United States Patent
`
`[19]
`
`Chasteen
`
`[11] Patent Number:
`
`4,901,701
`
`[45] Date of Patent:
`
`Feb. 20, 1990
`
`‘
`
`[54] TWO-CYCLE ENGINE WITH ELECTRONIC
`FUEL INJECTION
`
`[75]
`
`_
`.
`Inventor: Ronald E. Chasteen, Lakesrde, Anz.
`.
`.
`.
`_
`.
`[73] Asmgnee:
`Injection Research Specrahsts, Inc.,
`Colorado Springs, Colo.
`
`4,821,210 4/1989 Howell et a1.
`4,823,290 4/1989 Fasack et al.
`4,843,576 6/1989 Smith et a1.
`
`................. 364/551.0l
`
`..... 364/550
`......................... 364/557
`_
`Primary Examiner—Raymond A. Ne111
`Attorney, Agent, or Firm—Bruce G. Klaas; William P.
`O’Meara
`
`[63]
`
`[21] Appl. No.: 345,081
`[22] Filed:
`AP" 28’ 1989
`.
`.
`Related U-S- Apphcatlon Data
`Continuation of Ser. No. 119,626, Nov. 12, 1987, aban-
`doued.
`Int. C1.4 ....................... F02M 7/00; GOSD 23/00
`[51]
`[52] US. Cl. .................................... 123/478; 364/557;
`236/DIG. 3
`[58] Field of Search ..................... 123/478, 480, 73 A,
`123/65 BA, 333, 502, 440, 492, 489; 364/186,
`550, 557, 510, 555.01; 236/DIG_ 8
`.
`References Cited
`U.S. PATENT DOCUMENTS
`4,411,335 10/1983 Lamkewitz ................... 236/DIG. s
`....... 364/557
`4,607,962
`8/1986 Nagao et a1.
`..
`
`4,675,826 6/1987 Gentry et al.
`.
`364/557
`4»739»492 4/1988 COChran --------
`354/510
`
`i’gi’gg: 3233: 2:33;;t‘81‘”
`33%;?)
`4,763,629
`8/1988 Okazaki et al.
`123/489
`
`4,766,868
`8/1988 Shibata ..............
`123/440
`4,805,122 2/1989 McDavid et a1. ................... 364/557
`
`[56]
`
`ABSTRACT
`[57]
`A fuel injection system for a two-stroke cycle engine
`comprising an air manifold; a throttle valve; 3. fuel injec-
`tor; a fuel supply system including a fuel pump; a bat-
`tery voltage sensor; an air temperature sensor; an engine
`speed sensor; a tirriing sensor; a barometric pressure
`sensor; a “Home P°Siti°n sens“? a fir“ data Pr°°ess°r
`for receiving and Processing sensing signals for deter-
`mining fuel injector duration and timing and fuel pump
`Operating Speed; a first data processor temperature sen-
`sor for sensing the relative temperature of certain elec-
`tronic components in the first data processor; a heater
`operatively associated with the first data processor
`electronic components for selectively heating the elec-
`tronic components; and a second data processor opera-
`ble independently of the first data processor for receiv—
`ing an electronic component temperature sensing signal
`and for generating a control signal to the heater respon-
`sive thereto for heating the components when the tem-
`perature thereof is below a predetermined minimum
`value-
`
`1 Claim, 5 Drawing Sheets
`
`
`READ RPM AND
`W‘oTT : $511”an
`
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`ON FUEL MAPW
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`READ E M INQUT
`VALUES
`
`'MERCEDES
`
`EXHIBIT 1003
`
`MERCEDES
`EXHIBIT 1003
`
`

`

`US. Patent
`
`Feb. 20, 1990
`
`Sheet 1 of 5
`
`4,901,701
`
`0mN
`
`UN;UQKmow NEE
`
`N_
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`
`MERCEDES
`
`EXHIBIT 1003
`
`MERCEDES
`EXHIBIT 1003
`
`

`

`US. Patent
`
`Feb. 20, 1990
`
`Sheet 2 of5
`
`4,901,701
`
`F‘Iaz
`
`Sal
`
`INITIALIZE Poms
`AND FUNCTIONS
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`FROM MOIDIEIEDVVALUE 723
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`315
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`READ T'IMIMG
`SIGNAL.
`
`MERCEDES
`
`EXHIBIT 1003
`
`MERCEDES
`EXHIBIT 1003
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`

`

`US. Patent
`
`Feb. 20, 1990
`
`Sheet 3 of5
`
`4,901,701
`
`M0075 —>—
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`MERCEDES
`
`EXHIBIT 1003
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`MERCEDES
`EXHIBIT 1003
`
`

`

`
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`Feb. 20, 1990
`
`Sheet 4 of 5
`
`4,901,701
`1
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`MERCEDES
`
`EXHIBIT 1003
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`MERCEDES
`EXHIBIT 1003
`
`

`

`US. Patent
`
`Feb. 20, 1990
`
`Sheet 5 of5
`
`4,901,701
`
`
`
`
`cu77007“(M4773/N#EArEeELEME/W') 01
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`flag,
`
`MERCEDES
`
`EXHIBIT 1003
`
`MERCEDES
`EXHIBIT 1003
`
`

`

`1
`
`4,901,701
`
`TWO-CYCLE ENGINE WITH ELECTRONIC FUEL
`INJECTION
`
`The present application is a continuation of US. pa-
`tent application Ser. No. 119,626 filed Nov. 12, 1987.
`‘ BACKGROUND OF THE INVENTION
`
`The present invention relates generally to two-stroke
`operating cycle engines and, more particularly, to a
`two-stroke engine fuel injection system and control
`system therefor which are adapted for extreme weather
`conditions.
`Two-stroke operating cycle engines (two-cycle en-
`gines), although less fuel-efficient than four-stroke oper-
`ating cycle engines (four-cycle engines), are capable of
`developing greater horsepower and torque than a com-
`parably-sized four-cycle engine. This feature has led to
`the use of two-cycle engines in many environments in
`which operating efficiency is secondary to torque and
`weight considerations.
`injection is widely
`Electronically-controlled fuel
`used in four-cycle engines. In electronic fuel injection
`used in four-cycle engines, sensor readings associated
`with various engine operating parameters are used to
`calculate an optimum fuel/air mixture for the engine.
`Fuel is then injected directly into the engine’s cylinders
`in the proper amount based upon this electronically
`determined fuel/air mixture. In some four-cycle engine
`fuel injection systems, the fuel is injected into an air
`plenum upstream of the cylinder and is subsequently
`allowed to enter the cylinder with the plenum air
`through operation of an intake valve. Electronic fuel
`injection systems have replaced conventional carbure-
`tors in many four-cycle engines, especially in the auto-
`motive industry. However, fuel injection is not in gen-
`eral use with two-cycle engines and has not heretofore
`been used wit_h small-displacement two-cycle engines
`which are used under severe cold weather conditions,
`for a number of reasons. Small two-cycle engines are
`used in association with equipment that is relatively
`inexpensive as compared to automobiles and other ma-
`chines with which electronic fuel injection has been
`widely used in the past. In relatively large, expensive
`machinery, the cost associated with modifying basic
`engine components to enable internal mounting of vari-
`ous engine parameter sensors may be justified by in-
`creased fuel savings and engine performance and may
`amount to a relatively small portion of the purchase
`price of such an automobile, etc. In smaller engine envi-
`ronments, the cost of internal engine modification to
`existing engine assemblies would,
`in most cases, far
`outweigh any fuel savings which might be achieved by
`an electronic fuel injection unit and would represent a
`substantial increase in the cost of the associated small
`machine, e.g. snowmobile, dirt bike, etc., powered by
`the two-cycle engine.
`Fuel injection systems without electronic controls
`have bEen used on two-cycle engines, but have not been
`satisfactory on small-displacement, small-mass two-cy-
`cle engines. The reason that fuel injection without elec-
`tronic control has not been used successfully in small
`two-cycle engines is that such engines lack flywheels
`and other high-mass rotating components which tend to
`stabilize engine operation. Dueto this lack of a large
`rotating mass in such engines, even a short duration
`mismatch between the rate at which fuel is actually
`delivered to the engine and the optimum engine fuel
`
`10
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`rate requirements will cause engine sputter or rapid
`deceleration and stalling. Small, two-cycle engines are
`especially subject to malfunction under variable operat-
`ing conditions such as changes in sea level, with associ-
`ated barometric changes and changes in ambient air
`temperature. Many machines such as snowmobiles,
`snowblowers, dirt bikes, etc., are operated in such
`widely variable operating conditions. In view of the
`costs associated with engine modification for sensors’
`need for electronic control of fuel injectors and in view
`of the fact that the engine parameters which are critical
`to control of fuel injectors for two-cycle engines were
`not, prior to the present invention, understood in the
`art, a successful electronically-controlled fuel injection
`system for small, two-cycle engines which are subject
`to extremes in operating conditions has not been devel-
`oped in the prior art.
`OBJECTS OF THE INVENTION
`
`It is an object of the present invention to provide an
`electronic fuel injection system for a two-cycle engine
`which requires no internal modification to the basic
`engine assembly.
`It is another object of the present invention to pro-
`vide an electronic fuel injection control system which
`may be readily adapted for use with any conventional
`two-stroke cycle engine assembly.
`It is another object of the present invention to pro-
`vide a relatiVely small two-stroke cycle engine with
`electronic‘ fuel injection which is capable of operation
`under variable and extreme conditions of air tempera-
`ture and under widely varying barometric pressure
`conditions.
`'
`It is another object of the present invention to pro-
`vide a fuel injection system for a two-cycle engine in
`which fuel injection takes place in an air manifold.
`It is another object of the present invention to pro--
`vide a fuel injection and control system for a two-cycle
`engine in which all fuel injectors simultaneously inject
`fuel into portions of an air manifold which are associ-
`ated with individual cylinder/crankcases.
`It is another object of the present invention to pro-
`vide a control system for a electronic fuel injection
`system which utilizes relatively inexpensive electronic
`components and which is not subject to electronic com-
`ponent malfunction associated with low-temperature
`operation.
`It is another object of the present invention to pro-
`vide an electronic fuel injection system for a two-cycle
`engine which includes an electronically-stored fuel map
`indicative of the optimum fuel requirements for the
`engine under standard operating conditions over vari-
`able engine speed conditions and variable throttle con-
`ditions.
`It is another object of the present invention to pro-
`vide an electronic fuel injection system which provides
`a selected set of operating condition sensor inputs
`which do not require internal engine unit modifications
`and which provide optimized engine performance.
`SUMMARY OF THE INVENTION
`
`The present invention is directed to an electronic fuel
`injection system for a small two-cycle engine. One as-
`pect of the invention is a temperature control assembly
`which is operably associated with an electronic central
`processing unit of the type having electronic compo-
`nents which are subject to malfunction under low tem-
`perature conditions. The electronic components of the
`
`MERCEDES
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`

