JP2007002752A - Electronic control device for carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact electronic control device for a carburetor capable of enhancing the durability of an electric actuator and an electronic control unit. <P>SOLUTION: In the electronic control device for the carburetor consisting of transmission devices 24, 25 to be connected to valves 7, 8, electric actuators 20, 21 to drive these devices, and an electronic control unit 12a for controlling the operation thereof, the transmission devices 24, 25, the electric actuators 20, 21 and the electronic control unit 12a are accommodated in and held by a casing 12 mounted on a carburetor C, and ventilation means 74, 74', 89, 90 to be communicated with the outside are connected to a bottom in a casing 10 so that the inside of the casing 10 is breathable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic controller for a carburetor mainly applied to a general-purpose engine, and in particular, a transmission connected to a valve that opens and closes an intake passage of the carburetor, and an electric drive that opens and closes the valve via the transmission. The present invention relates to improvement of an actuator including an actuator and an electronic control unit for controlling the operation of the electric actuator.

Such an electronic control device for a vaporizer is known, for example, as disclosed in Patent Document 1 below.
Japanese Utility Model Publication No. 56-150834

  In the conventional electronic control unit for carburetor, the transmission device, the electric actuator, and the electronic control unit are separated and attached to the carburetor or the engine, so a separate casing is required to protect them from disturbance. In particular, the general-purpose engine used in connection with various working machines is prevented from being made compact.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electronic control device for a vaporizer that is compact and can contribute to improvement in durability of an electric actuator and an electronic control unit.

  In order to achieve the above object, the present invention provides a transmission device connected to a valve that opens and closes an intake passage of a carburetor, an electric actuator that drives the valve to open and close via the transmission device, and an operation of the electric actuator. In an electronic control unit for a vaporizer comprising an electronic control unit for controlling the transmission, the transmission device, the electric actuator and the electronic control unit are accommodated and held in a casing attached to the vaporizer, and at the bottom of the casing, externally The first feature is that the venting means is connected.

  The valve corresponds to the choke valve 7 and the throttle valve 8 in the embodiment of the present invention described later, and the electric actuator corresponds to the first and second electric motors 20 and 21 in the embodiment. The transmission device corresponds to the first and second transmission devices 24 and 25 in the embodiment.

  According to the present invention, in addition to the first feature, the vent means is constituted by a vent hole formed in the carburetor so that a bottom portion in the casing communicates with an intake passage of the carburetor. And

  In addition to the second feature, the third feature of the present invention is that the outer end of the vent hole is opened in a bearing hole of a carburetor that supports the choke valve shaft.

  Furthermore, in addition to the first feature, the present invention provides that at least a part of the ventilation means is formed on a surface facing the vaporizer and an adjacent member joined thereto, and is opened to the atmosphere with the outer end facing downward. The fourth feature is that the labyrinth is configured as a maze.

  The adjacent member corresponds to a cylinder head 3a in an embodiment of the present invention described later.

  According to the first feature of the present invention, the electronic control device for the vaporizer is configured by housing the transmission device, the electric actuator and the electronic control unit in a common casing. The entire engine including the carburetor to which the control device is attached can be made compact.

  Moreover, since the bottom of the casing communicates with the outside through the ventilation means, when the air in the casing expands and contracts due to heat generation and heat dissipation of the electric actuator, and heating and cooling of the casing due to engine temperature changes. , The inside of the casing can breathe, thus preventing excessive pressure from being applied to the electronic control unit and the electric actuator, and also preventing dew condensation on the electronic control unit and the actuator due to the breathing. It is possible to improve the durability.

  According to the second feature of the present invention, during operation of the engine, intake negative pressure generated in the intake passage acts in the casing through the vent hole, so that water droplets due to condensation should be accumulated on the bottom of the casing. This can be pulled out to the intake passage.

  In addition, connecting the vent hole to the intake passage eliminates the risk of inhaling external dust when breathing inside the casing.

  According to the third feature of the present invention, even if the vent hole has a large diameter, the opening end is narrowed between the inner peripheral surface of the bearing hole and the outer peripheral surface of the choke valve shaft fitted therein. As a result, when the engine blows back, it is possible to prevent the fuel contained in the blown-back gas from entering the air vent.

  According to the fourth aspect of the present invention, the inside of the casing communicates with the atmosphere via the labyrinth 89 so that it can breathe through it. Moreover, since the maze opens to the atmosphere with its outer end facing downward, rainwater and dust are not easily allowed to enter, and even if it may enter, it flows down to the outside naturally. Can be discharged.

