TECHNICAL FIELD

The present disclosure relates generally to systems for internal combustion engines, and more particularly, to methods and systems for valve movement detection in a fuel injector of an internal combustion engine.

BACKGROUND

Many internal combustion engines include electronic control units that monitor and operate aspects of the operation of the engine, including the timing and quantity of fuel injection. Engine control units perform these operations with the use of a series of maps, or other programming, stored in memory of the control unit. In conjunction with these maps or programs, control units receive and calculate various items of feedback representative of the operation of the engine. Some engines employ fuel injectors that each have multiple electronically-controlled valves. These valves transition between closed and open positions by selectively energizing actuators, such as solenoids, within each injector. These fuel injector solenoids may be connected to a power supply controlled by the control unit. Some control units may be programmed to detect movement of the valves. For example, when solenoids are deactivated, the control unit may detect movement of a valve member based on free-wheeling current generated in the solenoid (e.g., current induced by movement of a valve member returning to a resting position). The solenoids may be positioned in close proximity to each other to satisfy size constraints of the injector. However, drive currents of such closely-positioned solenoids in a fuel injector may introduce noise or cross-talk. This cross-talk may impair the ability of the control unit to accurately detect aspects of the fuel injector, such as movement of one or more valves.

A method of detecting a valve opening or closing event is disclosed in International Publication No. WO 2018/185314 A1 (the '314 publication) to Sykes. The method described in the '314 publication involves applying a voltage to a solenoid and sampling the current through the solenoid to determine the start of injection. The method of the '314 publication involves applying a continuously-chopped current so that a system for injecting reductant can be used in conjunction with a high voltage power supply. While the method of the '314 publication may be useful in some circumstances, it may not be useful in systems in which two or more solenoids are disposed in close proximity to each other and subject to cross-talk.

The disclosed method and system may solve one or more of the problems set forth above and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem.

SUMMARY

In one aspect, a fuel injection method may include applying a first method current to close a spill valve according to a first method, applying a control valve current to open a control valve, and discontinuing the application of the control valve current to thereby cause the control valve to close. The method may also include applying a second method current to maintain the spill valve closed according to a second method, and detecting a timing of a closing of the control valve while applying the second method current according to the second method, the second method being different than the first method.

In another aspect, a fuel injection method for a mechanically-actuated electronically-controlled fuel injector having a spill valve and a control valve may include applying a chopped spill valve current to close the spill valve according to a first method, applying a control valve current to cause a control valve member of the control valve to move from a first position to a second position, and stopping the application of the control valve current to cause the control valve member to return to the first position from the second position. The method may also include switching the chopped spill valve current to a non-chopped spill valve current to maintain the spill valve closed, according to a second method, and detecting a timing of the return of the control valve member to the first position while applying the non-chopped spill valve current.

In yet another aspect, a fuel injection control system may include at least one power source, a fuel injector including a spill valve including a spill valve solenoid and a control valve including a control valve solenoid, and a controller. The controller may be configured to apply a first method current to the spill valve solenoid according to a first method, apply a control valve current to open a control valve, and discontinue the application of the control valve current to the control valve solenoid to cause the control valve to close. The controller may also be configured to apply a second method current to hold the spill valve closed according to a second method, and detect a timing of a closing of the control valve while applying the second method current, wherein the second method has a lower cross-talk potential than the first method.

