JPH0230949A - Duty solenoid control device - Google Patents

Abstract

PURPOSE:To invariably keep the fixed valve opening regardless of the change of the valve temperature by correcting the reference duty ratio calculated in response to the operation state based on the driving current flowing through a duty solenoid. CONSTITUTION:For the control of an ISC valve 7, the output of an engine operation state detecting means 16 is inputted to a duty ratio calculating means 20, the target idle rotating speed in response to the cooling water temperature is map-retrieved, the correction in response to the operation state of an air conditioner is applied. The reference duty ratio is calculated in response to the variation between the target idle rotating speed and the actual engine rotating speed. On the other hand, the output of a driving current detecting means 17 detecting the driving current value flowing through the valve 7 is inputted to a correction coefficient calculating means 21, a map 22 is retrieved to determine the correction coefficient in response to the change of the valve temperature, it is outputted to a duty ratio correcting means 21. The reference duty ratio is corrected with the correction coefficient to determine the output duty ratio.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a control device for a duty solenoid used in various control valves of an automobile engine, such as an idle speed control valve (ISO valve) for controlling the number of idle revolutions.

[Conventional technology]

Conventionally, various control valves for automobile engines have been manufactured using ISC as disclosed in, for example, Japanese Patent Application Laid-open No. 128943/1983.
Like a valve, a proportional solenoid is used as an actuator, and the current value flowing through the coil is approximately proportional to the lift i (opening degree) of the valve.
The current value is given in the form of a pulse voltage duty ratio, and the lift amount is controlled by the duty ratio. The drive circuit for the above-mentioned duty solenoid is shown in FIG. 2. The drive circuit 15 consisting of a power transistor is turned on and off according to the output duty ratio by the output duty signal from the control unit. , a drive current I flows through the duty solenoid 7a to which a predetermined voltage (■8) is applied, and for example, ■S
The C valve 7 opens to a lift amount j according to the duty signal.

[Invention or problem to be solved]

By the way, in the above configuration, the duty solenoid 7a has a coil resistance R, and when the temperature of the IsC valve 7 changes, the resistance value R also changes, and even if a constant battery voltage 8 is applied, Duty solenoid 7
The drive current I flowing through a fluctuates. In other words, even if the same duty signal is output from the control unit, the lift amount 1, that is, the valve opening degree changes due to a change in the temperature of the ISC valve 7, causing a disturbance in the control system. For this reason, as shown in Japanese Unexamined Patent Publication No. 59-176447, for example, there are devices that perform feedback control of the current value, but there is a problem that the system becomes complicated. The present invention has been made to solve the above problems, and provides a duty solenoid control device that has a simple system configuration and can improve controllability of a control system without being affected by changes in valve temperature. The purpose is to provide

[Means to solve the problem]

In order to achieve the above object, the present invention provides a duty solenoid control device that drives a duty solenoid with a duty signal via a drive circuit and controls a controlled object such as a valve according to the duty signal force duty ratio. , a duty ratio calculation means for calculating a reference duty ratio under reference conditions based on an engine operating state, and detecting a drive current flowing through the duty inlenoid when a duty signal of the reference duty ratio is outputted. Using the drive current detection means, the detected drive current, and the reference duty ratio corresponding to the drive current, a correction coefficient map that is set in advance is used to calculate the value for changes in valve temperature, that is, changes in the resistance value of the duty solenoid. The apparatus is provided with a correction coefficient calculation means for calculating a correction coefficient, and a duty ratio correction means for correcting the reference duty ratio using the correction coefficient to determine an output duty ratio.

[For production]

With the above configuration, the duty ratio calculation means calculates a reference duty ratio under reference conditions (valve reference temperature) based on the operating state of the engine, and outputs a duty signal of the reference duty ratio to the drive circuit. Since the value of the drive current flowing through the duty solenoid is corrected using the correction coefficient k (R) obtained by map search, even if the resistance value of the duty solenoid fluctuates due to fluctuations in valve temperature, it always maintains a constant value. Valve opening can be maintained. [Embodiment] The present invention will be explained below with reference to FIGS. 1 to 6, taking an ISC valve for idle speed control as an example. In FIG. 1, reference numeral 1 is an engine, and its cylinder jacket is provided with a water temperature sensor 2 for detecting the engine cooling water temperature TV, an injector 3 is provided in the front stage of the intake boat, and a throttle valve 4 is provided with an idling state. An idle switch 5 is installed to detect. A bypass passage 6 is provided in the intake pipe to bypass the throttle valve 4, and an ISC valve 7 is provided therein as a valve means for regulating the intake air flow rate of the engine during idling. The opening degree of 7 is set by the duty ratio of a control signal (duty signal) given to duty solenoid 7a by control unit 8. The control unit 8 includes a microcomputer and the like, and includes a water temperature sensor 2. Along with the signal from the idle switch 5, the crank angle sensor (engine speed sensor) 9.
Intake temperature sensor 10. Air flow meter 11. It takes in signals from the boost pressure sensor 12, 02 sensor 13, etc., and performs idle rotation speed control in addition to air-fuel ratio control, ignition timing control, etc. In this idle rotation speed control, when the idle switch 5 detects that the throttle valve 4 is fully closed, the control unit 8 determines that the engine 1 has entered the idling state, and the engine cooling water temperature T detected by the water temperature sensor 2 changes. Based on this, the target idle speed Ni is set, and furthermore, air conditioner correction etc. are added, and the duty signal is set as shown in FIG. is output to the drive circuit 15 consisting of a power transistor etc., and the duty solenoid 7 of the ISC valve 7 is output according to its on-duty.
A battery voltage (3) is applied to a, a drive current I is applied, a lift amount 1, that is, a valve opening is obtained according to the duty signal force duty ratio, and the engine speed Ne is feedback-controlled to the target idle speed Nl. By the way, since the ISO valve 7 is located in the engine room and close to the engine 1, it may reach a high temperature, and since the temperature changes greatly, the coil resistance R of the duty solenoid 7a also changes. Now, if the coil resistance R0 of the duty solenoid 7a deviates from the resistance value R0 at the reference temperature as shown in FIG. 3, the drive current flowing through the duty solenoid 7a for the same duty ratio I S CouTy is ■. to ■1, and the valve opening also deviates from the desired opening. Therefore, the desired opening degree, that is, the desired current ■. In order to maintain the duty ratio l5 under standard conditions,
Cd,t, is the drive current ■. It is only necessary to correct the drive current value I that actually flows through the duty inlenoid 7a up to 15CDLITV. For this reason, the correction coefficient k (R) determined experimentally using the drive type iI flowing to the duty solenoid 7a and the output duty signal force duty ratio l5Cd, ta as parameters, is
As shown in the figure, the correction coefficient map 22 is set in advance in the ROM of the control unit 8. Next, the operation of the control function of the duty solenoid 7a as described above will be explained with reference to the block diagram shown in FIG. 5 and the flowchart shown in FIG. The control unit 8 first detects the engine operating state detection means 1.
Engine speed Ne from 6, engine coolant temperature Tv
, the air conditioner switch signal AC, etc. are taken in (step 5100), and the duty ratio calculation means 20 searches a map for the target idle speed according to the engine coolant temperature TV, and further, according to the on/off state of the air conditioner. At the same time, the reference duty ratio ISCdmty under reference conditions (reference temperature of ISC valve 7, that is, reference resistance value R8) is set according to the deviation from the detected engine revolution number Ne.
is determined (step 3101). Then, the duty (No. 8) of the reference duty ratio ISC,,t is output to the drive circuit 15 (Step 3102), and is delayed by a predetermined time T to wait for the drive current of the duty solenoid 7a to stabilize (Step 5103). . Next, in FIG. 2, the drive current value of the duty inlenoid 7a corresponding to the reference duty ratio 5C duty detected by the drive current detection means 17 consisting of a resistor 17a and a capacitor 17b connected to the emitter side of the power transistor 15. Step 5104)
The correction coefficient calculation means 21 searches the correction coefficient map 22 based on the previously outputted reference duty ratio l5Cduta and the detected drive current value ■, and calculates the resistance value of the duty solenoid 7a due to temperature change. Calculate the correction coefficient k(R)- for the change in R (step 5105)
, this correction coefficient k (R) has its validity, that is, the upper limit M set in advance so that extreme correction is not performed,
It is checked whether the upper limit Mlfi is within the range (step 310G), and if the upper limit M a x and the lower limit M1
If it exceeds the previous value, fix the correction value coefficient kfR) to the previous value in order to avoid extreme correction (step 3).
107). Then, the duty ratio correction means 23 corrects the standard duty ratio ■5Cduty under the standard conditions calculated by the duty ratio calculation means 20 using the correction coefficient k (R) to obtain the output duty ratio I S C DUTY.
DIJTY= T S C, , , , Xk (R) (step 3108), and output the duty signal to the drive circuit 15 (step 5109), so that even if a temperature change occurs, the ISC valve 7 is kept at the reference temperature. The same lift amount as the state duty ratio rsc, □, that is, the same -
Control the opening. [Effects of the Invention] As described above, according to the present invention, the duty signal force duty ratio is corrected based on the drive current flowing through the duty solenoid. Even if the coil resistance value changes, a constant opening can always be maintained. Moreover, it has a simple configuration and good responsiveness, and changes in valve temperature do not act as a disturbance to the control system, improving the controllability of the system and enabling more comfortable control.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of an idle speed control system to which the present invention is applied, FIG. 2 is a drive circuit diagram of an ISC valve,
FIG. 3 is a diagram showing changes in current value due to fluctuations in valve temperature (resistance), FIG. 4 is a diagram showing a correction coefficient map, and FIG. 5 is a diagram showing an embodiment of the duty solenoid control device according to the present invention. The block diagram and FIG. 6 are flowcharts showing the operation. 7... ISC valve, 7a... Duty solenoid, 8... Control unit, 17... Drive current detection means, 20... Duty ratio calculation means, 21... Correction coefficient calculation means, 22 ...Correction coefficient map, 23...
Duty ratio correction means.

Claims (1)

[Claims] In a duty solenoid control device that drives a duty solenoid with a duty signal via a drive circuit and controls a controlled object such as a valve according to the duty ratio of the duty signal force, a reference is determined based on the engine operating state. a duty ratio calculation means for calculating a reference duty ratio under the conditions; a drive current detection means for detecting a drive current flowing through the duty solenoid when a duty signal having the reference duty ratio is output; and a detected drive. a correction coefficient calculation means for calculating a correction coefficient for a change in valve temperature, that is, a change in resistance value of the duty solenoid, from a preset correction coefficient map based on the current and the reference duty ratio corresponding to the drive current; A duty solenoid control device comprising: duty ratio correction means for correcting a reference duty ratio using the correction coefficient to determine an output duty ratio.