
be applied to Otto cycle engineQ, ~i~sel engines, two troke
eAgines, and may be applied to compressors. When us~d in com-
pr~ or~, th~ ~ntake 6troke i8 extendQd whlch impro~es aspira-
tion.
BRIE~ DESCRIPTION OP THE ~RAWING~
P~ g. 1 is a schematic view ~howing the align~d relation
of the piston and crankshaft in a conventional engine.
Fig. 2 i~ia ~chematic view ~howing the offset relation of
the piiton and crankshaft in accordance with the present in~en-
tion.
Fig. 3 is a cro~ section view of an internal combu~tion
~ngine with an offset crankshaft, in accordance with the pre~ent
in~ ntion, ~hown during the int k ~troke~
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~ig. 4 i8 a cross-section YieW of an internal combustion
eng$n~ with an off~et crankshaft, in accordance with the pr~sent
~nventlon, shown dur~ng the compre~ion stroke.
Flg. 5 is a cross-section view of an internal combustion
5engine with an offset crank~haft, in accordance with the pre~ent
invention, shown at the beginning of the power stroke.
Fig. 6 i~ a cross-section view of an internal combustion
engine with an off6et crank~haft, in accordance with the present
in~ention, shown during the exhau~t stroke.
10Fig. ~ is a right elevat$on of an int~rnal combustion en-
gine w$th an of~s~t crankshaft, a~ shown in Figs. 3 - 6.
Fig. 8 1~ a graph of piston position v~. degxee~ of
crankshaft rotation for a con~ent~onal engine with aligned p~ston
and crank6haft and an en~ine with tho ofset relation of the p~-
15ton and crank~haft in accordance with the present in~ention of
the arrangem~nt shown in F$gs. 3 - ~ where both eng~nes ha~e
egual 6troke.
F$g. 9 is a graph of piston ~elocity ~8- degrees of
crankshaft rotation for a co mentional engine with aligned pi~ton
20and crankshaft and an engine wlth the offset relation of the pi~-
ton and crankshaft in accordance with the pre~ent invention of
the arrangement ~hown in Figs. 3 - 6 where both engines ha~e
equal ~troke.
Fig. lO is a graph of p$8~0n acceleration v~. degree~ of
25cranksh~ft rotatlon for a ~oA~ention~l en~lne ~lth ~llgned p1ston
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and crankshat and an engine with the of et relation of the pi~i-
ton and cranksha~t in accordance wit~ the present invention of
the arrange~ent shown in Pigs. 3 - 6 where both engine~ have
equal stroke.
Fig. 11 is a sraph of crank~haft torque vs. degrees of
crankshaft rotation for a conventional engine with aligned piston
~nd cranXshaft and an engine with the off~iet relation of the pi8-
ton and crankshaft in accordance with the present inYention of
- the arrangement hown in Figs. 3 - 6 where both enginei3 hav~
equal stroke.
~ig. 12 i8 a graph of integrated torque vs. degrees of
crank~haft rotation for a conventional engine with aligned piston
and cranksha~t and an engine with the off~et relation of the
pi~iton and crank8hat ln accordance with the present inven~ion o~
lS the arranqement shown in Figs. 3 - 6 where both engineQ ha~e
equal strokQ.
DESCRI:PTION O~ ~HE PR3~FERRED EI~BODII~ENq~
This invention relate~ to new and u~eful improvements in
$nternal combustion engines and re particularly to an engine in
which the piston i8 substantially offset from the center ~ine of
~e crankshaft.
Referring to the drawings by numerals of reference, in
~ig. 1, there is shown a schematic Yiew showing the aligned re-
lation of a piston 10 and crank~haft 11 in a conventional eng-
ine. In Fig. 2, there is ~ihown a schematic view showing the
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2~68~07
of~et rela~ion of the piston 12 and crankshaft 13 in accordance
wi~h the present invention.
For a ~tandard engine, when the crankshaft 11 i8 rotated,
the time it takes the piston 10 to travel from the top of the
stroke to the bottom of the stroke i~ equal to the tL~e it takes
the piston to return from the bottom of the ~troke to the top of
the ~troke. However, in an engine with an o~fset ~rankshaft em-
bodying the present lnvention, when the crankshaft 13 i8 rotated,
the time it takes the piston 12 to travel from the top of the
3troke to the bottom of the stro~e is great~r than the tLme it
takes the pi~ton to return from the bottom of the stroke tO the
top of the stroke. The distanc~ the piston travels from the top
of the stroke (pi~ton at maximum travel) to the bottom of the
atroke (pi~ton at the bottom o~ its travel) is greater than the
diame~er of the crankshaft rotation. The angle through which the
crankshaft m~ves during the downstroke is greater than 180. The
engine therefore has a longer time power ~troka than exhaust
stroke. The intake cycle is longer in time than the exhaust
cycle which improves aspiration of the engine.
In Fi~s. 3 - 7, an engine in which the pis~on is sub-
~tantlally offset from the center line of the ~rankshaft i5
shown in ~ore detail. Internal combustion engine 14 comprise~ a
cylinder 15 with a piston 16 positioned for reciprocal movement
therein.
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~he uppex end of cylinder 15 includes a cylinder head
portion 17 with an intake port 18 and ex~au~t port 19. An over-
head intake valve 20 cooperates with valve seat 21 and an over-
head exhaust ~alve 22 cooperates with valve ~eat 23. Overhead
valves 20 and 22 are spring loaded to a closed poaition by
spring3 24 and 25. Rocker arms 26 and 27 are operated by camshaft
28 to operate valve~ 20 and 22 in coordin~ion with mo~ment of
piston 16. Camshaft block 29 enclose3 an overhead cam~haft 28
and rocker arms 26, 27. The camshaft lobes are ~paced 85 or 95
apart in contrast to 90 for a standard engine to accQmodate the
offset c~anksha~t timing. The structure ~o far de~cribed, except
for the spacing of the camshaft lobes, i~ conventional internal
co~bustion en~ine dosign~
The bottom end of cylinder 15 includes a skirt portion 30
~orming the cover for the crankca~e 31. A crankshaft 32 i~ po8i-
tioned for rotation inside the crankcase 31 with its center line
33 laterally offset from the ce~ter line of cylinder 15. ~he
amount of offset is a matter of choice for the engine designer
along with other factors ~uch as d~en~ions of the engine, length
of connecting rod, etc. In the embodiment ~hown, the a~ount of
off~et is approximately equal to the length of the crank arm.
Th~ portion of cy~inder 15 ad~acent to crankcase 31 has a slot 36
positioned to accomodate ~idewi~e pivotal movement of connecting
rod 34 during movement of piston 16 and cranksha~t 32 through a
full cycle of operation.
206~07
In ~ig. 7, a right elevation of the engine iQ shown to
illustrate the varîous connec~ions. Crankshaft 32 ha~ a gear 36a
at lt6 outer end connected by a timing belt 37 to gear 38 which
operates cam~haft 28. ~he operation o~ engine 14 i8 the same a~
S that of conventional engine~ except for the crank~ha~t of~et and
valve timing. ~he pi~ton 16 reciprocates in cylinder 15 t~rough
the convent$onal intake, compress10n, power and exha st stroke~.
Ro~ation of crankshaft 32 operate~ camshaft 28 through timing
belt 3? to operate the intake valve 20 and exhaust valve 22 in
the proper ~equence for the intake, compression, power and ex-
haust ~trokes.
Thi~ invention is conventional in structure exce~t for
the of~set re~ation o~ the c~nter line o~ plston 16 and tho
cent~r line o~ cranksha~t 32. Alr inlet to the ~ngin~ is pro-
~ded through a carburetor (not shown) and an intake maniold
(not 8hown). Exhau~t gases from the engine pa~s through an ex-
haust manifold (noti6hown). The position of the cranXshaft 32 in
relation to pi~ton 16 and connecting rod 34 i~ shown for the in-
tak~, comprei~sion, ~ower and exhau~t strokes in Fig~. 3 - 6 and
th~ operating characteriistic~ of the engine are ~hown in the
graph~ compri~ing Fig~. 8 - 12.
