JP5443306B2 - General-purpose engine control device - Google Patents

Description

  The present invention relates to a general-purpose engine control device, and more particularly to a device that controls warm-up operation of a general-purpose engine.

  2. Description of the Related Art Conventionally, in an engine control device, a technology has been proposed in which the fuel injection amount is increased and corrected by a warm-up correction coefficient calculated based on the temperature of lubricating oil (oil) during warm-up (for example, a patent) Reference 1).

JP 2004-285834 A (paragraphs 0042 to 0046, FIG. 6 and the like)

  However, since a certain amount of time is required until the temperature increase of the engine due to the warm-up operation is transmitted to the lubricating oil, when the fuel injection amount is configured to be increased and corrected using the lubricating oil temperature as described above, The warm-up state of the engine is not immediately reflected in the increase correction, so the fuel injection amount suitable for the warm-up state is not calculated, and as a result, the warm-up operation is performed longer than necessary and the fuel consumption increases. There was a risk of malfunction.

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to use a parameter in place of the lubricating oil temperature to calculate an appropriate fuel injection amount according to the warm-up state of the engine. Is to provide.

In order to solve the above-described problems, the present invention is based on the basis of the throttle opening degree of the throttle valve and the engine speed arranged in the intake pipe of a general-purpose engine that can be used as a power source of the work machine. Basic injection amount calculation means for calculating the injection amount, spark plug seat temperature change amount detection means for detecting the temperature change amount of the spark plug seat of the general-purpose engine, and engine temperature detection for detecting the temperature of the cylinder head of the general-purpose engine means and, calculates the warm-up correction factor based on the temperature of the temperature change amount of the detected spark plug seat and the cylinder head, with the calculated warmup correction coefficient after startup of the general-purpose engine has been completed together and a warm-up control execution means for executing the warm-up control for injected from the injector to calculate the fuel injection amount at the time of warming-up by correcting the basic injection amount The warm-up correction coefficient was constructed as calculated to decrease by a predetermined value which is calculated on the basis of the initial value is calculated based on the temperature of the cylinder head to the temperature change amount of the ignition plug seat.

In the general-purpose engine control apparatus according to claim 2 , the warm-up correction coefficient is calculated every time the general-purpose engine rotates a predetermined number of times or a predetermined time elapses.

In the control device for a general-purpose engine according to claim 3 , the warm-up correction coefficient includes a multiplication term of 1.0 or more, and is performed every time the general-purpose engine rotates a predetermined number of times or a predetermined time elapses. The warm-up control execution means is configured to execute the warm-up control until the warm-up correction coefficient reaches 1.0.

In the general-purpose engine control device according to claim 4 , the general-purpose engine includes an actuator that opens and closes the throttle valve so that the engine speed becomes a target speed set by an operator. Configured.

In the control device for a general-purpose engine according to claim 1, the basic injection amount is calculated based on the throttle opening and the engine speed of the general-purpose engine, and the temperature change amount of the spark plug seat of the general-purpose engine and the cylinder head It detects the temperature, the detected temperature variation and by correcting the basic injection amount based on the temperature of the cylinder head to calculate the fuel injection amount at the time of warm-up warm-up control for ejection from the injector of the spark plug seat In other words, instead of the temperature of the lubricating oil, based on the amount of change in the temperature of the spark plug seat disposed in the vicinity of the combustion chamber where the engine temperature rise due to the warm-up operation is easily reflected immediately. Since the fuel injection amount at the time of warm-up is calculated, an appropriate fuel injection amount corresponding to the warm-up state of the engine (specifically, the progress state of warm-up) can be calculated. Short Together it becomes possible to, it is possible to reduce fuel consumption.

  Even if the general-purpose engine is an air-cooled general-purpose engine whose warm-up state (specifically, the warm-up progress state) is likely to change depending on the outside air temperature, It is possible to calculate an appropriate fuel injection amount according to the above.