`

`4,901,701
`
`3
`heating assembly are not subject to malfunction under
`low temperature conditions and are designed to pro-
`duce a heating response which is inversely proportional
`to temperature below a predetermined threshold tem-
`perature. The heating assembly is preferably mounted
`within a relatively small enclosure which also houses
`the electronic control system central processing unit.
`The heating assembly senses the temperature within the
`relatively small enclosure and rapidly heats electronic
`components within the relatively small enclosure to a
`predetermined temperature in response to sensing an
`environmental temperature within the enclosure which
`is below the predetermined temperature. The heating
`system may be actuated at the same time the electronic
`control system is actuated such as by the turning of the
`ignition switch of an associated machine, such as a
`snowmobile, etc.
`Another feature of the present invention is th provi-
`sion of an electronically-controlled fuel injection sys-
`tem which has a plurality of sensor inputs which are
`limited to the sensor inputs which are critical to the
`operation of a two-cycle engine and which may be
`mounted externally of a main engine assembly compris-
`ing a cylinder crankcase, piston, and crankshaft exclu-
`sive of the carburetion/fuel injection system therefor.
`The electronically-controlled fuel injection system of
`the present invention may thus be used without modifi-
`cation of existing two-cycle engine assemblies and is
`controlled by a CPU which may include a programma-
`ble memory device such as an EPROM which may be
`selectively programmed for any particular engine as-
`sembly with which the electronic fuel injection system
`is to be used. Another feature of the invention is the
`injection of fuel from a fuel injector into a portion of an
`air manifold which is in direct fluid communication
`with the crankcase portion of each individual cylinder/-
`crankcase assembly. This injection of fuel into a mani-
`fold upstreanLof a crankcase provides mixing of a pre-
`cise amount of fuel and air prior to entry of fuel into the
`crankcase and also enables all
`fuel
`injectors to be
`opened and closed simultaneously, rather than being
`timed to the operation of each associated piston.
`Thus, the present invention may comprise a control
`system for controlling the operation of a machine de-
`signed to be operated in a relatively broad air tempera-
`ture, comprising: (a) at least one performance variable
`sensing means for sensing the present state of a prese-
`lected variable associated with machine performance
`and for generating a performance variable sensing sig-
`nal indicative of said present state of said preselected
`performance variable; (b) a first data processing means
`for receiving and processing said performance variable
`sensing signal and for generating a control signal based
`upon the processing of said sensing signal for control-
`ling at least one operating parameter of said machine;
`said data processing means comprising at least one tem-
`perature-sensitive electronic circuit component which
`is subject to malfunction below a predetermined mal-
`function temperature which is within said relatively
`broad operating temperature range of said machine; (c)
`component environment temperature sensing means for
`sensing the temperature within the immediate operating
`environment of said temperature-sensitive electronic
`circuit component and for generating a temperature
`signal representative of the sensed temperature; (d) a
`second data processing means which operates indepen-
`dently of said first data processing means and which is
`not subject to temperature-related malfunction within
`
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`said operating temperature range of 5 id machine for
`processing said signal from said component environ-
`ment temperature sensing means and generating a heat-
`ing control signal responsive thereto when the tempera-
`ture in said electronic circuit environment is sensed to
`be below said predetermined malfunction temperature;
`(e) heating means responsive to said heating control
`signal for heating said temperature sensitive electronic
`component environment
`in response to said control
`signal; (f) power supply means for providing electric
`energy for operating said control system; (g) switch
`means for selectively operably electrically connecting
`or disconnecting said energy supply means and electri-
`cally operated components of said control system.
`The present invention may also comprise a fuel injec-
`tion system for a two-stroke cycle engine of the type
`comprising at least one cylinder, a crankcase associated
`with said cylinder, a piston reciprocally mounted in said
`cylinder and crankcase; a reciprocally openable and
`closable crankcase inlet for enabling combustible fluid
`to be drawn into the crankcase, a reciprocally openable
`and closable transfer port for transferring combustible
`fluid compressed in said crankcase to said cylinder, an
`ignition system for igniting compressed combustible
`fluid in said cylinder, a reciprocally openable and clos-
`able exhaust port in said cylinder for enabling exhaust of
`burned combustible fluid from said cylinder, a crank-
`shaft connected to said piston for transferring mechani-
`cal energy from said piston to a drive unit, and an elec-
