JPH11257526A - Solenoid valve driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely maintain the responsiveness of a solenoid valve even if oil temperature is raised up. SOLUTION: When an average energizing duty ratio Da of a coil SL is greater than a first reference value λh(=Dtmp×Dcv) computed (S320 and S340) based on the target duty ratio of a control signal Va, a target period and battery voltage, it is judged that coil temperature has been raised up (S350), the period of the control signal Va is thereby lengthened so as to be changed (S360 through 380), and when the average energizing duty ratio is found to have been smaller than a second reference value λ2 (=Dtmp×Dcv-Dhys) which is smaller than a first reference value λ1 by a hysteresis Dhys, it is judged (S390) that coil temperature has been lowered, and the period of a control signal Va is thereby shortened so as to be changed (S400 through S420). Thus by maintaining the ripple width of driving current Ic, and restraining an increase in the frictional resistance of a solenoid valve, the responsiveness of the solenoid valve can thereby be surely maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solenoid valve driving device for driving a solenoid valve.

[0002]

2. Description of the Related Art Conventionally, there has been known a solenoid valve having a coil which is energized by energization and drives a valve as a means for controlling a hydraulic pressure and an air flow rate. In such a solenoid valve, when the temperature of the coil (hereinafter, also referred to as "coil temperature") increases due to continuous energization or an increase in the ambient temperature, the internal resistance of the coil increases, and current hardly flows through the coil. There is a problem that the actual opening of the solenoid valve is different from the target opening.

[0003] In order to solve this problem, there is known a solenoid valve driving device as described in, for example, Japanese Patent Application Laid-Open No. 2-261987. In this solenoid valve driving device, a transistor circuit controls on / off of energization of a coil based on a duty signal output from a control computer to control a current flowing through the coil (hereinafter also referred to as “driving current”). Then, the opening of the solenoid valve is adjusted, and the drive current is detected immediately before the end of the ON period, and after comparison with a preset current value, based on the comparison result, pulse width modulation is performed. The on-time is corrected to be longer or shorter. For example, even if the internal resistance of the coil increases due to an increase in the coil temperature, the current to be passed through the coil (that is, the drive current) is maintained by largely correcting the on / off duty ratio of the transistor circuit, and the target opening degree You get

[0004]

By the way, a minute AC component (hereinafter, referred to as "ripple") is generated in the drive current in synchronization with the on / off of the current supply to the coil.
This ripple causes the solenoid valve to vibrate minutely around the target opening, thereby reducing the frictional resistance and changing the opening with good responsiveness. However, when the internal resistance of the coil increases, not only does the drive current decrease, but also the rate of increase and decrease becomes slower, so that the amplitude of the ripple (hereinafter referred to as "ripple width") becomes narrower (that is, smaller). turn into. Therefore, when the coil temperature rises and the internal resistance of the coil increases, the amplitude of the minute vibration of the solenoid valve decreases, the frictional resistance increases, and the responsiveness of the solenoid valve decreases.

In a conventional solenoid valve driving device, when the coil temperature rises, it is possible to keep the solenoid valve at a desired opening degree, but it is possible to prevent a decrease in the responsiveness of the solenoid valve due to such a decrease in the ripple width. I couldn't. The present invention has been made in view of the above problems, and an object of the present invention is to provide a solenoid valve driving device that can ensure responsiveness of a solenoid valve even when the temperature of a coil increases.

[0006]

Means for Solving the Problems and Effects of the Invention In the solenoid valve driving device according to the present invention (Claim 1) which has been made to solve the above-mentioned problems, the duty signal generating means has a function according to the current to be passed through the coil. A duty signal having the generated duty ratio is generated at a predetermined cycle, and the generated duty signal is supplied to the driving means to drive the driving means. Therefore, a current according to the duty ratio of the duty signal generated by the duty signal generating means flows through the coil.

In the present invention, the temperature judging means judges the fluctuation of the temperature of the coil, and the signal period changing means raises the temperature of the coil in accordance with the fluctuation of the temperature of the coil judged by the temperature judging means. The generation cycle of the duty signal is set so as to be longer. As a result, the duty signal generating means generates the duty signal at the generation cycle set by the signal cycle changing means.

When the temperature around the solenoid valve driven by the solenoid valve driving device configured as described above rises, for example, and the temperature of the coil rises with this, the internal resistance of the coil increases, and The rate of increase / decrease of the current flowing through the inverter becomes slow, and the amplitude of the ripple generated in synchronization with the duty signal becomes narrow. Therefore, if the generation cycle of the duty signal is made longer as the temperature of the coil becomes higher, the ripple width becomes the same width as before the temperature rise, even if the current flowing through the coil increases or decreases slowly. (That is, size).

That is, according to the solenoid valve driving device of the present invention, even if the temperature of the coil rises, the ripple width of the current flowing through the coil can be maintained, and the responsiveness of the solenoid valve can be secured. . Here, as the temperature determination means, for example, a temperature sensor may be provided near the coil, and a change in the temperature of the coil may be determined based on the output of the temperature sensor. When the solenoid valve driving device is configured to feed back the result of measuring the actual opening degree of the solenoid valve with the position sensor and generate a duty signal according to the current to be passed through the coil, the temperature determination may be performed. The means may be configured to measure a response delay of the actual opening with respect to the change of the target opening of the solenoid valve, and determine a change in the coil temperature based on the response delay of the actual opening. Also, when the solenoid valve driving device changes the target opening of the solenoid valve, first, in order to flow a current corresponding to the target opening to the coil,
The solenoid valve is driven at an expected duty ratio, and thereafter, a duty signal having a duty ratio according to a current to be supplied to the coil is generated while feeding back the result of measuring the actual opening of the solenoid valve with the position sensor. In this case, the temperature determination means may be configured to determine a change in coil temperature based on a difference between the actual opening and the target opening when the solenoid valve is driven at an expected duty ratio. it can.

