JPS5853670A - Fuel injection device - Google Patents

Abstract

PURPOSE:To improve the responsiveness of the injection time by opening or closing the timing valve arranged on the discharge passage relieving the fuel in a pressure feed pump chamber in accordance with the engine operating condition. CONSTITUTION:A feed port 31 and timing port 30 are opened together in a pressure feed pump chamber 68 and are connected to a tank 57 through the fuel discharge passage 51 having a timing solenoid valve 19, etc. The fuel in the tank 57 is introduced into the injection pump chamber 61 below an injection cylinder 16 through a regulating solenoid valve 17, etc., and a nozzle 4 is fitted below the chamber 61. First, a pressure feed and an injection plungers 2a, 1a are lowered from the top dead point to discharge the fuel in the chamber 68 through the ports 31, 30, and the valve 19 is closed so as to obtain the optimum injection time for the operating condition, thereby the high pressure in the chamber 68 is applied to the plunger 1a, thus the fuel is injected through the nozzle 4 under a predetermined pressure in the chamber 61 and the fuel quantity in the chamber 61 is controlled by the opening time of a valve 17b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for supplying fuel to a diesel engine.

In recent years, it has become necessary to increase the fuel injection pressure to improve the combustion characteristics of diesel engines. In conventional systems, the injection pressure of fuel into the engine is about 700 atm, but there is a demand for increasing it to a higher level. For this reason, a device has been proposed in which a pressure-feeding plunger that generates high pressure in the pressure-feeding pump chamber and an injection plunger that is driven based on the pressure of the pressure-feeding pump chamber and generates even higher pressure in the fuel injection chamber are arranged directly in JI1. .

In this type of device, it is necessary to control the drive timing of the injection plunger depending on the operating state of the engine. In other words, it is necessary to perform detailed control such as advancing the injection timing when the engine rotates at high speed or when starting. Therefore, an object of the present invention is to finely control the driving timing during injection plunge in the above-mentioned apparatus according to the engine operating state.

(2) Therefore, in the present invention, a timing valve that opens and closes the passage is provided in the middle of the exhaust passage that discharges fuel in the pressure pump chamber, and the closing timing of this timing valve is variably controlled according to the operating state of the engine. The drive timing of the injection plunger is controlled by the injection plunger.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described.

In FIGS. 1 and 2, 1b is an injection cylinder, and an injection plunger 1a is slidably fitted into the cylinder lb. In addition, an injection plunger 1 is included in the pressure feeding cylinder 2b that is assembled integrally with the injection cylinder 1b.
A pressure-feeding plunger medium 2a having a diameter larger than a is slidably fitted. The rear surface of the pressure-feeding plunger 2a is engaged with a seven-lower 9, and the plunger 2a is driven downward by a cam (not shown) in synchronization with the engine, and is pushed upward by a follower spring 8.

A feed boat 31 and a timing boat 30 are opened in the pressure feed cylinder 2b, and a timing lead 70 for opening and closing the timing boat 30 and a second spill lead 73 for opening and closing the feed boat 31 are provided in the feed plunger 2a. are formed, and furthermore, a vertical hole 65 and a horizontal hole 6 that communicate the pressure pump chamber 68 and the annular groove 67 are formed.
6 is formed.

Reference numeral 11 denotes a second feed pump 11 driven by the engine, and the fuel in the tank 57 is pumped out by this pump 11. The maximum pressure of the fuel is regulated by the safety valve 13, and the fuel is passed through the fuel supply passage 50 to the feed boat 31.
The pressure is supplied to the pressure pump chamber 68 from there. Pressure pump chamber 68
The fuel inside is discharged from the timing boat 30 through the fuel discharge passage 51.
．． Timing check valve 27. Timing orifice 20.
and is discharged to the tank 57 via the timing solenoid valve 19. The timing orifice 20 prevents high-pressure fuel from being directly applied to the seat surface of the timing solenoid valve 19, and has an inner diameter of about one fin.

A spill boat 33 and a drain boat 34 are opened in the injection cylinder 1b, and a spill lead 71 for opening and closing the spill boat 33 and a drain lead 72 for opening and closing the drain boat 34 are formed in the injection cylinder 1a. Furthermore, the injection pump chamber 61 and the annular groove 64
The vertical hole 62 and horizontal hole 63 that communicate with the injection cylinder lb
A nozzle holder 6 is arranged below. The nozzle holder 6, the pressure cylinder 2b, and the injection cylinder 1b are integrally assembled with a holder nut 100. Then, the downward movement of the injection plunger 1a is regulated by the nozzle holder 6, and the upward movement is regulated by the injection plunger 7 bar 7. An injection pump chamber 61 is provided at the outlet of the injection cylinder 1b, and is surrounded by the injection cylinder 1b and the nozzle holder 6.

10 is a first food pump driven by the engine;
The fuel supplied from this pump IO is supplied to the surge tank 14.
．． Metering solenoid valve 17. Metering check valve 5° balance orifice 18. Metering passage 53. Injection pump chamber 6 via metering valve 3
1 will be introduced. 16 is an accumulator that damps the pulsation of the fuel in the surge tank to keep the hydraulic pressure (5) level constant; 12 is a safety valve that adjusts the pressure of the supplied fuel to a constant pressure. This injection pump chamber 61 is connected to the metering boat 32. It is connected to the nozzle 4 via a regulating valve spring chamber 58 in the nozzle holder 6 and a fuel pressure passage 56 . Note that a metering valve 3 and a metering valve spring 90 are installed in the regulating valve spring chamber 58.

Further, the above-mentioned nozzle 4 can be integrally assembled into the nozzle holder 6 with a retaining nut 101.

This nozzle 4 is of a known type in which a nozzle hole is opened and closed by a needle valve 4a, and a nozzle spring 2 in a nozzle holder 6 is used.
1 urges the needle valve 4a in the valve closing direction. The nozzle spring chamber 69 is connected to the drain passage 5 via the communication passage 59.
5 will be contacted. The drain port 134 is also connected to this passage 55, and the passage 55 is connected to the tank 57 via the discharge passage 52.
connected to.

Next, the operation will be explained.

First, when the pressure-feeding plunger 2a and the injection plunger 1a (6) are at the top dead center, in this state, the injection pump chamber 61 is filled with a predetermined amount of fuel according to the injection amount by the action of the first feed pump 10. Also, the pressure pump chamber 68
The interior is filled with fuel sent from the second feed pump 11. Thereafter, when the pressure-feeding plunger 2a is lowered from the top dead center by the operation of a cam (not shown), the fuel in the pressure-feeding pump chamber 68 is transferred to the feed boat 31 as the pressure-feeding plunger 2a descends from the top dead center.
．． It is discharged from the timing boat 30.

First, the timing lead 70 is connected to the feed boat 3.
1, fuel will be discharged only from the timing boat 30. However, a timing solenoid valve 1tair is disposed in the fuel discharge passage 51 that discharges fuel from the timing port 30, and this timing is set at a time when the optimum injection timing is obtained considering the engine speed, load, etc. The solenoid valve 19 is closed. When the solenoid valve 19 closes and the discharge of fuel from the timing port 30 is stopped, the fuel in the pressure pump chamber 68 becomes high pressure.
The injection (7) is applied through the opening 7a of the injection plunger stopper 7 to the back surface of the injection plunger 1a. Therefore, the injection plunger 1a is driven at a speed increased by the pressure receiving area of the pressure-feeding plunger 2a and the injection plunger 1a.

The seat of the timing solenoid valve 19 receives high-pressure fuel from the pressure pump chamber 68 via the timing check valve 27 and timing orifice 20, so the force acting on the seat of the solenoid valve 19 is small. The driving electromagnetic force can be small. In addition, since the timing port 30 is opened at the position necessary for the most retarded injection, the timing port 30 is closed by the timing lead 70 before the fuel pressure in the pressure pump chamber 68 reaches high pressure. . Therefore, the high-pressure fuel is not loaded onto the solenoid valve 19, and the solenoid valve 19 is sufficiently protected in terms of strength and will not be destroyed. In addition, the solenoid valve 19 is a timing bow)
When the passage 30 is closed, the current is cut off and the passage 30a is opened.

