Thermal flow meter
View Patent ↗A thermal-type flowmeter includes a chip package. The chip package is formed through encapsulation with a resin of a sensor element, a drive circuit, a metal lead frame adapted to have mounted thereon the sensor element and the drive circuit, and a temperature detecting element. The chip package has an exposed structure in which a surface of the sensor element having the diaphragm is exposed. The temperature detecting element is mounted on the lead frame via an electrically conductive member.
1. A thermal-type flowmeter including a sensor element having an exothermic resistor formed on a diaphragm, a temperature detecting element, and a drive circuit electrically connected to the sensor element, comprising:
a chip package formed through encapsulation with a resin of the sensor element, the drive circuit, a metal lead frame adapted to have mounted thereon the sensor element and the drive circuit, and the temperature detecting element, wherein:
the chip package has an exposed structure in which a surface of the sensor element having the diaphragm is exposed, and
the temperature detecting element is mounted on the lead frame via an electrically conductive member.
2. The thermal-type flowmeter according to claim 1 , wherein the chip package is in a shape with a portion thereof, where the temperature detecting element is mounted, being protruded.
3. The thermal-type flowmeter according to claim 2 , wherein a direction of the protrusion of the portion of the chip package is an upstream direction of a flow of the fluid under measurement.
4. The thermal-type flowmeter according to claim 2 , wherein a direction of the protrusion of the portion of the chip package is a direction perpendicular to the flow of
the fluid under measurement.
5. The thermal-type flowmeter according to claim 2 , wherein the chip package has a connection terminal for electrical connection with an outside of the chip package, and is in a shape with the portion thereof being protruded in a direction perpendicular to a direction of the connection terminal.
6. The thermal-type flowmeter according to claim 2 , wherein the chip package has the connection terminal for electrical connection with the outside of the chip package, and is in a shape with the portion thereof being protruded in a direction horizontal to the direction of the connection terminal.
7. The thermal-type flowmeter according to claim 1 , further comprising a sub-flow path that takes in a part of a fluid under measurement passing through a main flow path, wherein the chip package is provided such that a portion on which the sensor element is mounted is disposed in the sub-flow path and a portion on which the temperature detecting element is mounted is disposed in the main flow path.
8. The thermal-type flowmeter according to claim 1 , wherein:
the metal lead frame has a mounting portion on which the drive circuit is mounted and a protruding portion that protrudes from the mounting portion, and
the temperature detecting element is mounted on the protruding portion.
9. The thermal-type flowmeter according to claim 1 , wherein the chip package has a capacitor mounted on the lead frame, the capacitor being encapsulated with the resin.