JPS63117163A - Fuel injection nozzle for diesel engine - Google Patents

Abstract

PURPOSE:To achieve a fuel injection characteristic suitable to the operating condition, by splitting a needle of a fuel injection nozzle into a projecting valve and an outer circumferential valve and providing a means for controlling the axial direction of the projecting valve. CONSTITUTION:A seat face 16 is provided in a nozzle body 1 and an outer circumferential valve 5 to be seated in said seat face 16 is inserted into a central hole section. Through-holes are made through the core section of the outer circumferential valve 5 and a pressure pin 6, and a projecting valve 9 is inserted into said through-hole. A solenoid drive control means 11 drives the projecting valve 9 according to the operating conditions of engine and controls the axial direction thereof. In such a manner, a fuel injection characteristic suitable to the operating condition can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in fuel injection nozzles for diesel engines.

[Prior Art] As is generally well known, in a diesel engine, fuel supplied from a fuel supply pump is pressurized by a fuel injection pump, and then forcefully delivered to a fuel injection nozzle. It is atomized by a nozzle and injected into the combustion chamber of the engine in the form of a mist. In a diesel engine equipped with such a fuel injection device, the optimal values for the amount of fuel to be injected into the combustion chamber of the engine and the amount of fuel injected per unit time (fuel injection rate) vary depending on the operating conditions. , as a fuel injection nozzle,
It has been desired to obtain injection characteristics suitable for all operating conditions.

However, in the conventional fuel injection nozzle of a diesel engine, as shown in FIG.
When the valve opening pressure determined by the spring load of the spring 53 that biases the valve 2 toward the valve closing side is exceeded, the needle 52 rises and fuel is injected. Needle 52 is maximum riff H.

As a result, most of the fuel is injected at the beginning of injection, making it impossible to obtain an appropriate injection timing and injection rate.
2 rises instantaneously, there is a problem in that the fuel pressure in the fuel injection nozzle temporarily decreases, resulting in poor spray conditions and causing engine combustion noise.

To solve the above problem, Japanese Patent Application Laid-Open No. 59-147862 makes it possible to extend the injection period without lowering the injection pressure by injecting fuel in two stages using a two-stage spring. We are proposing fuel injection valves for diesel engines. In this case, the first needle, which is biased with a relatively small spring force, first opens the valve and injects some fuel, and then the second needle, which is biased with a relatively high spring force, opens the valve and injects some fuel. The entire required amount of fuel is injected, but the lift amount of the needle is determined by the oil feed rate of the fuel injection pump, so the oil feed rate changes in proportion to the engine speed. First, sufficient two-stage fuel injection could not be obtained in the high rotation range.

Further, as shown in FIG. 9, a protrusion 5 is provided at the tip of the needle 54 in order to suppress the injection amount at the initial stage of fuel injection.
4a is provided, and at the time of initial injection, this protrusion 54a is located within the nozzle nozzle hole 55 to limit the fuel injection amount by narrowing the nozzle hole area, and when the needle 54 further rises, the protrusion 54a moves into the nozzle nozzle 55. A type of nozzle that deviates from this and has a large nozzle area and performs main injection is also well known.

However, in this type of nozzle, the needle 54
and the protrusion 54a are integrally formed, so when the amount of oil fed from the fuel injection pump (not shown) is large or the oil feeding rate (the amount of oil fed per unit time) is high, the needle 5
4 rises to the maximum lift Q4, and the throttle phenomenon that rises to the protrusion 54a is no longer obtained.

[Problems to be Solved by the Invention] However, in the case of lift control of the needle of a fuel injection nozzle, the oil feed rate changes depending on the rotation speed, so that
The pressure acting on the pressure receiving part of the needle also changes and the fuel injection rate changes.As a result, in the past, for example, in the low rotation and high load range, the lift amount of the needle was small, so the injection rate was regulated at the needle part, and the torque was increased. Temporary deterioration of engine performance, such as a temporary decrease in engine performance, and because the lift of the needle is large in the high-speed, low-load range, the injection rate is no longer regulated at the needle, resulting in worsening of NOx and noise. There is. In addition, the amount of needle lift is determined by the balance with the fuel injection pressure, so when a high injection rate is required when the injection pressure is low, such as when starting an engine, there is a problem that this requirement cannot be fully satisfied. was there.

