JP6528405B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device provided with an in-cylinder injection fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine.

  Patent Document 1 discloses a fuel injection device provided with an in-cylinder injection fuel injection valve that directly injects fuel into a combustion chamber of an internal combustion engine. The fuel injection valve of this fuel injection device (hereinafter referred to as "conventional device") is a needle valve for opening and closing a nozzle (fuel injection hole), and is disposed to abut the rear end of the needle valve. Has a piston.

  Furthermore, a chamber (control chamber) for accommodating "fuel for applying pressure to move the needle valve in the direction to close the nozzle" is contained inside the fuel injection valve of the conventional device, and "direction to open the nozzle" A chamber (nozzle chamber) is formed which contains fuel for applying pressure to the needle valve to move the needle valve.

  The control chamber is connected to the common rail via the "fuel passage and branch passage" and to the tank (fuel tank) via the "fuel passage and return passage". On the other hand, the nozzle chamber is connected to the common rail via "fuel passage and branch passage".

  Furthermore, the fuel injection valve of the conventional device is provided with a three-way valve. The three-way valve can be positioned at one of “a position (a high pressure position) for allowing fuel from the common rail to flow into the control chamber” and “a position (a low pressure position) for allowing the fuel to flow out from the control chamber”.

  Since the high pressure fuel flows from the common rail into the control chamber when the three-way valve is positioned at the high pressure position, the needle valve has the nozzle (fuel injection hole) closed. On the other hand, since the high pressure fuel flows out from the control chamber when the three-way valve is positioned at the low pressure position, the needle valve is in the state of opening the nozzle. At this time, fuel is injected from the fuel injection valve.

  Furthermore, the conventional device is provided with a pressure reducing mechanism for reducing the pressure of fuel from the common rail supplied to the nozzle chamber. In the conventional device, when the three-way valve is positioned at the low pressure position to inject fuel from the fuel injection valve, the pressure reducing mechanism reduces the pressure of the fuel from the common rail supplied to the nozzle chamber. As a result, the moving speed of the needle valve is reduced, the fuel injection rate at the initial stage of fuel injection is reduced, and the amount of NOx (nitrogen oxide) generated in the combustion chamber is reduced.

Patent No. 3691168 (see paragraphs 0007 to 0019 and FIG. 1)

  The pressure reducing mechanism of the conventional device is composed of a pressure reducing chamber, a plunger for increasing and decreasing the volume of the pressure reducing chamber, and a solenoid for moving the plunger. Therefore, the volume of the decompression chamber can be changed by changing the amount of movement of the plunger by the solenoid. According to this, the moving speed of the needle valve at the initial stage of fuel injection can be variably controlled continuously, and as a result, the fuel injection rate at the initial stage of fuel injection can be variably controlled continuously.

  However, it is not easy to control the moving amount of the plunger to the target moving amount with high accuracy by the solenoid. Furthermore, since the fuel injection rate at the initial stage of fuel injection can be variably controlled continuously, the fuel injection rate at the initial stage of fuel injection can be controlled in multiple stages rather than the fuel injection device whose control accuracy is low. In some cases, a fuel injector with high accuracy may be preferable.

  The present invention has been made to address the problems described above. That is, one of the objects of the present invention is to provide a fuel injection system for an internal combustion engine capable of controlling the fuel injection rate at the initial stage of fuel injection in multiple stages with high accuracy.

The fuel injection device of the present invention (hereinafter referred to as "the present device") is as follows.
(1) In-cylinder injection fuel injection valve (100) for directly injecting fuel into the combustion chamber of an internal combustion engine
(2) a high pressure fuel source (41) for supplying high pressure fuel to the fuel injection valve;
(3) a control unit (70) for controlling the operation of the fuel injection valve;
Is equipped.

The fuel injection valve (100) is
(1) fuel injection holes (103) for injecting fuel;
(2) A needle portion (104) which can be positioned at any one of a valve closing position for closing the fuel injection hole and a valve opening position for opening the fuel injection hole;
(3) A control chamber for storing fuel for applying fuel pressure for positioning the needle portion at the valve-closing position to the needle portion, the first fuel supply having a fuel flow throttle portion (107) A control chamber (100c) connected to the high pressure fuel source via a passage (111) and to a fuel discharge (46) via a first fuel discharge passage (105, 108, 130, 121, 106 ) ;
(4) A nozzle chamber for containing fuel for applying fuel pressure for positioning the needle portion at the valve opening position to the needle portion, the second fuel supply passage (105, 112, 140, 113) Connected to the high pressure fuel source via the second fuel discharge passage (113, 140, 122, 141, 123, 106) and connected to the fuel discharge portion (46) and in communication with the fuel injection hole Nozzle chamber (100 n) ,
(5) A first low pressure position (see FIG. 3A ) for communicating the control chamber with the fuel discharge unit via the first fuel discharge passage, and the first fuel discharge passage via the first fuel discharge passage A two-way valve (131) which can be positioned at any one of a first high pressure position (see FIG. 3B) which shuts off the communication between the control chamber and the fuel discharge portion;
(6) A second low pressure for connecting the nozzle chamber to the fuel discharge unit via the second fuel discharge passage and blocking communication between the nozzle chamber and the high-pressure fuel source via the second fuel supply passage Position (see FIG. 3A), and the nozzle chamber and the fuel via the second fuel discharge passage while communicating the nozzle chamber with the high pressure fuel source via the second fuel supply passage. A three-way valve (144) that can be positioned at either one of a second high pressure position (see FIG. 3B) that shuts off communication with the discharge part;
Is equipped.

The fuel pressure in the control chamber (100c) is controlled by the two-way valve (131) regardless of whether the three-way valve (144) is positioned at the second low-pressure position or the second high-pressure position. When the valve is positioned at the first high pressure position, the pressure is higher than when the two-way valve is positioned at the first low pressure position.
On the other hand, the fuel pressure in the nozzle chamber (100n) is the three-way valve (130) regardless of whether the two-way valve (131) is positioned at the first low pressure position or the first high pressure position. When 144) is positioned at the second high pressure position, the pressure is higher than when the three-way valve is positioned at the second low pressure position.
The needle portion (104) is configured to be positioned at the valve opening position when the difference between the fuel pressure in the control chamber and the fuel pressure in the nozzle chamber is equal to or greater than a predetermined value.

The control unit (70)
(1) In a state where the two-way valve and the three-way valve are respectively positioned at the first high pressure position and the second low pressure position (see FIG. 5A) , the two-way valve is at the first low pressure The first valve opening control (medium-speed opening ) in which the needle portion is positioned at the valve opening position by moving the three-way valve to the second high pressure position while moving it to the second position (see FIG. 5B). Valve control),
(2) In a state where the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second low pressure position (see FIG. 7A) , the two-way valve is at the first low pressure Second valve opening control (high-speed valve opening ) in which the needle portion is positioned at the valve opening position by moving the three-way valve to the second high pressure position (see FIG. 7B) while maintaining the position . Control), and
(3) In a state where the two-way valve and the three-way valve are respectively positioned at the first high pressure position and the second high pressure position (see FIG. 9A) , the three-way valve is at the second high pressure position Third valve opening control (low-speed valve opening ) in which the needle portion is positioned at the valve opening position by moving the two-way valve to the first low pressure position (see FIG. 9B) while maintaining control),
The fuel injection hole is configured to inject fuel by selectively performing any one of the above.

  In the fuel injection valve of the device according to the present invention, the needle portion moves from the valve closing position toward the valve opening position when "the difference (differential pressure) in the fuel pressure in the nozzle chamber to the fuel pressure in the control chamber" (Open the valve, start lifting). At this time, a period from when "the fuel injection rate representing the amount of fuel injected from the fuel injection holes per unit time" starts to increase until it reaches the maximum injection rate (hereinafter referred to as "fuel injection initial stage"). The increasing speed of the differential pressure at each of the first and second valve opening control (medium-speed valve opening control), the second valve opening control (high-speed valve opening control) and the third valve opening control (low-speed valve opening control) It is different.

  Therefore, also for the average value of the fuel injection rate at the initial stage of fuel injection, the first valve opening control (medium speed valve opening control), the second valve opening control (high speed valve opening control) and the third valve opening control (low speed) They differ in the valve opening control).

  As described above, the fuel injection rate at the initial stage of fuel injection not only affects the "amount of NOx generated in the combustion chamber", but also "the amount of sound generated due to the combustion of fuel in the combustion chamber" It also affects the level and the amount of unburned hydrocarbons (soot, smoke) generated in the combustion chamber.

  According to the device of the present invention, at least three values of the average value of the fuel injection rate at the initial stage of fuel injection can be obtained by appropriately selecting the operation patterns of the "two-way valve and three-way valve" when injecting fuel from the fuel injection valve. You can choose one of the two. Then, positioning the two-way valve at the first valve closing position or the first valve opening position and positioning the three-way valve at the second valve closing position or the second valve opening position corresponds to the amount of movement of the plunger as in the conventional device. It is extremely easy compared to controlling to the target movement amount.

Therefore, according to the device of the present invention, the fuel injection rate at the initial stage of fuel injection can be controlled in multiple stages with high accuracy.
In the device of the present invention, when the two-way valve (131) is positioned at the first low pressure position (see (A) in FIG. 3), the two-way valve (131) opens the first fuel discharge passage. The control chamber may be configured to communicate with the fuel discharge unit via the first fuel discharge passage.
In this case, when the two-way valve (131) is positioned at the first high pressure position (see (B) in FIG. 3), the first fuel discharge passage is blocked, thereby the first fuel The communication between the control chamber and the fuel discharger via the discharge passage may be shut off.
Furthermore, in this case, when the three-way valve (144) is positioned at the second low pressure position (see FIG. 3A), the second fuel supply passage is blocked and the second fuel discharge is performed. By opening the passage, the nozzle chamber is communicated with the fuel discharge unit through the second fuel discharge passage, and the communication between the nozzle chamber and the high-pressure fuel source is blocked through the second fuel supply passage. Can be configured to
Furthermore, in this case, when the three-way valve (144) is positioned at the second high pressure position (see FIG. 3B), the second fuel supply passage is opened and the second fuel discharge is performed. By blocking the passage, the nozzle chamber is communicated with the high-pressure fuel source via the second fuel supply passage, and the communication between the nozzle chamber and the fuel discharge portion via the second fuel discharge passage is blocked. Can be configured to
Furthermore, in the device of the present invention, the control unit (70)
(4) When the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second high pressure position (see FIG. 11A), the two-way valve is 1) The first valve closing control (in which the needle portion is positioned at the valve closing position by moving the three-way valve to the second low pressure position while maintaining the low pressure position (see FIG. 11B) Fast closing control),
(5) When the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second high pressure position (see FIG. 13A), the two-way valve is 1) The second valve closing control (high speed positioning) in which the needle portion is positioned at the valve closing position by moving the three-way valve to the second low pressure position while moving to the high pressure position (see FIG. 13B). Valve closing control), and
(6) When the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second high pressure position (see FIG. 15A), the three-way valve may be the second Third valve closing control (low speed) for positioning the needle portion at the valve closing position by moving the two-way valve to the first high pressure position while maintaining the high pressure position (see FIG. 15B) Valve closing control),
The fuel injection from the fuel injection hole may be stopped by selectively performing any one of the above.

FIG. 1 is an overall view of an internal combustion engine to which a fuel injection device (main injection device) according to an embodiment of the present invention is applied. FIG. 2 is a longitudinal sectional view of the fuel injection valve shown in FIG. (A) and (B) of FIG. 3 are respectively the same as FIG. 2, and (A) is a two-way valve and a three-way valve positioned at the first low pressure position and the second low pressure position, respectively. (B) shows the fuel injection valve when the two-way valve and the three-way valve are respectively positioned at the first high pressure position and the second high pressure position. FIG. 4 is a time chart showing changes in control room pressure and the like when the present injection device performs medium-speed valve opening control. (A) and (B) of FIG. 5 are respectively the same as FIG. 2, and (A) shows the fuel injection valve in the closed state, and (B) shows the medium speed valve opening control. The fuel injection valve in the opened state is shown. FIG. 6 is a time chart showing changes in control room pressure and the like when the present injection device performs high-speed valve closing control. (A) and (B) of FIG. 7 are respectively the same as FIG. 2, and (A) shows a fuel injection valve in a closed state, and (B) is opened by high-speed valve opening control. The fuel injection valve in the valved state is shown. FIG. 8 is a time chart showing changes in control room pressure and the like when the present injection device performs low speed valve opening control. (A) and (B) of FIG. 9 are respectively the same as FIG. 2, and (A) shows the fuel injection valve in the closed state, and (B) is opened by the low speed valve opening control. The fuel injection valve in the valved state is shown. FIG. 10 is a time chart showing changes in control room pressure and the like when the present injection device performs medium-speed valve closing control. (A) and (B) of FIG. 11 are respectively the same as FIG. 2, and (A) shows the fuel injection valve in the open state, and (B) shows the medium speed valve closing control. The fuel injection valve in the closed state is shown. FIG. 12 is a time chart showing changes in control room pressure and the like when the present injection device performs high-speed valve closing control. (A) and (B) of FIG. 13 are respectively the same as FIG. 2, and (A) shows the fuel injection valve in the opened state, and (B) is closed by high-speed valve closing control. The fuel injection valve in the valved state is shown. FIG. 14 is a time chart showing changes in control room pressure and the like when the present injection device performs low speed valve closing control. (A) and (B) of FIG. 15 are respectively the same as FIG. 2, and (A) shows the fuel injection valve in the opened state, and (B) is closed by low speed valve closing control. The fuel injection valve in the valved state is shown.

  Hereinafter, a “fuel injection device for an internal combustion engine (hereinafter, referred to as“ main injection device ”)” according to an embodiment of the present invention will be described with reference to the drawings.

  The present injection device is applied to an internal combustion engine (hereinafter referred to as "engine") 10 shown in FIG. The engine 10 is a reciprocating piston type, in-cylinder injection (direct injection), compression self-ignition type, multi-cylinder (in this example, four cylinders), diesel engine. The engine 10 includes a cylinder block 20 and a cylinder head 30.

  The cylinder block 20 includes a cylinder 21 and a piston 22. The piston 22 reciprocates in the cylinder 21. The cylinder 21, the piston 22 and the cylinder head 30 form a combustion chamber 23. The engine 10 has four combustion chambers. Hereinafter, the configuration of the engine 10 will be described in relation to one of the combustion chambers 23, and the configuration of the remaining three combustion chambers is the same as the configuration of the combustion chamber 23 described below.

  The cylinder head 30 includes an intake port 31 in communication with the combustion chamber 23, an intake valve 32 for opening and closing the intake port 31, an exhaust port 33 in communication with the combustion chamber 23, and an exhaust valve 34 for opening and closing the exhaust port 33. .

  The fuel injection valve 100 is disposed on the cylinder head 30 such that the central axis C100 thereof coincides with the central axis C23 of the combustion chamber 23. Furthermore, the fuel injection valve 100 is disposed in the cylinder head 30 so that the fuel injection hole is exposed in the combustion chamber 23. Therefore, the fuel injection valve 100 directly injects the fuel into the combustion chamber 23.

  The ECU (Electronic Control Unit) 70 is an electronic circuit including a known microcomputer, and includes a CPU, a ROM, a RAM, a backup RAM, an interface, and the like. As shown in FIG. 2, the ECU 70 is connected to the fuel pressure sensor 45, and receives (inputs) a signal from the fuel pressure sensor 45. Further, the ECU 70 is connected to the “solenoid 134 and an actuator (not shown)” of the fuel injection valve 100 and the “fuel pump 44”, and instructs (drives) these “solenoid 134 and actuator” and the “fuel pump 44”. It is supposed to be sent out.

  The fuel injection valve 100 includes a main body portion 101 and a nozzle portion 102. A plurality of (four in this example) fuel injection holes 103 are formed at the tip of the nozzle portion 102.

  A space extending along the central axis C100 of the fuel injection valve 100 is formed inside the nozzle portion 102, and a needle valve 104n is accommodated in this space. The needle valve 104 n is movable along the central axis C 100 in this space. The fuel injection valve 100 moves the needle valve 104 n to close the fuel injection hole 103 (hereinafter referred to as “valve closing position”) and opens the fuel injection hole 103 (hereinafter referred to as “the valve closing position”). The needle valve 104n can be positioned at any one of the following positions (open position).

  Hereinafter, the direction in which the needle valve 104n moves toward the valve closing position along the central axis C100 is referred to as "valve closing direction", and the direction in which the needle valve 104n moves toward the valve opening position along the central axis C100. Is referred to as "opening direction". Furthermore, in various members described below, the end on the "valve-closing direction" side is referred to as the "rear end", and the end on the "valve-opening direction" side is referred to as the "tip".

  A space extending along the central axis C100 is also formed inside the main body portion 101, and the piston portion 104p is accommodated in this space. The piston portion 104p is movable along the central axis C100 in this space. Further, the piston portion 104p is disposed so as to abut on the rear end of the needle valve 104n at its front end.

  Hereinafter, the needle valve 104 n and the piston portion 104 p will be collectively referred to as a “needle portion 104”.

  A fuel inlet passage 105 is formed in the main body portion 101. The passage 105 is connected to a common rail (high pressure fuel source) 41 via a fuel supply pipe 40. The common rail 41 is connected to the fuel tank 43 via the fuel supply pipe 42. A fuel pump 44 is disposed in the fuel supply pipe 42. The fuel pump 44 is connected to the ECU 70, and controls the flow rate of the discharged fuel in response to an instruction signal from the ECU 70.

  The fuel pump 44 pumps the fuel in the fuel tank 43 to the common rail 41. Therefore, high pressure fuel is stored in the common rail 41. The high-pressure fuel is supplied to the fuel injection valve 100 via the “fuel supply pipe 40 and the fuel inlet passage 105”.

  The common rail 41 is provided with a fuel pressure sensor 45 for detecting the pressure of the fuel stored therein. As described above, the fuel pressure sensor 45 is connected to the ECU 70, detects the pressure of the fuel stored in the common rail 41, and indicates the pressure (hereinafter referred to as "common rail pressure") Pcmn. Is input to the ECU 70.

  The ECU 70 obtains the common rail pressure Pcmn based on the signal representing the common rail pressure Pcmn. Further, the ECU 70 sends an instruction signal to the fuel pump 44 such that the common rail pressure Pcmn is maintained at a predetermined pressure.

  Further, a fuel outlet passage 106 is formed in the main body portion 101. The passage 106 is connected to the fuel tank 43 via a fuel return pipe 46. The fuel flowing out of the fuel injection valve 100 through the passage 106 is returned to the fuel tank 43 through the fuel return pipe 46.

  The fuel inlet passage 105 is connected to a first fuel supply passage 111 formed in the main body portion 101. An orifice (a fuel flow throttle portion) 107 is formed in the passage 111. Furthermore, the first fuel supply passage 111 is connected to a control chamber 100 c formed in the main body portion 101. The control chamber 100 c is formed by the rear end surface of the piston portion 104 p and the inner wall surface of the main body portion 101.

  The fuel in the common rail 41 is supplied to the control chamber 100c via the "fuel supply pipe 40, the fuel inlet passage 105, and the first fuel supply passage 111".

  Furthermore, the control chamber 100 c is connected to a two-way valve chamber 130 formed in the main body portion 101 via an orifice (flow rate reduction portion) 108. The fuel flow throttling effect of the orifice 108 is smaller than the fuel flow throttling effect of the orifice 107 formed in the first fuel supply passage 111.

  A two-way valve 131 is disposed in the two-way valve chamber 130. The two-way valve 131 is between a position at which the outlet of the orifice 108 is opened as shown in FIG. 3A and a position at which the outlet of the orifice 108 is closed as shown in FIG. Are disposed movably along the central axis C100.

  Furthermore, as shown in FIG. 2, an armature member 132 is attached to the rear end of the two-way valve 131. A compression coil spring 133 is disposed on the rear end surface of the armature member 132. The compression coil spring 133 biases the two-way valve 131 in the valve closing direction via the armature member 132.

  A solenoid 134 is disposed proximate to the armature member 132. As described above, the solenoid 134 is connected to the ECU 70, and the ECU 70 sends an instruction signal for supplying power to the solenoid 134.

  When power is supplied to the solenoid 134 in response to an instruction signal from the ECU 70, the solenoid 134 pulls the armature member 132 in the valve opening direction against the biasing force of the compression coil spring 133. As a result, the two-way valve 131 moves in the valve opening direction, and as shown in FIG. 3A, positioning is performed at a position where the outlet of the orifice 108 is opened (hereinafter referred to as "first low pressure position"). Be done.

  On the other hand, when the power supply to the solenoid 134 is stopped, the biasing force of the compression coil spring 133 moves the armature member 132 in the valve closing direction. As a result, the two-way valve 131 moves in the valve closing direction, and as shown in FIG. 3B, positioning is performed at a position where the outlet of the orifice 108 is closed (hereinafter referred to as "first high pressure position"). Be done.

  When the two-way valve 131 is positioned at the "first high pressure position", no fuel flow from the control chamber 100c to the two-way valve chamber 130 occurs. Therefore, when the two-way valve 131 is positioned at the "first high pressure position" for a predetermined time or more, the pressure of fuel in the control chamber 100c (hereinafter referred to as "control chamber pressure") Pctl is A high pressure (hereinafter referred to as "high pressure") Phigh equal to the common rail pressure Pcmn.

  On the other hand, when the two-way valve 131 is positioned at the "first low pressure position", the fuel flows out of the control chamber 100c into the two-way valve chamber 130. As described above, the fuel flow throttling effect of the orifice 108 is smaller than the fuel flow throttling effect of the orifice 107 formed in the first fuel supply passage 111. Therefore, the flow rate of the fuel flowing out of the control chamber 100 c through the orifice 108 is larger than the flow rate of the fuel flowing into the control chamber 100 c through the orifice 107. Therefore, when the two-way valve 131 is positioned at the “first low pressure position” for a predetermined time or more, the control room pressure Pctl is a pressure lower than the common rail pressure Pcmn (hereinafter referred to as “low pressure”). ) It is Plow.

  As shown in FIG. 2, the two-way valve chamber 130 is in communication with the fuel outlet passage 106 via the first fuel discharge passage 121 formed in the main body portion 101.

  Further, the fuel inlet passage 105 is connected to a second fuel supply passage 112 formed in the main body portion 101. The passage 112 is connected to a three-way valve chamber 140 formed in the main body portion 101.

  The three-way valve chamber 140 is connected to a spring chamber 141 formed in the main body portion 101 via a second fuel discharge passage 122. A compression coil spring 142 is disposed in the spring chamber 141. The spring 142 biases the needle valve 104 n in the valve closing direction via the ring member 143.

  The spring chamber 141 is in communication with the fuel outlet passage 106 via the third fuel discharge passage 123 formed in the main body portion 101.

  Further, the three-way valve chamber 140 is in communication with the nozzle chamber 100 n formed in the nozzle portion 102 via the third fuel supply passage 113. The nozzle chamber 100 n is formed by the outer peripheral wall surface of the needle valve 104 n and the inner wall surface of the nozzle portion 102.

  In the present embodiment, “the fuel inlet passage 105, the first fuel supply passage 111, the second fuel supply passage 112, the third fuel supply passage 113, the fuel outlet passage 106, the first fuel discharge passage 121, and the second fuel discharge passage The channel areas of 122 "are respectively equal to one another.

  The nozzle chamber 100 n is connected to the fuel injection hole 103 via the fourth fuel supply passage 114. The fourth fuel supply passage 114 is formed by the outer peripheral wall surface of the needle valve 104 n and the inner wall surface of the nozzle portion 102.

  When the needle valve 104n is positioned at the valve closing position, the communication between the nozzle chamber 100n and the fuel injection hole 103 via the fourth fuel supply passage 114 is shut off. On the other hand, when the needle valve 104 n is positioned at the valve opening position, the nozzle chamber 100 n and the fuel injection hole 103 communicate with each other through the fourth fuel supply passage 114. In this case, the fuel in the nozzle chamber 100 n is injected from the fuel injection hole 103.

  A three-way valve 144 is disposed in the three-way valve chamber 140. The three-way valve 144 closes the second fuel supply passage 112 as shown in FIG. 3A and opens the second fuel discharge passage 122, and as shown in FIG. 3B. A position for opening the second fuel supply passage 112 and closing the second fuel discharge passage 122 is movably disposed.

  In response to an instruction signal from the ECU 70, the three-way valve 144 “will close the second fuel supply passage 112 and open the second fuel discharge passage 122 by an actuator (not shown) (hereinafter referred to as“ second low pressure position ” The fuel flows out of the three-way valve chamber 140 into the spring chamber 141 via the second fuel discharge passage 122.

  Therefore, when the three-way valve 144 is positioned at the second low pressure position for a predetermined time or more, the fuel pressure in the three-way valve chamber 140 is a pressure (low pressure) Plow lower than the common rail pressure Pcmn. As a result, the pressure of fuel in the nozzle chamber 100n (hereinafter referred to as "the pressure in the nozzle chamber") Pnzl is also a low pressure Plow.

  On the other hand, in response to an instruction signal from the ECU 70, the three-way valve 144 “opens the second fuel supply passage 112 and closes the second fuel discharge passage 122 by an actuator (not shown) (hereinafter referred to as“ second high pressure position ” The fuel in the common rail 41 via the “fuel supply pipe 40, the fuel inlet passage 105, the second fuel supply passage 112, the three-way valve chamber 140 and the third fuel supply passage 113”. Flows into the nozzle chamber 100n.

  Therefore, when the three-way valve 144 is positioned at the second high pressure position for a predetermined time or more, the nozzle chamber pressure Pnzl is a high pressure Phigh equal to the common rail pressure Pcmn.

(Specific valve opening control of this injection device)
Next, specific valve opening control of the present injection device will be described. The present injection device performs “high-speed valve opening control”, “medium-speed valve opening control”, and “low-speed valve opening control” as valve opening control for opening (lifting) the needle portion 104 to inject fuel from the fuel injection valve 100. "Open valve control" selectively.

  In this example, the valve opening speed of the needle portion 104 when the needle portion 104 is opened by the high-speed valve opening control is the largest speed (hereinafter referred to as "maximum valve opening speed"). On the other hand, when the needle portion 104 is opened by the low speed valve opening control, the valve opening speed of the needle portion 104 is the smallest speed (hereinafter referred to as "minimum valve opening speed"). Further, the valve opening speed of the needle portion 104 when the needle portion 104 is opened by the medium speed valve opening control is a speed between the maximum valve opening speed and the minimum valve opening speed.

(Medium speed valve opening control)
First, medium speed valve opening control will be described with reference to FIGS. 4 and 5. In the example shown in FIG. 4, the present injection device starts the valve opening control of the fuel injection valve 100 at time t0. Therefore, before time t0, the fuel injection valve 100 is closed.

  When the fuel injection valve 100 is opened by medium speed valve opening control, as shown in (A) of FIG. 5, the present injection device is operated before time t0 (before the start of medium speed valve opening control). The directional valve 131 is positioned at a position (first high pressure position) where the outlet of the orifice 108 is closed. On the other hand, at this time, the present injection device positions the three-way valve 144 at a position (second low pressure position) where the second fuel supply passage 112 is closed and the second fuel discharge passage 122 is opened. Therefore, before time t0, as shown in FIG. 4, the control chamber pressure Pctl is a pressure (high pressure) Phigh equal to the common rail pressure Pcmn, and the nozzle chamber pressure Pnzl is a low pressure Plow.

  At this time, the differential pressure ΔP (= Pnzl−Pctl) between the control chamber pressure Pctl and the nozzle chamber pressure Pnzl is smaller than “0” (the control chamber pressure Pctl is higher than the nozzle chamber pressure Pnzl). Therefore, the needle portion 104 is positioned at the valve closing position (the fuel injection valve 100 is closed).

  At time t0, the present injection device moves the two-way valve 131 to the first low pressure position and moves the three-way valve 144 to the second high pressure position, as shown in FIG. 5B. As a result, as shown in FIG. 4, the control chamber pressure Pct1 decreases from the high pressure Phigh to the low pressure Plow, and the nozzle chamber pressure Pnzl increases from the low pressure Plow to the high pressure Phigh. At this time, the speed at which the control chamber pressure Pctl decreases toward the low pressure Plow is smaller than the speed at which the nozzle chamber pressure Pnzl increases toward the high pressure Phigh.

  Differential pressure ΔP gradually increases after time t0, and reaches a pressure (hereinafter referred to as “opening start differential pressure”) ΔPop_th that overcomes the biasing force of compression coil spring 142 at time t1.

  When the differential pressure ΔP reaches the valve opening start differential pressure ΔPop_th, the needle portion 104 starts to move (open, lift) in the valve opening direction. Therefore, the distance (hereinafter, referred to as “needle lift amount”) Lndl that the needle portion 104 has moved from the valve closing position starts to increase. Thereafter, the needle lift amount Lndl gradually increases, and reaches a predetermined lift amount Lndl_th at time t2.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to increase. Thus, fuel injection from the fuel injection valve 100 is started.

  Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually increase, and the fuel injection rate FIR reaches the maximum injection rate FIRmax at time t3. Thereafter, the needle lift amount Lndl reaches the maximum lift amount Lndl_max. Thereafter, at time t4, the control chamber pressure Pctl reaches the low pressure Plow, and as a result, the differential pressure ΔP reaches the maximum differential pressure ΔPmax.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” when the fuel injection valve 100 is opened by the medium-speed valve opening control.

(High-speed valve opening control)
Next, high-speed valve opening control will be described with reference to FIGS. 6 and 7. In FIG. 6, solid lines indicate "changes in the positions of the two-way valve 131 and the three-way valve 144" and "changes in the control chamber pressure Pctl etc." when the fuel injection valve 100 is opened by high-speed valve opening control. . On the other hand, the chain line indicates “change in the position of the two-way valve 131 and the three-way valve 144” and “change in the control chamber pressure Pctl” when the fuel injection valve 100 is opened by the medium speed valve opening control described above. It shows.

  Also in the example shown in FIG. 6, the present injection device starts the valve opening control of the fuel injection valve 100 at time t0. Therefore, before time t0, the fuel injection valve 100 is closed.

  When the fuel injection valve 100 is opened by high-speed valve opening control, as shown in FIG. 7A, the present injection device is a two-way valve before time t0 (before the start of high-speed valve opening control). The 131 and the three-way valve 144 are positioned at the first low pressure position and the second low pressure position, respectively. Therefore, as shown in FIG. 6, both the control chamber pressure Pctl and the nozzle chamber pressure Pnzl are at the low pressure Plow. At this time, the differential pressure ΔP is “0”. Therefore, the needle portion 104 is positioned at the valve closing position by the biasing force of the compression coil spring 142 (the fuel injection valve 100 is closed).

  At time t0, the present injection device moves the three-way valve 144 to the second high pressure position with the two-way valve 131 maintained at the first low pressure position, as shown in FIG. 7B. As a result, as shown in FIG. 6, with the control chamber pressure Pct1 maintained at the low pressure Plow, the nozzle chamber pressure Pnzl rises from the low pressure Plow toward the high pressure Phigh.

  Differential pressure ΔP gradually increases after time t0, and reaches valve opening differential pressure ΔPop_th at a time earlier than “time t1 when differential pressure ΔP reaches valve opening differential pressure ΔPop_th in medium-speed valve opening control”. .

  When the differential pressure ΔP reaches the valve opening start differential pressure ΔPop_th, the needle portion 104 starts to move (open, lift) in the valve opening direction. Therefore, the needle lift amount Lndl starts to increase. Thereafter, the needle lift amount Lndl gradually increases, and reaches the predetermined lift amount Lndl_th at a time earlier than the time t2 at which the needle lift amount Lndl reaches the predetermined lift amount Lndl_th in the medium-speed valve opening control.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to increase. Thus, fuel injection from the fuel injection valve 100 is started.

  Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually increase, and the fuel injection rate FIR is earlier than "the time t3 when the fuel injection rate FIR reaches the maximum injection rate FIRmax in the medium speed valve opening control". , Reaches the maximum injection rate FIRmax. Thereafter, the needle lift amount Lndl reaches the maximum lift amount Lndl_max.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” in the case where the fuel injection valve 100 is opened by high-speed valve opening control.

  As described above, in the medium speed valve opening control, the fuel in the control chamber 100c is moved by moving the two-way valve 131 to the first low pressure position and moving the three-way valve 144 to the second high pressure position. The fuel from the common rail 41 is supplied into the nozzle chamber 100n while being discharged to the valve chamber 130. As a result, the pressure in the control chamber Pctl is reduced and the pressure in the nozzle chamber Pnzl is increased, whereby the differential pressure ΔP is increased, and the needle portion 104 is opened (lifted).

  On the other hand, in the high-speed valve opening control, the two-way valve 131 is already positioned at the first low pressure position before the start of the valve opening control. Then, when the valve opening control is started, the fuel supplied from the common rail 41 to the fuel injection valve 100 by moving the three-way valve 144 to the second high pressure position while maintaining the two-way valve 131 at the first low pressure position. Are supplied to the nozzle chamber 100 n through the “fuel inlet passage 105, the second fuel supply passage 112, the three-way valve chamber 140 and the third fuel supply passage 113”. As a result, the pressure in the nozzle chamber Pnzl is increased while maintaining the control chamber pressure Pctl at the low pressure Plow, thereby increasing the differential pressure ΔP, and the needle portion 104 is opened (lifted).

  By controlling the two-way valve 131 and the three-way valve 144 in this manner, the fuel injection rate FIR in the period Top_high (see FIG. 6) from when the fuel injection rate FIR starts increasing and reaches the maximum injection rate FIRmax. Making the average value larger than the average value of the fuel injection rate FIR in the period Top_mid (see FIG. 4) from when the fuel injection rate FIR starts to increase to the maximum value Lndl_max in the medium speed valve opening control it can.

(Low speed valve opening control)
Next, low speed valve opening control will be described with reference to FIGS. 8 and 9. In FIG. 8, solid lines indicate “change in position of two-way valve 131 and three-way valve 144” and “change in control chamber pressure Pctl” when the fuel injection valve 100 is opened by low-speed valve opening control. . On the other hand, the chain line indicates “change in the position of the two-way valve 131 and the three-way valve 144” and “change in the control chamber pressure Pctl” in the case of opening the fuel injection valve 100 by the medium speed valve opening control described above. It shows.

  Also in the example shown in FIG. 8, the present injection device starts the valve opening control of the fuel injection valve 100 at time t0. Therefore, before time t0, the fuel injection valve 100 is closed.

  When the fuel injection valve 100 is opened by the low speed valve opening control, as shown in FIG. 9A, the present injection device is a two-way valve before time t0 (before the start of the low speed valve opening control). The 131 and the three-way valve 144 are positioned at the first high pressure position and the second high pressure position, respectively. Therefore, as shown in FIG. 8, both the control chamber pressure Pctl and the nozzle chamber pressure Pnzl are high pressure Phigh. At this time, the differential pressure ΔP is “0”. Therefore, the needle portion 104 is positioned at the valve closing position by the biasing force of the compression coil spring 142 (the fuel injection valve 100 is closed).

  At time t0, the present injection device moves the two-way valve 131 to the first low pressure position with the three-way valve 144 maintained at the second high pressure position, as shown in FIG. 9B. As a result, as shown in FIG. 8, the control chamber pressure Pct1 decreases from the high pressure Phigh toward the low pressure Plow while the pressure in the nozzle chamber Pnzl is maintained at the high pressure Phigh.

  Differential pressure ΔP gradually increases after time t0, and reaches valve opening differential pressure ΔPop_th at a time earlier than “time t1 when differential pressure ΔP reaches valve opening differential pressure ΔPop_th in medium-speed valve opening control”. .

  When the differential pressure ΔP reaches the valve opening start differential pressure ΔPop_th, the needle portion 104 starts to move (open, lift) in the valve opening direction. Therefore, the needle lift amount Lndl starts to increase. Thereafter, the needle lift amount Lndl gradually increases, and reaches the predetermined lift amount Lndl_th at a time earlier than the time t2 at which the needle lift amount Lndl reaches the predetermined lift amount Lndl_th in the medium-speed valve opening control.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to increase. Thus, fuel injection from the fuel injection valve 100 is started.

  Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually increase, and the fuel injection rate FIR is earlier than "the time t3 when the fuel injection rate FIR reaches the maximum injection rate FIRmax in the medium speed valve opening control". , Reaches the maximum injection rate FIRmax. Thereafter, the needle lift amount Lndl reaches the maximum lift amount Lndl_max.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” in the case where the fuel injection valve 100 is opened by the low speed valve opening control.

  As described above, in the medium speed valve opening control, the fuel in the control chamber 100c is moved by moving the two-way valve 131 to the first low pressure position and moving the three-way valve 144 to the second high pressure position. The fuel from the common rail 41 is supplied into the nozzle chamber 100n while being discharged to the valve chamber 130. As a result, the pressure in the control chamber Pctl is reduced and the pressure in the nozzle chamber Pnzl is increased, whereby the differential pressure ΔP is increased, and the needle portion 104 is opened (lifted).

  On the other hand, in the low speed valve opening control, the three-way valve 144 is already positioned at the second high pressure position before the start of the valve opening control. Then, when the valve opening control is started, the two-way valve 131 is moved to the first low pressure position while maintaining the three-way valve 144 at the second high pressure position, whereby the fuel in the control chamber 100c is transmitted through the orifice 108 It is discharged to the two-way valve chamber 130. As a result, while the pressure in the nozzle chamber Pnzl is maintained at the high pressure Phigh, the pressure in the control chamber Pct1 is decreased to increase the differential pressure ΔP, and the needle portion 104 is opened (lifted).

  By controlling the two-way valve 131 and the three-way valve 144 in this manner, the fuel injection rate FIR in the period Top_low (see FIG. 8) from when the fuel injection rate FIR starts increasing and reaches the maximum injection rate FIRmax. Making the average value smaller than the average value of the fuel injection rate FIR in the period Top_mid (see FIG. 4) from when the fuel injection rate FIR starts to increase to the maximum injection rate FIRmax in the medium speed valve opening control Can.

  As described above, the present injection device selectively increases the average value of the fuel injection rates FIR at the initial stage of fuel injection (the period Top_mid, Top_high, and Top_low) to any one of three different fuel injection rates FIR. Can be controlled by

(Specific valve closing control of this injection device)
Next, specific valve closing control of the present injection device will be described. The present injection device performs “high-speed valve closing control”, “medium-speed valve closing control”, and “low-speed valve closing” as valve closing control for closing the needle portion 104 in order to end fuel injection from the fuel injection valve 100. Perform "valve control" selectively.

  In this example, the valve closing speed of the needle section 104 when the needle section 104 is closed by the high speed valve closing control is the largest speed (hereinafter referred to as “maximum valve closing speed”). On the other hand, when the needle portion 104 is closed by the low speed valve closing control, the valve closing speed of the needle portion 104 is the smallest speed (hereinafter referred to as "minimum valve closing speed"). Furthermore, the valve closing speed of the needle section 104 when the needle section 104 is closed by the medium speed valve closing control is a speed between the maximum valve closing speed and the minimum valve closing speed.

(Medium speed valve closing control)
First, medium-speed valve closing control will be described with reference to FIGS. 10 and 11. In the example shown in FIG. 10, the present injection device starts closing control of the fuel injection valve 100 at time t5. Therefore, before time t5, the fuel injection valve 100 is opened.

  When the fuel injection valve 100 is opened, as shown in FIG. 11A, before time t5 (before the start of the medium-speed valve closing control), the two-way valve 131 is at the first low pressure position. Positioned, the three-way valve 144 is positioned at the second high pressure position. Therefore, before time t5, as shown in FIG. 10, the control chamber pressure Pctl is the low pressure Plow, and the nozzle chamber pressure Pnzl is the high pressure Phigh. At this time, the differential pressure ΔP is the maximum differential pressure ΔPmax. Therefore, the needle portion 104 is positioned at the valve opening position (the fuel injection valve 100 is opened).

  At time t5, the present injection device moves the three-way valve 144 to the second low pressure position while maintaining the two-way valve 131 at the first low pressure position, as shown in FIG. 11B. As a result, as shown in FIG. 10, with the control chamber pressure Pctl maintained at the low pressure Plow, the nozzle chamber pressure Pnzl decreases from the high pressure Phigh toward the low pressure Plow.

  The differential pressure ΔP gradually decreases after time t5, and reaches a pressure at which the needle portion 104 starts to move in the valve closing direction (hereinafter referred to as “valve closing start differential pressure”) ΔPcl_th at time t6.

  When the differential pressure ΔP reaches the valve closing start differential pressure ΔPcl_th, the needle portion 104 starts moving (valve closing) in the valve closing direction. Therefore, the needle lift amount Lndl starts to decrease. Thereafter, the needle lift amount Lndl gradually decreases and reaches a predetermined lift amount Lndl_th at time t7.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to decrease. Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually decrease and become “0” at time t8. Thus, the fuel injection from the fuel injection valve 100 is completed.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” in the case where the fuel injection valve 100 is closed by the medium speed valve closing control.

(High-speed valve closing control)
Next, high-speed valve closing control will be described with reference to FIGS. 12 and 13. In FIG. 12, solid lines indicate "changes in the positions of the two-way valve 131 and three-way valve 144" and "changes in the control chamber pressure Pctl etc." when closing the fuel injection valve 100 by high-speed valve closing control. And the chain line indicate "change in the position of the two-way valve 131 and the three-way valve 144" and "change in the control chamber pressure Pctl" in the case where the fuel injection valve 100 is closed by the medium speed valve closing control described above. ing.

  Also in the example shown in FIG. 12, the present injection device starts closing control of the fuel injection valve 100 at time t5. Therefore, before time t5, the fuel injection valve 100 is opened.

  When the fuel injection valve 100 is opened, as shown in FIG. 13A, the two-way valve 131 is positioned at the first low pressure position, and the three-way valve 144 is positioned at the second high pressure position. . Therefore, as shown in FIG. 12, the control chamber pressure Pctl is a low pressure Plow, and the nozzle chamber pressure Pnzl is a high pressure Phigh. At this time, the differential pressure ΔP is the maximum differential pressure ΔPmax. Therefore, the needle portion 104 is positioned at the valve opening position (the fuel injection valve 100 is opened).

  At time t5, the present injection device moves the two-way valve 131 to the first high pressure position and moves the three-way valve 144 to the second low pressure position, as shown in FIG. 13B. As a result, as shown in FIG. 12, the control chamber pressure Pct1 increases from the low pressure Plow toward the high pressure Phigh, and the nozzle chamber pressure Pnzl decreases from the high pressure Phigh to the low pressure Plow. At this time, the speed at which the control chamber pressure Pctl increases toward the high pressure Phigh is smaller than the speed at which the nozzle chamber pressure Pnzl decreases toward the low pressure Plow.

  Differential pressure ΔP gradually decreases after time t5, and reaches valve closing differential pressure ΔPcl_th at a time earlier than “time t6 when differential pressure ΔP reaches valve closing start differential pressure ΔPcl_th in medium-speed valve closing control”. .

  When the differential pressure ΔP reaches the valve closing start differential pressure ΔPcl_th, the needle portion 104 starts moving (valve closing) in the valve closing direction. Therefore, the needle lift amount Lndl starts to decrease. Thereafter, the needle lift amount Lndl gradually decreases, and reaches the predetermined lift amount Lndl_th at a time earlier than the time t7 at which the needle lift amount Lndl reaches the predetermined lift amount Lndl_th in the medium-speed valve closing control.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to decrease. Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually decrease, and at a time earlier than the time t8 at which the needle lift amount Lndl and the fuel injection rate FIR become “0” in the middle speed valve closing control, Each becomes "0". Thus, the fuel injection from the fuel injection valve 100 is completed.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” in the case where the fuel injection valve 100 is closed by high-speed valve closing control.

  As described above, in the medium speed closing control, the fuel in the nozzle chamber 100n is moved by moving the three-way valve 144 to the second low pressure position while maintaining the two-way valve 131 at the first low pressure position. It is discharged to the spring chamber 141 through the second fuel discharge passage 122. As a result, the pressure in the nozzle chamber Pnzl is decreased while maintaining the control chamber pressure Pctl at the low pressure Plow, whereby the differential pressure ΔP is decreased, and the needle portion 104 is closed.

  On the other hand, in the high speed valve closing control, the fuel is discharged from the control chamber 100c to the two-way valve chamber 130 by moving the two-way valve 131 to the first high pressure position and moving the three-way valve 144 to the second low pressure position. And the fuel in the nozzle chamber 100 n is discharged to the spring chamber 141 via the second fuel discharge passage 122. As a result, the pressure in the control chamber Pctl is increased and the pressure in the nozzle chamber Pnzl is decreased to decrease the differential pressure ΔP, thereby closing the needle portion 104.

  By controlling the two-way valve 131 and the three-way valve 144 in this manner, the average of the fuel injection rates FIR in the period Tcl_high (see FIG. 12) from when the fuel injection rate FIR starts to decrease until it reaches "0". The value can be made larger than the average value of the fuel injection rate FIR in a constant period Tcl_mid (see FIG. 10) after the fuel injection rate FIR starts to decrease in the medium speed valve closing control.

(Low speed valve closing control)
Next, low-speed valve closing control will be described with reference to FIGS. 14 and 15. In FIG. 14, the solid line indicates “change in the position of the two-way valve 131 and three-way valve 144” and “change in the control chamber pressure Pctl” when closing the fuel injection valve 100 by low speed valve closing control. . On the other hand, the chain line indicates "changes in the positions of the two-way valve 131 and the three-way valve 144" and "changes in the control chamber pressure Pctl" in the case where the fuel injection valve 100 is closed by the medium speed valve closing control described above. It shows.

  Also in the example shown in FIG. 14, the present injection device starts closing control of the fuel injection valve 100 at time t5. Therefore, before time t5, the fuel injection valve 100 is opened.

  When the fuel injection valve 100 is opened, as shown in FIG. 15A, the two-way valve 131 is positioned at the first low pressure position, and the three-way valve 144 is positioned at the second high pressure position. . Therefore, as shown in FIG. 14, the control chamber pressure Pctl is a low pressure Plow, and the nozzle chamber pressure Pnzl is a high pressure Phigh. At this time, the differential pressure ΔP is the maximum differential pressure ΔPmax. Therefore, the needle portion 104 is positioned at the valve opening position (the fuel injection valve 100 is opened).

  At time t5, the present injection device moves the two-way valve 131 to the first high pressure position while maintaining the three-way valve 144 at the second high pressure position, as shown in FIG. 15B. As a result, as shown in FIG. 14, the control room pressure Pctl increases from the low pressure Plow toward the high pressure Phigh while the pressure in the nozzle room Pnzl is maintained at the high pressure Phigh.

  Differential pressure ΔP gradually decreases after time t5, and reaches valve closing differential pressure ΔPcl_th at a time later than “time t6 when differential pressure ΔP reaches valve closing start differential pressure ΔPcl_th in medium-speed valve closing control” .

  When the differential pressure ΔP reaches the valve closing start differential pressure ΔPcl_th, the needle portion 104 starts moving (valve closing) in the valve closing direction. Therefore, the needle lift amount Lndl starts to decrease. Thereafter, the needle lift amount Lndl gradually decreases, and reaches the predetermined lift amount Lndl_th at a time later than the time t7 at which the needle lift amount Lndl reaches the predetermined lift amount Lndl_th in the medium-speed valve closing control.

  When the needle lift amount Lndl reaches the predetermined lift amount Lndl_th, the fuel injection rate FIR starts to decrease. Thereafter, the needle lift amount Lndl and the fuel injection rate FIR gradually decrease, and at a time later than a time t8 at which the needle lift amount Lndl and the fuel injection rate FIR become “0” in the medium-speed valve closing control, Each becomes "0". Thus, the fuel injection from the fuel injection valve 100 is completed.

  The above are “changes in the positions of the two-way valve 131 and the three-way valve 144” and “changes in the control chamber pressure Pctl” in the case where the fuel injection valve 100 is closed by the low speed valve closing control.

  As described above, in the medium speed closing control, the fuel in the nozzle chamber 100n is moved by moving the three-way valve 144 to the second low pressure position while maintaining the two-way valve 131 at the first low pressure position. It is discharged to the spring chamber 141 through the second fuel discharge passage 122. As a result, the pressure in the nozzle chamber Pnzl is decreased while maintaining the control chamber pressure Pctl at the low pressure Plow, whereby the differential pressure ΔP is decreased, and the needle portion 104 is closed.

  On the other hand, in the low speed valve closing control, the two-way valve 131 is moved to the first high-pressure position while maintaining the three-way valve 144 at the second high-pressure position, fuel from the control chamber 100c to the two-way valve chamber 130 Stop the discharge. As a result, while the pressure in the nozzle chamber Pnzl is maintained at the high pressure Phigh, the pressure in the control chamber Pct1 is increased to reduce the differential pressure ΔP, and the needle portion 104 is closed.

  By controlling the two-way valve 131 and the three-way valve 144 in this manner, the average of the fuel injection rates FIR during the period Tcl_low (see FIG. 14) from when the fuel injection rate FIR starts to decrease until it reaches "0". The value can be made smaller than the average value of the fuel injection rate FIR in a constant period Tcl_mid (see FIG. 10) after the fuel injection rate FIR starts to decrease in the medium speed valve closing control.

  As described above, the fuel injection valve 100 sets the average value of the fuel injection rates FIR in one of three different fuel injection rates FIR in the period immediately before the end of the fuel injection (the above periods Tcl_mid, Tcl_high and Tcl_low). It is possible to selectively control with high accuracy.

  DESCRIPTION OF SYMBOLS 10 internal combustion engine 41 common rail (high pressure fuel source) 100 fuel injection valve 100c control chamber 100n nozzle chamber 103 fuel injection hole 104 needle portion 105 fuel inlet passage 106 fuel Outlet passage 107: orifice (fuel flow throttle portion) 108: orifice (fuel flow throttle portion) 111: first fuel supply passage 112: second fuel supply passage 113: third fuel supply passage 121: third 1 fuel discharge passage, 122: second fuel discharge passage, 123: third fuel discharge passage, 131: two-way valve, 144: three-way valve, FIR: fuel injection rate

Claims (3)

In-cylinder injection fuel injection valve that directly injects fuel into the combustion chamber of an internal combustion engine,
A high pressure fuel source for supplying high pressure fuel to the fuel injection valve;
A control unit that controls the operation of the fuel injection valve;
In a fuel injection system of an internal combustion engine provided with
The fuel injection valve is
Fuel injection holes for injecting fuel,
A needle portion that can be positioned at one of a valve closing position for closing the fuel injection hole and an valve opening position for opening the fuel injection hole;
A control chamber for containing fuel for applying fuel pressure for positioning the needle portion at the valve closing position to the needle portion, the high pressure through a first fuel supply passage provided with a fuel flow rate restricting portion A control chamber connected to the fuel source and to the fuel outlet via the first fuel outlet passage;
A nozzle chamber for containing fuel for applying fuel pressure for positioning the needle portion at the valve opening position to the needle portion, the nozzle chamber being connected to the high pressure fuel source via a second fuel supply passage; (2) A nozzle chamber connected to the fuel discharge unit via a fuel discharge passage and in communication with the fuel injection hole,
A first low pressure position for communicating the control chamber with the fuel discharge unit via the first fuel discharge passage; and blocking communication between the control chamber and the fuel discharge unit via the first fuel discharge passage (1) Two-way valve positionable in any one of high-pressure positions, and
A second low pressure position connecting the nozzle chamber with the fuel discharge unit via the second fuel discharge passage and blocking communication between the nozzle chamber and the high pressure fuel source via the second fuel supply passage; A second high pressure position for connecting the nozzle chamber to the high pressure fuel source via the second fuel supply passage and blocking communication between the nozzle chamber and the fuel discharge unit via the second fuel discharge passage; Three-way valve, which can be positioned to either
Equipped with
The fuel pressure in the control chamber is such that the two-way valve is positioned at the first high pressure position regardless of whether the three-way valve is positioned at the second low pressure position or the second high pressure position In this case, the pressure is higher than when the two-way valve is positioned at the first low pressure position,
The fuel pressure in the nozzle chamber is such that the three-way valve is positioned at the second high pressure position regardless of whether the two-way valve is positioned at the first low pressure position or at the first high pressure position. In this case, the pressure is higher than when the three-way valve is positioned at the second low pressure position,
The needle portion is configured to be positioned at the valve opening position when the difference between the fuel pressure in the control chamber and the fuel pressure in the control chamber is equal to or greater than a predetermined value.
The control unit
In a state where the two-way valve and the three-way valve are respectively positioned at the first high pressure position and the second low pressure position, the two-way valve is moved to the first low pressure position and the three way valve is moved to the second high pressure position First valve opening control for positioning the needle portion at the valve opening position by moving the
With the two-way valve and the three-way valve positioned at the first low pressure position and the second low pressure position, respectively, the three-way valve is maintained at the first low pressure position while the three-way valve is at the second high pressure position Second valve opening control for positioning the needle portion at the valve opening position by moving the
In a state where the two-way valve and the three-way valve are positioned at the first high pressure position and the second high pressure position, respectively, the two-way valve is maintained at the second high pressure position while the two-way valve is at the first low pressure position Third valve opening control for positioning the needle portion at the valve opening position by moving the
Configured to inject fuel from the fuel injection holes by selectively executing any one of
Fuel injection device.   In the fuel injection device according to claim 1,
  When the two-way valve is positioned at the first low pressure position, the control chamber is communicated with the fuel discharge unit via the first fuel discharge passage by opening the first fuel discharge passage. Configured to
  When the two-way valve is positioned at the first high pressure position, communication between the control chamber and the fuel discharge unit via the first fuel discharge passage is blocked by blocking the first fuel discharge passage. Configured to block,
  When the three-way valve is positioned at the second low pressure position, the nozzle chamber is closed via the second fuel discharge passage by blocking the second fuel supply passage and opening the second fuel discharge passage. And communicating with the fuel discharge portion and blocking communication between the nozzle chamber and the high-pressure fuel source via the second fuel supply passage,
  When the three-way valve is positioned at the second high pressure position, the nozzle chamber is opened via the second fuel supply passage by opening the second fuel supply passage and blocking the second fuel discharge passage. And communicating with the high pressure fuel source and blocking the communication between the nozzle chamber and the fuel discharge portion via the second fuel discharge passage.
  Fuel injection device.   In the fuel injection device according to claim 1 or 2,
  The control unit
  When the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second high pressure position, the three-way valve is maintained at the first low pressure position while the three-way valve is held at the first low pressure position. A first valve closing control for positioning the needle portion at the valve closing position by moving it to a low pressure position;
  When the two-way valve and the three-way valve are positioned at the first low pressure position and the second high pressure position, respectively, the two-way valve is moved to the first high pressure position and the three-way valve is moved to the second A second valve closing control for positioning the needle portion in the valve closing position by moving it to the low pressure position;
  When the two-way valve and the three-way valve are respectively positioned at the first low pressure position and the second high pressure position, the two-way valve is maintained at the second high pressure position while the two-way valve is held A third valve closing control for positioning the needle portion at the valve closing position by moving it to a high pressure position;
  Configured to stop the injection of fuel from the fuel injection holes by selectively performing any one of
  Fuel injection device.

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