JP2005076522A - Throttle device for general-purpose engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throttle device for a general-purpose engine with a throttle valve to be opened when stopping the operation of the general-purpose engine for improving the next startability, contributing to simplified construction of a carburetor by preventing dieseling or run-on without providing a fuel cut valve in the carburetor. <P>SOLUTION: A main fuel passage and a slow fuel passage for the carburetor communicate with the upstream side of the throttle valve in an intake passage. When an instruction to stop the general engine is input via an engine stop switch (S10), an electric motor is driven so that the throttle valve is fully closed and the operation of the engine is stopped (S12), and when an engine speed NE is down to a preset speed NEref or lower (S14), the electric motor is driven so that the throttle valve is fully opened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a throttle device for a general-purpose engine, and more particularly to a throttle device for a general-purpose engine in which a throttle valve is opened and closed by an actuator.

  For general-purpose engines (spark-ignition internal combustion engines) used as a drive source in various applications such as generators and agricultural machinery, the throttle valve opening is conventionally adjusted with a mechanical governor consisting of weights and springs. The engine speed was controlled.

  Recently, even in this type of general-purpose engine, it has been proposed to use an electronically controlled throttle device (electronic governor) that opens and closes a throttle valve with an actuator such as a stepping motor to accurately control the engine speed. Has been.

  By the way, the operation of the general-purpose engine is normally stopped by ignition cut. At this time, the throttle opening of the general-purpose engine is kept fully open or half-opened due to the structure of the mechanical governor or for the next improvement in engine startability.

  However, since many general-purpose engines use a carburetor as a fuel supply device, if the throttle valve is opened when the operation is stopped, the fuel supply will not stop immediately, and dieseling and run-on will not be performed. There was a risk of causing it.

For this reason, conventionally, a fuel cut valve (solenoid valve) is arranged in the middle of the fuel passage of the carburetor, and the fuel cut valve is closed simultaneously with the ignition cut (for example, patent) Reference 1).
JP 2003-120422 A

  However, when the fuel cut valve is arranged in the middle of the fuel passage of the carburetor as described above, the configuration of the carburetor becomes complicated, and there is a problem that the carburetor is increased in size and cost.

  Accordingly, an object of the present invention is to eliminate the above-mentioned inconveniences, and when the general-purpose engine is stopped, the throttle valve is opened to improve the next startability, and the diesel engine is not provided with a fuel cut valve in the carburetor. Another object of the present invention is to provide a general-purpose engine throttle device that prevents the occurrence of run-on and thus simplifies the configuration of the carburetor.

  In order to solve the above-described object, in claim 1, the throttle valve disposed in the intake passage of a general-purpose engine, an actuator connected to the throttle valve, and the drive of the actuator are controlled to control the driving. A general-purpose engine throttle device comprising an actuator control means for adjusting an intake air amount by opening and closing a throttle valve, and a stop instruction input means for inputting a stop instruction for the general-purpose engine, and detecting a rotational speed of the general-purpose engine And an carburetor that is in communication with the intake passage and injects fuel, the fuel passage of the carburetor is communicated upstream of the throttle valve of the intake passage, and the actuator control means When a general engine stop instruction is input via the stop instruction input means, The throttle valve is fully opened when the detected engine speed drops below a predetermined speed while driving the actuator to stop the operation of the general-purpose engine so that the throttle valve has a fully closed opening. The actuator is configured to be driven at a degree.

  According to a second aspect of the present invention, the operating power source of the actuator is configured to be a power source generated by the rotation of the general-purpose engine.

  According to a third aspect of the present invention, the predetermined rotational speed is set to a value that does not restore the operation of the general-purpose engine even when the throttle valve is opened.

  According to the first aspect of the present invention, the throttle valve disposed in the intake passage of the general-purpose engine, the actuator connected to the throttle valve, and the throttle valve is opened / closed by controlling the driving of the actuator so that the intake air amount In a throttle device for a general-purpose engine provided with an actuator control means for metering, a stop instruction input means for inputting a stop instruction for the general-purpose engine, an engine speed detection means for detecting the rotational speed of the general-purpose engine, A carburetor that communicates with the intake passage and injects fuel, and communicates the fuel passage of the carburetor upstream of the throttle valve of the intake passage, and the actuator control means is connected via the stop instruction input means. When the general engine stop instruction is input, the throttle valve is fully closed The actuator is driven so that the operation of the general-purpose engine is stopped and the actuator is operated so that the throttle valve is fully opened when the detected engine speed decreases to a predetermined speed or less. Since it is configured to drive, it is possible to improve the next startability by opening the throttle valve when the operation is stopped. In addition, it is possible to prevent the occurrence of dieseling or run-on without providing a fuel cut valve in the carburetor, thereby simplifying the configuration of the carburetor.

  Specifically, the fuel passage of the carburetor is connected to the upstream side of the throttle valve, and the fuel supply is shut off by closing the throttle valve, so a fuel cut valve is provided in the carburetor. Thus, the occurrence of dieseling and run-on can be prevented, and the configuration of the vaporizer can be simplified. Further, since the throttle valve is opened when the engine speed is sufficiently reduced to a predetermined speed or less, the next startability can be improved.

  Further, in the present invention, since the operation power source of the actuator is configured to be the power generated by the rotation of the general-purpose engine, the next start from the valve closing operation for preventing dieseling or the like. The series of operations up to the valve opening operation for improving the performance can be completed while operating power is supplied to the actuator, and therefore even a general-purpose engine without a battery is described in claim 1. The same effect as that obtained can be obtained.

  In the third aspect of the present invention, the predetermined rotational speed is set to a value at which the operation of the general-purpose engine does not recover even when the throttle valve is opened. In addition to the effects, the operation of the general-purpose engine can be stopped reliably.

  The best mode for carrying out the throttle device for a general-purpose engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view generally showing a throttle device for a general-purpose engine according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 10 indicates a general-purpose engine (hereinafter referred to as “engine”). The engine 10 includes a single cylinder (cylinder) 12, and a piston 14 is accommodated therein so as to be capable of reciprocating. A combustion chamber 16 is formed between the head of the piston 14 and the cylinder wall surface, and an intake valve 18 and an exhaust valve 20 are disposed on the cylinder wall surface, and a space between the combustion chamber 16 and the intake passage 22 or the exhaust passage 24 is provided. Open and close. The engine 10 is specifically a water-cooled four-cycle single-cylinder OHV type internal combustion engine, and has a displacement of 196 cc.

  The piston 14 is connected to a crankshaft 28, and the crankshaft 28 is connected to a camshaft 30 through a gear. A flywheel 32 is attached to the crankshaft 28, and a recoil starter 34 for manually starting the engine 10 is attached to the front end side of the flywheel 32. A power generation coil (alternator) 36 is disposed inside the flywheel 32 to generate an alternating current. The alternating current generated by the power generation coil 36 is converted into a direct current through a processing circuit (not shown), and then supplied as an operating power source to an ECU, an electric motor, an ignition circuit (not shown), and the like. The engine 10 is a battery-less general-purpose engine that does not include a battery.

  Further, a carburetor (vaporizer) 40 is disposed upstream of the intake passage 22. The carburetor 40 accommodates a throttle valve 42, which is connected to an electric motor 44 (actuator, specifically, a stepping motor or a DC motor) via a throttle shaft and a reduction gear mechanism, which will be described later. The carburetor 40 is connected to a fuel tank (not shown), and generates an air-fuel mixture by injecting gasoline fuel into the intake air according to the opening of the throttle valve 42. The generated air-fuel mixture is sucked into the combustion chamber 16 of the cylinder 12 through the throttle valve 42, the intake passage 22 and the intake valve 18.

  A throttle opening sensor 46 is disposed in the vicinity of the electric motor 44 and outputs a signal corresponding to the opening θTH of the throttle valve 42 (hereinafter referred to as “throttle opening”). A crank angle sensor 48 made of an electromagnetic pickup is disposed near the flywheel 32 and outputs a pulse signal at every predetermined crank angle.

  An ECU (electronic control unit) 50 is disposed in the vicinity of the engine 10. The ECU 50 is formed of a microcomputer and includes a CPU, ROM, RAM, a counter, and the like (not shown). An engine stop switch 52 is disposed at an appropriate position of the engine 10. The engine stop switch 52 outputs an ON signal when an engine stop instruction is input from the operator (when operated).

  The outputs of the throttle opening sensor 46, the crank angle sensor 48, and the engine stop switch 52 are input to the ECU 50. The ECU 50 counts the output pulses of the crank angle sensor 48 and detects (calculates) the engine speed NE.

  The ECU 50 calculates the energization command value of the electric motor 44 based on the detected engine speed NE and the throttle opening θTH so that the engine speed NE matches the target speed NED and the calculated energization command value. Output to the electric motor 44 to control the driving of the electric motor 44. In addition, when an engine stop instruction is input via the engine stop switch 52, the ECU 50 drives the electric motor 44 to adjust the throttle opening θTH, and performs ignition cut to stop the operation of the engine 10.

  Thus, in this embodiment, the throttle valve 42 disposed in the intake passage 22 of the engine 10, the electric motor 44 connected to the throttle valve 42, and the drive of the electric motor 44 are controlled. Thus, the engine speed NE is controlled by an electronically controlled throttle device (electronic governor) having an ECU 50 that opens and closes the throttle valve 42 to adjust the intake air amount.

