JP2021101104A - Fuel injection control device - Google Patents

Abstract

To provide a fuel injection control device which can stabilize motion of a movable element and a valve body.SOLUTION: A fuel injection control device of the invention controls a fuel injection amount of a fuel injection device including: a valve body which separates from a valve seat to open a fuel passage; a movable element which causes the valve body to open or close; and a fixed element which suctions the movable element by an electric current flowing through a coil. The fuel injection control device includes: a valve opening timing detection part which detects valve opening completion timing (T32) at which the movable element collides with the fixed element; and a control unit which performs controlling so that a reverse voltage is applied to interrupt a driving current before the valve opening completion timing (T32) and a voltage is applied so that a hold current (331), being a driving current for maintaining a state that the valve body is open, flows after the valve opening completion timing.SELECTED DRAWING: Figure 4

Description

The present invention relates to a fuel injection control device that controls a fuel injection amount of the fuel injection device.

In recent years, a downsizing engine has been known in which the displacement is reduced to reduce the size and the output is obtained by a supercharger. Since the downsizing engine can reduce the pumping loss by reducing the displacement, it is possible to improve the fuel efficiency.

On the other hand, in a downsizing engine, since the cylinder diameter in the engine cylinder tends to be reduced, there is a concern that the injected fuel adheres to the cylinder wall surface and deteriorates the exhaust performance. Further, in a downsizing engine, when a non-uniform portion of fuel flow and air is generated, unburned particulate matter is discharged, and the exhaust performance is deteriorated. Therefore, in a downsizing engine, the pressure of the fuel supplied into the engine cylinder is increased, the injected fuel is atomized, and a uniform air-fuel mixture is formed, so that the air and fuel in the engine cylinder are homogenized. It is planned.

As a fuel injection device for improving the pressure of fuel supplied into the engine cylinder, for example, Patent Document 1 is described. The fuel injection device described in Patent Document 1 operates only the movable iron core before the start of energization by providing a gap in the displacement direction between the movable iron core and the valve body. As a result, the movable iron core can be run up, and the kinetic energy is used to increase the fuel pressure.

Japanese Unexamined Patent Publication No. 2002-115591

However, in the fuel injection device described in Patent Document 1, when the fuel injection device is driven at a low fuel pressure, the kinetic energy obtained by running the movable iron core works excessively, and the valve body and the movable iron core behave in an unstable manner. , The injection amount to be injected may not be stable.

An object of the present invention is to provide a fuel injection control device capable of stabilizing the movements of a mover and a valve body in consideration of the above problems.

In order to solve the above problems and achieve the object of the present invention, the fuel injection control device of the present invention includes a valve body that opens a fuel passage by moving away from the valve seat, and a stator that opens and closes the valve body. It is a fuel injection control device that controls the fuel injection amount of a fuel injection device including a stator that sucks a mover by flowing a current through a coil. This fuel injection control device includes a valve opening timing detection unit and a control unit. The valve opening timing detection unit detects the valve opening completion timing when the mover collides with the stator. The control unit applies a reverse voltage before the valve opening completion timing to shut off the drive current, so that the hold current, which is the drive current for maintaining the valve body open state after the valve opening completion timing, flows. Controls the application of voltage to.

According to the fuel injection control device having the above configuration, the movements of the mover and the valve body can be stabilized.
Issues, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is an overall block diagram which shows the basic structure example of the internal combustion engine equipped with the fuel injection control device which concerns on one Embodiment of this invention. It is sectional drawing which shows the fuel injection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the detail of the drive circuit and the engine control unit (ECU) of the fuel injection control device which concerns on one Embodiment of this invention. It is a figure which shows the drive command pulse (injection pulse), the drive voltage, the drive current, the displacement of a valve body, and the displacement of a movable iron core about the fuel injection device shown in FIG. It is a figure explaining the relationship between the injection amount of a fuel injection device, and a drive command pulse.

Hereinafter, the fuel injection control device according to the embodiment of the present invention will be described. The common members in each figure are designated by the same reference numerals.

[Internal combustion engine system]
First, the configuration of the internal combustion engine system equipped with the fuel injection control device according to the present embodiment will be described. FIG. 1 is an overall configuration diagram of an internal combustion engine system equipped with a fuel injection control device according to the present embodiment.

The internal combustion engine (engine) 101 shown in FIG. 1 is a four-cycle engine that repeats four strokes of a suction stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. For example, a multi-cylinder engine having four cylinders. It is an engine. The number of cylinders of the internal combustion engine 101 is not limited to four, and may have six or eight or more cylinders.

The internal combustion engine 101 includes a piston 102, an intake valve 103, and an exhaust valve 104. The intake air (intake air) to the internal combustion engine 101 passes through an air flow meter (AFM) 120 that detects the amount of inflowing air, and the flow rate is adjusted by the throttle valve 119. The air that has passed through the throttle valve 119 is sucked into the collector 115 which is a branch portion, and then enters the combustion chamber 121 of each cylinder via the intake pipe 110 and the intake valve 103 provided for each cylinder (cylinder). Be supplied.

On the other hand, the fuel is supplied from the fuel tank 123 to the high pressure fuel pump 125 by the low pressure fuel pump 124, and is increased to the pressure required for fuel injection by the high pressure fuel pump 125. That is, the high-pressure fuel pump 125 moves the plunger provided in the high-pressure fuel pump 125 up and down by the power transmitted from the exhaust cam shaft (not shown) of the exhaust cam 128, and the fuel in the high-pressure fuel pump 125. Pressurize (pressurize).

An on-off valve driven by a solenoid is provided at the suction port of the high-pressure fuel pump 125, and the solenoid is a control device 127 of a fuel injection device provided in an ECU (Engine Control Unit) 109 (hereinafter, "fuel injection"). It is connected to (referred to as "control device 127"). The fuel injection control device 127 controls the solenoid based on the control command from the ECU 109, and drives the on-off valve so that the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump 125 becomes a desired pressure.

The fuel boosted by the high-pressure fuel pump 125 is sent to the fuel injection device 200 via the high-pressure fuel pipe 129. The fuel injection device 200 injects fuel directly into the combustion chamber 121 based on the command of the fuel injection control device 127. The fuel injection device 200 operates the valve body to inject fuel by supplying (energizing) a drive current to the coil 208, which will be described later.

Further, the internal combustion engine 101 is provided with a fuel pressure sensor (fuel pressure sensor) 126 for measuring the fuel pressure in the high-pressure fuel pipe 129. Based on the measurement result by the fuel pressure sensor 126, the ECU 109 sends a control command for setting the fuel pressure in the high-pressure fuel pipe 129 to a desired pressure to the fuel injection control device 127. That is, the ECU 109 performs so-called feedback control to set the fuel pressure in the high-pressure fuel pipe 129 to a desired pressure.

Further, each combustion chamber 121 of the internal combustion engine 101 is provided with a spark plug 106, an ignition coil 107, and a water temperature sensor 108. The spark plug 106 exposes the electrode portion in the combustion chamber 121, and ignites the air-fuel mixture in which the intake air and the fuel are mixed in the combustion chamber 121 by electric discharge. The ignition coil 107 creates a high voltage for discharging at the spark plug 106. The water temperature sensor 108 measures the temperature of the cooling water that cools the cylinder of the internal combustion engine 101.

The ECU 109 controls the energization of the ignition coil 107 and the ignition by the spark plug 106. The air-fuel mixture in which the intake air and the fuel are mixed in the combustion chamber 121 is burned by sparks emitted from the spark plug 106, and the pressure pushes down the piston 102.

The exhaust gas generated by combustion is discharged to the exhaust pipe 111 via the exhaust valve 104. The exhaust pipe 111 is provided with a three-way catalyst 112 and an oxygen sensor 113. The three-way catalyst 112 purifies harmful substances such as nitrogen oxides (NOx) contained in the exhaust gas. The oxygen sensor 113 detects the oxygen concentration contained in the exhaust gas and outputs the detection result to the ECU 109. Based on the detection result of the oxygen sensor 113, the ECU 109 performs feedback control so that the fuel injection amount supplied from the fuel injection device 200 becomes the target air-fuel ratio.

Further, a crankshaft 131 is connected to the piston 102 via a connecting rod 132. Then, the reciprocating motion of the piston 102 is converted into a rotary motion by the crankshaft 131. A crank angle sensor 116 is attached to the crankshaft 131. The crank angle sensor 116 detects the rotation and phase of the crankshaft 131, and outputs the detection result to the ECU 109. The ECU 109 can detect the rotation speed of the internal combustion engine 101 based on the output of the crank angle sensor 116.

Signals such as a crank angle sensor 116, an air flow meter 120, an oxygen sensor 113, an accelerator opening sensor 122 indicating the opening degree of the accelerator operated by the driver, and a fuel pressure sensor 126 are input to the ECU 109.

The ECU 109 calculates the required torque of the internal combustion engine 101 based on the signal supplied from the accelerator opening sensor 122, and determines whether or not it is in the idle state. Further, the ECU 109 calculates the amount of intake air required for the internal combustion engine 101 from the required torque and the like, and outputs an opening signal corresponding to the amount to the throttle valve 119.

Further, the ECU 109 has a rotation speed detection unit that calculates the rotation speed (hereinafter, referred to as engine rotation speed) of the internal combustion engine 101 based on the signal supplied from the crank angle sensor 116. Further, the ECU 109 is a warm-up determination unit that determines whether or not the three-way catalyst 112 is in a warm-up state based on the temperature of the cooling water obtained from the water temperature sensor 108, the elapsed time after the start of the internal combustion engine 101, and the like. Has.

The fuel injection control device 127 calculates a fuel amount (target injection amount) according to the intake air amount, and outputs a fuel injection signal corresponding to the calculation to the fuel injection device 200. Further, the fuel injection control device 127 outputs an energization signal to the ignition coil 107 and outputs an ignition signal to the spark plug 106.

[Fuel injection device configuration]
Next, the configuration of the fuel injection device 200 shown in FIG. 1 will be described with reference to FIG.
FIG. 2 is a cross-sectional view showing the fuel injection device 200 shown in FIG.

As shown in FIG. 2, the fuel injection device 200 includes a fuel supply unit 212 for supplying fuel, a valve seat 202 having a fuel injection hole 215 as a fuel passage, and a movable iron core (movable) for driving the valve body 201. Child) 206 and. In this embodiment, an electromagnetic fuel injection device for an internal combustion engine using gasoline as a fuel will be described as an example.

In the fuel injection device 200, a fuel supply unit 212 is configured on the upper end side of the drawing, and a fuel injection hole 215 and a valve seat 202 are configured on the lower end side. A movable iron core 206 and a valve body are formed between the fuel supply unit 212 and the valve seat 202. 201, the intermediate member 214 is arranged.

The fuel injection device 200 is connected to a high-pressure fuel pipe 129 (see FIG. 1) whose end on the opposite side (fuel supply unit 212 side) to the fuel injection hole 215 and the valve seat 202 is not shown. In the fuel injection device 200, the end portion on the opposite side (fuel injection hole 215 side) to the fuel supply unit 212 is formed on a member (cylinder block, cylinder head, etc.) forming the combustion chamber 121 (see FIG. 1). It is inserted into the mounting hole (insertion hole).

The fuel injection device 200 receives fuel from the high-pressure fuel pipe 129 (see FIG. 1) through the fuel supply unit 212, and injects fuel into the combustion chamber 121 (see FIG. 1) from the tip of the valve seat 202. Inside the fuel injection device 200, a fuel passage is provided so that fuel flows substantially along the central axis 200a of the fuel injection device 200 from the base end on the fuel supply unit 212 side to the tip on the fuel injection hole 215 side. It is configured.

The coil 208 is arranged between the fixed iron core (stator) 207 and the housing 209. The fixed iron core 207, the coil 208 and the housing 209 form an electromagnet. In the valve closed state where the coil 208 is not energized, the force obtained by subtracting the urging force of the third spring member 217 from the urging force of the first spring member 210 and the second spring member 216 that urge the valve body 201 in the valve closing direction. Therefore, the valve body 201 is in contact with the valve seat 202. This state is defined as a valve closing stable state (valve closing standby state). In the valve closed stable state, the movable iron core 206 comes into contact with the intermediate member 214 and is arranged at the valve closed position. The valve body 201 is driven via a transmission surface 219 that transmits a load from the movable iron core 206.

In the valve closing stable state, the intermediate member 214 is urged to the downstream side (valve seat 202 side, valve closing direction) by the second spring member 216, comes into contact with the valve body 201, and stands still. The movable iron core 206 is urged to the upstream side (fixed iron core 207 side, valve opening direction) by the third spring member 217, and is in contact with the intermediate member 214. Since the urging force of the second spring member 216 is larger than the urging force of the third spring member 217, a gap 250 is formed between the valve body 201 and the movable iron core 206.

A fuel injection control device 127 and an ECU (engine control device) 109 are connected to the fuel injection device 200. The fuel injection control device 127 has a circuit that receives a drive command pulse (injection pulse) from the ECU 109 and energizes the fuel injection device 200 with a drive current (drive voltage). The ECU 109 and the fuel injection control device 127 may be configured as an integral part. At least the fuel injection control device 127 is a device that generates a drive voltage of the fuel injection device 200, and may be integrated with the ECU 109 or may be configured as a single unit.

The ECU 109 takes in signals indicating the state of the engine from various sensors and calculates an appropriate drive command pulse (injection pulse) width and injection timing according to the operating conditions of the internal combustion engine. The drive command pulse output from the ECU 109 is input to the fuel injection control device 127 through the signal line 223.

The fuel injection control device 127 controls the drive voltage applied to the coil 208 and supplies the drive current. The ECU 109 communicates with the fuel injection control device 127 through the communication line 222, and can switch the drive current generated by the fuel injection control device 127 according to the pressure of the fuel supplied to the fuel injection device 200 and the operating conditions. is there. The fuel injection control device 127 can change the control constant by communicating with the ECU 109, and the current waveform changes according to the control constant.

[Fuel injection control device configuration]
Next, the configuration of the fuel injection control device 127 will be described with reference to FIG.
FIG. 3 is a diagram showing details of the drive circuit of the fuel injection control device 127 and the ECU 109.

The ECU 109 (see FIG. 2) has a built-in CPU 501. The CPU 501 captures various signals indicating the state of the engine from the fuel pressure sensor 126, the air flow meter 120, the oxygen sensor 113, the crank angle sensor 116, and the like. Then, the CPU 501 calculates the drive command pulse (injection pulse) width and the injection timing for controlling the fuel injection amount to be injected from the fuel injection device 200 according to the operating conditions of the internal combustion engine in response to these signals. ..

Further, the CPU 501 calculates an appropriate drive command pulse pulse width and injection timing according to the operating conditions of the internal combustion engine, and outputs the drive command pulse to the drive IC 502 of the fuel injection device 200 through the signal line 223. The CPU 501 shows a specific example of the control unit according to the present invention. The magnitude of the injection amount is determined by the magnitude of the pulse width of the drive command pulse. After that, the drive IC 502 switches between energization and de-energization of the switching elements 505, 506, and 507 to supply a drive current to the fuel injection device 200.

The switching element 505 is connected between a high voltage source higher than the voltage source VB input to the drive circuit of the fuel injection control device 127 and a terminal on the high voltage side of the solenoid 540 of the fuel injection device 200. The switching elements 505, 506, and 507 are composed of, for example, FETs (Field effect transistors), transistors, and the like, and can switch between energization and de-energization of the fuel injection device 200.

The boost voltage VH, which is the initial voltage value of the high voltage source, is, for example, 65 V, and is generated by boosting the battery voltage by the boost circuit 514. The booster circuit 514 is composed of, for example, a coil 530, a transistor 531 and a diode 532 and a capacitor 533.

In the booster circuit 514, when the transistor 531 is turned on, the battery voltage VB flows to the ground potential 534 side. On the other hand, when the transistor 531 is turned off, the high voltage generated in the coil 530 is statically flowed through the diode 532, and the electric charge is accumulated in the capacitor 533. Then, ON / OFF of this transistor is repeated until the boosted voltage VH is reached, and the voltage of the capacitor 533 is increased. The transistor 531 is connected to the IC 502 or the CPU 501, and the boost voltage VH output from the booster circuit 514 is configured to be detected by the IC 502 or the CPU 501. The booster circuit 514 may be configured by a DC / DC converter or the like.

The switching element 507 is connected between the low voltage source and the high voltage terminal of the solenoid 540. The low voltage source VB is, for example, a battery voltage, and the voltage value thereof is about 12 to 14 V. The switching element 506 is connected between the terminal on the low voltage side of the fuel injection device 200 and the ground potential 515.

The drive IC 502 detects the current value flowing through the fuel injection device 200 by the current detection resistors 508, 512, and 513, and switches the energization / non-energization of the switching elements 505, 506, and 507 according to the detected current value. , Producing the desired drive current. The diodes 509 and 510 apply a reverse voltage to the solenoid 540 of the fuel injection device 200 to rapidly reduce the current supplied to the solenoid 540.

The CPU 501 communicates with the drive IC 502 through the communication line 222, and it is possible to switch the drive current generated by the drive IC 502 depending on the pressure of the fuel supplied to the fuel injection device 200 and the operating conditions. Further, both ends of the resistors 508, 512 and 513 are connected to the A / D conversion port of the IC 502, and the voltage applied to both ends of the resistors 508, 512 and 513 can be detected by the IC 502.

[Operation of fuel injection device]
Next, the operation of the fuel injection device 200 under the control of the fuel injection control device 127 will be described with reference to FIG.
FIG. 4 is a diagram showing a drive command pulse (injection pulse), a drive voltage, a drive current, a valve body displacement, and a displacement of a movable iron core.

As shown in FIG. 4, when the drive command pulse Ti is input at time ts, a high voltage 304 is applied from a high voltage source boosted to a voltage higher than the battery voltage VB, and the high voltage 304 is applied to the coil 208 (see FIG. 2). The current supply is started.

After energizing the coil 208, a magnetomotive force is generated by the electromagnet composed of the fixed iron core 207, the coil 208, and the housing 209. Due to this magnetomotive force, a magnetic flux orbiting a magnetic path configured to surround the coil 208 by the fixed iron core 207, the housing 209, and the movable iron core 206 flows. At this time, a magnetic attraction force acts between the movable core 206 and the fixed core 207, and the movable core 206 and the intermediate member 214 are displaced toward the fixed core 207. After that, the movable iron core 206 is displaced until the transmission surface 219 of the valve body 201 and the transmission surface 218 of the movable iron core 206 come into contact with each other. The valve body 201 continues to maintain the contact state with the valve seat 202.

When the movable iron core 206 is displaced by the gap 250 formed between the valve body 201 and the movable iron core 206 and the transmission surface 219 of the valve body 201 and the transmission surface 218 of the movable iron core 206 collide, the valve body 201 is movable. The valve body 201 is separated from the valve seat 202 by being pulled upstream by the energy of the iron core 206. As a result, a gap is formed in the valve seat portion, a fuel passage is opened, and fuel is injected from the fuel injection hole 215. The valve body 201 is steeply displaced by the movable iron core 206 having kinetic energy.

The fuel injection control device 127 is driven by applying a high voltage 304 from time ts until the time T31 (valve opening start timing) when the movable iron core 206 and the valve body 201 collide with each other and the valve body 201 separates from the valve seat 202. A current 308 is passed through the coil 208. As a result, a necessary and sufficient magnetic attraction force is generated between the movable iron core 206 and the fixed iron core 207, and the movable iron core 206 can be made to respond quickly. Then, by making the movable iron core 206 respond quickly, for example, even if the gap 250 which is the preliminary stroke varies from individual to individual, the influence of the variation on the injection amount can be reduced.

The drive current flowing through the coil 208 is steeply raised by the application of the high voltage 304 as shown by 308 (peak current 308). Then, when the current reaches the peak current value Ip, the fuel injection control device 127 applies the high voltage 304 in the reverse direction (applies the reverse voltage). That is, the fuel injection control device 127 turns off both the switching elements 505, 506, 507 (see FIG. 3). As a result, the diodes 509 and 510 are energized by the counter electromotive force due to the inductance of the fuel injection device 200, and the current is returned to the voltage source VH side. As a result, the drive current flowing through the coil 208 drops rapidly as shown by 317 and is cut off.

In the present embodiment, the peak current value Ip is set to be reached at the valve opening start timing, and when the peak current value Ip is reached, a reverse voltage is applied. As a result, the reverse voltage can be applied at a timing that can suppress the excessive acceleration of the movable iron core 206. The application time of the drive current until the peak current value Ip according to the present invention may be determined based on the valve opening start timing. For example, when the magnetic attraction generated by the valve opening start timing is weak. , The peak current value Ip may be reached after the valve opening start timing.

By rapidly reducing the current as in the drive current 317, the magnetic attraction force acting between the movable iron core 206 and the fixed iron core 207 is reduced. Due to this decrease in magnetic attraction, excessive acceleration of the movable iron core 206 is suppressed, and the collision energy when colliding with the fixed iron core 207 can be reduced. That is, by applying a reverse voltage before the time T32 (valve opening completion timing) when the movable core 206 collides with the fixed core 207, excessive acceleration of the movable core 206 is suppressed, and the movable core 206 becomes the fixed core 207. It reduces the collision energy at the time of collision.

After the collision between the movable core 206 and the fixed core 207, the valve body 201 is displaced upstream, and the movable core 206 is displaced downward. When the fixed core 207 and the movable core 206 collide with each other, the valve body 201 and the movable core 206 are separated from each other, and the movable core 206 is displaced to the downstream side, but eventually becomes stationary and stable at the target lift position. This state is defined as the valve opening stable state.

Since the movable core 206 and the valve body 201 are configured to be capable of relative movement, when the movable core 206 collides with the fixed core 207, the valve body 201 and the movable core 206 are separated from each other, and the valve body 201 is upstream. Displace to the side. If the displacement to the upstream side is excessively large, the behavior of the movable iron core 206 and the valve body 201 becomes unstable, and there is a possibility that the injection amount varies. Therefore, by reducing the drive current before the movable iron core 206 collides with the fixed core 207, the collision energy can be reduced and the movements of the movable iron core 206 and the valve body 201 can be stabilized.

After the movable core 206 collides with the fixed core 207, if the magnetic attraction acting between the fixed core 207 and the movable core 206 is less than the energy of the collision, the movable core 206 is held in the valve open state. You will not be able to. Therefore, the fuel injection control device 127 applies the boost voltage 336 at the time T32 (valve opening completion timing) when the movable iron core 206 collides with the fixed iron core 207, and the first hold in which the first current value Ih1 is maintained. A current 331 (driving current) is passed. As a result, the magnetic attraction force acting between the fixed iron core 207 and the movable iron core 206 is re-increased, and the valve open holding state can be smoothly shifted. As a result, the operation of the movable iron core 206 and the valve body 201 can be stabilized. The timing at which the first hold current 331 is passed can be appropriately set as long as it is after the time T32 (valve opening completion timing).

The CPU 501 of the ECU 109 determines whether or not to apply the high voltage 304 in the reverse direction (apply the reverse voltage) based on the value of the fuel pressure sensor 126 calculated by the fuel injection control device 127. Specifically, when the value of the fuel pressure sensor 126 is less than the predetermined value, it is determined to apply the reverse voltage before the valve opening completion timing, and the value of the fuel pressure sensor 126 is equal to or more than the predetermined value. In addition, it is decided not to apply the reverse voltage before the valve opening completion timing.

When the value of the fuel pressure sensor 126 is high (or more than a predetermined value), the force against the magnetic attraction acting between the fixed core 207 and the movable core 206 becomes stronger, so that the movable core 206 accelerates excessively. Not done. Therefore, it is not necessary to reduce the collision energy when the movable iron core 206 collides with the fixed core 207, and the CPU 501 decides not to apply the reverse voltage before the valve opening completion timing.

Further, the time 318 for shutting off the drive current (current cutoff time 318) is determined according to the time T32 (valve opening completion timing) at which the valve opening is completed, but is generally calculated by the fuel pressure sensor 126. The higher the fuel pressure in the high-pressure fuel pipe 129, the shorter the fuel pressure. That is, the higher the fuel pressure, the stronger the force against the magnetic attraction acting between the fixed iron core 207 and the movable iron core 206. Therefore, the current cutoff time 318 is shortened and the magnetic attraction force does not decrease too much. To do so.

After applying the boost voltage 336, when the drive current reaches the first current value Ih1 capable of holding the valve open, the fuel injection control device 127 repeatedly applies the battery voltage VB and 0V (305), and the first Control is performed so as to maintain the current value Ih1 of the above, and the first hold current 331 is passed.

After holding the first hold current 331 until a predetermined time elapses, the fuel injection control device 127 lowers the current value, and when the second current value Ih2 capable of holding the valve opening is reached, the battery voltage The application of VB and the application of 0V are repeated (305), control is performed so as to maintain the second current value Ih2, and the second hold current 332 (drive current) is passed. The predetermined time is set according to the time until the magnetic flux is saturated. The first hold current 331 and the second hold current 332 are drive currents for maintaining the valve body in a valve-opened state (valve-opened holding state).

As described above, the second current value Ih2 is set to a value smaller than the first current value Ih1, and the second hold current 332 is smaller than the first hold current 331. As a result, the rise of the drive current (first hold current 331) can be improved, and the subsequent second current value Ih2 can be maintained. As a result, the valve closing can be prevented from being accelerated, and the linearity of the injection amount can be improved.

The switching from the first hold current 331 to the second hold current 332 may be carried out by applying a voltage of 0 V or less to quickly lower the current value, or by applying a voltage of 0 V or a positive voltage to gradually change the current value. .. The valve closing delay time from when the drive command pulse is turned off to when the valve body 201 is closed is affected by the magnitude of the current value when the drive command pulse is turned off. When this current value is small, the valve closing delay time becomes small (short).

When the first hold current 331 is quickly switched to the second hold current 332 by a voltage of 0 V or less, the valve closing delay time is constant, that is, the injection amount is linear. It has the effect of being able to do it. Further, when the switching from the first hold current 331 to the second hold current 332 is performed slowly, there is an effect that the injection amount during the switching period gradually shifts to the linear region. These may be selected according to the characteristics of the fuel injection device to be driven.

Subsequently, when the drive command pulse Ti is turned off at the time Te, the fuel injection control device 127 applies the drive voltage in the reverse direction (applies the reverse voltage). As a result, the current supply to the coil 208 is cut off, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attraction force disappears. As a result, the movable iron core 206 that has lost the magnetic attraction force is pushed back to the closed position where the valve body 201 contacts the valve seat 202 by the load of the first spring member 210 and the force due to the fuel pressure.

The urging force of the first spring member 210 acting on the valve body 201 is transmitted to the movable iron core 206 via the transmission surface 219 on the valve body 201 side and the transmission surface 218 on the movable iron core 206 side. When the time required for valve closing from the time Te when the drive command pulse Ti is turned off to the time Tb when the valve closing is completed elapses (at time Tb), the valve body 201 comes into contact with the valve seat 202.

After the valve body 201 comes into contact with the valve seat 202, the transmission surface 218 on the movable iron core 206 side separates from the transmission surface 219 on the valve body 201 side and continues to move in the downward direction (valve closing direction). After the time Tb when the valve closing is completed, the movable iron core 206 and the valve body 201 are separated from each other as shown in FIG. At this time, as shown by the inflection point 330, the drive voltage changes like a bend. From this change, the time Tb at which the valve closing is completed can be detected.

When the fuel injection device 200 is closed, when the valve body 201 collides with the valve seat 202, the third spring member 217 changes from extension to compression, and the direction of movement of the movable iron core 206 is reversed. As a result, the acceleration of the movable iron core 206 changes, and the inductance of the coil 208 changes. That is, when the fuel injection device 200 is closed, the drive current flowing through the coil 208 is cut off, and a counter electromotive force is applied to the coil 208. Then, when the drive current converges, the counter electromotive force gradually decreases, so that the inductance changes when the counter electromotive force decreases, so that an inflection point 330 is generated in the drive voltage.

The inflection point 330 is the valve closing completion timing of the fuel injection device 200. The inflection point 330 appears as an extreme value (maximum value or minimum value) when the time series data of the drive voltage applied to the coil 208 is second-order differentiated. Therefore, the inflection point 330 can be specified by detecting the extreme value of the time series data of the drive voltage.

Further, the fuel injection control device 127 has a valve opening timing detection unit that detects the valve opening start timing described above. The valve opening timing detection unit detects a change in the speed or acceleration of the movable iron core 206 when the movable iron core 206 reaches the maximum opening as a time change of the current flowing through the solenoid 540, and the mover is maximally opened from the detected value. Detects the timing when the speed is reached (valve opening completion timing). Further, the valve opening timing detection unit estimates (detects) the valve opening start timing by multiplying the detected valve opening completion timing by a correction constant.

FIG. 5 is a diagram for explaining the relationship between the injection amount and the drive command pulse, in which the horizontal axis represents the drive command pulse width Ti and the vertical axis represents the fuel injection amount Q for each hour. The broken line shown in FIG. 5 shows the relationship between the injection amount and the drive command pulse in the conventional case where there is no time 318 during which the drive current shown in FIG. 4 is cut off, and the solid line shown in FIG. 5 is shown in FIG. The relationship between the injection amount and the drive command pulse in the case of the present embodiment in which the indicated drive current is cut off for a period of 318 is shown.

As shown in FIG. 5, by having the time 318 during which the drive current is cut off, the excess current (excessive acceleration of the mover 206) can be suppressed, the linearity of the injection amount is improved, and the injection is performed. It is possible to suppress the amount variation.

Further, the alternate long and short dash line shown in FIG. 5 shows the relationship between the injection amount and the drive command pulse when only the second hold current 332 is passed without passing the first hold current 331 shown in FIG. As shown in FIG. 5, when the first hold current 331 and the second hold current are passed, the linearity of the injection amount can be improved as compared with the case where only the second hold current 332 is passed.

[Summary]
As described above, the fuel injection control device (fuel injection control device 127) according to the above-described embodiment includes a valve body (valve body 201) that opens a fuel passage by moving away from the valve seat (valve seat 202). A fuel injection device (fixed iron core 207) including a mover (movable iron core 206) that opens and closes the valve body and a stator (fixed iron core 207) that sucks the mover by flowing a drive current through the coil (coil 208). The fuel injection amount of the fuel injection device 200) is controlled. This fuel injection control device has a valve opening timing detector that detects the valve opening completion timing when the mover collides with the stator, and a valve opening timing detector that applies a reverse voltage before the valve opening completion timing to shut off the drive current and open the valve. It is provided with a control unit (CPU 501) that controls applying a voltage so that a hold current, which is a drive current for maintaining the valve body in the opened state after the completion timing, flows. As a result, the drive current can be reduced before the mover collides with the stator. As a result, the collision energy between the mover and the stator can be reduced, and the movement of the mover and the valve body can be stabilized.

Further, in the valve opening timing detection unit of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment, the valve opening start timing at which the mover (movable iron core 206) collides with the valve body (valve body 201) Is detected. Then, the control unit (CPU501) applies a voltage so that the drive current flows until the valve opening start timing. As a result, a necessary and sufficient magnetic attraction force can be generated between the mover and the stator (fixed iron core 207), and the mover can be made to respond quickly.

Further, the control unit (CPU501) of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment applies a reverse voltage after the valve opening start timing. As a result, the magnetic attraction force acting between the mover (movable iron core 206) and the stator (fixed iron core 207) after the valve opening start timing is reduced. As a result, it is possible to secure a magnetic attraction force that causes the mover to collide with the stator and suppress the collision energy at that time.

Further, the control unit of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment determines the application time of the drive current until the peak current value is reached, based on the valve opening start timing. Thereby, it is possible to set the application time of the drive current capable of reducing the magnetic attraction force acting between the mover (movable iron core 206) and the stator (fixed iron core 207).

Further, in the fuel injection control device (fuel injection control device 127) according to the above-described embodiment, the application time of the drive current including the peak current value is set after the mover (movable iron core 206) operates and then the valve body (valve). It is more than the time until it collides with the body 201). As a result, the drive current including the peak current value can be prevented from being interrupted before the mover collides with the valve body, and the mover can be reliably collided with the valve body.

Further, the control unit (CPU501) of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment determines the timing at which the hold current is applied based on the valve opening completion timing. As a result, the magnetic attraction force acting between the movable element (movable iron core 206) and the stator (fixed iron core 207) is re-increased, and the valve body (valve body 201) is opened. Can be smoothly transitioned to.

Further, the control unit of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment applies a voltage so that a hold current flows at the valve opening completion timing. As a result, the distance that the mover (movable iron core 206) and the valve body (valve body 201) move in the valve closing direction can be shortened, and the valve open holding state can be smoothly shifted.

Further, the hold current controlled by the fuel injection control device (fuel injection control device 127) according to the above-described embodiment is after the first hold current (first hold current 331) and the first hold current. It has a second hold current (second hold current 332) to be passed. The set value of the first hold current (first current value Ih1) is larger than the set value of the second hold current (second current value Ih2). As a result, the rise of the drive current (first hold current 331) can be improved, and the subsequent second current value Ih2 can be maintained. As a result, the valve closing can be prevented from being accelerated, and the linearity of the injection amount can be improved.

Further, the fuel injection device controlled by the fuel injection control device (fuel injection control device 127) according to the above-described embodiment is configured so that a gap is formed between the mover and the valve body in the valve closed state. There is. As a result, the drive current can be steeply increased by the valve opening start timing when the mover (movable iron core 206) collides with the valve body (valve body 201), and the drive current is controlled to flow until the valve opening start timing. can do.

Further, the control unit (CPU501) of the fuel injection control device (fuel injection control device 127) according to the above-described embodiment is in the high-pressure fuel pipe (high-pressure fuel pipe 129) communicating with the fuel injection device (fuel injection device 200). Whether or not to apply the reverse voltage before the valve opening completion timing is determined based on the fuel pressure of. As a result, when the fuel pressure (fuel pressure) is equal to or higher than a predetermined value and it is not necessary to reduce the collision energy when the mover (movable core 206) collides with the stator (fixed core 207), the valve is opened. It is possible to prevent the reverse voltage from being applied before the completion timing. If the fuel pressure (fuel pressure) is less than the specified value and it is necessary to reduce the collision energy when the mover collides with the stator, a reverse voltage should be applied before the valve opening completion timing. Can be done.

The embodiment of the fuel injection control device of the present invention has been described above, including its action and effect. However, the control device for the fuel injection device of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention described in the claims. Further, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations.

For example, in the above-described embodiment, half-lift control has been described as an example of fuel injection control. However, the fuel injection control according to the present invention may be full lift control.

101 ... Internal engine, 102 ... Piston, 103 ... Intake valve, 104 ... Exhaust valve, 106 ... Spark plug, 107 ... Ignition coil, 108 ... Water temperature sensor, 109 ... ECU, 113 ... Oxygen sensor, 116 ... Crank angle sensor, 119 ... Throttle valve, 120 ... Air flow meter, 121 ... Combustion chamber, 122 ... Accelerator opening sensor, 123 ... Fuel tank, 124 ... Low pressure fuel pump, 125 ... High pressure fuel pump, 126 ... Fuel pressure sensor, 127 ... Fuel injection control Equipment, 128 ... Exhaust cam, 129 ... High-pressure fuel pipe, 131 ... Crank shaft, 200 ... Fuel injection device, 201 ... Valve body, 202 ... Valve seat, 206 ... Movable core (movable element), 207 ... Fixed core (fixed element) ), 208 ... Coil, 209 ... Housing, 210 ... First spring member, 212 ... Fuel supply section, 214 ... Intermediate member, 215 ... Fuel injection hole, 216 ... Second spring member, 217 ... Third spring member, 218, 219 ... Transmission surface, 222 ... Communication line, 223 ... Signal line, 250 ... Gap, 304 ... High voltage, 308 ... Drive current (peak current), 318 ... Current cutoff time, 330 ... Turn point, 331 ... First Hold current, 332 ... 2nd hold current, 336 ... Boost voltage, 501 ... CPU, Ih1 ... 1st current value, Ih2 ... 2nd current value

Claims (10)

Fuel injection including a valve body that opens a fuel passage by moving away from the valve seat, a mover that opens and closes the valve body, and a stator that sucks the mover by flowing a drive current through a coil. A fuel injection control device that controls the fuel injection amount of the device.
A valve opening timing detection unit that detects the valve opening completion timing at which the mover collides with the stator, and
A reverse voltage is applied before the valve opening completion timing to shut off the drive current, and a hold current, which is a drive current for maintaining the valve body in the valve open state, flows after the valve opening completion timing. A fuel injection control device including a control unit that controls the application of a voltage to the fuel injection controller. The valve opening timing detection unit detects the valve opening start timing at which the mover collides with the valve body, and determines the valve opening start timing.
The fuel injection control device according to claim 1, wherein the control unit applies a voltage so that a drive current flows until the valve opening start timing. The fuel injection control device according to claim 2, wherein the control unit applies a reverse voltage after the valve opening start timing. The fuel injection control device according to claim 2, wherein the control unit determines an application time of the drive current until the peak current value is reached based on the valve opening start timing. The fuel injection control device according to claim 4, wherein the application time of the drive current including the peak current value is equal to or longer than the time from the operation of the mover to the collision with the valve body. The fuel injection control device according to claim 1, wherein the control unit determines a timing at which the hold current flows based on the valve opening completion timing. The fuel injection control device according to claim 6, wherein the control unit applies a voltage so that the hold current flows at the valve opening completion timing. The hold current has a first hold current and a second hold current that flows after the first hold current.
The fuel injection control device according to claim 1, wherein the set value of the first hold current is larger than the set value of the second hold current. The fuel injection control device according to claim 1, wherein the fuel injection device is configured so that a gap is formed between the mover and the valve body in a valve closed state. The fuel injection according to claim 1, wherein the control unit determines whether or not to apply a reverse voltage before the valve opening completion timing based on the fuel pressure in the high-pressure fuel pipe communicating with the fuel injection device. Control device.

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