Gm Global Technolgoy Operations, Inc.

Mark K Krage

Marek T Wlodarczyk

Michel Farid Sultan

Michael J O'Rourke

Frederick R Faxvog

Robert M Storwick

Alexander Meduvsky

Deborah J Vickers

John H Lienesch

The invention introduces the concept of very low cost, fully integrated, large scale planar polymer light guide networks. These networks are intended primarily for automotive applications, including data communication, multiplex, sensor, switch and display networks. However, the concept is also applicable in other areas where the length of the network does not exceed a few meters. The basic idea is to `cut` a thin sheet of clear plastic (polymethylmetacrylate polycarbonate, or polystyrene) into a whole network consisting of optical links, couplers, sensors, etc. . . . In addition to being low cost, planar polymer light guide networks extend the one dimensional geometry of fiber optics into two dimensions, adding tremendous design capability and versatility.

Planar polymer light guide methods and apparatus

A microbend fiber optic pressure sensor includes a short length of sensing fiber comprising a fiber of a transparent dielectric material surrounded by a layer of aluminum or similar metal for which the real part of the complex permittivity is negative over a range of electromagnetic radiation wavelengths. The layer of aluminum is hermetically sealed to the transparent material. The sensing fiber receives light in the range of wavelengths and is subjected to microbends on the dielectric/aluminum boundary by pressure responsive mechanical apparatus for a much greater microbend light loss and therefore greater sensitivity than is obtained with similar sensors using an all glass core/cladding boundary. The sensing fiber may be an aluminum coated single mode fiber with a very small core and a large cladding layer in which the cladding modes are used and the core modes ignored or it may comprise a single glass fiber coated with aluminum. The sensing fiber is used only in the sensing region, with light coupled to one end from a light source and from the other end to a light detector through lower loss multimode optic fibers.

Fiber optic pressure sensor using pressure sensitive fiber different

A microwave method and apparatus for detecting the position of a piston of a pneumatic cylinder. While the piston is being moved by fluid pressure a microwave signal is applied to a cavity defined by the piston and interior of the cylinder and the reflected microwave signal is detected. The reflected microwave signal is processed to determine piston position.

Hydraulic actuator having a microwave antenna

A method of determining the compression ratio of a cylinder of an internal combustion engine. While the engine is being driven by a prime mover a PV curve is developed which is stored in the memory of a microprocessor. The unswept volume of the cylinder is determined by trying various values of unswept volume in the function PV.sup.n =C and determining which value of unswept volume causes the curve developed by this function to best fit the stored curve. Compression ratio is determined after the unswept volume is determined.

Method and apparatus for determining the compression ratio of an engine

A self aligning microbend sensor comprises a tubular housing having internal threads, an expandable insert with external threads loosely threaded into the housing with sufficient tolerance to allow expansion of the insert in response to a parameter being measured while maintaining registration of the threads, and a fiber optic element between the housing and the insert and extending transverse to the threads, such that upon expansion of the insert the fiber optic element experiences microbending due to deformation by the threads.

Self aligning fiber optic microbend sensor

Microwave piston position location

A microwave transmission device for transmitting microwave signals into and out of the combustion chamber of a spark ignited internal combustion engine. The device comprises a circular metallic waveguide that is adapted to encompass a resistor-type spark plug of the engine. An antenna element is disposed in the waveguide which excites it in the TE.sub.11 mode whereby the internal resistor does not substantially attenuate microwave transmission. The waveguide has means for securely attaching it to the exterior of the spark plug such that the waveguide and spark plug have a common longitudinal axis.

Engine testing microwave transmission device

While the crankshaft of an internal combustion engine is rotating, an encoder device produces a reference signal pulse and a series of encoder signal pulses during each crankshaft revolution and a microwave signal of a substantially constant amplitude and frequency is coupled through a microwave probe into the combustion chamber of a selected reference cylinder of the engine. The microwave signal waveform reflected from the reference cylinder combustion chamber while the reference cylinder piston approaches, passes through and moves away from the top dead center position during the compression and power strokes is processed to determine the encoder signal pulse count at which the line of symmetry thereof, the piston top dead center position, occurs. Initial ignition timing angle is then set relative to the encoder signal pulse count corresponding to the piston top dead center position.

Method and apparatus for accurately locating piston top dead center

Magnetic and dielectric properties of a sample are determined by measuring the microwave absorption of the sample. A cavity containing the sample material is coupled to a microwave source and the radiation propagated to the cavity is modulated at a reference frequency. A microphone coupled to the cavity senses the pressure fluctuations resulting from the thermal changes generated in the sample by the absorption of the modulated microwaves and the microphone signal is analyzed at the reference frequency to provide an electrical output which is a measure of the microwave absorption by the sample material. Both dielectric and magnetic properties of the sample can be measured.

Microwave acoustic spectrometer

Apparatus and method for microwave heating and heat recovery in a kiln wherein substances are successively exposed to microwaves to successively raise their temperature and are also successively passed in close proximity to each other to effect radiant heat transfer therebetween for more efficient heating of the substances while the substance from which heat is being transferred is shielded from further exposure to the microwaves to limit the electrical energy usage.

Apparatus and method for microwave heating in a kiln

A radar doppler frequency measuring system is described which times the duration between zero level cross-over of a selected number of doppler cycles. Errors due to spurious zero level cross-overs of the doppler signal due to noise is minimized by a circuit which imposes a time delay after the detection of a zero cross-over before the detection of the next zero cross-over. The time delay is made proportional to the period of the doppler signal to enable the system to operate over a wide doppler frequency bandwidth.

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Royal Oak, MI, United States of America

Mark K Krage