`trical energy supply source including a battery for oper-
`ating the ignition system and other electrical compo-
`nents, comprising: (a) air manifold means operably asso-
`ciated with said crankcase inlet; (b) throttle valve means
`operably positioned in said air manifold means for con-
`trolling airflow into said crankcase inlet, said throttle
`valve means dividing said manifold means into an up-
`stream portion positioned remote from said crankcase
`inlet and a downstream portion positioned contiguously
`with said crankcase inlet; (0) fuel injection means for
`injecting a fine spray of fuel into said downstream por-
`tion of said manifold means whereby a mixture of air
`and fuel is provided in said downstream portion of said
`manifold means which is subsequently drawn into said
`crankcase through said crankcase inlet; (d) fuel supply
`means for supplying fuel to said fuel injection means
`comprising: (i) fuel reservoir means for holding a vol-
`ume of fuel therein and having a reservoir inlet and a
`reservoir outlet; (ii) fuel circulation conduit means for
`transferring fuel from said fuel reservoir to said fuel
`injection means comprising a first end inlet
`in fluid
`communication with said fuel reservoir outlet, a second
`end outlet in fluid communication with said fuel reser-
`voir inlet and an interrnediately positioned fuel injection
`outlet positioned in fluid communication with said fuel
`injection means; (iii) fuel pump means operatively asso-
`ciated with circulation conduit means at a position
`thereon between said conduit means first end inlet and
`said conduit means fuel injector outlet for pumping fuel
`through said circulating conduit; (iv) pressure limiting
`regulator means operatively associated with said circu-
`lation conduit means at a position thereon between said
`conduit means fuel
`injector outlet and said conduit
`means second end outlet for preventing pressure in said
`conduit means from exceeding a predetermined maxi-
`mum pressure; (e) battery voltage sensing means for
`sensing battery voltage and for providing a battery
`voltage sensing signal representative thereof; (0 air
`temperature sensing means for sensing the temperature
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`MERCEDES
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`4,901,701
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`6
`ing means for receiving said electronic component tem-
`' perature sensing signal and for generating a control
`signal to said heating means responsive to said compo-
`nent temperature sensing signal for heating said compo-
`nents when the temperature thereof is below a predeter-
`mined minimum value.
`
`5
`of air in said upstream portion of said manifold means
`and for providing an air temperature signal representa-
`tive thereof; (g) engine speed sensing means for sensing
`the speed of revolution of said engine and for providing
`an engine speed signal representative thereof; (h) timing
`sensing means for sensing each occurrence of a prede-
`termined cyclically repeating state of said engine and
`for providing a timing signal indicative thereof; (i) baro-
`metric pressure sensing means for sensing atmospheric
`air pressure and for generating a barometric pressure
`sensing signal representative thereof; (j) throttle posi-
`tion sensing means for; sensing the relative amount of
`opening of said throttle valve means and for generating
`a throttle position signal representative thereof; (k) first
`data processing means for receiving and processing said
`sensing signals comprising: (i) means for processing said
`engine speed sensing signal and said throttle position
`sensing signal and for generating a priming control
`signal to said fuel injection means for selectively inject-
`ing or not injecting fuel into said manifold means based
`on said engine speed signal and said throttle position
`signal; (ii) means for receiving and processing said en-
`gine speed signal and throttle position signal for deter-
`mining a base fuel injection value; (iii) means for receiv-
`ing and processing said air temperature signal and cal-
`culating an air temperature modification value of said
`base fuel injection value; (iv) means for receiving and
`processing said barometric pressure sensing signal for
`calculating a barometric pressure modification value of
`said base fuel injection value; (v) means for receiving
`and processing said engine temperature signal for calcu-
`lating an engine temperature modification value of said
`base fuel injection value; (vi) means for determining a
`total fuel injection value representative of the total fuel
`amount which is to be injected by said fuel injection
`means during a single two-stroke operating cycle of said
`piston from said base fuel injection value, said air tem-
`perature modification value, said barometric pressure
`modification value, and said engine temperature modifi-
`cation value; '(vii) means for determining an injector
`open duration interval based on said total fuel injection
`value and a known fuel output rate capacity of said fuel
`injection means; (viii) means for generating a control
`signal for opening said injection means for said deter-
`mined injector duration open interval at a predeter-
`mined point in time determined from said timing sensing
`signal; (ix) means for receiving and processing said
`engine speed signal for overridingly terminating fuel
`injection means operation in response to an engine
`speed sensing signal indicative of a predetermined maxi-
`mum speed and for restoring fuel injection means opera-
`tion in response to an engine speed sensing signal indica-
`tive of a predetermined restore operation speed lower
`than said predetermined maximum speed; (x) means for
`receiving and processing said engine speed sensing sig-
`nal and for generating a pump control signal in response
`thereto for maintaining said pump at an optimum oper-
`ating speed for providing said predetermined maximum
`operating pressure in said fuel circulation conduit
`means at said pump; (1) first data processing means tem-
`perature sensing means for sensing the relative tempera-
`ture of certain electronic components in said first data
`processing means and providing a component tempera-
`ture sensing signal indicative thereof; (m) heating means
`operative associated with said first data processing
`means electronic components for selectively heating
`said electronic components; (n) second data processing
`means operable independently of said first data process-
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`BRIEF DESCRIPTION OF THE DRAWING
`
`An illustrative and presently preferred embodiment
`of the invention is shown in the accompanying drawing
`in which:
`FIG. 1 is a schematic illustration of a two-stroke
`cycle engine with electronically-controlled fuel injec-
`tion.
`FIG. 1A is a schematic illustration of the engine of
`FIG. 1 showing additional cylinder portions thereof.
`FIG. 2 is a flow chart illustrating operations of the
`electronic control unit of the present invention includ-
`ing the operation of the central processing unit and also
`the operation of a central processing unit temperature
`control assembly.
`FIG. 3 is a diagram illustrating sensor inputs and
`control signal outputs and basic functions performed by
`an electronic control unit.
`FIG. 4 is a typical engine fuel map expressed in rect-
`angular coordinates.
`FIG. 5 is a schematic illustration of an electronic
`control unit for a fuel injection system.
`FIG. 6 is a graph of heater output as a function of
`CPU temperature for a typical CPU temperature con-
`trol assembly of the type illustrated in FIG. 5.
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`A two-stroke engine unit 10 of the present invention
`is shown schematically in FIG. 1. In general, the two-
`stroke cycle engine unit 10 comprises an engine assem-
`bly 12, an ignition assembly 14, a fuel/air input assembly
`16, an electronic control assembly 18 and an electrical
`power supply assembly 20.
`ENGINE ASSEMBLY
`
`The engine assembly 12 illustrated in FIG. 1 is of a
`type which is conventional and well known in the art.
`The engine assembly comprises a cylinder cavity 30
`which is generally referred to in the art simply as a
`cylinder. The cylinder cavity is defined by a cylindrical
`sidewall 32 and a circular top wall 34 which is fixedly
`attached to the sidewall 32. The engine assembly also
`comprises a generally pear-shaped crankcase cavity 36
`which is generally referred to in the art simply as a
`crankcase. The crankcase cavity is defined by a crank-
`case sidewall 38 which is fixedly connected at the upper
`portion thereof to a lower portion of cylindrical side-
`wall 32. The crankcase wall is fixedly connected at a
`lower portion thereof to a base plate 40. The cylindrical
`cavity 30 and crankcase cavity 36 thus provide the
`upper and lower portions of a continuous total engine
`cavity. A cylindrical piston 42 is slidingly mounted in
`cylindrical cavity 30 and is pivotally attached to a con-
`necting rod 44 which is, in turn, pivotally attached to a
`portion of crankshaft 46 which rotates, as indicated at
`47, about a crankshaft central axis of rotation 48. The
`reciprocal motion of piston 42 within cylinder 30 is
`transferred by connecting rod 44 and crankshaft 46 to a
`conventional drive assembly 50 of an associated ma-
`chine such as, for example, a snowmobile 12.
`
`(
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`MERCEDES
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`EXHIBIT 1003
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`MERCEDES
`EXHIBIT 1003
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`7
`A fuel/air mixture which is sometimes referred to
`herein as combustion fluid or combustion material is
`drawn into the crankcase 36 through a combustion fluid
`inlet 52 sometimes referred to herein as an intake port
`52. The intake port 52 is positioned at an upper portion
`of crankcase 36 and is cyclically opened and closed by
`reciprocation of piston 42. Transfer passages 54, 56,
`etc., having crankshaft transfer passage openings 58, 60,
`etc., and cylinder transfer port openings 62, 64, etc.,
`enable transfer of compressed combustion fluid within
`the crankcase 36 to the cylinder 30. The cylinder trans-
`fer passage openings 62, 64, etc., are cyclically opened
`and closed through reciprocal motion of piston 42. A
`cylinder exhaust gas outlet 66 sometimes referred to
`herein as exhaust port 66 is provided in the cylinder
`sidewall 32 to discharge burned combustion fluid from
`cylinder 30. Exhaust port 66 is also cyclically opened
`and closed by reciprocation of piston 42. The engine
`assembly may comprise a plurality of cylinder/crank-
`case/piston assemblies identical
`to those described