The warm-up control execution means calculates a warm-up correction coefficient based on the detected temperature change amount of the spark plug seat and the temperature of the cylinder head, and uses the warm-up correction coefficient after the start of the general-purpose engine is completed. Since the fuel injection amount during warm-up is calculated by correcting the basic injection amount, an appropriate fuel injection amount can be calculated from the warm-up correction coefficient corresponding to the warm-up state of the engine in addition to the effects described above. Therefore, the warm-up operation time can be further shortened, and the fuel consumption can be further reduced.

Further , the warm-up correction coefficient is configured to be calculated so as to decrease by a predetermined value calculated based on the amount of change in the temperature of the spark plug seat from the initial value calculated based on the temperature of the cylinder head. In addition to the effect described in the item 2, the warm-up correction coefficient can be gradually (stepwise) decreased as the engine warms up, so that an appropriate fuel injection amount corresponding to the warm-up state of the engine is calculated. can do.

In the general-purpose engine control apparatus according to claim 2 , the warm-up correction coefficient is calculated every time the general-purpose engine rotates a predetermined number of times or every predetermined time elapses. In addition to the effects described in 3 above, in other words, as the engine warms up, the warm-up correction coefficient can be reliably reduced with the passage of time, so that the fuel injection more suitable for the warm-up state of the engine The amount can be calculated.

In the general-purpose engine control apparatus according to claim 3 , the warm-up correction coefficient is a multiplication term having a value of 1.0 or more, and is turned to 1.0 every time the engine rotates a predetermined number of times or a predetermined time elapses. In addition to the effects described in claims 3 and 4, the warm-up correction coefficient is gradually decreased toward 1.0 as the engine warms up. Therefore, it is possible to calculate a fuel injection amount more suitable for the warm-up state of the engine.

  Further, since the warm-up control execution means is configured to execute the warm-up control until the warm-up correction coefficient reaches 1.0, the warm-up control is executed until the engine warm-up is completed (continue) ).

In the general-purpose engine control apparatus according to claim 4 , the general-purpose engine includes an actuator that opens and closes the throttle valve so that the engine speed becomes a target speed set by an operator. Since the configuration, specifically, the electronic governor is provided, in addition to the effects described above, the throttle opening can be calculated (detected) based on the command value for driving the actuator, thus eliminating the need for the throttle opening sensor. The fuel injection amount suitable for the warm-up state of the engine can be calculated with a simple configuration.

It is the schematic which shows the control apparatus of the general purpose engine which concerns on the Example of this invention generally. FIG. 2 is a block diagram mainly showing a configuration of an electronic control unit (ECU) shown in FIG. 1. It is a flowchart which shows the warm-up correction process of the fuel injection amount of the control apparatus shown in FIG. 3 is an explanatory diagram showing a map used in the processing of the flow chart. 3 is an explanatory diagram showing a map used in the processing of the flow chart. 3 is a graph showing a map used in the processing of the flow chart. 2 is a graph showing the relationship between the temperature of a spark plug seat and the load connected to the engine during the warm-up operation of the engine shown in FIG. 1. 3 is a graph for explaining the processing of the flow chart.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments for implementing a general-purpose engine control apparatus according to the invention will be described with reference to the accompanying drawings.

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

  In FIG. 1, the code | symbol 10 shows a general purpose engine (general purpose internal combustion engine). The engine 10 is an air-cooled four-cycle single-cylinder OHV type that uses gasoline as fuel, has a displacement of, for example, about 400 cc, and can be used (connected) as a power source for small industrial machines such as agriculture and construction Consists of institutions.

  A piston 14 is accommodated in a cylinder 12 formed inside the cylinder block 10a of the engine 10 so as to be capable of reciprocating. A cylinder head 10 b is attached to the cylinder block 10 a, and a combustion chamber 16 is formed between the top of the piston 14.

  An intake pipe 20 is connected to the combustion chamber 16. A throttle valve 22 is disposed in the intake pipe 20 and an injector 24 is disposed in the vicinity of the intake port downstream thereof. The injector 24 is connected to the fuel tank 30 via the fuel supply pipe 26.

