US2188303A - Refrigeration test method - Google Patents

Description

Jan. 30, 1940. c. E. ROBERTS 2,188,303

REFRIGERATION TEST METHOD Filed Nov. 2'7, 193'! 4 Sheets-Sheet 1 F'IG.2.

WITNESSES: INVENTOR ,w; AM, CHARLES ERQBER-rs.

6.3 H WQZ ATTOR Jan. 30, 1940. c. E. ROBERTS REFRIGERATION TEST METHOD Filed Nov. 27, 1957 4 Sheets-Sheet 2 FROST LINE LIMIT FROST LINE LIMIT INVENTOR CHRRL.E5 EJ205525 ATTORNE PVC-L3.

WITNESSES law 5 2H Jan. 30, 1940. c. E. ROBERTS REFRIGERATION TEST METHOD 4 Shee ts-She et 3 Filed Nov. 27, 1957 INVENTOR CHARLES E'fiosza'rs WITNESSES:

BY i

ATTO y" Y Jan. 30, 1940. c. E. ROBERTS 2,188,303

REFRIGERATION TEST METHOD Filed Nov. 27, 1937 4 Sheets-Sheet 4 i AIR CONDITIONING: 3 I: APPARATUS FAN '3; 2, a L I==Il I 2 E1 l FIGJO.

WITNESSES:

INVENTOR w. CI- nm. E.Rqstn1'.s.

6.11. 4 I BY ATTOR Y Patented Jan. 30, 1940 2,188,303 REFRIGERATION TEST ME'rnon Charles E.

to Westinghouse of Pennsylvania Roberts, Springfield, Mass, assignor Electric & Manufacturing Company, East Pittsburgh, Pa.,

a corporation Application November 27, 1937, Serial No. 176,895

6 Claims.

My invention relates to a method for testing refrigerators and particularly to a method and apparatus for testing complete refrigerator units in large quantities on a production basis.

Complete refrigerator a condensing unit and a or evaporator. example, a condenser, a-

for driving the compressor.

units generally embody heat absorbing element The condensing unit includes, for

compressor and a motor The condensing unit and the evaporator are connected together by refrigerant tubing and after assembly are mounted in a refrigerator or air conditioning cabinet. Many test methods have been devised and used for testing complete refrigerator units in large quantities, but all prior schemes have been deficient in one or more respects.

For example, refrigerator units have been tested in production by placing insulating shrouds.

around the evaporators and then operating the units to determine certain performance characteristics thereof. Such a testing method is unsatisfactory because changes in atmospheric conditions in the building or refrigerating units are tests are not accurate.

the enclosure where the tested change the per- Furthermore, considerable expense in labor and materials is necessary for attachment and detachment of the shrouds.

Refrigerating units have also been tested on a production basis after they have been mounted in This testing method is refrigerator cabinets.

also unsatisfactory because of varying atmospheric conditions and high cost because of the space occupied by the in both the testing methods mentioned, it is the exception, rather than tremely heavy service conditions encountered in many homes and in cabinets. Furthermore,

the rule, that the exvarious geo graphic locations are encountered in such tests.

It is, therefore, an object of my invention to provide an improved method of testing refrigerator units on a production scale which will improve the accuracy of such tests and at the same time reduce the cost.

It is another object of my invention to automatically provide constant atmospheric conditions in an enclosure, so that a large number of refrigerator units may be uniformly tested and preferably under atmospheric conditions simulating heavy loads.

It is still another. obj

ect of my invention to provide an improved method of testing refrigerator units so that the units may be tested as they come off the assembly lines ready for shipment.

I which a large number of refrigerator units are carried on a continuously moving conveyor system, preferably.in a predetermined path, so that each unit will be subjected to conditions in all parts of the room and will'be in the room for a predetermined length of time.

It is still a further object of my invention to provide a room in which a substantially constant atmospheric heat load is maintained and though which refrigerators are carried on a moving conveyor system in such manner that the refrigerators may be tested while moving.

It is still a further object of my invention to provide a method for ascertaining the refrigerant charge, refrigeration capacity, head pressure and power input of a large number of individual refrigerator units while subjected to a substantially constant heat load.

