JPH10184975A - Controller for solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a solenoid valve following a driving current even if a change occurs in the operational delay characteristic of the solenoid valve after the lapse of time by renewing information on operational delay time store by a memory means according to a change in a driving current detected by a current detection circuit. SOLUTION: When a control output for making a switch circuit 2 conductive is sent from the CPU 10 of a control circuit 3 for opening/closing a solenoid valve 1, a driving current is supplied to the solenoid valve 1. This driving current is detected by a current detection circuit 5, its detected output is inputted to the control circuit 3 to perform time rating for a detected current value and, when the value is changed from positive to negative, the operation of the shaft core of the solenoid valve 1 is determined. Also, a time Δt from the start of current increase to a differential value 0 is set as the operation delay time of the solenoid valve 1. Then, information Δto on operation delay time stored in a memory means 14 is read, an operation of κ(Δto-Δt)/Δt| is carried out and, when a calculated value exceeds a threshold value, Δto is replaced by Δt for renewal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a device for opening and closing a solenoid valve at a high speed. The present invention relates to an improvement of an apparatus for program-controlling a solenoid valve according to a preset procedure. The present invention relates to an improvement in a control device that copes with a variation in operation delay time of a solenoid valve or a change with time. Although the present invention has been developed for use in a control device for an internal combustion engine, the present invention can be widely used not only for an internal combustion engine but also for a device for controlling a solenoid valve by computer.

[0002]

2. Description of the Related Art In recent years, a fuel injection device of a diesel engine uses a program control circuit (CPU) to control the opening and closing of a solenoid valve inserted into a fuel supply passage according to a preset procedure, thereby injecting fuel. Techniques for controlling the timing and injection quantity with high precision have come to be used. In such an apparatus, any control by software of a program control circuit, for example, opening and closing control with an accuracy of, for example, 1 millisecond or less can be substantially performed. Also for a switch circuit that controls opening and closing of the drive current of the solenoid valve, high-speed and stable switch control can be performed by using a semiconductor switch element.

[0003] Solenoid valves as parts have also been miniaturized and made more precise, and those which can control fuel intermittently with the rotation of the internal combustion engine have been obtained. It is a mechanical component involved, and has an operation delay time from when the drive current is turned on or off to when the valve is actually opened or closed. This operation delay time is electrically determined by the transient response characteristics of the coil, that is, equivalent impedance, etc., and mechanically, the mass of the solenoid valve drive rod, the constant of the return spring, the mass of the valve to be opened and closed,
Driving distance, driving speed, inertia, and the like influence.

Conventionally, manufacturing tolerances of solenoid valves have been strictly controlled, and the operation delay time or the operation delay characteristics of the solenoid valves have been manufactured uniformly.

On the other hand, control of an internal combustion engine accompanied by opening / closing control of a solenoid valve has become faster and more precise. The value of the operation delay time is several milliseconds, and the required precision error is 1/1.
It has reached 0 ms or 1/100 ms.

[0006]

If the accuracy of the operation delay time is set by manufacturing control, the manufacturing yield becomes extremely low, and the component price of the solenoid valve increases. Further, such accuracy cannot be met even if the allowable manufacturing accuracy is set strictly. Furthermore, in addition to the manageable factors that affect the operation delay characteristics as described above,
There are factors that are difficult to control, such as the state of contact between the movable part and the fixed part, the attachment of foreign matter, and the like, and the accuracy affected by these factors is required. Moreover, they are affected by the operating temperature and change over time, and it is impossible to obtain a uniform product no matter how strict the production control is, and the initial values are uniform. However, proper operation cannot be expected.

The present invention has been made in view of such a background, and an object of the present invention is to provide a control device capable of coping with a non-uniform operation delay characteristic of a solenoid valve. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device that can cope with a change in the operation delay characteristic of a solenoid valve due to the influence of temperature or the like. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device capable of following an operation delay characteristic of an electromagnetic valve even if the operation delay characteristic changes over time. An object of the present invention is to ease manufacturing control of a solenoid valve. An object of the present invention is to provide an inexpensive electromagnetic valve that performs high-precision control. The present invention
An object of the present invention is to improve the operation delay characteristics of a solenoid valve which can be handled by software without adding hardware or improving hardware.

[0008]

SUMMARY OF THE INVENTION The present invention focuses on the fact that the drive current of a solenoid valve is subtly changed according to the mechanical operation of the solenoid valve. The delay characteristic is electrically detected, and the operation delay characteristic is fed back to the control.

That is, the present invention comprises a switch circuit for opening and closing the drive current of the solenoid valve, and a control circuit for controlling the switch circuit according to a procedure set according to a control input, and the control circuit stores the procedure. In a control device for an electromagnetic valve including a memory unit, the memory unit includes:
Information of the operation delay time unique to the solenoid valve is stored, and a current detection circuit for detecting the drive current and supplying the detected current to the control circuit is provided. The control circuit includes a change in the drive current detected by the current detection circuit. Means for updating the information of the operation delay time stored in the memory means in accordance with the following.

The control circuit includes means for differentiating the output of the current detection circuit with time, and the information of the operation delay time is supplied to the switch circuit after giving a control output for making the switch circuit conductive. It is information indicating a time until an output of the time differentiating means becomes zero n times (n is an integer of 1 or more) and the current detection circuit includes a current transformer inserted in a path of the drive current. desirable.

A control circuit controls a switch circuit for opening and closing the drive current of the solenoid valve according to a procedure stored in the memory. Since information on the operation delay time unique to the solenoid valve is stored in the memory means in advance, control can be performed in consideration of the operation delay time unique to the solenoid valve. In other words, even if there is manufacturing variation in the operation delay time of the solenoid valve,
This can be absorbed at the time of control, and highly accurate control can be performed. Therefore, the production control of the solenoid valve becomes lenient, and the production yield can be improved.

Further, the control circuit updates the information of the operation delay time stored in the memory means each time according to the change of the drive current detected by the current detection circuit, and performs control based on the latest information. As a result, even when the operation delay characteristic of the solenoid valve is not uniform, or even if the delay time changes due to the influence of temperature or the like, or even if the delay time changes over time, the delay time changes appropriately. The solenoid valve can be operated. Further, since the present invention can be controlled by software without adding or improving hardware, the manufacturing control of the solenoid valve can be eased and the manufacturing cost of the solenoid valve can be reduced. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment of the present invention.

The first embodiment of the present invention is provided with a switch circuit 2 for opening and closing the drive current of the solenoid valve 1, and a control circuit 3 for controlling the switch circuit 2 in accordance with a set procedure according to a control input. The control circuit 3 includes a memory means 4 for storing the procedure and a CPU 10. Further, as a feature of the present invention, the memory means 4 is provided with a current detection circuit 5 which stores information on the operation delay time unique to the solenoid valve 1 and detects the drive current and supplies it to the control circuit 3.
The control circuit 3 includes means for updating the information of the operation delay time stored in the memory means 4 in accordance with the change in the drive current detected by the current detection circuit 5,
Means for differentiating the output with respect to time. The information on the operation delay time is the time from when the control output for turning on the switch circuit 2 is given to the switch circuit 2 until the output of the time differentiating means becomes zero n times (n is an integer of 1 or more). Is information representing In this embodiment, n = 1.

The current detection circuit 5 includes a current transformer 6 inserted in a drive current path, and an amplifier 9 for amplifying an output voltage of the current transformer 6. The output from the current detection circuit 5 is converted into a digital signal by the A / D converter 15 and connected to the CPU 10. Switch circuit 2
, A MOS transistor 7 is used, and the control circuit 3
The control output from the CPU 10 is amplified by the drive circuit 12 and sent to the gate of the MOS transistor 7.
The engine 13 is provided with a rotation sensor 14, and a detection output thereof is transmitted to the CPU 10 via an interface I / O.
Connected to.

Next, the operation of the first embodiment of the present invention will be described. FIG. 2 is a flowchart showing a flow of the operation in the first embodiment of the present invention. The control circuit 3 calculates the fuel injection timing in accordance with the rotation of the engine 13 and controls the opening and closing of the solenoid valve 1. However, the timing control is not directly related to the present invention, and the description is omitted. The operation will be described as an example.

As shown in FIG. 3A, the control circuit 3
When the control output from the PU 10 to the solenoid valve 1 is sent to the switch circuit 2 as an ON signal, the drive circuit 12 amplifies the control output and outputs it to the MOS transistor 7. M
When the OS type transistor 7 receives this control output, it becomes conductive, and a driving current is supplied from the battery 16 to the solenoid valve 1.

The drive current is detected by the current detection circuit 5 and the detection output is sent to the control circuit 3. FIG. 3B shows an example of this current waveform. That is, the current value increases after the switch circuit is turned on, but if the waveform of the increase in the current value is carefully examined, the current value sometimes drops once during the increase. When this was examined in detail, it was found that the shaft core of the solenoid valve was operated and mechanically displaced at the timing when the current value dropped. This is the timing when the mechanical displacement actually occurs, and the change in the current value allows the operating characteristics of the solenoid valve to be known.

The control circuit 3 converts this detection output into a digital signal by the A / D converter 15, and the CPU 10 takes in this output. The CPU 10 performs time differentiation of the detected current value, and it is assumed that the axis of the solenoid valve 1 operates when the value changes from positive to negative as shown in FIG. As shown in FIG. 3B, the time Δt from the start of the current rise until the differential value becomes zero is set as the operation delay time of the solenoid valve 1 in the apparatus of the present invention.

[0022] Then, CPU 10 reads the information Delta] t ₀ of the operation delay time stored in the memory means _{4, | (Δt 0 -Δt)} / Δt | of performed operations, whether it is less than a preset threshold Is determined. If the calculated value is equal to or less than the threshold value, it is determined that the operation delay time of the solenoid valve 1 has not changed, and the value of Δt ₀ in the memory means 4 is not changed. If the calculated value exceeds the threshold value, it is determined that there has been a change with respect to the operation delay time Δt ₀ stored in the memory means 4, and Δt ₀ is replaced with the calculated value Δt and updated. At the time of starting the CPU 10, it is preferable that a standard value is input to Δt ₀ .

As described above, the operation delay time Δt is measured each time the solenoid valve 1 is driven, and control is performed according to the operation delay time Δt corresponding to the situation at that time.
Even if the operation delay characteristic changes with temperature or changes over time, appropriate control can always be performed.

(Second Embodiment) FIG. 4 is a diagram showing a configuration of a main part of a current detection circuit according to a second embodiment of the present invention, and FIG.
FIG. 9 is a diagram showing a change at the time of current when the solenoid valve is operated in the second embodiment, and FIG. 10B is a diagram showing a change of a time differential value of an output of a current detection circuit.

In the circuit of the second embodiment of the present invention, a series circuit of a resistor R ₁ and a diode D is connected in parallel with the coil of the solenoid valve 1, and a protection resistor R _{2 is} provided in the current path of the MOS transistor 7. Is inserted. This circuit is a circuit suitable for implementing the present invention. That is, the solenoid valve 1
When the MOS transistor 7 is turned off while a DC current is being supplied to the coil, the current accumulated in the coil of the solenoid valve 1 is generated by the energy stored in the coil. Since this may exceed the limit voltage across the MOS transistors 7, by the diode D in order to prevent this bypass this current, so as to absorb this in resistor R _1.

In such a configuration, a current transformer is not required, and current can be detected by measuring the voltage across the resistors R ₁ and R ₂ . That is, by connecting the voltage detector 18 as shown in FIG. 4, it is possible to detect the current flowing through the MOS transistor 7.

In this case, the operating current of the solenoid valve 1 is as shown in FIG.
Is observed, and the operation delay time Δt of the solenoid valve 1 is
Is that the current differential waveform becomes zero the third time (n = 3) when the solenoid valve is turned on.

[0028]

As described above, according to the present invention, the operation delay characteristic of the solenoid valve inserted in the fuel supply passage of the diesel engine is not uniform, and changes due to temperature or the like, or changes with time. Even so, the operation of the solenoid valve can be made to follow this. Since the present invention can be implemented by software without adding or improving hardware, it is easy to control the manufacturing of the solenoid valve, and it is possible to loosen the processing accuracy of the component parts, thereby reducing the manufacturing cost of the solenoid valve. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of operation in the first embodiment of the present invention.

3A is a diagram showing opening and closing of a solenoid valve according to the first embodiment of the present invention, FIG. 3B is a diagram showing a change in current value during operation of the solenoid valve, and FIG. The figure which shows the change of a differential value.

FIG. 4 is a diagram showing a configuration of a main part of a current detection circuit according to a second embodiment of the present invention.

5A is a diagram showing a change in a current value when an electromagnetic valve is operated in a second embodiment of the present invention, and FIG. 5B is a diagram showing a change in a time differential value of an output of a current detection circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 solenoid valve 2 switch circuit 3 control circuit 4 memory means 5 current detection circuit 6 current transformer 7 MOS transistor 9 amplifier 10 CPU 12 drive circuit 13 engine 14 rotation sensor 15 A / D converter 16 battery 18 voltage detector

Claims (4)

[Claims] 1. A switch circuit for opening and closing a drive current of an electromagnetic valve, and a control circuit for controlling the switch circuit according to a set procedure according to a control input, wherein the control circuit stores the procedure. In the control device for an electromagnetic valve including: information on an operation delay time unique to the electromagnetic valve is stored in the memory means, and a current detection circuit that detects the drive current and provides the control current to the control circuit is provided; A control unit for updating the operation delay time information stored in the memory means according to a change in the drive current detected by the current detection circuit. 2. The solenoid valve control device according to claim 1, wherein said control circuit includes means for differentiating the output of said current detection circuit with time. 3. The information of the operation delay time is such that the output of the time differentiating means is given n times (n is 1) after a control output for turning on the switch circuit is given to the switch circuit.
3. The control device for a solenoid valve according to claim 2, wherein the control information is information indicating a time until the value becomes zero. 4. The solenoid valve control device according to claim 2, wherein the current detection circuit includes a current transformer inserted in a path of the drive current.