JP2009013965A - Electronic control device for carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low cost electronic control device for a carburetor capable of automatically opening and closing a throttle valve and a choke valve by one electric motor. <P>SOLUTION: In the electronic control device for the carburetor having an electric motor 11 mounted on the carburetor C provided in an intake air path 2 in an order of the choke valve 4 and the throttle valve 5 from an upstream side, and having an output shaft 20 of the electric motor 11 connected to the throttle valve 5 via the transmission mechanism 10 to open and close the throttle valve 5 by output of the electric motor 11, second output parts 23, 24 of the transmission mechanism 10 are stopped and the throttle valve 5 is retained at a roughly totally closed position when the choke valve 4 is opened from a totally closed position to a full open position by output of first output parts 37, 39 of the transmission mechanism 10, and the first output parts 37, 39 are stopped and open and close of the throttle valve 5 is controlled by output of the second output parts after the choke valve 4 is fully opened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic control device for a carburetor mainly applied to a general-purpose engine, and in particular, an electric motor is attached to a carburetor in which a choke valve and a throttle valve are arranged in this order from the upstream side of the intake passage. In order to open and close the throttle valve by output, the output shaft of the electric motor is connected to the throttle valve via a transmission mechanism, and the electric motor is connected to an electronic control unit for controlling the operation. About.

Conventionally, as an electronic control device for such a carburetor, one that manually opens and closes a choke valve (see Patent Document 1), and one that opens and closes a choke valve by an electric motor different from an electric motor for driving a throttle valve (See Patent Document 2).
JP-A-2005-76522 JP 2006-329094 A

  By the way, the former of the conventional device requires skill in manually opening and closing the choke valve, and the latter requires two electric motors for driving the throttle valve and the choke valve. Disadvantageous.

  The present invention has been made in view of such circumstances, and provides a low-cost electronic control device for a carburetor capable of automatically opening and closing a throttle valve and a choke valve by a single electric motor. For the purpose.

  In order to achieve the above object, the present invention attaches an electric motor to a carburetor in which a choke valve and a throttle valve are arranged in this order from the upstream side of the intake passage, and the throttle valve is opened and closed by the output of the electric motor. In the electronic control unit for a carburetor, the output mechanism of the carburetor is connected to the throttle valve via a transmission mechanism, and an electronic control unit for controlling the operation of the electric motor is connected to the electric motor. Provided with a first output unit and a second output unit for taking out the output, and the choke valve is driven by the output of the first output unit, and the throttle valve is individually opened and closed by the output of the second output unit. First feature.

  The first output portion corresponds to a control groove 37 and a choke lever 39 in an embodiment of the present invention described later, and the second output portion corresponds to a non-constant speed drive gear 23 and a non-constant speed driven gear 24. Correspond.

  According to the present invention, in addition to the first feature, when the transmission mechanism opens the choke valve from the fully closed position to the fully opened position by the output of the first output section, the second output section is paused. The throttle valve is held in a substantially fully open position, and after the choke valve is fully opened, the first output unit is stopped and the throttle valve is controlled to open and close by the output of the second output unit. Is the second feature.

  In addition to the second feature of the present invention, the transmission mechanism includes a pinion provided on the output shaft of the electric motor, an intermediate gear driven to decelerate by the pinion, and a drive gear interlocked with the intermediate gear. , A driven gear connected to the throttle valve to form the second output portion in cooperation with the drive gear, a control groove formed in the intermediate gear, and the first groove in cooperation with the control groove. A choke lever connected to the choke valve and engaged with the control groove to constitute one output portion, and the drive gear and the driven gear are connected to the choke valve by the control groove when the intermediate gear is rotated. A third feature is that the driven gear is started to be driven by the drive gear when the is operated from the fully closed position to the fully open position.

  In addition to the third feature of the present invention, when the throttle valve is opened by driving the driven gear by the drive gear, the reduction ratio between the drive gear and the driven gear approaches the fully closed position. A fourth feature is that the driving gear and the driven gear are configured to be non-constant speed types so as to increase as the speed increases.

  Furthermore, in addition to any one of the first to fourth aspects, the present invention provides a throttle valve opening changing speed that accompanies the rotation of the electric motor so that the choke valve opens as the electric motor rotates. A fifth feature is that the transmission mechanism is configured to be slower than the degree of change rate.

  According to the first feature of the present invention, a single electric motor for opening and closing the choke valve and the throttle valve is sufficient, and a reduction in the number of parts can bring about a significant cost reduction and a reduction in weight. Can do.

  According to the second feature of the present invention, the engine can be warmed up accurately.

  According to the third feature of the present invention, the sequential control of the choke valve and the throttle valve can be reliably performed with a transmission mechanism having a simple structure.

  According to the fourth aspect of the present invention, the opening degree of the throttle valve can be finely and accurately controlled in the normal rotation range of the engine. Thus, the engine speed can be automatically controlled to the desired speed regardless of load fluctuations.

  According to the fifth aspect of the present invention, it is possible to finely adjust the opening degree of the throttle valve, and to prevent hunting of the engine speed.

  Embodiments of the present invention will be described based on preferred embodiments of the present invention shown in the accompanying drawings.

  1 is a partially cross-sectional front view of a vaporizer equipped with an electronic control device of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along line 3-3 of FIG. 4 is a cross-sectional view taken along line 4-4, FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 3, FIG. 6 is a first operation explanatory view showing the state of the transmission mechanism when the engine is started, and FIG. FIG. 8 is a third action explanatory diagram showing the state of the transmission mechanism immediately after the end of the warm-up operation, and FIG. 9 is a state of the transmission mechanism during normal operation of the engine. FIG. 10 is a characteristic diagram showing the opening / closing timings of the choke lever and the throttle valve.

  1 and 2, a carburetor C includes a carburetor body 1 having an intake passage 2 connected to an intake port of a general-purpose engine (not shown), and a float chamber body 3 joined to the lower end of the carburetor body 1. The choke valve 4 and the throttle valve 5 are disposed in the intake passage 2 from the upstream side, and a fuel nozzle 9 is provided in the venturi portion of the intake passage 2 sandwiched between the choke valve 4 and the throttle valve 5. Open. Each of the choke valve 4 and the throttle valve 5 is configured as a butterfly type that is opened and closed by the rotation of the valve shafts 4 a and 5 a that are vertically supported by the carburetor body 1. An electronic control device D according to the present invention that controls opening and closing of the choke valve 4 and the throttle valve 5 is attached to the upper portion of the carburetor body 1. Hereinafter, the valve shaft 4a of the choke valve 4 is referred to as a choke shaft 4a, and the valve shaft 5a of the throttle valve 5 is referred to as a throttle shaft 5a.

  The electronic control unit D will be described with reference to FIGS.

  1 and 3, the case 7 of the electronic control unit D is attached to the upper surface of the vaporizer body 1. The case 7 includes a case main body 7a fixed to the vaporizer main body 1 with a plurality of bolts 8, and a case cover 7b for closing the upper open surface of the case main body 7a. The upper ends of the choke shaft 4a and the throttle shaft 5a extend into the case 7. In the case 7, the output of the single electric motor 11 common to the choke shaft 4a and the throttle shaft 5a via the transmission mechanism 10 is provided. The shaft 20 is connected. The mounting flange 12 of the electric motor 11 is fixed to the case main body 7a by a bolt 13.

  An electronic control unit 15 for controlling the drive of the electric motor 11 is attached to the case cover 7b. The electronic control unit 15 includes an output signal of an engine temperature sensor 16 for detecting the engine temperature and an engine desired by the operator. An output signal of a rotation speed setting unit 17 for setting the rotation speed is input.

  3 to 5, the transmission mechanism 10 is integrally formed with a pinion 21 fixed to the output shaft 20 of the electric motor 11, a large-diameter intermediate gear 22 meshing with the pinion 21, and the intermediate gear 22 coaxially. And a non-constant speed driven gear 24 that is fixed to the throttle shaft 5 a and meshes with the non-constant speed drive gear 23. Is connected to a throttle closing spring 25 for urging this in the closing direction of the throttle valve 5. The intermediate gear 22 and the non-constant speed drive gear 23 constitute a single stepped gear 26, and a support shaft 27 that rotatably supports the stepped gear 26 projects from the bottom surface of the case body 7a. The boss 28 is press-fitted and fixed.

  The non-constant speed drive and driven gears 23 and 24 are both constituted by an elliptical gear or a part of an eccentric gear, and mesh with each other in the movable region β (see FIG. 10) of the throttle valve 5 in the rotation range of the intermediate gear 22. When these mesh with each other, the reduction ratio of the non-constant speed driven gear 24 with respect to the non-constant speed drive gear 23 decreases as the opening of the throttle valve 5 increases (FIG. 10). (See curve b). Further, the non-constant speed drive gear 23 is merely in contact with the non-constant speed driven gear 24 in order to keep the throttle valve 5 in the fully open position in the movable region α (see FIG. 10) of the choke lever 39 in the rotation range of the intermediate gear 22. It has a cylindrical surface 23a that cannot drive the driven gear 24. The cylindrical surface 23a is flush with the non-constant speed drive gear 23 at the center.

  As shown in FIGS. 3 and 5, a boss 39a of a choke lever 39 is rotatably fitted to the choke shaft 4a via a bearing bush 40. Between the choke lever 39 and the choke shaft 4a, A relief mechanism 31 is provided that automatically opens the choke valve 4 to prevent over-concentration of the air-fuel mixture when a negative pressure of a certain value or more is generated downstream of the intake passage 2. The relief mechanism 31 receives an abutting protrusion 33 projecting from the outer periphery of the end of the choke shaft 4a and the abutting protrusion 33 formed on the choke lever 39 so as to allow the rotation of the predetermined angle. And a relief spring 34 that urges the contact protrusion 33 in the direction of closing the choke valve 4 in the groove 32. In the configuration of the relief mechanism 31, the choke shaft 4 a is offset from the center of the choke valve 4 in one direction so that valve opening torque acts on the choke valve 4 due to intake negative pressure generated downstream of the intake passage 2. Is done.

  The choke lever 39 is connected to a choke closing spring 35 that urges the choke lever 39 in the closing direction of the choke valve 4.

  On the other hand, on the lower surface of the intermediate gear 22, a control groove 37 is formed which includes a concentric arc groove 37a concentric with the intermediate gear 22 and a radial groove 37b bent radially inward from one end of the arc groove 37a. A driven pin 38 at the tip of the choke lever 39 is slidably engaged with the control groove 37.

  The transmission mechanism 10, particularly the non-constant speed driven and driven gears 23, 24, has an opening changing speed of the throttle valve 5 associated with the rotation of the electric motor 11, and the choke valve 4 associated with the rotation of the electric motor 11. It is comprised so that it may become slower than opening change speed. In FIG. 10, the opening change speed of the choke lever 39 appears as the slope of the straight line a, and the opening change speed of the throttle valve 5 appears as the slope of the curve b. The average slope of the curve b is the slope of the straight line a. More gradual.

  Next, the operation of this embodiment will be described mainly with reference to FIGS.

  When the engine is started, the electronic control unit 15 operates the electric motor 11 based on the engine temperature information input from the engine temperature sensor 16 and drives the intermediate gear 22 via the pinion 21. That is, when the engine is cold, the intermediate gear 22 is rotated to a position where the radial groove 37b of the control groove 37 receives the driven pin 38 of the choke lever 39 as shown in FIG. At this time, the cylindrical surface 23 a of the non-constant speed driving gear 23 is in contact with the non-constant speed driven gear 24, and the throttle valve 5 is held in the fully open position against the urging force of the throttle closing spring 25.

  Therefore, if the engine is cranked by the starter to start the engine, the fuel from the fuel nozzle 9 is generated in the intake passage 2 of the carburetor C so that an air-fuel mixture having a concentration suitable for starting at that time is generated. The engine is always started easily.

  If the engine intake negative pressure acts on the fully closed choke valve 4 after the engine is started and the valve opening torque of the choke valve 4 due to the intake negative pressure exceeds the valve closing torque of the choke valve 4 by the relief spring 34 The choke valve 4 automatically opens to reduce the intake negative pressure, thereby avoiding over-concentration of the air-fuel mixture generated in the intake passage 2 and ensuring a good warm-up operation state of the engine.

  If the engine temperature rises due to the progress of the warm-up operation, the electronic control unit 15 operates the electric motor 11 based on the output signal of the engine temperature sensor 16 that changes accordingly, and the intermediate gear 22 is connected via the pinion 21. 7 turns counterclockwise. Then, the choke lever 39 is forcibly and gradually opened by moving the driven pin 38 by the rotating radial groove 37b. When the choke lever 39 reaches the fully open position, the driven pin 38 is concentric with the intermediate gear 22 in the circular arc groove 37a. Is reached (state shown in FIG. 8). Therefore, thereafter, even if the intermediate gear 22 further rotates counterclockwise, the driven pin 38 only moves relatively in the arc groove 37a, and the choke valve 4 maintains the fully open position ( (See the choke movable region α in FIG. 10). That is, the choke lever 39 is in a resting state when the choke valve 4 is fully opened.

  On the other hand, the non-constant speed drive gear 23 that rotates integrally with the intermediate gear 22 is simply a non-constant speed on the cylindrical surface 23a until the choke valve 4 reaches the fully open position, as shown in FIGS. The driven gear 24 is received, and the non-constant speed driven gear 24 is not driven even when the intermediate gear 22 rotates. When the choke valve 4 reaches the fully open position, the non-constant speed drive gear 23 starts meshing with the non-constant speed driven gear 24 (see FIG. 8), and thereafter, the intermediate gear 22 rotates counterclockwise. Accordingly, since the non-constant speed drive gear 23 drives the non-constant speed driven gear 24, the throttle valve 5 is closed from the fully opened position (see FIG. 9), and the engine speed is set by the speed setting device 17. Match the set desired rotation speed. After that, the throttle valve 5 is controlled to open and close so as to correct the engine speed that changes in accordance with the fluctuation of the engine load (see the movable region β of the throttle valve 5 in FIG. 10).

  At that time, the opening change speed of the throttle valve 5 is controlled slower than the opening change speed of the choke valve 4 by the non-constant speed drive and the driven gears 23 and 24. This makes it possible to perform finely and prevents engine speed hunting.

  In particular, the reduction ratio of the non-constant speed driven gear 24 with respect to the non-constant speed drive gear 23 decreases as the opening of the throttle valve 5 increases, so that the opening of the throttle valve 5 can be precisely and precisely adjusted in the normal rotation range of the engine. Can be controlled. Thus, the engine speed can be automatically controlled to the desired speed regardless of load fluctuations.

  In this way, the output of one electric motor 11 is divided in the intermediate gear 22, one of which is connected to the choke lever 39 via the control groove 37 and the other is connected to the non-constant speed drive gear 23 and the non-constant speed driven gear 24. Therefore, the choke valve 4 and the electric motor 11 that opens and closes the throttle valve 5 are sufficient, and the cost can be greatly reduced by reducing the number of parts. In addition to being able to reduce weight.

  When the choke valve 4 is opened from the fully closed position to the fully open position, the choke valve 4 is controlled so that only the throttle valve 5 is controlled to open / close after the throttle valve 5 is held at the substantially fully open position and the choke valve 4 is fully opened. Since the throttle valve 5 is sequentially controlled, the engine can be warmed up accurately.

  Further, the transmission mechanism 10 includes a pinion 21 provided on the output shaft 20 of the electric motor 11, an intermediate gear 22 driven to decelerate by the pinion 21, a non-constant speed drive gear 23 interlocked with the intermediate gear 22, a throttle valve 5, a non-constant speed driven gear 24 driven by a non-constant speed drive gear 23, a control groove 37 formed in the intermediate gear 22, and a driven pin 38 connected to the choke valve 4 and the control groove 37. The non-constant speed drive gear 23 and the non-constant speed driven gear 24 are configured to engage with each other and the choke valve 4 is moved from the fully closed position to the fully open position by the control groove 37 when the intermediate gear 22 is rotated. Since it is configured to start driving the non-constant speed driven gear 24 by the driving gear 23 at the time of operation, the choke valve 4 and the throttle valve 5 are sequentially arranged with the transmission mechanism 10 having a simple structure. It is possible to perform your securely.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention.

The partial cross-sectional front view of a vaporizer provided with the electronic control apparatus of this invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 1. FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. The 1st operation explanatory view showing the state of the power transmission mechanism at the time of engine starting. The 2nd operation explanatory view showing the state of the power transmission mechanism in engine warm-up operation. The 3rd operation explanatory view showing the state of the power transmission mechanism just after the end of warm-up operation. The 4th operation explanatory view showing the state of the power transmission mechanism at the time of regular operation of an engine. The characteristic line figure which shows the opening / closing timing of a choke lever and a throttle valve.

Explanation of symbols

C ... Vaporizer D ... Electronic control device 2 ... Intake passage 4 ... Choke valve 5 ... Throttle valve 10 ... Transmission mechanism 11 ... ... Electric motor 15 ... Electronic control unit 20 ... Output shaft 21 ... Pinion 22 ... Intermediate gears 23, 24 ... Second output part of transmission mechanism (non-constant speed) Drive gear, non-constant speed driven gear)
37, 39 ... 1st output part of transmission mechanism (control groove, choke lever)

Claims (5)

An electric motor (11) is attached to a carburetor (C) in which a choke valve (4) and a throttle valve (5) are arranged in this order from the upstream side of the intake passage (2), and the output of the electric motor (11) In order to open and close the throttle valve (5), the output shaft (20) of the electric motor (11) is connected to the throttle valve (5) through a transmission mechanism (10), and the electric motor (11) In an electronic control unit for a vaporizer, to which an electronic control unit (15) for controlling the operation is connected,
The transmission mechanism (10) is provided with a first output part (37, 39) and a second output part (23, 24) for taking out an output, and the choke valve (4) is output by the output of the first output part (37, 39). ), And the throttle valve (5) is individually driven to open and close by the output of the second output section (23, 24). The electronic control device for a vaporizer according to claim 1,
When the transmission mechanism (10) opens the choke valve (4) from the fully closed position to the fully open position by the output of the first output section (37, 39), the second output section (23, 24) is opened. After stopping and holding the throttle valve (5) in a substantially fully open position and opening the choke valve (4), the first output part (37, 39) is stopped and the second output part ( 23, 24) An electronic control unit for a carburetor, characterized in that the throttle valve (5) is controlled to open and close by the output of 23, 24). The electronic control device for a vaporizer according to claim 2,
The transmission mechanism (10) includes a pinion (21) provided on the output shaft (20) of the electric motor (11), an intermediate gear (22) driven to decelerate by the pinion (21), and an intermediate gear ( 22) and a driven gear (23) coupled to the throttle valve (5) to form the second output part (23, 24) in cooperation with the drive gear (23). 24), a control groove (37) formed in the intermediate gear (22), and the choke valve (37, 39) to constitute the first output part (37, 39) in cooperation with the control groove (37). 4) and a choke lever (39) engaged with the control groove (37), and the drive gear (23) and the driven gear (24) are rotated when the intermediate gear (22) is rotated. The choke valve (4) is fully closed by the control groove (37). Characterized by being configured to start driving the driven gear (24) by the drive gear (23) when actuated to the fully open position from the vaporizer of the electronic control unit. The electronic control device for a vaporizer according to claim 3,
When the driven gear (24) is driven by the drive gear (23) and the throttle valve (5) is opened, the reduction ratio between the drive gear (23) and the driven gear (24) is the same as the throttle valve (5). An electronic control unit for a carburetor, characterized in that the drive gear (23) and the driven gear (24) are configured to be non-constant speed types so as to increase as they approach the closed position. In the electronic control apparatus of the vaporizer in any one of Claims 1-4,
The opening change speed of the throttle valve (5) accompanying the rotation of the electric motor (11) is slower than the opening change speed of the choke valve (4) accompanying the rotation of the electric motor (11). An electronic control unit for a vaporizer, characterized in that the transmission mechanism (10) is configured.

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