JPS63150446A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To stabilize a running state and to improve workability of a working machine, by a method wherein, in reverse droop control coping with an increase in the number of revolutions of an engine during increase of a load and a temporary increase in a load, the number of revolutions of an engine is steppedly changed. CONSTITUTION:In engine 1, an engine output and torque are decided by means of an injection quantity and the injection timing of a fuel injection pump 2 and the number of revolutions of an engine. In this case, the number of revolutions of an engine detected by a number of revolutions sensor 7 and a fuel injection quantity, detected by a position sensor 5 for detecting the actuating position of an actuator 3 of a fuel injection quantity regulating lever 10 are inputted to a control part 20. By means of a control part 20, a load rate is calculated from a deference between the actual value and the set value of the number of revolutions of an engine, and it is decided whether a load rate exceeds an allowable value and whether it is reduced to the allowable value or less from a state that it exceeds the allowable value. This constitution gradually increases and decreases a set value, and decides a target fuel feed amount being gradually changed from the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for an internal combustion engine that eliminates instability in the operation of the internal combustion engine when the load factor increases.

<Prior art> In general, when an internal combustion engine is operated below the peak torque rotation speed, when the load increases, the rotation speed decreases, and as the rotation speed decreases, the shaft torque decreases, resulting in a vicious cycle in which the rotation speed further decreases. This may occur. Therefore, the applicant
Japanese Patent Application No. 59-196170 (Japanese Unexamined Patent Publication No. 1986-1961) proposes to automatically increase the rotation speed when the load suddenly increases to cope with the increase in load.
721346) has already been proposed. Hereinafter, such control will be referred to as reverse droop control in this memorandum.

<Problems to be Solved by the Invention> In the device proposed above, the amount of increase in rotation speed applied when the load factor exceeds an allowable value is set in the form of a map corresponding to the set value of rotation speed. , the rotational speed is changed by the amount commensurate with the increase. However, since the rotation speed changes rapidly, there is a shock and the operation feeling is poor.Also, in operations that require constant speed operation, such as digging potatoes with agricultural machinery, if the rotation speed suddenly increases, the harvest will be damaged. Inconveniences may occur, such as dirt becoming more likely to get mixed into the engine, and rapid changes in rotational speed may also have a negative effect on the life of the engine.

The present invention has been made in view of the above-mentioned problems and has an object of providing a control device for an internal combustion engine in which the rotational speed changes smoothly during reverse droop control.

Means for Solving the Problems> In order to achieve the above object, the control device of the present invention includes an engine rotation speed detection means for detecting the actual value of the engine rotation speed and a set value of the engine rotation speed. A set rotation speed detection means to detect the relationship between the rotation speed and the load factor, which is used as a criterion for determining whether the load factor has exceeded the allowable value and whether it has fallen below the allowable value from a state exceeding the allowable value. A memory means for remembering,
an increase amount setting means for specifying an amount of increase in the set value of the engine speed when the load factor exceeds the allowable value; and a load factor is calculated from the difference between the detected actual value of the engine speed and the set value; Based on the data stored in the storage means, it is determined whether the load factor exceeds the permissible value and whether the load factor has fallen below the permissible value from the state exceeding the permissible value, and if it has exceeded the permissible value, the increase amount setting means increases the load factor. Gradually increase the set value to the value with the added amount, and if the value falls below the allowable value from exceeding the allowable value, gradually increase the set value from the value with the increased amount added to the value without adding the increased amount. a calculation means for determining a target fuel supply amount that gradually changes according to the set value and outputting a control output; and a fuel control means for adjusting the fuel supply amount based on the control output of the calculation means. ing.

<Operation> The internal combustion engine control device of the present invention is configured as described above, and when the load factor exceeds a certain value, the rotation speed is automatically increased to cope with the increase in load. Since the number changes gradually rather than abruptly, the operator will not be shocked and workability will not be adversely affected.

<Example> Hereinafter, an illustrated example regarding control of a diesel engine will be described.

