JPS5911728B2 - 4 cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-stroke engine that prevents fuel blow-by, increases combustion efficiency, and also enables supercharging of the air-fuel mixture.

Generally, a 4-cycle engine has an exhaust hole and an intake hole in the cylinder head, sucks in a mixture of fuel and air from the intake hole, and exhausts combustion gas from the exhaust hole, and the piston is at top dead center. The exhaust valve and intake valve are both open for a short period of time in the front and rear, resulting in what is called "valve overlap".
It is common to provide

Therefore, it was not possible to avoid a so-called blow-out phenomenon in which a part of the air-fuel mixture taken in through the air hole does not remain in the cylinder, but instead passes through the cylinder as it is and exits into the exhaust hole. The reason for the need for valve overlap is for both the exhaust and intake valves. In other words, in order to complete the exhaust as much as possible, the lift-time area of the exhaust valve should be increased.
In order to start closing as late as possible and draw out the combustion gases remaining at the top of the cylinder by using the negative pressure created by the energy of the flow in the exhaust pipe, it is necessary to I need to close it later. That is,
Ideally, it should be closed when the piston begins to descend and the negative pressure in the cylinder and the negative pressure in the pipe due to exhaust gas outflow are exactly the same. Also, if the intake valve starts to open at the same time as the exhaust valve closes or later than this, the negative pressure applied to the piston will act as a brake, resulting in large energy loss and poor operating conditions. . Furthermore, due to the inertia of the air-fuel mixture, when the valve begins to open, no gas flow occurs immediately, and the period corresponding to a certain crank angle is a so-called ineffective angle period. Therefore, it is necessary to provide valve overlap for a period corresponding to a certain crank angle. If this overlap period is set to be optimal for engine backfire conversion, the blowout phenomenon will be severe at low engine speeds, and conversely, if it is set to be optimal at low engine speeds, sufficient output will be generated for backfire conversion. There was a drawback that I could not get it.

The present invention can prevent the blow-through phenomenon at low engine speeds even if the valve overlap is set to be optimal for backfire conversion, and also has a supercharging effect by compressing the air-fuel mixture and injecting it into the cylinder. Therefore, it is an object of the present invention to provide a four-stroke engine that can increase the output of the engine.

FIG. 1 is a schematic diagram showing the present invention 0-Embodiment, and 1
is the cylinder, 2 is the piston, and 3 is the cylinder head.
An exhaust hole 5 that opens and closes with an exhaust valve 4, an air intake hole 7 that opens and closes with an empty air valve 6, and a mixture hole 9 that opens and closes with a mixture valve 8 are provided.
An exhaust pipe 10, an air conduit 11, and an air mixture conduit 12 are connected to each of the above holes.

This air-fuel mixture conduit is equipped with a piston-type, roots-type, etc. compressor 1.
3 is connected to the carburetor 14 through this.
FIG. 2 illustrates the timing of exhaust, intake, and mixture supply corresponding to the crank angle when the engine of FIG. 1 is rotated one stroke, that is, 720 degrees.

In this case, intake means taking in only air, and mixture refers to a mixture of fuel and air. Now, let P be the point corresponding to top dead center when moving to the intake stroke.As mentioned above, the human exhaust valve closes after a crank angle θ1 from this point, and the air valve closes after a crank angle θ2. There is an overlap of the valves (θ, +θ2) for the exhaust valve to start opening at point F, but only nitrogen is supplied and no air-fuel mixture is supplied until the exhaust valve closes at point F, so there is a risk of blow-by phenomenon. There isn't. When the piston 2 descends from the top dead center P, nitrogen is sucked into the cylinder 1 from the nitrogen suction hole 7, and then the piston 2 passes the top dead center Pa and enters the compression stroke. When the point is reached, the air valve 6 is closed.

The air-fuel mixture valve 8 opens at point C (at the end of the air intake stroke), which is slightly earlier than the air valve 6 closes, and the air-fuel mixture from the carburetor 14 is forced into the cylinder 1 by the compressor 13. Of course,
Since this mixture mixes with the air from the air intake hole 7,
It is concentrated in advance and mixed with the air from the air intake hole 7 to achieve an optimal mixing ratio. The mixture valve 8 is operated during the compression stroke.
It closes at point D, and thereafter the air-fuel mixture supplied into the cylinder 1 is compressed by the rise of the piston 2, and when the piston 2 approaches top dead center Pb, the fuel is ignited by an ignition plug (not shown), and the explosion stroke begins. Move. Then, the piston 2 becomes near the bottom dead center Pc. The exhaust valve 4 opens and the piston 2
When the cylinder 1 passes the bottom dead center Pc and enters the exhaust stroke, the combustion gas in the cylinder 1 is discharged from the exhaust hole 5. Furthermore, when the piston 2 approaches the top dead center P when it moves to the suction stroke again, the air valve 6 opens, and the air sucked into the cylinder 1 from the air suction hole T completely transfers the combustion gases into the cylinder 1. Let it drain. At this time, as described above, only air is supplied into the cylinder 1, so there is no room for fuel to blow through. In addition, in the present invention, the melon mixture is transferred to the compressor 1.
3, it is possible to produce a so-called supercharging effect, thereby improving the output of the engine.

Since the present invention has the above-described structure and operation, it is possible to completely prevent the fuel blow-by phenomenon, and as a result, the harmful components such as hydrocarbons in exhaust gas are significantly reduced, contributing to pollution prevention. It is.

Since the air-fuel mixture is compressed and injected into the cylinder, a supercharging effect can be expected and the output of the engine can be increased. Furthermore, it is possible to freely set when the exhaust valve closes and when the air valve opens. Furthermore, since the air-fuel mixture is fed under pressure by a compressor after air is supplied to the cylinder, the air-fuel mixture tends to form a layer within the cylinder. This is because the air valve opens at the beginning and only air is sucked into the cylinder, so even if this is stirred, there is no effect, and then, near the end of the nitrogen intake stroke, the mixture valve is forced and the mixture is mixed. This is due to the fact that the air-fuel mixture component after (above) the air component tends to maintain a layered state. In this way, the air and mixture are formed in layers K, . Moreover, if the air-fuel mixture that enters later is located near the spark plug, even after compression, the air-fuel mixture components will remain near (above) the spark plug, making it easier to ignite (the cylinder as a whole will be a lean burner). )
This ignition flame spreads over the entire compressed area, preventing irregular combustion and knocking. If lean combustion becomes possible in this way, combustion efficiency will improve. Furthermore, since the mixture zero injection is performed at the end of the air intake stroke, it is easier to set the timing for opening the mixture valve, etc.
It has many effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of a four-stroke engine according to the present invention, and FIG. 2 shows exhaust, intake, and
FIG. 3 is a diagram illustrating the timing of supplying a mixture. 3... Cylinder head, 4... Exhaust valve, 5... Exhaust 6... Air valve, 7... Air suction element 1-8...
Mixture valve, 9...Mixture hole.

Claims (1)

[Claims] 1. The cylinder head is provided with an exhaust hole, an air intake hole, and a mixture hole that are respectively opened and closed by an exhaust valve, an air valve, and a mixture valve, and the air valve opens before the top dead center of the piston before the exhaust valve closes; The air-fuel mixture valve is set to close near the bottom dead center, and the air-fuel mixture valve opens near the end of the air suction stroke of the air valve to inject the compressed rich air-fuel mixture into the cylinder. cycle engine.