Air-fuel mixture supplying device for internal combustion engines

An air-fuel mixture supplying device for internal combustion engines, in which sonic nozzles are disposed facing each other in such a manner that their center lines lie in the same horizontal and vertical planes so that the fuel ejected from the nozzle is pulverized and mixed with bleed air ejected from the opposing nozzle in optimum condition. During intermittent ejection of fuel, two injector valves inject fuel alternately so that the fuel particles ejected from the opposing nozzles do not collide with each other but only strike against and mix with the bleed air. This eliminates the possibility of fuel particles becoming agglomerated and produces desirable air-fuel mixtures.

BACKGROUND OF THE INVENTION 
This invention relates generally to an air-fuel mixture supplying device 
for internal combustion engines and more specifically relates to 
improvements in pulverization of fuel and fuel distribution among 
cylinders of the engine. 
In conventional air-fuel mixture supplying devices as shown in FIGS. 1, 2 
and 3, injector valves 200 and 200' have fuel ejection ports 102 and 102' 
which open to a venturi portion 103 downstream of the throttle valve 101 
and deviate by .epsilon. from each other as best illustrated in FIG. 1. 
The fuel is introduced into the fuel chamber 301 from the passage 303, and 
the return fuel is also introduced to the fuel chamber 301 through the 
passage 304. The fuel in the chamber 301 is then led to the inlets of the 
injector valves 200 and 200' through a passage 305. When the coils 204 and 
204' of the injector valves 200 and 200' are energized, plungers 201 and 
201' are retracted against the force of springs 205 and 205' thereby 
opening the delivery ports 202 and 202' from which a required amount of 
fuel corresponding to the quantity of air drawn into the engine is 
ejected. 
Ejected fuel is pulverized by bleed air in the atomizing chamber and 
further pulverized while passing through sonic nozzles 203 and 203' before 
being ejected from the ejection ports 102 and 102'. 
Since in the conventional method the ejection speed of fuel from ejection 
ports 102 and 102' is large, the ejected fuel does not easily mix with the 
air coming through the throttle valve 101. Further, since the ejection 
ports face each other in such a way that their center lines deviate from 
each other, the pulverized fuel particles strike the internal surface of 
the venturi portion 103 and adhere to it so that the diameters of the 
atomized fuel particles become large before they reach the combustion 
chamber of the engine. This will adversely affect the fuel distribution 
among the cylinders of the engine. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to overcome the above-mentioned 
drawbacks by arranging the openings (outlets) of the sonic nozzles in such 
a manner that they oppose each other and controlling them such that 
air-fuel mixture from one nozzle strikes against bleed air from the 
opposed nozzle. 
This invention is characterized by the fact that openings of the sonic 
nozzles oppose each other with their center lines lying in the same 
vertical plane and at least one nozzle is connected to the fuel injector 
valve. Further, this invention is characterized by the following features: 
the center lines of the openings of the sonic nozzles lie in the same 
vertical and horizontal planes; injectors are used as the fuel injector 
valves; both the opposing openings of the sonic nozzles are connected to 
the fuel injector valves which open alternately or in a staggered relation 
with each other.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described with reference to the 
accompanying drawings. 
In FIG. 4, the injector valve 200 injects a required amount of fuel to the 
engine. The injected fuel mixes with the air introduced through the air 
bleed passage 104 and is pulverized while passing through the sonic nozzle 
203. The atomized fuel is then ejected from the ejection port 102. The 
fuel mixture ejected from the ejection port 102 now collides against the 
bleed air which has been introduced from the air bleed passage 104' and 
accelerated at the sonic nozzle 105, with the result that the fuel mixture 
loses its horizontal velocity and at the same time diffuses in the venturi 
pipe 103. The diffused fuel mixture is then drawn into the combustion 
chamber of the engine while being mixed with the air coming through the 
throttle valve 101. The fuel may be injected either continuously or 
intermittently by the injector valve 200. If the sonic nozzle 105 were not 
provided, the fuel particles atomized by the sonic nozzle 203 would adhere 
to the venturi pipe 103 or combine to form larger fuel particles before 
being mixed with the air. This will not only deteriorate the fuel 
distribution among cylinders in the engine but also reduce the 
accelerating performance of the engine. However, the fuel supplying device 
according to this invention eliminates the above drawbacks and improves 
the fuel distribution among cylinders in the engine since the fuel mixture 
ejected from the ejection port 102 is slowed down and diffused by the 
bleed air ejected from the sonic nozzle 105. 
Referring to FIGS. 5 and 6, the injector valves 200 and 200' inject the 
required quantities of fuel. The injected fuel is mixed with the bleed air 
passing through the air bleed passages 104 and 104', pulverized at the 
sonic nozzles 203 and 203' and ejected from the ejection ports 102 and 
102'. The ejected fuel particles collide with the bleed air ejected from 
the opposing ejection ports 102 and 102' so that the fuel particles lose 
their horizontal speed and are diffused in the venturi pipe 103. While 
being drawn into the engine, the atomized fuel is further mixed with the 
air passing through the throttle valve 101. 
Since the sonic nozzles 203 and 203' are disposed facing each other, the 
bleed air and the fuel particles are ejected against each other from the 
sonic nozzles 203 and 203' to produce the same effect as obtained in the 
air-fuel supplying device shown in FIG. 4. 
The fuel mixture may be injected either continuously or intermittently from 
the injector valves 200 and 200'. 
For an intermittent injection of fuel, the air-fuel supplying device as 
shown in FIGS. 5 and 6 is provided with a driving circuit for injector 
valves 200 and 200' shown in FIG. 8 that actuates these two valves in such 
a manner that they do not inject fuel simultaneously. 
In FIG. 8, a signal synchronous with the engine revolution is emitted from 
an engine revolution detector 402. After the wave form of the synchronous 
signal is shaped by a shaping circuit 403, the signal frequency is reduced 
to one-half by a frequency divider 404. An operational circuit 405 
provides a pulse signal in synchronism with the signal from the frequency 
divider 404, the width of the pulse being proportional to the quantity, 
divided by the number of engine revolutions of air passing through the 
throttle valve 101. The quantity of air that passes through the throttle 
valve 101 is detected by an air quantity sensor 401 which transmits a 
signal to the operational circuit 405. The pulse signal from the 
operational circuit 405 is transferred to a flip-flop circuit 407 and AND 
gates 408 and 408' to alternately actuate injector actuating circuits 406 
and 406'. The pulses for actuating the injector valves are illustrated in 
FIG. 7. 
The injector valves 200 and 200' are so arranged that when the fuel is 
injected intermittently, these two injector valves do not inject fuel 
simultaneously. Therefore, the fuel particles ejected from the ejection 
ports 102 and 102' do not strike against and adhere to one another but 
only collide with the bleed air. This brings forth the same effect as 
obtained in the embodiment shown in FIG. 4 but in a greater degree. 
It is desirable that the diffuse angles of the sonic nozzles 105, 203 and 
203' are between 8.degree. and 22.degree.. While a small diffuse angle 
less than 8.degree. is more effective in accelerating the fuel, the fuel 
particles are more likely to become agglomerated and therefore not easily 
atomized and mixed with air. For a diffuse angle of more than 22.degree., 
it is very likely that ejected fuel particles may adhere to the venturi 
portion 103 without mixing with the bleed air. The sonic nozzles 105, 203 
and 203' may be inclined downwardly as shown in FIG. 2, although the 
horizontally disposed nozzles are most effective in atomizing the fuel by 
the bleed air, as shown in FIGS. 4, 5 and 6. However, if the tilting angle 
with respect to the horizontal plane exceeds 45.degree., the atomizing 
effect will be greatly reduced. 
As can be seen in the foregoing, the air-fuel supplying device according to 
this invention eliminates the aforementioned drawbacks of the conventional 
device and can perform desirable pulverization of fuel so that the fuel 
distribution among the cylinders of the engine is improved.