[Purpose of the Invention] This invention was made to solve the above problems, and its basic purpose is to obtain fuel injection characteristics that match the operating conditions by devising the needle of the fuel injection nozzle. It is something to do.

[Means for Solving the Problems] Therefore, the present invention provides an ejector valve that forms a predetermined gap between the needle of a fuel injection nozzle and the inner circumferential surface of the ejector hole in the nozzle nozzle hole portion, and the ejector valve. are fitted coaxially and slidably in the axial direction, can be seated on the seat surface of the nozzle body, and are divided into an outer peripheral valve that is biased in the seating direction by a valve-closing spring, and A control means for controlling the axial position of the ejection valve is provided.

[Effect of the invention] By making the fuel injection nozzle of the co-diesel engine have the above structure, it is possible to continuously control the flow passage area of the injection hole regardless of the lift amount of the outer peripheral valve, so that it is compatible with the operating conditions. As a result, it is possible to reduce engine noise in the partial load range and nitrogen oxide (NOx) concentration in the exhaust gas without reducing output (torque). The need to increase the amount of injection can be easily met.

Further, according to the present invention, since the axial position of the ejector valve can be controlled arbitrarily, not only the flow path area of the nozzle injection hole but also the amount of protrusion of the ejector valve can be controlled. By protruding the needle valve in the low/medium load range, it is also possible to obtain a so-called needle valve protrusion effect in which hydrocarbons (HC), -carbon oxides (Co), and smorphs in the exhaust gas are reduced.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of a fuel injection nozzle for a diesel engine according to the present invention, which is of the so-called pin type nozzle type. As shown in this figure, a guide bushing 2 is mounted on the upper part of the nozzle body 1, and a nozzle holder body 3 is mounted on the upper part of this guide bushing 2.
are sequentially arranged abutting each other and coaxially, and these are:
The nozzle holder body 3 is integrally fastened and fixed by a retaining nut 4 using a screw threaded onto the outer diameter portion thereof. The nozzle holder body 3 includes a fuel passage 3 that introduces high-pressure fuel supplied from a fuel injection pump (not shown).
a is provided, and this fuel passage 3a is connected to the guide bush 2.
The fuel passage 2a and the fuel passage 1a provided in the nozzle body l and leading to the fuel chamber tb located at the upper part of the nozzle hole 1c coincide with each other and communicate with each other. A seat surface 16 is provided in the nozzle body 1 at an intermediate portion between the fuel chamber lb and the injection hole IC, and a seat surface 16 is provided in the center hole, and a seat surface 16 is provided in the center hole. A peripheral valve 5 with a tip 17 that can be inserted is inserted.

A pressure-receiving taper portion 18 is provided at an intermediate portion between the tip portion 17 of the outer peripheral valve 5 and the outer-diameter sliding portion to lift the outer peripheral valve 5 upward in response to fuel pressure. When the tip 17 of the outer peripheral valve 5 is seated on the seat surface 16 of the nozzle body 1, the portion 18 closes the fuel chamber tb.
It is located inside. The maximum lift amount Q of the outer circumferential valve 5 is determined by the distance between the upper end surface of the outer circumferential valve 5 and the lower end surface of the guide bushing 2. A pressure pin 6 is disposed in the upper part of the outer circumferential valve 5 so as to be inserted into the center hole of the guide bush 2 and protrude into the spring chamber 15 in the nozzle holder body 3. An outer spring 7 is installed between the pressure pin 6 and a spring receiver 8 disposed on the upper end surface of the spring chamber 15, and constantly urges the outer peripheral valve 5 downward via the pressure pin 6.

