JP2000274292A - Electronic fuel injection engine for work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a fuel injection amount, in response to a change of an external load with superior following performance even by use of feedback control, and to suppress instability of operation at no load or a low load. SOLUTION: This engine has a load state decision part 53 for deciding whether an operation state of an engine is a middle-load/high load state or a low-load/non-load state, a first feedback control part 55 for setting an injection amount according to a middle-load/high-load map 54 set with a fuel poor side target air-fuel ratio in response to the decision by the load state decision part 53 that the operation state is the middle-load/high-load state, and a second feedback control part 58 for setting the injection amount according to a low-load/non-load map 57 set with a fuel rich side target air-fuel ratio, in response to the decision by the load state decision part 53 that the operation state is in the low-load/non-load state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic fuel injection engine for a working machine mounted on a working machine and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, an automobile engine detects the oxygen concentration in exhaust gas by an oxygen sensor provided in an exhaust passage when the vehicle is running at a constant speed, that is, when there is no significant change in the engine load or the rotational speed. To detect the actual air-fuel ratio and perform feedback control so that the deviation from the target air-fuel ratio falls within an allowable value.
It is controlled to be 4.7.

[0003] By setting the air-fuel ratio to the stoichiometric air-fuel ratio, a three-way catalyst for maximally reducing CO, HC and NOx near the stoichiometric air-fuel ratio is operated, and harmful components in the exhaust gas during constant speed running are reduced. It can be removed and fuel efficiency can be improved. On the other hand, in an automobile engine, from the viewpoint of safety for preventing overheating of the catalyst, when the engine speed is high and the output is high, the feedback control is canceled and the injection amount is set by open control. JP-A-58-5
1241).

[0004]

Generally, a working machine engine is often operated in an overloaded state, a low-load state, and a no-load state, as compared with the above-described automobile engine. Also, in the working machine engine, the load applied externally fluctuates greatly,
An instantaneous transition from the overload state to the no-load state, and conversely, a transition from the no-load state to the overload state frequently occur during the work.

[0005] Fig. 7 is a diagram showing the difference between the operating modes of the working machine engine and the automobile engine. The output is plotted on the vertical axis and the engine speed is plotted on the horizontal axis. In the case of an automobile engine, a characteristic curve changes according to a first speed curve 90a and a second speed curve 90b, and a human controls the speed by operating a clutch, an accelerator pedal, and a brake. The driving range of the vehicle engine is centered on the low-speed low-load range 91. On the other hand, the speed of the working machine engine is controlled by the governor (governor) as a medium speed operation line 92b and a high speed operation line 92c with the maximum output line 92a as an upper limit, and the operation range is high speed and high speed. In most cases, it is set in the load area 93. Taking a cultivator engine as an example of a work machine engine, when the soil is removed from the ground while being plowed by the rotary earth-crusher, the load is instantaneously reduced from the state 95 of the rated load and the rated number of revolutions. 96.

On the other hand, when the rotary earth-crusher is rotating in the air and the soil is dug at once, the load increases rapidly and sometimes becomes overloaded. If the fuel injection amount is not adjusted, engine stall may occur. Thus, in the working machine engine, the load applied from the outside is instantaneous, for example,
In about 0.01 to 1.0 seconds, a sudden change from full load to no load and from no load to full load can occur. On the other hand, in the case of an automobile engine, the most significant change in load is about the time of acceleration when the accelerator is suddenly depressed. Is unlikely to occur with a car engine.

[0007] The magnitude of the fluctuation of the external load is not only in the engine for the cultivator but also in the engine generator and the like. If there is, the power generation frequency fluctuates, which is a problem. Therefore, it is important to immediately increase the fuel injection amount in the overload state so that the rotation does not become unstable or the engine stalls. In addition, the rotation tends to be unstable even in a low-load / no-load state, and it is necessary to immediately increase the amount of fuel. Furthermore, in an overload state and a low-load / no-load state, rotation tends to be unstable due to an external load change, and it is necessary to control the fuel injection amount with a high response to the load change.

However, in the prior art, the feedback control is released and the open control is performed only when the rotation is high and the output is high. Therefore, there is a limit in that the air-fuel ratio is accurately controlled to the target air-fuel ratio. Further, as can be seen from FIG. 7, in the working machine engine, no load, low load,
Due to an external load variation such as overload, the operating range of the load targeted by the engine is wide. Therefore, it is preferable in terms of stable operation of the working machine if the fuel injection amount can be set promptly in response to the load fluctuation in the entire wide range of the load range unique to the working machine engine.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an electronic fuel injection engine for a working machine and a control method therefor that can solve the above problems. An example of a specific purpose is as follows. (a) To provide an electronic fuel injection engine for a working machine capable of suppressing a change in an air-fuel ratio in an overload state or a low load / no load state. (b) Even if the feedback control is adopted, the fuel injection amount can be changed with good responsiveness to the fluctuation of the external load, and the unstable operation at no load / low load or over load can be suppressed. Provided is an electronic fuel injection engine for a work machine. (c) Even if the feedback control is adopted, the work machine can be stably operated in the entire wide load range from no load to overload. It should be noted that the problems of the invention other than those described above and the means for solving the problems will be described in detail in the description in the following specification.

[0010]

The present invention will be described below with reference to, for example, FIGS. 1 to 6 showing an embodiment of the present invention. The first invention includes a fuel injection device 4 provided in an engine, a wide-band air-fuel ratio detecting means 20 provided in an exhaust passage and detecting an air-fuel ratio in a wide air-fuel ratio range, and a first target air-fuel ratio on a side where fuel is low. Feedback control means 55 for controlling the injection amount of the fuel injection device such that the deviation between the measured value and the measured air-fuel ratio falls within an allowable value.
And second feedback control means 58 for controlling the injection amount of the fuel injection device such that the deviation between the second target air-fuel ratio on the fuel-rich side and the measured air-fuel ratio falls within an allowable value. Load state determining means 53 for determining whether the load is high load or high load, or the load state determining means 53 is responsive to the load state determining means 53 determining that the load is medium load or high load. (1) The second feedback control unit 58 sets the injection amount in response to the feedback control unit 55 setting the injection amount and the load state determination unit 53 determining that the load is overloaded. I do.

The second invention comprises a fuel injection device 4 provided in the engine, a wide-band air-fuel ratio detecting means 20 provided in the exhaust passage for detecting the air-fuel ratio in a wide air-fuel ratio range, A first control method for controlling the injection amount of the fuel injection device so that the deviation between the target air-fuel ratio and the measured air-fuel ratio falls within an allowable value.
Feedback control means 55; second feedback control means 58 for controlling the injection amount of the fuel injection device such that the deviation between the second target air-fuel ratio on the fuel-rich side and the measured air-fuel ratio falls within an allowable value; Load state determining means 53 for determining whether the operating state is medium load / high load, low load / no load, and load state determining means 53
The first feedback control means 55 sets the injection amount in response to the determination that the load is medium load / high load, and responds to the load state determination means 53 determining that the load is low load / no load. The second feedback control means 58 sets an injection amount.

The third invention comprises a fuel injection device 4 provided in the engine, a wide-band air-fuel ratio detecting means 20 provided in the exhaust passage for detecting the air-fuel ratio in a wide air-fuel ratio range, A first control method for controlling the injection amount of the fuel injection device so that the deviation between the target air-fuel ratio and the measured air-fuel ratio falls within an allowable value.
Feedback control means 55; second feedback control means 58 for controlling the injection amount of the fuel injection device such that the deviation between the second target air-fuel ratio on the fuel-rich side and the measured air-fuel ratio falls within an allowable value; Load state determining means 53 for determining whether the operating state is low load / no load, medium load / high load, or overload.
The first feedback control means 55 sets the injection amount in response to the load state determination means 53 determining that the load is medium or high, and the load state determination means 53 determines that the load is overloaded. In response to the above, the second feedback control means 58 sets the injection amount, and in response to the load state determination means 53 determining that the load is low / no load, the second feedback control means 58 58 sets the injection amount.

A fourth aspect of the present invention is that the second feedback control means 58 sets the overload basic injection amount storage means 56 or the fuel quantity for setting the target air-fuel ratio on the fuel-rich side at the time of overload or low load / no load. The injection amount is set by feedback control based on the low-load / no-load basic injection amount storage means 57 in which the target air-fuel ratio on the side with the larger number is set. The fifth invention further comprises a catalyst 11 for removing harmful substances near the stoichiometric air-fuel ratio, and a narrow-band air-fuel ratio detecting means provided in the exhaust passage and detecting the air-fuel ratio in a narrow range near the stoichiometric air-fuel ratio. The first feedback control means 55 controls the injection amount of the fuel injection device 4 so that the deviation between the first target air-fuel ratio and the air-fuel ratio measured by the narrow-band air-fuel ratio detection means falls within an allowable value. It is characterized by.

Next, the first to fifth inventions will be described. In the first to fifth aspects of the present invention, the definitions of no load, low load, medium load, high load, and overload may be obtained by setting the numerical value of the load in each work engine according to the use form of the work machine. As the load detecting means to be determined by the load state determining means 53 in the first to third inventions, any means can be used as long as it can detect transient load fluctuations with relatively high responsiveness.
The configuration is not particularly limited. As such,
For example, detection of oil pressure, detection by a torque sensor of a piezoelectric element type having good response, detection of current in the case of a generator, and the like can be exemplified. In the case of detecting the load state including the work equipment, the load detection means may be configured by providing means for detecting a current value, a voltage value, a position of the work equipment, and the like representing the load state. In an embodiment described later, the load calculating unit 51 is shown as an example of the load detecting unit.

[0015]

According to the first aspect of the present invention, the first feedback control means sets the injection amount in response to the load state determining means determining that the load is a medium load or a high load. At the time of a high load, it is possible to perform an operation in consideration of fuel efficiency while maintaining a stable air-fuel ratio on the side with less fuel. Further, in response to the load state determining means determining that the load is overloaded, the second feedback control means sets the second target air-fuel ratio on the fuel-rich side and sets the injection amount. At the time of load, it is possible to perform an operation in which the air-fuel ratio is accurately maintained while maintaining a high output on the side with a large amount of fuel. In addition, since a wide-band air-fuel ratio detecting means for detecting the air-fuel ratio in a wide air-fuel ratio range is provided, regardless of overload, medium load or high load,
Feedback control can be performed by one air-fuel ratio detecting means.
Such a configuration that enables stable operation over a load range from the middle output to the high output side is suitable for a working machine engine.

According to the second aspect of the present invention, in response to the load state determining means determining that the load is medium or high, the first state is determined.
Since the feedback control means sets the injection amount,
At the time of medium load and high load, it is possible to operate in consideration of fuel efficiency while maintaining a stable air-fuel ratio on the side where fuel is low. Further, in response to the load state determining means determining that the load is low and no load, the second feedback control means sets the second target air-fuel ratio on the fuel-rich side and sets the injection amount. Therefore, when the load is low and no load is likely to cause unstable rotation, the operation can be performed with a high air-fuel ratio while maintaining stable rotation on the side with a large amount of fuel. In addition, since the wide-band air-fuel ratio detecting means for detecting the air-fuel ratio in a wide air-fuel ratio range is provided, feedback control can be performed by one air-fuel ratio detecting means regardless of low load / no load, medium load / high load. . Such a configuration that enables stable operation over a load range from no load to a high output side is suitable for a working machine engine.

According to the third aspect of the invention, the effects of the first and second aspects of the invention can be obtained. In addition, even in a working machine engine that frequently switches from no-load to overload during work, it is possible to reduce the load from no-load. It can operate stably in a wide load range up to overload. According to a fourth aspect, the second feedback control means sets the injection quantity by feedback control based on the overload basic injection quantity storage means or the low-load / no-load basic injection quantity storage means. Thereby, the calculation time of the injection amount can be shortened as compared with a configuration in which the basic injection amount is multiplied by the increase coefficient,
The ability to follow external load fluctuations during feedback control can be improved. According to the fifth aspect, a catalyst for removing harmful substances near the stoichiometric air-fuel ratio and a narrow-band air-fuel ratio detecting unit for detecting the air-fuel ratio in a narrow range near the stoichiometric air-fuel ratio are provided, and the first feedback control unit is provided. By controlling the injection amount of the fuel injection device so that the deviation between the first target air-fuel ratio and the actual air-fuel ratio measured by the narrow-band air-fuel ratio detection means is within an allowable value, the wide-band air-fuel ratio detection means Also, the air-fuel ratio can be accurately controlled to a value closer to the stoichiometric air-fuel ratio, and the effect of removing harmful components in the exhaust gas can be enhanced.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of an electronic fuel injection engine for a working machine according to the present invention. The electronic fuel injection engine E for a working machine includes a fuel spark plug 2 provided facing a combustion chamber 1 of the engine, a fuel injection device 4 provided in an intake pipe 3, and an air flow rate to the combustion chamber 1. A throttle valve 5 for controlling the inflow amount, a mechanical governor 6 for controlling the opening of the throttle valve 5, a pressure sensor 7 for detecting a pressure p in the intake pipe 3, and an engine by detecting a crank angle signal for a certain period of time. Speed sensor 9 for detecting the speed n of the motor
And an intake air temperature sensor 18 for detecting an intake air temperature t of the intake pipe 3
An engine liquid temperature sensor 19 for detecting the temperature t of the engine coolant, and a valve opening sensor 8 for detecting the opening of the throttle valve 5
It has.

In FIG. 1, at a predetermined position in the exhaust passage,
A three-way catalyst 11 is provided, and an air-fuel ratio detection sensor 20 for detecting an air-fuel ratio (for convenience, indicated by an excess air ratio λ) of the engine based on the oxygen concentration in the exhaust gas is provided at an upstream position or a downstream position. . FIG. 1 shows a configuration in which an air-fuel ratio detection sensor 20 is provided at a downstream position. As shown in FIG. 6 (A), the air-fuel ratio detection sensor 20 employs a sensor capable of outputting a detection voltage corresponding to a wide-band air-fuel ratio, for example, an air-fuel ratio in which λ is 0.6 to 1.3. is there.
In the case of the configuration of the fifth invention, in addition to the wide-band air-fuel ratio detection sensor 20, as shown in FIG. 6B, the sensor has a characteristic that the output voltage of the sensor changes abruptly near the stoichiometric air-fuel ratio. A narrow band air-fuel ratio detection sensor (not shown) is provided,
The output λ is input to a first feedback control unit 55 described with reference to FIG. As the narrow band air-fuel ratio detection sensor, a zirconia oxygen sensor conventionally used in combination with a three-way catalyst can be adopted. Although FIG. 1 shows only the injection valve, the fuel injection device 4 actually includes a fuel tank, a fuel pump for pumping fuel to the injection valve, and the like.

The electronic fuel injection engine E for work equipment is provided with a control unit 10 composed of a microcomputer for performing general control. The control unit 10 includes a detection pressure p of the pressure sensor 7, The engine speed n from the number sensor 9, the intake air temperature t from the intake air temperature sensor, the temperature t of the engine coolant from the engine fluid temperature sensor 19, the air-fuel ratio λ from the air-fuel ratio detection sensor 20, the air-fuel ratio λ from the valve opening sensor The valve opening degree θ is input. The injection pulse signal of the control unit 10 is output to the fuel injection device 4 to open the valve, and the injection amount is set based on the calculation of the control unit 10 according to the length of the injection time.

In the case of a multi-cylinder engine, it is general that each intake pipe is connected to each cylinder via a surge tank chamber 12 and each fuel injection device 4 is provided for each intake pipe. . The mechanical governor 6 includes, for example, a governor lever 14 swingably supported on a governor shaft 13 and a governing lever 1 for setting an engine rotation speed by an operator.
5 and a governor spring 16. An operating rod 17 of the throttle valve 5 is interlockedly connected to one end of the governor lever 14, and a governor spring 16 is connected to the other end of the governor lever 14.
And the governor spring 16 is linked to the speed control lever 15. By applying governor force (GF) to the governor lever 14, the throttle valve 5 is driven in a direction to close, and the governor spring 16 is driven to open the throttle valve 5 in tension.
That is, governor force (GF) and governor spring 1
The opening degree of the throttle valve 5 is controlled in proportion to the tension of the throttle 6.

The valve opening sensor 8 is configured to detect the rotation of the governor shaft 13. With this configuration, the valve opening sensor 8 can be stably supported, and the governor lever 14 and the throttle valve 5 can be supported. The effect of the operation delay of the connecting rod 17 and the like can be reduced. However, it is also possible to provide a valve opening sensor 8 at the position of the throttle valve 5. As in this embodiment, even in the electronic fuel injection engine, by controlling the opening of the throttle valve 5 by the mechanical governor 6, the control of the intake air amount can be left to the mechanical governor 6, The unit 10 has an advantage that it can concentrate on processing such as setting of an optimal fuel injection amount, and that when mounted on a working machine, it can stably exert a speed control function even under severe operating conditions.

FIG. 2 is a functional block diagram showing a schematic configuration of the control unit. The control unit 10 calculates a load applied to the engine from the engine speed n and the intake negative pressure p, and a load calculation unit 51 based on the load calculated by the load calculation unit 51 and the engine speed. Load / high load condition,
(B) detecting whether the state is an overload state or (c) a low load state or a no load state, and performing feedback control or open control based on the determination data 52 as shown in FIG. State determination unit 53 for determining whether to perform
In response to the load state determination unit 53 determining that the state is a medium load / high load state, the basic injection amount is set based on the medium load / high load map 54 to perform feedback control based on the air-fuel ratio. First feedback control unit 55 to be performed
And in response to the load state determination unit 53 determining that the state is an overload state or a low load / no load state, respectively,
A second feedback control unit 58 that sets a basic injection amount based on the overload map 56 and the low-load / no-load map 57 and performs feedback control based on the air-fuel ratio is provided.

Each of the feedback control units 55 and 58
, The pressure detection value p, the engine speed n, and the air-fuel ratio λ are input. For convenience, the medium load / high load map 54 and the first feedback control unit 55
Although the low-load / no-load map 57 and the second feedback control unit 58 are separately illustrated, each control unit 55, 58 is actually configured by a microcomputer and its program, and each map 54, 56, 57 Each is stored in the ROM of the computer.

In this specification, the basic injection amount (basic injection time) determined based on the rotational speed n and the pressure value p is expressed by E
(P, n), and the basic injection amount determined based on the rotational speed n and the throttle valve opening θ is described as E (θ, n). E
The (p, n) map stores the basic injection amount data in the form of grid points using the engine speed n and the intake negative pressure p as parameters as shown in FIG. 3A. Data between each grid point is calculated by interpolation between adjacent grid points. E
The (θ, n) map stores the basic injection amount data in the form of lattice points using the engine speed n and the throttle valve opening θ as parameters as shown in FIG. 3B.

The first feedback control unit 5 shown in FIG.
5. The second feedback controller 58 multiplies the basic injection amount E (p, n) by the air-fuel ratio correction coefficient F to increase or decrease the basic injection amount. In this embodiment, the medium-load / high-load map 54, the overload map 56, and the low-load / no-load map 57 are all given by data of the detected pressure value p and the rotation speed n, that is, the E (p, n) map. ing. The characteristic points of the medium load / high load map 54, the overload map 56, and the low load / no load map 57 are mainly as follows. In the medium-load / high-load map 54, a basic injection amount is set such that the stoichiometric air-fuel ratio (λ = 1) becomes close to the amount of air taken into the cylinder. The range of the air-fuel ratio is shown in FIG.
This is indicated by reference numeral 80 in (B). In the overload map 56, the basic injection amount is set such that a high output is obtained at the time of overload and the rotation is stable, for example, the air-fuel ratio on the fuel rich side of A / F = 13. . The low-load / no-load map 57 is, for example, an A
The basic injection amount is set so that the air-fuel ratio on the fuel-rich side of / F = about 12 to 14 is obtained. The range of the air-fuel ratio set in the low-load / no-load map 57 is indicated by reference numeral 81 in FIG. It should be noted that the range of the air-fuel ratio set in the overload map 56 corresponds to a position on the reference numeral 81 where the fuel is rich.

FIG. 4 is a flowchart for explaining the processing flow of this embodiment. The operation will be described below with reference to FIGS. This processing flow is performed for each injection of each cylinder. First, in step SP1, the intake negative pressure p,
The load calculation unit 51 (see FIG. 2) calculates the load by taking in the rotation speed n, and in step SP2, the load state determination unit 5
3 is based on the calculated load and engine speed,
(B) Medium load / high load condition, (b) Overload condition,
(C) Detecting any one of a low-load state and a no-load state, and then performing determination based on the determination data 52, and determining whether the load state determination unit 53 is in a medium-load or high-load state. In response to the determination that there is, in step SP3, the first feedback control unit 55 sets the basic injection amount based on the medium load / high load map 54 and performs feedback control based on the air-fuel ratio, and the load state determination unit 53 In response to the determination that
In P4, the second feedback control unit 58 sets the basic injection amount based on the overload map 56, and performs feedback control based on the air-fuel ratio. Also, the load state determination unit 5
In response to the determination that No. 3 is in the low-load / no-load state, in step SP5, the second feedback control unit 58 sets the basic injection amount based on the low-load / no-load map 57 and performs feedback based on the air-fuel ratio. Perform control. Here, as described above, if the load on the engine can be detected by other means, the processing in step SP1 is to take in the load value.

Further description will be made with reference to FIG. FIG.
Is a diagram showing the data for determination in the present embodiment,
FIG. 5 is a diagram showing the rotation speed on the horizontal axis, the load on the vertical axis, and the states of (a) medium load / high load, (b) overload, and (c) low load / no load. . The position (load, load, etc.) of the detected data 52
(The number of rotations). This discrimination data 52 performs the first feedback control in the medium load / high load range over the entire speed range from the low speed rotation to the high speed rotation of the engine in consideration of the governing action of the governor. -It is set so that the second feedback control is performed in a low load area, and the second feedback control is also performed in an overload area. The operation based on the discrimination data 52 will be described with reference to FIG. 6. When the engine is operated at a predetermined set rotation speed, a medium speed operation line 92 b and a high speed operation line 9
2c, the speed is controlled as shown in FIG.
In the case where the load slowly changes from no load → low load → medium load → high load → overload on the high-speed operation line 92c and the low-speed operation line (not shown), the second embodiment will be described. Switching is performed in the order of feedback control → first feedback control → second feedback control. Furthermore, in this embodiment, when the load is low and no load, the amount of increase at the time of overload adopts a configuration in which the map itself storing the basic injection amount is changed to that at the time of medium load and high load. There is an advantage that the injection amount can be set in a short time, and the followability is improved.

More specifically, F is a feedback correction coefficient that makes the deviation between the target air-fuel ratio and the measured air-fuel ratio zero, and does not change the basic injection amount during overload or the like.
If the basic injection amount is multiplied by the increase correction coefficient Kz to increase the amount of fuel at the time of overload or the like, the injection time Ti becomes Ti = E (p, n) · F · Kz, and the increase correction coefficient Kz It takes extra time to obtain by calculation. On the other hand, the overload map 56 and the low-load / no-load map 57 show the overload basic injection amount E, respectively.
(P, n), the basic injection amount E (p,
If n) is set separately, it can be calculated only by Ti = E (p, n) · F even when the load is increased at the time of overload or at low load / no load. Can be increased.

Next, a second embodiment of the present invention will be described. In the working machine engine, the change in the external load is first applied to the output shaft of the engine, so the change in the rotational speed n appears first, then the opening degree θ of the throttle valve changes, and finally, the engine The intake negative pressure p changes according to the change in the rotation speed n and the opening degree θ. In other words, unstable overload, low load,
In the no-load state, the change in the load corresponds to the rotation speed change rate (dn /
dt) is the most responsive, and the rate of valve opening change (dθ / d
t), the response decreases in the order of the intake negative pressure change rate (dp / dt). Therefore, overload condition where rotation is likely to be unstable,
In the low-load / no-load state, the actual injection amount is set based on a map in which the basic injection amount is set based on the throttle valve opening θ and the engine speed n, which are more responsive than the intake negative pressure p. If this is the case, the ability to follow changes can be improved.

According to such a concept, the entire period in which the second feedback control unit 58 performs control is set to E (θ,
A method of setting the basic injection amount based only on n) is also conceivable. According to this method, the basic injection amount can be set in a shorter time when the load is low, no load, or overload, and the engine rotation, which tends to be unstable, can be further stabilized. Further, according to a predetermined rule as described above, E (p, n) and E (p, n)
The injection amount may be obtained by performing weighting with (θ, n). Further, at the time of medium load and high load, the first feedback control unit sets the actual injection amount based on a map in which the basic injection amount is set based on the intake negative pressure p and the engine speed n, so that the longest operation is possible. The fuel consumption at the time of the rated rotation and the rated output at which the operation is performed can be improved. This is because driving on the basis of E (p, n)
This is because fuel efficiency is improved as compared with driving based on (θ, n).

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an electronic fuel injection engine of the present invention.

FIG. 2 is a functional block diagram of a control unit.

FIG. 3A shows an engine speed n and an intake negative pressure p.
FIG. 3A is a diagram schematically showing a map having basic injection amount data in a lattice point with parameters as parameters, and an engine speed n and a throttle valve opening θ as parameters in a lattice point as shown in FIG. It is a figure which shows the map which has injection amount data typically.

FIG. 4 is a flowchart schematically showing a basic process performed by a control unit according to the first embodiment.

FIG. 5 is a diagram showing discrimination data according to the present embodiment, in which the horizontal axis represents the number of revolutions, the vertical axis represents the load, (a) medium load / high load, and (b) overload. FIG. 4 is a diagram showing states, (c) a state of low load and no load in regions.

6A is a diagram showing a relationship between an air-fuel ratio and an output value of a wide-band air-fuel ratio detection sensor, and FIG. 6B is a diagram showing a relationship between an air-fuel ratio and an output value of a narrow-band air-fuel ratio detection sensor. FIG.

FIG. 7 is a diagram for explaining an operational difference between an automobile engine and a work engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Combustion chamber, 4 ... Fuel injection device, 5 ... Throttle valve, 7 ... Pressure sensor, 8 ... Valve opening sensor, 20 ... Broadband air-fuel ratio detection sensor, 53 ... Load state discriminator, 55 ... First feedback control Unit, 56: overload map, 57: low load / no load map, 58: second feedback control unit.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3G093 AA08 AB05 BA14 BA20 CA05 DA01 DA03 DA04 DA06 DA11 DB09 EA05 EA09 FA04 FA10 3G301 HA01 HA28 JA03 JA21 KA06 LA01 MA13 NC04 ND01 ND07 PA07Z PA10Z PA11Z PD04A PD04Z PE01Z PE08

Claims (5)

