JPS6267277A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To adjust an injection pressure as well as an injection quantity in response to various loads, by providing an injection pressure adjusting plunger in addition to an injection quantity adjusting plunger, and carrying out adjustment of the injection pressure by adjusting a stroke of the injection pressure adjusting plunger. CONSTITUTION:A compression chamber 37 of an injection plunger 16 for adjusting a fuel injection quantity is communicated through a communication hole 39 to a decompression chamber 40 of a pressure reducing plunger 17 for adjusting a fuel injection pressure. The pressure reducing plunger 17 is connected through a lever having a movable adjustable fulcrum pin 28 to a reciprocating plunger driving rod 31. Under low load, operation of the pressure reducing plunger 17 is stopped, while under high load, the plunger 17 is maximally operated. Under the intermediate load, the plunger 17 is operated to a degree intermediate therebetween. Adjustment of a stroke of the pressure reducing plunger 17 is carried out by moving the fulcrum pin of the lever. Accordingly, when the injection pressure is intended to be increased, the fulcrum pin of the lever is so moved as to reduce the stroke of the pressure reducing plunger 17. In contrast, when the injection pressure is intended to be decreased, the fulcrum pin is reversely moved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fuel injection pump.
It is used as a fuel pump for internal combustion engines such as diesel engines.

Conventional technology Bosch type fuel injection pumps are often used as fuel injection pumps for conventional diesel engines, but this type of fuel injection pump only controls the injection amount for each load, and the injection pressure is matched at the rated output.

Problems to be Solved by the Invention As mentioned above, conventional fuel injection pumps only control the injection amount for each load, so if the injection system is matched at the rated output, it will be possible to reduce the injection amount at low loads when the injection amount is small. There is a problem in that the injection pressure decreases and combustion becomes violent, and if matching is done at a low load, the injection pressure will rise too much at high loads with a large injection amount, leading to mechanical damage. There is a point. The present invention attempts to solve these problems. That is, an object of the present invention is to provide a fuel injection pump that can improve combustion by adjusting not only the injection amount but also the injection pressure for each load. be.

Means for solving the problem: In addition to the injection amount adjustment plunger, an injection pressure adjustment plunger is provided, and the injection pressure is adjusted by adjusting the stroke of the injection pressure adjustment plunger. That is, the configuration of the present invention includes, in addition to the injection plunger for adjusting the fuel injection amount, which is connected to the plunger drive rod that reciprocates by the rotation of the cam and is incorporated into the fuel pump body of the internal combustion engine. a pressure reducing sylanger for adjusting the fuel injection pressure built into the fuel pump main body in parallel, and - the injection pressure can be adjusted by adjusting the stroke of the pressure reducing plunger; A compression chamber, which is a plunger chamber of the plunger, and a decompression chamber, which is a plunger chamber of the decompression plunger, are connected through a communication hole, and the decompression plunger is connected to the plunger via a lever having a movable and adjustable fulcrum bottle as a fulcrum. It is characterized by being connected to a drive rod.

Operation The stroke of the vacuum plunger can be adjusted by moving the fulcrum of the lever.

Therefore, if you want to increase the injection pressure, move the fulcrum of the lever so that the stroke of the decompression plunger becomes smaller.
Conversely, if you want to reduce the injection pressure, move the fulcrum in the opposite direction.

Embodiment FIG. 1 shows an embodiment of the present invention. In the figure, 1 is the fuel pump body of the diesel engine, 2 is the roller guide, 5 is the pump head, 4 is the engine frame, 5 is the cam, 6 is the roller, 7 is the roller bush, 8 is the roller bin, and 9 is the discharge port. cylinder, 10 is a discharge valve, 11 is a discharge valve spring, 12 is an injection barrel holder, 15 is a vacuum barrel holder, 14 is an injection barrel, 15 is a vacuum barrel, 16 is an injection plunger, 17 is a pressure reduction plunger, 18 is a gear cutter. , 19 is the rack axis, 20
21 is a gear holder, 21 is a spring holder, 22 is a decompression plunger spring, 23 is a spring holder, 24 is a ball head holder, 25 is a plunger fixing hardware, 26 is a fixing pin, 27 is a fulcrum holder, and 28 is a fulcrum pin. , 29 is a sliding hardware, 30 is a lever as a lever, 31 is a plunger drive rod, 32 is a roller spring, 33 is a plunger drive rod fixing hardware, 34 is a mounting bolt, and 35 is a roller piston.

That is, an injection plunger 16 and a pressure reduction plunger 17 are inserted into the injection barrel 14 and the pressure reduction barrel 15, respectively, and incorporated into the fuel pump main body 1. Each of the barrels 14 and 15 is connected to the pump head 3 via an injection barrel holder 12 and a vacuum barrel holder 13, respectively.

A discharge valve housing 9 is attached to the pump head 6, and a discharge valve 10 and a discharge valve spring 11 are assembled therein.

