Abstract: A wear and scuff-resistant timing plunger for a timing assembly in a unit fuel injector for an internal combustion engine is provided. The timing plunger is formed of a high thermal expansion ceramic with a thermal expansion coefficient greater than 6.times.10.sup.-6 /.degree. C. and a hardness greater than 800 Kg/mm.sup.2, which maintains a desired diametral clearance and efficient plunger function without scuffing or sticking under the axial, tangential and pressure loads encountered in the fuel injector operating environment. Preferred high thermal expansion ceramics are zirconia, alumina-zirconia and alumina.

Abstract: The improved needle controlled common rail fuel system of the present invention includes split common rails serving respective sets of unit injectors. Each unit injector includes a mechanically actuated plunger reciprocally mounted to cyclically create gradual periods of increasing pressure in the common rail during the advancement stroke of the plunger followed by respective periods of decreasing pressure during the plunger's retraction stroke. The fuel injectors include a pressure control valve for controlling the amount of fuel pressurized by the plunger and a needle valve control device including an injection control valve for creating an injection event during a pumping event by controlling the fuel flow to drain so as to control the fuel pressure forces acting on an injector needle valve element. A flow limiting device is provided to limit the fuel flow from a control volume to drain during an injection event thus reducing parasitic losses while maintaining quick valve closing.

Abstract: An injection rate shaping nozzle assembly for a fuel injector is provided which includes a closed nozzle valve element and a rate shaping control device including an injection spill circuit for spilling a portion of the fuel to be injected to produce a predetermined time varying change in the flow rate of fuel injected into a combustion chamber. The spill circuit includes a spill passage integrally formed in the nozzle valve element. The rate shaping control device may include a spill accelerating chamber in formed in the nozzle valve element for creating a rapid increase in the spill flow rate. A spill circuit purge device is provided to remove fuel from the spill circuit and accelerating chamber between each of the injection events thereby ensuring an unimpeded, effective spill fuel flow during the next spill event.

Abstract: The improved needle controlled common rail fuel system of the present invention includes split common rails serving respective sets of injectors and a respective high pressure pump associated with each rail. The high pressure pumps reciprocate to cyclically create gradual periods of increasing pressure in the common rail during the advancement stroke of the plunger followed by respective periods of decreasing pressure during the plunger's retraction stroke. The fuel injectors include an injection control valve and a needle control device for creating an injection event during a pumping event by controlling the fuel flow to drain so as to control the fuel pressure forces acting on an injector needle valve element. A flow limiting device is provided to limit the fuel flow from a control volume to drain during an injection event thus reducing parasitic losses while maintaining quick valve closing. The system also includes an improved fuel injector design including an intensification plunger assembly.

Abstract: An apparatus and method for determining start of fuel injection (SOI), preferably in an open nozzle fuel injection system, comprises means for obtaining injector train load data as a function of crank shaft timing, and a computer for sampling the data, performing a smoothing operation thereon, computing a first derivative of the smoothed injector train load data samples with respect to crank shaft timing, computing a maximum value of the first derivative, computing a predefined fraction of the maximum value of the first derivative, and mapping the predefined fraction of the maximum value of the first derivative to its corresponding crank shaft angle, wherein the corresponding crank shaft angle defines the crank shaft angle, measured in degrees relative to piston top dead center, at which SOI occurs. In an alternative embodiment, the smoothing operation and computation of the first derivative may be combined into a single operation.

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: A sliding friction- and wear-resistant elephant's foot or swivel pad adjusting screw assembly for contacting an actuating member interface in an internal combustion engine is provided to transmit arcuate motion into reciprocal motion. The assembly includes a metal screw element configured to move along an arcuate path in a correspondingly configured socket in a ceramic pad element. A retainer element secures the pad element to the screw element loosely to allow this relative motion. The ceramic pad element includes a planar contact face for contacting a corresponding planar contact surface on an internal combustion engine actuating member, such as a valve, a valve crosshead or a unit fuel injector.

Abstract: A ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.

Abstract: A ball link assembly in which a link member has a semi-spherical cavity formed in each end for rotatably receiving a respective complementary spherical bearing ball formed, preferably, of a ceramic material. Each ball is freely retained by a ball retainer formed of spring steel, the ball retainer extending just over the equator of the ball and mounting to the link by a sideways snap-on action. In one form, the link is designed to accommodate an existing link retainer which is fixed internally of the injector assembly, while in a second form the link assembly is retained by a link retainer which is externally tethered.

Abstract: In accordance with preferred embodiments of the invention, a disc-shaped contact pad of ceramic material is disposed within a recess formed in the top surface of a metal valve crosshead. The pad is held in the recess by a retainer that clips onto the crosshead. The retainer is designed to maintain only a light pressure on only a narrow shoulder of the pad to keep it seated, and does not, itself, experience any dynamic loading. Furthermore, by the provision of a circumferential clearance between the pad and both the wall of the crosshead recess and the retainer, the need for precision machining of the ceramic material can be avoided. Additionally, a reduction of frictional sliding forces imposed on the crosshead, and in turn upon the valves, by the rocker lever is achieved by the ceramic pad, so that resultant frictional side loading is not imposed on adjacent valve components to a significant extent.

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 ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.