JPS63239343A - Carburetor starter for two-cycle engine - Google Patents

Abstract

PURPOSE:To improve fuel ignitability at the time of cold starting in particular, by feeding starting fuel to an engine crankcase or the like directly with discharge pressure out of a fuel pump at the time of engine starting, while increasing the quantity of starting air. CONSTITUTION:Fuel in a fuel tank T is fed to a carburetor A feeding a two-cycle engine B with an air-fuel mixture with pressure. In this case, a starting fuel feed passage 28 is branched off from a fuel feed passage 25 interconnecting a fuel chamber 22 of the fuel tank T and a carburetor body 1 together, and the end is connected to a crankcase or the like of the engine B. And, in the starting fuel feed passage 28, there is provided with a normally closed type on-off valve 29 opening or closing this passage 28. On the other hand, a start operating lever 31 is supported on a shaft J of the carburetor body 1 free of rotation, and a first bending part 31A as the starting air increment device is made to correspond to a throttle valve lever 5, while a flange part 29A of the on-off valve 29 is engaged with a second bending part 31B.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a carburetor for controlling the concentration and amount of air-fuel mixture supplied to an engine, and in particular to a starting device for a carburetor used in a two-stroke engine. It is related to.

[Conventional technology]

Conventionally, the commonly used starting device for two-stroke engine carburetors is a so-called choke system in which a choke valve is placed in the intake duct of the carburetor and the intake duct is held in a fully closed state by the choke valve when the engine is started. type, and the so-called so-called type in which the front and back of the throttle valve placed in the intake passage are connected through a starting passage, and a starter on-off valve is placed in the starting passage, and the starter on-off valve holds the starting passage open when the engine is started. There is also a starter type.

[Problem that the invention seeks to solve]

Such a conventional starting device has the following problems.

That is, according to the former, when the choke valve is closed and the engine is cranked during startup, the negative pressure in the intake tract generated by this cranking is increased by the choke effect of the Chigok valve, and the low-speed nozzle opening in the intake tract is increased. , the increased intake air negative pressure acts on the nozzle holes such as the main nozzle, sucking out fuel from the nozzle holes and supplying starting fuel to the engine, but at low speeds reaching these low speed nozzle holes. The fuel system or the main fuel system leading to the main nozzle is in a low-speed cartwheel state of the engine or in the middle, respectively.

Settings are made to suit high-speed operating conditions, and in order to adjust the low-speed fuel system and main fuel system to satisfy the starting conditions, a lot of time is spent on setting to suit the conditions. .

In other words, when changing the low-speed fuel system or main fuel system that has been set once to improve starting performance, the low-speed fuel system or main fuel system must be changed again.
This is because it is necessary to test the main fuel system to confirm.

Also, according to the latter, since the low-speed fuel system and the main fuel system have a starting passage as completely separate systems, unlike the former, there is no connection between the low-speed fuel system and the main fuel system, making the setting work easier. When the throttle valve is opened at the time of starting the engine, it is difficult to obtain a high intake tract negative pressure in the intake tract, which may make it impossible to suck out the starting fuel, resulting in poor starting performance.

[Means to solve the problem]

In view of the above drawbacks, the present invention provides a starting device for a two-stroke engine carburetor that is easy to set to improve starting performance and has good starting performance that can supply optimal starting fuel. In particular, in order to achieve the above purpose, the starting fuel supply path is branched from the fuel supply path that connects the fuel pump and the fuel inlet of the carburetor, and the starting fuel supply path is connected to the starting fuel supply path. An on-off valve is provided to control opening and closing, and when the on-off valve is opened, the amount of air supplied from the carburetor to the engine can be increased compared to the amount of air at the lowest idling opening of the carburetor. Will there be a way to increase the amount? This is a starting device for a carburetor for a cycle engine.

[Effect]

When starting the engine, the on-off valve is opened to prepare for starting, and then the engine begins cranking operation. Through this cranking operation, the fuel pump pumps the fuel in the fuel tank, and a portion of the fuel pumped by the fuel pump is injected into, for example, the crankcase of the engine.

On the other hand, the amount of air supplied to the engine simultaneously with the opening of the on-off valve is increased compared to the amount of air at the lowest idling time.

Therefore, an engine is started by increasing the amount of rich air-fuel mixture and air suitable for starting.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to FIG.

A is a carburetor that supplies the air-fuel mixture to the two-stroke engine B, and the fuel in the fuel tank T is fed to the carburetor A by the fuel pump P.
It is sent under pressure.

The vaporizer A has the following configuration. That is, l is a carburetor main body through which an intake passage 2 passes, and a throttle valve 4 supported by a throttle valve shaft 3 is rotatably arranged in the intake passage 2. A throttle valve lever 5 is integrally arranged at the end protruding from the container body l. A float chamber body 6 is disposed below the carburetor body 1, and a float chamber 7 is formed by the lower recessed portion of the carburetor body 1 and the float chamber body 6.

8 is a valve seat connected to the fuel inlet H and opened into the float chamber 7; a float valve 9 is movably disposed corresponding to the valve seat 8; The float arm l
The float arm 10 of the float arm 12 is rotatably supported on the bin 11 at the point O. The rotation of the flow valve 12 with respect to the bottle 11 causes the float arm 10 to control the opening and closing of the valve seat 8 in the float valve 9.

Further, 13 is a main nozzle as a main fuel system.

Its tip protrudes into the intake passage 2 and opens, and the other end is connected to a main fuel jet 14 formed in the float chamber 7 and placed below a constant liquid level.

Reference numeral 15 denotes a stop screw screwed onto the carburetor main body l, the tip of which comes into contact with the throttle valve lever 5. By adjusting the screw movement of the stop screw 15, the throttle valve 4 can be adjusted to its lowest position. The idling opening degree is adjusted.

The fuel pump P has a pump main body 20 divided into a fuel chamber 22 and a pulsation chamber 23 by a partition 21 such as a diaphragm, and the fuel chamber 22 has a fuel suction passage 24 connected to a fuel tank T and a carburetor. The fuel supply path 25 connected to the fuel population H of the main body 1 is open [This, the fuel suction path 24 has an intake side check valve 26
is arranged, and a discharge side check valve 27 is arranged in the fuel supply path 25.

Furthermore, the pulsating chamber 23 is connected to, for example, the crankcase of the two-stroke engine B, in order to impart reciprocating motion to the partition body 21, and pulse pressure within the crankcase is introduced into the pulsating chamber 23. Reference numeral 28 denotes a starting fuel supply passage branched from the fuel supply passage 25, the end of which is connected to, for example, the crankcase of engine B;
A normally closed on-off valve 23 for opening and closing the supply passage is arranged in B, and 30 is a valve M disposed in the starting fuel supply passage 28.
This is a controlled jet.

Further, 31 is a starting operation lever rotatably supported, for example, on the shaft J of the carburetor main body l, and the first bent portion 31A serving as air increasing means at starting corresponds to the throttle valve lever 5.
A collar portion 29A of the on-off valve 29 is locked to the second bent portion 31B. When the starting operation lever 31 is not operating (the state shown in the figure), there is a gap between the first bent portion 31A and the throttle valve lever 5, and the throttle valve lever 5 contacts the stop screw 15 to throttle the throttle valve. It regulates the minimum idling opening degree of the valve 4, and the bending part 31B of the force cylinder 2 is also the same as the flange part 29A.
The on-off valve 29 has a gap between it and the starting fuel supply path 2.
8 in a closed state.

Next, its effect will be explained.

First, a case in which the ambient temperature and the engine temperature of one engine are high will be described. The starting operation lever 31 is not operated and is in the state shown in FIG. 1. When a cranking operation is performed to start the engine in such a state, the pulsating chamber 23 of the fuel pump P receives pulse pressure within the crankcase, causing the compartment 21 to reciprocate and increase or decrease the volume of the fuel chamber 22. The fuel in the fuel tank T is fed to the fuel port H and the valve seat 8 through the fuel supply path 25, and a desired constant amount of fuel is stored in the float chamber.

Incidentally, since the starting fuel supply passage 28 is closed by the on-off valve 29, fuel is not supplied to the crankcase of the engine via the supply passage.On the other hand, no fuel is supplied to the intake passage 2 of the carburetor main body l by the cranking operation. This is the main nozzle on which negative air pressure acts, and this air air air negative pressure opens into the air intake air 2! Since the fuel in the float chamber 7 is sucked out into the intake passage 2 and supplied to the engine B, it is possible to start the engine.

After that, fuel is sequentially supplied from the fuel pump P to the carburetor,
The engine can be operated normally.

Next, regarding starting in a state where the engine ambient temperature is low, the starting operation lever 31 is first rotated counterclockwise prior to the starting operation of one engine. According to this, the first bending portion 31A first contacts the throttle valve lever 5, rotates the throttle valve lever 5 counterclockwise, opens the throttle valve 4 from the lowest idling opening, and sets the first idling opening state. It is something that can be kept.

On the other hand, the second bent portion 31B bends the collar portion 29B of the on-off valve 2B to t.
By pulling it toward the side, the starting fuel supply path 2B is held open. When the engine is cranked after the start preparation state is completed, the fuel pump P operates and fuel is supplied to the fuel supply passage 25 at the same time as in the fourth paragraph, and the on-off valve 29 is connected to the starting fuel supply passage. 28 is open, the starting fuel limited by the control jet 30 is directly injected and supplied to the crankcase of the engine B.

Further, the throttle valve 4 of the carburetor A is opened from the minimum idling opening degree so that #a amount of starting air can be supplied to the engine B.

As described above, the starting fuel is directly injected into the engine crankcase using the discharge pressure of the fuel pump P, and the amount of starting air is increased, which improves the ignition performance especially at low temperatures and allows the engine to complete. This made it possible to improve the toughness of the engine to keep it running after a detonation.

Furthermore, in the example shown in FIG. 2, the opening of the throttle valve 4 is not directly opened, but a starting air passage 40 is provided across the upper and lower waves of the throttle valve 4 as means for increasing the amount of air during startup. In addition, the starting air passage 40 is opened and closed by a starting air valve 41, and in particular, this starting air valve 41 is opened and closed synchronously with the opening/closing valve 29 that opens and closes the starting fuel supply path 28. According to this, when setting the starting air passage, it is sufficient to simply select the passage diameter of the starting air passage 40, and furthermore, the arrangement of the on-off valve 29 and the starting air valve 41 can be set independently of the carburetor, so there is freedom in design and arrangement. It is possible to improve the level of performance. (In FIG. 2, parts with the same structure as in FIG. (not shown), and the starting operation lever 31 or on-off valve 28, starting air valve 41,
By sensing temperature changes such as engine ambient temperature and engine temperature, and automatically controlling the opening and closing of these levers and valves, the starting operation can be automated and the starting operation can be made easier.

In addition, in a multiple carburetor that uses multiple carburetors, supplying starting fuel from the starting fuel supply path to the crankcase or intake pipe of each engine will help improve the startability of the multi-cylinder engine. It is something.

〔Effect of the invention〕

As described above, the starting device for a two-stroke engine carburetor according to the present invention provides the following effects.

■When starting the engine, the fuel pump directly injects and supplies the discharged fuel at the discharge pressure without relying on the negative pressure in the intake airway, and at the same time increases the amount of starting air, improving the ignitability of the engine and achieving complete engine explosion. Since the toughness with respect to continued rotation afterward was improved, starting performance was significantly improved.

■Since the starting fuel supply path is provided completely separate from the intake path of the carburetor, the fuel in the starting fuel supply path is Since it is only necessary to distribute it across the width, it is possible to easily organize the starting system for the entire engine.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram including a sectional view of the carburetor showing one embodiment of the starting device for a two-cycle engine carburetor according to the present invention, and FIG. 2 is an overall configuration diagram showing another embodiment. Aoo, carburetor, B,, two-stroke engine, Pll,
Fuel pump, Tol, fuel tank, 420. throttle valve,
H61, fuel inlet, 25, fuel supply path, 2B,
,, fuel supply path for starting, 29. ,,on-off valve, 31.
,,starting operation lever, 40. ,, starting air passage,
41. ,,starting air valve.

Claims (1)

[Claims] In a two-stroke engine that supplies fuel to a carburetor by a fuel pump driven by pulse pressure generated in the crankcase of the one- and two-stroke engine, the fuel pump and the fuel inlet of the carburetor are connected. The starting fuel supply path is branched from the communicating fuel supply path, and the starting fuel supply path is provided with an on-off valve that controls the opening and closing of the starting fuel supply path, and when the on-off valve is opened, the starting fuel supply path is connected to the starting fuel supply path. A starting device for a two-cycle engine carburetor, which is provided with a starting air increasing means capable of increasing the amount of air supplied to the engine compared to the amount of air at the minimum idling opening of the carburetor. 2. The carburetor for a two-stroke engine according to claim 1, wherein the air increasing means at the time of starting is configured to open a throttle valve by a certain opening degree from the minimum idling opening degree when the on-off valve is opened. starting device. 3. As the air increasing means at the time of starting, an air opening/closing valve is arranged in the starting air passage to connect the intake passages before and after the throttle valve with a starting air passage, and to open and close the air opening/closing valve in the starting air passage, and in the starting fuel supply passage. 2. A starting device for a two-stroke engine carburetor according to claim 1, wherein an air on-off valve is opened synchronously when an on-off valve is opened. 4. The starting device for a two-stroke engine carburetor as set forth in claim 1, wherein the opening end of the starting fuel supply path is connected to the crankcase of the two-stroke engine. 5. The starting device for a two-stroke engine carburetor as set forth in claim 1, wherein the open end of the starting fuel supply path is connected to an intake pipe leading to the two-stroke engine.