[Claims] 1. A fuel injection device (4) provided in an engine.
A wide-band air-fuel ratio detecting means (20) provided in the exhaust passage and detecting the air-fuel ratio in a wide air-fuel ratio range; and a deviation between the first target air-fuel ratio on the side where the fuel is low and the measured air-fuel ratio is within an allowable value. First feedback control means (55) for controlling the injection amount of the fuel injection device so as to fall within the range; and a fuel injection device for controlling the deviation between the second target air-fuel ratio on the side with a large amount of fuel and the measured air-fuel ratio within an allowable value. Feedback control means (58) for controlling the injection amount of the engine, and load state determination means (53) for determining whether the operation state of the engine is medium load, high load, or overload. The first feedback control means in response to the load state determination means (53) determining that the load is medium or high;
(55) sets the injection amount, and the load state determination means (5)
An electronic fuel injection engine for a working machine, wherein the second feedback control means (58) sets an injection amount in response to the determination in (3) that the engine is overloaded. 2. A fuel injection device (4) provided in an engine.
A wide-band air-fuel ratio detecting means (20) provided in the exhaust passage and detecting the air-fuel ratio in a wide air-fuel ratio range; and a deviation between the first target air-fuel ratio on the side where the fuel is low and the measured air-fuel ratio is within an allowable value. First feedback control means (55) for controlling the injection amount of the fuel injection device so as to fall within the range; and a fuel injection device for controlling the deviation between the second target air-fuel ratio on the side with a large amount of fuel and the measured air-fuel ratio within an allowable value. Feedback control means (58) for controlling the injection amount of the engine, and load state determination means for determining whether the operation state of the engine is medium load / high load, low load / no load
(53), wherein the first feedback control means responds to the load state determination means (53) determining that the load is medium or high.
(55) sets the injection amount, and the load state determination means (5)
An electronic fuel injection engine for a working machine, wherein the second feedback control means (58) sets an injection amount in response to the determination in (3) that the load is low / no load. 3. A fuel injection device (4) provided in an engine.
A wide-band air-fuel ratio detecting means (20) provided in the exhaust passage and detecting the air-fuel ratio in a wide air-fuel ratio range; and a deviation between the first target air-fuel ratio on the side where the fuel is low and the measured air-fuel ratio is within an allowable value. First feedback control means (55) for controlling the injection amount of the fuel injection device so as to fall within the range; and a fuel injection device for controlling the deviation between the second target air-fuel ratio on the side with a large amount of fuel and the measured air-fuel ratio within an allowable value. Feedback control means (58) for controlling the injection amount of the engine, and that the operating state of the engine is one of low load, no load, medium load, high load, and overload State determination means (53) for determining whether the load is medium or high, and the first feedback control means responds to the determination that the load is medium or high.
(55) sets the injection amount, and in response to the load state determining means (53) determining that the load is overloaded, the second feedback control means (58) sets the injection amount. The second feedback control means responds to the state determination means (53) determining that the load is low or no load.
(58) An electronic fuel injection engine for a working machine, wherein an injection amount is set. 4. The electronic fuel injection engine for a working machine according to claim 1, wherein said second feedback control means (58) is overloaded or under low load / no load. In (5), an overload basic injection amount storage means (56) in which the target air-fuel ratio on the fuel-rich side is set or a low-load / no-load basic injection amount storage means (57) in which the target air-fuel ratio on the fuel-rich side is set An electronic fuel injection engine for a working machine, characterized in that the injection amount is set by feedback control based on the engine. 5. The method according to claim 1, wherein
In the electronic fuel injection engine for a work machine described in the paragraph, a catalyst (11) for removing harmful substances near the stoichiometric air-fuel ratio, and a narrow band for detecting the air-fuel ratio in a narrow range near the stoichiometric air-fuel ratio provided in the exhaust passage Air-fuel ratio detection means, wherein the first feedback control means (55) controls the fuel injection device so that the deviation between the first target air-fuel ratio and the actual air-fuel ratio measured by the narrow-band air-fuel ratio detection means falls within an allowable value. (4) An electronic fuel injection engine for a working machine, wherein the injection amount is controlled.