  More specifically, the injector 24 is connected to the sub fuel tank 32 via the first fuel supply pipe 26a, and the sub fuel tank 32 is connected to the fuel tank 30 via the second fuel supply pipe 26b. The

  A low pressure pump 34 is inserted in the second fuel supply pipe 26 b to pump up fuel (gasoline) stored in the fuel tank 30 and pump it to the sub fuel tank 32. A fuel pump (high pressure pump) 36 is disposed in the sub fuel tank 32.

  The fuel pump 36 pressurizes the fuel that has been pumped and filtered by the filter 32a to a high pressure, and feeds the fuel to the injector 24 through the fuel supply pipe 26a while adjusting the pressure by the regulator 32b. Part of the fuel in the sub fuel tank 32 is returned to the fuel tank 30 through the return pipe 26c.

  The intake air drawn from the air cleaner (not shown) flows through the intake pipe 20, the flow rate is adjusted by the throttle valve 22, reaches the intake port, and mixes with the fuel injected from the injector 24 to form an air-fuel mixture.

  When the intake valve 40 is opened, the air-fuel mixture flows into the combustion chamber 16 and is ignited and burned by a spark plug 42 disposed in the vicinity of the combustion chamber 16 to drive the piston 14. When the exhaust valve 44 is opened, the exhaust gas generated by the combustion flows through the exhaust pipe 46 and is discharged to the outside.

  A crankcase (not shown) is attached to the cylinder block 10a on the side facing the cylinder head 10b, and a crankshaft 50 is rotatably accommodated therein. The crankshaft 50 is connected to the piston 14 via a connecting rod 14 a and rotates according to the driving of the piston 14.

  A camshaft (not shown) is rotatably accommodated in the crankcase in parallel with the crankshaft 50, and is connected to and driven by the crankshaft 50 via a gear mechanism (not shown). The camshaft includes an intake side cam and an exhaust side cam, and opens and closes the intake valve 40 and the exhaust valve 44 via a push rod and a rocker arm (not shown).

  A flywheel 52 is attached to the other end of the crankshaft 50. A pulsar coil (crank angle sensor) 54 is attached to the crankcase at a position outside the flywheel 52, and rotates relative to one magnet (permanent magnet piece, not shown) attached to the surface side of the flywheel 52. By intersecting with the magnetic flux, one output is generated per one rotation of the crankshaft 50 (per 360 degrees) at a predetermined crank angle near the top dead center.

  In addition, a power coil (power generation coil) 56 is attached to an inner position of the crankcase, and with relative rotation with eight magnets (permanent magnet pieces, not shown) attached to the back side of the flywheel 52. It functions as an ACG (alternating current generator) that generates an electromotive force by crossing with the magnetic flux of the magnet. The generated electromotive force is rectified and then supplied to a battery (not shown) to charge the battery.

  A load 60 such as a work machine is connected to one end of the crankshaft 50. Here, the load 60 means “the size of the mechanical equipment that consumes energy (output) from the prime mover or the power (work rate) consumed by the mechanical equipment”.

  An accelerator lever 62 that can be operated by an operator (user) is disposed at an appropriate position on a housing (not shown) of the engine 10. The accelerator lever 62 is a knob that can be pinched by the operator's finger and rotate within a range from a predetermined minimum engine speed to the maximum engine speed to indicate the target speed Nd intended by the operator.

  The throttle valve 22 is connected to an electric motor (actuator, more specifically, a stepping motor) 64. The electric motor 64 is configured to open and close the throttle valve 22 independently of the operator's operation of the accelerator lever 62. That is, the throttle valve 22 is configured as a Drive By Wire type.

  An intake temperature sensor 70 including a thermistor or the like is disposed upstream of the position where the throttle valve 22 is disposed in the intake pipe 20, and generates an output indicating the temperature of intake air flowing through that portion. In the cylinder block 10a, an engine temperature sensor 72 including a thermistor is disposed in the vicinity of the cylinder head 10b. The temperature of the part, that is, the temperature of the engine 10 (engine temperature. Produces an output indicating (temperature) T.

  A spark plug seat temperature sensor 73 is attached to a spark plug seat (seat surface portion) 42a that contacts the cylinder head 10b in the spark plug 42, and outputs a signal indicating the temperature Ta of the spark plug seat 42a.

  A variable resistor (potentiometer) 74 is connected to the accelerator lever 62 to generate an output indicating the target rotational speed Nd set by the operation of the accelerator lever 62 by the operator, and at an appropriate position on the housing of the engine 10. An operation switch 76 that can be operated by an operator (user) is arranged.

  The operation switch 76 generates an output indicating a driving instruction when operated (turned on) by the operator to an on position, and generates an output indicating a stop instruction when operated (turned off) by the operator.

  The outputs of these sensors 70, 72, 73, 74, the switch 76, the pulsar coil 54 and the power coil 56 are sent to an ECU (Electronic Control Unit) 80. The ECU 80 controls operations of the injector 24, the spark plug 42, the electric motor 64, and the like based on the output.

  FIG. 2 is a block diagram mainly showing the configuration of the ECU 80. The ECU 80 includes an engine speed detection block 80a, a governor control block 80b, a fuel injection amount calculation block 80c, and an ignition timing calculation block 80d.

  The engine speed detection block 80a counts the output of the pulsar coil 54 and detects the engine speed NE. The engine speed NE may be detected from the output of the power coil 56.

  The governor control block 80b determines the target rotational speed Nd of the engine 10 from the output of the variable resistor 74 according to the operation of the accelerator lever 62, and the engine rotational speed NE input from the engine rotational speed detection block 80a is the target rotational speed. The throttle opening is adjusted so as to be Nd (so as to coincide with each other).

  Specifically, when the detected engine speed NE is smaller than the target engine speed Nd, a throttle opening command value TH that is increased by a predetermined opening from the current throttle opening command value TH is output. On the other hand, when the engine speed NE is greater than the target speed Nd, the throttle opening command value TH that is reduced by a predetermined opening from the currently output throttle opening command value TH is output. The output throttle opening command value TH is transmitted to the electric motor 64, and the throttle opening is adjusted by the electric motor 64. In other words, the engine 10 according to this embodiment includes an electronic governor having a mechanism including the electric motor 64, the ECU 80, and the like.

  Since the ECU 80 commands the rotation amount of the electric motor 64 in this way, the opening (throttle opening) of the throttle valve 22 is calculated (detected) from its own command value TH without requiring a throttle opening sensor. To do. The throttle opening is calculated as a percentage when the vicinity of the fully closed position is 0 and the vicinity of the fully open position is 100.

  The fuel injection amount calculation block 80c is a fuel injection amount map (characteristics) set in advance based on the engine speed NE detected by the engine speed detection block 80a and the throttle opening command value TH input from the governor control block 80b. ) To calculate the basic injection amount, that is, a method called a throttle speed method.

  Further, the fuel injection amount calculation block 80c detects the engine temperature T from the output of the engine temperature sensor 72 during warm-up, and detects the temperature Ta of the spark plug seat 42a from the output of the spark plug seat temperature sensor 73, and detects it. A warm-up correction coefficient is calculated based on each of the temperatures T and Ta.

  Specifically, based on the engine temperature T, a warm-up correction coefficient initial value map (characteristic) and a warm-up correction coefficient subtraction amount map (characteristic) set in advance are searched and the warm-up correction coefficient initial value (initial value) is searched. And a warm-up correction coefficient subtraction amount are calculated, and a spark plug seat temperature correction coefficient map (characteristic) set in advance based on the temperature Ta of the spark plug seat 42a (more precisely, the temperature change amount) is searched for the spark plug. A seat temperature correction coefficient is calculated.

  The warm-up correction coefficient is obtained from the initial value of the warm-up correction coefficient, the warm-up correction coefficient subtraction amount, and the spark plug seat temperature correction coefficient, and fuel injection during warm-up is performed by multiplying the basic injection amount by the warm-up correction coefficient. The amount is calculated and transmitted to the injector 24 as the final fuel injection amount command value Qf. The injector 24 opens the valve for a valve opening time corresponding to the transmitted command value Qf and injects fuel. The calculation of the fuel injection amount during warm-up will be described in detail later.

