US2284915A

US2284915A - Heat exchange apparatus

Info

Publication number: US2284915A
Application number: US347341A
Authority: US
Inventors: Ralph K Miller
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1940-07-24
Filing date: 1940-07-24
Publication date: 1942-06-02
Anticipated expiration: 1959-06-02

Description

R. K. MILLER HEAT EXCHANGE APPARATUS June 2, 1942.

Filed July 24, 1940 Fig. 1

2 Sheets-Sheet l ATTORT June 2, 1942. R. K. MILLER HEAT EXCHANGE APPARATUS Filed July 24, 1940 2 Sheets-Sheet 2 ATTORNEYS Patented June 2, 1942 UNITED STATES PATENT OFFICE HEAT EXCHANGE APPARATUS Ralph K. Miller, Dayton, Ohio, assignor to General Motors Corporatiom'Day'ton, Ohio, a corporation of Delaware Application July 24, 1940 Serial No. 347,341 4 Claims. (Cl. 257-241)- This invention relates to refrigerating apparatus and more particularly to means for controlling the contact between primaryand secondary heat transfer systems.

Recently there has been introduced a type of refrigerator known as a Cold Wall refrigerator. This type differs from conventional household Fig. 4 is asectional view taken along the lines 4 -4 of Fig.2.}

refrigerators in that a glass partition is provided I for dividing the interior into upper and lower compartments. This type also differs in that a secondary refrigerant circuit is wrapped around the walls of the lower compartment and has a portion in contact with the evaporator or freezer -coil in the upper compartment. The temperature of the lower compartment depends upon this contact between the secondary circuit and the freezer coil. It is diflicult to make the contact between the bare tubing of the secondary circuit with the freezer coil uniform in production and considerable servicing is required in'correcting the contact variations.

It is an object of my invention to provide a contact arrangement between the primary and secondary and heat transfer means which will be uniform when made by satisfactory mass production methods.

It is another object of my invention to provide a contact arrangement between the primary and secondary heat transfer means which will maintain desired secondary temperatures.

It is another object of my invention to provide a contact arrangement designed to take advantage of certain properties of power tools used in assembling, to obtain uniformity of contact.

It is another object of my invention to provide a contact arrangement'whereby each portion of the contact area' is assured of proper contact pressure.

It is still another object of my invention to provide a contact arrangement wherein uniform contact area is assured regardless of the conditions of assembly.

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:

Fig. 1 is a perspective view of a refrigerator embodying one form of my invention;

Fig. 2 is a side view of the primary evaporator or freezer coil with the contact portion of the secondary circuit mounted thereon; I

Fig. 3 is a view of the opposite side of the contact portion of a secondary circuit; and

While Iha've shown the invention as applied to a household refrigerator, it is applicable to' any contact arrangement between a primary unit and a secondary circuit. The drawings show a Cold Wall type of refrigerator in which the contact portion of the secondary is formed. into a hairpin loop provided with a contact plate having .webs extending across the loop and provided with contact surfaces held in contact with various wall'portions of the primary evaporator by screws located at the center portion of each web.

ticularly to Fig. 1, there is shown a refrigerator cabinet provided with outer metal walls 22 surrounding a box-shaped inner liner member 24.

The space between the inner liner 24 and the outer metal walls 22 is filled with a suitable insulating material to obstruct the flow of heat into the interior of the inner liner. Beneath the bottom of the inner liner 24 is a machine compartment containing a refrigerant liquefying means which-supplies liquid refrigerant to and withdraws evaporated refrigerant from the primary evaporator 26 located in the upper portion of the interior of the inner liner member 24.

This evaporation within the primary evaporator member 30 may be provided with ventilating apertures 38, if desired, in order to provide a controlled amount of ventilation or circulation between the two compartments.

The lower compartment 36 is cooled by a sec-' ondary refrigerant circuit which includes an initial portion 40 fastened to the bottom wall of the inner liner member 24 and a succeeding portion 42 which is wrapped around and is clamped to the side and rear walls of the inner liner 24 beneath the glass dividing partition 30. These portions of the secondary circuit are connected to a hairpin loop contact portion 44 located adjacent a side wall of the primary evaporator 26. This loop enters the upper compartment 34 Referring now to the drawings and more parthrough a slot in the rear wall of the inner liner 24 which is covered by a rubber grommet 4B or some other suitable covering and sealing means.

evaporator to the secondary circuit varied considerably in different refrigerators. This is quite reasonable since different workmen in different shifts perform the fastening operation and will not fasten the secondary tubing to the primary evaporator with the same tightness. Because of this, much servicing was required in order to adjust the. thermal contact between the primary and secondary circuits.

In the construction shown in this application these variations are avoided. Instead of applying the bare tubing directly to the walls of the primary evaporator I provide a contact plate 48 which has its upper and lower edges soldered, welded or otherwise bonded to the upper and lower portions of the hairpin loop contact portion 44 of the secondary circuit. The contact plate 48 is provided with uniformly spaced slots 50 throughout its length so as to divide the midportion of the plate into eight webs 52 which are uniform in width, thickness and shape. The plate is bent into the shape shown most clearly in Fig. 4 so that each web has a central bowed portion 54 provided with a central aperture which receives a fastening screw 56 for clamping its web into contact with the flat portions 58' -The slots 58 receive the refrigerantpassages 50 and thus by this construction no difference need-be made in the construction of the primary evaporator 26 from the conventional construction. All that needs to be done is to provide threaded apertures in the flat portions of'one of the side walls.

The ends of the bowed portion 54 of each web are bent upwardly to provide convex surfaces 64 and B6 in contact with the wall portion 58 of the primary evaporator 26. Preferably this bend is uniform so that no matter how tight the fastening screws 56 are tightened, the same amount of contact surface is provided. This construction provides line contact between the convex portion of each web and the primary evaporator 26 so that the contact therein is very limited and accurately controlled. The hairpin loop proper of the secondary circuit is kept away from the pri mary evaporator 26 and all thermal conduction must pass through the contactplate 48 which controls the thermal contact between the two refriger'ant circuits.

The fastening is done by a power screw-driver and the workmen are ordered to thread these screws in place with the power screw-driver until the motor stalls. Since this stalling point will be uniform, a uniform contact pressure between the contact plate 48 and the evaporator 26 will be obtained. The bowed portion of each web will serve as a sort of spring to always maintain this contact pressure. Thus by this construction I take advantage of the uniformity of power in the power screw-driver machine used in order to secure uniformity with respect to the contact between the primary and secondary circuits with respect to the entire output.

The number of webs and slots are varied in accordance with the different sizes of refrigerators, to satisfy the refrigerating requirements for the lower compartment.

The primary evaporator 26 is placed close to the wall of the inner liner 24 nearest the contact portion 44 so as to reduce the air cooling requirements of that wall of the primary evaporator and to increase the air flow wiping the bottom and the other side of the primary evaporator for cooling the upper compartment.

While the form'of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be, understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Heat transfer apparatus including a primary heat transfer unit, means forming a secondary circuit unit, one of said units being provided with separated bowed webs having convex surfaces at each end of the bowed portion, and separate fastening means at each 'of said bowed portions for holding said convex surfaces firmly in contact with the other unit.

2. Heat transfer apparatus including a pri- 'mary heat transfer unit, means forming a secondary circuit unit, one of said units being provided with separated web portions, and clamping means for holding each of said web portions firmly in contact with the other unit.

.3. Heat transfer apparatus including a primary heat'transfer unit, means forming a secondary circuit unit removably associated with said primary unit, said secondary unit being provided with separated web portions, and detachable clamping means for holding each of said web portions firmly in contact with said primary unit.

4. Heat transfer apparatus including a primary heat transfer unit, means forming a secondary circuit unit, one of said units being provided with separated bowed webs, and separate clamping means for detachably holding the ends of said bowed webs firmly in contact with the other unit.

' RALPH K. MILLER.