EP0436374A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Heater diagnostics and electronic control for a clothes dryer
Assignee: Whirlpool Corp
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Filing: 1990-12-21
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Granted: —
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Expires: 2010-12-21
Abstract
Abstract A control for a clothes dryer with an induction drive motor (18) and an electric resistance heater element (34). A single sense winding (108) is threaded through sensors (102, 104) monitoring drive motor current and heater current, generating an output voltage each time the alternating motor or heater current passes through a zero-crossing. The control monitors the ON/OFF condition of the heater and samples the lagging phase angle of the motor current, and provides an improved means of detecting when the clothes load is dry. The control provides a clothes cooldown period with controlled moisture regain as per the user dryness selection. Numerous heater related diagnostic conditions are monitored at the start of each cycle, or, throughout each cycle, including: heater ground fault detection; 208 or 240 VAC service voltage identification; heater open/short circuit detection; open door detection; heater box thermostat cycling; and restricted air flow detection.
Inventors
- 👤 Larry T. Bashark
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 16:19
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1913; D; D06; D06F; D06F34/00; D06F34/14; D06F34/20; D06F58/00; D06F58/32; D06F58/34; D06F58/36; D06F58/38; G05D23/20; G05D23/24; D06F2101/00; D06F2101/14; D06F2101/16; D06F2103/00; D06F2103/28; D06F2103/32; D06F2103/44; D06F2103/46; D06F2105/00; D06F2105/28; D06F2105/46; D06F2105/56; D06F58/46
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
126 words
A method of detecting temperature of an environment, said method comprising the steps of: disposing a thermistor in said environment; electrically connecting said thermistor and a known circuit resistor to the inverting input of a comparator; alternating connecting either said thermistor or said resistor to the circuit while simultaneously disconnecting said resistor or said thermistor, respectively, in a predetermined sequence; supplying a full wave rectified signal to the non-inverting input of said comparator; monitoring the width of the pulse produced at the output of said comparator at each zero-crossing of the AC line voltage, and processing said information to compare the unknown value of the thermistor resistor to the known value of the circuit resistor by computation of the relative value of said accumulated pulse widths.
Claim 2
Dependent Claim
31 words
The method of claim 1 wherein said thermistor or resistor is activated for two consecutive line half cycles to eliminate bias due to possible voltage asymmetry between consecutive line half cycles.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein said environment consists of the exhaust air line of a clothes dryer.
Claim 4
Dependent Claim
109 words
A temperature measuring device comprising: a comparator having an inverting input, a non-inverting input, and an output; a thermistor, connected to said inverting input of said comparator; a resistor of known resistance also connected to said inverting input of said comparator; means for alternatively supplying a source of DC power to said resistor and to said thermistor; and means for supplying a full wave rectified signal to said non-inverting input of said comparator, such that said output of said comparator is a pulse train wherein the relative width of the pulses is determined by the relative value of said thermistor and said resistor, hence, the temperature of the thermistor.
Claim 5
Dependent Claim
31 words
The method of claim 1 wherein said thermistor or resistor is activated for two consecutive line half cycles to eliminate bias due to possible voltage asymmetry between consecutive line half cycles.
Claim 6
Dependent Claim
107 words
A sensor circuit for determining the type of voltage supplied to an appliance having a three wire connector interconnectable to an AC power source having a first hot side, a neutral side, and a second hot side, said sensor circuit comprising: a means of providing a signal that straddles the AC voltage zero-crossings between the first hot side and the neutral side of said AC source; a sensor means providing a signal indicative of the zero-crossings of the AC current between the first hot side and the second hot side of said AC source; means for comparing the timing of said voltage and said current zero-crossing signals.
Claim 7
Dependent Claim
12 words
The sensor circuit of claim 6 wherein said appliance is a dryer.
Claim 8
Dependent Claim
52 words
The sensor circuit of claim 6 wherein said appliance has a heater connected between said first and second hot sides such that said sensor means senses the current through said heater such as to provide information about the operation or inoperation of said heater in addition to providing said voltage type information.
Claim 9
Dependent Claim
15 words
The sensor circuit of claim 8 wherein said sensor means comprises a core wound sensor.
Claim 10
Dependent Claim
56 words
The sensor circuit of claim 6 wherein said appliance has a motor connected between said first hot side and said neutral side and a sensing means indicative of the zero-crossings of the AC current through said motor such as to provide information about the operation of said motor in addition to providing said voltage type information.
Claim 11
Dependent Claim
17 words
The sensor of claim 10 wherein said motor AC current zero-crossing sensor comprises a core wound sensor.
Claim 12
Dependent Claim
61 words
The sensor circuit of claim 6 wherein said appliance has a heater connected by an electrical line between said first and second hot sides and a motor having a winding connected between said first hot side and said neutral side, said heater and motor AC current zero-cross sensing means further comprising core sensors surrounding, respectively, said heater and said motor winding.
Claim 13
Dependent Claim
17 words
The sensor circuit of claim 7 further comprising a sense winding wound through both said core sensors.
Claim 14
Dependent Claim
68 words
The sensor circuit of claim 13 further comprising current pulse means connected to said sense winding, said current pulse means receiving voltage spikes from said sense winding indicative of said zero crossings, for generating a third signal having current pulses corresponding to said voltage spikes, such the timing relationship between said pulses is indicative of the phase relationship between said first and second sides of said AC source.
Claim 15
Dependent Claim
30 words
The sensor circuit of claim 14 further comprising microcomputer means for generating a digital record indicative of said timing relationship between said first and second sides of said AC source.
Claim 16
Dependent Claim
28 words
The sensor circuit of claim 6 further comprising means for controlling the operation of said heater in response to detection of the type of said AC voltage source.
Claim 17
Dependent Claim
28 words
The sensor circuit of claim 6 further comprising means for controlling the operation of said appliance in response to detection of the type of said AC voltage source.
Claim 18
Dependent Claim
28 words
The sensor circuit of claim 6 further comprising means for generating a record indicative of said timing relationship between said first and second sides of said AC source.
Claim 19
Dependent Claim
82 words
The sensor circuit of claim 6 wherein said appliance has a motor having at least one motor winding connected between said first hot side, and said neutral side, said sensor circuit further comprising: third sensor means providing a third signal indicative of zero crossings of the power through said motor winding; and means for comparing the timing of said first and third signals such as to determine the phase angle shift of said motor winding AC power relative to said power source.
Claim 20
Dependent Claim
54 words
The sensor circuit of claim 20 wherein said appliance further has a heater connected between said first and second hot sides such that said second sensor means senses the current through said heater such as to provide information about the operation or inoperation of said heater in addition to providing said voltage type information.
Claim 21
Dependent Claim
51 words
The sensor circuit of claim 20 wherein said second sensor means comprises a first core wound about the line to said heater and said third sensor means comprises second core wound about said motor winding, said sensor circuit further comprising a sense winding wound through both said first and second cores.
Claim 22
Independent Claim
84 words
A method of determining the type of AC voltage supplied to an appliance having a three wire connector interconnectable to any AC voltage source having a first hot side, a second hot side, and a neutral side, said method comprising the steps of: sensing the zero crossings of the AC power between the first and second hot sides; sensing the zero crossings of the AC power between the first hot side and the neutral side; and comparing the relative timing between said zero crossings.
Claim 23
Dependent Claim
31 words
The method of claim 22 wherein at least one of said zero crossings is measured by using a core wound about an electrical line between two sides of said AC source.
Claim 24
Dependent Claim
56 words
The method of claim 22 wherein at least one of said steps of sensing zero crossings comprises sensing zero crossings of the AC power through a component of said appliance such that at least one step provides, in addition to information about the type of AC source, information about the operation or inoperation of said device.
Claim 25
Dependent Claim
45 words
The method of claim 24 wherein said appliance is a dryer and said component is a heater connected between the first and second hot side such that said step of sensing the zero crossings comprises sensing zero crossing of the power through the said heater.
Claim 26
Dependent Claim
65 words
The method of claim 22 further comprising the steps of: providing a record indicative of the detection of a 240 VAC power course if said timing of said zero crossings is substantially less than 45, electrical degrees different; and providing a record indicative of the detection of a 208 VAC power source if said timing of said zero crossings is approximately 90 electrical degrees apart.
Claim 27
Dependent Claim
66 words
A sensor circuit for determining if a heater coil line is receiving power, said sensor circuit comprising: a core winding wound about said heater coil line; a sense winding wound through said core winding, said sense winding providing a voltage spike indicating zero crossings of current through the heater, such that the absence of said voltage spikes indicative of the absence of current through said heater.
Claim 28
Dependent Claim
26 words
The sensor circuit of claim 27 further comprising sensor means for monitoring the current through the winding of a motor used in conjunction with said heater.
Claim 29
Dependent Claim
48 words
The sensor circuit of claim 28 wherein said means for monitoring comprises a second core wound a said motor winding, said sense winding being would through said second core such as to provide a second spike indicating zero crossings of the current through said winding of said motor.
Claim 30
Dependent Claim
44 words
The sensor circuit of claim 29 further comprising current pulse means connected to said sense winding, said current pulse means receiving voltage spikes from said sense winding indicative of said zero crossings and generating a signal having current pulses corresponding to said voltage spikes.
Claim 31
Dependent Claim
24 words
The sensor circuit of claim 27 further comprising microcomputer means for generating a record indicative of the existence or non-existence of said voltage spikes.
Claim 32
Dependent Claim
21 words
The sensor circuit of claim 27 further comprising thermometer means for detecting the temperature of an environment heated by said heater.
Claim 33
Dependent Claim
24 words
The sensor circuit of claim 32 further comprising means for controlling said heater in response to the said voltage spike and said temperature information.
Claim 34
Dependent Claim
23 words
The sensor circuit of claim 32 wherein said thermometer means comprises: means for providing a pulse representation of the temperature of said environment.
Claim 35
Dependent Claim
96 words
The sensor circuit of claim 34 wherein said thermometer means further comprises: a comparator having an inverting input, a non-inverting input, and an output; a thermistor; connected to said inverting input of said comparator; a resistor of known resistance connected in parallel with said thermistor to said inverting input of said comparator; means for alternating supplying a source of DC power to said resistor and to said thermistor; and to said non-inverting input of said comparator, such that said output of said comparator supplies a pulse of a width determined by the temperature of said thermistor.
Claim 36
Dependent Claim
44 words
The sensor circuit of claim 35 further comprising current pulse means connected to said sense winding, said current pulse means receiving voltage spikes from said sense winding indicative of said zero crossings and generating a signal having current pulses corresponding to said voltage spikes.
Claim 37
Dependent Claim
38 words
The sensor circuit of claim 36 further comprising microcomputer means for generating a first record indicative of the existence or non-existence of said voltage spikes and a second record indicative of the temperature measured by said thermometer means.
Claim 38
Independent Claim
101 words
A method of drying clothes in a clothes dryer having a rotating drum, a motor driving said rotating drum, air inlet into said drum, a heater disposed along said air inlet, an air outlet from said drum and a source of AC power for said heater and said motor, said method comprising the steps of: measuring the temperature down stream of said heater; providing a first representation of said temperature; detecting the operational status of said heater; providing a second representation of said operational status; and automatically controlling the operation of said dryer in response to said first and second representations.
Claim 39
Dependent Claim
24 words
The method of claim 38 wherein said step of measuring the temperature downstream of said heater comprises measuring the temperature along said exhaust line.
Claim 40
Dependent Claim
90 words
The method of claim 38 wherein said step of measuring said temperature comprises the steps of: disposing a thermistor in said environment disposing a known resistor electrically in parallel with said thermistor; alternating passing C current through said known resistance and through said thermistor into the inverting input of a comparator; supplying a full wave rectified signal to the non-inverting input of said comparator; and monitoring the width of the volt pulse produced at the output of said comparator, said width being proportional to the temperature measured by said thermistor.
Claim 41
Dependent Claim
57 words
The method of claim 38 wherein said step of detecting the operating status of said heater comprises: disposing a core winding about the power line to said heater; and passing a sense winding through said core winding such that the AC power in said lines induces voltage spikes in said sense winding when said heater in operational.
Claim 42
Dependent Claim
49 words
The method of claim 39 wherein said step of automatically controlling the operation of said dryer in response to said first and second representations comprises: determining the length of the cool down period for said dryer in response to a detection of a predetermined change in said first representation.
Claim 43
Dependent Claim
23 words
The method of claim 42 wherein said cool down period is selected between a predetermined minimum and a predetermined maximum period of time.
Claim 44
Dependent Claim
23 words
The method of claim 42 wherein said predetermined change in said first representation comprises: detecting that said exhaust temperature is no longer decreasing.
Claim 45
Dependent Claim
96 words
A cool down control for controlling a clothes dryer having a rotating drum for holding a clothes load, a motor driving said rotating drum, an air inlet into said drum, a heater disposed along said air inlet, an air outlet from said drum, and a source of AC power for said heater and said motor, said control comprising: means for measuring the temperature along said exhaust line during the cool down of said clothes load; and means for automatically determining the period of cool down for said clothes load in response to changes in said temperature.
Claim 46
Dependent Claim
30 words
The cool down control of claim 45 wherein said means for determining the cool down period selects a period between a predetermined maximum and a predetermined minimum period of time.
Claim 47
Dependent Claim
51 words
The cool down control of claim 45 wherein said means for determining the cool down period selects a period for response determined by the time at which the temperature measured by said means for measuring is no longer decreasing by more than a predetermined amount over a preset length of time.
Claim 48
Dependent Claim
29 words
The cool down control of claim 47 wherein said preset length of time is user programmable such as to permit user programming of the dryness of said clothes load.
References Cited (Backward Citations)
No citation records indexed.
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