JPS6050983B2 - Diesel engine fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in fuel injection systems for diesel engines.

The configuration of a conventional fuel injection device of this type is shown in FIG.

In the figure, 1 is a fuel cam, 2 is a tappet with a cam roller, 3 is a jerk type fuel pump, 4 is an injection pipe, and 5 is a fuel valve. As the fuel camshaft rotates, the fuel cam 1 pushes up the tappet 2 with a cam roller, pushes the plunger (not shown) sliding inside the fuel pump 3, compresses the fuel inside, and sends it to the injection pipe 4, which injects fuel into the injection pipe 4. When reaching the valve 5, the built-in automatic valve automatically opens the valve when the pressure exceeds a certain valve opening pressure, and fuel is injected from the nozzle hole at the tip to the cylinder liner 7, piston 8, and cylinder cover 9. The air compressed and heated to a high temperature in the combustion chamber 6 thus configured causes ignition and combustion. Figure 1 shows the case of one fuel pump, one injection pipe, and one fuel valve, while Figure 2 shows the case of one fuel pump, two injection pipes (branch pipes), and two fuel valves. The case of a fuel valve is shown. The configuration is almost the same as that shown in FIG. 1, but the fuel oil coming out of the fuel pump 3 is divided into two injection pipes 41 and 42 and injected into the combustion chamber 6 from two fuel valves 51 and 52 almost simultaneously. It has a structure like this. Diesel engines achieve good performance with this system, but fuel injection systems are generally designed to be optimal at rated output.

As a result, the nozzle area of the fuel valve is too large in the low-speed and low-load ranges, making it impossible to achieve good injection at high pressures as at high-speeds and high-loads, and only spraying with poor atomization and poor penetration power occurs at low pressures. cannot be formed. As a result, it is difficult to achieve good combustion in the low speed range and low load range. Particularly in the current situation where vessels operate at reduced speeds, this poor speed is a major problem, and a solution is needed. Ideally, at low engine speeds and low load regions, the nozzle hole area should be made small to prevent a drop in injection pressure to maintain combustion performance, and at high speeds and high load regions, the nozzle hole area should be reduced. It is desirable to increase the injection pressure to prevent excessive injection pressure and to improve the sharpness of injection, thereby achieving a good fuel efficiency.

The purpose of the present invention is to focus on the above points, and to reduce the nozzle hole area to
Substantially changing the low load range, high speed, and high load range,
Our goal is to provide a fuel injection device that can maintain high injection pressure even in low speed and low load regions to obtain good spray and achieve efficient combustion. A plurality of independent fuel valves or one composite fuel valve consisting of a plurality of fuel valves are installed in the 2000, and the plurality of fuel valves are divided into two groups, and the injection pipes are combined into one injection pipe for each group. Each of the two fuel valve groups is connected to a distributor, and the distributor is further connected to a fuel pump, and the two fuel valve groups are connected to each other alternately every other revolution of the fuel camshaft in the low speed or low load range of the engine. The fuel pump is connected to the fuel pump, and all fuel valves are configured to communicate with the fuel pump at all times in the high speed range.

In this case, it is possible to improve combustion efficiency during deceleration operation of ships and to improve low-speed performance of small vehicle engines and the like. The present invention can be widely applied to engines having fuel injection devices such as large diesel engines for land and marine use, small diesel engines for vehicles, construction, agriculture, and small marine use.

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

FIG. 3 is an explanatory diagram showing a first embodiment of the apparatus according to the present invention.

This device has two fuel valves and is basically the same in construction as the conventional device shown in FIG. 2, but includes a distributor, its drive and control device, etc. In the figure, 1
is a fuel cam, which is equipped with a fuel camshaft and is driven in a certain relationship with a crankshaft (not shown).

2 is a tappet with a roller, 6 is a fuel pump, 4 is a common injection pipe, 43 and 44 are branch injection pipes, 51 and 52 are fuel valves, and the combustion chamber is constituted by a cylinder 7, a piston 8, and a cylinder cover 9. A nozzle hole is opened in 6.

The common injection pipe 4 and the branch injection pipes 43, 44 are connected via a distributor 40, which connects a gear 101 with a camshaft to a chain (or toothed belt) 106, 10.
7, intermediate gears 102, 103, and gear 10 with a distributor shaft
4 and is driven at a rotational speed of 112 of the camshaft speed.

The structure of the distributor is shown in FIG.

That is, FIG. 4A is a sectional view showing the structure of the distributor, and FIG. 4B is a sectional view taken along the line BB in FIG. 4A. Reference numeral 401 denotes a distributor body, which incorporates a rotatable distributor shaft 402, which has distribution grooves 403 and 404, and which connects the drive gear 104 and the fitting part 4.
05, and can also slide in the axial direction.

There is a collar 406 at the other end of the distributor shaft 402, with which a control handle 407 is engaged, and by moving the handle 407 left and right, the distributor shaft 402 can be moved left and right, as shown in FIG. At the solid line position A, as shown in FIG.
07 to the dashed line position, the distributor shaft 402 moves to the left, and the distribution groove 404 communicates with the common injection pipe, and since it is a circumferential groove, it is always in communication with the branch injection pipes 43 and 44 at the same time. I will do it.

In this state, it will perform exactly the same function as a normal injection device (FIG. 2). The operation in the case of the above configuration will be described.

If the handle 407 shown in FIG. 4A is set to the broken line position (during high-speed, high-load operation), the common injection pipe 4
4 is in communication with the branch injection pipes 43 and 44 at all times, and the two fuel valves 51 and 52 are connected with the fuel pump 3 regardless of the rotation of the distributor shaft 402, allowing for high-speed, high-load operation. It becomes a suitable device.

