| 摘要 |
PROBLEM TO BE SOLVED: To provide a thermal type flowmeter that has high precision and high reliability, and is simple in structure and more inexpensive.SOLUTION: A thermal type flowmeter comprises a sub-passage where a fluid to be measured is taken in, a sensor element 2 which measures a flow rate of the fluid to be measured in the sub-passage, a temperature detecting element 5 which detects a temperature of the fluid to be measured, a drive circuit 3 which controls a heating temperature of the sensor element 2, and a protection circuit 4 which protects the drive circuit 3 against noise, has a cavity part formed in a substrate of the sensor element 2, a heat generating resistor formed at a thin film part on the cavity part with an electric insulation film interposed, and detects the flow rate from a temperature distribution of the thin film part. The sensor element 2 and drive circuit 3 are mounted on a metallic lead frame 6, the sensor element 2, drive circuit 3 and lead frame 6 are packaged in a chip by sealing the entire periphery with thermosetting resin 9, and one of a chip component 4 for protecting at least the drive circuit 3 and an air temperature detecting element 5 is mounted together in the chip package 1.SELECTED DRAWING: Figure 1 |