As described above, there are various methods for judging the fluctuation of the coil temperature. However, the method of providing the solenoid valve with the temperature sensor and the position sensor increases the size and complexity of the solenoid valve. Therefore, as described in claim 2, in the solenoid valve driving device,
State detecting means for detecting the operating state of the solenoid valve driven by the solenoid valve driving device,
A duty ratio corresponding to a current to be passed through the coil to control the solenoid valve to the target state based on a deviation between the actual operating state of the solenoid valve and the target state detected by the state detecting means. If the configuration is such that the duty signal is generated, the temperature determination means sets a reference value for determining the temperature of the coil from the duty ratio of the duty signal generated by the duty signal generation means. Means for calculating based on the generation cycle of the duty signal generated by the means and the current to be passed through the coil, wherein the reference value calculated by the reference value calculation means and the reference value generated by the duty signal generation means are provided. If the duty ratio is greater than the reference value, the temperature of the coil When it is determined that the temperature has risen, and when the duty ratio is smaller than the reference value, it is configured to determine that the temperature of the coil has decreased, and the signal cycle changing unit determines that the temperature of the coil has increased by the temperature determination unit. Then, it is preferable that the generation period of the duty signal generated by the duty signal generation unit is lengthened, and the generation period is shortened when the temperature determination unit determines that the temperature of the coil has decreased.

In the solenoid valve driving device constructed as described above, when the internal resistance of the coil increases due to an increase in the temperature of the coil and the current becomes difficult to flow, the actual operation state of the solenoid valve (the current flowing through the coil, the solenoid valve , The air flow rate controlled by the solenoid valve and other actual operating conditions) change. Then, the duty signal generating means generates a duty signal having a larger duty ratio in order to control the actual operating state of the solenoid valve to the target state (feedback control), in order to maintain the current which should be originally passed through the coil.

Therefore, by comparing the duty ratio of the duty signal with a predetermined reference value, it is possible to determine a change (increase or decrease) in the coil temperature. However, even if there is no fluctuation in the coil temperature, the actual duty of the coil, and
The valve is operated to a value corresponding to the target state of the solenoid valve. Therefore, it is necessary to calculate the reference value for determining the fluctuation of the coil temperature by comparing with the duty ratio of the duty signal in accordance with the target state of the solenoid valve and the coil temperature. On the other hand, the target state of the solenoid valve and the temperature of the coil are indirectly determined from the current to be passed through the coil to control the solenoid valve to the target state and the generation cycle of the duty signal changed according to the coil temperature. You can know. Therefore, in the solenoid valve driving device according to the second aspect, the reference value for determining the temperature fluctuation of the coil based on the duty ratio of the duty signal is calculated based on the generation cycle of the duty signal and the current to be passed through the coil. Then, comparing the calculated reference value with the duty ratio of the duty signal, if the duty ratio is greater than the reference value, it is determined that the temperature of the coil has increased, and the duty ratio is greater than the reference value. When it is smaller, it is determined that the temperature of the coil has decreased.

As described above, according to the solenoid valve driving device of the second aspect, the temperature fluctuation of the coil can be determined without providing a temperature sensor or a position sensor in the solenoid valve.・
It is preferable because it does not complicate.

Now, as the temperature of the coil decreases, the duty ratio of the duty signal becomes smaller than the reference value, or the generation cycle of the duty signal is extended, so that the duty ratio of the duty signal becomes a new reference value (ie, the duty signal (The reference value calculated on the basis of the new generation cycle and the current to be passed through the coil), the generation cycle of the duty signal may be shortened immediately.
However, in such a case, hunting may occur and the operation of the solenoid valve control device may become unstable. Therefore, as described in claim 3, the reference value calculating means uses the first reference value for determining whether the temperature of the coil has risen as the reference value and whether the temperature of the coil has dropped. A second reference value (smaller than the first reference value) for determining whether the first reference value and the second reference value calculated by the reference value calculation means are calculated.
Each of the reference values is compared with a duty ratio of a duty signal generated by the duty signal generating means. When the duty ratio is larger than the first reference value, it is determined that the temperature of the coil has increased, and the duty ratio is determined. If the temperature is smaller than the second reference value, it is preferable to determine that the temperature of the coil has decreased. With this configuration, hunting can be prevented, and the operation of the solenoid valve driving device can be prevented from becoming unstable.

When the voltage of the power supply for supplying current to the coil decreases, the voltage rises in the same manner as when the temperature of the coil rises.
Although it becomes difficult for the current to flow through the coil, in the solenoid valve driving device of the present invention (claim 2 or 3), in such a case, an attempt is made to maintain the current that should originally flow through the coil.
The duty ratio of the duty signal is increased. Therefore, an increase in the duty ratio of the duty signal due to an increase in the temperature of the coil and an increase due to a decrease in the voltage of the power supply may be confused. In view of the above, according to a fourth aspect of the present invention, the temperature determination unit corrects the reference value calculated by the reference value calculation unit based on the voltage of the power supply so as to decrease as the voltage of the power supply increases. The reference value corrected by the reference value correction unit and the duty ratio of the duty signal generated by the duty signal generation unit may be compared. In this way, even if the voltage of the power supply that supplies current to the coil changes, it is possible to accurately determine the change in the coil temperature.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an electric configuration of a solenoid valve driving device for controlling an auxiliary air amount of a carburetor in an internal combustion engine as one embodiment.

As shown in FIG. 1, a solenoid valve driving device 1 of the present embodiment includes a control computer 2 for performing various control processes and a solenoid valve from a battery BT having a voltage + B (hereinafter referred to as “battery voltage + B”). Coil S
The current supplied to L (hereinafter, referred to as “drive current Ic”)
, A current feedback circuit 3 for controlling the voltage according to a pulse signal (hereinafter, referred to as a “control signal Va”) from the control computer 2, and an AD converter 4 (hereinafter, “ADC”) for detecting the battery voltage + B and inputting it to the control computer 2.
4 ". ) And the drive voltage Vc of the solenoid valve
(I.e., a voltage on the side of the coil SL opposite to the battery BT), and after shaping the waveform, a waveform shaping circuit 5 that is input to the control computer 2.

The current feedback circuit 3 includes a coil SL
Switching circuit 3a for interrupting the current flowing through
A current detection circuit 3b for detecting a drive current Ic flowing through L;
A control signal receiving circuit 3c that receives a control signal Va input from the control computer 2, a deviation integration circuit that operates based on the driving current Ic detected by the current detecting circuit 3b and the control signal Va received by the control signal receiving circuit 3c. 3d, and a switching control circuit 3e for controlling the switching circuit 3a to turn on and off according to the operation of the deviation integration circuit 3d.

The switching circuit 3a includes a transistor T
The transistor Tr1 has an emitter connected to the power supply Vcc, a base connected to the switching control circuit 3e, and a collector connected to the base of the transistor Tr2 via the resistor R1. On the other hand, the collector of the transistor Tr2 is a coil SL
Are connected to the current detection circuit 3b. Therefore, when the transistor Tr1 is turned on / off by the output voltage of the switching control circuit 3e,
The transistor Tr2 is turned on / off, and the coil SL is driven at the on / off duty ratio of the transistor Tr2.

The current detection circuit 3b includes resistors R2, R3,
It comprises R4, R5, R6, R7, R8 and R10, diode D1, and operational amplifier OP1. Resistor R
2 is connected to the transistor Tr of the switching circuit 3a.
2 and the other end is connected to the input minus side of the operational amplifier OP1 via a resistor R4. One end of the resistor R3 is connected to the collector of the transistor Tr2, and the other end is connected to the positive input side of the operational amplifier OP1. One end of the resistor R5 is connected to the emitter of the transistor Tr2, the other end is connected to the positive input side of the operational amplifier OP1, and one end of the resistor R7 is connected to the emitter of the transistor Tr2 and the other end is grounded. I have.

The negative input of the operational amplifier OP1 is grounded via a resistor R8, and the positive input of the operational amplifier OP1 is a resistor R6.
Grounded. Further, the output side and the input minus side of the operational amplifier OP1 are connected via a resistor R10. On the other hand, the connection point between the resistors R2 and R4 is
It is connected to one end of the battery BT via the diode D1. The resistor R7 is a resistor for detecting a current (a so-called ON current) flowing through the coil SL when the transistor Tr2 is in an ON state.
When the transistor Tr2 is turned off, the coil SL
Is a resistor for detecting a current (a so-called surge current) flowing through the coil SL by a back electromotive force generated in the coil SL. The resistors R3, R4, R5, and R8 are connected to the operational amplifier OP1.
The resistors R6 and R10 are resistors for determining the amplification factor of the operational amplifier OP1. Therefore, the current detection circuit 3b converts the drive current Ic (the on-current and the surge current) flowing through the coil SL into the operational amplifier OP
1 (hereinafter referred to as a “current detection voltage Vi”).

The diode D1 is connected to the transistor Tr
2 is turned off by a resistor R2
For flowing through. Control signal receiving circuit 3c
Is composed of a transistor Tr3 and resistors R12 and R13. The base of the transistor Tr3 is connected to the control computer 2, and the emitter is grounded. The collector of the transistor Tr3 is connected to the power supply Vcc via the resistor R12, and is grounded via the resistor R13. As a result, the transistor Tr3 is turned on / off by receiving the control signal Va from the control computer 2 at the base. The voltage appearing at the collector of the transistor Tr3 is determined by the saturation voltage between the collector and the emitter when the transistor Tr3 is turned on (low level), and when the transistor Tr3 is turned off, the resistors R12 and R13 are turned off.
, The divided voltage value (high level) of the power supply Vcc. Therefore, if the transistor Tr3 is driven using the control signal Va, a voltage having a waveform obtained by inverting the waveform of the control signal Va (hereinafter referred to as “reference voltage VD”) is output to the collector of the transistor Tr3. Thereby, the duty ratio of the control signal Va (hereinafter referred to as “the target duty ratio Dtr”
g ". ), The average value of the reference voltage VD changes linearly. Here, the target duty ratio Dtrg
Is given as a ratio of a low-level time to a repetition period Ttrg of the control signal Va (hereinafter, referred to as “target period Ttrg”). This is because when the control signal Va is in a low level state, the reference voltage VD is at a high level.

The maximum value of the reference voltage VD is determined by the coil SL
Is set higher than the current detection voltage Vi output by the operational amplifier OP1 in accordance with the maximum value of the drive current Ic of the first driving current Ic. It is set smaller than the detection voltage Vi.

The deviation integrating circuit 3d includes a resistor R14 (R1
4≫R12, R13) and the capacitor C1 are connected in series. One end of the resistor R14 is connected to the collector of the transistor Tr3 of the control signal receiving circuit 3c, and the other end of the resistor R14 detects the current through the capacitor C1. It is connected to the output side of the operational amplifier OP1 of the circuit 3b. As a result, the deviation integrating circuit 3d operates according to the difference between the reference voltage VD and the current detection voltage Vi.

The switching control circuit 3e comprises an operational amplifier OP2, which is a comparator, and a resistor R15. The positive input of the operational amplifier OP2 has a capacitor C
1 and the operational amplifier OP1 of the current detection circuit 3b, and the minus side of the input is connected to the capacitor C1 and the resistor R1.
4 is connected. The output side of the operational amplifier OP2 is connected to a switching circuit 3a via a resistor R15.
Is connected to the base of the transistor Tr1. As a result, the switching control circuit 3 e
The transistor Tr1 of the switching circuit 3a is turned on / off according to the polarity of the charging voltage of the capacitor C1 of d. The resistor R15 is a current matching resistor.

Next, the operation of the solenoid valve driving device according to the present embodiment will be described focusing on the deviation integration circuit 3d.
First, if the current detection voltage Vi output from the operational amplifier OP1 in accordance with the current Ic flowing through the coil SL is smaller than the reference voltage VD, the negative polarity of the input voltage of the operational amplifier OP2 is input after the delay time described later. It is larger than the plus side. As a result, the output of the operational amplifier OP2 becomes low level, the two transistors Tr1 and Tr2 of the switching circuit are turned on, the current flowing through the coil SL increases, and the current detection voltage Vi also increases.

On the other hand, if the current detection voltage Vi increases and becomes larger than the reference voltage VD, the polarity of the charging voltage of the capacitor C1 becomes smaller on the minus side of the input of the operational amplifier OP2 than on the plus side after a delay time described later. As a result, the output of the operational amplifier OP2 becomes high level,
Two transistors Tr1 and Tr2 of the switching circuit
Are turned off, the current flowing through the coil SL decreases, and the current detection voltage Vi also decreases.

Therefore, the current detection voltage Vi is equal to the reference voltage V
Since the control signal Va follows D with a delay time to be described later, when the control signal Va having the constant target duty ratio Dtrg is input, the electric charge charged in the capacitor C1 is reduced to 0 when averaged over the target cycle Ttrg. Become. Note that the above-mentioned delay time is a product of the response delay based on the inductance load of the coil SL and the time constant A of the deviation integration circuit 3d (the capacitance C1 of the capacitor C1 and the resistance value R14 of the resistor R14. = C1 × R14.), And the current detection voltage Vi changes at the same cycle as the reference voltage VD (ie, the target cycle) with a delay of this delay time. That is, the electric charge charged to the capacitor C1 of the deviation integration circuit 3d is equal to the target period Dtrg determined by the control signal Va.
Will change.

As described above, since the time average of the charge stored in the capacitor C1 is 0, if the time constant A is sufficiently larger than the target period Ttrg (A≫T),
The time average of the reference voltage VD and the current detection voltage Vi is equal. Thereby, the capacitor C1 is
Since the charge and discharge are repeated at the target cycle Ttrg and the polarity of the charge voltage is inverted, the operational amplifier OP2 operates at the target cycle Ttg.
On / off control of the coil SL is performed by rg. Further, as described above, since the current detection voltage Vi and the reference voltage VD have the same time average, the target duty ratio Dtrg and the time average of the drive current Ic flowing through the coil SL have a linear relationship. That is, the drive current I flowing through the coil SL
c is feedback-controlled by the target duty ratio Dtrg.

Although the operation of the solenoid valve driving device has been described above mainly on the operation of the deviation integration circuit 3d, the timing chart of FIG. 2 shows the above operation more specifically. As shown in FIG. 2A, when a control signal Va is output from the control computer 2, the polarity of the charging voltage of the capacitor C1 is inverted at the same cycle as the control signal Va (that is, the target cycle Ttrg). OP2 turns on / off the transistor Tr2 in response to the reversal of the polarity of the charging voltage of the capacitor C1. As a result, the drive current Ic flows through the coil SL with a ripple having the same cycle as the target cycle Ttrg (FIG. 2B), and the solenoid valve is slightly vibrated at that cycle. At this time, the transistor Tr
2 (i.e., the driving voltage Vc) is synchronized with the oscillation (i.e., ripple) of the driving current Ic, and the collector voltage of FIG.
It changes like That is, when the transistor Tr2 is on, the drive current Ic increases and the drive voltage Vc goes low, but when the transistor Tr2 turns off, a back electromotive force is generated in the coil SL, and the drive voltage Vc instantaneously rises. Then, as the drive current Ic is released as a surge current via the resistor R2 and the diode D1 and decreases, the drive voltage Vc also gradually decreases. Then, when the transistor Tr2 is turned on again, the drive current Ic increases and the drive voltage Vc becomes low.

When the coil temperature rises and the internal resistance of the coil SL increases as shown in FIG. 2E, the drive current Ic becomes difficult to flow, and the speed of the increase / decrease becomes slow. As a result, the ripple width W2 after the coil temperature rises becomes smaller than the ripple width W1 before the coil temperature rise of the drive current Ic, the frictional resistance of the solenoid valve increases, and the responsiveness decreases. .

As described above, when the coil temperature rises, the drive current Ic gradually increases and decreases, but at the same time, the energization duty ratio D increases. Here, the energization duty ratio D is a repetition cycle T of energization of the coil SL.
(Hereinafter referred to as “power supply cycle T”; always equal to target cycle Ttrg). Time Ton of power supply (on state of transistor Tr2) (hereinafter referred to as “power supply time Ton”).
Is the ratio of The drive current Ic is feedback-controlled by the duty ratio of the control signal Va regardless of the internal resistance of the coil SL. However, when the current hardly flows through the coil SL, the drive current Ic is operated in a direction in which the energization duty ratio D increases. When the current easily flows through the coil SL, the operation is performed by operating the energization duty ratio D in a smaller direction. That is, since the drive current Ic is feedback controlled, the energization duty ratio D after the coil temperature rises
h (Electrification time and energization cycle after coil temperature rise
If onh and Th, then Dh = Tonh / Th. )
Is larger than the energization duty ratio Dl before the coil temperature rise (Dl = Tonl / Tl if the energization time and energization cycle before the coil temperature increase are Tonl and Tl).

Therefore, in the present embodiment, the energization duty ratio D is measured, and based on the change, it is determined whether or not the coil temperature has risen. If it is determined that the coil temperature has risen, the control signal Va Change the cycle longer. This way,
The ripple width of the drive current Ic can be increased, and the frictional resistance of the solenoid valve can be reduced.

To calculate the energization duty ratio D, first, the waveform of the drive voltage Vc is shaped by the waveform shaping circuit 5 (FIG. 2 (d)), and is taken into the control computer 2 as the drive voltage signal Vb. The drive voltage signal Vb is input to the control computer 2 as a pulse signal. A low level state of the pulse signal indicates that the transistor Tr2 is on, and a high level state indicates that the transistor Tr2 is off. You can see that. Therefore, the energization duty ratio D can be obtained as a ratio of the period of the low level state to the repetition period of the drive voltage signal Vb.

A control process performed by the control computer 2 to perform such a process will be described below with reference to FIGS. The target duty calculation process shown in FIG. 3A is a process that is started at predetermined time intervals. In order to control the drive current Ic to flow through the coil SL that determines the opening of the solenoid valve, the duty ratio of the control signal Va Is a process for calculating.

When the target duty calculation process is started, first, the coil S is calculated based on the target opening of the solenoid valve.
A target current value I which is a target value of the drive current Ic to be passed through L
Calculate trg (Step 110; hereinafter “Step”)
Is denoted as “S”. ). Then, the target duty ratio Dtrg is determined based on the target current value Itrg (S12).
0). The control signal Va is output at the target duty ratio Dtrg determined in this way and the target cycle Ttrg set in a process different from the present process.

The target duty ratio Dtrg is set so that the drive current Ic having the strength of the target current value Itrg flows.
What is obtained experimentally in advance is stored in the control computer 2, and as shown in FIG. 3B, the target current value It
The target duty ratio Dtrg corresponds to rg on a one-to-one basis. Further, the target opening is calculated by the control computer 2 as an operation different from the operation as the present solenoid valve control device in accordance with the operating conditions of the internal combustion engine.

On the other hand, the energization duty ratio calculation process shown in FIG. 4A is a process for calculating the energization duty ratio D in order to determine a change in the coil temperature, and is a process for calculating the pulse waveform of the drive voltage signal Vb. It is activated by an interrupt at the falling edge. As described above, the coil SL is controlled by the control signal Va (FIG. 4B) output from the control computer 2.
A drive current Ic (FIG. 4C) flows through the control computer 2, and the waveform of the drive voltage Vc at this time is taken into the control computer 2 as a drive voltage signal Vb. The falling and rising times of the pulse waveform of the drive voltage signal Vb are sequentially stored in a register in the control computer 2 as a falling time Tn and a rising time Tp, respectively, and this energization duty calculation process is started. First, the energizing time To from the previous fall to the current fall
n is calculated (S210). Then, an energization cycle T, which is the elapsed time from the previous fall to the current fall, is calculated (S220), and the energization duty ratio Don during that is calculated (S230).

More specifically, in FIG. 4D, assuming that the present process is started at the falling time Tn2, for example, the coil SL is switched between the previous falling time Tn1 and the current falling time Tn2. Is supplied from the previous fall time Tn1 and the previous rise time Tp1 as Ton1 = Tp1-Tn1 (1). The energization cycle T1, which is the elapsed time from the previous fall time Tn1 to the current fall time Tn2, is obtained by T1 = Tn2−Tn1 (2), so that the energization duty ratio Don1 during that time is obtained.
Can be obtained from the energization time Ton1 and the energization cycle T1 calculated as described above by the following expression: Don1 = Ton1 / T1 (3)

In this way, the energization duty ratio Don between the previous fall and the present fall is calculated by the processing from S210 to S230, but the spontaneous noise, the fluctuation of the battery voltage + B, etc. May affect the calculation result. Therefore, in the present embodiment, each time the energization duty ratio Don calculated in this process started in the past is calculated, the energization duty ratio Don is stored, and N times of the predetermined number of times including the energization duty ratio Don calculated this time are used in the past. The energization duty ratio Don (the optimum value is determined by experiment) is averaged (S240). That is, based on N energization duty ratios Don1 to DonN including the energization duty ratio DonN calculated this time, an average value (hereinafter referred to as “average energization duty ratio Da”) is given by Da = (Don1 + Don2 +... + DonN) / N (4) Is calculated.) In this way, by averaging a predetermined number of times in the past, it is possible to eliminate the effects of sporadic noise and fluctuations of the battery voltage + B.

The cycle changing process shown in FIG. 5 is a process started at predetermined time intervals. The coil temperature fluctuates based on the average energization duty ratio Da calculated in the energization duty ratio calculation process. This is a process of determining whether or not the target period Ttrg of the control signal Va is changed according to the determination result.

When the cycle changing process is started, first, it is determined whether or not the battery voltage + B is equal to or higher than a predetermined voltage (hereinafter, referred to as "coil temperature determination permission voltage") (S310). This determination is made based on the battery voltage + B
When the coil temperature is greatly reduced (for example, when the internal combustion engine is started), a sufficient current cannot be supplied to the coil SL, and the energization duty ratio D (and hence the average energization This is because, since the duty ratio Da) becomes large, it may be erroneously determined that the coil temperature has changed in this process. In order to eliminate this erroneous determination, it is checked whether or not the battery voltage + B is equal to or higher than the coil temperature determination permission voltage.
310: “NO”), the present process is temporarily ended.

On the other hand, when it is determined that the battery voltage + B is equal to or higher than the coil temperature determination permission voltage (S310: "YE
S "), a coil temperature determination duty ratio Dtmp (hereinafter," determination duty ratio Dtmp ") for determining a change in coil temperature based on the current target cycle Ttrg and target duty ratio Dtrg of the output control signal Va.
Is calculated (S320). The determination duty ratio Dtmp is used for determining the magnitude comparison with the average energization duty ratio Da, as described later. When the average energization duty ratio Da is larger than the determination duty ratio Dtmp, the coil temperature is determined. Is judged to have risen,
The target cycle Ttrg is lengthened.

The calculation of the determination duty ratio Dtmp is specifically performed as follows.

[0045]

[Table 1]

As shown in Table 1, the horizontal axis (tentatively, the X axis)
, The target cycle Ttrg is plotted on the vertical axis (tentatively, the Y axis), and the intersection of X and Y is
A two-dimensional map in which a determination duty ratio Dtmp obtained in advance by an experiment is recorded is stored. Then, the coil determination duty ratio Dtmp is determined by referring to the two-dimensional map using the target duty ratio Dtrg and the target period Ttrg (or interpolating if there is no corresponding numerical value). For example,
Target duty ratio Dtrg = Dtrg3, target cycle Tt
If rg = Ttrg2, it is determined that the determination duty ratio Dtmp = Dtmp32.

As described above, the determination duty ratio Dtmp is determined based on the target duty ratio Dtrg and the target period Ttrg.
Is calculated for the following reason. That is, the average energization duty ratio Da is determined by the current feedback control.
At an actual coil temperature, the solenoid valve is operated to a value corresponding to a target current value Itrg to be passed through the coil SL in order to control the solenoid valve to a target state (in this embodiment, a target opening). Therefore, it is necessary to calculate the determination duty ratio Dtmp for determining the fluctuation of the coil temperature in comparison with the average energization duty ratio Da based on the target opening of the solenoid valve and the coil temperature. On the other hand, the target opening degree of the solenoid valve and the coil temperature are respectively set to a target current value Itrg (accordingly, a target duty ratio Dtrg) to be passed through the coil to control the solenoid valve to a target state.
In addition, it can be indirectly known from the energization cycle T (that is, the target cycle Ttrg) that is changed to be longer or shorter according to the vertical fluctuation of the coil temperature. For these reasons, the duty ratio Dtmp for determination is calculated based on the target duty ratio Dtrg and the target cycle Ttrg.

The average energization duty ratio Da increases as the target current value Itrg to be passed through the coil SL for controlling the solenoid valve to the target opening increases and as the coil temperature increases. Therefore, the duty ratio Dtmp for determination also increases as the target duty ratio Dtrg corresponding to the target current value Itrg increases.
The longer the target cycle Ttrg indirectly indicating the coil temperature is, the larger the value is recorded in the two-dimensional map.

If the average energization duty ratio Da becomes smaller than the determination duty ratio Dtmp as a result of a decrease in coil temperature or a change to lengthen a target period Ttrg to be described later, the target period Ttrg is shortened immediately. However, in such a case, hunting may occur and the opening characteristics of the solenoid valve may be affected. Therefore, in the present embodiment, the target cycle Ttrg and the target duty ratio Dtrg of the current control signal Va are set.
, The hysteresis Dhys of the coil temperature determination duty ratio Dtmp is calculated (S330). As described later, the average energization duty ratio Da is determined by the hysteresis D
When the hys is smaller than the value obtained by subtracting the hysteresis from the determination duty ratio Dtmp, the target cycle Ttrg is shortened.

The calculation of the hysteresis Dhys is specifically performed as follows.

[0051]

[Table 2]

As shown in Table 2, the horizontal axis (tentatively, the X axis)
Is stored in a two-dimensional map in which the target duty ratio Dtrg is taken, the target cycle Ttrg is taken on the vertical axis (tentatively the Y axis), and the hysteresis Dhys predetermined in the experiment is recorded at each intersection of X and Y. Then, the target duty ratio Dt
The hysteresis Dhys is determined by referring to the two-dimensional map using rg and the target cycle Ttrg (or interpolating if there is no corresponding numerical value). For example, the target duty ratio Dt
When rg = Dtrg3 and target cycle Ttrg = Ttrg2, the hysteresis Dhys = Dhys32 is determined. Now, based on the two-dimensional map shown in Table 1, the determination duty ratio Dtmp for comparison with the average energization duty ratio Da is determined. However, as shown in FIG. The increase speed fluctuates. For example, when the battery voltage + B decreases, the increasing speed of the drive current Ic decreases, and as a result, the average energization duty ratio Da increases. Therefore, in order to distinguish between the fluctuation of the average energization duty ratio Da due to the fluctuation of the battery voltage + B and the fluctuation due to the coil temperature fluctuation, in the present embodiment, the battery voltage + B is detected via the ADC 4, and the detection is performed. Based on the value, the duty ratio for determination Dtmp
Of the correction coefficient Dcv for correcting (S34)
0).

The calculation of the correction coefficient Dcv is specifically performed as follows.

[0054]

[Table 3]

As shown in Table 3, a correction coefficient Dcv corresponding to the battery voltage + B on a one-to-one basis is stored. Then, based on the battery voltage + B, the correction coefficient Dcv is determined (if there is no corresponding numerical value, interpolation is performed). For example, when the battery voltage + B = V2, the correction coefficient Dc
It is determined that v = Dcv2. Since the average energization duty ratio Da decreases as the battery voltage + B increases, the correction coefficient Dcv is also stored so as to decrease as the battery voltage + B increases.

As described above, the determination duty ratio Dtm
When p, the hysteresis Dhys, and the correction coefficient Dcv are determined (S320 to S340), the average energization duty ratio Da changes the determination duty ratio Dtmp to the correction coefficient Dcv.
(Hereinafter referred to as “first reference value λh”. Λh≡
Dtmp × Dcv. ) Is determined (S35).
0).

First, when the average energization duty ratio Da is larger than the first reference value λh (S350: “YE
S "), it is determined that the coil temperature has risen, and first, based on the target cycle Ttrg, the coil high-temperature side cycle correction value Tch
Is calculated (S360). Coil high temperature side cycle correction value Tc
The calculation of h is specifically performed as follows.

[0058]

[Table 4]

As shown in Table 4, the coil high-temperature side cycle correction value Tch corresponding to the target cycle Ttrg on a one-to-one basis is stored. Then, based on the current target cycle Ttrg, the coil high-temperature side cycle correction value Tch is referred to (if there is no corresponding numerical value, interpolation is performed). For example, the target cycle Tt
When rg = Ttrg2, it is determined that the coil high-temperature side cycle correction value Tch = Tch2.

The correction of the target cycle Ttrg is performed by adding the coil high-temperature side cycle correction value Tch thus determined (S380). However, if the cycle of the minute vibration of the solenoid valve becomes too long, the frictional resistance is suppressed. The effect of doing so is diminished. Therefore, the target cycle Tt
The maximum target cycle Tmax is stored in advance as the upper limit of rg, and before correcting the target cycle Ttrg, it is determined whether or not the result of the correction exceeds the maximum target cycle Tmax (S370). Then, when it is determined that the correction result does not exceed the maximum target cycle Tmax (S370:
“NO”) is the sum of the current target cycle Ttrg and the coil high-temperature-side cycle correction value Tch as a new target cycle Ttr.
It is set as trg (S380), and this process is once ended. When it is determined that the correction result exceeds the maximum target cycle Tmax (S370: “YES”), the present process is temporarily terminated without changing the target cycle Ttrg.

When it is determined in S350 that the average energization duty ratio Da is equal to or smaller than the first reference value λh (S350: “NO”), a value obtained by subtracting the hysteresis Dhys from the first reference value λh ( Hereinafter, it is determined whether it is smaller than “second reference value λ1” (λlλDtmp × Dcv−Dhys) (S390). At this time, if the average energization duty ratio Da is larger than the second reference value λl (S390: “NO”), the current target cycle Ttrg
Since there is no need to change, this process is temporarily ended.

On the other hand, when the average energization duty ratio Da is smaller than the second reference value λ1 (S390: “YES”), first, the coil low-temperature side cycle correction value Tcl is calculated based on the target cycle Ttrg (S400). . The calculation of the coil low temperature side cycle correction value Tcl is performed by the coil high temperature side correction value Tch.
Is performed in the same manner as described above. That is, as shown in Table 4, the target period T
The coil low-temperature cycle correction value Tcl corresponding to trg on a one-to-one basis is stored, and the coil low-temperature cycle correction value Tcl is referenced based on the current target cycle Ttrg (if there is no corresponding numerical value, Interpolation). For example, the target cycle T
When trg = Ttrg2, it is determined that the coil low-temperature side cycle correction value Tcl = Tcl2.

The correction of the target cycle Ttrg is performed by subtracting the coil low-temperature side cycle correction value Tcl thus determined (S420). However, if the energization cycle T becomes too short, the pulse output per unit time increases. Therefore, the processing load on the control computer 2 increases. Therefore, the minimum target cycle Tmin is stored in advance as the lower limit of the target cycle Ttrg, and before the correction of the target cycle Ttrg, it is determined whether or not the result of the correction is smaller than the minimum target cycle Tmin (S410). The result of the correction is the minimum target cycle T
min (S410: “N
O ”) is a value obtained by subtracting the coil low-temperature side cycle correction value Tcl from the current target cycle Ttrg to obtain a new target cycle Ttr.
g is set (S420), and this process is once ended.
When it is determined that the result of the correction is smaller than the minimum target cycle Tmin (S410: "YES"), the present process is temporarily terminated without changing the target cycle Ttrg.

As described above, in the solenoid valve driving device of the present embodiment, the drive voltage Vc (ie, drive voltage signal Vb) of the coil SL is detected, and the energization duty ratio D (ie, average energization duty ratio Da) is obtained. Then, based on the average energization duty ratio Da, a change in the coil temperature is detected, and when it is determined that the coil temperature has increased,
If the cycle of the control signal Va is changed to be longer and it is determined that the coil temperature has decreased, the cycle of the control signal Va is changed to be shorter. Thus, the ripple width of the drive current Ic can be maintained, and an increase in the frictional resistance of the solenoid valve can be suppressed. As a result, the responsiveness of the solenoid valve can be ensured even when the temperature of the coil SL increases.

For example, the coil temperature rises (see FIG. 7).
(E)) Consider a case where the ripple width W2 of the drive current Ic after the coil temperature rises becomes narrower than the ripple width W1 before the coil temperature rise (FIG. 7B). In this case, by measuring the drive voltage Vc of the coil SL (FIG. 7C), the energization duty ratio D is changed from the energization duty ratio Dl (DI = Tonl / Tl) before the coil temperature rise to the energization after the coil temperature rise. It is detected that the duty ratio has increased to Dh (Dh = Tonh / Th) (FIG. 7D), and the control signal Va is detected.
(Ie, the target cycle Ttrg) is increased (see FIG. 7).
(A)). As a result, the ripple width W3 after changing the cycle is
It becomes wider than the ripple width W2 before the cycle change (FIG. 7).
(B)), the increase in the frictional resistance of the solenoid valve is suppressed, and the responsiveness of the solenoid valve is ensured.

In this embodiment, the battery BT corresponds to the power supply, the signal output from the operational amplifier OP2 corresponds to the duty signal, and the switching circuit 3a corresponds to the driving means. The processing of the control signal receiving circuit 3c, the deviation integrating circuit 3d, the switching control circuit 3e, and S120 constitutes a duty signal generating means. Also, S35
The processing of 0 and S390 corresponds to the processing as temperature determination means. Also, S360 to S380 and S400 to S4
The processing of 20 corresponds to the processing as signal period changing means. Further, the current detection circuit 3b corresponds to a state detection unit. Further, the waveform shaping circuit and S210 to S240, S
The processes of 320 and S330 correspond to a reference value calculation unit. Further, the processing of the ADC 4 and S340 constitutes a reference value correction unit.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can take various forms. For example, in the solenoid valve driving apparatus of the above embodiment, the description has been given assuming that the average energization duty ratio Da is calculated. However, the cycle change processing is performed without calculating the average energization duty ratio Da and directly changing the energization duty ratio D. It is also possible to use it. However, in such a case, it is preferable that the average energization duty ratio Da be calculated and used because there is a possibility of being affected by a single-shot fluctuation of the battery voltage + B and noise. Further, the method of calculating the average energization duty ratio Da is not limited to the above equation (4), and a weighted average for averaging with appropriate weighting for each energization duty ratio D may be used.

Further, in the solenoid valve driving apparatus of the above embodiment, the correction of the target cycle Ttrg (that is, the energizing cycle T) determines the coil temperature based on the average energizing duty ratio Da (or energizing duty ratio D). However, the present invention is not limited to this. For example, the coil temperature is configured to be directly detected by a temperature sensor,
The target cycle may be corrected in consideration of the temperature characteristics of the resistance value of the coil. A position sensor capable of detecting the actual opening of the solenoid valve is provided to measure a response delay of the actual opening with respect to a change in the target opening, and the coil temperature is determined based on the response delay of the actual opening. May be.

