A dynamic respiratory control device includes a fast-response valve capable of dynamically imposing multiple resistive loads on the flow of respiratory gas to and from a patient. The resistive loads are applied in response to measured flow rates, patient lung volumes, and/or mouthpiece pressures. The device can precisely constrain tidal breathing, provide precise volumetric control of the airway, and impose multiple specific inspiratory and/or expiratory loading functions to evaluate respiratory function. The device is useful for pulmonary function testing, CT and MRI imaging of the chest, combined CT imaging/interventional radiology, radiotherapy delivery to the thorax/abdomen, and/or as a resistive muscle trainer for weaning patients off ventilators and for respiratory muscle training.

Dynamic respiratory control

A physical quantity sensing device includes an AC voltage generator for generating an AC voltage and a bridge circuit that has first and second input points, to which the AC voltage is applied, and first and second output points connected to a differential amplifier. The bridge circuit includes first and second sensor elements, the impedance of which change with a physical quantity to be measured. The first and second sensor elements have a positive temperature characteristic in which sensitivity increases as temperature rises. The AC voltage generator includes an amplitude limiter which has a negative temperature characteristic that decreases the amplitude of the AC voltage with a rise in temperature, thereby compensating for temperature dependence of a differential voltage produced between the first and second output points.

Physical quantity sensing device with bridge circuit and temperature compensating method

A bi-directional mass air flow sensing device for measuring air flow, comprising a bridge circuit coupled across a voltage potential, wherein the bridge circuit comprises a first side including first and second temperature dependent sensor resistors connected in series and disposed on a thermally insulative substrate window in line with an air flow and arranged such that relative to a first direction of air flow, the first sensor resistor is upstream of the second sensor resistor, and a second side in parallel with the first side and including third and fourth temperature dependent sensor resistors connected in series and disposed on the thermally insulative substrate in line with the air flow such that relative to the first direction of air flow, the third sensor resistor is upstream of the fourth sensor resistor, and a temperature dependent balance resistor connected between the first and second temperature dependent sensor resistors on the first side of the bridge circuit.

Thermally balanced mass air flow sensor

Vorrichtung zur thermischen Massenstrommessung, insbesondere zur Messung der einer Brennkraftmaschine zugefuhrten Luftmasse, umfassend einen temperaturabhangigen elektrisch beheizten Widerstand als Heizelement (RH), einen temperaturabhangigen elektrischen Widerstand als Temperaturfuhler (RT) zur Messung der Temperatur des Massenstroms und zwei Festwiderstande (R2, R3), wobei das Heizelement (RH), der Temperaturfuhler (RT) und die Festwiderstande (R2, R3) in einer Wheatstone-Brucke verschaltet sind, ein weiterer Festwiderstand (R1) mit dem Temperaturfuhler (RT) in Reihe geschaltet ist, das Heizelement (RH) und der Temperaturfuhler (RT) in thermischem Kontakt mit dem stromenden Medium stehen, der Temperaturfuhler (RT) und der Festwiderstand (R1) passen zu dem Heizelement (RH) abgeglichen sind und der Temperaturkoeffizient des Festwiderstands (R1) kleiner als der Temperaturkoeffizient des Temperaturfuhlers (RT) ist.

Vorrichtung zur thermischen massenstrommessung, insbesondere zur messung der einer brennkraftmaschine zugeführten luftmasse

The present invention provides a speed measuring device, a speed measuring method and a vehicle speed measuring system. The device includes a controller and a first electric bridge; the first electricbridge includes a thermo-sensitive component and a voltage dividing module; the thermo-sensitive component and the voltage dividing module are connected in series with each other; two ends of the first electric bridge are respectively connected with the positive pole and negative pole of a power source; the first input end and second input end of the controller are respectively connected with twoends of the voltage dividing module, so that the controller can acquire the voltage of the voltage dividing module; when airflow flows through the thermo-sensitive component, the resistance value ofthe thermo-sensitive component changes with temperature, and the voltage of the voltage dividing module changes with the change of the resistance value of the thermo-sensitive component; and the controller is used for adjusting the temperature of the thermo-sensitive component when a preset compensation condition is satisfied, so as to make the resistance value of the thermo-sensitive component return to a target resistance value, acquiring the voltage variation quantity of the voltage dividing module in the adjustment process, and obtaining the speed of the airflow according to a mapping relation between the voltage variation quantity and airflow speed variation quantity. The device of the invention has the advantages of simplicity in realization and high measurement accuracy.

Speed measuring device, method and vehicle speed measuring system

For determining the air mass flow in the intake pipe of an internal combustion engine by means of an electrical bridge, normally the current flowing through the current measurement resistor when balancing the bridge is evaluated as an indirect measure of the air mass flow. The primary measured quantity for the air mass flow is, however, the power converted at the air flow measurement resistor around which the air flows so that the indirect measurement always includes an error. To reduce this measurement error, the invention utilizes the evaluation of the sum of the voltage across the current measurement resistor and the voltage or a partial-voltage across the air flow measurement resistor as a measure of the air flow.

Temperature compensation in mass flow sensors employing the hot-wire anemometer principle

Temperaturkompensation bei Massenstromsensoren nach dem Prinzip des Hitzdraht-Anemometers

The circuit includes a bridge circuit with an air flow measurement resistance (RL) exposed to the air flow and connected in one bridge arm in series with a current measurement resistor (R1). A temp. compensation resistor (RT) detecting the air temp. is connected in the other bridge arm in series with a fixed resistance (R2). The bridge difference voltage in the bridge diagonal is detected and used to balance the bridge. The measurement voltage resulting from the sum of the voltage across the current measurement resistor and a partial voltage across the air flow measurement resistor is evaluated as a measure of the air flow.

Michael Daetz

Papers

Temperature compensation in mass flow sensors employing the hot-wire anemometer principle

Temperaturkompensation bei Massenstromsensoren nach dem Prinzip des Hitzdraht-Anemometers

Temperature compensation in mass flow sensors after the principle of a hot wire anemometer