A through hole is formed in the axial center of the outer peripheral valve 5 and the pressure pin 6, and a protruding valve 9 is provided in this through hole.
is fitted and can be slid in the axial direction. This ejection valve 9 is assembled into the upper part of the nozzle holder body 3, is held by an electromagnetic solenoid type drive control means 11 fixed by a cap nut 13 via a ring 12, and is urged downward by an inner spring IO. ing. The upper limit of the lift of the ejection valve 9 is determined by the lower end surface of the cap nut I3.

The drive control means 11 receives a signal from a mount roll unit 14 that sends a control signal to the ejector valve 9 in accordance with various operating conditions of the engine, drives the ejector valve 9, and controls its axial position.

In addition, in the nozzle holder body 3, the spring chamber 1
A passage 19 provided so as to be led to the outside from the peripheral valve 5 and a passage 20 provided so as to be led to the outside from the space defined between the protrusion valve 9 and the cap nut 13. This passage is provided to return the oil that has lubricated the sliding parts of the valve 9 to an oil tank (not shown).

In the above configuration, high-pressure fuel pumped from a fuel injection pump (not shown) flows through the fuel passages 3a and 2a.

The fuel is introduced into the fuel chamber lb sequentially through the fuel chambers 1a and 1b, and applies a valve-opening force to the pressure-receiving tapered portion 18 of the outer valve 5.

When this valve-opening force exceeds the valve-closing force determined by the spring load of the outer spring 7 that biases the outer circumferential valve 5 toward the valve-closing side, the outer circumferential valve 5 rises and the nozzle hole 1c of the nozzle body 1
Fuel injection begins. At this time, the ejection valve 9 is a control unit, regardless of the axial position and rising speed of the outer peripheral valve 5. Since the axial position of the protruding valve 9 is directly controlled by the control means 11 in response to the signal from the nozzle 4, for example, even if the outer peripheral valve 5 rises suddenly to the maximum lift, the protruding valve 9 cannot be moved into the nozzle hole 1c. While maintaining the throttle state while the protruding valve 9 is kept protruding, the protruding valve 9 is slid up and down depending on various operating conditions of the engine to continuously open the nozzle hole 1c.
The area of the flow path can be changed.

FIG. 2 is a graph schematically showing how the flow path area S of the nozzle hole lc changes with respect to the lift measurement of the outer peripheral valve 5,
The horizontal axis represents the lift measurement of the outer peripheral valve 5, and the vertical axis represents the flow path area S of the nozzle hole 1c. As can be seen from this graph, in the case of a conventional fuel injection nozzle with an integrally formed needle, the valve opens (L=O) as shown by the solid line in Figure 2.
There are only - ways in which the flow path area S changes from to the maximum lift (L = J2.), and the maximum value S of the flow path area S
Of course, O was also constant. On the other hand, in the case of the fuel injection nozzle according to the embodiment of the present invention, the lift ff1L is the lift amount ep corresponding to the point P which is the starting point of the throttle period.
In a region larger than , the relationship between the flow path area S and the lift scale changes according to changes in the amount of protrusion of the protrusion valve 9, as shown by broken lines A, B, C, and D in FIG. , it changes in many ways, and the maximum lift (L=
The flow path area in 121) can also be changed from the flow path area Ss at throttle time as the minimum value to the maximum SA (>So). That is, both the throttle period and the maximum flow area can be varied. For example, the broken line A shows the maximum lift (L=I2) from the valve opening (L=0).
．． ), the protrusion valve 9 is controlled so as not to protrude from the tip of the outer peripheral valve 5 at all. In this case, no throttle phenomenon is observed, and the maximum flow area SA is the same as the protrusion part. Therefore, it is generally larger than the maximum value So in the case of an integrated type of 21 dollars. On the contrary, the dashed line indicates the maximum lift (t, = C,) from the valve opening (shi-〇).
The figure shows the case where the protrusion valve 9 is controlled to protrude into the injection hole IC over the entire period leading up to the maximum lift. The flow path area at (L-J,) also remains the flow path area Ss at the time of throttle. A broken line C shows the case where the protrusion valve 9 is controlled so that the throttle period becomes longer. Moreover, a broken line B shows the case where the protrusion valve 9 is controlled so that the throttle period is shortened.

