Fuel Injection Nozzle

Abstract

A pintle type fuel injection nozzle comprises a nozzle body, a needle movable relative to the nozzle body, and means provided above the needle for controlling the extent of lift of the needle according to the engine speed and engine load.

Description

FIELD AND BACKGROUND OF THE INVENTION

This invention relates to fuel injection nozzles for internal combustion engines and, more particularly, to fuel injection nozzles where the lift of the needle is varied according to the engine speed and load.

In internal combustion engines, in order to ensure satisfactory combustion with a constant density of sprayed fuel, it is usually desirable to provide fuel spray of strong penetration when the engine load is large, i.e., when the quantity of fuel supplied is large, and to provide a fuel spray of weak penetration when the engine load is small, i.e., when the quantity of fuel supplied is small.

The usual fuel injection nozzles are roughly classed into two kinds, namely hole type nozzles and pintle type nozzles. The hole type nozzles generally provide a small spray angle and strong spray penetration, while the pintle type nozzles generally provide a large spray angle and weak spray penetration. Heretofore, it has been usual to adopt fuel injection nozzles of either one of the above two types for installation on engines. Therefore, there is a drawback in that, where the hole type nozzle is adopted, the spray penetration tends to be excessive at the time of small-load, low-speed engine operation. On the other hand, where the pintle type nozzle is adopted, the spray penetration tends to be insufficient at the time of large-load, high-speed engine operation.

The above problem, that is, the inability of providing a satisfactory fuel spray at both small load or large load engine operation, could not be solved insofar as either one of the above two kinds of fuel injection nozzles is solely adopted.

In order to facilitate the understanding of the invention, the relation between engine speed or load and spray angle or penetration will first be discussed in connection with FIG. 1, which shows a pintle type nozzle as an example of a prior-art fuel injection nozzle.

Referring to FIG. 1, reference numeral 1 designates a nozzle holder body, and numeral 2 a nozzle body. The nozzle body 2 is secured to the nozzle holder body 1 together with an intervening distance piece 3 by means of a nozzle nut 4. Accommodated within the distance piece 3 is a push rod 5. A clearance L is defined between the lower end of the distance piece 3 and the top of a large diameter portion of a needle 6 accommodated within the nozzle body 2. A nozzle spring 8 is disposed to bear at one end upon the top of the push rod 5 and at the other end upon the nozzle holder body 1 through a shim 7. The nozzle holder body 1, distance piece 3 and nozzle body 2 are formed with respective fuel ducts or passages 9, 10 and 11 communicating with one another and with a fuel storage cavity or recess 12 formed in the nozzle body 2 near the tip thereof. Numeral 13 designates the nozzle hole provided at the nozzle tip. The needle 6 has a lower extension projecting from the tip of the nozzle body 2 for a length P. The relation betweeen clearance L and projecting length P is set as L > P. The nozzle holder body 1 is also formed with an oil leakage duct 14, and a hose joint 15 is provided at the outer open end of the duct 14.

In operation, pressurized fuel introduced from a fuel injection pump (not shown) through the fuel ducts 9, 10 and 11 into the fuel storage cavity 12 lifts the needle 6 so that the fuel is sprayed through the nozzle hole 13.

The extent of lift of the needle 6 at this time, however, will not exceed a predetermined value since the clearance L is preset. Therefore, with the above construction it is impossible to vary the afore-mentioned lift for varying the form of the fuel spray so as to maintain optimum fuel density under changing engine speed and load, that is, it is impossible to obtain satifactory fuel-to-air ratio for maintaining sufficient ignition and combustion within the combustion chamber in the high-speed, large-load engine operation.

SUMMARY OF THE INVENTION

The present invention is based on a fact that the spray form may be varied by varying the extent of lift of the needle in pintle type fuel injection nozzles as shown in FIG. 1, and it has for its object the provision of a fuel injection nozzle with which the lift of the needle can be varied according to the engine speed and load to always provide satisfactory fuel spray for the formation of fuel-air mixtures with optimum fuel-to-air ratios over the entire range of engine speed and engine load.

The above and other objects and features of the invention will become more apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, it is of course to be understood that the invention is by no means limited by the illustrated embodiments but is limited only by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is an axial sectional view of a prior-art fuel injection nozzle;

FIG. 2 is an axial sectional view of a first embodiment of the fuel injection nozzle according to the invention;

FIGS. 3 and 4 are axial sectional views, with a block form showing of associated parts, of second and third embodiments of the fuel injection nozzle according to the invention; and

FIG. 5 is an enlarged fragmentary axial sectional view showing the tip of the fuel injection nozzle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the drawings, like or equivalent parts are designated by identical reference numerals.

Referring to FIG. 2, there is shown a first embodiment of the invention. As is clearly shown in FIg. 5, the needle 6 has a lower extension or pin-like portion 6A having a first downwardly tapering conical surface 6.sub. 1 terminating in a second downwardly flaring conical surface 6.sub.2 terminating in a third, downwardly tapering conical surface 6.sub.3 at the lower or downstream end. The diameter d of the pin-like portion 6A at the junction between the second and third conical surfaces 6.sub.2 and 6.sub.3 is made smaller than the inner diameter D of the nozzle hole 13 of the nozzle body 2. Also, the distance S of the extension of the aforementioned junction from a second junction between a downwardly tapering conical inner surface 2.sub.1 of the nozzle body 2 and the cylindrical inner surface of the nozzle hole 13 is made greater than the distance T of the afore-said second junction from the lower end of the nozzle body 2.

Numeral 16 designates a control rod extending axially through the nozzle holder body 1 and defining a clearance C between its lower end and the top of the push rod 5. The relation between the clearances C and L is made such that C < L, and the relation between the clearance L and the length P of a portion of the lower extension 6A projecting from the lower end of the nozzle body 2 is made such that L > P. An upper portion 16A of the control rod 16 is threaded, and a nut 17 is fitted on the threaded portion 16A and secured to the top of the nozzle holder body 1. Further, a control lever 18 is secured to the top of the control rod 16, so that the control rod 16 is vertically movable by rotating the control lever 18. The control lever 18 is coupled to an engine speed regulator built in a fuel injection pump, not shown. Numeral 19 designates an O-ring interposed between control rod 16 and nozzle holder body 1 to prevent fuel leakage therebetween.

The operation of the fuel injection nozzle of the above construction is essentially similar to the prior-art pintle type fuel injection nozzle. With this construction, however, the extent of lift of the needle is not fixed but variable. More particularly, by the control of the rotational angle of the control lever 18 in accordance with the engine speed and load through the speed regulator, the position of the control rod 16 may be changed vertically to change the magnitude of the clearance C, whereby the lift of the needle 6 may be varied according to the engine speed and load within the range of the clearance L.

The clearance L is made large enough so that the tip of the needle 6 may be withdrawn into the nozzle hole 13. Thus, the tip of the needle 6 may be brought into and out of the nozzle hole 13 in accordance with the angular position of the control lever 18. It may be withdrawn into the nozzle hole 13 at the time of high-speed, large-load engine operation for obtaining a fuel spray of small angle and strong penetration, while it may be projected from the nozzle hole 13 at the time of low-speed, small-load engine operation to obtain a fuel spray of large angle and weak penetration. In this way, it is possible always to provide a satisfactory form of fuel spray for the formation of the fuel-air mixture with an optimum fuel-to-air ratio in either high-speed and large-load or low-speed and small-load engine operation.

FIG. 3 shows a second embodiment, in which the position of the control rod 16 is not controlled mechanically, as in the preceding first embodiment but through electromagnetic means. In the Figure, numeral 20 designates a needle lift controller, which provides appropriate current as a output according to the engine speed and load. Numeral 21 designates a control spring, and numeral 22 an electromagnetic coil. In this device, the control rod 16 is made of a magnetic material, at least its upper portion extending from the nozzle holder body 1, and has the spring 21 interposed between its top and the electromagnetic coil 22.

In this embodiment, the position of the needle 6 is determined by supplying information concerning the engine speed and load to the needle controller 20 so as to cause appropriate current, depending upon the spring force of the control spring 21, to pass through the electromagnetic coil 22. In this way, similar to the previous first embodiment, the position of the control rod, which is here made of a magnetic material in at least its upper portion, may be varied to vary the extent of the lift of the needle 6 according to the engine speed and load, so that it is possible always to ensure satisfactory ignition and combustion.

FIG. 4 shows a third embodiment. In this embodiment, the needle 6 is provided with an upper, small-diameter integral extension 6B, and an electromagnetic coil 23 is provided to surround this integral portion 6B. Also, a valve spring 24 is interposed between a base or seat 6'a provided at the top of the integral portion 6B and the nozzle holder body 1.

Numeral 25 designates a fuel tank, numeral 26 a fuel pump, numeral 27 a pressurizing chamber, and numeral 28 a fuel valve. The fuel in the fuel tank 25 is introduced through the fuel pump 26 into the pressurizing chamber 27, where it is pressurized to a constant pressure, and thence it is introduced through the fuel valve 28 into the nozzle holder body 1.

Numeral 29 designates a speed regulator, and numeral 30 a fuel controller. The speed regulator 29 produces a signal according to the engine speed and engine load, and this signal is coupled to the fuel controller 30, which in turn produces an output signal corresponding to the engine speed and engine load for on-off controlling the fuel valve 28. In this way, the requisite quantity of fuel is supplied into the nozzle holder body 1, that is, into the fuel storage cavity 12, in accordance with the engine speed and engine load.

Meanwhile, the signal produced from the speed regulator 29 according to the engine speed and load and the signal produced from the fuel controller 30 according to the rate of flow of the fuel are coupled to an optimum needle lift calculator 31, which produces an output signal coupled to a needle lift controller 32. The needle lift controller 32 also receives the output signal of a timing detector 33, and provides current, as its output, caused to flow, in dependence upon the force of the valve spring 24, through the electromagnetic coil 23. In this way, the needle 6 having the small diameter integral extension 6B is lifted to optimum extents according to the engine speed and engine load, so that it is possible to obtain a fuel spray of strong penetration at the time of high-speed and large load engine operation and a fuel spray of large angle at the time of low-speed and small-load engine operation.

As has been described in the foregoing, with the pintle type fuel injection nozzle according to the invention it is possible to control the fuel spray form so as to obtain strong spray penetration at the time of high-speed and large-load engine operation and a large spray angle at the time of low-speed and small-load engine operation through the means of varying the extent of lift of the needle 6 according to the engine speed and engine load, which means may consist of a control rod 16 and means for mechanically or electrically varying the position of the rod, as in the first or second embodiment of FIG. 2 or 3, or means for electrically calculating the optimum lift and causing corresponding current through an electromagnetic means, as in the previous third embodiment of FIG. 4.

Claims

What is claimed is:

1. In a pintle type fuel injection nozzle of the type including a nozzle body formed with a cavity receiving fuel under pressure and with a cylindrical discharge orifice communicating with the cavity, a needle mounted for movement in the nozzle body for reciprocation axially of the orifice to control discharge of fuel therethrough, the needle being subjected to the pressure of the fuel in the cavity acting to move the needle in a nozzle opening direction, and means biasing the needle in a nozzle closing direction; the improvement comprising, in combination, said needle having a reduced extension engageable in said orifice and formed with an inner cylindrical portion, a downwardly tapering intermediate portion extending from said cylindrical portion, and a downwardly flaring outer portion extending from said intermediate portion and terminating in an outer edge, of a diameter less than that of said orifice, movable axially into and out of said orifice, upon reciprocation of said needle, to vary the spray angle and magnitude of penetration of the fuel discharged from said nozzle; and control means operatively associated with said needle and controlling the extend of lift of said needle, responsive to fuel pressure in said cavity, in accordance with engine speed and engine load.

2. In a pintle type fuel injection nozzle according to claim 1, said needle lift control means including a control rod disposed in axial alignment with and spaced from said needle, and means operable to control the axial position of said control rod.

3. In a pintle type fuel injection nozzle according to claim 2, wherein said rod position controlling means includes an electromagnetic coil disposed on a nozzle holder body, an extension of said control rod extending through said electromagnetic coil, and a needle lift controller coupled to said electromagnetic coil.

4. The pintle type fuel injection coil according to claim 1, wherein said needle lift control means includes a small diameter extension integral with the inner end of said needle, a stationary electromagnetic coil surrounding said small diameter extension, and a needle lift controller coupled to said electromagnetic coil.

5. A fuel injection system comprising the pintle type fuel injection nozzle according to claim 4, a speed regulator to provide a signal according to the engine speed and engine load, a fuel controller receiving the output signal of said speed regulator, and an optimum lift calculator receiving the output signal of said fuel controller, the output of said optimum lift calculator being coupled to said needle lift controller, and the output of said fuel controller being also used to control a fuel valve.

6. A pintle type fuel injection nozzle comprising a nozzle body, a needle movable relative to said nozzle body, and means provided above said needle for controlling the extent of lift of said needle according to the engine speed and engine load; said needle lift control means including a control rod disposed inwardly of said needle and spaced from said needle, and means to control the vertical position of said control rod; said vertical rod position controlling means including a male thread formed on an upper portion of said control rod, a female thread member provided on top of a nozzle holder body and screwed on said male threaded portion, and means provided on top of said control rod for rotating said control rod.