US3373478A - Method of making refrigeration apparatus - Google Patents

Description

March 19, 1968 H. F; SIMMONDS, JR

METHOD OF MAKING REFRIGERATION APPARATUS Filed Nov. 17, 1965 3 Sheets-Sheet 1 INVENTOR Harold F Simmonds]:

BY [I ATTORAIE? WITNESSES March 19, F 5|MMONDS, JR

METHOD OF MAKING REFRIGERATION APPARATUS Filed Nov. '17, 1965 1 5 Sheets-Sheet 2 is \&\\\\\\\\\\\\\\\\\\\\w March 19, 1968 H. F. SIMMCDNDS, JR 3,373,478

METHOD OF MAKING REFRIGERATION APPARATUS Filed Nov. 17, 1965 3 Sheets-Sheet 5 FIGS. F|G.5. C l

United States Patent Oflice 3,373,478 Patented Mar. 19, 1968 3,373,478 METHOD OF MAKING REFRIGERATION APPARATUS Harold F. Simmonds, .lr., Columbus, Ohio, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a

corporation of Pennsylvania Filed Nov. 17, 1965, Ser. No. 508,221

8 Claims. (Cl. 29407) ABSTRACT OF THE DESCLOSURE' Method of producing a foamed-in-place insulated refrigeration device in which the refrigeration producing system is assembled to a fully testable state separate from the refrigeration device cabinet and tested, is then installed in the cabinet and tested again with its major parts in their final assembly physical locations, the cabinet then being foamed to fill the hollow insulating spaces in the cabinets with portions of the refrigeration system captured therein, and then testing said refrigeration system for proper operation.

This invention relates to a method of making refrigerators and like devices of the type using foamed-in-place insulation material.

While the use of polyurethane plastic material which is foamed-in-place in the walls of refrigerator cabinets has yielded substantial benefits, such as a reduction in required thickness of refrigerator walls without a corresponding loss in insulating quality, it has also posed some difi'icult manufacturing problems.

One problem has been concerned with the sequence of assembly of the components which make up the finished product since the step of foaming-in-place is in the nature of a fait accompli with respect to the character of the final product. That is, the foaming process is irreversible and, accordingly, defects in the assembly at the time of foaming are often not able to be remedied, as a practical matter, after the foaming step occurs. Hence, the manufacturer is faced with the question of which parts should be assembled when the foaming operation is carried out to obtain a maximum number of satisfactory products, and to minimize the defective products which experience has shown are hard to rework after foaming. This decision by the manufacturer must also be consistent with eificiency in the subassembly and final assembly steps, consistent with testing requirements at various stages and, finally, consistent with reworking requirements for those refrigerators which nevertheless turn out to be defective in one respect or another regardless of the efforts to minimize defects.

To aid an appreciation of the nature of the invention, some background as to specific problems arising in connection with foamed-in-place insulated refrigerators may be helpful. The principal structural components of such a refrigerator include an open-front outer shell serving as the exterior cabinet, and an open-front inner shell serving as a liner for the food compartment and the freezer compartment. The inner shell is nested within the cabinet with the facing liner and cabinet walls spaced apart to receive the insulating material. The gap between the front peripheral edges of the liner and cabinet is covered by thermal breaker strips which reduce heat conduction between the liner and cabinet, and which hide the raw peripheral edges. The refrigeration producing unit, which will hereafter he termed simply the unit, includes the conventional compressor, condenser, evaporator, refrigeration conduction lines connecting these parts, and the electrical wiring for controlling the operation of the unit in accordance with desired operation. The compressor, and sometimes the condenser, is usually located in a machine compartment below the bottom cabinet wall. The evaporator must be in, or at least be thermally contiguous to, the cold space to produce the refrigerating effect. Accordingly, the refrigerant lines connecting the evaporator to the remainder of the unit must somehow pass from the outside to the inside of the cold space. Also, a substantial amount of electrical wiring must connect parts at various locations both outside and inside the cold space.