A gearing 18 is rotatably attached to the lower end of the injection barrel 14. This gear piece 18 is connected to the rack shaft 19 on the left side.
The injection plunger 16 is further engaged with the lower gear of the injection plunger 16. By moving the rack shaft 19 back and forth, the gear cutter 18 is rotated, and the injection plunger 16 meshed therewith is rotated. In addition, the injection plunger 16 is connected to the gear cutter 1.
It has a structure that allows it to slide relative to 8 in the vertical direction. A vacuum grading spring 22 is installed at the bottom of the vacuum lever 15 via a spring holder 21 and is supported by a spring receiver 26 attached to the bottom of the vacuum plunger 17 . The lower part of the decompression plunger 17 has a spherical head and rests on the Leno (-30) via the spherical head receiver 24.

The injection plunger 16 is rotatably attached to a plunger drive rod 31 via a plunger fixing hardware 25.

Further, a boss for supporting a fixing pin 26 is formed on the fixing hardware 25. A lever 30 that can rotate around this fixing pin 26 is attached, and a groove is cut in the center of the lever 30, and a fulcrum pin 28 can be moved into this groove via a sliding metal fitting 29. installed on. The fulcrum pin 28 is supported by a fulcrum holder 27, and the fulcrum holder 27 has a structure that allows it to move in a diagonal groove cut into the fuel pump body 1. The plunger drive rod 31 is attached to the roller piston 65 with a mounting bolt 34 via a plunger drive rod fixing hardware 63. Further, the roller piston 35 is incorporated so as to be able to slide on the inner surface of the roller guide 2. The roller 6 is attached to a roller piston 65 with a roller pin 8 via a roller bush 7. Roller guide 2 and roller piston 65
The roller spring 32 is assembled and twisted between the rollers 6 and cam 5.
The structure is such that it is pressed down so that it makes contact with the

4 to 7 are explanatory diagrams of the principle of adjusting the injection pressure by the injection plunger 16 and the pressure reducing plunger 17 shown in FIG. 1. Figure 4 shows the start of injection under high load, and Figure 5 shows the end of injection under high load.
FIG. 6 shows the start of injection at low load, and FIG. 7 shows the end of injection at low load.

4 to 7, 36 is a notch hole provided in the injection barrel 14, 37 is a compression chamber which is a plunger chamber of the injection plunger 16, and 38 is a notch hole provided in the injection plunger 16. , 69 is the compression chamber 37
and a communication hole connecting a decompression chamber 40, which will be described later, 40 is a decompression chamber which is a plunger chamber of the decompression plunger 17;
1 is a high pressure pipe attachment hole. The arrow 42 shown in Figures 4 and 6 indicates the fuel supply, and dl shown in Figure 4 is the ridge.
is the diameter of the injection plunger 16, and d2 shown in the figure
is the diameter of the pressure reducing plunger 17.

That is, the diameter d1 of the injection plunger 16 is selected so that a necessary and sufficient injection pressure can be obtained even when the engine is operated at the maximum load and the pressure reduction plunger 17 performs the maximum stroke pressure reduction operation. In other words, the effective stroke of the injection plunger 16 at maximum load is /1, and the effective stroke of the pressure reducing plunger 17 is 12.
Then, the required injection volume at maximum load is as shown in the following equation.

-(di l!, -d蕃e2) The principle of operation is that at low loads, the decompression plunger 17 stops operating, at high loads, the decompression plunger 17 is operated to the maximum, and at intermediate loads, the decompression plunger 17 is operated to the maximum level. It allows you to perform the following movements.

In FIG. 4, when the plunger drive rod 61 rises and the tip of the injection plunger 1B closes the cutout hole 56 of the injection barrel 14, compression of fuel for injection begins. Compression chamber 37
The fuel is pressurized and led to the decompression chamber 40 through the communication hole 39. Now, since the fulcrum pin 28 of the fulcrum receiver 27 is placed between the fixing pin 26 and the axis of the decompression plunger 17, as the injection plunger 16 rises, the decompression plunger 17 is pulled down by the lever 30 as a lever. Descend. Therefore, the pressure in the decompression chamber 40 decreases,
The pressure obtained by subtracting the pressure reduced in the pressure reduction chamber 40 from the pressure increased in the compression chamber 37 is discharged from the high pressure pipe attachment hole 41 via the discharge valve 10 as injection pressure.

FIG. 5 shows a state when the notch hole 68 at the top of the injection plunger 16 has passed through the notch hole 36. At this time, the compression chamber 67 and the notch hole 36 are communicated with each other, and the compression of the fuel is completed and the injection is completed.

In FIG. 6, by moving the rack shaft 19, the gear cutter 18 is
rotates, and the injection plunger 16 meshed with it rotates. For this reason, the position of the notch hole 38 of the injection plunger 16 relative to the notch hole 36 of the injection lever 14 is changed compared to FIG. In this case, the fulcrum pin 28 of the fulcrum receiver 27 is placed in a position that coincides with the axis of the decompression plunger 17.The protruding tip of the injection plunger 16 closes the notch hole 36, and the fuel in the compression chamber 37 is pressurized. The fuel is led to the decompression chamber 40 through the communication hole 39, but the lever 30
The pressure reducing plunger 17 only rotates around the fulcrum pin 28 located below the axis of the pressure reducing plunger 17, and the pressure reducing plunger 17 does not descend. Therefore, there is no volume change in the decompression chamber 40, and the fuel pressurized in the compression chamber 37 is not depressurized. Since the diameter d, of this injection plunger 16 is designed to be larger than the design value of a normal injection plunger, at this low load, the injection pressure increases more than in the case of a normal plunger. The pressurized fuel passes through the discharge valve 10 and is discharged from the high pressure pipe attachment hole 41.

In FIG. 7, the compression chamber 57 and the notch hole 36 are in communication with each other, the compression of the fuel is completed, and the injection is completed.

FIG. 2 is an explanatory diagram of an injection pressure waveform by a conventional fuel injection pump, and FIG. 6 is an explanatory diagram of an injection pressure waveform by the fuel injection pump of the present invention shown in FIG. time on the horizontal axis. Curve a in Figure 2 is the injection pressure waveform at low load, and curve a is highly negative! The injection pressure waveform at load time, straight line C is the combustion top, curve d in Fig. 3 is the injection pressure waveform at low load,
The curve θ is the injection pressure waveform at high load. Note that curve a in FIG. 2 is shown in FIG. 3 for comparison of the injection pressure waveform at low load. The curve in Figure 2 and the curve θ in Figure 3 are the same.

In other words, as shown in Fig. 2, conventionally, when the load is low, the maximum injection pressure T'l decreases, causing combustion to worsen.
However, there was a drawback that the fuel efficiency rate decreased. In Figure 6,
Due to the operation of the pressure reducing plunger 17 explained in FIGS. 4 and 5, the injection pressure p2 is maintained at the same level as before at high loads, but at low loads the operation of the pressure reducing plunger 17 explained in FIGS. 6 and 7 is maintained. By discontinuing the injection, the injection pressure becomes p (p>p+), and the above-mentioned conventional drawbacks are eliminated.

Effects of the Invention The present invention includes a pressure reducing plunger for adjusting fuel injection pressure in addition to an injection plunger for adjusting fuel injection amount, and
゛The injection pressure is adjusted by moving the fulcrum of one lever that adjusts the stroke of the pressure reduction plunger, so when the load is low, the operation of the pressure reduction plunger is stopped in order to obtain the necessary and sufficient injection pressure. At maximum load, the fulcrum is moved to prevent the injection pressure from being too high to operate the depressurizing plunger to the maximum, and at intermediate loads, the fulcrum is selected at a position suitable for the intermediate load to set the injection pressure to the optimum value. Therefore, the optimum fuel injection amount and optimum injection pressure can be guaranteed for each load. Therefore, fuel atomization is improved for each load, resulting in good combustion performance and fuel savings.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of an injection pressure waveform by a conventional fuel injection pump,
Figure 3 is an explanatory diagram of the fuel injection pressure waveform by the fuel injection pump in Figure 1, Figure 4 is an explanatory diagram showing the state of the fuel injection pump in Figure 1 at the beginning of injection at high load, and Figure 5 is An explanatory diagram showing the state at the end of injection under high load.
FIG. 6 is an explanatory diagram showing a state at the beginning of injection at a low load, and FIG. 7 is an explanatory diagram showing a state at the end of injection at a low load. 1... fuel pump body, 5... cam, 16...
Injection plunger, 17. ,, pressure reduction plunger, 27...
・Fulcrum holder, 28...Fulcrum pin, 30...Lever,
31... Plunger drive rod, 37... Compression chamber, 39
...Communication hole, 40...Decompression chamber. Figure 1 Page A

Claims (1)

[Claims] 1. In addition to an injection plunger for adjusting the fuel injection amount, which is connected to a plunger drive rod that reciprocates by the rotation of a cam and is incorporated into the fuel pump body of the internal combustion engine, the fuel pump is connected in parallel with the injection plunger. Equipped with a pressure reducing plunger for adjusting fuel injection pressure built into the main body, and
A compression chamber, which is a plunger chamber of the injection plunger, and a decompression chamber, which is a plunger chamber of the decompression plunger, are connected through a communication hole so that the injection pressure of the fuel can be adjusted by adjusting the stroke of the decompression plunger. A fuel injection pump characterized in that the pressure reducing plunger is connected to the plunger drive rod via a lever having a movably adjustable fulcrum pin as a fulcrum.