An apparatus for measuring airflow in an airstream includes a generally planar panel adapted to be placed in the airstream so that air passes over opposite surfaces of the panel. The panel includes at least one slot that extends through the panel. A hot-point element is mounted on one of the panel surfaces adjacent the at least one slot. The at least one slot is configured to permit air passing over the opposite surfaces to pass through the slot and become mixed together. The hot-point element is positioned on the panel so that the mixed air passes over the hot-point element.

An airflow velocity measuring apparatus that includes a fixed-temperature heat generating device. The fixed-temperature heat generating device includes a power supply, a positive-temperature-coefficient thermistor element, a switching element, a comparator element, a first negative-temperature-coefficient thermistor element, a second negative-temperature-coefficient thermistor element, and plural resistor elements. The positive-temperature-coefficient thermistor element is disposed at a measuring point at which the velocity of airflow is measured. The switching element is repeatedly turned ON and OFF so as to cause the positive-temperature-coefficient thermistor element to generate heat at a preset temperature, thereby applying a pulse voltage from the power supply to the positive-temperature-coefficient thermistor element. The airflow velocity measuring apparatus measures the velocity of airflow at the measuring point based on the waveform of this pulse voltage. Adding of a second switch makes it possible to correct measurement errors caused by a rise or a fall in the temperature of subject airflow.

An airflow velocity measuring apparatus that includes a fixed-temperature heat generating device. The fixed-temperature heat generating device includes a power supply, a positive-temperature-coefficient thermistor element, a switching element, a comparator element, a first negative-temperature-coefficient thermistor element, a second negative-temperature-coefficient thermistor element, and plural resistor elements. The positive-temperature-coefficient thermistor element is disposed at a measuring point at which the velocity of airflow is measured. The switching element is repeatedly turned ON and OFF so as to cause the positive-temperature-coefficient thermistor element to generate heat at a preset temperature, thereby applying a pulse voltage from the power supply to the positive-temperature-coefficient thermistor element. The airflow velocity measuring apparatus measures the velocity of airflow at the measuring point based on the waveform of this pulse voltage. Adding of a second switch makes it possible to correct measurement errors caused by a rise or a fall in the temperature of subject airflow.

A sensor of a thermal flow measuring device, as well as the flow measuring device itself. The sensor comprises a sensor platform, which bears at least one measuring sensor element and a heated sensor element. Each of the at least two sensor elements is surrounded by a metal sleeve, which protrudes from the sensor platform. The sensor has a plate-shaped element, which defines a plane, whose axis extends parallel to the axis of at least one of the metal sleeves, wherein the plane is spaced from the sensor platform in the axial direction of the metal sleeve. The metal sleeve with the heated sensor element has a terminal end face and the plate-shaped element is provided along the end face of the metal sleeve with the heated sensor element for flow guidance.

A sensor of a thermal flow measuring device, as well as the flow measuring device itself. The sensor comprises a sensor platform, which bears at least one measuring sensor element and a heated sensor element. Each of the at least two sensor elements is surrounded by a metal sleeve, which protrudes from the sensor platform. The sensor has a plate-shaped element, which defines a plane, whose axis extends parallel to the axis of at least one of the metal sleeves, wherein the plane is spaced from the sensor platform in the axial direction of the metal sleeve. The metal sleeve with the heated sensor element has a terminal end face and the plate-shaped element is provided along the end face of the metal sleeve with the heated sensor element for flow guidance.

An airflow sensor for a heat sink has a first portion having a first electrical point of contact, a second portion have a second electrical point of contact, and a deformable portion made of an electroactive material electrically coupled to the first and second portions. The deformable portion has first electrical properties measured between the first and second electrical points of contact when there is no airflow and the deformable portion is in a first position, and has second electrical properties different than the first electrical properties when a source of airflow blows air against the deformable portion, thereby causing the deformable portion to extend to a second position farther away from the source of airflow than the first position. The airflow sensor can be incorporated into a heat sink for an electronic component.

An airflow sensor for a heat sink has a first portion having a first electrical point of contact, a second portion have a second electrical point of contact, and a deformable portion made of an electroactive material electrically coupled to the first and second portions. The deformable portion has first electrical properties measured between the first and second electrical points of contact when there is no airflow and the deformable portion is in a first position, and has second electrical properties different than the first electrical properties when a source of airflow blows air against the deformable portion, thereby causing the deformable portion to extend to a second position farther away from the source of airflow than the first position. The airflow sensor can be incorporated into a heat sink for an electronic component.

A downhole fluid analysis device includes a piezoelectric helm resonator, a spectroscopy sensor positioned symmetrically with respect to the piezoelectric helm resonator in at least one direction, and a circuit comprising a first terminal and a second terminal electrically coupled to a power supply. The piezoelectric helm resonator and the spectroscopy sensor are electrically coupled in parallel between the first and second terminals. The power supply drives the piezoelectric helm resonator with a voltage of a first polarity and the spectroscopy sensor with a voltage of a second polarity. The circuit includes at least one current flow control device in the circuit configured to prevent both the piezoelectric helm resonator and the spectroscopy sensor from being powered simultaneously.

A downhole fluid analysis device includes a piezoelectric helm resonator, a spectroscopy sensor positioned symmetrically with respect to the piezoelectric helm resonator in at least one direction, and a circuit comprising a first terminal and a second terminal electrically coupled to a power supply. The piezoelectric helm resonator and the spectroscopy sensor are electrically coupled in parallel between the first and second terminals. The power supply drives the piezoelectric helm resonator with a voltage of a first polarity and the spectroscopy sensor with a voltage of a second polarity. The circuit includes at least one current flow control device in the circuit configured to prevent both the piezoelectric helm resonator and the spectroscopy sensor from being powered simultaneously.

Traditional flow sensors include an upstream resistive sensor element, a downstream resistive sensor element and an intervening heater resistive element. To help reduce the size and/or cost of such flow sensor, it is contemplated that the heater resistor may be eliminated. When so provided, the space required for the heater resistive element, as well as the corresponding heater control circuit, may be eliminated. This can reduce the cost, size and complexity of the flow sensor.