Fluid flow sensor
First Claim
Patent Images
1. A flow sensor for determining the speed of a fluid flow comprising:
- a die including a relatively thick substrate portion and a thin diaphragm portion;
a heat source located on said diaphragm portion of said die;
a first and a second heat sensor located on said diaphragm portion of said die to detect at least a portion of heat generated by said heat source, said first and second heat sensors and said heat source being arranged in a non-linear orientation; and
a pressure sensor located on said die for determining the pressure of said fluid flow.
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Abstract
A flow sensor for determining the velocity and direction of a fluid flow including a substrate, a heat source located on the substrate, and a first and a second heat sensor located on the substrate 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.
139 Citations
56 Claims
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1. A flow sensor for determining the speed of a fluid flow comprising:
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a die including a relatively thick substrate portion and a thin diaphragm portion;
a heat source located on said diaphragm portion of said die;
a first and a second heat sensor located on said diaphragm portion of said die to detect at least a portion of heat generated by said heat source, said first and second heat sensors and said heat source being arranged in a non-linear orientation; and
a pressure sensor located on said die for determining the pressure of said fluid flow. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A flow sensor for determining the speed of a fluid flow over said flow sensor comprising:
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a die including a relatively thick substrate portion and a thin diaphragm portion;
a heat source located on said diaphragm portion of said die;
a first and a second heat sensor located on said diaphragm portion of said die to detect at least a portion of heat generated by said heat source, said first heat sensor and said heat source forming a first axis and said second heat sensor and said heat source forming a second axis, said first and said second axes being non-parallel; and
a pressure sensor located on said die for determining the pressure of said fluid flow. 31.The flow sensor of claim 30 wherein said first axis is generally perpendicular to said second axis. - View Dependent Claims (31, 32)
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33. A flow sensor for determining the speed of a fluid flow over said flow sensor comprising:
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a die;
a heat source located on said die, said heat source being connectable to a processor such that said processor can control the temperature of said heat source;
a heat sensor located on said die to detect at least a portion of heat generated by said heat source, said heat source being connectable to said processor to provide an output to said processor; and
a fluid temperature sensor located on said die for determining the upstream temperature of fluid which is substantially unheated by said heat source flowing over said die, said fluid temperature sensor being connectable to said processor to provide an output to said processor such that said processor can determine the speed of said fluid flow.
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- 34. The flow sensor of claim 34 further comprising a pressure sensor located on said die for determining the pressure of said fluid flow.
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36. A flow sensor for determining the speed of a fluid flow over said flow sensor comprising:
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a die;
a heat source located on said die, said heat source being connectable to a processor such that said processor can control the temperature of said heat source;
a heat sensor located on said die to detect at least a portion of heat generated by said heat source, said heat sensor being connectable to said processor to provide an output to said processor;
a pressure sensor located on said die for determining the pressure of said fluid flow; and
a die temperature sensor located on said die for determining the temperature of said die;
said die temperature sensor being connectable to said processor to provide an output to said processor such that said processor can determine the speed of said fluid flow.
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- 37. The flow sensor of claim 37 further comprising a fluid temperature sensor located on said die for detecting the temperature of said fluid.
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39. The flow sensor of claim 39 wherein said piezoelectric element has a thickness of less than about a thickness of said pressure sensor diaphragm.
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41. A flow sensor for determining the speed of a fluid flow comprising:
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a die;
a processor; and
a first, second and third heat sensor located on said die, said first, second and third heat sensors being arranged in a non-linear orientation and coupled to said processor such that said processor can monitor and directly control the temperature of said first, second and third heat sensors by maintaining said first, second and third heat sensors at a generally constant temperature for a predetermined period of time and thereby determine the speed of said fluid flow.
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- 42. The flow sensor of claim 42 wherein said first, second heat and third sensors are resistors, and wherein said processor monitors the power required to maintain said heat sensors at said generally constant temperature, and processes the required power for each heat sensor to determine the velocity of flow over the flow sensor.
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45. A method for determining the speed of a fluid flow comprising the steps of:
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providing a flow sensor comprising a die and a first and a second heat sensor located on said die;
providing a processor;
coupling said first and second heat sensors to said die such that an output of said first and second heat sensors is provided to said processor;
causing a fluid to flow over said flow sensor;
using said processor to maintain said first and second heat sensors at a generally constant temperature for a predetermined period of time as said fluid flows over said sensor; and
monitoring said first and second heat sensors as said fluid flows over said sensor to determine said fluid speed.
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46. The method of claim 46 wherein said monitoring step includes maintaining said first and second heat sensors at a constant temperature.
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47. A method for determining the speed of a fluid flow comprising the steps of:
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providing a flow sensor comprising a die, a heat source located on a diaphragm portion of said die, a first and a second heat sensor located on said diaphragm portion of said die, said first and second heat sensors and said heat source being located in a non-linear orientation, and a pressure sensor located on said die for determining the pressure of said fluid flow;
providing a processor;
coupling said heat source and said first and second heat sensors to said processor such that an output of said first and second heat sensors is provided to said processor;
causing a fluid to flow over said flow sensor;
causing said processor to control the heat output by said heat source and monitor said first and second heat sensors to determine said fluid speed; and
monitoring the pressure measured by said pressure sensor to determine said fluid speed.
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48. A flow sensor comprising:
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a die;
a speed sensor located on said die, said speed sensor being connectable to a processor to provide an output such that said processor can determine the speed of said fluid flow;
a pressure sensor located on said die, said pressure sensor being connectable to a processor to provide an output such that said processor can determine the pressure of said fluid flow; and
a fluid temperature sensor located on said die, said fluid temperature sensor being connectable to said processor to provide an output such that said processor can determine the upstream temperature of said fluid which is substantially unheated by said heat source.
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49. The flow sensor of claim 49 wherein said die includes a relatively thin pressure sensor diaphragm portion, and wherein said pressure sensor includes a portion of piezoresistive material located on said pressure sensor diaphragm portion to detect the pressure of said fluid flow.
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50. The sensor of claim 50 wherein said speed sensor and said fluid temperature sensor each include a resistor.
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51. The sensor of claim 51 wherein said resistor of said speed sensor and said fluid temperature sensor each include material having a non-zero temperature coefficient of resistance formed in a generally serpentine shape.
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52. The flow sensor of claim 52 further comprising a processor coupled to said speed sensor, said fluid temperature sensor and said pressure sensor to determine the speed, temperature, and pressure of said fluid.
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53. The flow sensor of claim 53 wherein said processor maintains said resistor of said speed sensor at a constant temperature for at least part of the time, and said processor can monitor the power required to maintain the resistor at said constant temperature to calculate the speed of said fluid flow.
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54. A flow sensor for determining the speed of a fluid flow comprising:
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a die;
a heat source located on said die;
a first and a second heat sensor located on said die to detect at least a portion of heat generated by said heat source, said first and second heat sensors and said heat source being arranged in a non-linear orientation; and
a protective layer located on top of said heat source and said heat sensors.
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55. A flow sensor for determining the speed of a fluid flow comprising:
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a die including a relatively thick substrate portion and a relatively thin diaphragm portion;
a heat source located on said diaphragm portion of said die;
a first and a second heat sensor located on said diaphragm portion of said die to detect at least a portion of heat generated by said heat source, said first and second heat sensors and said heat source being arranged in a non-linear orientation, wherein each heat sensor is located on an upper surface of said die to detect at least a portion of heat generated by said heat source as carried by said fluid flow; and
a pressure sensor located on said die for determining the pressure of said fluid flow.
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56. A flow sensor for determining the speed of a fluid flow over said flow sensor comprising:
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a die;
a heat source located on said die, said heat source being connectable to a processor such that said processor can control the temperature of said heat source;
a heat sensor located on said die to detect at least a portion of heat generated by said heat source, said heat sensor being connectable to said processor to provide an output to said processor;
a pressure sensor located on said die for determining the pressure of said fluid flow, said pressure sensor including a pressure sensor diaphragm and a piezoelectric element located on said pressure sensor diaphragm such that said piezoelectric element can measure deflection of said pressure sensor diaphragm; and
a die temperature sensor located on said die for determining the temperature of said die, said die temperature sensor being connectable to said processor to provide an output to said processor such that said processor can determine the speed of said fluid flow.
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Specification