JPS6155362A - Fuel injection nozzle - Google Patents

Abstract

PURPOSE:To reduce production of noise and NOX by pilot injection and main injection proceded by the pilot injection through control of a fuel injection pressure related to the coefficient of fuel injection. CONSTITUTION:During the initial stage of introduction of an injection pressure in which driving of a second piston 18 is started, a moving force is exerted on a first piston 8 in a pressure chamber 9 to lift a needle valve 10, and a fuel injection nozzle 6 is opened to inject fuel oil therethrough. After fuel injection, the second piston 18 is driven by a given stroke, and when it is stopped by a spacer 15, an internal pressure in the pressure chamber 90 is increased again. Driving of the second piston 18 causes the occurrence of a timing lag to a previous transfer pressure. When a moving force against a spring 21, compressed at a given valve opening pressure, is compressed by the second piston to exert it on the first piston 8, the needle valve 10 is lifted again to inject the fuel.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel injection nozzle employed in a diesel search engine, and in particular controls the penalty injection pressure involved in the fuel injection 01 rate to control the pilot injection and the fuel injection nozzle. Next, the main injection q dimension can reduce noise, NOx, etc.[Related to injection nozzles].

[Prior art] In general, the combustion process in a diesel engine involves an ignition delay W.
It consists of an initial combustion period in which the fuel injected into the fuel mixture becomes a premix and burns all at once, followed by a diffusion combustion period.

[Problems to be solved by the invention] By the way, if the combustion rate in the initial combustion period (fuel injection rate in the initial combustion period) is high, the noise and vibration of the engine will be large, and the amount of NOx emission will increase. This was particularly noticeable in direct injection diesel engines with high fuel injection rates.

In other words, when the fuel injection rate is high and the energy state inside the combustion chamber is high during the initial combustion period, combustion proceeds rapidly (explosively) at the same time as a large number of flame kernels are generated, increasing the rate of pressure rise in the cylinder chamber and generating large pressure waves. This generates rA sound and vibration, and NOx is generated in the 5th mountain due to the rapid temperature rise in the early stages of combustion.

Here, as a measure to solve the above problem, controlling the fuel injection rate may be considered, for example, distributed fuel +17I Q'
A piston is provided in the 1α pressure range of the J pump, or a spill passage d is branched from the oil supply passage of the fuel injection valve body a shown in Fig. 4 and opened and closed by the lift of the auxiliary valve C. (Japanese Unexamined Patent Publication No. 50-63327), etc., has been devised to prevent part of the fuel from escaping.

However, these proposals are considered to be unable to achieve sufficient reductions in noise and NOx because the injection rates become uneven in each cylinder due to variations in the opening pressure of the injection nozzles of the plurality of cylinders and changes in the springs over time.

[Objective of the Invention] The present invention was devised in view of the above-mentioned problems, and its purpose is to control pilot injection and (Continued) To provide a fuel injection nozzle that achieves reduction of noise, NOx, etc. through main injection.

[Summary of the Invention 1 The present invention provides that the fuel injection pressure supplied from the pressure supply system is applied to a first piston for lifting a needle valve that opens a fuel injection hole by applying the fuel injection pressure supplied from the pressure supply system. A second piston is provided which is moved by a predetermined stroke when the pressure is applied, and a spring is provided between these pistons to return the pistons that have moved while adjusting the valve opening pressure. The first piston is driven to perform fuel injection 01 (pilot injection), and the second piston is driven by a predetermined stroke to increase the pressure on the first piston side to a predetermined valve opening pressure. The gist of this invention is that after delaying the first piston, the first piston is driven to perform further fuel injection (main injection).

[Example] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a fuel injection nozzle used in a direct injection diesel engine. This fuel injection nozzle mainly consists of a nozzle body 1 formed in the shape of a sleeve and coupling parts 2 provided at both ends of the nozzle body 1 in the axial direction.
and a nozzle part 3. The nozzle part 3 is fixed to the nozzle body 1 via a ring-shaped spacer 4, and the coupling part 2 is directly fixed to the nozzle body 1 by a retaining nut 5. is done.Covering part 2
The fuel 11 is placed in the narrow diameter portion 2a extending along the axial direction.
14 is connected to a fuel oil pipe (not shown) forming part of the pressure and supply system for supplying the injection pressure, and the other nozzle part 3
A fuel injection hole 6 is formed at the tip of a narrow diameter portion extending along the axial direction. And this. A series of fuel oil passages 7 are formed between the fuel injection holes 6 and the coupling part 2, which form part of a pressure supply system that introduces fuel oil supplied from the fuel oil pipe and transmits and supplies the pressure. be done.

By the way, a first piston 8 is provided at the end of the nozzle portion 3 opposite to the fuel nozzle hole 6 so as to be able to reciprocate in the axial direction. A pressure receiving part 8a that receives the fuel injection pressure that gives A needle valve 10 is installed on the first piston 8 and extends from the pressure receiving part 8a toward the fuel injection holes 6, and is configured to be able to be lifted freely in order to open and close these fuel injection holes 6. .

Furthermore, the first piston 8 has an end surface 8b opposite to the pressure receiving part 8a.
is opposed to the subena 4. This spacer 4 has a function of regulating the moving first piston 8 by a considerable stroke amount while relieving the needle valve 10. Further, the spacer 4 is attached to the first piston 8 from its end surface 8b.
A bushing rod 11 is provided through the u.

On the other hand, a branch passage 12 is formed in the coupling portion 2, which branches off from the fuel oil passage 7 extending to the fuel nozzle hole 6 and passes through the end of the nozzle body 1 opposite to the first piston 8.

This branch path 12 forms part of the pressure supply system,
The same fuel injection pressure as that on the fuel oil passage 7 side is introduced. A cylinder chamber 13 is formed at one end of the nozzle body 1 to which this branch passage 12 is connected, and a shim 14 and a ring-shaped spacer 15 are sequentially placed inside this cylinder chamber 13.

A sleeve 16 is attached and fixed with lock nuts 1 to 17 having through holes 17a. In the sleeve 16 there is a first
A second piston 18 is provided so as to be reciprocally movable relative to the piston 8 in its movement direction. This second piston 18 faces the pressure receiving part 1 through the branch passage 12 and faces the through hole 17a through which the fuel injection pressure that gives the piston a moving force is introduced.
8a is formed. In particular, the pressure receiving area A2 of the pressure receiving part 18a of the second piston 18 is larger than that of the pressure receiving part 8 of the first piston 8.
The pressure receiving portion mA+ of a is set as follows, and the second piston 18 is configured to receive a force greater than that of the first piston 8.

Here, DI: Outer diameter of the first piston d1: Outer diameter of the needle valve D2: Outer diameter of the second piston Also, the end face 18b of the second piston 18 on the opposite side to the pressure receiving part 18a faces the spacer 15. second piston 18
is stopped by this spacer 15 at a predetermined movement stroke.

Furthermore, a bushing rod 19 is installed in the second piston 18 with a spacer 15 passed through L1 from its end surface 18b.

Furthermore, a spring seat 2 is provided between these opposed pistons 8 and 18, specifically bushing rods 11 and 19.
A spring 21 serving as an elastic means is provided through the spring 21.

This spring 21 is set at a set force M2 that is compressed by a relatively smaller pressure than the set valve opening pressure when the fuel injection pressure is not applied, and when the fuel injection pressure is applied, the second piston 18 is moved to a predetermined position. The configuration is such that when the valve moves in a stroke and is stopped by the spacer 15, the set force M1 becomes a set force M1 which is compressed and further compressed at a set valve opening pressure.

Note that 22 is a return pipe for returning fuel oil leaked around the spring 21 via the pistons 8 and 18 to a tank or the like, and is fixed to the nozzle body 1.

Next, we will discuss the effect.

At the beginning of fuel injection, fuel oil is supplied at a considerable fuel injection pressure via the fuel injection bomb pressure supply system. The pressure introduced from the coupling portion 2 is transmitted to the fuel oil passage 7, branch passage 12, etc. of the nozzle body 1, etc. The pressure introduced here acts on the first piston 8 but also on the second piston 18, and the second piston generates a large force due to the setting of the small pressure receiving area A+ and △2. 18 is driven while sequentially compressing the spring 21.

As shown in FIG. 2, at the beginning of the introduction of the fuel injection pressure when the drive of the second piston 18 starts 17i7, the pressure chamber 9 has no pressure due to the inertial effect of the introduced pressure. A moving force acting against the spring 21 compressed by a force M2 smaller than the normal valve opening pressure acts on the piston 8 of No. 1, the needle valve 10 is lifted, the fuel injection hole 6 is opened, and fuel oil is injected. (Pie [1st jet 01, part A in Figure 2).

When fuel is injected, the pressure inside the pressure air 9 decreases,
In addition, the pressure of 14 sexual effects tJ chrysanthemum height is so high that the needle valve 10
is returned by the spring 21 to close the fuel injection hole 6 and stop the injection of fuel oil (section B in FIG. 2).

When the piston 18 of the cylinder 2 is driven a predetermined stroke and stopped by the spacer 15, the internal pressure of the pressure air 9 rises again. On the other hand, a time lag T is given.

A moving force F resists the spring 21 which is compressed by the second piston 18 and compressed at a predetermined valve opening pressure.
When SIhi acts on the first piston 8, the needle valve 10 is lifted again and fuel oil is injected (main injection,
Figure 2 Part C>.

Finally, when the pressure feeding of fuel oil from the fuel injection pump is completed, the pressure in the pressure supply system decreases, and the piston 8.18 is returned by the spring 21, completing one cycle of fuel injection (the second drawing section ).

By the way, in the present invention, as shown in FIG. 3, at the beginning of the introduction of the fuel injection pressure, tf of the pressure of j5 LJ! The pilot injection is performed at a low injection rate due to the sexual effect, and then the second piston 18 is driven for a predetermined stroke.
This increases the time lag in the injection timing, allowing the timing of main injection to be delayed, thereby suppressing the formation of pre-humidified air during the ignition delay period and achieving warm initial combustion compared to conventional methods. (Indicated by Q in the figure.Also, Δ,
Sections B, C, and D correspond to sections A, B, C, and 0 in FIG. 2, respectively).

Therefore, it is possible to prevent sudden increases in cylinder pressure and temperature.
It is possible to reduce engine vibration Ej+-noise and generation of NOx, etc.

It should be noted that there is a concern that lowering the fuel injection rate may worsen output and smoke during high-speed operation, but in the present invention, pressure is introduced as the transition to high-speed operation occurs.
The inertial effect increases and the pilot injection and main injection are no longer separated, resulting in injection almost the same as a normal nozzle.

In addition, in the present invention, the first piston 8 and the second piston
Since the piston 18 is made to work once with one spring 21, the operating ratio can be kept constant even if deterioration occurs over time, compared to the case where each is controlled by the spring on the Z side, and the injection timing can be kept constant. fluctuations can be suppressed as much as possible.

The present invention can also be applied to sub-combustion chamber type diesel engines.

[Effects of the Invention] In conclusion, according to the present invention, the following disadvantageous effects are achieved.

(1) a second piston that delays transmission of fuel injection pressure to the first piston that drives the needle valve;
Due to the inertial effect of the pressure at the beginning of the introduction of fuel injection pressure, pilot injection and main injection can be performed in one cycle, suppressing sudden increases in cylinder pressure and temperature, and reducing noise and vibration between stages. It is possible to reduce NOx, etc.

(2) Since the first piston and the second piston are actuated by a single spring, the operating ratio can be kept constant and reliability can be improved.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing a preferred embodiment of the present invention;
The figure is a graph showing the relationship between the crank rotation angle and the pressure transmitted to the first piston, and FIG. 3 is a graph showing the relationship between the crank rotation angle, the cylinder pressure, and the fuel injection rate.
FIG. 4 is a side sectional view showing a conventional example. In the figure, 6 is a fuel injection hole, 7 and 12 are fuel oil passages and branch passages that constitute a pressure supply system, 8 is a first piston, 10 is a needle valve, 18 is a second piston, and 21 is an elastic means. This is the spring shown as an example. Patent Applicant: Isuzu Motors Co., Ltd. Representative Patent Attorney Nobuo Kinutani Figure 3 2 Points Franz Kaiyun Moehiki □

Claims (1)

[Claims] a pressure supply system for supplying fuel injection pressure; a first piston that is driven by the pressure supplied from the pressure supply system and lifts a needle valve that opens a fuel injection hole;
a second piston driven by a predetermined stroke with the pressure supplied from the pressure supply system to delay pressure transmission to the first piston; and a second piston provided between these pistons to spring and return them. A fuel injection nozzle characterized in that it is equipped with an explosive means.