JP2017025812A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device of an internal combustion engine which can easily discharge non-fuel which is mixed into fuel in a pressure accumulator.SOLUTION: A fuel injection device of an internal combustion engine comprises: a fuel tank 41 which stores the fuel of an engine 2 in a constant-pressure state; a low-pressure pump 42 which pressure-sends the fuel stored in the fuel tank 41 at relatively-low pressure; a fuel line 43 for making the fuel which is pressure-sent by the low-pressure pump 42 circulate to a high-pressure pump 44; the high-pressure pump 44 which mechanically boosts the fuel which is sent through the fuel line 43, and sends it to a delivery 45; the delivery 45 for accumulating the fuel which is boosted by the high-pressure pump 44 while maintaining the pressure of the fuel; and an ECU 3 which makes the fuel tank 41 release pressure in the delivery 45, and discharge non-fuel and the fuel in the delivery 45 when the ECU determines that the non-fuel is mixed into the delivery 45.SELECTED DRAWING: Figure 1

Description

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

  A fuel injection device for an internal combustion engine includes a low-pressure pump that pumps fuel stored in a fuel tank, a fuel pipe that distributes fuel pumped by the low-pressure pump, and a high-pressure pump that further pressurizes fuel supplied from the fuel pipe. And a pressure accumulator such as a delivery or a common rail that holds the fuel pressurized by the high pressure pump at a high pressure, and an injector that injects the fuel held by the pressure accumulator into the combustion chamber of the internal combustion engine.

  In such a fuel injection device for an internal combustion engine, when non-fuel such as air, fuel vapor, or water is mixed in an injector, a pressure accumulator, or a fuel pipe, the fuel is injected from the injector into the combustion chamber in a state containing non-fuel. Is done. In this case, an appropriate amount of fuel is supposed to be injected, but since it contains non-fuel, there is a problem that the amount of fuel is insufficient and the combustion state deteriorates.

  In particular, when water is mixed, the water is dispersed in the pressurized fuel and does not stay in a part like fuel vapor or air. For this reason, the water stays in the accumulator, which causes problems such as engine stall and poor start of the internal combustion engine.

  Patent Document 1 proposes that fuel leakage from the injector and generation of fuel vapor are prevented by releasing the pressure in the fuel pipe through the return pipe when the internal combustion engine is stopped.

  However, the method of Patent Document 1 cannot be applied to a fuel injection device for an internal combustion engine that employs a returnless pipe that does not have a return pipe that returns excess fuel from the accumulator to the fuel tank.

  Usually, in an internal combustion engine that employs returnless piping, measures are taken using a filter or a gas-liquid separator as in Patent Document 2.

  In Patent Document 2, a device for separating water and fuel is mounted, the separated water is stored in a water storage tank, the water mixed in the fuel tank is separated, and water is prevented from entering the pressure accumulator and the injector. It has been proposed.

Japanese Patent Laid-Open No. 11-190263 JP 2013-174236 A

  However, in the fuel injection device for an internal combustion engine as described in Patent Document 2, the cost increases because the above-described filter or gas-liquid separation device is employed. Regular maintenance is also required.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device for an internal combustion engine that can easily discharge non-fuel mixed in the fuel in the pressure accumulator.

  An aspect of the invention of a fuel injection device for an internal combustion engine that solves the above-described problem is a pressure accumulator that distributes and supplies fuel to each combustion chamber of the internal combustion engine while holding the fuel at a predetermined pressure, A high-pressure pump that supplies fuel pressurized to pressure, and whether or not non-fuel is mixed in the accumulator based on the state of the internal combustion engine, and determined that non-fuel is mixed in the accumulator In this case, a controller for releasing the pressure in the pressure accumulator and discharging non-fuel and fuel in the pressure accumulator to the fuel tank is provided.

  Thus, according to one aspect of the present invention, non-fuel mixed in the fuel in the pressure accumulator can be easily discharged.

FIG. 1 is a diagram showing a fuel injection device for an internal combustion engine according to an embodiment of the present invention, and is a conceptual block diagram thereof. FIG. 2 is a diagram showing a fuel injection device for an internal combustion engine according to an embodiment of the present invention, and is a cross-sectional view of the high-pressure pump in the plunger ascending / descending direction. FIG. 3 is a diagram showing a fuel injection device for an internal combustion engine according to an embodiment of the present invention, and is a flowchart showing the non-fuel discharge processing procedure. FIG. 4 is a view showing a fuel injection device for an internal combustion engine according to another aspect of the embodiment of the present invention, and is a flowchart showing the non-fuel discharge processing procedure.

