Two-evaporator refrigerator having a controlled variable throttler

• US 6,715,305 B2
• Filed: 01/03/2003
• Issued: 04/06/2004
• Est. Priority Date: 01/15/2002
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Noguchi, Akihiro, Doi, Takashi
• Primary Examiner(s): NORMAN, MARC E
• Application Number:
  US10/336,028
• Publication Number:
  US 20030131618A1
• Time in Patent Office: 459 Days
• Field of Search: 621/80, 622/284, 622/23, 621/962, 625/10
• US Class Current: 62/180
• CPC Class Codes: F25B 1/10 with multi-stage compression with cascade operation F25B7/00
• CPC Class Codes: F25B 2400/13 Economisers
• CPC Class Codes: F25B 2400/23 Separators
• CPC Class Codes: F25B 2600/024 by controlling the electric parameters, e.g. current or voltage
• CPC Class Codes: F25B 2600/112 of evaporator fans
• CPC Class Codes: F25B 41/34 with the valve member being actuated by electric means, e.g. by piezoelectric actuators
• CPC Class Codes: F25B 41/37 Capillary tubes
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: F25B 5/04 arranged in series
• CPC Class Codes: F25D 11/022 with two or more evaporators
• CPC Class Codes: F25D 17/065 with compartments at different temperatures
• CPC Class Codes: F25D 2317/0682 Two or more fans
• CPC Class Codes: F25D 2400/04 Refrigerators with a horizontal mullion
• CPC Class Codes: F25D 2400/30 Quick freezing
• CPC Class Codes: F25D 2700/123 more than one sensor measuring the inside temperature in a compartment
• CPC Class Codes: F25D 2700/14 Sensors measuring the temperature outside the refrigerator or freezer
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A refrigerator has a refrigerant circuit that is comprised of; a power-variable two-stage compressor, a variable throttler, which are computer controlled; and a first evaporator for fresh food compartments and a second evaporator for freezer compartments. Temperatures in the first and second evaporators are controlled independently from each other, by controlling throttling extent of the variable throttler. Temperature in the first evaporator is kept in a range not causing frost formation on surface of the first evaporator, for example in a range from −2° C. to 2° C., by controlling the throttling extent as well as the power of the compressor. In a preferred embodiment, the variable throttler is a pulse motor valve at downstream of a condenser and at upstream of the first evaporator.

Claims

1. A refrigerator comprising:

a two-stage and power-variable compressor having an outlet and first and second inlets, pressure of said first inlet being intermediate between pressures of the outlet at higher pressure and the second inlet at lower pressure;

a condenser at downstream of said outlet;

a first evaporator at downstream of the condenser;

a gas-liquid separator being at downstream of the first evaporator and having a gas-phase refrigerant exit and a liquid-phase refrigerant exit;

a second evaporator at downstream of said liquid-phase refrigerant exit;

a first suction pipe connecting from the gas-phase refrigerant exit to said first inlet of the compressor;

a second suction pipe connecting from the second evaporator to said second inlet of the two-stage compressor;

a first fan for sending out air around the first evaporator into a fresh food compartment;

a second fan for sending out air around the second evaporator into a freezer compartment;

first and second throttlers, respectively interposed between the condenser and the first evaporator, and between said liquid-phase refrigerant exit and the second evaporator, throttling extent of at least one of said first and second throttlers being variable in response of computerized control;

sensors for detecting temperatures in the fresh food and freezer compartments and in the first and second evaporators; and

controller for controlling power of the compressor and throttling extent of said at least one of the first and second throttlers, based on detection of said sensors, as to keep said temperatures within respective prescribed ranges.

2. A refrigerator according to claim 1, throttling extent of said first throttler being varible and controlled by the controller.

3. A refrigerator according to claim 1, throttling extent of said first and second throttlers being varible and controlled by the controller.

4. A refrigerator according to claim 1, temperature in the first evaporator being controlled at a prescribed temperature range so that surface temperature of the first evaporator being kept substantially at 0°

C. or more.

5. A refrigerator according to claim 4, said prescribed temperature range being from −

2°

C. to 2°

C.

6. A refrigerator according to claim 4 or claim 5, further comprising a sensor for detecting temperature ambient to the refrigerator;

and

said controller implementing an operational control comprising;

determining whether ambient temperature detected is higher than a prescribed upper limit; and

,

if so determined, making and keeping the first evaporator at substantially lowest of said prescribed temperature range, by controlling said extent of throttling.

7. A refrigerator according to claim 4 or claim 5, said controller implementing an operational control comprising:

determining whether vigorous cooling is needed for the freezer compartment;

reducing temperature in the first evaporator, if so determined, to said prescribed temperature range, by keeping power of the compressor as enhanced to substantially its maximum;

while keeping rotational numbers of the first and second fans as raised above their predominant operation range, and by keeping the throttling extent of the first throttler as intense; and

then,

reducing temperature of the second evaporator to a temperature for the vigorous cooling, while allowing temperature rise in the first evaporator, by further keeping power of the compressor as enhanced to substantially its maximum and by keeping rotational number of the first fan as reduced below its predominant operation range;

while keeping rotational number of the second fan as raised above its predominant operation range, and by keeping the throttling extent of the first throttler as intense.

8. A refrigerator according to claim 4 or claim 5, further comprising a sensor for detecting temperature ambient to the refrigerator;

and

said controller implementing an operational control comprising;

determining the temperature ambient to the refrigerator to be lower than a prescribed lower limit;

reducing temperature of the first evaporator, if so determined, to a temperature within said prescribed temperature range by keeping power of the compressor as reduced below its predominant operantion range;

while rotational numbers of the first and second fans are reduced below their predominant operation range, and throttling extent of the first throttler is kept as loosen;

subsequently, further reducing temperature in the second evaporator to a temperature within a presciribed range or within a predominant operation range of the second evaporator, by further keeping rotational number of the second fan as reduced below its predominant operation range;

while stopping the first fan and keeping the throttling extent of the first throttler as intense; and

when the temperature of the second evaporator having been reduced to its predominant operation range, making or keeping temperature in the first evaporator as to be ice free on its surface, by loosening the throttle extent of the first throttler substantially to its maximum;

while keeping rotaitional number of the first fan within its predominant operation range, and while reducing the rotational number of or stopping the second fan.

9. A refrigerator according to claim 8, wherein the power of the compressor is further reduced or the compressor is stopped when said making or keeping temperature in the first evaporator as to be ice free on its surface.

10. A refrigerator according to claim 1, said at least one of the throttlers being a variable valve.

11. A refrigerator according to claim 10, said variable valve being either of a pulse motor valve and an electrical variable valve comprised of piezoelectric actuator.