[A] Overall configuration and basic control In the conceptual system diagram shown in Figure 1, 1 is the engine, 2 is the fuel injection pump, 3 is the rack actuator, 4 is the timer actuator, and 5 and 6 are the actuators for each actuator. Position sensor, 7 is rotation speed sensor, 8 is accelerator position sensor, 9
is the accelerator.

The engine output and torque of the engine 1 are determined by the injection amount and injection timing of the fuel injection pump 2 and the engine rotational speed. The fuel injection amount is adjusted by moving a fuel rack (not shown) of the fuel injection pump 2 via an injection amount adjustment lever 10 by an actuator 3 using a linear solenoid, a stepping motor, or the like. As a governor including the rack actuator 3, etc., there is used, for example, the one shown in FIG. 2 of the above-mentioned Japanese Patent Application Laid-Open No. 61-72846.

In addition, the injection timing is adjusted by changing the prestroke or changing the cam phase, and these changes are made mechanically or by using hydraulic pressure, and by using a linear solenoid, stepping motor, electromagnetic valve, etc. via the timing adjustment lever 11. This is done by actuator 4. The engine speed is detected, for example, by detecting the movement of the concave groove 13 of the magnetic rotating body 12 attached to the camshaft with a rotation speed sensor 7 consisting of an electromagnetic pickup, and the fuel injection amount is determined in advance based on the rack position. By measuring the injection amount according to the engine speed,
It can be known by detecting the operating position of the actuator 3 with a position sensor 5 such as a differential transformer and simultaneously detecting the engine rotation speed.

14 indicates a nozzle.

2o is a control unit that controls the operating state of the engine according to instructions from the operator. A microcomputer is used as this control section, and an I10 control ROM 21. A CPU 22 that gives control calculations and input/output instructions, a RAM 23 used for control calculations of the CPU 22, a program ROM 24 that stores a pg control program, and stores various data necessary for control calculations such as speed fluctuation rate characteristics to be described later. It is composed of a data ROM 25 and the like.

The data ROM 25 contains the set value of the engine speed, which is arbitrarily set by the position of the accelerator operated by the operator of his/her own will, and the speed fluctuation rate characteristic, which shows how the actual speed (actual value) changes depending on the load. are stored in the form of arithmetic expressions or numerical tables for each type of work that requires different speed fluctuation rate characteristics. The case of the numerical table will be explained below. Table 1 is an example of the i-th numerical table (hereinafter referred to as droop rate map), where the set value N5et and the actual value Nact
Di at the intersection point indicates the droop coefficient in each case.

In addition, the no-load equivalent rack position map shown in Table 2 which defines the relationship between the no-load fitting rotation speed N1dl corresponding to the set value N set and the corresponding rack position, that is, the no-load equivalent rack position Ridl, Maximum rack position maps shown in Table 3 determined to limit the maximum injection amount at various rotational speeds are stored in the data ROM 25, respectively.

Note that even if N1dl in Table 2 above is replaced with N set, and Nmax in Table 3 is replaced with N act, they are substantially the same.

As mentioned above, the droop rate map is created for each of a plurality of control modes having different speed fluctuation rate characteristics, but for the sake of simplifying the explanation below.

i=1 and i=2. That is, a case will be described in which two maps, control mode 1 and control mode 2, are used. In Fig. 1, -127 is a control mode selection switch for selecting a predetermined one from among these plural modes, and the 1 selection instruction is recognized by the on/off state of the switch and is made by logical judgment on the control program. ,
It has the ability to always select one of the modes.

FIG. 2 shows an example of the relationship between engine speed, engine shaft torque, and rack position based on these maps, and intermediate values not shown in the table are obtained by interpolation. In FIG. 2, 80 and A2 each indicate the characteristics according to Table 1, B indicates the no-load equivalent rack position according to Table 2, and C indicates the maximum rack position according to Table 3.

Next, the operation will be explained with reference to the control flowchart shown in FIG.

Various signals for recognizing engine status are controlled by I10 control R.
Managed by OM21, converted into a recognizable signal and transmitted to the CP
It is input to U22. The CPL 122 then performs control calculations according to a predetermined program and outputs various control signals.

Regarding the speed fluctuation rate, first, as shown in FIG. 3, the set value N set and the actual value Nact of the engine speed are recognized.

