US3477648A - Fuel injection nozzle - Google Patents

Description

NOV. v, RQOSA FUEL INJECTION NOZZLE Filed July 12, 1967 A mmm s MEN. MM. 1% PM. 1 m w .M m

, NM 6% W a j United States Patent 3,477,648 FUEL INJECTION NOZZLE Vernon D. Roosa, West Hartford, Conn. (Hartford Machine Screw Co., P.O. Box 1440, Hartford, Conn.

' Filed July 12, 1967, Ser. No. 652,872 Int. Cl. B05b 1/32; F23k 5/00 US. Cl. 239-533 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to fuel injection nozzles for internal combustion engines and is an improvement in the nozzle described in my prior Patent 3,224,684, issued Dec. 21, 1965, and entitled Fuel Injection Nozzle.

In fuel injection nozzles of the type contemplated by this invention, the valve is lifted from its seat against the bias of a spring by the pressure of the fuel delivered to the nozzle from an associated high pressure pump in measured quantities or charges. Each charge of fuel is discharged from the nozzle into a combustion chamber of an associated engine, and its discharge is timed to take place when the air in the combustion chamber is compressed and continues after ignition of the fuel begins. The pressure of the charge must be substantially higher than the pressure within the combustion chamber in order to discharge the fuel during the short interval available for injection. This may present a problem at cranking speeds when the inherent leakage in the pump may be suflicient to reduce the pressure developed by the pump and hence the quantity of fuel delivered to the engine. Moreover, particularly under cold starting conditions, it is desirable to provide for early injection of at least part of the fuel into the cylinder to facilitate the ignition thereof.

Accordingly, it is one object of this invention to provide for the injection of a portion of the fuel into the engine prior to the opening of the nozzle valve. Included in this object is the provision of a nozzle wherein the reverse flow of combustion gases into the nozzle is prevented.

Another object of this invention is to provide a nozzle which enhances the cold starting capabilities of the engme.

Another object of this invention is to provide a fuel injection nozzle which promotes an improved flame propagation during the combustion of the fuel.

A still further object of this invention is to provide a fuel injection nozzle which delivers excess fuel for startmg.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which is exemplified in the construction hereafter set forth, and the scope of the invention is indicated in the appended claims.

In the drawing:

FIG. 1 is a cross-sectional view of a portion of a fuel injection nozzle embodying the present invention in conice junction with a schematic illustration of an associated high pressure pump for delivering measured. charges of fuel to the nozzle; and

FIG. 2 is a fragmentary cross-sectional view, similar to FIG. 1, of a portion of the fuel injection nozzle embodying a modified form of the invention.

Referring to the drawing, in which like numerals refer to like parts throughout the several views, the exemplary nozzles shown therein are generally similar to the nozzle illustrated in my aforementioned prior Patent 3,224,- 684 and includes an elongated generally tubular body member 10 having a nozzle tip 12 rigidly fixed at one end thereof and a central longitudinal bore 14 extending throughout its length. Located within the central bore 14 is a rod-like plunger stem or valve 16 which cooperates with a conical valve seat 18 formed in the nozzle tip 12 to control the discharge of fuel from the nozzle body 10-. A valve guide 20 fixedly positioned within the bore 14 of the body 10 at a position remote from the valve seat 18 slidably mounts and aligns the valve 16 so as to permit rapid reciprocal movement thereof within the bore 14 under the influence of the fuel pressure within the bore 14 against the bias of spring 22. The nozzle is provided with a fuel inlet 24 communicating with the bore 14 of the nozzle body 10 for delivery of high pressure fuel thereto adjacent the guide 20 from an associated high pressure fuel pump 26.

The upper end of the valve 16 is shown as being provided with a partispherical surface 25 which swivelly engages a spring seat 28 having a complementary partispherical surface. The other end of the spring 22 is shown as being similarly provided with. a spring seat 30 which swivelly engages an annular washer 32 with the washer 32 and the spring seat 30 providing complementary partispherical engaging surfaces to accommodate lack of squareness of the ends of the spring 22 or axial misalignment between the valve 16 and the annular washer 32.