  FIG. 2 is a plan view of the carburetor 40. 3 is a cross-sectional view taken along line III-III in FIG.

  As shown in FIG. 3, the carburetor 40 is provided with a throttle valve 42. The throttle valve 42 is supported by a throttle shaft 54. The throttle shaft 54 is connected to the output shaft 44 </ b> S of the electric motor 44 via the reduction gear mechanism 58. The electric motor 44, the reduction gear mechanism 58, and a part of the throttle shaft 54 are accommodated in a unit case 60 that is integrally attached to the throttle body 40.

  4 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIG. 4, in the carburetor 40, a main fuel passage 64 and a slow fuel passage 66 communicate with the intake passage 22 upstream of the throttle valve 42. The main fuel passage 64 and the slow fuel passage 66 are connected to a fuel tank via a float chamber (not shown). A venturi 68 is formed in the vicinity of the main fuel passage 64, and a choke valve 70 is disposed upstream of the venturi 68.

  Here, the fuel injection operation of the carburetor 40 will be briefly described. When the throttle valve 42 is at a high opening, the fuel is injected from the main fuel passage 64 by the negative pressure of the intake air passing through the venturi 68, and the air-fuel mixture. Is generated. On the other hand, when the throttle valve 42 has a low opening, fuel is injected from the slow fuel passage 66 mainly by the negative pressure generated by the lowering of the piston 14 (not shown in FIG. 4). Further, at the time of cold start, the air-fuel ratio is enriched by closing the choke valve 70 and reducing the intake air amount.

  Note that many general-purpose engines are used at a constant speed (for example, about 2500 rpm) in the high-speed region, so that low-speed rotation (for example, 1000 rpm or less) near idle rotation is not required. Therefore, in this embodiment, in order to simplify the configuration of the carburetor 40, an idle port (a fuel passage communicating downstream from the throttle valve 42) is not intentionally provided. Therefore, in the engine 10 according to this embodiment, when the throttle valve 42 is fully closed, the supply of fuel is cut off and the operation is stopped.

  Next, the operation of the throttle device for a general-purpose engine according to this embodiment, more specifically, the throttle opening control when the engine 10 is stopped will be described with reference to FIG. FIG. 5 is a flowchart showing the operation. The illustrated program is executed every predetermined cycle (for example, 100 msec).

  In the following, first, in S10, it is determined whether or not the engine stop switch 52 is outputting an ON signal, that is, whether or not the operator has instructed to stop the engine 10. When the result in S10 is negative, the subsequent processing is skipped, while when the result in S10 is positive, the process proceeds to S12, and the electric motor 44 is driven so that the throttle valve 42 is fully closed, and the ignition cut is performed. The operation of the engine 10 is stopped.

  Here, since the carburetor 40 does not include a fuel passage disposed on the downstream side of the throttle valve 42, the fuel supply is shut off by fully closing the throttle valve 42 as described above. Accordingly, by driving the electric motor 44 so that the throttle valve 42 is fully closed in S12, it is possible to prevent the occurrence of dieseling or run-on after the ignition cut.

  Next, in S14, it is determined whether or not the engine speed NE has decreased below a predetermined speed NEref. The predetermined rotation speed NEref is set to a value (for example, 800 rpm) that does not restore the operation of the engine 10 even if the throttle valve 42 is opened after the engine rotation speed NE has decreased to a lower rotation speed.

  When the result in S14 is negative, the subsequent processing is skipped, while when the result in S14 is positive, the process proceeds to S16, and the electric motor 44 is driven so that the throttle valve 42 is fully opened. Here, the throttle valve 42 is opened in order to improve the next startability of the engine 10.

  The engine 10 does not include a battery, and the electric motor 44 uses electric power generated by the rotation of the engine 10 (rotation of the flywheel 32) as an operating power supply. Therefore, if the engine 10 is completely stopped, the throttle The valve 42 cannot be opened. Therefore, as described above, the throttle valve 42 is opened when the engine speed NE has decreased to the predetermined speed NEref or less, that is, before the engine 10 is completely stopped (before power generation is completed). did. As a result, even a general-purpose engine without a battery can reliably perform a series of operations from a valve closing operation for preventing dieseling or the like to a valve opening operation for improving the next startability. . Since the engine speed NE has decreased to the predetermined speed NEref or less, even if the throttle valve 42 is opened, the operation of the engine 10 is not recovered and stops.

  Thus, in the throttle device for a general-purpose engine according to this embodiment, the main fuel passage 64 and the slow fuel passage 66 of the carburetor 40 are communicated with the upstream side of the throttle valve 42 of the intake passage 22 and the engine is stopped. When an instruction to stop the engine 10 is input via the switch 52, the electric motor 44 is driven to stop the operation of the engine 10 so that the throttle valve 42 is fully closed, and the engine speed NE is predetermined. Since the electric motor 44 is driven so that the throttle valve 42 is fully opened when the rotational speed falls below the NEref, the carburetor 40 does not have a fuel cut valve, which is conventionally required. The occurrence of run-on can be prevented, and thus the configuration of the carburetor 40 can be simplified. . Further, since the throttle valve 42 is opened when the engine speed NE is sufficiently lowered to the predetermined speed NEref or less, the next startability can be improved.

  In addition, since the operation power source of the electric motor 44 is a power source generated by the rotation of the engine 10, the valve opening operation for improving the next startability from the valve closing operation for preventing dieseling and the like. The series of operations up to can be completed while the operation power is supplied to the electric motor 44 (that is, while the power generation is continued). Therefore, even if it is a general purpose engine which is not provided with a battery like the engine 10 of this Example, the above-mentioned effect can be acquired.

  Further, since the predetermined rotation speed NEref is set to a value that does not restore the operation of the engine 10 even when the throttle valve 42 is opened, the operation of the engine 10 can be stopped reliably.

  As described above, in the first embodiment of the present invention, the throttle valve (42) disposed in the intake passage (22) of the general-purpose engine (10), and the actuator connected to the throttle valve (42) ( General-purpose engine throttle device comprising an electric motor 44) and actuator control means (ECU 50) for controlling the drive of the actuator (44) to open and close the throttle valve (42) to regulate the amount of intake air And a stop instruction input means (engine stop switch 52) for inputting a stop instruction for the general purpose engine (10), and an engine speed detection means (crank angle sensor) for detecting the rotational speed (NE) of the general purpose engine (10). 48) and a carburetor (carburetor 40) communicating with the intake passage (22) and injecting fuel, The fuel passage (main fuel passage 64, slow fuel passage 66) of the generator (40) communicates with the upstream side of the throttle valve (42) of the intake passage (22), and the actuator control means (50) When an instruction to stop the general-purpose engine (10) is input via the stop instruction input means (52) (S10 in the flowchart of FIG. 5), the actuator ( 44) is driven to stop the operation of the general-purpose engine (10) (S12 in the flowchart of FIG. 5), and when the detected engine speed (NE) falls below a predetermined speed (NEref) (FIG. 5 in step S14), the actuator (44) is driven so that the throttle valve (42) is fully open (FIG. 5 flow). S16 in chart) was constructed as.

  Further, the operation power supply of the actuator (44) is configured to be a power supply generated by the rotation of the general-purpose engine (10).

  Further, the predetermined rotational speed (NEref) is set to a value that does not restore the operation of the general-purpose engine (10) even when the throttle valve (42) is opened.

  In the above description, the electric motor 44 is exemplified as the actuator for opening and closing the throttle valve 42. However, other actuators such as a rotary solenoid may be used.

FIG. 1 is a schematic view generally showing a throttle device for a general-purpose engine according to a first embodiment of the present invention. It is a top view of the carburetor shown in FIG. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. 1 is a flowchart showing the operation of the apparatus.

Explanation of symbols

10 General-purpose engine 22 Air intake path 40 Carburetor (vaporizer)
42 Throttle valve 44 Electric motor (actuator)
48 Crank angle sensor (engine speed detection means)
50 ECU (actuator control means)
52 Engine stop switch (stop instruction input means)
64 Main fuel passage (fuel passage)
66 Slow fuel passage (fuel passage)

Claims (3)

  A throttle valve disposed in an intake passage of a general-purpose engine; an actuator connected to the throttle valve; and an actuator control means for adjusting the intake air amount by opening and closing the throttle valve by controlling the driving of the actuator. A stop instruction input means for inputting a stop instruction for the general-purpose engine, an engine speed detection means for detecting the rotational speed of the general-purpose engine, and fuel that is communicated with the intake passage. A carburetor for injecting, communicating a fuel passage of the carburetor to an upstream side of a throttle valve of the intake passage, and the actuator control means is configured to issue a stop instruction for the general-purpose engine via the stop instruction input means. When input, the throttle valve is opened so that the throttle valve is fully closed. Driving the actuator to stop the operation of the general-purpose engine, and driving the actuator so that the throttle valve is fully opened when the detected engine speed decreases to a predetermined speed or less. A throttle device for a general-purpose engine characterized by comprising.   2. The throttle device for a general-purpose engine according to claim 1, wherein an operating power source of the actuator is a power source generated by rotation of the general-purpose engine. 3. The throttle device for a general-purpose engine according to claim 1, wherein the predetermined rotational speed is set to a value that does not restore the operation of the general-purpose engine even when the throttle valve is opened.

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