WO2011074405A1

WO2011074405A1 - Engine for working machine

Info

Publication number: WO2011074405A1
Application number: PCT/JP2010/071404
Authority: WO
Inventors: 博冨田
Original assignee: 株式会社マキタ
Priority date: 2009-12-17
Filing date: 2010-11-30
Publication date: 2011-06-23
Also published as: JP2011127501A

Abstract

Provided is an engine for a working machine, wherein it is possible to use fuels having different concentrations of ethanol. A vaporizer (100) is used to adjust the mixing ratio of air and fuel within an air mixture, which is supplied to a combustion chamber (8), depending on the proportion of ethanol contained in the fuel being used. Thus, the fuel within the air mixture can be adjusted to be at an appropriate amount in response to the proportion of ethanol contained in the fuel, the engine can be reliably started even if fuels having different ethanol content were to be used, and it is possible to obtain the required output.

Description

Engine for work equipment

The present invention relates to an engine used for a working machine such as a brush cutter.

Conventionally, as this kind of work machine engine, a combustion chamber for inhaling an air-fuel mixture to explode, a piston reciprocating by an explosion pressure generated in the combustion chamber, and a piston linked to the piston, A crankshaft for converting the reciprocating motion into a rotational motion and outputting it, a fuel tank for storing fuel, and a carburetor for generating an air-fuel mixture supplied to the combustion chamber by mixing fuel with air (For example, refer to Patent Document 1). In working engine engines, gasoline is widely used as a fuel. However, in recent years, in view of environmental problems and fuel cost problems, in addition to gasoline, ethanol mixed gasoline fuel in which ethanol is mixed with gasoline and a volume ratio of 90 are used. Ethanol is used as a fuel, such as an ethanol fuel composed of a percentage or more ethanol.

Japanese Patent Laid-Open No. 10-288020

There are a plurality of types of fuel containing ethanol depending on the concentration of ethanol, and each has different combustion characteristics. However, in the working machine engine, since the mixing ratio of fuel and air in the mixture supplied to the combustion chamber is fixed to a predetermined mixing ratio, fuel other than the fuel having the ethanol concentration suitable for use is used. As a result, the startability may deteriorate, or even if the engine is started, the predetermined ability may not be exhibited.

An object of the present invention is to provide a working machine engine that can use fuels having different concentrations of ethanol.

According to the first aspect of the present invention, there is provided a combustion chamber for inhaling and exploding an air-fuel mixture, a piston that reciprocates due to an explosion pressure generated in the combustion chamber, and a reciprocating motion of the piston linked to the piston. A crankshaft for converting the fuel into fuel, a fuel tank for storing fuel containing ethanol, and fuel in the mixture supplied to the combustion chamber according to the proportion of ethanol contained in the fuel used. And a mixing ratio adjusting means capable of adjusting the mixing ratio of air.

According to a second aspect of the present invention, the mixing ratio adjusting means comprises a fuel adjusting mechanism for adjusting the amount of fuel mixed with air in the carburetor.
According to a third aspect of the present invention, the fuel adjustment mechanism switches the ratio of the fuel in the mixture to two stages.
According to a fourth aspect of the present invention, the fuel adjustment mechanism includes an ethanol mixed gasoline fuel obtained by mixing ethanol and gasoline so as to contain ethanol in a volume ratio of 22% to 28%, and ethanol in a volume ratio of 90% or more. Switch to ethanol fuel.
In the invention of claim 5, the fuel adjustment mechanism is set so that the mass ratio of the fuel in the air-fuel mixture is 6.5% or more in the case of the ethanol mixed gasoline fuel, and when the fuel is the ethanol fuel, The mass ratio of the fuel in the air-fuel mixture is set to 8.5% or more.
In a sixth aspect of the invention, the mixture ratio adjusting means is applied to a four-cycle engine.
According to a seventh aspect of the invention, the mixing ratio adjusting means is a diaphragm type vaporizer.