  Hereinafter, a fuel injection device for an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, a vehicle 1 equipped with an internal combustion engine fuel injection apparatus according to an embodiment of the present invention includes an internal combustion engine type engine 2 and an ECU 3 as a control unit.

  The engine 2 is constituted by a four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston reciprocates twice within the cylinder.

  The piston housed in each cylinder is connected to the crankshaft via a connecting rod. The connecting rod converts the reciprocating motion of the piston into the rotational motion of the crankshaft.

  Therefore, the engine 2 drives the vehicle 1 by causing the piston to reciprocate by burning a mixture of fuel and air in the combustion chamber 21 in the cylinder and rotating the crankshaft via the connecting rod. It is designed to generate power.

  A starter 22 is connected to the crankshaft of the engine 2 via a reduction gear (not shown). The starter 22 cranks the engine 2 by rotating a crankshaft via a reduction gear.

  The ignition switch 31 is switched between an on state and an off state by operating an ignition key (not shown). When the ignition switch 31 is on, power is supplied to the ECU 3, and when the ignition switch 31 is off, power is not supplied to the ECU 3.

  The starter switch 32 is switched between an on state and an off state by operating an ignition key (not shown). When the starter switch 32 is on, power is supplied to the starter 22, and when the starter switch 32 is off, power is not supplied to the starter 22.

  When the starter switch 32 is turned on by operating the ignition key, the starter 22 is supplied with power from a battery (not shown) and cranks the engine 2. When the starter switch 32 is turned off by the operation of the ignition key, the starter 22 is turned off from the battery and stops the cranking of the engine 2.

  The fuel tank 41 stores the fuel of the engine 2 in a normal pressure state. The fuel stored in the fuel tank 41 is pumped by the low-pressure pump 42 and injected into the combustion chamber 21 from the injector 46 provided in each cylinder via the fuel line 43, the high-pressure pump 44 and the delivery 45.

  The low-pressure pump 42 is an electric pump and is driven by electric power supplied from a battery (not shown). The low pressure pump 42 sends fuel at a relatively low pressure. The low-pressure pump 42 is connected to the ECU 3 and is driven and controlled by the ECU 3.

  The fuel line 43 distributes the fuel pumped by the low pressure pump 42 to the high pressure pump 44.

  The high pressure pump 44 mechanically boosts the fuel sent from the low pressure pump 42 through the fuel line 43 and sends it to the delivery 45.

  The delivery 45 stores the fuel pressurized by the high pressure pump 44 while maintaining the pressure. A plurality of injectors 46 corresponding to each cylinder of the engine 2 are connected to the delivery 45. The fuel stored in the delivery 45 is injected into the combustion chamber 21 when the injector 46 opens. The delivery 45 constitutes the pressure accumulator of the present invention.

  The injector 46 is connected to the ECU 3, and the injection timing of the fuel into the combustion chamber 21 of each corresponding cylinder is individually adjusted under the control of the ECU 3. The delivery 45 is provided with a fuel pressure sensor 47. The fuel pressure sensor 47 detects the pressure in the delivery 45. The ECU 3 can calculate the fuel injection time and the fuel injection amount based on the valve opening time and the fuel pressure of the injector 46.

  The ECU 3 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  A program for causing the computer unit to function as the ECU 3 is stored in the ROM of the ECU 3 together with various control constants and various maps. That is, the computer unit functions as the ECU 3 when the CPU executes a program stored in the ROM.

  In this embodiment, in addition to the fuel pressure sensor 47 described above, various sensors such as a crank angle sensor 23 and an accelerator position sensor (not shown) are connected to the input port of the ECU 3. The crank angle sensor 23 detects the rotation angle of the crankshaft of the engine 2. The ECU 3 calculates an engine speed that is the engine speed of the engine 2 based on the detection result input from the crank angle sensor 23. The accelerator position sensor detects an accelerator opening representing an operation amount of the accelerator pedal.

  On the other hand, various control objects such as a low pressure pump 42, a high pressure pump 44, and an injector 46 are connected to the output port of the ECU 3.

  The configuration of the high-pressure pump 44 will be described with reference to FIG. FIG. 2 is a sectional view of the plunger 55 of the high-pressure pump 44 in the ascending / descending direction.

  The high-pressure pump 44 includes a pump main body 51, an electromagnetic spill valve 52, a tappet 53, a tappet spring 54, a plunger 55, and an electromagnetic valve 56.

  The pump body 51 is fixed to a pump mounting portion 2p provided in the engine 2, and houses an electromagnetic spill valve 52 and a plunger 55 so as to be movable.

  Also, the pump body 51 is connected to the upstream fuel line 43 in the direction in which the fuel flows, and sucks in the fuel, the discharge port 51t connected to the downstream delivery 45 and discharges the fuel, the fuel And a boosting chamber 51s for boosting the pressure. An electromagnetic valve 56 is provided at the discharge port 51t.

  The pressurizing chamber 51 s is composed of a space defined by the pump body 51 and the end face of the plunger 55. The movement that the plunger 55 narrows the boosting chamber 51s is raised, and the movement that the plunger 55 widens the boosting chamber 51s is lowered.

  The end of the plunger 55 opposite to the end housed in the pump body 51 is connected to the tappet 53. A tappet spring 54 is accommodated between the tappet 53 and the pump mounting portion 2p. The tappet spring 54 is accommodated so as to press the tappet 53 in the direction opposite to the pump mounting portion 2p.

  The tappet 53 is in contact with a substantially square pump cam 24 provided on the camshaft of the engine 2. The tappet 53 is pressed by the tappet spring 54 and presses the pump cam 24 with a predetermined pressing force.

  The camshaft of the engine 2 is connected to the crankshaft of the engine 2 by a power transmission member such as a chain (not shown), and is rotated by the rotation of the crankshaft.

  Therefore, the pump cam 24 rotates with the rotation of the crankshaft of the engine 2 and moves the tappet 53 up and down. The plunger 55 is raised and lowered together with the tappet 53.

  The electromagnetic spill valve 52 includes a valve 52v and an electromagnet (not shown). The electromagnet is connected to the ECU 3, and when the electromagnet is energized by the ECU 3, the valve 52v is sucked and the suction port 51k is closed. That is, the electromagnetic spill valve 52 is a normally open type valve that opens the valve 52v when not energized.

  Conversely, when the ECU 3 is de-energized, the valve 52v is separated and the suction port 51k is opened.

  The electromagnetic valve 56 includes a spring 56s, a valve 56v, and an electromagnet (not shown). The valve 56v is pressed in the direction opposite to the fuel flow direction of the discharge port 51t by the spring 56s, and closes the discharge port 51t. And if it presses from the discharge port 51t side at a pressure higher than the pressing force of the spring 56s, the valve 56v will be in an open state.

  The electromagnet of the electromagnetic valve 56 is connected to the ECU 3, and when the electromagnet is energized by the ECU 3, the valve 56v is attracted in the direction opposite to the pressing direction of the spring 56s to open the discharge port 51t.

  In such a high-pressure pump 44, if the electromagnetic spill valve 52 is closed when the plunger 55 is raised, the fuel in the pressure increasing chamber 51s is boosted by the raising of the plunger 55. When the pressure of the fuel is increased and becomes higher than the pressing force of the spring 56s of the solenoid valve 56, the fuel is discharged into the delivery 45 from the discharge port 51t.

  The high-pressure pump 44 raises the sucked fuel to a high pressure in the pressure-increasing chamber 51 s by raising the plunger 55. The pressurized fuel flows through the delivery 45 from the discharge port 51t and is supplied to the injector 46.

  The amount of pressure increase of the fuel by raising the plunger 55 is controlled by adjusting the opening / closing timing of the electromagnetic spill valve 52 with respect to the raising / lowering timing of the plunger 55.

  In the present embodiment, the ECU 3 determines whether there is any mixture other than fuel such as water, air, or fuel vapor in the delivery 45. When it is determined that there is a mixture other than fuel in the delivery 45, the ECU 3 releases the pressure in the delivery 45 and discharges the contaminant in the delivery 45.

  The ECU 3 determines that there is a mixture other than fuel in the delivery 45 when the engine speed does not exceed the threshold value within a predetermined time after the starter switch 32 is turned on and cranking by the starter 22 is started. . The predetermined cranking time and the engine speed threshold are obtained in advance by experiments or the like and stored in the ROM of the ECU 3. The target rotational speed is preferably set to an engine rotational speed that indicates that the engine 2 has completely exploded. Note that, regardless of the engine speed, if the cranking time is longer than the predetermined time, it may be determined that there is a mixture other than fuel in the delivery 45.

  When the ECU 3 determines that there is a mixture other than fuel in the delivery 45, the ignition switch 31 is turned off, and the electromagnetic spill valve 52 and the electromagnetic valve 56 of the high-pressure pump 44 are opened at the time of self-shutoff to end the operation. The high-pressure pump 4 is fully opened for a predetermined time to release the pressure in the delivery 45, and the fuel in the delivery 45 is caused to flow backward and discharged to the fuel tank 41.

  Non-fuel discharge processing by the fuel injection device for an internal combustion engine according to the present embodiment configured as described above will be described with reference to FIG. The non-fuel discharge process described below is started when the ECU 3 starts operating, and is executed at a preset time interval.

  In step S11, the ECU 3 determines whether or not the ignition switch 31 is on. When it is determined that the ignition switch 31 is in the on state, in step S12, the ECU 3 determines whether or not cranking is being performed with the starter switch 32 in the on state.

  When it is determined that the cranking is being performed, in step S13, the ECU 3 has the engine speed lower than the threshold and the cranking time that is an elapsed time from the start of cranking is longer than the predetermined time. It is determined whether or not.

  When it is determined that the engine speed is lower than the threshold value and the cranking time is longer than the predetermined time, in step S14, the ECU 3 sets “established” in the determination result of non-fuel mixture in delivery.

  If it is determined in step S11 that the ignition switch 31 is not on, or if it is determined that cranking is not performed in step S12, or if the engine speed is not lower than the threshold value in step S13 or the cranking time When it is determined that it is not longer than the predetermined time, in step S15, the ECU 3 determines whether or not the ignition switch 31 is in an OFF state. When it is determined that the ignition switch 31 is not in the off state, the ECU 3 ends the process.

  When it is determined that the ignition switch 31 is in the OFF state, in step S16, the ECU 3 determines whether or not “established” is set in the non-delivery non-fuel mixture determination result. When it is determined that “establishment” is not set in the determination result of non-delivery in the delivery, the ECU 3 ends the process.

  If it is determined that “established” is set in the non-delivery in-delivery determination result, in step S17, the ECU 3 opens the high-pressure pump 4 for a predetermined time and ends the process.

  As another aspect of the present embodiment, the ECU 3 determines that the fuel injection time from the start of cranking is longer than a predetermined time after the starter switch 32 is turned on and the cranking by the starter 22 is started. When the fuel injection amount from the start is larger than the threshold value, it is determined that there is a mixture other than fuel in the delivery 45.

  Non-fuel discharge processing by the fuel injection device for an internal combustion engine according to another aspect of the present embodiment will be described with reference to FIG. The non-fuel discharge process described below is started when the ECU 3 starts operating, and is executed at a preset time interval.

  Similar to the above-described embodiment, in step S11 to step S12, the ECU 3 determines whether or not the ignition switch 31 is in an on state and whether or not cranking is being performed, and the ignition switch 31 is in an on state. If it is determined that cranking has been performed, it is determined in step S23 whether the fuel injection time is longer than a predetermined time or the fuel injection amount after cranking is started is greater than a threshold value. Determine.

  When it is determined that the fuel injection time is longer than the predetermined time or the fuel injection amount after the cranking is started is greater than the threshold value, in step S14, the ECU 3 determines that the result of the determination of non-fuel mixture in delivery is “established”. Set.

  Thereafter, as in the above-described embodiment, in step S15, the ECU 3 determines whether or not the ignition switch 31 is in an off state. If the ignition switch 31 is not in an off state, the process is terminated.

  If it is determined that the ignition switch 31 is in the OFF state, in step S16, the ECU 3 determines whether “established” is set in the non-delivery non-fuel mixing determination result, and the non-delivery non-fuel mixing determination result is determined. If it is determined that “Established” is set, in step S17, the high-pressure pump 4 is fully opened for a predetermined time, and the process is terminated.

  In addition, in this embodiment, although the case where the pressure accumulator was the delivery 45 was shown, even when a pressure accumulator is a common rail, it can implement similarly.

  Alternatively, the number of failed engine 2 starts may be counted, and the mixture of non-fuel may be determined in consideration of the number of failed engine 2 startups. The prescribed time or threshold value shown may be set strictly. By doing so, the non-fuel in the delivery 45 can be easily discharged.

  Further, in this embodiment, when the engine speed is lower than the threshold value within a predetermined time or when the cranking time is longer than the predetermined time, it is determined that there is a mixture other than fuel in the delivery 45. In another aspect of the present embodiment, when the fuel injection time is longer than the predetermined time or when the fuel injection amount is larger than the threshold value, it is determined that there is a mixture other than fuel in the delivery 45. It may be determined using one of these, or a plurality of these conditions may be determined, and it may be determined that there is a mixture other than fuel in the delivery 45 when any one of them is satisfied.

  Thus, in the above-described embodiment, when it is determined that non-fuel is mixed in the delivery 45, the pressure in the delivery 45 is released and the non-fuel and fuel in the delivery 45 are discharged to the fuel tank 41. An ECU 3 is provided.

  Thus, when it is determined that non-fuel is mixed in the delivery 45, the non-fuel and fuel in the delivery 45 are discharged to the fuel tank 41. For this reason, the non-fuel mixed in the fuel in the delivery 45 can be easily discharged.

  In addition, the ECU 3 releases the pressure in the delivery 45 by opening the electromagnetic spill valve 52 and the electromagnetic valve 56 provided in the high-pressure pump 44.

  Thereby, the electromagnetic spill valve 52 and the electromagnetic valve 56 provided in the high-pressure pump 44 are opened, and the pressure in the delivery 45 is released. For this reason, even in an internal combustion engine that employs returnless piping, non-fuel mixed in the fuel in the accumulator can be easily discharged.

  Further, the ECU 3 determines that non-fuel is mixed in the delivery 45 when the engine speed after a predetermined time has elapsed is lower than the predetermined speed during cranking for starting the engine 2.

  Thereby, when the engine 2 does not completely explode during a predetermined time, it is determined that the non-fuel is mixed in the delivery 45. For this reason, it can be suitably determined that non-fuel is mixed in the delivery 45.

  Further, the ECU 3 determines that non-fuel is mixed in the delivery 45 when the cranking time for starting the engine 2 is longer than a predetermined time.

  Thereby, when cranking does not end within a predetermined time, it is determined that non-fuel is mixed in the delivery 45. For this reason, it can be suitably determined that non-fuel is mixed in the delivery 45.

  In addition, the ECU 3 determines that non-fuel is mixed in the delivery 45 when the fuel injection amount is larger than the threshold during cranking for starting the engine 2.

  As a result, when the cranking is not completed even though the fuel is injected more than the delay determination injection amount, it is determined that the non-fuel is mixed in the delivery 45. For this reason, it can be suitably determined that non-fuel is mixed in the delivery 45.

  Further, the ECU 3 determines that non-fuel is mixed in the delivery 45 when the fuel injection time is longer than a predetermined time during cranking for starting the engine 2.

  Thereby, when the cranking does not end within the predetermined fuel injection time, it is determined that non-fuel is mixed in the delivery 45. For this reason, it can be suitably determined that non-fuel is mixed in the delivery 45.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 vehicle 2 engine (internal combustion engine)
3 ECU (control unit)
4 High Pressure Pump 23 Crank Angle Sensor 31 Ignition Switch 32 Starter Switch 41 Fuel Tank 42 Low Pressure Pump 43 Fuel Line 44 High Pressure Pump 45 Delivery (Accumulator)
46 Injector 52 Solenoid spill valve 56 Solenoid valve

Claims (6)

An accumulator that distributes and supplies fuel to each combustion chamber of the internal combustion engine while holding the fuel at a predetermined pressure;
A high pressure pump for supplying fuel pressurized to a predetermined pressure to the accumulator;
When it is determined whether or not non-fuel is mixed in the pressure accumulator based on the state of the internal combustion engine, and when it is determined that non-fuel is mixed in the pressure accumulator, the pressure in the pressure accumulator is A fuel injection device for an internal combustion engine, comprising: a controller that opens and discharges the non-fuel and the fuel in the pressure accumulator to a fuel tank.   2. The fuel injection device for an internal combustion engine according to claim 1, wherein the control unit releases a pressure in the accumulator by opening a valve provided in the high-pressure pump.   In the cranking for starting the internal combustion engine, the control unit determines that non-fuel is mixed in the pressure accumulator when the engine speed of the internal combustion engine after a predetermined time has elapsed is lower than a predetermined speed. The fuel injection device for an internal combustion engine according to claim 1 or 2.   The control unit determines that non-fuel is mixed in the pressure accumulator when cranking for starting the internal combustion engine and the cranking time of the internal combustion engine is longer than a predetermined time. 2. A fuel injection device for an internal combustion engine according to 1.   The control unit determines that non-fuel is mixed in the pressure accumulator when a fuel injection amount of the internal combustion engine is larger than a predetermined amount during cranking for starting the internal combustion engine. 2. A fuel injection device for an internal combustion engine according to 1.   The said control part determines that the non-fuel is mixed in the said accumulator when the fuel injection time of the said internal combustion engine is longer than predetermined time at the time of cranking which starts the said internal combustion engine. 2. A fuel injection device for an internal combustion engine according to 1.

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