JP2001280189A - Control method for electromagnetic fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the injection amount in initial setting by detecting a change in delay of an opening and closing valve of a fuel injection valve using gas fuel or corrosive fuel and correcting fuel pulse length. SOLUTION: A displacement point of an opening and closing valve is detected from a change in current flowing to a coil, the fluctuation of the delay time of the opening and closing valve is detected on the basis of the information, and fuel pulse length is corrected by the fluctuation. Therefore, the stable injection amount not to be easily affected by a secular change in the injection valve can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an electromagnetic fuel injection valve of an internal combustion engine. Regarding the control method of the electromagnetic fuel injection valve that shuts off the flow and opens and closes the electromagnetic valve, the fuel may be not only gasoline but also CNG gas.

[0002]

2. Description of the Related Art A conventional method of controlling an electromagnetic fuel injection valve is as follows.
For example, as described in Japanese Patent Application Laid-Open No. Hei 8-261051, first, a fuel injection pulse width for supplying fuel required for driving the engine is calculated from an engine speed, an operating state, and the like, and the fuel injection pulse width is calculated. A pulse control signal corresponding to the fuel injection pulse width is applied to a semiconductor switching element that controls interruption of energization of a driving coil of a solenoid valve that forms the valve.

At the start of energization, that is, when the valve is opened, the current flowing through the coil rises with a time constant consisting of the resistance and inductance of the drive coil of the solenoid valve. By shortening the coil, the inductance is removed, the current can be cut off in a short time, and the time required for closing the injection valve is shortened.

[0004]

When, for example, CNG gas (liquefied natural gas) or a fuel containing corrosive components is used as the fuel, lubricating properties such as gasoline cannot be expected, so that the fuel in the injection valve is not provided. There is a problem in that friction occurs in the movable part, and corrosion occurs in each part due to corrosive components, so that the operation of the on-off valve of the movable valve changes over time and the injection amount characteristic changes.

[0005] Although a certain degree of change can be covered by control such as O ₂ feedback, if the amount of change in the injection amount characteristic is large, the change cannot be fully covered, causing problems such as poor operability and engine stall.

An object of the present invention is to maintain the injection amount at the time of initial setting even if the state of the injection valve changes over time.

[0007]

In order to achieve the above object, the present invention detects a displacement point generated in a current flowing through a coil at a fully open point or a fully closed point of an electromagnetic valve, and detects the displacement point and the displacement of the coil. The opening and closing delay times are detected from the relationship between the rising timing and the falling timing of the pulse-like control signal applied to the semiconductor switching element for controlling the conduction and interruption of the current, and based on this, the delay time becomes the same as the initial delay time. Thus, the width of the pulse-like control signal applied to the semiconductor switching element is controlled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 is a control system diagram of an engine using CNG gas as fuel.

The CNG gas is stored in a gas cylinder 100, a shutoff valve 101 for shutting off a passage in an emergency, and a pressure regulator for controlling the gas pressure within a predetermined value.
102, an electromagnetic fuel injection valve 10 composed of an electromagnetic valve.
4 is supplied. (The specific configuration of the electromagnetic fuel injection valve 104 will be described later in detail with reference to FIG. 2.) On the other hand, the air taken in from the air cleaner 110 is mechanically or electrically controlled by the amount of depression of the accelerator. The amount is adjusted by the opening of the throttle valve 111.

A throttle body provided with a throttle valve 111 is attached to an inlet of a surge tank 112. The surge tank 112 has the other ends of a plurality of independent branch pipes 113 connected to one end of each cylinder 120 of the engine E. Is connected.

In this embodiment, the electromagnetic fuel injection valve 104 is attached to one end of each of the independent intake pipes 113, and is opened and closed by an intake valve 121 of the engine E.
The CNG gas is injected toward the intake port of.

The intake valve 121 and the exhaust valve 122 of the engine E
Sucks a mixture of air and fuel into the cylinder 120 in synchronization with a fuel cycle of intake, compression, explosion, and exhaust of the engine, and exhausts the burned exhaust gas to an exhaust pipe 123.

The ignition plug 124 ignites a mixture of air and fuel sucked into the cylinder 120 at a predetermined timing, and burns the mixture in the cylinder 120.

The power distributor 126 has an ignition coil. The battery voltage is boosted by the coil to generate a high ignition voltage, and the high voltage for ignition is distributed to the ignition plug 124 attached to each cylinder.

The EGR valve 127 recirculates a part of the exhaust gas to the intake passage.
In this embodiment, the exhaust gas recirculation passage 128 extends from the downstream side of the collecting portion 125 where the
Is installed on the way.

The idle air control valve 129 is provided in a passage 130 bypassing the throttle valve 111 in an intake passage portion where the throttle valve 111 is provided, and the engine rotation in an idle state in which the throttle valve 111 is closed. The amount of air is controlled to maintain the number.

The catalysts 140 and 141 are for removing harmful components in the exhaust gas.

The control unit 200 receives signals from various sensors and controls control signals or power supply to various control devices.

The air flow sensor 131 is provided in an intake pipe between the air cleaner 110 and the throttle valve 111, detects an actual amount of air adjusted by the throttle valve 112, and sends the detected air to the control unit 200.

A throttle positioning sensor (throttle opening sensor) 132 includes an accelerator wire (not shown),
Alternatively, the actual opening of the throttle valve 111 operated by an electric actuator such as a motor is detected and sent to the control unit 200.

The engine cooling water temperature sensor 133 is attached to the water jacket of the engine, detects the temperature of the cooling water of the engine, and sends it to the control unit 200.

The engine combustion temperature sensor 134 is attached to the engine body, detects the temperature of the engine, and sends it to the control unit 200.

The fuel temperature sensor 135 is attached to a fuel supply pipe between the pressure regulator 102 and the fuel injection valve 104, detects the temperature of the fuel supplied to the fuel injection valve, and sends it to the control unit 200.

The fuel pressure sensor 136 is attached to a fuel supply pipe between the pressure regulator 102 and the fuel injection valve 104, and controls the fuel pressure adjusted by the pressure regulator 102, that is, the pressure of the fuel acting on the fuel injection valve. Is detected and sent to the control unit 200.

The oxygen concentration sensors 137 and 138 are provided downstream of the collecting portion 125 of the exhaust pipe 123 of each cylinder,
Are attached to the exhaust pipes before and after the catalyst 140 to detect the oxygen concentration in the exhaust gas before and after the catalyst 140 and send it to the control unit 200.

The crank angle sensor 139 is composed of a magnetic pickup and detects the rotation angle of the crankshaft of the engine and sends it to the control unit 200.

Although not shown, the throttle valve 111
Is driven by a motor, an accelerator sensor for detecting the amount of depression of the accelerator is provided and sent to the control unit 200.

The control unit 200 determines the required torque of the engine based on the signals of the air flow sensor 131 and the crank angle sensor 139, determines the amount of fuel required to obtain the torque, and supplies the required amount of fuel. The valve opening time of the appropriate fuel injection valve 104 is calculated. Since the valve opening time varies depending on the temperature and pressure of the fuel, the valve opening time is corrected based on signals from the fuel temperature sensor 135 and the fuel pressure sensor 136.

On the other hand, the fuel injection timing is obtained based on the signal of the crank angle sensor 139.

At the injection timing thus obtained, the control unit 200 electrically connects the fuel injection valve 104 and the battery VB via the wiring 104a to the fuel injection valve 104 and the battery VB via the driver circuit (not shown) during the valve opening time. The driving power for valve opening is supplied to the valve 104.

FIG. 2 is a sectional view of the fuel injection valve 104.

A cylindrical excitation coil 9 is provided at the central cylindrical portion of the core 1.
These are housed inside a bottomed cup-shaped yoke 2, and are combined with each other in such a state that the flange portion of the core 1 covers the opening of the bottomed cup-shaped yoke 2.

The bottom of the cup-shaped yoke 2 has a through hole through which the movable valve element is inserted.

The movable valve element comprises a plunger 3, a ball valve 4, and a guide ring 13 made of a non-magnetic material.

A through hole is formed in the center of the core 1, and a spring 7 and a spring adjuster 8 for adjusting the spring force are provided in this hole. Further, a cylindrical guide ring 13 of a movable valve body is provided in this hole. To guide the axial movement of the movable valve element.

The spring 7 whose one end contacts the spring adjuster 8 passes through the cylindrical guide ring 13 and the other end contacts the end face of the plunger 3, whereby the spring 7 between the spring adjuster 8 and the plunger 3 is moved. The set load of the spring 7 is configured to be adjustable by a spring adjuster 8.

A stopper 17 is mounted at an intermediate position between the plunger 3 and the ball valve 4 of the movable valve body. The stopper 17 is inserted into a cylindrical portion formed at the tip of the yoke, and the tip cylindrical portion of the yoke 2 is inserted. The nozzle 5 is held between one end of the nozzle 5 and the shoulder of the yoke 2.

The nozzle 5 is formed with a seat (valve seat) portion 6 with which the ball valve 4 of the movable valve body contacts, and a fuel injection hole 16 formed at the center thereof.

Further, the nozzle 5 has a through hole for guiding the ball valve 4 of the movable valve body and the fuel passage 1 for giving a swirling force to the fuel.
The guide member 15 provided with the seats (valve seats) 6
Is fixed on the upstream side.

Thus, a magnetic circuit is formed by the core 1 and the yoke 2 as the fixed iron core and the plunger 3 as the movable iron core.
The ball valve 4 is pressed toward the seat portion 6 of the ball.

Connector 10 for transmitting to coil 9, coil 9
And a coil assembly composed of a bobbin 11 holding the coil 9 and an outer mold 12 wrapping the coil 9. Below the yoke 2, a plunger 3, a ball valve 4 and a ring 13 are provided.
A nozzle 5 having an injection hole 16 for injecting fuel is provided by guiding a ball valve 4 of a valve element formed of a fuel cell and connecting a guide member 15 having a fuel groove 14 for supplying fuel to the seat portion 6. There is a stopper 17 between the nozzle 5 and the yoke 2 for determining the stroke of the valve element.

Under the above configuration, when the coil 9 is energized, the core 1, the yoke 2, and the plunger 3 are excited, and the plunger 3 is attracted to the core 1 against the force of the spring 7. The plunger 3 is integrally connected with the ball valve 4 and the ring 13. The movement of the plunger 3 causes the ball valve to move, and separates from the seat portion 6 of the nozzle 5 to open. Here, the plunger 3 has its shoulder 18
Moves until it hits the stopper 17, and the plunger 3 and the core 1 do not come into direct contact. Fuel is supplied from the outer periphery of the filter 19, passes through the fuel hole 20 of the yoke 2,
And the coil assembly and between the yoke 2 and the plunger 3 to the nozzle 5.

Further, the fuel passes through the vertical groove 21 formed between the outer peripheral surface of the guide member 15 and the peripheral surface without the nozzle 5, and passes through the radial fuel groove 14 provided on the lower end surface of the guide member 15. The sheet is supplied to the sheet unit 6.

When the coil 9 is energized and attracted by the plunger 3 and the core 1, the movable valve 4 separates from the seat portion 6, and
Fuel gas is injected through an injection hole 16 provided at the center of the tip of the nozzle 5.

FIG. 3 is a diagram showing a drive pulse applied to the injection valve, a drive current flowing through the coil, and a temporal change in lift of the movable valve.

As shown in this figure, the drive current rises with a rise characteristic consisting of the resistance and inductance of the coil, and falls to a saturation current value determined by the relationship between the applied voltage and the supply current.

The drive circuit is configured so that the current immediately falls when the applied pulse is cut.

Looking at the current change (change from the beginning of the flow until the saturation current is reached) when the injection valve is opened, it can be seen that immediately after the shoulder 18 of the plunger 3 collides with the stopper 17, It has been found that the inductance changes differently from the previous change, and as a result, the displacement of the current changes.

Then, when this change in the drive current was differentiated, it was found that an inflection point appeared in the differential value at the current displacement point.

Therefore, the valve opening delay Ta can be detected by calculating the time difference between the displacement point and the rising point of the drive pulse.

On the other hand, when looking at the current change (change from the falling point of the current to the time when the current reaches zero) at the time of closing the valve, immediately after the movable valve body 4 collides with the valve seat 6, the magnetic path It has been found that the inductance inside changes differently from the previous change, and as a result, the displacement of the current changes.

Then, when the change in the drive current was differentiated, it was found that an inflection point appeared in the differential value at the current displacement point.

Therefore, the valve closing delay Tb can be detected by calculating the time difference between the displacement point and the falling point of the drive pulse.

The valve opening delay Ta and valve closing delay T thus determined
b is compared with the initial valve opening delay Ta and the valve closing delay Tb to detect the changes ΔTa and ΔTb, and to correct and control the drive pulse Tp based on ΔTa and ΔTb. The fluctuation of the fuel injection amount due to the above can be suppressed, and an appropriate amount of fuel can always be supplied.

Here, the valve opening delay Ta is determined by the force obtained by subtracting the spring force from the suction force, but the valve closing delay Tb is determined only by the spring force. The effect of the change of the injection valve, that is, the deterioration of the injection valve over time or the abnormality, is caused by the valve closing delay T
b clearly appears.

As described above, since the rate at which the injection amount fluctuates due to the change in the valve closing delay Tb is larger, a sufficient effect can be recognized only by the correction based on the change in the valve closing delay Tb. A more accurate correction can be made by adding the correction based on the change.

A specific circuit and a flowchart of the operation will be described below in detail with reference to FIGS. 6, 7A and 7B.

The coils 9 of the injection valves corresponding to the respective cylinders are connected to a power supply circuit 60.

The power supply circuit 60 basically includes a vehicle-mounted battery (12 V, 24 V or 42 V), a noise removal circuit,
It is configured to include a constant voltage circuit.

When the injection valve is configured to inject fuel directly into the cylinder, a large valve opening force is required. In this case, the injection valve is configured to include a booster circuit.

As shown in FIG. 4, when a reverse voltage is applied when the valve is closed, the control circuit is included.

A power supply side terminal of a field effect transistor (FET) 61 is connected to each coil 9 in series.

Further, a field effect transistor (FET) 6
A current detection resistor 62 is connected in series to one of the arc-side terminals, and is connected to the ground via this resistor.

A detection terminal of a current detection circuit 63 is connected to a connection between the current detection resistor 62 and the FET 61.

The current detection circuit 63 detects the current I flowing through the coil.
A detects the voltage generated at the terminal of the current detection resistor 62 and sends it to the engine control unit ECU.

The microcomputer constituting the ECU executes the current detection circuit 6 based on a subroutine periodically executed by a timer interrupt shown in FIG.
Read the output of # 3.

The microcomputer differentiates the read output of the current detection circuit 63 and calculates the current IA from the result.
The current displacement point when the valve is opened or closed is detected.

The rising and falling delay time data is calculated from the displacement point data and the rising point data and falling point data of the fuel injection pulse TP obtained in the main routine.

In the main routine, the detection data of the engine speed and the intake air amount are read, and the basic fuel injection pulse width TP is calculated.

Next, the basic injection pulse width TP is corrected according to the separately obtained rise and fall delay time changes, and the coil 9 is energized by the corrected injection pulse. Thus, even if the rise and fall delay times change, the same amount of fuel as in the initial state (for the same valve opening pulse width)
Is obtained.

FIG. 4 shows the detection of a displacement point in a case where a current is caused to flow in the reverse direction after the end of the application pulse to prevent the movable valve from colliding with and rebounding from the valve seat. In this configuration, the generation of eddy current due to the reverse current is small, and the effect of speeding up the valve closing can be obtained.

FIG. 5 shows a state in which a small current of a level at which the movable valve is not re-attracted after the application pulse is applied, and a displacement point generated there is detected.

The same effects as in FIG. 3 can be obtained by the displacement point detecting methods shown in FIGS.

[0075]

According to the present invention, even if the movement of the movable valve changes over time due to wear and corrosion and the delay time of the on-off valve changes,
Since this can be detected and the pulse width can be corrected, the secular change of the fuel injection amount can be reduced, and there is an effect that malfunction such as poor driving performance and engine stall hardly occurs.

[Brief description of the drawings]

FIG. 1 is a system diagram of a CNG injection system in which the present invention is implemented.

FIG. 2 is a sectional view showing an example of a fuel injection valve to which the present invention is applied.

FIG. 3 is a time chart showing changes in a drive pulse applied to a coil of an injection valve, a drive current flowing through the coil, and a stroke of a movable portion of the injection valve.

FIG. 4 is a time chart showing changes in a drive pulse applied to a coil of another example of the injection valve, a drive current flowing through the coil, and a stroke of a movable portion of the injection valve in a different example of a method of interrupting the coil current.

FIG. 5 is a time chart showing a drive pulse applied to a coil of a further example of the injection valve, a drive current flowing through the coil, and a change in a stroke of a movable portion of the injection valve, in which the method of interrupting the coil is different.

FIG. 6 is a circuit diagram showing an example of a drive control circuit of the injection valve.

FIG. 7A shows a main routine of fuel injection valve control;
(B) shows a subroutine for current detection.

[Explanation of symbols]

1 ... fixed iron core (core), 2 ... outer peripheral case (yoke), 3
... Plunger, 4 ... Ball valve, 5 ... Nozzle, 6 ... Seat part, 7 ... Spring, 8 ... Spring adjuster, 9 ...
Coil, 10 connector, 11 bobbin, 12 outer mold, 13 ring, 14 fuel groove, 15 guide member, 16 injection hole, 17 stopper, 18 shoulder part, 19 filter, 20 fuel hole.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shuichi Shimizu 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Car Engineering Co., Ltd. (72) Takashi Hasunuma 2477 Takaba Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Corporation F term (reference) 3G066 AA02 AB02 AD10 AD12 BA43 CC01 CC15 CE24 CE29 CE34 DA01 DA04 DC04 DC09 DC14 DC15 DC18 3G301 HA01 HA22 JA14 JA15 LA03 LB02 LB04 LC01 LC10 MA12 MA18 NA05 PA01Z PA11Z PB01Z PB08Z PC05Z PD02Z DA02Z DB02 DB12 DB23 DB32 DC04 DD03 EE01 EE27 EE48 FA04 FB08 FB24 KK18

Claims (5)

[Claims] 1. A solenoid valve which opens and closes an electromagnetic valve by interrupting a current flowing through a coil by a semiconductor switching element which conducts and shuts off by applying a pulse-like control signal. A control signal to be applied to the semiconductor switching element based on a relationship between any one of the displacement points of the drive current and a rising point or a falling point of the pulse-like control signal. A method for controlling an electromagnetic fuel injection valve for controlling a pulse width of a fuel injection valve. 2. A fully open point or a fully closed point of a valve is detected from a displacement point of a drive current appearing at a fully open position and a fully closed position of the valve, and either of the fully open point or the fully closed point of the valve and the pulse-like control are detected. At least one of a valve opening and valve closing delay time is detected from a relationship with either a rising point or a falling point of the signal, and a control signal applied to the semiconductor switching element based on the opening and closing delay time is detected. 2. The control method according to claim 1, wherein the pulse width is controlled. 3. A control method for an electromagnetic injection valve according to claim 1, wherein the detection of the delay time of opening or closing the valve is performed in a specific one cylinder of the engine. 4. A control method for an electromagnetic fuel injection valve according to claim 1, wherein the delay time of opening or closing the valve is detected in all cylinders of the engine. 5. The electromagnetic fuel according to claim 1, wherein the control of the drive pulse width of the valve based on the delay time of opening or closing the valve is performed in a specific cylinder of the engine. Control method of injection valve.