JP4990837B2 - Control device for general-purpose internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a general-purpose internal combustion engine, and more particularly to a control device for a general-purpose internal combustion engine that performs a warm-up operation.

Conventionally, in general-purpose internal combustion engines that are used as drive sources in various applications such as generators and agricultural machines, warm-up operation is performed after startup to stabilize the engine speed, and stall due to sudden opening and closing of the throttle valve It is well practiced to prevent such problems, and examples thereof include the technique described in Patent Document 1 below. In the technique described in Patent Document 1, until the temperature of the engine reaches a predetermined value after the internal combustion engine is started, in other words, an operation state (completely warm-up state) in which it is possible to reliably prevent the occurrence of a stall or the like is achieved. Until this time, the warm-up operation is performed by increasing the amount of fuel supplied (fuel amount).
Japanese Patent Laid-Open No. 5-59992 (paragraphs 0035, 0036, 0042 to 0044, FIGS. 10, 15 etc.)

  However, as in the technique described in Patent Document 1, if the amount of fuel is increased until the engine is completely warmed up, stall can be reliably prevented, but the fuel consumption performance is deteriorated and the emission performance is also decreased by the increase in fuel. The problem that occurs. Therefore, it has been desired to end the warm-up operation performed by increasing the fuel amount as early as possible.

  Accordingly, the object of the present invention is to solve the above-mentioned problems, prevent the internal combustion engine from stalling at the start, and end the warm-up operation performed by increasing the fuel amount as early as possible, thereby improving the fuel efficiency performance. It is an object of the present invention to provide a control device for a general-purpose internal combustion engine that improves emission performance.

In order to solve the above-mentioned object, in claim 1, in a control device for a general-purpose internal combustion engine comprising a throttle valve disposed in an intake passage and an actuator for driving the throttle valve, the temperature of the internal combustion engine Temperature detecting means for detecting engine speed, engine speed detecting means for detecting the engine speed of the internal combustion engine, and first warm-up from when the internal combustion engine is started until the detected engine speed is stabilized time, the is from rather long set the first warm-up time, determine the warm-up is determined based on a second warm-up time to the internal combustion engine is fully warmed-up state with the detected temperature time Means, time measuring means for measuring an elapsed time since the internal combustion engine was started, and fuel supplied to the internal combustion engine until the measured elapsed time exceeds the determined first warm-up time Increase quantity A fuel amount increasing means for reducing the throttle opening of the throttle valve from the time when the elapsed time exceeds the first warm-up time to the time when the determined second warm-up time is exceeded. And an actuator control means for controlling the operation of the actuator.

In the control apparatus for a general-purpose engine according to claim 2, which is the detected from the elapsed time before Symbol measured beyond the first warm-up time before exceeding the second warm-up time when the engine speed does not reach a predetermined value, and configured with a shutdown hands stage for stopping the operation of the internal combustion engine.

In the control apparatus for a general-purpose internal combustion engine according to claim 1, the first warm-up time until the detected engine speed is stabilized after the internal combustion engine is started, and longer than the first warm-up time. And a second warm-up time until the internal combustion engine is completely warmed up is determined based on the detected temperature, and an elapsed time from the start of the internal combustion engine is determined as the first warm-up time. Since the fuel amount supplied to the internal combustion engine is increased until the engine time is exceeded, for example, the first warm-up time is set to the time until the engine speed is stabilized, and the second warm-up time is completely set. By setting the time until the warm-up state is reached, the increase in the fuel amount can be completed in a first warm-up time shorter than the second warm-up time when the warm-up state is reached. As a result, the warm-up operation performed by increasing the fuel amount can be terminated at an early stage, and thus the fuel efficiency performance and emission performance can be improved accordingly. In addition, the operation of the actuator is controlled so that the change speed of the throttle opening of the throttle valve decreases from the elapsed time exceeding the first warm-up time until exceeding the second warm-up time. Therefore, the throttle valve is not suddenly opened and closed until the engine is completely warmed up, and a sudden change in the air-fuel ratio can be avoided, so that the stall of the internal combustion engine can be reliably prevented. Furthermore, it is possible to reduce the fouling of the combustion chamber, spark plug, and lubricating oil accompanying the increase in the amount of fuel.

