Measuring and testing – Volume or rate of flow – Thermal type
Reexamination Certificate
2001-01-30
2003-10-14
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Volume or rate of flow
Thermal type
Reexamination Certificate
active
06631638
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a fluid flow sensor, and more particularly, to a thermal based thin film sensor for determining the velocity of fluid flow.
Thermal based thin film systems are typically used as flow sensors to determine the velocity of gas flowing over the sensor. When fluid flows over the sensor, the flow distorts a set of generated isotherms (i.e., the heat field) which can be at least partially detected by a heat sensor. Typically, a plurality of such fluid flow sensors are located on a surface, such as an air foil, where local velocity, temperature, angle of attack and angle of sideslip of the fluid flow are of critical interest. Furthermore, ground or flight based weather anemometry requires both a direction and a magnitude of air flow. In order to measure both the direction and velocity of the fluid flow, a plurality of fluid flow sensors are typically spaced across the surface of interest.
When the fluid flow reaches higher velocities, the temperature of the heat source must be increased to accurately measure velocity. However, the temperature of the heat source can be increased to only a certain level before the heat source and/or sensor is damaged. When the fluid reaches a speed above that which can be sensed by the thin film sensor, a system of pressure sensors spaced across the surface are typically utilized to determine velocity of the flow. Each pressure sensor is pneumatically connected to the surface by a pressure tap.
In such a system described above, a plurality of sensors and a plurality of pressure sensors must be located across the surface. Each individual pressure and heat sensor must be mounted to the surface and connected to a processor. Each additional sensor also requires additional power. Furthermore, the resultant array of sensors may also create a relatively highly observable feature on the surface with respect to radar and infrared signatures.
Accordingly, there is a need for a small, compact, and efficient flow sensor that can accurately measure a wide range of flow velocities and directions.
SUMMARY OF THE INVENTION
In one embodiment, the present invention is a flow sensor which includes a central heat source and a pair of non-linearly aligned heat sensors such that the sensor, acting alone, can accurately determine the direction and magnitude of the fluid flow. The sensor may include an integral pressure sensor, thereby eliminating the need for separate pressure taps and pressure sensors on the surface and increasing the dynamic range of the sensor (i.e. the range of velocities that can be measured by the sensor). The sensor may also include a substrate temperature sensor for sensing the temperature of the substrate of the sensor. The sensor may also include an isolated fluid temperature sensor to measure the temperature of the surrounding fluid.
In one embodiment, the invention is a flow sensor for determining the velocity and direction of a fluid flow including a die, a heat source located on the die, and a first and a second heat sensor located on the die to detect at least a portion of heat generated by the heat source. The first and second heat sensors and the heat source are arranged in a non-linear orientation.
Other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings.
REFERENCES:
patent: 3677085 (1972-07-01), Hayakawa
patent: 3881181 (1975-04-01), Khajezadeh
patent: 3931736 (1976-01-01), Olmstead
patent: 3988928 (1976-11-01), Edstrom et al.
patent: 3991613 (1976-11-01), Adler et al.
patent: 3995481 (1976-12-01), Djorup
patent: 3996799 (1976-12-01), van Putten
patent: 4024761 (1977-05-01), Djorup
patent: 4089214 (1978-05-01), Egami et al.
patent: 4135396 (1979-01-01), Stanke et al.
patent: 4320655 (1982-03-01), Kammermaier et al.
patent: 4331036 (1982-05-01), Severson et al.
patent: 4332157 (1982-06-01), Zemel et al.
patent: 4345465 (1982-08-01), Gruner et al.
patent: 4391137 (1983-07-01), Kerfoot et al.
patent: 4399698 (1983-08-01), Hiromasa et al.
patent: 4449397 (1984-05-01), Lauterbach
patent: 4462262 (1984-07-01), Kahnke
patent: 4472239 (1984-09-01), Johnson et al.
patent: 4478076 (1984-10-01), Bohrer
patent: 4478077 (1984-10-01), Bohrer et al.
patent: 4498337 (1985-02-01), Gruner
patent: 4501144 (1985-02-01), Higashi et al.
patent: 4542650 (1985-09-01), Renken et al.
patent: 4548077 (1985-10-01), van Putten
patent: 4548078 (1985-10-01), Bohrer et al.
patent: 4555939 (1985-12-01), Bohrer et al.
patent: 4566320 (1986-01-01), Bohrer
patent: 4576050 (1986-03-01), Lambert
patent: 4587843 (1986-05-01), Tokura et al.
patent: 4594889 (1986-06-01), McCarthy
patent: 4624137 (1986-11-01), Johnson et al.
patent: 4637253 (1987-01-01), Sekimura et al.
patent: 4651564 (1987-03-01), Johnson et al.
patent: 4680963 (1987-07-01), Tabata et al.
patent: 4682503 (1987-07-01), Higashi et al.
patent: 4696188 (1987-09-01), Higashi
patent: 4735099 (1988-04-01), Ohta et al.
patent: 4784721 (1988-11-01), Holmen et al.
patent: 4790181 (1988-12-01), Aine
patent: 4843445 (1989-06-01), Stemme
patent: 4870860 (1989-10-01), Ohta et al.
patent: 4885937 (1989-12-01), Tanaka et al.
patent: 4895616 (1990-01-01), Higashi et al.
patent: 4914742 (1990-04-01), Higashi et al.
patent: 4930347 (1990-06-01), Henderson
patent: 4966037 (1990-10-01), Sumner et al.
patent: 5228333 (1993-07-01), Kleinschmidt et al.
patent: 5231877 (1993-08-01), Henderson
patent: 5231878 (1993-08-01), Zanini-Fisher et al.
patent: 5237867 (1993-08-01), Cook, Jr.
patent: 5295389 (1994-03-01), Nagata et al.
patent: 5321983 (1994-06-01), Nagata
patent: 5467649 (1995-11-01), Reihlen et al.
patent: 5663508 (1997-09-01), Sparks
patent: 5852239 (1998-12-01), Sato et al.
patent: 5852308 (1998-12-01), Wood
patent: 5861545 (1999-01-01), Wood
patent: 5869749 (1999-02-01), Bonne et al.
patent: 5892140 (1999-04-01), Wood
patent: 5995209 (1999-11-01), Ohman et al.
patent: 6132083 (2000-10-01), Enala
patent: 019135 (1980-04-01), None
patent: 019135 (1980-04-01), None
patent: 0021291 (1982-03-01), None
patent: 203622 (1986-02-01), None
patent: 0285451 (1988-10-01), None
patent: 0285451 (1988-10-01), None
patent: 490764 (1991-12-01), None
patent: 2171800 (1986-09-01), None
patent: 594722 1 (1959-03-01), None
patent: 61-87385 (1986-05-01), None
patent: 890351 2 (1989-04-01), None
patent: 985076 3 (1998-11-01), None
Masayoshi Esashi, “Micro Flow Sensor and Integrated Magnetic Oxygen Sensor Using It”, 1991 International Conference on Solid State Sensors and Actuators. Jun. 24-27, 1991, San Francisco, CA pp. 34-37.
D. Moser, et al., “Silicon Gas Flow Sensors Using Industrial CMOS and Bipolar IC Technology”,Sensors and Actuators A, 25-27, 1991, pp. 577-581.
G. Wachutka, et al., “Analytical 2D-Model of CMOS MicroMachined Gas Flow Sensors”,Transducers '91. 1991 International Conference of Solid-State Sensors and Actuators, Digest of Technical Papers, Jun. 24-27, 1991, San Francisco, CA, pp. 22-25.
N.R. Swart, et al., “Flow-rate microsensor modelling and optimization using SPICE*”,Sensors and Actuators A, 34, 1992, pp. 109-122.
Scott W. Ma, Ph.D., “Forced covection heat transfer from microstructures”, 1992, 1-88.
Michael J. Moen, et al., “The Effect of Sensor Size and Substrate Properties On the Performance of Flush-Mounted Hot-Film Sensors”,Conference: Proceedings of the Fluids Engineering Conference, Fed—vol. 167,Thermal Anemometry, 1993, pp. 249-261.
U. Dillner, “Thermal modeling of multilayer membranes for sensor applications*”,Sensors and Actuators A, 41-42, 1994, pp. 260-267.
Jin-Biao Huang, et al., “Micro Thermal Shear Stress Sensor with and without Cavity underneath”, Mechanical, Aerospace, and Nuclear Engineering Department, University of California, 6/95, pp. 171-174.
N.T. Nguyen, et al., “Low-cost silicon sensors for mass flow measurement of liquids and gases”,Sensors and Actuators A 49, 1995, pp. 17-20.
Jin-Biao Huang, et al., “Fluidic Shear-Stress Measurement Using Surface-Micromachined Sensors”,IEEE 1995 Region 10 Conference on Microelectronics and VLSI, Hong Kong, Nov., 1995, pp. 57
James Steven D.
Kunik William G.
Lefkowitz Edward
Rosemount Aerospace Inc.
Thompson Jewel V.
LandOfFree
Fluid flow sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluid flow sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid flow sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3114839