US2741095A

US2741095A - Refrigeratior having multiple section evaporator

Info

Publication number: US2741095A
Application number: US313453A
Authority: US
Inventors: James W Jacobs
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1952-10-07
Filing date: 1952-10-07
Publication date: 1956-04-10
Anticipated expiration: 1973-04-10

Description

April 10, 1956 J. w. JACOBS Filed Oct. 7. 1952 REFRIGERATOR HAVING MULTIPLE SECTION EVAPORATOR 2 Sheets-Sheet l INVENTOR. James WJacobs April 10, 1956 J. w. JACOBS 2,741,095

REFRIGERATOR HAVING MULTIPLE SECTION EVAPORATOR Filed Oct. 7, 1952 2 Sheets-Sheet 2 INVENTOR. James W Jacobs BYWMMMQ United States Patent O l REFRIGERATOR HAVING MULTIPLE SECTION EVAPORATOR James W. Jacobs, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware Application October 7, 1952, Serial No. 313,453

4 Claims. (Cl. 62-4) This invention relates to refrigerating apparatus and more particularly to a method and apparatus which facilitates defrosting both of the evaporators in a dual compartment refrigerator.

It is an object of this invention to provide a refrigerating system wherein the frost which forms on the evaporators is allowed to thaw during the off portion of each refrigeration cycle.

More particularly it is an object of this invention to provide a refrigerating system wherein the'evaporator means comprises three different sections connected in series refrigerant flow relationship and wherein two of the three evaporator sections are defrosted during each ott cycle.

Still another object of this invention is to provide a method and apparatus for defrosting that portion of the frozen food compartment evaporator on which frost normally accumulates while maintaining the main food supporting shelf below freezing at all times.

A further objectof this invention is to divide the evaporator for the frozen food compartment into two sections so as to make it possible to defrost the one evaporator section independently of the other.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Figure 1 is a perspective view with parts broken away showing somewhat diagrammatically a refrigerator constructed in accordance with my invention; and,

Figure 2 is a schematic view showing the refrigerant circuit and the controls for the system.

Referring now to the drawings wherein a preferred embodiment of the invention has been shown, reference numeral designates the outer shell of a refrigerator having a frozen food compartment 12 and an unfrozen food compartment 14. For purposes of illustration there has been shown a multiple door refrigerator wherein a first door 16 is provided for closing the front opening to the frozen food compartment 12 and a second door 18 is provided for closing the front opening of the unfrozen food compartment 14. The invention is also applicable to a refrigerator in which a single door closes both compartments. I

The frozen food compartment 12 is adapted to be maintained in a refrigerated condition by means of a pair of plate type evaporator sections 26 and 22. The evaporator section 20 is fiat and serves as the bottom for the frozen food compartment 12 and consequently it is in direct mechanical contact with the frozen foods stored in the compartment 12. Experience shows that the bottom wall of the frozen food compartment is normally covered by frozen foods and therefore the top surface of the evaporator section 20 is largely protected against the accumulation of frost thereon.

The evaporator section 22 is bent so as to form the top and side walls of the compartment 12. These are the 2,741,095 Patented Apr. 10, 1956 walls where frost tends to accumulate and consequently they must be defrosted from time to time. The inner surfaces of the evaporator section 22 are normally fully exposed to the air with the result that most of the excess moisture from the air tends to freeze on these surfaces.

In order to facilitate the drainage of defrost water from the surfaces of the section 22, the lower edges thereof are spaced from the adjacent edges of the evaporator section 20 so as to allow the defrost Water to drain into the condensate collecting pan 30 located directly below the

evaporator sections

20 and 22 as shown in Figure 1. The arrangement is such that the condensate water drains from the pan 30 through a drain pipe 32 into the main food storage compartment 14. The outlet of the drain pipe 32 is located directly adjacent the one wall of the compartment 14 as shown in Figure 1 whereby the drain water will flow down the side wall of the compartment 14 and into a drain opening 34 provided in the bottom wall of the compartment 14. The drain opening 34 discharges the water into the condensate evaporating pan 36 located directly over the condenser 38 so as to cause reevaporization of the water into the condenser air stream in accordance with well known practice.

The food storage compartment 14 is refrigerated by means of a plate type evaporator 40 mounted adjacent the upper rear corner of the compartment 14. A trough 42 is provided directly beneath the evaporator 46 and serves to direct the condensate water down along the rear wall of the compartment 14 in accordance with practice which is now well known in the refrigeration industry. Suitable insulation 44 surrounds the compartments l2 and 14 in the manner shown. The insulation which'surrounds the

evaporator sections

20 and 2 2 is preferably of the type enclosed within moisture proof plastic bags so as to prevent frost or moisture from permeating the insulation. There is no tendency for moisture damaging the insulation around the lower compartment 14 and consequently any form of insulation can be used to insulate this lower compartment.

It will be noted that the condensate collecting pan 30 separates the insulation surrounding the compartment 12 from the insulation surrounding the compartment 14. The pan 30 is large enough to collect any defrost water which occasionally may drain from the outer surfaces of the bags of insulation surrounding the frozen food compartment 12. A slight clearance between the outer edges of the pan. 30 and the outer wall of the cabinet 19 constitutes a breather space whereby any excess moisture in the lower part of the refrigerator is free to travel upwardly past the pan 30 and condense on the exposed and relatively cold surfaces of the evaporator section 22.

Referring now to Figure 2 of the drawing wherein the refrigerant circuit has been diagrammatically shown, reference numeral 50 designates a conventional sealed motorcompressor unit which serves to discharge compressed refrigerant through a line 52 into the condenser 38. The condensed refrigerant flows from the condenser 38 to a receiver and dryer receptacle 54 from whence liquid refrigerant is fed through a capillary tube type of restrictor 56.- The restrictor 56 feeds liquid refrigerant at a reduced pressure into the plate type evaporator or evaporator section 20 so as to refrigerate the foods placed thereon. Excess refrigerant flows from the evaporator 213 through a trap 58 to the evaporator 56 which is located in the compartment 14. During portions of the refrigeration cycle more liquid refrigerant will be supplied to the

evaporators

20 and 40 than can be evaporated therein and this extra liquid refrigerant then flows to the evaporator section 22 and helps to maintain the required low temperature in the frozen food compartment 12. The vaporized refrigerant returns to the compressor through the suction line 69.

The motor-compressor unit 50 is controlled by means of a thermostat 62 in thermal exchange relationship with the evaporator 29. The thermostat 62 opens and closes a switch 64 located in the power line '66 which leads to the motor-compressor unit 53*. The switch 64 is designed to close the circuit when the temperature of the evaporator 48 exceeds a predetermined value such as 36 degrees. Once the switch 64 closes it will remain closed until the temperature of the evaporator 44; drops to a predetermined low temperature such as'miiius 2 degrees. above mentioned temperature valu'eshave been given for purposes of illustration and may be varied somewhat without departing from the spirit ofmy invention.

A secondary refrigerating system is used for refrigerating the bottom wall ofthe food storage compartment 14 and includes an evaporator section 74 arranged in thermal exchange relationship with the'hotto'm wall of the compartmentland a condensing section 72 arranged in thermal exchange relationship with the back of the evaporator 40.

By virtue of the above described primaryrefrigerant circuit the evaporator section 20 will be supplied with an adequate amount of liquid refrigerant so as to prevent objectionable Warm-up of the frozen foods supported thereon even during defrosting. The

evaporator sections

40 and 22 however will be starved during each 05 cycle to such an extent that any frost which may have accumu- I-ated thereon during the on portion of the cycle will melt before another on cycle begins.

While the form of embodimentof the invention as herein disclosed'constitutes a preferred form, it isto be understood that other forms mightbe adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerator having a frozen-food storage compartment and an unfrozen food storage compartment, a first evaporator section forming the bottom wall of said frozen food storage compartment, a second evaporator section arranged in thermal exchange relationship with the contents of said unfrozen food compartment, a third evaporator section arranged in the upper portion of said frozen food storage compartment and connected to the outlet of said second evaporator section, said first and third evaporator sections forming the bottom and side walls respectively of said frozen food storage compartment, said bottom wall and said side walls being spaced from one another so as to prevent conduction of heat from said side walls to said bottom wall, refrigerant liquefying means for supplying liquid refrigerant to said evaporator sections, and means responsive to the temperature of said second evaporator section for controlling the operation of said refrigerantliquefying'means.

, 2. In a refrigerator having an upper frozen food s't'or-,

age compartment and a lower unfrozen food storage compartment, a first evaporator section forming the bottom Wall of said upper frozen food storage compartment, a second evaporator section arranged below said first evaporator section in thermal exchange relationship with the contents of said unfrozen food compartment, a third evaporator section arranged in the upper portion of said frozen food storage compartment and comprising refrigerant The insulated from said bottom wall, refrigerant liquefying means for supplying liquid refrigerant to said first evaporator section and thereafter said second and third evaporator sections in series refrigerant flow relationship, means responsive to the temperature of said second evaporator section for starting and stopping said refrigerant liquefying means, and means for trapping refrigerant in said first evaporator section while said refrigerant liquefying means is stopped. v a

3. In a refrigerator having a frozen food storage compartment and an unfrozen food storage compartment, 21 first evaporator section forming the bottom wall of said frozen food storage compartment, a second evaporator section arranged in thermal exchange relationship with the contents of said unfrozen food compartment, a third evaporator section arranged in the upper portion of said frozen food storage compartment and comprising refrigerant conduit means adjacent the top and side walls of said frozen food compartment, said top and side walls being insulatedfrom said bottom wall, refrigerant lique fying means for supplying liquid refrigerant to said first evaporator section and then to said Second and third evaporator sections, means responsive to the temperature of one of said latter evaporator sections for controlling said refrigerant liquefying means, said control means serving to stop said refrigerant liquefying means at a predetermined low temperature and to restart said refrigerant liquefying means at a predetermined higher temperature above the freezing temperature "of water whereby said conduit means adjacent the top and side walls of said frozen food compartment, said side and top walls being one section warms up to a defrosting temperature before said refrigerant liquefying means restarts and condensate collecting means disposed beneath the vside walls of said frozen food compartmentfor receiving the defrost, water.

4. In' a refrigerator having afroz'en food storage compartment and an unfrozen food storage compartment, a first plate type evaporator section forming the bottom Wall of said frozen food storage com'partment, a second evaporator section arranged in thermal exc'hangerelationship with the contents of said unfrozen food compartment, a third plate type evaporator section arranged in the upper portion of said frozen food storage compartment and forming side Walls of said frozen food storage compartment, said first and third evaporator sections being out of contact with one another so as to substantially prevent the conduction of heat from one to the other, refrigerant liquefying means for suplying liquid refrigerant to said evaporator sections in series refrigerant flow relationship, and means responsive to the temperature of said second'evaporator section for controlling the operation of said refrigerant liquefying means, said second evaporator section being connected between said first and third evaporator sections.

References Cited in the file of this patent UNITED STATES PATENTS 7 2,260,825 Blood Oct. 28, 1941 2,578,906 Tobey Dec. 18, 1951 2,597,267 Shoemaker May 20, 1952 2,617,268 Ashby Nov. 11, 1952 2,622,412 Staebler -z -2, Dec. 23, 1952 2,706,894 Shoemaker Apr. 22, 1955