Mass flow controller
A mass flow controller includes a flow meter, a mechanical pressure-regulating valve disposed adjacent to and on an upstream side of the flow meter, and a flow control valve disposed on a downstream side of the flow meter. The mechanical pressure-regulating valve is embedded in a base of the mass flow controller. The mass flow controller also includes a compulsive valve-opening mechanism configured to compulsorily open the mechanical pressure-regulating valve. Thereby, the mass flow controller can instantly recover pressure on the upstream side of the flow meter to its original pressure even in a case where the pressure changes, and can raise measurement accuracy of a flow rate measured by the flow meter.
1. A mass flow controller comprising:
a base;
a flow meter mounted on said base;
a mechanical pressure-regulating valve embedded in said base and disposed adjacent to and on an upstream side of said flow meter; and
a flow control valve mounted on said base and disposed on a downstream side of said flow meter
wherein;
said mechanical pressure-regulating valve comprises;
a pressure-regulating chamber which constitutes a part of a channel of a fluid in said mass flow controller; and
a diaphragm which separates an internal region of said pressure-regulating chamber from an external region of said channel; and
said mechanical pressure-regulating valve is configured to be opened by at least one part of said diaphragm being displaced to a side of said pressure-regulating chamber when pressure of said fluid in said pressure-regulating chamber is lower than a predetermined set pressure.
2. The mass flow controller of claim 1 , wherein:
said flow meter is a pressure type flow meter.
3. The mass flow controller of claim 2 , wherein:
said pressure type flow meter comprises a pressure sensor on the upstream side and a pressure sensor on the downstream side.
4. The mass flow controller of claim 2 , wherein:
said pressure type flow meter comprises a differential pressure sensor configured to measure differential pressure between pressure on the upstream side and pressure on the downstream side.
5. The mass flow controller of claim 1 , further comprising:
a pressure sensor on the upstream side of said mechanical pressure-regulating valve.
6. The mass flow controller of claim 5 , wherein:
said flow meter is a pressure type flow meter.
7. The mass flow controller of claim 6 , wherein:
said pressure type flow meter comprises a pressure sensor on the upstream side and a pressure sensor on the downstream side.
8. The mass flow controller of claim 6 , wherein:
said pressure type flow meter comprises a differential pressure sensor configured to measure differential pressure between pressure on the upstream side and pressure on the downstream side.
9. The mass flow controller of claim 1 , further comprising a valve-opening mechanism configured to open said mechanical pressure-regulating valve by an external operation.
10. A mass flow controller comprising:
a base;
a flow meter mounted on said base;
a flow control valve mounted on said base and disposed on a downstream side of said flow meter;
a mechanical pressure-regulating valve embedded in said base and disposed adjacent to and on an upstream side of said flow meter, said mechanical pressure-regulating valve comprises:
a pressure-regulating chamber which constitutes a part of a channel of a fluid in said mass flow controller; and
a diaphragm which separates an internal region of said pressure-regulating chamber from an external region of said channel;
said mechanical pressure-regulating valve is configured to be opened by at least one part of said diaphragm being displaced to a side of said pressure-regulating chamber when pressure of said fluid in said pressure-regulating chamber is lower than a predetermined set pressure; and
a valve-opening mechanism configured to open said mechanical pressure-regulating valve, said valve-opening mechanism comprises a member configured to displace at least said one part of said diaphragm to said side of said pressure-regulating chamber by an external operation.
11. The mass flow controller of claim 10 , wherein:
an opening when said mechanical pressure-regulating valve is opened by said valve-opening mechanism is larger than a maximum opening of said mechanical pressure-regulating valve at the time of an operation of said mass flow controller.
12. The mass flow controller of claim 10 , wherein:
said valve-opening mechanism is disposed in an outer region of said channel of said fluid.
13. The mass flow controller of claim 12 , wherein:
an opening when said mechanical pressure-regulating valve is opened by said valve-opening mechanism is larger than a maximum opening of said mechanical pressure-regulating valve at the time of an operation of said mass flow controller.
14. The mass flow controller of claim 10 , wherein:
said flow meter is a pressure type flow meter.
15. The mass flow controller of claim 14 , wherein:
said pressure type flow meter comprises a pressure sensor on the upstream side and a pressure sensor on the downstream side.
16. The mass flow controller of claim 14 , wherein:
said pressure type flow meter comprises a differential pressure sensor configured to measure differential pressure between pressure on the upstream side and pressure on the downstream side.
17. The mass flow controller of claim 10 , further comprising:
a pressure sensor on the upstream side of said mechanical pressure-regulating valve.
18. The mass flow controller of claim 17 , wherein:
said flow meter is a pressure type flow meter.
19. The mass flow controller of claim 18 , wherein:
said pressure type flow meter comprises a pressure sensor on the upstream side and a pressure sensor on the downstream side.
20. The mass flow controller of claim 18 , wherein:
said pressure type flow meter comprises a differential pressure sensor configured to measure differential pressure between pressure on the upstream side and pressure on the downstream side.
21. The mass flow controller of claim 10 , further comprising a valve-opening mechanism configured to open said mechanical pressure-regulating valve by an external operation.