It is yet another object of my invention to provide an enclosure for testing refrigerator units in production in which the dry bulb temperature and relative humidity, or the wet bulb temperature, are maintained substantially constant and impose a fixed heat load on the refrigerator units. as they operate in the enclosure.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a side view of a complete refrigerator 1 unit mounted on a frame which is used in shipping the unit;

Fig. 2 is an end view of the frame and refrigerator unit shown in Fig. 1;

Fig. 3 is an enlarged view of the evaporator of the refrigerator unit showing the inlet and outlet connections thereto;

Fig. 4 is a view illustrating an adjustable temperature control and wiring diagram for the refrigerator unit;

Fig. 5 is a view of a manually adjustable temperature control knob and the indlcia associated therewith;

Fig. 6 is a view taken on line VI-VI of Fig. '7 showing a refrigerator unit and frame mounted on a conveyor system used in the testing of the units;

Fig. 7 is a partial side view of the conveyor system;

Fig. 8 is a view Fig.

taken on line vnI-vm of view of an enclosure units are tested and units therethrough on refrigerator unit .ll 01'. the compression type is.

shown, by way of example, in Figs-1 and 2. The refrigerator unit ll includes what is generally termed a high pressure side, or condensing unit l2, and a low pressure side or evaporator l3. The condensing unit I2 embodies a hermetically sealed'motor-compressor unit M, a condenser IS, a fan IS, a fan motor I! and a float valve [8. Suitable conduits and electrical conductors connect the various parts of the refrigerator unit and liquid refrigerant is supplied to and vaporized refrigerant is withdrawn from the evaporator l3 by the motor-compressor unit l4,-

thus lowering the temperature of the evaporator, in accordance with the principle of the wellknown compressor-condenser-expander refrigeration cycle. The entire refrigerator unit is mounted on a shipping frame l9, as completely shown and described in Patent No. 2,079,238 to J. H. Ashbaugh, assigned to the Westinghouse Electric & Manufacturing Company.

As shown in Figs. 4 and 5, an adjustable control mechanism 2|, contained in a box 20, shown close contacts in Fig. 1, controls the operation of the compressor motor 22 and the fan motor I! in response to the temperature of the evaporator l3. A bulb 23, filled with an expansible medium, is in contact with the evaporator l3 and is connected by a conduit a to a bellows 24. The bellows 24 operates a pivoted lever 25 in response to temperature changes of the evaporator l3, which in turn operates a snap-acting mechanism 26 to open and 21 and establish a circuit between the line conductors L1 and La and the motors l1 and 22. A spring 28 opposes the force of the bellows, the bias of the spring being adjustable by a manually movable control knob 29 so that the evaporator temperatures at which the contacts 21 open and close may be varied. An indicating dial 3|, as shown in Fig. 5 is associated with the control knob 29, the #1 position being the coldest or continuous running" position, and the Defrost position being the warmest position at which the refrigerating system will cycle. An "off position is also provided on the indicating dial 3|.

Continuous running of the motors l1 and 22, regardless of evaporator temperature, is effected when the knob 29 is set at the #1 position by means of an arm 32 threaded on a shaft 33 to which the control knob 29 is attached. The arm 32 engages with a contact carrying member 34 of the snap-acting mechanism the contact carrying member 34 to a position where the contacts 21 are closed when the control knob 29 is turned to the #1 position. The position of the pivoted switch operating lever 25, therefore, has no effect on the contacts 2'! and the refrigerating system is operated continuously regardless of evaporator temperature.

As the control knob 291s turned clockwise to the higher numbered positions, the arm 32 is disengaged from the movable contact carrying member 34, which is then free to snap to open and the "oil" position,

26 and raises closed position, moving in a slot 33 in the arm 32. Movement of the control knob 29 to the higher numbered positions also increases the bias of the spring 28 so that the mean temperature of the evaporator is progressively raised, both the cut-oil! and cut-on temperature limits being higher.

In the off position, the motors l1 and 22 cannot be energized regardless of evaporator temperature. When the control knob 29 is set at the arm 32 is lowered and engages the contact carrying member 34 to hold it down so that the contacts 21 cannot close. The position of the pivoted lever 25, therefore, has no effect on operating the motors l1 and 22. It will also be noted that a magnetically operated switch 36 is provided in the circuit of the motors I! and 22 for controlling the starting windings thereof.

In practicing my invention, the refrigerator units II are first completely assembled and preferably are mounted on the shipping frames l9, as shown in Figs. 1 and 2. The units II are then subjected to a run-in test of approximately four hours in an enclosure (not shown) in which the dry bulb temperature alone is maintained substantially constant, preferably at 855 F. Both the-condensing unit l2 and the evaporator l3 are completely exposed to the 85 F. temperature during the run-in test. The first two hours of this test are conducted with the control mechanism adjusted to the #1 or continuous running position. Any units which have defects such as tight or noisy motor-compressor units, defective control or fan, and the like, are rejected. Just before stopping the units at the end of the two hour period, the units are purged for air, a purge fitting 40 (Fig. 2) containing a spring biased ball check valve 31 being provided for this purpose near the top of the float valve I 8. During the final two hours of the run-in test the units I I are operated with the control mechanism adjusted to the "Defrost position, at which adjustment the unit cycles rather slowly. This test insures that the units cycle properly and that the control adjustment effects defrosting of the evaporator l3 in the Defrost position. The evaporators are then permitted to dry,-as preferably no moisture should be present thereon at the start of the next part of the test.

The refrigerator units H are then placed on a movable conveyor system, illustrated in Figs. 6

to 9, inclusive. The conveyor system comprises a driving chain 39 and a trolley 4! which'r'olls on overhead I-beams 42. An attaching chain 43 engages the frame l9 to support the refrigerator unit ll. Bus-bar conductors 44 (Fig. 8) are connected to a source of power Io, L4 and flexible pick-up conductors 45 and 46 engage the bus-bars 44 to convey-electrical energy to the motors l1 and 22 of the refrigerator units through a plug and cord connection 41, (Fig. 7), a fuse 48 preferably being contained in the circuit.-

As shown in Fig. 9, the conveyor system moves the refrigerator units through an enclosure 49 in a sinuous path so that each refrigerator unit is moved through all parts of the enclosure 49 between the time it enters and leaves. Since the conveyor chain 391s moving at a constant and predetermined rate, and since the path for each refrigerator unit is the same, it is clear that each unit will be in the enclosure 49 the same length of time, preferably about three hours.

The enclosure 49 is maintained at a constant dry bulb temperature and relative humidity throughout by air conditioning apparatus 5| diagrammatically shown in Fig. 10, or, in other words, a constant heat load or-wet bulb temperature is maintained therein. I have found that a dry bulb temperature of 86:2" F. and a relative humidity of 47%i3% are very satisfactory and effect a proper heat load on .the refrigerator units while in the enclosure 49 with both the condensing units l2 and the evaporators l3 completely exposed. Air locks 52 and 53, shown in Fig. 9 are provided for the entrance and exit of the units. A humidistat 54 and a thermostat 55 are provided in the enclosure 49 for controlling the dry bulb temperature and relative humidity of the air delivered by the air conditioning apparatus 5|.

The maintenance of the enclosure 49 at a constant dry bulb temperature and relative humidity, or in other words, at a constant wet bulb temperature, is a very important feature of my invention, and, as will appear as the description of the various tests advances, effects accurate and consistent results in testing refrigerating systems in large quantities.

Before the refrigerator units ll enter the enclosure 49, the adjustable control mechanism 2| is adjusted to the #l, or continuous running position. As the individual units enter the air lock 52 on the conveyor system, the flexible contacts 45 and 45 engage the energized bus-bars 44 so that energization of the fan'motor l1 and compressor motor 22 is effected and the .condensing unit l2, therefore, continuously'supplies refrigerant liquid to the evaporator l3 and removes vaporized refrigerant therefrom, thereby reducingthe temperature of the evaporator to below the freezing point of water. The evaporator temperature is approximately F. after continuous operation for a short period of time. The evaporators l3 will, therefore, condense moisture from the air in the enclosure, which moisture will be deposited in the form of frost on the evaporator l3, and in some instances on a suction gas conduit 55 (Fig. 3) which conveysvaporized refrigerant from the evaporator l3 back to the condensing unit [2. Since several hundred units are generally in the enclosure 49, all of which are removing moisture therefrom and carrying moisture out of the enclosure in the form of frost, it is usually necessary for the air conditioning apparatus to continuously add moisture to the air in the enclosure 49 to maintain the relative humidity therein constant.

After the individual refrigerating systems have been operating continuously in the enclosure for approximately half the total time therein, or about one and a half hours, the units have been subjected to a heavy load for a considerable period of time and if operating properly the evaporators l3 are completely covered with frost. All during the test, operators are moving through the enclosure 49 checking units to ascertain whether they are running continuously as they should be, or whether they are cycling or have completely stopped. Any units which are not operating continuously are rejected. As shown in Fig. 10, a test station marked Test station l is provided about half way through the room and at this point the first analytical tests of the units II are made.

While the units are moving on the conveyor, the head pressure of the individual units is deter mined by attaching a pressure gauge (not shown) to the purge fitting 40, shown in Fig. 2, which communicates with the interior of the float valve It. The spring closed ball check valve 31, also shown in Fig. 2, is forced open 'by screwing the pressure gauge into the purge fitting 49, so that the pressure gauge registers the pressure in the condensing unit, or high pressure side of the refrigerating system II. If the head pressure is too high, a small amount of refrigerant is purged from the fitting 49 by depressing the ball check valve 31, which purging operation also removes any non-condensable gases which have collected in the float valve it. The head pr'essure is again checked and if too high the unit is again purged of a small amount of refrigerant and non-condensables. If the test shows that the head pressure is too low, the unit is rejected.

Since the units H are all subjected to a constant heat load on the evaporators l3 and on the condensing units l2 in the enclosure 49, and have all operated continuously for the same period of time when they reach the "Test station #I," it is possible to check each unit against the proper head pressure under the heat load condition existing in the enclosure. Each unit should be within definite limits of head pressures, because' each unit is tested under exactly the same conditions. The temperature and humidity of the air outside the enclosure, which varies from day to day and from season to season, obviously would change the heat load and, therefore, the head pressure of the units, so that constant corrections for varying conditions would have to be made to obtain intelligent and accurate test results if the units were not tested in the enclosure 49 where the heat load is always the'same.

The refrigerator units I I are also preliminarily tested for refrigerant charge at Test station #1. If the unit is overcharged, the frost on the suction tube 56 will extend beyond or to the left of the vertical line marked Frost line limit" in Fig. 3. If the unit is undercharged, the frost on the evaporator will not reach up to the horizontal line marked Frost line limitl Again, since every unit H is exposed to air of constant dry bulb temperature and relative humidity during test, the temperature of the evaporator and the dew point of the air is always the same, and the frost line on every unit should be substantially at the same position and may, therefore, be checked to ascertain whether it is within the permissible limits. If such a test was attempted under varying conditions, the position of the frost line .would vary considerably and thetest would be far from accurate. If the unit is overcharged, refrigerant is purged from the fit ting 40, at Test station #1 and the unit ll continues moving on the conveyor operating con-- tinuously. If the unit is undercharged, it is rejected and returned to the charging station for more refrigerant. If more than a definite percentage of units are found to be improperly charged, the instruments and workmen at the charging station may be immediately checked and the difficulty remedied.

A Test station #2, shown in Fig. 9, is provided almost at the exit from the enclosure 49, and when a unit arrives at this station, it has been in the enclosure approximately three hours, operating continuously. The frost line is again finally checked and only units whose frost lines are within the aforesaid definite limits are approved. The units are then tested for instantaneous watts input under the constant heat load, and each unit should be within definite predetermined limits of power consumption, since 7 is not limited to a frame support.

the evaporator temperature is to turn the control knob 29 toward its higher temperature positions, and determine at what position the condensing unit l2 s'tops operating. As the control knob 29 is rotated in a clockwise direction, the bias of the spring 28 against the bellows 24 increases, and if the pressure in the bellows 24 is at a sufliciently low value corresponding to the proper evaporator temperature, the contacts 21 will be opened at approximately the same control setting for each refrigerator. The heat load imposed by the air in the enclosure at the aforesaid temperature and humidity values is such that it is not necessary to wait for the evaporator l3 to increase intemperature. The unit should stop immediately when a certain'control setting is reached. Again, such a test is made possible by the constant heat load to which each unit H is subjected, and accurate results are ensured at all times. If the units l I do not cease operation at the proper control setting, the control is checked, and if the trouble is not in the control, the unit is rejected.

The control knob 29 is then turned to a predetermined position corresponding to a higher temperature than the cut-oil position just described, and the unit should start within a predetermined minimum time, which is substantially the same for all the units since they are all subjected to constant heat load. This test effects a final check on the control mechanism and starting relay. At this time, the fan is checked to determine if it is operating at full speed and in the proper direction.

It is to be noted that all of the aforementioned tests are made while the refrigerator units are moving on the conveyor system.

The refrigerating units l I then leave the air conditioned enclosure 49 and are given a noise test, a high and a low voltage starting and running test, and are finally tested at a very high voltage to detect any grounds in the electrical connections or motor windings. The individual units II are then conveyed to a transportation vehicle for shipment.

From the foregoing, it will be apparent that I have provided an improved method and apparatus for testing individual refrigerating systems or units on a quantity production basis. Although I have shown refrigerating units of the mechanical compression type, my invention isv equally applicable to other types. Furthermore, while I have shown the units being tested on a shipping frame, it is obvious that my invention It is also clear that many varying dry bulb temperature and relative humidity conditions of the conditioned air are suitable, and that constant heat load may be maintained by providing a constant wet bulb' air temperature. Furthermore, ferred embodiment, I control both temperature and humidity, improved results over those heretofore obtained will result from the use of my while in my preestablishing method and apparatus where only temperature or humidity is maintained substantially constant.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from'the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. The method of testing large numbers of individual refrigerating systems on a quantity or production basis, each of which refrigerating systems embodies an evaporator or heat absorbing element and a condenser or heat dissipating element, which method comprises maintaining an enclosure at a substantially constant temperature and humidity condition such as to impose upon the systems to be tested a predetermined heat load, introducing the systems into and progressively advancing the same through the enclosure, establishing by a lapse of time a uniform test condition for said systems by operating them with their respective evaporators and condensers directly exposed to the condition in the enclosure while they are advancing through the latter and ascertaining the accuracy of the quantities of refrigerant fluid contained in the respective systems by observing the position of a frost line on the respective systems while they are still effected by the aforesaid heat load conditions and after said lapse of time.

2. The method or testing large numbers of individual refrigerating systems on a quantity or production basis, each of which refrigerating systems embodies an adjustable mechanism for controlling the refrigeration temperatures of the systems, an evaporator or heat absorbing element and a condenser or heat dissipating element, which method comprises maintaining an enclosure at a substantially constant. temperature and humidity condition such as to impose upon the systems to be tested a predetermined load, introducing the systems into and progressively advancing the same through the enclosure, by a lapse of time a uniform test condition for said systems by operating them with their respective evaporators and condensers directly exposed to the condition in the enclosure while they are advancing through the latter and ascertaining the capacity of the respective ,refrigerating systems by observing the temperatures at which the systems cease to operate when the temperature control mechanisms of the respective systems are adjusted to relatively higher temperatures while the systems continue to be eifected by the aforesaid heat load conditions and after said lapse of time.

3. The method of testing large numbers of individual refrigerating systems on a quantity or production basis, each of which refrigerating systems embodies an adjustable mechanism for controlling the refrigerating temperatures of the systems, an evaporator or heat absorbing element and a condenser or heat dissipating element, which method comprises maintaining an enclosure at a substantially constant temperature and humidity condition such as to impose-upon the systems to be tested a predetermined heat load, introducing the systems into and progressively advancing the same through the enclosure, establishing by a lapse of time a uniform test condition for said-systems by operating them with amazes their respective evaporators and condensers directly exposed to the condition in the enclosure while they are advancing through the latter, ascertaining the discharge pressures in the individual systems, ascertaining the accuracy of the quantities of refrigerant fluid contained in the respective systems by observing the position of a frost line on the respective systems, and ascertaining' the capacities of the respective refrigerating systems by observing the temperatures at which the systems cease to operate when the temperature control mechanisms of the respective systems are adjusted to relatively higher temperatures, all while the systems continue to be affected by the aforesaid heat load conditions and after said lapse of time.

4. The method of testing mechanical refrigerating units, each comprising at least an evaporator and a condenser in operative relation with one another, said method comprising conveying said units progressively at apredetermined speed through a predetermined path, at least a portion of said path extending through an atmosphere of predetermined characteristics regarding moisture and temperature with the condenser and evaporator exposed to said atmosphere, starting the operation of said units at a relatively early position in said path, and observing the operating characteristics of said unit at a relatively later position in said path and comparing the observed operating characteristics with a predetermined standard, said path, speed, atmosphere, and first and second positions establishing an automatically-timed operating period forsaid units under standardized conditions.

5. The method of testing large numbers of individual refrigerating systems on a quantity or production basis, each of which refrigerating systems embodiesan evaporator or heat absorbing element and a condenser or heat dissipating element, which method comprises maintaining an enclosure at a substantially constant temperature and humidity condition such as to impose upon the systems to be tested a predetermined heat load, introducing substantial numbers of the systems into the enclosure, establishing by a lapse of time a uniform test condition for said systems by operating them with their respective evaporators and condensers directly exposed to the condition in the enclosure and ascertaining the accuracy of the quantities of refrigerant fluid contained in the respective systems by observing the position of a frost line on the respective systems as compared with a predetermined standard and while they are still affected by the aforesaid heat load conditions and after said lapse of time.

6. The method of testing large numbers of individual refrigerating systems on a quantity or production basis, each of which refrigerating systems embodies an adjustable mechanism for controlling refrigerating temperatures of the systems, an evaporator or heat absorbing element and a condenser or heat dissipating element, which method comprises maintaining an enclosure at a substantially constant temperature and humidity condition such as to impose upon the systems to be tested a predetermined heat load, introducing a plurality of the systems into the enclosure, establishing by a lapse of time a uniform test condition for said systems by operating them with their respective evaporators and condensers directly exposed to the condition in the enclosure, and ascertaining the capacity of the respective refrigerating systems by observing the temperatures at which the systems cease to 0D- erate when the temperature control mechanisms of the respective systems are adjusted to relatively higher temperatures as compared with a predetermined standard and while the systems continue to be affected by the aforesaid heat load

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