JP2014139415A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of suppressing unintended valve opening.SOLUTION: The present invention provides an internal combustion engine control device including: a fuel injection valve 30 that includes a needle 72 opening/closing an injection hole 78 and a control chamber 84 controlling a pressure in a valve opening direction to act on the needle 72, and that injects fuel to an internal combustion engine; and a hydraulic control unit 64 that controls the pressure while the internal combustion engine stops to be increased to be equal to or higher than a predetermined value. The internal combustion engine control device of the present invention can suppress unintended opening/closing of the fuel injection valve.

Description

  The present invention relates to a control device for an internal combustion engine.

  A fuel injection valve that injects fuel into an internal combustion engine (engine) opens and closes by raising and lowering a needle. The needle is operated by pressure, for example. Patent Document 1 describes a fuel injection valve that opens and closes by hydraulic pressure in a control chamber. Patent Document 2 describes an invention in which a solenoid valve is closed to suppress a common rail pressure drop. Patent Document 3 describes an invention that increases the force in the valve closing direction applied to the needle using an electromagnetic coil. Patent Document 4 describes an invention that performs pressure relief to reduce fuel injection pressure by letting fuel remaining in a delivery pipe escape to a tank when the engine is stopped. The force in the valve opening direction decreases due to pressure release.

  The hydraulically operated fuel injection valve operates with a balance of pressure applied to the upper and lower sides of the needle. The control chamber pressure and the spring load act as a valve closing force. The fuel pressure and the in-cylinder pressure act as a valve opening force. In ordinary common rail diesel, the control chamber pressure and the fuel pressure are both supplied from the fuel in the common rail.

JP 2009-281298 A JP 2004-324440 A JP 2005-90387 A JP 2004-346904 A

  As described above, both the control chamber pressure and the fuel pressure are supplied from the fuel in the common rail. When the fuel injection valve is not driven, the relationship of control chamber pressure = fuel pressure is maintained. That is, even if the common rail pressure decreases due to a stop of the hydraulic pump or the like, the fuel pressure (valve opening force) also decreases together with the control chamber pressure (valve closing force). Therefore, the possibility of opening the valve unintentionally is small.

  On the other hand, some hydraulic fuel injection valves are individually supplied with control chamber pressure and fuel pressure. When the fuel injection valve is not driven, the control chamber pressure may sometimes be less than the fuel pressure. For example, if the hydraulic pump stops and the control chamber pressure (valve closing force) decreases with the fuel pressure (valve opening force) remaining, the control chamber pressure <fuel pressure. At this time, valve opening may occur unintentionally. Thereby, fuel is injected and fuel consumption deteriorates. For example, valve opening can be suppressed by performing pressure relief as in Patent Document 4. However, it takes a long time to increase the fuel pressure when the engine is restarted. This makes it difficult to start quickly. In view of the above problems, an object of the present invention is to provide a control device for an internal combustion engine that can suppress unintended valve opening.

  The present invention includes a needle that opens and closes a nozzle hole, and a pressurizing unit that applies pressure in the valve closing direction to the needle, and a fuel injection valve that injects fuel into the internal combustion engine, and the pressure during the stop of the internal combustion engine A control device for an internal combustion engine, comprising: a hydraulic control unit that raises the pressure to a predetermined value or more.

  In the above configuration, when it is determined that the internal combustion engine does not restart within the predetermined time, the hydraulic pressure control unit determines that the pressure is increased to a predetermined value or more and the internal combustion engine restarts within the predetermined time. In this case, the hydraulic pressure control unit may be configured not to increase the pressure above the predetermined value.

  In the above configuration, when the pressure becomes less than the predetermined value while the internal combustion engine is stopped, the pressure control may be configured to increase the pressure to the predetermined value or more.

  In the above configuration, the pressurizing unit is a control chamber that stores hydraulic oil, and the hydraulic pressure of the hydraulic oil in the control chamber acts on the needle, and includes a pump that supplies the hydraulic oil to the control chamber. When the pressure becomes less than the predetermined value while the internal combustion engine is stopped, the hydraulic pressure control unit operates the pump by rotating the internal combustion engine to increase the hydraulic pressure to the predetermined value or more. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can suppress the valve opening which is not intended can be provided.

FIG. 1A is a block diagram illustrating an engine according to the first embodiment. FIG. 1B is a functional block diagram illustrating the configuration of the ECU. FIG. 2A is a cross-sectional view illustrating the fuel injection valve when the valve is closed. FIG. 2B is a cross-sectional view illustrating the fuel injection valve when the valve is opened. FIG. 3 is a time chart illustrating the operation of the engine. FIG. 4 is a flowchart illustrating engine control. FIG. 5 is a time chart illustrating the operation of the engine. FIG. 6 is a flowchart illustrating engine control.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a block diagram illustrating an engine according to the first embodiment. As shown in FIG. 1A, an intake pipe 11 and an exhaust pipe 12 are connected to the engine body 10. The intake pipe 11 and the exhaust pipe 12 are connected by a return pipe 14. For example, the engine body 10 is provided with four cylinders 24. The intake pipe 11 is provided with an AFM (Air Flow Meter) 16. The intake pipe 11 supplies air to each cylinder 24. Exhaust gas discharged from the engine body 10 flows through the exhaust pipe 12 and is discharged out of the vehicle. A catalyst 22 and an air-fuel ratio sensor 23 are provided in the exhaust pipe 12. The catalyst 22 purifies nitrogen oxides in the exhaust gas. The air-fuel ratio sensor 23 measures the air-fuel ratio. A part of the exhaust gas passes through the return pipe 14 and is supplied to the cylinder 24 via an EGR (Exhaust Gas Recirculation) cooler 18 and an EGR valve 20.

  The fuel injection valve 30 is provided for each cylinder 24 and injects fuel into the cylinder 24. As the fuel, for example, high-pressure gaseous fuel such as hydrogen fuel can be used. The delivery pipe 32 and the hydraulic oil pipe 34 that are hatched in the drawing are connected to the fuel injection valve 30. The delivery pipe 32 supplies fuel to the fuel injection valve 30. The hydraulic oil pipe 34 supplies hydraulic oil to the fuel injection valve 30. A fuel pressure sensor 36 provided in the delivery pipe 32 measures the pressure (fuel pressure) of the fuel in the delivery pipe 32. The hydraulic oil pressure sensor 38 measures the pressure (hydraulic pressure) of the hydraulic oil in the hydraulic oil pipe 34. As will be described later, the fuel pressure is a valve opening force for opening the fuel injection valve 30, and the oil pressure is a valve closing force for closing the valve.

  A supply pipe 42 and a pressure release line 44 are connected to the delivery pipe 32. The supply pipe 42 is provided with a shutoff valve 46 and a pressure reducing valve 48, and the supply pipe 42 is connected to the fuel tank 50. The fuel is stored in the fuel tank 50. The fuel is supplied from the fuel tank 50 to the supply pipe 42 by the pump 51 and supplied to the delivery pipe 32 through the supply pipe 42. The shutoff valve 46 closes the supply pipe 42 and shuts off the fuel supply. The pressure reducing valve 48 adjusts the fuel pressure to a predetermined pressure. A pressure relief valve 52 is provided in the pressure relief line 44. By opening the pressure relief valve 52, the fuel flows out from the delivery pipe 32 to the pressure relief line 44, and the fuel pressure decreases.

  A pressure relief line 54 is connected to the hydraulic oil pipe 34. A pressure reducing valve 56 is provided in the pressure release line 54. When the pressure reducing valve 56 is opened, the hydraulic oil flows out from the hydraulic oil pipe 34 to the pressure release line 54. As a result, the hydraulic pressure decreases. The pump 40 pumps hydraulic oil from the tank 41 and supplies it to the hydraulic oil pipe 34. As a result, the hydraulic pressure increases.

  An ECU (Engine Control Unit) 60 acquires the air-fuel ratio from the air-fuel ratio sensor 23, acquires the fuel pressure from the fuel pressure sensor 36, and the hydraulic pressure from the hydraulic oil pressure sensor 38. The EUC 60 operates the pumps 40 and 51, the shutoff valve 46, the pressure reducing valves 48 and 56, and the pressure relief valve 52.

  FIG. 1B is a functional block diagram illustrating the configuration of the ECU 60. As shown in FIG. 1B, the ECU 60 functions as a fuel pressure control unit 62 and a hydraulic pressure control unit 64. The fuel pressure control unit 62 controls the opening and closing of the shut-off valve 46, the pressure reducing valve 48, and the pressure relief valve 52, and controls the fuel pressure, thereby changing the fuel injection amount. The hydraulic control unit 64 controls the hydraulic pressure of the hydraulic oil. Details will be described later.

  The configuration of the fuel injection valve 30 will be described. FIG. 2A is a cross-sectional view illustrating the fuel injection valve 30 when the valve is closed. FIG. 2B is a cross-sectional view illustrating the fuel injection valve 30 when the valve is opened.

  As shown in FIGS. 2A and 2B, a needle 72 that is slidable in the axial direction (vertical direction in the drawing) is provided in the nozzle body 70 of the fuel injection valve 30. A sheet portion 72 a is formed at the tip of the needle 72. The needle 72 includes a collar portion 72b. A piston 74 is connected to the proximal end side of the needle 72, and an electromagnetic valve 76 is provided on the proximal end side of the piston 74.

  The nozzle body 70 has a nozzle hole 78, a fuel reservoir chamber 80, a first spring chamber 82, a control chamber 84 (pressurizing portion), a second spring from the distal end side (lower side in the figure) to the proximal end side (upper side). A chamber 86 is provided. A fuel passage 88 is connected to the fuel reservoir 80. The fuel passage 88 is connected to the delivery pipe 32 of FIG. The control chamber 84 is located on the proximal end side of the piston 74 and is connected to the hydraulic oil passage 90. The hydraulic oil passage 90 is connected to the hydraulic oil pipe 34 in FIG. A return passage 92 is connected to the first spring chamber 82 and the control chamber 84. A spring 82 a is provided in the first spring chamber 82. The pressure (fuel pressure) of the fuel in the fuel reservoir 80 acts on the needle 72. The pressure (hydraulic pressure) of the hydraulic oil in the control chamber 84 acts on the piston 74 and acts on the needle 72 via the piston 74. The elastic force of the spring 82a acts on the flange 72b. The fuel pressure is a valve opening force (upward force) that opens the fuel injection valve 30. The hydraulic pressure and the elastic force of the spring 82a are the closing force (downward force) for closing the fuel injection valve 30. The second spring chamber 86 is provided with a spring 86a. The elastic force of the spring 86a acts on the electromagnetic valve 76. As will be described below, the needle 72 opens and closes the nozzle hole 78.

  As shown in FIG. 2A, hydraulic oil is supplied to the control chamber 84 through the hydraulic oil passage 90. The electromagnetic valve 76 is pressed in the distal direction by the elastic force of the spring 86 a and blocks the control chamber 84 and the return passage 92. For this reason, the hydraulic pressure in the control chamber 84 increases. When the sum of the hydraulic pressure and the elastic force of the spring 82a becomes larger than the fuel pressure, the needle 72 is lowered. The injection hole 78 is closed by the seat portion 72 a seating on the inner wall of the nozzle body 70. For this reason, fuel is not injected. That is, the fuel injection valve 30 is closed.

  As shown in FIG. 2B, when the solenoid valve 76 is energized, the solenoid valve 76 moves to the proximal end side. As a result, the control chamber 84 and the return passage 92 are connected. The hydraulic oil flows out from the control chamber 84 into the return passage 92. As a result, the hydraulic pressure decreases. When the sum of the hydraulic pressure and the elastic force of the spring 82a becomes smaller than the fuel pressure, the needle 72 rises. The seat 72 a is separated from the inner wall of the nozzle body 70, so that fuel is injected from the injection hole 78. That is, the fuel injection valve 30 is opened.

