JP2012057537A - Fuel shortage determining apparatus for general-purpose engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel shortage determining apparatus for a general-purpose engine, determining whether the general-purpose engine having a so-called electronic governor is out of fuel, so as to prevent a trouble such as afterburning.SOLUTION: In a control device for a general-purpose engine having a so-called electronic governor, it is determined whether or not a detected engine speed is in a low-speed condition which is less than a predetermined engine speed (for example, 1500 rpm), whether or not throttle opening is in a high opening condition exceeding predetermined opening (for example, 90%), and whether or not the low-speed condition and the high-opening condition are continued for a predetermined time (for example, 100 msec) or longer, so as to determine whether or not the engine is in the fuel shortage condition that is out of fuel (S16). When the fuel shortage condition is determined, the engine 10 is stopped (S12).

Description

  The present invention relates to a fuel failure determination device for a general-purpose engine, and more specifically to a device for determining a fuel shortage state of a general-purpose engine and preventing afterburning or the like.

  As described in Patent Document 1, a general-purpose engine used as a power source for industrial small work machines such as agriculture and construction includes an operation switch (main switch) that can be operated by an operator (user). The operation of the engine is started when the switch is turned on, and the fuel supply is stopped and the operation of the engine is stopped when the switch is turned off and a stop instruction is input.

JP 2007-002715 A

  As described above, the general-purpose engine is stopped immediately when the operation switch is turned off. However, if a fuel shortage occurs due to a lack of fuel, stop processing cannot be performed unless the operation switch is turned off, and the behavior until the stop is not achieved. It may become stable, the engine speed may become unstable, and afterburning or backfire may occur.

  In particular, in the case of a general-purpose engine equipped with an actuator that opens and closes a throttle valve arranged in an intake pipe so as to achieve a target engine speed set by an operator, that is, a so-called electronic governor, the fuel supply is insufficient and the engine speed decreases. Therefore, the throttle opening is increased, and the fuel adjustment (adjustment of the air-fuel ratio) becomes extremely lean and unstable, so that the above-described disadvantages are remarkable.

  Therefore, the object of the present invention is to solve the above-mentioned problems and to avoid the occurrence of the above-mentioned inconveniences such as afterburn by determining the out-of-fuel state in a general-purpose engine equipped with a so-called electronic governor. An object of the present invention is to provide an out-of-fuel determination apparatus.

  In order to achieve the above object, in the fuel shortage determination device for a general-purpose engine according to claim 1, the fuel can be used as a power source for a work machine, and fuel stored in a fuel tank is supplied. In a general-purpose engine having an actuator that opens and closes a throttle valve disposed in an intake pipe so as to reach a target engine speed set by an operator, it is determined whether or not the fuel is in a fuel-deficient state. It is configured to include a state determination unit and a stop unit that stops the engine when it is determined that the fuel is out of fuel.

  In the fuel shortage determination device for a general-purpose engine according to claim 2, the fuel shortage state determination means is in a low speed state where the detected engine speed is less than a predetermined speed and the throttle opening is predetermined open. It is determined whether the low rotation state and the high opening state have continued for a predetermined time or more, and the low rotation state and the high opening state have continued for a predetermined time or more. When it is determined that the fuel is out of fuel, it is determined that the fuel is out.

  In the fuel shortage determination device for a general-purpose engine according to claim 3, the fuel shortage determination unit includes an operation switch that is operably disposed by an operator and generates an output corresponding to operation / stop. After the operation switch is turned on and the start of the engine is completed, it is determined whether or not the fuel is out of fuel.

  In the general-purpose engine fuel shortage determination device according to a fourth aspect, the stop means is configured to stop the engine by stopping fuel supply.

  In the fuel failure determination device for a general-purpose engine according to claim 5, the stop means is configured to stop the engine by stopping ignition.

  In the apparatus for determining fuel shortage of a general-purpose engine according to claim 1, a target engine rotation that can be used as a power source for a work machine, is supplied with fuel stored in a fuel tank, and is set by an operator In a general-purpose engine equipped with an actuator that opens and closes the throttle valve arranged in the intake pipe so as to be a so-called electronic governor, it is determined whether or not the fuel is depleted, and it is determined that the fuel is exhausted. Since the engine is stopped when the engine is operated, the engine speed becomes unstable even if the operation switch is not turned off by determining the out-of-fuel state in a general-purpose engine equipped with a so-called electronic governor. Or inconveniences such as afterburn and backfire can be avoided.

  In addition, because it is possible to perform the stop process normally, the engine stop process can be performed before the fuel supply pipe is filled with air, so that it is not necessary to vent the air at the next refueling. Can be improved.

  In the fuel shortage determination device for a general-purpose engine according to claim 2, the detected engine speed is in a low speed state where the engine speed is less than a predetermined speed, and the throttle opening is in a high position where the throttle opening exceeds a predetermined position. And when it is determined that the low rotation state and the high opening degree state have continued for a predetermined time or more, it is determined that the fuel is in a fuel exhausted state. Whether or not can be determined with high accuracy.

  The fuel shortage determination device for a general-purpose engine according to claim 3 is provided with an operation switch that is operably disposed by an operator and generates an output in accordance with operation / stop. When the engine is turned on and the engine has been started, it is configured to determine whether or not the fuel has run out. There is no judgment.

  In the general-purpose engine fuel shortage determination device according to claim 4, since the engine is stopped by stopping the fuel supply, the engine can be surely stopped in addition to the effects described above.

  Since the fuel shortage determination device for a general-purpose engine according to claim 5 is configured to stop the engine by stopping the ignition, the engine can be stopped reliably in addition to the above-described effects.

It is the schematic which shows the fuel outage determination apparatus of the general purpose engine which concerns on the Example of this invention generally. It is a flowchart which shows the determination of the fuel shortage state of the engine of the apparatus shown in FIG. 1, and a stop operation | movement. 3 is a time chart showing the operation of the engine when the process of FIG. 2 is not performed in the apparatus shown in FIG. 3 is a time chart showing the operation of the engine when the process of FIG. 2 is performed in the apparatus shown in FIG.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A best mode for carrying out a fuel shortage determination device for a general-purpose engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view generally showing a fuel shortage determination device for a general-purpose engine 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.

  As described above, the engine 10 is connected to a fuel supply system including the fuel supply pipe 26, the fuel tank 30, the sub fuel tank, the fuel pump 36, and the like, and is operated by being supplied with gasoline from the fuel supply system.

  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.

  The air-fuel mixture flows into the combustion chamber 16 when the intake valve 40 is opened, and is ignited and burned by the spark plug 42 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 the muffler (not shown) 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 includes a knob that can be pinched by an operator's finger and rotate within a range from a predetermined minimum engine speed to a maximum engine speed to indicate the target engine speed 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 air temperature sensor 70 including a thermistor is disposed upstream of the arrangement position of the throttle valve 22 in the intake pipe 20, and an output indicating the temperature of the intake air flowing through the portion is generated. The engine temperature sensor 72 is arranged to generate an output indicating the temperature of the part, that is, the temperature of the engine 10.

  A variable resistor (potentiometer) 74 is connected to the accelerator lever 62 to generate an output indicating the target engine speed intended by the operator, and to the operator (user) at an appropriate position on the housing of the engine 10. A freely operable operation switch (main switch) 76 is disposed.

  The operation switch 76 generates an output indicating an operation instruction including engine start when operated by the operator to the on position (turned on), and gives a stop instruction when operated to the off position (turned off). Produces the output shown.

  The outputs of the sensors 70, 72, 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 includes a microcomputer, detects the engine speed from the output of the pulsar coil 56, and controls the valve opening operation of the injector 24, the driving operation of the fuel pump 36, the driving operation of the electric motor 64, and the like from other sensor outputs. . The engine speed may be detected from the output of the power coil 56.

  Regarding the driving of the electric motor 64, the ECU 80 gives an instruction (determination) according to the operation of the accelerator lever 62 by the operator, in other words, the opening degree of the throttle valve 22 (the target engine speed set by the operator) ( (Throttle opening) is calculated, and the electric motor 64 is commanded via a drive circuit (not shown) so as to be the calculated throttle opening. 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 in this manner, the opening (throttle opening) of the throttle valve 22 is calculated (detected) from its command value without requiring a throttle opening sensor. 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 control will be described with respect to the valve opening operation of the injector 24. The ECU 80 searches for a preset map value (characteristic) from at least the calculated throttle opening and the engine speed detected from the output of the pulsar coil 54. Thus, the fuel injection amount is calculated, that is, the fuel injection amount is calculated by a technique called a throttle speed method.

  The fuel injection amount is calculated by the injection time (valve opening time) of the injector 24. When the engine 10 is started, the map search value is corrected with the detected engine temperature, and when the intake air temperature change is large, the map search value is corrected with the detected intake air temperature.

  Further, regarding the ignition control, the ECU 80 calculates the ignition timing from appropriate parameters, 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.

