US 4,725,001 A · Electronic thermostat employing adaptive cycling

Abstract

Environmental heating/cooling systems are controlled by an interactive microprocessor and have continuous on-time and adaptive cycling modes wherein continuous on-time brings the temperature to a programmed set point and cycling precisely maintains that temperature rather than causing the temperature to oscillate between limits of a dead zone. Minimum pause and on-time intervals of the cycling mode are established in accordance with optimum thermal transfer efficiency and/or equipment limitations. The initial cycle pause interval is a function of the degree transition time (i.e., time required for system to change temperature one degree as measured during continuous on-time mode); the initial cycle on-time interval becomes the established minimum interval. Cycle intervals are modified as necessary to maintain the temperature at the set point with preference given to minimizing the cycle on-time interval. Hence, the cycle on-time interval is decreased to its established minimum before attempting to increase the cycle pause interval; conversely, the pause interval is decreased to its established minimum before increasing the cycle on-time interval. The system is predisposed to remain in the cycling mode whereby predetermined temperature variations from set point, in a direction opposed to system control, initiate a continuous on-time to bring the temperature back to set point, but only after attempting to do so with an additional modified cycle. Degree transition time and initial pause and intervals are re-established during each continuous mode. Cost savings provided by cycling, as compared to continuous, are periodically computed.

Claims126

Dependent claims

An electronic thermostat system for controlling the operation of a temperature-modifying apparatus arranged to modify the temperature of a conditioned space, said apparatus having an on state in which it consumes fuel and an off state in which it does not consume fuel, said thermostat comprising:

set point storage means for storing an operative set point temperature representing the desired temperature in said conditioned space;
measurement means for measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperature;
cycle means for establishing a cycle mode of operation for said system in which said apparatus alternates between a variable on-time interval (in which said apparatus is in said on state) and a variable pause interval (in which said apparatus in in said off state), wherein the total time of the on-time and pause intervals is variable during different cycles;
means for establishing a minimum on-time interval for said cycle mode;
and
cycle modification means responsive to said measured temperature signal, said set point temperature, said minimum on-time interval and the most recent values of said on-time and pause intervals for modifying the on-time and pause intervals to maintain the temperature in said conditioned space substantially at the set point temperature.

3 more elements

An electronic thermostat system for controlling the operation of a temperature modifying apparatus arranged to modify the temperature, in a first sense, of a conditioned space, said apparatus having an on state in which the apparatus consumes fuel and an off state in which the apparatus does not consume fuel, said thermostat comprising:

set point means for storing an operative set point temperature representing the desired temperature in said conditioned space;
measurement means for measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperature;
cycle means for establishing a cycle mode of operation for said system in which said apparatus alternates between a variable on-time interval (in which said apparatus is in said on state) and a variable pause interval (in which said apparatus is in said off state);
means for establishing a minimum on-time interval for said cycle mode, said minimum on-time interval corresponding to the on state time of said apparatus required to achieve substantially optimum efficiency in terms of maximum temperature modification in said conditioned space for a specified fuel consumption;
means for establishing a minimum pause interval for said cycle mode, said minimum pause interval corresponding to sufficient time in the off state to permit said apparatus to dissipate substantially all of the useful residual thermal energy remaining stored in said apparatus after an immediately preceding on-time interval;
cycle modification means responsive to temperature conditions in said conditioned space for maintaining the measured temperature substantially at said set point temperature, said cycle modification means including:
means responsive to differences between said measured temperature and said set point temperature in a second sense, opposite said first sense, for maintaining said on-time interval at said minimum on-time interval while decrementing said pause interval in successive cycles until the measured temperature returns substantially to said set point temperature or until said pause interval becomes equal to said minimum pause interval, which ever occurs first;
and
means responsive to (a) the pause interval being equal to the minimum pause interval, (b) the on-time interval being equal to the minimum on-time interval, and (c) a difference between said measured temperature and said set point temperature in said second sense, for incrementing said on-time interval to reduce said difference;
whereby the minimum on-time interval is the preferred on-time interval for said system and is maintained in spite of temperature modification requirements in said conditioned space unless the pause interval is equal to the minimum pause interval.

7 more elements

A method for controlling the operation of a temperature-modifying apparatus arranged to modify the temperature of a conditioned space, said apparatus having an on state in which it consumes fuel and an off state in which it does not consume fuel, said method comprising the steps of:

(a) storing a set point temperature representing the desired temperature in said conditioned space;
(b) measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperature;
(c) establishing a cycle mode of operation in which said apparatus alternates between a variable on-time interval (in which said apparatus is in said on state) and a variable pause interval (in which said apparatus is in said off state), wherein the total time of the on-time and pause intervals is variable from cycle to cycle;
(d) establishing a minimum on-time interval for said cycle mode;
and
(e) in response to said measured temperature signal, to said set point temperature, to said minimum on-time interval, and to the most recent values of said on-time and pause intervals, modifying the on-time and pause intervals to maintain the temperature in the conditioned space substantially at the set point temperature.

3 more elements

A method for controlling the operation of a temperature modifying apparatus arranged to modify the temperature (in a first sense) of a conditioned space, said apparatus having an on state in which the apparatus consumes fuel and an off state in which the apparatus does not consume fuel, said method comprising the steps of:

(a) storing a set point temperature representing the desired temperature in said conditioned space;
(b) measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperature;
(c) establishing a cycle mode of operation in which said apparatus alternates between a variable on-time interval (in which said apparatus is in the on state) and a variable pause interval (in which said apparatus is in said off state);
(d) establishing a minimum on-time interval for said cycle mode, said minimum on-time interval corresponding to the on state time of said apparatus required to achieve substantially optimum efficiency in terms of maximum temperature modification in said conditioned space for a specified fuel consumption;
(e) establishing a minimum pause interval for said cycle mode, said minimum pause interval corresponding to a sufficient time in the off state to permit the apparatus to dissipate substantially all of the useful residual thermal energy remaining stored in said apparatus after an immediately preceding burn interval;
and
(f) in response to temperature conditions in said conditioned space, maintaining the measured temperature substantially at said set point temperature, said step of maintaining including:
in response to differences between said measured temperature and said set point temperature in a second sense (opposite said first sense), maintaining said on-time interval at said minimum on-time interval while decrementing said pause interval in successive cycles until the measured temperature returns substantially to said set point temperature, or until said pause interval becomes equal to said minimum pause interval, whichever occurs first;
and
in response to (1) the pause interval being equal to the minimum pause interval, (2) the on-time interval being equal to the minimum on-time interval, and (3) a difference between said measured temperature and said set point temperature in said second sense, incrementing said on-time interval to reduce said difference;
whereby the minimum on-time interval is the preferred on-time interval for said system and is maintained in spite of temperature modification requirements in said conditioned space unless the pause interval is equal to the minimum pause interval.

8 more elements

set point means for storing a set point temperature representing the desired temperature in said conditioned space;
measurement means for measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperatures;
cycle means for establishing a cycle mode of operation for said system in which said apparatus alternates between a variable on-time interval (in which said apparatus is in said on state) and a variable pause interval (in which said apparatus is in said off state);
means for establishing a minimum on-time interval for said cycle mode, said minimum on-time interval corresponding to the on state time of said apparatus required to achieve substantially optimum efficiency in terms of maximum temperature modification in said conditioned space for a specified fuel consumption;
means for establishing a minimum pause interval for said cycle mode, said minimum pause interval corresponding to sufficient time in said off state to permit said apparatus to dissipate substantially all of the useful residual thermal energy remaining stored in said apparatus after an immediately preceding on-time interval;
cycle modification means responsive to temperature conditions in said conditioned space for maintaining the measured temperature substantially at said set point, said cycle modification means including:
means responsive to differences between said measured temperature and said set point temperature in said first sense for maintaining said pause interval at said minimum pause interval while decrementing said on-time interval in successive cycles until the measured temperature returns substantially to said set point temperature, or until said on-time interval becomes equal to said minimum on-time interval, whichever occurs first;
and
means responsive to (a) the on-time interval being equal to the minimum on-time interval, (b) the pause interval being equal to the minimum pause interval, and (c) a difference between said measured temperature and said set point temperature in said first sense, for incrementing said pause interval to reduce said difference;
whereby the minimum on-time interval is the preferred on-time interval for said system.

7 more elements

set point storage means for storing a set point temperature representing the desired temperature in said conditioned space;
measurement means for measuring the temperature in said conditioned space and providing a measured temperature signal representing the measured temperature;
cycle means for establishing a cycle mode of operation for said system in which said apparatus alternates between a variable on-time interval (in which said apparatus is in said on state) and a variable pause interval (in which said apparatus is in said off state), wherein the total time of the on-time and pause intervals is variable from cycle to cycle;
means for establishing a minimum on-time interval for said cycle mode;
cycle modification means responsive to said measured temperature for maintaining the temperature in said conditioned space substantially at the set point temperature by modifying the durations of the on-time and pause intervals;
means for establishing a temperature increment transition time for said apparatus corresponding to the time required for said apparatus (in said on state) to change the temperature in said space by a predetermined minimum temperature increment;
and
initial interval determining means responsive to entry of said system into said cycle mode for establishing an initial value of said on-time interval which is significantly less than said temperature increment transition time;
wherein said minimum on-time interval is determined by operation characteristics of said apparatus, and wherein said initial interval determining means includes means for establishing said minimum on-time interval as said initial value of said on-time interval;
and
wherein said initial interval determining means further includes means for establishing an initial pause interval as an inverse function of the temperature increment transition time.

8 more elements

Dependencies are inferred from the claim text.

Electronic thermostat employing adaptive cycling

Life of this patent

Electronic thermostat employing adaptive cycling

Life of this patent

Abstract

Claims126