WO2021199577A1

WO2021199577A1 - Control device, control method, and program for fuel injection device

Info

Publication number: WO2021199577A1
Application number: PCT/JP2021/001182
Authority: WO
Inventors: 亮草壁; 助川　義寛; 猿渡　匡行
Original assignee: 日立Astemo株式会社
Priority date: 2020-03-30
Filing date: 2021-01-15
Publication date: 2021-10-07
Also published as: JP2021156256A; JP7256772B2

Abstract

It has not been possible to minimize combustion fluctuation when the injection amount of a fuel injection device varies from cylinder to cylinder.　A control device 150, which controls a fuel injection device 101 that injects fuel multiple times in one combustion cycle, is provided with a control unit 500 that calculates the fuel injection amount at each injection performed in one combustion cycle, and performs control so that as the injection amounts of injections performed before the final injection become larger than the injection amount of the final injection in one combustion cycle to a greater extent, the injection pulse width of an injection pulse supplied to the fuel injection device 101 at the final injection is made less than the injection pulse widths of injection pulses supplied to the fuel injection device 101 at injections performed before the final injection to a commensurately greater extent.

Description

Fuel injection controller, control method and program

The present invention relates to a control device, a control method, and a program of a fuel injection device.

In recent years, from the viewpoint of preventing global warming and suppressing the depletion of fossil fuel resources, the engine of an internal combustion engine is required to reduce _{carbon dioxide (CO 2) during mode driving.} In _{order to reduce CO 2} , it is necessary to suppress fuel consumption, and lean combustion, in which fuel is burned in a state where it is diluted with respect to air, is an effective technology. In particular, in lean combustion, since it is necessary to ignite the air-fuel mixture in a state where the equivalent ratio in the cylinder is thin, the combustion speed becomes slow, combustion tends to become unstable, and a technique for suppressing combustion fluctuation is required. ..

There is a method disclosed in Patent Document 1 as a technique for suppressing combustion fluctuations. Patent Document 1 describes a method of suppressing variation in injection amount for each cylinder by detecting the operation timing of the valve body of the fuel injection device for each combustion injection device of each cylinder and correcting the fuel injection amount for each cylinder. Is disclosed.

JP-A-2018-197548

Combustion fluctuations include variations in the indicated mean effective pressure (IMEP) for each cylinder and variations in IMEP for each combustion cycle in each cylinder. Factors that cause variations in IMEP for each combustion cycle include variations in air flow and variations in the injection amount of the fuel injection device. Even if an attempt is made to suppress variations in the injection amount for each cylinder by using the technique described in Patent Document 1 in order to suppress combustion fluctuations, if the injection amount of the combustion injection device fluctuates in each combustion cycle, combustion occurs. In some cases, fluctuations could not be suppressed.

The present invention has been made in view of such a situation, and an object of the present invention is to suppress combustion fluctuations by reducing variations in the injection amount of fuel injected from the fuel injection device in one combustion cycle. do.

The control device according to the present invention controls a fuel injection device that injects fuel a plurality of times in one combustion cycle. This control device calculates the fuel injection amount at each injection performed in one combustion cycle, and the injection amount of the injection performed before the last injection from the injection amount of the last injection in one combustion cycle. The greater the number, the smaller the injection pulse width of the injection pulse supplied to the fuel injection device at the last injection than the injection pulse width of the injection pulse supplied to the fuel injection device in the injection performed before the last injection. It is equipped with a control unit that controls the fuel.

According to the present invention, even if the injection amount of the fuel varies in the injection performed before the last injection in one combustion cycle, the injection amount can be adjusted in the last injection, so that the injection in one combustion cycle It is possible to reduce the variation in quantity and suppress the variation in combustion.
Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

It is a figure which shows an example in the structure of the fuel injection system which concerns on 1st Embodiment of this invention. It is a figure which shows the vertical sectional view of the fuel-injection apparatus which concerns on 1st Embodiment of this invention, and the structural example of the drive circuit and ECU which are connected to drive the fuel-injection apparatus. It is an enlarged cross-sectional view which showed the example of the drive part structure of the fuel injection device which concerns on 1st Embodiment of this invention. The relationship between the general injection pulse for driving the fuel injection device according to the first embodiment of the present invention, the drive voltage and drive current supplied to the fuel injection device, the displacement amount of the valve body and the mover, and the time is shown. It is a timing chart. It is a figure which shows the detailed structural example of the drive circuit and ECU of the fuel injection device which concerns on 1st Embodiment of this invention. It is a figure which showed the injection pulse, the drive current, and the injection rate which are supplied to the fuel injection device for each cylinder from the ECU which concerns on 1st Embodiment of this invention in one combustion cycle. It is a figure which showed the injection pulse width of a certain cylinder, the displacement amount of a valve body, and the time series of the fuel pressure output from the pressure sensor attached to the fuel injection device which concerns on 1st Embodiment of this invention. Relationship between time and injection pulse width, inter-terminal voltage, drive current, second-order differential value of voltage, current, that is, second-order differential value of voltage, displacement amount of valve body, and time according to the first embodiment of the present invention. It is a figure which showed. It is a figure which showed the relationship between the injection pulse width of the fuel injection device of a certain cylinder, the injection amount, and the shot variation of the injection amount which concerns on the 1st Embodiment of this invention. The injection pulse according to the second embodiment of the present invention, the drive current supplied to the fuel injection device, the switching element of the fuel injection device, the voltage between the terminals of the solenoid, the displacement amount of the valve body and the mover, and the time. It is a figure which showed the relationship. The relationship between the injection pulse width and the injection amount and the standard deviation of the shot variation of the injection amount when the control device according to the second embodiment of the present invention controls the fuel injection device with the drive current waveform of FIG. 10 is shown. It is a figure. It is a figure which showed the injection pulse, the drive current, and the injection rate which are supplied to the fuel injection device for each cylinder from the ECU which concerns on 2nd Embodiment of this invention in one combustion cycle. It is a figure which showed the injection pulse, the drive current, and the injection rate which are supplied to the fuel injection device for each cylinder from the ECU which concerns on 3rd Embodiment of this invention in one combustion cycle. As another example of the control method according to the third embodiment of the present invention, it is a figure which showed the injection pulse, the drive current, and the injection rate which are supplied from the ECU to the fuel injection device for each cylinder in one combustion cycle. It is a figure which showed the injection pulse, the injection rate and the ignition timing which are supplied to the fuel injection device for each cylinder from the ECU which concerns on 4th Embodiment of this invention in one combustion cycle.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same function or configuration are designated by the same reference numerals, and redundant description will be omitted.

[Structure example and operation example of fuel injection system] Hereinafter, a basic configuration example and an operation example of a fuel injection system composed of a fuel injection device and a control device according to the present invention will be described with reference to FIGS. 1 to 6.

First, the configuration of the fuel injection system will be described with reference to FIG.
FIG. 1 is a diagram showing a configuration example of the fuel injection system 1. The fuel injection system 1 is an example in which the present invention is applied to an in-cylinder direct injection engine (an example of an internal combustion engine), but the present invention is not limited to this example. In the present specification, the in-cylinder direct injection engine may be simply referred to as an "engine".

As shown in FIG. 1, the fuel injection system 1 is composed of four fuel injection devices 101A to 101D and a control device 150. The in-cylinder direct injection engine according to the present embodiment includes four cylinders 108 (engine cylinders). The control device 150 is, for example, a control device for a vehicle that controls the fuel injection device 101. This control device (control device 150) controls a fuel injection device (fuel injection device 101) that injects fuel a plurality of times in one combustion cycle. In the following description, when the fuel injection devices 101A to 101D are not distinguished, they are referred to as "fuel injection device 101".

In each cylinder 108 of the fuel injection system 1, fuel injection devices 101A to 101D are installed so that atomized fuel is directly injected into the combustion chamber 107 from the injection holes 219 (see FIG. 2 described later). .. The fuel is boosted by the fuel pump 106, sent to the fuel pipe 105, and delivered to the fuel injection devices 101A to 101D through the fuel pipe 105. At one end of the fuel pipe 105, a pressure sensor 102 for measuring the fuel pressure in the fuel pipe 105 is installed. The fuel pressure varies depending on the balance between the flow rate of the fuel discharged by the fuel pump 106 and the injection amount of the fuel injected into each combustion chamber 107 by the fuel injection device 101. Based on the measurement result (fuel pressure) of the pressure sensor 102, the discharge amount of fuel discharged from the fuel pump 106 is controlled with a predetermined pressure as a target value.

Further, a pressure sensor 109 is installed between the fuel pipe 105 and the fuel injection devices 101A to 101D, respectively. The pressure sensor 109 detects the fuel pressure of the fuel injection device 101 provided in each cylinder 108 of the engine, and outputs the fuel pressure information to the engine control unit (hereinafter, referred to as “ECU”) 104.

The fuel injection of the fuel injection devices 101A to 101D is controlled by the pulse width of the injection pulse (hereinafter referred to as "injection pulse width") transmitted from the ECU 104. That is, the injection amount of the fuel injected from the fuel injection device 101 is determined based on the injection pulse width supplied to the fuel injection device 101. The command of the injection pulse width is input to the drive circuit 103 provided for each fuel injection device 101. The drive circuit 103 determines a waveform (referred to as a "drive current waveform") of a drive current (sometimes abbreviated as "current") based on a command from the ECU 104, and a fuel injection device for a time based on an injection pulse. The drive current waveform is supplied to 101A to 101D. The drive circuit 103 may be mounted as a component or a board integrated with the ECU 104. A device in which the drive circuit 103 and the ECU 104 are integrated is referred to as a control device 150.

Next, the configuration and basic operation of the fuel injection device 101 and its control device 150 will be described.
FIG. 2 is a vertical cross-sectional view of the fuel injection device 101 and a configuration example of a drive circuit 103 and an ECU 104 connected to drive the fuel injection device 101. In FIG. 2, the same symbols are used for parts equivalent to those in FIG.

The ECU 104 takes in signals indicating the state of the engine from various sensors (not shown), and calculates the width of the injection pulse and the injection timing for controlling the injection amount to be injected from the fuel injection device 101 according to the operating conditions of the internal combustion engine. I do.

Further, the ECU 104 is provided with an A / D converter and an I / O port (both not shown) for capturing signals from various sensors. The injection pulse output from the ECU 104 is input to the drive circuit 103 of the fuel injection device 101 through the signal line 110. The drive circuit 103 controls the voltage applied to the solenoid 205 (an example of a coil) and supplies a current. The ECU 104 communicates with the drive circuit 103 through the communication line 111, switches the drive current generated by the drive circuit 103 according to the pressure of the fuel supplied to the fuel injection device 101 and operating conditions, and sets the current and time. It is possible to change the value.

Next, the configuration and operation of the fuel injection device 101 will be described with reference to the vertical cross section of the fuel injection device 101 of FIG. 2 and the enlarged cross section of the vicinity of the mover 202 and the valve body 214 of FIG. FIG. 3 is an enlarged cross-sectional view showing an example of the drive unit structure of the fuel injection device 101. In particular, the relationship between the mover 202, the valve body 214, and the stator 207 will be described.

