US3780532A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control system for centrifugal liquid chilling machines
Assignee: York International Corp
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Filing: 1971-09-17
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Granted: 1973-12-25
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Expires: 1991-09-17
Abstract
Abstract An improved temperature control system for centrifugal compressors in refrigeration equipment for elimination of ''''droop'''' associated with proportional position control is disclosed using a two thermistor temperature sensing unit for sensing both the temperature and the rate and direction of change of the temperature of the chilled liquid from the evaporator and for producing a change in the pre-rotation vane setting. The rate and direction of change of temperature is obtained by comparing a fast and a slow temperature signal in a summing amplifier to control a pulse width modulator that modulates a sawtooth generator to control a vane motor through appropriate logic. The fast temperature signal is also compared with a unit cycling thermostat reference signal in a Schmitt Trigger to de-energize the compressor when that temperature signal reaches the reference level. The fast temperature signal is also used to drive a recorder.
Inventors
- 👤 D Norbeck
- 👤 F Kimpel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:32
CPC Classifications
F; F25; F25B; F25B49/00; F25B49/02; G; G05; G05D; G05D23/00; G05D23/19; G05D23/1927; G05D23/1928; G05D23/193; G05D23/1931; G05D23/20; G05D23/24
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
213 words
In a refrigeration system, the combination of: means defining a refrigerant circuit; a centrifugal compressor connected in the circuit for compressing refrigerant; an electric motor connected for driving said centrifugal compressor; refrigerant throttling means, coupled throttle refrigerant supplied to said compressor for reducing the load on said electric motor; control means for controlling said refrigerant throttling means; and temperature sensing and signaling means connected to produce two electrically independent signals and for operating said throttling control means in response to one and both of said independent signals; and wherein said sensing and signaling means produces a first d.c. signal whose voltage is proportional to sensed current output temperature as one of said independent electrical signals and a second d.c. signal whose voltage amplitude is proportional to the prior output temperature as the other of said independent electrical signals; said system includes a set point reference signal source which set point signal is a d.c. voltage of a preselected amplitude; means coupled to receive said first, second and set point signals for producing an output d.c. signal whose amplitude is a function of all three such signals; and means actively coupled to said aforementioned signal receiving means, for energizing said control means for said throttling means in response to said input d.c. signal thereof.
Claim 2
Dependent Claim
213 words
In a refrigeration system, the combination of: means defining a refrigerant circuit; a centrifugal compressor connected in the circuit for compressing refrigerant; an electric motor connected for driving said centrifugal compressor; refrigerant throttling means, coupled throttle refrigerant supplied to said compressor for reducing the load on said electric motor; control means for controlling said refrigerant throttling means; and temperature sensing and signaling means connected to produce two electrically independent signals and for operating said throttling control means in response to one and both of said independent signals; and wherein said sensing and signaling means produces a first d.c. signal whose voltage is proportional to sensed current output temperature as one of said independent electrical signals and a second d.c. signal whose voltage amplitude is proportional to the prior output temperature as the other of said independent electrical signals; said system includes a set point reference signal source which set point signal is a d.c. voltage of a preselected amplitude; means coupled to receive said first, second and set point signals for producing an output d.c. signal whose amplitude is a function of all three such signals; and means actively coupled to said aforementioned signal receiving means, for energizing said control means for said throttling means in response to said input d.c. signal thereof.
Claim 3
Dependent Claim
133 words
In a refrigeration system, the combination of: means defining a refrigerant circuit; a centrifugal compressor connected in the circuit for compressing refrigerant; an electric motor connected for driving said centrifugal compressor; refrigerant throttling means, coupled throttle refrigerant supplied to said compressor, for reducing the load on said electric motor; control means for controlling said refrigerant throttling means; and temperature sensing and signaling means connected to produce two electrically independent signals and for operating said throttling control means in response to one and both of said independent signals; wherein means are provided for deriving a rate of change signals from said independent temperature signals and for deriving set point deviation indicating signals and said throttling means is governed as a function of both said rate of change signals and said set point deviation signals.
Claim 4
Dependent Claim
133 words
In a refrigeration system, the combination of: means defining a refrigerant circuit; a centrifugal compressor connected in the circuit for compressing refrigerant; an electric motor connected for driving said centrifugal compressor; refrigerant throttling means, coupled throttle refrigerant supplied to said compressor, for reducing the load on said electric motor; control means for controlling said refrigerant throttling means; and temperature sensing and signaling means connected to produce two electrically independent signals and for operating said throttling control means in response to one and both of said independent signals; wherein means are provided for deriving a rate of change signals from said independent temperature signals and for deriving set point deviation indicating signals and said throttling means is governed as a function of both said rate of change signals and said set point deviation signals.
Claim 5
Dependent Claim
83 words
The invention of claim 2 which also includes: control means (76) for interrupting the supply of electrical current to said electric motor; and unit cycling means (329, 320) coupled to said sensing and signaling means and to electrical interrupting controller means and responsive to the concurrent output temperature signal for causing the interruption of current to said motor in response to a current output temperature signal reaching a predetermined level and for ceasing the interruption after such signals fall below a certain level.
Claim 6
Dependent Claim
45 words
The invention of claim 3 wherein the system also includes: electric current module means (50) for sensing the electric current drawn by said motor and for also altering said operation of said throttling control means in response to a sensed overcurrent drawn by said motor.
Claim 7
Dependent Claim
31 words
The invention of claim 2 which also includes: a recorder coupled to said temperature sensing and signaling means for recording over a period of time the sensed current temperature signal therefrom.
Claim 8
Dependent Claim
192 words
In a refrigeration system of the type having a compressor, evaporator, liquid heat exchanger in the evaporator and a control system responsive to chilled liquid temperature, the improvement in a chilled liquid sensor unit (28) comprising: a first thermal sensitivity electric circuit element (283); a second thermal sensitivity electric circuit element (287) of a similar electrical characteristic to said first element; a housing (282) in which said first and said second elements are enclosed, said housing having means (281) adapting it for insertion into a chilled liquid leaving line; means for thermally insulating said first element to a relatively greater extent than said second element from the chilled liquid in such a leaving line; and electrical lines coupled to said first and said second elements and extending without said housing for allowing a first electrical signal to be produced representative of the temperature of said first element and a second electrical signal to be produced representative of said second element; whereby independent control functions, such as current liquid temperature recording using one of said elements, as well as rate of temperature change control using both of said elements, may be simultaneously employed.
Claim 9
Dependent Claim
192 words
In a refrigeration system of the type having a compressor, evaporator, liquid heat exchanger in the evaporator and a control system responsive to chilled liquid temperature, the improvement in a chilled liquid sensor unit (28) comprising: a first thermal sensitivity electric circuit element (283); a second thermal sensitivity electric circuit element (287) of a similar electrical characteristic to said first element; a housing (282) in which said first and said second elements are enclosed, said housing having means (281) adapting it for insertion into a chilled liquid leaving line; means for thermally insulating said first element to a relatively greater extent than said second element from the chilled liquid in such a leaving line; and electrical lines coupled to said first and said second elements and extending without said housing for allowing a first electrical signal to be produced representative of the temperature of said first element and a second electrical signal to be produced representative of said second element; whereby independent control functions, such as current liquid temperature recording using one of said elements, as well as rate of temperature change control using both of said elements, may be simultaneously employed.
Claim 10
Dependent Claim
58 words
The improvement described in claim 6, wherein: said first and said second thermal sensitive electric circuit elements are thermistors; said electric lines for producing independent signals are three: a first line connected to one side of each of said thermistors and a second line and third line respectively connected to the other end of one of said thermistors.
Claim 11
Dependent Claim
38 words
The invention of claim 7, wherein: said housing is a generally tubular shape; said thermistors are encased in epoxy within different portions of said tubular housing; and a thermal insulating wall (285) is positioned between said encased thermistors.
Claim 12
Dependent Claim
201 words
A refrigeration system comprising: a centrifugal refrigerant compressor having load reducing means; a condenser coupled to said compressor, to receive compressed refrigerant therefrom; an expansion device coupled to the condenser; an evaporator for receiving refrigerant from said expansion device and supplying it to said compressor, said eveporator having a heat exchanger employing a return liquid and leaving chilled liquid lines; a sensor unit connected in the chilled liquid leaving line, said sensor unit having two negative temperature responsive resistors one of which is mounted to track closely with the temperature of the chilled liquid leaving and the other of which has thermal insulation between it and that liquid so as to lag in responding to changes in the temperature of that liquid; an electronic temperature module coupled to said sensor unit for deriving an independent temperature information signal from each of said temperature responsive resistors thereof and for producing a rate of change signal therefrom and for producing a load modification signal as a function of the temperature and rate signals; and means responsive to the load modification signals of said module for altering the load reducing means of said centrifugal compressor; whereby said system may be caused to reduce ''''droop.''''
Claim 13
Dependent Claim
201 words
A refrigeration system comprising: a centrifugal refrigerant compressor having load reducing means; a condenser coupled to said compressor, to receive compressed refrigerant therefrom; an expansion device coupled to the condenser; an evaporator for receiving refrigerant from said expansion device and supplying it to said compressor, said eveporator having a heat exchanger employing a return liquid and leaving chilled liquid lines; a sensor unit connected in the chilled liquid leaving line, said sensor unit having two negative temperature responsive resistors one of which is mounted to track closely with the temperature of the chilled liquid leaving and the other of which has thermal insulation between it and that liquid so as to lag in responding to changes in the temperature of that liquid; an electronic temperature module coupled to said sensor unit for deriving an independent temperature information signal from each of said temperature responsive resistors thereof and for producing a rate of change signal therefrom and for producing a load modification signal as a function of the temperature and rate signals; and means responsive to the load modification signals of said module for altering the load reducing means of said centrifugal compressor; whereby said system may be caused to reduce ''''droop.''''
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |