JP2005016438A - Throttle device for general-purpose engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throttle device for a general-purpose engine capable of opening and closing a throttle valve by an electric motor and facilitating engine start at the next time even when the throttle valve is held in the vicinity of fully closed opening when the engine is stopped. <P>SOLUTION: A unit case 60 storing a throttle shaft 54 and the electric motor 42 is provided in a throttle body 40. One end of the throttle shaft 54 protrudes from the unit case 60, and a manually operated operation lever 80 capable of being manually and freely operated is attached to a protruding section 541. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
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 electric motor.
[0002]
[Prior art]
In general-purpose engines (spark-ignition internal combustion engines) used as drive sources in various applications such as generators and agricultural machinery, the throttle valve opening is usually adjusted with a mechanical governor consisting of weights and springs. The engine speed is controlled.
[0003]
Recently, even in this type of general-purpose engine, an electronically controlled throttle device (electronic governor) that opens and closes a throttle valve with an electric motor such as a stepping motor can be used to accurately control the engine speed. Proposed. As a throttle device that opens and closes the throttle valve with an electric motor, for example, a technique described in Patent Document 1 can be cited.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-263098
[Problems to be solved by the invention]
By the way, when fuel is supplied to the general-purpose engine with a carburetor, the throttle opening at the start of the engine is required to be fully open or in the vicinity thereof. For this reason, when a carburetor is combined with the throttle device described in Patent Document 1 described above, the electric motor is usually driven so that the throttle valve returns to the fully open position after the engine is stopped. If the throttle valve is held in the vicinity of the fully closed position due to the above, there is a problem that the next engine start is difficult.
[0006]
Accordingly, an object of the present invention is to eliminate the above-mentioned inconveniences, and even when the throttle valve is opened and closed by an electric motor and the throttle valve is held near the fully closed position when the engine is stopped, the next time It is an object to provide a throttle device for a general-purpose engine that can easily start the engine.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to claim 1, a throttle valve accommodated in a throttle body disposed in an intake passage of a general-purpose engine, a throttle shaft that supports the throttle valve, and the throttle shaft A general-purpose engine that opens and closes the throttle valve by rotating the throttle shaft by driving the electric motor and adjusting the amount of air sucked through the intake passage. In the throttle device, the throttle body is provided with a unit case for accommodating the throttle shaft and the electric motor, and one end of the throttle shaft is protruded from the unit case, and a manually operated lever that can be manually operated is provided on the protruded portion. Configured to attach.
[0008]
Thus, according to the first aspect of the present invention, the throttle body is provided with the unit case that houses the throttle shaft and the electric motor that rotates the throttle shaft, and one end of the throttle shaft is protruded from the unit case. Since the manual operation lever that can be manually operated is attached to the selected part, even if the throttle valve is held near the fully closed position when the engine is stopped, the manual operation lever can be operated. Since the throttle valve can be opened, the next engine start can be easily performed.
[0009]
According to a second aspect of the present invention, there is provided an idle rotation speed adjustment mechanism that can be manually operated to adjust the idle rotation speed of the general-purpose engine by adjusting the position of the manual operation lever.
[0010]
Thus, according to the second aspect of the present invention, since the idle speed adjusting mechanism that can be manually operated is provided to adjust the idle speed of the general-purpose engine by adjusting the position of the manual operation lever. With this lever, it is possible to open the throttle valve and adjust the idling speed when starting the engine, and the configuration can be made compact.
[0011]
According to a third aspect of the present invention, there is provided a manually operated push rod that pushes the manual operation lever to open the throttle valve.
[0012]
Thus, according to the third aspect of the present invention, since the push rod that can be manually operated to open the throttle valve by pushing the manual operation lever is provided, the operability when the throttle valve is opened is provided. Therefore, the next engine start can be performed more easily.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A general-purpose engine throttle device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.
[0014]
FIG. 1 is a schematic view generally showing a throttle device for a general-purpose engine according to this embodiment.
[0015]
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.
[0016]
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, a motor driver (not shown), an ignition circuit (not shown) or the like.
[0017]
A throttle body 40 is disposed upstream of the intake passage 22. Although not shown in FIG. 1, a throttle valve is accommodated in the throttle body 40, and the throttle valve is connected to an electric motor 42 (stepping motor) via a throttle shaft and a power transmission mechanism which will be described later. In the throttle body 40, a carburetor assembly is provided on the upstream side of the throttle valve. The carburetor assembly is connected to a fuel tank and generates a fuel-air mixture by injecting gasoline fuel into the intake air in accordance with the opening of the throttle valve. The generated air-fuel mixture is sucked into the combustion chamber 16 of the cylinder 12 through the throttle valve, the intake passage 22 and the intake valve 18.