As described above, the protrusion amount of the protrusion valve 9 is controlled regardless of the lift amount of the outer peripheral valve 5, and the flow path area S of the nozzle hole IC is controlled.
For example, when the engine is running at low speed, by narrowing down the flow passage area S to a small value to lengthen the throttle period, and then gradually increasing the flow passage area S, the torque can be reduced as previously experienced. It is possible to eliminate the temporary drop phenomenon. FIG. 3 is a diagram showing changes in torque in a low rotation range, with the horizontal axis representing engine speed and the vertical axis representing torque. In this diagram,
The solid line shows the example of the present invention, and the broken line shows the case using the conventional fuel injection nozzle.The torque valley in the low rotation range seen in the conventional example is eliminated in this example, and the characteristic curve is generally gentle. It can be seen that it shows.

Further, according to the present invention, since the axial position of the ejector valve 9 can be determined arbitrarily, it is possible to control the flow path area S of the nozzle injection hole IC and at the same time, control the amount of protrusion of the ejector valve 9. As a result, by protruding the needle valve in the low and medium load range, hydrocarbons (H
C) - The needle valve protrusion effect of reducing carbon oxide (CO) and smoke can also be obtained. Figures 4 and 5
6 and 6 are diagrams schematically representing the needle valve protrusion effect, in which the horizontal axis represents the engine load, and the vertical axis represents hydrocarbons (HC) and carbon oxide (Co) contained in the exhaust gas. ) and the amount of smoke, respectively. Figure 4 above,
In FIGS. 5 and 6, the solid line indicates the case where the needle valve protrudes, and the broken line indicates the case where there is only the needle valve protrusion.

FIG. 7 shows the main parts of another embodiment of the invention. In this figure, a protruding valve 3.2 is inserted into the axial hole of the outer peripheral valve 3I from above, and a pressure pin 33 is screwed into the upper part. The above outer peripheral valve 31
In this, a controlled flow is introduced from a space 34 defined by the upper end surface of the protruding valve 32 and the lower end surface of the pressure bin 33 at the upper part of the axial hole of the outer peripheral valve 31 to the outer surface of the outer peripheral valve 3I. A hole 35 and a controlled flow discharge hole 36 are drilled through the lateral force direction. Further, on the outer diameter part of the outer peripheral valve 31, the upper surface of the shoulder of the pressure pin 33 and the guide bush 3 are arranged at the openings of the control inlet hole 35 and the control outlet hole 36.
An artificial notch 37 and an outlet notch 38 are provided, respectively, which have a longer axial length than the maximum lift ff1(!,) of the outer circumferential valve 31 determined by the maximum distance between the lower end surfaces of the nozzle body. 40 is provided with a control flow introduction hole 41 that communicates the inlet cutout 37 and the fuel passage 40a at a portion facing the inlet cutout 37, and the control flow introduction hole 41
is opened or closed by an inlet valve 43 which is interposed between the artificial notch 37 and the fuel passage 40a and is opened or closed in response to a signal from the control unit 47. Further, a control flow discharge hole 42 is provided at a portion facing the outlet cutout 38 to communicate the outlet cutout 38 with a spring chamber 45 located above the guide bush 39. is interposed between the outlet notch 38 and the spring chamber 45, and is connected to a control unit 47.
The outlet valve 44 is opened or closed by the outlet valve 44, which opens and closes in response to a signal from the outlet valve 44. In addition, the spring chamber 45
A relief passage 46 is provided at the top of the fuel tank for returning control flow to the fuel tank (not shown).

In the above configuration, the inlet valve 43 and the outlet valve 44
is opened and closed by a control signal sent from the control unit 47, and by controlling the pressure in the space 34 above the ejection valve 32, the amount of ejection of the ejection valve 32 can be controlled. For example, inlet valve 43. When both outlet valves 44 are in the open state, a portion of the high-pressure fuel sent to the fuel passage 40a is introduced from the control flow inlet 41 as a high-speed control flow, and flows into the inlet notch 37.
．． Since it passes through the space 34 through the control inlet hole 35, a negative pressure is generated in the space 34, and the ejection valve 32 is lifted upward. The controlled flow that has passed through the space 34 passes through the controlled outlet hole 36, the outlet notch 38, and the controlled flow outlet 42, and is discharged into the spring chamber 45 on the low pressure side, and from the spring chamber 45 into the relief passage. 46
The fuel is returned to the fuel tank (not shown) through the Further, when the outlet valve 44 is closed while the inlet valve 43 remains open, the pressure in the space 34 becomes equal to the fuel pressure,
Since this pressure acts on the upper end surface of the ejector valve 32, the ejector valve 32 descends downward and becomes in a protruding state. In this way, by operating the inlet valve 43 and the outlet valve 44 in accordance with the signals from the control unit 47 that sends control signals according to various operating conditions of the engine, the state of the controlled flow, that is, the space above the ejection valve 32 can be controlled. By controlling the pressure of 34, the amount of protrusion of the ejection valve 32 can be controlled.

As explained above, according to the present invention, the axial position of the protruding valve can be controlled according to various engine operating conditions regardless of the lift of the outer circumferential valve, so that the flow passage area of the nozzle hole can be continuously adjusted. control, it is possible to obtain fuel injection characteristics that match the engine's slow rotation conditions, and as a result, the output (
It is possible to reduce engine combustion noise in the partial load range and nitrogen oxide (NOx) concentration in exhaust gas without suffering a decrease in torque), and also to reduce the need for increased injection amount at startup etc. You can easily satisfy that request.

Furthermore, according to the present invention, since the amount of protrusion of the protrusion valve can be controlled arbitrarily, the needle valve protrusion effect can be easily obtained, and in the low to medium load range, the amount of protrusion of the protrusion valve can be controlled. HC), -carbon oxide (Co) and smoke can be reduced.

It should be noted that although the above embodiments were directed to a single-hole pin type nozzle, it goes without saying that the present invention can also be applied to other types of nozzles, such as multi-hole pole type nozzles.

[Brief explanation of the drawing]

FIG. 1 is an overall vertical sectional view showing a fuel injection nozzle according to the present invention. FIG. 2 is a diagram showing the change in the flow passage area of the nozzle hole section with respect to the lift of the outer peripheral valve, and FIG. 3 is a diagram showing the change in torque with respect to the engine rotation speed. The characteristics of the example and the conventional fuel injection nozzle are compared. 4, 5, and 6 are diagrams for explaining the needle valve protrusion effect, and FIG. 7 is a sectional view of main parts showing another embodiment of the present invention, and FIG. and FIG. 9 are sectional views of main parts of a conventional fuel injection nozzle. ■...Nozzle body, lc...Nozzle hole section, 5.31
...Outer valve, 7...Outer spring, 9.3
2... Projection valve, 11... Control means, 16... Nozzle body seat surface.

Claims (1)

[Claims] (1) The needle is fitted coaxially and slidably in the axial direction with a protrusion valve that forms a predetermined gap between the needle and the inner peripheral surface of the nozzle hole in the nozzle hole portion of the nozzle body. Ori,
A peripheral valve that can be seated on the seat surface of the nozzle body and is biased in the seating direction by a valve-closing spring, and a control means that controls the axial position of the protrusion valve is provided. A diesel engine fuel injection nozzle featuring: