JP2011256755A - Small engine and engine working machine equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small engine which adjusts an amount of air-fuel mixture flowing into a crankcase by a device having a compact and simple structure, and an engine machine equipped with the same.SOLUTION: A small engine 1 includes a carburetor 4, a cylinder block 8 in which an intake opening 13 and intake port 14 are formed, an insulator 19 which is provided between the carburetor 4 and cylinder block 8 and with an intake passage 20 communicating between the intake port 14 and carburetor 4 and which contains a coil 26 producing magnetic flux through energization, and a reed valve 21 which has a magnetic body and which is provided to the intake passage 20 to be driven so as to close the intake passage 20 by electromagnetic force acting on an electromagnetic body at energization to the coil 26.

Description

  The present invention relates to a small engine, particularly a small engine suitable for a portable engine working machine such as a brush cutter or a chain saw, and an engine working machine including the same.

  In a two-cycle engine, for example, as shown in Patent Document 1, when the engine speed increases to a predetermined speed or more, the air-fuel mixture passage is displaced by displacing a blocking body assembled to the insulator by a driving body provided outside the insulator. Some of them are equipped with a governor device that adjusts the amount of air-fuel mixture flowing into the crank chamber by blocking the engine and prevents the engine from over-rotating.

JP-A-7-253033

  By the way, since the governor apparatus of patent document 1 has provided the transmission mechanism which displaces a drive body and a blocking body on the outer side of an insulator, the subject that a number of parts will increase, a structure will become complicated, and an apparatus will enlarge. is there.

  The present invention has been made in view of the above problems, and provides a small engine capable of adjusting the amount of air-fuel mixture flowing into the crank chamber by an apparatus having a compact and simple structure, and an engine working machine including the same. With the goal.

In order to achieve the above object, a small engine according to a first aspect of the present invention includes:
A vaporizer for supplying a fuel / air mixture;
The piston has an intake opening that opens and closes to a cylinder bore that reciprocates, and supplies the air-fuel mixture supplied from the carburetor to the crank chamber provided in the crankcase through the cylinder bore from the intake opening. A cylinder block in which an intake port is formed;
An insulator provided between the carburetor and the cylinder block, having an intake passage communicating the intake port and the carburetor, and having magnetic flux generation means for generating magnetic flux by energization;
An intake control valve having a magnetic body, provided in the intake passage, and driven to close the intake passage by an electromagnetic force acting on the magnetic body when energizing the magnetic flux generating means.
It is characterized by that.

Further, the magnetic flux generating means is a coil wound in an annular shape around the outside of the intake passage,
The intake control valve may be a butterfly valve inside the coil, supported rotatably on the intake passage via a rotation shaft, and capable of controlling a rotation angle by energizing the coil. Good.

Further, the magnetic flux generation means is composed of a coil provided outside the intake passage and an iron core provided inside the coil,
The intake control valve opens to the cylinder bore side when the pressure difference between the carburetor side and the cylinder bore side is equal to or greater than a predetermined value, and closes the intake passage by being sucked into the iron core when the coil is energized. It may be a reed valve held in position.

A rotation signal output means for outputting a signal synchronized with the rotation of the small engine;
Control means for energizing the magnetic flux generation means for a period corresponding to a period during which the intake opening is opened based on the output signal of the rotation signal output means may be further provided.

  Furthermore, it is preferable that the control means energizes the magnetic flux generation means when the rotational speed of the small engine exceeds a predetermined value based on the output of the rotation signal output means.

Further, it further comprises throttle operation state detection means for detecting the operation state of the throttle,
The control means may intermittently energize the magnetic flux generating means when the throttle operation state detecting means detects that the throttle is closed.

  Further, the small engine is preferably a two-cycle engine.

  An engine working machine according to a second aspect of the present invention includes the above-described small engine.

  According to the present invention, the insulator having the magnetic flux generating means for generating the magnetic flux by energization and the magnetic body are provided in the intake passage, and the intake passage is blocked by the electromagnetic force acting on the magnetic body when the magnetic flux generating means is energized. Since the intake control valve that is driven to close is provided, the amount of air-fuel mixture flowing into the crank chamber can be adjusted by a device having a compact and simple structure.

The perspective view of the brush cutter carrying the small engine which concerns on this invention. The rear view side view which showed a part of brush cutter of FIG. 1 in the cross section. The figure corresponding to FIG. 2 which partially showed the small engine in the cross section. The expanded sectional view of the insulator part of FIG. The front view of FIG. The figure corresponding to FIG. 4 which concerns on the modification of an insulator part. The control block diagram of the small engine which concerns on this invention. The timing chart which shows operation | movement of an intake opening and a valve drive device. The other timing chart which shows the operation | movement of an intake opening and a valve drive device. FIG. 6 is still another timing chart showing the operation of the intake opening and the valve driving device. The figure corresponding to FIG. 3 which shows the modification of this invention. The expansion perspective view in the state where the valve of the insulator part of Drawing 11 was closed. The expansion perspective view in the state where the valve of the insulator part of Drawing 11 opened.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. As shown in FIG. 1, a brush cutter 1001 equipped with a small two-cycle engine 1 (small engine, hereinafter referred to as engine) suitable for mounting on a portable engine working machine has a rotary blade 1003 at the tip of an operating rod 1002. The engine 1 is attached to the rear end of the operation rod 1002. The output of the engine 1 is supplied to the rotary blade 1003 through a drive shaft that is inserted into the operation rod 1002. The operator operates the brush cutter 1001 by holding the handle 1004 attached to the operation rod 1002.

  As shown in FIG. 2, the engine 1 housed in the engine cover 2 includes a carburetor 4 that mixes fuel and air supplied from the fuel tank 3 and supplies the mixture to the engine 1, a muffler 5, A magnet rotor 7 fixed to the crankshaft 6, an ignition coil 9 fixed to the cylinder block 8 of the engine 1, and a spark plug 10 connected to the ignition coil 9 are attached. As shown in FIG. 3, on the inner peripheral wall of the cylinder bore 11 formed inside the cylinder block 8, an exhaust opening 13 connected to the exhaust port 12, an intake opening 15 connected to the intake port 14, and a scavenging passage (not shown). Scavenging openings (not shown) connected to A piston 16 is accommodated in the cylinder bore 11 so as to be able to reciprocate in the vertical direction in the figure, and when the piston 16 moves up and down, the exhaust opening 13, the intake opening 15, and the scavenging opening are opened and closed by the side walls of the piston 16, respectively. In FIG. 3, the piston 16 is located at the top dead center, the exhaust opening 13 is in a closed state, and the intake opening 15 is in a fully open state. The piston 16 is connected to a crankshaft 6 rotatably supported by a crankcase (not shown) attached below the cylinder block 8 via a piston pin 17 and a connecting rod 18. A muffler 5 is connected to the cylinder block 8 so as to communicate with the exhaust port 12, and an insulator 19 is connected so that the intake port 12 and the intake passage 20 of the insulator 19 communicate with each other. The vaporizer 4 is connected to the insulator 19.

  As shown in FIGS. 3 to 5, a reed valve (intake control valve) 21 is provided at the end 22 on the intake port 14 side of the insulator 19. The reed valve 21 is a plate-like magnetic body that can be elastically deformed, such as stainless steel or bainitic steel. The reed valve 21 is cantilevered with a screw 24 together with a stopper 23 provided on the intake port 14 side of the reed valve 21 at the end 22 on the intake port 14 side of the insulator 19 so as to completely cover the intake passage 20 of the insulator 19. Supported. When the piston 16 moves up and the pressure difference between the crank chamber and the intake passage 20 exceeds a predetermined value (the crank chamber becomes negative pressure), the reed valve 21 is elastically deformed toward the intake port 14 and opens the intake passage 20. In the undeformed state, the reed valve 21 covers the end of the intake passage 20 on the intake port side and closes the intake passage 20. Further, a coil wound around the iron core 25 and the iron core 25 on the free end side of the reed valve 21, that is, on the opposite side to the screw 24 across the intake passage, outside the intake passage 20 of the insulator 19. An electromagnet 27 composed of (magnetic flux generating means) 26 is provided. When the coil 26 of the electromagnet 27 is energized, a magnetic flux is generated in the iron core 25. The electromagnet 27 attracts the reed valve 21 made of a magnetic material by electromagnetic force, and the reed valve 21 is held in a state where the intake passage is closed. Instead of the electromagnet 27 described above, as shown in FIG. 6, a tubular iron core 125 provided so as to cover a part of the outside of the intake passage 20 of the insulator 19, and the iron core 125 is surrounded on the outside of the insulator 19. Alternatively, an electromagnet 127 composed of an annular coil 126 may be used.

  As shown in FIG. 7, a control device (control means) 28 used in the engine 1 includes a rotational speed detection unit 29 that detects the rotational speed of the engine 1 and the position of the crankshaft 6 of the engine 1 (crank angle or piston position). ) For detecting the position of the throttle lever 31 provided on the handle 1004 and the throttle position detector 32 for detecting the position of the throttle lever 31 provided on the handle 1004 and the engine 1 provided on the handle 1004 are stopped. A stop switch position detector 34 for detecting the position of the stop switch 33 to be operated, a valve drive unit 35 for energizing the coil 26, and a calculator 36. The engine speed detector 29 detects a signal from the ignition coil 9 to detect the engine speed of the engine 1 and outputs a speed signal to the calculator 36. The crank position detection unit 30 is connected to a power supply circuit 37, and the crankshaft 6 is connected to a predetermined coil by using voltage pulses generated when the magnet 39 of the magnet rotor 7 passes through a charging coil 38 that supplies power to the power supply circuit 37. The position, for example, the top dead center position or a position at a predetermined angle before the top dead center is detected, and when the crank shaft 6 passes the predetermined position, a crank position signal indicating the predetermined position of the crank shaft 6 is calculated. Output to. The crank position signal may be configured to detect the position of the crankshaft 6 using a voltage pulse generated in the ignition coil 9 instead of using the charging coil 38. The throttle position detection unit 32 detects whether the throttle lever 31 is operated and outputs a throttle position signal to the calculation unit 36. The stop switch position detection unit 34 operates the stop switch 33 (engine stop). ) And a stop switch signal is output to the calculation unit 36. The calculation unit 36 receives signals output from the engine speed detection unit 29, the crank position detection unit 30, the throttle position detection unit 32, and the stop switch position detection unit 34, and is input to the valve drive unit 35. A signal for driving the valve, that is, for energizing the coil 26 to operate the electromagnet 27 is output to the valve drive unit 35.

  The control device 28 detects a state in which the throttle position detector 32 is not operated (a state in which the throttle is closed), and an engine speed detector 29 detects that the engine speed is equal to or less than the idling speed. For example, when it is detected that the speed is 3000 rpm or less, the valve drive unit 35 is not driven as shown in FIG. That is, in this state, the valve drive unit 35 does not operate with respect to opening and closing of the intake opening 15 (upper stage in the figure) accompanying the vertical movement of the piston, and the reed valve 21 closes the intake passage 20. It will not be retained. In this state, when the engine 1 speed increases and the engine speed detector 29 detects a first engine speed higher than the idling engine speed, for example, more than 3500 rpm, that is, the throttle position detector 32 When the state in which the lever 31 is not operated (the state in which the throttle is closed) is detected, and the engine speed detection unit 29 detects a speed exceeding the first speed, the control device 28 detects the crank position detection unit. Based on the crank position signal of 30 and the engine speed signal of the engine speed detecting unit 29, the intake passage 15 is opened while the intake opening 15 is open with respect to the number of times the intake opening 15 is opened in accordance with the opening timing of the intake opening 15. The valve drive unit 35 is driven as shown in FIG. 9 so that the number of times 20 is closed becomes a predetermined value of 1/2. Therefore, in this state, the reed valve 21 closes the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 in half of the number of opening and closing of the intake opening 15 due to the vertical movement of the piston. Retained. In addition, by operating the valve drive unit 35 earlier than the opening timing of the intake opening 15, the lead valve 21 is energized while the intake passage 20 is closed (the reed valve 21 is not deformed). The valve 21 is preferably attracted to the electromagnet 27. Further, when the rotation speed of the engine 1 rises and the engine rotation speed detection unit 29 detects a second rotation speed higher than the first rotation speed, for example, a rotation speed exceeding 3600 rpm, that is, the throttle position detection section 32 When the state in which the lever 31 is not operated (state in which the throttle is closed) is detected, and the engine speed detection unit 29 detects a speed exceeding the second speed, the control device 28 detects the crank position. On the basis of the crank position signal of the part 30 and the engine speed signal of the engine speed detection part 29, the intake air while the intake opening is open with respect to the number of times the intake opening is opened is synchronized with the opening timing of the intake opening 15. The valve drive unit 35 is shown in FIG. 10 so that the number of times of closing the passage becomes another predetermined value of 3/4 (the predetermined value is changed from 1/2 to 3/4). To drive to. Therefore, in this state, the reed valve 21 closes the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 at 3/4 of the number of opening and closing of the intake opening 15 due to the vertical movement of the piston. Retained. Even in this case, the valve drive unit 35 is operated earlier than the opening timing of the intake opening 15 so that the reed valve 21 closes the intake passage 20 (the reed valve 21 is not deformed). The reed valve 21 is preferably attracted to the electromagnet 27 by energizing the electromagnet.

  In addition, when the control device 28 detects that the throttle position detector 32 is operating the throttle lever 31, and detects that the engine speed detector 29 is equal to or lower than the third speed, for example, 8000 rpm or lower. As shown in FIG. 8, the valve drive unit 35 is not driven. That is, in this state, the valve drive unit 35 does not operate with respect to opening and closing of the intake opening 15 (upper stage in the figure) accompanying the vertical movement of the piston, and the reed valve 21 closes the intake passage 20. It will not be retained. From this state, when the engine speed increases and the engine speed detector 29 detects a fourth engine speed higher than the third engine speed, for example, a speed exceeding 9000 rpm, that is, an engine engine speed detector. When 29 detects a rotational speed exceeding the fourth rotational speed, the control device 28 determines the intake opening 15 based on the crank position signal of the crank position detector 30 and the engine speed signal of the engine speed detector 29. FIG. 9 shows the valve drive unit 35 so that the number of times the intake passage 20 is closed while the intake opening 15 is open becomes a predetermined value of 1/2 with respect to the number of times the intake opening 15 is opened in accordance with the opening timing. To drive. Therefore, in this state, the reed valve 21 closes the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 in half of the number of opening and closing of the intake opening 15 due to the vertical movement of the piston. Retained. In addition, by operating the valve drive unit 35 earlier than the opening timing of the intake opening 15, the lead valve 21 is energized while the intake passage 20 is closed (the reed valve 21 is not deformed). The valve 21 is preferably attracted to the electromagnet 27. Further, when the rotational speed of the engine 1 increases and the engine rotational speed detection unit 29 detects a fifth rotational speed higher than the fourth rotational speed, for example, a rotational speed exceeding 9100 rpm, that is, the engine rotational speed detection unit 29 When detecting the rotational speed exceeding the second rotational speed, the control device 28 opens the intake opening 15 based on the crank position signal of the crank position detecting section 30 and the engine rotational speed signal of the engine rotational speed detecting section 29. In accordance with the timing, the number of times the intake passage is closed while the intake opening is open is another predetermined value of 3/4 (the predetermined value is reduced from 1/2 to 3/4). The valve drive unit 35 is driven as shown in FIG. Therefore, in this state, the reed valve 21 closes the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 at 3/4 of the number of opening and closing of the intake opening 15 due to the vertical movement of the piston. Retained. Even in this case, the valve drive unit 35 is operated earlier than the opening timing of the intake opening 15 so that the reed valve 21 closes the intake passage 20 (the reed valve 21 is not deformed). The reed valve 21 is preferably attracted to the electromagnet 27 by energizing the electromagnet.