~n Fig. 3, the engine 14 wi~h offset crankshaft 32 is
shown in the intake stroke. Cylinder lS ~s filling with the
fuel-air mixture, and the pi~ton 16 i8 shown in the first down-
~; 25 ~troke or lntake stroke. The connecting rod 34 and crankshaft 32
, 10
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2~68507
are ~hown offset as described above. Exhau~t val~e 22 i~ closed
and intake valve 20 i8 open.
In Fig. 4, the engine ~4 with offset crank~ha~t 32 i~
shown at the start of the compression stroke. Cylinder 15 is
~illed with the fuel-air mixture, and the pl~ton 16 is shown in
the first upstroke or compression stroke. The connecting rod 34
and crankshaft 32 are shown offse$ as described above. Both
valves 20 and 22 are clo~ed.
In Fig. 5, ~h~ engine 14 with an off~et cranXshaf~ 32 i9
~hown with the cylinder 15 containing the fuel-air mixture at the
complet1On of the compression stroke and starS of the po~er
stroke. When the fuel m~xture i8 ignited by A spark fromi the
spark plug, th~ piston 16 starts to move downward in the second
downstrok~ or power ~trok~. The connectlng rod 34 and crank~ha~t
32 a~e shown arranged for the offset position. Both valves 20
and 22 are ~hown in the clo~ed po~it~on. On full movement
through the power stroke, the piston xeaches the po~ition shown
in Pig. 4, and exhaust valve 22 is opened in preparation for t~e
exhaust stroke.
In Fig. 6, the engine 14 with an offset crank~haft 32 is
~hown with the cy}inder 15 as the exhaust gases are leaving. ~he
piston 16 i8 ~hown in the second up~troke or exhaust stroke. ~he
connecting rod 34 and crank6haft 32 are shown arranged for the
of~et position. The exhaust val~e 22 i~ shown in the open posi-
tion.
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2068507
Por starting the engine 14, initial rotation of ~he
crankshaft 32 i8 pro~ided by a starter motor ~not ~hown). The
charge for the electrical ~y6tem i8 maintained by a generator
(not Eihown). Fuel i~ provided to the engine 14 through the car-
S buretor, by a fuel pump (not shown). The fuel is mixed with
air, and the mixture ii introduced into the cylinder 15 for com-
bustion. Any impuritie~ which may b~ present in the fuel are re-
moved by a fuel filter (not shown).
~he overhead camshaft 28 i~ rotated through a gear 38
attacbed at one end which i~ engaged to a timing belt 3~, which
i8 also engaged to, and rotated by, a gear 36 attsched at one end
of the crankshaft 32. The ~ngine 14 has an ignition system (not
gho~n) which includes ~park plugs, spar~ plug wires, distributor,
d~stributor cap, points, and conden~er.
Where contact of metal-to-m0tal ~urfaces occur8, ~ieal$ng
~8 provided by gaskets (not shown) of appropriate material. Shaft
deflection of the crank~haft 32 i8 prevented by the provi3ion of
siuitable bearings. The engine may be water cooled or air cooled.
O~RAT~ON
The operation of the engine 10 ~ith an off~et crank~ihaft
32 should b4 obvious from the description of the preferred em-
bodiment, but wîll be stated herein for clarity.
The operation of the engine 14 with an of~set crank6haft
32 i~ similar to the operation of a standard ~ngine ha~inq a
~our-stroke cycle, or a two-stroke cycle. Combustion occursi in
,
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2~68~07
the cylinder lS, in the upper portion, forcing the piston 16 to
move downward. The pi8ton downward mo~ement moves the connect-
~ng xod 34 downward turn~ng th~ crankshaft 32.
The rotation o crankshaft 32 and movement of pi~ton 16
S i8 seen in F~g~. 3 - 6. At the start of the intake &troke, the
pi3to~ 16 i~ at the upper end of cylinder 15, ~s seen in Fig. 5,
~ut with the intake valve 20 open. Pisto~ 16 moves downward, as
~n Yig. 3, until it reaches the 10we3t po~ition, a~ in Fig. 4,
but with intake ~alve 20 still open.
At thls point, both valves 20 and 22 are closed, as in
Fig. 4, and the piston 16 6tart~ the upstroke for compre~sion and
move~ to the uppermo~t po~ition, as in Fig. 5, which i~ the end
: of th~ compres~ion ~troke. Ignition then takes place, and piston
16 starts downward from the po6ition of Fig. S until it reachos
the po8i~ion of F~g. 4. Exhau8t ~alve 22 then opens and piston
16 mov~8 upward, a~ in Fig. 6, through the exhaust ~tro~e.
~hrough this rotation of crankshaft 32 and movement of
; piston 16, the offset relaSion of the crank6haft and piston re-
8ults in the time for piston travel from the top of the stroke to
the bot~om of the ~troke being greater than the time for the pi~-
ton to return from t~e bottom of the ~troke to the top of the
stroke. The distance th~ piston travels from the top of the
~troke (piston at maximum travel) to the bottom of the stroke
(pi8ton at the bottom of its travel) i~ greater than the diameter
2~ of the cr~nk~haft ~oeatioA. The ~rgle throuqh which the crank-
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2068507
s~Aft mov~g during the downstroke i~ greater than 180. ~he e~-
gine therefor~ has a longer time power stroke than exhau6t
~txoke. The intake cycle i8 }onger in time than the exhaust
cy~le which ~mprove6 a8piration of the engine.
S Fig6. 8 - 12 graph the crankshaft rotation against pi~ton
po~t~on, torqu~, etc. In Fig. 8, pi~ton po~ition i8 graphed
against ~rankshaft rotation for an ~ngine with con~entional
crankshaft and for this invention where the crankshaft is off-
set. It is seen that the angle of movement of the crankshaft
between top and bottom positions of the piston is 180 for the
con~entional crankshaft arrangement and 190.3 for the offset
crank~haft of this invention. This allows a longer t~me power
strok~ and intake 6troke and a shorter time compression ~troke
and exhau~t,stroke.
In F~q. 9, pi8ton velocity i6 graphed against crank~haft
rotation for an engine with conventional crankshaft and for this
in~ention where the crankshaft i8 offset by the length of the
~rank arm. It is ~e~n that the maxLmum downward velocity occur6
at about 165 for the conventional cran~haft arrangement and
180 for the off~et crankshaft of this invent~o~.
In ~ig. 10, piston acceleration i8 graphed against
crankshaft rotation for an ~ngine wîth conventio~al crankshaft
and for thi8 invention where the crankshaft i~ of~et. It is
seen that the maximum acceleration is lower for the off~et cranX-
14
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2068~07
~haft than for the conventional crank~ha~t during the down ~troke
but higher on the upstroke.
In Fig. ll, cran~shaft torgue is graphed against crank-
shaft rotation for an engine with con~entional crank~haft and for
this in~ention where the crankshaft is off~et by the length of
the crank arm. It i6 seen that the maximum torque for the off~et
crankshaft occurs after and i~ lower than the maximum torque for
the conven~ional crankshaft.
In Fig. 12, integrated crankshaft torgue is graphed
agains~ crank~haft rota~ion for an engine with conventional
crankshaft and for this invention whe~e the crank~haft is offset
by the length of the cran~ arm. It i~ ~een that the ~axLmum in-
tegrated torque for the off6et crankshaft occur6 after but i8
egual to ~he total integrated torque of the con~entional engine,
lS both engines having equal ~troke.
While this invention ha8 be~n de~cribed fully and com-
pletely wi~h special emphasi~ upon a preferred embodiment, it
~hould be understood that, within ~h~ scope of the appended
claims, the invention may be practiced otherwise than as spec-
ifically described herein.
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