JP2721974B2 - Duty solenoid control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a duty solenoid control device used for various control valves of an automobile engine, for example, an idle speed control valve (ISC valve) for controlling an idle speed.

[Prior art]

Conventionally, a proportional solenoid is used as an actuator for various control valves of an automobile engine, such as an ISC valve disclosed in JP-A-59-128943. And the lift amount (opening degree) of the valve is approximately proportional. Usually, the current value is given in the form of a duty ratio of the pulse voltage, and the lift amount is controlled by the duty ratio. FIG. 2 schematically shows a drive circuit of the duty solenoid. The drive circuit 15 composed of a power transistor is turned on / off in accordance with a duty ratio by an output duty signal from a control unit. the battery voltage V _B is the drive current I flows through the duty solenoid 7a that is applied, for example, the ISC valve 7
Is the opening of the lift amount 1 according to the duty signal.

[Problems to be solved by the invention]

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 a constant power supply voltage
Also be applied to V _B, the drive current I flowing to the duty solenoid 7a is varied. That is, even if the same duty signal is output from the control unit, the lift amount 1, that is, the valve opening changes due to the temperature change of the ISC valve 7. Further, the same applies to the supply voltage (battery voltage) V _B, when the power supply voltage V _B changes also varies the current I flowing through the duty solenoid 7a. Thus for the same duty ratio, when the resistance value R of the power supply voltage V _B and the valve temperature i.e. duty solenoid 7a is changed, also changes the valve opening degree becomes a cause of deteriorating the controllability becomes disturbance of the control system, idle The rotation speed may become unstable. For this reason, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-176447, there is a device in which current value feedback control is performed, but there is a problem that the system becomes complicated. The present invention has been made to solve the above-described problems, and has a simple system configuration, and can improve controllability of a control system without being affected by fluctuations in valve temperature or power supply voltage. It is an object to provide a duty solenoid control device.

[Means for solving the problems]

The present invention provides a duty solenoid control device that drives a duty solenoid that operates a controlled object by a duty signal and controls the controlled object according to a duty ratio of the duty signal. A duty ratio calculating means for calculating a reference duty ratio in the above, a power supply voltage detecting means for detecting a power supply voltage applied to the duty solenoid, a drive current detecting means for detecting a drive current flowing through the duty solenoid, A drive current conversion means for converting the drive current detected by the detection means into a reference drive current corresponding to the reference power supply voltage based on the power supply voltage detected by the power supply voltage detection means at this time; and output to the duty solenoid last time Output duty ratio and the reference drive converted this time Correction value calculating means for obtaining a correction value for compensating for a change in the resistance value of the duty solenoid due to a temperature change from a preset correction value map, and correcting the reference duty ratio with the correction value. And a duty ratio correction means for determining a duty ratio of the output duty ratio and outputting a duty signal having the output duty ratio to the duty solenoid.

[Action]

With the above configuration, based on the operating state of the engine, the duty ratio calculated by the duty ratio calculation means under the reference conditions (reference battery voltage, reference temperature of the valve, etc.) is replaced by the actual drive current value flowing through the duty solenoid. If the correction is performed by multiplying the correction coefficient directly obtained from the map search, etc., the change in the drive current value caused by the change in the power supply voltage becomes a correction error. Then, a correction coefficient is read out based on the reference drive current value and the output duty ratio output last time, and the reference duty ratio is corrected based on the correction coefficient. A desired valve opening can be obtained.

【Example】

Hereinafter, the present invention will be described with reference to FIGS. 1 to 6 by taking an ISC valve for controlling an idle speed as an example. In FIG. 1, reference numeral 1 denotes an engine, a water temperature sensor 2 for detecting an engine cooling water temperature Tw is provided in a cylinder jacket thereof, an injector 3 is provided in front of an intake port, and a throttle valve 4 is in an idling state. Is installed. A bypass passage 6 is provided in the intake pipe so as to bypass the throttle valve 4, and the bypass passage 6 serves as a valve means for regulating the intake air flow rate of the engine during idling.
An ISC valve 7 is provided, and the opening degree of the ISC valve 7 is set by a duty ratio of a control signal (duty signal) given to a duty solenoid 7a by a control unit 8. The control unit 8 is composed of a microcomputer or the like, and together with signals from the water temperature sensor 2 and the idle switch 5, a crank angle sensor (engine speed sensor) 9, an intake air temperature sensor 10, an air flow meter 11, a boost pressure sensor 12, and O _{2 It} takes in signals from the sensor 13 and the like and performs idle speed control in addition to air-fuel ratio control and ignition timing control. When the idle switch 5 detects that the throttle valve 4 is fully closed by the idle speed control, the control unit 8
Determines that the engine 1 has entered the idling state, sets a target idle speed Ni based on the engine cooling water temperature Tw detected by the water temperature sensor 2, further adds air conditioner correction, etc., and A duty signal is output to a drive circuit 15 composed of a power transistor or the like as shown in FIG. 2 in accordance with the detected deviation from the actual engine speed Ne, and a duty solenoid of the ISC valve 7 is provided in accordance with the on-duty. 7a to by applying a power supply voltage V _B flows a driving current I, obtained lift l ie valve opening corresponding to the duty ratio of the duty signal, feedback control of the engine speed Ne to the target idle rotational speed Ni. By the way, since the ISC valve 7 is arranged in the engine room and close to the engine 1, the temperature may be high, and the temperature change is large. Therefore, the coil resistance R of the duty solenoid 7a also changes. Now, assuming that the coil resistance R of the duty solenoid 7a deviates from the resistance value R ₀ at the reference temperature as shown in FIG.
Same drive current flowing to the duty solenoid 7a relative duty ratio ISC _duty is changed to I ₁ from I _0, also becomes deviated from the desired opening degree valve opening. Therefore,
In order to maintain the desired opening degree, that is, the desired current value I ₀ , the duty ratio ISC _duty may be corrected according to the drive current value I actually flowing through the duty solenoid 7a up to the ISC _DUTY that becomes the drive current I ₀ . Therefore, the correction coefficient k (R) experimentally obtained is corrected in advance as shown in FIG. 4 using the drive current I flowing through the duty solenoid 7a and the duty ratio ISC _DUTY of the output duty signal as parameters. by setting in the ROM of the control unit 8 as the coefficient k (R) map Iga, drive current I of the duty solenoid 7a which is one parameter of the supply voltage V _B deviates from the reference power supply voltage V _B14, drive Since the current value also changes,
Supply voltage V _B can not directly find the correction factor k (R) mapped by in which the driving current value detected in a state I where varied. The reason detected drive current value I reference drive current I in response to the change in the power supply voltage V _B 'on, I' =
If the conversion is performed as (V _B14 / V _B ) × I and a map search is performed using the converted reference drive current value I ′, the above-described correction error does not occur. Next, the control operation of the duty solenoid as described above will be described with reference to the block diagram shown in FIG. 5 and the flowchart shown in FIG. The control unit 8 firstly detects the engine operating state
Each state signal such as the engine rotation speed Ne, the engine cooling water temperature Tw, and the air conditioner switch signal AC from 16 is fetched (step S100), and the duty ratio calculation means 20 maps the target idle rotation speed according to the engine cooling water temperature Tw. The search is further performed, and a correction is made according to the on / off state of the air conditioner to set a target idle speed Ni, and a reference condition (battery reference voltage V _B14 , ISC) is set according to a deviation from the detected engine speed Ne. The reference duty ratio ISC _duty at the temperature of the valve 7, that is, the reference resistance value R ₀ ) is determined (step S101). This reference duty ratio ISC _duty is
Duty correction means 21 correction decorated with the output duty ratio ISC _DUTY becomes as described below, the is outputted to the drive means 15, the correction coefficient k last as duty ratio ISC _{DUTY · n-1} in the next routine ( R) is loaded into the calculation means 23 (step S103). Next, in FIG. 2, and supplies a power supply voltage V _B detected by the drive current I and the power supply voltage detecting means is detected by the drive current detection means 17 consisting of CR circuit connected to the emitter side of the power transistor 15 ( Step S10
4), the driving current value I when the power supply voltage V _B at the drive current converter 24 is converted into the reference drive current I 'I' = I × V B14 / V B at the reference power source voltage V _B14 (step S105). Then, the correction coefficient calculating means 23 calculates the reference power supply voltage V _B14
The reference drive current value I 'converted to a drive current value corresponding to the current, and the previous output duty ratio loaded
Based on ISC _{DUTY · n-1} , the correction coefficient map 22 is searched to read out the corresponding correction coefficient k (R) (step S10).
6) The validity of the read correction coefficient k (R), that is, an upper limit _Max set in advance so that no extreme correction is performed.
And is checked whether it is in the range between the lower limit M _1n is calculated at (step S107), the duty ratio calculation unit 20 as long as it is within the range correction value coefficient k a (R) as it is output to the duty ratio correcting means 21 The calculated output duty ratio ISC is multiplied by the calculated reference duty ratio ISC _duty (step S108).
_DUTY is output to the drive circuit 15 (step S109). on the other hand,
If the read correction coefficient k (R) exceeds the range between the upper limit _Max and the lower limit _M1n , the correction coefficient calculating means 23 uses the previous output duty ratio ISC _{DUTY · n-1} that has been loaded. The correction coefficient k (R) is fixed as it is (step S110).
This correction coefficient k (R) is multiplied by the reference duty ratio calculated by the duty ratio calculation means 20 (step S108) to obtain and output the output duty ratio ISC _DUTY (step S10).
9). And finally, the ISC output for the next control
_{Store the DUTY} as ISC _{DUTY · n-1} (step S11).
1) Go through the control routine. Thus, the temperature change of the ISC valve 7, that is, the change of the resistance value R of the duty solenoid 7a, and the change of the power supply voltage V _B
Output duty ratio ISC _DUTY corrected for
Since driving the SC valve 7, the opening degree of the ISC valve 7, even if the changes in temperature and power supply voltage V _B, always coincides with the desired value.

【The invention's effect】

As described above, according to the present invention, the duty ratio calculated according to the engine operating state is corrected for the fluctuation of the power supply voltage and the change of the valve temperature. Therefore, fluctuations in the power supply voltage and changes in the valve temperature do not act as disturbances in the control system, so that controllability is improved and more comfortable control can be performed.

[Brief description of the drawings]

FIG. 1 is a block 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, and FIG. 3 is an explanation of a duty ratio correction for a change in a power supply voltage and a valve temperature. FIG. 4, FIG. 4 is a diagram showing a correction coefficient map, FIG. 5 is a block diagram showing a configuration of a control unit according to the present invention, and FIG. 6 is a flowchart showing its operation. 7 ... ISC valve, 7a ... Duty solenoid, 8 ...
... Control unit, 17 ... Drive current detecting means, 18 ... Power supply voltage detecting means, 20 ... Duty ratio calculating means, 21 ... Duty ratio correcting means, 22 ... Correction coefficient map, 23 ... Correction coefficient calculating means , 24 ... Drive current conversion means.

Claims (1)

(57) [Claims] 1. A duty solenoid control device for driving a duty solenoid for operating a controlled object by a duty signal and controlling the controlled object in accordance with a duty ratio of the duty signal. A duty ratio calculating means for calculating a reference duty ratio below; a power supply voltage detecting means for detecting a power supply voltage applied to the duty solenoid; a drive current detecting means for detecting a drive current flowing through the duty solenoid; A drive current converter for converting the drive current detected by the current detector to a reference drive current corresponding to the reference power supply voltage based on the power supply voltage detected by the power supply voltage detector this time; The output duty ratio that was output and the By the drive current,
Correction value calculating means for obtaining a correction value for compensating for a change in the resistance value of the duty solenoid due to a temperature change from a preset correction value map; and correcting the reference duty ratio with the correction value to obtain a current output duty ratio. And a duty ratio correction means for outputting a duty signal having the output duty ratio to the duty solenoid.