JPS63239346A - Carburetor starter for two-cycle engine - Google Patents

Abstract

PURPOSE:To improve fuel ignitability at the time of cold starting in particular, by installing a starting fuel storage chamber and a starting fuel pump combinedly in the side of a carburetor body in order, and at the time of engine starting, feeding fuel inside the starting fuel storage chamber directly to a crankcase or the like of an engine. CONSTITUTION:Fuel in a fuel tank T is fed to a carburetor A which feeds an air-fuel mixture to a two-cycle engine B with pressure by a fuel pump P. In this case, a starting fuel storage chamber 20 is formed in the side of a carburetor body 1 separately from a float chamber 4. The starting fuel storage chamber 20 is interconnected to the float chamber 4 via a warm-up fuel jet 21, and to the atmosphere via a warm-up air jet 22, respectively. In addition, a starting fuel pump R is set up in the side of the starting fuel storage chamber 20, this pump is made up of partitioning the inside of a pump body 30 into a fuel chamber 32 and a pulsating chamber 33 by a partitioner 31 of a diaphragm or the like. And, a starting fuel discharge passage 35 to be opened to this fuel chamber 32 is connected to a crankcase or the like of the engine B via a normally closed type starting on-off valve 38.

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 starting device for a two-stroke engine carburetor that is commonly used has a choke valve placed in the intake duct of the carburetor, and the intake duct is kept fully open with a check valve when the engine is started. The so-called choke type is connected to the front and back of the throttle valve placed in the intake duct by a starting passage, and a starter on-off valve is placed in the starting passage, and the starter on-off valve keeps the starting passage open when the engine is started. There is a so-called 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 choke valve, and opens into the intake tract. The increased intake air negative pressure acts on the nozzle holes such as the low-speed nozzle hole and the main nozzle, sucking out fuel from the nozzle hole and supplying starting fuel to the engine, but these low-speed nozzle holes The low-speed fuel system leading to the main nozzle or the main fuel system leading to the main nozzle are operated at low-speed or medium-speed operation of the engine, 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-mentioned purpose, a starting fuel storage chamber is provided separately from the float chamber, and the starting fuel storage chamber is connected to the starting fuel storage chamber below a constant liquid level in the float chamber via a warm-up fuel jet. The engine communicates with the atmosphere via an air jet, and a starting fuel suction passage is opened in the starting fuel storage chamber for the starting fuel pump, which is driven by the pulse pressure generated in the engine crankcase. A starting fuel discharge passage is opened in the pump chamber, and a normally closed starting opening/closing valve is disposed in either the starting fuel intake passage or the starting fuel discharge passage.

[Effect]

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

Therefore, a rich air-fuel mixture can be supplied to the engine and the engine can be started easily.

〔Example〕

An embodiment of the present invention will be explained below 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, in 1, an intake passage 2 passes through the interior, and a float basic body 3 is arranged below the carburetor main body 1, and a float chamber 4 is formed by the lower four parts of the carburetor main body 1 and the float basic body 3. It is formed. 5 is fuel inlet H
It is a valve seat that is connected to and opens into the float chamber 4,
A float valve 6 is movably disposed in correspondence with the valve seat 5, and furthermore, this float valve 6 is disposed within the float chamber 4 and is rotatably supported on a bin 8 by a float arm 7. The float arm 7 of the float 9
are arranged correspondingly. The rotation of the float 9 relative to the bin 8 causes the float arm 7 to control the opening and closing of the valve seat 5 in the float valve 6.

In addition, lO is a main nozzle as the main fuel system, whose tip protrudes into the intake passage 2 and opens, and the other end is a main fuel jet formed in the float chamber 4 and placed below a constant liquid level. 1
Connects to 1.

The above structure is a conventionally known technique, and the starting device for a two-stroke engine carburetor according to the present invention has the following structure in order to achieve the above object. That is, reference numeral 20 denotes a starting fuel storage chamber, which is formed on the side of the carburetor main body 1 and independently of the float chamber 4. (It does not necessarily have to be integrated with the carburetor main body l and the float basic body 3.) The bottom of this starting fuel storage chamber 20 is connected to the bottom of the float chamber 4 under a constant liquid level via the warm-up fuel jet 21. ,
Furthermore, its upper part is connected to the atmosphere via a warm-up air jet 22, and in this embodiment, it is connected to an atmospheric chamber with a constant liquid level E in the float chamber 4.

Therefore, there is a warm-up fuel jet in this starting fuel storage chamber 20.
The fuel in the float chamber 4 is stored via 21. This storage is at the same level as the constant liquid level height xx in the float chamber 4.

Further, R is a starting fuel pump driven by pulse pressure generated in a two-stroke engine, and the pump main body 30 is divided into a fuel chamber 32 and a pulsation chamber 33 by a partitioning body 31 such as a diaphragm. The chamber 32 includes a starting fuel storage chamber 20.
A starting fuel intake passage 34 and a fuel starting discharge passage 35 are opened, and a suction side advance valve 36 is arranged in the starting fuel intake passage 34, and a discharge side advance II-valve is disposed in the starting fuel discharge passage 35. 3
7 is placed.