  The ignition timing calculation block 80d calculates the ignition timing from the output of the pulsar coil 54 and controls the ignition operation of the spark plug 42 via the ignition device 82 such as an ignition coil. The fuel injection timing and the ignition timing are executed in accordance with the output of the pulsar coil 54.

  FIG. 3 is a flowchart showing the warm-up correction process for the fuel injection amount from when the operation switch 76 is turned on until the warm-up operation of the engine 10 is completed, among the processes executed by the ECU 80.

  Explaining below, first, at S10, the start-up control for injecting the start injection amount calculated based on the engine temperature T from the injector 24 is executed to increase the fuel injection amount. Specifically, the start injection amount map shown in FIG. 4 is searched from the engine temperature T at the start of the start to calculate the start injection amount, and the calculated start injection amount is injected from the injector 24. The starting injection amount is a fuel injection amount necessary for the starting operation of the engine 10 and is set so as to decrease stepwise as the engine temperature T rises as shown in the figure.

  Next, the routine proceeds to S12, where it is determined whether or not the engine 10 has been started. Specifically, it is determined whether or not the engine speed NE has reached a complete explosion speed (for example, 1000 rpm). On the other hand, if the determination is affirmative, the process proceeds to S14 and thereafter. The processes from S14 to S20 indicate warm-up control for warming up the engine 10 by increasing the fuel injection amount.

  In the warm-up control, first, in S14, a warm-up correction coefficient initial value map shown in FIG. 5 is searched from the engine temperature T to determine a warm-up correction coefficient initial value (initial value). As shown in the figure, the warm-up correction coefficient initial value includes a multiplication term of 1.0 or more, and is set so as to gradually decrease as the engine temperature T increases.

  Next, in S16, the temperature change amount [° C./sec] per unit time (specifically, 1 sec) of the spark plug seat 42a is detected. Next, in S18, the warm-up correction coefficient is calculated based on the basic injection amount and the temperature change amount of the spark plug seat 42a, and the basic injection amount is corrected with the calculated warm-up correction coefficient to warm up the engine. The fuel injection amount is calculated and injected from the injector 24.

Specifically, the fuel injection amount during warm-up is calculated according to the following formula.
Fuel injection amount during warm-up = basic injection amount x warm-up correction factor (1)
The warm-up correction coefficient is calculated using the following formulas (2) and (3).
Warm-up correction coefficient = initial value of warm-up correction coefficient-final warm-up correction coefficient subtraction amount (2)
Final warm-up correction coefficient subtraction amount = warm-up correction coefficient subtraction amount x spark plug seat temperature correction coefficient
... Formula (3)

  The basic injection amount of the equation (1) is calculated by searching a fuel injection amount map based on the throttle opening (more precisely, the throttle opening command value TH) and the engine speed NE.

  The warm-up correction coefficient includes a multiplication term of 1.0 or more, and every time the engine 10 rotates a predetermined number (for example, once), the final warm-up correction coefficient is subtracted from the initial value of the warm-up correction coefficient toward 1.0. It is calculated so as to decrease by (predetermined value). That is, every time the engine 10 rotates a predetermined number of times, the equations (2) and (3) are calculated to calculate the warm-up correction coefficient. In the second and subsequent calculations of the warm-up correction coefficient, the initial value of the warm-up correction coefficient in equation (2) is “(previously calculated) warm-up correction coefficient”. Further, the warm-up correction coefficient may be calculated so as to decrease by the final warm-up correction coefficient subtraction amount every time a predetermined time elapses instead of the rotation of the engine 10.

  The final warm-up correction coefficient subtraction amount is obtained by multiplying the warm-up correction coefficient subtraction amount by the spark plug seat temperature correction coefficient as shown in Equation (3). The warm-up correction coefficient subtraction amount is calculated by searching the engine temperature T for the warm-up correction coefficient subtraction amount map shown in FIG. The warm-up correction coefficient subtraction amount gradually increases in proportion to the increase in the engine temperature T, and is 0 when the engine temperature T is a value (for example, 100 ° C.) that can be estimated that the warm-up has ended.

  The spark plug seat temperature correction coefficient includes a multiplication term of 1.0 or more, and searches the spark plug seat temperature correction coefficient map shown in FIG. 6 based on the temperature change amount of the spark plug seat 42a detected in S16. calculate. As shown in the figure, the spark plug seat temperature correction coefficient is set to 1.0 when the temperature change amount of the spark plug seat 42a is relatively small (specifically, when it is between 0 and the value a). When the temperature change amount is greater than or equal to the value a (in other words, when the temperature change amount is relatively large), the temperature change amount is set to gradually increase. Further, the spark plug seat temperature correction coefficient is set to be an upper limit value (for example, 1.75) when the temperature change amount is not less than a value b larger than the value a.

  As a result, when the temperature change amount of the spark plug seat 42a is relatively large, the spark plug seat temperature correction coefficient increases, and the final warm-up correction coefficient subtraction amount obtained by equation (3) increases. As the final warm-up correction coefficient subtraction amount increases, the warm-up correction coefficient decreases in equation (2), and as a result, the fuel injection amount during warm-up in equation (1) decreases.

  The reason why the fuel injection amount during warm-up is reduced when the temperature change amount of the spark plug seat 42a is relatively large will be described with reference to FIG.

  FIG. 7 is a graph showing the relationship between the temperature Ta of the spark plug seat 42 a and the load connected to the engine 10 during the warm-up operation of the engine 10. In FIG. 7, from time 0 to time a, the engine speed NE is constant and the load acting on the engine 10 is small, that is, when the engine 10 is in the idle region, and after time a, the engine speed NE is A state where the load is constant and the load is applied, that is, when the engine 10 is in the rated region is shown.

  As shown in the figure, when the engine 10 is in the idling region, the thermal energy generated by the explosion in the combustion chamber 16 is relatively low, so the temperature rise (inclination) of the spark plug seat 42a to which the thermal energy is transmitted becomes moderate. In other words, the amount of temperature change is relatively small. On the other hand, when the engine 10 is in the rated region, the thermal energy generated by the explosion in the combustion chamber 16 is relatively high, so that the temperature rise (slope) of the spark plug seat 42a becomes steep, in other words, the temperature change amount is It becomes relatively large. Furthermore, although illustration is omitted, since the thermal energy increases as the load increases, the temperature change amount further increases as the load increases.

  From this, by detecting the temperature change amount of the spark plug seat 42a, it is possible to estimate the amount of load and the amount of thermal energy due to the explosion described above. Therefore, for example, when the temperature change amount of the spark plug seat 42a is large and it is estimated that the thermal energy is large at a high load, the warm-up of the engine 10 is promoted (advanced) by the amount of the thermal energy. Thus, it becomes possible to make the fuel injection amount at the time of warm-up smaller than the initially calculated value.

  From the above, in the process of S18, when the temperature change amount of the spark plug seat 42a is relatively large, the warm-up is proceeding. Therefore, the spark plug seat temperature correction coefficient is increased as described above according to the progress state. Thus, the final warm-up correction coefficient subtraction amount is increased, and the fuel injection amount during warm-up calculated by equation (1) is decreased.

  In the flowchart of FIG. 3, the process then proceeds to S20 to determine whether or not the current warm-up correction coefficient is greater than 1.0. When the result is affirmative in S20, the process returns to S16, while when the result is negative, that is, when the warm-up correction coefficient is reduced to 1.0 or less by the formula (2), the process proceeds to S22 and the warm-up control is finished. And exit the program. In other words, the warm-up control is executed until the warm-up correction coefficient becomes 1.0. In addition, although normal fuel-injection control is performed after completion | finish of warm-up, since it does not have a direct relationship with the summary of this application, description is abbreviate | omitted.

  FIG. 8 is a graph illustrating the above processing. In the figure, the horizontal axis represents the number of times the engine 10 has rotated.

  As will be described below, when the operation switch 76 is turned on while the engine 10 is stopped, first, start-up control for injecting the start injection amount from the injector 24 is executed (S10). Next, when the engine 10 is rotated, for example, r1 times and the start of the engine 10 is completed (S12), the warm-up calculated by correcting the basic injection amount with the warm-up correction coefficient calculated based on the temperature change amount of the spark plug seat 42a. Warm-up control for injecting the fuel injection amount from the injector 24 is started (S16, S18).

