US3594546A — Air temperature control apparatus

Claim 1

Independent Claim 110 words

Apparatus adaptEd to regulate the temperature of the air in a space comprising ducting including an electrical heater, circulating means to circulate a portion of the air in the space through said ducting and to thereafter return the portion of air to the space, temperature-sensing means to sense the temperature of the air, and control means responsive to said temperaturesensing means to control the electrical heater, the control means comprising means to derive from an electrical supply voltage a derived voltage having a cyclic waveform consisting of alternately occuring peaks of relatively large amplitude and troughs of relatively small amplitude, and means to apply said derived voltage to the heater.

Claim 2

Dependent Claim 110 words

Apparatus adaptEd to regulate the temperature of the air in a space comprising ducting including an electrical heater, circulating means to circulate a portion of the air in the space through said ducting and to thereafter return the portion of air to the space, temperature-sensing means to sense the temperature of the air, and control means responsive to said temperaturesensing means to control the electrical heater, the control means comprising means to derive from an electrical supply voltage a derived voltage having a cyclic waveform consisting of alternately occuring peaks of relatively large amplitude and troughs of relatively small amplitude, and means to apply said derived voltage to the heater.

Claim 3

Dependent Claim 116 words

Apparatus as claimed in claim 1 wherein the apparatus is adapted to operate from a source of AC electrical power, the said means to derive and apply the said derived voltage to the heater comprise means to connect the element to the source during half cycles of the source waveform of one polarity and to disconnect the element from the source during half cycles of the source waveform of opposite polarity, the said means for connecting and disconnecting effecting said connection and disconnection while the instantaneous power about to be drawn or being drawn from the source by the element is small compared to the mean power drawn by the element while connected to the source.

Claim 4

Dependent Claim 138 words

Apparatus adapted to regulate the temperature of the air in a space comprising ducting including an electrical heater, circulating means to circulate a portion of the air in the space through said ducting and to thereafter return the portion of air to the space, a first temperature sensor to sense the temperature of the air in the space, a second temperature sensor to sense the temperature of the said portion of the air before it is returned to the space and control means responsive to said temperature sensors to control the electrical heater, the control means comprising means to derive from an electrical supply voltage a derived voltage having a cycle voltage waveform consisting of alternately occurring peaks of relatively large amplitude and troughs of relatively small amplitude, and means to apply said derived voltage to the heater.

Claim 5

Dependent Claim 138 words

Apparatus adapted to regulate the temperature of the air in a space comprising ducting including an electrical heater, circulating means to circulate a portion of the air in the space through said ducting and to thereafter return the portion of air to the space, a first temperature sensor to sense the temperature of the air in the space, a second temperature sensor to sense the temperature of the said portion of the air before it is returned to the space and control means responsive to said temperature sensors to control the electrical heater, the control means comprising means to derive from an electrical supply voltage a derived voltage having a cycle voltage waveform consisting of alternately occurring peaks of relatively large amplitude and troughs of relatively small amplitude, and means to apply said derived voltage to the heater.

Claim 6

Dependent Claim 25 words

Apparatus as claimed in claim 3 wherein the first temperature sensor is thermistor, thermostat, through which in operation the current for the electrical heater passes.

Claim 7

Dependent Claim 59 words

Apparatus as claimed in claim 2 wherein the temperature-sensing means comprises a thermistor, a switching transistor being arranged to control the means for connecting and disconnecting, the thermistor, forming part of a biassing circuit for the thermistor, a potentiometer also forming part of the biasing circuit, for adjusting the temperature at which in operation the switching transistor changes state.

Claim 8

Dependent Claim 30 words

Apparatus as claimed in claim 3 wherein the second temperature sensor is positioned to sense the temperature of the portion of air after it has passed through the electrical heater.

Claim 9

Dependent Claim 20 words

Apparatus as claimed in claim 3 comprising means to control the circulating means in response to the first temperature sensor.

Claim 10

Dependent Claim 28 words

Apparatus as claimed in claim 3 comprising means to add air from outside the space to the said portion of air before it passes through the electrical heater.

Claim 11

Dependent Claim 39 words

Apparatus as claimed in claim 1 wherein the control means comprises a unilaterally conductive means adapted to derive said derived voltage from parts of the cycles of an alternating voltage supply, said part cycles all being of one polarity.

Claim 12

Dependent Claim 95 words

Apparatus as claimed in claim 9 wherein the electrical heater comprises first and second heating elements or banks of elements in parallel, means to apply the first-mentioned derived voltage to the first element or bank of elements, the control means also comprising a second unilaterally conductive means adapted to derive a further derived voltage from further like parts of the cycles of the supply voltage, the further part cycles all being of opposite polarity to the firSt-mentioned part cycles, and means to apply the further derived voltage to the second element or bank of elements.

Claim 13

Dependent Claim 54 words

Apparatus as claimed in claim 10 wherein the control means comprises a logic circuit to control the second unilaterally conductive means whereby a further derived voltage is only derived from a given part cycle of opposite polarity when a first-mentioned derived voltage was derived from the immediately preceding said part cycle of one polarity.

Claim 14

Dependent Claim 58 words

Apparatus as claimed in claim 11 wherein the logic circuit comprises a capacitor, means to charge said capacitor by the derived voltage derived from said immediately preceding part cycle, and means to discharge said capacitor during said given part cycle of opposite polarity, thereby providing a control signal to the second unilaterally conductive means to render it conductive.

Claim 15

Dependent Claim 60 words

Apparatus as claimed in claim 9 wherein the first-mentioned unilaterally conductive means comprises a thyristor, means to provide a voltage dependent on the temperature sensed by a said temperature sensor and voltage-sensitive switching to sense said temperature-dependent voltage and to render the thyristor conductive by controlling a voltage at its control terminal when said temperature is below a chosen value.

Claim 16

Dependent Claim 90 words

Apparatus as claimed in claim 13 comprising means to connect the control terminal of the thyristor via a capacitor and a bias resistor across the alternating voltage supply, the thyristor being conductive while said signal is applied to the control terminal at a time during the alternating voltage cycle in which the alternating voltage has a small increasing value and being nonconductive at a time during the said cycle in which the alternating voltage has reverse biased the thyristor, reducing radio interference and/or harmonic distortion in the alternating voltage supply.

Claim 17

Dependent Claim 43 words

Apparatus as claimed in claim 13 wherein the control means comprises a read relay, the voltage-sensitive switching governing the state of the reed relay, and means to control said voltage at the control terminal of the thyristor via contacts of the reed relay.

Claim 18

Dependent Claim 46 words

Apparatus as claimed in claim 13 wherein the said electrical heater constitutes a second heater, the said temperature sensor being the second temperature sensor, another electrical heater constituting the first heater, there being means to control the first heater in response to the first temperature sensor.

Claim 19

Dependent Claim 22 words

Apparatus as claimed in claim 16 comprising means to control the second electrical heater also in response to the first temperatures sensor.

Claim 20

Dependent Claim 22 words

Apparatus as claimed in claim 3 wherein the first temperature sensor comprises a thermostat, and the second temperature sensor comprises a thermistor.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-07-19	1975-01-18	1975-07-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-07-19	1979-01-18	1979-07-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-07-19	1983-01-18	1983-07-20	$7700.00	Window Closed / Lapsed

Air temperature control apparatus

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