JPH01232159A - Starting fuel supplier device to internal combustion engine for portable work machine - Google Patents

Abstract

PURPOSE:To obtain a starting fuel supplying device with its constitution simplified and a starting fuel amount controlled continuously corresponding to a change of temperature by providing a temperature sensing member which limits a plunger for its stroke correlating to an ambient temperature. CONSTITUTION:Before an engine is started, when a primer pump 37 is normally rotated, a fuel reservoir 32 is charged with fuel in a metering chamber 16 via a passage 40, starting fuel metering device 81 and a passage 38. Simultaneously with starting of the engine, when the primer pump 37 is reversely rotated, the fuel in the fuel reservoir 32 is delivered to a chamber 92a of the starting fuel metering device 81. Here closing a check valve 95, fuel in a metering chamber 92b is jetted by a plunger 87 to an intake passage 17 of a carburetor from a fuel nozzle 14. By a temperature sensing member 99, consisting of thermowax arranged in the inside of the starting fuel metering device 81, a stroke (s) in a suction stroke of the plunger 87 is automatically controlled correlating to an ambient temperature of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a starting fuel supply device for an internal combustion engine for a portable working machine.

[Prior Art] Portable working machines such as chain saws and brush cutters that are small and require high output are equipped with a two-stroke internal combustion engine equipped with a diaphragm carburetor that can respond to three-dimensional changes in the attitude of the machine body. In recent years, internal combustion engines have also been equipped with starter motors, making starting operations easier. However, especially in portable working machines used in cold regions, the amount of fuel automatically increases depending on the ambient temperature when starting. Since there is no mechanism, there is a problem with startability.

Therefore, the present applicant, by Japanese Patent Application No. 133-8836,
An application has been filed for a device that automatically adjusts the amount of starting fuel in response to temperature conditions. However, the technology related to this application only adjusts the torque of the motor that drives the starting fuel gauge II device in accordance with the temperature conditions, and gradually changes the starting fuel amount to 111111 in accordance with the temperature conditions. It's hard to call it a thing. If the amount of starting fuel is to be electrically controlled continuously, the configuration of the electrical control circuit will become very complex, leading to an increase in cost.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to have a simple configuration,
An object of the present invention is to provide a starting fuel supply device for an internal combustion engine for a portable working machine, in which the amount of starting fuel is continuously controlled in response to temperature changes.

Means for Solving Problem E] In order to achieve the above object, the configuration of the present invention is to transfer the fuel filled into the fuel reservoir l\\ from the fuel tank through the starting fuel metering device having a plunger by normal rotation of the pump. The reversal of the pump activates the plunger of the starting fuel metering device,
Total! The device injects the maximum amount of fuel into the intake passage of the carburetor, and is equipped with a temperature-sensitive member that limits the stroke of the plunger in relation to the ambient temperature.

[Function] According to the present invention, the stroke (operating range) of the plunger 87 of the starting fuel metering device 81 is continuously controlled in response to temperature changes, and the amount of starting fuel suitable for the temperature conditions is supplied to the engine. Supplied.

When the primer pump 37 is rotated forward before starting the engine, the fuel in the metering chamber 16 flows through the passage 40, the check valve 39, and the passage 83.
, starting fuel gauge! The fuel is sucked into the primer pump 37 through the i device 81 and the passage 38, and further through the passage 30 into the fuel reservoir 3.
2 is filled, and excess fuel is returned to the fuel tank 35 via the relief valve 33 and the pipe 34.

When the primer pump 37 is reversed at the same time as the engine starts,
The fuel in the fuel reservoir 32 passes through the passage 30 to the primer pump 37.
and is further discharged through the passage 38 into the chamber 92a of the starting fuel metering device 81. At this time, the check valve 95 is closed, and the plunger 87 causes the fuel in the metering chamber 92b to be injected from the fuel nozzle 14 into the intake passage 17 of the carburetor via the passages 83, 31° and the check valve 29.

A temperature-sensitive element 99 made of thermowax arranged inside the starting fuel metering device 81 automatically adjusts the stroke S of the plunger 87 during the suction stroke by 11.1 till in relation to the ambient temperature of the engine. Therefore, the amount of starting fuel suitable for the ambient temperature is automatically metered into the metering chamber 92b.

