JPS6235047A - Fuel supply device for starting portable sevice machine engine - Google Patents

Abstract

PURPOSE:To improve starting characteristics by filling a pressure accumulator with fuel in a metering chamber to inject fuel from a nozzle at the upstream side of a throttle valve in low temperature start and hindering the injected fuel flowing into an intake path in high temperature start. CONSTITUTION:A primer pump 85 is connected to a metering chamber 16 of a diaphragm type carburetor 2 to fill a pressure accumulator 120 with fuel in the metering chamber 16 by the pump 85. the pressure accumulator 120 communicates to a fuel nozzle 81 provided at the upstream side of a throttle valve 20 in an intake path through a fuel injection valve 110. In low temperature engine the fuel injection valve 110 is opened by negative intake pressure at the same time as cranking to inject fuel in the pressure accumulator 120 from the nozzle 81 to a Venturi tube 17. In high temperature a control plate 79 is lowered by a heat sensitive member 73 so that fuel drips from the nozzle 81 to a porous material 83.

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 maintain good operating conditions of the engine in any position. Therefore, a diaphragm type vaporizer is used. This type of diaphragm type vaporizer is a constant pressure seedling (
metering chamber), but if there is no fuel in the metering chamber because the fuel tank has run out of fuel or has been left unused for a long time, or if the engine is restarted after full load operation. In some cases, such as when fuel vapor fills the intake passage or metering chamber, the operator must perform different starting operations each time depending on the engine usage status, making it difficult to start the engine. was difficult.

In order to solve such problems, the applicant has filed a patent application filed in 1983.
No. 0-15799 has been filed. However, since this device cannot take into account the thermal conditions of the engine, the operation of the choke valve or the start button is left to the operator's discretion. Automatic start control devices that are compatible with all starting conditions have already been put into practical use for automobile engines, but portable work machine engines that do not have a power source battery require electricity before starting! I11 control is not possible.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to be able to start the engine reliably with the same minimum number of operations under any engine condition or situation, and to improve the engine operation after starting. To provide a starting fuel supply device for an engine of a portable working machine, which can maintain a suitable condition and prevent fuel from being discharged to the outside regardless of the posture of the engine.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention includes a pressure accumulator that maintains the pressure of the primer fuel on the discharge port side of the suction type primer pump that communicates with the metering chamber of the diaphragm vaporizer. The pressure accumulator is connected to the fuel tank via a relief valve, and is connected to a fuel nozzle disposed on the inlet side of the carburetor via a fuel release valve that opens due to suction negative pressure when starting the engine by recoil operation. , a control member is provided which is connected to a heat-sensitive member that senses engine heat and controls the direction in which fuel is ejected from the pressure accumulator, and the fuel in the pressure accumulator is ejected in the direction of the throttle valve when the engine temperature is below a set temperature. be.

[Function] The heat-sensitive member 73 made of bimetal that senses the temperature of the engine 27 is connected to the control member 80 via a link mechanism, and the control plate 79 of the control member 80 is disposed upstream of the throttle valve 20. The fuel from the fuel nozzle 81 is controlled to be injected toward the venturi 17 and to be applied to the control plate 79 to be dripped and adsorbed onto the porous member 83 .

A fuel release valve 110 is connected to the fuel nozzle 81 from the pressure accumulator 120.
This fuel release valve 110 is supplied through the engine 27.
When intake negative pressure is introduced into the intake port 66 by cranking, the intake port 66 opens.

Fuel from the metering chamber 16 is supplied to the pressure accumulator 120 by a suction type primer pump 85 coupled to the carburetor 2.
Excess fuel is returned to the fuel tank 1 via the relief valve 107.

When the engine 27 is in a low temperature state, the fuel release valve 110 opens at the same time as cranking, and the fuel in the pressure accumulator 120 is ejected from the fuel nozzle 81 toward the venturi 17 of the carburetor 2, resulting in a relatively high concentration mixture. Since air is supplied to the engine 27, the engine 27
is definitely started.

On the other hand, when the engine 27 is in a high temperature state, the control board 79
As a result, the fuel from the fuel nozzle 81 is dripped into the porous material 83, and the relatively low concentration air-fuel mixture sucked from the fuel nozzle of the carburetor 2 is supplied to the engine 27, so that the engine 27 is smoothly and quickly supplied. is started.

[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 the 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 inflow lower of the carburetor 2.

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

When this recoil device pulls a lobe wrapped around a pulley during startup, the crankshaft of the engine 27 is rotated via a one-way clutch.

The vaporizer 2 connects the main body 3 to the shilling 65 via the heat insulating member 51.
An intake passage including a venturi 17 communicates 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 coupled to the upper wall of the main body 3 with the diaphragm 6 in between, while the cover 1 is coupled to the lower wall with the diaphragm 11 in between.
5 are combined. The cover 4 is provided with a pulsating pressure introduction port 5, and is connected to the 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 1o. 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 needle-type inflow valve 1o is disposed at the end of the passage 60 and is opened and closed by a lever 13. That is,
One end of a lever 13 rotatably supported on the wall of the metering seedling 16 with a shaft 12 is urged into engagement with the end of the inflow valve 10 by the force of a 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 26F3 and a high speed fuel metering needle valve 25. The metering chamber 16 also includes a check valve 23 and a low-speed fuel metering needle valve 2.
2 to the low-speed fuel nozzle 21.

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 air cleaner 28 is configured 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 9o, and an inlet 86 is connected to the cap 9o. Installed in one piece.

Eight reinforcing ribs are provided on the inner surface of this cap 9o,
It is lightly pressed against the filter 88.

According to the present invention, a fuel nozzle 81 is provided to automatically supply fuel to the inlet side of the carburetor 2 at the time of starting the engine. In the illustrated embodiment, the connecting pipe 1 of the air cleaner 28
A fuel nozzle 81 is disposed on the upper wall of the venturi 13 with its ejection direction directed toward the venturi 17 .

A control member 81 is provided that controls the direction of fuel jet from the fuel nozzle 81 based on the temperature conditions of the engine 27. That is, the control plate 79 can protrude facing the fuel nozzle 81.
is slidably supported by the connecting pipe 113. This control board 7
9 projects in front of the fuel nozzle 81 and blocks the ejected fuel from flowing toward the throttle valve 20 when the ejection of fuel from the fuel nozzle 81 is not required. For this reason, a porous member 83 is provided on the upstream side of the throttle valve 20, preferably on the lower wall of the connecting pipe 113, so that unnecessary fuel is adsorbed by the porous member 83.

Pressure accumulator 120 that holds fuel supplied to fuel nozzle 81
The diaphragm 10 is constructed integrally with the fuel release valve 110, and the diaphragm 10 is placed between the housing 129 divided into three parts.
5 and 110a, and a pressure accumulating chamber 121 is formed between the intermediate wall portion and the dial ram 110a. A diaphragm 110 that partitions this pressure accumulation chamber 121 and the chamber 108
a is the pressure accumulator 12 due to the spring 109 housed in the chamber 108.
1. And the pressure accumulation chamber 121
is connected with a pipe 84 to the outlet of a primer pump 85 attached to the cover 15 of the vaporizer 2.

Further, the pressure accumulation chamber 121 is connected to a pipe 112 via a relief valve 107, and this pipe 112 is connected to the fuel tank 1. Further, the accumulated pressure v121 is connected to the fuel nozzle 81 via the fuel release valve 110.

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.

The fuel release valve 110 has a valve body 103 supported by a diaphragm 105 that partitions the chamber 102 and v106, and is configured to close a passage communicating between the chamber 106 and the pressure accumulation chamber 121 by a spring 104. Chamber 106 is connected to fuel nozzle 81 . The air 102 is connected to the throttle valve 2 with the piping 101.
0 , specifically, to the intake passage of the heat insulating member 51 , so that negative intake pressure is introduced into the chamber 102 .

A control member 80 that controls the fuel jetting direction of the fuel nozzle 81
A control plate 79 is connected to one arm of the bell crank 77. This bell crank 77 is rotatably supported by a bracket provided on the connecting pipe 113 with a shaft 78, and the other arm is connected to the lever 75 of the heat sensitive member 73 via a link 76.

The lever 75 of the heat-sensitive member 73 is supported by the heat radiation part of the engine, specifically the cylinder head, with a shaft 74.
One end of a clockwork-shaped bimetal is connected to 4, and the other end is locked to the cylinder head.

Next, the operation of the starting fuel supply system for a portable working machine engine according to the present invention will be explained. When the engine 2.7 is in a cooling state, the heat-sensitive member 73 is in a tightened state, and the lever 75 is rotated clockwise, so that the bell crank 77
The control plate 79 is pulled up.

When the dropper 85a is pressed repeatedly to operate the primer pump 85 before starting the engine 27, the dropper 85a
When a expands elastically, the inside becomes negative pressure, the suction valve 52 opens, and the fuel in the metering chamber 16 is sucked 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. At this time, if the fuel tank 1 is empty of fuel, there is naturally no fuel in the metering chamber 16 either, and it is possible to sense that the fuel tank 1 is empty from the feeling of operating the primer pump 85. The state of the fuel filled into the pressure accumulator 121 can be detected by operating the primer pump 85. However, if excessive fuel is supplied to the pressure accumulation chamber 121, the relief valve 107 opens and the piping 11
2, excess fuel is returned to the fuel tank 11\.

Next, when the crankshaft of the engine 27 is rotated by a known glue coil device, the negative pressure in the intake boat 66 is transferred to the piping 10.
1 to the chamber 102 of the fuel release valve 110. Therefore, the diaphragm 105 resists the force of the spring 104.
At the same time, the valve body 103 is sucked to the left and opens, and the pressure accumulation chamber 1
21 of fuel is ejected from the fuel nozzle 81 toward the venturi 17 through the chamber 106. At the same time, air cleaner 28
from the inlet 86 to the filter 88, the outlet 82 and the connecting pipe 1
It is mixed with the air flowing through venturi 17 through 13,
A relatively highly concentrated air-fuel mixture is drawn into the cylinder 65 from the intake boat 66, allowing the engine to start.

Note that if the engine 27 is restarted soon after it has stopped operating, that is, when it is in a high temperature state, the heat-sensitive member 7
3 is expanded, the lever 75 is rotated counterclockwise, the bell crank 77 is rotated clockwise about the shaft 78 via the link 76, the control plate 79 is pushed down, and the fuel nozzle 81 is rotated. Block the front of the. Therefore, in this case, the fuel ejected from the fuel nozzle 81 hits the control plate 79, drops onto the porous member 83 and is adsorbed, and is not directly supplied to the engine 27, but is suitable for high temperatures. Starting is possible by supplying a relatively low-concentration air-fuel mixture to the engine.

Eventually, fuel is supplied from the fuel nozzles 24, 21 of the carburetor 2, and an appropriate air-fuel mixture is supplied to the engine for high-temperature starting of the engine.

In this way, when the engine 27 is started, the crank
The pulsating pressure of 1 is introduced into the pulsating pressure introducing space 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 fuel in the fuel tank 1 passes through the fuel pipe 9 and the inflow lower, pushes open the check valve 48 and enters the fuel v61,
It roughly pushes open the check valve 47 and flows into the passage 6o, and when the inflow valve 10 is open, it is replenished into the metering chamber 16.

When the fuel in the metering chamber 16 decreases, the pressure in the metering chamber 16 decreases.
The diaphragm 11 is pushed up by the pressure of 2, 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 is intermittently replenished into the metering chamber 16 is transferred to the check valve 23 by the intake negative pressure of the venturi 17.
When the fuel is opened, the low-speed fuel passes through the low-speed fuel metering needle valve 22, is drawn into the air supply passage from the low-speed fuel injection port 21, is mixed with air, and is supplied to the engine 27.

[Effects of the Invention] As described above, the present invention charges the fuel in the metering chamber 16 to the pressure accumulator 120 by the primer pump 85 connected to the metering chamber 16 of the diaphragm type carburetor, and the pressure accumulator 120 is filled with the fuel in the metering chamber 16. When starting the engine 27,
Since the fuel is ejected from the fuel nozzle 81 disposed upstream of the throttle valve 20 into the intake passage through the fuel release valve 110 that is opened by intake negative pressure, when the engine is in a low temperature state, the fuel nozzle The fuel ejected from 81 is mixed with air and supplied to the engine 27, and regardless of the state of the carburetor 2, an air-fuel mixture with a relatively high degree of a is supplied to the engine 27. start-up can be achieved reliably.

On the other hand, when the operation of the engine 27 is interrupted and then restarted soon, that is, when the engine is in a high temperature state, the seven control plates of the control section are lowered by the heat-sensitive member 73, and the fuel ejected from the rinsing nozzle 81 is transferred to the intake air. In this case, a relatively low concentration air-fuel mixture suitable for starting the engine in a high temperature state is supplied to the engine 27, and smooth engine starting is achieved.

Then, the driver operates the primer pump 85 in advance to fill the pressure accumulator 120 with starting fuel, and then cranks the fuel using the recoil device, which automatically supplies fuel to the engine according to engine conditions. Since the concentration of the air-fuel mixture is controlled, the operation is very simple and reliable starting can be obtained.

[Brief explanation of the drawing]

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, and FIG. 2 is a side sectional view of a pressure accumulator of the same device. 1: Fuel tank 2: Carburetor 16: Metering room
20: Throttle valve 27: Engine 28: Air cleaner 66: Intake boat 71: Crank chamber 73: Heat-sensitive member 75 Nilever 76: Link 77: Bell crank 79: Control board 80: Control member 81: Fuel nozzle 83: Porous member 85: Primer pump 105
．． 110a: Diaphragm 107: Relief valve 110:
Fuel release valve 113: Connection pipe 120: Pressure accumulator 121
:Accumulation chamber

Claims (2)

[Claims] (1) A pressure accumulator that maintains the pressure of the primer fuel is connected to the discharge port side of the suction type primer pump that communicates with the metering chamber of the diaphragm vaporizer, and the pressure accumulator is connected to the fuel tank via a relief valve, and the recoil It is connected to a fuel nozzle disposed on the inlet side of the carburetor through a fuel release valve that opens due to suction negative pressure when the engine is started by operation, and is connected to a heat-sensitive member that senses engine heat, and discharges fuel from the pressure accumulator. What is claimed is: 1. A starting fuel supply device for a portable work machine engine, comprising: a control member for controlling a jetting direction; and jetting fuel in the pressure accumulation chamber toward a throttle valve when the temperature of the engine is below a set temperature. (2) The control member is provided with a control plate that can protrude to a position facing the fuel nozzle, and a porous member is provided on the upstream side of the throttle valve, and when the temperature of the engine is higher than a set temperature, the control plate controls the fuel nozzle. The starting fuel supply device for a portable working machine engine according to claim (1), characterized in that the flow of fuel ejected from the porous member is adsorbed toward the porous member.