Patent Publication Number: US-3876152-A

Title: Noncoking fuel injection nozzle

Description:
D United States Patent 1191 1111 Roosa Apr. 8, 1975 [54] NONCOKING FUEL INJECTION NOZZLE 3.348.520 l0/l967 Lockwood 239/93 X {76] inventor: Vernon D. Roosa, c/o Hartford FOREIGN PATENTS OR APPUCATIONS Scre C 8 a ga v 1.453.616 8/1966 France 239/533 Hartford. Conn. 06005 412.741 2/l946 Italy 239/533 [22] Flled: 1967 Primary E.\&#39;uminerLloyd L. King [2]] Appl. No.: 609,178 Attorney. Agent, or Firm-Prutzman. Hayes. Kalb &amp;  
 Chilton [52] U.S. Cl. 239/533 1511 Int. Cl B05b 1/30 [57] I ABSTMCT [58] Field of Search 239/533, 87, 93 A fuel 1 for mmbusm&#34; gines having an inwardly opening pressure operated [56] References cued valve positioned in a bore and guided for reciprocat- UNITED STATES PATENTS ing movement in a guide of larger cross section than 2 5 2 I I I 4/1 5 B h f 39, 33 the stern of the valve wherein a hydraulic restriction to ISC O 3.159.350 l2/l964 Mangold 239/533 lg 5 2? fuel flow between the Stem and the bore 3.224.684 l2/1965 Roosa 239/533 p 3,255.974 6/1966 Roosu 239/533 1 Claim, 4 Drawing Figures NONCOKING FUEL INJECTION NOZZLE This invention relates generally to fuel injection nozzles for internal combustion engines and to an improvement in the nozzle described in my prior U.S. Pat. No. 3,224,684 issued Dec. 21, 1965 and entitled Fuel Injection Nozzle&#34;.  
  In fuel injection nozzles of the type contemplated by this invention, the plunger or valve is lifted from its seat 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 to operate the engine at the desired speed and torque, and the discharge of the charge from the nozzle is timed to take place when the air in the combustion chamber is compressed and continues after ignition of the fuel begins. The nozzle incorporates a biasing spring to hold the valve against the valve seat and to reseat the valve after the charge is discharged into the cylinder when the combustion pressure within the cylinder increases substantially. As the spring is reseating the valve, it is important that the pressure within the valve adjacent the seat is sufficient to prevent combustion gases from entering the nozzle to deposit carbona ceous combustion products. A primary object of this invention is to provide a nozzle capable of preventing such entry of combustion gases.  
  Another object of this invention is to provide a nozzle capable of maintaining the pressure of the fuel within the nozzle adjacent the valve seat at least equal to the combustion pressures within the cylinder during the closing of the valve.  
  Another object of this invention is to provide a nozzle constructed and arranged to provide differential hydraulic pressures between the inlet and discharge ends of the nozzle sufficient to reseat the valve without the reverse flow of combustion gases into the nozzle.  
  A still further object of this invention is to provide a fuel injection nozzle in which the valve serves as a pump to provide a desired pressure of the fuel at the discharge end of the nozzle during the reseating of the valve.  
  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. I is a cross-sectional view of a portion of a fuel injection nozzle embodying the present invention in conjunction with a schematic illustration of an associated high pressure pump for delivering measured charges of fuel to the nozzle;  
  FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG. 1;  
  FIG. 3 is a cross-sectional view taken along the lines 33 of FIG. 1; and  
  FIG. 4 is a cross-sectional view taken along the lines 4-4 of FIG. 1.  
  Referring to the drawing, in which like numerals refer to like parts throughout the several views, the exemplary nozzle shown therein and embodying the present invention is generally similar to that illustrated in my aforementioned prior U.S. Pat. No. 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 valve seat 18 formed in the nozzle tip 12 to control the discharge of fuel from the nozzle body I0. A valve guide 20 fixedly positioned within the bore 14 of the body at a position remote from the valve seat I8 slidably mounts and precisely 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 from an associated high pressure fuel pump 26.  
  The upper end of the valve 16 is 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 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 any 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 retainer 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 retainer sleeve 34 threadably receive an externally threaded pin 40 providing an adjustable lift stop for the valve I6. With this arrangement, the nozzle valve opening pressure may be adjusted as desired by merely turning the retainer 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 pin 40 with re spect to the retainer 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 retainer sleeve 34 and the lift stop pin 40 in adjusted position.  
  The charge pump 26 illustrated schematically in FIG. I is of the type more fully described in my prior U.S. Pat. No. 3,204,622 issued Sept. 7, 1965 and entitled Fuel Injection Pump Timing Device.&#34; It is sufficient to say for the purpose of describing this invention 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 U.S. Pat. No. 3,204,622, 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 charge pump.  
  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 sufficient to overcome the bias of spring 22 to move the valve 16 upwardly, the charge of fuel is discharged through the orifices in the nozzle tip 12.  
  As the rollers 56 begin to engage the trailing surface 580 of the cam lobes 58, as shown in FIG. 1, the pressure within the passageway 64 and the fuel inlet 24 of the nozzle rapidly reduces since very little restriction is offered to the flow of fuel therebetween.  
  The portion 16b (FIG. 3) of the valve 16 is shown as having a diameter which is less than that of guide portion 160 (FIG. 4). Thus, a drop of pressure at the inlet 24 reduces the resultant hydraulic force acting on the differential area of surface 66 over opposed area 67. Under such conditions, the pressure in the chamber 140 acting on the area 68 and the tip of the valve 16 becomes the dominating factor in the total hydraulic force opposing the bias of spring 22.  
  In achieving the objectives of this invention, means forming a hydraulic restriction effective to restrict the reverse flow of fuel from the chamber 140 to the inlet 24 are provided, In the exemplary embodiment, such a hydraulic restriction is provided by intentionally constructing and dimensioning the annular passageway between the portion l6b of the valve and the bore 14 to effect a predetermined amount of restriction to the reverse flow of fuel from the chamber 14a toward the fuel inlet 24 during the reseating of the valve.  
  It will be further understood that during reseating the tip of the valve 16 displaces a quantity of the fuel within the chamber 14a corresponding to the diameter of valve portion 16b multiplied by the longitudinal movement of the valve 16 during reseating. Since the total hydraulic force acting on surface 66 adjacent the inlet 24 and the tip of the valve within chamber 140 are opposed by the spring 22, it will be apparent that as the spring reseats the valve, the valve acts as a pump to pressurize the fuel in the chamber 140 at a level deter mined by the rate of discharge of the fuel from cham ber 14a.  
  In the application of this concept to a specific nozzle structure having a given spring force for spring 22 and given relative areas of portions 16a and 16b of valve 16, the dimensions of the annular fuel passageway between the chamber 140 and the inlet 24 may be so constructed and arranged to maintain or provide any desired fuel pressure in the chamber 140 during the reseating of the valve by providing the desired restriction rate of flow from the chamber 14a to the inlet 24 dur ing reseating. In other words, with a given restriction to reverse fuel flow from chamber 140 to inlet 24, the valve 16 under the bias of spring 22 serves as a pump to continue the pressure in the chamber 140 at any de sired pressure until valve 16 is reseated. Where such pressure is equal to or greater than the effective cylinder pressures during the interval of reseating of the valve 16, the entry of combustion gases into the tip of the valve adjacent the seat 18 is prevented.  
  In carrying out this invention, it is readily apparent that a number of specific combinations of dimensions could be utilized. One specific embodiment which has been constructed is as follows:  
 Diameter of guide portion [6a 0126:: Diameter of stem portion 16b 0.080 Diameter of bore 14 (1105 Diameter of valve seat l3 0.060&#34; Approximate length of uniform re -Continued stricted passage between bore l4 and stem [6b (FIG. 3) 2.5&#34; Spring force 27 No.  
  With the nozzle having the foregoing dimensions, a pressure of just over 2800 psi. will be required to initially open the nozzle when using conventional diesel fuel under normal room temperature conditions. When the rollers 56 begin to descent the trailing surface of cam lobes 58 of pump 26 and the pressure at the inlet 24 drops to, say, 2000 p.s.i., the spring 22 will move the valve toward the valve seat 18 and maintain a hydraulic pressure in the chamber 14a at the nozzle tip at slightly more than 2400 psi. Since this pressure is well above the typical maximum effective combustion pressure of 1500 psi. developed in conventional commercially available nonsupercharged diesel engines, it is readily apparent, and test results confirm, that the nozzle will not permit combustion gases to enter the discharge orifices of the nozzle. Stated another way, by providing a hydraulic restriction effective to restrict the flow of fuel from the chamber 14a at the nozzle tip to the inlet 24 as the pressure at inlet 24 is falling, the pressure in the chamber 14a may be maintained at a higher level than cylinder pressure during the reseating of valve 16 to prevent combustion gases from entering the discharge orifices of the nozzle. This eliminates the possibility of deposits of tacky and tar-like carbonaceous components of the gases within the nozzle and on the valve seat.  
  From the foregoing it is apparent that this invention provides a fuel nozzle which will prevent the entry of combustion gases into the nozzle by maintaining the pressure of the fuel in the nozzle adjacent the nozzle tip at the desired level until the valve is fully reseated under the influence of the biasing spring.  
  As will be apparent to persons skilled in the art, vari ous modifications and adaptations of the structure 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 fol lows:  
  1. In the operation of an inwardly opening pressure actuated nozzle having a plunger normally biased against a valve seat to close the same, a chamber ad jacent the valve seat, and an inlet for receiving intermittent pulses of high pressure fuel for delivery through a passage in the nozzle communicating with said chamber, the steps of delivering a pulse of fuel under high pressure to the inlet to apply a hydraulic force on the plunger sufficient to lift the plunger from the valve seat against the normal bias thereon and to discharge the fuel through the valve seat and maintaining, until the plunger is fully seated, the pressure in said chamber at a level substantially equal to the pressure therein when the plunger begins to reseat by restricting the reverse flow of fuel in said passage as the normal bias exceeds the hydraulic force on said plunger toward the end of the delivery of the pulse.