US3599862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for controlling temperature relative to humidity
Assignee: Fairchild Hiller Corp
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Filing: 1969-04-17
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Granted: 1971-08-17
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Expires: 1989-04-17
Abstract
Abstract Dewpoint control apparatus for maintaining the temperature of a gas within a predetermined zone above the dewpoint of the gas over a preselected temperature range, comprising a relative humidity sensing device, a control means, and a means for heating the gas. A relative humidity value of the gas is selected at which the temperature of the gas will always be within a small predetermined zone above dewpoint over the temperature range of interest. The control means is responsive to the relative humidity sensing device and causes the heating means to vary the temperature of the gas to maintain its relative humidity constant at said preselected value. The impedance of the preferred relative humidity sensing device changes as a function of temperature as well as relative humidity. Accordingly, a bridge circuit incorporating a plurality of thermistors is provided to compensate for such impedance changes by nulling the effect of temperature on the impedance of said relative humidity sensing device.
Inventors
- 👤 William John Hogan
- 👤 Vito Michael Liantonio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:48
CPC Classifications
G; G05; G05D; G05D22/00; G05D22/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
138 words
Apparatus for maintaining a preselected relationship between the temperature of a gas and its relative humidity, comprising means for producing an electrical signal representative of the relative humidity of the gas, said signal producing means including a relative humidity sensor having an electrical impedance which varies as a function of relative humidity and temperature, and means for nullifying the effect of temperature changes on the impedance of said relative humidity sensor, control means responsive to the output of said signal producing means for producing a control voltage which represents the extent to which the relative humidity of the gas differs from a preselected relative humidity for any temperature within a preselected temperature range, and means responsive to said control means for varying the temperature of said gas to cause said relative humidity to approach said preselected relative humidity.
Claim 2
Dependent Claim
138 words
Apparatus for maintaining a preselected relationship between the temperature of a gas and its relative humidity, comprising means for producing an electrical signal representative of the relative humidity of the gas, said signal producing means including a relative humidity sensor having an electrical impedance which varies as a function of relative humidity and temperature, and means for nullifying the effect of temperature changes on the impedance of said relative humidity sensor, control means responsive to the output of said signal producing means for producing a control voltage which represents the extent to which the relative humidity of the gas differs from a preselected relative humidity for any temperature within a preselected temperature range, and means responsive to said control means for varying the temperature of said gas to cause said relative humidity to approach said preselected relative humidity.
Claim 3
Dependent Claim
36 words
Apparatus according to claim 1, wherein said nullifying means includes a temperature sensor having an impedance which varies as a function of temperature, said temperature sensor and relative humidity sensor being connected in a bridge circuit.
Claim 4
Dependent Claim
28 words
Apparatus according to claim 2, including additional impedance means associated with said relative humidity sensor and temperature sensor for adjusting the impedance versus temperature characteristics of said sensors.
Claim 5
Dependent Claim
53 words
Apparatus according to claim 3, wherein said bridge circuit includes two pairs of opposite branches, with temperature sensors in two of said opposite branches, said relative humidity sensor being in one of the other branches and further impedance means in the last of said branches for substantially equalizing said impedance versus temperature characteristics.
Claim 6
Dependent Claim
20 words
Apparatus according to claim 1, including a second relative humidity sensor in parallel with said first named relative humidity sensor.
Claim 7
Dependent Claim
22 words
Apparatus according to claim 1 wherein said temperature varying means includes pneumatic valve means for introducing a gas having a preselected temperature.
Claim 8
Dependent Claim
145 words
Apparatus for maintaining the temperature of a gas within a predetermined zone above the dewpoint of the gas throughout a preselected temperature range, comprising first means for producing a first electrical quantity which is a function of the temperature of said gas, second means for producing a second electrical quantity which is a function of the relative humidity of said gas, said first and second means producing substantially equal quantities at any temperature within said preselected range at a specified relative humidity, said specified relative humidity being selected so that when said gas has said specified relative humidity and is at a temperature within said preselected range, its temperature is within said predetermined zone, comparison means for comparing said first and second quantities, and means responsive to said comparison means for varying the temperature of said gas until said first and second quantities are equal.
Claim 9
Dependent Claim
145 words
Apparatus for maintaining the temperature of a gas within a predetermined zone above the dewpoint of the gas throughout a preselected temperature range, comprising first means for producing a first electrical quantity which is a function of the temperature of said gas, second means for producing a second electrical quantity which is a function of the relative humidity of said gas, said first and second means producing substantially equal quantities at any temperature within said preselected range at a specified relative humidity, said specified relative humidity being selected so that when said gas has said specified relative humidity and is at a temperature within said preselected range, its temperature is within said predetermined zone, comparison means for comparing said first and second quantities, and means responsive to said comparison means for varying the temperature of said gas until said first and second quantities are equal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-16 | 1975-02-15 | 1975-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-16 | 1979-02-15 | 1979-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-16 | 1983-02-15 | 1983-08-17 | $7700.00 | Window Closed / Lapsed |