JPS6241955A - Device for feeding fuel for starting engine for portable work machine - Google Patents

Abstract

PURPOSE:To improve starting property by charging fuel in a metering chamber into an accumulator by the action of a priming pump and allowing said fuel to jet out from a fuel nozzle on the upper course side of a throttle valve via a manually openable fuel discharging valve. CONSTITUTION:A priming pump 85 is connected to the metering chamber 16 of a diaphragm type carburetor 2, to charge fuel in the metering chamber 16 into an accumulator 120. The accumulator 120 is connected to a fuel nozzle 81 provided on the upper course side of a throttle valve 20, via a fuel discharging valve 110. When starting an engine, the fuel discharging valve 110 is manually opened, to allow fuel in the accumulator 120 to jet out into an intake passage from the nozzle 81. Thereby, an air-fuel mixture required for starting can be efficiently atomized and fed, improving starting property.

Description

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

[Prior Art] A carburetor installed in a small two-stroke engine used as a drive source for portable working machines such as chainsaws and brush cutters is required to control the operating state of the engine well in any position. Therefore, one diaphragm type vaporizer is used. In this type of diaphragm type carburetor, fuel is stored in a constant pressure chamber (metering chamber) divided by a diaphragm, but due to the fuel tank running out of fuel or being left unused for a long time, the metering chamber The work must be carried out on a case-by-case basis depending on the engine situation, such as when there is no fuel in the engine, or when steam fuel has filled the intake passage and metering chamber, such as during a hot restart after engine operation under full load. It was difficult to start the engine because the operator had to perform different starting operations.

In order to solve and overcome such problems, the applicant stores fuel as starting fuel in a starting fuel chamber using a primer pump,
We have previously filed an application for a device that supplies fuel to the upstream side of the throttle valve of a carburetor using natural head.

However, the following problems remain in the starting fuel supply device according to this application as well. In other words, when starting a portable work machine engine while holding the portable work machine in hand, the engine may tilt, which changes the natural head and reduces the amount of starting fuel supplied. Variations are likely to occur. Additionally, since the supply of starting fuel is based on natural head, it takes time for the fuel to reach the carburetor, and this can be resolved by increasing the cross-sectional area of the supply passage, but this is not the case with small carburetors. In some cases, there may not be enough room to set up a number of aisles.

[Problems to be Solved by the Invention] Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a system in which the amount of starting fuel supplied does not affect the attitude of the engine, and to freely set the piping of the starting fuel chamber. An object of the present invention is to provide a starting fuel supply device for a portable working machine engine that can perform the following steps.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention maintains the pressure of the starting fuel at the discharge port side of the suction type primer pump that communicates with the metering chamber of the diaphragm type carburetor. A pressure accumulator is connected to the pressure accumulator, and the pressure accumulator chamber of the pressure accumulator is connected to the fuel tank via a relief valve, and the fuel is connected to the fuel tank upstream of the throttle valve of the diaphragm type carburetor via a fuel release valve that is manually opened when starting the engine. It is connected to a fuel nozzle placed on the side.

[Operation] When the push button 133 of the fuel release valve 110 is pushed in against the force of the spring 132 at the same time as engine starting (cranking), the pressure accumulation chamber 121 of the pressure accumulator 120 and the fuel nozzle 81 are released.
The passage 81a connecting the two is opened, and the fuel in the pressure accumulation chamber 121 is injected from the nozzle 81 toward the venturi 17 of the carburetor 2, and sufficient air-fuel mixture for starting is supplied to the engine, ensuring that the engine starts. be lost. Since a sufficient amount of fuel is stored in the pressure accumulator 120, the engine can continue to operate.

Eventually, the vaporized fuel in the metering chamber 16 of the carburetor 2 and the passage from this metering chamber 16 to the fuel injection ports 21 and 24 is sucked into the engine 27 through the air supply passage, and a fuel tank 1 is placed in the metering chamber 16. Since liquid fuel is supplied from the engine, continuous operation of the engine is possible.

Fuel from the remetering chamber 16 is supplied to the pressure accumulator 120 to a suction type primer pump 85 connected to the carburetor 2, and excess fuel is returned to the fuel tank 1 via the relief valve 107.

[Examples of the Invention] The present invention will be described based on Examples. As shown in FIG. 1, the engine 27 has a diaphragm carburetor 2 and an air cleaner 28 attached to one side of a main body including a cylinder 65, and an exhaust muffler (not shown) attached to the other side. The fuel tank 1 is attached to the lower end of the engine 27, that is, below the crank chamber 71. The fuel tank 1 is supplied with fuel through an inlet closed by a cap 44. A filter (not shown) is housed inside the fuel tank 1, and a fuel pipe 9 connected to the filter is connected to the carburetor 2.
connected to the inflow lower of the

A known glue coil device is connected to the end of the crankshaft of the engine 27 via a one-sided clutch.

This recoil device is designed to rotate the crankshaft of the engine 27 via a one-way clutch when a rope wrapped around a pulley is pulled during startup.

The main body 3 of the carburetor 2 is connected to the side wall of a cylinder 65 via an intake pipe 51 made of a heat insulating material, and an intake passage including a venturi 17 is communicated with an intake boat 66 provided in the cylinder 65. A known throttle valve 20 is rotatably supported with a valve shaft 19 inside the intake passage including the venturi 17 .

The cover 4 is connected to the earthen wall of the main body 3 with the diaphragm 6 in between, while the cover 1 is connected to the lower wall with the diaphragm 11 in between.
5 are combined. The cover 4 is provided with a pulsating pressure introduction chamber 5 and connected to a crank chamber 71 of the engine 27 via a pipe 72 . Fuel chamber 6 divided by diaphragm 6
1 is connected to the inflow lower via a check valve 48. Further, the fuel chamber 61 is connected to the metering chamber 16 via a check valve 47, a passage 60, and an inflow valve 10. Metering room 1
An atmospheric chamber 62 between the diaphragm 11 and the cover 15, which partitions the diaphragm 6, is opened to the atmosphere through a hole 62a.

A one-valve type inflow valve 10 is disposed at the end of the passage 60 and is opened and closed by a l collar 13. That is, one end of the lever 13, which is rotatably supported on the wall of the metering chamber 16 with the shaft 12, is urged into engagement with the end of the inflow valve 10 by the force of the spring. The other end of the lever 13 abuts against a protrusion connected to the approximate center of the diaphragm 11. The metering chamber 16 is connected to the high speed fuel injection port 24 via a check valve 26 and a high speed fuel metering 1 valve 25. Further, the metering chamber 16 is connected to the low-speed fuel nozzle 21 via a check valve 23 and a low-speed fuel il quantity valve 22 .

A connecting pipe 1 is connected to the inlet side of the venturi 17 of the main body 3 of the carburetor 2.
An air cleaner 28 is connected via 13. This AC reach 28 is constructed by supporting a filter 88 at the end of a dish-shaped housing 87 connected to the connecting pipe 113 and having an outlet 82, and also coupled with a dish-shaped cap 90. are provided integrally.

A reinforcing rib 89 is provided on the inner surface of this cap 90,
It is lightly pressed against the filter 88.

According to the present invention, a pressure accumulator 120 and a fuel nozzle 81 are provided in order to supply starting fuel to the inlet side of the carburetor 2 at the time of starting the engine. In the illustrated embodiment, a fuel nozzle 81 is disposed on the upper wall of the connecting pipe 113 of the air cleaner 28 with its ejection direction directed toward the venturi 17 .

The pressure accumulator 120 is connected with a diaphragm 110a sandwiched between a housing 129 made of two parts, and a spring 109 is accommodated in a chamber 108 partitioned by the housing 129 to form a pressure accumulator 12.
1. This pressure accumulation chamber 121
An outlet of a primer pump 85 is connected to the primer pump 85 via a piping 84. Further, the pressure accumulation chamber 121 is connected to a pipe 112 via a relief valve 107 which is normally closed by a spring 134, and this pipe 112 is connected to the fuel tank 1.

The housing 129 has a part that protrudes into the pressure accumulation chamber 121.
1. A fuel release valve 110 is provided to be opened;
The pressure accumulation chamber 121 is connected to the fuel nozzle 81 via the fuel release valve 110. Stem 13 of this fuel release valve 110
1 is slidably supported by the housing 129 and has a fuel release valve 110 between it and a push button 133 coupled to the outer end of the housing 129.
A spring 132 is interposed to bias the opening in the closing direction.

The primer pump 85 has a dropper 85a made of rubber or the like coupled to the cover 15, and is provided with a suction valve 52 and a discharge valve 53 at its inlet and outlet, respectively. Suction valve 5
2 is connected to the metering chamber 1 via passage 135.
Connected to 6.

Next, the operation of the starting fuel supply system for a portable working machine engine according to the present invention will be explained. Before starting the engine 27, press the dropper 85a repeatedly to remove the primer pump 8.
5, when the dropper 85a expands elastically, the inside becomes negative pressure, the suction valve 52 is opened, and the metering chamber 16 is opened.
of fuel is drawn into the dropper 85a through the passage 135.

Next, when the dropper 85a is crushed, the suction valve 52 is closed, the discharge valve 53 is pushed open, and the pressure accumulation chamber 1 is discharged from the pipe 84.
21.

10- The situation of fuel filled into the pressure accumulation chamber 121 can be sensed by the feeling of operating the primer pump 85, but if excessive fuel is supplied to the pressure accumulation chamber 121, the relief valve 107
is opened, and excess fuel is returned to the fuel tank 1 from the pipe 112 without being discharged to the outside.

Next, when the crankshaft of the engine 27 is rotated by a known glue coil device and the push button 133 is pressed at the same time, the fuel release valve 110 is opened and the fuel in the pressure accumulation chamber 121 is released through the fuel release valve 110. It is ejected from the nozzle 81 toward the venturi 17. Then, from the inlet 86 of the T-acreach 28, the filter 88, the outlet 82 and the connecting pipe 11
3 and the air flowing to the venturi 17, the air-fuel mixture with a relatively high concentration necessary and sufficient for starting is delivered to the intake port 6.
6 into the cylinder 65, and the engine can be started.

In this way, when the engine 27 is started, the crank chamber 7
A pulsating pressure of 1 is introduced into the pulsating pressure inlet 5 of the carburetor 2, and the diaphragm 6 moves back and forth to expand and compress the volume of the fuel chamber 61. The liquid fuel in the fuel tank 1 passes through the fuel pipe 9 and the inflow lower, pushes open the check valve 48, enters the fuel chamber 61, roughly pushes open the check valve 47, flows into the passage 60, and the inflow valve 10 opens. When the metering room 16 is in use, the metering room 16 is replenished.

When the fuel in the metering chamber 16 decreases, the pressure in the metering chamber 16 decreases.
The pressure of 2 pushes up the diaphragm 11, and when the lever 13 is rotated clockwise about the shaft 12, it opens. When the metering chamber 16 is filled with fuel, the diaphragm 11 is pushed down and the inflow valve 10 is closed.

In this way, the fuel that has been intermittently replenished into the metering chamber 16 is drawn into the intake passage from the fuel injection ports 21, 24 by the intake negative pressure of the venturi 17, mixed with air, and supplied to the engine 27.

If the engine 27 is operated with fuel from the carburetor 2, the engine will continue to operate even if the push button 133 is released.

[Effects of the Invention] As described above, in the present invention, when the engine is started, the primer pump 85 connected to the metering chamber 16 of the diaphragm type carburetor transfers fuel from the metering chamber 16 to the pressure accumulator 1.
20, manually open the fuel release valve 110, and the fuel in the pressure accumulator 120 is ejected from the fuel nozzle 81 disposed upstream of the throttle valve 20 into the intake passage. It is very simple and the pressure accumulator 12
0 holds the starting fuel in a pressurized state, so the installation location of this pressure accumulator 120 can be freely selected, and the fuel from the pressure accumulator 120 is transferred to the throttle valve 2 of the carburetor 2.
Since the fuel is injected at high speed to the upstream side of 0, the injected fuel is efficiently atomized, and sufficient air-fuel mixture for starting is supplied to the engine 27, so that the engine 27 can be started reliably and after starting. Operation is maintained.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing the configuration of a starting fuel supply device for a portable working machine engine according to the present invention. 1: Fuel tank 2: Carburetor 16: Metering room
20: Throat 1-le valve 27: Engine 28: Air cleaner 66: Intake port 1-71: Crank chamber 81:
Fuel nozzle 85: Primer pump 110: Fuel release valve 110a: Diaphragm 113: Connection pipe 120
: Pressure accumulator 121: Pressure accumulator

Claims (1)

[Claims] A pressure accumulator that maintains the pressure of starting fuel is connected to the discharge port side of the suction type primer pump that communicates with the metering chamber of the diaphragm type carburetor, and the pressure accumulator of the pressure accumulator is connected to the fuel tank via a relief valve. , a starting fuel supply device for a portable working machine engine, characterized in that the device is connected to a fuel nozzle disposed upstream of the throttle valve of the diaphragm type carburetor through a fuel release valve that is opened by manual operation when starting the engine. .