Method and apparatus for measuring gas flow using Boyle's law

Claim 3

The method of claim 1 wherein said step (a) of directing is preceded by the step of providing a controllable valve in the path between the inlet and the outlet.

Claim 4

The method of claim 2 wherein said step (a) of directing includes the steps of operating the valve to provide a temporary flow path from the inlet to the enclosed volume and blocking the flow path from the enclosed volume to the outlet.

Claim 5

The method of claim 2 wherein said step (b) of blocking includes the step of operating the valve to provide a temporary flow path from the enclosed volume to the outlet and blocking the flow path from the inlet to the enclosed volume.

Claim 6

The method of claim 1 wherein said step (c) of generating includes the steps of generating a signal representative of the gas pressure in the enclosed volume and sampling the maximum and minimum values of the signal.

Claim 7

The method of claim 1 wherein said step (d) of determining includes the step of applying the signal generated in step (c) to a display device.

Claim 8

A flow meter for determining the flow rate of a gas along a path having an inlet and an outlet, said flow meter comprising: an enclosed volume having a gas entrance; a sensor in communication with the gas pressure within said volume for generating an output signal representative of said gas pressure; valve means coupled to said enclosed volume for enabling gas communication between the gas path inlet and said gas entrance when the valve means is in a first position and between said gas path entrance and the gas path outlet when the valve means is in a second position; accumulator means coupled to said valve means and the gas path inlet for limiting the pressure rise between the gas path inlet and said gas entrance when said valve means is in the second position. processing means coupled to said sensor for converting the sensor signal to a gas flow rate signal; and control means coupled to said valve means and said processing means for enabling said valve means to alternately couple the gas path inlet to said gas entrance and said gas entrance to the gas path outlet over a fixed measurement cycle so that said enclosed volume is alternately filled to a first pressure and relieved to a second pressure, said control means enabling said processing means to generate said gas flow rate signal from the sensor signals representative of the first and second gas pressure values during the measurement cycle.

Claim 9

A flow meter for determining the flow rate of a gas along a path having an inlet and an outlet, said flow meter comprising: an enclosed volume having a gas entrance; a sensor in communication with the gas pressure within said volume for generating an output signal representative of said gas pressure; valve means coupled to said enclosed volume for enabling gas communication between the gas path inlet and said gas entrance when the valve means is in a first position and between said gas path entrance and the gas path outlet when the valve means is in a second position; accumulator means coupled to said valve means and the gas path inlet for limiting the pressure rise between the gas path inlet and said gas entrance when said valve means is in the second position. processing means coupled to said sensor for converting the sensor signal to a gas flow rate signal; and control means coupled to said valve means and said processing means for enabling said valve means to alternately couple the gas path inlet to said gas entrance and said gas entrance to the gas path outlet over a fixed measurement cycle so that said enclosed volume is alternately filled to a first pressure and relieved to a second pressure, said control means enabling said processing means to generate said gas flow rate signal from the sensor signals representative of the first and second gas pressure values during the measurement cycle.

Claim 10

The invention of claim 7 wherein said valve means includes an inlet port coupled to the gas inlet, an outlet port coupled to the gas outlet, and a common port coupled to said gas entrance; and a controllable valve element for alternately coupling said inlet port to said common port and said outlet port to said common port.

Claim 11

The invention of claim 8 wherein said controllable element of said valve means is electrically operable.

Claim 12

The invention of claim 7 wherein said processing means includes an sample and hold circuit having a signal input coupled to said sensor, a signal output for manifesting said gas flow rate signal, and a control input coupled to said control means.

Claim 13

The invention of claim 7 wherein said control means includes a timing circuit for specifying a four phase measurement cycle.

Claim 14

The invention of claim 11 wherein said timing circuit includes a first output terminal for manifesting a control timing signal for said valve means and a second output terminal for manifesting a control timing signal for said processing means.

Claim 15

The invention of claim 7 wherein said processing means generates said gas flow rate signal in accordance with the equation: F=Vb×dP×Fc where Vb is the magnitude of the enclosed volume, dP is the difference between the maximum and the minimum gas pressure values and Fc is the frequency of the measurement cycle.

Claim 18

The invention of claim 14 further including an accumulator volume positioned between said gas inlet and said gas inlet port for limiting the pressure rise when said controllable valve element is in said second position.

Claim 19

The invention of claim 14 further including processing means for converting said pressure sensor signal to a gas flow rate signal.

Claim 20

The invention of claim 16 further including display means coupled to said processing means for displaying the magnitude of the gas flow rate.

Claim 21

A flow meter for determining the flow rate of a gas along a path having an inlet and an outlet, said flow meter comprising: an enclosed volume having a gas entrance; a sensor in communication with the gas pressure within said volume for generating an output signal representative of said gas pressure; valve means for enabling gas communication between the gas path inlet and said gas entrance when the valve means is in a first position and between said gas path entrance and the gas path outlet when the valve means is in a second position, said valve means including an inlet port coupled to the gas inlet, an outlet port coupled to the gas outlet, a common port coupled to said gas entrance, and a controllable valve element for alternately coupling said inlet port to said common port and said outlet port to said common port; processing means coupled to said sensor for converting the sensor signal to a gas flow rate signal; and control means coupled to said valve means and said processing means for enabling said valve means to alternately couple the gas path inlet to said gas entrance and said gas entrance to the gas path outlet over a fixed measurement cycle so that said enclosed volume is alternately filled to a first pressure and evacuated to a second pressure, said control means enabling said processing means to generate said gas flow rate signal from the sensor signals representative of the first and second gas pressure values during the measurement cycle.

Claim 22

A flow meter for determining the flow rate of a gas along a path having an inlet and an outlet, said flow meter comprising: an enclosed volume having a gas entrance; a sensor in communication with the gas pressure within said volume for generating an output signal representative of said gas pressure; valve means for enabling gas communication between the gas path inlet and said gas entrance when the valve means is in a first position and between said gas path entrance and the gas path outlet when the valve means is in a second position, said valve means including an inlet port coupled to the gas inlet, an outlet port coupled to the gas outlet, a common port coupled to said gas entrance, and a controllable valve element for alternately coupling said inlet port to said common port and said outlet port to said common port; processing means coupled to said sensor for converting the sensor signal to a gas flow rate signal; and control means coupled to said valve means and said processing means for enabling said valve means to alternately couple the gas path inlet to said gas entrance and said gas entrance to the gas path outlet over a fixed measurement cycle so that said enclosed volume is alternately filled to a first pressure and evacuated to a second pressure, said control means enabling said processing means to generate said gas flow rate signal from the sensor signals representative of the first and second gas pressure values during the measurement cycle.

Claim 23

The invention of claim 18 wherein said controllable element of said valve means is electrically operable.