JPH0122460B2 - - Google Patents

Description

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

[Prior art]

In general, engine idle speed control devices are
When the engine is idling, the amount of air-fuel mixture supplied to the engine is adjusted to keep the engine speed constant at a low speed, thereby stabilizing combustibility and improving fuel efficiency. 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 adjust the throttle valve opening. A method of feedback controlling the temperature, etc. is known.

In the case of the former method, even if the initial opening of the throttle valve 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, due to individual differences among engines, this has naturally caused the problem that depending on the engine, the idle speed becomes high and fuel efficiency deteriorates.

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

One of the devices that has solved this problem is conventionally, as shown in Japanese Patent Application Laid-Open No. 113725/1982, which performs estimated correction using a predetermined amount of correction when the external load increases. There is a system in which the rotational speed is increased to around the target rotational speed and feedback control is performed from that state.

In this case, after a load such as a cooler is applied, the control amount of the feedback control is performed using the same control amount as when no load was 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 there is no load, the difference is that when the load is applied, the amount of the mixture is equal to the amount driven by the load. 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 even when the load is not high.

[Purpose of the invention]

In view of these conventional problems, 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. The engine rotation speed is detected, and when the engine is idling, the calculation means 62 calculates the difference between the detected actual engine rotation speed and the target rotation speed, and the control means 63 adjusts the air-fuel mixture with a control amount according to the rotation speed difference. In addition to driving the means 65, the control amount at the time of driving is detected by the load state detecting means 61.
When the external load state of the engine detected by
The value is set to be larger than when it is small.

〔Example〕 Embodiments of the present invention will be described below 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, 1 is an engine, a throttle valve 3 is provided in an intake passage 2 of the engine 1, a fuel injection valve 4 is provided in the intake passage 2 upstream of the throttle valve 3, and a fuel injection valve 4 is provided in the intake passage 2 upstream of the throttle valve 3. Fuel is supplied from a fuel tank 6 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. The regulating valve 10 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. A three-way valve 14 for switching between introducing negative pressure and introducing atmospheric pressure is interposed in the middle of the negative pressure introducing passage 13.

In the figure, 16 is a crank angle sensor that detects the rotation angle of the crankshaft, 17 is a negative pressure sensor that detects the pressure downstream of the throttle valve 3 in the intake passage 2, and 18 is a throttle opening sensor that detects the opening degree of the throttle valve 3. temperature sensor, 19 to 22 are external load detection signals, 19 is a headlight signal that becomes "1" when the headlight is turned on, 20 is a cooler switch signal that becomes "1" when the cooler switch is turned on, 21 is a power steering signal that becomes "1" when the power steering is operated, and 22 is a shift signal that becomes "1" when the transmission is shifted to the D range.

Furthermore, 23 is an input/output interface 24,
It is a control unit composed of a CPU 25 and a memory 26, and the memory 26 includes
It 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 to T5 is a table of the rotational fluctuation amount/control amount characteristics shown by straight lines d1 to d5 in FIG. 4, where d1 is the cooler load, d2 is the power steering load, and d3 is the electric load, d4 is the shift load, and d5 is the characteristic when there is no load. Further, the CPU 25 receives the outputs of the sensors 16, 17, and 18, determines a fuel injection pulse according to the operating state, and sends it to the fuel injection valve 4.
In addition to controlling fuel injection by adding
While determining the difference between the actual engine speed and the preset target speed when the engine 1 is idling, the presence or absence of the load detection signals 19 to 22 is determined, and the control gain table according to the load state is used to determine the difference between the actual engine speed and the preset target speed. Control is performed by determining a control amount from the rotational speed difference, and applying a control signal corresponding to this control amount to the three-way valve 14 to adjust the amount of air-fuel mixture.

In the above configuration, the CPU 25 realizes the functions of the calculation means 62 and control means 63 shown in FIG. 1, and the crank angle sensor 16 and throttle opening sensor 18 perform the idle detection shown in FIG. The crank angle sensor 16 constitutes the means 60, and furthermore, the crank angle sensor 16 serves as the rotation speed detecting means 64. Further, the headlight signal 19, cooler switch signal 20, power steering signal 21 and shift signal 22 are transmitted to the load state detection means 61 of FIG.
The bypass passage 9, the regulating valve 10, the diaphragm device 12, the negative pressure introduction passage 13, and the three-way valve 14 constitute the air-fuel mixture regulating means 65 in FIG.

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

When the engine 1 is cranked to an idle state, the crank angle sensor 16 detects the rotation angle of the crankshaft, the negative pressure sensor 17 detects the intake negative pressure downstream of the throttle valve 3, and the throttle opening sensor 18 detects the intake negative pressure downstream of the throttle valve 3.
detects the opening degree of the throttle valve 3, and the output of each sensor 16 to 18 is sent to the control unit 2.
3 is input. Then, the CPU 25 in the control unit 23 outputs a fuel injection pulse with a pulse width corresponding to the engine speed and intake negative pressure to the fuel injection valve 4, and controls the fuel injection amount according to the operating state of the engine.

Further, the CPU 25 calculates the actual engine rotation speed from the output of the crank angle sensor 16 and calculates the difference between this actual engine rotation speed and a preset target rotation speed.
22 are all "0", the control gain table T5 (see d5 in FIG. 4) corresponding to no load in the memory 26 is used to calculate the control amount D according to the above difference.
5 is determined, and a control signal corresponding to this control amount D5 is output. Then, the three-way valve 14 receives this control signal and introduces negative pressure or atmospheric pressure according to the control amount D5 into the negative pressure chamber of the diaphragm device 12, and the regulating valve 10
increases or decreases the passage area of the bypass passage 9.
By adjusting the amount of intake air flowing through the engine 1, the amount of air-fuel mixture supplied to the engine 1 is increased or decreased, and the engine speed is also increased or decreased.In this way, the engine speed is maintained at the target even with the control amount D5 according to the difference in the speed. Feedback control is applied to the rotational speed.

If an external load is applied to the engine 1 while the engine speed is feedback-controlled to the target speed in this way, the engine speed will decrease due to this load, so as described above, If feedback control is performed with the control amount D5 at no-load, it will take time to reach the target rotational speed.

However, in this device, when an external load is applied alone, the CPU 25 retrieves the control gain tables T1 to T4 (fourth
(see d1 to d4 in the figure), and using this table, select the control amount D1 to D4, which is larger than that at no load.
is determined and feedback control is performed using this control amount, so the engine speed immediately rises and returns to the target speed.Moreover, at this time, the control amount is an appropriate value according to the load condition, so the control Hunting does not occur because the amount is 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,
This table is used to find the control amount according to the rotational speed difference for each load, and each control amount is added to find the final control amount, which also performs feedback control, so in this case as well. The engine speed will be quickly controlled to the target speed.

Next, the operation will be explained in detail using FIGS. 3 and 4. Here, FIG. 3 shows a flowchart of idle rotation speed control among the calculation processes of the CPU 25.

When the engine 1 starts, the CPU 25 first initializes (steps) the registers, etc. in the CPU 25.
30) After that, input information from each sensor 16 to 1
8 and load detection signals 19 to 22 are read through the interface 24 (step 31),
The read engine speed and throttle valve 3
It is determined whether or not the engine is in an idle state based on the opening degree of the engine (step 32). If the engine is not in an idle state, the process returns to step 31 and cycles through the routes of steps 31 and 32. Conversely, when the engine is in an idle state, the routine proceeds to step 33, where it is determined from the read load detection signals 19 to 22 whether two or more loads are being applied to the engine 1, that is, whether there is a multiple load.

If there is no multiple load, the CPU 25 proceeds to step 34 and retrieves control gain tables T1 to T5 corresponding to the type of no load or single load from the memory 26.
After selecting the engine speed, the difference between the actual engine speed and the target speed is calculated (step 35), and it is further determined whether the above difference is within the dead band (step 35).
36), if the difference is the value of the dead band material, proceed to step 37 to determine whether the actual rotation speed is higher than the target rotation speed, and if the actual rotation speed is lower, proceed to step 38
Then, using the control gain tables T1 to T5 selected above, the control amounts D1 to D5 corresponding to the above differences for increasing the actual rotational speed are determined, and conversely, if the actual rotational speed is higher, in step 39, the above Using the control gain tables T1 to T5, control amounts D1 to D5 are determined according to the above-mentioned difference for lowering 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.

Then, if we calculate the control amount as above,
The CPU 25 proceeds to step 49, calculates an output value from the control amounts D1 to D5 obtained above, and performs output processing using the obtained output value (step 50), whereby a control signal is applied to the three-way valve 14. The amount of intake air in the bypass passage 9 is controlled.

If it is determined in step 33 that there are multiple loads, the CPU 25 proceeds to step 41, selects from the memory 26 control gain tables T1 to T4 corresponding to the types of loads applied to the engine 1, and then selects the control gain tables T1 to T4 corresponding to the types of loads applied to the engine 1. The difference between the rotational speed and the target rotational speed is calculated (step 42), and it is determined whether the calculated difference is within the dead band (step 43). If the difference is outside the dead band, the process proceeds to step 44. It is determined whether the actual rotation speed is higher than the target rotation speed or not. If the actual rotation speed is lower, proceed to step 45 and increase the actual rotation speed using each of the control gain tables T1 to T4 selected above. The control amounts D1 to D4 are determined for each load according to the difference in the rotational speeds to reduce the actual rotational speed.Conversely, if the actual rotational speed is higher, proceed to step 46 and set the above rotational speed to lower the actual rotational speed. Determine control amounts D1 to D4 for each load according to the difference between
The final control amount is determined by adding the respective control amounts D1 to D4 (step 47), and the steps 49 and 50 described above are then performed.
Follow the route.

In the device of this embodiment as described above, when an external load is applied to the engine during idling, the actuator is driven with a control amount corresponding to the load, and when multiple loads are applied, each load is Since the final control amount is obtained by adding up the control amounts obtained at each time, the engine speed can be quickly controlled to the target rotation 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 obtain the control amount, and these are added to obtain the final control amount. When multiple loads are applied in this manner, the loads may be prioritized, and the control amount for the load with the highest priority may be determined and used as the final control amount.

FIG. 5 shows a flowchart of the arithmetic processing of the CPU 25 in another embodiment of the present invention in which control is performed according to the priority order of the loads in the case of multiple loads. In the figure, the same reference numerals as in FIG. 3 indicate the same parts as in the same figure, and 51 to 54 are determination steps for determining whether a cooler load, a power steering load, an electric load, or a shift load is applied to the engine 1, respectively. , 55 to 59 are control gain tables corresponding to the cooler load, power steering load, electrical load, shift load, or no load (d1 to d in FIG.
5)).

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 was provided for each load, but the present invention provides a control gain table regardless of the type of load.
Only one control gain table may be provided. Moreover, the load may be other than the cooler, power steering, shift, and electrical load. Furthermore, the fuel supply means may be a carburetor instead of a fuel injection valve.

〔Effect of the invention〕

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 speed fluctuation amount is set to a larger value as the current external load condition is larger. Therefore, regardless of the type of load, the response during load fluctuations can be improved, and the hunting phenomenon near the target rotation speed can be minimized.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention.
Fig. 2 is a block diagram of an engine idle speed control device according to an embodiment of the present invention, Fig. 3 is a flowchart of arithmetic processing of the CPU 25 in the above device, and Fig. 4 is a rotation fluctuation amount in the above device. FIG. 5 is a diagram showing a flowchart of the arithmetic processing of the CPU 25 according to another embodiment of the present invention, and FIG. 6 is a diagram showing the characteristics of the control amount with respect to the rotational fluctuation amount in the above device. It is. 1... Engine, 60... Idle detection means,
65...Mixture adjustment means, 61...Load condition detection means, 64...Rotation speed detection means, 62...Calculation means, 63...Control means, 16...Crank angle sensor, 18...Throttle opening sensor , 25...
CPU.

Claims (1)

[Claims] 1 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 state of external load applied to the engine; and detection means for detecting the rotational speed of the engine. 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 state detection means receiving the output of the means and the output of the calculating means, determining a control amount for driving the air-fuel mixture adjusting means according to the magnitude of the difference obtained by the calculating means, and determining the control amount for the difference; An engine idle speed control device comprising control means for controlling a value larger when the external load is large than when it is small, depending on the magnitude of the external load state.