  Further, as described above, the ECU 80 determines the target engine speed in accordance with the operation of the accelerator lever 62, calculates the throttle opening of the throttle valve 22 so as to be the determined target engine speed, and at least the calculated value. The fuel injection amount is calculated from the throttle opening and the detected engine speed.

  The ECU 80 executes the determination of the target engine speed, the calculation of the throttle opening, the detection of the engine speed, and the calculation of the fuel injection amount every predetermined period, for example, 10 msec, and the calculated value is determined in predetermined control periods. Hold (memorize) during The ECU 80 executes the above-described operation when the operation switch 76 is turned on by the operator, and stops (ends) the above-described operation when the operation switch 76 is turned off.

  The ECU 80 further performs a determination of a fuel out condition of the engine 10 and a stop process.

  FIG. 2 is a flow chart showing the determination of the out-of-fuel state of the engine 10 and the stop process.

  As will be described below, in S10, it is determined whether or not the operation switch 76 is turned on by the operator. If the determination is negative, the process proceeds to S12, and the engine 10 is stopped. That is, normal stop processing is performed.

  Specifically, in S12, the engine is stopped by stopping the fuel supply (fuel injection) through the injector 24, or by stopping the ignition through the ignition device 82 and the ignition plug 42 (or stopping both the fuel supply and the ignition). 10 is stopped.

  Further, in S12, the engine 10 may be stopped by driving the throttle valve 22 to the stop opening degree via the electric motor 64 instead of or in addition to stopping the fuel supply / ignition, and further, the fuel pump The engine 10 may be stopped by stopping 36 (the electric motor).

  Since the ECU 80 executes the processing of the flowchart in FIG. 2 when the operation switch 74 is turned on by the operator, when the operation switch 74 is turned on once and then turned off by the operator, a stop instruction is given. This determination is denied and the process proceeds to S12, and the normal stop process described above is performed.

  On the other hand, if the result in S10 is affirmative, the program proceeds to S14, in which it is determined whether or not the engine 10 has completely exhausted, that is, whether the rotation of the engine 10 has reached the complete explosion speed, in other words, whether the engine 10 has been started. To do.

  When the result in S14 is negative, since it is determined that the engine 10 is being started, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S16, and the detected engine speed is set to a predetermined speed (for example, 1500 rpm). ) In a low rotation state where the throttle opening is higher than a predetermined opening (for example, 90%), and the low rotation state and the high opening state continue for a predetermined time (for example, 100 msec) or longer. Judge whether or not.

  FIG. 3 is a time chart showing the operation of engine 10 when the processing of FIG. 2 is not performed in the apparatus shown in FIG.

  If a fuel shortage (so-called gas shortage) occurs when gasoline (fuel) is deficient (fuel is cut), as shown in FIG. When air is mixed into the pipe 26, the amount of fuel supplied to the engine 10 becomes insufficient and unstable, and the combustion in the combustion chamber 16 becomes unstable.

  As a result, the engine 10 cannot maintain the target engine speed, and the engine speed becomes unstable as shown in the figure (hunting occurs). Also, as a result of the rapid increase in the throttle opening as the engine speed decreases, fuel adjustment becomes extremely lean and unstable. Furthermore, when misfire occurs, unburned gas flows into the exhaust pipe 46 and the muffler, and afterburning and backfire are generated.

  Returning to the description of the flow chart of FIG. 2, the determination in S16 corresponds to determining whether or not the fuel is in a dead state, as is apparent from the description of FIG.

  Accordingly, when the determination at S16 is affirmative, that is, when it is determined that the low rotation state and the high opening degree state have continued for a predetermined time or more, it is determined that the fuel has run out. Perform stop processing.

  That is, the engine 10 is stopped by stopping fuel supply (fuel injection) through the injector 24 or stopping ignition through the ignition device 82 and the spark plug 42 (or stopping both fuel supply and ignition). . If the result in S16 is negative, the subsequent processing is skipped.

  FIG. 4 is a time chart showing the operation of the engine 10 when the processing of FIG. 2 is performed in the apparatus shown in FIG.

  As is apparent from the figure, when it is determined that the fuel has run out, even if the operation switch 76 is not turned off at the stop processing execution point, the engine speed is reduced by immediately executing the normal stop processing. Decreases quickly without becoming unstable. Thus, by performing this process, the engine 10 can be stopped without causing afterburning or backfire.

  As described above, the engine fuel shortage determination device according to this embodiment can be used as a power source for the work machine (load 60), is supplied with fuel stored in the fuel tank 30, and is set by the operator. In the general-purpose engine 10 equipped with an actuator (electric motor) 64 that opens and closes the throttle valve 22 disposed in the intake pipe 20 so as to achieve the target engine speed, that is, a so-called electronic governor, the fuel is in a depleted state. Because it is configured to include a fuel shortage state determining means (ECU80, S16) for determining whether or not, and a stop means (ECU80, S12) for stopping the engine 10 when it is determined that the fuel is in a fuel exhausted state. The operation switch 76 is turned off by determining the out-of-fuel state in the general-purpose engine 10 equipped with a so-called electronic governor. Even in the absence, it can be or become engine speed unstable, inconvenience to afterburn and backfire or generated to avoid the occurrence.

  Furthermore, since it is possible to perform the stop process normally, the stop process of the engine 10 can be performed before the fuel supply pipe 26 is filled with air. The next startability can be improved.

  Further, the fuel out condition determining means is a high opening degree in which the detected engine speed is in a low speed state less than a predetermined engine speed (for example, 1500 rpm) and the throttle valve opening exceeds a predetermined valve position (for example, 90%). It is determined whether or not the low rotation state and the high opening state have continued for a predetermined time (for example, 100 msec) (ECU 80, S16), and the low rotation state and the high opening state have continued for a predetermined time or more. When it is determined that the engine is out of fuel, it is determined that the engine is out of fuel. Therefore, in addition to the effects described above, it can be accurately determined whether or not the engine 10 is out of fuel.

  In addition, an operation switch 76 that is operably disposed by an operator and generates an output in accordance with operation / stop is provided, and the fuel shortage determination means is configured to start the engine 10 when the operation switch 76 is turned on. (ECU 80, S 10, S 14), it is configured to determine whether or not the fuel is out of fuel (ECU 80, S 16). It is not mistakenly judged as a cut state.

  Further, since the stopping means is configured to stop the engine 10 by stopping fuel supply (ECU 80, S12), in addition to the above-described effects, the engine 10 can be stopped reliably.

  Further, since the stop means is configured to stop the engine 10 by stopping ignition (ECU 80, S12), in addition to the above-described effects, the engine 10 can be stopped reliably.

  In the above, the predetermined rotation speed, the predetermined opening degree, the predetermined time, etc. are all examples, and are not limited to them. Although a general-purpose engine using gasoline as fuel has been described as an example, it is applicable to a general-purpose engine using light oil or the like as fuel.

  10 general-purpose engine (general-purpose internal combustion engine), 12 cylinders, 14 pistons, 22 throttle valves, 24 injectors, 30 fuel tanks, 36 fuel pumps, 42 spark plugs, 50 crankshafts, 52 flywheels, 54 pulsar coils (crank angle sensors), 56 power coil, 60 load, 62 accelerator lever, 64 electric motor (actuator), 70 intake air temperature sensor, 72 engine temperature sensor, 74 variable resistor, 76 operation switch, 80 ECU (electronic control unit)

Claims (5)

  An actuator that can be used as a power source for a work machine, is supplied with fuel stored in a tank, and opens and closes a throttle valve arranged in an intake pipe so as to achieve a target engine speed set by an operator. The general-purpose engine provided includes: a fuel-out state determination unit that determines whether or not the fuel is in a fuel-deficient state; and a stop unit that stops the engine when it is determined that the fuel-out state. An out-of-fuel determination device for a general-purpose engine.   The out-of-fuel state determining means is in a low engine speed state where the detected engine speed is less than a predetermined engine speed, and is in a high engine position where the throttle opening is greater than a predetermined engine opening, and It is determined whether or not the opening state continues for a predetermined time or more, and when it is determined that the low rotation state and the high opening state continue for a predetermined time or more, it is determined that the fuel is out of fuel. The general-purpose engine fuel shortage determination device according to claim 1.   An operation switch that is operably disposed by an operator and that generates an output in accordance with operation / stop is provided, and the fuel out condition determination unit is configured to turn on the fuel after the operation switch is turned on and the start of the engine is completed. 3. The fuel outage determination device for a general-purpose engine according to claim 1 or 2, wherein it is determined whether or not the engine is out of operation.   4. The fuel outage determination device for a general-purpose engine according to any one of claims 1 to 3, wherein the stop means stops the engine by stopping fuel supply.   4. The fuel outage determination device for a general-purpose engine according to claim 1, wherein the stop means stops the engine by stopping ignition.

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