  Further, the control device 28 detects that the stop switch position detection unit 34 detects the operating state of the stop switch 33 (a state in which the engine 1 is stopped), and the engine speed detection unit 29 detects the state where the engine 1 is rotating. The valve drive unit 35 is set so that the intake passage 20 is always closed while the intake opening 15 is open in accordance with the opening timing of the intake opening 15 in all the opening and closing times of the intake opening 15 due to the vertical movement of the piston. To drive. When the stop switch position detection unit 34 simply detects the operation of the stop switch 33 without detecting the rotation of the engine 1, while the intake opening 15 is open, the intake opening 15 is opened. For example, the valve drive unit 35 may be driven for a predetermined time so that the intake passage 20 is always closed.

  According to the engine 1 configured as described above, when the rotational speed of the engine 1 increases during idling, for example, when it exceeds 3500 rpm, the control device 28 first reduces the number of opening / closing of the intake opening 15 to 1 /. 2, the reed valve 21 keeps the intake passage 20 closed while the intake opening 15 is open by the operation of the valve drive unit 35. As a result, the supply of the air-fuel mixture to the crank chamber can be limited to suppress an increase in the rotational speed of the engine 1, and control can be performed to maintain the idling rotational speed of 3000 rpm. When the rotational speed of the engine 1 exceeds 3500 rpm, the reed valve 21 opens the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 at 3/4 of the number of opening / closing of the intake opening 15. Keep it closed. As a result, the supply of the air-fuel mixture to the crank chamber is further limited to further suppress the increase in the rotational speed of the engine 1, and it is possible to more effectively control the engine so as to maintain the idling rotational speed of 3000 rpm. Therefore, the idling state of the engine 1 can be reliably maintained, and immediately after starting, the idling speed is excessively increased and the centrifugal clutch is connected due to the operation of the starting assist mechanism such as idle up. Can also be suppressed. Further, when the engine 1 increases in idling speed, the control device 28 restricts the supply of the air-fuel mixture to the crank chamber in a stepwise manner, that is, in accordance with the engine speed. In addition, the driving state of the engine 1 does not change abruptly, and the operability can be improved by suppressing the operator from feeling uncomfortable. Further, since the supply of the air-fuel mixture is suppressed when the idling speed is increased, it is possible to suppress the discharge of unburned gas, to realize low exhaust gas characteristics, and to reduce fuel consumption.

  In addition, when the rotational speed of the engine 1 increases excessively during operation, for example, when it exceeds 9000 rpm, the control device 28 first sets the valve drive unit 35 at ½ of the number of opening / closing of the intake opening 15. As a result, the reed valve 21 keeps the intake passage 20 closed in the intake opening 15. As a result, the supply of the air-fuel mixture to the crank chamber can be restricted to prevent an excessive increase in the rotational speed of the engine 1, and the rotational speed of the engine 1 can be controlled to be 9000 rpm or less. When the rotational speed of the engine 1 exceeds 9500 rpm, the reed valve 21 opens the intake passage 20 in the opening of the intake opening 15 by the operation of the valve drive unit 35 at 3/4 of the number of opening and closing of the intake opening 15. Keep it closed. As a result, the supply of the air-fuel mixture to the crank chamber is further restricted to suppress an excessive increase in the rotational speed of the engine 1 and to more effectively control to maintain the idling rotational speed of 9000 rpm. Therefore, it is possible to reliably suppress over-rotation of the engine 1. Further, when the rotational speed of the engine 1 increases excessively, the control device 28 restricts the supply of the air-fuel mixture to the crank chamber in a stepwise manner, that is, so as to increase according to the rotational speed. The driving state of the engine 1 does not change abruptly, and the operability can be improved by suppressing the operator from feeling uncomfortable. Further, the reed valve 21 is not always kept in a state of closing the intake passage 20 during the opening of the intake opening 15, and the reed valve 21 is opened and cranked at least 1/4 of the number of opening and closing of the intake opening 15. An air-fuel mixture is supplied into the room. Accordingly, it is possible to supply the air-fuel mixture containing the lubricating oil to the inside of the crank chamber to lubricate the inside of the crank chamber, and to suppress the seizure of the engine 1 and the like. Further, since the supply of the air-fuel mixture is suppressed during engine rotation, it is possible to suppress the discharge of unburned gas, to realize low exhaust gas characteristics, and to reduce fuel consumption.

  Further, in the case where the engine is rotating despite the stop switch 33 being operated, the opening and closing times of the intake opening 15 associated with the vertical movement of the piston are matched with the opening timing of the intake opening 15. The intake passage 20 is always closed by the reed valve 21 while the intake opening 15 is open. Therefore, it is possible to stop the supply of excess air-fuel mixture to the engine 1 to suppress the emission of harmful exhaust gas components and to reduce fuel consumption, effectively preventing run-on and after-fire. It becomes possible.

  The intake passage 20 is controlled to open and close by a reed valve 21 made of a magnetic material at an end portion 22 on the intake port 14 side of the insulator 19 and an electromagnet 27 that attracts the reed valve 21 to the outside of the intake passage 20 of the insulator 19. be able to. Therefore, it is not necessary to provide a drive mechanism outside the insulator 19, the structure is simple and can be made compact, a large space for installing the device around the insulator 19 and the engine 1 is not required, and the assembly is simple. This can reduce the cost of the product. In addition, when the crank chamber is at a positive pressure, the reed valve 21 is in a state of closing the intake passage 20, and the reed valve 21 is energized so that the reed valve 21 does not open when the reed valve 21 is closed before the intake opening 15 is opened. Therefore, it is not necessary to draw the reed valve 21 away from the electromagnet, and power consumption can be suppressed. Further, since the engine 1 is a two-cycle engine, the opening / closing timing can be controlled with a simple configuration without providing an intake / exhaust valve or the like and the configuration is simple.

  Note that the intake passage 20 may be configured by a butterfly valve (intake control valve) 221 as shown in FIGS. In this case, the insulator 19 is provided with a coil 226 that is wound in an annular shape so as to surround the intake passage 20 on the outside of the intake passage 20, and is rotatably supported by a rotation shaft 241 on the inside of the coil 226. The butterfly valve 221 is provided. The coil 226 is connected to the valve drive unit 35 of the control device 28. The butterfly valve 221 is provided with a magnet 242. In addition, a spring member 243 that holds the butterfly valve 221 in the open position is provided at a connection portion between the rotating shaft 241 and the coil 226. When the coil 226 is energized, the electromagnetic force generated in the magnet 242 by the magnetic flux generated by the coil 226 overcomes the force that holds the butterfly valve 221 in the open position by the spring member 243 and rotates the butterfly valve 221 around the rotation shaft 241. Let Then, as shown in FIG. 12, the butterfly valve 221 is rotated so that the butterfly valve 221 closes the intake passage 20. When the coil 226 is not energized, the butterfly valve 221 is held in the open position by the spring member 243 as shown in FIG. The conditions for the butterfly valve 221 to close the intake passage 20 are the same as those for the reed valve 21 described above.

  As described above, when the butterfly valve 221 is used, as in the case of the reed valve 21, it is not necessary to provide a drive mechanism outside the insulator 19, and the structure can be simplified and made compact. A large space for installing the device around 1 is not required, and it is simple to assemble and can reduce the cost of the product. In the case of the butterfly valve 221, in addition to simply controlling the opening and closing of the intake passage 20, for example, the rotation angle of the butterfly valve 221 when the intake passage 20 is open according to the rotational speed is controlled. In this case, it is possible to more effectively control the rotational speed, for example, maintain idling rotational speed and suppress over-rotation.

  Note that the control of the reed valve 21 or the butterfly valve 221 during idling or over-rotation is not limited to being performed in two stages as in the above-described embodiment, and is increased to, for example, three stages, four stages, or 1 May be reduced in stages. The number of times the intake passage 20 is closed relative to the number of times the intake opening 15 is opened and closed is not limited to the above example, and the number may be increased or decreased. In the present embodiment, the present invention is applied to a two-cycle engine, but may be applied to a four-cycle engine. Further, in the above-described embodiment, the engine 1 is mounted on the brush cutter 1001, but the engine 1 is not limited to mounting on the brush cutter 1001, and is mounted on an engine working machine such as a chain saw, a blower, or a hedge trimmer. May be.

DESCRIPTION OF SYMBOLS 1 Engine 4 Vaporizer 6 Crankshaft 7 Magnet rotor 8 Cylinder block 9 Ignition coil 10 Spark plug 11 Cylinder bore 14 Intake port 15 Intake opening 16 Piston 19 Insulator 20 Intake passage 21 Reed valve 23 Stopper 24 Screw 25 Iron core 26 Coil 27 Electromagnet 28 Control Device 29 Rotational speed detection unit 30 Crank position detection unit 31 Stroll lever 32 Stop switch 33 of engine 1 Stop switch 34 Stop switch position detection unit 35 Valve drive unit 36 Calculation unit 37 Power supply circuit 38 Charging coil

Claims (8)

A vaporizer for supplying a fuel / air mixture;
The piston has an intake opening that opens and closes to a cylinder bore that reciprocates, and supplies the air-fuel mixture supplied from the carburetor to the crank chamber provided in the crankcase through the cylinder bore from the intake opening. A cylinder block in which an intake port is formed;
An insulator provided between the carburetor and the cylinder block, having an intake passage communicating the intake port and the carburetor, and having magnetic flux generation means for generating magnetic flux by energization;
An intake control valve having a magnetic body, provided in the intake passage, and driven to close the intake passage by an electromagnetic force acting on the magnetic body when energizing the magnetic flux generating means.
A small engine characterized by that. The magnetic flux generating means is a coil wound in an annular shape around the outside of the intake passage,
The intake control valve is a butterfly valve that is inside the coil and is rotatably supported by the intake passage via a rotation shaft, and the rotation angle can be controlled by energizing the coil.
The small engine according to claim 1. The magnetic flux generation means includes a coil provided outside the intake passage and an iron core provided inside the coil.
The intake control valve opens to the cylinder bore side when the pressure difference between the carburetor side and the cylinder bore side is equal to or greater than a predetermined value, and closes the intake passage by being sucked by the iron core when the coil is energized. A reed valve held in position,
The small engine according to claim 1. Rotation signal output means for outputting a signal synchronized with the rotation of the small engine;
Control means for energizing the magnetic flux generation means for a period corresponding to a period during which the intake opening is opened based on an output signal of the rotation signal output means.
The small engine according to claim 1, wherein the engine is a small engine. The control means energizes the magnetic flux generation means when the rotational speed of the small engine exceeds a predetermined value based on the output of the rotation signal output means.
The small engine according to claim 4. Throttle operation state detection means for detecting the operation state of the throttle is further provided,
The control means intermittently energizes the magnetic flux generation means when detecting that the throttle is closed by the throttle operation state detection means.
The small engine according to claim 4 or 5, wherein the engine is small. The small engine is a two-cycle engine;
The small engine according to claim 1, wherein the engine is a small engine. The small engine according to any one of claims 1 to 7, comprising:
An engine working machine characterized by that.

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