The fuel injection device 101 shown in FIGS. 2 and 3 is an electromagnetic fuel injection device including a normally closed solenoid valve. The fuel injection device 101 has a substantially rod-shaped valve body 214 inside, and an orifice cup 216 on which a valve seat 218 is formed is provided at a position facing the tip end portion of the valve body 214. The valve seat 218 is formed with an injection hole 219 for injecting fuel. Above the valve body 214, a spring (hereinafter referred to as "first spring") 210 for urging the valve body 214 in the valve closing direction (downward direction) is provided.

The solenoid (solenoid 205) is a stator (solenoid 205) that forms a space for introducing fuel between the valve seat (valve seat 218) and the valve body (valve body 214) when a drive current is supplied from the drive circuit 103. A magnetic attraction force for attracting the mover 202) is generated in the stator (stator 207). The stator (stator 207) attracts the mover (movable element 202) by magnetic attraction. The mover (movable element 202) on which the magnetic attraction force acts moves, and the valve body (valve body 214) moves in conjunction with the mover 202. When the solenoid 205 is not energized, the valve body 214 is urged in the valve closing direction by the first spring 210, and the valve body (valve body 214) seals the fuel in contact with the valve seat (valve seat 218). It has a structure (valve closed state).

A recess 202C is formed on the upper end surface 202A of the mover 202 toward the lower end surface 202B side. An intermediate member 220 is provided inside the recess 202C. The intermediate member 220 is a member located between the mover 202 and the stator 207. A recess 220A is formed upward on the lower surface side of the intermediate member 220. The recess 220A has a diameter (inner diameter) and a depth in which a stepped portion 329 (flange portion) formed in an annular shape on the outer peripheral surface of the head 214A is accommodated. That is, the diameter (inner diameter) of the recess 220A is larger than the diameter (outer diameter) of the stepped portion 329, and the depth dimension of the recess 220A is larger than the dimension between the upper end surface and the lower end surface of the stepped portion 329. big. A through hole 220B through which the protrusion 331 of the head 214A penetrates is formed in the bottom portion (bottom surface 220E) of the recess 220A.

A spring (hereinafter referred to as "third spring") 234 is held between the intermediate member 220 and the cap 232. The upper end surface 220C of the intermediate member 220 constitutes a spring seat with which one end of the third spring 234 abuts. The third spring 234 urges the mover 202 from the stator 207 side in the valve closing direction.

A lid-shaped cap 232 is arranged above the intermediate member 220. A flange portion 232A protruding in the radial direction is formed at the upper end portion of the cap 232, and a spring seat is formed in which the other end portion of the third spring 234 abuts on the lower end surface of the collar portion 232A. .. A cylindrical portion 232B is formed downward on the lower end surface of the flange portion 232A of the cap 232, and the upper portion (head 214A) of the valve body 214 is press-fitted and fixed in the tubular portion 232B.

In this way, the cap 232 and the intermediate member 220 each form the spring seat of the third spring 234. Therefore, the diameter (inner diameter) of the through hole 220B of the intermediate member 220 is smaller than the diameter (outer diameter) of the flange portion 232A of the cap 232. Further, the diameter (outer diameter) of the tubular portion 232B of the cap 232 is smaller than the inner diameter of the third spring 234.

The cap 232 receives the urging force of the first spring 210 from above and the urging force (set load) of the third spring 234 from below. The urging force of the first spring 210 is larger than the urging force of the third spring 234, and as a result, the cap 232 is the difference between the urging force of the first spring 210 and the urging force of the third spring 234. It is pressed against the protrusion 331 on the upper part of the valve body 214 by the urging force. No force is applied to the cap 232 in the direction in which the valve body 214 is removed from the protrusion 331 of the valve body 214 (lower direction in the drawing). Therefore, it is sufficient to press-fit and fix the cap 232 to the protrusion 331, and it is not necessary to weld the cap 232.

Further, in order to arrange the third spring 234, it is necessary to provide a certain distance between the lower end surface of the flange portion 232A of the cap 232 and the upper end surface 220C of the intermediate member 220. Therefore, it is easy to secure the length of the tubular portion 232B of the cap 232.

The intermediate member 220 will be described again. The state of the fuel injection device 101 shown in FIG. 2 is a state in which the valve body 214 receives the urging force by the first spring 210 and the magnetic attraction force does not act on the mover 202. In this state, the tip portion 214B (seat portion) of the valve body 214 is in contact with the valve seat 218, and the fuel injection device 101 is closed to be in a stable state.

In this valve closed state, the intermediate member 220 receives the urging force of the third spring 234, and the bottom surface 220E of the recess 220A formed in the intermediate member 220 hits the upper end surface of the stepped portion 329 of the valve body 214. I'm in contact. That is, the size (dimension) of the gap G3 between the bottom surface 220E of the recess 220A and the upper end surface of the stepped portion 329 of the valve body 214 is zero. The bottom surface 220E of the recess 220A formed in the intermediate member 220 and the upper end surface of the stepped portion 329 of the valve body 214 form contact surfaces where the intermediate member 220 and the stepped portion 329 of the valve body 214 come into contact with each other. ..

A zero spring (hereinafter referred to as "second spring") 212 is located between the lower end surface 202B of the mover 202 and the contact surface 303 formed inside the nozzle holder 201 (large diameter tubular portion 240). Is placed. Since the mover 202 receives the urging force of the second spring 212 and is urged toward the stator 207 side, the bottom surface 202D of the recess 202C formed in the mover 202 is the lower end surface 220D of the intermediate member 220. Contact. The urging force of the second spring 212 is smaller than the urging force of the third spring 234. Therefore, the mover 202 cannot push back the intermediate member 220 urged downward by the third spring 234, and moves upward (valve opening direction) by the intermediate member 220 and the third spring 234. Is stopped.

The depth dimension of the recess 220A of the intermediate member 220 is larger than the height of the stepped portion 329 of the valve body 214 (the dimension between the upper end surface and the lower end surface). Therefore, in the state shown in FIG. 3 (valve closed state), the bottom surface 202D of the recess 202C formed in the mover 202 and the lower end surface of the stepped portion 329 of the valve body 214 are not in contact with each other, and the recess 202C A gap G2 having a size (dimension) of D2 is formed between the bottom surface 202D of the above and the lower end surface of the stepped portion 329. The size D2 of the gap G2 is the size of the gap G1 between the upper end surface 202A of the stator 202 (the surface facing the stator 207) and the lower end surface 207B of the stator 207 (the surface facing the stator 202). Dimensions) Smaller than D1 (D2 <D1). As described here, the intermediate member 220 is a member that forms a gap G2 having a size of D2 between the mover 202 and the lower end surface of the stepped portion 329 of the valve body 214, and is a member that forms a gap G2. You may call it.

The third spring 234 urges the intermediate member (gap forming member) 220 in the valve closing direction (downward), and in the valve closing state of FIG. 3, the intermediate member 220 is the stepped portion 329 of the valve body 214. It is positioned on the upper end surface (reference position) of. In this state, when the lower end surface 220D of the intermediate member 220 comes into contact with the mover 202, the lower end surface of the stepped portion 329 which is the engaging part of the valve body 214 and the recess 202C which is the engaging part of the mover 202 A gap G2 having a size D2 is formed between the bottom surface 202D and the bottom surface 202D. The intermediate member 220 is positioned at the upper end surface (reference position) of the stepped portion 329 by abutting the bottom surface 220E of the recess 220A with the upper end surface (reference position) of the stepped portion 329 of the valve body 214.

Here, the urging forces of the three springs explained above will be explained again. Of the first spring 210, the second spring 212, and the third spring 234, the spring force (urging force) of the first spring 210 is the largest. Next, the spring force (biasing force) of the third spring 234 is large, and the spring force (biasing force) of the second spring 212 is the smallest.

In the present embodiment, the diameter of the through hole formed in the mover 202 is smaller than the diameter of the stepped portion 329 of the valve body 214. Therefore, during the valve opening operation in which the valve body 214 shifts from the valve closed state to the valve open state, or during the valve closing operation in which the valve body 214 shifts from the valve open state to the valve closed state, the lower end surface of the stepped portion 329 of the valve body 214. Engages with the bottom surface 202D of the recess 202C formed in the mover 202, and the mover 202 and the valve body 214 move in cooperation with each other. However, when the force for moving the valve body 214 upward or the force for moving the mover 202 downward acts independently, the valve body 214 and the mover 202 can move in different directions. The operations of the mover 202 and the valve body 214 will be described in detail later.

In the present embodiment, the outer peripheral surface of the mover 202 is in contact with the inner peripheral surface of the nozzle holder 201 (housing member) to guide the movement in the vertical direction (valve opening direction and valve closing direction). Further, the valve body 214 is guided to move in the vertical direction (valve opening direction and valve closing direction) by contacting the outer peripheral surface of the valve body 214 with the inner peripheral surface of the through hole of the mover 202. That is, the inner peripheral surface of the nozzle holder 201 functions as a guide when the mover 202 moves in the axial direction. Further, the inner peripheral surface of the through hole of the mover 202 functions as a guide when the valve body 214 moves in the axial direction. The tip end portion 214B of the valve body 214 is guided by a guide hole of the annular guide member 215. In this way, the valve body 214 is guided so as to reciprocate straight in the axial direction by the inner peripheral surface of the nozzle holder 201, the through hole of the mover 202, and the guide member 215.

In the present embodiment, the upper end surface 202A of the mover 202 and the lower end surface 207B of the stator 207 are described as being in contact with each other, but the present invention is not limited to this example. In some cases, protrusions are provided on either one or both of the upper end surface 202A of the mover 202 and the lower end surface 207B of the stator 207 so that the protrusions and the end faces or the protrusions come into contact with each other. be. In this case, the above-mentioned gap G1 becomes a gap between the contact portion on the mover 202 side and the contact portion on the stator 207 side.

Returning to FIG. 2 for explanation. A stator 207 is press-fitted into the inner peripheral portion of the large-diameter tubular portion 240 of the nozzle holder 201, and both members are welded and joined at the press-fitting contact position. The stator 207 is a component that applies a magnetic attraction force to the mover 202 to attract and attract the mover 202 in the valve opening direction. The gap formed between the inside of the large-diameter tubular portion 240 of the nozzle holder 201 and the outside air is sealed by welding the stator 207. The stator 207 is provided with a through hole (center hole) having a diameter slightly larger than the diameter of the intermediate member 220 as a fuel passage at the center thereof. The head 214A and the cap 232 of the valve body 214 are inserted through the inner circumference of the lower end of the through hole of the stator 207 in a non-contact state.

The lower end of the first spring 210 for setting the initial load is in contact with the spring receiving surface formed on the upper end surface of the cap 232 provided near the head 214A of the valve body 214. The upper end of the first spring 210 is received by the adjusting pin 224 (see FIG. 2) that is press-fitted into the through hole of the stator 207, so that the first spring 210 is placed between the cap 232 and the adjusting pin 224. It is being held. By adjusting the fixed position of the adjusting pin 224, the initial load of the first spring 210 pressing the valve body 214 against the valve seat 218 can be adjusted.

With the initial load of the first spring 210 adjusted, the lower end surface 207B of the stator 207 faces the upper end surface 202A of the mover 202 with a magnetic attraction gap (gap G1) of about 40 to 100 μm. It is configured to do. In FIG. 2, the dimensional ratio is ignored and the image is enlarged.

Further, a cup-shaped housing 203 is fixed to the outer periphery of the large-diameter cylindrical portion 240 of the nozzle holder 201. A through hole 213 is provided in the center of the bottom of the housing 203, and a large-diameter tubular portion 240 of the nozzle holder 201 is inserted through the through hole 213. The outer peripheral wall portion of the housing 203 forms an outer peripheral yoke portion facing the outer peripheral surface of the large-diameter tubular portion 240 of the nozzle holder 201. An annular or cylindrical solenoid 205 is arranged in the annular space formed between the housing 203 and the large-diameter tubular portion 240.

The solenoid 205 is formed by an annular bobbin 204 having a groove having a U-shaped cross section that opens outward in the radial direction, and a copper wire 206 wound in the groove. A rigid conductor 209 is fixed to the winding start end and the winding end end of the solenoid 205. The outer periphery of the large-diameter tubular portion 240 of the conductor 209, the stator 207, and the nozzle holder 201 is molded by injecting an insulating resin from the inner peripheral side of the upper end opening of the housing 203, and is covered with the resin molded body. An annular magnetic passage is formed in the stator 207, the mover 202, the large-diameter tubular portion 240 of the nozzle holder 201, and the housing (outer circumference yoke portion) 203 so as to surround the solenoid 205.

The fuel supplied to the fuel injection device 101 is supplied from the fuel pipe 105 provided upstream of the fuel injection device 101, and flows to the tip of the valve body 214 through the first fuel passage hole 231. The fuel is sealed by the tip portion 214B (seat portion) formed at the end portion of the valve body 214 on the valve seat 218 side and the valve seat 218. In the valve closed state, the fuel pressure creates a differential pressure between the upper part and the lower part of the valve body 214, and the valve body is formed by the fuel pressure and the force corresponding to the pressure receiving surface of the inner diameter of the seat portion (inner diameter of the tip portion 214B) at the valve seat position. 214 is pushed in the valve closing direction. Further, in the valve closed state, a gap G2 is formed between the valve body 214 and the mover 202 at their contact surfaces (the lower end surface of the stepped portion 329 and the bottom surface 202D of the recess 202C) via the intermediate member 220. Have. In this way, in the state where the valve body 214 is seated on the valve seat 218, the mover 202 is arranged with the valve body 214 in the axial direction via the gap G2.

The operation of the fuel injection device 101 configured as described above will be described. When a current is supplied to the solenoid 205, a magnetic field generated by a magnetic circuit causes a magnetic flux to pass between the stator 207 and the mover 202, and a magnetic attraction force acts on the mover 202. When the magnetic attraction force acting on the mover 202 exceeds the load by the third spring 234, the mover 202 starts to be displaced in the direction of the stator 207. At this time, since the valve body 214 and the valve seat 218 are in contact with each other, the movement of the mover 202 is performed in a state where there is no fuel flow. Since the movement of the mover 202 is a free-running movement performed separately from the valve body 214 which is subjected to the differential pressure due to the fuel pressure, the mover 202 is not affected by the fuel pressure or the like. , It is possible to move at high speed.

Further, in order to suppress fuel injection even when the combustion pressure in the cylinder 108 increases, it is necessary to strongly set the load by the first spring 210. That is, in the valve closed state, the valve body 214 can move at high speed by configuring the valve body 214 so that the load by the first spring 210 does not act on the valve body 214.

Then, when the displacement amount of the mover 202 reaches the size of the gap G2, the mover 202 transmits a force to the valve body 214 through the bottom surface 202D of the recess 202C and the lower end surface 220D of the intermediate member 220, and causes the valve body 214 to move. Pull up in the valve opening direction. At this time, the mover 202 collides with the valve body 214 in a state of performing a free-running motion and having kinetic energy. As a result, the valve body 214 receives the kinetic energy of the mover 202 and starts displacementing in the valve opening direction at high speed.

A differential pressure generated by the pressure of the fuel acts on the valve body 214. The differential pressure acting on the valve body 214 is the pressure generated as the fuel flow velocity increases and the static pressure decreases due to the Bernoulli effect in a range where the flow path cross-sectional area near the tip portion 214B (seat portion) of the valve body 214 is small. It occurs when the pressure of the fuel in the vicinity of the tip portion 214B of the valve body 214 decreases due to the descent.

The differential pressure acting on the valve body 214 is greatly affected by the cross-sectional area of the flow path near the tip portion 214B (seat portion). Therefore, the differential pressure is large under the condition that the displacement amount of the valve body 214 is small, and the differential pressure is small under the condition that the displacement amount is large. Therefore, when the valve body 214 is started to open from the closed state, the displacement is small, and the valve opening operation becomes difficult due to the large differential pressure, the valve opening of the valve body 214 is impacted by the idling motion of the mover 202. Is done. As a result, the fuel injection device 101 can perform the valve opening operation even when a higher fuel pressure is applied. Further, the urging force of the first spring 210 can be set to a stronger force with respect to the fuel pressure range in which the valve opening operation is required. By setting the first spring 210 to a stronger force, the time required for the valve closing operation, which will be described later, can be shortened, which is effective in controlling the minute injection amount.

After the valve body 214 starts the valve opening operation, the mover 202 collides with the stator 207. When the mover 202 collides with the stator 207, the mover 202 bounces off, but the mover 202 is attracted to the stator 207 by the magnetic attraction force acting on the mover 202, and eventually stops. At this time, since a force acts on the mover 202 in the direction of the stator 207 by the second spring 212, the displacement amount of the bounce can be reduced, and the time until the bounce converges can be shortened. can. Since the bounce motion is small, the time for which a gap is generated between the mover 202 and the stator 207 is shortened, and stable motion can be performed even for a smaller injection pulse width.

The mover 202 and the valve body 214 that have completed the valve opening operation in this way stand still in the valve opening state. In the valve open state, a gap (an example of a space) is formed between the valve body 214 and the valve seat 218, and fuel is injected from the injection hole 219 into the combustion chamber 107. The fuel passes through the central hole (through hole) provided in the stator 207, the fuel passage hole provided in the mover 202, and the fuel passage hole provided in the guide member 215, and is injected in the downstream direction (injection). It is designed to flow into hole 219).

After that, when the energization of the solenoid 205 is cut off, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attraction force on the mover 202 also disappears. When the magnetic attraction force acting on the mover 202 disappears, the valve body 214 is pushed back to the closed position in contact with the valve seat 218 by the load due to the first spring 210 and the force due to the fuel pressure.

[Control device drive circuit] Next, the configuration of the control device 150 of the fuel injection device 101 will be described with reference to FIG.
FIG. 5 is a diagram showing a detailed configuration example of the drive circuit 103 and the ECU 104 of the fuel injection device 101.

The control device 150 includes a drive circuit 103 and an ECU 104. For example, the ECU 104 has a drive IC (Integrated Circuit) 502 and a CPU (Central Processing Unit) 501 as an arithmetic processing device. In addition to the

pressure sensors

102 and 109, the CPU 501 captures signals indicating the state of the engine output by various sensors such as an A / F sensor, an oxygen sensor, and a crank angle sensor (not shown).

The CPU 501 is provided with a detection unit 541 that detects the operation in the fuel injection device 101 or calculates the fuel injection amount. Further, the drive IC 502 is provided with a current control unit 542 that controls the drive current supplied to the solenoid 205. The drive current is controlled, for example, by combining the injection pulse, the drive voltage, and the drive current supplied to the solenoid 205. The CPU 501 and the drive IC 502 are referred to as a control unit 500. Further, the ECU 104 may include the drive circuit 103. Further, the CPU 501 may be configured with a detection unit 541 and a current control unit 542, and the drive IC 502 may drive the drive circuit 103 under the control of the current control unit 542 to supply a drive current to the fuel injection device 101.

As shown in FIG. 1, the pressure sensor 102 is attached to the fuel pipe 105 upstream of the fuel injection device 101, and the pressure sensor 109 is attached between the fuel pipe 105 and the fuel injection device 101. .. The A / F sensor measures the amount of inflow air into the cylinder 108 (engine cylinder). The oxygen sensor detects the oxygen concentration of the exhaust gas discharged from the cylinder 108. The CPU 501 controls the injection amount of fuel injected from the fuel injection device 101 according to the operating conditions of the internal combustion engine based on the signals captured from various sensors. The pulse width of the injection pulse (injection pulse width shown in FIG. 4). Ti) and injection timing are calculated.

Further, the CPU 501 outputs the injection pulse width Ti to the drive IC 502 of the fuel injection device 101 through the communication line 504. 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 101 (that is, the solenoid 205). The switching

elements

505, 506, and 507 are composed of, for example, FETs, transistors, and the like, and can switch between energization and de-energization of the fuel injection device 101.

The ECU 104 is equipped with a register and a memory 501M (an example of a storage medium) for storing numerical data necessary for engine control such as calculation of an injection pulse width. The register and the memory 501M are included in the control device 150 or the CPU 501 in the control device 150. In the example of FIG. 5, the memory 501M is arranged outside the CPU 501. The memory 501M may store a computer program for the CPU 501 to control the drive of the fuel injection device 101. In this case, the CPU 501 reads and executes the computer program recorded in the memory 501M, thereby realizing all or part of the function of controlling the drive of the fuel injection device 101. Instead of the CPU 501, another arithmetic processing device such as an MPU (Micro Processing Unit) may be used.

Then, the control device (control device 150) includes a control unit (control unit 500). The control unit (control unit 500) calculates the fuel injection amount at each injection performed in one combustion cycle, and is performed before the injection amount of the last injection in one combustion cycle and before the last injection. The larger the injection amount of the injection, the more the last injection from the injection pulse width Ti (see FIG. 4) of the injection pulse supplied to the fuel injection device (fuel injection device 101) in the injection performed before the last injection. Controls so that the injection pulse width Ti of the injection pulse supplied to the fuel injection device (fuel injection device 101) is reduced.

The switching element 505 is connected between the booster circuit 514 (high voltage source) that supplies the boost voltage VH and the high voltage side terminal (power supply side terminal 590) of the solenoid 205 of the fuel injection device 101. The boost voltage VH output by the boost circuit 514 is higher than the battery voltage VB supplied by the battery voltage source 520 (low voltage source) to the drive circuit 103. For example, the boost voltage VH, which is the initial voltage output by the boost circuit 514, is 60 V, and is generated by boosting the battery voltage VB by the boost circuit 514.

As a method of realizing the booster circuit 514, there are, for example, a method of configuring with a DC / DC converter and the like, and a method of configuring with a solenoid 530, a transistor 531 and a diode 532 and a capacitor 533 as shown in FIG. In the case of the latter booster circuit 514, when the transistor 531 is turned on, the current due to the battery voltage VB flows to the ground potential 534 side via the solenoid 530. On the other hand, when the transistor 531 is turned off, the high voltage generated in the solenoid 530 is rectified through the diode 532, and the electric charge is accumulated in the capacitor 533. The booster circuit 514 can increase the voltage of the capacitor 533 to the booster voltage VH by repeating ON / OFF of the transistor 531. The transistor 531 is connected to the drive IC 502 or the CPU 501, and is configured so that the boost voltage VH output from the boost circuit 514 can be detected by the drive IC 502 or the CPU 501.

Further, a diode 535 is provided between the power supply side terminal 590 of the solenoid 205 and the switching element 505 so that a current flows from the booster circuit 514 (high voltage source) in the direction of the solenoid 205 and the ground potential 515. .. Further, a diode 511 is also provided between the power supply side terminal 590 of the solenoid 205 and the switching element 507 so that a current flows from the battery voltage source 520 (low voltage source) in the direction of the solenoid 205 and the ground potential 515. There is. While the switching element 507 is energized, no current flows from the ground potential 515 toward the solenoid 205, the battery voltage source 520, and the booster circuit 514.

Further, the switching element 507 is connected between the battery voltage source 520, which is a low voltage source, and the power supply side terminal 590 of the fuel injection device 101. The value of the battery voltage VB output by the battery voltage source 520 is, for example, about 12V to 14V. The switching element 506 is connected between the terminal on the low voltage side of the fuel injection device 101 and the ground potential 515. The drive IC 502 detects the current value flowing through the fuel injection device 101 (each part of the drive circuit 103) by each of the

current detection resistors

508, 521, and 513. The drive circuit 103 switches between energization and de-energization of the switching

elements

505, 506, and 507 according to the current value detected by the drive IC 502, and generates a desired drive current.

The

diodes

509 and 510 are provided to apply a reverse voltage to the solenoid 205 of the fuel injection device 101 to rapidly reduce the current supplied to the solenoid 205. The CPU 501 communicates with the drive IC 502 through the communication line 503, and can switch the drive current generated by the drive IC 502 depending on the pressure of the fuel supplied to the fuel injection device 101 and the operating conditions. Further, both ends of the

resistors

508, 512 and 513 are connected to the A / D conversion port of the drive IC 502, and the voltage applied to both ends of the

resistors

508, 512 and 513 can be detected by the drive IC 502.

[General timing chart] Next, referring to FIG. 4, the injection pulse output from the ECU 104, the drive voltage and drive current (excitation current) at both ends of the solenoid 205 of the fuel injection device 101, and the fuel injection device. The relationship with the displacement amount (valve body behavior) of the valve body 214 of 101 will be described. FIG. 4 is a timing chart showing the relationship between a general injection pulse for driving the fuel injection device 101, a drive voltage and drive current supplied to the fuel injection device 101, displacement amounts of the valve body 214 and the mover 202, and time. Is.

When the injection pulse 405 is input to the drive circuit 103, the drive circuit 103 energizes the switching

elements

505 and 506 according to the input injection pulse width Ti. As a result, the drive circuit 103 applies a high voltage 401 to the solenoid 205 by the boosted voltage VH boosted to a voltage higher than the battery voltage VB, and starts supplying the drive current to the solenoid 205. Here, the drive current supplied by the drive circuit 103 to the solenoid 205 is held in a state where the peak current for driving the mover (movable element 202) and the mover (movable element 202) are attracted to the solenoid (solenoid 205). Therefore, it consists of a holding current that switches in a range lower than the maximum value of the peak current.

The drive circuit 103 stops applying the high voltage 401 when the current value of the current supplied to the solenoid 205 reaches the maximum drive current I _peak (hereinafter referred to as “maximum current”) predetermined in the ECU 104.

When the switching element 506 is turned on and the switching

elements

505 and 507 are de-energized during the transition period from the maximum current I _{peak to the holding current 403, the drive circuit 103 applies a voltage of substantially 0 V to the solenoid 205.} The current supplied to the solenoid 205 flows through the paths of the fuel injection device 101, the switching element 506, the resistor 508, the ground potential 515, and the fuel injection device 101, so that the current flowing through the solenoid 205 gradually decreases. By gradually reducing the current flowing through the solenoid 205, the current supplied to the solenoid 205 can be secured. Therefore, even when the fuel pressure supplied to the fuel injection device 101 increases, the fuel injection device 101 can stably open the valve until the mover 202 and the valve body 214 reach the maximum height position.

The holding current 403 is a holding current for holding the mover 202 at the maximum height position. The maximum height position is the position where the mover 202 comes into contact with the stator 207 (G1 = 0).

On the contrary, _{when the switching elements 505, 506, and 507 are turned off during the transition period from the maximum current I peak} to the holding current 403, the diode 509 and the diode 510 are energized by the counter electromotive force due to the inductance of the fuel injection device 101. When the diode 509 and the diode 510 are energized, the current of the solenoid 205 is returned to the booster circuit 514 side, and the current supplied to the fuel injection device 101 rapidly drops from the _{maximum current I peak like the current 402.} As a result, the time required for the current flowing through the solenoid 205 to reach the level of the holding current 403 is shortened. Therefore, when the switching

elements

505, 506, and 507 are turned off, there is an effect of accelerating the time from when the current flowing through the solenoid 205 reaches the holding current 403 to when the magnetic attraction becomes constant after a certain delay time. ..

Then, when the current flowing through the solenoid 205 becomes smaller than the current value 404 (almost the same level as the holding current 403) required to hold the valve body 214 at the maximum height position, the drive circuit 103 energizes the switching element 506. At the same time, the switching element 507 is switched between energization and de-energization. As a result, the battery voltage VB is applied to the solenoid 205, and the level of the holding current 403 is maintained. A switching period is provided to control such a predetermined holding current 403 to be maintained.

In FIG. 4, the transition period until the shift to the hold current 403 from the maximum current _{I peak,} after the drive current drops to the level of the holding current 403 is greater than the holding current 410 at a timing _{t 46,} the holding current 410 is coercive It is shown that there is a switching period controlled by the controller 150 to hang down. However, there may be no switching period for maintaining this holding current 410.

When the fuel pressure supplied to the fuel injection device 101 increases, the fluid force acting on the valve body 214 increases, and the time until the valve body 214 reaches the target opening due to the fluid resistance becomes long. As a result, the arrival timing of the target opening degree may be delayed with respect to the arrival time of the set _{maximum current I peak.} However, when the current of the solenoid 205 is rapidly reduced, the magnetic attraction acting on the mover 202 is also rapidly reduced, so that the behavior of the valve body 214 becomes unstable, and in some cases, the valve closing is started even when the power is on. It may end up. When the switching element 506 is energized and the current is gradually reduced during the transition from the maximum current I _peak to the holding current 403, the decrease in magnetic attraction can be suppressed and the stability of the valve body 214 at high fuel pressure is ensured. There is an effect that can be done.

The fuel injection device 101 is driven by the profile of the drive current supplied to the solenoid 205. Between the start of application of the high voltage 401 and the time when the current of the solenoid 205 _{reaches the maximum current I peak} , the mover 202 _{starts displacement at timing t 41} , and the valve body 214 starts displacement at timing t _42. (G2 = 0). After that, the mover 202 and the valve body 214 reach the maximum height position. The maximum height position is the amount of displacement in which the mover 202 comes into contact with the stator 207. The control that the mover 202 and the valve body 214 reach the maximum height position in this way is called "full lift". When the mover 202 comes into contact with the valve body 214 and the injection pulse 406 is turned off as shown by the alternate long and short dash line at _{the timing t 42 when the valve body 214 starts to be displaced, the momentum of the mover 202 drops.} In this case, since the mover 202 and the valve body 214 decelerate, the mover 202 and the valve body 214 do not reach the maximum height position. The control in which the mover 202 and the valve body 214 do not reach the maximum height position in this way is called a "half lift".

Then, the control unit (control unit 500) sets the peak current supplied to the solenoid (solenoid 205) at the last injection from the peak current supplied to the solenoid (solenoid 205) at the injection performed before the last injection. The valve body (valve body 214) is operated at full lift at the final injection.

_{When the mover 202 collides with the stator 207 at the timing t 43} when the mover 202 reaches the maximum height position, the mover 202 makes a bouncing motion with the stator 207. The valve body 214 is configured to be able to be displaced relative to the mover 202. Therefore, the valve body 214 is separated from the mover 202, and the displacement of the valve body 214 overshoots beyond the maximum height position. That is, the lower end surface of the stepped portion 329 of the valve body 214 is separated from the bottom surface 202D of the recess 202C formed in the mover 202.

Then, at timing t ₄₄ , the mover 202 is sucked into the stator 207 together with the valve body 214 again. Then, the mover 202 comes to rest at a predetermined maximum height position by the magnetic attraction generated by the holding current 403 and the force in the valve opening direction of the second spring 212. Further, the valve body 214 sits on the mover 202, stands still at a position corresponding to the maximum height position, and is in the valve open state (timing t ₄₅ ).

In the case of a fuel injection device having a movable valve in which the valve body 214 and the mover 202 are integrated, the displacement amount of the valve body 214 does not become larger than the maximum height position, and after reaching the maximum height position. The displacement amounts of the mover 202 and the valve body 214 are the same.

[First Embodiment] Up to this point, the configuration and operation examples common to each embodiment of the present invention have been described. From here on, the control device and the control method according to the first embodiment will be described with reference to FIGS. 6 to 9.

FIG. 6 is a diagram showing an injection pulse, a drive current, and an injection rate supplied from the ECU 104 to the fuel injection device 101 for each cylinder 108 in one combustion cycle. Here, the injection rate is a value representing the flow rate per unit time of the fuel injected from the fuel injection device 101 into the combustion chamber 107. Although the configuration of three cylinders is shown in FIG. 6, the same effect can be obtained even if the number of cylinders is changed by using the present invention. Further, since the fuel injection amount can be calculated based on the injection rate and the time, the injection amount may be referred to in the following description with reference to the graph of the injection rate.

In FIG. 6, among the three cylinders, the injection pulse, the drive current, and the injection rate of the fuel injection device 101 provided in the first cylinder are represented by a chain line, and the injection pulse of the fuel injection device 101 provided in the second cylinder. The drive current and injection rate are represented by solid lines. Further, the injection pulse, the drive current, and the injection rate of the fuel injection device 101 provided in the third cylinder are represented by broken lines.

The control device 150 according to the first embodiment controls the injection amount of the fuel injection device 101 that injects fuel a plurality of times in one combustion cycle. Here, the control device 150 supplies a drive current having the same injection pulse width to each of the fuel injection devices 101 of each cylinder in the injection performed before the last injection in one combustion cycle, and fuels the fuel. It is assumed that the injection device 101 has performed the injection 601. In this case, as shown in the injection rate 603 of the first cylinder, the injection rate 604 of the second cylinder, and the injection rate 605 of the third cylinder, the injection rate fluctuates for each cylinder 108. Therefore, the injection amount obtained by integrating the injection rate per unit time with time also varies from cylinder to cylinder 108. As a result, the variation in the injection amount during one combustion cycle becomes large, and the combustion variation becomes large.

Therefore, the control device 150 calculates the injection amount of each injection by the fuel injection in one combustion cycle, and the larger the injection amount of the injection performed before the last injection in one combustion cycle, the more the pulse of the last injection. A control unit 500 for controlling the width to be reduced is provided. At this time, in the current control unit (current control unit 542), the more the injection amount of the injection performed before the last injection is larger than the appropriate injection amount, the more the fuel injection device (fuel injection device 101) is in the final injection. The injection pulse width Ti supplied to the vehicle is reduced. Further, the current control unit (current control unit 542) tells the fuel injection device (fuel injection device 101) that the injection amount of the injection performed before the last injection is smaller than the appropriate injection amount at the last injection. Increase the injection pulse width Ti to be supplied.

Specifically, after the ECU 104 supplies the injection pulse having the injection pulse width indicated by the injection 601 to the fuel injection device 101 of each cylinder 108, the detection unit 541 calculates the injection amount for each fuel injection device 101 of each cylinder 108. do. Then, in the final injection during one combustion cycle, the current control unit 542 increases the injection pulse to the fuel injection device 101 of the first cylinder, which has a small injection amount, as in the injection pulse width 608, and injects the injection amount. For the fuel injection device 101 of the third cylinder, which has a large number of fuels, the injection pulse width is corrected to be as small as 606. However, the current control unit 542 does not correct the injection amount for the fuel injection device 101 of the second cylinder in which the injection amount is appropriate. In this way, the current control unit 542 can suppress combustion fluctuations during one combustion cycle by correcting the injection amount of the fuel injection device 101 for each cylinder 108 at the final injection during one combustion cycle.

Due to such control, shot variation in the injection amount occurs at the final injection 602 in one combustion cycle in each cylinder 108. Therefore, the current control unit 542 makes the injection pulse width of the last injection 602 in one combustion cycle smaller than the injection pulse width of the injection 601 performed before the last injection 602. By such control, even if the shot variation of the injection amount occurs in the final injection 602, the current control unit 542 reduces the influence on the injection amount in one combustion cycle, so that the combustion fluctuation can be suppressed.

Since the control device 150 according to the first embodiment can suppress shot variation in the injection amount during one combustion cycle, combustion variation in each cylinder 108 even under transient conditions in which the engine speed and load change. The effect of suppressing the variation of the above can be obtained. Further, by suppressing the shot variation of the injection amount, it is possible to suppress an increase in the amount of fuel adhering to the wall surface caused by the cylinder 108 having a large injection amount, so that HC and CO emitted from the engine can be reduced.

<Method of detecting the first injection amount> Next, the control method according to the first embodiment and the method of detecting the injection amount in the control device 150 will be described. First, a method of detecting the first injection amount will be described with reference to FIG. 7.
FIG. 7 is a diagram showing a time series of the injection pulse width of a cylinder 108, the displacement amount of the valve body 214, and the fuel pressure output from the pressure sensor 109 attached to the fuel injection device 101.

Here, from the well-known orifice formula Q = cA√ (2 / ρ · ΔP), it is shown that the fuel injection amount Q is proportional to the square root of the pressure drop ΔP. In the formula, c is the flow coefficient, A is the area of the orifice, ρ is the density of the fuel, and ΔP is the differential pressure. Therefore, the detection unit 541 can estimate (calculate) the injection amount by detecting the change ΔP of the fuel pressure of the fuel injection device (fuel injection device 101) detected by the pressure sensor 109.

FIG. 7 shows a state _{from the timing t 71} when the valve body starts to open to the timing t _{74 when the valve body 214 closes.} The amount of displacement of the valve body and the change in the pressure of the fuel in the fuel injection device 101 due to the injection 701 will be described.

In the injection 701, after the injection pulse is turned on from OFF and a predetermined time elapses, the valve body 214 starts moving and the amount of displacement of the valve body increases. Then, since the fuel is injected from the injection hole 219 shown in FIG. 2, the pressure of the fuel in the fuel injection device 101 decreases. When the valve body displacement reaches the maximum opening, the reduced fuel pressure becomes almost constant. After the fuel is injected at a predetermined injection amount, the valve body 214 starts closing, so that the valve body displacement amount is reduced. The pressure of the fuel in the fuel injection device 101 increases as the amount of displacement of the valve body decreases. When the amount of displacement of the valve body becomes zero, the pressure of the fuel in the fuel injection device 101 returns to almost the original value. However, as will be described later, the pressure drop 703 occurs by the amount of the fuel injected by the fuel injection device 101.

_{Here, the detection unit 541 continuously detects the pressure 702 from the timing t 71} when the valve body starts to open to the timing t ₇₄ when the valve body 214 closes, and calculates the valve body 214 by the formula of the orifice. The injection amount can be calculated accurately by integrating the injection amount at each displacement amount.

Further, the detection unit 541 detects the injection amount using the pressure detected by the pressure sensor 109, so that the valve body 214 can be subjected to variations in the valve opening start timing and the valve closing completion timing of the valve body 214. It is also possible to detect variations in the injection amount that occur when the eccentricity occurs. Therefore, the current control unit 542 can improve the correction accuracy of the injection amount.

The control device 150 is controlled so that the fuel is not supplied from the fuel pump 106 between the time when the valve body 214 starts to open and the time when the valve body 214 completes closing, so that the fuel injection device 101 injects fuel. A pressure drop of 703 occurs by the amount of the fuel used. However, there is a correlation between the pressure drop 703 and the injection amount of the fuel injection device 101 of each cylinder 108. For example, the larger the pressure drop 703, the smaller the injection amount of the fuel injection device 101. Therefore, when the detection unit 541 detects the pressure drop 703, the current control unit 542 controls the injection pulse width of the final injection 602 to be smaller as the pressure drop 703 becomes larger. By controlling the injection pulse width of the final injection 602 in this way, the current control unit 542 can suppress variations in the injection amount during one combustion cycle.

<Second Injection Amount Detection Method> Next, a second injection amount detection method will be described with reference to FIG.
_{FIG. 8 shows the relationship} between the injection pulse width Ti, the terminal voltage V inj, the drive current, _{the second derivative value of the voltage VL1} , the current, that is, the second derivative value of the voltage _VL2 , and the displacement amount of the valve body 214, and time. It is a figure shown.

The detection unit (detection unit 541) is a valve body (valve body) of the fuel injection device (fuel injection device 101) due to an electrical change caused by the collision of the mover (movable element 202) with the stator (stator 207). The fuel injection period obtained from the valve opening start timing and the valve closing completion timing of 214) is estimated, and the injection amount is calculated based on the injection period. For example, the current control unit 542 applies the battery voltage VB to the stator 207 before the valve body 214 reaches the maximum height position. Here, the valve body 214 from the injection pulse is ON to start displaced the duration of moving the period T _M801, the valve displacement is to the period T _M802 a period including the moment in which the maximum height position .. The detection unit 541 can detect an electrical change caused by the collision of the mover 202 with the stator 207, specifically, a change in inductance, at an inflection point of the current in the _{period T m 802.} _{Therefore, the detection unit 541 can detect the valve opening completion timing t 81} at which the valve body 214 completes valve opening by detecting the timing at which the second derivative value of the current becomes maximum in the period T _{m 802.}

Further, when the current control unit 542 turns off the injection pulse and the valve body 214 comes into contact with the tip portion 214B (seat portion), the mover 202 is separated from the valve body 214 and parabolic in the valve closing direction. At this time, since the load and fluid force of the first spring 210 acting through the valve body 214 do not act on the mover 202, the acceleration of the mover 202 changes and the inflection point 801 changes to the voltage between terminals. Occurs. Here, the period until immediately before the injection pulse valve body displacement since the OFF becomes 0 and the period T _M803, the valve displacement is to the period T _M804 a period including a moment became 0. The detection unit 541 can detect the valve closing completion timing t ₈₂ of the valve body 214 by detecting the minimum value of the second derivative value of _{the voltage VL1} _{between the terminals in the period T m804} .

Further, assuming that the fuel injection period is from the start of valve opening to the completion of valve closing of the valve body 214, there is a positive correlation between the injection period and the injection amount. Then, as the injection period becomes longer, the fuel injection amount increases.

The following describes a detection method of the valve opening start timing t _80. The valve opening completion timing t ₈₁ and the valve opening start timing t ₈₀ have a high correlation. Therefore, the detection unit 541 can detect the valve _{opening start timing t 80} by _{multiplying the detected valve opening completion timing t 81} by a correction constant set in advance by the ECU 104. Then, the current control unit (current control unit 542) supplies the injection pulse having the injection pulse width Ti changed to the fuel injection device (fuel injection device 101).

According to the control method performed by the control device 150 according to the first embodiment of the present invention, the fuel injection device 101 in which the current control unit 542 has a longer injection period from the valve opening start timing to the valve closing completion timing is such that the fuel injection device 101 has a longer injection period. The injection pulse width of the last injection 602 is corrected to be smaller, and the fuel injection device 101 having a shorter injection period is corrected to have a larger injection pulse width of the last injection 602. By correcting the injection pulse width by the current control unit 542 in this way, the variation in the injection amount during one combustion cycle is suppressed, and the variation in the equivalent ratio is reduced, so that the combustion fluctuation can be suppressed.

<Control method in which the last injection is a full lift injection> Next, a control method in which the last injection 602 in one combustion cycle is a full lift injection will be described with reference to FIGS. 8 and 9.
FIG. 9 is a diagram showing the relationship between the injection pulse width Ti of the fuel injection device 101 of a certain cylinder 108, the injection amount, and the shot variation of the injection amount.

The ECU 104 sets the injection pulse width of the last injection 602 shown in FIG. 6 to be shorter than the injection pulse width of the injection performed before the last. Further, in the final injection 602, as shown in FIG. 8, the valve body 214 may come into contact with the stator 207, that is, the valve body 214 may be driven to reach the maximum height position (referred to as “full lift”). ..

As shown in FIG. 9, when the injection pulse width supplied by the current control unit 542 to the fuel injection device 101 exceeds a certain injection pulse width 91, the valve body 214 starts to be displaced, and the fuel is discharged from the fuel injection device 101. Injection is started. Further, when the current control unit 542 increases the injection pulse width, the mover 202 comes into contact with the stator 207 after the injection pulse width 93, and thereafter, the injection amount increases according to the length of the injection pulse width.