[0018]
A throttle opening sensor 46 is disposed in the vicinity of the electric motor 42 and outputs a signal corresponding to the throttle valve opening θTH (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.
[0019]
An ECU (electronic control unit) 50 is disposed in the vicinity of the engine 10. The ECU 50 includes a microcomputer and includes a CPU, a ROM, a RAM, and a counter.
[0020]
The outputs of the throttle opening sensor 46 and the crank angle sensor 48 described above 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.
[0021]
The ECU 50 calculates the energization command value of the electric motor 42 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 It outputs to the electric motor 42 and controls the drive of the electric motor 42.
[0022]
As described above, in this embodiment, the throttle valve is opened and closed by the electronically controlled throttle device (electronic governor) including the throttle body 40, the ECU 50, and various sensors, and the engine speed NE is controlled. .
[0023]
Further, the throttle device for a general-purpose engine according to this embodiment will be described in detail with reference to FIG. FIG. 2 is a plan view showing the throttle body 40 of the throttle device. 3 is a cross-sectional view taken along line III-III in FIG.
[0024]
As shown in FIG. 3, a throttle valve 52 is disposed in the middle of the intake passage of the throttle body 40. The throttle valve 52 is supported by a throttle shaft 54. Further, the above-described carburetor assembly 56 is attached upstream of the throttle valve 52 in the intake passage of the throttle body 40.
[0025]
Further, as shown in FIGS. 2 and 3, the throttle body 40 includes an electric motor 42, a power transmission mechanism 58 (reduction gear mechanism) composed of four gears described later, and a part of the throttle shaft 54. A unit case 60 for housing is integrally provided. The electric motor 42 is fastened and fixed to the unit case 60 with two screws 64, and its output shaft 42 o is connected to the throttle shaft 54 via a power transmission mechanism 58.
[0026]
Specifically, a first gear 66 is attached to one end 42o1 of the output shaft of the electric motor, and the first gear 66 includes a second gear 68 that is rotatably supported inside the unit case 60. Meshed. A third gear 70 is attached coaxially with the second gear 68, and the third gear 70 is engaged with a fourth gear 72 attached to the throttle shaft 54. Thereby, the output of the electric motor 42 is transmitted to the throttle shaft 54 while being decelerated according to the gear ratio of each gear, and the throttle valve 52 is opened and closed.
[0027]
The third gear 70 and the fourth gear 72 are eccentric gears as well shown in FIG. More specifically, in the third gear 70 and the fourth gear 72, the rotation angle of the fourth gear 72 with respect to the rotation angle of the third gear 70 becomes smaller (reduction ratio) as the throttle opening θTH becomes smaller. Is set to be larger). This is because the pressure difference between the upstream side and the downstream side of the throttle valve 52 decreases as the throttle opening θTH increases, and eventually saturates (that is, the amount of change in the amount of intake air passing through the throttle valve 52 is the throttle opening degree). Therefore, when the throttle opening θTH is small, precise opening adjustment is performed, and when the throttle opening θTH is large, quick opening / closing is performed. The opening degree can be adjusted at speed, and the target engine speed can be accurately followed and responsive.
[0028]
Incidentally, if the positional relationship between the output shaft 42o of the electric motor 42 and the throttle shaft 54 varies, there is a risk that friction will occur in the power transmission mechanism 58 that connects them. Accordingly, it is necessary to accurately position the output shaft 42o with respect to the unit case 60.
[0029]
Therefore, in this embodiment, both ends of the output shaft 42o of the electric motor protrude from the housing 42h of the electric motor, and one end 42o1 is connected to the throttle shaft 54 via the power transmission mechanism 58 as described above. The other end 42o2 is inserted into a concave boss 76 (shown in FIG. 3) formed in the unit case 60, which is an attachment portion of the electric motor 42. That is, the other end 42o2 of the output shaft is inserted into a boss 76 formed on the unit case 60, whereby the electric motor 42 is positioned with respect to the unit case 60.
[0030]
Thereby, for example, even when a deviation (molding error) occurs between the positions of the center of gravity of the output shaft 42o and the housing 42h, the positioning of the electric motor 42 is performed by the output shaft 42o instead of the housing 42h. Can be accurately placed at a desired position. Therefore, there is no variation in the positional relationship between the output shaft 42o and the throttle shaft 54, and therefore it is possible to prevent the generation of friction in the power transmission mechanism 58 that connects them.
[0031]
Further, since it is possible to prevent the power transmission mechanism 58 from generating friction, the driving speed of the electric motor 42 can be improved and the loss of transmission torque can be reduced. Can be made smaller. In addition, since the output shaft of the electric motor is generally smaller in diameter than the protruding portion for positioning that has been formed in the prior art as well as the housing, the diameter of the boss 76 can be set small, and processing is easy. Become.
[0032]
The “housing 42h” means a case-like member that accommodates the rotor or stator (not shown) of the electric motor 42 and defines the outer shape of the motor.
[0033]
2 and FIG. 3, one end of the throttle shaft 54 passes through the inside of the unit case 60 and protrudes outward from the unit case 60. A manual operation lever 80 that can be manually operated is attached to a portion (indicated by reference numeral 541 in the figure) of the throttle shaft 54 that protrudes outward from the unit case 60.
[0034]
In the vicinity of the manual operation lever 80 on the outer periphery of the unit case 60, an idle rotation speed adjustment mechanism 82 that can be manually operated for adjusting the idle rotation speed of the engine 10 is provided. The idle rotation speed adjustment mechanism 82 includes a female screw portion 84 projecting from the outer peripheral surface of the unit case 60 and having a female screw threaded at the center thereof, and a bolt 86 screwed into the female screw.
[0035]
As shown in FIG. 3, a throttle return spring 90 (torsion coil spring) is disposed on the outer periphery of the throttle shaft 54 inside the unit case 60. One end of the throttle return spring 90 is connected to a fourth gear 72 attached to the throttle shaft 54, and the other end is connected to a hook pin 92 protruding inside the unit case 60. The winding direction of the throttle return spring 90 is set so that the throttle shaft 54 is rotated in the direction in which the throttle valve 52 is closed.
[0036]
The throttle shaft 54 urged in the direction to close the throttle valve 52 by the throttle return spring 90 is held in its rotating position (corner) by the manual operation lever 80 coming into contact with the tip of the bolt 86 described above. . The opening degree of the throttle valve 52 at this time becomes the throttle opening degree when the engine 10 is idling. Therefore, by rotating the bolt 86 and changing its tip position, the throttle opening during idling can be changed and the idling speed of the engine 10 can be adjusted.
[0037]
Here, as described above, since the fuel is supplied to the engine 10 by the carburetor assembly 56, it is necessary that the throttle opening at the time of starting the engine be fully open or close to it. Accordingly, the ECU 50 is set to drive the electric motor 42 so that the throttle valve 52 returns to the fully open position after the engine 10 is stopped, but the throttle valve 52 is fully closed due to an operation error or the like when the engine is stopped. If it is held near the opening, there is a problem that the next engine start is difficult.
[0038]
However, in this embodiment, one end of the throttle shaft 54 is protruded from the unit case 60, and the manually operated lever 80 that can be manually operated is attached to the protruded portion. Even if 52 is held near the fully closed opening, the throttle valve 52 can be opened by operating (turning) the manual operation lever 80 as shown in FIG. It is possible to easily start the engine.
[0039]
Further, since the idle speed adjusting mechanism 82 for adjusting the idle speed of the engine 10 is adjusted by adjusting the position (rotation position) of the manual operation lever 80, the throttle at the time of starting the engine with one lever is provided. The valve can be opened and the idling speed can be adjusted, and the configuration can be made compact.
[0040]
Next, a throttle device for a general-purpose engine according to a second embodiment of the present invention will be described.
[0041]
FIG. 5 is a plan view showing a throttle body in the throttle device for a general-purpose engine according to the second embodiment.
[0042]
The following description focuses on the differences from the previous embodiment. In this embodiment, a manually operated push rod that pushes the manual operation lever 80 to open the throttle valve 52. 94 is provided.
[0043]
The push rod 94 is held so as to be linearly movable by a holding portion 96 protruding from the outer peripheral surface of the unit case 60. The holding portion 96 and the vicinity of the tip of the push rod 94 are connected by a push rod return spring 98 (a tension coil spring).
[0044]
Due to the urging force of the push rod return spring 98, the push rod 94 is arranged so that the tip is located near the rotational position of the manual operation lever 80 during idle operation when not operated.
[0045]
When the operator pushes the push rod 94 against the urging force of the push rod return spring 98, the manual operation lever 80 is pushed by the push rod 94 and the throttle shaft 54 is rotated. Therefore, even if the throttle valve 52 is held near the fully closed position when the engine is stopped, the throttle valve 52 is opened by operating (pushing) the push rod 94 as shown in FIG. can do. Further, by providing the push rod 94, the operation point can be brought closer to the operator as compared with the previous embodiment, and the operation is also a linear motion, so that the operability when opening the throttle valve 52 is improved. Therefore, the next engine start can be performed more easily.
[0046]
The remaining configuration is the same as that of the previous embodiment, and a description thereof will be omitted.
[0047]
As described above, in the first and second embodiments of the present invention, the throttle valve (52) accommodated in the throttle body (40) disposed in the intake passage (22) of the general-purpose engine (10). ), A throttle shaft (54) for supporting the throttle valve (52), and an electric motor (42) for rotating the throttle shaft (54), and driving the electric motor (42) to In a throttle device for a general-purpose engine that opens and closes the throttle valve (52) by rotating a shaft (54) and adjusts the amount of air sucked through the intake passage (22), the throttle body (40) And a unit case (60) for accommodating the throttle shaft (54) and the electric motor (42). One end of Rushafuto (54) projecting from said unit case (60) and configured to mount the manual operation freely manually operated lever (80) to the site (541) which is protruded.
[0048]
Further, an idle speed adjusting mechanism (82) that can be manually operated is provided for adjusting the idle speed of the general-purpose engine (10) by adjusting the position of the manual operation lever (80).
[0049]
Further, a push rod (94) that can be manually operated is provided to push the manual operation lever (80) to open the throttle valve (52).
[0050]
In the above description, the electric motor 42 is a stepping motor, but it may be a DC motor or the like. A rotary solenoid or the like may be used.
[0051]
【The invention's effect】
According to the first aspect of the present invention, the throttle body is provided with a unit case that houses the throttle shaft and the electric motor that rotates the throttle shaft, and one end of the throttle shaft is protruded from the unit case, and the protruding portion is Since the manual operation lever that can be operated manually is attached, even if the throttle valve is held near the fully closed position when the engine is stopped, the throttle valve is opened by operating the manual operation lever. Therefore, the next engine start can be easily performed.
[0052]
According to the second aspect of the present invention, there is provided a manually operated idle rotation speed adjustment mechanism for adjusting the idle rotation speed of the general-purpose engine by adjusting the position of the manual operation lever. Thus, it is possible to open the throttle valve and adjust the idling speed at the time of starting the engine, and the configuration can be made compact.
[0053]
According to the third aspect of the present invention, a push rod that can be manually operated to open the throttle valve by pushing the manual operation lever is provided, so that the operability when the throttle valve is opened is improved. Therefore, the next engine start can be performed more easily [Brief description of the drawings]
FIG. 1 is a schematic view generally showing a throttle device for a general-purpose engine according to an embodiment of the present invention.
FIG. 2 is a plan view showing a throttle body in the apparatus shown in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a plan view of the throttle body shown in FIG. 2. FIG.
FIG. 5 is a plan view showing a throttle body in a throttle device for a general-purpose engine according to a second embodiment of the present invention.
6 is a plan view of the throttle body shown in FIG. 5. FIG.
[Explanation of symbols]
10 engine (general purpose engine)
22 Intake passage 40 Throttle body 42 Electric motor 52 Throttle valve 54 Throttle shaft 541 Portion of throttle shaft protruding from unit case 60 Unit case 80 Manual operation lever 82 Idle rotation speed adjusting mechanism 94 Push rod

Claims (3)

A throttle valve housed in a throttle body disposed in an intake passage of a general-purpose engine, a throttle shaft that supports the throttle valve, and an electric motor that rotates the throttle shaft, and drives the electric motor to In a throttle device of a general-purpose engine that opens and closes the throttle valve by rotating a throttle shaft and adjusts the amount of air sucked through the intake passage, the throttle shaft and the electric motor are accommodated in the throttle body A throttle device for a general-purpose engine, characterized in that a unit case is provided, one end of the throttle shaft is protruded from the unit case, and a manually operated lever is attached to the protruded portion. 2. The throttle device for a general-purpose engine according to claim 1, further comprising an idle rotation speed adjustment mechanism that can be manually operated to adjust an idle rotation speed of the general-purpose engine by adjusting a position of the manual operation lever. 3. The throttle device for a general-purpose engine according to claim 1, further comprising a push rod that can be manually operated to push the manual operation lever to open the throttle valve.

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