  In the control device for a general-purpose internal combustion engine according to claim 2, the elapsed time from the start of the internal combustion engine exceeds the first warm-up time and before the second warm-up time is exceeded. Since it is configured to stop the operation when the engine speed does not reach the predetermined value, in addition to the above effect, for example, when it is estimated that some abnormality occurs in the internal combustion engine and the engine speed does not increase, The operation of the internal combustion engine can be stopped reliably.

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

  FIG. 1 is an overall view showing a control apparatus for a general-purpose internal combustion engine according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a general-purpose internal combustion engine (hereinafter referred to as “engine”). The engine 10 is an air-cooled four-cycle single-cylinder OHV engine (displacement is 440 cc, for example), and is used as a drive source in various applications such as a generator and an agricultural machine.

  The engine 10 includes a single cylinder (cylinder) 12, and a piston 14 is accommodated therein so as to be capable of reciprocating. An intake valve 20 and an exhaust valve 22 are disposed at a position facing the combustion chamber 16 of the engine 10, and opens and closes between the combustion chamber 16 and the intake port 24 or the exhaust port 26. Further, a temperature sensor (temperature detection means) 28 is disposed in the vicinity of the cylinder 12 and generates an output indicating the temperature of the engine 10.

  The piston 14 is connected to the crankshaft 30, and the crankshaft 30 is connected to the camshaft 32. The crankshaft 30 and the camshaft 32 are accommodated in a crankcase 34 attached to the lower part of the cylinder 12. The lower part of the crankcase 34 constitutes an oil pan that receives oil (lubricating oil).

  A load (not shown) such as a generator is connected to one end of the crankshaft 30, while a flywheel 36 is attached to the other end. A plurality of permanent magnets 38 are arranged inside the flywheel 36, and a power coil (power generation coil) 40 faces the permanent magnet 38 on the outside so as to face the permanent magnet 38 inside the flywheel 36. Thus, the pulsar coil 42 is installed. The power coil 40 outputs an alternating current having a frequency corresponding to the number of rotations of the crankshaft 30, and the pulsar coil 42 outputs a pulse signal at every predetermined crank angle. In addition, a recoil starter 44 that starts the engine 10 by an operator's manual operation is attached to the crankshaft 30.

  A carburetor 46 is connected to the intake port 24.

  FIG. 2 is an enlarged cross-sectional view of the carburetor 46 shown in FIG.

  As shown in FIG. 2, the carburetor 46 integrally includes an intake passage 50, a motor case 52, and a carburetor assembly 54. The intake passage 50 has a downstream side connected to the intake port 24 via an insulator 56 and an upstream side connected to an air cleaner (not shown) via an air cleaner elbow 58. A throttle valve 60 is disposed in the intake passage 50, and a choke valve 62 is disposed upstream of the throttle valve 60 in the intake passage 50. Further, the intake passage 50 is reduced in diameter between the throttle valve 60 and the choke valve 62 to form a venturi 64.

  A cover 66 is attached to the motor case 52, and an electric motor (actuator) 70 that drives the throttle valve 60 and the choke valve 62 is disposed in an internal space formed by the motor case 52 and the cover 66. The electric motor 70 is specifically a stepping motor and includes a stator and a rotor around which coils are wound. The electric motor 70 is connected to the throttle valve 60 via a throttle valve opening / closing mechanism (gear mechanism) 72.

  FIG. 3 is a plan view of the carburetor 46 shown in FIG. 2 with the cover 66 of the motor case 52 removed. FIG. 3 shows a state in which the throttle valve 60 is in the fully closed position and the choke valve 62 is in the fully open position, as indicated by an imaginary line.