1 is a front sectional view of a 4-cycle engine showing an embodiment of the present invention. It is side surface sectional drawing of a 4-cycle engine. It is a front sectional view of a vaporizer. It is principal part front sectional drawing of a vaporizer. FIG. 5 is a cross-sectional view taken along the line AA ′ of FIG. It is a figure which shows the opening degree of a throttle valve. It is front sectional drawing which shows the adjustment task screw and main jet according to the opening degree of the throttle valve at the time of using E25 as a fuel. It is a top sectional view showing an adjustment task screw and a main jet according to the opening degree of the throttle valve when E25 is used as fuel. It is front sectional drawing which shows the adjustment task screw and main jet according to the opening degree of the throttle valve at the time of using E100 as a fuel. It is a top sectional view showing an adjustment task screw and a main jet according to the opening of a throttle valve when using E100 as fuel. It is an exploded view of a secondary filter.

FIG. 1 is a front sectional view of a four-cycle engine used in a brush cutter, and FIG. 2 is a side sectional view.
As shown in FIGS. 1 and 2, the four-cycle engine 1 accommodates a piston 4 in a cylinder block 2 so as to be capable of reciprocating. A cylinder head 6 is integrally provided on one end side in the longitudinal direction of the cylinder block 2 (upward in the drawing), and a combustion chamber 8 is formed by the upper surface of the cylinder block 2, the cylinder head 6 and the piston 4. .
An oil pan 10 is fixed to the other end side in the longitudinal direction of the cylinder block 2 (downward in the figure), and the crankcase 12 is configured by the cylinder block 2 and the oil pan 10.

A crank chamber 14 is formed inside the crankcase 12, and a crankshaft 16 is rotatably supported so that both ends protrude from the crank chamber 14. The crankshaft 16 is connected to the piston 4 by a connecting rod 18, and the reciprocating motion of the piston 4 is converted into the rotational motion of the crankshaft 16 through the connecting rod 18.
An oil reservoir chamber 20 is provided in the crankcase 12 for storing lubricating oil for lubricating each engine. The oil reservoir chamber 20 is partitioned from the crank chamber 14 by a partition wall 2a formed in the cylinder block 2 as shown in the figure, and is a sealed space. Thereby, in a portable working machine such as a brush cutter, the lubricating oil does not scatter from the oil reservoir chamber 20 even when the top and bottom is turned upside down or turned sideways during use.

Further, as shown in FIG. 2, a communication path 22 is formed in the crankcase 12. One end of the communication passage 22 opens into the oil reservoir chamber 20 and the other end faces the periphery of the crankshaft 16 in the crank chamber 14. A pipe 24 having flexibility is connected to the opening on the oil reservoir chamber 20 side in the communication passage 22. A weight 26 is provided at the tip of the pipe 24, and even if the four-cycle engine 1 is tilted, the pipe 24 follows the displacement of the liquid level of the lubricating oil, so that the lubricating oil in the oil reservoir chamber 20 is surely secured. Can be inhaled.

Further, the crankshaft 16 is formed with a lubricating oil passage 16a that communicates the communication passage 22 and the crank chamber 14 during the rotation thereof, and lubrication in the oil reservoir chamber 20 is caused by the negative pressure action generated in the crank chamber 14. Oil is guided to the crank chamber 14 through the pipe 24, the communication passage 22 and the lubricating oil passage 16a. The lubricating oil introduced into the crank chamber 14 is scattered mainly from the crank web or the like by the rotation of the crankshaft 16 and lubricates the piston 4 and various components in the crank chamber 14. At this time, a part of the lubricating oil scattered in the crank chamber 14 is misted and guided to a side chamber 50 or a valve operating chamber 52 described later via a passage (not shown), whereby the side chamber 50 or the valve operating chamber is Various components provided in 52 are also lubricated. The lubricating oil guided to the side chamber 50 and the valve operating chamber 52 is returned again into the crank chamber 14 from a return passage (not shown) by a negative pressure effect generated by the lifting and lowering action of the piston 4. The partition wall 2 a is provided with a one-way valve 28 that allows only the lubricating oil to flow from the crank chamber 14 to the oil reservoir chamber 20. The one-way valve 28 is opened by the pressurizing action in the crank chamber 14 and returns the lubricating oil lubricated with various components to the oil reservoir chamber 20.

The cylinder head 6 is formed with an intake port 30 that guides an air-fuel mixture generated in the carburetor 100 described later to the combustion chamber 8 and an exhaust port 34 that guides exhaust gas generated in the combustion chamber 8 to the exhaust muffler 32. Has been. The cylinder head 6 is provided with an intake valve 36 for opening and closing the intake port 30 with respect to the combustion chamber 8 and an exhaust valve 38 for opening and closing the combustion chamber 8 with respect to the exhaust port 34. The intake valve 36 and the exhaust valve 38 are opened and closed by a valve operating mechanism 40.