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

  1 is a front view of a general-purpose engine according to an embodiment of the present invention, FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1, FIG. 3 is a view taken in the direction of arrow 3 in FIG. 5 is a view taken in the direction of arrow 5 in FIG. 4 (a plan view of the electronic control device), FIG. 6 is a plan view of the electronic control device with the cover removed, and FIG. 7 is a cover of the electronic control device. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 4, and FIG. 9 is a plan view (A) and a front view of the first transmission device for controlling the choke valve to a fully closed state. FIGS. 10 (B) and 10 are a plan view (A) and a front view (B) of the first transmission device for controlling the choke valve to a fully opened state, and FIG. 11 is a plan view of the first transmission device showing an operating state of the relief mechanism. (A), front view (B), and FIG. 12 are plan views showing the non-operating state (A) and the operating state (B) of the choke forced valve closing mechanism in FIG. 7, and FIG. 13 is an electronic control unit. 14 is a diagram showing the relationship between the choke valve opening and the lever ratio between the relief lever and the choke lever, FIG. 15 is a sectional view taken along line 15-15 in FIG. 5, and FIG. 16 is an electronic control unit. FIG. 17 is a sectional view taken along line 17-17 of FIG. 4, FIG. 18 is a view corresponding to FIG. 17, showing a modification of the ventilation structure in the casing, and FIG. FIG.

  First, as shown in FIGS. 1 to 3, the engine body 1 of the general-purpose engine E includes a crankcase 2 having a mounting flange 2 a on the lower surface and horizontally supporting the crankshaft 4, and one side from the crankcase 2. A recoil type engine starter 5 for cranking the crankshaft 4 is attached to the front side of the crankcase 2. A fuel tank T disposed above the crankcase 2 and an air cleaner A and an exhaust muffler M adjacent to the fuel tank T above the cylinder 3 are attached to the engine body 1. A vaporizer C is mounted on one side of the head of the cylinder 3 to supply the air-fuel mixture generated by intake from the air cleaner A into the cylinder 3.

  As shown in FIGS. 4 and 8, the carburetor C has an intake passage 6 connected to the intake port at the head of the cylinder 3. The intake passage 6 has an upstream side, that is, an air cleaner A side. The choke valve 7 and the throttle valve 8 are disposed, and a fuel nozzle (not shown) opens in the venturi portion of the intake passage 6 in the middle portion between the valves 7 and 8. Both the choke valve 7 and the throttle valve 8 are configured as a butterfly type that is opened and closed by the rotation of the valve shafts 7a and 8a. Mounted on top of vessel C. Hereinafter, the valve shaft 7a of the choke valve 7 is referred to as a choke valve shaft 7a, and the valve shaft 8a of the throttle valve 8 is referred to as a throttle valve shaft 8a.

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

  First, in FIGS. 4, 5, and 14, the casing 10 of the electronic control unit D includes a casing body 11 to which the bottom wall 11 a is joined to the upper end surface of the vaporizer C, and the casing body 11 has its open surface closed. And a lid body 12 which is joined together. The lid 12 is fitted to the casing main body 11 with a flat box-shaped cover 12b made of a steel plate joined with a bolt 13 so as to cover the open end face, and the cover 12b. 12b and an electronic control unit 12a sandwiched between the casing main body 11, and an endless seal portion 19 in close contact with the lower surface of the outer peripheral portion of the electronic control unit 12a is provided on the inner peripheral edge of the open end surface of the casing main body 11. Installed.

  As shown in FIGS. 4 and 15, the cover 12b is formed with a bulging portion 71 that bulges outward except for its peripheral edge, and this bulging portion 71 is located between the electronic control unit 12a. A void 70 is defined. An air passage 72 that communicates the gap 70 with the open end of the cover 12b is provided between the electronic control unit 12a and the cover 12b. The air passage 72 is bent in a bowl shape and opens to the atmosphere with the outer end facing downward.

  As shown in FIGS. 4, 6, and 7, the casing body 11 includes a casing body 11 that divides the casing 10 into a transmission chamber 14 on the bottom wall 11 a side and a driving chamber 15 on the lid 12 side. A separate partition plate 16 is provided, and this partition plate 16 is fixed to the vaporizer C together with the bottom wall 11 a by a plurality of bolts 17.

  An opening 18 is provided in the bottom wall 11 a of the casing body 11, and a recess 14 a that matches the opening 18 is provided in the upper end surface of the vaporizer C, and this recess 14 a is added as a part of the transmission chamber 14. It is. It arrange | positions so that each outer end part of the choke valve axis | shaft 7a and the throttle valve axis | shaft 8a may face this recessed part 14a.