  As shown in FIGS. 2 and 3, the throttle valve opening / closing mechanism 72 includes four gears. Specifically, a first gear 74 is attached to the output shaft 70 </ b> S of the electric motor 70, and the first gear 74 is meshed with a second gear 76 that is rotatably supported inside the motor case 52. The A third gear (eccentric gear) 78 that rotates integrally with the second gear 76 is attached coaxially with the second gear 76. As can be seen from FIG. 3, the teeth of the third gear 78 are formed only on a part of the outer periphery of the third gear 78 (part connected to a fourth gear (described later)).

  The third gear 78 meshes with a fourth gear (eccentric gear) 82 attached to a throttle shaft 80 that supports the throttle valve 60. As a result, the output of the electric motor 70 is transmitted to the throttle shaft 80 while being decelerated in accordance with the gear ratio of the gears 74, 76, 78, 82, thereby opening and closing the throttle valve 60. One of the characteristic features of the throttle valve opening / closing mechanism 72 according to this embodiment is that the throttle valve 60 is opened / closed between a fully closed position and a position where the fully opened position exceeds a predetermined opening according to the operation of the electric motor 70, That is, the throttle valve 60 is opened and closed from the fully opened position to a position exceeding a predetermined opening in the valve opening direction, which will be described later.

  A return spring 84 (shown in FIG. 2) made of a torsion coil spring is disposed on the outer periphery of the throttle shaft 80. One end of the return spring 84 is connected to the fourth gear 82, and the other end is connected to a hook pin 86 (shown in FIG. 2) that projects from the motor case 52. Note that the winding direction of the return spring 84 is set to a direction in which the throttle valve 60 is opened via the throttle shaft 80.

  A choke valve 62 is connected to the throttle valve opening / closing mechanism 72 configured as described above via a choke valve opening / closing mechanism 90. The choke valve opening / closing mechanism 90 is attached to a choke shaft 92 that supports the choke valve 62 and rotates the choke shaft 92. The arm 94 and the throttle valve opening / closing mechanism 72 (more precisely, the throttle valve opening / closing mechanism 72 It consists of a link 96 connecting the third gear 78).

  The link 96 is supported inside the motor case 52 so as to be rotatable about the rotation shaft 100. In the link 96, an end 96a on the arm 94 side is provided with a first pin 96b extending upward in FIG. The first pin 96 b is inserted through a long hole 94 a formed in the arm 94.

  A second pin 96d protrudes upward in FIG. 2 at the end 96c of the link 96 on the third gear 78 side. The second pin 96d is brought into contact with a portion where teeth are not formed on the outer periphery of the third gear 78. The portion where the teeth are not formed on the outer periphery of the third gear 78 (that is, the portion where the second pin 96d abuts) has a substantially disc shape and includes a concave portion. Hereinafter, a concave portion formed on the outer periphery of the third gear 78 is referred to as a “first contact portion” and is denoted by reference numeral 78a. Further, the remaining portion (substantially disk-shaped portion) other than the first contact portion 78a in the portion where the outer peripheral teeth of the third gear 78 are not formed is referred to as a “second contact portion”, which is denoted by reference numeral 78b. Show. The positions where the first and second contact portions 78a and 78b are formed on the outer periphery of the third gear 78 will be described later.

  On the outer periphery of the choke shaft 92, a return spring 102 made of a torsion coil spring is disposed as shown in FIG. One end of the return spring 102 is connected to the arm 94, and the other end is connected to a hook pin 104 protruding inside the motor case 52. The winding direction of the return spring 102 is set to a direction in which the choke valve 62 is closed via the choke shaft 92.

  The choke valve opening / closing mechanism 90 is configured to include the return spring 102 that urges the choke valve 62 in the valve closing direction (fully closed position), so that the urging force is transmitted to the link 96 via the arm 94. Is done. Accordingly, a counterclockwise force acts on the link 96 around the rotation shaft 100, so that the second pin 96 d of the link 96 is connected to the outer peripheral surface of the third gear 78 (specifically, the first or the second 2 abutting portions 78a and 78b), while being always pressed (pressed).

