JP6623907B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device that controls a fuel injection valve that injects fuel used for combustion of an internal combustion engine.

  2. Description of the Related Art Conventionally, a common rail fuel injection system has been known as a method for increasing a fuel injection pressure for an engine fuel injection and optimally controlling fuel injection conditions such as an injection timing and an injection amount. The common rail fuel injection system stores fuel pressurized to a predetermined pressure by a fuel supply pump in a common rail in a state of accumulated pressure, and based on the pressure action of the fuel, the fuel is injected from the fuel injection valve under optimal fuel injection conditions into a combustion chamber. It is a system that injects. The fuel injection valve is provided with a needle for performing control to pass or cut off fuel supplied through a fuel supply pipe (for example, see Patent Document 1).

JP 2005-90341 A

  In the common rail fuel injection system, during operation of the engine, the high pressure fuel pumped from the fuel supply pump keeps the common rail and the fuel supply path from the common rail to the fuel injection valve at high pressure. However, when the engine stops, the fuel pressure in the fuel supply path decreases. When the fuel pressure decreases, the fuel filling density decreases, so that air that has been dissolved in the fuel appears and the like is mixed. If the operation of the engine is restarted in a state where such air is mixed, the needle cannot be controlled with high accuracy by air, and there is a problem that appropriate fuel injection is not performed until the air is completely removed.

  Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fuel injection control device capable of easily removing air.

  The present invention employs the following technical means to achieve the above object.

According to the present invention, when the fuel pressure of the fuel flowing into the high-pressure fuel passage (51a) is lower than the valve opening pressure for opening the valve body (60), the outflow passage (52b) communicates the control member (33). A start control unit (17) for controlling the drive unit (30) to be in a state to start at least a removal process for removing air from the fuel outflow chamber (54); even before, the control member controls the drive unit so that the state of blocking the outflow passage, and the end control unit that ends the removal process (17), only contains, the start control unit and end controller, A fuel injection control device that switches between a state in which the outflow passage is communicated and a state in which the outflow passage is shut off a plurality of times during the removal processing until the fuel pressure reaches the valve opening pressure .

  According to the present invention, when the fuel pressure is lower than the valve opening pressure for opening the valve body, the removal process for removing air from the fuel outflow chamber is started. Therefore, no fuel is injected during the removal process. Also, in the removal process, after controlling the control member to a state where the outflow passage communicates, before the fuel pressure reaches the valve opening pressure at which the valve element opens, the outflow passage is controlled to be in a closed state, The removal processing ends. When the control member is controlled to communicate with the outflow passage, the high-pressure fuel in the pressure control chamber flows into the fuel outflow chamber. Then, the fuel in the fuel outflow chamber is discharged to the return flow path via the discharge passage. Thus, at least the air in the fuel outflow chamber can be discharged to the return flow path together with the fuel. Also, after discharging the fuel, the outflow passage is controlled to be closed before the fuel pressure reaches the valve opening pressure, so that the fuel is prevented from being injected while the air is being removed. be able to. Thus, air can be removed without fuel injection.

  Note that the reference numerals in parentheses of the above-described units are examples showing the correspondence with specific units described in the embodiments described later.

FIG. 1 is a diagram illustrating an overall configuration of a fuel supply system according to a first embodiment. Sectional drawing which shows a fuel injection valve. 5 is a time chart illustrating the operation of a fuel injection valve. Sectional drawing explaining operation | movement of a fuel injection valve. The figure explaining operation | movement of a fuel injection valve. 9 is a flowchart illustrating a removal process. 5 is a time chart illustrating a removal process.

(1st Embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The fuel supply system 10 shown in FIG. 1 uses the fuel injection valve 100 according to the first embodiment. The fuel supply system 10 supplies fuel to a combustion chamber 22 of a diesel engine 20, which is an internal combustion engine, by using a fuel injection valve 100. The fuel supply system 10 includes a feed pump 12, a high-pressure fuel pump 13, a common rail 14, an engine control device 17, and a plurality of fuel injection valves 100.

  The feed pump 12 is an electric pump that pumps the fuel stored in the fuel tank 11 to the high-pressure fuel pump 13. The feed pump 12 is connected to a high-pressure fuel pump 13 by a fuel pipe 12a. The fuel tank 11 stores fuel such as light oil.

  The high-pressure fuel pump 13 is driven by an output shaft of a diesel engine. The high-pressure fuel pump 13 is connected to a common rail 14 by a fuel pipe 13a. The high-pressure fuel pump 13 further increases the pressure of the fuel supplied by the feed pump 12 and supplies the fuel to the common rail 14.

  The common rail 14 is connected to each fuel injection valve 100 via a fuel pipe 14a. FIG. 1 shows one fuel injection valve 100. The fuel pipe 14a forms a fuel flow path 15 that supplies fuel to each fuel injection valve 100. The common rail 14 temporarily stores the high-pressure fuel supplied from the high-pressure fuel pump 13 and distributes the high-pressure fuel to the fuel injection valves 100 while maintaining the pressure. The surplus fuel in the common rail 14 is discharged to the surplus fuel pipe 14b while being reduced in pressure. The surplus fuel pipe 14b forms a return flow path 16 for returning surplus fuel to the fuel tank 11.

  The engine control device 17 is a fuel injection control device, and is a microcomputer or microcontroller including a processor as an arithmetic circuit, a RAM, and a rewritable nonvolatile storage medium, and a drive circuit for driving each fuel injection valve 100 This is a configuration including The engine control device 17 controls the operation of each fuel injection valve 100 according to the operating state of the diesel engine 20.

  The engine control device 17 acquires information from various sensors and controls each unit. The engine control device 17 controls the pressure of the common rail 14 using, for example, the fuel pressure obtained from the pressure sensor 14d that detects the pressure of the common rail 14.

  A fuel pipe 14a and a return pipe 14c are connected to the fuel injection valve 100. The fuel injection valve 100 is attached to the head member 21 while being inserted into an insertion hole of the head member 21 forming the combustion chamber 22. The fuel injection valve 100 directly injects the fuel supplied through the fuel passage 15 from the plurality of injection holes 44 into the combustion chamber 22. The fuel injection valve 100 includes a valve mechanism that controls the injection of fuel from the injection hole 44. The valve mechanism includes a pressure control valve 35 (see FIG. 2) that operates based on a drive signal from the engine control device 17, and a main valve unit 50 that opens and closes the injection hole 44. The fuel injection valve 100 uses a part of the fuel supplied through the fuel flow path 15 to open and close the injection hole 44. The fuel used to open and close the injection holes 44 is discharged to the return pipe 14c while being decompressed. The return pipe 14c, together with the surplus fuel pipe 14b, forms a return flow path 16 for returning the fuel not used for combustion to the fuel tank 11.

  As shown in FIG. 2, the fuel injection valve 100 includes a control body 40, a nozzle needle 60, an armature 33, a driving unit 30, a return spring 66, and a floating plate 70. The control body 40 has an injection hole 44, a high-pressure fuel passage 51a, an inflow passage 52a, an outflow passage 52b, a supply passage 52c, a pressure control chamber 53, an armature chamber 54, and a low-pressure fuel passage 51b.

  As shown in FIGS. 1 and 2, the injection hole 44 is formed at the distal end of the control body 40 inserted into the combustion chamber 22 in the insertion direction. The tip is formed in a conical or hemispherical shape. A plurality of injection holes 44 are provided radially from the inside to the outside of the control body 40. High-pressure fuel is injected into the combustion chamber 22 through the injection hole 44. As the fuel passes through the injection holes 44, the fuel is vaporized and is easily mixed with air.

  The high-pressure fuel passage 51 a is connected to the fuel passage 15. The high-pressure fuel passage 51a allows high-pressure fuel supplied from the common rail 14 to flow through the inflow passage 52a and the supply passage 52c. The inflow passage 52a connects the high-pressure fuel passage 51a with the pressure control chamber 53. The inflow passage 52 a allows high-pressure fuel to flow into the pressure control chamber 53. The outflow passage 52b communicates the pressure control chamber 53 with the armature chamber 54. The outflow passage 52b allows the fuel in the pressure control chamber 53 to flow out to the armature chamber 54. The supply passage 52c allows the high-pressure fuel supplied through the high-pressure fuel passage 51a to flow to the injection holes 44.

  The pressure control chamber 53 is provided inside the control body 40 on the opposite side of the injection hole 44 with the nozzle needle 60 interposed therebetween. The high-pressure fuel supplied through the fuel passage 15 and the inflow passage 52a flows into the pressure control chamber 53. The fuel pressure in the pressure control chamber 53 fluctuates due to the inflow of high-pressure fuel from the inflow passage 52a and the outflow of fuel to the armature chamber 54 through the outflow passage 52b. The pressure control chamber 53 reciprocates the nozzle needle 60 using the pressure fluctuation of the fuel.

  Fuel flows out of the pressure control chamber 53 into the armature chamber 54 through the outflow passage 52b. The armature chamber 54 accommodates the armature 33 so as to be reciprocally displaceable. The pressure of the fuel in the armature chamber 54 is lower than the pressure of the fuel in the pressure control chamber 53.

  The low-pressure fuel passage 51b is connected to the armature chamber 54 and the return flow passage 16. The low-pressure fuel passage 51b extends in the control body 40 along the high-pressure fuel passage 51a. The low-pressure fuel passage 51 b discharges the fuel in the armature chamber 54 to the return passage 16.

  The control body 40 includes a nozzle body 41 formed of a metal material, a cylinder 56, an orifice plate 46, a holder 48, and the like. The nozzle body 41, the orifice plate 46, and the holder 48 are arranged in this order from the tip end side in the direction of insertion into the head member 21 (see FIG. 1).

  The nozzle body 41 is a cylindrical member having a bottom. The nozzle body 41 has an injection hole 44 and a supply passage 52c. The nozzle body 41 has a nozzle needle storage chamber 43 and a seat part 45. The nozzle needle storage chamber 43 is formed in a cylindrical hole shape, and stores the nozzle needle 60 and the cylinder 56. The nozzle needle accommodating chamber 43 defines a supply passage 52c together with the cylinder 56. The seat portion 45 is formed in a conical shape inside the front end portion, and faces the supply passage 52c.

  The cylinder 56 is formed in a cylindrical shape. The cylinder 56 defines a pressure control chamber 53 together with the orifice plate 46 and the nozzle needle 60. The cylinder 56 is arranged on the inner peripheral side of the nozzle body 41 so as to be coaxial with the nozzle body 41.

  The orifice plate 46 is formed in a disk shape. The orifice plate 46 has an inflow passage 52a and an outflow passage 52b. The orifice plate 46 has a control seat 46a. The control sheet portion 46a is formed so as to surround the opening of the outflow passage 52b on the top surface of the orifice plate 46 facing the holder 48 side. The control seat portion 46a forms a pressure control valve 35 together with the armature 33.

  The holder 48 is formed in a cylindrical shape. The holder 48 has two vertical holes extending in the axial direction. Each vertical hole forms a high-pressure fuel passage 51a and a low-pressure fuel passage 51b, respectively. The drive unit 30 is housed in the holder 48.

  The nozzle needle 60 is formed in a cylindrical shape as a whole by a metal material. The nozzle needle 60 is housed in the nozzle body 41. One end of the nozzle needle 60 is inserted into the cylinder 56. The nozzle needle 60 is axially reciprocable along a support surface 56 a formed on the inner peripheral wall of the cylinder 56.

  The nozzle needle 60 has a valve pressure receiving surface 61 and a face portion 65. The nozzle needle 60 reciprocates along the axial direction of the nozzle body 41 due to a change in fuel pressure in the pressure control chamber 53 received on the valve pressure receiving surface 61, and causes the face portion 65 to be separated from and seated on the seat portion 45. The face portion 65 forms a main valve portion 50 for opening and closing the injection hole 44 together with the seat portion 45. When the face portion 65 separates from the seat portion 45, the injection hole 44 is opened and fuel is injected. When the face portion 65 is seated on the seat portion 45, the injection hole 44 is closed and the fuel injection is stopped.

  The armature 33 is housed in an armature chamber 54 and is capable of reciprocating in the armature chamber 54. The armature 33 is a two-stage cylindrical member formed of a metal material that is a ferromagnetic material. The armature 33 changes the pressure of the pressure control chamber 53 by controlling the outflow of fuel from the pressure control chamber 53 to the armature chamber 54. The armature 33 has a suction part 33a and a control face part 33b. The suction part 33a is formed in a circular plate shape. The suction unit 33 a is sucked toward the drive unit 30 by the magnetic force generated by the drive unit 30. The control face portion 33b is formed at the tip of a columnar portion protruding from the center of the suction portion 33a toward the opening of the outflow passage 52b. The control face portion 33b can be pressed against the control sheet portion 46a by the displacement of the armature 33 to close the opening of the outflow passage 52b facing the armature chamber 54.

  The drive unit 30 is connected to the armature 33 and drives the armature 33. The drive unit 30 has a solenoid 31a, a pole face plate 31b, and a spring 31c. The solenoid 31a is a coil wound in a cylindrical shape. A pulse-like drive signal is supplied from the engine control device 17 to the solenoid 31a. The solenoid 31a generates a magnetic field that circulates in the axial direction by supplying a drive signal. The pole face plate 31b is a circular plate-shaped member formed of a magnetic material. The pole face plate 31b faces the suction part 33a. The pole face plate 31b is magnetized in the magnetic field generated by the solenoid 31a, and attracts the attracting portion 33a by magnetic force. The spring 31c is a coil spring in which a metal wire is spirally wound. The spring 31c urges the armature 33 in a direction to separate the armature 33 from the pole face plate 31b.

  When there is no power supply from the engine control device 17, the driving unit 30 causes the control face portion 33b to be seated on the control seat portion 46a by the urging force of the spring 31c. As a result, the pressure control valve 35 is in a closed state in which communication between the pressure control chamber 53 and the armature chamber 54 as the fuel outflow chamber is interrupted.

  On the other hand, when the power is supplied from the engine control device 17, the driving unit 30 sucks the armature 33 and separates the control face unit 33b from the control seat unit 46a. Thus, the pressure control valve 35 is in an open state in which the pressure control chamber 53 and the armature chamber 54 communicate with each other. As described above, the drive section 30 opens and closes the pressure control valve 35 by reciprocating the armature 33 under the control of the engine control device 17. As a result, the outflow of fuel from the pressure control chamber 53 to the armature chamber 54 is controlled by the pressure control valve 35.

  The return spring 66 is a coil spring in which a metal wire is spirally wound. The return spring 66 urges the nozzle needle 60 toward the injection hole 44 to seat the face portion 65 on the seat portion 45.

  The floating plate 70 is a movable plate, housed in the pressure control chamber 53, and switches between a state in which the high-pressure fuel passage 51a communicates and a state in which the high-pressure fuel passage 51a is shut off. In the floating plate 70, an out orifice 71 is formed as a communication path that connects the outflow passage 52b and the pressure control chamber 53. The floating plate 70 is formed in a disk shape from a metal material. The floating plate 70 is disposed in the pressure control chamber 53 so as to be reciprocally displaceable along the axial direction of the nozzle body 41. The floating plate 70 is urged toward the orifice plate 46 by a spring 72. Out floating orifices 71 are formed in the floating plate 70. The out orifice 71 is a through hole that passes through the floating plate 70 in the thickness direction. The flow passage area of the out orifice 71 is defined to be smaller than the flow passage area of the outflow passage 52b. The out orifice 71 allows the fuel to flow from the pressure control chamber 53 to the outflow passage 52b and restricts the flow rate of the fuel flowing out to the outflow passage 52b when the floating plate 70 is in close contact with the orifice plate 46.

  In the above fuel injection valve 100, the fuel in the pressure control chamber 53 flows out to the armature chamber 54 through the out orifice 71 and the outflow passage 52b by opening the pressure control valve 35. As a result, the fuel pressure in the pressure control chamber 53 decreases, and the nozzle needle 60 moves toward the pressure control chamber 53 to open the injection hole 44. When the communication between the pressure control chamber 53 and the armature chamber 54 is interrupted by closing the pressure control valve 35, the fuel supplied through the inflow passage 52 a pushes the floating plate 70 down against the urging force of the spring 72. While flowing into the pressure control chamber 53. As a result, the fuel pressure in the pressure control chamber 53 recovers, and the nozzle needle 60 quickly moves to the seat portion 45 side to close the injection hole 44.

  Next, an operation in which the fuel injection valve 100 performs fuel injection according to the drive current from the engine control device 17 will be described. When the drive current from the engine control device 17 is caused to flow to the solenoid 31a to control the opening of the pressure control valve 35, the outflow passage 52b communicates with the armature chamber 54. As a result, the fuel in the pressure control chamber 53 starts to be discharged to the outside of the fuel injection valve 100 through the outflow passage 52b and the low-pressure fuel passage 51b. This fuel discharge first reduces the pressure in the gap between the upper end surface of the floating plate 70 and the lower end surface of the orifice plate 46. Due to this decompression, the floating plate 70 starts to be displaced upward and sits on the orifice plate 46. That is, the floating plate 70 closes the opening of the inflow passage 52a, and blocks communication between the inflow passage 52a and the pressure control chamber 53.

  Then, since the fuel flows out of the pressure control chamber 53 to the armature chamber 54, the pressure in the pressure control chamber 53 decreases, and the nozzle needle 60 is immediately pushed up toward the pressure control chamber 53 at a high speed and starts to be displaced. As a result, the nozzle needle 60 separates from the face portion 65 and opens. While the nozzle needle 60 is displaced, the pressure in the pressure control chamber 53 changes substantially constant as the volume of the pressure control chamber 53 decreases.

  Thereafter, when the drive current from the engine control device 17 is stopped to perform valve closing control so as to start closing the pressure control valve 35, the fuel discharge from the outflow passage 52b is stopped. This stop of fuel discharge causes the pressure in the gap between the upper end surface of the floating plate 70 and the lower end surface of the orifice plate 46 to rise. Then, the floating plate 70 in the seated state is separated from the orifice plate 46. That is, the floating plate 70 opens the opening of the inflow passage 52a, and makes the inflow passage 52a and the pressure control chamber 53 communicate with each other. Then, the fuel flows into the pressure control chamber 53, the pressure in the pressure control chamber 53 increases, and the nozzle needle 60 is pushed down at a high speed to be seated on the face portion 65, so that the valve is closed.

  Thereafter, after the nozzle needle 60 is seated, the volume of the pressure control chamber 53 does not increase, so that the pressure of the pressure control chamber increases. Then, since the force for pushing up the floating plate 70 increases, the floating plate 70 in the unseated state moves and sits on the orifice plate 46. A spring 72 is provided on the lower end surface of the floating plate 70, and the spring 72 applies an elastic force in a direction in which the floating plate 70 is seated. This elastic force assists the floating plate 70 in moving in the seating direction.

  In FIG. 1, reference symbol Pn indicates the pressure in the nozzle needle storage chamber 43, and the pressure Pn is the pressure of the fuel supplied to the fuel injection valve 100. The fuel is accumulated and distributed to a plurality of fuel injection valves. It corresponds to the pressure in the common rail. Reference symbol Pc in FIG. 1 indicates the pressure in the pressure control chamber 53, and more specifically, indicates the pressure in the region of the pressure control chamber 53 closer to the injection hole 44 with respect to the floating plate 70. The symbol Py in FIG. 1 is the pressure in the injection hole 44 during fuel injection.

1 indicates the force received by the valve pressure receiving surface 61 of the nozzle needle 60, and is expressed by the following equation (1) using the diameter dn of the nozzle needle 60 and the pressure Pc of the pressure control chamber 53. .
Fc = π / 4 × dn ＾ 2 × Pc (1)

  1 indicates a force that the nozzle needle 60 receives from the return spring 66 toward the injection hole 44.

The lower end of the nozzle needle 60 receives a force Fn in the valve opening direction due to the pressure Pn in the nozzle needle storage chamber 43. Here, the outer diameter of the nozzle needle 60 is a diameter dn, and the valve seat diameter (seat diameter) of the face portion 65 is a diameter ds. Then, in the valve closed state of the nozzle needle 60, the pressure receiving area on the lower end side of the nozzle needle 60 with respect to the force Fn in the valve opening direction is (π / 4) × (dn ＾ 2−ds ＾ 2). Therefore, when the nozzle needle 60 is closed, the force Fn in the valve opening direction can be expressed by the following equation (2).
Fn = (π / 4) × (dn ＾ 2-ds ＾ 2) × Pn (2)

When the nozzle needle 60 opens, a portion of the face portion 65 closer to the tip end than a portion in contact with the seat portion 45 is also exposed to the fuel having the injection pressure Py. Therefore, in the valve-open state of the nozzle needle 60, the pressure receiving area on the lower end side of the nozzle needle 60 for the force Fy in the valve-opening direction is π / 4 × ds ＾ 2. Therefore, when the nozzle needle 60 is in the valve-open state, the force Fy in the valve-opening direction can be expressed by the following equation (2).
Fy = π / 4 × ds ＾ 2 × Py (3)

The valve opening force of the nozzle needle 60 is the sum of the force acting in the valve opening direction and the force acting in the valve closing direction. The forces acting in the valve opening direction are the force received from the fuel pressure around the tip of the nozzle needle 60 and the force received from the nozzle needle storage chamber 43. The force acting in the valve closing direction is the fuel pressure Fc in the pressure control chamber 53 and the force Fs received from the return spring 66 pressing the nozzle needle 60. Therefore, since the valve opening force can be expressed by the following equation (4), substituting equations (1) to (3) into equation (4) gives the following equation (5).
Valve opening force = (Fn + Fy)-(Fs + Fc) (4)
Valve opening force = (π / 4 × (dn ＾ 2-ds ＾ 2) × Pn + π / 4 × ds ＾ 2 × Py)
− (Fs + π / 4 × dn ＾ 2 × Pc) (5)

  When the valve opening force ≧ 0, the nozzle needle 60 starts to rise, so Pn when the valve opening force = 0 is the valve opening pressure.

  Next, a removal process in which the fuel injection valve 100 removes air in accordance with a drive current from the engine control device 17 will be described with reference to FIGS. Before energization, as shown in FIG. 4, the control face portion 33b of the pressure control valve 35 is in contact with the control seat portion 46a, so that the outflow passage 52b is in a closed state. When performing the removal process, the pressure of the common rail 14 is assumed to be smaller than the valve opening pressure.

  When the drive current from the engine control device 17 flows through the solenoid 31a at time t1 from the state before the energization to energize, the pressure control valve 35 rises. This causes the outflow passage 52b to be in a communicating state, and the fuel in the pressure control chamber 53 starts to be discharged to the outside of the fuel injection valve 100 through the outflow passage 52b and the low-pressure fuel passage 51b. This starts the removal process. Therefore, as shown in FIG. 3, the leak amount increases.

  Then, rapid decompression occurs in the pressure control chamber 53, but since the pressure Pn in the nozzle needle storage chamber 43 has not reached the valve opening pressure, the nozzle needle 60 is not displaced and the valve closed state is maintained. I have. Thus, the fuel in the pressure control chamber 53 and the fuel in the armature chamber 54 flow out of the low-pressure fuel passage 51b. However, since there is no fuel flowing out any more, the outflow stops at time t2 as shown in FIG.

  Thereafter, at time t3, when the drive current from the engine control device 17 is stopped, the closing of the pressure control valve 35 is started. Then, at time t4, the control face portion 33b comes into contact with the control seat portion 46a, and the valve is closed. Thus, the removal processing ends. Then, due to the pressure of the fuel supplied from the inflow passage 52a, the seated floating plate 70 is displaced downward from the orifice plate 46 and separated, and the inflow passage 52a and the pressure control chamber 53 are communicated. Then, the fuel flows into the pressure control chamber 53, and the pressure control chamber 53 is filled with the fuel again.

  If this is a 2W valve structure, the amount of leak increases as shown in FIG. 3 according to the energization time. The 2W valve structure is a structure in which fuel can flow into the pressure control chamber 53 even when fuel flows out of the pressure control chamber 53. Therefore, when the outflow passage 52b is in the communicating state, the fuel always flows.

  However, in the fuel injection valve 100 in which the entrance and exit of the pressure control chamber 53 have a three-way valve structure 80, that is, a 3W valve, as in the present embodiment, the amount of leakage generated by one opening is very small. As schematically shown in FIG. 5, in the three-way valve structure 80, when the fuel flows out of the pressure control chamber 53 through the outflow passage 52b, the fuel does not flow into the pressure control chamber 53 from the inflow passage 52a. Conversely, when the fuel flows from the pressure control chamber 53 through the inflow passage 52a, the fuel does not flow from the pressure control chamber 53 to the outflow passage 52b. Therefore, the amount of flow out of the low-pressure fuel passage 51b per opening of the valve is about the volume of the pressure control chamber 53, and there is a flow-out time Tsl until the flow stops. Therefore, the outflow time Tsl is defined as the time from when the outflow passage 52b is communicated to when the flow of fuel from the pressure control chamber 53 in the outflow passage 52b to the armature chamber 54 stops.

  Similarly, after the valve is opened once, the amount flowing from the high-pressure fuel passage 51a is about the volume of the pressure control chamber 53, and there is a flowing time Tsh until the flow stops. Therefore, the inflow time Tsh is defined as the time from when the outflow passage 52b is shut off until the flow of fuel into the pressure control chamber 53 in the high-pressure fuel passage 51a stops. Using such an outflow time Tsl and an inflow time Tsh, a removal process for removing air is performed.

Next, the outflow time Tsl will be described. The pressure Pc of the pressure control chamber 53 is calculated from the value of the pressure sensor 14d of the common rail 14, and the inflow time Tsh during which fuel enters the pressure control chamber 53 using the pressure Pc and the optimal outflow for fuel to escape from the pressure control chamber 53. The time Tsl is calculated. For calculation of these times, for example, the following equation (6) is used.

  Here, K indicates the bulk modulus, and Pl indicates the fuel pressure (individual value) of the armature chamber 54. Ph indicates the fuel pressure of the high pressure section obtained by the pressure sensor 14d, V indicates the volume of the pressure control chamber 53, and A indicates the flow path area. Using equation (6), the outflow time, that is, the time when Q (t) = 0, is obtained from the outflow orifice, that is, the flow rate Q (t) at the outlet of the pressure control chamber 53 and the fuel pressure P (t) in the pressure control chamber 53. Tsl.

  Since the solid parameters such as the outlet diameter A of the outflow passage 52b connected to the armature chamber 54 and the volume V of the pressure control chamber 53 are known, the outflow time Tsl and the inflow time Tsh can be calculated using equation (6). . The outflow time Tsl and the inflow time Tsh both correlate with the pressure of the common rail 14, and the higher the pressure, the longer the outflow time Tsl and the inflow time Tsh.

  Next, the removal processing will be described with reference to FIG. The removal process shown in FIG. 6 is repeatedly executed in a short time while the engine control device 17 is powered on. In step S1, it is determined whether or not the engine has been started. If the engine has been started, the process proceeds to step S2. If the engine has not been started, the flow ends. When the engine is started, it has the same meaning as when the ignition is turned on. In step S2, it is determined whether or not the fuel pressure of the common rail 14, that is, the fuel pressure Pn in the nozzle needle accommodating chamber 43, is smaller than the valve opening pressure Po. To end. As described above, when the engine is started, since the fuel pressure Pn of the common rail 14 is often lower than the valve opening pressure Po, the air removal processing is performed.

  In step S3, the solenoid 31a is energized, and the process proceeds to step S4. In step S4, the energization is continued until the outflow time Tsl elapses, and when the outflow time Tsl elapses, the process proceeds to step S5. As a result, the fuel in the armature chamber 54 can be discharged.

  In step S5, it is again determined whether or not the fuel pressure Pn in the nozzle needle storage chamber 43 is lower than the valve opening pressure Po. If the fuel pressure Pn is lower, the process proceeds to step S6, and if not, the flow ends. In step S6, the energization of the solenoid 31a is stopped, and the routine goes to step S7. In step S7, the energization stop is continued until the energization stop time elapses the inflow time Tsh. When the inflow time Tsh elapses, the process returns to step S2.

  Thus, the energization and the energization stop are repeated until the rail pressure which is the pressure of the common rail 14 exceeds the valve opening pressure Po. In the example shown in FIG. 7, the power supply to the solenoid 31a is turned on seven times. The outflow time Tsl and the inflow time Tsh, which are energization times, become longer as time elapses. This is because the rail pressure has increased as described above. When the engine is started, the rail pressure lower than the valve opening pressure at the time of starting gradually increases as shown in FIG. Although the rail pressure gradually increases, the pressure Pc in the pressure control chamber 53 repeats inflow and outflow of fuel when power is turned on and off, so that the pressure Pc repeatedly increases and decreases.

  When the power supply to the solenoid 31a is stopped, fuel flows into the solenoid 31a, so that the in-orifice amount increases. When the solenoid 31a is energized, the fuel flows out, so that the out orifice amount increases. By repeatedly turning on and off the current until the rail pressure reaches the valve opening pressure, the accumulated leak amount can be increased, so that the air in the armature chamber 54 can be more reliably removed.

  As described above, when the fuel pressure of the common rail 14 is lower than the valve opening pressure Po, the engine control device 17 of the present embodiment starts the removal process of removing air from the armature chamber 54. Therefore, no fuel is injected during the removal process. In the removal process, after the armature 33 as a control member is controlled to be in a state where the outflow passage 52b communicates, the removal process is performed by closing the outflow passage 52b before the fuel pressure reaches the valve opening pressure. finish. When the armature 33 is controlled so that the outflow passage 52b communicates, the high-pressure fuel in the pressure control chamber 53 flows to the armature chamber 54. Then, the fuel in the armature chamber 54 is discharged to the return passage 16 via the low-pressure fuel passage 51b which is a discharge passage. As a result, at least the air in the armature chamber 54 can be discharged to the return passage 16 together with the fuel. In addition, after the fuel is discharged, the outflow passage 52b is controlled to be closed before the fuel pressure reaches the valve opening pressure, so that the fuel is prevented from being injected while the air is being removed. can do. Thus, air can be removed without fuel injection.

  Further, in the present embodiment, the engine control device 17 functioning as a start control unit and an end control unit switches between a state in which the outflow passage 52b is communicated and a state in which the outflow passage 52b is shut off a plurality of times during the removal processing. The number of times of switching and the amount of fuel flowing out of the return flow path 16 are directly proportional. Therefore, by switching the communication and the cutoff a plurality of times during the removal process, the amount of fuel discharged from the fuel injection valve 100 to the return flow path 16 can be increased. Therefore, air can be more reliably removed.

  Furthermore, in the present embodiment, the outflow time Tsl required for the fuel in the pressure control chamber 53 to flow out to the armature chamber 54 is calculated using the fuel pressure, and the communication of the outflow passage 52b is set to be equal to or less than the outflow time Tsl. Controlling time. As a result, it is possible to prevent the outflow passage 52b from communicating even though there is no or less fuel flowing out. Therefore, by setting the outflow time Tsl to a required time, another time can be used as the inflow time Tsh.

Further, in the present embodiment, the inflow time Tsh required until the fuel fills the pressure control chamber 53 from the high-pressure fuel passage 51a is calculated using the fuel pressure, and the outflow passage 52b is cut off so as to be equal to or less than the inflow time Tsh. Controlling time. In this way, even when the pressure control chamber 53 is filled with fuel or the like, there is little or no room for fuel to flow in, and it is possible to prevent the outflow passage 52b from being blocked. Therefore, by setting the inflow time Tsh to a required time, another time can be used for the outflow time Tsl.

  Further, in the present embodiment, the fuel injection valve 100 is controlled so as to perform the removal processing at the time of starting. When the fuel injection valve 100 is started, the pressure of the common rail 14 is often lower than the valve opening pressure. Also, if there is air at the time of starting, there is a possibility that the fuel injection cannot be controlled with high accuracy. Therefore, by removing air at the time of starting, fuel injection can be controlled with high accuracy.

  In other words, the fuel injection valve 100 has a problem that when air enters the armature chamber 54, the armature 33 causes a fluttering increase in the fuel injection amount and a deterioration in the fuel injection rate σ. Therefore, in the present embodiment, when the outlet of the pressure control chamber 53 is open, the inlet of the pressure control chamber 53 closes, that is, in the fuel injection valve 100 having a 3W valve structure such that there is no inflow of fuel, air is supplied. Removed when starting the engine. Specifically, paying attention to the fact that the leak amount per time at the time of opening the armature 33 is determined from the pressure of the pressure control chamber 53, the volume of the pressure control chamber 53, and the flow coefficient of the orifice, the calculated outflow time Tsl is used. Thus, the driving time of the solenoid 31a for removing air is controlled.

  In the first embodiment, the armature 33 corresponds to a “control member”, the control body 40 corresponds to a “valve body”, the low-pressure fuel passage 51b corresponds to a “discharge passage”, and the armature chamber 54 corresponds to a “fuel outflow chamber”. ". Further, the nozzle needle 60 corresponds to a “valve body”.

(Other embodiments)
As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the gist of the present invention.

  The structure of the above-described embodiment is merely an example, and the scope of the present invention is not limited to the scope of the description. The scope of the present invention is shown by the description of the claims, and further includes all modifications within the meaning and scope equivalent to the description of the claims.

  In the above-described first embodiment, the removal processing is performed at the time of starting the internal combustion engine, which is the engine. However, the removal processing is not limited to the time of starting the engine. For example, the removal processing may be performed during idle stop.

  In the above-described first embodiment, the control is performed on one fuel injection valve 100. However, the removal processing may be performed on a plurality of fuel injection valves 100 in parallel. In this case, each fuel injection valve 100 may be driven by shifting the energization time to the drive unit 30 of each fuel injection valve 100. In other words, while the drive unit 30 of one fuel injection valve 100 is on, the drive unit 30 of the other fuel injection valve 100 is turned off, that is, the drive unit 30 is turned on and off alternately. Thereby, the removal processing of the plurality of fuel injection valves 100 can be performed in the same time zone.

  In the first embodiment described above, the control is performed using the rail pressure, but the control is not limited to the control using the rail pressure. For example, another value related to the increase in the rail pressure may be used instead of the rail pressure. For example, since the rail pressure increases after the engine is started, when the elapsed time reaches a predetermined time, it may be determined that the rail pressure has increased to the valve opening pressure, and the removal processing may be terminated.

10: fuel supply system 12a: fuel pipe 14: common rail
15 fuel flow path 16 return flow path 17 engine control device (start control unit, end control unit)
DESCRIPTION OF SYMBOLS 30 ... Drive part 33 ... Armature (control member) 35 ... Pressure control valve 40 ... Control body (valve body) 41 ... Nozzle body 43 ... Nozzle needle accommodating chamber 44 ... Injection hole 45 ... Seat part 51a ... High pressure fuel passage 51b ... Low pressure fuel Passage (discharge passage)
52a ... inflow passage 52b ... outflow passage 52c ... supply passage 53 ... pressure control chamber 54 ... armature chamber (fuel outflow chamber) 60 ... nozzle needle (valve element)
70: floating plate (movable plate) 71: out orifice (communication passage)
100 ... fuel injection valve

Claims (4)

Fuel injection control for injecting fuel supplied through a fuel flow path (15) from an injection hole (44) and controlling a fuel injection valve (100) for discharging a part of the supplied fuel to a return flow path (16) A device,
The fuel injection valve,
A high-pressure fuel passage (51a) communicating with the injection hole and the fuel flow path, a pressure control chamber (53) into which fuel supplied through the high-pressure fuel passage flows, and a fuel outflow chamber from which fuel in the pressure control chamber flows out ( 54) a valve forming an outflow passage (52b) for discharging fuel from the pressure control chamber to the fuel outflow chamber, and a discharge passage (51b) for discharging fuel from the fuel outflow chamber to the return flow path. Body (40),
A valve body (60) housed in the valve body and reciprocatingly displaced by the pressure fluctuation of the pressure control chamber to open and close the injection hole;
A control member (33) that is housed in the fuel outflow chamber, switches between a state in which the outflow passage communicates and a state in which the outflow passage is shut off, and changes the pressure in the pressure control chamber;
A communication passage (71) that is housed in the pressure control chamber and switches between a state in which the high-pressure fuel passage communicates and a state in which the high-pressure fuel passage is shut off, and a communication passage (71) that communicates the outflow passage with the pressure control chamber is formed. A movable plate (70),
A driving unit (30) for driving the control member,
When the control unit causes the outflow passage to communicate with the drive unit, the movable plate disconnects the high-pressure fuel passage, and the fuel in the pressure control chamber passes through the communication passage and the outflow passage. After flowing out of the outflow passage, the pressure in the pressure control chamber is reduced, the valve body is displaced, and the injection hole is opened,
When the driving member causes the control member to shut off the outflow passage, the movable plate communicates with the high-pressure fuel passage by the pressure of the high-pressure fuel passage, and the pressure control chamber is connected via the high-pressure fuel passage. Fuel flows into, the pressure of the pressure control chamber is increased, the valve body is displaced to close the injection hole,
When the fuel pressure of the fuel flowing into the high-pressure fuel passage is lower than the valve opening pressure for opening the valve body, the control unit controls the drive unit so that the outflow passage communicates with the control member. A start control unit (17) for starting a removal process for removing air from at least the fuel outflow chamber;
Before the fuel pressure reaches the valve opening pressure, the control unit controls the driving unit so that the outflow passage is shut off, and the end control unit (17) ends the removal processing. ) and, only including,
The start control unit and the end control unit are configured to switch between a state in which the outflow passage is communicated and a state in which the outflow passage is shut off a plurality of times during the removal process until the fuel pressure reaches the valve opening pressure. . From the time that the outflow passage communicates, the time until the flow of fuel from the pressure control chamber to the fuel outflow chamber in the outflow passage is stopped is defined as outflow time,
The start control unit includes:
Using the fuel pressure, calculate the outflow time,
The fuel injection control device according to claim 1 for controlling the communication time of the outlet passage so as not to exceed the outflow time. After the outflow passage is shut off, the time from when the flow of fuel to the pressure control chamber in the high-pressure fuel passage disappears is defined as the inflow time,
The termination control unit includes:
Using the fuel pressure, calculate the inflow time,
3. The fuel injection control device according to claim 1, wherein the shutoff time of the outflow passage is controlled so as to be equal to or shorter than the inflow time. Fuel injected from the fuel injection valve is used for combustion of the internal combustion engine,
The fuel injection control device according to any one of claims 1 to 3 , wherein the start control unit starts the removal process when the internal combustion engine is started.

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