Also read the no-load equivalent rack position Ridl from Table 2,
Next, the state of the control mode selection switch 27 set by the operator is read, and the target rack position 1iRset to be set is calculated based on the droop rate map of i=1 or i=2 depending on the mode. This target rack position Rset corresponds to the target fuel supply amount for obtaining a predetermined actual value Nact for the set value N set of the engine speed, and is based on the detected N sat and N a
Droop coefficient Di obtained from ct according to Table 1 and Table 2
Next, read the maximum rack position Rmax from Table 3 and compare it with the Rset you just found, and if Rset > Rmax.
Otherwise, a control signal for setting the actual rack position Ract to Rset is output from the CPU 22 to the rack actuator 3, and R set ) Rma
If x, then the CPU 22 sends a control signal to correct Rset = RIIIax so that the rotation speed does not exceed the allowable value, and to change the actual rack position Ract to the corrected target rack position Rset. output to the actuator 3. In this way, the rack position of the fuel pump 2 is automatically adjusted, and the fuel pump 2 is operated at a predetermined speed fluctuation rate.

The plurality of speed fluctuation rate characteristics in the above explanation are selected depending on the work content, and in Fig. 2, control mode 2 is a special case where the speed fluctuation rate is zero, that is, a constant speed control characteristic. It shows. Such constant speed control is used for work that requires constant speed operation, such as rotary, plowing, potato digging, and the like.

In this way, one of the control modes is a constant speed characteristic.

In the case of
An example using ift will be described.

FIG. 4 shows the control mode selection procedure,
Constant speed control is based on the assumption that the operator is not operating the accelerator, so when the control mode selection switch 27 is set to mode 2, it is first checked whether the accelerator is fixed, and the accelerator is fixed. If the accelerator is being accelerated or decelerated, mode 1 droop control is selected regardless of the control mode selection switch 27.

When mode 2 is selected, as shown in FIG. 5, the set value N5et and the actual value N act are first compared, and the corrected set value N5et' is determined by the following calculation formula %. The correction coefficient N5ift is a value set in advance through preliminary experiments depending on the structure and rating of the engine. Next, the target rack position Rset is calculated in the same manner as in FIG. 4, but when N5et' is determined, this N5et' is used instead of the set value N5et set by the accelerator.

In this way, the rack is moved to the target rack position based on the corrected set value, and constant speed control is performed.

(B) Reverse droop control method according to the present invention Basic reverse droop control according to the present invention will be explained.

Assume that the load increases while droop control or constant speed control is being performed according to the above procedure.

The rotational speed at that time is the peak torque rotational speed N shown in Figure 2.
If it is between p and rated rotation speed Nr, if the rotation speed decreases due to an increase in load, the shaft torque will conversely increase, so if the load is within a range where the rotation speed and shaft torque can be balanced, the rotation speed will decrease to some extent. operation continues at a position that balances the load.

However, in the case of work with a small load, if the load increases while operating at a rotation speed lower than the peak torque rotation speed Np, the rotation speed will decrease and the shaft torque will increase up to the maximum torque line (maximum rack line). , more load is added, maximum torque #! (Maximum Rack IIA), the shaft torque will drop rapidly and the rotational speed will drop accordingly, making stable operation impossible. This is prevented by droop control.

In Figure 2, D is a reference line for determining whether the load factor exceeds the allowable value, and E is a reference line for determining whether the load factor has returned to within the allowable value, as shown in Table 4 below. A rotation up load factor map and a rotation return load factor map as shown in Table 5 are stored in the data ROM 25, respectively. Although not shown in the figure, the rotation up amount map shown in Table 6 is also stored in the ROM 25, and the following control is performed using each of these maps.

First, as shown in Fig. 6(a), the actual value N of the engine speed
act and the actual rack position Ract, calculate the no-load equivalent rack position Ridl and the maximum rack position Rmax from Tables 2 and 3, and calculate the load factor L a at that time using the following formula.
ct is required. Note that the intermediate values in Tables 2 and 3 are obtained by interpolation calculation.

Next, as shown in FIG. 6(b), the actual value of the rotation speed N a
ct is applied to Table 4 to find the load factor Lup, which is a criterion for determining whether the load factor for the rotational speed at that time exceeds the allowable value.

Further, as shown in FIG. 6(C), the set value N s of the rotation speed
et is applied to Table 6 to determine the amount of increase N nup by which the set value is increased. The intermediate values of the table are each determined by interpolation calculation.

These calculations are performed every t1 time at regular intervals, and the calculated Lact, Lup, and Nnup are used to calculate the seventh
The set value of the rotation speed is controlled by the procedure shown in the figure.

In Fig. 7, Nnup' is the set value increase amount each time, Nupl is the unit increase amount each time, and N
nup' is initially O, and Nup is a preset constant small value. First, compare the load factor Lact at that time with the reference value Lup just obtained, and if Lact>Lup, add Nup1 to the previous Nnuρ′ and
Correction setting value N5et obtained by adding nup' + N up□ to the setting value N5et set by the accelerator
2 is calculated. Then, the target rack position Rset corresponding to this correction set value N5et2 is calculated in the same way as in the case of FIG. 3, and a control signal is output. The rotation speed increases.

This larva production is repeated every t1 hours, and Nnup' becomes N
up, and the rotational speed increases step by step accordingly. This Nnup' is the final increase amount N according to Table 6.
It is compared with nup every time, and Nnup'≧N nu
When p is reached, Nnup' is fixed as Nnup&:,
The engine 1 is now operated at a rotational speed of N5et2=N5et+Nnup. In this way, the operating point moves along line F in FIG. 2, and operation is performed to cope with the temporary increase in load. Note that if it is not Lact)Lup, the set value is not changed as N5et2=N5et.

In this way, when reverse droop control is performed to temporarily increase the rotation speed, the actual rotation speed value Nact is applied to Table 5 as shown in FIG. 6(d), and the rotation speed at that time is determined. The load factor L down, which is the criterion for determining whether the load factor for the number has returned to within the allowable value, is calculated, and this L down
Using n, the above Lact, and Nnup, control is performed to return the rotational speed to the original speed according to the procedure shown in FIG. The intermediate values in the table are determined by interpolation calculations.

In other words, the load factor L act at that time is compared with the reference value Ldo%in just obtained, and if the operating point moves along the line G and becomes L act (L down), the preset unit is Using the down amount Nup, Nnup' is gradually decreased by Nup2 every t2 time until the corrected set value N5et2 becomes the original set value N5et.

Therefore, the operating point moves along the line H and returns to the original position 1
Engine 1 has the set value N5e set by the accelerator.
The engine returns to the state where it is operated at the rotational speed of t. Furthermore, L
When act < L down and a large load continues to be applied, N 5et2 = N set
+Nnup remains and the set value is kept high.

In the above embodiment, the final increase amount N nup is set by storing it in the ROM 25 and calculating it using Table 6, but this can also be done by another setting means such as an external setting volume. .

(C) Releasing reverse droop control As mentioned above, this invention can withstand a temporary increase in load by automatically increasing the engine speed and increasing the output when the load factor increases. This increases the margin for load fluctuations, so
Overall, the operating condition becomes stable and work efficiency can be improved, and a great effect can be obtained especially when operating at a rotation speed lower than the peak torque rotation speed. Since the rotational speed is increased in stages, there is no shock to the operator and good operability is achieved. Note that increasing the rotation speed without the operator's accelerator operation is extremely dangerous in the case of a car and must be avoided, but it is not dangerous in the case of a working machine such as a tractor.

However, if this is determined to be an increase in load when one brake is applied during a turn, for example, reverse droop control is performed, increasing the vehicle speed and making it difficult to turn. Also,
If you place emphasis on the PTO rotation speed and do not want to change the rotation speed to the limit of the load, or if you can predict that the load fluctuation will be temporary, it may not be necessary to perform this reverse droop control. , or there are things you don't want to do.

Therefore, in this embodiment, this reverse droop control is not performed when the brake is operated, and the operator can select whether or not to perform this control according to his/her intention.

In FIG. 1, 30 is a reverse droop control on/off switch, and 31 is a brake switch.The on/off states of these are input to the control unit 20 via the I10 control ROM 21, and the control is performed according to the procedures shown in FIGS. 9 and 10. It will be done.

These procedures are the same as those in FIGS. 7 and 8 with the addition of a step for determining the on/off state of each switch.

That is, in FIG. 9, the engine speed setting value N5e
After recognizing t, reverse droop control on/off switch 30
The state of the brake switch 31 is determined, and only when the former is on and the latter is off, control moves to stepwise increase of the rotation speed as shown in Fig. 7, even if the on/off of either switch is the reverse of the above. There is no tobacco control.

Also, Fig. 10 shows the case where the line-of-sight droop control is activated, and the rotation speed shown in Fig. 8 is controlled to be returned to the original value in stages only when the reverse droop control on/off switch 30 is on and the brake switch 31 is off. be exposed. When the reverse droop control on/off switch 30 is turned off or the brake switch 31 is turned on by operating the brake, the reverse droop control is immediately canceled and the rotation speed returns to its original value.

Although the above embodiments are for a diesel engine, the control according to the present invention can also be applied to a gasoline engine, for example, by making modifications according to the type of engine. In this case, the throttle opening corresponds to the rack position in the embodiment.

<Effect of the invention> As is clear from the above description, this invention has the following features.

In reverse droop control, which deals with temporary increases in load by increasing the rotation speed and increasing the output when the load increases, the rotation speed is changed in stages, and this prevents load factor fluctuations. The advantage of reverse droop control is that it improves workability in each task because the margin is increased and the operating condition is stabilized, and the change in rotation speed is smoother, improving the operation feeling of the work equipment and the work. This has the effect of improving the performance of the engine, and reducing the possibility that a large force will be momentarily applied to the engine and adversely affect the engine's lifespan.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a conceptual system diagram, Fig. 2 is a characteristic diagram showing the relationship between engine speed, rack position, and shaft torque, and Figs. 3 to 5 are basic diagrams. FIGS. 6(a) to 8 are flowcharts of basic control according to the present invention, and FIGS. 9 and 10 are flowcharts of control according to the embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 2... Fuel injection pump, 3... Rack actuator, 7... Rotation speed sensor, 8...
Accelerator position sensor, 9... Accelerator, 20... Control unit, 22... CPU, 25... Data ROM, 3
0... Reverse droop control on/off switch, 31...
brake switch. Patent applicant Yanmar Diesel Co., Ltd. Agent
Patent Attorney Shino 1) Actual Figure 1: Figure 2 Figure 4 Figure 6 Figure 6 (a) Figure 6 (C) Figure 6 (d)
Figure 9 Figure 10

Claims (3)

[Claims] (1) An engine speed detection means for detecting the actual value of the engine speed; a set speed detection means for detecting the set value of the engine speed; and a means for detecting the set value of the engine speed; A storage means for storing the relationship between the rotation speed and load factor, which is used as a criterion for determining whether the load factor has fallen below the allowable value, and an increase in the set value of the rotation speed when the load factor exceeds the allowable value. The load factor is calculated from the difference between the actual value and the set value of the detected engine speed, and the load factor is determined based on the data stored in the storage means as to whether the load factor exceeds the allowable value. , and determines whether or not the value has fallen below the permissible value from the state exceeding the permissible value, and if the value has exceeded the permissible value, the set value is gradually increased to a value including the increase amount set by the increase amount setting means, and When the value exceeds the value and falls below the allowable value, the set value is gradually decreased from the value with the increased amount added to the value without the increased amount added, and the target fuel gradually changes in response to this set value. A control device for an internal combustion engine, comprising: a calculation means for determining a supply amount and outputting a control output; and a fuel control means for adjusting the fuel supply amount based on the control output of the calculation means. (2) The motor according to claim 1, which includes a brake detection means, and automatically stops the control to increase the rotation speed when the load factor exceeds a permissible value when the brake is operated. Internal combustion engine control device. (3) The internal combustion engine according to claim 1, which is equipped with a manual control stop means, and is capable of selecting whether or not to perform control to increase the rotational speed when the load factor exceeds a permissible value. Control device.