  Returning to the description of FIG. 1, the carburetor assembly 54 is connected to a fuel tank (not shown) and receives fuel supply, and injects an amount of fuel corresponding to the opening of the throttle valve 60 to generate an air-fuel mixture. Further, when the choke valve 62 is closed, the negative pressure in the intake passage 50 caused by the lowering of the piston 14 increases, so the amount of fuel injected from the carburetor assembly 54 increases and the air-fuel ratio is enriched. .

  The air-fuel mixture generated as described above is sucked into the combustion chamber 16 through the intake port 24 and the intake valve 20. The air-fuel mixture sucked into the combustion chamber 16 is ignited and burned by a spark plug (not shown), and the generated combustion gas (exhaust gas) passes through the exhaust valve 22, the exhaust port 26, a silencer (not shown), and the like. Is discharged outside.

  A rotation speed setting volume 110 and an engine stop switch 112 are arranged at positions that can be operated by the operator. The rotation speed setting volume 110 generates an output indicating the target engine rotation speed NED according to the operation of the operator. The engine stop switch 112 outputs an ON signal when an engine stop instruction is input from the operator (when operated).

  The outputs of the temperature sensor 28, the power coil 40, the pulsar coil 42, the rotation speed setting volume 110, and the engine stop switch 112 described above are input to an ECU (Electronic Control Unit) 114. The ECU 114 is composed of a microcomputer including a CPU, ROM, RAM, an input / output circuit, and the like.

  The output (AC current) of the power coil 40 input to the ECU 114 is input to a bridge circuit (not shown) provided in the ECU 114, where it is converted into DC current by full-wave rectification. This direct current is supplied to each part of the engine 10 as an operating current. The output of the power coil 40 is also input to a pulse generation circuit (NE detection circuit, not shown) provided in the ECU 114 and converted into a pulse signal. Since the frequency of the alternating current generated by the power coil 40 is proportional to the rotational speed of the crankshaft 30, the engine rotational speed NE can be detected based on the pulse signal obtained from the output of the power coil 40.

  Further, the ECU 114 ignites the spark plug at a timing according to the engine speed based on the output (pulse signal) of the pulsar coil 42. Further, the ECU 114 determines the target opening of the throttle valve 60 and the choke valve 62 based on the output of the temperature sensor 28 and the rotation speed setting volume 110, the detected engine speed NE, and the like, and responds to the determined target opening. The control signal is output to a motor driver (not shown) to operate the electric motor 70, and the valves 60 and 62 are opened and closed to adjust the engine speed NE and the amount of fuel supplied to the engine 10.

  Next, the opening / closing operation of the throttle valve 60 and the choke valve 62 will be described with reference to FIG. 3 and FIG. 4 and thereafter, focusing on the operations of the electric motor 70, the throttle valve opening / closing mechanism 72, and the choke valve opening / closing mechanism 90.

  FIG. 4 is an explanatory diagram showing the characteristics of the opening / closing operation of the throttle valve 60 and the choke valve 62.

  When the throttle valve 60 is in the fully closed position, the electric motor 70 rotates the throttle shaft 80 via the first to fourth gears 74, 76, 78, 82 of the throttle valve opening / closing mechanism 72, and the throttle valve 60. Is closed to the fully closed position shown in FIG. 3 and FIG. At this time, as can be seen from FIG. 3, the second pin 96d of the link 96 is in contact with the second contact portion 78b of the third gear 78, and the choke valve 62 is in the fully open position.

  When the throttle valve 60 is opened from the fully closed position to the fully opened position, the electric motor 70 rotates the first to fourth gears 74, 76, 78, and 82 in the directions indicated by the arrows in FIG. The throttle shaft 80 is rotated counterclockwise, and the throttle valve 60 is opened to the fully open position. At this time, the second pin 96d slides to the vicinity of the first contact portion 78a, but is still in contact with the second contact portion 78b, and therefore also shown in FIG. Thus, the choke valve 62 is held in the fully open position. Thus, the choke valve opening / closing mechanism 90 holds the choke valve 62 in the fully open position when the throttle valve 60 is between the fully closed position and the fully open position.

