Abstract: A pressure-responsive spring-biased cutoff valve for an open nozzle unit fuel injector in an internal combustion engine is provided allowing for the selective operation of a given number of cylinders during an engine low load or idling speed condition for improved white smoke control. The fuel injector of the present invention includes an injector body having a central bore with a reciprocating injector plunger positioned therein to form an injection chamber. The injection chamber is supplied with fuel from a supply passage through a metering orifice with the fuel cutoff valve located in the supply passage upstream of and adjacent to the metering orifice and in close proximity to the injection chamber for a substantial reduction in the entry of combustion gases and other unwanted substances into the fuel supply.

Abstract: The present invention is directed to open nozzle unit fuel injectors for injecting a metered quantity of fuel into the cylinder of an internal combustion engine, as synchronously controlled by a drive train, wherein the unit fuel injector comprises an injector body with a reciprocably movable plunger assembly disposed therein. The present invention is more specifically directed to a high pressure open nozzle unit fuel injector including a mechanism for injecting fuel at SAC pressures of 30,000 psi or more. Moreover, the plunger assembly comprises a two-piece plunger with a variable timing chamber and a timing plunger inbetween the upper and lower plungers.

Abstract: An electronically controlled fuel supply system is provided for employing a plurality of fuel injectors which maximize SAC pressures under both low speed and high speed operating conditions and are capable of sustaining SAC pressures in excess of 30,000 psi. The fuel supply system of the present invention includes a gear pump which supplies pressure-modulated fuel to a fueling channel and to a timing channel and from there to a plurality of injectors. Fuel pressure regulator means and timing fluid pressure regulator means are provided in the fueling and timing channel, respectively. An electronic control unit receives information relating to engine operating conditions from a plurality of sensors and actuates the fuel pressure regulator means and the timing fluid pressure regulator means to adjust the pressure as required for the specific engine operating conditions.

Abstract: A fuel injector having both stepped and infinitely variable timing is disclosed. The fuel injector includes an injector housing and a plunger wherein the plunger includes an axial bore formed in the top of the plunger. A plunger top is mounted within the axial bore and is translatable between an upper position and a lower position. A coil spring having a predetermined spring rate is disposed in the axial bore for biasing the plunger top in the upper position. An upper and a lower piston are disposed above the plunger and are translatable within the injector housing. A timing chamber is formed between the upper piston and the lower piston. When the timing chamber contains timing fluid, the fluid serves as a hydraulic link between the upper and lower pistons and the fuel injector operates at a first level of advanced timing.

Abstract: A unit fuel injector for a fuel injection system for an internal combustion engine is described that is reciprocably driven from a camshaft by a drive train, and the unit injector includes a device for controlling the rate of fuel injection into an engine cylinder. The rate control device operates to divert or bleed off a quantity of fuel from the main metering chamber of an open-nozzle type fuel injector during an initial phase of injection, and the diverted fuel is returned to the metering chamber at a later phase in the injector operation. The rate control device includes an auxiliary metering chamber which receives the diverted fuel via an auxiliary passageway. An auxiliary plunger is mounted within the auxiliary metering chamber. A biasing device such as a helical spring or a fluid pressure spring, controls the inward and outward movement of the auxiliary plunger.

Abstract: A valve tappet and control system is provided including expansible and collapsible hydraulic link; wherein the control system causes expansion of the hydraulic link and determines the timing of the collapse and thus the closing of an intake valve of an internal combustion engine. The timing is variable depending on engine operating conditions, such as output power and turbo charger boost pressure. In one embodiment, a rotary valve and fluid gating device is used to connect a pressure line used to expand the hydraulic link to a dump line at one instance during each cam shaft rotation to provide the early closing of the valve. In a second embodiment, a rotary cam follower with an oblique surface is used, wherein the orientations of the oblique surface is the determinative feature that is controlled to change early closing time as well as a delayed opening.

Abstract: A fuel injector includes an injector housing having a plunger assembly disposed within a central axial bore and including a lower plunger, an intermediate plunger, and an upper plunger. The lower plunger reciprocates within the central bore to meter a variable quantity of fuel during downward portions of the reciprocating motion. A timing spring is wound around the upper portion of the lower plunger to bias the lower plunger upwardly. A timing chamber formed between the upper and intermediate plungers receives timing fluid to create a hydraulic link between the plungers. Timing fluid exits the timing chamber through a central passage, which may have a reduced area regulating orifice, formed through the intermediate plunger, which is ordinarily closed by a valve mechanism. The valve mechanism is acted upon in part by the timing spring. To improve the pressure regulation using a higher spring load and to accommodate a larger area drainage passage, a valve spring biases closed the passage.

Abstract: An electronically controlled fuel supply system is provided for employing a plurality of fuel injectors which maximize SAC pressures under both low speed and high speed operating conditions and are capable of sustaining SAC pressures in excess of 30,000 psi. The fuel supply system of the present invention includes a gear pump which supplies pressure-modulated fuel to a fueling channel and to a timing channel and from there to a plurality of injectors. Fuel pressure regulator means and timing fluid pressure regulator means are provided in the fueling and timing channel, respectively. An electronic control unit receives information relating to engine operating conditions from a plurality of sensors and actuates the fuel pressure regulator means and the timing fluid pressure regulator means to adjust the pressure as required for the specific engine operating conditions.

Abstract: A cam for controlling the injection rate of fuel in a fuel injection system having a four part cam profile is disclosed. The first 120.degree. is the plunger advancement segment. The next 80.degree. is the advanced dwell segment. The next 100.degree. is the plunger retraction segment and the last 60.degree. is the retracted dwell segment. The plunger advancement segment is divided into three subsegments: pre-injection stroke, injection stroke, and overtravel stroke. The pre-injection subsegment achieves minimum velocity and acceleration at the start of injection. In the injection subsegment, the cam follower acceleration is achieved as rapidly as can Hertz stress permits to increase the injection pressure and to achieve the maximum injection rate. The overtravel subsegment achieves a sharp and clean end of injection. Preferably, this cam causes injection of less than 20 mm.sup.3 of fuel per stroke during the first ten cam angle degrees of cam rotation.

Abstract: A fuel injector train having a variable injection rate includes a fuel injector having a plunger and a plunger biasing device having a predetermined spring rate for controlling the injection rate of the injector. A cam assembly is mounted to impart force through a push rod to a rocker arm which communicates the force of the cam assembly to the fuel injector plunger. In some embodiments, the push rod collapses axially a short distance in response to axial force applied thereto. The push rod has an inherent bias against collapsing that is less than the total bias of the injector biasing device so that during a portion of the injection cycle, part of the force imparted to the push rod collapses the push rod to operate the injector at a reduced rate. In another embodiment, the rocker arm is formed with a closable gap between its first and second ends, and the gap has an inherent bias against closing that is less than the total bias of the fuel injector biasing device.

Abstract: An internal combustion engine is disclosed with a modified four stroke cycle which takes place during a single crankshaft revolution, wherein a reciprocating piston moves through a compression stroke and power expansion stroke, each having a short duration, and an exhaust stroke and intake stroke, each having a relatively long duration compared to the intake and power strokes. The piston stroke distance for each of the aforementioned strokes is equal, defined by, in the preferred embodiment, a first and second cam lobe on the crankshaft, wherein one lobe extends over less of the crankshaft, radial periphery than the other lobe. Preferably, the lobe defining the compression and power strokes act during only 90.degree. of crankshaft revolution while the other lobe act during the remaining 270.degree. of revolution.

Abstract: The present invention relates to a fuel injector for an internal combustion engine, which utilizes a fuel supply control valve and pilot or servo-valve to control the supply and drain of fuel to and from a main fuel chamber. More particularly, the pilot valve separates and isolates the main fuel chamber from the control valve which controls the fuel supply to the main fuel chamber. In this manner, the control valve can operate without interference from the fuel pressure fluctuations created in the main fuel chamber by a reciprocating plunger.

Abstract: A hydromechanical fuel pump system of supplying timing fluid and fuel to high pressure fuel injectors utilizing a hydromechanical fuel control circuit to control the flow of fuel that is withdrawn from a fuel reservoir by a pump and delivered to the fuel injectors which includes a speed signal generator that produces a fuel pressure in a speed signal branch line of the fuel control circuit that is a function of engine rpm, and a torque shaping module that is provided in a fuel delivery branch of the fuel control circuit.

Abstract: A cam follower assembly for mechanically connecting a cam on a camshaft to a push rod assembly is disclosed. The cam follower assembly includes a cam follower link rotatably mounted to a pivot at a first end. At a second end the cam follower link has a substantially semicylindrical recess having a thin axial wall formed at each end of the recess. The cam follower link contacts a push rod adjacent its second end on a surface opposite the surface having the substantially semicylindrical recess. A pinless roller is mounted within the substantially semicylindrical recess and is restrained from axial movement by the thin axial walls. The pinless roller is held in rolling contact with a corresponding cam by imposition by the link of restraining force directly on the cam engaging surface of the roller. The roller may include an annular groove to facilitate lubrication of the cam follower assembly.

Abstract: A fuel injector of the open nozzle type, which is capable of achieving SAC pressures in excess of 30,000 psi during injection. The injector assembly of the preferred embodiments includes a plunger assembly having three plungers arranged to form a hydraulic, variable timing fluid chamber between upper and intermediate plungers and an injection chamber below a lower plunger. To prevent leakage from the injection chamber, the fuel supply passage is provided, along with the injection chamber, within a one-piece injector cup and a predetermined minimum seal length, at commencement of injection, between a land portion of an injection plunger and a wall surface defined by a bore of the injector within which it reciprocates is coordinated to the dimensions of the bore below the land and a predetermined maximum solid fuel height for the injector to result in the minimum seal length being at least one-half of the maximum solid fuel height.

Abstract: A unit injector (2) of the cam actuated, open nozzle type is disclosed in which an extremely compact injector body (4) has a minimum number of internal flow passages (66, 72) designed to reduce the complexity and cost of manufacture of the injector. The invention is characterized by an injector body (4) having an exterior shape designed to form a fuel supply flow path (22) and an isolated fuel drain flow path (24) between the exterior surface of the injector body (4) and the interior surface of the recess (6) in which the injector (2) is designed to be received. This arrangement allows a very simple pattern of radial passages (66, 72) to be formed in the injector body (4) even through the injector (2) is designed to provide scavenging fuel flow previously requiring a much more complex injector design.

Abstract: A unit fuel injector assembly (2, 88) is disclosed for periodically injecting fuel of a variable quantity on a cycle to cycle basis as a function of the pressure of fuel supplied to the injector from a source of fuel (48) and at a variable time during each cycle as a function of the pressure of a timing fluid supplied to the injector from a source of timing fluid (54). A reciprocating plunger assembly (24,146) is received within the injector body (10, 106) and includes an upper plunger section (26, 148), a lower plunger section (28,150) and an intermediate plunger section (30,152) in order to define a variable volume timing chamber (32,138), a variable volume injection chamber (34,162) and a variable volume compensation chamber (36,176).

Abstract: A unit injector (200, 300, 400, 500, 600) of the cam actuated, open nozzle type is disclosed including an extremely compact injector body (202, 302, 402, 502) having a minimum number of internal flow passages and a two piece injector plunger (222, 308, 310, 412, 506, 510, 606, 612) arranged to provide pressure/time metering (all embodiments), scavenging fuel flow (all embodiments), hydraulic timing (all embodiments), fuel cut off (embodiments of FIGS. 1, 3 and 4), wear compensation in advance timing mode (all embodiments) and sharp cut off of fuel injection without high "crush" loads and wear compensation in retard and advance modes (embodiment of FIG. 3).

Abstract: A pressure limiting expandable hydraulic tappet is provided for use in an internal combustion engine to selectively vary timing by altering the effective profile of a camshaft. The tappet expands to extend the drive train between the camshaft and a camshaft operated mechanism by enlarging and filling an internal hydraulic chamber with a noncompressible hydraulic fluid via an inlet port. The fluid is retained in the tappet chamber by a control valve until a predetermined pressure is attained, when the valve control opens to exit the pressurized fluid through the inlet port and maintain said predetermined pressure for the duration of the camshaft stroke. The valve control means is responsive to the hydraulic pressure acting on an area differential within the chamber to overcome a selected bias.

Abstract: This disclosure deals with a mechanism for adjusting the timing of initiation of injection by a fuel injector of an internal combustion engine. The mechanism includes a piston connected to be moved by a drive for the injector, and another piston which is connected to move the plunger of the injector. A timing fluid supply is provided for feeding a timing fluid into a timing chamber formed between the two pistons under selected operating conditions, the timing fluid forming a hydraulic link between the two pistons. The mechanism further includes pressure relief means for releasing a portion of the timing fluid after the termination of injection, the relief means comprising a pressure responsive mechanism.