JP2000274293A - Electronic fuel injection engine for work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a fuel injection amount in response to even a rapid load change with superior following performance, and to suppress instability of operation in a transient state. SOLUTION: This engine is provided with a fuel injection device, a target engine speed set part 37 for setting a target engine speed, a speed change rate calculation part 31 for calculating an engine speed change rate, a steady/ transient state decision part 32 for detecting that an operation state of the engine is a transient state, according to the calculated engine speed change rate, and a feedback correction coefficient calculating part 39 for controlling an injection amount of the fuel injection device, such that a deviation of a detected actual engine speed from the target engine speed is within an allowable value, in response to the decision by the steady/transient state decision part 32 that the operation state is the transient state. Thereby, the rotation change in the transient state is quickly suppressed to stabilize engine rotation early.

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 in which a sudden load change can occur, and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, as an electronic fuel injection device used for an automobile engine, in order to prevent exhaust gas from becoming too high when an engine is in a high load range, a catalyst provided in an exhaust passage is damaged. 2. Description of the Related Art There is known a method of controlling fuel injected from a fuel injection device (valve) to suppress a rise in temperature of exhaust gas. Also, in order to purify exhaust gas, CO, HC, N
A three-way catalyst for maximally reducing Ox is used. An oxygen sensor provided in an exhaust passage detects an oxygen concentration in exhaust gas to detect an actual air-fuel ratio, and a deviation from a target air-fuel ratio. The feedback control is performed so that the value falls within an allowable value, and the injection amount is adjusted.

Further, Japanese Patent Application Laid-Open No. Hei 3-111649 discloses that the engine speed and the engine load are detected, and when the load is high, the feedback control functioning near the stoichiometric air-fuel ratio is stopped to increase the injection amount by open control. A method of doing so is disclosed.

[0004]

SUMMARY OF THE INVENTION The above-mentioned JP-A-3-111
As disclosed in Japanese Unexamined Patent Publication No. 649, the release of the feedback control at the time of high load and the execution of the open control are as follows.
The present invention is also applicable to a working machine engine. However, since the working machine engine has a sudden change in load not found in an automobile engine, the engine speed and the load are detected as disclosed in Japanese Patent Application Laid-Open No. 3-111649, and the detected speed and load are detected. Only the method of switching to the open control based on the above cannot solve the problem peculiar to the working machine that the fluctuation of the rotation speed at the time of the transition due to the load fluctuation becomes large.

The above problem will be further described. FIG. 9 is a diagram showing the difference between the operating modes of the working machine engine and the automobile engine, in which the vertical axis represents the output and the horizontal axis represents the engine speed. Curve 90 for the first speed in the case of a car engine
a, the characteristic curve changes according to the curve 90b for the second speed, and the human controls the speed by operating the clutch, the accelerator pedal, and the 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 an example of a cultivator engine as a work machine engine, when the soil is plowed from the ground by the rotary earth-crusher, when the soil is removed from the ground, the load is instantaneously changed from the rated load, the rated speed state 95 to the no-load state. Therefore, if the setting of the fuel injection amount is not quickly followed in response to the rapid change of the load, the fluctuation of the rotational speed continues for a long time, and the operation becomes unstable.

Conversely, when the rotary earth-crusher is rotating in the air and the soil is excavated at once, the load increases rapidly. Therefore, the fuel injection amount must be adjusted in accordance with the increase. , There is a risk of stalling. As described above, in the working machine engine, the load applied from the outside suddenly changes from full load to no load, and from no load to full load in an instant, for example, about 0.01 to 1.0 seconds. It can happen. Such a thing cannot be achieved with an automobile engine, and it is preferable from the viewpoint of stable operation of a working machine if a fuel injection amount can be set promptly in response to a transitional change peculiar to a working machine engine. Also, not only for cultivator engines, but also for engines mounted on engine generators, when a sudden load is applied, if there is a large rotation speed fluctuation during the transition, if the power generation frequency is Will fluctuate, which is also a problem.

[0007]

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 which can solve the above problems. An example of a specific purpose is as follows. (a) Provided is an electronic fuel injection engine for a working machine that can change the fuel injection amount with good followability even for a sudden load change and can suppress the operation from becoming unstable during a transition. 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.

[0008]

The present invention will be described below with reference to, for example, FIGS. 1 to 8 showing an embodiment of the present invention. The first invention comprises a fuel injection device 4, target engine speed setting means 37 for setting a target engine speed, and engine speed detecting means 9
A rotational speed change rate calculating means 31 for calculating an engine rotational speed change rate, and a steady transient time detecting means 32 for detecting that the operating state of the engine is in a transient state based on the calculated engine speed change rate. , Its steady-state transient detection means 32
Is in a transient state, the injection amount of the fuel injection device 4 is adjusted so that the deviation between the actual engine speed detected by the engine speed detecting means 9 and the target engine speed is within an allowable value. And a rotation speed feedback control means for controlling the rotation speed.

In a second aspect of the present invention, the air-fuel ratio detecting means 20 for detecting the air-fuel ratio and the fuel injection so that the deviation between the target air-fuel ratio and the measured air-fuel ratio from the air-fuel ratio detecting means 20 fall within an allowable value. An electronic fuel injection engine comprising an air-fuel ratio feedback control means 33 for controlling an injection amount of the device 4. The air-fuel ratio feedback control means 33 responds to the detection of the transient state by the steady-state transient detection means 32. An open control means 34 for releasing the control and setting the injection amount by open control based on the transient injection amount map 35 is provided.

According to a third aspect of the present invention, a throttle valve 5 for controlling an amount of air flowing into the combustion chamber 1, a pressure sensor 7 for detecting a pressure in an intake passage, and an opening θ of the throttle valve 5 are detected. A valve opening sensor 8, wherein the open control means 34 controls the map 23 in which the basic injection amount is set based on the pressure value p and the engine speed n, and the base 23 based on the valve opening θ and the engine speed n. A map 24 in which the injection amount is set, and weighting means 25 for weighting the first basic injection amount and the second basic injection amount calculated based on each map according to a predetermined rule, and the injection amount weighted by the weighting means 25 Is set based on the actual injection amount. The fourth invention includes a fuel injection device 4, a target engine speed setting means 37 for setting a target engine speed, an engine speed detecting means 9, a load state detecting means for detecting a load state on the engine, Steady-state transient detecting means 32 for detecting that the operating state of the engine is in a transient state based on the detected load state, and responding to the steady-state transient state detecting means 32 detecting that the engine is in a transient state. A rotation speed feedback control unit that controls an injection amount of the fuel injection device 4 such that a deviation between the actual rotation speed detected by the rotation speed detection unit 9 and the target engine rotation speed is within an allowable value. And

Further, the first to fourth inventions will be described. In the first invention, the target rotation speed setting unit 37 includes:
A configuration in which an average value of the number of rotations for a predetermined time is calculated and the average value of the number of rotations is set as a target value, or the speed control lever 1 shown in FIG.
5 may be constituted by a position detecting means for detecting the position of No. 5. In the third invention, the weighting coefficient is defined as a valve opening change rate (dθ).
/ Dt) and a pressure change rate (dp / dt). The configuration of the load state detecting means in the fourth invention is not particularly limited as long as it is a means capable of detecting transient load fluctuations with relatively high responsiveness. As such, for example, detection of oil pressure, detection by a responsive piezoelectric element type torque sensor, detection of current in the case of a generator, etc. (Dθ / dt) detection,
And the like. In order to detect an external load condition applied to the engine by the engine alone, it is preferable to employ the rate of change in the rotational speed (dn / dt) as in the first invention. The load state detecting means may be configured by providing means for detecting a current value, a voltage value, a position of a work implement, and the like representing a load state.

[0012]

According to the first aspect of the present invention, in response to the steady-state transient detecting means detecting that the engine is in the transient state, the rotational speed feedback control means controls the actual rotational speed detected by the engine rotational speed detecting means. Since the injection amount by the fuel injection device is controlled so that the deviation of the target engine speed is within an allowable value, the injection amount can be set so as to more quickly suppress the fluctuation of the engine speed during a transition. Further, since the fact that the operating state of the engine is in a transient state is detected based on the rate of change of the engine speed, it is possible to respond to an external load change applied to the engine most quickly. This utilizes the fact that when the load on the engine suddenly increases or decreases, the engine speed decreases or increases with the highest responsiveness via the output shaft of the engine. is there.

According to the second aspect of the present invention, in response to the steady-state transient detection means detecting that the transient state has occurred, the open control means cancels the feedback control based on the air-fuel ratio and sets the transient injection amount map. Based on the open control, the injection amount is set. Therefore, since the open control is performed, the setting of the fuel injection amount during the transition can be performed more quickly, and the unstable operation of the engine due to a large fluctuation in the engine speed during the transition can be suppressed. The operation and effect of the third invention will be described. Considering the case where the load is instantaneously reduced from the rated load and the rated speed as when the soil is removed from the ground with the rotary soil crusher as mentioned above, Since the load on the output shaft of the motor disappears, the change in the rotation speed appears first,
Then, the opening degree θ of the throttle valve changes, and finally, the intake negative pressure p changes due to changes in the engine speed n and the opening degree θ.

That is, when the load suddenly changes, the rate of change of the rotational speed (dn / dt) has the best response,
Valve opening change rate (dθ / dt), intake negative pressure change rate (dp /
Responsiveness decreases in the order of dt). Therefore, in the transient state, if 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, load fluctuations may occur. It can be seen that the ability to follow the accompanying transient state can be improved.

Therefore, the open control means sets a basic injection amount based on the pressure value and the engine speed, a map in which the basic injection amount is set based on the valve opening and the engine speed, Weighting means for weighting the first basic injection amount and the second basic injection amount calculated on the basis of a predetermined rule, and setting an actual injection amount based on the injection amount weighted by the weighting means. Then, according to the contents of the rules, finer control of the injection amount can be performed even during the transition. For example, in the initial stage of the transient period when the rotational speed fluctuates greatly during the transient period, the basic injection amount is set mainly based on the valve opening and the engine rotational speed. In the last stage, the rule may be set such that the basic injection amount is set mainly based on the pressure value and the engine speed. By making it possible to perform finer injection amount control even during the transition,
An optimal injection amount can be set, and control can be performed so that fluctuations in the number of revolutions can be converged more quickly. 4th
According to the invention, in response to the steady-state transient detecting means detecting that the engine is in a transient state based on the detected load state, the rotational speed feedback control means controls the actual rotational speed detected by the engine rotational speed detecting means. Since the injection amount by the fuel injection device is controlled so that the deviation of the target engine speed is within an allowable value, the injection amount can be set so as to more quickly suppress the fluctuation of the engine speed during a transition.

[0016]

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 the intake air temperature 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. 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 control unit 10 mainly includes a microcomputer program and a computer R
This is configured by data stored in the OM. 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 can concentrate on processing such as setting of an optimum fuel injection amount, and can stably exert a speed control function even under severe operating conditions when mounted on a work machine.

FIG. 2 is a functional block diagram showing a schematic configuration of the control unit. The control unit 10 includes a target rotation speed setting unit 37,
Superimposer 38 for superimposing actual engine speed and target speed
An engine speed change rate calculating unit 31 for calculating the engine speed change rate; and a calculated engine speed n change rate (d
n / dt) and a predetermined threshold value, the engine is in a steady state in which the engine is rotating stably at a constant rotational speed, or a transient of large rotational speed fluctuation due to an external load fluctuation. Steady-state transient determination unit 32 for determining whether the state is the state
A first injection amount setting unit 21 for setting a first basic injection amount based on an E (p, n) map (not shown) based on the intake negative pressure p and the engine speed n; 3
A switch 40 that is in a short-circuit state in response to the determination that the transition time 2 is in a transient state, and a feedback correction coefficient calculation unit 39 that calculates a feedback coefficient so that the deviation obtained by the superimposer 38 falls within an allowable range. In response to the steady-state transient determination unit 32 determining that a transition is being made, the feedback compensation coefficient calculated by the feedback correction coefficient calculation unit 39 during the first injection time set by the first injection amount setting unit 31. A multiplier 41 for multiplying a coefficient to obtain a corrected injection time. The above-mentioned steady-state transient detection means detects a transient state by the steady-state transient determination unit 32.
This is performed by a determination process that this is a transition time.

FIG. 6 is a functional block diagram showing an embodiment in which a configuration for switching between feedback control and open control based on the air-fuel ratio is added as described in the second invention. In addition to the configuration shown in FIG. 2, the control unit 10 receives the pressure detection value p, the engine speed n, and the air-fuel ratio λ in response to the steady-state transient determination unit 32 determining that the engine is in a steady state. In response to the feedback control unit 33 performing the feedback control based on the air-fuel ratio by setting the basic injection amount based on the steady-state injection amount map 36, and responding to the steady-state transient determination unit 32 determining that the engine is in the transient state. As a result, the pressure detection value p and the engine speed n are input, and the transient injection amount map 35
And an open control unit 34 for setting the fuel injection amount by open control based on the open control. Explaining the correspondence between FIG. 2 and FIG. 6, when performing the feedback control based on the air-fuel ratio, the setting of the first injection amount setting unit 21 in FIG. 2 becomes the feedback control unit 33 based on the air-fuel ratio, and the open control of the air-fuel ratio is performed. Is performed, the first injection amount setting unit 2
The setting of 1 becomes the open control unit 34.

In FIG. 6, for convenience, the steady-state injection amount map 36 and the feedback control unit 33 and the transient-time injection amount map 35 and the open control unit 34 are separately illustrated. Actually, each of the control units 33 and 34
Is constituted by a microcomputer program, and each of the maps 36 and 35 is stored in the ROM of the computer.

In the present specification, the basic injection amount (basic injection time) determined based on the rotation speed n and the pressure value p is 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 (p, n)
The map shows the engine speed n as shown in FIG.
The basic injection amount data is stored in the form of lattice points using the intake negative pressure p as a parameter. Data between each grid point is calculated by interpolation between adjacent grid points. E (θ, n)
The map shows the engine speed n as shown in FIG.
The basic injection amount data is stored in the form of lattice points using the throttle valve opening θ as a parameter.

The feedback control section 33 multiplies the basic injection amount E (p, n) by an air-fuel ratio correction coefficient F to increase or decrease the basic injection amount. In this embodiment, both the steady-state injection amount map 36 and the transient-time injection amount map 35 are given by the data of the detected pressure value p and the number of revolutions n, that is, E (p, n). The differences between the transient injection amount map 35 and the steady-state injection amount map 36 are mainly as follows. In the transient injection amount map 35, injection amount data relating to the rotational speed n and the detected pressure value p, which is not necessary in a steady state, is set in advance in consideration of the rotational speed variation that overshoots during the transient. The transient injection amount map 35 is determined by a sudden load change.
In order not to take a long time until the rotation speed stabilizes,
Map data storing a large basic injection amount value on the fuel rich side (rich side) is set in advance so as to suppress fluctuations in the rotational speed due to sudden load fluctuations. However, as a simple method, except for the steady-state injection amount map 36,
And the transient injection amount map 35 may be configured with exactly the same data.

FIG. 4 is a flow chart for explaining the processing flow of this embodiment, and is a flowchart in the case where the configuration for switching the feedback control based on the air-fuel ratio to the open control and the configuration for performing the feedback control based on the engine speed are combined. It is. This processing flow is performed for each injection of each cylinder. First, at step SP1, the intake negative pressure p and the rotational speed n are fetched, and at step SP2, the rotational speed change rate (dn / dt) and the proportional component P (n) of the rotational speed, the integral component I (n) of the rotational speed, and the rotational speed The differential components D (n) of the numbers are calculated, and the steady state and the transient state are determined based on the rotational speed change rate in step SP3. If the steady state is determined, the steady state injection is performed in step SP4. The basic injection amount E (p, n) is calculated based on the amount map 36,
In step SP5, a feedback correction coefficient F based on the air-fuel ratio is calculated, and in step SP6, the basic injection amount is multiplied by the feedback correction coefficient F to E (p, n) to obtain an injection time Ti feedback-corrected based on the air-fuel ratio. calculate. On the other hand, if it is determined that the engine is in a transitional state, the basic injection amount E (p, n) is calculated in step SP7 based on the transient injection amount map 36, and the process proceeds to step SP7.
In step S8, open control is performed by setting the feedback correction coefficient F based on the air-fuel ratio to 1.
In P9, the injection time Ti is calculated based on the basic injection amount E (p, n) and the rotation speed feedback correction coefficient G.

A further description will be given with reference to FIG. FIG.
(A) is a diagram showing a change in the number of revolutions when the load suddenly changes from full load to no load in the present embodiment, in which the horizontal axis represents time and the vertical axis represents the number of revolutions. FIG. 5B is a diagram showing a change in the air-fuel ratio at that time. First, at the time t0, when the load suddenly drops and becomes small, the load is not applied to the output shaft of the engine.
The number of revolutions rises sharply. The inclination (dn / dt) 26
In step SP3, it is determined whether or not the threshold value has exceeded a predetermined threshold value, thereby determining whether it is a steady state or a transient state.
In FIG. 5A, the time when it is determined that the time is a transition is indicated by t1. As a determination method, as shown in FIG. 4, when the load suddenly increases, the rotation speed decreases. If dn / dt <predetermined value, then it is determined that the engine is in a transient state. When dn / dt> predetermined value is satisfied, it is determined that the engine is in a transient state.

When it is determined that the engine is in a steady state, the basic injection amount E
After calculating (p, n), in step SP5, the feedback correction coefficient F is set to a known method so that the deviation between the target air-fuel ratio and the air-fuel ratio detected by the air-fuel ratio detection sensor 20 (see FIG. 1) becomes zero. In step SP6, the injection time Ti corrected by the equation of Ti = E (p, n) .F.Kx is calculated. Here, Kx is a correction coefficient taking into account the temperature t from the liquid temperature sensor 19 shown in FIG.
Is a correction coefficient obtained by integrating correction coefficients and the like in consideration of the above.

On the other hand, when it is determined that a transient state has occurred, F = 1 is set in step SP8 to perform open control, and in step SP9, the proportional component P (n) of the rotational speed obtained in step SP2 is determined. ), The integral component I (n) of the rotational speed, and the differential component D (n) of the rotational speed, the feedback correction coefficient calculator 39 shown in FIG. PID (n) = a.P (n) + b.I (n) + c.D (n) where a, b, and c are gain coefficients for realizing optimal feedback. Then, an injection time Ti corrected by Ti = E (p, n) · PID (n) · Kx is calculated.

In this embodiment, the open control does not calculate the feedback correction coefficient F, and there is no process of multiplying the basic injection amount E (p, n) by the feedback correction coefficient F. When the fuel injection amount is set so as to be stable, the followability is improved, and fluctuations in the rotational speed during transition can be suppressed as quickly as possible. Also, during the open control, the injection amount is corrected by the feedback control based on the rotation speed, so that the fluctuation of the rotation speed can be fed back to the injection amount quickly, and the fluctuation of the rotation speed during the transition can be reduced. Can be suppressed quickly.

In FIG. 5A in which the load suddenly decreases, it is determined only by whether or not dn / dt> predetermined value.
Although the control returns to the feedback control at 2, the rotation speed is stabilized from t 1 by providing the predetermined determination means.
Open control can be performed up to three times. As the method, for example, the state of (a) in which the rate of change of the rotational speed is gradually reduced, the state of (b) of slight undulation, and the like are determined from the rate of change in the rotational speed to determine whether or not the speed is stable. How to be able to. It is determined whether (dθ / dt) has returned to the steady value.
This is because (dθ / d)
t) gradually becomes smaller. This state is determined by comparing with a threshold value. There is. With these methods, open control can be performed only during a transition.

[0032]

Second Embodiment FIG. 7 is a control flowchart showing a second embodiment of the present invention. In the second embodiment, in order to further speed up the following operation of the fuel injection amount during the transition, FIG.
A weighted injection time setting unit 44 for setting a weighted injection time Tj, which will be described later, at a position 43 of the first injection amount setting unit 21 of FIG.
Is provided in place of the first injection amount setting unit 21, and at least the weighting time setting unit 44 determines the fuel injection device 4 based on the detected valve opening θ and the detected engine speed n. Setting the basic injection amount E (θ, n) of the fuel injection device 4 based on the detected pressure detection value p and the detected engine speed n.
It is characterized in that it includes a process of setting (p, n) and a process of weighting the two basic injection amounts E (θ, n) and E (p, n) according to a predetermined rule.

FIG. 8 is a block diagram showing an example of the configuration of the weighted injection time setting section. 8, a weighted injection time setting unit 44 sets an E (p, n) map 23 in which a basic injection amount is set based on a pressure value p and an engine speed n.
A first basic injection amount setting unit 21 that sets a first basic injection time based on an E (p, n) map 23, a detected pressure p, and a detected rotational speed n; An E (θ, n) map 24 in which the basic injection amount is set based on
A second basic injection amount setting unit 22 for setting a second basic injection time based on the (θ, n) map 24, the detection valve opening θ, and the detected rotation speed n; a first basic injection time and a second basic injection time And a weighting unit 25 for weighting according to a predetermined rule.
The injection amount calculated by the weighting unit 25 is output to the multiplier 41 shown in FIG.

As described above, when the external load fluctuation occurs, the rotational speed change rate (dn / dt) has the best response, the valve opening degree change rate (dθ / dt), and the intake negative pressure. Responsiveness decreases in the order of the change rate (dp / dt). Therefore,
During a transition, the valve opening degree θ is more responsive than the intake negative pressure p.
By setting the actual injection amount based on the E (θ, n) map 24 in which the basic injection amount is set based on the engine speed n, the follow-up performance can be further improved.
According to such a concept, a method of setting the basic injection amount for all periods in which the open control unit 34 performs control based on only the E (θ, n) map 24 is also conceivable. This method is also an extremely effective method if emphasis is placed on making a good follow-up operation of the injection amount setting at the initial stage of the transition.

In the flowchart shown in FIG. 7, E (θ,
Instead of setting the injection amount based only on n), the responsiveness can be improved at the time of transition to the transient state, and the injection amount is set by weighting in consideration of the responsiveness of dθ / dt and dp / dt. A method for performing the above will be described. FIG.
First, in step SP11, the intake negative pressure p, the rotation speed n, and the throttle valve opening θ are taken in.
At 12, the rate of change of rotation speed (dn / dt), the rate of change of throttle valve opening (dθ / dt), the rate of change of intake negative pressure (dp / dt)
Is calculated, a proportional component P (n) of the rotational speed, an integral component I (n) of the rotational speed, and a differential component D (n) of the rotational speed are calculated. If it is determined that it is in a transitional state and it is determined that it is in a steady state, it is determined in steps SP4 to SP4 in the first embodiment.
The injection time Ti that has been feedback-corrected by the same processing as in step 6 is calculated.

On the other hand, if it is determined in step SP13 that the time is a transition, then in step SP17,
The detected intake negative pressure p, valve opening θ, rotation speed n, E (p,
n) Based on the map 23 and the E (θ, n) map 24, the first basic injection time E (p, n) and the second basic injection time E
(θ, n) is calculated, and in step SP18, the injection time Tj weighted by the following first equation is calculated.

[0037]

(Equation 1)

Next, in step SP19, open control is performed by setting the feedback correction coefficient F based on the air-fuel ratio to 1, and in step SP20, the injection time Ti corrected by the equation Ti = Tj.PID (n) .Kx is calculated. calculate. With this control flow, weighting processing and feedback control based on the number of rotations can be performed.

The processing of step SP18 in FIG. 7 will be further described. In the above first equation, immediately after the load change indicated by t0 in FIG. 5A, (dθ / dt) is larger than (dp / dt).
Is much larger, so that in the initial stage of the transition, the second basic injection time E (θ, n) accounts for most of the time. Then (d
As (θ / dt) decreases, (dp / dt) gradually increases this time. Therefore, in the initial stage of the transition, the weighting coefficient (dθ / dt) of the second basic injection time E (θ, n) is large. Weighting coefficient (dp / dt) increases. If this change is described with reference to FIG. 5A, when the change during the transition is severe (t0 to t2), the fuel injection amount that emphasizes the followability can be set mainly by E (θ, n), and the steady state can be set. (T2 to t3), the fuel injection amount can be set with emphasis on stability and fuel efficiency mainly by E (p, n). Here, α and β are adjustment coefficients for adjusting the sum of the weighted first basic injection time and the second basic injection time so that the appropriate injection time is obtained. For example, α + β = 1 Is done. In the case where the embodiment for determining whether the load is in a steady state or a transient state based on the load state is adopted, a configuration in which a voltage value, a current value, and the like indicating the detected load state are compared with a predetermined threshold value is adopted. do it.

[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. 5A is a diagram showing a change in rotation speed when a sudden change from full load to no load occurs in the present embodiment;
FIG. 5B is a diagram showing a change in the air-fuel ratio at that time.

FIG. 6 is a functional block diagram for explaining the invention in which the feedback control of the air-fuel ratio is canceled and the process shifts to the open control during a transition.

FIG. 7 is a flowchart schematically illustrating a basic process performed by a control unit according to the second embodiment.

FIG. 8 is a functional block diagram of a weighted injection time setting unit according to the second embodiment.

FIG. 9 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, 9 ... Engine speed detection sensor, 20 ... Air-fuel ratio detection sensor, 23 ... E (p, n) ) Map, 24... E (θ, n) map, 25.
31: engine speed change rate calculation unit, 32: steady state transient detection unit, 33: feedback control unit, 34: open control unit, 35: transient injection amount map, 37: target engine speed setting unit

Continued on the front page F-term (reference) 3G084 AA06 BA03 BA05 BA09 BA13 DA04 DA11 EB06 EB11 FA02 FA10 FA11 FA20 FA29 FA33 3G301 HA01 HA28 JA04 KA06 LA01 MA01 MA13 MA14 MA16 NA00 NC02 ND01 ND07 ND16 PA07Z PA08Z PA10 PE11Z01ZZZ PE08Z

Claims (4)

[Claims] 1. A fuel injection device (4), target engine speed setting means (37) for setting a target engine speed, engine speed detecting means (9), and a speed for calculating an engine speed change rate. Number change rate calculating means (31) and steady state transient time detecting means (32) for detecting that the operating state of the engine is in a transient state based on the calculated engine speed change rate.
The deviation between the actual engine speed and the target engine speed detected by the engine speed detecting means (9) in response to the detection of the transient state by the steady state transient detecting means (32) is an allowable value. An electronic fuel injection engine for a working machine, comprising: a rotation speed feedback control means for controlling an injection amount of the fuel injection device (4) so as to be inside. 2. An electronic fuel injection engine for a working machine according to claim 1, wherein said air-fuel ratio detecting means detects an air-fuel ratio, and said target air-fuel ratio and air-fuel ratio detecting means are provided.
An electronic fuel injection engine comprising air-fuel ratio feedback control means (33) for controlling the injection amount of the fuel injection device (4) so that the deviation from the measured air-fuel ratio from the measured value falls within an allowable value. The air-fuel ratio feedback control is canceled in response to the time detecting means (32) detecting that it is in the transient state, and the injection amount is set by open control based on the transient injection amount map (35). An electronic fuel injection engine for a working machine, comprising an open control means (34). 3. An electronic fuel injection engine for a working machine according to claim 2, wherein a throttle valve (5) for controlling an amount of air flowing into the combustion chamber (1) and a pressure in an intake passage are detected. And a valve opening sensor (8) for detecting an opening (θ) of the throttle valve (5).
(34) is a map (23) in which the basic injection amount is set based on the pressure value (p) and the engine speed (n), and the basic injection amount is set based on the valve opening (θ) and the engine speed (n). A map (24) in which the amount is set, and weighting means (25) for weighting the first basic injection amount and the second basic injection amount calculated based on each map according to a predetermined rule. An electronic fuel injection engine for a working machine, wherein an actual injection amount is set based on a weighted injection amount. 4. A fuel injection device (4), target engine speed setting means (37) for setting a target engine speed, engine speed detecting means (9), and a load for detecting a load state applied to the engine. State detecting means, steady state transient detecting means (32) for detecting that the operating state of the engine is transient based on the detected load state, and the steady state transient detecting means (32) is transient. In response to the detection, the fuel injection amount of the fuel injection device (4) is adjusted so that the deviation between the actual engine speed detected by the engine speed detecting means (9) and the target engine speed is within an allowable value. Characterized by comprising a rotation speed feedback control means for controlling
Electronic fuel injection engine for work equipment.