  Further, when the choke valve 62 is closed to enrich the air-fuel ratio, such as when the engine 10 is started (during a warm-up operation described later), the electric motor 70 operates the throttle valve opening / closing mechanism 72 and linked to it. The choke valve 62 is opened and closed by rotating the choke shaft 92 by displacing 96. Specifically, the electric motor 70 rotates the gears 74, 76, 78, and 82 in the directions indicated by the arrows in FIG. 6 to further rotate the throttle shaft 80 counterclockwise to fully open the throttle valve 60. The valve is opened to a position exceeding the predetermined opening degree α (hereinafter referred to as “over fully open position”).

  At this time, the second pin 96d slides to the first contact portion 78a by the rotation of the third gear 78. Thereby, the link 96 is displaced counterclockwise around the rotation shaft 100, and the first pin 96b displaces the arm 94 while sliding in the long hole 94a. Due to the displacement of the arm 94, the choke shaft 92 is rotated clockwise in the figure, so that the choke valve 62 is closed to the fully closed position as shown in FIG.

  As described above, the positions at which the first and second contact portions 78a and 78b are formed in the third gear 78 are determined when the second pin 96d contacts the second contact portion 78b, that is, 3 or 5, the choke valve 62 is in the fully open position, the third gear 78 is rotated clockwise in the figure by the electric motor 70, and the second pin 96 d is in the first contact position. When contacting the contact portion 78a (in the state shown in FIG. 6), the choke valve 62 is set to the fully closed position.

  4 and (a) to (c) of FIG. 4, the choke valve opening / closing mechanism 90 opens and closes the choke valve 62 in conjunction with the operation of the throttle valve opening / closing mechanism 72. More specifically, the throttle valve When 60 is between the fully closed position and the fully open position, the choke valve 62 is held in the fully open position, while the throttle valve 60 is between the fully open position and the over fully open position (the position where the fully open position exceeds the predetermined opening α). In some cases, the choke valve 62 is configured to open and close between a fully open position and a fully closed position.

  In the above description, the operation of the choke valve 62 has been described in two types, the fully open position and the fully closed position. However, since the first contact portion 78a is formed in a concave shape, the second pin 96d and the first contact By appropriately adjusting the contact position with the contact portion 78a, the choke valve 62 can be set to an arbitrary opening degree. That is, the choke valve 62 can be freely opened and closed between the fully open position and the fully closed position by appropriately adjusting the throttle valve 60 between the fully open position and the over fully open position.

  Next, the opening / closing operation of the throttle valve 60 and the choke valve 62 when the engine 10 is started will be described.

  FIG. 7 is a flowchart showing the control of the operation of the throttle valve 60 and the like when the engine 10 is started, among the operations of the ECU 114. The illustrated program is executed only once when the engine 10 is started. Before the engine 10 is started, the throttle valve 60 and the choke valve 62 are in the state shown in FIGS. 6 and 4C. Specifically, the throttle valve 60 is set to the over fully open position by the urging force of the return spring 84. The choke valve 62 is fully closed by the return spring 102.

  Hereinafter, the opening / closing operation of the throttle valve 60 and the choke valve 62 will be described with reference to the flowchart of FIG. When the recoil starter 44 is operated by the operator and the power coil 40 starts generating power and the ECU 114 is activated, first, the temperature of the engine 10 is detected based on the output of the temperature sensor 28 in S10.

  Proceeding to S12, a first warm-up time T1 and a second warm-up time T2 for warming up the engine 10 are determined based on the detected temperature. The first warm-up time T1 means the time from when the engine 10 is started until the engine speed NE is stabilized, and the second warm-up time T2 is, for example, when the throttle valve 60 is suddenly opened and closed. In this case, it means a time until an operation state where no stall or the like occurs (that is, a complete warm-up state).

  Specifically, as shown in FIG. 8, a map obtained in advance by experiments and stored in the ROM is searched from the temperature of the engine 10, and first and second warm-up times T1, T2 are determined (calculated). ) In FIG. 8, the first warm-up time T1 is indicated by a broken line, and the second warm-up time T2 is indicated by a solid line.

  As can be seen from FIG. 8, the second warm-up time T2 is set to be longer than the first warm-up time T1. The first and second warm-up times T1, T2 are both set to decrease as the temperature of the engine 10 increases. This is because when the temperature of the engine 10 is relatively low, in other words, the outside air temperature is relatively low, and during cold start, it takes a long time to complete warm-up, while the temperature of the engine 10 This is because a short warm-up time is sufficient when the air temperature is high (when the outside air temperature is relatively high or when warm start (hot restart)).

  Next, the routine proceeds to S14, where the first warm-up time T1 determined is set in the first timer (down counter, time measuring means), and the routine proceeds to S16, where the second warm-up time T2 is set to the second timer (down). Set to the counter (time measuring means). Thus, the elapsed time after the engine 10 is started is measured using the first and second timers.

  Proceeding to S18, the amount of fuel supplied to the engine 10 is increased, and the warm-up operation is performed. Specifically, the operation of the electric motor 70 is controlled so that the throttle valve 60 is driven (opened / closed) between the over fully open position and the fully open position. By driving the throttle valve 60 as described above, the choke valve 62 is opened and closed between the fully closed position and the fully opened position, as shown in FIGS. As a result, the amount of fuel increases, the air-fuel ratio in the intake passage 50 is enriched, the engine 10 is warmed up, and its startability is also improved.

  Next, the process proceeds to S20 to determine whether or not the value of the first timer has become zero. When the result in S20 is negative, the program returns to S18 to continue the warm-up operation performed by increasing the amount of fuel described above. That is, the amount of fuel supplied to the engine 10 is increased until the elapsed time from the start of the engine 10 exceeds the first warm-up time T1.

  When the result in S20 is affirmative, the routine proceeds to S22, where the increase in the fuel amount is finished, specifically, the warm-up operation performed by increasing the fuel amount is finished. Specifically, the operation of the electric motor 70 is controlled so that the throttle valve 60 that has been driven between the fully open position and the fully open position is driven to the fully open position. By driving the throttle valve 60 to the fully opened position, as shown in FIG. 4B, the choke valve 62 is held at the fully opened position, and thus the increase in the fuel amount by the choke valve 62 is terminated.

  Next, the routine proceeds to S24, where the speed of change of the throttle opening of the throttle valve 60 (the amount of change of the throttle opening per unit time) is decreased, and the throttle valve 60 is driven between the fully closed position and the fully opened position in that state. Thus, to be precise, the operation of the electric motor 70 is controlled so that the throttle valve 60 reaches the target opening degree in order to maintain the target engine speed NED input by the speed setting volume 110.

  Specifically, the reduction of the throttle opening change speed is performed by reducing the driving speed (rotational speed) of the electric motor 70, for example, by reducing the driving speed to 100 pps when the normal driving speed is 300 pps.

  Moreover, the change rate of the throttle opening degree is also reduced by gradually changing the target engine speed NED. This will be described with reference to FIG. 9. For example, the target engine speed is changed from the first target engine speed NED1 to the second target engine speed NED2 by operating the speed setting volume 110 at time t1. In this case, the target engine speed NED in the ECU 114 is not immediately changed to the second target engine speed NED2 (indicated by a one-dot chain line in FIG. 9), but from the first target engine speed NED1 to the second target engine speed NED1. It gradually increased (changed) toward the number NED2. That is, as the target engine speed NED increases stepwise, the throttle opening of the throttle valve 60 gradually increases accordingly, and thus the change rate of the throttle opening is reduced. In the above description, the case where the target engine speed NED is increased has been described as an example. Similarly, when the target engine speed NED is decreased, the target engine speed NED is gradually decreased.

  Next, the process proceeds to S26, where the engine speed NE is detected. The process proceeds to S28, where it is determined whether or not the detected engine speed NE is equal to or less than a predetermined value (for example, 1300 rpm). Affirmative in S28, that is, when the engine speed NE does not reach the predetermined value before the second warm-up time T2 after the elapsed time from the start of the engine 10 exceeds the first warm-up time T1 Since it is presumed that some abnormality has occurred in the engine 10, the process proceeds to S30, the ignition is cut, etc. to stop the operation of the engine 10, and the program is terminated.

