US5295364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Refrigeration pull-down technique
Assignee: Honeywell Inc
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Filing: 1993-07-14
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Granted: 1994-03-22
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Expires: 2013-07-14
Abstract
Abstract Apparatus for and method of rapidly bringing a controlled space to a desired temperature. The technique is particularly applicable to the maintenance of controlled temperature spaces for the transportation of perishable cargo, such as in refrigeration trucks. Immediately following completion of the loading process, it is desirable to bring the internal temperature of the controlled space to the proper operating point as quickly as possible to retard spoilage. However, it is necessary to avoid unacceptable overshoot to prevent damage to the cargo by freezing. The disclosed system employs multiple sensors and a control algorithm to permit pull down to occur as rapidly as possible without unacceptable overshoot.
Inventors
- 👤 Greg Truckenbrod
- 👤 Paul C. Wacker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:04
CPC Classifications
F; F25; F25D; F25D29/00; F25D29/003; G; G05; G05D; G05D23/00; G05D23/19; G05D23/1927; G05D23/193; G05D23/1935
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
144 words
A refrigeration system control apparatus comprising: a. means for initiating a pull down mode of operation; b. a plurality of sensors for monitority a plurality of parameters during said pull down mode wherein said plurality of sensors includes a discharge air temperature sensor; c. means for comparing each of said plurality of parameters to a different predetermined standard to produce a plurality of comparisons including second means for determining whether discharge air temperature is less than a predetermined set point minus ten degrees and including second means coupled to said second determining means for deactivating said pull down mode whenever said second determining means indicates that said discharge air temperature is less than a predetermined set point minus ten degrees; and means responsively coupled to said comparing means for terminating said pull down mode in response to a one of said plurality of comparisons.
Claim 2
Dependent Claim
144 words
A refrigeration system control apparatus comprising: a. means for initiating a pull down mode of operation; b. a plurality of sensors for monitority a plurality of parameters during said pull down mode wherein said plurality of sensors includes a discharge air temperature sensor; c. means for comparing each of said plurality of parameters to a different predetermined standard to produce a plurality of comparisons including second means for determining whether discharge air temperature is less than a predetermined set point minus ten degrees and including second means coupled to said second determining means for deactivating said pull down mode whenever said second determining means indicates that said discharge air temperature is less than a predetermined set point minus ten degrees; and means responsively coupled to said comparing means for terminating said pull down mode in response to a one of said plurality of comparisons.
Claim 3
Dependent Claim
18 words
An apparatus according to claim 1 wherein said plurality of sensors further comprises a return air temperature sensor.
Claim 4
Dependent Claim
40 words
An apparatus according to claim 1 or claim 2 further comprising means for discontinuing said pull down mode whenever the difference between said discharge air temperature and a predetermined floor temperature multiplied by time is greater than a predetermined integral.
Claim 5
Dependent Claim
14 words
An apparatus according to claim 3 wherein said predetermined integral is 150 degree minutes.
Claim 6
Dependent Claim
68 words
An apparatus according to claim 1 wherein said comparing means further comprises: a. first means for determining whether return air temperature is less than a predetermined set point plus one degree; and b. first means coupled to said first determining means for deactivating said pull down mode whenever said first determining means indicates that said return air temperature is less than said predetermined set point plus one degree.
Claim 7
Dependent Claim
67 words
An apparatus according to claim 2 wherein said comparing means further comprises: a. first means for determining whether return air temperature is less than a predetermined set point plug one degree; and first means coupled to said first determining means for deactivating said pull down mode whenever said first determining means indicates that said return air temperature is less than said predetermined set point plus one degree.
Claim 8
Dependent Claim
40 words
An apparatus according to claim 5 or claim 6 further comprising means for discontinuing said pull down mode whenever the difference between said discharge air temperature and a predetermined floor temperature multiplied by time is greater than a predetermined integral.
Claim 9
Dependent Claim
14 words
An apparatus according to claim 7 wherein said predetermined integral is 150 degree minutes.
Claim 10
Independent Claim
98 words
A method of terminating a pull down mode of a heat exchange system of a temperature controlled space comprising: a. monitoring a first parameter of said temperature controlled space; b. terminating said pull down mode if aid first parameter coincides with a first predefined condition; c. monitoring a second parameter of said temperature controlled space; d. terminating said pull down mode if said second parameter coincides with a second predefined condition; e. computing a third parameter of said temperature controlled space; and f. terminating said pull down mode if said third parameter coincides with a third predefined condition.
Claim 11
Independent Claim
98 words
A method of terminating a pull down mode of a heat exchange system of a temperature controlled space comprising: a. monitoring a first parameter of said temperature controlled space; b. terminating said pull down mode if aid first parameter coincides with a first predefined condition; c. monitoring a second parameter of said temperature controlled space; d. terminating said pull down mode if said second parameter coincides with a second predefined condition; e. computing a third parameter of said temperature controlled space; and f. terminating said pull down mode if said third parameter coincides with a third predefined condition.
Claim 12
Independent Claim
104 words
An apparatus for refrigerating a space comprising: a. means for initating a pull down mode of operation; b. a return air temperature sensor; c. a discharge air temperature sensor; d. means responsively coupled to said initiating means and said return air temperature sensor for terminating said pull down mode of operation whenever said return air temperature is less than a setpoint plus a first predetermined number; and e. means responsively coupled to said initiating means and said discharge air temperature sensor for terminating said pull down mode of operation whenever said discharge air temperature is less than said setpoint minus a second predetermined number.
Claim 13
Independent Claim
104 words
An apparatus for refrigerating a space comprising: a. means for initating a pull down mode of operation; b. a return air temperature sensor; c. a discharge air temperature sensor; d. means responsively coupled to said initiating means and said return air temperature sensor for terminating said pull down mode of operation whenever said return air temperature is less than a setpoint plus a first predetermined number; and e. means responsively coupled to said initiating means and said discharge air temperature sensor for terminating said pull down mode of operation whenever said discharge air temperature is less than said setpoint minus a second predetermined number.
Claim 14
Dependent Claim
18 words
An apparatus according to claim 10 wherein said first predetermined number is smaller than said second predetermined number.
Claim 15
Dependent Claim
67 words
An apparatus according to claim 11 further comprising: a. means for determining duration of said pull down mode of operation; and b. means coupled to said initiating means, said determining means, and said discharge air temperature sensor for terminating said pull down mode of operation whenever the integral over time of a floor temperature minus said discharge air temperature is greater than a predetermined number of degree-minutes.
Claim 16
Dependent Claim
15 words
An apparatus according to claim 12 wherein said floor temperature is about 33 degrees fahrenheit.
Claim 17
Dependent Claim
15 words
An apparatus according to claim 13 wherein said setpoint is larger than said floor temperature.
Claim 18
Dependent Claim
14 words
An apparatus according to claim 14 wherein said predetermined number of degree-minutes is 150.
References Cited (Backward Citations)
US3964676A
Cited
US4021213A
Cited
US4060123A
Cited
GB2059642A
Cited
US4509586A
Cited
US4589060A
Cited
US4663725A
Cited
US4715190A
Cited
US4742689A
Cited
EP0299361A2
Cited
US4918932A
Cited
US4977752A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-03-21 | 1997-09-20 | 1998-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-21 | 2001-09-20 | 2002-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-21 | 2005-09-20 | 2006-03-22 | $7700.00 | Window Closed / Lapsed |