JPH0245068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solenoid valve operating state determination device that accurately determines the operating state of a solenoid valve, such as a fuel injection valve used in an electronic fuel injection device. It is something.

[Prior art] Solenoid valves for internal combustion engines, such as fuel injection valves, are required to operate reliably under any operating conditions. In this case, the internal combustion engine cannot be operated stably. Therefore,
It is necessary to monitor the operating state of this type of solenoid valve, and conventionally the operating state of the solenoid valve has been determined as follows.

A solenoid valve, such as a fuel injection valve, has an excitation coil wound around it and a plunger slidably disposed inside the coil core.By passing current through the excitation coil, the plunger is moved to open the valve, and the fuel is internally combusted. It supplies each cylinder of the engine. Conventionally, therefore, the operating state of the solenoid valve has been determined using the change in self-inductance when the plunger moves and stops (see Japanese Patent Application Laid-Open No. 1983-43230).

FIG. 1 shows how the current flowing through the excitation coil of the solenoid valve changes over time, and at time T ₀ a driving voltage is applied to the excitation coil in order to start moving the plunger. Since the force generated is proportional to the current flowing through the coil, when this force exceeds the force of a return spring (not shown), the plunger begins to move. That is, it starts moving from a certain point after time T ₀ (a point before point TE). Here, before and during movement of the plunger, the current flowing through the coil increases at a positive rate of change. However, the plunger moves against the return spring to its maximum movable position, and at the time TE
When the coil stops at , the rate of change of current changes in the negative direction due to the influence of the coil's self-inductance, and as shown in FIG. 1, the current flowing through the coil decreases. After the plunger stops, the influence of self-inductance gradually disappears, so the current increases slightly, and from then on, the current flowing through the coil remains at a constant value.

Therefore, conventionally, it has been determined whether the plunger is operating (moving) by detecting the presence or absence of a point where the rate of change of the excitation current changes in the negative direction.

In such conventional solenoid valve operating state determination devices, it was determined whether or not the plunger was operating as described above. Therefore, based on the presence or absence of the above change, it is difficult to determine how far the plunger has moved and how much fuel has been consumed. It was not possible to determine whether the current was flowing through the solenoid valve. Furthermore, it was not possible to determine whether the plunger had completely returned to its original state due to dust or the like.

Therefore, there is a known device for detecting the opening/closing timing of a solenoid valve, as described in Japanese Utility Model Application Publication No. 78873/1983.

In this example, a pin is directly connected to the movable iron core, and when the pin pushes up a lever or moves away from the lever, a micro switch is turned on and off, thereby providing a transmission means for detecting the opening/closing timing of the solenoid valve.

[Problems to be Solved by the Invention] However, if a mechanical transmission means is used to determine the operating state of the solenoid valve based on the actual moving position of the plunger, the timing of opening and closing of the fluid passage on-off valve and Due to design errors in the timing of movement into and out of the magnetic circuit, delays due to movement, etc., errors occur in detecting the opening/closing timing and responsiveness in detecting the opening/closing timing deteriorates. Therefore, it is not possible to accurately detect the valve opening time, and especially when a solenoid valve operates at high speed like a fuel injection valve in an internal combustion engine, the opening/closing timing cannot be detected due to the aforementioned delay, making accurate detection difficult. . Therefore, there is a drawback that it is difficult to accurately determine the operating state of the fuel injection valve that supplies fuel accurately and at high speed.

In view of the above-mentioned conventional drawbacks, an object of the present invention is to
An object of the present invention is to provide an electromagnetic valve operating state determination device that can accurately determine the operating state of a fuel injection valve that supplies fuel accurately and at high speed.

[Means for Solving the Problems] In order to achieve the above object, the present invention moves a plunger by exciting an excitation coil by a valve drive signal that controls the fuel injection amount of a fuel injection valve, and also moves the plunger by exciting an excitation coil by a valve drive signal that controls the fuel injection amount of a fuel injection valve. A solenoid valve that is demagnetized and returns the plunger to its original position by a spring to open and close the valve, a vibration sensor attached to the solenoid valve, and a signal from the vibration sensor are input, and A filter means that extracts a high frequency component caused by vibration caused by the movement of the plunger and outputs a signal, and an opening/closing timing detection means that detects the timing from when the fuel injection valve opens to when it closes based on the output signal of the filter means. The present invention is characterized in that the operating state of the electromagnetic valve is determined by comparing the output signal from the opening/closing timing detection means and the valve drive signal.

[Function] Therefore, in the electromagnetic valve operating state determination device configured as described above, the vibration generated by the movement of the plunger during the excitation and demagnetization of the excitation coil is detected by the vibration sensor, and the high frequency component of the vibration is detected by the filter means. is extracted, so it is possible to know from when to when the solenoid valve was activated and its operating state from the signal indicating the time from valve opening to valve closing detected by the opening/closing timing detection means based on these high frequency components. .

[Example] Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 2 shows an example of the configuration of a solenoid valve according to the present invention, where 1 is a solenoid valve as a fuel injection valve, 2 is a fuel pipe that supplies fuel to the solenoid valve 1, and 3 is a fuel injection port. , the solenoid valve 1 is opened at a desired timing to inject fuel from the injection port 3. 4 is a vibration sensor for determining the operating state of the solenoid valve 1. The output signal of the vibration sensor 4 is processed by a signal processing circuit shown in FIG. 3 to determine the operating state of the solenoid valve 1.

Based on FIGS. 3 and 4, the vibration sensor 4
The procedure for processing the output signal will be explained.

Figure 4A shows the valve drive signal 11 supplied to the solenoid valve 1.
The waveform of is shown. Now, such a valve drive signal 11
is supplied to the solenoid valve 1, a plunger (not shown) is driven by excitation due to the rise of the signal, and the plunger, which has started moving, moves to the limit position where it can move against the force of a return spring (not shown). When the vibration sensor 4 moves up to and stops, the vibration sensor 4 outputs a waveform signal 41 as shown in FIG. 4B. This vibration waveform 41 is caused by the vibration that occurs due to a collision when the plunger stops, that is, when the solenoid valve opens. (It can be considered that the timing coincides with that.) The solenoid valve 1 is now in an open state, and fuel is injected from the injection port 3. Next, when the valve drive signal 11 is lowered, the plunger returns to its original position by the return spring and stops. At this time, the vibration sensor 4 outputs a vibration waveform 42 as shown in FIG. 4B. This vibration waveform 42 is caused by vibrations generated by a collision when the plunger stops, that is, when the solenoid valve finishes closing. At this time, the electromagnetic valve 1 is in a closed state, so fuel is cut off.

Therefore, these output signals 41 and 42 are supplied to an amplifier 22 via an input terminal 21 of a signal processing circuit shown in FIG. Further, a high-pass filter 23 extracts only the high frequency signal and outputs signals 51 and 52 shown in FIG. 4C. That is, the signal 51 is the vibration that occurs when the plunger stops at the limit of its movable range, and the signal 52 is the vibration that occurs when the plunger moves from the limit position to the original position due to the force of the return spring and stops. It is. These signals 51 and 52 are supplied to the first comparison circuit 24, and compared with the signal 50 at the level shown by the dashed line in FIG. 4C, the signal 61 shown in FIG. 4D is obtained.
and 62 are output. These signals 61 and 62 are connected to a rapid charging/slow discharging circuit (hereinafter referred to as a charging/discharging circuit).
25. When the signals 61 and 62 are at the "1" level, the capacitor 26 of the charging/discharging circuit 25
is rapidly charged through the diode 27 and becomes “0”
At the level, the capacitor 26 is connected via the resistor 28.
The charge is discharged in a time that is slow compared to the charging time. Therefore, the signal 7 shown in FIG.
1 and 72 are obtained. Next, the signals 71 and 72 are supplied to the second comparison circuit 29, where they are compared with the signal 70 at the level shown in FIG. 4E, subjected to waveform shaping, and square wave signals 81 and 82 shown in FIG. 4F are output. . That is, the signal 81 that is generated first allows us to know when the solenoid valve is open (when it has finished opening), and the signal 82 that immediately follows can tell us when the solenoid valve is closed (when it has finished closing). ) can be known.

Then, the output signal of the second comparison circuit 29 (signal shown in FIG. 4F) is supplied to AND gates 30 and 31, respectively. The valve drive signal 11 is directly supplied from the terminal 32 to the AND gate 30, and the inverter 3
The inverted signal is supplied to the AND gate 31 via the gate 3. Therefore, when the signal 81 occurs while the valve drive signal 11 is occurring, the AND output 9 corresponding to the pulse width of the signal 81 is generated as shown in FIG. 4G.
1 is obtained, and when the signal 82 occurs while the valve drive signal 11 is not occurring, as shown in FIG. 4H, the AND output 9 corresponding to the pulse width of the signal 82 is generated.
2 is obtained. Each AND output is applied to the flip-flop 34 such that the AND output 91 is applied to the set terminal S of the flip-flop 34 to set the flip-flop 34, and the AND output 92 is applied to the reset terminal R of the flip-flop 34 to reset the flip-flop 34. , Figure 4 I
As shown in FIG. 3, the flip-flop 34 outputs a signal 100 at the "1" level only from the time when the AND output 91 rises until the time when the AND output 92 rises. This signal 100 is taken out from the output terminal 35, and for example, the signal 100 is supplied to a pulse width counter (not shown) that displays the pulse width of the signal 100 as a digital value. Read the time from when 1 finishes opening until it finishes closing. This makes it possible to detect the amount of fuel supplied to the engine from the solenoid valve 1, and detect variations in each cylinder of the engine by determining the operating state of each fuel injection valve 1 attached to each cylinder of the engine. can do. In other words, if each cylinder of the engine operates unevenly, engine operation becomes unstable and problems such as emission failure (emissions of hydrocarbons such as HC contained in exhaust gas exceed the standard value) occur. Such a state can be determined simply by monitoring the operating state of the injection valve 1.

Furthermore, by detecting the time from the rise of the valve drive signal 11 to the rise of the detection signal 100, or the time from the fall of the valve drive signal 11 to the fall of the detection signal 100, it is possible to determine whether the solenoid valve 1 is completely open. , or it is possible to judge whether the solenoid valve 1 is completely closed.
malfunction can be determined.

[Effects of the Invention] As described above, according to the present invention, vibrations generated when a solenoid valve operates, that is, vibrations generated based on valve opening and closing operations by a plunger, are detected by a vibration sensor. After detecting the vibration, high frequency components are extracted from the vibration by a filter means, and based on these, the timing from the valve opening to the valve closing is detected by the opening/closing timing detection means, and these are compared with the valve drive signal. Since the operating state of the electromagnetic valve is determined, it is possible to accurately and easily determine the operating state of the fuel injection valve that supplies fuel at high speed.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing changes in excitation current in a conventional electromagnetic valve operating state determination device, Fig. 2 is a diagram showing an example of the configuration of the electromagnetic valve according to the present invention, and Fig. 3 is a diagram showing a signal processing circuit according to the present invention. FIG. 4 is a block diagram showing an example, and a timing chart showing waveforms of each part thereof. 1... Solenoid valve, 2... Fuel pipe, 3... Fuel injection port, 4... Vibration sensor, 11, 41, 42,
51, 52, 61, 62, 71, 72, 81, 8
2,91,92,100...signal, 21,32,
35... terminal, 22... amplifier, 23... filter, 24, 29... comparison circuit, 25... charging/discharging circuit, 26... capacitor, 27... diode,
28...Resistance, 30, 31...And gate, 3
3...Inverter, 34...Flip-flop.

Claims (1)

[Claims] 1. An excitation coil is excited by a valve drive signal that controls the fuel injection amount of the fuel injection valve to move the plunger, and the excitation coil is demagnetized and the plunger is returned to its original position by a spring. a solenoid valve that opens and closes the valve with a vibration; a vibration sensor attached to the solenoid valve; and a signal from the vibration sensor is inputted to detect the vibration caused by the movement of the plunger accompanying the excitation and demagnetization. a filter means for extracting a high frequency component and outputting a signal; and an opening/closing timing detection means for detecting the timing from when the fuel injection valve is opened to when it is closed based on the output signal of the filter means, A solenoid valve operating state determining device, characterized in that the operating state of the solenoid valve is determined by comparing an output signal from the opening/closing timing detection means with the valve drive signal.