  When the result in S28 is negative, the program proceeds to S32, in which it is determined whether or not the value of the second timer has become zero. When the result in S32 is negative, the program returns to S24 and repeats the above processing. In this way, the change speed of the throttle opening of the throttle valve 60 decreases from the time when the engine 10 has been started exceeds the first warm-up time T1 to the second warm-up time T2. Thus, the operation of the electric motor 70 is controlled.

  On the other hand, when the result in S32 is affirmative, that is, when the engine 10 is completely warmed up and the warm-up operation is finished, the process proceeds to S34, and the throttle valve 60 is normally controlled. Specifically, the drive speed of the electric motor 70 is set to a normal value (for example, 300 pps), and the target engine speed NED in the ECU 114 is made to correspond to the output from the speed setting volume 110, and in this state, the throttle valve The operation of the electric motor 70 is controlled so that the motor 60 is driven between the fully closed position and the fully opened position (more precisely, the throttle valve 60 has a target opening degree so as to maintain the target engine speed NED). .

  Next, the opening / closing operation of the throttle valve 60 and the choke valve 62 when the engine 10 is stopped will be described.

  FIG. 10 is a flowchart showing control of the operation of the throttle valve 60 when the engine 10 is stopped, among the operations of the ECU 114. The illustrated program is executed in the ECU 114 at predetermined intervals (for example, 100 msec).

  First, in S100, it is determined whether or not a stop instruction for the engine 10 has been input, specifically, whether or not the engine stop switch 112 has been operated by the operator to output an ON signal. When the result in S100 is negative, the subsequent processing is skipped, while when the result is positive, the process proceeds to S102 to control the operation of the electric motor 70 so that the throttle valve 60 is driven (opened) to the over fully open position. By driving the throttle valve 60 as described above, the choke valve 62 is closed to the fully closed position as shown in FIG.

As described above, according to the embodiment of the present invention, the control of the general-purpose internal combustion engine (engine) 10 including the throttle valve 60 disposed in the intake passage 50 and the actuator (electric motor) 70 for driving the throttle valve. In the apparatus, temperature detecting means (temperature sensor 28, ECU 114. S10) for detecting the temperature of the internal combustion engine and engine speed detecting means (ECU 114. S26) for detecting the engine speed (engine speed NE) of the internal combustion engine. and), the first warm-up time T1 from the internal combustion engine is started until the detected engine speed is stabilized, is from rather long setting the first warm-up time, the internal combustion engine is completely A warm- up time determining means (ECU 114.S12) for determining a second warm-up time T2 until the warm-up state is reached based on the detected temperature ; and the internal combustion engine Time measuring means (first timer, second timer, ECU 114, S14, S16) for measuring the elapsed time since the start of the function, and the determined first warm-up time Fuel amount increasing means (ECU 114, S18, S20) for increasing the amount of fuel supplied to the internal combustion engine until the time exceeds, and the second time determined after the elapsed time exceeds the first warm-up time. Actuator control means (ECU 114. S24, S32) for controlling the operation of the actuator so that the change rate of the throttle opening of the throttle valve is decreased until the warm-up time of is exceeded.

  As described above, since the amount of fuel supplied to the engine 10 is increased until the elapsed time from the start of the engine 10 exceeds the first warm-up time T1, the first warm-up time T1 is set. Is set to the time until the engine speed NE is stabilized, and the second warm-up time T2 is set to the time until the complete warm-up state, thereby increasing the fuel amount to the second warm-up state. It can be terminated at a first warm-up time T1 that is shorter than the warm-up time T2. As a result, the warm-up operation performed by increasing the fuel amount can be terminated at an early stage, and thus the fuel efficiency performance and emission performance can be improved accordingly. Further, the operation of the electric motor 70 is controlled so that the change rate of the throttle opening of the throttle valve 60 decreases from the elapsed time exceeding the first warm-up time T1 to the second warm-up time T2. Thus, the throttle valve 60 is not suddenly opened and closed until the engine is completely warmed up, so that a sudden change in the air-fuel ratio can be avoided, and the stall of the engine 10 can be reliably prevented. it can. Furthermore, it is possible to reduce the fouling of the combustion chamber 16, spark plugs, lubricating oil and the like accompanying the increase in the fuel amount.

Further, when the detected engine speed NE before the elapsed time before Symbol measure exceeds the second warm-up time T2 from beyond said first warm-up time T1 has not reached the predetermined value, Operation stop means (ECU 114. S28, S30 ) for stopping the operation of the internal combustion engine is provided. Thereby, for example, when it is estimated that some abnormality occurs in the engine 10 and the engine speed NE does not increase, the operation of the engine 10 can be stopped reliably.

  In the above description, while the drive speed of the electric motor 70 is decreased and the target engine speed NED is gradually changed, the change speed of the throttle opening of the throttle valve 60 is decreased. It may be configured to reduce the change rate of the throttle opening only.

  Further, the actuator (electric motor 70) that drives the throttle valve 60 and the like is a stepping motor, but other electric motors, electromagnetic solenoids, etc. may be used, and hydraulic equipment that operates by driving a pump with an electric motor, etc. It may be.

  Further, the fuel is supplied by the carburetor 46, but the present invention is not limited to this, and an injector (fuel injection valve) may be arranged in the intake port 24 to supply the fuel.

1 is an overall view showing a control device for a general-purpose internal combustion engine (engine) according to an embodiment of the present invention. It is an expanded sectional view of the carburetor shown in FIG. It is a top view which shows the state which removed the cover of the motor case of the carburetor shown in FIG. It is explanatory drawing which shows the characteristic of the opening / closing operation | movement of the throttle valve and choke valve shown in FIG. It is a top view of the carburetor similar to FIG. It is a top view of the carburetor similar to FIG. 2 is a flow chart showing control of operations of a throttle valve and the like at the time of starting a general-purpose internal combustion engine (engine) among the operations of the electronic control unit shown in FIG. It is a graph which shows the table characteristic of the 1st, 2nd warming-up time with respect to the temperature of a general purpose internal combustion engine (engine) used by the process of FIG. Similarly, it is a time chart showing the change of the target engine speed with respect to the output of the speed setting volume used in the processing of FIG. 2 is a flowchart showing control of the operation of a throttle valve when the general-purpose internal combustion engine (engine) is stopped, among the operations of the electronic control unit shown in FIG. 1.

Explanation of symbols

  10 engine (general-purpose internal combustion engine), 28 temperature sensor (temperature detection means), 50 intake passage, 60 throttle valve, 70 electric motor (actuator), 114 ECU (electronic control unit)

Claims (2)

In a control device for a general-purpose internal combustion engine comprising a throttle valve disposed in an intake passage and an actuator for driving the throttle valve,
a. Temperature detecting means for detecting the temperature of the internal combustion engine;
b. Engine speed detecting means for detecting the engine speed of the internal combustion engine;
c. Said first warm-up time from the internal combustion engine is started until the detected engine speed is stabilized, the are from rather long set the first warm-up time, the internal combustion engine is fully warmed-up state a warm-up time determination means for determining based on to the second and warm-up time becomes the detected temperature,
d . Time measuring means for measuring an elapsed time since the internal combustion engine was started;
e . Fuel amount increasing means for increasing the amount of fuel supplied to the internal combustion engine until the measured elapsed time exceeds the determined first warm-up time;
f . The operation of the actuator is performed so that the change rate of the throttle opening of the throttle valve decreases from the elapsed time exceeding the first warm-up time to the determined second warm-up time. Actuator control means for controlling;
A control apparatus for a general-purpose internal combustion engine, comprising: g . When the detected engine speed does not reach a predetermined value after the measured elapsed time exceeds the first warm-up time and before the second warm-up time, the internal combustion engine is operated. control apparatus for a general-purpose engine according to claim 1, characterized in that it comprises the operation stop hand stage to stop.

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