JPS6034776Y2 - Injection valve device for pre-chamber diesel engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an injection valve device for a diesel engine having a pre-chamber.

In this main engine, for example, as shown in FIG. 1, a mouthpiece 2 is fitted onto a cylinder head 1 to form a vortex chamber 3 as an auxiliary chamber, and a main chamber is recessed in the upper surface of a piston 4. 5 and the swirl chamber 3 are communicated through a communication hole 6 formed in the base 2.

Furthermore, by arranging the communication hole 6 along the tangential direction of the swirl chamber 3, the air pushed into the swirl chamber 3 from the communication hole 6 during the compression stroke swirls inside the swirl chamber 3, causing a so-called vortex flow. I have to.

The swirl chamber 3 is provided with an injection valve 7 that injects fuel forward in the swirl direction, and a preheating plug 8 is installed on the upstream side of the injection valve 7 to improve startability. .

9 is the cylinder block, A is the arrow indicating the direction of the vortex, B
is the injected fuel (refer to pages 26 to 32 of the Technical Manual for Diesel Engines published by Nissan Motor Co., Ltd., June 1932).

However, when the fuel is injected in a direction relative to the vortex, the relative velocity between the injected fuel and the air is small, so heat transfer from the air to the fuel is poor, resulting in ignition delay. becomes longer and the combustion noise becomes higher.

In addition, there was a drawback that starting performance was poor because not only little fuel reached the preheating plug 8, but also little fuel blown through the communication hole 6 into the main chamber 5 during cranking.

The present invention has been developed in view of the above, and includes an injection valve having a main injection that is performed in the direction of the vortex flow and a sub-injection hole that injects fuel toward the preheating plug in a direction that is opposed to the vortex flow. .

As a result, the fuel injected from the auxiliary nozzle comes into contact with the heated air flowing in the opposite direction at a high relative speed, and after efficiently transferring heat and increasing its temperature, it collides with the red-hot part of the preheating plug and is further heated. Atomization or vaporization is promoted.

Sufficiently vaporized fuel is sufficiently mixed with air due to the turbulence of the airflow generated near the preheating plug, resulting in improved ignitability, and the ignited fuel assists in igniting the main injected fuel.

Furthermore, since the fuel injected from the sub-nozzle hole is easily blown into the main chamber through the communication hole, the fuel is also supplied to the main chamber, which has a higher temperature and pressure than the swirl chamber, and improves ignition performance.

These comprehensive effects shorten the ignition delay, improve startability, and reduce combustion noise.

The present invention will be described below with reference to the embodiments shown in FIGS. 2 to 5.

In the figure, a main chamber 12 is recessed into the upper surface of a piston 11 that is fitted and pushed into a cylinder block 10, and a mouthpiece 14 is press-fitted and fixed to a cylinder head 13 that is tightened and fixed to the cylinder block 10. A vortex chamber 15 is formed as a sub-chamber in the form of a sphere or a spheroid.

The main chamber 12 and the swirl chamber 15 are communicated with each other by forming a communication hole 16 in the base 14 along the tangential direction of the swirl chamber 15, as in the conventional case.

Therefore, during the compression stroke, air in the main chamber 12 flows through the communication hole 1.
6 into the swirl chamber 15 to form a strong swirl A.

Further, a preheating plug 17 is provided in the swirl chamber 15, and an injection valve 18 is provided downstream of the preheating plug 17.

Here, the preheating plug 17 and the battery 19 are, for example, as shown in FIG. 2, the preheating contact 20a of the key switch 20,
Accelerator switch 21 that detects accelerator opening (load)
It is connected via a normally closed relay 22 controlled by .

The coil of the relay 22 is supplied with the output voltage of the voltage regulator 23 as a power source, and the accelerator switch 21 detects the load condition via the cam plate 24 linked to the accelerator pedal and stops idling. It is designed to be closed in a low load area including

A starter motor 26 is connected to the starting contact 20b of the key switch 20 via a starter relay 25.

The preheating contact 20a of the key switch 20 is activated when the key switch 20 is switched to the operating position and the starting position, and
When a preheating position is provided, it is also closed at this preheating position, and the starting contact 20b is closed only when the key switch 20 is switched to the starting position.

On the other hand, the injection valve 18 has a throttle portion 3 at the tip of a nozzle needle 29 which is held in pressure contact with a nozzle body 28 by a spring 27, as shown in FIGS. 3 and 4, for example.
0, and the main injection hole 3 whose opening degree of the throttle part is adjusted.
The nozzle is composed of a Vintokes type nozzle in which a sub-nozzle hole 32 is additionally drilled in a throttle nozzle equipped with a 1-inch throttle nozzle.

The injection direction of the main nozzle hole 31 is made to run in the direction of the vortex A, and the sub-nozzle hole 32 is made to go in a direction opposite to the vortex A so as to face the red-hot part of the preheating plug 17.

33 is a fuel inlet, 34 is a fuel passage, 35 is an overflow port, 3
A bolt 6 positions and fixes the injection valve 18 to the cylinder head 13.

In the above configuration, when the engine is stopped, the alternator is stopped, so the contacts of the relay 22 are kept closed regardless of the status of the accelerator switch 21.

Therefore, when the key switch 20 is switched to the preheating position or the operating position to start the engine, the preheating contact 20a is closed, current flows from the battery 19 to the preheating plug 17, and the preheating plug 17 becomes red hot.

After learning that the preheating plug 17 has become red hot via a heater signal or a pilot lamp (not shown), the key switch 20 is switched to the starting position.

Then, the starting contact 20 is closed while the preheating contact 20a is closed.
b is also closed, current is supplied to the starter motor 26 via the starter relay 25 while the preheating plug 17 remains energized, and the engine is cranked.

When the engine is cranked, a vortex is created in the vortex chamber 15 during the compression stroke, and fuel is fed into the fuel passage 34 from a fuel injection pump (not shown) through the fuel inlet 33 of the injection valve 18.

When the pressure within the fuel passage 34 increases, the nozzle needle 29 is lifted against the spring 27, and its tip seat section floats above the seat section of the nozzle body 28.

Then, since the sub-nozzle hole 32 is fully opened from the region where the lift amount of the nozzle needle 29 is small, during the rising period of the injection from the main nozzle hole 31, the flow flows from the nozzle hole 32 against the vortex A and reaches the red-hot part of the preheating plug 17. and fuel is pilot injected.

Therefore, the relative speed between the fuel injected from the sub-nozzle hole 32 and the air becomes extremely large, so that the heat in the vortex is efficiently transferred to the fuel, and the fuel with increased temperature is transferred to the preheating plug 17. It is further heated and vaporized by the collision with the red-hot part, and is sufficiently mixed with air due to the turbulence generated near the preheating plug 17, so that it ignites in an extremely short time.

This ignition facilitates ignition of the main injection injected from the main nozzle hole 31, and the overall ignition delay is significantly shortened.

Furthermore, since the opening degree of the main nozzle hole 31 increases rapidly when the lift amount of the nozzle needle 29 exceeds a predetermined value, the amount of fuel injected from the main nozzle hole 31 in parallel with the vortex flow is reduced by ignition. increases approximately in synchronization with the occurrence of

Furthermore, the fuel injected from the sub-nozzle hole 32 is transferred to the communication hole 1.
6 to the main room 12, the swirl chamber 15
Fuel is also supplied into the main chamber 12, which has a higher temperature and pressure than the main chamber 12.

Therefore, the ignition delay is shortened and the startability of the engine is improved.

Note that the amount of fuel injected from the main injection hole 31 in the direction of the vortex is set to be sufficiently larger than the amount of fuel injected from the sub-injection hole 32 in a direction opposite to the vortex.

FIG. 5 shows the relationship between the lift amount of the nozzle needle 29 and the nozzle opening area of the injection valve 18 as a whole.

Here, in order to improve the combustion efficiency, by injecting fuel in the direction of the vortex, the fuel along the wall surface of the vortex chamber 15 is brought into contact with the high-temperature air pushed in through the communication hole 16, and ignited. However, since only a small amount of fuel is injected from the sub-nozzle hole 32 against the vortex flow,
The influence of the sub-injection is not a practical problem at all; on the contrary, the effect of shortening the ignition delay due to the sub-injection is much greater.

Furthermore, after the engine has started, the key switch 20 is returned to the operating position, but since the preheating contact 20a continues to be closed even in this state, the relay 22 is activated by the action of the accelerator switch 21 in low load areas including idling. Closed.

For this reason, the red-hot portion of the preheating plug 17 is heated even in the above-mentioned region where the ignition combustibility deteriorates, so that the ignition delay is shortened and the noise is reduced.

In the embodiment, the preheating plug is operated even in a low load range including idling, but depending on the engine specifications or operating conditions, the preheating plug may be stopped while the engine is running.

Further, the sub-injection from the sub-nozzle hole 32 is not necessarily a pilot injection, but may be performed simultaneously with the main injection depending on the purpose.

As explained above, according to the present invention, in addition to the main nozzle hole that injects fuel in the direction of the vortex generated in the pre-chamber, there is also a sub-nozzle that injects fuel against the vortex and toward the preheating plug. Because it is equipped with nozzle holes, the relative velocity between the fuel injected from the sub-nozzle hole and the air increases, significantly improving the air-fuel mixture properties, and the preheating plug directly heats the fuel to promote its vaporization. do.

Sufficiently vaporized fuel is sufficiently mixed with air due to the turbulence of the airflow generated near the preheating plug, resulting in improved ignitability, and the ignited fuel assists in igniting the main injected fuel.

Furthermore, since the fuel injected from the sub-nozzle hole is easily blown into the main chamber through the communication hole, the fuel is also supplied to the main chamber, which has a higher temperature and pressure than the swirl chamber, and improves ignition performance.

These comprehensive effects shorten the ignition delay, reduce noise, and improve startability.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a combustion chamber showing a conventional example, Fig. 2 is a sectional view of a combustion chamber according to an embodiment of the present invention, Fig. 3 is a sectional view of an injection valve, and Fig. 4 is a sectional view of a combustion chamber according to an embodiment of the present invention. FIG. 5, which is a sectional view of the main part, is a diagram showing the relationship between the lift amount of the nozzle needle and the nozzle hole area by the same injection valve. 12...Main chamber, 15...Sub-chamber (vortex chamber), 16...Communication hole, 17...Preheating plug, 18...・Injection valve, 31... Main injection hole,
32... Sub-nozzle hole, A... Vortex flow.

Claims (1)

[Scope of utility model registration request] In a pre-chamber type diesel engine, a preheating plug and an injection valve are provided in a pre-chamber that communicates with the main chamber through a communication hole, and a vortex flow is created in the pre-chamber during the compression stroke. An injection valve for a pre-chamber type diesel engine, characterized in that the injection valve is provided with a main nozzle hole for injecting fuel into the pre-chamber, and a side hole for injecting fuel toward a preheating plug against the vortex flow in the pre-chamber. Valve device.