US2479011A - Milk can cooler - Google Patents

Description

R. D. KEMPER MILK cm COQOLER Aug. 16, 1949.

2 Sheets-Sheet 1 Filed D60. 2. 1948 Snventor Ralph D.Kmper v TIN mm. 3 a 3 i AM x a r flw of, E 2 mm mm o x 5 m 0 WM H 0i Filed 12 0.2,1948

Aug. 16, 1949. v I I Q EMPER' 2;479, o11

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maentor attorneys Patented Aug. 16, 1949 MILK CAN COOLER Ralph D. Kemper, Springettsbury Township, York County, Pa assignor to York Corporation, York, Pa., a corporation of Delaware Application December 2, 1948, Serial No. 63,109

Claims. (01. 62-7) This invention relates to refrigeration, and particularly to a milk cooler for use on dairy farms.

Such coolers are used twice a day to cool the milk in can-s immediately after milking. The milk so cooled may be stored for varying periods in the cooler. Thus, there is a, heavy demand for refrigeration twice in each 24 hour period. This demand continues for an hour or less. Between these relatively short periods the demand for refrigeration is low but may be continuous.

The intermittent character of the refrigerative load has led to the adoption of cooler-s in which a small mechanical refrigerating unit operates for long periods or even continuously and in low load periods stores refrigerative effect by freezing water into ice which is melted during the peak load periods.

This scheme, which in principle has been Well known for a great many years, is desirable from a thermodynamic standpoint. Attempts to use it in farm milk coolers have resulted in cumbersome devices which were expensive to construct and. inconvenient to use, particularly as .to the placing and removal of the heavy milk cans.

The present invention ofiers a device in which the quantity of water stored is reduced to the practicable minimum so that the size and weight of the device are kept within reasonable limits. The can racks are low, so as to eliminate the necessity of lifting the cans very high, and the access door is practically coextensive with the front of the cabinet. Both the latter advantages are attained by using a shallow water-storage sump which occupies the entire horizontal area of the interior of the cabinet.

Since the water is showered over the cans during the peak load period, at least one pump is needed. It requires very little additional apparatus to shower the water also over the evaporator. This permits the use of a plate or coil evaporator of the type in which the liquid to be cooled is fed to a distributor and fioWs from the distributor downward over the heat-exchange surface of the plate or coil, an arrangement notably better than the submerged coils heretofore proposed. There is no risk of freezing up the pumps for the water in the sump cannot be frozen. Heat exchange is stimulated. Thermostatic control of the refrigerative unit is simplified and made more precise in action. The control of the showering of water over the cans can be exercised by a simple manually set time switch arranged to by-pass the thermostatic control. The ice block formed in low load periods is exposed to the air in the cabinet, and thermosiphon effects assure air circulation which gives goodrefrlgeration of the cans during storage periods, irrespective of water circulation.

Two embodiments, each having a capacity of four cans, will be described. They differ in that one uses two pumps while the other accomplishes similar results with one pump and a solenoid valve.

In the drawings:

Fig. 1 is a vertical section'on the line l--l of Fig. 2 showing the general arrangement of the cabinet and refrigerating unit.

Fig. 2 is a vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 1.

Fig. 4 is a simplified wiring diagram illustrating the control principle.

Fig. 5 is a perspective view showing the spray system arranged to be operated by a single P p.

An insulated cabinet 6 closed on all sides except the front, has a doorway in the front with a raised sill 1 which confines water in a sump 8 located in the bottom of the interior of the cabinet and coextensive therewith. The doorway is normally closed by a gasketed door 9. The top of the cabinet is closed except for an opening H, and this opening is sealed by the base plate l2 which supports all elements of the refrigerating unit, as will later be described.

The construction of the cabinet and the watertight sump follows accepted standards and illustration of such structural details is considered unnecessary.

Channel iron frame members 13 support angle iron skidways I4, which are alined with the top of sill I. This makes insertion of cans, such as can C, a very simple operation. The skidways guide the cans to positions between ported shower pipes l5 fed by a header l6 and arranged to direct sprays onto the shoulders of inserted cans. The showered water is drawn from sump 8 by pump l1 whose discharge is connected to header [8. The pump is driven by an electric motor l8. A bailie I9 is provided toprotect the motors from spray.

The spray pipes l5, header l6, pump I1 and motor l8 are all fixedly mounted within the cabinet 6 by brackets as clearly shown in the drawing.

The refrigerating unit supported by base 12 is of the compressor-condenser-evaporator circuit type. According to accepted practice a compressor, and the electric motor which drives it, are enclosed in a hermetic casing. The numeral 2| is applied to the casing to identify this conventional unit. Discharge line 22 leads compressed refrigerant from the compressor to condenser 23 and liquid line 24 conducts liquefied refrigerant from the condenser to the inlet at the bottom of a plate-like corrugated evaporator 25. Any appropriate expansion device may be used to control flow of liquid refrigerant into the evaporator, and no attempt to illustrate this conventional detail is made. A suction line 23 leads from the top of evaporator 25 to the intake of the compressor. A motor 21 drives a fan 23 to cool condenser 23.

The motor-compressor 2I, condenser 23 and fan motor 21 are mounted on the upper side of base I2. The evaporator 25 is mounted in frames 23 pendant from the lower side of base I2, and is spaced a moderate distance from the-side wall of the cabinet 6.

A second pump 3| driven by motor 32 draws water from sump 8 and discharges it through pipe 33 and valve 34 to the distributor 35 by which the pumped water is distributed along the top of the evaporator in such a way that it flows in a film downward in contact with the evaporator, or with the ice film which tends to form thereon. The evaporator is operated at a sub-freezing temperature. Clips 36 are used to assist in retaining the ice mass on the evaporator.

The valve34 is so constructed that it can be only partially closed. Normally it is wide open, but in starting up the plant the valve is partly closed so as to limit the rate of flow of warm water over the evaporator. This protects the refrigerating system against overload.

The pump 3|, motor 32, pipe 33 and distributor 35 are supported by the cabinet 6, and pipe 33 extends between the cabinet wall and the evaporator 25. Preparatory to removing the refrigerating unit from the cabinet, base I2 is slid slightly to the left (as viewed in Fig. 1) to carry evaporator 25 clear of distributor 35. The unit may then be lifted vertically, without detaching the distributor 35.

A thermostatically operated single pole, double throw switch 31 is mounted on bas I2. The thermostatic bulb which actuates the switch is connected thereto by a capillary tube 33 and is shown at 39 (see Fig. 2) mounted at the lower extremity of the evaporator and spaced therefrom so as to be affected by the ice mass. The parts are so arranged that the switch contactor closes against the on" contact until the evaporator is adequately iced and then shifts to the "oii contact and remains there until thawing starts. The position of the bulb 39 determines the degrees of icing up and thawing which will cause the switch to shift.

A time switch 4| is mounted on base I2 as shown in Fig. 1. It is of the type which may be manually closed and when closed remains so for a definite number of minutes and then opens.

The diagram, Fig. 4, shows the principle of control. The power lines are shown at 42 and 43. If thermostatic switch 31 is on the on contact, the compressor unit 2|, fan motor 21 and pump motor 32run. This is the condition for icing up the evaporator. Eventually the evaporator will become adequately iced up and switch 31 will shift to the off contact stopping motors 2|, 21 and 32. Under control of the evaporator icing switch 31 will turn these three motors on and of! to maintain the iced condition.

Regardless of the position of switch 31 closure of switch U will cause all four motors I3, 2|, 21 and 32 to run.

The unit is started up initially with valve 34 6 partially closed. After the water is chilled and ice starts to form on the evaporator the valve is opened wide and remains open as long as the unit continues in use.

All that the operator does is to open the-door, insert the cans, close the door 3 and close switch M. The switch is adjusted to remain closed long enough to assure the proper chilling of milk in the cans. In this phase of operation the evaporator will be partly or even wholly de-iced. When switch 4I opens, the motor i3 stops, but motors 2I, 21 and 32 continue operating until the evaporator is iced sufllciently to shift switch 31. The cans can be removed at any time after switch 4I opens. They will be kept refrigerated by circulating cold air as long as they remain in the cabinet.