[Embodiments of the Invention] FIG. 1 shows a schematic configuration of a starting fuel supply device for an internal combustion engine for a portable working machine according to the present invention. The carburetor 2 has a throttle valve 20 disposed inside the intake passage 17, and a fuel pump A including a diaphragm 6 is coupled to the upper part of the main body 3.
5 through a pipe 9 is sent to a metering chamber 16 of a fuel supply mechanism B coupled to the lower side of the main body 3, and from there is supplied to an intake passage 17 by negative intake pressure.

The starting fuel supply device includes a primer pump 37 driven by a motor 36, and the fuel in the fuel tank (actually the metering chamber 16) is supplied to the passage 40, the check valve 39, the passage 83, and the starting fuel metering device! 181, the fuel is sucked into the primer pump 37 through the passage 38, and is stored in the fuel reservoir 32 through the pipe 30. Excess fuel is returned to the fuel tank 35 through the return valve 33 and the pipe 34.

When the primer pump 37 is reversed when starting the engine, the fuel in the fuel reservoir 32 is sucked into the primer pump 37 through the passage 30, and then through the passage 38 to the starting fuel gauge IH [81
The fuel in the metering chamber 92t) is discharged by the plunger through the passages 83, 31 and the check valve 29, and flows into the fuel nozzle 14.
The air is ejected from the air into the intake passage 17.

A control device 42 for controlling the motor 36 is constructed as shown in FIG. In FIG. 2, 41 is a power source battery, 45
is a switch that is closed by the start key, and in conjunction with this, the switch 44 of the engine's ignition circuit 49 is closed. 5
2 is a pump switch, 8 is a temperature switch that closes when the ambient temperature of the engine is lower than a predetermined value, and 55.56 is a motor 36.
The start switch 5 is a changeover switch for forward and reverse rotation, and is interlocked with a switch 57 that drives the starter motor 46.
4. The start switch 54 is normally in the state shown and is switched only during the driving period of the starter motor 46.

FIG. 3 shows how the carburetor 2, which is integrally equipped with a starting fuel supply device, is attached to the engine 27. The engine 27 has a diaphragm type carburetor 2 and an air cleaner (not shown) attached to the side wall of the cylinder 65 via a suction pipe 51 made of a heat insulating member. A pipe 9 from the fuel tank 35 is connected to the inlet side of the fuel pump A of the carburetor 2.

The carburetor 2 has an intake passage 17 including a venturi in the main body 3,
It communicates with an intake boat 66 provided in the cylinder 65. A known throttle valve 20 is rotatably supported within the intake passage 17 by a valve shaft 19 . Diaphragm 6 on the earthen wall of main body 3
The cover 4 is coupled to the lower wall with the diaphragm 11 in between, while the cover 15 is coupled to the lower wall with the diaphragm 11 in between. The pulsating pressure inlet 5 defined by the diaphragm 6 communicates with the crank chamber 71 of the engine 27 via a pipe 72 . Pump room 61
- is communicated with the pipe 9 via the check valve 48, while the check valve 4
7, a passage 60, and an inflow valve 10 to communicate with the metering chamber 16.

An atmospheric chamber 62 between the diaphragm 11 and the cover 15 that partitions the metering chamber 16 is opened to the atmosphere through a passage 62a. A needle-type inlet valve 10 is arranged at the end of the passage 60 and is opened and closed by a lever 13 supported by a shaft 12 on the wall of the metering chamber 16 . That is, the lever 13
One end of the lever 13 is biased and engaged with the end of the inflow valve 10 by the force of a spring, and the other end of the lever 13 is abutted against a protrusion connected approximately to the center of the diaphragm 11. The metering chamber 16 is connected to the high speed fuel nozzle 24 via a check valve 26 and a high speed fuel metering needle valve 25.
will be communicated to. Also, the metering v16 is the check valve 23.
, and communicates with the low-speed fuel injection port 21 via the low-speed fuel metering needle valve 22 .

A casing 53 that supports the primer pump 37 and a housing 50 that accommodates the motor 36 are provided below the cover 15.
are combined. One port of the primer pump 37 (the suction port during forward rotation) is connected to the passage 38, the starting fuel metering device 81, and the passage 8.
3. It communicates with the metering chamber 16 via a check valve 39 and a passage 40, and also communicates with the fuel nozzle 14 via a passage 83.31 and a check valve 29. The other port (discharge port during forward rotation) of the primer pump 37 is communicated via a passage 30 with a fuel reservoir 32 made of a pipe made of rubber, vinyl, or the like. The fuel reservoir 32 is communicated with a fuel tank 35 via a reversing valve 33 and a pipe 34 connected to the lower end thereof.

