JPS6153437A - Control device for idling rpm in internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve accuracy of control by A/D converting a current flowing through a linear solenoid, and controlling it to follow a target value in the captioned device having a valve being adapted to by-pass a throttle valve and controlled in its opening by said linear solenoid. CONSTITUTION:Idling rpm is controlled by adjusting by a linear solenoid 5, opening of a valve intervened in the middle of a by-pass passage so as to by- pass a throttle valve disposed in a suction pipe. Thereupon, first, target opening thetaS of the SOL5 is set by making use of a microcomputer 16 in conformity with a signal yielded after A/D converting 15 an output from a water temperature sensor 14, and a target current IS to conduct through the SOL5 corresponding to the opening thetaS is set. Then, an average current Il flowing through the SOL5 is A/D converted 15, compared with the target current IS, and a ratio of on and off times of a transistor 11 is adjusted to permit a drive current for driving the SOL5 is controlled. The current flowing through the SOL5 is detected across resistance 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an idling rotation speed control device for an internal combustion engine using a linear solenoid, and particularly to an improvement in control accuracy thereof.

[Prior art]

In order to prevent the rotation speed of the engine from fluctuating due to changes in the load of auxiliary equipment when the engine is idling, and to change the rotation speed in response to the temperature of the engine, the amount of air sucked into the engine during idling or Various methods have been proposed for adjusting the amount of air-fuel mixture, one of which is to install a valve driven by a linear solenoid in the passage that passes through the intake air throttle valve to control the bypass nitrogen amount. Is there a way to adjust it?

FIG. 1 shows a conventional idling speed control device using a linear solenoid. In the figure, ] is an internal combustion engine, 2 is an intake pipe, 3 is a throttle valve disposed in the intake pipe 2 and interlocks with the accelerator pedal, 4 is a pipe and throttle pipe that bypasses the throttle valve 3, 5 is an IJ near solenoid that adjusts the amount of intake air that passes through all the pipes 4, 6 is a valve driven by the linear solenoid 5, and 7 and 8 are pipes that connect the intake pipe 2 and the bypass pipe 4. . The linear solenoid 5 is driven by a control circuit shown in FIG. In FIG. 3, 1] is a transistor for driving the linear solenoid 5; 12 is a flywheel diode connected in series with the linear solenoid 5; 13 is a congressor for a cooler, power steering, etc. that affects the internal combustion engine l; Loads such as automatic transmissions and lamps, ]7 is load 1
4 is a water temperature sensor that indicates the temperature of the internal combustion engine; 15 is a water temperature sensor obtained as an analog value; A converts the signal of 4 into a digital value;
/D converter, 16 is a microcomputer which is a control means for controlling the on/off ratio of the transistor 1 depending on the state of the water temperature sensor 14 and the load 3, and 9 is a DC power supply.

The amount of intake air when the internal combustion engine 1 is idling, that is, the opening degree () (I/4' opening degree) of the valve 6 of the bypass pipe 4, is determined by the operating state of the internal combustion engine 1 and the load of the auxiliary equipment.
Specifically, as shown in Figure 5, when the temperature of the cooling water is low, a large opening is required, and when there is no load, the Fm line is a, and when a load such as a cooler contelsor is operating, the opening is large. It is expressed as follows. Such required characteristics are stored in advance in the memory (ROM) in the microcomputer 6, and the current of the IJ near solenoid 5 is controlled in accordance with the procedure shown in FIG.

To explain the operation with reference to the flowchart in FIG. 6, first, the signal from the water temperature sensor 14 is converted into a digital value by the A/D converter 15, and this converted water temperature is input to the microcomputer 6. The required bypass opening degree is determined by RA in the microcomputer 16.
Read from M and set the opening degree θ, = fCWT). Next, input the on/off state of the load switch 17,
Setting the bypass opening degree θ,=f(L) corresponding to the load When these ratios are large, the average value of the drive current 2 shows a large value. Therefore, the on rate (duty ratio)
By changing this, the stroke of the linear solenoid 5 is controlled, the opening degree of the valve 6 provided in the piston pipe 4 is changed, and the amount of intake air is adjusted. In this way, the amount of intake air during idling is controlled, but in the conventional device, the average value of the drive current with respect to the tute ratio, that is, the stroke (opening degree) changes considerably depending on the temperature and applied voltage of the near solenoid 5. The lack of doing it, φ
It had

That is, as shown in FIG. 7, the linear solenoid 5 has a characteristic that its stroke changes proportionally to the drive current, and even if the duty ratio is the same, the applied voltage may decrease or The coil resistance value is WA degrees.
, increases due to rising rotation, the average current of the coil with respect to the duty ratio changes greatly from the normal characteristic a, as shown in Fig. 8, and becomes as shown in b, and the desired average box flow, that is, the stroke, cannot be obtained. I won't be able to do it. For this reason, the bypass pipe 4
The desired idling opening setting value is stored in advance in the ROM in the microcomputer 6 as a characteristic shown in FIG. 9, and the load switch 17 is reduced to just one. is not limited, and load switches are provided individually for the loads of the number of nuclei, and these individual load signals are input to the microcomputer 16, and the values of the curve shown in FIG. I'll argue if it happens.

When the final target opening θ8=f (OF, θL) is set according to the water temperature and load condition, the average value of the voltage applied to the near solenoid 5 (Tuty ratio) μ The characteristics will be as shown in Figure 2 V, so store the characteristics of this linear solenoid 5 in advance in a 16 yen microcomputer ROM VC, and set the target opening to 08.
The duty ratio corresponding to is read out, and the transistor ]1 is driven with this duty ratio. The linear solenoid 5 has a stroke characteristic that is proportional to the drive current, and when the linear solenoid 5 is turned on and off at a constant cycle, the average value of the drive current is I+ shows a small value, and as shown in FIG. 4(b), it becomes impossible to maintain the ON rotation speed.

Therefore, in order to eliminate such drawbacks, a device as shown in FIG. 9 was devised. In this device, a shear near solenoid 5 is controlled from a microcomputer 16.
The D/A converter 18 outputs a digital value corresponding to the current, converts this digital value into an analog value by the D/A converter 18, and converts VC, t pair 'f20, and transistor so that the current of the linear solenoid 5 matches this analog value. 11 and a resistor 19 for current feedback performs t-current feedback control. According to this, the current of the linear solenoid 5 can obtain accurate characteristics without being affected by changes in resistance value due to coil temperature or applied voltage, but the circuit configuration is complicated because it requires the D/A converter 18. This method is not expensive, but increases the number of bits required for the interface with the microcomputer 16, and also has the drawbacks that since the transistor 11 operates continuously, the power loss of the transistor 11 is large and the temperature rise is also large. had.

[Summary of the invention]

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and detects the current value of the linear solenoid 5, converts this value into a digital value in the A/D converter, and uses the microcomputer to convert the current value into a digital value. By performing correction control to the current value corresponding to the duty ratio, the control precision I! f
An object of the present invention is to provide an idling speed control device for an internal combustion engine that can improve the overall performance of the engine, has a simple configuration, and reduces power loss.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 10, 30 is a resistor connected in series with the linear solenoid 5 with respect to the DC 1i source 9, 31 is an operational amplifier, 32 is a resistor, and 33 is a capacitor.

The operation of the above device will be explained with reference to the flowchart in Figure 1. First, the target opening degree θ8 of the linear solenoid 5 is set in accordance with the water temperature take and the load condition, as in the conventional case. Next, a target current value I8 to be applied to the linear solenoid 5 corresponding to the target opening degree θ8 is set. This target opening degree θ8
The relationship between the current value Is and the target current value Is is as shown in FIG.
Remember it. Next, the average current value flowing through the linear solenoid 5 is an analog value eA/D converter 15
The current value is converted into a digital value, and the target current value is set using this digital value and the microcomputer 16. and in order to match the two, turn on transistor]1,
By adjusting the off-time ratio, the drive current of the linear solenoid 5 is controlled. The current f flowing through the linear solenoid 5 is detected as a voltage by the resistor 30,
After the voltage is amplified by an operational amplifier 31, it is averaged by a smoothing circuit consisting of a resistor 32 and a capacitor 33, and is input to the A/D converter 15.

In this way, in this embodiment, the current of the beam near solenoid 5 is @
Since direct feedback control is used, the opening degree of the linear solenoid 5 is not affected by fluctuations in coil temperature or applied voltage.
A stable n' degree is always maintained.

〔Effect of the invention〕

As described above, in the present invention, the current of the linear solenoid is input to the control means via the A/D converter that converts the degree information into A/D, and feedback control is performed so that it matches the target value. With a simple configuration, there is no unnecessary power loss, a stable amount of binox air is always obtained, and the accuracy of the idling speed can be improved.

[Brief explanation of drawings]

Figure 1 is a basic configuration diagram of the idling speed 1 [control device], Figures 2 and 7 are characteristic diagrams of the beam near solenoid, Figure 3 is a circuit diagram of the control 1 of the conventional device, and Figure 4 is a diagram of the beam near solenoid. Figure 5 is a diagram showing the bypass opening required for an internal combustion engine with respect to water temperature and load, Figure 6 is a flowchart of the conventional device, and Figure 8 is a diagram showing the relationship between applied -1 pressure and current. 9 is a control circuit diagram of another example of the conventional device, and FIGS. 10 and 11 are control circuit diagrams and flowcharts of the device of the present invention, respectively.
It is a chart. 1... Internal combustion engine, 2... Intake pipe, 3... Throttle valve,
4...Pi/4's tube, 5...Linian renoid,
6... Valve, ]3... Load, ]4... Water temperature sensor,
15... A/D converter, 16... Microcomputer, 17... Load switch, 30... Resistor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A/D that converts engine temperature information into digital values
In an idling speed control device for an internal combustion engine, which has a converter and controls the engine speed at idling by varying the amount of air intake into the engine in response to engine load fluctuations and engine temperature, A linear valve that is installed in a passage that bypasses a throttle valve that is arranged in a pipe and that is linked to an accelerator pedal and that adjusts the amount of air passing through the bypass passage, and that controls the opening degree of the valve to a target value depending on the engine condition. A solenoid, a control means for controlling the current of the linear solenoid to a target value by varying a duty ratio, and a current detection means for detecting the current of the linear solenoid, and the analog signal obtained from the current detection means is converted into the A/D converter. The control means compares the current target value of the linear solenoid with the output of the A/D converter and adjusts its duty output so that the deviation becomes zero. An idling speed control device for an internal combustion engine, characterized in that: