Abstract: Diagnostic systems including a pressure sensor, a determiner in communication with the pressure sensor, wherein the determiner is structured to estimate a sonic speed of a fuel based on identification of a fundamental oscillation frequency are disclosed. Also disclosed are diagnostic methods comprising receiving, by a pressure interpreter, a pressure signal, determining, by a determiner in communication with the pressure interpreter, a fundamental frequency of oscillation of the pressure signal, and determining, by the determiner, a sonic speed of a fuel based on the fundamental frequency of oscillation.

Abstract: An injector has an injector body including an injector cavity defining an inner wall and a longitudinal axis, an injector orifice and a plunger slidably disposed within the injector cavity. The plunger has an outer portion and an inner portion at different locations longitudinally along the plunger. The inner portion has a plurality of surface portions including a guiding portion configured to substantially mate with the inner wall of the injector cavity, guide the plunger to slidably move in a direction along the longitudinal axis and substantially prevent the plunger from laterally translating within the injector cavity. The plurality of surface portions also includes a restriction portion configured to form a restrictive cavity between an exterior surface of the inner portion and the inner wall of the injector cavity axially along a length of the inner portion.

Abstract: A fuel injector includes an injection control valve having a stator core that is electrically isolated from surrounding parts such as a stator housing. The stator core includes a first annulated wall having an inner surface, a second annulated wall having an outer surface, a radially extending wall connecting the first and second annulated wall, and a radially extending slot extending through the first annulated wall, the radially extending wall, and the second annulated wall. The stator core may include a limited number of contact points with the stator housing. Alternatively or additionally, an electrically insulating material may be placed between the stator core and the stator housing.

Abstract: A fuel injector has a plurality of injection fuel delivery passages, which transport fuel from a proximate end to an injector cavity near the distal end of the fuel injector, wherein less than a total number of injection fuel delivery passages include an orifice. This configuration provides a reduction in fueling variation from pulse to pulse (multi-pulse) with respect to pulse separation due to pressure variation while allowing a sufficient amount of fuel flow to the injector cavity. Thus, the consistency of Start-Of-Injection (SOI) and opening rate both improve significantly and advantageously. For compactness, the orifices may be positioned in a cover plate used to retain the components of the injection control valve assembly and may further be arranged in an arc segment when viewed along a longitudinal axis.

Abstract: Diagnostic systems including a pressure sensor, a determiner in communication with the pressure sensor, wherein the determiner is structured to estimate a sonic speed of a fuel based on identification of a fundamental oscillation frequency are disclosed. Also disclosed are diagnostic methods comprising receiving, by a pressure interpreter, a pressure signal, determining, by a determiner in communication with the pressure interpreter, a fundamental frequency of oscillation of the pressure signal, and determining, by the determiner, a sonic speed of a fuel based on the fundamental frequency of oscillation.

Abstract: A system and method is provided to analyze an intermediate pressure signal portion between an end of an injection event signal portion and a start of a subsequent injection event signal portion. The analysis is simplified by identifying a plurality of single cycle windows and calculating a single value, such as a mean or a median, for each of the windows. An intermediate portion single value is determined by averaging the single values for each of the windows. The intermediate portion single value may then be used to identify pumping events or leakage errors that occur during the intermediate pressure signal portion that affect further analysis of the intermediate pressure signal portion.

Abstract: A system and method for is provided to determine a fuel flow cutout delay between transmitting a signal to stop a fuel flow to a fuel accumulator of a fuel system and the actual stop of fuel flow to the fuel accumulator. The fuel flow cutout delay is used to determine when pressure data from a sensor associated with the fuel accumulator is unaffected by fuel flow to the fuel accumulator.

Abstract: A method includes determining a stored injection relationship that includes a number of fuel performance parameters. In one form the fuel performance parameters are related to a particular shape, and may be related to a particular operating condition. The method includes determining a fuel performance outcome during a fuel injection event, and updating the stored injection relationship in response to the fuel performance outcome. The fuel performance outcome can be an injected fuel quantity.

Abstract: A system and method for measuring fuel pressure decreases in a fuel accumulator of an internal combustion engine is provided. The system includes the ability to stop a fuel flow to a fuel accumulator of the engine. Pressure signals are transmitted to a control system of the engine until the fuel pressure in the fuel accumulator drops by a predetermined amount, at which time fuel flow is re-enabled. The pressure signals are then analyzed to determine the amount or quantity of fuel delivered by each fuel injector. The system and method maintain engine and emissions performance by limiting the amount of fuel pressure decrease in the fuel accumulator.

Abstract: A fuel injector, comprising an injector body having a longitudinal axis, an injector cavity, an injector orifice at a distal end of the injector cavity, and an inlet conduit configured to supply fuel into the injector cavity, a nozzle valve in the injector cavity, a drain circuit configured to drain fuel from the injector cavity to a low pressure drain, a pilot valve in flow communication with the drain circuit, a chamber housing having an inlet passage to receive fuel from the injector cavity, a return port in flow communication with the pilot valve to drain fuel to the drain circuit, and an abutting surface surrounding the return port, and a control body slidably disposed in the chamber housing, the control body having, a distal end, a proximal end, and a longitudinal axis parallel with the injector body longitudinal axis, a first depression at the distal end defining a first control chamber in which one end of the nozzle valve is guided, a second depression at the proximal end defining a second control cha

Abstract: A system and method for measuring fuel pressure decreases in a fuel accumulator of an internal combustion engine is provided. The system includes the ability to stop a fuel flow to a fuel accumulator of the engine. Pressure signals are transmitted to a control system of the engine until the fuel pressure in the fuel accumulator drops by a predetermined amount, at which time fuel flow is re-enabled. The pressure signals are then analyzed to determine the amount or quantity of fuel delivered by each fuel injector. The system and method maintain engine and emissions performance by limiting the amount of fuel pressure decrease in the fuel accumulator.

Abstract: A system and method for measuring fuel pressure decreases in a fuel accumulator of an internal combustion engine is provided. The system includes the ability to stop a fuel flow to a fuel accumulator of the engine. Pressure signals are transmitted to a control system of the engine until the fuel pressure in the fuel accumulator drops by a predetermined amount, at which time fuel flow is re-enabled. The pressure signals are then analyzed to determine the amount or quantity of fuel delivered by each fuel injector. The system and method maintain engine and emissions performance by limiting the amount of fuel pressure decrease in the fuel accumulator.

Abstract: A system and method for measuring fuel pressure decreases in a fuel accumulator of an internal combustion engine is provided. The system includes the ability to stop a fuel flow to a fuel accumulator of the engine. Pressure signals are transmitted to a control system of the engine until the fuel pressure in the fuel accumulator drops by a predetermined amount, at which time fuel flow is re-enabled. The pressure signals are then analyzed to determine the amount or quantity of fuel delivered by each fuel injector. The system and method maintain engine and emissions performance by limiting the amount of fuel pressure decrease in the fuel accumulator.

Abstract: A system and method is provided to analyze an intermediate pressure signal portion between an end of an injection event signal portion and a start of a subsequent injection event signal portion. The analysis is simplified by identifying a plurality of single cycle windows and calculating a single value, such as a mean or a median, for each of the windows. An intermediate portion single value is determined by averaging the single values for each of the windows. The intermediate portion single value may then be used to identify pumping events or leakage errors that occur during the intermediate pressure signal portion that affect further analysis of the intermediate pressure signal portion.

Abstract: An injector has an injector body including an injector cavity defining an inner wall and a longitudinal axis, an injector orifice and a plunger slidably disposed within the injector cavity. The plunger has an outer portion and an inner portion at different locations longitudinally along the plunger. The inner portion has a plurality of surface portions including a guiding portion configured to substantially mate with the inner wall of the injector cavity, guide the plunger to slidably move in a direction along the longitudinal axis and substantially prevent the plunger from laterally translating within the injector cavity. The plurality of surface portions also includes a restriction portion configured to form a restrictive cavity between an exterior surface of the inner portion and the inner wall of the injector cavity axially along a length of the inner portion.

Abstract: A fuel injector includes an injection control valve having a stator core that is electrically isolated from surrounding parts such as a stator housing. The stator core includes a first annulated wall having an inner surface, a second annulated wall having an outer surface, a radially extending wall connecting the first and second annulated wall, and a radially extending slot extending through the first annulated wall, the radially extending wall, and the second annulated wall. The stator core may include a limited number of contact points with the stator housing. Alternatively or additionally, an electrically insulating material may be placed between the stator core and the stator housing.

Abstract: A system and method is provided to analyze an intermediate pressure signal portion between an end of an injection event signal portion and a start of a subsequent injection event signal portion. The analysis is simplified by identifying a plurality of single cycle windows and calculating a single value, such as a mean or a median, for each of the windows. An intermediate portion single value is determined by averaging the single values for each of the windows. The intermediate portion single value may then be used to identify pumping events or leakage errors that occur during the intermediate pressure signal portion that affect further analysis of the intermediate pressure signal portion.

Abstract: A fuel injector has a plurality of injection fuel delivery passages, which transport fuel from a proximate end to an injector cavity near the distal end of the fuel injector, wherein less than a total number of injection fuel delivery passages include an orifice. This configuration provides a reduction in fueling variation from pulse to pulse (multi-pulse) with respect to pulse separation due to pressure variation while allowing a sufficient amount of fuel flow to the injector cavity. Thus, the consistency of Start-Of-Injection (SOI) and opening rate both improve significantly and advantageously. For compactness, the orifices may be positioned in a cover plate used to retain the components of the injection control valve assembly and may further be arranged in an arc segment when viewed along a longitudinal axis.

Abstract: A system and method for measuring fuel pressure decreases in a fuel accumulator of an internal combustion engine is provided. The system includes the ability to stop a fuel flow to a fuel accumulator of the engine. Pressure signals are transmitted to a control system of the engine until the fuel pressure in the fuel accumulator drops by a predetermined amount, at which time fuel flow is re-enabled. The pressure signals are then analyzed to determine the amount or quantity of fuel delivered by each fuel injector. The system and method maintain engine and emissions performance by limiting the amount of fuel pressure decrease in the fuel accumulator.

Abstract: A fuel pressure relief valve is positioned along a fuel circuit of an internal combustion engine. The pressure relief valve includes a valve body, a first plunger positioned within the valve body, a second plunger positioned within the first plunger, and a valve plug securing the first and second plungers in the valve body. A spring is positioned between the valve plug and the second plunger. Fuel leakage into the pressure relief valve causes the pressure relief valve to lift undesirably in the absence of excessive fuel pressure. The undesirable lifting undesirably affects the operation of the fuel rail and causes wear and shortened life of the pressure relief valve. The first plunger has at least one relief passage or groove located on an exterior surface, relieving the undesirable pressure buildup from a chamber formed between the valve body and the first plunger, eliminating undesirable liftoff events.