United Technologies Corporation

Ambac Industries, Inc.

United Technologies Diesel Systems, Inc.

Breed Technologies, Inc.

Breed Automotive Technology, Inc.

Walter J., Jr. Wiegand

Robert H. Bullis

Charles B. Brahm

Harold D. Meyer

James L. Swindal

Robert H Bullis

Walter J Wiegand, Jr

James L Swindal

John A Kimberley

Frank W Gobetz

Charles B Brahm

Harold D Meyer

Robert P Couch

James R Voss

Christopher A Parent

Arthur G Foyt

Robert A DiDomenico

Paul L Provenzano

Robert J Kuhlberg

Thomas M McHugh

Peter P Chenausky

Daniel H Grantham

Robert J Mongeon

Richard E Swarts

Russell G Meyerand, Jr

Clyde O Brown

Mario T Lopiccolo

James P Towey

James W Lennon

Ernest B Manning, Deceased

Jr Wiegand Walter J

A silicon capacitive microsensor which is sensitive to acceleration forces includes a silicon capacitive sensing element 10 comprising three silicon layers 12,16,26 having glass dielectric layers 14,24 between each pair of silicon layers with the middle silicon layer 16 consisting of a proof mass 18 suspended between the two glass dielectric layers 14,24 by a silicon hinge 20 which is connected to a slightly thicker silicon support layer 17 around the periphery (FIG. 3 ) between the glass layers 14,24 (FIG. 1 ). Three metallic bond pads 40,42,44 on the surface 45 of the silicon layers 26,16,12, respectively, are soldered to circuit trace pads 108 on a circuit board 100 which has a glass upper layer 104 and a silicon support layer 102. The thermal expansion coefficient between the glass layer 104 and the sensing element 10 are substantially the same, thereby minimizing thermally induced stresses on the sensing element 10 and minimizing inaccuracies associated therewith. Such direct mounting greatly simplifies the manufacturing process for such sensors. Also, such direct mounting eliminates flying leads thereby allowing the sensing element 10 to be fabricated to much smaller dimensions than that of the prior art.

Sensor having direct-mounted sensing element

A silicon capacitive pressure sensor is disclosed that has a glass dielectric material sputter-deposited onto a silicon substrate of the sensor. After deposition of the bulk dielectric material, the glass is patterned and etched to form a pair of concentric rings. An inner ring is of a circular shape, while the outer ring is of an octagonal shape. As compared to prior art dielectric spacers which are of a single ring of relatively wide thickness, the pair of concentric rings disclosed herein significantly reduce the parasitic capacitance of the glass dielectric material, thereby increasing the sensitivity of the sensor.

Capacitive pressure sensor having a reduced area dielectric spacer

A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are separately fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.

Method of manufacturing silicon pressure sensor having dual elements

A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.

Reference element for high accuracy silicon capacitive pressure sensor

A silicon capacitive pressure sensor is disclosed having a silicon substrate and a silicon diaphragm separated by a glass dielectric spacer. The substrate has an upper surface formed as a mesa which is generally curved in shape, the curvature being concave. Due to manufacturing constraints the mesa upper surface comprises a series of concentric rings that approximate the desired concave shape. The step height and diameter of the rings are such that, at full deflection of the diaphragm, the diaphragm touches the center of the mesa, but not the edges of the individual steps. That is, letting the edges or corners of the steps define a curve, the radius of curvature of the diaphragm is smaller than the radius of curvature of the locus of the step corners.

Capacitive pressure sensor having a substrate with a curved mesa

Manufacturing hinged diaphragms for semiconductor sensors (e.g., accelerometers, pressure transducers, etc.), from a SIMOX wafer (W, FIG. 3 A), in which the internal, insulating, silicon dioxide (SiO.sub.2) layer (3) is used as an etch stop in removing silicon from the underside of the wafer by etching with an appropriately selective etch, producing the reduced thickness, peripheral 'hinge' areas (9; FIG. 3 A to FIG. 3 B), with the exposed part of the silicon dioxide layer being removed in a subsequent etching step (FIG. 3 B to FIG. 3C) using a different, selective etch. This produces a single layer, single-crystal, silicon 'hinge' (9'; FIG. 3C) of uniform, continuous material, enhancing the linearity of diaphragm movement during use and the sensor's sensitivity and accuracy. (See FIG. 4 for methodological steps.) If the top, silicon region of the SIMOX wafer is insufficiently thick for the desired diaphragm thickness, additional layer(s) of epitaxial silicon are grown on the upper side of the silicon crystal until the desired thickness is reached; the same being true for increasing the thickness of the silicon substrate. If having reduced thickness areas for the 'hinge' on both sides of the diaphragm are desired, a SIMOX wafer having an intermediate, silicon dioxide layer on both the 'bottom' and the 'top' of the wafer is used, with each layer serving as an etch stop on its respective side, with the then exposed portions of the silicon dioxide layers thereafter being removed, leaving flanking, alternating, silicon 'hinge' bridges (90a/90b; FIG. 5A-C).

Methodology for manufacturing hinged diaphragms for semiconductor sensors

A micromachined three-plate capacitive accelerometer incorporates a 'sandwich' proof mass formed from two layers that are boron-doped to define hinges attached essentially to the midplane of the proof mass by being placed abutting a bonding interface region at the midplane.

Capacitive accelerometer with mid-plane proof mass

Pressure sensors utilizing capacitance variations to sense pressure variations of the silicon-on-silicon type in which dielectric drift, which occurs in such sensors due to the changing characteristics primarily of the dielectric wall support layer (16) extending up from the silicon substrate (12) between it and the silicon diaphragm (11), is minimized by in turn minimizing the contribution of the dielectric layer to the total capacitance of the sensor (10), reducing the dielectric contribution of the capacitance from, for example, about fifty (50%) percent down to a range of no more than about twenty to twenty-five (20-25%) percent and down typically to sixteen to about ten (16%-10%) percent of the total capacitance or lower. Three exemplary approaches are illustrated, namely, etching the outer edges of the dielectric layer, making the wall(s) it form(s) thinner (FIG. 2); reducing the horizontal thickness of the effective peripheral, lower edge(s) of the silicon diaphragm where it interfaces in contact with the wall(s) formed by the dielectric layer (FIG. 3); and/or reducing the horizontal thickness of the effective peripheral, upper edge(s) of the silicon base or substrate where it interfaces with the wall(s) formed by the dielectric layer (FIUG. 4); and/or a combination of one or more of these approaches or any other approach that minimizes the effective capacitive contribution of the peripheral dielectric layer to the total capacitance of the sensor and hence to long term drift.

Capacitive sensor with minimized dielectric drift

A micromachined three-plate capacitive accelerometer incorporates hinges attached to top and bottom surfaces of the proof mass that are symmetric about X and Y axes and also about diagonal axes; passageways for gas film damping in the fixed members that do not affect the capacitance to any significant degree; and provision for independently selecting two of the parameters sensitivity, capacitance and maximum acceleration.

Capacitive accelerometer with separable damping and sensitivity

The present invention is related to a sight glass(10) that utilizes both reflected light at a glass to air interface(40) as well as the light transmitted through a glass to fluid to glass interface(44) to form a light pattern that is indicative of the true fluid level. By requiring that light always appear in either an 'air' or 'fluid' channel(42,46), any absence of light is assumed due to film coated surfaces or to other abnormal conditions. An absence of light is a signal that maintenance is required.

Optical fluid level sensor

The method and apparatus for generating start of combustion signals associated with the combustion events in a diesel engine (10), and for using such signals to control the timing of fuel delivery to the engine. The combustion event is sensed, as by an electrostatic (230, 330) or optical (130, 430) sensor, and signal conditioning circuitry (32) provides a start-of-combustion (SOC) signal (34) which is directly and precisely indicative of the time of the onset of combustion. The sensors (130, 230) include self-cleaning capabilities (48, 248) for extended operating life on an engine. The sensors may be incorporated in the structure of a glow plug (330, 430). The SOC signal (34) is advantageously supplied to a timing control circuit (26) which delivers a timing control signal (28) to a fuel delivery device, such as the controller (16') associated with a fuel pump (16). The control circuit (26) stores (65) one or more start of combustion values (SOC*) which indicate the desired timing, relative to an engine cycle (24), for the start of the combustion event as a function of speed (25) and load (27). One or more adjustment signals (.DELTA.SOC) are stored (75) and applied (67, 68) as a function of speed and load to adjust the desired signal (SOC*) such that the control signal (28, SOC.sub.c) is corrected for delays. The actual SOC signal (34) is compared (71) with the desired signal (66) to generate an error signal (72) which may be used to finely adjust the stored (75) .DELTA.SOC signal for particular speed and load conditions.

Method and apparatus for controlling fuel injection timing in a

A method and apparatus are provided for controlling the torque or fuel quantity limit to an internal combustion engine such as a diesel engine, at least partly as a function of the sensed level of smoke in the exhaust gas stream of the engine. An open-loop preliminary fuel quantity limit signal is provided as a function of engine speed. The actual smoke level is compared with a smoke limit value for the particular operating condition, and an error signal indicates the sense and possibly the magnitude of any difference. The error signal is the basis of a compensating signal which is added to the open-loop preliminary fuel quantity limit signal such that the resulting fuel quantity limit signal provides for maximum torque without exceeding the smoke limit. The smoke level is obtained by a direct measurement of the particulate level or the like in the exhaust gas stream. An alarm may be provided for indicating when the actual smoke level exceeds some threshold relative to the smoke limit.

Method and apparatus for torque control of an internal combustion engine

Ions are emitted (14) into the gas stream (15) of a gas turbine engine at a point with respect to the gas stream (15), in comparison with the position of an ion-responsive electrostatic probe (24), so that there is a discernible, reliable difference in the ion impingement on the electrostatic probe (24) during normal gas flow (FIGS. 3 and 4) in contrast with that which occurs during the abnormal gas flow attendant a surge (FIG. 5) thereby to provide early and sustained detection of stall and/or surge conditions in the engine, even in the absence of flame from the combustor (17).

Emitted ion surge/stall detection

A method and apparatus for controlling the recirculation of exhaust gas in a diesel engine includes an EGR valve responsive to an EGR control signal for relatively opening and closing a recirculation duct to the passage of exhaust gas therethrough. A sensor provides a signal indicative of the level of particulates in the exhaust gas stream. Control circuitry responsive to various signals indicative of engine operating conditions, including the signal indicative of exhaust gas particulate level, provides an EGR control signal for regulating the EGR valve at least partly as a function of the sensed level of particulates in the exhaust gas stream. The engine operating condition signals typically are indicative of the speed of the engine or fuel injection pump, the engine load, and engine operating temperature. The particulate level signal is preferably provided by electrostatically sensing the passage of packets of charged particles by an electrically-passive, annular electrode positioned in or adjacent to the exhaust gas stream. The control circuitry includes storage of open loop EGR valve control signals as a function of speed and load, as well as particulate objective signals also as a function of speed and load. The sensed exhaust gas particulate level is compared with the appropriate particulate objective signal for the development of an error signal, which error signal is then used in an adaptive manner to adjust the open loop EGR control signal in a direction to diminish the particulate error signal. Such adaptive control of the EGR control signal as a function of the exhaust gas particulate level is further advantageous because a predeterminable relationship exists between exhaust particulate levels and NO.sub.x levels as a function of percent EGR. EGR control may be inhibited by depressed engine temperature.

Method and apparatus for controlling diesel engine exhaust gas

The method and apparatus for generating start of combustion signals associated with the combustion events in a diesel engine, and for using such signals to control the timing of fuel delivery to the engine. The combustion event is sensed, as by an electrostatic or optical sensor, and signal conditioning circuitry provides a start-of-combustion signal which is directly and precisely indicative of the time of the onset of combustion. The sensors include self-cleaning capabilities for extended operating life on an engine. The sensors may be incorporated in the structure of a glow plug. The SOC signal is advantageously supplied to a timing control circuit which delivers a timing control signal to a fuel delivery device, such as the controller associated with a fuel pump. The control circuit stores one or more start of combustion values which indicate the desired timing, relative to an engine cycle, for the start of the combustion event as a function of speed and load. One or more adjustment signals are stored and applied as a function of speed and load to adjust the desired signal such that the control signal is corrected for delays. The actual SOC signal is compared with the desired signal to generate an error signal which may be used to finely adjust the stored .DELTA.SOC signal for particular speed and load conditions.

Growing community of inventors

Avon, CT, United States of America

Robert H Bullis