  A first electric motor 20 and a second electric motor 21 are respectively attached to the partition plate 16 by screws 22 and 23 in the drive chamber 15 to transmit the output torque of the first electric motor 20 to the choke valve shaft 7a. A transmission device 24 and a second transmission device 25 that transmits the driving force of the second electric motor 21 to the throttle valve shaft 8 a are disposed in the transmission chamber 14. Thus, the first and second electric motors 20 and 21 and the first and second transmission devices 24 and 25 are accommodated in the casing 10 and protected.

  As shown in FIGS. 7 to 9, the first transmission device 24 is supported at both ends by the first pinion 27 fixed to the output shaft 20 a of the first electric motor 20, the partition plate 16, and the carburetor C. A first sector gear 29 that is rotatably supported by one support shaft 28 and meshes with the first pinion 27; and a relief lever 30 that is supported by the first support shaft 28 so as to be rotatable relative to the first sector gear 29. , A choke lever 32 integrally formed at the outer end of the choke valve shaft 7a and connected to the relief lever 30 is provided. The first sector gear 29 and the relief lever 30 are respectively formed with contact pieces 29a and 30a that contact each other and transmit the driving force in the opening direction of the first sector gear 29 to the choke valve 7 to the relief lever 30. A relief spring 31 comprising a torsion coil spring is mounted around the first support shaft 28 to urge the first sector gear 29 and the relief lever 30 with a constant set load in the contact direction of the contact pieces 29a, 30a. .

  As shown in FIG. 9, the connecting structure of the relief lever 30 and the choke lever 32 includes a connecting pin 34 provided on the choke lever 32 and protruding from the side surface of the tip of the relief lever 30. It is configured by slidably engaging with a long hole 35 extending in the longitudinal direction.

  Thus, the output torque of the first electric motor 20 is transmitted from the first pinion 27 to the first sector gear 29 at a reduced speed. The first sector gear 29 and the relief lever 30 are normally connected via contact pieces 29 a and 30 a and a relief spring 31 and can rotate together. Therefore, the first sector gear 29 and the relief lever 30 are transmitted to the first sector gear 29. The output torque of the electric motor 20 is transmitted from the relief lever 30 to the choke lever 32 and the choke valve shaft 7a, and the choke valve 7 can be opened and closed.

  By the way, as shown in FIG. 8, the choke valve shaft 7a is arranged offset from the center of the intake passage 6 to one side, and the choke valve 7 is in the fully closed state so that the side with the larger rotation radius of the choke valve 7 is located. , It is inclined with respect to the central axis of the intake passage 6 so as to come to the downstream side of the intake passage 6 from the side with the smaller rotation radius. Therefore, when the first electric motor 20 is operating so as to fully close the choke valve 7 or hold the choke valve 7 at a small opening, if the intake negative pressure of the engine E exceeds a predetermined value, the rotation radius of the choke valve 7 is large. Until the difference between the rotational moment due to the intake negative pressure acting on the side and the rotational moment due to the intake negative pressure acting on the side with the smaller rotation radius of the choke valve 7 balances with the rotational moment due to the relief spring 31. The choke valve 7 can be opened regardless of the operation of the motor 20 (see FIG. 11). Therefore, the relief lever 30 and the relief spring 31 constitute a relief mechanism 33. The relief lever 30 and the relief spring 31 are supported by the first support shaft 28 so as to be offset from the output shaft 20a of the first electric motor 20 and the choke valve shaft 7a.

  As shown in FIGS. 9 and 10, the relief lever 30 and the choke lever 32 are arranged at right angles or close to right angles at the fully open position and the fully closed position of the choke valve 7, and the connecting pin 34 is a long hole. 35 is positioned on one end side far from the choke valve shaft 7a. Further, the relief lever 30 and the choke lever 32 are aligned in a straight line at a predetermined intermediate opening of the choke valve 7, and the connecting pin 34 is positioned on the other end side of the long hole 35 on the side close to the choke valve shaft 7a. Therefore, the effective arm length of the choke lever 32 is maximum at the fully open and fully closed positions of the choke valve 7 and minimum at a predetermined intermediate opening of the choke valve 7, and as a result, the lever ratio between the relief lever 30 and the choke lever 32 is increased. As shown in FIG. 14, the maximum value changes when the choke valve 7 is fully opened and fully closed and the minimum value when the choke valve 7 is at a predetermined intermediate opening degree.

  Even when the first electric motor 20 becomes inoperable when the choke valve 7 is fully opened due to insufficient storage of a battery 60 (FIG. 13), which will be described later, the choke valve 7 is forced to be able to start the engine E. A choke forced closing mechanism 37 that closes the valve is provided adjacent to one side of the relief lever 30.

  As shown in FIGS. 4, 7 and 12, the forced choke valve closing mechanism 37 includes a lever shaft 38 whose both ends are rotatably supported by the bottom wall 11a and the carburetor C of the casing body 11, and the lever. An operating lever 39 connected to the shaft 38 and disposed at the lower portion of the casing body 11, an operating arm 40 formed integrally with the lever shaft 38 and facing one side surface of the contact piece 30 a of the relief lever 30, The operating arm 40 is composed of a return spring 41 made of a torsion coil spring connected so as to be urged away from the contact piece 30a, that is, in a backward direction, and the choke valve 7 is fully opened. When the operating lever 39 is rotated against the urging force of the return spring 41, the operating arm 40 presses the contact piece 30a of the relief lever 30 in the closing direction of the choke valve 7. That.

  When the operating lever 39 and the operating arm 40 are integrally connected to each other, the retracted position of the operating arm 40 is such that one side of the operating arm 40 abuts on a locking pin 42 provided on the casing body 11 to lock the fixed end of the return spring 41. It is regulated by. The operation lever 39 is usually arranged, for example, with its tip directed toward the engine E so that no other object hits it. By doing so, erroneous operation of the operation lever 39 is avoided.

  Next, the second transmission device 25 will be described with reference to FIGS. 4, 6 and 7.

  The second transmission device 25 is rotatably supported by a second pinion 44 fixed to the output shaft 21a of the second electric motor 21 and a second support shaft 45 supported at both ends by the partition plate 16 and the vaporizer C. The second sector gear 46 meshing with the second pinion 44, the non-constant speed drive gear 47 integrally formed on one side in the axial direction of the second sector gear 46, and the outer end of the throttle valve shaft 8a are fixed and non-fixed. A non-constant speed driven gear 48 that meshes with the constant speed drive gear 47 is connected to a throttle valve closing spring 49 that urges the non-constant speed driven gear 48 in the closing direction of the throttle valve 8. The non-constant speed drive and driven gears 47 and 48 are both elliptical gears or part of eccentric gears so that their gear ratio, that is, the reduction ratio, decreases as the opening of the throttle valve 8 increases. Therefore, the reduction ratio is maximum when the throttle valve 8 is fully closed. In this way, fine opening degree control by the operation of the second electric motor 21 is possible in a low opening degree range including the idle opening degree of the throttle valve 8.

  By the way, the first and second support shafts 28 and 45 which are one component of the first and second transmission devices 24 and 25 are supported by fitting both ends to the vaporizer C and the partition plate 16 respectively. Therefore, it plays the role of a positioning pin for positioning the partition plate 16 at a fixed position of the vaporizer C, and does not require a dedicated positioning pin, thereby contributing to a reduction in the number of parts. By such positioning of the partition plate 16, the connection between the first transmission device 24 and the choke valve shaft 7a and the connection between the second transmission device 25 and the throttle valve 8 can be accurately performed. Moreover, since the first and second electric motors 20 and 21 are attached to the partition plate 16, the connection between the first electric motor 20 and the first transmission device 24, and the second transmission device 25 with the second electric motor 21, Can be accurately connected.

  In FIG. 17, the carburetor C is provided with a ventilation structure inside the casing 10, that is, the transmission chamber 14 and the drive chamber 15 that communicate with each other. This ventilation structure is formed by a ventilation hole 74 or 74 ′ that is formed in the upper side wall of the carburetor C and communicates the bottom of the casing 10 with the intake passage 6. The vent hole 74 is provided so as to open to the intake passage 6 through a bearing hole 77 that rotatably supports the choke valve shaft 7 a, and the vent hole 74 ′ is provided to open directly to the intake passage 6.

  Next, the electronic control unit 12a will be described with reference to FIGS.

  As shown in FIGS. 4 and 5, the electronic control unit 12 a has various electronic components 51 to 54 mounted on a substantially rectangular board 50 on which an electric circuit is printed and wired, and input connectors 55 at both longitudinal ends of the board 50. The output connector 56 is coupled. The substrate 50 is arranged in parallel with the bottom wall 11a of the casing body 11. On the inner surface facing the drive chamber 15, the large electronic device having high height such as a transformer 51, capacitors 52a and 52b, a heat sink 53, and the like. A thin electronic component having a small thickness such as a component and a CPU 54 is mounted, and a pilot lamp 68 is mounted on the outer surface of the substrate 50. Accordingly, the large electronic components 51 to 53 and the thin electronic component 54 are accommodated in the driving chamber 15, and at this time, the large electronic components 51 to 53 are close to the partition plate 16 on one side of the driving chamber 15. The thin electronic component 54 is disposed on the other side of the drive chamber 15. The first and second electric motors 20 and 21 are disposed on the other side of the driving chamber 15 so as to be close to the substrate 50 and the thin electronic component 54. Thus, the first and second electric motors 20 and 21 and the large electronic components 51 to 53 are arranged alternately.

  With such an alternate arrangement, the first and second electric motors 20 and 21 and the large electronic components 51 to 53 can be efficiently accommodated in the drive chamber 15. Therefore, the dead space of the drive chamber 15 can be greatly reduced to reduce the capacity of the drive chamber 15, and the casing 10 can be reduced in size, and the entire engine E including the carburetor C with the electronic control unit D can be made compact. You can plan.

  In order to seal the substrate 50 on which the various electronic components 51 to 54 are mounted, a synthetic resin coating 57 for covering them is formed. The coating 57 is formed with a substantially uniform thickness along the shape of the substrate 50 and various electronic components 51 to 54.

  The light emitting portion of the pilot lamp 68 (see FIG. 5) is disposed so as to penetrate the coating 57 and the cover 12b, so that the lighting / extinguishing state associated with the on / off of the main switch 64 can be visually recognized from the outside of the lid body 12. It is like that.

  In FIG. 13, the electronic control unit 12 a is connected to the electric power of the battery 60 through the input connector 55, the output signal of the speed setting device 61 for setting the desired speed of the engine E, and the speed for detecting the speed of the engine E The output signal of the number sensor 62, the output signal of the temperature sensor 63 that detects the temperature of the engine E, and the like are input. A main switch 64 is provided in the energization circuit between the battery 60 and the input connector 55.

  On the other hand, an internal connector 67 (see FIG. 6) connected to the current-carrying wire harnesses 65 and 66 of the first and second electric motors 20 and 21 is coupled to the output connector 56.

  Next, the operation of this embodiment will be described.

  In the electronic control unit 12a, when the main switch 64 is turned on, first, the first electric motor 20 is operated based on the output signal of the temperature sensor 63 by the electric power of the battery 60, and the first transmission device 24 is used. The choke valve 7 is driven to the starting opening corresponding to the engine temperature at that time. For example, when the engine E is cold, the choke valve 7 is driven to the fully closed position as shown in FIG. 9, and when hot, the engine E is held at the fully opened position as shown in FIG. Since the starting opening of the choke valve 7 is controlled in this way, if the recoil starter 5 is operated and cranked in order to start the engine E, the intake passage 6 of the carburetor C is started at that time. An air-fuel mixture having a suitable concentration is generated, and the engine E can always be started easily.

  Immediately after starting in the cold state, excessive intake negative pressure of the engine E acts on the choke valve 7 in the fully closed state. Then, as described above, the difference between the rotational moment due to the intake negative pressure acting on the side with the larger rotation radius of the choke valve 7 and the rotational moment due to the intake negative pressure acting on the side with the smaller rotation radius of the choke valve 7 is the relief spring. Since the choke valve 7 is automatically opened (see FIG. 11) regardless of the operation of the first electric motor 20 until it balances with the rotational moment by 31, the excessive intake negative pressure is eliminated, and the air-fuel mixture thereby Over-concentration can be prevented, and a good warm-up operation state of the engine E is ensured.

  By the way, the relief mechanism 33 including the relief lever 30 and the relief spring 31 is arranged offset from the output shaft 20a of the first electric motor 20 and the choke valve shaft 7a. The transmission chamber 14 that accommodates the first transmission device 24 is flattened while the relief mechanism 33 is interposed in the first transmission device 24 without being placed on the output shaft 20a or the choke valve shaft 7a. This can contribute to making the casing 10 compact.

  If the engine temperature rises due to the progress of the warm-up operation, the first electric motor 20 is operated based on the output signal of the temperature sensor 63 that changes accordingly, and the choke valve 7 is opened via the first transmission device 24. At the end of the warm-up operation, the choke valve 7 is fully opened (see FIG. 10), and this state is maintained during the subsequent operation.

  On the other hand, the second electric motor 21 operates based on the output signals of the rotational speed setter 61 and the rotational speed sensor 62, and the throttle valve 8 is connected via the second transmission device 25, and the engine rotational speed is the rotational speed setter 61. The amount of air-fuel mixture supplied from the carburetor C to the engine E is adjusted by controlling the opening and closing so as to coincide with the desired rotational speed set in step. That is, when the engine speed detected by the speed sensor 62 is lower than the desired speed set by the speed setting device 61, the opening of the throttle valve 8 is increased, and when the engine speed is higher than the desired speed, the throttle valve 8 is increased. By reducing the opening of the engine, the engine speed can be automatically controlled to the desired speed regardless of load fluctuations. Therefore, various working machines can be driven at a stable speed regardless of load fluctuations by the power of the engine E.