The fuel nozzle 14 is disposed approximately at the center of the inlet of the intake passage 17, and its jet orifice is directed toward the downstream side of the intake passage 17.

As shown in FIG. 4(a), the starting fuel metering device 81 has a hollow plunger 87 fitted into a cylinder 82 of a housing 94 to define a chamber 92a on the upper side and a metering chamber 92b on the lower side. The chamber 92a is connected to the primer pump 37 via the passage 38.
The measuring chamber 92b communicates with the passage 83 of the housing 94.
will be communicated to.

The plunger 87 is equipped with a seal ring 88 that provides liquid tightness between the plunger 87 and the cylinder 82 , so that the lower end 85 of the conical shape can face a seal member 93 fitted into the cylinder 82 .

A check valve 95 and a temperature-sensitive member 99 made of thermowax, for example, are arranged in the inner space of the plunger 87. Check valve 95
is the through hole 1 that communicates with the measuring chamber 92b provided in the plunger 87.
1886 is fitted and fixed in the inner space of the plunger 87 and the valve body 89 made of rubber etc. for opening and closing, and the jet hole 91
A plurality of protrusions are provided on the surface of the seat plate 90 facing the valve body 89 to prevent the jet hole 91 from closing even when the valve body 89 is pressed against the seat plate 90. It has become. The temperature sensing member 99 that is fitted and fixed into the inner space of the plunger 87 has a radial passage 99b that communicates with the jet hole 91 cut in the bottom wall, and an axial passage 99a cut in the peripheral wall. It is equipped with The temperature sensing member 99 is filled with wax, and the rod 97 is pushed up against the force of the spring 84 due to thermal expansion of the wax. The spring 84 is interposed between a spring seat integrally formed in the middle portion of the rod 97 and a cup-shaped spring seat 98 screwed onto the upper end of the plunger 87. The stroke S of the plunger 87 is limited to the dimension between the rod 97 that projects upwardly from the plunger 87 and the end wall of the cylinder 82, that is, the lower surface of the casing 53.

In the embodiment shown in FIG. 5, the temperature sensing member 99 is supported on the end wall of the cylinder 82 rather than the plunger.

Specifically, a cup-shaped spring seat 98 is screwed into the cylindrical portion of the cover 15 to fix the temperature sensing member 99 to the inner end of the cylindrical portion, and the corresponding component is shown in FIG. The same reference numerals will be used and the explanation will be omitted.

Next, the operation of the starting fuel supply device for an internal combustion engine for a portable working machine according to the present invention will be explained. Box 2 before starting engine 27
When the switches 44 and 45 shown in the figure are closed and the pump switch 52 is closed, the primer pump 37 is rotated forward by the motor 36. The fuel in the metering chamber 16 in FIG.
The measuring chamber 92 in FIG. 4(a) is reached through the check valve 39 and the passage 83.
b, and roughly pushes open the check valve 95 from the passage 86 of the plunger 87 to the jet hole 91, passage 99b,
Primer pump 37 via 99a1 chamber 92a and passage 38
be sucked into. Fuel is charged from the primer pump 37 to the vl reservoir 32 via the passage 30 in FIG. Excess fuel is released by pushing open the relief valve 33 and passing through the pipe 34 to the fuel tank 3.
Returned to 5. At this time, the plunger 87 is sucked up by the fluid resistance of the jet hole 91 and the suction force of the primer pump 37, and the rod 97 of the temperature sensing member 99 hits the upper end wall of the cylinder 82, that is, the casing 53.

Next, when the pump switch 52 shown in FIG. 2 is opened and the start switch 54 is switched, the m degree switch 8
is closed, the switch 45 is disconnected from the power supply battery 41.
, the temperature switch 8, the changeover switch 56, the motor 36, and the changeover switch 55 are energized, and the primer pump 37 is reversed. At the same time, starter motor 46 is driven.

Fuel in the fuel reservoir 32 shown in FIG. 3 is sucked into the primer pump 37 through the passage 30, and is further discharged from the primer pump 37 through the passage 38 into the chamber 92a shown in FIG. 4(a). The check valve 95 is closed by the fuel pressure in the chamber 92a, and the plunger 87 is pushed down and pressed against the sealing member 93. The fuel in this metering chamber 92b flows through the passage 83 in FIG.
．． 31, the fuel is ejected from the nozzle 14 to the intake passage 17 via the check valve 29, so that the engine 27 is smoothly started by the starter motor 46.

The amount of starting fuel supplied from the metering chamber 92b to the fuel nozzle 14 is determined by the stroke S of the plunger 87, and this stroke S is determined by the amount of protrusion of the plunger 97 that protrudes from the sensing member 99 that senses the ambient temperature. . That is, the sixth
As shown in the figure, when the ambient temperature is below t1, the rod 97 is retracted into the plunger 87 and the maximum starting fuel fiQ2 is reached, but when the ambient temperature becomes higher than tl,
The amount of protrusion of the rod 97 from the top end of the plunger 87 increases approximately in proportion to the ambient temperature, and as a result, the stroke S of the plunger V87 becomes smaller, and the amount of starting fuel supplied from the metering chamber 92b to the fuel nozzle 17 decreases. .

Note that even in cold weather, when restarting the engine immediately after stopping it, the ambient temperature around the engine is high, so the temperature switch 8 flashes and the primer pump 37 is not reversed, thus preventing the engine from starting. No fuel is supplied.

[Effects of the Invention] As described above, the present invention is capable of metering the starting fuel by rotating the pump in the normal direction to fill the fuel from the fuel tank into the fuel reservoir through the starting fuel GI agricultural device having a plunger by rotating the pump in the normal direction. In a device that operates the plunger of the device and injects fuel from the metering chamber into the intake passage of the carburetor, it is equipped with a temperature-sensitive member that limits the stroke of the plunger in relation to the ambient temperature 1, so that changes in the ambient temperature of the engine can be prevented. The stroke (operating range) of the plunger of the starting fuel metering device changes automatically depending on the ambient temperature, so that the amount of starting fuel delivered by the plunger from the metering chamber to the fuel nozzle automatically and continuously in relation to the ambient temperature. controlled. That is, the lower the ambient temperature is, the larger the stroke of the plunger becomes, and the amount of starting fuel increases accordingly. Therefore, the appropriate amount of starting fuel required by IIIpA corresponding to the temperature is supplied, and the startability of the engine is improved.

According to the present invention, it is sufficient to simply incorporate the sensing member inside the starting fuel metering device, and a complicated electric control circuit is not required, thereby reducing costs.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a starting fuel supply system for an internal combustion engine for a portable working machine according to the present invention, Fig. 2 is an electric control circuit diagram of the starting fuel supply system, and Fig. 3 is a dynamic fuel supply system. Side cross-sectional view of a vaporizer with Figures (a) and (b) are side sectional views showing the states before and after the operation of the starting fuel meter ffi device, Figure 5 is a side sectional view of a modified embodiment of the starting fuel metering device, and Figure 6 is a It is a microcosm showing the temperature characteristic of a heating member. 2: Carburetor 8: Temperature switch 14: Fuel nozzle 1
7 Two intake passages 27: Internal combustion engine 32: Fuel r4 reservoir 36
: Motor 37: Primer pump 81: Starting fuel il
ll loading 87: Plunger 91 Nijet hole ″92
b: Measuring chamber 95: Check valve 97: Rod 99 Two temperature sensing members

Claims (3)

[Claims] (1) When the pump rotates in the normal direction, fuel is filled from the fuel tank through the starting fuel metering device with a plunger into the fuel reservoir chamber.When the pump rotates in the reverse direction, the plunger of the starting fuel metering device is activated, and the fuel in the metering chamber is vaporized. 1. A starting fuel supply device for an internal combustion engine for a portable working machine, characterized in that the device is equipped with a temperature-sensitive member that limits the stroke of a plunger in relation to ambient temperature. (2) The starting fuel supply device for an internal combustion engine for a portable working machine according to claim (1), wherein the temperature-sensitive member is thermowax. (3) The internal combustion engine for a portable working machine according to claim (1), wherein the temperature-sensitive member is incorporated into a plunger of a starting fuel metering device, and the rod protrudes so as to be able to come into contact with an end wall of the housing. starting fuel supply system.