`above which are operably connected to common crank-
`shaft 46.
`
`The mechanical operation of the two-cycle engine
`assembly, in general, is as follows. During upward mo-
`tion of piston 42, crankcase intake port 52 is progres-
`sively opened and cylinder transfer passage openings
`62, 64 and cylinder exhaust port 66 ar progressively
`closed causing fuel/air mixture to be drawn into crank-
`case 3 through port 52 and causing fluid air mixture in
`cylinder 30 to be retained therein and progressively
`compressed. When the piston 42 reaches approximately
`its upward limit of motion or “top dead center”
`(T.D.C.), sparkplug 70 ignites the fuel/air mixture driv-
`ing piston 42 downwardly. During the downward
`movement of the piston, cylinder exhaust port 66 is
`progressively opened, cylinder transfer port openings
`62 and 64 are progressively opened and crankcase inlet
`52 is progressively closed causing fuel/air mixture
`within the crankcase to be compressed and forced
`through the transfer passages 54, 56 into cylinder 30.
`Theinflow of fresh fuel/air mixture into cylinder 30 is
`physically channeled into the cylinder in a manner to
`drive out burned exhaust gas within the cylinder out
`through exhaust port 66. During the subsequent upward
`movement of the piston 42, the abovedescribed cylinder
`fuel/air compression and crankcase fuel/air intake is
`again repeated, etc.
`
`Ignition Assembly
`
`Ignition assembly 14 comprises a conventional spark-
`plug mounted within cylinder 34 for igniting the fuel-
`/air mix therein. Sparkplug 70 is conventionally con-
`nected to an ignition coil 72 which is, in turn, conven-
`tionally connected to an electrical power supply 20 and
`conventional timing apparatus 74 which may be con-
`ventionally linked to crankshaft 46. In an engine assem-
`bly with a plurality of cylinder/ctankcase/piston as-
`semblies, each cylinder is provided with a spark plug.
`
`Fuel Air Input Assembly
`Fuel air input assembly 16 includes an air manifold 80
`mounted in fluid communication with crankshaft intake
`port 52. A throttle valve 82, which in a preferred em-
`bodiment comprises a conventional butterfly valve,
`divides the air manifold 80 into an upstream portion 84
`which is in fluid communication with atmospheric air 8
`through conventional air filters, etc. (not shown) and a
`downstream manifold portion 86 which opens directly
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`4,901,701
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`into crankcase 36. In the case of a multiple cylinder
`engine, there may be a single manifold upstream portion
`and a plurality of downstream portions, one for each
`cylinder/crankcase. An electrically operated fuel injec-
`tor 92 comprising a solenoid valve portion 94 and a gas
`jet nozzle portion 96 is mounted so as to discharge a gas
`spray into the downstream manifold portion 86 to pro-
`duce a fuel/air mixture in the downstream manifold
`portion which is subsequently drawn into crankcase 36.
`The fuel injector may be of a convention commercially
`available type such as Bosch 280150-007 available from
`the Robert Bosch Company, or NAPA 217514 available
`from Echlin, Inc., Branfort, Conn., 06405. The fuel
`injector 92 is connected at
`the solenoid valve end
`thereof to a fuel circulation conduit 98 which is in fluid
`communication with a fuel reservoir 102 in fuel tank
`100. The fuel circulation conduit comprises a conduit
`first end 104 connected to a fuel tank outlet 106 and a
`second end 108 connected to a fuel tank return inlet 110.
`
`An electric fuel pump 112 is provided for pumping fuel,
`such as gasoline, through the conduit 98. The electric
`fuel pump 112 is operably connected in fluid communi-
`cation with the conduit at a point thereon between the
`fuel tank outlet 106 and the fuel injector 92. Conven-
`tional speed control circuitry 113 is provided to control
`the relative pumping speed of the fuel pump in response
`to a signal from the electronic control assembly 18 as
`discussed in further detail below. The fuel pump is con-
`ventionally connected to the electrical power supply
`assembly ‘20 from which it draws its operating energy.
`A conventional mechanically operated pressure limit-
`ing regulator 114 is operatively mounted in the fuel
`circulation conduit at a point between the fuel injector
`92 and the fuel tank return inlet 110. Pressure regulator
`114 prevents the fluid pressure in the circulating con-
`duit from exceeding a predetermined maximum pres-
`sure which may be, e.g. 42 psia. A conventional coarse
`fuel filter 116 may be provided in the circulating con-
`duit between fuel tank outlet 106 and fuel pump 112. A
`conventional fine fuel filter 118 may be provided in the
`circulating conduit between the fuel pump and injector
`92. As shown in phantom in FIG. 1,
`the above-
`described fuel system may be employed to provide fuel
`to further fuel injectors 120, 122 which are attached in
`fluid communication with the circulating conduit be-
`tween the first fuel injector 92 and the pressure regula-
`tor 114. These fuel injectors 120, 122 may be mounted in
`manifold assemblies which may be identical to manifold
`assembly 16 described above and which are in turn
`associated with ignition assemblies and cylinder/crank-
`case piston assemblies 121, 123 which may be identical
`to those described above and which may be operably
`connected