JPS6035152A - Control device of idle speed in engine - Google Patents

Abstract

PURPOSE:To suppress a hunting phenomenon in idle operation of an engine to a minimum limit, by adjusting a control amount in accordance with an external load of the engine, in the case of a control device which controls a mixture adjusting means by the control amount corresponding to the difference between an actual speed of the engine and its target speed. CONSTITUTION:A mixture adjusting means 65, which adjusts the amount of a mixture so as to control an idle speed by means of controlling the opening of a regulating valve provided in a bypass passage bypassing a throttle valve in an intake air passage, is provided and controlled by a central processing unit (CPU) 25. This CPU25 is formed by providing an arithmetic means 62, which receives outputs of an idle detecting means 60 and a speed detecting means 64 so as to obtain a difference between the speed of an engine and its target speed when the engine is in idle operation, and a control means 63 which inputs an output of the arithmetic means 62 and an output of a load condition detecting means 61 detecting the condition of an external load applied to the engine by a cooler or the like. Then a control amount obtained in accordance with the output of the arithmetic means 62 is adjusted in accordance with the condition of the external load.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine idle speed control device.

[Prior art]

- When the engine is idling, the engine idle speed control device adjusts the amount of air-fuel mixture supplied to the engine to control the engine speed to a constant low speed, thereby stabilizing combustibility and improving fuel efficiency. This is what I tried to do. Conventionally, there are two methods for controlling the idle speed to a constant value: one is to give the throttle valve an initial opening (idle opening) at the time of manufacture, and the other is to detect the actual engine speed and control the throttle valve opening. A method of feedback controlling the degree, etc. is known.

In the case of the former method, even if the initial throttle valve opening is the same, the actual engine speed will vary due to manufacturing errors and individual differences in engine characteristics. I had to set it higher. However, if this is done, there is a problem in that, due to individual differences among engines, the idle speed of some engines becomes high and fuel efficiency deteriorates.

On the other hand, the latter method using feedbank control has the advantage that the idle rotation speed can be maintained at a desired target rotation speed regardless of manufacturing errors, individual differences, etc., and good fuel efficiency can be guaranteed. In conventional idle speed control devices that employ such feedbank control, if the operating tension (control amount) of the actuator, etc. is set to a large value relative to the difference (rotation fluctuation amount) between the actual engine speed and the target speed, The control amount was set to a relatively small value to avoid the hunting phenomenon of the control, but in this way, if the engine speed suddenly decreases due to an external load such as a cooler, There was a problem that it took a long time to reach the target rotational speed again, or that if the rotational speed decreased extremely, the engine stalled.

One of the devices that solves this problem is the one disclosed in Japanese Patent Laid-Open No. 54-113725, which performs estimated correction using a predetermined amount of correction when the external load increases to adjust the engine speed. There is a system in which the rotation speed is increased to around the target rotation speed, and feedback control is performed from that state.

In this case, after a load such as a cooler is applied, the feedback control is performed using the same control amount as when no load is applied, which causes a problem that it takes time to reach the target rotation speed. In other words, if you increase or decrease the predetermined mixture amount when a load is applied, or if you increase or decrease the predetermined mixture amount when no load is applied, only the driving bone of the load will be affected when the load is applied. Since the amount of variation in rotation is small, the control amount must be adjusted several times until the target rotation speed is reached. If a large control amount is set in advance here, hunting will occur as described above when no load is applied.

[Purpose of the invention]

In view of these conventional problems, the present invention has been developed in a unique way.
.

It is an object of the present invention to provide an engine idle speed control device that can improve responsiveness and minimize hunting regardless of the type of load.

[Structure of the invention]

Therefore, as shown in the functional block diagram of FIG. 1, the present invention provides an engine idle speed control device in which an idle state of the engine is detected by an idle detection means 60, and an engine speed is detected by a rotation speed detection means 64. When the engine is idling, the calculating means 62 calculates the difference between the detected actual engine speed and the target engine speed, and the control means 63 drives the air-fuel mixture adjusting means 65 with a control amount according to the difference in engine speed. At the same time, the control amount during the drive is increased or decreased in accordance with the external load state of the engine detected by the load state detection means 61.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an engine idle speed control device according to an embodiment of the present invention. In the figure, l is an engine, a throttle valve 3 is provided in an intake passage 2 of the engine 1, and a fuel injection valve 4 is provided in the intake passage 2 upstream of the throttle valve 3.
is provided, and fuel from a fuel tank 6 is supplied to the fuel injection valve 4 by a fuel pump 5 via a regulator 7. Further, the upstream end of the intake passage 2 is connected to an air cleaner 8.

A bypass passage 9 is formed in the intake passage 2 by bypassing the throttle valve 3 and the fuel injection valve 4, and the bypass passage 9 is provided with an adjustment valve 10 for adjusting the area of the passage. This regulating valve lO is provided with a diaphragm device 12 for driving it, and the diaphragm device 12
is provided with a negative pressure introduction passage 13 that communicates the negative pressure chamber with the downstream side of the throttle valve 3 of the intake passage 2, and in the middle of the negative pressure introduction passage 13, the introduction of negative pressure and the introduction of atmospheric pressure are provided. A three-way valve 14 for switching is provided.

In the figure, 16 is a crank angle sensor that detects the rotation angle of the crankshaft, and 17 is a throttle valve 3 in the intake passage 2.
A negative pressure sensor 18 detects the downstream pressure, a throttle opening sensor 19 to 22 detects the opening of the throttle valve 3.
is the external load detection signal, 19 is the headlight signal that becomes 1" when the headlight is turned on, 2o is the cooler switch signal that becomes "1" when the cooler switch is turned on, and 21 is the power steering operation. 1 when
22 is a shift signal that becomes "1" when the transmission is shifted to the D range.

Furthermore, 23 is a human output interface 24. cPU25
and a memory 26, and the memory 26 stores arithmetic processing programs for the CPU 25, control gain tables T1 to T5 for each load, and the like. Here, each of the above control gain tables T1~
T5 is a table of the rotational fluctuation amount/control amount characteristics shown by straight lines d1 to d5 in Fig. 4, where dl is the cooler load, d2 is the power steering load, d3 is the electrical load, d4 is the shift load, d5 is the characteristic when no load is applied.

Further, the CPU 25 receives the outputs of the sensors 16, 17, and 18, performs fuel injection control such as generating a fuel injection pulse according to the operating state and applying it to the fuel injection valve 4. While calculating the difference between the actual engine rotation speed and the preset target rotation speed, it also determines the presence or absence of load detection signals 19 to 22, and performs control based on the rotation speed difference using a control gain table according to the load condition. A control signal corresponding to the controlled amount is sent to the three-way valve 1.
In addition to step 4, this control also adjusts the amount of air-fuel mixture.

In the above configuration, the CPU 25 realizes the functions of the calculation means 62 and the control means 63 shown in FIG. 1, and the crank angle sensor 16 serves as the rotation speed detection means 64. Also headlight signal 19. Cooler switch signal 20. The power steering signal 21 and the shift signal 22 are the detection signals of the load condition detection means 61 shown in FIG. Diaphragm device 12. The air-fuel mixture adjustment means 65 in FIG.
It consists of

Next, the general operation of this device will be explained.

When the engine 1 is cranked and becomes idle, the crank angle sensor 6 detects the rotation angle of the crankshaft, and the negative pressure sensor 7 detects the intake negative pressure downstream of the throttle valve 3.
The throttle opening sensor 8 detects the opening of the throttle valve 3, and the outputs of the sensors 16 to 18 are input to the control unit 23. Then, the CPU 25 in the control unit 23 sends a fuel injection pulse to the fuel injection valve 4 with a pulse width corresponding to the engine speed and intake negative pressure.
The fuel injection amount is controlled according to the engine operating condition.

Further, the CPU 25 obtains the actual engine rotation speed from the output of the crank angle sensor 6 and calculates the difference between this actual engine rotation speed and a preset target rotation speed. 22 are all "0", the control gain table T corresponding to no load in the memory 26
5 (see d5 in FIG. 4) to determine the control amount D5 according to the above-mentioned difference, and output a control signal according to this control amount D5. Then, the three-way valve 14 receives this control signal and applies negative pressure or atmospheric pressure to the diaphragm device 12 according to the control amount D5.
The regulating valve 10 increases or decreases the passage area of the bypass passage 9 to adjust the amount of intake air flowing through the passage 9,
As a result, the amount of air-fuel mixture supplied to the engine 1 increases or decreases, and the engine rotational speed also increases or decreases, and thus the engine rotational speed is feedback-controlled to the target rotational speed using the control amount D5 according to the rotational speed difference.

If an external load is applied to the engine 1 while the engine speed is being feedback-controlled to the target speed, this load will cause the engine speed to drop. If feedback control is performed using the no-load control amount D5, it will take time to reach the target rotational speed.

However, in this device, when an external load is applied alone, the CPU 25 reads control gain tables T1 to T4 (d1 to d in FIG. 4) according to the type of load from the memory 26.
4) is selected, and using this table, the control variables D1 to D4, which are larger than those under no-load conditions, are determined. Feedback control is performed using these control variables, so the engine speed immediately increases to the target speed. Since the control amount is an appropriate value according to the load condition, hunting will not occur due to the control amount being too large.

In addition, in the case of so-called multiple loads in which two or more loads are applied, the CPU 25 selects a control gain table according to the type of each load from the memory 26, and uses this table to determine the rotation speed for each load. The control amount is determined according to the difference, and each control amount is added to determine the final control amount, which is used to perform feedback control, so that the engine speed quickly reaches the target speed in this case as well. It will be controlled.

Next, the operation will be explained in detail using FIGS. 3 and 4. Here, FIG. 3 shows a flowchart of idle rotation speed control of the CPO25m calculation process.

When the engine 1 starts, the CPU 25 first
After initializing the registers etc. in 25 (step 30), input information such as the output of each sensor 16 to 18 and load detection signals 19 to 22 is read via the interface 24 (step 31), and the read engine It is determined whether or not the engine is in the idle state based on the rotational speed and the opening degree of the throttle valve 3 (step 32). If the engine is not in the idle state, the process returns to step 31 and cycles through the paths of steps 31 and 32.

On the other hand, when the engine is in an idle state, the process proceeds to step 33, and it is determined from the read load detection signals 19 to 22 whether two or more loads are applied to the engine 1, that is, whether there is a multiple load.

If there is no multiple load, the CPU 25 performs step 34.
After proceeding to step 35), select control gain tables T1 to T5 corresponding to the type of no-load or single load from the memory 26, and then calculate the difference between the actual engine speed and the target 2 speed (step 35). Step 36) to determine whether the above-mentioned difference is a value within the dead zone.
When the difference is a value outside the dead band, the process proceeds to step 37, where it is determined whether the actual rotation speed is higher than the target rotation speed, and when the actual rotation speed is lower, at step 38, the control gain table T1 selected above is determined. ~ T5 is used to determine the control amounts D1 to D5 according to the above-mentioned difference in order to increase the actual rotational speed, and conversely, if the actual rotational speed is higher, the control gain tables T1 to T5 are determined in step 39. Control amounts D1 to D5 are determined in accordance with the above-mentioned difference to reduce the actual rotational speed. If it is determined in step 36 that the difference in rotational speed is within the dead zone, the process proceeds to step 40 and the control amount is set to zero.

After determining the control amount as described above, the CPU 25 proceeds to step 49, calculates the output value from the control amount D1 to D5 obtained above, and performs output processing using the requested output value (step 50). As a result, a control signal is applied to the three-way valve 14 to control the intake air amount in the bypass passage 9.

3 If it is determined in step 33 that there are multiple loads, the CPU 25 proceeds to step 41 and selects from the memory 26 control gain tables T1 to T4 corresponding to the type of each load applied to the engine 1. , calculate the difference between the actual rotation speed and the target rotation speed (Step 42), and determine whether the calculated difference is within the dead zone (Step 4).
3) If the difference is a value outside the dead band, the process proceeds to step 44 to determine whether the actual rotation speed is higher than the target rotation speed, and if the actual rotation speed is lower, the process proceeds to step 45. Using each of the selected control gain tables T1 to T4, set control amounts D1 to D4 for each load in accordance with the difference in the above rotational speeds to increase the actual rotational speed, and conversely, when the actual rotational speed is higher. The process proceeds to step 46, where control amounts D1 to D4 are determined for each load in accordance with the difference in the rotation speed to reduce the actual rotation speed, and each control amount D1 to D4 is added to obtain the final control amount. (step 47), followed by step 49 above.
．． Follow 50 routes.

In the device of this embodiment as described above, when an external load is applied to the engine at idle, the actuator is driven with a control amount corresponding to the load, and when multiple loads are applied. Since the final control amount is determined by adding the control amounts determined for each load, the engine speed can be quickly controlled to the target speed with good responsiveness. Moreover, since the control amount at this time is an appropriate amount according to the load state, hunting near the target rotation speed can also be suppressed to a minimum.

By the way, in the above embodiment, when multiple loads are applied, a control gain table is selected for each load, each table is used to determine the control amount, and these are added to determine the final control amount. However, when multiple loads are applied like this, it is possible to prioritize the loads, set the amount of control for the load with the highest priority, and use this as the final amount of control. good.

FIG. 5 shows C of another embodiment of the present invention in which control is performed according to the priority order of loads in the case of multiple loads.
Flowchart 5 of the arithmetic processing of P U 25 is shown. In the figure, the same reference numerals as in FIG. 3 indicate the same parts as in the same figure, and 51 to 54 represent a Tara load and a power steering load for the engine 1, respectively.

Judgment steps 55 to 59 for determining whether an electrical load or a shift load is applied, respectively, retrieve control gain tables (corresponding to cooler load, power steering load, electrical load, shift load, or no load) from the memory 26.
(see dl-d5 in FIG. 6).

Since the operation of this embodiment is easy to understand, the explanation will be omitted, but in this embodiment as well, similar to the above embodiments, we aim to improve responsiveness during transients caused by external loads and suppress hunting phenomena. It can be achieved.

In both of the above embodiments, a control gain table is provided for each load, but in the present invention, only one control gain table may be provided regardless of the type of load. Moreover, the load may be other than the tarla, power steering, shift, and electric load. Furthermore, the fuel supply means may be a carburetor instead of a fuel injection valve.

〔Effect of the invention〕

6 As described above, according to the present invention, in the engine idle speed control device that performs feedback control of the engine speed, the control amount for the rotation fluctuation amount is increased or decreased according to the current load condition. This has the effect of improving responsiveness during load fluctuations regardless of the type of load, and minimizing the hunting phenomenon near the target rotation speed.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram of an engine idle speed control device according to an embodiment of the present invention, and FIG. 3 is a flowchart of the arithmetic processing of the CPU 25 in the above device. 4 is a diagram showing the characteristics of the control amount with respect to the amount of rotational fluctuation in the above device, FIG. 5 is a diagram showing a flowchart of the calculation processing of the CPU 25 according to another embodiment of the present invention, and FIG. It is a figure which shows the characteristic of the control amount with respect to the amount of rotation fluctuation|variation in . 1... Engine, 60... Idle detection means, 65
... Air-fuel mixture adjustment means, 61... Load state detection means,
67 4... Rotation speed detection means, 62... Calculation means, 63.
... Control means, 16... Crank angle sensor, 18...
- Throttle opening sensor, 25...CPU. Patent applicant Toyo Kogyo Co., Ltd. (one other person) Representative Patent attorney Ken Hayase - 8

Claims (1)

[Claims] (11) Idle detection means for detecting the idle state of the engine, mixture adjustment means for adjusting the amount of air-fuel mixture supplied to the engine, load state detection means for detecting the external load state applied to the engine, and a calculation means that receives the output of the idle detection means and the output of the rotation speed detection means and calculates the difference between the engine rotation speed at idle and a preset target rotation speed, and the load Receiving the output of the state detection means and the output of the calculation means, driving the air-fuel mixture adjustment means with a control amount according to the output of the calculation means, while increasing or decreasing the control amount in accordance with an increase or decrease in the external load state. What is claimed is: 1. An engine idle speed control device comprising: a control means;