  The operation of the engine E can be stopped by turning off the main switch 64 and operating a kill switch (not shown) of the engine E. The engine E that has completed the predetermined work is normally in a hot state, and therefore, the choke valve 7 is held in the fully open state by the first electric motor 20. The fully open state of 7 is maintained. When the engine E is left in a cold region, an icing phenomenon in which water droplets condensed around the choke valve shaft 7a freeze and the choke valve 7 is stuck often occurs. Such a phenomenon generally makes it difficult to shift the choke valve 7 to the fully closed position at the next engine start.

  However, in the first transmission device 24, as described above, the connecting structure of the relief lever 30 and the choke lever 32 has a maximum lever ratio between the levers 30 and 32 in the fully open and fully closed positions of the choke valve 7, and the choke valve 7 Therefore, when the engine E is cold started, the first electric motor 20 moves in the closing direction of the choke valve 7 based on the output signal of the temperature sensor 63. When operating, the maximum torque is applied to the choke valve shaft 7a to crush the ice around the choke valve shaft 7a, so that the choke valve 7 can be driven from the fully open position to the fully closed position. The reliability of the auto choke function is guaranteed.

  In addition, the connecting structure of the relief lever 30 and the choke lever 32 can maximize the torque acting on the choke valve shaft 7a from the first electric motor 20 at least at the fully open position of the choke valve 7. By suppressing the increase in the number of reduction gears such as the first pinion 27 and the first sector gear 29, the first transmission device 24 can be made compact, and thus the transmission chamber 14 can be reduced in volume and the casing 10 can be made compact. obtain. Further, since it is not necessary to apply an excessive reduction ratio to the first pinion 27 and the first sector gear 29, there is no concern about a reduction in tooth root strength due to an excessive decrease in the modules of each gear.

  At the time of the cold start, if the stored amount of the battery 60 is insufficient, the first electric motor 20 does not operate and the choke valve 7 remains open as shown in FIG. Thus, at the time of starting, a rich mixture suitable for cold starting is not generated in the intake passage 6. In such a case, as shown in FIG. 12 (B), the operation lever 39 of the choke forced valve closing mechanism 37 is photographed and rotated against the urging force of the return spring 41. Then, the operating arm 40 that is connected to the operation lever 39 and faces the contact piece 30a of the relief lever 30 presses the corresponding contact piece 30a, so that the pressing force is transmitted from the relief lever 30 to the choke lever 32. Thus, the choke valve 7 is closed to the fully closed position, and if the engine E is started in this operating state, a rich mixture suitable for cold start is generated in the intake passage 6 to ensure cold start. .

  When the engine E is started, the function of the battery 60 is restored by the operation of the generator normally provided in the engine E, or the first electric motor 20 is normally operated by supplying power directly from the generator to the electronic control unit 12a. In operation, the choke valve 7 is controlled to an appropriate warm-up opening, so that the operating arm 40 needs to be returned to the non-operating position retracted from the relief valve 30 so as not to hinder the operation of the first electric motor 20. There is.

  Therefore, if the hand is released from the operating lever 39, the operating lever 39 and the operating arm 40 can be automatically returned to the non-operating position by the urging force of the return spring 41. An increase of 20 can be prevented.

  By the way, the operating arm 40 can press the contact piece 30a of the relief lever 30 only in the closing direction of the choke valve 7, and when it is held in the retracted position by the set load of the return spring 41, the relief arm 30 Simply facing the contact piece 30 a of the lever 30, the lever 30 is separated from the first transmission device 24. Therefore, when the choke valve 7 is driven by the normal first electric motor 20, the choke forced closing mechanism 37 does not become a load on the first transmission device 24 and avoids malfunction or breakage of the first transmission device 24 in advance. can do.

  In such an electronic control device D, a gap 70 that is opened to the atmosphere via the air passage 72 is provided between the electronic control unit 12a and the cover 12b constituting the lid 12 of the casing 10, so that the electronic control unit When the air between the electronic control unit 12a and the cover 12b expands and contracts due to heat generation and heat dissipation of 12a, and heating and cooling of the cover 12b due to temperature change of the engine E, the air gap 70 breathes and the electronic control is performed. It is possible to prevent excessive pressure from being applied to the unit 12a, and it is also possible to prevent condensation on the electronic control unit 12a due to the respiration. As a result, the durability of the electronic control unit 12a can be improved.

  Further, the air passage 72 for ensuring the respiration of the air gap 70 extends in a bowl shape from the air gap 70 and opens to the atmosphere with the outer end facing downward, so that it is difficult for rainwater or the like to enter the air gap 70 from the air passage 72. At the same time, if it enters, it can be easily discharged from the air passage 72.

  Further, the gap 70 is defined between the cover 12b and the electronic control unit 12a by forming a bulging portion 71 that bulges outward except for the peripheral edge portion thereof. While the support of the unit 12a is stabilized, the gap 70 having a constant thickness can be easily obtained. Therefore, the increase in size of the apparatus due to the gap 70 is negligible.

  Further, the upper wall of the carburetor C is provided with a vent hole 74 or 74 'that allows the bottom of the casing body 11 to communicate with the intake passage 6, so that the casing 10 has the first and second electric motors of the electronic control unit 12a. When the air in the casing 10 expands and contracts due to heat generation and heat dissipation of the motors 20 and 21 and heating and cooling of the casing 10 due to a temperature change of the engine E, the inside of the casing 10 breathes through the vent holes 74 or 74 '. Thus, it is possible to prevent excessive pressure from being applied to the electronic control unit 12a and the first and second electric motors 20, 21, and the respiration causes the electronic control unit 12a and the first and second electric motors to As a result, the electronic control unit 12a and the first and second electric motors 20 and 21 are improved in durability. It can be achieved. During the operation of the engine E, the intake negative pressure generated in the intake passage 6 is transmitted into the casing 10 through the vent holes 74 or 74 ', so that even if water drops due to condensation accumulate on the bottom of the casing 10, Can be drawn out to the intake passage 6.

As described above, it is advantageous to open the vent hole 74 or 74 ′ in the intake passage 6 instead of outside air because there is no fear of sucking outside dust during breathing inside the casing 10. Further, if a structure that opens to the intake passage 6 through the bearing hole 77 of the choke valve shaft 7a, such as the vent hole 74, is adopted, even if the vent hole 74 has a large diameter, the opening end of the bearing hole 77 Therefore, when the engine E blows back, the fuel that is contained in the blown-back gas slightly enters the air vent 74 when the engine E blows back. Therefore, it is relatively easy to drill the large-diameter ventilation hole 74.

  In addition, the large electronic components 51 to 53 of the electronic control unit 12a are arranged on one side of the drive chamber 15 so as to be close to the partition plate 16, and the thin electronic component 54 is arranged on the other side of the drive chamber 15, The first and second electric motors 20, 21 are arranged on the other side of the drive chamber 15 so as to be close to the substrate 50 and the thin electronic component 54, so that the first and second electric motors 20, 21 are large-sized. Since the electronic components 51 to 53 are arranged alternately, the first and second electric motors 20 and 21 and the large electronic components 51 to 53 can be efficiently accommodated in the drive chamber 15. Therefore, the dead space of the drive chamber 15 can be greatly reduced to reduce the capacity of the drive chamber 15, and the casing 10 can be reduced in size, and the entire engine E including the carburetor C with the electronic control unit D can be made compact. Can be planned.

  Moreover, in order to seal the substrate 50 on which the various electronic components 51 to 54 are mounted, the synthetic resin coating 57 that covers them has a substantially uniform thickness along the shape of the substrate 50 and the various electronic components 51 to 54. Therefore, there is no useless thickness portion, and therefore, the alternate arrangement of the first and second electric motors 20 and 21 and the large electronic components 51 to 53 is not hindered, and the casing 10 is made compact.

  Here, a method of forming the film 57 will be described with reference to FIG.

  A hot melt molding method is used to form the film 57. First, as shown in FIG. 16A, a fixed mold 80 and a movable mold 81 that are openable and closable are prepared, the movable mold 81 is opened, and various electronic components 51 to 51 are placed at fixed positions between the two molds 80 and 81. Next, the movable board 81 is closed with respect to the fixed mold 80. At this time, a cavity 82 having a uniform gap is formed between both molds 80 and 81 and the substrate 50 and various electronic components 51 to 54.

  Therefore, as shown in FIG. 16B, when hot melt melted by heating is injected and filled into the cavity 82 from the gate 83 of the fixed mold 80, a coating film 57 made of hot melt having a uniform thickness is formed on the substrate 50 and It can form on the surface of various electronic components 51-54.

  When the hot melt injected and filled into the cavity 82 is cooled and solidified from the two molds 80 and 81, the movable mold 81 is opened as shown in FIG. 12a can be taken out between both molds 80 and 81.

  Finally, a modified example of the ventilation structure inside the casing 10 will be described with reference to FIGS. 18 and 19.