All of the foregoing must be considered by the manufacturer in designing the refrigerating apparatus and in determining how the various parts of the refrigerator apparatus will be assembled, and in what sequence.

One way to assemble a refrigerating apparatus of foamcd-in-place type is to carry out the foaming step on the bare nested shells with substantially all of the unit components and the electrical connections omitted, and then mount an essentially complete and electrically connected unit to the shells after the foaming step. When a finned-tube type of evaporator is used, this requires that access holes be provided in the inner and outer shells to permit the later installation of the evaporator. The holes must be covered and sealed for the foaming step, and must also usually be protected against adhesion of the foam to the covers for ease in later removal to permitthe installation of the evaporator. Also, provision must be made to accommodate the refrigration lines, and the electrical wiring so that they may be properly connected and hidden in the finished product. In some cases of assembly in this fashion, the breaker strips are omitted, and a temporary sealing element is used at the peripheral edges of the liner and outer cabinet to prevent leakage out of the space between the walls. Electrical wiring is later placed in the space behind the breaker strips before the strips are installed. Salient advantages of assembling a complete unit after the foaming operation are that unit testing is facilitated, and defective units may be detected and remedied without the task of removal after installation. Further, replacement may he usually accomplished relatively easily without requiring discarding the already foamed shells.

Another way of accomplishing the assembly for a foamed type refrigerator apparatus is to mount the components of a refrigeration producing unit in their final locations as generally individual, unconnected parts before the foaming operation, and then connecting these parts after the foaming operation to make an operative unit. Of course, this permits parts of the refrigeration sys tem to be out of the foaming operation area insofar as generally only those parts which will be buried in the foam need be in their locations for the foaming operation. The disadvantages of this arrangement is that while individual components can be tested :as individual parts before the foaming operation, it is only after they are totally connected with all the joints and welds made that a fully adequate test can be made. Thus, clogged systems resulting from welds, blocking joints and noisy units are not detectable until the final connections have been made. Any defective assemblies uncovered at this point can result in costly repairs and perhaps even scrapping the cabinet.

With the method according to the present invention, the refrigeration producing unit is made as a separate subassembly in an area geared to efiicient assembly and designed to facilitate test procedures during the construction of the unit. The unit is tested for operating sound, refrigeration leaks, electrical connections, mechanical joints, and refrigeration producing ability, for example. Then the unit is assembled to the nested bare shells 3 before foaming with substantially all parts of the unit in their final locations and with the operative integrity of the unit maintained during installation. After the components are physically located, the unit is then again checked for operativeness including noise, leaks, clogging and electrically before the foaming step so that any defects in parts which would be ultimately buried in the foam are detected and may be remedied before the foaming step, or the entire refrigeration unit may be removed and replaced before foaming. Breaker strips are then installed, and the foam fixtures applied to support the cabinet against the pressure generated by the foaming reaction. The foaming step is then carried out. When the refrigerator is removed from the foaming fixture, such finishing touches as mounting the door, inserting interior lights, and connecting the interior temperature control element are all carried out to complete the refrigerator.

The invention will be described in connection with the accompanying drawing illustrating two examples of refrigerating devices designed to accommodate the application of the inventive concept, and wherein:

FIGURE 1 is an exploded isometric view, partly diagrammatic and partly schematic, of the principal components of a refrigerator and their general arrangement for assembly in a method according to the invention;

FIG. 2 is a partly-diagrammatic isometric view of a refrigerator with the parts in assembled relation before the foam fixtures are applied;

FIG. 3 is a fragmentary side view, in the nature of the vertical section, illustrating the manner in which the foam fixtures bear against various parts of the refrigerator for the foaming step;

FIG. 4 is a partly broken side view of a foam fixture with a contained refrigerator disposed to receive the foaming mixture;

FIG. 5 is a rear isometric view of an upright freezer of the type using a wire and tube condenser on its rear surface and illustrating the use of an expander support between the condenser and cabinet rear wall;

FIG. 6 is a side view of the nature of a vertical section illustrating the freezer of FIG. 5 in a foaming fixture; and

FIG. 7 is an isometric view illustrating the general location of certain parts of the refrigeration producing unit relative to the shells in a freezer of the type illustrated in FIGS. 5 and 6.

The refrigerator shown in FIG. 1 includes an openfront face outer shell or cabinet 10 shown in the supine position which it initially occupies when the other parts are to be assembled to it, the cabinet having a base cavity 12 usually called a machine compartment and separated from the generally rectangular box-shaped remaining space 14 by the bottom wall 16. The front face of the cabinet is defined by an inwardly-directed peripheral flange 18 extending entirely around the open-front face. The inner shell or liner 20 also has a generally open-front face provided with an intermediate partition 22 dividing the liner into a bottom freezer compartment 24 and a top food storage compartment 26. The peripheral edges 28 of the liner, and the edges 29 of the cabinet, are formed to accommodate the breaker strips 30 which are assembled to the liner and cabinet at a later stage of the process.

The refrigeration producing system or unit generally designated 32 includes a compressor 34, condenser 36, evaporator 38, suction and pressure lines bonded into heat exchange contact (therefore hereafter called the heat exchanger 40) and which carry the liquid and gaseous refrigerant through the system, and various electrical elements designated 42 and schematically illustrated to represent devices which perform a control function or some other function supplementing the basic refrigeration function of the unit. The parts represented by these blocks 42 include the freezer fan motor, timer motor, light switches, defrost termination thermostat, and various heaters such as the defrost heater, mullion, food liner heater, drain trough heater, evaporator cover heater, and

so on.

In accordance with the invention, the refrigeration producing unit 32 is made as a subassembly in a suitably designed unit construction facility in the manufacturers plant geared for efficient construction, charging and testing of the unit. Then, after these steps are completed, the unit is brought to the assembly line in that form, i.e., as a substantially complete operative subassembly, where it joins the shells It) and 20, the breaker strips 30, and other miscellaneous parts to be used in the assembly of the finished product.

The liner 20 is nested into the space 14 of the cabinet with the facing side walls of the liner and cabinet spaced by suitable mounting supports 33, and the unit 32 is then moved into a preliminary position adjacent the machine compartment 12. The compressor 34 and condenser 36 are mounted in the machine compartment 12 and the various electrical connections to those elements 42 not previously connected are then made. It is noted that while all of the elements 42 are shown as associated directly with the unit 32, some of these elements, such as the food liner heater, drain trough heater and the like which are preferably intimately bonded to one of the structural surfaces of the liner or cabinet may in fact be apart from the unit 32 during the unit construction and testing in its subassembly facility. However, the unit may still be fully tested by using standard substitute equivalents for these missing components, as will be readily appreciated. The electrical connections between those components intimately associated with the liner and cabinet are made by simply joining the wires leading from the terminal block on the compressor to the corresponding wires leading away from their elements. These wires are for the most part located in the spaces between the shell walls after the connections are made, except where they feed into the machine compartment, or where they feed from the wall space into one or the other of the compartments 24 and 26. The Wires for these parts such as the food liner heater and freezer side heater which are bonded to the outer surface of the liner emerge from the foaming space between the walls only at the machine compartment, while those wires for parts such as the compartment fan, which is physically located inside of the freezer compartment 24, have one end leading into the freezer compartment and the other end emerging into the machine compartment, with their intermediate lengths located for ultimate burial by the foam.

Referring now to both FIGS. 1 and 2, the evaporator 38 and heat exchanger 40 may be placed in their final locations before or after the electrical connections are made. They are mounted and installed by manipulating the heat exchanger 40 so that the exchanger length 4011 extends upwardly from the machine compartment 12 along the notch 44 formed in the front face of the cabinet bottom wall 16, and which is later covered by a plate 46. The next length 4011 extends to the right in the space to be foamed along the freezer bottom front edge to the right side. Length 401: extends in the foam space up the freezer right front edge to the right front upper corner of the freezer compartment. Here the heat exchanger is brought back into the interior of the freezer compartment space with length 40d extending back to the upper right rear corner of the freezer compartment where length 40:; runs down the corner. The evaporator, which remains in connected relation to the heat exchanger during the heat exchanger manipulation, is of course simultaneously manipulated into its final location where it is mounted immediately forward of the freezer compartment liner rear wall. Preferably the heat exchanger is pressed into the spaces which are to receive foam only far enough to accommodate the installation of the breaker strips 30. Accordingly, the part of the heat exchanger which is ultimately buried in the foam is closely adjacent the rear face of the breaker strip. This is advantageous in the event that the heat exchanger must be removed, since the breaker strip overlying the heat exchanger may be snapped out of place, and the heat exchanger torn out of the foam without great difi'iculty.

After the unit components are installed in their final locations and all of the electrical connections made between the components, the breaker strips 30'are installed by pressing them into place with their edge flanges engaging the respective peripheral edegs of the cabinet and liner. The preferred construction of the breaker strip means and cooperating cabinet structure is disclosed more fully in copending Kessler US. patent application Ser. No. 508,223 filed contemporaneously herewith on Nov. 17, 1965.

At this stage, the unit is energized to test the various electrical circuits to insure that the wiring is neither shorted nor open, and in good order. A skilled inspector can also tell reasonably Well from the noise produced whether the refrigeration unit is intact, and clogs, leaks and such are absent, so that the unit can produce the required refrigeratiom'lf defects are found during this testing, they may be easily remedied by replacing the defective component, or if necessary the entire unit, before the foaming operation takes place.

The refrigerator, after the testing, is then ready for the foaming step and is accordingly placed in a suitable fixture as shown in FIGS. 3 and 4. The fixture includes expandable plug portions which are located in each of the interior cavities to buttress the walls of the liner and cabinet which Will be subject to pressure generated by the foaming step. The food space plug is identified by the numeral 48, the freezer space plug is 50, and the machine compartment plug is 52. The plugs have surface contours designed to accommodate the various protruding components in the spaces, such as the evaporator 38 in the freezerspace. The presently preferred arrangement for the machine compartment plug is to provide a plug only in the front portion of this space, and to form the rear part of the cabinet bottom wall with a domed contour which yields only slightly 0 the foam pressure.

The foaming fixture (FIGS. 3 and 4) has, as a whole, the general shape of a rectangular box 54 and includes a lid 56 which presses againts the rear Wall of the cabinet. The cabinet rear wall is provided with a pair of pour holes 58 (later plugged) through which the measure amount of foaming material issuing from the nozzles 60 passes into the space between the cabinet and liner walls. The pressure generated by the reacting material causes the foam to expand and work itself into substantially all of the spaces between the walls, and up to the rear faces of the breaker strips. Accordingly, the foam bu-ries wiring and components previously installed in the spaces between the walls. The refrigerator walls and breaker strips resist displacement from the pressure exerted bythe foam by virtue of being backed up by the plugs" and fixture walls which are. well braced and latched in place before the foam is admitted into the space to be insulated.

After the foaming operation, the fixture and contained refrigerator are passed through an oven for sufficient time to permit the foam to cure. After the fixture emerges from the oven, the lid is taken off and the refrigerator is lifted out of the fixture and set up to permit inspection'of the refrigerator for foam leakage. At this stage, the refrigerator is substantially complete and simply. requires finishing touches such as the installation of a front door, and insertion of parts such as light bulbs and a temperature control switch for the cabinet, for example, which have been omitted during the foaming step to prevent damage thereto. It will be appreciated that the absence of the cabinet control is of little consequence with respect to the testing of the unit since its function is simply to close a circuit, and this may be accomplished by shorting the two leads which are ultimately to be attached to the cabinet control. It is also at this stage that parts of the refrigerator such as the coil cover, and

the various air diffusers associated with the frost-free type of refrigerator and freezer are installed, and the accessory parts such as shelves and the like are then placed in the refrigerator. However, to aid in properly delineating the inventive concept here involved, it is noted that these elements, while serving an operational function in the finished refrigerator, are not necessary during the noise, electrical and performance testing steps undertaken dwuring the construction and pretesting of the unit, and during its testing immediately prior to being placed in the foaming fixture. In other words, the elements which are required to be present during the testing operations prior to foaming, so that a determination as to the adequate performance of the finished product can be made, are present at those times. Accordingly, while there will still be some refrigerators which after foaming turn out to be defective in one respect or another, the number of such defective refrigerators found after foaming is significantly reduced by carrying out the method of this invention.

It will be appreciated that the inventive concept is not limited to the type of refrigerator having the specific construction shown in FIGS. l-4. For example, if the refri erator were to be of the type having a top mounted freezer, the principal different with respect thereto would be the location of the evaporator in the top freezer compartment rather than in the bottom freezer compartment, and the extension of the heat exchanger behind the breaker strip of substantially the height of the liner, rather than simply for the height of the bottom compartment. Other examples will also readily suggest themselves to those skilled in this art, and, accordingly, the reference to the bottom mounted and top mounted freezer as examples is not to be taken as limiting in any sense.

As one example of how the inventive concept may be applied to a freezer of the upright type having multiple shelf evaporators, the freezer of FIGS. 5-7 is illustrated. Several differences with respect to the construction of the freezer as compared to the refrigerator described heretofore stand out, and comment will be directed mainly to these differences. In the case of the freezer illustrated, a wire and tube condenser of extended area 62 is disposed adjacent the rear wall of the freezer instead of the forced air condenser described in connection with the refrigerator. Accordingly, the lid 64 of the foaming fixture 66 is spaced from the rear wall of the cabinet against which the foaming pressure exerts a force, and to buttress the rear wall in the area of the condenser, and to provide for transmission of the foam pressure to the lid through the condenser, an expander support 68 having pivotal links 70 is provided. The support 68 is placed between the condenser and the rear wall of the cabinet and opened as shown in FIGS. 5 and 6. In some cases the expander support 68 may be omitted with the condenser itself distributing the forces from the cabinet rear Wall to the lid of the fixture, and the lower part of the condenser being temporarily pushed into the machine compartment. Accordingly, it will be appreciated that the provision of a wire and tube condenser does not require a departure from the inventive concept expressed herein.

Referring now to FIGS. 6 and 7, the other major difference encountered in this type of construction is that the evaporators take the form of multiple shelves 72 vertically spaced in the cold space of the freezer instead of a single finned-tube type evaporator. The refrigeration unit and the multiple shelves in connected relation are installed in the cabinet with the heat exchanger '74 extending up behind the right side breaker strip 76 for example, and emerging into the freezer space at the upper right corner of the freezer compartment. The heat exchanger then extends back to the rear wall of the freezer liner and downwardly along the right rear corner, all of the connections between the shelves and the heat exchanger taking place in this corner. Subsequently a cover is installed over the heat exchanger lengths within the cold space to hide the exchanger. After testing the freezer for proper operation, it is placed in its foam fixture 66 and the foaming operation is carried out as previously described.

From the foregoing, it should be appreciated that the method concept of the invention is applicable to various refrigerator and freezer constructions. The concept requires that the refrigeration producing unit be a subassembly susceptible to adequate testing as a subassembly apart from the device into which it is to be installed, and the provision of sutficient length of heat exchanger line so that the evaporator may be manipulated, whether in finned-tube form or multiple evaporator shelf form, into its final location in the refrigerator or freezer without breaking the connections to the remainder of the refrigeration producing unit. The arrangement permits the replacement individually of most defective unit components by a service man in the field in generally the same way that replacement takes place with respect to conventional cabinets utilizing glass fiber insulating material. The heat exchanger, as one of the parts least susceptible to field failure, may still be replaced if need be by removing the breaker strip immediately in front of the heat exchanger. The method lends itself to the efficient construction and testing of the refrigerant producing units, permits substantially complete testing before the foaming step, and accordingly results in relatively few defective units after the foaming step is completed.

The preferred method of construction according to the invention includes the use of breaker strips made from a relatively tough and flexible acrylic butadiene polystyrene plastic having properties which permit the foam to expand directly against the breaker strips as disclosed in the noted Kessler application.

I claim as my invention:

1. The method of making refrigerating apparatus of the character described comprising the steps of:

forming an outer cabinet and a smaller inner liner adapted to be assembled into a nested liner-cabinet assembly having hollow insulating wall spacers therebetween;

assembling a refrigeration producing system including refrigerant conducting lines to an operative, substantially fully testable state;

testing said refrigerant producing system for proper operation;

assembling said liner and cabinet;

installing said system in said liner-cabinet assembly while maintaining operative integrity of said system and with at least a portion of said refrigerant conducting lines located in said hollow insulating wall spaces;

then again testing said system in its installed environment; and then filling said hollow insulating wall spaces of said linercabinet assembly with foamed-in-place plastic insulation forming an expanded insulating body capturing said portions of said refrigerant conducting lines in said spaces.

2. The method according to claim 1 including:

locating at least a part of the refrigerant conducting lines in said wall spaces; and

expanding said foamed-in-place plastic insulation in said wall spaces to capture said part of said refrigerant conducting lines.

3. The method according to claim 1 including: applying sealing means to said cabinet and said liner to substantially close said wall spaces in preparation for the subsequent step of filling said wall spaces with said foamed-in-place plastic insulation.

4. The method according to claim 2 including: applying breaker strip means to seal the gap between the adjacent edges of said liner and said cabinet after installing said system and before filling said spaces with said plastic insulation.

5. The method according to claim 4 including: locating said part of said refrigerant conducting lines closely behind said breaker strip means. 6. The method of making refrigerating apparatus having an inner liner generally defining a storage chamber, and an outer shell generally encompassing said liner in spaced relation, comprising the steps of:

assemblying a refrigeration producing system including a compressor, condenser, evaporator, connecting refrigerant conducting lines, and connecting electrical and control lines to form an operative, substantially fully testable subassembly;

then testing said subassembly for proper operation;

then assembling said subassembly and said liner to said shell in their finished product physical locations while maintaining the operative integrity of said system, said assemblying step including locating at least some portions of said refrigerant conducting lines and said electrical lines in the space between said liner and said shell;

sealing the gap between the edges of said liner and said shell, and sealing other openings in said liner and said shell to prevent leakage from the space between said shell and liner of foamed-in-place insulation applied during a subsequent step;

then testing said system to determine operativeness of said system in its installed environment;

applying a foaming fixture to said assembly of shell, liner, and system for supporting portions of said liner and shell against displacement during the subsequent foamed-in-place step;

applying a foamable plastic insulation material to said space between said liner and shell to form an eX- panded insulating body capturing said portions of said refrigerant conducting lines and said other lines located in said space; and thentesting said refrigeration system for proper operation after foaming.

7. The method according to claim 6 including:

applying breaker strip means in finished product locations to seal said gap between said liner and said shell.

8. The method according to claim 7 including:

locating a portion of said refrigerant conducting lines connecting said condenser and said evaporator in said space closely behind said breaker strip means.

References Cited UNITED STATES PATENTS a THOMAS H. EAGER, Primary Examiner,

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