However, when the mover 202 collides with the stator 207, the mover 202 bounces. Therefore, in the section 902 of the injection pulse widths 92 to 93, the shot variation of the injection amount becomes large. Therefore, if the time from when the current control unit 542 stops the injection pulse until the valve body 214 closes changes for each injection pulse, a section 902 in which the shot variation of the injection amount becomes large occurs. In the section 903 after the injection pulse width 93 where the bounds of the mover 202 and the stator 207 converge, the shot variation of the injection amount becomes small.

It can be explained as follows that the shot variation of the injection amount becomes large in the section 902 of the injection pulse width 92 to 93. For example, in the

sections

902 and 903 after the injection pulse width 92, the valve body 214 is driven by a full lift that reaches the maximum height position. On the other hand, the section 901 having the injection pulse widths 91 to 92 is driven by a half lift in which the valve body 214 does not reach the maximum height position.

The amount of displacement of the valve body 214 controlled by the half lift is not geometrically regulated. However, when the valve body 214 is affected by an external force such as the fluid force of the fuel, the displacement amount of the valve body 214 or the eccentric amount of the valve body 214 becomes large, so that the shot variation of the injection amount becomes large. Further, even in the case of full lift, as described above, in the section 902 of the injection pulse width 92 to 93, the mover 202 and the stator 207 bounce, so that the shot variation of the injection amount becomes large.

Therefore, in the control method performed by the control device 150 according to the first embodiment of the present invention, the last injection 602 in one combustion cycle for correcting the injection pulse width is injected under the condition of full lift after the injection pulse width 92. Control to do. By such control, the control device 150 can suppress the shot variation of the injection amount and reduce the variation of the injection amount during one combustion cycle.

Also, the shot variation of the injection amount is larger in the section 902 than in the section 903. Therefore, the current control unit 542 may control the final injection 602 of the fuel injection device 101 by supplying an injection pulse larger than the injection pulse width 93 to the fuel injection device 101. By using the injection pulse width larger than the injection pulse width 93 by the current control unit 542, it is possible to further suppress the shot variation of the injection amount and enhance the effect of suppressing the combustion fluctuation.

[Second Embodiment] Next, an example of the control method of the fuel injection device according to the second embodiment of the present invention will be described with reference to FIGS. 5, 10, 11 and 12.

Figure 10 is injection pulse according to the second embodiment of the present invention, the driving current supplied to the fuel injection device 101, the switching

elements

505, 506 and 507 of the fuel injection device 101, the terminal voltage _{V inj} solenoid 205 It is a figure which showed the relationship between the displacement amount of the valve body 214 and the mover 202, and time.

FIG. 10 describes how the current control unit 542 drives the fuel injection device 101 using three types of

drive currents

1001, 1002, 1003. Then, the drive current, the behavior of the switching element, the voltage between terminals, and the displacement amount of the valve body when the drive current 1001 is used are represented by thick solid lines, and the drive current, the behavior of the switching element, and the distance between terminals when the drive current 1002 is used are shown. The voltage and the amount of displacement of the valve body are represented by thick broken lines. Further, the drive current, the behavior of the switching element, the voltage between terminals, and the amount of displacement of the valve body when the drive current 1003 is used are represented by thin broken lines.

FIG. 11 is a diagram showing the relationship between the injection pulse width Ti and the injection amount and the standard deviation (σ) of the shot variation of the injection amount when the control device 150 controls the fuel injection device 101 with the drive current waveform of FIG. Is. _{In FIG. 11, the injection amount characteristic (Q 1101} ) when the ECU 104 controls the fuel injection device 101 with the drive current 1001 (see FIG. 10) is represented by a thick line, and the injection when the fuel injection device 101 is controlled with the drive current 1002. The quantity characteristic (Q ₁₁₀₂ ) is represented by a thin line.

The shot variation of the injection amount of the fuel injection device 101 changes depending on the individual difference of the fuel injection device 101 and the environmental conditions (temperature, etc.). For example, when the drive current 1001 is used, the injection amount rapidly increases until the injection pulse width Ti reaches the injection pulse width 1103, and in the section where the injection pulse width Ti is the injection pulse width 1103 to 1104, the reference indicated by the alternate long and short dash line. The injection amount increases or decreases with respect to the line. Therefore, the shot variation of the injection amount in the section where the injection pulse width Ti has the injection pulse width 1103 to 1104 becomes large. However, when the injection pulse width Ti becomes the injection pulse width 1104 or more, the increase / decrease in the injection amount with respect to the reference line becomes small, and the shot variation of the injection amount becomes small and becomes a constant value. Under the condition that the injection pulse width Ti is large as described above, the current control unit 542 applies a reverse voltage to the solenoid 205 to rapidly reduce the current waveform of the drive current 1001 and decelerate the valve body 214. Here, the waveform represented by the injection amount characteristic (Q ₁₁₀₁ ) shown in FIG. 11 is called a fast fall waveform.

On the other hand, when the drive current 1002 is used, the injection amount rapidly increases until the injection pulse width Ti becomes the injection pulse width 1103, which is the same as when the drive current 1001 is used. However, in the section where the injection pulse width Ti is the injection pulse width 1103 to 1104, the injection amount increases or decreases with respect to the reference line indicated by the alternate long and short dash line, but the increase or decrease is smaller than when the drive current 1001 is used. Therefore, the shot variation of the injection amount in the section where the injection pulse width Ti is the injection pulse width 1103 to 1104 is smaller than that when the drive current 1001 is used. However, when the injection pulse width Ti becomes the injection pulse width 1104 or more, the injection amount increases or decreases with respect to the reference line, so that the shot variation of the injection amount becomes larger than when the drive current 1001 is used. Under the condition that the injection pulse width Ti is small as described above, the current control unit 542 supplies a large drive current 1002 to the solenoid 205 before the valve body 214 opens, thereby suppressing the valve opening variation of the valve body 214. .. Here, the waveform represented by the injection amount characteristic (Q ₁₁₀₂ ) shown in FIG. 11 is referred to as a peak hold waveform.

The driving current 1003 is held for a predetermined period in the vicinity of the maximum driving current value _{I peak2} shown in FIG. Even if the drive current 1003 having such a current waveform is used, a predetermined current value can be given to the solenoid 205 until the valve body 214 opens, so that the same effect as when the drive current 1002 is used can be obtained. Be done. After that, the drive current 1003 decreases rapidly like the drive current 1002 and is held in the vicinity of the current value 1012, but the shot variation of the injection amount becomes larger than when the drive current 1001 is used.

In this way, the injection amount and the shot variation of the injection amount change depending on the magnitude of the drive current. Therefore, the control device 150 requires a technique for correcting the injection amount in one combustion cycle.

First, an operation example when the control device 150 controls the injection amount of the fuel injection device 101 with the drive current 1002 will be described with reference to FIG. _{At the timing t 101} shown in FIG. 10, when an injection pulse having an injection pulse width Ti is input from the CPU 501 to the drive IC 502 through the communication line 504, the switching element 505 and the switching element 506 are turned on. Then, when a boost voltage VH higher than the battery voltage VB is applied to the solenoid 205, the drive current 1002 supplied to the fuel injection device 101 rapidly rises from 0A as shown in the current 1010.

When a current is supplied to the solenoid 205, a magnetic attraction force acts between the mover 202 and the stator 207. The mover 202 starts displacement at the timing when the resultant force of the magnetic attraction force, which is the force in the valve opening direction, and the load of the second spring 212 exceeds the load of the third spring 234, which is the force in the valve closing direction. do. After that, after the mover 202 slides in the gap G2, the mover 202 _{collides with the valve body 214 before the timing t 106} , so that the displacement of the valve body 214 is started and fuel is injected from the fuel injection device 101. NS.

When the drive current 1002 reaches a maximum current _{I peak 1} at the timing _{t 102,} the switching element 506 is energized. At this time, the switching element 505 and the switching element 507 are de-energized. Then, a voltage of approximately 0 V is applied to both ends of the fuel injection device 101 by a so-called free wheel in which a current is regenerated between the ground potential 515, the switching element 506, the fuel injection device 101, and the ground potential 517, and the drive current 1002 is generated. The current gradually decreases as shown in 1011.

After that, when the timing t ₁₀₃ is reached, the control device 150 switches between energization and de-energization of the switching element 507, and controls the drive current 1002 so as to hold the current value 1012 at or near the current value 1004. The period in which the control device 150 controls the drive current 1002 is referred to as a first current holding period 1055.

Here, the control device 150 sets a current value (current value higher than the current value 1004) capable of holding the valve body 214 at the maximum height position until _{the timing t 104 when the valve body 214 reaches the maximum height position.} It is preferable to supply the solenoid 205. Under the condition that the valve body 214 is at a height lower than the maximum height position, there is a magnetic gap between the mover 202 and the stator 207, so that the magnetic resistance increases and the mover 202 and the stator 207 come into contact with each other. The magnetic attraction is lower than when it is.

Therefore, the control device 150 supplies a current value higher than the current value 1004 until the mover 202 and the valve body 214 reach the maximum height position, so that the valve body 214 stably reaches the maximum height position. It becomes reachable, and the timing at which the valve body 214 reaches the maximum height position becomes earlier. When the control device 150 uses the drive current 1002, the behavior of the valve body 214 before reaching the maximum height position is stabilized, and the variation in the displacement amount of the valve body 214 for each shot is suppressed. Therefore, the shot variation of the injection amount after the injection pulse width 1103 when the valve body 214 reaches the maximum height position can be reduced.

On the other hand, since the mover 202 collides with the stator 207 at a high speed, the mover 202 bounces with the stator 207 or the valve body 214 as shown in the displacement period 1060 of the valve body 214 and the mover 202. There is a period. As a result, there is a problem that the shot variation of the injection amount is not reduced even after the injection pulse width 1103 shown in FIG. This problem is the same for the current waveform of the drive current shown in FIG. 4, and the condition that the control device 150 supplies the drive current of the high current waveform to the solenoid 205 before the valve body 214 reaches the maximum height position. In some cases, a similar problem occurred.

The relationship between the driving method and injection pulse width of the driving current 1001 and the injection amount and the shot variation of the injection amount according to the second embodiment of the present invention for solving the above problems will be described.
First, the control performed by the control device 150 to suppress the speed at which the mover 202 collides with the stator 207 will be described. The current control unit 542 supplies the solenoid 205 with a drive current 1001 having a predetermined injection pulse width. In the current control unit (current control unit 542), the mover (movable element 202) starts displacement toward the stator (stator 207), and the mover (movable element 202) accelerates to a predetermined value at the timing. The energization of the solenoid (solenoid 205) is turned off to reduce the speed at which the mover (movable element 202) collides with the stator (stator 207). For example, the current control unit 542 turns off the switching

elements

505, 506, and 507 _{at the timing t 106} (FIG. 10) when the mover 202 starts displacement in the direction of the stator 207 and the mover 202 sufficiently accelerates. ..

As a result, the back electromotive force due to the inductance of the fuel injection device 101 energizes the diode 509 and the diode 510, and the current is fed back to the booster circuit 514 (high voltage source) side. Then, the current supplied to the fuel injection device 101 rapidly decreases from the _{maximum drive current value I peak2 as shown in the current 1051 of FIG.} When the control device 150 applies a reverse voltage to the solenoid 205 to rapidly reduce the current, the magnetic flux generated in the magnetic circuit is reduced after a certain delay due to the eddy current, and the magnetic attraction acting on the mover 202 is reduced. The force becomes smaller.

_{After that, the mover 202 and the valve body 214 decelerate at the timing t 107} (see FIG. 10) shown in the displacement amount of the valve body 214 and the mover 202, and the speed when the mover 202 collides with the stator 207 becomes smaller. Become. Therefore, the bounces of the mover 202 and the valve body 214 generated with respect to the stator 207 are reduced, and the timing at which the bounces of the valve body 214 converge is earlier than _{the timing t 108.} As a result, the shot variation of the injection amount after the injection pulse width 1104 (see FIG. 11) after the valve body 214 reaches the maximum height position and a certain time has passed is smaller than that when the drive current 1002 is used. can do.

Further, if the current control unit 542 supplies the drive current 1001 to the fuel injection device 101, the speed at which the mover 202 collides with the stator 207 becomes smaller. Therefore, as compared with the case where the current control unit 542 supplies the drive current 1002 to the fuel injection device 101, there is also an effect that the drive noise generated from the fuel injection device 101 can be reduced.

When the control device 150 uses the drive current 1001 in this way, the mover 202 and the valve body 214 decelerate before the valve body 214 reaches the maximum height position. Therefore, the behavior of the valve body 214 may become unstable until the valve body 214 reaches the maximum height position. Further, under the condition that the injection pulse width Ti is smaller than the injection pulse width 1104, the shot variation of the injection amount may be larger than that when the drive current 1002 is used.

Therefore, an example of the control method according to the second embodiment of the present invention will be described with reference to FIG.
FIG. 12 is a diagram showing an injection pulse, a drive current, and an injection rate supplied from the ECU 104 to the fuel injection device 101 for each cylinder 108 in one combustion cycle. Also in FIG. 12, similarly to FIG. 6, the injection pulse, drive current, and injection rate of each fuel injection device 101 provided in the first to third cylinders are represented by a chain line, a solid line, and a broken line.

It is assumed that in one combustion cycle, in the injection performed before the last injection, the ECU 104 performed the injection 1201 with the same injection pulse width for each fuel injection device 101 of each cylinder 108. In this case, as shown in the injection rate 1203 of the first cylinder, the injection rate 1204 of the second cylinder, and the injection rate 1205 of the third cylinder, the injection rate fluctuates for each cylinder 108.

Therefore, the control device 150 according to the second embodiment of the present invention has a detection unit 541 that calculates the injection amount of each injection by fuel injection in one combustion cycle, and before the last injection in one combustion cycle. The current control unit 542 is provided to control so that the injection pulse width Ti of the last injection becomes smaller as the injection amount of the performed injection increases. In the final injection in one combustion cycle, the current control unit 542 performs injection 1202 in which the ECU 104 has an injection pulse width different for each fuel injection device 101 of each cylinder 108.

For example, when the current control unit 542 supplies the fuel injection device 101 with the injection pulse width in the injection 1201 performed before the end of one combustion cycle, the third cylinder corresponding to the injection rate 1205 having a large injection amount. The injection pulse of the last injection 1202 supplied to the fuel injection device 101 attached to the fuel injection device 101 is corrected to be as small as the injection pulse width 1206. On the other hand, the current control unit 542 largely corrects the injection pulse of the last injection 1202 supplied to the fuel injection device 101 attached to the first cylinder corresponding to the injection rate 1203 with a small injection amount, such as the injection pulse width 1208. .. The current control unit 542 sets the final injection supplied to the fuel injection device 101 attached to the second cylinder whose injection amount corresponds to the appropriate injection rate 1204 to the injection pulse width 1207 without correction.

Further, as shown in FIG. 10, the current control unit (current control unit 542) has a maximum drive current supplied to the solenoid (solenoid 205) by the injection performed before the last injection of one combustion cycle. After reaching, the solenoid (solenoid 205) is controlled to apply a reverse voltage. Then, in the final injection, the current control unit (current control unit 542) may supply a larger drive current to the solenoid (solenoid 205) up to the holding current than the first injection performed in one combustion cycle.

At this time, as shown in FIG. 12, in the injection 1201 (first injection) performed before the final injection 1202, the current control unit 542 has a fast injection pulse width Ti with a long shot variation. It is controlled by using the drive current 1001 of the fall waveform. After that, the current control unit 542 controls the final injection 1202 by using the drive current 1002 having a peak hold waveform with a small shot variation in the injection amount under the condition that the injection pulse width Ti is short. In this way, the current control unit 542 switches the

drive currents

1001 and 1002 in one combustion cycle according to the injection timing. By switching the

drive currents

1001 and 1002 by the current control unit 542 in this way, the effect of suppressing shot variation in the injection amount in one combustion cycle can be obtained.

Further, the current control unit 542 can suppress a decrease in the boost voltage VH by using a drive current 1001 having a small _{peak current value I peak} in the injection 1201 performed before the final injection 1202. Therefore, the boosted voltage VH easily returns to the initial value 1070 shown in FIG. 10 at the final injection 1202, so that the accuracy of the injection amount at the final injection 1202 can be improved and the variation in the injection amount during one combustion cycle can be suppressed. ..

[Third Embodiment] Next, an example of the control method of the fuel injection device according to the third embodiment of the present invention will be described with reference to FIGS. 5, 13 and 14. In the first and second embodiments described above, an example of a control method in the case of performing injection twice in one combustion cycle is shown, but in the third embodiment, three times in one combustion cycle. An example of a control method in the case of performing the above injection will be described.

FIG. 13 is a diagram showing an injection pulse, a drive current, and an injection rate supplied from the ECU 104 to the fuel injection device 101 for each cylinder 108 in one combustion cycle. In FIG. 13, as in FIG. 6, the injection pulse, drive current, and injection rate of each fuel injection device 101 provided in the first to third cylinders are represented by a chain line, a solid line, and a broken line.

The fuel injection device 101 according to the third embodiment injects fuel at a number of injections more than two times in one combustion cycle. In this case, as shown in the injection rate 1310 of the first cylinder, the injection rate 1311 of the second cylinder, and the injection rate 1312 of the third cylinder, the injection rate fluctuates for each cylinder 108.

Therefore, the control device 150 according to the third embodiment of the present invention is based on injection 1301 (referred to as "first injection") and injection 1302 (referred to as "second injection") performed before the end. The injection amount of the fuel injection device 101 of each cylinder 108 when each injection pulse is supplied to the fuel injection device 101 is calculated. For example, the detection unit 541 calculates the injection amount from the fuel injection period from the start of valve opening to the completion of valve closing of the valve body 214 and the pressure detected by the pressure sensor 109 attached to the fuel injection device 101. ..

Then, the current control unit (current control unit 542) causes the fuel injection device (fuel injection device 101) to inject three or more times in one combustion cycle, and a plurality of injections performed before the final injection. The injection amount of the last injection is corrected based on the sum of the injection amounts in. Here, the current control unit (current control unit 542) has an injection pulse so that the larger the sum of the injection amounts in the plurality of injections performed before the last injection, the smaller the injection amount in the last injection. Reduce the width Ti. For example, the current control unit 542 sets a small correction pulse width 1306 for the fuel injection device 101 of the third cylinder, which has a large sum calculated from the injection rate 1301 of the first injection and the injection rate 1302 of the second injection. Supply and have the final injection 1303 performed. On the other hand, the current control unit 542 applies a greatly corrected injection pulse width 1308 to the fuel injection device 101 of the first cylinder, which has a small sum calculated from the injection rate 1301 of the first injection and the injection rate 1302 of the second injection. Supply and have the final injection 1303 performed.

The current control unit 542 injects the fuel injection device 101 attached to the second cylinder in which the sum calculated from the injection rate 1301 of the first injection and the injection rate 1302 of the second injection is appropriate without correction. A pulse width of 1307 is supplied to perform the final injection 1303.

In this way, the current control unit 542 suppresses shot variation in the injection amount when the number of injections in one combustion cycle is more than two, and suppresses injection amount variation in the fuel injection device of each cylinder 108. As a result, the effect of suppressing combustion fluctuations is enhanced.

FIG. 14 is a diagram showing another example of the control method according to the third embodiment. FIG. 14 is a diagram showing an injection pulse, a drive current, and an injection rate supplied from the ECU 104 to the fuel injection device 101 for each cylinder 108 in one combustion cycle. In FIG. 14, as in FIG. 6, the injection pulse, drive current, and injection rate of each fuel injection device 101 provided in the first to third cylinders are represented by a chain line, a solid line, and a broken line.

FIG. 14 shows the state of two

injections

1401 and 1402 in the intake step 1420 and one injection 1403 in the compression step 1421 in one combustion cycle. Also in FIG. 14, the fuel injection device 101 injects more than two injections in one combustion cycle. In this case, as shown in the injection rate 1410 of the first cylinder, the injection rate 1411 of the second cylinder, and the injection rate 1412 of the third cylinder, the injection rate fluctuates for each cylinder 108. Then, the current control unit (current control unit 542) causes the fuel injection device (fuel injection device 101) to inject before the final injection in the intake step 1420 in one combustion cycle, and fuels in the compression step 1421. The injection device (fuel injection device 101) is made to perform the final injection.

The difference between the control method described with reference to FIG. 14 and the control method described with reference to FIG. 13 is that the injection pulse width Ti in the injection 1402 performed before the final injection 1403 is set in the final injection 1403. The point is to make it smaller than the injection pulse width Ti. Therefore, the current control unit (current control unit 542) is a fuel injection device (fuel injection device 101) in the injection performed immediately before the last injection among the plurality of injections performed before the last injection. ) Is made smaller than the injection pulse width Ti supplied to the fuel injection device (fuel injection device 101) at the final injection. Since the fuel injection with the injection pulse width Ti of the first injection 1401 in the intake step 1420 is performed at the timing when the air flow in the cylinder 108 is strong, the control device 150 controls so that the injection amount is large.

Then, the injection 1402 after the first injection 1401 (the latter half of the intake step 1420) is performed at the timing when the air flow in the cylinder 108 becomes weak. Therefore, the current control unit 542 sets the injection 1402 to the injection pulse width Ti shorter than the injection pulse width Ti in the first injection 1401 so that the fuel sprayed by the fuel injection device 101 can be appropriately placed on the weak air flow. Fuel is injected with a small injection amount. Such control makes it possible to improve the homogeneity of the fuel in the cylinder 108 in the intake step 1420.

In the control described with reference to FIG. 14, the control device 150 is set before the last injection, that is, the sum of the injection pulse width of the first injection 1401 and the injection pulse width of the second injection 1402. The injection pulse width of the final injection 1403 may be set to be small.
The control device 150 controls the injection amount of the injection 1402 performed before the injection amount of the last injection 1403 to be smaller, so that even if the injection amount of the last injection 1403 varies, the injection amount during one combustion cycle can be reached. The degree of contribution can be reduced. Therefore, it is possible to reduce the shot variation of the injection amount during one combustion cycle and suppress the combustion variation.

Further, in the control device 150 according to the third embodiment, the current control unit (current control unit 542) supplies a plurality of peak currents supplied to the solenoid (solenoid 205) at the last injection before the last injection. It is made larger than the peak current supplied to the solenoid (solenoid 205) by one injection. As shown in FIG. 14, the current control unit 542 sets the peak current supplied to the solenoid 205 by the third injection 1403 to be larger than the peak current supplied to the solenoid 205 by the first injection 1401 and the second injection 1402. .. Here, conversely, the current control unit 542 sets the peak current value of the current waveform corresponding to the injection pulse width in the second injection 1402 to the first injection 1401 and the third injection 1402. It is set lower than the peak current value of the current waveform corresponding to the injection pulse width in the injection 1403.

Then, the current control unit (current control unit 542) halves the valve body (valve body 214) by the injection performed immediately before the last injection among the plurality of injections performed before the last injection. It is operated by a lift, and the valve body (valve body 214) is operated by a full lift at the final injection. For example, the current control unit 542 operates in the second injection 1402 with a half lift in which the valve body 214 does not reach the maximum height position. In this way, the current control unit 542 reduces the injection pulse width in the second injection 1402 to reduce the peak current, thereby suppressing the magnetic attraction force acting on the mover 202. Then, the current control unit 542 stably controls the injection period when the valve body 214 is operated by the half lift.

[Fourth Embodiment] Next, an example of the control method of the fuel injection device according to the fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, an example of a control method in which the control unit retards the ignition timing will be described.

FIG. 15 is a diagram showing an injection pulse, an injection rate, and an ignition timing supplied from the ECU 104 to the fuel injection device 101 for each cylinder 108 in one combustion cycle. Similar to FIG. 12, in FIG. 15, the injection pulse and the injection rate of each fuel injection device 101 provided in the first to third cylinders are represented by a chain line, a solid line, and a broken line. Further, the ignition timing before the control according to the fourth embodiment is represented by a dotted line, and the ignition timing after the control according to the fourth embodiment is represented by a solid line.

FIG. 15 shows the state of two

injections

1501 and 1502 in the intake step 1520 and one injection 1503 in the compression step 1521 in one combustion cycle. Also in FIG. 15, the fuel injection device 101 injects more than two injections in one combustion cycle. In this case, as shown in the injection rate 1510 of the first cylinder, the injection rate 1511 of the second cylinder, and the injection rate 1512 of the third cylinder, the injection rate fluctuates for each cylinder 108.

Therefore, the control unit (control unit 500) causes the fuel injection device (fuel injection device 101) to inject three or more times in the intake step and the compression step of one combustion cycle, and sets the ignition timing to the top dead center in the combustion step 1522. It is retarded from (TDC). For example, at the time of starting the engine, under the condition of warming up the temperature of the three-way catalyst or the like, the control unit 500 causes the ignition timing to retard from the top dead center as shown in the

ignition timings

1530 and 1531. By retarding the ignition timing in this way, it is possible to intentionally increase the exhaust loss, increase the amount of heat supplied to the three-way catalyst, and perform control to improve the temperature of the three-way catalyst. By raising the temperature of the three-way catalyst, the purification efficiency of the three-way catalyst is improved, so that the amount of exhaust gas discharged from the vehicle can be suppressed.

However, under the condition of performing ignition retardation, the ignition timing is delayed from the optimum ignition timing, so that there is a problem that the combustion speed becomes slow and the combustion fluctuation in each combustion cycle becomes large. Since the time until the three-way catalyst is activated becomes shorter as the ignition timing is retarded, it is required to suppress the combustion fluctuation under the condition of retarding the ignition timing.

In the control method and control device 150 according to the fourth embodiment, the fuel of each cylinder to which the injection pulses having a predetermined injection pulse width are supplied in the

injections

1501 and 1502 performed before the final injection 1503, respectively. The injection amount of the injection device 101 is calculated from the injection period or pressure drop described in the first embodiment. Then, the control device 150 greatly corrects the injection pulse width of the last injection such as 1508 in the first cylinder having a small injection amount, and adjusts the injection pulse width of the last injection to 1506 in the third cylinder having a large injection amount. The current control unit 542 is provided so as to make a small correction.

Further, after the current control unit 542 corrects the injection pulse width from the start of the engine, the control unit controls to delay the ignition timing 1530 to the ignition timing 1531 as compared with before correcting the injection pulse width. .. By reducing the shot variation of the injection amount during one combustion cycle, the combustion fluctuation can be suppressed even if the ignition timing is delayed, and the temperature of the three-way catalyst can be improved.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various other application examples and modifications can be taken as long as the gist of the present invention described in the claims is not deviated.
For example, each of the above-described embodiments describes in detail and concretely the configurations of the apparatus and the system in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those including all the described configurations. Further, it is possible to replace a part of the configuration of the embodiment described here with the configuration of another embodiment, and further, it is possible to add the configuration of another embodiment to the configuration of one embodiment. It is possible. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.
In addition, the control lines and information lines indicate those that are considered necessary for explanation, and do not necessarily indicate all the control lines and information lines in the product. In practice, it can be considered that almost all configurations are interconnected.

1 ... Fuel injection system, 101 ... Fuel injection device, 103 ... Drive circuit, 104 ... ECU, 106 ... Fuel pump, 107 ... Combustion chamber, 108 ... Cylinder, 150 ... Control device, 202 ... Movable element, 207 ... Stator, 214 ... Valve body, 500 ... Control unit, 501 ... CPU, 502 ... Drive IC, 541 ... Detection unit, 542 ... Current control unit

Claims

In a control device that controls a fuel injection device that injects fuel a plurality of times in one combustion cycle, the fuel injection amount at each injection performed in the one combustion cycle is calculated, and the final injection in the one combustion cycle is performed. The larger the injection amount of the injection performed before the last injection than the injection amount, the wider the injection pulse width of the injection pulse supplied to the fuel injection device in the injection performed before the last injection. , A control device including a control unit that controls so as to reduce the injection pulse width of the injection pulse supplied to the fuel injection device at the final injection.
The fuel injection device is supplied with a valve body that seals fuel in contact with a valve seat, a mover that drives the valve body, a stator that sucks the mover by magnetic attraction, and a drive current. Then, the stator is provided with a solenoid that generates the magnetic attraction force in the stator so as to form a space for introducing fuel between the valve seat and the valve body.
The drive current includes a peak current that drives the mover and a hold current that switches within a range lower than the maximum value of the peak current in order to hold the mover in a state of being attracted to the solenoid.
The control unit makes the peak current supplied to the solenoid in the last injection larger than the peak current supplied to the solenoid in the injection performed before the last injection, and makes the last injection. The control device according to claim 1, wherein the valve body is operated with a full lift by injection.
The control unit
The injection amount is calculated based on the change in the fuel pressure of the fuel injection device, or the valve body of the fuel injection device is opened due to an electrical change caused by the collision of the mover with the stator. A detection unit that estimates the fuel injection period obtained from the start timing and the valve closing completion timing and calculates the injection amount based on the injection period.
The control device according to claim 2, further comprising a current control unit that supplies the injection pulse having a changed injection pulse width to the fuel injection device.
The current control unit reduces the injection pulse width supplied to the fuel injection device in the final injection as the injection amount of the injection performed before the last injection is larger than the appropriate injection amount. The third aspect of claim 3, wherein the injection amount of the injection performed before the last injection is smaller than the appropriate injection amount, the width of the injection pulse supplied to the fuel injection device at the last injection is increased. Control device.
In the current control unit, the mover starts displacement toward the stator, and when the mover accelerates to a predetermined value, the energization of the solenoid is turned off, and the mover moves the stator. The control device according to claim 3, which reduces the speed at which the vehicle collides with the vehicle.
The current control unit controls to apply a reverse voltage to the solenoid after the drive current supplied to the solenoid reaches a maximum value in the injection performed before the last injection. The control device according to claim 5, wherein in the final injection, the driving current is supplied to the solenoid so as to reach the holding current, which is larger than that of the first injection performed in the one combustion cycle.
The current control unit causes the fuel injection device to inject three or more times in the one combustion cycle, and based on the sum of the injection amounts in the plurality of injections performed before the last injection. The control device according to claim 3, wherein the injection amount of the last injection is corrected.
The current control unit claims to reduce the injection pulse width so that the larger the sum of the injection amounts in the plurality of injections performed before the last injection, the smaller the injection amount in the last injection. Item 7. The control device according to item 7.
The current control unit determines the injection pulse width to be supplied to the fuel injection device in the injection performed immediately before the last injection among the plurality of injections performed before the last injection. The control device according to claim 8, wherein the width of the injection pulse supplied to the fuel injection device at the final injection is smaller than the width of the injection pulse.
In the one combustion cycle, the current control unit causes the fuel injection device to inject before the last injection in the intake step, and causes the fuel injection device to perform the last injection in the compression step. Item 8. The control device according to item 8.
The eighth aspect of the present invention, wherein the current control unit increases the peak current supplied to the solenoid by the last injection to be larger than the peak current supplied to the solenoid by a plurality of injections performed before the last injection. Control device.
The current control unit operates the valve body with a half lift in the injection performed immediately before the last injection among the plurality of injections performed before the last injection, and the last injection. The control device according to claim 11, wherein the valve body is operated with a full lift.
The control device according to claim 2, wherein the control unit causes the fuel injection device to inject three or more times in the intake step and the compression step of the one combustion cycle, and retards the ignition timing from the top dead center in the combustion step. ..
In a control method for controlling a fuel injection device that injects fuel a plurality of times in one combustion cycle, a process of calculating the fuel injection amount at each injection performed in the one combustion cycle and a process of calculating the fuel injection amount at each injection.
The larger the injection amount of the injection performed before the last injection than the injection amount of the last injection in the one combustion cycle, the more the injection performed before the last injection is applied to the fuel injection device. A control method including a process of controlling the injection pulse width of the injection pulse supplied to the fuel injection device at the last injection to be smaller than the injection pulse width of the supplied injection pulse.
A computer that operates a control device that controls a fuel injection device that injects fuel multiple times in one combustion cycle.
The procedure for calculating the fuel injection amount at each injection performed in the one combustion cycle, and
The larger the injection amount of the injection performed before the last injection than the injection amount of the last injection in the one combustion cycle, the more the injection performed before the last injection is applied to the fuel injection device. A program for executing a procedure for controlling the injection pulse width of the injection pulse supplied to the fuel injection device at the last injection to be smaller than the injection pulse width of the supplied injection pulse.