  Since the warm-up correction coefficient is calculated so that the final warm-up correction coefficient is subtracted from the initial value of the warm-up correction coefficient every time the engine 10 rotates a predetermined number of times, the fuel injection amount during warm-up also gradually decreases. To do.

  For example, when the temperature change amount of the spark plug seat 42a changes when the engine 10 rotates r2 times or r3 times, in other words, the load fluctuates and the engine 10 is warmed up (specifically, the progress state). ) Is changed accordingly, the final warm-up correction coefficient subtraction amount is increased / decreased by increasing / decreasing the spark plug seat temperature correction coefficient accordingly, so that the fuel injection at the time of appropriate warm-up according to the warm-up state of the engine 10 The amount is calculated and injected from the injector 24.

  Then, when the engine 10 rotates r4 times, the warm-up correction coefficient becomes 1.0, and the fuel injection amount during warm-up becomes the same value as the basic injection amount, the warm-up control is terminated. For example, the warm-up control is executed until the warm-up correction coefficient becomes 1.0 (S20, S22).

As described above, in the embodiment of the present invention, the throttle opening (throttle opening command) of the throttle valve 22 disposed in the intake pipe 20 of the general-purpose engine 10 that can be used as the power source of the work machine (load 60). Value) basic injection amount calculation means for calculating a basic injection amount based on TH and engine speed NE (ECU80, S18), spark plug seat temperature for detecting the temperature change amount of the spark plug seat 42a of the general-purpose engine 10 Change amount detection means (ECU 80, S16), engine temperature detection means (engine temperature sensor) 72 for detecting the temperature (engine temperature) T of the cylinder head 10b of the general-purpose engine 10, and the detected spark plug seat 42a. the temperature change amount and the fuel injection amount at the time of warming-up by correcting the basic injection amount the calculated on the basis of the temperature T of the cylinder head 10b Was composed as provided with a warm-up control execution means for executing the warm-up control to inject from the injector 24 (ECU80.S18) out.

  Thus, instead of the temperature of the lubricating oil, the warm-up is based on the temperature change amount of the spark plug seat 42a disposed in the vicinity of the combustion chamber 16 where the temperature rise of the engine 10 due to the warm-up operation is easily reflected immediately. Since it is configured to calculate the fuel injection amount at the time, an appropriate fuel injection amount according to the warm-up state of the engine 10 (specifically, the warm-up progress state) can be calculated, thereby shortening the warm-up operation time This makes it possible to reduce fuel consumption.

  Even when the general-purpose engine 10 is composed of an air-cooled general-purpose engine whose warm-up state (specifically, the warm-up progress state) is likely to change depending on the outside air temperature, It is possible to calculate an appropriate fuel injection amount according to the state.

Further, the warm-up control execution means calculates a warm-up correction coefficient based on the detected temperature change amount of the spark plug seat 42a and the temperature T of the cylinder head 10b, and the start of the general-purpose engine 10 is completed. After that, the basic injection amount is corrected with the calculated warm-up correction coefficient to calculate the fuel injection amount at the time of warm-up (S18), so that the warm-up according to the warm-up state of the engine 10 is performed. An appropriate fuel injection amount can be calculated from the correction coefficient, so that the warm-up operation time can be further shortened and the fuel consumption can be further reduced.

The warm-up correction coefficient is a predetermined value calculated from an initial value (warm-up correction coefficient initial value) calculated based on the temperature T of the cylinder head 10b based on the temperature change amount of the spark plug seat 42a. Since it is configured to be calculated so as to decrease by (the final warm-up correction coefficient subtraction amount) (S18), the warm-up correction coefficient can be gradually (stepwise) decreased as the engine 10 warms up. Therefore, an appropriate fuel injection amount corresponding to the warm-up state of the engine 10 can be calculated.

