§
Luxuse
Patent Intelligence
Sign In
← Back to Patent Explorer
US3872685A Expired / Lapsed US ⏱️ 0.0 years remaining

Evaporator temperature control for refrigeration systems

Assignee: Eaton Corp
•
Filing: 1974-01-15
•
Granted: 1975-03-25
•
Expires: 1994-01-15
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract Each of the two refrigeration systems incorporates an electric evaporator temperature control regulated by a solid state temperature switch which may be adjusted for a desired temperature and may be located in a remote location. In one system the control valve is located in the suction line between the evaporator and compressor and functions to throttle flow to the compressor when the temperature at the thermistor sensing probe falls below the set point. In the other system the temperature control valve functions as a hot gas bypass valve from the compressor outlet to the suction line between the evaporator and the compressor. The valve is opened when the temperature at the thermistor sensing probe falls below the set point. In either system operation of the temperature control valve acts to control pressure in the evaporator and thus controls the temperature. With the sensor located in the air stream, the system functions to control the air stream temperature and will compensate the system for frost build-up on the evaporator. The temperature control valve itself is preferably a ported sleeve-type valve actuated by a bimetallic stack energized by a heater regulated by the remote temperature sensing control. The temperature control includes a thermistor which forms part of an adjustable branch of a bridge circuit, the output of which is fed into a signal amplifier which, in turn, feeds into a power amplifier to give a desired voltage change per a selected increment of temperature deviation from the set point. In addition to giving remote sensing and adjustability, this system achieves close temperature control and more rapid pulldown of the system since there is a minimal modification of evaporator temperature/pressure until the desired temperature is reached. When used in a display case the system can incorporate an added resistance and switch to shift the set point to compensate for changed ambient conditions.

Inventors

  • 👤 Alan A Matthis

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 12:09
CPC Classifications
A; A47; A47F; A47F3/00; A47F3/04; A47F3/0478; F; F25; F25B; F25B41/00; F25B41/20; F25B41/22; F25B49/00; F25B49/02; F25B2347/00; F25B2347/02; F25B2347/023; F25B2400/00; F25B2400/22; F25B2600/00; F25B2600/02; F25B2600/026

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 219 words
A control for regulating the temperature in a space refrigerated by a system including a compressor, condenser, an expansion valve, and an evaporator, the compressor discharging hot compressed refrigerant to the condenser where it is condensed and the refrigerant flow to the evaporator is regulated by the expansion valve, the evaporator outlet being connected to the compressor inlet, an electrically operated control valve located between the evaporator and the compressor and operative to control evaporator pressure and thus temperature independently of the expansion valve, a temperature sensing thermistor located in the refrigerated space at a point at which the temperature is to be controlled, an electric circuit including the thermistor and the control valve and an electric bridge circuit having the thermistor electrically connected in one branch of the bridge, means for adjusting the resistance of said one branch whereby the temperature setting of the control may be adjusted to determine the temperature maintained at the thermistor, said bridge circuit being operative to develop a control signal which is amplified and supplied to the control valve to cause the control valve to be actuated to control evaporator pressure solely as function of the temperature at the thermistor and as a result the evaporator pressure is compensated for presence of frost on the evaporator or other restriction upon heat transfer.
Claim 2
Dependent Claim 219 words
A control for regulating the temperature in a space refrigerated by a system including a compressor, condenser, an expansion valve, and an evaporator, the compressor discharging hot compressed refrigerant to the condenser where it is condensed and the refrigerant flow to the evaporator is regulated by the expansion valve, the evaporator outlet being connected to the compressor inlet, an electrically operated control valve located between the evaporator and the compressor and operative to control evaporator pressure and thus temperature independently of the expansion valve, a temperature sensing thermistor located in the refrigerated space at a point at which the temperature is to be controlled, an electric circuit including the thermistor and the control valve and an electric bridge circuit having the thermistor electrically connected in one branch of the bridge, means for adjusting the resistance of said one branch whereby the temperature setting of the control may be adjusted to determine the temperature maintained at the thermistor, said bridge circuit being operative to develop a control signal which is amplified and supplied to the control valve to cause the control valve to be actuated to control evaporator pressure solely as function of the temperature at the thermistor and as a result the evaporator pressure is compensated for presence of frost on the evaporator or other restriction upon heat transfer.
Claim 3
Dependent Claim 53 words
A control according to claim 1 including a second resistance in series with said one branch of said bridge circuit, and a switch for shunting said second resistance whereby the temperature set point as determined by said adjusting means can be shifted by having the second resistance in or out of the circuit.
Claim 4
Dependent Claim 54 words
A control according to claim 1 in which the control valve is located in the flow path between the evaporator and the compressor and is open until the selected control temperature is reached at which time it functions to throttle flow to the compressor and thereby prevent further pulldown of evaporator pressure and temperature.
Claim 5
Dependent Claim 61 words
A control according to claim 1 including a bypass conduit from the compressor discharge to a point downstream of the expansion valve, said control valve being located in the bypass conduit and being closed until the selected control temperature is reached at which time it opens to pass hot compressed refrigerant and thereby prevent further pulldown of evaporator pressure and temperature.

References Cited (Backward Citations)

US2309773A Cited
US3380262A Cited
US3577743A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-03-24 1978-09-23 1979-03-25 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-03-24 1982-09-23 1983-03-25 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-03-24 1986-09-23 1987-03-25 $7700.00 Window Closed / Lapsed

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag