Starting fuel system for engine

A motorcycle powered by a two cycle crankcase compression fuel injected internal combustion engine. The injection system for the engine includes a main fuel air/injector that injects fuel directly into the combustion chamber and a second or auxiliary fuel injector that injects fuel into the induction system for the engine. Control means control the fuel injectors so that the second or auxiliary fuel injector supplies fuel only during starting and high load, high speed conditions. The engine components are laid out in such a way that the spark plugs of the engine and the fuel injector will each be exposed to unobstructed air flow for cooling.

BACKGROUND OF THE INVENTION 
This invention relates to a starting fuel system for an engine and more 
particularly to an improved arrangement for providing starting fuel to a 
fuel injected two cycle crankcase compression internal combustion engine. 
The advantages of two cycle internal combustion engines in providing not 
only simplicity but high output for a given displacement are well known. 
One main disadvantage to conventional two cycle crankcase compression 
internal combustion engines is their somewhat poor fuel efficiency and the 
undesirable exhaust gas emissions normally associated with such engines. 
To solve or minimize these problems, it has been proposed to provide 
direct cylinder injection for a two cycle engine. By providing direct 
cylinder injection, it is possible to better control the amount of fuel 
consumed by the engine and also to control the amount of undesirable 
exhaust gas constituents. However, when all of the fuel for the two cycle 
engine is delivered by means of a direct injection system, certain 
problems arise. 
One specific problem is that direct injected two cycle engines do not start 
as well as conventional two cycle engines. During starting, even if high 
atomization is possible with direct injection, the fuel may not vaporize 
to the extent necessary to permit good starting with relatively small 
amounts of fuel. In addition, direct cylinder injection may, upon starting 
operation, give rise to a higher than desired exhaust gas emission of 
unburned hydrocarbons. 
In addition, when all of the fuel for a two cycle engine is supplied 
directly to the combustion chamber, problems can occur under high speed, 
high load conditions. Normally a two cycle engine is at least partially 
cooled by the evaporation of the fuel as it flows through the crankcase 
and scavenge passages. When no fuel is delivered through the crankcase 
chamber, then overheating can occur under high load, high speed 
conditions. 
It is, therefore, a principal object of this invention to provide an 
improved fuel injection system for a two cycle crankcase compression 
internal combustion engine. 
It is a further object of this invention to provide an improved arrangement 
for providing starting fuel to a fuel injected engine. 
It is yet another object of this invention to provide a fuel injection 
system for a two cycle crankcase compression internal combustion engine 
wherein fuel may be supplied both directly to the combustion chamber and 
to the engine through its induction system so as to improve starting and 
high speed running while maintaining all of the advantages of direct fuel 
injection. 
SUMMARY OF THE INVENTION 
A first feature of this invention is adapted to be embodied in a fuel 
injection system for a two cycle crankcase compression internal combustion 
engine having an induction system and a combustion chamber to which the 
induction system delivers a charge. A first fuel injector is provided for 
injecting fuel directly into the combustion chamber. A second fuel 
injector injects fuel into the induction system. In accordance with this 
feature of the invention, control means control the operation of the fuel 
injectors so that only the second fuel injector supplies fuel to the 
engine during starting. 
A further feature of the invention is adapted to be embodied in a method 
for operating a fuel injection system for a two cycle crankcase 
compression engine that has an induction system and a combustion chamber 
to which the induction system delivers a charge. First and second fuel 
injectors are provided for injecting fuel directly into the combustion 
chamber and into the induction system, respectively. In accordance with 
this feature of the invention, means are provided for sensing when the 
engine is being started and supplying fuel to the engine for starting 
purposes only by the second fuel injector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
Referring now in detail to the drawings and first initially to FIG. 1, a 
motorcycle powered by an internal combustion engine constructed in 
accordance with an embodiment of the invention is depicted and is 
identified generally by the reference numeral 11. Although the invention 
has utility in conjunction with other applications for internal combustion 
engines, it has particular utility in conjunction with motorcycles since 
such vehicles normally require a compact high power output engine and are 
the type of vehicle commonly powered by two cycle crankcase compression 
internal combustion engines. It will be obvious to those skilled in the 
art that the invention has particular utility in conjunction with the 
powering of motor vehicles and particularly certain features have 
application with vehicles wherein the powering engine is positioned in an 
area where cooling air flows across it. 
The motorcycle 11 is comprised of a frame assembly, indicated generally by 
the reference numeral 12 which may be of any known type and is depicted as 
being of a welded construction having a pair of main frame members 13 that 
diverge downwardly and rearwardly from a head pipe 14. Down tubes 15 are 
fixed to the head pipe 14 and main frame members 13 and extend downwardly 
and terminate at a cradle portion 16. Further tubes 17 extend between the 
lower rear portions of the tubes 16 and the rear portions of the main 
frame members 13. Seat rails 18 are connected to the main frame members 13 
and carry a seat 19 that is designed to accommodate a rider. 
The head tube 14 journals a front fork assembly 21 which is steered by a 
handlebar 22 and which rotatably journals a front wheel 23 at its lower 
end. The front fork assembly 21 may include any type of suspension 
arrangement and also carries a front fender 24 that overlies the front 
wheel 23. 
A trailing arm assembly 25 has a pivotal connection 26 at its forward end 
to the frame assembly 12. A rear wheel 27 is rotatably journaled at the 
rear end of the trailing arm 25 and a suitable suspension element (not 
shown) is provided between the trailing arm 25 and the frame assembly 12 
for controlling the movement of the rear wheel 27 relative to the frame 12 
in a known manner. 
An internal combustion engine, indicated generally by the reference numeral 
28, is supported in the frame assembly 12 in a known manner, by means of a 
plurality of engine supports, one of which is indicated by the reference 
numeral 29. The engine 28 is a two-stroke crankcase compression internal 
combustion engine and, in the illustrated embodiment, includes a cylinder 
block 31 that is inclined generally forwardly and in which one cylinder 
bore, to be described, is provided. Although the invention is described in 
conjunction with a single cylinder engine, it should be readily apparent 
to those skilled in the art how the invention can be employed with 
multiple cylinder engines. A cylinder head 32 is affixed to the cylinder 
block 31 in a known manner. 
The engine 28 also includes a crankcase assembly 33 that is fixed to the 
lower end of the cylinder block 31 and, as is conventional in motorcycle 
practice, contains a change speed transmission having an output shaft 34 
to which a sprocket 35 is affixed. A chain 37 encircles the sprocket 35 
and is driven by it. The chain 37 is entrained around a sprocket 38 
affixed to the rear wheel 27 in a known manner for driving this rear 
wheel. 
The engine 28 is water cooled and there are provided a pair of radiators 39 
that are mounted on opposite sides of the down tubes 15 and through which 
liquid coolant is circulated in a manner to be described. 
The engine 28 is provided with an induction system that includes an air 
intake device 41 positioned rearwardly of the engine 28 within the frame 
12 and which supplies an inlet duct or manifold 42. 
The engine 28 has a forwardly facing exhaust port to which an exhaust pipe 
43 is affixed and which exhaust pipe extends around the side of the engine 
and defines an expansion chamber 44 that communicates with a muffler 45 
through a tail pipe 46. The muffler 45 silences and discharges the exhaust 
gases to the atmosphere through an outlet 47. 
A fuel tank 48 is mounted on the main frame members 13 forwardly of the 
seat 19 and supplies fuel to the engine 28 in a manner which will now be 
described by primary reference to the remaining figures. 
Referring now primarily to FIGS. 2-6, the construction of the internal 
combustion engine 28 will be described. It should be understood that, 
except that hereinafter will be noted, the engine 28 is generally 
conventional in construction and, for that reason, components which are 
conventional will not be described, except insofar as is necessary to 
understand their relationship to the invention. 
As has been noted, the cylinder block 31 is forwardly inclined and defines 
a single cylinder bore, this cylinder bore being shown in FIGS. 3, 5 and 6 
and is indicated generally by the reference numeral 48, being formed by a 
liner inserted into the cylinder block 31. A piston 49 reciprocates within 
the cylinder bore 48 and is connected by means of a connecting rod 51 to a 
throw 52 of a crankshaft 53 that is journaled in the crankcase assembly 33 
in a known manner. 
As has been previously noted, an intake air charge is supplied to the 
engine from the air inlet device 41 and intake manifold 42. The intake 
manifold 42 has positioned within it a throttle valve 54 for controlling 
the engine speed and the communication of the intake manifold 42 with an 
intake port 55 formed in the crankcase 33. A reed type check valve 56 is 
positioned in the intake port 55 for permitting flow into the crankcase 
chamber but precluding reverse flow. 
The charge which has been admitted to the crankcase chamber is compressed 
and then transferred through one or more scavenge passages 57 to a 
combustion chamber 58 formed by the cylinder bore 48, head of the piston 
49 and a recess formed in the cylinder head assembly 32. Fuel is mixed 
with the air, in a manner to be described, and is then fired by means of a 
pair of spark plugs 59 that are mounted in the cylinder head 32 in a 
relationship as best shown in FIGS. 2 and 4. It should be noted that the 
spark plugs 59 are inclined forwardly and are spaced circumferentially 
apart so as to be positioned between the radiators 39 and thus subjected 
to the cooling air flow which flows across the engine 28 from a forward to 
rearward direction, as should be readily apparent. As a result, the spark 
plugs 59 will be well cooled and the flow of air across them will not be 
obstructed by any other component of the engine 28. 
The burned charge is discharged through an exhaust port 61 formed in the 
forward side of the cylinder block 31 and which communicates with the 
exhaust pipe 43 in a known manner. An exhaust control valve 62 may be 
positioned in the exhaust port 61 for controlling the timing at which the 
exhaust port 61 opens in response to engine load or engine speed. 
As has been noted, fuel for the engine 28 is supplied from the fuel tank 
48. A portion of the fuel is supplied directly to the combustion chamber 
58 by a fuel/air injector assembly, indicated generally by the reference 
numeral 63, which is mounted centrally in the cylinder head 32 and between 
the spark plugs 59. As a result of this location, air may freely flow 
across the fuel/ air injector 63 without interference from the spark plugs 
59 and with each of these components being disposed so that no air 
disruption will occur and each will be adequately air cooled. 
The fuel/air injector 63 may be of any known type and receives air under 
pressure, in a manner to be described, and fuel from a fuel injector 64 
that is mounted to the fuel/air injector 63 and which extends in a 
rearward direction therefrom as best shown in FIGS. 3 and 4. The fuel/air 
injector 63 includes a chamber to which the compressed air is delivered 
and also a chamber to which fuel is delivered by the fuel injector 64. 
This fuel and air is then delivered to the combustion chamber 58 upon the 
opening of an injection valve. 
A reciprocating type of air compressor, indicated generally by the 
reference numeral 65 is driven from the engine 28 in an appropriate manner 
and delivers air under pressure to an air manifold 66 which forms a part 
of the air/fuel injector 63. In addition, a high pressure fuel pump, 
indicated by the reference numeral 67 is also driven by the engine and 
delivers fuel to the fuel injector 64. The drive for the air compressor 65 
and fuel pump 67 may be of the type shown in co-pending application 
entitled "Injection Pump Drive for Engine," Ser. No. 742,420, filed Aug. 
8, 1991, in the names of Norihisa Mochizuki and Toshio Kinoshita and 
assigned to the assignee hereof. Of course, other types of air and fuel 
systems may be employed. 
If all of the fuel supply to the engine 28 is supplied by the air/fuel 
injector 63, it has been found that starting may be difficult. In 
addition, there may be inadequate cooling of the engine and particularly 
the under side of the piston 49 and components associated with the 
crankcase 33 under high speed, high load conditions. Therefore, there is 
provided an auxiliary fuel injector 68 that is mounted in the intake 
manifold 42 and which sprays fuel thereinto downstream of the throttle 54 
and immediately upstream of the reed type check valve 56. The injector 68 
may inject pure fuel or may also be a fuel/air injector, if desired. 
A control system (not illustrated) is provided for controlling the amounts 
of fuel delivered by the fuel/air injector 63 and the amount of fuel 
delivered by the fuel injector 68 and also the timing when each injector 
63, 68 supplies fuel. In accordance with a preferred timing strategy, 
means are provided that are responsive to the starting of the engine to 
insure that all starting fuel is supplied only by the fuel injector 68. 
When the engine then begins running and operating at low and low medium 
mid-range performance, the fuel injector 68 supplies no fuel and all of 
the fuel requirements for the engine are supplied by the fuel injector 64 
of the fuel/air injector assembly 63. As the engine moves into high load, 
high speed conditions from the upper mid-range, then the control has the 
fuel injector 68 inject fuel. In one preferred form of strategy, the 
amount of fuel injected by the fuel injector 64 of the fuel/air injector 
63 is held constant at this high load condition and additional fuel is 
supplied by the fuel injector 68 so as to achieve the desired power output 
and speed. Of course, various other strategies may be employed. It is 
important to the invention, however, that the fuel injector 68 supplies 
the only fuel for starting and fuel only during the high speed, high load 
running conditions. 
As has been noted, the engine 28 is liquid cooled and heat is exchanged by 
a pair of side mounted radiators 39. Coolant is delivered from the 
radiators 39 through a conduit 71 to a coolant pump 69 (FIG. 3) that is 
driven from the crankshaft 53. This coolant is then discharged into a 
cylinder block cooling jacket 72 for circulation generally in the 
direction indicated by the arrows in certain of the figures, and 
particularly FIGS. 3, 5 and 6. The coolant flows around the cylinder bore 
49 and enters a cylinder head cooling jacket 73 through ports 74 formed in 
the upper portion of the cylinder block 31. The ports 74 are designed 
primarily so as to create a generally circular flow of coolant around the 
cylinder head 32 as indicated by the phantom line 75 in FIG. 4 so as to 
pass first adjacent the air/fuel injector 63, then the spark plugs 59 and 
exit the cylinder head 32 through an outlet port 76 that communicates with 
a thermostat housing 77 in which a thermostat is positioned so as to 
maintain a uniform and desired temperature for the engine. This water is 
then returned to the radiators 39 through return pipes 78. 
It should be readily apparent, therefore, that the described engine 
construction provides an extremely effective fuel control for a two cycle 
crankcase compression internal combustion engine wherein good fuel economy 
and emission control can be realized and also good cold starting and 
adequate temperature control of the engine can be maintained under all 
running conditions. Of course, the foregoing description is that of a 
preferred embodiment of the invention and various changes and 
modifications may be made without departing from the spirit and scope of 
the invention, as defined by the appended claims.