MASS FLOW CONTROLLER WITH ENHANCED OPERATING RANGE
First Claim
1. A mass flow controller comprising:
- a sensor tube through which a portion of the gas flows when a gas is flowing through the mass flow controller;
first and second sensing elements coupled to the sensor tube at first and second locations of the sensor tube, respectively; and
a bridge circuit having first, second, third, and fourth nodes, a first predetermined resistive component being connected between the first and second nodes, a second predetermined resistive component being connected between the second and third nodes, the first sensing element being connected between the first and fourth nodes, the second sensing element being connected between the fourth and third nodes, the bridge circuit configured to provide a first signal from the second and fourth nodes and to provide a second signal from the first and third nodes; and
a control portion configured to control a valve position of the mass flow controller responsive to the first signal when the flow of the gas is within a first flow-range-rate and control the valve position of the mass flow controller responsive to the second signal when the flow of the gas is within a second flow-range-rate.
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Accused Products
Abstract
A mass flow controller among other embodiments and method is described. The mass flow controller including a thermal mass flow sensor including at least two sensing elements coupled to a sensor tube of the mass flow controller, the thermal mass flow sensor being designed to provide a first signal indicative of flow of a gas within a first flow-rate-range and a second signal indicative of flow of the gas within a second flow-rate-range; and a control portion figured to control a valve position of the mass flow controller responsive to the first signal when the flow of the gas is within the first flow-rate-range and control the valve position of the mass flow controller responsive to the second signal when the flow of the gas is within a second flow-rate-range.
71 Citations
15 Claims
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1. A mass flow controller comprising:
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a sensor tube through which a portion of the gas flows when a gas is flowing through the mass flow controller; first and second sensing elements coupled to the sensor tube at first and second locations of the sensor tube, respectively; and a bridge circuit having first, second, third, and fourth nodes, a first predetermined resistive component being connected between the first and second nodes, a second predetermined resistive component being connected between the second and third nodes, the first sensing element being connected between the first and fourth nodes, the second sensing element being connected between the fourth and third nodes, the bridge circuit configured to provide a first signal from the second and fourth nodes and to provide a second signal from the first and third nodes; and a control portion configured to control a valve position of the mass flow controller responsive to the first signal when the flow of the gas is within a first flow-range-rate and control the valve position of the mass flow controller responsive to the second signal when the flow of the gas is within a second flow-range-rate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A mass flow controller comprising:
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a thermal mass flow sensor including at least two sensing elements coupled to a sensor tube of the mass flow controller, the thermal mass flow sensor being designed to provide a first signal indicative of flow of a gas within a first flow-rate-range and a second signal indicative of flow of the gas within a second flow-rate-range; and a control portion figured to control a valve position of the mass flow controller responsive to the first signal when the flow of the gas is within the first flow-rate-range and control the valve position of the mass flow controller responsive to the second signal when the flow of the gas is within a second flow-rate-range. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method for operating a mass flow controller, comprising:
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receiving a first input from a second and fourth nodes of a bridge circuit; receiving a second input from a first and third nodes of the bridge circuit, the bridge circuit including a first predetermined resistive component being connected between the first and second nodes and a second predetermined resistive component being connected between the second and third nodes, a first sensing element being connected between a first and fourth nodes of the bridge circuit, and a second sensing element being connected between the fourth and third nodes of the bridge circuit, the first and second sensing elements coupled to a sensor tube at first and second respective locations of the sensor tube through which a portion of a gas flows when the gas is flowing through the mass flow controller; controlling a valve position of the mass flow controller responsive to the first input when the flow of the gas is within a first flow-range-rate; and controlling the valve position of the mass flow controller responsive to the second input when the flow of the gas is within a second flow-range-rate. - View Dependent Claims (15)
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Specification