JPH0220460Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a pressure booster plunger type fuel injection device.

[Prior art]

Conventional pressure booster plunger type fuel injection devices for internal combustion engines operate a large diameter plunger of the pressure booster plunger using a switching servo valve, and drive a plunger pump connected to this large diameter plunger at high speed to inject the plunger. The amount of fuel supplied to the fuel injection nozzle is controlled based on the amount of movement.

[The problem that the idea aims to solve]

The metering piston device constituting the metering section in the conventional fuel injection device includes, for each pressure booster plunger,
In other words, they are installed in accordance with the number of cylinders in the engine, and as a result, the number of metering piston devices increases and becomes more complex, and the operation of each metering piston device becomes uneven, and in some cases, all cylinders may operate in the same manner. There were problems such as difficulty in producing output.

[Means to solve the problem]

The present invention aims to eliminate the drawbacks of the metering piston device constituting the metering section in the conventional pressure booster plunger type fuel injection device, and the present invention has a configuration to achieve this purpose. In this method, a switching servo valve is provided in the middle of each fuel oil supply pipe connecting the fuel pump and the pressure boosting plungers of the same number as the number of cylinders, and when the switching servo valve switches the communication between the fuel pump and the pressure boosting plungers, the switching operation is performed. ,
A metering piston device is provided that communicates with the pressure booster plunger, and the metering piston device has a stopper that is displaced according to the engine output and a metering piston of the same number as the number of cylinders whose strokes are regulated by the stopper. This is a pressure plunger type fuel injection device.

〔Example〕

Examples of the pressure booster plunger type fuel injection device of the present invention will be described below, but first, the schematic structure of the pressure booster plunger type fuel injection device most suitable for applying the present invention will be explained with reference to Fig. 1. .

In the figure, reference numeral 1 denotes a pressure booster plunger, which operates a small diameter plunger 5 of a plunger pump 4 by a large diameter plunger 3 housed in a cylinder 2 to pressurize the fuel in a fuel chamber 6 and inject fuel into a fuel injection nozzle 7.
and injected into each cylinder of an internal combustion engine (not shown).

A switching servo valve 8 is connected to the pressure increase plunger 1, and the switching servo valve 8 is configured to be controlled by a four-way solenoid valve 9.
Further, a metering piston device 10, which constitutes an important part of the metering section, is connected to the switching servo valve 8.

The switching servo valve 8 has three consecutive pistons 8b, 8c, and 8d housed in a cylinder 8a, and the pistons are pushed to the right in the figure by a spring 8e.

The four-way solenoid valve 9 has a valve body 9 pressed by a spring 9a.
b, and the fuel tank 1 is opened by this valve body 9b.
1. Pump 12, reflux pipe 13 and switching servo valve 8
It is configured to switch the pipe line between the cylinder 8a and the cylinder 8a.

The fuel chamber 6 of the plunger pump 4 has a check valve 1.
4, and is connected to a pipe 16 connecting the fuel pump 15 and the switching servo valve 8, and is configured to drive the large diameter plunger 3 by the pressure oil discharged from the fuel pump 15. . Further, a communication port 8g provided in the cylinder 8a of the switching servo valve 8 and the fuel tank 11 are connected by a recirculation pipe 17.

The metering piston device 10 is composed of a cylinder 10a, a metering piston 10b, a stopper 10c, and a spring 10d, and the metering piston 10b is moved to the right by the oil pressure in the pipe 18 that connects the switching servo valve 8 and the metering piston device 10. However, the movement is stopped by contacting the stopper 10c, and when the pressure inside the cylinder 10a decreases, the movement is moved to the left by the action of the spring 10d and returned to the original position.

The stopper 10c is a member that changes its stop position according to the output of the internal combustion engine, and is driven (in the left-right direction in FIG. 1) by, for example, an accelerator pedal.

The pressure booster plunger type fuel injection device according to the present invention preferably relates to an improvement of the metering piston device constituting the metering section of the fuel injection device shown in FIG. 1.

Specifically, the present invention provides a device configured to meter the amount of fuel supplied to a plurality of cylinders of an internal combustion engine using a single metering piston device.

