Wide range vacuum gauge
First Claim
1. A device for determining a pressure of gas in an evacuated chamber comprising:
- a cylinder positioned in fluid communication with the evacuated chamber, said cylinder forming a compressed gas chamber;
a reciprocating piston received within said cylinder and mounted for reciprocal movement within said cylinder;
a communication means for selectively fluidly communicating said compressed gas chamber with the evacuated chamber;
a drive means for reciprocating said piston between a retracted position, where said compressed gas chamber communicates with the evacuated chamber, and an extended position where communication between said compressed gas chamber and said evacuated chamber is interrupted;
a determining means for determining when a predetermined pressure differential between said compressed gas chamber and the evacuated chamber is reached; and
a processing means for determining the pressure of the gas within the evacuated chamber based on said predetermined pressure differential and when said predetermined pressure differential is reached.
6 Assignments
0 Petitions
Accused Products
Abstract
A device for determining a pressure of gas in an evacuated chamber including a cylinder positioned in fluid communication with the evacuated chamber with the cylinder forming a compressed gas chamber, a reciprocating piston received within the cylinder and mounted for reciprocal movement therein, a port or valve for providing selective fluid communication between the compressed gas chamber and the evacuated chamber is disclosed. A drive mechanism is provided for reciprocating the piston between a retracted position, where the compressed gas chamber communicates with the evacuated chamber, and an extended position where communication between the compressed gas chamber and the evacuated chamber is interrupted, the position being a position where a pressure transducer determines that a predetermined pressure differential between the chambers has been reached. In the preferred embodiment, a stepper motor is used to measure a distance travelled by the piston at the point where the predetermined pressure differential is reached. Utilizing these parameters, a processor then determines the pressure of the gas within the evacuated chamber.
28 Citations
36 Claims
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1. A device for determining a pressure of gas in an evacuated chamber comprising:
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a cylinder positioned in fluid communication with the evacuated chamber, said cylinder forming a compressed gas chamber; a reciprocating piston received within said cylinder and mounted for reciprocal movement within said cylinder; a communication means for selectively fluidly communicating said compressed gas chamber with the evacuated chamber; a drive means for reciprocating said piston between a retracted position, where said compressed gas chamber communicates with the evacuated chamber, and an extended position where communication between said compressed gas chamber and said evacuated chamber is interrupted; a determining means for determining when a predetermined pressure differential between said compressed gas chamber and the evacuated chamber is reached; and a processing means for determining the pressure of the gas within the evacuated chamber based on said predetermined pressure differential and when said predetermined pressure differential is reached. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A device for determining a pressure of a gas in an evacuated chamber comprising:
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a first cylinder positioned in fluid communication with the evacuated chamber, said first cylinder forming a first compressed gas chamber; a first reciprocating piston received within said first cylinder and mounted for reciprocal movement within said cylinder; a second cylinder formed in said first piston; a second reciprocating piston received within said second cylinder and mounted for reciprocal movement within said cylinder; a communication means for selectively fluidly communicating said compressed gas chamber with the evacuated chamber; a drive means for reciprocating each of said first and second pistons between retracted positions and extended positions; a determining means for determining when a predetermined pressure differential between said compressed gas chamber and the evacuated chamber is reached; a processing means for determining the pressure of the gas within the evacuated chamber based on the predetermined pressure differential and when said predetermined pressure differential is reached. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for determining a pressure of gas in an evacuated chamber comprising:
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providing a cylinder and piston assembly, said cylinder forming a compressed gas chamber selectively communicating with the evacuated chamber; positioning said piston in a retracted position where said compressed gas chamber and the evacuation chamber are in fluid communication with one another; advancing said piston in said cylinder to an extended position, the extended position being that position where a predetermined pressure differential between gas in said compressed gas chamber and the gas in the evacuated chamber is reached; determining the position of said piston to reach the extended position; and determining the pressure of the gas in the evacuated chamber based on said predetermined pressure differential and said position of said piston. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for determining a pressure of a gas in a chamber comprising the steps of:
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compressing a gas of a known volume in a compressed gas chamber having an initial pressure equal to the pressure in the chamber until a predetermined pressure difference across a diaphragm positioned between said chamber and the known volume is reached; and determining the initial pressure of the gas in the known volume based on a geometry of the known volume after compression of the gas in the known volume. - View Dependent Claims (29, 30, 31, 32)
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33. A method for determining a pressure of a gas in an evacuated chamber comprising the steps of:
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compressing a gas of a known volume in a cylinder, said compressing carried out by a solid piston reciprocably received in said cylinder; determining a pressure differential wherein said pressure differential is the difference between the pressure in the evacuated chamber and the cylinder; determining a compression ratio of the gas within said cylinder; and determining the pressure of the gas in said evacuated chamber based on said pressure differential and said compression ratio. - View Dependent Claims (34, 35, 36)
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Specification