JPH051854U - Fuel supply device for in-cylinder direct injection engine - Google Patents

Abstract

(57) [Abstract] [Purpose] In a high-pressure fuel supply system equipped with an accumulator, improve startability and the like with a simple structure and control. [Structure] A high pressure regulator 4 for adjusting fuel pressure to a common rail 41 to which fuel is supplied by a high pressure pump 38.
3. Injector 1 that directly injects fuel into each cylinder
0, a control valve 50 communicating with an accumulator 45 for reducing fluctuations in fuel pressure, and provided in a passage 44 between the common rail 41 and the accumulator 45 at least for opening / closing according to ON / OFF of an ignition switch 52, and controlling when the engine is stopped. The valve 50 holds high-pressure fuel in the accumulator 45, and when the engine is started, the control valve 50 causes, for example, cranking and the accumulator 45 at the same time.
The fuel having a relatively high fuel pressure is generated by injecting the accumulated pressure fuel into the common rail 41, whereby a substantially predetermined fuel injection is performed in the cylinder to enable a good start.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention is applied to a direct injection type two-cycle engine or four-cycle engine. For details on the fuel supply device that supplies high fuel pressure fuel to the injector, Regarding measures for improving startability in a system equipped with an accumulator that reduces fluctuations in fuel pressure. To do.

[0002]

[Prior art]

As a vehicle engine, there has already been proposed a fuel supply system in which a high-pressure one-fluid injector is mounted in a combustion chamber, a nozzle of the injector is electronically opened / closed, and fuel is directly injected into a cylinder at high pressure. In this fuel supply system, the fuel pressure of the injector is set to a relatively high pressure of, for example, 30 kg / cm ² or more in order to inject directly into the cylinder in the compression stroke in the two-stroke engine. Since the fuel injection amount is specified by the injection pulse width, it is necessary that the fuel pressure be constant without fluctuation. (Even in the case of the variable fuel pressure type, it is desirable that it does not fluctuate with respect to the target value.) By the way, fluctuations due to fuel pump drive, fluctuations due to injector opening / closing, fluctuations due to the fuel pressure regulator, fluctuations due to pulsation in the fuel passage, etc. Fluctuations in fuel pressure occur due to various factors. Therefore, as a measure for reducing this fuel pressure fluctuation, a method of mounting an accumulator to absorb the fluctuation is known. However, in the system with this accumulator installed, if the fuel in the accumulator becomes empty when the engine is stopped, the increase in fuel pressure will be delayed by the time when the accumulator is filled with fuel when the engine is started, resulting in poor startability. It is necessary to improve the points.

[0003]   Conventionally, regarding the startability of the fuel supply apparatus including the accumulator, for example, There is a prior art of Japanese Utility Model Laid-Open No. 63-200666. Where for the fuel pipe The accumulator is the first control valve on the inlet side, the one-way valve on the outlet side, the second It is shown to be connected by bypassing by the control valve.

[0004]

[Problems to be solved by the device]

  By the way, in the above prior art, the accumulator is connected to the fuel pipe. Since it is connected by passing, the effect of reducing pressure fluctuation is small, and the structure and control are complicated. However, there are problems such as high cost.

[0005]   The present invention has been made in view of this point, and a high-pressure fuel equipped with an accumulator is provided. The purpose is to improve startability, etc. with a simple structure and control in the charge supply system. It

[0006]

[Means for Solving the Problems]

  In order to achieve the above-mentioned object, the present invention provides a combustor that is supplied with fuel by a high pressure pump. This common rail has a high-pressure regulator that adjusts the fuel pressure and each An injector that directly injects fuel into the cylinder and an accumulator that reduces fuel pressure fluctuations. In the fuel supply system that communicates with the muller, Open and close the passage between them at least depending on whether the ignition switch is on or off. A control valve is provided.

[0007]

[Action]

  Based on the above configuration, when the engine is stopped, a high pressure is applied to the accumulator by the control valve. Fuel is accumulated in pressure and is controlled by the control valve at the same time as cranking when the engine is started. Accumulator's accumulator fuel flows into the common rail to generate fuel with a relatively high fuel pressure. Occurs, which causes a substantially predetermined fuel injection into the cylinder and starts a good start. Become so.

[0008]

【Example】

  Embodiments of the present invention will be described below with reference to the drawings. In Figure 2, in-cylinder direct injection type As an engine, the overall configuration in the case of a two-cycle engine will be described. Mark No. 1 is the main body of a 2-cycle engine, and the piston 3 can reciprocate in the cylinder 2. Which is inserted into the crank chamber 4 and is eccentrically provided with respect to the crankshaft 5 of the crank chamber 4. 6, the piston 3 is connected and the reciprocating inertia force of the piston 3 is applied to the crankshaft 5. The balancer 7 is provided to kill. Combustion chamber 8 is offset, wedge, A high-pressure single-fluid injector 10 having a shape such as a bounce is provided at a high position near the center top. Is installed so that it is opened for the on-time (pulse width) of the pulse signal. Also, The spark plug 9 is tilted so that the electrode 9a is located immediately below the injector 10 in the injection direction. Installed.

[0009]   The distance between the injector 10 and the electrode 9a is low and medium load, and injection is performed immediately before ignition. It is set considering the cone type fuel spray. That is, if the distance is short, the atomization is insufficient. However, as the spray spreads over a long period of time, the rear end of the spray is ignited between the two It is possible to carry out layer combustion. Further, the injector 10 is an abbreviation for the cylinder 2. Since it is located on the center line, a large amount of fuel injected at an early stage under high load Rapidly diffuses from the inner center of the cylinder 2 to uniform premixing and uniform combustion. It is possible to do.

[0010]   The cylinder 2 has an exhaust port 1 that opens and closes at a predetermined timing by a piston 3. 1 is opened, and a catalyst device 13 and a muffler 14 are installed in the exhaust pipe 12 from the exhaust port 11. Be kicked. Here, an exhaust rotary valve 15 is installed in the exhaust port 11, and a belt The opening / closing of the exhaust port 11 is separately determined by connecting to the crankshaft 5 by means 16. It That is, when the piston 3 starts to rise from the bottom dead center side, the exhaust rotary valve 15 causes When the fuel is injected in the uniform combustion system under high load, the exhaust port 11 is closed early. It is possible to set the period early.

[0011]   In the cylinder 2, the exhaust port 11 is rotated by 180 degrees in the circumferential direction. Similarly, the piston 3 opens and closes at a predetermined timing at a position offset by about 90 degrees. A scavenging port 17 for opening is provided. And an air supply pipe upstream of the scavenging port 17 18, an air cleaner 19 and a throttle valve 20 that opens according to the accelerator opening are installed. The scavenging pump 21 is provided downstream of the throttle valve 20 by the belt means 22. It is connected to the crankshaft 5 and the pump power is constantly driven by the engine power to generate scavenging air pressure. It is set up like this. Here, the throttle valve 20 is slightly opened even when the accelerator is fully closed to perform scavenging. The pump 21 is set so that it can be sucked in. If the play range is exceeded, the accelerator opening will change. Accordingly, the throttle valve 20 opens to control the air amount. And with scavenging air pressure only The scavenging action is forced, and fresh air is supplied.

[0012]   In FIG. 1, the fuel supply system will be described. First, the fuel from the fuel tank 30 The feed passage 31 communicates with the feed pump 32, and the discharge side of the feed pump 32 33 communicates with the low pressure regulator 35 through the low pressure filter 34, and A return passage 36 from the guulator 35 communicates with the fuel tank 30 to allow a predetermined low-pressure fuel to be burned. Generate fees. The low pressure fuel passage 37 from the low pressure regulator 35 is connected to the high pressure pump 38. And the passage 39 on the discharge side of the high-pressure pump 38 is connected to the high-pressure filter 40. And communicates with the common rail 41 having a predetermined capacity. Return passage 42 of common rail 41 Is equipped with a high-pressure regulator 43 for adjusting to a predetermined fuel pressure. The common rail 41 communicates with the accumulator 45 through the passage 44. Accu The murrator 45 has a high pressure on the side opposite to the fuel that is partitioned by the diaphragm 46. Gas G is enclosed to reduce fuel pressure fluctuations. Further common rail 4 1, the passage 47 communicates with the injector 10 of each cylinder so as to supply high-pressure fuel. are doing.

[0013]   Further, in the above configuration, the communication between the common rail 41 and the accumulator 45 is made. A control valve 50 for opening and closing is provided in the middle of the path 44. This control valve 50 is not energized It is a normally closed type that sometimes closes, and at least the ignition switch It is possible to close the passage 44 by closing it when the switch is turned off.

[0014]   Further, the control system will be described. The fuel pressure for detecting the fuel pressure on the common rail 41 A sensor 51 is attached. In addition, the ignition switch 52, various sensors The sensor 53 and the switch signals are input to the control unit 54 and processed. Be treated. That is, the control unit 54 controls the fuel pressure to keep it constant. The adjustment signal is output to the high voltage regulator 43. In addition, fuel injection according to each operating condition The injection amount and injection timing are calculated and the ignition timing is determined. It outputs to the injector 10 and outputs an ignition signal to the spark plug 9. In addition, igu The engine start is judged by the ON signal of the nision switch 52, and the control valve 50 is judged. Turn on the power, turn off the ignition switch 52, or activate the ignition and injection systems. When the engine is stopped, it is determined that the engine is stopped and the control valve 50 is de-energized. It

[0015]   Next, the operation of this embodiment will be described. First, when the 2-cycle engine is operating In addition, the throttle valve 20 opens according to the accelerator opening, etc., and the air is transferred to the scavenging pump 21. A predetermined scavenging pressure is generated by suction, and the exhaust port 11 opens when the piston 3 descends, Next, when the scavenging port 17 is also opened, this pressurized air flows from the scavenging port 17 to the cylinder 2 Flows into the interior. The residual swirl of the cylinder 2 is generated by the vertical swirl flow of the supply air. Is pushed out from the exhaust port 11, and the scavenging action is performed to fill the air supply with high filling efficiency. It On the other hand, when the piston 3 starts rising from the bottom dead center, the exhaust rotary valve 15 closes. Exhaustion is completed, and it becomes possible to inject fuel without causing fuel blow-through. Then, the scavenging port 17 is closed and the compression stroke is started.

[0016]   At this time, the feed pump 32 and the high pressure pump 38 of the fuel supply system are driven, The fuel in the tank 30 is sucked by the feed pump 32 and a low pressure regulator The pressure is adjusted to a predetermined low pressure by 35 and is fed under pressure to the high pressure pump 38. Therefore, the predetermined fuel is always smoothly supplied to the high pressure pump 38. Discharge from high-pressure pump 38 The high-pressure fuel that comes out flows into the common rail 41 and is burned by the high-pressure regulator 43. By adjusting the pressure, a certain amount of fuel is always stored at a constant high fuel pressure. The fuel in the common rail 41 further flows into the accumulator 45, and the high pressure Due to the equilibrium relationship with the gas G, fluctuations in fuel pressure due to various factors are absorbed and smoothed. It Then, from the control unit 54 to the injector 10 of each cylinder in the compression stroke described above. When the injection signal is output, the smoothed high-pressure fuel on the common rail 41 causes the injection pulse width Is injected directly into the cylinder with an injection amount according to Burned.

[0017]   On the other hand, if the ignition switch 52 is turned off when the engine is stopped, the fuel is supplied. The pump drive of the system is stopped, but the control unit 54 deenergizes the control valve 50. The fuel is stored at high pressure in the accumulator 45 for immediate closing. Will be done. After that, turn on the ignition switch 52 when starting the engine. Then, simultaneously with the start of cranking, the control unit 54 energizes the control valve 50. Open more. Therefore, the fuel and the accumulator 45 on the way of rising by the high pressure pump 38 The fuel with the accumulated pressure flows into the common rail 41, and the synergistic action of the two causes the common rail The fuel of relatively high fuel pressure is promptly secured in the fuel tank 41, which causes At the time of ranking, the fuel is injected from the injector 10 at a high pressure, and the fuel injection amount is almost the predetermined And will start satisfactorily.

[0018]   Another embodiment of the present invention will be described with reference to FIG. In this example, the control Signals from the ignition switch 52 and the engine speed sensor 55 to the unit 54 Has a cranking determination unit 56 for input. And ignition switch 5 When the switch 2 is turned off, the control valve 50 is immediately de-energized by the drive unit 57, and the ignition is turned on. When the switch 52 is turned on, the drive unit 57 drives the control valve 5 after the cranking determination. It is designed to energize 0. Therefore, in this embodiment, the engine is stopped Assuming that the pressure holding of fuel compression in the accumulator is insufficient due to the mechanism. ing. That is, the control valve 50 is closed during the cranking when the engine is started, and Since the passage 44 of the relator 45 is blocked, the fuel of the high-pressure pump 38 is temporarily exhausted. It will not flow into the humulator 45. Therefore, the fuel pressure of the common rail 41 is effectively Ascend and start well. And the control valve 50 opens after cranking. Since the fuel is gradually accumulated in the accumulator 45, the common rail 41 It acts so as to absorb the fluctuation without causing a sudden decrease in fuel pressure.

[0019]   The embodiments of the present invention have been described above, but the present invention is not limited thereto.

[0020]

[Effect of device]   As described above, according to the present invention, a fuel supply device for a direct injection type cylinder engine is provided. In a system equipped with an accumulator that reduces fluctuations in fuel pressure, By opening and closing the control valve provided in the passage, the fuel pressure rises quickly when the engine starts. Since it is controlled, the startability is improved. The control valve is the ignition switch Since it is a normally closed type that opens and closes depending on whether it is on or off, the structure and control are It will be easier. In another embodiment of the invention, the accumulator is connected after cranking. Since it is passed, it is possible to prevent the fuel pressure from decreasing. Accumulator is high pressure fuel Since it is provided in communication with a common rail that stores fuel, the effect of reducing fuel pressure fluctuations is great. Kii.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a fuel supply system for a direct injection type engine according to the present invention.

FIG. 2 is a block diagram showing a general outline of an example of an in-cylinder direct injection engine of the present invention.

FIG. 3 is a block diagram showing a main part of another embodiment of the present invention.

[Explanation of symbols]

1 2 cycle engine body 10 injectors 38 High pressure pump 41 common rail 43 High pressure regulator 44 passage 45 Accumulator 50 control valve 52 Ignition switch 54 control unit

Claims (3)

[Scope of utility model registration request] 1. A common rail to which fuel is supplied by a high-pressure pump, wherein a high-pressure regulator for adjusting fuel pressure, an injector for directly injecting fuel into each cylinder, and a variation in fuel pressure are reduced on the common rail. In a fuel supply system that communicates with an accumulator, a control valve that opens and closes at least according to on / off of an ignition switch is provided in a passage between the common rail and the accumulator, and a fuel supply device for a direct injection engine of a cylinder type. . 2. The fuel supply system for a direct injection type engine according to claim 1, wherein the control valve is a normally closed type. 3. The fuel supply system for a cylinder direct injection engine according to claim 1, wherein the control valve is controlled so as to be temporarily closed during cranking at the time of starting.