JPH0224944Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a multi-stage valve opening pressure nozzle for a diesel engine.

[Prior art]

Conventional combustion in diesel engines has a higher compression ratio than in gasoline engines, and since compression ignition is used, the combustion pressure is higher, which increases noise and vibration during combustion.

Conventionally, in order to reduce noise and vibration during combustion, for example, as disclosed in Japanese Utility Model Application Publication No. 52-53224, an attempt was made to reduce the maximum combustion pressure, maximum pressure rise rate, and combustion temperature. A fuel injection valve has been proposed in which fuel injection performed in a cycle is divided into two stages.

However, in the case of such conventional multi-stage fuel injection valves, only the number of stages is required to change the spring that presses the needle valve, and since the springs with different spring constants are arranged in series, the shape is large. As the valve opening pressure increases, the structure becomes more complex, the number of parts increases, and the adjustment of valve opening pressure, etc. becomes extremely complicated.

Furthermore, Japanese Patent Application Laid-Open No. 58-27878 discloses a needle valve having a plurality of pressure receiving surfaces, and Japanese Patent Application Publication No. 58-59365 discloses an injection valve that connects a relief passage by moving the needle valve during low-load operation. JP-A-54-47028 discloses two coaxial needle valves and two parallel needle valves, and JP-A-57-51947 describes an injection nozzle with a fuel relief groove in the valve member. Although disclosed, it does not in any way eliminate the above-mentioned drawbacks.

[Purpose of invention]

This idea was devised by focusing on the conventional problems, and its purpose is to create a simple structure with a reduced number of parts, and to easily adjust valve opening pressure etc. with minimal settings. The present invention provides a multi-stage valve-opening pressure nozzle that can perform the following steps.

[Structure of the idea]

In order to achieve the above object, this invention divides the nozzle body into a first pressure chamber that communicates with the injection port and the fuel supply hole, and a plurality of pressure chambers that communicate with the relief passage through communication holes. A needle valve having a plurality of pressure receiving surfaces facing each of the pressure chambers is provided so as to force the nozzle port into a closed state, and the needle valve closes a communication hole with the plurality of pressure receiving surfaces and opens a relief oil passage. Low pressure lift amount status,
Further, the present invention is characterized in that the single pressure receiving surface facing the first pressure chamber is configured to move beyond the low pressure lift amount state and into the full lift amount state.

〔Example〕

Embodiments of this invention will be described below based on the accompanying drawings.

FIG. 1 shows a cross-sectional view of a hole-type fuel injection nozzle in which this invention has been implemented, in which 1 is a nozzle body body equipped with a nozzle 2 at the tip, 3 is a nozzle holder, and inside the nozzle body body 1 is a pressure chamber. 4
is formed in multiple stages.

The pressure chamber 4 is divided into a first pressure chamber 4a and a second pressure chamber 4b through a communication hole 5, and the first pressure chamber 4a has a fuel supply hole 6 through which oil is supplied from a fuel injection pump (not shown). has been established.

Inside the first pressure chamber 4a and the second pressure chamber 4b, a nozzle 2 is always connected via a spring (not shown).
A multistage needle valve 7 biased toward the side is slidably housed inside.

This needle valve 7 is composed of a first sliding body 7a and a second sliding body 7b, which are connected via a rod 8.

The first sliding body 7a has a cylindrical sliding surface 9 in the center that can be fitted into the communication hole 5, and has an axial line at its tip with respect to the fuel pressure supplied to the first pressure chamber 4a. Tapered pressure receiving surface 1 that acts in the direction
0 is formed.

Further, a tapered surface 11 for setting a low-pressure lift amount h is formed at the rear end of the first sliding body 7a, and a second sliding body 7b is connected to the end surface of this tapered surface 11 via the rod 8. .

A tapered pressure receiving surface 12 is also formed at the tip of the second sliding body 7b, and a push rod 14 is connected to the rear end of the second sliding body 7b via a rod 13.
are connected.

Reference numeral 15 indicates a pressure oil relief passage connecting the second pressure chamber 4b and the passage 16 through which the push rod 14 moves up and down, and H indicates a pressure oil relief passage formed between the lower end surface of the nozzle holder 3 and the upper surface of the second sliding body 7b. This shows the total lift amount H of the needle valve body 7.

Next, the operation of the multi-stage valve opening nozzle constructed as described above will be explained.

First, during low speed and low load, the first pressure chamber 4a is supplied from the fuel injection pump (not shown) through the fuel supply hole 6.
When fuel is discharged into the second pressure chamber 4b, this fuel pressure is applied to the pressure receiving surface 10 of the first sliding body 7a and the second pressure chamber 4b.
Simultaneously acting on the pressure receiving surface 12 of the sliding body 7b, the needle valve 7 is raised by a low pressure lift amount h as shown in FIG. 2, but this rise causes the first pressure chamber 4a and the second pressure chamber 4b to At the same time as the dividing communication hole 5 is closed, the pressure oil relief passage 15 is opened and the pressure receiving surface 12 becomes inactive, so that at the upper limit position of the low pressure lift amount h, there is a single pressure receiving surface facing the first pressure chamber 4a. There will be only 10. While the needle valve 7 is moving up and down during this low pressure lift amount h, a relatively small amount of fuel is injected into the combustion chamber (not shown) from the injection port 2 at a low valve opening pressure. .

Next, when the engine is running at high speed and under high load, more fuel is injected from the fuel injection pump, and as a result, when the needle valve 7 rises by more than the low pressure lift amount h against the elastic force of a spring (not shown), the first slide When the moving body 7a closes the communication hole 5, no fuel is introduced into the second pressure chamber 4b, and no fuel pressure acts on the pressure receiving surface 12 of the second sliding body 7b. At the same time, the second pressure chamber 4
When the pressure oil relief passage 15 opens, the fuel accumulated in the nozzle holder 3 is discharged into the passage 16 on the nozzle holder 3 side, on which the push rod 14 slides. Thereafter, only the pressure receiving surface 10 of the first sliding body 7a receives the fuel pressure, and the first sliding body 7a rises against the elastic force of a spring (not shown) until it reaches the total lift amount H. That is, at high speeds and high loads, between the low pressure lift amount h and the total lift amount H, the needle valve 7 is raised and lowered only by the single pressure receiving surface 10 facing the first pressure chamber 4a, and fuel injection is performed by high valve opening pressure. will be carried out.

As described above, this needle valve has a simple structure that only biases the needle valve 7 to close the nozzle 2 provided in the first pressure chamber 4a without using a large number of springs. 7
is moved to a low-pressure lift amount h state until the communication hole 5 is closed by the first pressure chamber 4a and the multiple stages of pressure receiving surfaces 10 and 12 facing the multiple stages of pressure chambers,
In this low pressure lift amount h state, the communication hole 5 is closed and the relief passage 15 is opened to open the second pressure chamber 4b.
Since the pressure receiving surface 12 facing the first pressure chamber of the needle valve 7 is in an inactive state, the high pressure state is maintained by only the single pressure receiving surface 10 facing the first pressure chamber of the needle valve 7 from the low pressure lift amount h state to the total lift amount H state. Move with.

In this way, the pressure receiving surface of the needle valve 7 is operated by the multiple stages of pressure receiving surfaces 10 and 12 simultaneously until the low pressure lift amount h state is reached, and after the low pressure lift amount h state is reached and the total lift amount H state is reached. By changing only the pressure receiving surface 10 facing the first pressure chamber 4a to act independently, a small amount of fuel can be injected within the low pressure lift amount h at low speeds and low loads, and at high speeds and low loads.
At high loads, fuel corresponding to the total lift amount H is injected, so noise and vibration, especially at low loads, can be sufficiently reduced compared to conventional systems, and the fuel consumption rate can also be improved.

Further, FIG. 3 shows a second embodiment of this invention.While the first embodiment described above changes the valve opening pressure in two steps, this embodiment changes the valve opening pressure in four steps. This is what I did.

That is, in the case of this embodiment, a first pressure chamber 4a, a second pressure chamber 4b, and a third pressure chamber 4c are defined in stages through the communication hole 5 inside the nozzle body main body 1. Moreover, this first pressure chamber 4a and the second pressure chamber 4a
Projections X1, X2, and X3 for stoppers are formed in the partition between the pressure chamber 4b and the third pressure chamber 4c. Three sliding bodies 7a, 7 are connected through rods 8 in the pressure chambers 4a, 4b, 4c.
A needle valve 7 in which parts b and 7c are integrally formed is slidably installed inside.

With this configuration, high speeds can be achieved even at low speeds and low loads. It is possible to change the valve opening pressure in four stages while reaching a high load.

Furthermore, by increasing the number of pressure chambers and sliding bodies, it is also possible to change the valve opening pressure in a stepwise manner.

Regarding other configurations and effects,
Since it is similar to the first embodiment described above, the same reference numerals are given and the explanation will be omitted.

[Effect of idea]

As mentioned above, this invention has a simple structure in which the needle valve is biased to close the nozzle provided in the first pressure chamber, without using a large number of springs as in the conventional method. , this needle valve is moved to a low pressure lift state until the communication hole is closed and the relief passage is opened by the first pressure chamber and the multiple stages of pressure receiving surfaces provided facing the multiple stages of pressure chambers. Fuel can be injected using valve opening pressure. Moreover, in the low-pressure lift state, the communication hole is closed, the relief passage is opened, and the pressure-receiving surface facing the multiple pressure chambers becomes inactive.
The needle valve is moved by only a single pressure-receiving surface facing the first pressure chamber, and fuel can be injected at a high valve opening pressure.

Therefore, without using a large number of springs as in the past, by changing the pressure receiving surface provided on the needle valve according to the low pressure state and high pressure state, the needle valve can be adjusted to the low pressure lift state and this state. Since it can move between the low-pressure lift state and the full lift state, the number of parts does not increase, and the overall configuration is compact.Furthermore, the valve opening pressure adjustment is not as complicated as in the past, and can be adjusted to the minimum. This can be easily done with limited settings.

Furthermore, the multi-stage valve opening pressure nozzle according to the present invention has the effect of sufficiently reducing vibration and noise, which is the purpose of the multi-stage valve opening pressure nozzle, and also improving fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multi-stage valve-opening pressure nozzle embodying this invention, FIG. 2 is a sectional view showing the operating state of FIG. 1, and FIG. 3 is a sectional view showing another embodiment. 1... Nozzle body main body, 7... Needle valve, 7a, 7b... Sliding body, 10, 12... Pressure receiving surface.

Claims (1)

[Scope of utility model registration request] A first pressure chamber communicating with the nozzle and the fuel supply hole and a plurality of pressure chambers communicating with the relief passage are defined in the nozzle body main body via communication holes, and a plurality of stages facing each pressure chamber are formed. A needle valve having a pressure-receiving surface is provided to bias the nozzle in a closed state, and the needle valve is placed in a low-pressure lift state in which the plurality of pressure-receiving surfaces close the communication hole and open a relief oil passage, and further in a first pressure chamber. A multi-stage valve-opening pressure nozzle configured to move beyond a low-pressure lift state to a full-lift state with a single pressure-receiving surface facing the air.