Furthermore, the pulsating chamber 33 is connected to, for example, the crankcase of a two-stroke engine B, in order to impart reciprocating motion to the partition body 31, and pulse pressure within the crankcase is introduced into the pulsating chamber 33. The end of the starting fuel discharge passage 35 is connected to, for example, the crankcase of the engine B;
A normally-closed starter opening/closing valve 38 that opens and closes the starting fuel discharge passage 35 is arranged in the starting fuel discharge passage 35 .

Next, its effect will be explained.

First, to explain the case where the engine ambient temperature and engine temperature are high, when a cranking operation is applied to one engine to start the WL engine, the starting fuel pump is operated by n+ due to the pulse pressure generated in the crankcase. However, since the starting on-off valve 38 disposed in the starting fuel discharge passage 35 keeps the discharge passage 35 closed, the starting fuel discharge passage 35
No starting fuel is supplied to the engine, and the engine is started normally.

Next, regarding starting in a state where the engine ambient temperature is low, before starting the engine, first open the starting on-off valve 38.
The engine cranks after opening.

According to this, the starting fuel pump R is immediately driven and can supply the starting fuel in the starting fuel storage chamber 20 into the crankcase of the engine via the starting fuel discharge passage 35, Since the fuel in the starting fuel storage chamber 20 can be used sufficiently without being restricted in any way by the warm-up fuel jet 21, a sufficiently rich mixture can be supplied to the engine.

Next, when the engine completely explodes and starts warming up, this +1! ?
, the fuel already stored in the starting fuel storage chamber 20 is filled, and a mixture of starting fuel limited by the warm-up fuel jet and air limited by the warm-up air jet is mixed for this starting. Since it is supplied from the starting fuel discharge passage 35 via the fuel pump R and can supply an appropriately diluted mixture, a good warm-up operation state can be obtained.

When the warm-up operation is completely completed, the starting on-off valve 38
If the engine is returned to its original state and the starting fuel discharge passage 35 is closed, the supply of fuel from the discharge passage 35 is cut off and good operation can be maintained by receiving fuel supplied by a normal carburetor.

Note that instead of the starting on-off valve 38 disposed in the starting fuel discharge passage 35, a normally closed starting on-off valve that opens and closes the pulse passage is provided in the pulse passage 40 that introduces the pulsating pressure in the crankcase into the pulsating chamber 33. By arranging the starting fuel pump R, the driving of the starting fuel pump R can be completely stopped when the pulse passage of the starting on-off valve is blocked, thereby improving the durability of the starting fuel pump R. It does not apply pressure fluctuations to the

Incidentally, the starting fuel discharge passage 35 may be connected to an intake pipe (not shown) that connects the carburetor A and the engine B, and the starting on-off valve 38, engine atmosphere temperature, engine temperature, etc. The starting operation can be automated by sensing and automatically controlling the opening and closing of these valves, making the starting operation easier.

〔Effect of the invention〕

As described above, according to the starting device for a two-stroke engine carburetor according to the present invention, when starting the engine, the discharge fuel having the discharge pressure is directly injected and supplied by the starting fuel pump without relying on the negative or positive air intake passage. As a result, the ignitability of the engine can be improved, and the startability has been greatly improved.Especially when warming up the engine after a complete explosion, the warm-up fuel jet and warm-up air jet are automatically activated. Since the starting fuel supplied from the starting fuel pump could be diluted, it was possible to provide a starting device with good warm-up performance.

Furthermore, since the starting fuel discharge passage is provided completely separate from the intake passage of the carburetor, the fuel in the starting fuel discharge passage is Since it is only necessary to distribute the starting system, 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 an embodiment of the starting device for a two-cycle engine carburetor according to the present invention. Aoo, carburetor, B,, two-cycle engine, Poo,
Fuel pump, T10. Fuel tank, R06, starting fuel pump, Hlo, fuel inlet, 20. ,,starting fuel storage chamber, 210. Warm-up fuel jet, 22. ,,warming air jet. 35., starting fuel discharge passage, 38. , starting on-off valve.

Claims (4)

[Claims] (1) In a two-stroke engine that supplies fuel to the carburetor by a fuel pump driven by pulse pressure generated in the crankcase of the two-stroke engine, a starting fuel storage chamber is provided separate from the float chamber, and the starting fuel The storage chamber is connected to a constant liquid level in the float chamber via a warm-up fuel jet, and communicates with the atmosphere via a warm-up air jet. The starting fuel suction passage of the starting fuel pump driven by the pulse pressure of A starting device for a two-stroke engine carburetor that has a normally closed starting on-off valve on one side. (2) In a two-stroke engine that supplies fuel to the carburetor by a fuel pump driven by pulse pressure generated in the crankcase of the two-stroke engine, a starting fuel storage chamber is provided separate from the float chamber, and the starting fuel The storage chamber is connected to a constant liquid level in the float chamber via a warm-up fuel jet, and communicates with the atmosphere via a warm-up air jet. The starting fuel suction passage of the starting fuel pump driven by the pulse pressure of A starting device for a two-stroke engine carburetor, which includes a normally closed starting on/off valve on one side and a normally closed starting on/off valve on the pulse passage of a starting fuel pump. (3) The starting device for a carburetor for a two-stroke engine according to claims 1 and 2, wherein the opening end of the starting fuel discharge passage is connected to the crankcase of the two-stroke engine. (4) The starting device for a carburetor for a two-stroke engine according to claims 1 and 2, wherein the opening end of the starting fuel discharge passage is connected to an intake pipe leading to the two-stroke engine.