FIG. 2A is a side sectional view showing details of the metering piston device 20, and FIG. 2B is a front view thereof. Further, a cylinder 23 is arranged in an annular shape in the main body 21 corresponding to the port 22.
A measuring piston 24 is slidably inserted into each of the measuring pistons 24, and a spring 25 is provided to press behind the measuring piston 24. The end of this spring 25 is supported by a support 28.

A guide hole 29 is formed in the support body 28 in an annular shape toward the center of the cylinder 23.
A rod 30 is slidably fitted therein, and the end of the rod 30 is in contact with a stopper 31. A keyway 33 is provided in the hole 32 in the center of this stopper 31.
A key 37 provided on a shaft 36 is fitted into a hole 35 provided at the center of the lid portion 21a of the main body 21. At the end of this shaft 36, there is provided a member that moves in proportion to the output of the internal combustion engine, such as a lever 38 connected to an accelerator pedal.

The main body 21 is provided with a threaded portion 40, and a threaded portion 41 provided on the stopper 31 is screwed into this threaded portion 40. Therefore, when the lever 38 rotates in accordance with the output of the internal combustion engine, the shaft 3
6. The stopper 31 is rotated via the key 37 and moved in the axial direction (left and right direction) by the action of the threaded portion. As the stopper 31 moves, the position where the movement of the rod 30 is restricted changes, and eventually the position where the metering piston 24 is stopped changes, and depending on the position of the metering piston 24, the injection into the cylinder is made. The amount of fuel will be controlled.

In the present invention, as shown in FIG.
There are a plurality of cylinders 23 corresponding to the number of cylinders of the internal combustion engine inside, and a metering piston 2 housed inside the cylinders 23.
4, the stopping position of the rod 30 that contacts one side of the piston 24 is regulated by one stopper 31, and the stopper 31 is moved back and forth toward the metering piston 24 in relation to the output of the internal combustion engine. It is distinctive in its composition.

Therefore, if the number of cylinders of the internal combustion engine is six, for example, six metering pistons 24 are provided in an annular shape along the cylindrical body, and the rod 30 is also provided in an annular shape in accordance with the metering piston 24. Further, the stopper 31 is formed into a disk shape, and a shaft 36 is provided in the center thereof so as to be movable back and forth as described above. Note that the main body 21 is provided with a discharge port 43 for discharging leaked fuel to the outside.

Metering piston device 20 of the present invention shown in FIG.
is provided for one internal combustion engine, and the main body 2
The fuel supply port 22 provided in the fuel injection device 1 is connected to the switching servo valve 8 of the fuel injection device, which is composed of the pressure booster plungers 1 provided as many as the number of cylinders, the switching servo valve 8, etc., as shown in FIG. 1. has been done.

For convenience of explanation, the operating state of the fuel injection device shown in FIG. 1 will be explained. 3 and 4 are diagrams showing the operating state of the switching servo valve 8 in the device shown in FIG. 1.

(1) Measuring fuel Measuring start position, that is, plunger pump 4
The initial position when sucking fuel into the pump is that the small diameter plunger 5 of this plunger pump 4 and the large diameter plunger 3 of the pressure booster plunger 1 that drives it are at the lowest position as shown in FIG. .

Series of pistons 8b, 8 of switching servo valve 8
c and 8d are pushed by the spring 8e and moved to the right end side as shown in FIGS. 1 and 3. On the other hand, a pipe 16 connects the fuel pump 15 that supplies fuel into the plunger pump 4 and the cylinder 8a of the switching servo valve 8.
is closed by the piston 8b, and a pipe 18 connecting the cylinder 2 of the pressure booster plunger 1 and the metering piston device 20 is communicated through a gap between the pistons 8b and 8c. Therefore, when the large diameter plunger 3 is raised, the metering piston device 20 is ready to operate due to the pressure in the tube 18.

The fuel in the fuel tank 11 is pressurized by the fuel pump 15 and supplied to the plunger pump 4 via the check valve 14, causing the small diameter plunger 5 to rise as indicated by arrow B in FIG. Then, the fuel filled in the upper part of the large diameter plunger 3 passes through the gap between the pistons 8b and 8c of the switching servo valve 8 and the pipe 18 to the metering piston device 20,
10 to move the metering piston 24, 10b to the right as shown by arrow C against the springs 25, 10d.

As mentioned above, when the metering piston 24 moves to the right in the drawing against the spring 25, the rod 30 comes into contact with the stopper 31 and stops in FIG. 2A.

In this way, when the metering piston 24 stops, pressure rises instantaneously in the pipe 18 that communicates the metering piston device 20 and the switching servo valve 8, and finally the force acting on the tip surface of the small diameter plunger 5 increases. The large diameter plunger 3 and the small diameter plunger 5 stop in a state where the force acting on the diameter plunger 3 is balanced.

This state is the completion of metering by the metering piston device 20, and the large diameter plunger 3 rises from the lowest position, causing the metering piston 24 of the metering piston device 20 to rise.
is raised until it is stopped by the stopper 31, and the necessary amount of high-pressure fuel to be injected next is sucked into the fuel chamber 6 of the plunger pump 4.
(Fig. 4) (2) Fuel injection stroke Next, the four-way solenoid valve 9 is energized, the valve body 9b moves in the direction of arrow A (downward) in Fig. 1, and the fuel from the low-pressure pump 12 (relatively low pressure (fuel) is supplied into the cylinder 8a of the switching servo valve 8 as shown by arrow D in FIG. 4, and moves the piston 8d to the left against the spring 8e.

FIG. 4 shows a state in which this operation has been completed, in which the piston 8d moves to the left against the spring 8b, and the high pressure discharged from the fuel pump 15 through the gap between the pistons 8b and 8c. fuel pipe 16
The large-diameter plunger 3 is momentarily lowered, and the high-pressure fuel in the fuel chamber 6 is supplied to the fuel injection nozzle 7 by the small-diameter plunger 5.
A measured amount of fuel is injected from the fuel injection nozzle 7 into the combustion chamber in the cylinder of the engine.

In the process of the small diameter plunger 5 rising, the pressure of high pressure fuel discharged from the fuel pump 15 acts on the tip surface of the small diameter plunger 5, but when injecting fuel as described above, the pressure of the large diameter plunger 3 is Since the pressure of the fuel pump 15 acts on the surface, the fuel in the plunger pump 4 is pressurized and injected in proportion to the ratio of the areas of both plungers 3 and 5.

This fuel injection continues until the large diameter plunger 3 of the pressure booster plunger 1 moves to the lowest position, which is the starting point of metering, and this large diameter plunger 3
The process ends in a state where the machine stops at the lowest position. (The state shown in Fig. 3 changes from the state shown in Fig. 4.) On the other hand, the reflux pipe 17 and the pipe 18 connected to the metering piston device 20 are in a connected state due to the gap between the pistons 8c and 8d. Therefore, the fuel filled in the pipe 18, metering piston device 20, and switching servo valve 8 flows out as indicated by arrow E in FIG. 4 and flows back into the fuel tank 11. During this process, the measuring pistons 24, 10b of the measuring piston device 20 are pressed by the springs 25, 10d and move to the left in preparation for the next measurement.

(3) Return operation of the servo valve As shown in Fig. 4, the back of the large-diameter plunger 3 is pressed by the high-pressure fuel sent out from the fuel pump 15 to complete fuel injection. When the small diameter plunger 5 of No. 4 moves to the lowest position, the state shown in FIG. 3 is again achieved.

In this state, when the electromagnetic valve 9 is de-energized, the valve body 9b is pushed by the spring 9a and rises in the direction opposite to the arrow A, resulting in the state shown in FIG.

In this state, as shown in FIG. 1, the cylinder 2 of the pressure booster plunger 1 and the metering piston device 2 are
0 are connected via a pipe 18. On the other hand, the pipe 16 of the fuel pump 15 is closed by the piston 8b, and the pipe on the check valve 14 side is opened, so that the high pressure fuel discharged from the fuel pump 15 is transferred to the plunger pump 4. It is supplied into the chamber 6 and the small diameter plunger 5 rises.

In the ascending process of the small diameter plunger 5,
The piston 3 integrated with this small-diameter plunger 5 rises, and fuel is supplied to the metering piston device 2 via the pipe 18.
0, 10 cylinders 23, 10a,
This metering piston 24, 10b is the stopper 3
1, 10c and the pressure within the pipe 18 connecting the switching servo valve 8 and the metering piston device 20 is increased, the large diameter plunger 3, that is, the small diameter plunger 5 is stopped from rising, and then This completes the measurement of the fuel to be injected.

[Effect of idea]

As explained above, the metering device in the pressure booster plunger type fuel injection device according to the present invention is provided with switching servo valves in the middle of the fuel oil supply pipes connecting the fuel pump and the pressure booster plungers of the same number as the number of cylinders. A metering piston device is provided that communicates with the pressure booster plunger when the switching servo valve is switched to disconnect or disconnect communication between the fuel pump and the pressure booster plunger, and the metering piston device includes a stopper that is displaced according to the engine output, and a stopper that is displaceable according to the engine output. It is characterized by having the same number of built-in metering pistons as the number of cylinders whose strokes are regulated, and the following effects can be achieved.

(b) The metering piston device in the pressure booster plunger type fuel injection device according to the present invention has the same number of metering pistons as the number of cylinders of the internal combustion engine built into one main body, so the arrangement of the metering piston device is simple. Space is significantly compacted.

(b) Also, since the positions of the plurality of metering pistons provided in the main body according to the number of cylinders of the internal combustion engine are regulated by one stopper, the positions at which the plurality of metering pistons stop are regulated by one stopper. can be regulated all at once. In this manner, the stop positions of the individual metering pistons can be accurately regulated, and as a result, the fuel metering of the individual metering pistons becomes accurate and does not vary from one another.

(c) Furthermore, the stopper of the metering piston device is
Since its position is displacement-adjusted in accordance with the output of the internal combustion engine, fuel metering can be performed in accordance with the output of the engine, which has the effect of increasing the output of the engine.

In the embodiment shown in FIG. 2, the driving means for the stopper 31 is constructed by the screw portions 40 and 41, so that the rotation of the lever 38 can be accurately transmitted to the back and forth movement of the stopper 31. It is. However, as the drive means for the stopper 31, for example, means such as a cam that moves in relation to the output of the internal combustion engine may be employed.

[Brief explanation of the drawing]

Figure 1 is a pipeline diagram showing the main parts of a pressure booster plunger type fuel injection system that is most suitable for applying the metering device in the pressure booster plunger type fuel injection system of the present invention, and Figure 2-A is a main part of the pressure booster plunger type fuel injection system of the present invention. 2-B is a front view of the same, and FIGS. 3 and 4 show the relationship between the large-diameter plunger of the pressure booster plunger and the switching servo valve in the metering state. FIG. 3 is a diagram showing a state immediately before fuel is sucked into the plunger pump, and FIG. 4 is a diagram showing a state during fuel injection. 1... Pressure booster plunger, 2... Cylinder, 3...
...Large diameter plunger, 4...Plunger pump, 5
... Small diameter plunger, 6 ... Fuel chamber, 8 ... Switching servo valve, 9 ... Four-way solenoid valve, 14 ... Check valve, 15 ... Fuel pump, 20 ... Metering piston device, 21 ... Main body, 22... Fuel supply port, 23... Cylinder, 24... Metering piston,
25...Spring, 28...Support, 29...
Guide hole, 30...rod, 31...stopper,
32...hole, 33...keyway, 35...hole, 36
...Shaft, 37...Key, 38...Lever, 40...
... Threaded portion, 41... Threaded portion, 43... Fuel discharge port.

Claims (1)

[Scope of utility model registration request] A switching servo valve 8 is provided in the middle of each fuel oil supply pipe 16 connecting the fuel pump 15 and the same number of pressure booster plungers 1 as the number of cylinders.
A metering piston device 20 is provided which communicates with the pressure booster plunger 1 when the communication between the fuel pump 15 and the pressure booster plunger 1 is switched. This is a pressure booster plunger type fuel injection device which incorporates the same number of metering pistons 24 as the number of cylinders whose stroke is regulated by a stopper 31.