Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-03-08
2001-10-09
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S494000, C073S114220
Reexamination Certificate
active
06298827
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to control valves for hydraulic devices, and more particularly to a system and method for monitoring and adjusting the actuation of control valves for hydraulic devices.
BACKGROUND ART
In a hydraulically actuated electronically controlled fuel injection system, the injection of fuel into the cylinder is controlled by moving a poppet valve between a high pressure seat and a low pressure seat. The poppet valve member is a portion of an overall control valve that includes an electronic actuator (usually a solenoid) and various body components that include the valve seating surfaces and define the various internal fluid passageways. In part because of the requirement that the various components that make up the control valve be manufactured with realistic tolerances, performance variations in poppet valve opening and closing from one injector to another sometimes occurs. In other words, the activation and deactivation stages of different injectors sometimes diverges substantially from an expected nominal injector performance due at least in part to machining tolerances. In general, it is desirable that a group of injectors installed in a single engine all perform in a uniform and predictable manner. One way of at least partially accomplishing this goal is to ensure that the activation stage for each injector occur in a uniform and expected manner.
The fuel-injection system is operated using an activation profile map that is based upon a predicted nominal injector performance. These activation profiles are a function of different operating conditions, such as speed, load, etc. Each activation profile includes an on-time, an off-time, and a solenoid current magnitude that may vary over the duration between the on-time and the off-time. For instance, the initial current may be a pull in current, and for the remaining duration of the injection event may only be a hold current. When current is sent to an individual injector, it responds by lifting the poppet valve member to close a low pressure seat. When the solenoid current is terminated, the poppet valve member moves back toward its biased position to close a high-pressure seat. In most instances, noise is generated when the poppet valve member impacts both its low-pressure seat and the high-pressure seat.
Since the activation stage characteristics for a nominal injector are known for a given activation profile, the amount an individual injector deviates from nominal can be estimated if the activation stage characteristics of that injector can be determined. Furthermore, if the deviation of an individual injector from the nominal can be quantified, it is conceivable that the injector's performance can be brought more into line with a nominal injector by adjusting the activation profile to compensate for measured deviations due to machining tolerances and other factors.
The present invention is corrected to these and other problems associated with monitoring and adjusting the actuation stage of hydraulically actuated devices, such as fuel injectors.
DISCLOSURE OF THE INVENTION
An electronically controlled hydraulic system includes at least one electronically controlled hydraulic device with a control valve member operably coupled to an electronic actuator. The control valve member impacts a seat when the device is activated and deactivated. An electronic control module is in communication with and capable of controlling the electronic actuator. The electronic control module has an activation profile generator and an activation profile adjuster. A control valve impact sensor is in communication with the electronic control module.
In another aspect, a method of monitoring performance of an electronically controlled hydraulic system includes the initial step of providing at least one electronically controlled hydraulic device having a control valve member operably coupled to an electronic actuator. The control valve member impacts a seat when the device is activated and deactivated. The electronically controlled hydraulic device is then activated according to an activation profile. The seat impacts of the control valve member are then detected. The detected seat impact characteristics are recorded. Finally, the detected seat impact characteristics are compared to expected seat impact characteristics.
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Desai Chetan J.
Fuelberth David L.
Caterpillar Inc.
Liel & McNeil
Moulis Thomas N.
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