  Next, the operation of the engine will be described. Take the case where the engine is stopped and then restarted. FIG. 3 is a time chart illustrating the operation of the engine. In order from the top, the engine speed 10 (engine speed), starter on / off, oil pressure P, pump 40 hydraulic fluid discharge, pressure reducing valve 56 opening / closing, fuel injection pressure, fuel injection amount Represents opening and closing of the shut-off valve 46. A solid line is Example 1, and a broken line is a comparative example. In the comparative example, the control for increasing the hydraulic pressure performed in the first embodiment is not performed.

  As shown in FIG. 3, at the time t1, the rotational speed R becomes R1 or less. At this time, the amount of fuel injected from the fuel injection valve 30 increases. At time t2, the rotational speed R becomes R2 or less. By closing the shutoff valve 46, the supply of fuel to the delivery pipe 32 is stopped, and the supply of fuel to the fuel injection valve 30 is also stopped. As a result, the injection pressure decreases from P1a and maintains P1b or higher. In the comparative example, since the pressure relief valve 52 is opened and the pressure relief is performed when the engine is stopped, the injection pressure is reduced to less than P1b, for example, zero.

  At time t3, the rotational speed R is equal to or less than R3. At this time, the hydraulic control unit 64 increases the discharge amount of the pump 40 to V2a and increases the hydraulic pressure P to P2a. Since the valve closing force increases, the fuel injection valve 30 is closed and the fuel injection amount becomes zero. The engine body 10 rotates by inertia. As the power of the pump 40, the rotational force of the engine can be used. The rotational speed becomes zero at time t4. That is, the engine body 10 stops. At this time, the pump 40 is also stopped.

  At time t5, the starter (not shown in FIG. 1) is turned on. The engine body 10 is restarted. The hydraulic control unit 64 opens the pressure reducing valve 56 and decreases the hydraulic pressure P. At time t6, the rotational speed R reaches R3. The pump 40 operates by the rotation, and the discharge amount becomes V2b smaller than V2a. The hydraulic pressure P is substantially constant. At time t7, the shut-off valve 46 opens. Thereby, fuel is supplied to the delivery pipe 32 and the fuel injection valve 30, and fuel injection is started. The injection amount is, for example, V1. By opening the shut-off valve 46, the injection pressure increases and reaches, for example, P1a at time t8. At time t9, the rotational speed R becomes larger than R3 and then further increases.

  In the comparative example, the hydraulic pressure P decreases to zero. By closing the shut-off valve 46 and opening the pressure relief valve 52 at time t4, the injection pressure is reduced to zero. The injection pressure reaches P1 after restart at a time t9 later than that of the first embodiment. The rotation speed R becomes larger than R3 at a time t10 later than that of the first embodiment.

  FIG. 4 is a flowchart illustrating engine control. As shown in FIG. 4, the fuel pressure control unit 62 acquires the rotation speed R from a rotation speed sensor (not shown), and determines whether the rotation speed R is equal to or less than R1 (step S10). If No, the control ends. In the case of Yes, the fuel pressure control unit 62 performs control to recover the rotation of the engine body 10 (step S11). Specifically, the fuel pressure control unit 62 increases the fuel injection amount at time t1 in FIG. The fuel pressure control unit 62 determines whether the rotation has been recovered (step S12). The recovery of rotation means, for example, that the rotation speed R increases and becomes larger than R1. If yes, the control ends. In No, the fuel pressure control part 62 determines whether the rotation speed R is R2 or less (step S13). If no, step S13 is repeated. In the case of Yes, the fuel pressure control unit 62 decreases the injection pressure (step S14, time t2).