Fig. 5 shows an arrangement which substitutes a solenoid valve for motor I3 and pump I1. In this view parts analogous to parts in Figs. 1-3 25 are given the same reference numerals increased by 100. A pump I3I driven by motor I32 draws water from the sump and delivers it through valve I34 to Baudelot distributor I35. A valve 44, biased to close, controls flow to header H6 and spray pipes II5. A solenoid 45, when energized, opens valve 44. Solenoid is connected precisely as motor I3 is shown connected in Fig. 4. Opening of valve 44 has the same effect as operation of pump I1.

The first arrangement is preferred because two pumps operated as they are needed are better than a single large pump which must be operated for long periods at part capacity.

The sump 3 should be proportioned to hold somewhat more water than is necessary to ice the evaporator. Some water must be left in the sump in the liquid phase, for otherwise thawing flow could not be started. A large excess serves no useful purpose and requires the skidways I4 to 45 be set needlessly high.

What is claimed is:

1. The combination of a thermally insulated cabinet having in its lower portion a water retaining sump and can-supporting racks; a refrigerating unit of the compressor-condenser-evaporator circuit type having its evaporator mounted in the cabinet above the sump and arranged to maintain the evaporator at a sub-freezing temperature when the compressor operates; can sprayers for showering water on cans supported on said racks;

a distributor for flowing water over the evaporator and thence back to the sump; electrically operated means including at least one electric motor-driven pump arranged to draw water from- 80 the sump, said means being controllable to deliver water to the distributor alone, or to both the sprays and the distributor; an electric motor for driving the compressor of the refrigerating unit;

a thermostatic switch responsive to a. predetermined degree of icing of said evaporator and controlling said electrically operated means and the compressor motor to operatethe compressor and deliver water to the distributor whenicing of the evaporator isbelow said predetermined degree and suspend such operation at other times; and

an independently operable switch effective when closed to operate said electrically operated means so as to deliver water both to the sprays and to the distributor.

2. The combination deiined in claim 1 in which the independently operable switch is effective when closed to operate also the compressor motor and is a time switch of the type which is normally open, can be manually closed, and when closed automatically opens after a predetermined time interval.

3. The combination defined in claim 1 in which the electrically operated means comprises two electric motor-driven pumps one connected to deliver to the sprays and the other connected to deliver to the distributor and the thermostatic switch controls the compressor motor and the sec ond named electric motor-driven pump to stop and start them in unison; the independent operable switch being connected to operate both motor-driven pumps and the compressor motor, when said switch is closed.

4. The combination defined in claim 1 in which the electrically operated means comprises an electric motor-driven pump connected to deliver to the sprays and to the distributor, and a normally closed, electrically opened valve interposed in the connection to the sprays; the thermostatic switch being connected to stop and start the compressor motor and the motor-driven pump in unison, and the independently operable switch being connected to open the normally closed electrically opened valve and operate saidcompressor motor and motor-driven pump, when said switch is closed.

5. In a milk cooler, the combination of a thermally insulated cabinet having a water-retaining sump in its lower portion, and can racks arranged to drain water to said sump; a freezing unit of the compressor-condenser-evaporator circuit type arranged with its evaporator in said cabinet, ofiset laterally from said can racks and positioned in a generally vertical plane above said sump so that water draining from the evaporator will flow to said sump; pump means for delivering under pressure water drawn from said sump; spray connections for discharging water delivered by said'pump means against cans supported by said racks; a distributor for causing water to flow in a film over said evaporator and over the ice coating formed thereon; and controlling means for said freezing unit and pump means adapted to establish selectively three operating conditions in which respectively (1) the freezing unit is operated and water is pumped to the distributor to accumulate reserve refrigeration in the form of ice, (2) the freezing unit is operated and water is pumped to the sprays and distributor, to apply both the reserve refrigeration and the output of the unit to the delivery of a refrigerated spray, and (3) the freezing unit and pump means are shut down and refrigeration of the interior of the cabinet is sustained by thermo-siphon flow of air within the cabinet in contact with an ice coating on the evaporator.

RALPH D. KEMPER.

REFERENCES CITED The-following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 2,256,971 Chamberlain Sept. 23, 1941 Chamberlain July 31, 1945

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