When the handle 407 in FIG. 4A is set to the solid line position (at low speed or low load), the common injection pipe 4
, the distributor shaft 402 rotates at a speed of 112 of the camshaft.

This distribution groove 403 is formed approximately 2B on the circumference, and is configured so that either the branch injection pipe 43 or 44 communicates with the common injection pipe 4 depending on the rotation angle of the shaft 402. In the case of B in the figure, the common injection pipe 4 and the branch injection pipe 43 are in communication, and at the next injection timing, they rotate 1800 times, so
It comes to communicate with the branch injection pipe 44. Therefore, in this injection pipe system, the fuel valves 51 and 52 are operated (injected) alternately in the low speed range and low load range by the distributor 40.
There is only one fuel valve for one plunger of the fuel pump 3, and the actual nozzle hole area can be reduced to 112, so the injection pressure increases significantly even when rotating at low speed, ensuring good spray. It becomes possible to form.

The above case has the following effects.

At high speeds and high loads, it operates in the same manner as before, achieving high performance at the rated level, and at low speeds or low loads, by alternately injecting from the two nozzle holes, the injection pressure is increased and good performance is achieved. Combustion performance is improved by forming a spray, and effective combustion performance can be achieved over a wide range of conditions, from high speeds and high loads to low speeds and low loads.

FIG. 5 is an explanatory diagram showing a second embodiment of the apparatus according to the present invention.

In the embodiment shown in FIG. 3, each cylinder was configured with two fuel valves, but in this embodiment, four fuel valves are provided, and the fuel oil discharged from the fuel pump 3 is The common injection pipe 4 leads to the distributor 40, from which it is divided into branch injection pipes 43 and 44, which further branch into branch pipes 431, 432 and 441, 442, and the fuel valve 511 attached to the cylinder cover 9. , 512 and 521
, 522.

The operation is exactly the same as in the first embodiment, and the fuel valves 511, 5
12 and fuel valves 521 and 522 are in the low speed range,
They operate alternately in low load ranges, and operate all at once in high speed and high load ranges.

The effect is also similar to that of the first embodiment.

FIG. 6A is an explanatory diagram showing a third embodiment of the apparatus according to the present invention, and FIG. 6B is a sectional view taken along the line B--B in FIG. 6A (7).

In the conventional central injection type fuel injection system shown in Fig. 1, a composite fuel valve with the functions of two fuel valves is installed in one fuel valve, as shown in Fig. 6. Show details. In the figure, cam 1, tappet with roller 2, fuel pump 3
, the common injection pipe male distributor 40, and the branch injection pipes 43 and 44 are the same as those in FIGS. 3 and 4 of the first embodiment.

The feature of this embodiment is in the fuel valve 55, and this fuel valve 55 has 1
The nozzle chip 5510 has the functions of two completely built-in fuel valves, that is, one fuel valve is composed of two fuel valves, and the nozzle tip 5510 has an inner row nozzle hole 5511 and an outer row nozzle hole 5511. The nozzle holes 5521 are opened independently of each other, and their opening is controlled by opening pressure adjusting springs 5514 and 5524.

Oil passage 551 is opened and closed by needle valves 5512 and 5522.
It communicates with the aforementioned branch injection pipes 43 and 44 via No. 3 and 5523. The operation is exactly the same as in the first embodiment, and at low speed or low load, the inner row nozzle holes 5511 and the outer row nozzle holes 5521
Therefore, at high speeds and high loads, both rows of nozzle holes inject at the same time, so at low speeds or low loads, the nozzle hole area becomes 112, and at high speeds and high loads, the nozzle area becomes 112.
High injection pressure can be ensured from high load to low speed or low load, and good combustion characteristics can be achieved.

Note that the structure of the distributor is not limited to the configuration of this embodiment, and includes those that can achieve the functions aimed at by the present invention by electrical or other methods.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional fuel injection device having one fuel valve, FIG. 2 is an explanatory diagram showing a conventional fuel injection device having a plurality of fuel valves, and FIG. 3 is an explanatory diagram showing a conventional fuel injection device having a plurality of fuel valves. An explanatory diagram showing the device of one embodiment, FIG. 4A is a cross-sectional view showing the structure of the distributor, FIG. 4B is a cross-sectional view taken along the line B-B in FIG. 4A (7),
FIG. 5 is an explanatory diagram showing a second embodiment of the apparatus according to the present invention, FIG. 6A is an explanatory diagram showing a third embodiment of the apparatus according to the present invention, and FIG. 6B is B of FIG. 6A. -B is a sectional view taken along the arrow. DESCRIPTION OF SYMBOLS 1... Fuel cam, 3... Fuel pump, 4... Common injection pipe, 40... Distributor, 43, 44... Branch injection pipe, 51, 52, 55, 511, 512, 521 ,52
2...Fuel valve.

Claims (1)

[Claims] 1. A fuel injection system for a diesel engine having a plurality of independent fuel valves or one composite fuel valve composed of a plurality of fuel valves per cylinder and one jerk-type fuel pump, the fuel pump as described above. A distributor is provided downstream of the common injection pipe connected to the common injection pipe, and an injection pipe system is formed in which the plurality of fuel valves are divided into two groups and connected to each other downstream of each branch injection pipe divided into two by the distributor. In the low speed or low load range of the engine, the two fuel valve groups alternately communicate with the fuel pump every other revolution of the fuel camshaft, and in the high speed range of the engine, all the fuel valves always communicate with the fuel pump. A fuel injection device for a diesel engine, characterized in that it is configured to communicate with a pump.