JP2629757B2 - Engine intake system - Google Patents

Description

Description: Object of the Invention (Industrial Application Field) The present invention relates to an intake device for an engine suitable for supplying an air-fuel mixture having an optimum mixing ratio to the engine in the entire rotation range of the engine.

(Prior Art) Generally, a capleter is disposed in an intake passage connected to an intake port of an engine, and a mixture of air and fuel is produced and supplied to the intake port. The carburetor is configured to generate an air-fuel mixture having an optimum mixing ratio according to the operating condition of the engine by opening and closing a throttle valve.

(Problems to be Solved by the Invention) However, in the case where such an air-fuel mixture is formed by itself, as shown by a broken line C in FIG. 2, the mixture is atomized and supplied at a specific engine speed. The flow rate of the fuel may decrease. As a result, the mixture ratio decreases at this specific rotation speed, and a thin mixture is sent to the intake port of the engine, and the engine output may decrease.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an intake device for an engine capable of supplying an air-fuel mixture having an optimum mixture ratio to the engine in the entire rotation range of the engine and improving the engine output.

(Structure of the Invention) (Means for Solving the Problems) In order to solve the above-mentioned problems, an intake device for an engine according to the present invention includes an intake passage connected to an intake port of a two-stroke engine. A piston valve type carburetor for supplying air-fuel mixture to the port is provided, and a reed valve device is provided near the intake port side in an intake passage between the carburetor and the intake port. A fuel injection device is disposed therebetween, and the fuel injection device is mounted at an angle so that the fuel injector faces the suction side of the reed valve device,
An air-fuel mixture produced by the carburetor is set lower than an optimum air-fuel ratio, and a fuel whose flow rate is controlled is injected from a fuel injection device into the air-fuel mixture to adjust the air-fuel mixture to an optimum air-fuel ratio. It is configured to replenish.

(Action) Therefore, according to the engine intake device of the present invention, the carburetor and the fuel injection device control the mixture ratio of the air-fuel mixture guided to the engine intake port. A decrease in the mixing ratio in the number can be prevented by replenishing the fuel from the fuel injection device, and the air-fuel mixture having the optimum mixing ratio can be supplied to the engine intake port.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of an intake device for an engine according to the present invention together with a two-cycle engine.

A cylinder 3 is fitted in a cylinder block 2 of the engine 1, and a piston 4 is accommodated in the cylinder 3 so as to be able to reciprocate. The piston 4 is connected to a crank 6 via a connecting rod 5, and the crank 6
Reciprocating motion is converted into rotary motion.

The cylinder 3 has an intake port 7, an exhaust port 8, and a scavenging port (not shown). The scavenging port is communicated with the crank chamber 9 connected to the cylinder 3. The intake port 7, the exhaust port 8 and the scavenging port are controlled to open and close by the piston 4.
The exhaust port 8 and the scavenging port are opened at the bottom dead center side, and the intake port 7 is opened at the top dead center side.

A reed valve device 10 is installed in the intake port 7. The reed valve device 10 is formed so as to close the intake port 7 with a V-shaped surface, and has a valve body 12 having an opening 11 formed in the V-shaped surface.
And a valve stopper 14 that limits the lift of the reed valve 13 by opening and closing the opening 11 by contacting the V-shaped surface of the reed valve 13.

In the reed valve device 10, when the piston 4 rises and the pressure in the crank chamber 9 becomes negative, the reed valve 13 opens and the air-fuel mixture is sucked into the crank chamber 9. When the air-fuel mixture burns in the cylinder 3 and the piston 4 descends, the pressure in the crank chamber 9 changes to positive pressure, the reed valve 13 returns to its original position, closes the opening 11, and the air-fuel mixture in the crank chamber 9 is compressed. The compressed air-fuel mixture in the crank chamber 9 is eventually led into the cylinder 3 through the scavenging port.

Further, an intake passage 16 provided with a piston valve type carburetor 15 is connected upstream of the intake port 7. In the intake passage 16, a fuel injector 17 of a fuel injection device is disposed between the carburetor 15 and the intake port 7, and furthermore, between the reed valve device 10. The fuel injector 17 is on the suction side of the reed valve device 10 (near the upstream of the reed valve 13).
It is attached to the intake passage 16 so as to be inclined. With these carburetors 15 and fuel injectors 17,
The mixture is guided to the intake port 7.

The carburetor 15 includes a float chamber 19, a throttle valve 20, a needle jet 21, and a jet needle 22. The float chamber 19 is provided below the carburetor body 18 and has a certain amount of fuel (gasoline).
Store. The throttle valve 20 is provided in the venturi portion of the carburetor body 18, and changes the diameter of the venturi portion by operating the throttle. The needle jet 21 is provided below the throttle valve 20 in the carburetor body 18 and communicates with the inside of the float chamber 19. Further, the jet needle 22 is attached to the throttle valve 20 and inserted into the needle jet 21 to form a gap with the needle jet 21.

In the carburetor 15, the throttle valve 20 is directly operated by operating the throttle, and the carburetor body 18 is operated.
Adjust the amount of air passing through. When the air amount is increased by opening the throttle valve 20, the flow velocity in the venturi increases, and the air pressure in the venturi decreases. Also,
When the throttle valve 20 is opened, the jet needle 22 is raised, so that the gap between the shet needle 22 and the needle jet 21 increases. As a result, a large amount of fuel in the float chamber 19 is ejected to the venturi through the gap between the jet needle 22 and the needle jet 21.

Further, in the carburetor 15, the amount of fuel flow (fuel ejection amount) from the carburetor 15 is adjusted by adjusting the taper amount of the jet needle 22 and the depth of insertion into the needle jet 21 as shown by a dashed line B in FIG. Is set so that the air-fuel mixture produced by the carburetor 15 is lower than the fuel flow rate at which the optimum mixing ratio is obtained, that is, the fuel is poor against air.

On the other hand, the fuel injector 17 is attached to the intake passage 16 so as to be directed in the direction of the reed valve 13. Further, the fuel injector 17 operates based on a signal from a control device (not shown), and injects the fuel pressurized in the delivery pipe 23 into the intake passage 16. As a result, the fuel mixture is further supplied from the fuel injector 17 to the air-fuel mixture produced by the carburetor 15. As shown by the solid line A in FIG. 2, when the fuel injection amount (fuel flow rate) from the fuel injector 17 is added to the fuel flow rate from the carburetor 15, the air-fuel mixture supplied to the intake port 7 is optimally mixed. It is set to be a ratio.

Therefore, according to this embodiment, the carburetor 15 and the fuel injection device 17 control the mixture ratio of the air-fuel mixture guided to the intake port 7, and as shown by the one-dot chain line B in FIG. Even when the fuel flow rate from the carburetor 15 decreases at the rotation speed and the mixture ratio of the air-fuel mixture produced by the carburetor 15 decreases, fuel is supplied from the fuel injector 17 as shown by the solid line A in FIG. As a result, a decrease in the mixture ratio can be prevented, and a mixture having an optimal mixture ratio can be supplied to the intake port 7. Therefore, an air-fuel mixture having an optimum mixing ratio can be supplied to the intake port 7 in the entire rotation range of the engine, and the engine output can be improved.

In the above embodiment, the fuel flow rate from the carburetor 15 is set lower than the case where the air-fuel mixture has the optimum mixing ratio.However, the fuel flow rate from the carburetor 15 is set so that the mixing ratio is optimum as in the conventional case. However, fuel may be supplied from the fuel injector 17 when the flow rate of fuel from the carburetor 15 decreases at a specific engine speed. The control of the fuel injector 17 in this case is performed by a control device (not shown).

〔The invention's effect〕

As described above, according to the engine intake device of the present invention, the piston valve carburetor, the fuel injection device, and the reed valve device are sequentially arranged in the engine intake passage, and the fuel injector of the fuel injection device is connected to the reed valve device. At the same time, the air-fuel mixture is set to be lower than the optimal mixture ratio, and the fuel mixture is injected with fuel whose flow rate is controlled from the fuel injector to adjust the mixture to the optimal mixture ratio. The carburetor and the fuel injector can ensure the optimum mixture ratio, and the carburetor and the fuel injector can maintain the optimum mixture ratio. While fuel is injected from the fuel injector to sufficiently and effectively diffuse the mist of the fuel mixture, Since the injector is oriented so as to face the direction of the intake air flow, the fuel injected from the fuel injector can be efficiently loaded on the intake air flow, and the optimum mixing ratio based on the stoichiometric mixing ratio is secured in the entire engine speed range. It can be supplied to the intake port, and has effects such as an improvement in engine output and an improvement in stability by preventing variation in engine output.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an intake system for an engine according to the present invention together with a two-stroke engine, and FIG. 2 is a graph showing a relationship between a fuel flow rate supplied from a carburetor and a fuel injector and an engine speed. is there. 1 ... engine, 2 ... cylinder block, 7 ... intake port, 15 ... carburetor, 16 ... intake passage, 17 ... fuel injector.

Claims (1)

(57) [Claims] A piston valve carburetor for supplying a mixture of air and fuel to the intake port is provided in an intake passage connected to an intake port of a two-stroke engine, and intake air between the carburetor and the intake port is provided. A reed valve device is provided near the intake port side in the passage, and a fuel injection device is disposed between the reed valve device and the carburetor, and the fuel injection device is inclined such that the fuel injector faces the suction side of the reed valve device. The fuel-air mixture is adjusted to an optimal mixture ratio by injecting fuel whose flow rate is controlled from a fuel injection device into the mixture, thereby adjusting the mixture to an optimal mixture ratio. An intake device for an engine, wherein air is supplied to a two-stroke engine.