JPH01159463A - Intake system for engine - Google Patents

Abstract

PURPOSE:To make an air-fuel mixture in optimum ratio feedable in all driving ranges by setting up a carburetor and a fuel injection device in a suction passage, and constituting fuel so as to be supplied to the air-fuel mixture generated in the carburetor by injection out of the fuel injection device. CONSTITUTION:In an intake port 7 being opened or closed by a piston 4 in a two-cycle engine 1, there is provided with a lead valve device 10 with a lead valve 13 to be opened when the piston 4 goes up and a crankcase 9 comes to negative pressure. In addition, a suction passage 16, where a carburetor 15 is set up, is connected to an upstream of the intake port 7. In this case, a fuel injector 17 is set up between the carburetor 15 in the suction passage 16 and the intake port 7. When a fuel flow rate out of the carburetor 15 in specific rotational frequency of the engine 1 is decreased and thereby the ratio of an air-fuel mixture is lowered, a fuel supply takes place from the fuel injector 17 whereby drop in the air-fuel mixture is prevented from occurring.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides an engine intake 1 suitable for supplying an air-fuel mixture with an optimal mixture ratio to the engine over the entire engine rotation range.
Regarding fiff.

(Prior Art) Generally, a capretor is disposed in an intake passage connected to an intake port of an engine, and creates a mixture of air and fuel and supplies it to the intake port.

This carburetor operates by opening and closing the throttle valve.
It is configured to create a-aiki with the optimum mixture ratio depending on the operating conditions of the engine.

(Problem to be Solved by the Invention) However, when creating a mixture using such a single V-bullet, as shown by the broken line C in Figure 2, at a certain engine speed, the mixture is not atomized. The outflow of the supplied fuel may be reduced.

As a result, the mixture ratio decreases at this specific rotation speed, and a lean mixture is sent to the intake port of the engine, which may reduce the engine output.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an engine intake device that can improve engine output by supplying an air-fuel mixture with an optimal mixture ratio to the engine over the entire rotation range of the engine. With the goal.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a carburetor which is disposed in an intake passage connected to an intake port of an engine, and which supplies a mixture of air and fuel to the intake port. A fuel injection device is disposed between the fuel injection device and the port, and is configured to inject fuel from the fuel injection device to replenish the air-fuel mixture created by the carburetor.

(Function) Therefore, according to the engine intake system according to the present invention, since the carburetor and the fuel injection device control the mixture ratio of the air-fuel mixture guided to the engine intake port, the specific engine rotation rate that occurs when the carburetor is used alone A decrease in the mixture ratio can be prevented by replenishing fuel from the fuel injection device, and an air-fuel mixture with an optimal mixture ratio can be supplied to the engine intake port.

(Example) Embodiments of the present invention will be described below based on the drawings.

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

A cylinder 3 is fitted into a cylinder block 2 of an engine 1, and a piston 4 is housed within 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 converts the reciprocating motion of the piston 4 into rotational motion.

The cylinder 3 is formed with an intake port 7, an exhaust port 8, and an air port (not shown), respectively.

Among these, the scavenging port communicates with a crank chamber 9 connected to the cylinder 3. These intake ports 7 and exhaust ports 8
and the scavenging port is controlled to open and close by the piston 4,
The exhaust bows I to 8 and the scavenging bow] open on the bottom dead center side of the piston 4, and the intake port 7 opens on the top dead center side.

Further, a reed valve device 10 is installed at the intake port 7. This reed valve device 10 includes a valve body 12 which is formed so as to close the intake port 7 with a ■-shaped surface, and an opening 11 is provided in this V-shaped surface, and a valve body 12 which is in contact with the V-shaped surface of this valve body 12 and has an opening 11 formed in the V-shaped surface. The reed valve 13 includes a reed valve 13 that can be opened and opened, and a valve stopper 14 that restricts the lift of the reed valve 13.

In this reed valve device 10, when the piston 4 rises and the crank chamber 9 becomes negative pressure, 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 crank chamber 9
The pressure inside changes to positive, and the reed valve 13 returns to its original position and opens the opening 1.
1 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.

Furthermore, an intake passage 16 in which a carburetor 15 is disposed is connected upstream of the intake bow 1 to 7. A fuel injector 17 of a fuel injection device is arranged between the carburetor 15 and the intake port 7 in this intake passage 16. These carburetors 15 and fuel injectors 1
7, the above-mentioned air-fuel mixture that is introduced to the intake port 7 is created.

The capretor 15 includes a float chamber 19, a throttle valve 20. It is configured with a needle jet 21 and a jet needle 22. Floatchi 1! The chamber 19 is provided below the carburetor body 18 and stores a certain amount of fuel (gasoline). Also, throttle valve 2
0 is provided in the venturi portion of the carburetor body 18, and the diameter of the venturi portion is changed by operating the throttle 1-role. The needle jet 21 is provided below the throttle valve 20 in the capletor body 18 and communicates with the foot chamber 19 .

Furthermore, the jet needle 22 is connected to the throttle valve 2
0 and inserted into the needle jet 21, forming a gap between the needle jet 21 and the needle jet 21.

In this carburetor 15, the throttle valve 20 is directly actuated by operating the throttle to adjust the amount of air passing through the kissable carburetor body 18. When the throttle valve 20 is opened to increase the amount of air, the flow velocity at the venturi section increases and the air pressure at the venturi section decreases. Moreover, since the jet needle 22 is pulled up when the throttle valve 20 is closed, the gap between the jet needle 22 and the needle jet 21 becomes larger.

As a result, a large amount of fuel in the 70-chamber 19 is ejected into the venturi portion through the gap between the jet needle 22 and the needle jet 21.

Further, in this carburetor 15, the jet needle 22
By adjusting the taper amount and the insertion depth into the needle jet 21, the one-point chain l! 8, the fuel flow ω (fuel injection amount) from the carburetor 15 is
Set so that the air-fuel mixture created in step 5 is lower than the fuel flow rate that gives the optimum mixture ratio.

On the other hand, the fuel injector 17 is attached to the intake passage 16 so as to be oriented toward the reed valve 13 . Further, the fuel injector 17 operates based on a signal from an a/Ill device (not shown), and injects the pressurized fuel in the delivery pipe 23 into the intake passage 16. As a result, the air-fuel mixture created by the carburetor 15 is further supplied with fuel from the fuel injector 17. The amount of fuel injected from the fuel injector 17 (fuel flow rate) is determined by the amount of fuel injected from the fuel injector 17, as shown by the solid line A in FIG.
When added to the fuel flow m from the intake port 7, the U air gas supplied to the intake port 7 is set to have an optimum mixing ratio.

Therefore, according to this embodiment, the mixture ratio of the air-fuel mixture introduced into the intake port 7 is controlled by the carburetor 15 and the fuel injection device 17. Fuel from carburetor 15 at rpm! Even if ffi decreases and the mixture ratio of the air-fuel mixture created 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, it is possible to prevent the above-mentioned mixture ratio from decreasing, and it is possible to supply air with an optimum mixture ratio to the intake port 7. Therefore, an air-fuel mixture with an optimal mixture ratio can be supplied to the intake port 7 over the entire rotation range of the engine, and the engine output can be improved.

Note that in the above embodiment, the fuel flow rate from the carburetor 15 was set lower than the case where the air-fuel mixture reached the optimum mixture ratio, but the fuel flow rate from the carburetor 15 was set to be the same as before so that the mixture ratio was optimum. However, when the fuel flow rate from the carburetor 15 decreases at a specific engine speed,
Fuel may be supplied from the fuel injector 17. Control of the fuel injector 17 in this case is performed by an aIIJIXl device (not shown).

〔Effect of the invention〕

As described above, according to the engine intake system according to the present invention, the carburetor and the fuel injection device are disposed in the engine intake passage, and fuel is injected from the fuel injection device δ into the air-fuel mixture created by the carburetor. Since the fuel flow m supplied from the carburetor decreases, it can be compensated for by the fuel supplied from the fuel injection device, and the optimum mixture ratio can be maintained over the entire rotation range of the engine. U air can be supplied to the intake port, improving engine output.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1. A carburetor that supplies a mixture of air and fuel to the intake port is disposed in an intake passage connected to the intake port of the engine, and a fuel is provided between the carburetor and the intake port. An intake device for an engine, characterized in that an injection device is disposed and configured to inject fuel from the fuel injection device to replenish the air-fuel mixture created by the carburetor. 2. The engine according to claim 1, wherein the mixture ratio of the air-fuel mixture produced by the carburetor is set lower than the optimum mixture ratio, and the optimum mixture ratio is set by controlling the flow rate of fuel supplied from the fuel injection device. intake device.