As shown in FIG. 2, in the present embodiment, the valve mechanism 40 is a so-called OHV type valve mechanism. The valve mechanism 40 has a crankshaft gear 42, a camshaft 44, rocker arms 46, 48, and the like as main components. The crankshaft gear 42 and the camshaft 44 are provided in a side chamber 50 formed along the cylinder block 2 and the crankcase 12, and the rocker arms 46 and 48 are formed further upward in the drawing than the cylinder head 6. Provided in the valve operating chamber 52.

The crankshaft gear 42 rotates integrally with the crankshaft 16 in the side chamber 50. The camshaft 44 is provided with a camshaft gear 44 a that meshes with the crankshaft gear 42 in the side chamber 50 and rotates the camshaft 44 by ½ rotation of the crankshaft 16. Further, the camshaft 44 is provided with a cam 44 b that rotates integrally with the camshaft 44. One end of the push rod 54 is in contact with the cam 44b, and the push rod 54 moves in the longitudinal direction by the rotation of the cam 44b. The other end of the push rod 54 is connected to the rocker arms 46 and 48 described above, and the rocker arms 46 and 48 swing as the push rod 54 moves. As the rocker arms 46 and 48 swing, the intake valve 36 and the exhaust valve 38 move up and down, respectively, thereby opening and closing the intake port 30 and the exhaust port 34.

The intake valve 36 opens in the intake process in which the piston 4 moves from the top dead center to the bottom dead center. In this intake process, the air-fuel mixture is sucked into the combustion chamber 8 from the intake port 30 by the action of the negative pressure generated as the volume increases in the combustion chamber 8. Thus, the vaporizer 100 generates the air-fuel mixture sucked into the combustion chamber 8. The carburetor 100 mixes the fuel guided from the fuel tank 56 with the air that has passed through the air cleaner to generate an air-fuel mixture.
As already described, in consideration of the possibility that the top and bottom may be reversed or turned sideways during use, in this embodiment, the vaporizer 100 is a diaphragm type so that it can be used in any direction. It is configured. Below, the structure of the vaporizer | carburetor 100 is demonstrated using FIG.

As shown in FIG. 3, the vaporizer 100 includes a vaporizer body 102. The carburetor main body 102 is formed with a pulse passage 104 communicating with the crank chamber 14, and this pulse passage 104 faces one side (upper surface in the drawing) of the pump diaphragm 106. A pump chamber 108 is formed on the other side (the lower surface in the drawing) of the pump diaphragm 106. A fuel inlet 112 communicates with the pump chamber 108 via an inlet valve 110, and a diaphragm chamber 118 communicates with an outlet valve 114 and a needle valve 116. The fuel inlet 112 is connected to the fuel tank 56 via a suction pipe 200 and a suction pipe 62 described later (see FIG. 1).

In the crank chamber 14, positive pressure and negative pressure interact with each other as the volume changes, and this pressure change acts on the pump diaphragm 106 via the pulse passage 104. Thereby, the pump diaphragm 106 performs a wave motion. When a negative pressure is applied to the pump chamber 108 side by the movement of the pump diaphragm 106, the inlet valve 110 is opened while the outlet valve 114 is closed, and fuel is drawn into the pump chamber 108 from the fuel inlet 112. On the other hand, when a positive pressure is applied to the pump chamber 108 side by the movement of the pump diaphragm 106, the outlet valve 114 is opened while the inlet valve 110 is closed, and fuel is discharged from the pump chamber 108 to the diaphragm chamber 118. The

The diaphragm chamber 118 is separated from the back pressure chamber 122 by the metal ring diaphragm 120. A negative pressure of the engine acts on the back pressure chamber 122, and the metering diaphragm 120 is operated by a pressure difference between the negative pressure of the engine and the diaphragm chamber 118. The metering diaphragm 120 is connected to the needle valve 116 via a control lever 124, and the needle valve 116 is opened and closed by the operation of the metering diaphragm 120. Specifically, when the diaphragm chamber 118 is filled with fuel, the diaphragm chamber 118 is pressurized and the metering diaphragm 120 is operated toward the back pressure chamber 122 side. At this time, due to the elastic force of the control lever spring 126, the control lever 124 rotates so that one end (left side in the figure) is pushed down and the other end (right side in the figure) is pushed up. The needle valve 116 is pushed up by such a turning operation of the control lever 124, and the communication between the pump chamber 108 and the diaphragm chamber 118 is blocked.

Further, the vaporizer body 102 is formed with a passage 128 that connects the intake port 30 formed in the cylinder head 6 and an air cleaner (not shown). The passage 128 has an upstream side (air cleaner side) as a large-diameter portion 128a and a downstream side (intake port 30 side) as a venturi portion 128b having a smaller diameter than the large-diameter portion 128a. A throttle valve 130 is provided for displacing the valve. The throttle valve 130 has a rotational axis orthogonal to the passage 128, and rotates while sliding in the vertical direction in the figure by operating the rotation lever 130a. The opening degree of the venturi portion 128b is displaced by the amount of rotation. .

Also, the throttle valve 130 is provided with a first adjuster screw 131 for finely adjusting the amount of fuel mixed with the air flowing through the passage 128 coaxially with the rotation shaft. The first adjuster screw 131 is provided with a second adjuster screw 132 coaxially with the rotation axis thereof. The second adjuster screw 132 is provided so as to extend in the vertical direction in the drawing, and its outer dimension decreases in two stages from the outer diameter dimension substantially the same as the inner diameter dimension of the nozzle 134 described later from above to below. A switching portion 132a for switching a main jet 136 described later is provided at the tip of the second adjustment task screw 132. The first adjuster screw 131 moves downward in the figure when rotated in one direction (screw tightening direction) with respect to the throttle valve 130, and conversely, rotates in the other direction (screw return direction) with respect to the throttle valve 130. Then, it moves upward in the figure. Similar to the first adjustment task screw 131, the second adjustment task screw 132 moves downward in the figure when rotated in one direction (screw tightening direction), and conversely, the first adjustment task screw 132. When it rotates to the other side (screw unwinding direction) 131, it moves upward in the figure.

Further, the vaporizer body 102 is provided with a nozzle 134 so as to face the second adjuster screw 132, and the tip of the second adjuster screw 132 is inserted into the nozzle tip 134 a of the nozzle 134.
Further, a hole 134 b that opens to the passage 128 is formed in the nozzle 134, and a base end 134 c that communicates with the hole 134 b faces the diaphragm chamber 118. A main jet 136 and a main check valve 138 as a mixing ratio adjusting unit and a fuel adjusting mechanism are provided between the hole 134b and the diaphragm chamber 118.

As shown in FIGS. 4 and 5, the main jet 136 has a first main jet portion 136a that communicates the hole 134b of the nozzle 134 and the diaphragm chamber 118 with a predetermined opening area, and an opening area larger than the first main jet portion 136a. A second main jet portion 136b that communicates the hole 134b of the nozzle 134 and the diaphragm chamber 118 is provided. In the main jet 136, one of the first main jet portion 136 a and the second main jet portion 136 b is closed by the switching portion 132 a of the second adjustment task 132, and the other communicates the hole 134 b of the nozzle 134 and the diaphragm chamber 118. The main jet 136 rotates the second adjuster screw 132 with respect to the first adjuster screw 131, thereby switching between closing and opening of the first main jet part 136a and the second main jet part 136b.
That is, the main jet 136 causes the fuel to flow to one of the first main jet portion 136a and the second main jet portion 136b by rotating the second adjustment task screw 132 with respect to the first adjustment task screw 131 according to the fuel to be used.

In this embodiment, as fuel, an ethanol mixed gasoline (hereinafter referred to as E25) in which gasoline and ethanol are mixed so as to contain about 25 percent (22 percent or more and 28 percent or less) ethanol by volume, and about 100 percent. Ethanol (90% or more by volume) (hereinafter referred to as E100) is selected and used. Further, the opening area of the first main jet portion 136a is set in accordance with the required air / fuel ratio of E25 from the volume of fuel to be mixed with the unit weight of air calculated from the theoretical air / fuel ratio of E25 and the stoichiometric fuel / air ratio of E100. The opening area of the second main jet portion 136b is set in accordance with the required air / fuel ratio of E100. Further, the first main jet portion 136a is set so that the mass ratio of the fuel in the air-fuel mixture becomes 6.5% or more by calculating from the theoretical air fuel ratio of E25. Further, the second main jet portion 136b is set so that the mass ratio in the air-fuel mixture becomes 8.5% or more by calculating from the theoretical air / fuel ratio of E100.

In the carburetor 100, when the intake valve 36 is opened, air having a flow rate corresponding to the opening of the throttle valve 130 passes through the passage 128 from the air cleaner toward the intake port 30. At this time, the flow velocity of air increases in the venturi portion 128b, and the fuel is sucked up from the diaphragm chamber 118 by the negative pressure action near the nozzle 134. The fuel sucked up from the diaphragm chamber 118 is sucked out into the passage 128 through the hole 134b. In this way, an air-fuel mixture is generated, and this air-fuel mixture is guided to the combustion chamber 8 via the intake port 30. The amount of fuel mixed in the air is controlled as follows according to the opening of the throttle valve 130, that is, the air flow rate.

First, when the four-cycle engine 1 is in an idle state, as shown in FIG. 6A, the opening degree of the venturi portion 128b is throttled by the throttle valve 130, and a slight amount of air passes through the passage 128. At this time, the amount of fuel sucked out from the hole 134 b can be adjusted by the position of the second adjuster screw 132 with respect to the throttle valve 130. That is, in order to use E25 as the fuel, when the second adjuster screw 132 is set to a position rotated in one direction (screw tightening direction), as shown in FIGS. 7A and 8A, the switching unit 132a As a result, the second main jet portion 136b is closed and the first main jet portion 136a is opened, and the opening of the hole 134b is minimized. Further, when the second adjuster screw 132 is rotated in the other direction (in the screw return direction) in order to set the fuel to E100, as shown in FIG. 9A and FIG. The part 136a is closed and the second main jet part 136b is opened. At this time, a portion where the outer diameter of the second adjustment task screw 132 is reduced by one step is located in the hole 134b, and the opening degree of the hole 134b becomes larger than when the fuel is set to E25. Therefore, the amount of fuel sucked out from the hole 134b is larger than that in the case of setting E25, and the concentration of the fuel contained in the air-fuel mixture becomes higher. Thus, by operating the second adjustment task 132, it is possible to simultaneously adjust the concentration of the air-fuel mixture in the idle state at E25 and E100 and the concentration of the air-fuel mixture when fully open. The first adjuster screw 131 finely adjusts the amount of fuel mixed with the air flowing through the passage 128 by rotating the throttle valve 130 with the second adjuster screw 132 set to E25 or E100. I do.

When the rotary lever 130a is rotated from the above-described idle state, as shown in FIG. 6B, the throttle valve 130 rotates while sliding in the direction of the rotation axis, the opening degree of the venturi portion 128b increases, and the passage 128 Increases the flow rate of air passing through. At this time, the second adjuster screw 132 also slides upward in FIG. 3 together with the throttle valve 130. Therefore, when the second adjustment task screw 132 is set to use E25 as the fuel, as shown in FIGS. 7B and 8B, the second adjustment task screw 132 is closed with the second main jet portion 136b closed. Pulled upward. As a result, the portion where the outer diameter of the second adjustment task screw 132 is reduced by one step is located in the hole 134b, the opening of the hole 134b is increased, and the amount of fuel sucked into the passage 128 becomes the above-mentioned idle state. More than that. When the second adjustment task screw 132 is set to use E100 as fuel, as shown in FIGS. 9B and 10B, the second adjustment task screw 132 is closed with the first main jet portion 136a closed. Pulled upward. Thereby, the upper end of the portion where the outer diameter of the second adjustment task screw 132 is the smallest is positioned in the hole 134b portion, and the opening degree of the hole 134b becomes larger than that in the case where E25 is used as fuel.

Then, when the rotating lever 130a is further rotated from the above state, as shown in FIG. 6C, the throttle valve 130 rotates while further sliding in the rotation axis direction, and the opening degree of the venturi portion 128b is maximized. . In addition, the second adjuster screw 132 is further lifted together with the throttle valve 130. Therefore, when the second adjustment task screw 132 is set to use E25 as the fuel, as shown in FIGS. 7C and 8C, the second adjustment task screw 132 is further closed while the second main jet portion 136b is closed. Is raised upward. As a result, the portion of the hole 134b where the outer diameter of the second adjuster screw 132 is the smallest is located, the opening of the hole 134b is increased, and the amount of fuel sucked into the passage 123 is larger than that in the above state. Become more. When the second adjustment task screw 132 is set to use E100 as fuel, as shown in FIGS. 9C and 10C, the second adjustment task screw 132 is further closed while the first main jet portion 136a is closed. Is raised upward. As a result, the portion where the outer diameter of the second adjuster screw 132 is the smallest is located in the hole 134b portion, and the opening degree of the hole 134b becomes larger than in the case where E25 is set as fuel.

As shown in FIG. 3, the vaporizer main body 102 is configured to be manually compressed and expanded, and is provided with a primer pump 140 for generating a negative pressure in the diaphragm chamber 118 by the operation. When the primer pump 140 is operated, the diaphragm chamber 118 becomes negative pressure, so that fuel is sucked up from the fuel tank 56 into the diaphragm chamber 118. At this time, the main check valve 138 functions to prevent air from flowing from the passage 128 into the diaphragm chamber 118 via the nozzle 134. The sucked fuel is returned from the diaphragm chamber 118 to the fuel tank 56 through the overflow pipe 142.

Here, as shown in FIG. 1, the vaporizer 100 and the fuel tank 56 are connected by a suction pipe 200 and a return pipe 202.
More specifically, the fuel tank 56 has a substantially U-shaped cross section and is disposed so as to cover the crankcase 12. In the fuel tank 56, a cap fitting hole 58 is formed in a portion facing the vaporizer 100, and the cap 60 is fitted in the cap fitting hole 58. The cap 60 is inserted through the return pipe 202 in a press-fitted state. One end of the return pipe 202 is press-fitted and fixed to the overflow pipe 142 of the vaporizer 100, and the other end is positioned in the fuel tank 56. Thereby, the fuel sucked into the diaphragm chamber 118 by the operation of the primer pump 140 is returned to the fuel tank 56 through the overflow pipe 142 and the return pipe 202.

Further, the cap 60 is penetrated with the suction pipe 62 being press-fitted and fixed. The suction pipe 62 has flexibility, one end 62 a is connected to the suction pipe 200 via a connecting member 204 described later, and the other end 62 b is located in the fuel tank 56. ing. The suction pipe 62 is longer than the return pipe 202, and can enter the fuel tank 56. Further, a primary filter 64 for removing impurities in the fuel is provided at the end 62b of the suction pipe 62 so that the impurities do not enter the suction pipe 62 when the fuel is guided to the vaporizer 100. I have to. A weight 66 is provided around the primary filter 64 so that the suction pipe 62 follows the displacement of the fuel level even if the four-cycle engine 1 is tilted. As a result, the fuel in the fuel tank 56 is reliably sucked even when the four-cycle engine 1 is tilted in any direction.

The suction pipe 62 and the suction pipe 200 are connected via a connection member 204 as shown in FIG. In other words, the connecting member 204 includes a hollow cylinder 204a and a lid 204b that is fixed to the cylinder 204a by screwing. The suction pipe 200 is fixed to the cylindrical body 204a by press-fitting, an adhesive, or the like. Similarly, the end portion 62a of the suction pipe 62 is fixed to the lid body 204b. A through-hole is formed in the lid 204b, and the suction pipe 62 and the suction pipe 200 communicate with each other by screwing the lid 204b to the cylindrical body 204a.
In addition, a secondary filter 206 and a spring 208 for pressing the secondary filter 206 from the lid 204b side to the cylinder body 204a are provided in the cylinder body 204a. The area of the side surface of the secondary filter 206 is larger than the opening area of the suction pipe 200, and the secondary filter 206 is pressed against the entire opening of the suction pipe 200 by the elastic force of the spring 208, so that the fuel to be sucked in is reliably And pass through the secondary filter 206.

This secondary filter 206 removes substances (for example, celluloses, hereinafter referred to as “non-decomposed substances”) that remain without being decomposed during the production process of biomass ethanol when biomass ethanol is used as ethanol. It is intended. That is, in the process in which the fuel is guided from the fuel tank 56 to the vaporizer 100, first, impurities such as dust mixed in the fuel are removed by the primary filter 64. The fuel from which impurities have been removed by the primary filter 64 further passes through the secondary filter 206. In the course of the fuel passing through the secondary filter 206, non-decomposed substances contained in the fuel (biomass ethanol) are removed. Is done. In the present embodiment, as the secondary filter 206, a metal fiber having a property in which fine filter holes are formed and the fibrous body is three-dimensionally entangled in the fuel flow direction is used. In view of the above, it is more desirable to use stainless steel fibers.

As described above, in the working machine engine of the present embodiment, the mixing ratio of the fuel and air in the air-fuel mixture supplied to the combustion chamber 8 is adjusted according to the ratio of ethanol contained in the fuel used by the carburetor 100. I am doing so. As a result, the fuel in the air-fuel mixture can be set to an appropriate amount according to the proportion of ethanol contained in the fuel, so that even fuels with different ethanol contents can be reliably started to obtain the required output. It becomes possible.
Further, the vaporizer 100 adjusts the fuel / air mixture ratio in the air-fuel mixture. This eliminates the need for a separate dedicated device for adjusting the mixing ratio of the fuel and air in the air-fuel mixture, so that the working machine engine itself does not increase in size.
In addition, since the switching of the first main jet portion 136a and the second main jet portion 136b of the main jet 136 and the adjustment by the hole 134b at the time of medium / low speed are interlocked, the mixing ratio of the fuel and air in the air-fuel mixture is adjusted by a simple operation. Therefore, the operability can be improved.

In the present embodiment, the case where the present invention is applied to a four-cycle engine has been described. However, the present invention can also be applied to a two-cycle engine.
In addition, working machines to which the present invention is applicable include all machines that are connected to the crankshaft 16 and are operated by the rotational power of the crankshaft 16.
In addition, the shape and arrangement of the fuel tank 56, the carburetor 100, or the components such as the combustion system and the drive system such as the piston 4 and the crankshaft 16 in the present embodiment are merely examples, and are limited to the configuration of the present embodiment. Is not to be done.

Further, in the present embodiment, ethanol mixed gasoline (E25) in which gasoline and ethanol are mixed so that ethanol is contained in a volume ratio of about 25 percent, and about 100 percent ethanol (E100) can be selectively used as fuel. However, the present invention is not limited to this, and is not limited to this. Ethanol mixed gasoline (E10) mixed with 10% ethanol by volume, or ethanol mixed gasoline (E85) mixed with 85% ethanol by volume. It is applicable to ethanol blended gasoline with any ethanol concentration. In addition, the ethanol-mixed gasoline is not limited to those composed only of ethanol and gasoline, and includes those containing other substances such as a denaturant, a corrosion inhibitor, and a small amount of moisture mixed in the manufacturing process.

4 Piston 8 Combustion chamber 16 Crankshaft 56 Fuel tank 100 Vaporizer 130 Throttle valve 131 First adjuster screw 132 Second adjuster screw 134 Nozzle 134b Hole 136 Main jet 136a First main jet part 136b Second main jet part

Claims

A combustion chamber for inhaling and exploding the mixture,
A piston that reciprocates due to an explosion pressure generated in the combustion chamber;
A crankshaft linked to the piston for converting a reciprocating motion of the piston into a rotational motion and outputting the rotary shaft;
A fuel tank for storing fuel containing ethanol;
A working machine engine comprising: a mixing ratio adjusting means capable of adjusting a mixing ratio of fuel and air in an air-fuel mixture supplied to a combustion chamber according to a ratio of ethanol contained in a fuel to be used.
The working machine engine according to claim 1, wherein the mixing ratio adjusting means includes a fuel adjusting mechanism for adjusting an amount of fuel mixed with air in the carburetor.
The working machine engine according to claim 2, wherein the fuel adjustment mechanism switches a ratio of fuel in the air-fuel mixture in two stages.
The fuel adjustment mechanism switches between an ethanol mixed gasoline fuel in which ethanol and gasoline are mixed so as to contain ethanol in a volume ratio of 22% to 28%, and an ethanol fuel composed of ethanol in a volume ratio of 90% or more. 2. The working machine engine according to 2.
The fuel adjustment mechanism is set so that the mass ratio of the fuel in the air-fuel mixture becomes 6.5% or more in the case of ethanol-mixed gasoline fuel, and the mass of the fuel in the air-fuel mixture when the fuel is ethanol fuel The work machine engine according to claim 4, wherein the ratio is set to be 8.5 percent or more.
The working machine engine according to any one of claims 1 to 5, wherein the mixing ratio adjusting means is applied to a four-cycle engine.
The working machine engine according to any one of claims 2 to 6, wherein the mixing ratio adjusting means is a diaphragm type carburetor.