Further, in the solenoid valve driving apparatus of the above embodiment, the driving current Ic flowing through the coil SL is feedback-controlled by the current feedback circuit 3 to drive the solenoid valve. Is not limited to the one that performs feedback control. For example, as shown in FIG. 8, the actual opening of the solenoid valve is detected by the position sensor, and the drive current is operated so as to eliminate the deviation of the actual opening from the target opening calculated based on the operating conditions of the internal combustion engine. Alternatively, a solenoid valve driving device configured to feedback-control the opening degree of the solenoid valve may be used. In the solenoid valve driving device having such a configuration, when the coil temperature rises and the driving current hardly flows through the solenoid valve, the on / off duty ratio of the solenoid valve driving is maintained in order to maintain the actual opening at the target opening. An operation of increasing the drive current (corresponding to the energization duty ratio D in the above embodiment) and maintaining the drive current is performed. Therefore, as in the above-described embodiment, the responsiveness of the solenoid valve can be ensured by determining the coil temperature based on the ON / OFF duty ratio (temperature determination unit) and changing the target cycle. When changing the target opening of the solenoid valve, the solenoid valve is driven at an expected duty ratio so that a current corresponding to the target opening flows through the coil, and then the actual opening of the solenoid valve is measured by a position sensor. While feeding back the measurement results,
When a duty signal having a duty ratio corresponding to the current to be passed through the coil is generated, when the temperature of the coil rises, the actual opening and the target opening when the solenoid valve is driven at the expected duty ratio are increased. Since the deviation from the degree increases, the temperature of the coil can be determined based on the deviation between the two. Also in the apparatus, the coil temperature may be directly detected by the temperature sensor, and the target cycle may be corrected in consideration of the temperature characteristics of the resistance value of the coil.

FIG. 8 shows that the actual opening is controlled to coincide with the target opening, that is, "the opening of the solenoid valve".
Although the solenoid valve driving device that performs feedback control as a control amount has been described, the present invention is not limited to this, and it is also possible to drive the solenoid valve by feeding back the flow rate and other physical quantities of the fluid controlled by the solenoid valve. The invention described in can be applied.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an electrical configuration of a solenoid valve driving device as one embodiment of the present invention.

FIG. 2 is a time chart showing the operation of each part of the solenoid valve driving device of the embodiment before and after the coil temperature rises.

FIG. 3A is a flowchart illustrating a target duty calculation process executed in the solenoid valve driving device according to the embodiment, and FIG. 3B is a graph illustrating a correspondence relationship between a target current value and a target duty ratio. .

FIG. 4A is a flowchart illustrating an energization duty calculation process performed in the solenoid valve driving device according to the embodiment, and FIGS. 4B to 4D are diagrams illustrating operations and energization of each unit of the solenoid valve driving device. 6 is a time chart showing a relationship between duty ratios.

FIG. 5 is a flowchart showing a cycle changing process executed in the solenoid valve driving device according to the embodiment.

FIG. 6 is an explanatory diagram showing a change in an increasing speed of a drive current due to a change in a battery voltage.

FIG. 7 is a time chart showing the operation of each part of the solenoid valve driving device according to the embodiment before and after the correction of the target cycle.

FIG. 8 is a block diagram showing a configuration of a solenoid valve driving device as a modification.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 solenoid valve driving device 2 control computer 3 current feedback circuit 3 a switching circuit 3 b current detection circuit 3 c control signal receiving circuit
3d: deviation integration circuit, 3e: switching control circuit, 4
... A / D converter, 5 ... waveform shaping circuit, BT ... battery, SL ... coil.

Claims (4)

[Claims] 1. A driving unit that is energized by a current from a power supply to intermittently energize a coil that drives a solenoid valve, and generates a duty signal having a duty ratio according to a current to be passed through the coil at a predetermined cycle. A duty signal generating means for supplying the generated duty signal to the driving means to drive the driving means; and a temperature judging means for judging a change in the temperature of the coil; In accordance with the variation in the temperature of the coil determined by the temperature determining means, the generation cycle of the duty signal generated by the duty signal generation means is increased as the temperature of the coil increases. And a signal cycle changing means for setting. 2. The solenoid valve driving device according to claim 1, further comprising: a state detecting unit that detects an operation state of the solenoid valve driven by the solenoid valve driving unit, wherein the duty signal generating unit includes the state detection unit. On the basis of the deviation between the actual operating state of the solenoid valve and the target state detected by the detecting means, a duty signal having a duty ratio corresponding to the current to be supplied to the coil for controlling the solenoid valve to the target state is generated. The temperature determination means is configured to provide a reference value for determining a change in the temperature of the coil from a duty ratio of a duty signal generated by the duty signal generation means to the duty signal generation means. Calculated based on the generation cycle of the generated duty signal and the current to be passed through the coil. Comparing the reference value calculated by the reference value calculation means with the duty ratio of the duty signal generated by the duty signal generation means, and determining that the duty ratio is larger than the reference value. When it is determined that the temperature of the coil has risen, when the duty ratio is smaller than the reference value, it is determined that the temperature of the coil has fallen. When it is determined that the temperature of the coil has risen, the generation cycle of the duty signal generated by the duty signal generation means is lengthened, and when it is determined by the temperature determination means that the temperature of the coil has decreased, A solenoid valve driving device characterized by shortening the generation cycle. 3. The solenoid valve driving device according to claim 2, wherein the reference value calculation unit includes, as the reference value, a first reference value for determining whether or not the temperature of the coil has increased; Calculating a second reference value smaller than the first reference value for determining whether or not the temperature of the coil has decreased; and the first determination unit calculates the first reference value calculated by the reference value calculation unit. The value of the coil is increased when the duty ratio is greater than the first reference value by comparing each of the value and the second reference value with the duty ratio of the duty signal generated by the duty signal generation means. And determining that the temperature of the coil has dropped when the duty ratio is smaller than the second reference value. 4. The solenoid valve driving device according to claim 2, wherein the temperature determination unit determines a voltage of the power supply based on a voltage of the power supply based on a reference value calculated by the reference value calculation unit. A reference value correcting means for correcting the reference value to be smaller as the value becomes higher, and comparing a reference value corrected by the reference value correcting means with a duty ratio of a duty signal generated by the duty signal generating means. Solenoid valve driving device.