| 摘要 |
PURPOSE:To obtain an air flow meter with simple structure which can measure flow rate highly accurately by connecting a primary branch pipe provided with a secondary branch pipe to an air duct for measurement to measure the air flow rate in the secondary branch pipe. CONSTITUTION:A measuring air duct 1a having an orifice is inserted between ducts 1 and connected to them. A primary branch pipe 3 is connected to the outside of the air duct 1a and a secondary branch pipe 4 privided with a hot wire type flow meter 5 is connected to the primary branch pipe 3. By such constitution, the air flow rate in the air duct 1a is proportional to that in the primary branch pipe 3 and the air flow rate in the primary branch pipe 3 is proportional to that in the secondary branch pipe 4. Consequently the air flow rate in the secondary branch pipe 4 is proportional to that in the duct 1, so that the air flow rate in the duct can be measured by measuring the air flow rate in the secondary branch pipe 4 with the heat wire type flow meter 5. |