The annular washer 32 is seated against the end of an externally and internally threaded longitudinally slotted retaining sleeve 34 the external threads 35 of which are threadably received in the internal mating threads 36 of the tubular body 10.

The internal threads 38 of retaining sleeve 34 threadably receive an externally threaded stop 40 to provide an adjustable lift stop for the valve 16. With this arrangement, the nozzle valve opening pressure may be adjusted as desired by merely turning the retaining sleeve 34 in or out until the desired biasing force is provided by the spring 22, and the valve lift may be independently adjusted by axially adjusting the stop 40 with respect to the retaining sleeve 34. Lock nut 46 which is threaded on the external threads 35 of the retainer sleeve 34 is tightened against the end shoulder 48 of the tubular body 10 to maintain the retaining sleeve 34 and the lift stop pin 40 in adjusted position.

The charge pump 26 illustrated schematically in FIG. 1 is of the type more fully described in my prior Patent 3,204,622 issued Sept. 7, 1965 and entitled Fuel Injection Pump Timing Device. For the purpose of describing this invention it is suflicient to state that the pump 26 includes a pair of pistons 50 which are reciprocated radially as the rotor 52 is rotated in timed relation with the associated engine through intermediate roller shoes 54 and rollers 56 which engage diametrically opposed cam lobes 58 of relatively stationary cam 60 to pressurize the measured quantity or charge of fuel within the chamber 62 of the charge pump. As more fully explained in the aforesaid Patent 3,240,622, the delivery passage 64 of pump 26 registers with the rotor outlet passage 65 from the charge pump chamber 62 to deliver the highly pressurized measured charge of fuel to inlet 24 of the nozzle.

The pressurized fuel delivered to the inlet 24 by the charge pump increases the pressure of the fuel within the bore 14 and acts on the areas 66 and 68 of the valve 16. When the force exerted thereby is sufircient to overcome the bias of spring 22 to move the valve 16 upwardly, the charge of fuel is discharged through the orifices 11 in the nozzle tip 12.

It will be apparent that at low cranking speeds the leakage past the pistons 50 and through the other clearances within the pump 26 during the pumping stroke will be greater than the leakage at higher speeds because of the greater interval of time required by the pumping stroke. Since the pressure within bore 14 must reach a predetermined level to overcome the pressure of the biasing spring 22 and open the valve 16 to initiate the injection of fuel by the nozzle, it is apparent that at slow cranking speeds, the amount of fuel delivered by prior nozzles as compared with the maximum capability of the pump is reduced. Since it is desirable to provide a system having the capacity to deliver excess fuel for starting, any reduction in the quantity of fuel delivered to the engine under starting conditions is considered detrimetnal to the starting capabilities of the engine.

This invention provides a solution for this problem.

Referring to FIG. 1, a small opening 70 is provided in z the nozzle tip 12. Opening 70 has a small diameter of, say, 6 mils (or approximately /2 the diameter of the ports 11) and is spaced above the valve seat 18 so as to provide a bypass for the delivery of fuel by the nozzle when the valve 16 is seated on the valve seat 18.

As the pressure of the nozzle increases as the rollers 56 of the pump 26 move up the leading surface of the cam lobes 58, a minor amount of the fuel delivered by the charge pump is sprayed into the cylinder before the pressure of the fuel in the bore 14 is sufiicient to lift the valve 16 from the valve seat. Desirably the opening 70 is indexed with respect to the cylinder so as to provide a spray into the center of the cylinder where it will cornbust more readily and serves to cause a more uniform ignition of the main charge of fuel subsequently discharged through ports 11 of the nozzle tip 12 for more uniform flame propagation throughout the charge within the cylinder thereby providing maximum power.

As the pressure in bore 14 begins to drop, the pressure within the bore 14 would normally fall very rapidly since very little restriction is offered to the flow of fuel. With the combustion pressures within the associated cylinder rising rapidly due to the combustion of the fuel in the cylinder, it is apparent that the use of the opening 70 alone would permit the reverse flow of combustion gases into the nozzle. To avoid this undesirable result, this invention provides a hydraulic restriction effective to prevent the reverse flow of fuel from the chamber 14a as the pressure therein decreases.

In the exemplary embodiment of FIG. 1, such a hydraulic restriction is provided by the spring biased oneway check valve at the inlet 24 of the nozzle. As shown, the ball 72 is biased into engagement with the seat 74 by light biasing spring 76 which is held in adjusted position by an externally fluted stop 78 positioned in an intermediate coupling element 79 serially disposed in sealed relation between the separable ends of the inlet 24 and the supply line 81. The stop 78 may be secured in the bore 82 of the intermediate coupling element 79 by a light press fit since the only requirement for the spring 76 is to bias the ball 72 lightly toward the seat 74. The stop 78 may be provided with an axial extension 84 disposed concentrically within the spring 76 to limit the movement of the ball 72 from the seat 74. It will be apparent that, as the pressure within the delivery passage 64 of the pump reduces to cause reverse flow of the fuel from the nozzle toward the passage 64, the ball 72 is automatically seated to trap the fuel within the nozzle thereby maintaining the bore 14 of the nozzle filled with fuel and preventing the entry of combustion gases through the opening 70 into the nozzle.

Referring now to FIG. 2, there is shown another embodiment of this invention wherein an annular one-Way valve 86 is provided to obstruct the reverse flow of fuel out of the chamber 14a adjacent the valve seat. The washer 86 is preferably formed of a resilient low surface friction material, such as neoprene, and is when assembled, in the form of a truncated cone to form a seal with valve 16 to prevent the reverse flow of fuel from the chamber 1411 while at the same time being expandable under the influence of the pressure from the charge pump to permit the passage of fuel toward the chamber 14a. The upper end 87 of the washer 86 may be reinforced and secured to the nozzle body in any desired manner as, for example, by a sleeve 88 secured in the bore 14 by a press fit and overlying the upper end 87 of the washer 86 in clamping relationship. Furthermore, since the washer 86 engages the valve 16 with a sliding fit, it is apparent that the valve is free to reciprocate into and out of engagement with the valve seat 18.

It will thus be seen that the washer 86 will expand to allow fuel flow toward the chamber 14a but will be automatically held in tight sealing relationship by the pressure in the bore 14 and the chamber 14a to obstruct the reverse flow of fuel from chamber 14a, thereby maintaining chamber 14a full of liquid fuel and preventing the entry combustion gases.

From the foregoing it will be apparent that the invention provides a fuel nozzle which will permit the preinjection of a desired predetermined portion of the fuel charge into the cylinder under starting conditions to obtain the attendant advantages set forth.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure of the above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injection nozzle for delivering to the combustion chamber of an associated engine pulsed fuel charges received from a high pressure fuel source comprising a nozzle body having a valve seat and a discharge tip at one end projecting into the combustion chamber of the associated engine, an inwardly opening pressure actuated valve having a stem disposed in said nozzle body and spaced therefrom to define an annular passage, guide means mounting said valve for reciprocating movement toward and away from the valve seat, an inlet conduit for delivering fuel to a chamber adjacent the valve seat through said annular passage and a one-way valve disposed in said annular passage to oppose the reverse flow of fuel toward said inlet conduit said one-way valve comprising a truncated conical washer secured in the passage to accommodate reciprocation of the valve relative thereto, the washer being formed of a resilient material and having its smaller diameter downstream relative to the flow of fuel from said inlet to said chamber to accommodate the forward flow of fuel therebetween. 60

References Cited UNITED STATES PATENTS EVERETT W. KIRBY, Primary Examiner US. Cl. X.R.

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