JPS632023B2 - - Google Patents

Description

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

Pilot injection (prior injection) is one form of control of the fuel injection rate.

Conventional pilot injection methods include two plungers for pumping fuel, each driven separately, two nozzles, pilot injection and main injection using separate nozzles, and a method that uses two nozzles to perform pilot injection and main injection. There is a method that sets the valve pressure in two stages. A method using two plungers or nozzles requires a complicated driving method and requires many fuel pipes, making the device larger. Furthermore, in the method of pilot injection using a nozzle, the nozzle becomes large and difficult to attach to the engine.

In order to overcome the drawbacks of the prior art, it is an object of the present invention to provide a light and small fuel injection device that is capable of performing optimal pilot injection according to the rotational speed load of the engine.

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

In FIG. 1 showing the first embodiment, the cylinder 1
A pressure-feeding plunger 2 is slidably fitted to the holder. The injection plunger 3 is vertically arranged inside the pressure-feeding plunger 2.
and the pilot plunger 4 are slidably fitted. A plunger stopper 8 formed around the hole 37 is screwed into the lower end of the pressure-feeding plunger 2,
It serves to regulate the lower position of the injection plunger 3.

A holder body 5 is fastened to the lower end of the cylinder 1, and a nozzle 6 is supported on the holder body 5. As is well known, the nozzle 6 includes a needle valve 200, and the needle valve 200 is normally biased to close by a nozzle spring 7 installed in a nozzle spring chamber 13 in the holder body 5. . It is also well known that when the pressure-feeding fuel from the pressure-feeding passage 95 acts on the needle valve 200, the needle valve 200 opens upward against the biasing force of the spring 7, and injection is performed. On the other hand, a follower 50 is inserted into the upper end of the cylinder 1, and this follower 50 is engaged with the pressure-feeding plunger 2,
Further, a driving spring 51 is installed between the cylinder 1 and the follower 50. The pressure-feeding plunger 2 is connected to a follower 50 by a cam (not shown) that rotates in synchronization with an engine (not shown).
is driven downward via the driving spring 51.
is pulled upward by the

The inside of the cylinder 1 at the lower end of the pressure-feeding plunger 2 is formed as a pressure-feeding pump chamber 10, and hydraulic pressure is applied to the injection plunger 3 during the downward stroke of the pressure-feeding plunger 2. The lower surface of the pressure-feeding plunger 2 connects the metering port 20 of the cylinder 1 to the pressure-feeding pump chamber 1.
It serves as a metering lead 40 that opens and closes with respect to zero. The spill hole 31 of the pressure-feeding plunger 2 communicates with the annular spill groove 26 of the cylinder 1 when the pressure-feeding plunger 2 is lowered. The metering port 20 communicates with a low-pressure fuel supply pump 61 (described later), and the spill port 26 communicates with the tantameter 6 through discharge passages 92 and 81.
Connects to 0. The injection plunger 3 is formed in a stepped manner, and a pressure relief lead 41 serving as a shoulder serves to open and close the pressure pump chamber 10 to the pressure relief hole 32 of the pressure plunger 2. This pressure relief hole 3
2 communicates with the discharge passage 92 on the tank 60 side.

An injection pump chamber 11 is formed within the pressure plunger 2 between the pilot plunger 4 and the injection plunger 3. This injection pump chamber 11 is connected to a fuel reservoir chamber in the nozzle 6 via a horizontal hole 93 of the pressure-feeding plunger 2, an annular port 94 of the cylinder 1, a pressure reduction chamber 105, a pressure-feeding passage 91, and a pressure-feeding passage 95 in the holder body 5. Communication is possible. In addition, the injection pump chamber 11 can also communicate with the fuel introduction passage 102 via the transverse hole 33 of the pressure-feeding plunger 2 and the metering port 28 of the cylinder 1 .

A pilot pump chamber 12 is formed within the pressure-feeding plunger 2 at the upper end surface of the pilot plunger 4. The pilot pump chamber 12 communicates with the pressure passage 91 of the cylinder 1 via the pilot port 34 of the pressure plunger 2, and with the fuel passage 25 of the cylinder 1 via the passage 35 of the pressure plunger 2. The pilot lead 42, which is the upper end surface of the pilot plunger, plays the role of opening and closing the pilot port 34 formed in the pressure-feeding plunger 2.

Next, to outline the pump device that supplies and discharges fuel to each of the pump chambers 10, 11, and 12 described above, the fuel in the tank 60 is sent out by the engine-driven first fuel supply pump 61, and the fuel is sent out through the supply passage 70. The fuel is supplied from the metering port 20 to the pressure pump chamber 10 via the fuel passage 90 of the cylinder 1 .
Further, a portion of the fuel sent out from the first fuel supply pump 61 is further pressurized by an engine-driven second fuel supply pump 62, and then adjusted to a constant pressure by a pressure regulating valve 67. A part of this pressure-regulated fuel is then supplied to a solenoid valve 63 whose opening time is controlled by a control circuit (not shown) depending on the engine load, etc., and a balance orifice 100 to eliminate variations in metering between cylinders. , the check valve 65, the fuel passage 102 in the cylinder 1, and the metering groove 28 to the injection pump chamber 11, and some other pressure-regulated fuel is supplied to the injection pump chamber 11 via the solenoid valve 64 and the timing variation between cylinders. Balance orifice 10 to eliminate
1. The fuel is introduced into the pilot pump chamber 12 via the check valve 66, the fuel passage 25 in the cylinder 1, and the passage 35 of the pressure-feeding plunger 1.

Although not shown, the part assembled integrally with the cylinder 1 is attached to the cylinder 1 and the holder body 5 so that the tip of the nozzle 6 faces the combustion chamber of the engine.
It can be attached to the engine's cylinder head using the

Next, the operation will be explained.

At the bottom dead center position of the plunger 2, the follower 50, which engages with a cam (not shown), resists the spring 51 and assumes the lowest position. At this time, as will be described later, the pilot pump chamber 12 is filled with a predetermined amount of fuel corresponding to the set pilot injection amount, and the injection pump chamber 11 is filled with a predetermined amount of fuel corresponding to the main injection amount. ing.

Next, the cam moves the follower 50 to the spring 5 (not shown).
Accordingly, the pressure-feeding plunger 2, which comes into contact with the follower, begins to rise. Bubbles are generated in the pressure pump chamber 10 from the time when the spill hole 31 of the pressure plunger 2 cuts off the communication with the spill groove 26 until the time when the metering lead 40 opens the metering port 20. When opened, fuel is supplied from the first fuel supply pump 61 to the pressure pump chamber 10 to eliminate the bubbles, and the pressure plunger 2
When the pump stops at top dead center, the pressure pump chamber 10 is filled with fuel, the injection plunger 3 is pushed, and the injection pump chamber 1 is filled with fuel.
1. Any air bubbles that may be generated within the timing pump chamber 12 are also eliminated, and the next pumping stroke begins.

When the pressure plunger 2 is driven downward by a cam (not shown) and the metering lead 40 closes the metering port 20, the pressure pump chamber 10
The pressure in the injection pump chamber 11 is increased by pushing the injection plunger 3. At this time, since the pilot port 34 communicates with the annular groove 24, the pressure pushes the pilot plunger 4, and the fuel in the pilot pump chamber 12 is pumped through the pilot port 34, the annular groove 24, and the pressure passages 91, 95. Pilot injection is performed from the nozzle 6 prior to the main injection.
After this, when the pilot lead 426 comes to the lateral hole 93, this lateral hole 93 just communicates with the annular groove 94 and connects the injection pump chamber 11 to the pressure reduction chamber 105. Due to the volumetric effect of the chamber 105, the pressure in the pump chamber 11 is temporarily reduced and the pilot injection is terminated.

Thereafter, as the pressure-feeding plunger 2 further descends, the horizontal hole 93 communicates with the annular groove 94, and as the fuel pressure in the pressure-feeding pump chamber 10, injection pump chamber 11, and pilot pump chamber 12 increases, the injection pump chamber 1
1 is force-fed to the nozzle 6 through a horizontal hole 93 in the pressure-feeding plunger 2, a fuel pressure-feeding passage 91 in the cylinder 1, and a fuel passage 95 in the holder body 5, and main injection is performed. At this time, the injection plunger 3 is driven at an increased speed compared to the driving speed of the pressure-feeding plunger 2 by the pressure-receiving area ratio of the pressure-feeding plunger 3. When the pressure-feeding plunger 2 further descends and the pressure relief lead 41 of the injection plunger 3 opens the pressure-relief hole 32 of the pressure-feeding plunger 2, the pressure-feeding pump chamber 1
0 to the tank 60 via the discharge passages 92 and 81 to lower the pressure in the pressure pump chamber 10,
The drive of the injection plunger 3 is stopped to complete the injection. The pressure-feeding plunger 2 continues to move downward to continue discharging the fuel in the pressure-feeding pump chamber 10. When the spill hole 31 communicates with the spill groove 26, the fuel is also discharged through the hole 31 and the groove 26, and the fuel inside the pressure-feeding plunger 2 is discharged. After completing the pumping stroke, the pumping plunger 2 further descends slightly and reaches the bottom dead center.

At this bottom dead center position, the passage 33 opening into the injection pump chamber 11 communicates with the port 102, and the passage 34 opening into the pilot pump chamber 35 communicates with the port 25. As a result, the second fuel supply pump 6
The pressure-regulated fuel from 2 is regulated and sent into the pilot pump chamber 12 by a solenoid valve 64 that opens for a predetermined time depending on the pilot injection amount.
This pushes down the pilot plunger 4 and also pushes down the injection plunger 3 via the fuel in the injection pump chamber 11, causing the fuel in the pressure pump chamber 10 to be transferred from the spill hole and spill groove 26 to the tank 60.
discharge to. When the solenoid valve 63 opens, fuel corresponding to the main injection amount is sent into the injection pump chamber 11 via the check valve 65 and the fuel passage 102, thereby pushing down the injection plunger 3 by a stroke corresponding to the injection amount. At this time, the fuel in the pressure pump chamber 10 is similarly discharged to the tank 60.

As understood from the above explanation, the pilot injection amount is controlled by the opening time of the solenoid valve 64, and the main injection amount is controlled by the opening time of the solenoid valve 63.
By controlling the opening times of these electromagnetic valves 63 and 64 according to the engine load, etc., it is possible to obtain an appropriate pilot injection amount and injection amount. The maximum main injection amount is obtained when the pilot plunger 4 closes the pilot port 34 and the injection plunger 3 is in contact with the injection plunger stopper 8 at the end of metering. becomes 0.

In addition, in this embodiment, each solenoid valve 63, 64
The order in which the valves are opened may be reversed or at the same time, and the timing may be when the pressure-feeding plunger 2 is not at the bottom dead center, is rising, or is at the top dead center.

FIG. 2 shows the second embodiment, and below, the first embodiment is shown.
The points that are different from the embodiment will be mainly explained. The injection plunger 4 is connected to the pressure-feeding plunger 2 as shown in FIG.
It is not provided inside the cylinder 1, but is provided inside the second cylinder 1b on the lower side of the cylinder 1. The injection pump chamber 11 is formed by the second cylinder 1b, the holder body 5, and the injection plunger 3. The intermediate shoulder 3 of the injection plunger 3 is formed as a spill reed 113, which opens and closes the spill port 112 of the second cylinder 1b to determine the end of injection. The nozzle leak fuel discharge passage 96 is the fuel passage 120 of the second cylinder 1b.
It communicates with the fuel discharge passage 92 of the cylinder 1 via. The injection pump chamber 11 and the fuel passage 111 of the cylinder 1b can communicate through the port 112 at a predetermined lift of the plunger 3 or more. This passage 1
11 can also communicate with the injection pump chamber 11 through a check valve 65b. In the embodiment shown in FIG. 1, the movement of the injection plunger 3 is restricted by a stopper 8, but
In FIG. 2, the movement of the pilot plunger 4 is restricted by a stopper 8b. A pilot lead 42b is formed on the pilot plunger 4,
It plays the role of opening and closing the horizontal hole 31 of the pressure-feeding plunger 3. This horizontal hole 31 is connected to a pump chamber 106 at the upper end of the injection plunger 3 via a fuel passage 97.
The pilot injection is performed until the pilot lead 42b opens the horizontal hole 31. After that, the fuel in the pump chamber 10 is introduced into the chamber 106 through the passage 97, the injection plunger 3 starts to descend, and the fuel is discharged from the pump chamber 11 into the passage. 95 and enters main injection. Note that the same or equivalent parts as in the embodiment shown in FIG. 1 are simply given the same reference numerals, and detailed explanation thereof will be omitted.

According to this configuration, since the length of the fuel passage from the injection pump chamber 11 to the nozzle 6 is shortened, the delay in injection is shortened and the injection pressure can be increased. At the end of injection, the fuel in the injection pump chamber 11 flows into the vertical hole 11.
4. Since the fuel is released to the fuel passage 111 side through the side hole 115 and the spill port 112, the end of injection becomes sharper. In addition, after the injection is completed, the spilled fuel is transferred again from the spill port 112 side to the check valve 65b.
Since the injection plunger 3 is pushed up by the amount of the spill stroke by back-filling the chamber 11 through the pump, the fuel utilization efficiency becomes high. Furthermore, since the port 31 communicates with the passage 120 during spillage from the pressure pump chamber 10, the spilled fuel is transmitted to the nozzle spring chamber 13 and urges the needle to close. This makes the end of the injection even sharper.

Next, a third embodiment shown in FIG. 3 will be described. The difference from the first embodiment is that the pressure reduction chamber 105
In its place, the pilot plunger 4 is provided with a spill lead 120 and a vertical hole 12 communicating with the pilot pump chamber 12 and the horizontal hole 93 in the pressure-feeding cylinder 2.
1 and a horizontal hole 122. The horizontal hole 93 is connected to the check valve 66 and check valve 140 through the spill hole 123 and spill passage 124 in the cylinder 1 when the pressure-feeding plunger 2 descends and pilot injection ends.
communicate between. Therefore, according to this configuration, after the pilot plunger 4 hits the upper end of the pilot pump chamber 12 after the pilot injection ends, the chamber 1
The fuel in the fuel tank 1 is pressurized and enters main injection, in which the fuel is fed under pressure from the fuel passage 11 to the nozzle.

In the embodiment shown in FIGS. 1 to 3, two fuel supply pumps 61, 62 are used, but instead of this, one fuel supply pump is used for each pump chamber 10, 1.
It is also possible to share the fuel supply to Nos. 1 and 12. Furthermore, if the pressure regulating valve 67 is of a type that adjusts the fuel pressure according to the engine rotation, the fuel injection amount will be automatically adjusted according to the engine rotation speed. Furthermore, although two solenoid valves are used, if you change to a two-position three-port valve or four-port valve, one
Metering is also possible with a single solenoid valve. Furthermore,
Regarding the positional relationship of the plungers 2 to 4, the positions of the injection plunger 3 and the pilot plunger 4 may be exchanged, or only one of the injection plunger 3 and the pilot plunger 4 may be inserted into the pressure-feeding plunger 2. Furthermore, it is also possible to insert the pilot plunger 4 into the injection plunger 3 or vice versa, and it is of course also possible to insert each of the plungers 2 to 4 into separate cylinders.

As is clear from the above description, according to the present invention, since the injection plunger can be moved by a stroke corresponding to the amount of fuel supplied, bubbles are not generated in the injection pump chamber, and therefore, fluctuations in the injection amount,
Asymmetric injections can be prevented. Further, the pilot injection amount can be arbitrarily set in order to supply fuel matching the set pilot injection amount and move the pilot plunger. Furthermore, by driving the pressure plunger with an engine, there is no need to maintain a high-pressure hydraulic power source, which provides the excellent effect of reducing output loss and making it possible to eliminate the high-pressure circuit.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional configuration diagram showing the first embodiment of the device of the present invention, FIG. 2 is a schematic cross-sectional configuration diagram showing the second embodiment, and FIG. 3 is a schematic cross-sectional diagram showing the third embodiment. FIG. 2...Pressure plunger, 3...Injection plunger, 4...Pilot plunger, 6...Nozzle, 11...Injection pump chamber, 12...Pilot pump chamber, 61, 62...Fuel supply pump.

Claims (1)

[Claims] 1 A pressure-feeding plunger that is driven by an engine and generates hydraulic pressure by reciprocating in synchronization with the engine, an injection plunger that forms an injection pump chamber at one end and pumps fuel to a nozzle, and a pilot pump chamber at one end. a pilot plunger for controlling a pilot injection amount, which is formed and driven by hydraulic pressure from the pressure-feeding plunger to force-feed fuel to a nozzle prior to pressure-feeding by the injection plunger; and a fuel supply pump that supplies fuel to both the injection pump chamber and the pilot pump chamber. and a solenoid valve that guides fuel in an amount corresponding to the main injection amount and the pilot injection amount from the fuel supply pump to the injection pump chamber and the pilot pump chamber. 1. A fuel injection device for an internal combustion engine, characterized in that fuel is pumped to a nozzle in the order of a pilot plunger, then an injection plunger.