JPS6030471A - Fuel injector - Google Patents

Abstract

PURPOSE:To reduce fuel consumption and reduce the amount of smoke in exhaust gas by increasing the injection pressure on starting injection and at the end of injection. CONSTITUTION:The fuel in an accumulator 25 is supplied into a nozzle 10 by opening a valve 28 on exit side when the pressure is reduced by a fuel injection pump. Therefore, the injection pressure particularly on starting injection can be increased by the accumulator 25, and the injection rate, namely the starting-up characteristic of the variation of the injection amount with respect to time can be improved. Since both of the valve opening pressure and the valve closing pressure are increased by installing the accumultor 25, the injection amount forms a sharp curve, and the fuel cut-off can be improved, and fuel consumption can be improved, and the amount of smoke in exhaust gas can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device, and more particularly to a fuel injection device that injects pressurized fuel in the form of a mist through an injection nozzle.

In a direct injection type diesel engine, a fuel injection device is provided in the cylinder head of the engine, and fuel supplied from a fuel injection pump is atomized and injected by the fuel injection device. The above-mentioned injection device is composed of a holder and a nozzle attached to the tip of the holder and having a spout. A nozzle needle is arranged inside the nozzle, and this nozzle needle is pressed by a spring inside the holder.

Therefore, when the nozzle needle moves upward against the spring due to the injection pressure applied to the fuel via the fuel injection pump, the nozzle is opened and the fuel is injected in the form of a mist. .

According to such a conventional fuel injection device, the pressure when the nozzle needle hears the nozzle and the pressure when it closes are:
The injection pressure is determined by the balance between the injection pressure and the spring installed in the nozzle holder, and the injection pressure is determined by the camshaft V.
It is determined by the discharge pressure of the plunger pump driven by F1~.

That is, since the fuel injection pump uses a cam to push up the plunger to pressurize the fuel, it has the disadvantage that the pressure of the fuel is low when starting and ending the injection. Therefore, especially at the start of injection nozzle #1 and the end of injection #A, where the pressure is low, incomplete combustion is likely to occur, resulting in poor fuel efficiency and a large amount of smoke in the exhaust gas.

The present invention was made in view of these problems, and aims to reduce fuel consumption and reduce the amount of smoke in the exhaust gas by increasing the injection pressure at the start and end of injection. The purpose of this invention is to provide a fuel injection device.

The present invention will be explained below with reference to an illustrated embodiment.

FIG. 1 shows a cross section of a diesel engine equipped with a fuel injection device 1 according to this embodiment, and a piston 3 is slidably disposed within a cylinder 2 of the engine. A combustion hole 4 consisting of a recess is formed at the top of the piston 3. The upper part of the cylinder 2 is closed by a cylinder head 5. The cylinder head 5 is formed with an intake boat 8 and an exhaust boat 9 each having an intake valve 6 and an exhaust valve 7. Further, the above-mentioned fuel injection device 1 is attached to this cylinder head 5. This fuel injection device 1 is composed of a nozzle boulder 11 having a nozzle 10 at its tip. It is configured to inject atomized fuel into the combustion chamber 4 of the piston 3.

Next, this fuel injection device 1 will be explained in more detail with reference to FIG. 2. A nozzle 10 is provided with a plurality of injection ports 12 at its lower end, and is connected to a nozzle holder 11 by a connecting sleeve 13. . A nozzle needle 14 is disposed within the nozzle 10 so as to be slidable in the axial direction.

This needle 14 controls opening and closing of the nozzle 12. The nozzle needle 14 is in contact with the lower end of the press rod 15, and the press rod 15 is in contact with the boulder 11.
It is pressed by a spring 17 in a spring 16 formed therein. The upper end of the spring 17 is received by a spring receiver 18. Note that the gap between the outer circumference of the spring receiver 18 and the holder 11 is very small to prevent fuel leakage. Note that even if an oil seal is provided between the spring receiver 18 and the boulder 11, it is not possible. The upper end of this spring holder (]18 is attached to the adjusting screw 1.
It is pressed by 9. Furthermore, Boulder 1
A cap 20 is attached to the upper end of the cover 1 so that it can be removed.

Furthermore, in this fuel injection device 1, the nozzle holder 1
A fuel supply passage 21 is formed in communication with the nozzle 1 and the nozzle 10 . A communication passage 22 is formed in the holder 11 to communicate the fuel supply passage 21 with the spring 16. The upper end side of the fuel supply path 21 is connected to the connector 23
It is connected to the fuel supply path 24 of. This supply path 27I is connected to the recess 25 of the connector 23.

This recess 25 constitutes an accumulator. A spring 26 is housed in the accumulator 25 and presses the check valve 27. The check valve 27 is attached to the inlet side of the accumulator 25, and a second check valve 28 is integrally connected to the check valve 27.
It is designed to be installed on the outlet side of the The connector 23 constituting the accumulator 25 is connected to a fuel supply pipe 29, through which the injection device 1 is connected to a fuel injection pump (not shown).

In the above configuration, the intake valve 6 not shown in FIG.
When opened, intake air is introduced into the cylinder 2 through the intake bows 1-8. As the piston 3 moves toward the top dead center side, this intake air is compressed and its temperature rises. In this state, atomized fuel is injected from the nozzle 12 of the nozzle 10 of the fuel injection device 1, and this fuel mixes with the intake air to cause a combustion explosion in the combustion chamber 4. Accordingly, the piston 3 receives the pressure j pushing downward and moves toward the bottom dead center side. This movement of the piston 3 is converted into rotational motion by a crankshaft (not shown), which is taken out as an output from the engine.

As shown in FIG. 2, the fuel injection device 1 that performs such fuel injection includes a fuel supply pipe 29 and a connector 23.
Fuel is supplied from the fuel injection pump via the fuel injection pump at a predetermined timing. The fuel supplied from the fuel injection pump is once accumulated in pressure by an accumulator 25 formed in the connector 23, and then is transferred to the fuel supply path 25.
and 21 to be supplied to the nozzle 10. That is, when the pressure of the plancit pump of the fuel injection pump corresponding to this injection device 1 increases, this pressure pushes the check valve 27 on the inlet side, and opens the check valve 27 against the spring 26. , the second check valve 28 on the outlet side is closed. Therefore, the fuel supplied from the fuel injection pump is once transferred to the accumulator 25.
At the same time, the pressure inside this accumulator 25 increases.

Next, when the discharge pressure of the plunger pump drops to a certain extent as the cam of the fuel injection pump rotates, the first check valve 27 is closed by the spring 26, and in synchronization with this, the first check valve 27 is closed by the spring 26. The second check valve 28 is closed. Therefore, the fuel stored in the accumulator 25 is guided to the nozzle 10 through the fuel supply channels 24 and 21, and the pressure of this fuel pushes the nozzle needle 14 up against the spring 17. , the fuel is injected into the cylinder 2 by listening to the nozzle 12.

Furthermore, in this fuel injection device 1, the injection pressure of the fuel 1 is applied to the spring seedling 16 via the fuel supply path 21 and the communication path 22, and for this purpose the nozzle needle 14 is It receives not only the pressure of the spring 17 but also the @pressure of the fuel. Therefore, according to such a fuel injection device 1, it becomes possible to inject fuel at an injection rate different from the conventional one. In other words, the injection pressure applied to the spring 16 is the same as that of the accumulator 25.
Since the second check valve 28 is applied only when the fuel is delivered, pressure is not applied to the nozzle needle 14 all the time, but only during injection. become.

Therefore, by providing the communication passage 22, the start of injection is delayed, the end of injection is brought forward, and the pressure at the start and end of injection is increased.

According to the fuel injection device 1 of this embodiment, the fuel pressurized by the fuel injection pump is temporarily accumulated in the accumulator 25, and when the pressure by the fuel injection pump decreases, the pressure in the accumulator 25 is Fuel is supplied to the nozzle 10 via a valve 28 on the outlet side. Therefore, this accumulator 25 makes it possible to increase the injection pressure particularly when starting injection, and it becomes possible to improve the injection rate, that is, the rising characteristics of the change in injection amount with respect to time. Also this accumulator 2
By setting step 5, both the valve-closing pressure and the valve-closing pressure increase, resulting in a sharp curve for the injection amount, which improves fuel depletion, improves fuel efficiency, and reduces exhaust gas emissions. It is possible to reduce the amount of smoke emitted by

Further, in this fuel injection device 1, a communication passage 22 is provided to supply fuel into the spring chamber 10, and apply fuel injection pressure to the nozzle needle 14 from the rear side. Therefore, pressure is applied to the nozzle needle 14 only at the injection timing, and this also causes the valve-closing pressure and the valve-closing pressure to increase. Therefore, when this action is combined with the action of the accumulator 25, the injection characteristics can be roughly improved, and fuel efficiency and smoke in the exhaust gas can be improved.

As described above, the present invention provides an accumulator in the supply path for supplying fuel to the injection nozzle, and connects a pair of check valves connected to each other so as to move integrally to the inlet side and the outlet side of the accumulator. It is related to the fuel injection (HH position) where J: with the sea urchin spring (= I force) and the check valve on the inlet side is closed. Therefore, in the present invention, J: It is possible to increase the injection pressure, especially at the beginning of injection.Therefore, the injection characteristics can be improved to better ones, improving fuel efficiency and reducing exhaust emissions. Smoke in the gas can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a main part of an engine equipped with a fuel injection device according to an embodiment of the present invention, and FIG. 2 is an enlarged longitudinal sectional view of the fuel injection device of this engine. In addition, in the symbols used in the drawings, 1...Fuel injection device 10...Nozzle 21...Fuel supply path 23...Connector 25...Accumulator (recess) 26...Spring 27...No. No. 1 check valve (inlet side) 28...Second check valve (outlet side). Applicant 1] No Jidosha Kogyo Co., Ltd.

Claims (1)

[Claims] In a device in which pressurized fuel is atomized and injected by an injection nozzle, an accumulator is provided in a supply path for supplying fuel to the injection nozzle, and the accumulators are connected to each other so as to move integrally. A fuel injection device characterized in that a pair of check valves are attached to the inlet side and the outlet side of the Akicomulator, respectively, and the check valve on the inlet side is biased by a spring to close.