US 2013/0199280 A1 · Thermal Flow Meter

Abstract

An object of the present invention is to provide a thermal type flow rate sensor that offers high sensitivity and improved reliability. A sensor element according to the present invention includes a semiconductor substrate, a cavity portion formed on the semiconductor substrate, a heating resistor formed on the cavity portion via an electrically insulating film, a heating temperature sensor for detecting heating temperature of the heating resistor, and a driving circuit for controlling the heating temperature of the heating resistor using the temperature detected by the heating temperature sensor. The heating temperature sensor comprises temperature-sensitive resistors having resistance values varying according to temperature and disposed upstream and downstream of a direction of flow of a fluid to be measured relative to the heating resistor and on upper and lower sides in a direction perpendicular to the direction of flow of the fluid to be measured relative to the heating resistor.

Claims17

Dependent claims

A thermal flow meter comprising:

a subsidiary passage having an opening portion through which a fluid to be measured is to be drawn in;
and
a sensor element disposed in the subsidiary passage, the sensor element for measuring a flow rate of the fluid to be measured;
wherein the sensor element includes:
a semiconductor substrate;
a cavity portion formed in the semiconductor substrate;
a heating resistor formed on the cavity portion via an electrically insulating film;
a heating temperature sensor for detecting heating temperature of the heating resistor;
and
a driving circuit for controlling the heating temperature of the heating resistor using the temperature detected by the heating temperature sensor;
and
wherein the heating temperature sensor comprises temperature-sensitive resistors having resistance values varying according to temperature and disposed upstream and downstream of a direction of flow of the fluid to be measured relative to the heating resistor and on upper and lower sides in a direction perpendicular to the direction of flow of the fluid to be measured relative to the heating resistor.

9 more elements

A thermal flow meter comprising:

a subsidiary passage having an opening portion through which a fluid to be measured is to be drawn in;
and
a sensor element disposed in the subsidiary passage, the sensor element for measuring a flow rate of the fluid to be measured,
wherein the sensor element includes:
a semiconductor substrate;
a cavity portion formed in the semiconductor substrate;
a heating resistor formed on the cavity portion via an electrically insulating film;
a heating temperature sensor for detecting heating temperature of the heating resistor;
a driving circuit for controlling the heating temperature of the heating resistor using the temperature detected by the heating temperature sensor;
and
a wiring portion connected electrically to the heating resistor;
wherein the heating resistor and the wiring portion have a connecting portion for connecting therebetween, the connecting portion including a throttle portion;
and
wherein the heating temperature sensor is disposed along the throttle portion so as to surround a periphery of the heating resistor.

11 more elements

Dependencies are inferred from the claim text.

Thermal Flow Meter

Life of this patent

Thermal Flow Meter

Life of this patent

Abstract

Claims17