  The hydraulic control unit 64 determines whether restart of the engine can be expected (step S15). The case where restart can be expected is a short time such as an engine stall due to a misoperation of the clutch and gear shift (engine stall), an ECU 60 sending an engine stall request, a hill start, an engine stop due to tire lock in sudden braking, etc. Is a stop. In this case, it is determined to restart within a predetermined time. The case where the restart cannot be expected is a long-time stop such as an engine stall due to a malfunction in the engine such as a spark plug and a throttle valve, or an engine stall due to a collision accident. In this case, it is determined not to restart within a predetermined time. If yes, control returns to step S11. In the case of No, the hydraulic control unit 64 increases the hydraulic pressure (step S16, time t3 to t4).

  The hydraulic control unit 64 determines whether the engine body 10 has been restarted (step S17). If no, step S17 is repeated. In the case of Yes, the hydraulic control unit 64 reduces the hydraulic pressure (step S18, time t5 to t6). The fuel pressure control unit 62 opens the shut-off valve 46 and starts fuel injection (step S19, time t7). After step S19, the control ends.

  According to the first embodiment, the hydraulic control unit 64 increases the hydraulic pressure to P2a before the engine is stopped. While stopping (time t4 to t5), the hydraulic pressure decreases, but P2b or higher is maintained. The sum of the hydraulic pressure P2a and the elastic force and the total of the hydraulic pressure P2b and the elastic force act as valve closing forces, respectively. These valve closing forces are larger than the valve opening force due to the fuel pressure applied to the needle 72. For this reason, the unintended valve opening of the fuel injection valve 30 while the engine is stopped can be suppressed. Therefore, fuel injection is not performed, and deterioration of fuel consumption is suppressed. In the comparative example shown by the dotted line in FIG. 3, the hydraulic pressure decreases to near zero while the engine is stopped. Thereby, since fuel is injected from the fuel injection valve 30, fuel consumption deteriorates. P2a is a value equal to or greater than P2b and can be an arbitrary value.

  In the comparative example, for example, by performing pressure relief, the fuel pressure can be reduced and the valve opening can be suppressed. The injection pressure is reduced to, for example, zero by depressurization. Since the low pressure fuel is injected until the injection pressure rises, the fuel consumption deteriorates. Further, the increase in the injection pressure after the restart is slower than that in the first embodiment. For example, the time when the injection pressure reaches P1a is time t9, which is later than that of the first embodiment. In the comparative example, the rotation speed R exceeds R3 at time t10, which is later than the time t9 in the first embodiment.

  According to the first embodiment, the pressure relief is not performed or the number of pressure reliefs can be reduced. For this reason, the drop of injection pressure is suppressed and fuel consumption improves. Further, when the engine body 10 is restarted, the injection pressure and the injection amount can be quickly increased. As shown at time t3 in FIG. 3, the fuel pressure control unit 62 sets the injection pressure to P1b or higher. P1b is a minimum injectable pressure, for example. The minimum injectable pressure is a minimum pressure for injecting fuel from the fuel injection valve 30. The injection pressure while the engine is stopped is maintained at P1b or higher.

  The pump 40 is operated to increase the hydraulic pressure. In the first embodiment, the pump 40 is operated using the rotation of the engine body 10 as power during a period (t3 to t4) in which the engine is rotating by inertia. When the engine body 10 stops, the pump 40 also stops. Thereby, oil pressure can be raised efficiently.

  When restarting, if the hydraulic pressure is high, the opening of the fuel injection valve 30 is delayed. Therefore, quick restart becomes difficult. If the restart can be expected, the hydraulic control unit 64 does not increase the hydraulic pressure to P2a (Yes in step S15 in FIG. 4). This enables a quick restart. When it is expected not to restart, the oil pressure control unit 64 increases the oil pressure, so that deterioration of fuel consumption is suppressed. The hydraulic pressure control unit 64 receives signals from, for example, sensors (not shown) that detect the states of the engine body 10, the clutch, the gear, and the brake, and determines whether restart can be expected within a predetermined time. As a case where the restart cannot be expected, for example, an idle stop, an engine stop during an eco-run in a hybrid vehicle, or the like may be included.

  For example, the injection pressure may be reduced at time t2 by depressurization using the depressurization line 44. In addition to the pressure reducing valve 56, for example, the solenoid valve 76 may be opened to such an extent that the needle 72 is not operated. When the solenoid valve 76 is opened, the hydraulic oil leaks and the hydraulic pressure is lowered. Alternatively, the injection pressure may be reduced by closing the shutoff valve 46 and performing fuel injection. The injection pressure may be reduced to P1b.

  The second embodiment is an example in which the hydraulic pressure is increased while the engine is stopped. The configuration of the engine and the fuel injection valve 30 is the same as that of the first embodiment.

  FIG. 5 is a time chart illustrating the operation of the engine. The example of FIG. 5 is an example in which the engine stops according to the idle stop request. The stop times t4 to t5 are longer than the example of FIG. In FIG. 5, a part of time t4 to t5 is omitted. A chart of an idle stop request is described above the rotation speed. Description of operations common to those in FIG. 3 is omitted.

  At time t1, the ECU 60 turns on the idle stop request. The engine speed starts to decrease. At time t11 between times t4 and t5, the oil pressure drops below P2b. At this time, the hydraulic control unit 64 turns on the starter and rotates the engine body 10. As a result, the pump 40 operates and the hydraulic pressure rises to P2c, which is a value equal to or greater than P2b. At time t12, the engine body 10 stops and the pump 40 also stops. At time t5, the ECU 60 turns off the idle stop request. As a result, the engine body 10 is restarted.

  FIG. 6 is a flowchart illustrating engine control. Description of control common to FIG. 4 is omitted. After step S16, the hydraulic control unit 64 determines whether the hydraulic pressure P is less than P2b (step S20). In No, it progresses to Step S17. In the case of Yes, the hydraulic control unit 64 increases the hydraulic pressure (step S21, times t11 and t12). After step S21, steps S17 to S19 are performed.

  If the hydraulic pressure decreases while the engine is stopped, the fuel injection valve 30 may open unintentionally. According to the second embodiment, even when the engine is stopped (time t4 to t5), the engine body 10 is temporarily rotated to increase the hydraulic pressure. Thereby, the unintended opening of the fuel injection valve 30 is suppressed. Thereby, deterioration of fuel consumption is suppressed. The engine body 10 may be motored at the minimum number of revolutions required for the operation of the pump 40. The hydraulic pressures P2a, P2b, and P2c are predetermined values that can be arbitrarily determined according to, for example, the size of the fuel injection valve 30, the type of fuel used, and the like.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Engine body 24 Cylinder 32 Delivery pipe 34 Hydraulic oil pipe 30 Fuel injection valve 40, 51 Pump 60 ECU
62 Fuel Pressure Control Unit 64 Hydraulic Control Unit 72 Needle 78 Injection Hole 84 Control Chamber 100 Internal Combustion Engine

Claims (4)

A fuel injection valve for injecting fuel into the internal combustion engine, including a needle that opens and closes the nozzle hole, and a pressurizing unit that applies pressure in the valve closing direction to the needle;
A control unit for an internal combustion engine, comprising: a hydraulic control unit configured to increase the pressure to a predetermined value or more while the internal combustion engine is stopped. When it is determined that the internal combustion engine does not restart within the predetermined time, the hydraulic control unit increases the pressure to a predetermined value or more,
2. The control device for an internal combustion engine according to claim 1, wherein when it is determined that the internal combustion engine is restarted within the predetermined time, the hydraulic pressure control unit does not increase the pressure to the predetermined value or more.   The control device for an internal combustion engine according to claim 1 or 2, wherein when the pressure becomes less than the predetermined value while the internal combustion engine is stopped, the pressure control increases the pressure to the predetermined value or more. The pressurizing unit is a control chamber that stores hydraulic oil, and the hydraulic pressure of the hydraulic oil in the control chamber acts on the needle,
A pump for supplying the hydraulic oil to the control chamber;
When the pressure becomes less than the predetermined value while the internal combustion engine is stopped, the hydraulic pressure control unit operates the pump by rotating the internal combustion engine to increase the hydraulic pressure to the predetermined value or more. The control device for an internal combustion engine according to claim 3.

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