JP2637543B2 - Engine idle speed control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an engine, and more particularly to correction of an intake air amount supplied to an engine according to an electric load amount.

[Conventional technology]

In the conventional idle speed control device, the amount of intake air supplied to the engine is controlled in accordance with the deviation between the target idle speed and the actual engine speed, and the engine speed is maintained at the target speed. ing.

[Problems to be solved by the invention]

In the above-described conventional device, when an electric load (a headlight, an electric radiator fan, or the like) that consumes a large amount of electric power is used, the operation of the generator that supplies electric power to the electric load increases the load of the engine, and the engine rotation increases The number drops. The decrease in the engine speed eventually returns to the target speed by the control operation described above. However, since the control response is slow, the engine may stall depending on the magnitude of the electric load.

Therefore, for example, Japanese Patent Application Laid-Open No. 58-197449 proposes that a plurality of electric load switches are detected to correct the intake air amount, but switches and input circuits corresponding to the number of electric loads are required. This complicates the scale of the control device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an engine idle speed control device that has a simple structure and can eliminate engine stall and control response delay. .

[Means for solving the problem]

An engine idling control device according to the present invention includes an excitation period detecting means for detecting an excitation period for each predetermined crank angle period of the engine, correcting an intake air amount of the engine according to the excitation period, Correction means for changing the period according to the engine speed is provided.

(Operation)

In the present invention, the excitation period for each predetermined crank angle period of the engine is detected, the intake air amount of the engine is corrected based on the excitation period, and the engine load fluctuation due to the electric load fluctuation is accurately and early detected. The predetermined crank angle period is varied according to the engine speed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an engine idle speed control apparatus according to this embodiment, wherein 1 is a generator, and 2 is a field coil.
11 is a switching means for controlling the exciting current, 3 is an engine switch, and 4 is a vehicle battery. The generator 1 includes an armature winding 10, a field coil 11, and diodes 12 to 14 that rectify the three-phase AC output of the armature winding 10 and are Y-connected. The switching means 2 includes a voltage detection circuit 21 for detecting a voltage value of the battery 4, a field coil 11
And a semiconductor switching element 22 connected in series with the output of the voltage detection circuit 21 when the voltage of the battery 4 becomes lower than a predetermined value.
It is composed of a diode 23 that commutates the exciting current flowing through the field coil 11 when the node 22 is turned off. 5 receives an on / off signal (hereinafter referred to as an excitation signal) of a connection point between the field coil 11 and the semiconductor switching element 22 and a crank angle signal generated in synchronization with a predetermined crank angle of the engine, and inputs the signal during a predetermined crank angle period of the engine. The control unit detects an excitation period of the field coil 11 (an ON period of the semiconductor switching element 22) and calculates a control amount according to the result. Reference numeral 6 denotes a solenoid for controlling the opening and closing of the solenoid valve 7 in accordance with a control amount output from the control unit 5. Will be

Next, the operation of the above configuration will be described. The generator 1 is driven by the engine and charges the battery 4. The switching means 2 controls the excitation period of the field coil 11 so that the generated voltage of the generator 1 or the voltage of the battery 4 becomes a predetermined value, and controls the excitation current. Next, the detection operation of the excitation period for each predetermined crank angle period will be described with reference to FIGS. FIG. 2 shows the details of the control unit 5, and FIG. 3 is a time chart showing the operation thereof. A pulse generator 51 generates a pulse A of a predetermined frequency (shown in FIG. 3 (c)). The pulse A is input to a counter 53 via a resistor 52. On the other hand, since this input signal is masked by the transistor 54 only during the non-conduction period of the excitation signal shown in FIG. 3B, the signal B shown in FIG. The counter 53 counts the signal B and sends a count value C shown in FIG. The CPU 55 reads the count value C every time the crank angle signal shown in FIG. 3A is generated (in this embodiment, for each rising engine), and outputs an initialization signal R (FIG. 3F) to generate a counter. Initialize 53. As a result, the count value C is as C _P shown in FIG. 3 (e).
By the above operation, the count value C _P read by the CPU 55
Is a value corresponding to the excitation period for each predetermined crank angle period.

Then, CPU 55 is for calculating a control amount for controlling the amount of intake air from the read count value C _P and the crank signal,
The operation will be described with reference to FIGS. FIG. 4 is a time chart, and FIGS. 5 and 6 are flowcharts showing the procedure for calculating the control amount. The flow of FIG. 6 is executed according to a control program, and a crank angle signal is generated during this execution. 6, the flow of FIG. 6 is stopped, and the crank angle signal interruption routine of FIG. 5 is executed. Step S51 reads the count value C _P In initializes the counter 53 which is provided outside in step S52. That is, CPU55
The count value C _P loaded on is updated every crank angle signal changes as shown in FIG. 4 (c). Next, in step S53, the crank angle signal period T is measured, and in step S53,
In step 54, the excitation period ratio D for the crank angle signal period T is obtained by the following equation.

Here, K ₁ is a conversion coefficient for converting the exciting period ratio D to a predetermined resolution. That is, assuming that the excitation period ratio D means the excitation period during the crank angle signal period T as t ₁ and t ₂ shown in FIG. It can be understood that the value becomes a value corresponding to the exciting current flowing through the field coil 11, and the movement is as shown in FIG. 4 (d). As described above, the crank angle signal interruption routine of FIG. 5 is completed.

Next, to obtain a correction amount P _E corresponding thereto based on the exciting period ratio D in routine of FIG. 6. First, in step S61, _IE is searched from the relationship diagram between the excitation period ratio D and _IE shown in FIG. This _IE has a value corresponding to the output current of the generator 1.
The D- _IE relationship changes with the engine speed Ne as a parameter because D corresponds to the exciting current of the field coil 11 and _IE corresponds to the output current of the generator 1. That is, the output of the generator 1 is given by the magnitude of the exciting current and the engine speed. Next, step S62
In, first shows the relationship between the generator output current I _E and the correction amount P _E 8
From the figure, to find the correction amount P _E corresponding to I _E. The data set in FIG. 8 is the generator output _IE0 when there is no electric load.
Is set to zero, and a correction amount corresponding to the increase in the electric load is set. In step S63, the correction amount P _E obtained from Figure 7 is additive correction to the basic control amount P _B for controlling the intake air amount, determining the final control amount P _T. That is, the intake air amount is increased in accordance with the correction amount P _E.

By the way, in the above description, the detection operation of the excitation period for each predetermined crank angle period has been described. However, when the excitation period detection period is detected at a fixed predetermined crank angle period up to a high rotation speed, the detection period becomes short at high rotation. detection amount C _P of the excitation period is greatly changed. Therefore, in this embodiment, the predetermined crank angle period is switched according to the engine speed. FIG. 9 shows the state of the change. Fig. 9 shows the count value when the engine speed is high and the excitation current is constant.
FIG. 4 is a diagram showing the movement of C _P and the excitation period rate D, wherein C _P1 , D ₁
Is the amount detected when the crank angle signal is detected every cycle, C
_P2, D ₂ represents a detectable amount when encountering the crank angle signal every two cycles. Dashed line in the figure is a exciting period in the average, as is apparent from the figure, towards the crank angle signal 2 count value detected for each cycle C _P2 and exciting period ratio D ₂ variation is less. However, if the predetermined crank angle period is set to an unnecessarily long crank angle period, the detection responsiveness deteriorates, and especially at a low rotation speed, a response delay of the intake air amount correction to the change in the electric load occurs. For this reason, by switching the predetermined crank angle period according to the engine speed, a highly accurate detection amount with good responsiveness can be obtained at all engine speeds.

〔The invention's effect〕

As described above, according to the present invention, the excitation period of the switching means for controlling the field current of the generator is detected,
Since the intake air amount supplied to the engine is corrected by the correction amount determined based on the excitation period,
It is possible to accurately and early detect engine load fluctuations due to an increase in electric load, to suppress a decrease in engine speed and engine stall due to a delay in control response, and to have a simple configuration. Further, since the output phase of the generator is synchronized with the engine rotation phase, the correction amount is determined based on the excitation period for each predetermined crank angle period, and a highly accurate detection amount can be stably obtained. That is, since the excitation period of the field coil of the generator is detected every predetermined crank angle period, the following effects can be obtained. That is, since the torque of the engine is generated in synchronization with the crank angle, the intake air amount can be corrected at an appropriate timing.
In addition, an intermittent electric load such as an ignition coil or an injector coil is a load synchronized with a crank angle, so that the field current detection value is stable and changes little even for such a load, and the load is stable. Rotational speed control with good responsiveness becomes possible. Further, since the predetermined crank angle period is changed according to the engine speed, a highly responsive and highly accurate load fluctuation detection amount can be obtained in the entire engine speed range.

[Brief description of the drawings]

1 and 2 are an overall configuration diagram of the device of the present invention and a configuration diagram of a control unit, FIGS. 3 and 4 are time charts showing the operation of the device of the present invention, and FIGS. 7 and 8 are control characteristic diagrams stored in a control unit according to the present invention, and FIG. 9 is a diagram showing a case where a crank angle period which is an excitation period detection period of the present invention is switched. It is a time chart of each part. DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Switching means, 4 ... Battery, 5 ... Control unit, 6 ... Solenoid, 7 ... Solenoid valve, 8 ... Bypass passage, 11 ... Field coil. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A generator driven by an engine to charge a battery, and an excitation period of a field coil of the generator is controlled by controlling an excitation period of a field coil of the generator so that a generated voltage of the generator or the battery voltage becomes a predetermined voltage. , An excitation period detecting unit for detecting an excitation period for each predetermined crank angle period of the engine, and a control amount for controlling an intake air amount taken into the engine based on an output of the excitation period detection unit. An idling speed control device for an engine, comprising: a correcting means for correcting the predetermined crank angle period in accordance with the engine speed while making a correction with the determined correction amount.