Patent Application
20070028697
Embodiments are generally related to the manufacture of in-cylinder pressure sensors, particularly one piece needle and diaphragm systems, and methods. Embodiments are further related to fiber optic dynamic and static pressure measurement systems.
Cylinder pressure is a fundamental factor in determining the operating state of an automotive internal combustions engine. In particular, combustion pressure data can be utilized in advanced engine control and monitoring systems, if available continuously and in real-time. Based on cylinder-specific pressure information, closed-loop control applications have been proposed for power balancing in large-bore natural gas engines, lean burn combustion in passenger cars, or stall control in aircraft engines.
Currently, the widespread use of cylinder pressure based monitoring and control systems has been hampered by one chief factor. The lack of a cost-effective, reliable, and durable combustion pressure sensor has prevented cylinder pressure based detection systems from being widely implemented in commercial and industrial applications.
Piezoelectric-quartz pressure transducers, for example, that have been utilized for decades in engine development and calibration are not well-suited for implementation in production engines. Such devices are subject to electromagnetic interference (EMI) effects, have limited lifetime, and are cost prohibitive. Lower cost piezoceramic devices, for example, such as spark plug washers and boss-type sensors, do not offer high accuracy under all engine conditions, are subject to electrical interference problems, and are prone to large temperature errors. In addition, their durability is not sufficient for use in production engines as a consequence of degrading effects of alloy segregation, selective oxidation, and diffusion.
In contrast to electronic devices, fiber-optic pressure sensors are well suited for applications characterized by high temperatures and high levels of EMI encountered in combustion engines. Such devices, which offer exceptional durability and very low production costs, make fiber optic sensors prime candidates for use in automotive production engines. Due to their miniature size, resistance to high temperatures, and immunity to EMI, such sensors can be combined with existing engine components (e.g., ignition spark plugs, fuel injectors, glow plugs, and so forth).
Such multifunctional devices with embedded pressure sensors can offer numerous advantages for practical and low-cost automotive systems not only from the point of view of sensor expense alone but also on the account of minimum total installation and operational cost. An embedded sensor does not require a separate access point into the engine and the device that the sensor is integrated with can be conventionally installed. No additional cables or connectors are required because the pressure sensor information is sent via the existing cable and connector. Connecting multiple non-embedded sensors to the engine controller represents a complex and costly task in engines with a large number of cylinders.
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The one piece needle and diaphragm assembly provides an alternative to traditional in-cylinder pressure sensing systems, in that they are cheaper to manufacture (e.g. less components by incorporating the needle and housing into one element), require less time to produce by eliminating at least one welding operation, and offer a higher degree of precision which can be more readily tailored to individual customers′needs. In-cylinder pressure sensing allows an unprecedented level of engine performance monitoring, for example, by reducing the total system costs required to achieve stringent new emissions regulations. In addition, fiber optic pressure sensor technology has wide ranging applicability in the civil transportation, aviation, military, and marine industries.
The following summary is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
According to aspects illustrated herein, there is provided a one piece needle and diaphragm system comprising a pressure monitoring diaphragm functioning as a sensor and a needle and housing assembly operatively connected to said diaphragm sensor.
In accordance with another feature, there is provided a one piece needle and diaphragm pressure measurement system comprising an in-cylinder pressure monitoring diaphragm functioning as a sensor and a fiber optic needle and housing assembly operatively connected to said diaphragm sensor.
Other disclosed features of the embodiments include a method of employing a one piece needle and diaphragm system to measure in-cylinder pressure attributes comprising placing a pressure monitoring diaphragm over a one piece needle and housing assembly and then measuring a specified mechanical distance to collect at least one pressure attribute. Next, the pressure monitoring diaphragm is removably attached to the one piece needle and housing assembly by at least one weld. Finally, the pressure monitoring diaphragm is removed from the one piece needle and housing assembly, thus facilitating serviceability and/or replacement.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the present invention and are not intended to limit the scope of the invention.
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The first step in the employment of a one piece needle and diaphragm system is accomplished by placing a pressure monitoring diaphragm over a one piece needle and housing assembly as depicted in block 310.
Once the pressure monitoring diaphragm is positioned into place, a specified mechanical distance is measured between the one piece needle and housing assembly and the diaphragm as described in block 320. Based on the desired pressure attributes to be collected, this distance can be modified or varied.
After measurement, the pressure monitoring diaphragm is removably attached to the one piece needle and housing assembly by at least one weld as depicted in block 330. Lastly, the pressure monitoring diaphragm can be removed from the one piece needle and housing assembly, thus facilitating serviceability and/or replacement as illustrated in block 340.
It will be appreciated that various of the above disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