Now, when the timing port 30 is closed, the injection plunger 1a is driven by the pressure in the pressure pump chamber 68 and increases the pressure in the injection pump chamber 61. When the pressure-feeding plunger 2a further descends and the pressure in the injection pump chamber 61 reaches the valve opening pressure of the nozzle 4, the needle valve 4a is moved by the nozzle spring 2.
1 and starts injecting fuel from the push-up nozzle 4.

The fuel injection pressure at this time is set to be a very high pressure.

The pressure-feeding plunger 2a continues to descend and continues to inject, but
When the spill lead 71 or the spill boat 33 in the injection plunge chamber 1a is opened, the high pressure fuel in the injection pump chamber 61 flows through the vertical hole 62. Horizontal hole 63. The fuel is returned to the metering passage 53 through the spill passage 54 via the annular groove 64 and the spill boat 33, and as a result, the fuel pressure in the injection pump chamber 61 decreases and injection ends. After that, the pressure plunger 2a further descends a little to drive the injection plunger 1a, and the drain lead 72 opens the drain boat 34 to drain the high pressure fuel in the pressure pump chamber 68 to the drain passage 55. The liquid is discharged to the tank 5 and 7 through the discharge passage 52, and at this point, the driving of the injection plunger 1a is once stopped. However, the pressure-feeding plunger 2a continues to descend further after that, and the spill lead 73 opens the feedbow 31 of the pressure-feeding cylinder 2°b, and the fuel in the pressure-feeding pump chamber 68 is discharged from the feedboat 31 as well. After further descending a little, the pressure-feeding plunger 2a reaches the bottom dead center and stops.

The fuel once spilled to the metering passage 53 is transferred to the spill boat 3.
3 or flows backwards from the metering valve 3 to the injection pump chamber 61 and is used repeatedly each time to improve metering efficiency.

Now, when the pumping plunger 2a starts rising from the bottom dead center, the feed boat 31 is first closed by the spill lead 73. Then, the fuel pressurized by the first feed pump IO is supplied into the injection pump chamber 61, thereby moving the injection plunger upward in the figure. Here, since the required amount of fuel supplied into the injection pump chamber 61 varies depending on the operating state of the engine, in this example, the opening time of the metering solenoid valve 17 is determined according to the operating state of the engine. is now under control.

That is, when the engine is under high load, the solenoid valve 17 is opened (10), and the valve time becomes longer, and a large amount of fuel is supplied into the pump chamber 61. Conversely, when the engine is under low load, the solenoid valve 17 is opened (10) to reduce the amount of fuel supplied. The valve opening time has become shorter. However, no matter how much the opening/closing time of the electromagnetic valve 17 is controlled, if there is a fluctuation in the pressure of the supplied fuel, the predetermined amount of fuel will not be supplied, so in this example, the pressure regulating valve 12. Surge tank 14. An accumulator 16 keeps the fuel pressure constant.

The pressure-feeding plunger 2a further rises to feed the feed port 3.
When the hole 1 is opened again, fuel is supplied from the second feed pump 11 to the pressure pump chamber 68.

The pumping plunger 2a further rises a little, reaches the top dead center, and stops. Then, the pressure-feeding plunger 1a starts to descend again, and this operation is repeated thereafter.

As is clear from the above explanation, in this example, the injection pump chamber 6
The amount of fuel to be injected is controlled by adjusting the amount of fuel supplied to the pump chamber 68, and the timing of injection is controlled by controlling the timing at which pressure rise in the pressure pump chamber 68 starts. The nozzle 4 is installed in both pump chambers 61 and 68.
The high injection pressure from the fuel injection valve is not directly applied, so that a stable injection amount and injection timing can be obtained.

Next, a second embodiment will be explained based on FIGS. 3 and 4. The difference from the first embodiment is that a fuel gear rally 15 is formed within the engine rad 102, and a holder nut 100 is formed inside the engine rad 102.
An O-ring 103 is inserted into the fuel gear rally 15 to ensure oil tightness between the fuel gear and the hend 102, and the exhaust fuel from the timing solenoid valve 19 is routed through the exhaust passage 83, and the drain fuel from the drain boat 34 of the injection cylinder 1b is routed to the fuel gear rally 15. are connected via drain passages 55.82 to fuel gear rally 1.
From 5 onwards, the gear rally orifice 80. The gear rally check valve 81 is biased by a gear rally check valve spring 92 and has a valve opening pressure set to be connected to the tank 57 via the gear rally check valve 81 .
4 was added. According to this configuration, the fuel discharged from the pressure pump chamber 68 is collected in the fuel gear rally 15 and can be reversely charged from the drain port 34, and other cylinders can also be effectively filled, increasing fuel utilization efficiency. Can be simplified.

Next, FIG. 5.6 showing the third embodiment will be explained.

Similar to the second embodiment, a timing plunger 93 is formed in a timing cylinder 105 instead of a timing electromagnetic valve 19, and is connected via a timer 104 to a timer shaft 106 that rotates in synchronization with a camshaft (not shown). It's in the configuration. According to this configuration, the injection timing is controlled by the lead 95 formed on the timing plunger 93 that opens and closes the fuel discharge passage 51. That is, an arbitrary injection timing can be obtained by shifting the phase of the timer shaft 106 and the timing plunger 930 using the timer 104 (which can be electrically controlled). The fuel that entered the timing plunger 93 is transferred to the port 94. Fuel passage 96. It is the same as in the second embodiment that the fuel is led to the gear rally 15 via the exhaust passage 83 through the shaft hole 97° radius hole 98.

(13) In these embodiments, even one feed pump can be used, and the spill leads 71 and 73 can also be used.

As explained above, in the present invention, the pressure pump chamber controls the injection timing, and the injection pump chamber controls the amount of fuel injected, and since the two mechanisms are separated, stable fuel injection can be performed, and especially This has the excellent effect of improving the responsiveness of injection timing.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing a first embodiment of the device of the present invention, FIG. 2 is a cross-sectional configuration diagram of the device shown in FIG. 1, and FIG. 3 is a main part of the second embodiment of the device of the present invention. System configuration diagram shown,
4 is a cross-sectional configuration diagram of the device shown in FIG. 3, and FIG. 5 is a system configuration diagram showing main parts of the third embodiment of the device of the present invention, 1l
Figure iB is a cross-sectional configuration diagram of the apparatus shown in Figure 5. la... injection plunger, 1b... injection cylinder. 2a... Pressure feeding grunge, 2b... Pressure feeding cylinder. 4... Nozzle, 19... Timing solenoid valve, 20...
...ri (14) Imming orifice, -61 ... Injection pump chamber, 68
...Pressure pump room. Representative Patent Attorney Takashi Okabe (15) M2 Audience 3 Kyou

Claims (1)

[Claims] (11 A pressure-feeding plunger that is inserted into the pressure-feeding cylinder and reciprocates in synchronization with the engine, a pressure-feeding pump chamber where pressure is generated by the reciprocating motion during this pressure-feeding plunge, and a fuel discharge that releases the fuel in this pressure-feeding pump chamber. a timing valve that is disposed in the fuel discharge passage and opens and closes the fuel discharge passage at a timing according to the operating state of the engine; and an injection plunger that is inserted into the injection cylinder and driven by the pressure of the pressure pump chamber. an injection pump chamber in which pressure is generated by the reciprocation of the injection plunger, a fuel supply passage that supplies fuel to the injection pump chamber, and a fuel injection nozzle that injects the fuel in the injection pump chamber into the engine. (2) The fuel injection device according to claim 1, wherein an orifice is formed in the fuel discharge passage between the pressure pump chamber and the timing valve. )