JP4091889B2 - Engine fuel injector - Google Patents

Description

  The present invention relates to an engine fuel injection device.

As a fuel injection device for an engine, there is a fuel injection device that pressurizes fuel in a fuel tank with a high-pressure pump and stores it in a common rail, and injects the high-pressure fuel from the common rail into a combustion chamber of the engine via a fuel injector. When gas fuel is used, fuel vaporized gas leaks from the fuel injector nozzle when the engine is stopped, and the leaked vaporized gas accumulates in the combustion chamber, causing abnormal combustion when the engine is started. On the other hand, there is one that forms a purge line that collects the common rail fuel into the purge tank via the purge control valve when the engine is stopped. This is when the common rail fuel temperature exceeds the set temperature when the engine is stopped. The common rail fuel is collected by opening the purge control valve (for example, Patent Document 1).
JP 2003-56393 A

  In such a fuel injection device, it is estimated whether the fuel temperature in the fuel injector has reached the critical temperature from the fuel temperature of the common rail, and the purge control valve is opened. In this case, the common rail, the fuel injector, If there is a difference in level, it is difficult to estimate the critical temperature, and even though the fuel in the fuel injector does not evaporate, the purge control valve is opened and the common rail fuel is recovered. Otherwise, the fuel heat flow may not reach the common rail, and the opening of the purge control valve may be delayed, causing fuel vaporized gas to leak from the nozzle portion of the fuel injector into the combustion chamber.

  An object of the present invention is to solve such problems by increasing the closing force of a needle valve of a fuel injector when the engine is stopped.

  According to a first aspect of the present invention, there is provided an engine fuel injection device for injecting high-pressure fuel from a fuel injector, wherein an electromagnetic coil for increasing a needle valve seating load for increasing a valve closing force of a needle valve of the fuel injector is provided. And a control circuit for operating the device.

According to a second invention, in the first invention, the needle valve of the fuel injector opens and closes the nozzle portion of the fuel injector by opening and closing the valve closing pressure chamber .

  According to a third aspect, in the first aspect, the control circuit operates the electromagnetic coil for a predetermined time after the engine is stopped.

  According to a fourth invention, in the first invention, a purge line for collecting fuel via a purge control valve is formed on a common rail that guides fuel boosted by a high-pressure pump to a fuel injector, and the control circuit is configured to stop the engine Thereafter, the purge control valve is opened after operating the electromagnetic coil for a predetermined time.

  According to a fifth invention, in the first invention, the fuel is a liquefied gas.

  In the first invention, when the engine is stopped, it is possible to reliably prevent the fuel in the fuel injector from being vaporized at a high temperature and leaking from the nozzle portion of the fuel injector to the combustion chamber. Gas does not cause abnormal combustion.

  In the second invention, the fuel injector is opened and closed by opening and closing the valve closing pressure chamber of the needle valve. When the engine is stopped, the fuel in the fuel injector is vaporized at a high temperature, and the nozzle of the fuel injector is transferred to the combustion chamber. It can be surely prevented from leaking.

  In the third aspect of the invention, when the engine is restarted during a predetermined time after the engine is stopped, the engine can be restarted promptly.

  In the fourth aspect of the invention, when the engine is not operated for a long time after the engine is stopped, the fuel in the common rail and the fuel injector can be recovered to reliably prevent the vaporized gas from accumulating in the common rail and the fuel injector. When starting the engine, the fuel injection from the fuel injector can be performed promptly and appropriately.

  FIG. 1 is a cross-sectional view of the fuel injector 1, and FIG. 2 is a configuration diagram of the fuel injection device.

  As shown in FIG. 1, the fuel injector 1 is provided with a needle valve 3 in a main body 2.

  The inner wall of the distal end of the main body 2 is formed on a seating surface 4 on which the tapered tip of the needle valve 3 is seated, and a nozzle hole 5 is opened at the center of the seating surface 4. Around the needle valve 3 is formed a fuel chamber 6 into which the high-pressure fuel of the common rail 17 is guided.

  A piston portion 7 is provided at the proximal end of the needle valve 3, and the piston portion 7 is slidably inserted into a guide portion between the valve chamber 7 and a valve closing pressure chamber 8 formed at the back of the fuel chamber 6. A communication groove 10 that communicates the fuel chamber 6 and the valve closing pressure chamber 8 is formed in the portion 7. A return spring 11 that biases the needle valve 3 in the closing direction via the piston portion 7 is interposed in the valve closing pressure chamber 8.

  The outlet of the valve closing pressure chamber 8 is connected to the fuel return passage 13 via the outlet passage 12, and an electromagnetic valve 14 for opening and closing the outlet of the valve closing pressure chamber 8 is provided.

  A ring portion 15 is formed near the piston portion 7 of the needle valve 3, and the seat portion of the needle valve 3 is increased around the fuel chamber 6 of the main body 2 by attracting the ring portion 15 by electromagnetic force. An electromagnetic coil 16 is interposed.

  When the electromagnetic valve 14 is opened, the valve closing pressure chamber 8 is opened, the needle valve 3 is lifted by the fuel pressure in the fuel chamber 6, the nozzle hole 5 is opened, and fuel is injected. The fuel in the valve closing pressure chamber 8 is discharged from the outlet passage 12 to the fuel return passage 13 by the backward movement of the piston portion 7 and returned to the fuel tank (described later).

  When the electromagnetic valve 14 is closed, the valve closing pressure chamber 8 is closed, the fuel in the fuel chamber 6 is guided to the valve closing pressure chamber 8 through the communication groove 10, and the pressure applied to the piston portion 7 causes the needle valve 3. Is seated, the nozzle hole 5 is closed, and fuel injection is terminated.

  When the engine is stopped (the solenoid valve 14 is closed) and the electromagnetic coil 16 is operated, the ring portion 15 of the needle valve 3 seated on the seating surface 4 is attracted by the electromagnetic force, and the needle valve 3 The seating load is increased.

  In FIG. 2, 20 is an engine combustion chamber, and 21 is a fuel tank for liquefied gas fuel.

  The fuel in the fuel tank 21 is pressurized to a predetermined high pressure by the high pressure pump 22 and sent to the common rail 17. The high-pressure fuel in the common rail 17 is introduced into the fuel injector 1 through the distribution passage 23.

  The common rail 17 is formed with a purge line for recovering the fuel of the common rail 17 to the purge tank 25 via the purge control valve 24. The fuel recovered in the purge tank 25 is a pressure pump 26 for regenerating purge gas when the engine is operated. And is returned to the fuel tank 21 side.

  The control circuit 30 controls the opening and closing of the solenoid valve 14 of the fuel injector 1 so that the required amount of fuel is injected from the fuel injector 1 at the required injection timing during engine start-up and operation, and when the engine is stopped, The operation of the electromagnetic coil 16 of the fuel injector 1 is controlled.

  In this case, the electromagnetic coil 16 is operated for a predetermined time T (for example, several hours) from the time when the engine is stopped (provided that the engine is continuously stopped), and then the operation is terminated. At the end of this time, the purge control valve 24 is opened to collect the fuel of the common rail 17 in the purge tank 25 (provided that the engine is stopped), and the pressurizing pump 26 is turned on during the subsequent engine operation. Control is performed to drive the regenerative liquefied gas back to the fuel tank 21 side.

  FIG. 3 shows a control flow when the engine is stopped. When the engine stops, the engine stop time is determined in S1.

  When the engine stop time is equal to or shorter than the predetermined time T, the electromagnetic coil 16 for increasing the needle valve seating load of the fuel injector 1 is energized in S2.

  In S3, it is determined whether or not the key is turned on for restarting the engine. If the key is turned on for restarting the engine, in S4, the electromagnetic coil 16 for increasing the needle valve seating load of the fuel injector 1 is applied. The energization is turned off, the engine is started in S8, and the process is terminated.

  On the other hand, when the engine stop time exceeds the predetermined time T, the purge mechanism is turned on (purge control valve 24 is opened) in S5 (the electromagnetic coil 16 for increasing the needle valve seating load of the fuel injector 1 is turned off).

  In S6, it is determined whether the key for engine restart is turned on. If the key for engine restart is turned on, the purge mechanism is turned off (purge control valve 24 is closed) in S7, and S8 is turned on. The engine is started and the process is terminated.

  Due to such a configuration, it is possible to prevent the fuel in the fuel injector 1 from being vaporized at a high temperature and leaking from the nozzle portion of the fuel injector 1 to the combustion chamber 20 when the engine is stopped.

  That is, when the engine is stopped, the seating load of the needle valve 3 is increased by energizing the electromagnetic coil 16 of the fuel injector 1, so that it is possible to reliably prevent the fuel vaporized gas from leaking from between the seating surface 4. The energization of the electromagnetic coil 16 of the fuel injector 1 is performed for a predetermined time.

  Therefore, when the engine is started, abnormal combustion is not caused by the leaked vaporized gas. Further, when the engine is restarted in a short time after the engine is stopped, the high-pressure fuel can be immediately supplied to the fuel injector 1 by driving the high-pressure pump 22, and the engine can be restarted quickly. .

  On the other hand, when the predetermined time has elapsed after the engine is stopped (the engine is stopped), the purge control valve 24 is opened and the fuel in the common rail 17 is collected in the purge tank 25. The fuel recovered in the purge tank 25 is liquefied by driving the pressure pump 26 for purging the purge gas during the operation of the engine and returned to the fuel tank 21 side.

  FIG. 4 shows the fuel purge operation of the common rail 17, and FIG. 5 shows the fuel regeneration and return operations of the purge tank 25.

  Therefore, when the engine is not operated until the next day after the engine is stopped, the fuel in the common rail 17 and the fuel injector 1 is recovered in the purge tank 25, and it is ensured that vaporized gas accumulates in the common rail 17 and the fuel injector 1. When the engine is subsequently started, the fuel injection from the fuel injector 1 can be promptly and appropriately performed.

  The operation and operation time of the electromagnetic coil 16 and the purge control valve 24 of the fuel injector 1 may be set by the driver by providing setting means (switches or the like) in the cab.

  Note that if the spring force of the return spring 11 that biases the needle valve 3 of the fuel injector 1 in the closing direction is strengthened, the seating load of the needle valve 3 is increased. It may interfere with the behavior and is not preferable.

It is sectional drawing of a fuel injector. It is a block diagram of a fuel-injection apparatus. It is a control flowchart at the time of an engine stop. It is a figure which shows the purge operation | movement of the fuel of a common rail. It is a figure which shows the regeneration and return operation | movement of the fuel of a purge tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injector 3 Needle valve 4 Seating surface 5 Nozzle hole 6 Fuel chamber 7 Piston part 8 Valve closing pressure chamber 11 Return spring 12 Exit passage 14 Solenoid valve 15 Ring part 16 Electromagnetic coil 17 Common rail 20 Combustion chamber 21 Fuel tank 22 High pressure pump 24 Purge control valve 25 Purge tank 26 Pressure pump 30 Control circuit

Claims (5)

In an engine fuel injection device that injects high-pressure fuel from a fuel injector,
Provide a needle valve seating load increase electromagnetic coil to increase the valve closing force of the fuel injector needle valve,
A fuel injection device for an engine comprising a control circuit for operating the electromagnetic coil when the engine is stopped. 2. The fuel injection device for an engine according to claim 1, wherein the needle valve of the fuel injector opens and closes the nozzle portion of the fuel injector by opening and closing the valve closing pressure chamber .   2. The engine fuel injection device according to claim 1, wherein the control circuit operates the electromagnetic coil for a predetermined time after the engine is stopped. In the common rail that guides the fuel boosted by the high-pressure pump to the fuel injector, a purge line for collecting the fuel via the purge control valve is formed, and
The engine fuel injection device according to claim 1, wherein the control circuit opens the purge control valve after operating the electromagnetic coil for a predetermined time after the engine is stopped.   The engine fuel injection device according to claim 1, wherein the fuel is liquefied gas.

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