  A flange portion 84 formed at the upstream end of the carburetor C is connected to a cylinder head 3a of the engine E by a connecting bolt 86 through an annular insulator 85 together with an intake duct 91 connected to an air cleaner (not shown). The intake passage 6 of the carburetor C communicates with the intake port 87 of the cylinder head 3 a through the hollow portion of the insulator 85. At that time, a gasket 88 is interposed between the insulator 85 and each of the flange portion 84 and the cylinder head 3a.

  A labyrinth 89 that opens to the atmosphere with the outer end facing downward is formed on one opposing surface of the flange portion 84 and the insulator 85 (the end surface on the flange portion 84 side in the illustrated example). A vent hole 90 is provided on the upper side wall of the vaporizer C.

  Thus, since the inside of the casing 10 communicates with the atmosphere through the vent hole 90 and the maze 89, it is possible to breathe through them. Moreover, the labyrinth 89 that opens downward at the outer end does not easily allow rainwater or dust to enter, and even if it enters, it can naturally flow down and be discharged to the outside.

  Since other configurations are the same as those of the previous embodiment, portions corresponding to those of the previous embodiment in FIG. 18 and FIG. 19 are denoted by the same reference numerals, and redundant description is omitted.

  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. For example, the labyrinth 89 can be formed on one joint surface of the carburetor C and the intake duct 91.

The front view of the general purpose engine which concerns on the Example of this invention. FIG. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 1. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a view taken in the direction of arrow 5 in FIG. 4 (a plan view of the electronic control unit). The top view shown in the state which removed the cover body of the said electronic control apparatus. The top view shown in the state which removed the cover body and the partition board of the same electronic control unit. FIG. 5 is a sectional view taken along line 5-5 of FIG. The top view (A) and front view (B) of the 1st transmission which control a choke valve in a fully closed state. The top view (A) and front view (B) of the 1st transmission which control a choke valve to a full open state. The top view (A) and front view (B) of the 1st transmission which show the operating state of a relief mechanism. FIG. The top view which shows the non-operation state (A) and operation state (B) of the choke forced valve closing mechanism in FIG. The top view of an electronic control unit. The diagram which shows the relationship between the choke valve opening and the lever ratio between the relief lever and the choke lever. FIG. 15 is a sectional view taken along line 15-15 in FIG. 5; Explanatory drawing of the film formation method to an electronic control unit. FIG. 17 is a sectional view taken along line 17-17 in FIG. 4; FIG. 18 is a view corresponding to FIG. 17 showing a modification of the ventilation structure in the casing. FIG. 19 is a cross-sectional view taken along line 19-19 of FIG.

Explanation of symbols

C ... Vaporizer D ... Electronic control unit 3a ... Adjacent member 6 of vaporizer ... Intake passage 7 ... Valve (choke valve)
8 ... Valve (Throttle valve)
10 .... casing 7a ... choke valve shaft 12a ... electronic control unit 12b ... cover 20 ... electric actuator (first electric motor)
21... Electric actuator (second electric motor)
24... Transmission device (first transmission device)
25... Transmission device (second transmission device)
74 ... ・ Ventilation means (vent hole)
74 '... Ventilation means (vent hole)
77... Bearing holes 89 and 92.

Claims (4)

A transmission device (24, 25) connected to a valve (7, 8) that opens and closes an intake passage (6) of the carburetor (C), and the valve (7, 8) via this transmission device (24, 25). In an electronic controller for a vaporizer, comprising: an electric actuator (20, 21) for opening and closing a motor) and an electronic control unit (12a) for controlling the operation of the electric actuator (20, 21).
The transmission (24, 25), the electric actuators (20, 21) and the electronic control unit (12a) are accommodated and held in the casing (12) attached to the vaporizer (C), and the casing (10) An electronic control device for a vaporizer, characterized in that ventilation means (74, 74 ', 89, 90) leading to the outside are connected to the bottom. The electronic control unit for a vaporizer according to claim 1,
The ventilation means is constituted by ventilation holes (74, 74 ') which are drilled in the carburetor (C) and communicate the bottom of the casing (10) with the intake passage (6) of the carburetor (C). An electronic control unit for vaporizers. The electronic control device for a vaporizer according to claim 2,
An electronic control device for a carburetor characterized in that an outer end of the vent hole (74) is opened in a bearing hole (77) of a carburetor (C) that supports a choke valve shaft (7a). The electronic control unit for a vaporizer according to claim 1,
At least a part of the ventilation means is constituted by a labyrinth (89) which is formed on the opposing surface of the vaporizer (C) and the adjacent member (3a) joined thereto and opens to the atmosphere with the outer end facing downward. An electronic control device for a vaporizer, characterized by that.

Images