  Further, since the warm-up correction coefficient is calculated every time the general-purpose engine 10 rotates a predetermined number of times or every predetermined time elapses (S18), in other words, with the passage of time, in other words, the engine As the warm-up of 10 progresses, the warm-up correction coefficient can be surely reduced, so that a fuel injection amount more suitable for the warm-up state of the engine 10 can be calculated.

  Further, the warm-up correction coefficient includes a multiplication term of 1.0 or more, and decreases every predetermined value toward 1.0 each time the general-purpose engine 10 rotates a predetermined number of times or every predetermined time elapses. While being calculated (S18), the warm-up control execution means is configured to execute the warm-up control until the warm-up correction coefficient reaches 1.0 (S20, S22). As the engine advances, the warm-up correction coefficient can be gradually decreased toward 1.0, and thus a fuel injection amount more suitable for the warm-up state of the engine 10 can be calculated. Further, since the warm-up control is executed until the warm-up correction coefficient becomes 1.0, it is possible to execute (continue) the warm-up control until an appropriate time when the warm-up of the engine 10 is completed. Become.

  The general-purpose engine 10 is configured to include an actuator (electric motor) 64 that opens and closes the throttle valve 22 so that the engine speed NE becomes a target speed Nd set by an operator. Since the electronic governor is provided, since the throttle opening can be calculated (detected) based on the command value (throttle opening command value TH) for driving the actuator 64, the throttle opening sensor can be dispensed with. The fuel injection amount suitable for the warm-up state of the engine 10 can be calculated with a simple configuration.

  In the above description, the warm-up correction coefficient, the initial value of the warm-up correction coefficient, and the spark plug seat temperature correction coefficient are set as multiplication terms, but they may be addition terms. Further, although the spark plug seat temperature correction coefficient, the warm-up correction coefficient initial value, the warm-up correction coefficient subtraction amount, and the like are shown as specific values, these are examples and are not limited.

  Further, the fuel injection amount at the time of warm-up is calculated from the temperature change amount of the spark plug seat 42a. However, for example, an engine temperature change amount or an exhaust temperature change amount is used instead of the temperature change amount of the spark plug seat 42a. You may comprise as follows.

  DESCRIPTION OF SYMBOLS 10 engine (general purpose engine), 20 intake pipe, 22 throttle valve, 24 injector, 42 spark plug, 42a spark plug seat, 60 load (work machine), 64 electric motor (actuator), 80 ECU (electronic control unit)

Claims (4)

A basic injection amount calculating means for calculating a basic injection amount based on a throttle opening and an engine speed of a throttle valve disposed in an intake pipe of a general-purpose engine that can be used as a power source of a work machine; and ignition of the general-purpose engine Spark plug seat temperature change amount detection means for detecting the temperature change amount of the plug seat, engine temperature detection means for detecting the temperature of the cylinder head of the general-purpose engine, and the detected temperature change amount of the spark plug seat and the cylinder head Based on the temperature of the engine, a warm-up correction coefficient is calculated, and after the start of the general-purpose engine is completed, the basic injection amount is corrected with the calculated warm-up correction coefficient to calculate a fuel injection amount during warm-up and Rutotomoni a warm-up control execution means for executing the warm-up control to eject from the injector, the warm-up correction coefficient, the temperature based on said cylinder head Control apparatus for a general-purpose engine, characterized in that calculated from the initial value calculated have to decrease by a predetermined value which is calculated based on the temperature change amount of the ignition plug seat. The warm-up correction coefficient, the general-purpose engine control system for a general-purpose engine according to claim 1, wherein the calculated whenever the elapsed time or a predetermined time to rotate a predetermined number. The warm-up correction coefficient includes a multiplication term of 1.0 or more, and is calculated so as to decrease by a predetermined value toward 1.0 every time the general-purpose engine rotates a predetermined number of times or a predetermined time elapses. together with the warm-up control execution means, the control device according to claim 1, wherein the general-purpose engine the warmup correction coefficient and executes the warm-up control until 1.0. The general purpose engine according to any of claims 1 to 3, characterized in that it comprises an actuator for the engine speed to open and close the throttle valve so that the target rotational speed set by the operator General-purpose engine control device.

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