Abstract: A cam operated open nozzle fuel injector is provided comprising a reciprocating plunger assembly including an outer plunger, an inner plunger and a variable volume timing chamber located between the plungers. A hold down force generating means includes a cam having a hold down cam or ramp portion for maintaining the inner plunger in an innermost position against the inner end of the injector body with a sufficient hold down force during each hold down period throughout injector operation independently of injector train wear. The hold down cam portion operates to move the outer plunger inwardly towards the inner plunger throughout a substantial portion of the hold down period. The hold down cam portion functions to compensate for fuel drainage from the timing chamber so as to maintain a predetermined pressure in the timing chamber corresponding to a desired hold down force.

Abstract: A low inertia, wear-resistant needle valve assembly is provided for an internal combustion engine closed nozzle unit fuel injector. The needle valve assembly includes a needle and spring retainer subassembly made from an advanced structural ceramic, such as silicon nitride. A valve seat subassembly in the injector cup is made from a combination of metal and ceramic. The assembly materials and configuration provide maximum control over the efficiency of the injection event so that the fuel injection event can be terminated quickly, thereby allowing more effective control over exhaust emissions.

Abstract: In a closed-nozzle fuel injector, an injection timing chamber and an injection chamber and a metering plunger/valve moving in a bore between them. A passage from the injection chamber to the injection spray ports is closed by a needle valve. A piston cup seats one end of a needle valve closing spring, the other end being seated on the needle timing spill passageway is opened by a metering plunger and spills fuel from the injector timing chamber to drive an injection needle-valve-spring-loading-piston away from a rest position toward the spring seat on the valve and apply additional force on the valve-closing-spring at the end of injection. In one embodiment, a passageway from the space above the spring-loading piston to a drain line has an orifice therein to maintain pressure atop the piston to hold the valve closed long enough for combustion pressure in the cylinder to drop before return of the spring seat piston to original rest position.

Abstract: A solenoid valve for use in a fuel system includes a valve body with a central core and three interconnected passageways. A spool is disposed within the central core and by means of enlarged and reduced diameter portions controls the flow through the solenoid valve. Solenoid armatures cooperatively control movement of the valve spool which is sized and shaped so as to provide a fuel flow path from an inlet passageway to an outlet passageway when the solenoid valve is in an opened condition. When the spool is shifted to a closed condition, incoming fuel is blocked and a flow path is created from the output passageway to a drain passageway, The drain passageway allows excess fuel in the injector to drain to relieve fuel pressure on the metering plunger. As the spool moves from a closed condition to an opened condition, some fuel flows to the drain passageway. The amount of fuel "loss" depends on the speed of the spool and the size of the drain passageway.

Abstract: A metering system is provided which controls the amount of fuel supplied to the combustion chambers of a multi-cylinder internal combustion engine comprising a fuel pump for supplying fuel at low pressure to a first and a second group of unit fuel injectors, a first solenoid-operated fuel control valve controlling the flow of fuel to the first set of injectors and a second solenoid-operated fuel control valve controlling the flow of fuel to the second set of injectors. The system may also include first and second solenoid-operated timing fluid control valves associated with the first and the second group of injectors, respectively. The injectors are capable of being in the fuel receiving mode, establishing a metering period, and the timing receiving mode, establishing a timing period, at the same time to increase the amount of time available for metering both timing fluid and fuel.

Abstract: A highly wear-resistant plunger assembly for a fuel injector, particularly an open nozzle fuel injector, is provided. The wear-resistant plunger assembly of the present invention includes components formed from wear-resistant materials specifically including, but not limited to, ceramics and metals capable of withstanding the high temperatures and frictional forces produced by prolonged motoring and other potentially adverse engine operating conditions. Different portions of the plunger assembly may be formed from different kinds of wear-resistant materials.

Abstract: A variable displacement high pressure pump having a plurality of high pressure pumping units which receive fuel from a low pressure fuel pump. A rotary cam-driven roller tappet, for producing pumping displacement of the pumping plunger of a respective pumping element, is connected to the pumping plunger by a separated link in a manner permitting the pumping plunger to float relative to the roller tappet during at least a portion of each pumping cycle. As a result, the capacity of the pumping chamber can be limited to an extent that is less than the full stroke achievable by the pumping plunger being retracted to the maximum extent which is permitted by the driving cam.

Abstract: A fuel distributor is provided which is capable of distributing fuel through plural fuel injection lines to the corresponding cylinders of a multicylinder internal combustion engine and which includes a distributor housing including a supply inlet passage, a plurality of fuel injection outlet passages and a plurality of distributor valves for providing sequential periodic fluidic communication between the supply inlet passage and the outlet passages. Each distributor valve, which may be cam-actuated or solenoid-actuated, is adapted to be placed in an open position to define a fuel injection period during which high pressure fuel may flow through the distributor valve to the respective engine cylinder and a closed position blocking fuel flow through the respective fuel injection outlet passage.

Abstract: A compact closed nozzle assembly for a fuel injector is provided which reduces the total length of the injector, minimizes the trapped volume of fuel and, thus, the response time of the injector and eliminates a high pressure joint in the injector body. The compact closed nozzle assembly of the injector includes a nozzle valve element positioned in an injector cavity adjacent injector orifices and operable to be placed in an open position in which fuel may flow a fuel transfer circuit through the injector orifices into the combustion chamber, and a closed position in which fuel flow through the injector orifice is blocked. A nozzle spring, which is shorter and larger in diameter than conventional nozzle springs, biases the nozzle valve element into the closed position.

Abstract: An improved high pressure fuel injector for internal combustion engines of the type having a plunger assembly, with a plurality of plungers, that is mounted within a central bore within the body of the fuel injector for reciprocal movement, the plunger assembly having an upper plunger and a lower plunger mounted for reciprocal motion within the central bore and a variable volume injection chamber in said lower end of the central bore between the injection orifice and a bottom end of the lower plunger. In accordance with a preferred embodiment, the problem of large quantities of air being drawn into the injector from the combustion chamber during the retraction stroke injection stroke is avoided by limiting the return stroke of the lower plunger to a distance that is significantly less than that of the stroke of the upper plunger of the plunger assembly.

Abstract: A fuel system for fuel injectors of an internal combustion engine is provided with a hydromechanical timing valve having a valve body assembly with a barrel and plunger arrangement. The plunger is displaceable within the barrel under the counterbalancing forces of rail fuel pressure (load) and one or more timing valve springs. The relative position of the barrel and plunger determines the effective size of the port through which timing fluid can flow. In accordance a first embodiment, the plunger has a tapered head which covers and uncovers ports in the barrel to a greater or lesser extent, thereby creating a variable flow-through cross section. Alternatively, in accordance with other embodiments, the barrel has ports with slot-like orifices of progressively changing widths which coact with a metering groove on the spool to define a variable flow cross section through which the timing fluid must pass.

Abstract: An electro-hydraulic position-servo device to quickly and accurately position a stop element is provided for use with a positive displacement fuel injection system, wherein a shuttle is used to positively displace pre-metered slugs of fuel to unit injectors. The stop device is operatively associated with a control shaft having at least one helical surface thereon; the stop element and control shaft slidably located within a housing. The housing permits communication between at least one pressurized fluid source and a drain line by way of a chamber within which the control shaft is located. Thus, by simply rotating the control shaft from rotational drive means, the control shaft will assume an axial position determined by the orientation of the helical surface with respect to the supply and drain lines. The device is adjustable by rotation of the shaft to a new position with the re-orientation of the helical surface.

Abstract: A unit fuel injector assembly (88) periodically injects 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 and at a variable time during each cycle as a function of the pressure of the timing fluid supplied to the injector from a source of timing fluid. A reciprocating plunger assembly (146) is received within the injector body (106) and includes an upper plunger section (148), a lower plunger section (150) and an intermediate plunger section (152) in order to define a variable volume timing chamber (138), a variable volume injection chamber (162) and a variable volume compensation chamber (176).

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: The present invention is directed to open nozzle type unit fuel injectors, and more specifically to an improved lower plunger and cup design of an open nozzle unit injector to minimize trapped volume and reduce unburned hydrocarbons in vehicle emissions. The lower plunger includes at least a major and a minor diameter sections with the minor diameter section extending within a bore of said cup at least partially between the fully advanced and retracted positions of the plunger. Moreover, the labyrinth flow area between the cup bore and the minor diameter section of the plunger is designed to reduce the trapped volume of fuel that results in the advanced plunger position while reducing sensitivity to fuel metering in the retracted plunger position. In one embodiment, the cup bore and minor diameter section are stepped. In another, both the bore and the minor diameter section are tapered. In yet another embodiment, only the cup bore is modified.

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 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 positive displacement fuel injection system for use with a combustion engine including a fuel pump (10,10') which forms and delivers pre-metered slugs of fuel and timing fluid to unit injectors (300,300') associated with the engine combustion chambers. The pre-metered slug of timing fluid has a prescribed volume and sets the timing advance for the unit injector. The fuel pump can vary the size of the pre-metered slugs of fuel and timing fluid on a cycle-by-cycle basis.

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).