|Publication number||US3585813 A|
|Publication date||Jun 22, 1971|
|Filing date||Mar 28, 1969|
|Priority date||Mar 28, 1969|
|Publication number||US 3585813 A, US 3585813A, US-A-3585813, US3585813 A, US3585813A|
|Inventors||Hansen Charles C, Lonn Harold J|
|Original Assignee||Refrigerating Specialties Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (9), Classifications (13)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 1,408,744 3/1922 Keen etal Inventors Charles C. Hansen Hlnsdale; Harold J. Loun, Lombard, both of, Ill. App]. N0. 811,316 Filed Mar. 28, 1969 Patented June 22, 1971 Assignee Refrigerating Specialties Company Broadview, lll.
SELF-CONTAINED PORTABLE COOLER References Cited UNITED STATES PATENTS 1 13,sss,s13
Primary Examiner--William F. O'Dea Assistant Examiner-J. D. Ferguson Attorney-Harbaugh and Thomas ABSTRACT: A self-contained, portable, refrigerated shipping container in which the working temperature of the shipping compartment is provided by gravity flow of a volatile liquified refrigerant, or forced flow of a nonvolatile liquid refrigerant, in a closed circuit as regulated by a liquid flow control valve that is controlled with respect to temperature or refrigerant pressure changes whereby heat is removed from the working compartment to a heat sink compartment that is chilled by a fluid or solid stored therein that has an effective temperature below that of the working compartment. Preferably the valve for purposes of miniaturization and great sensitivity has a sinuous land of substantial length defining a port area whose major dimension is fractionally less than the diameter of a circle whose circumference has the same length.
SHEET 1 [IF 2 CHARLES C. HANSEN BY HAROLD J. LONN SELF'CONTAINED PORTABLE COOLER BACKGROUND OF THE INVENTION Although the shipping container of the present invention can be used easily with lay-in external super chilled sources of refrigeration for standby operation either for short or long periods of time, and it is an additional advantage that it can, it is primarily concerned with a self-contained, refrigerated shipping container that from the time that it is packed until it is delivered, it can be handled by carriers as though it were an unrefrigerated package.
I-Ieretofore, containers for goods requiring refrigeration not only undergo all of the handling problems to which portable containers are subjected but they also include proper positioning and fastening for umbilical refrigeration connections and additionally must withstand temperatures of -30 F. at high altitudes and 200 F. under cleaning conditions. They also are subjected to a varying wide range of external atmospheric pressures, and acceleration, deceleration or tipping forces. They must also perform normal operation at all times, or, recover normal operation afler such has been disrupted by unusual temporary conditions. Moreover, and often the most important, is the factor that the temperature must be closely regulated in the working compartment under wide and rapid changes in the environmental pressures and temperatures.
INVENTION In the present invention, standby and umbilically connected refrigeration is not necessary, yet wherever standby refrigera tion is present, such can be economically utilized if desired without liquid flow connections for long periods of time. Otherwise, when a container embodying the invention is packed or in transit, it is a completely self-contained refrigerating container without any need to rely upon a particular type or location of a refrigeration supply aboard a carrier, nor is it dependent upon particular carrier equipment, nor does it require special handling.
At least two thermally insulated compartments are provided, either vertically or horizontally spaced. One continuous conduit which is less than filled with a volatile liquid refrigerant, is mounted in the container with a plurality of inclined conduit turns that form a condenser-type coil in the upper compartment where a super chilled material can be stored, and, another group of coils spaced and insulated therefrom form an evaporation-type coil in the lower or working compartment or compartments where liquified gas vaporizes with absorbed heat. Vapor refrigerant chilled and liquified in the upper coil collects and flows downwardly to the bottom of the lower coil as regulated by a liquid flow control valve between them that is controlled by pressure differential across the diaphragm. Flow is induced in either one of two ways, or both. In one way, by gravity upon the liquid in the system, or by forced circulation where necessary. The pressure differential for the diaphragm involves the relative refrigerant pressure in the system on one side and the external pressure on the other side which can be either atmospheric pressure or an applied pressure that is exerted either by a temperature bulb pressure or a compressed pressure that is sealed in the regulator bonnet.
More particularly, the volatile refrigerant in the conduit of the preferred system is under a variable internal pressure due to overall temperature changes yet there is only a slight pressure differential developed across the valve and this is due to relative hydrostatic pressures on opposite sides of the valve. The latter induces flow of liquid through the valve when opened but desirably is not enough to effect the opening of the valve for proper temperature control in the work compartment.
With respect to valve operation, since the pressure varies very little, only a matter of a column of 2 to 20 inches of static pressure of the liquid refrigerant in the system from one coil portion of the circuit to any other coil portion, a regulator that is externally subjected to constant atmospheric pressure will open quite accurately in response to changes in the system pressure which is a function of the average temperature and heat load in the working compartment and the average temperature and degree of heat exchange in the super chilled compartment with the condenser portion of the circuit. Consequently, if the heat exchange conditions are constant, then the pressure in the system will be a function of the temperature and load of the working compartment.
Also, since the hydrostatic pressure differential across the valve varies very little, a temperature bulb which is essentially a sealed discrete heat expansion system filled with vapor or liquid can operate the valve with sensitivity and accuracy to open it at any adjusted point where a bonnet spring and atmosphere are set to just close the valve when a predetermined temperature is attained in the control compartment.
Thus, with a sensitive control and a low pressure differential across the valve, the pressure regulator must open as much as possible during heavy loading of the control or during warm conditions, such as startup pulldown, so that the refrigerant circulation flow rate will be at a relatively high rate to increase the amount of heat exchange cooling occurring in both compartments. With the slight pressure drop at the valve, this requires a large flow area valve which generally is a large valve which has inadequate sensitivity. If the load is less, or when the working compartment reaches a more desirable low temperature, the refrigerant pressure drops, the temperature bulb pressure reduces and the regulator partially closes, it being noted that the pressure drop across the valve is only slightly higher due to the increased amount of chilled refrigerant in its liquid phase in the upper portion of the condenser of the system.
Progressive closure results in reducing circulation of the refrigerant from the chilled compartment and reduces the refrigeration effect in the working compartment to more closely approximate that required to maintain the desired temperature.
In the preferred embodiment the regulating valve is comparatively quite small to conserve weight and space, yet it is unusually sensitive with a large flow area in that the effective valve flow area rapidly increases or decreases with very small lineal movements of the small valve head. The land of the valve port may be circular and will work but preferably is sinuous, having a multiradii contour in which its flow area is greater than a circular port having any one of said radii. Thus, as a matter of possible comparison the effective flow area of the valve seat with the same slight lineal movement potentially is equivalent to the flow area of the valve outlet or inlet opening that communicates therewith and even greater than a much larger conventional design round seat port valve. This provides for sensitivity and maximum flow with a temperature bulb, especially under conditions in which gravity alone induces flow in which there is only slight pressure drop across the valve. The temperature bulb correspondingly moves the valve with small increments of temperature change but with large changes in flow area. The flow normally, in direct temperature operated valves, would be comparatively low at any temperature level but with the present invention a much larger and rapidly increased flow area for slight changes in temperature are provided to take care of heavy loading or other conditions involving rapidly changing critical environmental facmm.
In addition to sensitivity gain, the sinuous valve seat decreases the effect which valve seat pressure drop has upon valve setting because this effect is a function of root cross-sectional area which causes forces to be exerted along the axis of valve movement. Since such forces are proportioned to valve cross-sectional area, the use of a sinusoidal seat design reduces such cross-sectional area for a given amount of valve flow capacity, thereby minimizing the disturbing axial forces which result from valve seat pressure drop.
In view of these considerations the objects and purposes of the invention will be better understood in that the invention provides a very simple, selfcontained refrigeration system and control device which can accomplish the desired temperature control with precision in several embodiments which are either adapted to particular environmental conditions or are used by particular shippers.
This object includes a simple valve modification which will provide selective control at two or more temperatures for various loads or products which require different temperatures, and can also be shut off to conserve refrigeration when desired.
The invention also contemplates the use of pump recirculation of liquid to augment gravity flow of a volatile liquid which bubbles as previously described.
A further object of the invention is to achieve a wide open characteristic of the valve with great sensitivity at heavy load conditions for an otherwise simple pressure regulator and in doing so to achieve a precise degree of throttling under light load conditions to closely maintain a predetermined temperature even if the heat exchange in the chilled compartment lessens.
Another object is to provide a valve seat design which will, for limited seat openings of 0.005 inches to 0.010 inches, provide liquid flow passage area which greatly multiplies the flow over that of a simple circular seat design of like diameter, thereby facilitating higher liquid flow rates under conditions of limited valve opening due to a very slight temperature change of the temperature bulb.
Another object is to provide a direct temperature operated valve of nonbalanced single seat design which has a minimum area exposed to seat pressure drop forces, thereby minimizing the effect which such pressured drop has upon the control temperature, or pressure in the case of a simple direct operated pressure regulator.
A further object of the invention is a temperature control valve for use with forced circulation in closed circuits to achieve an opening point and an opening ability for a valve which will be a function of the compartment temperature alone and not of any circulation forcing pressure of liquid refrigerant that may vary.
Another object of the invention is to provide a control valve design, including modifications, which will operate reliably despite occasional exposure pressures as high as 500 p.s.i.g. and as low as p.s.i.g.; temperatures as high as 220 and as low as 40 F.; fluids which contain no lubricant and which have very little lubricating ability; multipositioning of container; heavy vibrations; and, possibly very rapid changes in temperature during an expected hot cleaning operation of the compartment.
Another object is to provide a main valve which requires no pressure drop across its valve seat to remain in open position and facilitate gravity flow under extremely low pressure drop conditions. These being among the objects of the invention, other and further objects will be apparent from the description and claims relating to the drawing herein, wherein like numeral refer to the parts and in which:
FIG. I is a perspective view of a refrigeration portable container for storage and shipping embodying the invention;
FIG. 2 is a sectional view taken on line 2-2 in FIG. 1;
FIG. 3 is an enlarged sectional view of refrigerant flow control valve shown in FIG. 2;
FIG. 4 is an enlarged vertical medial sectional view of a two temperature setting modification of the bonnet portion of the embodiment;
FIG. 5 is an enlarged vertical medial sectional view of a modification of the valve port construction of the embodiment shown in FIG. 3 whereby the valve is controlled in relation to the temperature of the refrigerant in the system;
FIG. 6 is a view similar to FIG. 5 showing a modification where pumped fluid can be used as a refrigerant; this version has a balanced seat design to minimize the effect at pumping pressure and quantity changes;
FIG. '7 is a perspective view of the valve seat construction that can be used in FIG. 3;
FIG. f; is a cross-sectional view taken on line 8-8 of HO. 3; and
FIG. 8A is a view similar to and is a modification of the configuration construction shown in FIG. fl and FIG. 7.
Unless otherwise defined, suffix letters for numerals in the drawings identify modifications of structure already described in the specification.
Referring now to FIGS. 31 and 2 in further detail, a gravity recirculating liquid-vapor-type refrigeration system It) is illustrated in connection with a shipping container 12 having thermally insulated sides 114i defining an inside space that is vertically divided by a thermally insulated cross wall to, into an upper super chill compartment 18 and a lower refrigerated or working compartment 20. The top side MT has an opening 22 closed by a thermal cover 24. Dry ice 26, water ice, other cold eutectic solid, or cold liquid such a nitrogen or an evaporator (not shown) ofa standby system can be placed, poured or laid in the upper compartment as a source of refrigeration. An opening 330 closed by a door 28 is provided in the front wall 14F for access to load and unload the working compartment with articles to be refrigerated. l-iandles and hooks (not shown) may be provided as desired for handling the container including skid buttons 32 on the bottom side MB.
Although two or more coils of like function can be connected in parallel in the refrigerating system at connections 430A and 32A (FIG. 2) the invention is illustrated with a single condenser coil 3d in the upper compartment and a single expansion coil 36 in the bottom compartment. Control valve 414 can control several expansion coils in parallel. It is also possible for one condenser coil to feed several control valves Ml, each controlling different refrigerated spaces of different temperatures. Also, more than one condenser coil can be located in the same super chill compartment 118.
Although both coils may be plate type, made of tubing or embossed sheet metal stampings, having top and bottom ends, the coils are illustrated as made of reversely bent horizontal turns of tubing with the top turns of the upper and lower coils interconnected by a vertical portion 4th and the lower turns interconnected by a vertical portion 42 which includes a flow control valve 4d. The valve is controlled by a temperature responsive means as having temperature sensitive bulb 47 disposed in the working compartment 20.
There is enough volatile liquid refrigerant such as Freon I2, sealed in the system to at least partially fill the lower coil 356 with liquid at low temperature and preferably till the lower turns of the upper coil with liquid so that flow of refrigerant in the tube is in the direction of the arrows as hydrostatically impelled by gravity and levitation in which refrigerant warmed or vaporized in the lower coil 36 increases the volume-to-weight ratio of refrigerant in the lower coil while the refrigerant chilled and condensed in the upper coil 35 i decreases the volume-to-weight ratio of the refrigerant collecting in the bottom of the upper coil whereby the weight imbalance of the liquid in the upper coil and the levitation of vapor in the lower coil motivate the flow of refrigerant as indicated. In this connection it will be noted (FIG. 3) that if the valve is closed, there is a pressure drop between the inlet 4% and outlet 50 of the valve Ml caused by an increased gravity pressure of liquid backing up in the condenser coil. This urge to increase the flow is controlled by the valve and thereby the refrigeration of the lower compartment 20 is controlled by the valve despite variation in condenser liquid head.
Referring now to FIG. 3 a preferred embodiment of the flow control diaphragm valve 54% is shown wherein the bonnet side of the diaphragm 52 is subjected to ambient pressure in the bonnet 5 through an opening 49 and the other side is subjected to refrigerant pressures exerted at both the inlet 48 and outlet 50 and if the ambient pressure for the bonnet is con stant the regulator will be opening in response to changes in the system pressure since the pressure cannot vary much from one portion of the refrigerant circuit to any other portion of the circuit.
It will be noted however that the atmospheric pressure can also vary if the container is to be airborne and the wider the pressure differential between ambient and refrigerant pressures the wider the valve will open. Thus, the lower will be the controlled temperature when airborne unless the bonnet is isolated or pressurized.
Assuming use of the container where atmospheric pressure remains substantially constant but variations of the magnitude of 5 p.s.i. can occur, the regulator 44 as shown in FIG. 3 comprises a body having an inlet bore 56 and an outlet bore 58 separated by a central body portion 60. The central body portion has a threaded recess 62 on its upper face to receive a valve port member 64 and is surrounded with an enlarged recess 66 that is in communication with the outlet 50 through passage 66. The enlarged recess is bordered by a flange portion 70 having a marginal annular planar portion 73 and a circumferential thread 72. The bonnet is provided with a shoulder 76 and a mating thread at 72 on its bell edge 78. The marginal edge of the diaphragm 52 is disposed between two gaskets 74 and these elements are clamped in sealing relationship against the planar portion 73 by the shoulder 76 to provide a bonnet chamber that may either be sealed from or exposed to ambient atmospheric pressure.
The bonnet is also threaded at its closed end to receive a spring adjusting screw 80 and lock nut 81 with a moisture seal 82 press fitted into the threads. The screw engages an intermediate adjusting screw plate 84 to compress a coiled bonnet spring 86 whose other end engages a lower spring plate 88 centrally spherically dimpled at 90 to engage in a rocking relation in a conical recess 92 in the upper face of a diaphragm follower 94. The diaphragm follower in turn rests on the diaphragm 52 and is disposed concentric with the valve port member to close it. For this purpose the diaphragm is preferably of hard flexible metal possibly plated with a hard metal to resist erosion by the valve port member or sandwiched to a separate metal faceplate which seats against the port.
Said lower spring plate 88 may be a dished bimetal disc constructed with the upper layer of metal 96A having the higher coefficient of heat expansion in order to lessen its dished relation and decrease or counteract the compression effect of a warm spring 86, or a heat-expanded atmosphere sealed in the bonnet, and thereby increase the opening sensitivity of the valve or its otherwise expected opening distance when the valve is warm, yet maintaining constant the effective valve closing action of the spring 86 with increasing sensitivity in a predetermined or critical temperature range.
A suitable upstanding cylindrical guide boss 98 is disposed in the recess 92A and has a bore 96 through the central portion 60 to receive a thrust pin 100 therethrough that is rounded on its lower end to extend into a backcap cavity 102 on the lower face of the body 60. The backcap cavity is recessed at 104 to receive a diaphragm follower 106 and engages and reciprocates the pin 100. A shallow recess at 108 bordered by an annular flat surface 110 that marginally terminates in an annular flange 112 to receive the diaphragm 114 of the temperature bulb 47 and actuates the diaphragm follower 166. The diaphragm provides a sealed chamber 116 above it that is subjected to the refrigerant pressure at the inlet 48 by way of the clearance space around pin 100. The diaphragm is assembled on a retainer cover 118 having a shallow recess 120 and this assembly is marginally secured in place in sealed relationship by the annular flange 112 being welded or swaged inwardly marginally therearound under pressure and then soldered to form the sealed compartment 116 above the backcap diaphragm 114. The temperature bulb 47 is part of the back cap assembly and is connected in communication with the back cap compartment 120 through a passage 121 by a tube 46 silver soldered in place. The compartment, tube and bulb are filled with a conventional thermal-responsive liquid and vapor charge whereby the diaphragm 114, follower 106 and pin 100 are positively driven upwardly as the temperature bulb is warmed above a predetermined temperature. The areas of the two diaphragms 52 and 114 are preferably about equal in order to balance out the effect of refrigerant pressure in the valve.
The increment of linear movement per degree of temperature change is not great with temperature bulbs and diaphragms for most commercial purposes relays energized by microswitches are employed to utilize them. in the present invention for portability with minimum equipment, small increments of linear movement of the valve control diaphragm are converted into large changes in the flow area of the valve.
Reference is made to FIGS. 7, 8 and 8A in which further details are shown of modified constructions of the valve port member 64 similar in shape to a pipe bushing having a hexshaped head 125. The head is provided preferably with a planar upper surface 127 and has an externally threaded shank portion 131 deflning the flow passageway 65 therethrough that is received in the threaded opening 62. The planar surface 127 is provided with a short section 133 of a noncylindrical sleeve extrusion serving as a port land of appreciable height which at one end is silver soldered, copper brazed, welded or cemented, as at 135 to the planar upper sur face around the flow passageway 65 and is lapped at the other end to provide a semisharp valve seating edge 137 closing against the lower face of the diaphragm 52 or its sandwich layer of plating or metal part.
The cross-sectional shape of the thin wall extruded section 133 is sinuous or pseudosinusoidal in that its radial dimension varies with or without regularity between major and minor radii indicated by arrows 141 and 143 (FIG. 7) and its included cross-sectional area is less than that of a circle having the major radius, or conversely, greater than a circle having the minor radius. In FIG. 7 the valve seating edge 137 of the valve port member 64A is serpentine with rounded turns 145 where the land portions interconnecting the reversely curved portions approach radial lines. In FIG. 8A the turns 145A are sharp with the intermediate portions 151 straight with acute internal angles. In FIG. 8 the outer portions 153 are sections of large-sized circles and adjacent ends are radially connected by straight sections 155 whose inner ends join to form outwardly directed acute angles. These forms are representative of other contours which are a compromise between total lineal length and height of the section. The essential consideration may be explained in relation to providing with minimum valve movement the maximum flow area within the capacity of the conduits leading to and from the valve.
Assuming that minimum lineal valve movement to attain reasonable maximum flow in the system is the relationship desired, the flow area that is to be attained within the limits of the system is divided by the maximum inducible movement of the diaphragm and the quotient is the circumferential length of the seat on the valve port land. The configuration of the seat and its minor dimension, which generally is the diameter of the circular flow area, is then related to the spaces between the inner convolutions as at 161 which provide a flow area at their narrowest spacing adequate to supply the flow area opening that occurs between the valve members at the seat convolutions radially beyond the narrowest spacing. Thus, not only the actual length of the valve port land but the height of the land can be determined in relation to any cross-sectional configuration that is easiest to fashion with tools at hand provided the total spacing multiplied by land height between adjacent inner curves of the land at their closest points provides a flow area that equals or exceeds the flow area radially therebeyond between the valve and valve seat during initial opening movements of the valve. With this consideration it will be noted that as the inflow area and outflow area remain approximately equal and equal to or in excess of the multiple of circumferential seat length by maximum inducible diaphragm movement flow will be a function possibly of valve movement. The inflow through the port region may be more restrictive than the outflow where an expanding vapor or gas is increasing its volume appreciably as it passes through the circumferential valve seat opening.
By way of further consideration, flow is inversely proportional to the flow resistance, referred to as R through a valve seat. R, is composed of the resistance to flow through the inlet 65 to the valve mt referred to as resistance R,, resistance to flow across the seat bead l3? referred to as resistance R,,, and resistance to flow from the seat bead through the outlet 68 of the valve referred to as outlet resistance R,,. For flow in through the center of the seat and radially outward as shown in MG. 6, the inlet resistance is composed of the throat resistance through the small center diameter as at M3 (FlG. '7) of the seat R plus the resistance of the channel inlets as at 141 to the seat bead R as at 65; the outlet resistance is composed of the resistance of the channel outlets (R,,) from the seat bead plus the resistance which occurs in the peripheral region, R, as at K63 (FlG. ii). The total resistance is derived as follows:
In a typical simple, raised, circular seat bead with flow occurring between the diaphragm (or a flat disc moving with the diaphragm) and the seat bead with h indicating relative axial distance, the major resistance, due to a very small diaphragm movement compared to bead diameter, is R,,; consequently, R, is approximately equal to it, since R R R, and R, are relatively very small. Where the bead is a sinuous, planar edge as described herein, R is relatively similar in value to R R R, and R, unless care is taken in the seat design to minimize these values, such as increasing height h to h, of the sleeve 1133. The limiting factor eventually proves to be R a design proportion must be achieved in which R, is about two or three times R c in order to retain flow control at the seat head in relation to diaphragm movement. Then, R R, and R, should be made equal to or less than R Another important consideration when opening the valve is the ratio of minimum flow area across the seat head to the cross-sectional area of the sinusoidal seat area as projected at the diaphragm. For flows which cause noticeable pressure drop across the seat head of any direct operated pressure regulating valve, the deviation from control pressure is affected adversely by the cross-sectional area, which tends to close the flow opening of a simple upstream pressure regulator of the direct operating design. For a given flow capacity, the sinusoidal seat bead design of this invention minimizes the cross-sectional area and thereby minimizes such control pressure deviation for a simple unbalanced seat type of pressure regulator as shown in FIG. 5.
Now in minimizing control pressure deviation where:
V= Velocity, M Mass flow rate, v specific volume, A cross-sectional area. 0, i, b, o, p are flow regions already considered in relation to resistance.
a is the flow region at the valve end of the conduit 65.
b is the laterfl flow region at the valve bead 1137.
i is the lateral flow region 1511 between c and b.
a is the outlet flow at the major diameter of the bead 1163. p is the flow region 6% beyond 0.
D entry (or exit) diameter through center of seat port.
D outside diameter of seat port.
la normal maximum lift of diaphragm above planar seat face.
I, length of seat bead 1137 mass flow equation, and more mental flow area across seat bead A A h,, A l,,. Total area of flow across bead A 12,, d1, which is the same lift of diaphragm. Then For constant specific volume flow, such as is common for liquids or for gases at low-pressure drops, the velocity at any region is inversely proportional to the area. Since the flowcontrolling region must be that at the seat bead, all other velocities should be small in comparison. Thus, assuming 1% V V V V or V,, then 2.4 A,., A A or 14,.
As A, is maximized by means of a lengthy sinuous path, the above relationships show that typical designs should be such that A .4 A, and A, must be made as generous as possible. In many design considerations, the starting available limiting dimension is D,.m which determines A as A, 'n' D /4. From this would be evolved an appropriate sinuous path, whose length l times maximum available diaphragm lift h equals A which would be at least 2 times A,.. Then the appropriate entry and exit areas A A1,, and A, would be developed by varying such dimensions as h, or It and varying the wave length and wave path (but not changing the already established sinuous length path l Maximum land height need only be one-fourth, or less, than the radius of a circular flow conduit of equivalent flow capacity. And, if the minimum dimension of the elongated land equals the diameter of the conduit, then the length of the seat land can be multiplied by the sensitivity factor desired and the initial opening range of the valve will have that sensitivity. This sensitivity will not diminish until maximum flow is approached since the depth of the land between its radial portions will supply nonlimited flow capacity during the initial range of opening and thereafter additional opening progressively provides in a lineal direction additive flow area space.
On the other hand if the land height is more than one-fourth of the circular flow area radius, the full flow supply will be supplied essentially at the level of the land until the opening is accomplished at a point that is less than said one-fourth the radius divided by the sensitive factor. Thus the higher the land, the greater and more constant is the sensitivity factor throughout the valve opening movement.
in these considerations the simple modification shown in FIGS. 3 and 8 illustrates a desirable high sensitivity up to a full flow capacity of the bore 65. its configuration includes comparatively sharp corners 145B and the land 157 at the minor dimensions and from adjacent ones of these corners the lands extend substantially parallel as at 167 to the outer dimension where they terminally join in a moderately curved outer portion 153. In this configuration, twenty radial sides 167 of the ten convolutions equal three circumferences of the bore 6-5 and the ten peripheral sections 153 total one circumference. Accordingly, the sensitivity multiplication factor is 4X in which the total length of the land is divided by the circumference of the circular flow area of the bore 65. With the area of the bore 65 represented by the equation A=1rll and a corresponding valve opening flow area represented by A (Zn-R) Z, then Z 12/2, as related to the radius, or
Z 2R/4, as related to the diameter, where Z is the opening distance for full flow of the valve port 65.
with the effective flow area of the land 157 being four times that of the bore 65, as noted above, then Z R/ 8 as related to the radius, or
Z R2/ 16 as related to the diameter.
Therefore, since is R equals lineal movement for the full flow opening of a circular port, the lineal valve movement for this embodiment for full flow is V1 R, and it will be observed that the radial length of the land portions 167 having a radial dimension of the convolutions 157 is an index to the sensitivity of the valve action.
In F IG. 8 a further feature of interest is the relation that the radial extremities of the convolutions overhang the edges of the annular planar surface 127 for increase land 167 length and the overhanging portions are appropriately sealed by the fillets of silver solder 1171. These enable a reduction of the axial height of the land since the planar surface 127 obstructs much less the flow area 1161 between convolution portions E67. Thus, the flow areas are much less restricted for a given size lineal flow area. This also indicates that the lands may be of folded sheet metal, as well as extrusion sections, or they can be formed by die forging, deep chemical etching or electrical cutting. in any of these it is desirable to grind and lap the port edge after the element 64 is fashioned.
The notches are to receive a spanner wrench for tightening the valve member in place. Where a hexagonal bushing is used such as in H6. 7, Spanner notches are not required because of the existence of wrench flats 125.
ln H6. 5 the regulator body is constructed to omit the temperature bulb 47 and rely upon the differential between desired and actual refrigerant pressures to operate the valve. If the ambient temperature surrounding the container is reasonably constant, then for each system having identical components, insulation value, refrigerant charge, and condenser heat sink capacity, there will be a system pressure which is associated with an interior compartment temperature. By setting the simple pressure regulator to start closing of this system pressure, a relative constant compartment interior temperature can be maintained. During heavy loading of the compartment due to pulldown after a warm condition, entry of warm product, or location in a very warm ambient, the system pressure will rise somewhat, thereby causing the regulator to open and provide more refrigeration. While not as versatile or sensitive as the temperature regulator of FIG. 3, the pressure regulator of FIG. 5 will provide considerably better compartment temperature constant than would be possible with no control in the system at all, such as the use of a mere orifice in the inside pipe vertical portion 42. Since this differential provides adequate power to actuate the valve a valve port member 648 having a regular circular land and bore 65 may provide adequate sensitivity. This regulator is characterized by the absence of the backcap diaphragm of HO. 3, there being no backcap assembly required.
In FIG. 4 a modification of FIG. 3 is illustrated in which the bonnet 54A is sealed from ambient pressures and has a dual temperature capability. The upper spring plate 84A is externally threaded at 175 to serve as spring adjusting plate and has an opening 177 through it to receive a plunger 179 that operates a secondary spring. The plunger is slidably sealed in the bonnet cap 181 by an O-ring 183 in a groove 185 and a lever cam 187 pivoted on a yoke 189 on the bonnet cap actuates a secondary spring 191 to vary the pressure at which the valve will open. A tire valve 193, sometimes referred to as a Dill valve, is mounted in the wall of the bonnet by which the bonnet pressure on the diaphragm 52 may be a fixedpressure for containers that may be airborne. In lieu of valve 193, a capillary tube may be used to charge an inert gas into the bonnet of FIG. 3 in which case no spring 86 would be necessary nor would spring adjusting screw 80 exist as a nonhermetic bonnet penetration. Regular and sensitive valve port members 6 38 and M are interchangeable with this embodiment.
ln FIG. 6 the backcap construction shown in H0. 3 is modified to provide a temperature modulated valve for a pumped refrigerant such as nonvolatile brine in that the downstream pressure in outlet 50 is balanced out on corresponding facing peripheral areas of the two diaphragms 52 and l 14 through passage 103 and the upstream pressure is applied equally to facing central areas 197 and 195 of the respective diaphragms, as represented by the bore 65 and corresponding area piston 195 of piston 199 as sealed by an optional -ring 101 or outer seal leaving the bonnet spring 86 and the temperature bulb 47 to actuate the valve.
In this embodiment it should be noted that if the valve port member 64 of FIG. 8 is used for high sensitivity with the temperature bulb 47 the effective area of the piston 199 should be provided which matches the effective valve spring force pressure area of any of the multiradii port lands 64 described herein, their effective areas being slightly greater than that of the circular port land 65 shown in FIG. 6.
Having thus described the invention and several embodiments thereof it will be understood by those skilled in the art how the objects and advantages set forth are attained and how various and further embodiments can be provided without departing from the spirit of the invention.
What we claim is:
l. A self contained portable cooler means comprising a plurality of compartments thermally insulated from the atmosphere and from each other,
a closed refrigeration circuit including a condenser coil in one of the compartments and an evaporator coil in the other compartment, the upper portions of said coils being connected in open communication with each other,
a connecting conduit between the lower ends of the coils including a flow regulating valve having an inlet connected to the bottom of said condenser coil and an outlet connected to said evaporator. coil at a point below the level of the condenser coil,
said flow regulating valve having a housing defining an enclosed space,
pressure-responsive means separating said space into a valve compartment connecting the coils in series in said circuit through a valve port comprising a noncircular valve land defining a cross-sectional flow area greater than the crosssectional flow area of said inlet,
valve means carried by said pressure-responsive means in said valve compartment disposed in closing relationship with said land for opening said valve port under refrigerant pressure present in said valve compartment for widely differing fiow rates with small movements of the valve means,
resilient means for urging said valve means to close said valve port.
2. The combination called for in claim 1 in which said valve land defines a sinuous planar port configuration of varying cross-sectional dimension whose area is less than a circle having as its diameter a major dimension of the configuration.
3. The combination called for in claim 1 in which said valve land is an upstanding sinuous land having a major cross-sectional dimension substantially less than one-third its peripheral length.
4. The combination called for in claim 1 in which said valve land is an upstanding land defining a sinuous port edge having a length substantially greater than 1r times its major dimension.
5. The combination called for in claim 1 in which said valve inlet has a circular bore of a predetermined radius and whose valve land in communication with said bore comprises a planar port edge of sinuous form in which adjacent portions having a radial inward convergence defining between them an outwardly opening acute angle over a portion of their lengths.
6. The combination called for in claim 1 in which said valve inlet has a circular bore and a sinuous port land whose lineal length is more than 1r times the diameter of said bore.
7. The combination called for in claim 1 including means for pressurizing the bonnet compartment with a predetermined pressure different from an external ambient pressure.
8. The combination called for in claim 1 in which said spring means includes a temperature change responsive element reducing the valve closing pressure thereof at temperatures above a predetermined controlled temperature to facilitate opening of the valve.
9. The combination called for in claim 1 in which said housing defines a backcap space, and including a backcap diaphragm means separating said backcap space into a compartment in communication with said valve compartment and a backcap compartment,
temperature bulb means in communication with said backcap compartment, and
means driven by said backcap diaphragm means for urging the opening of said valve means.
10. The combination called for in claim 1 in which said housing defines a backcap space and including backcap diaphragm means separating said backcap space into a backcap compartment and a compartment in communication with said evaporator coil,
piston means interconnecting the two diaphragm means having an efi'ective area substantially equal to the effective area of said valve port exposed to the pressure of the refrigerant in said condenser coil, and
temperature bulb means in communication with said backcap compartment.
ll ll llll. A flow-regulating valve having a housing defining two compartments sealed from each other, one of which has a flow inlet and a flow outlet,
pressure-responsive means between said compartments and movable in response to a differential between the pressures in the two compartments,
valve means in said one of the compartments including a valve port element through which fluid flows from the inlet to the outlet comprising an upstanding land of appreciable height having a sinuous edge defining a planar port whose circumferential length is greater than 1r times its major sectional dimension, and
including a flat wall element carried by said pressureresponsive means, whose face engages said planar edge in variably closing relationship.
E2. The combination called for in claim 111 in which said wall is flexible.
113. The combination called for in claim l l in which said flat wall is a portion of said pressure-responsive means.
M. The combination called for in claim )13 in which the area of said flat wall enclosed by said land when said flat wall element engages said planar edge is less than an area of a circle having said major dimension as a diameter.
115. A flow-regulating valve having a body housing defining two compartments one of which has a flow inlet and a flow outlet,
pressure-responsive means between said compartments sealing them from each other and movable in response to a differential between the pressures in the two compartments,
valve means in said one of the compartments including a valve port element through which fluid flows from the inlet to the outlet and a port closure element for variably closing said valve port element,
said valve port element comprising an upstanding land of appreciable height having a sinuous planar edge defining a port whose circumferential length is greater than 1r times its major sectional dimension,
one of said elements being supported by said body housing and the other element by said pressure-responsive means for relative movement therebetween at a rate wherein full flow would be reached within a distance substantially less than one-half the radius of a circular passage determining said full flow.
l6. ln a flow-regulating valve having a flow control valve comprising valve means having a planar closing face, and
a valve member having a bore for the flow of liquid surrounded at one end by a land defining a sinuous planar port edge to be engaged by said planar closing face.
117. The combination called for in claim 16 in which said land is an extrusion section of appreciable height.
H8. The combination called for in claim 116 in which said planar closing face is one side of a flexible diaphragm subjected to variable opposing opening and closing pressures.
R9. The combination called for in claim 16 in which said port edge comprises straight line sections in which adjacent ones define acute angles between them.
20. The combination called for in claim J16 in which each convolution comprises two straight and substantially parallel lines and an included circumferential section joining their outer ends.
21. The combination called for in claim 16 in which said port edge defines sections having a radial dimension and these sections are joined together alternately by inner and outer curved portions.
22. The combination called for in claim 211 in which the land portions interconnecting the inner and outer curved portions approach radial lines.
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|U.S. Classification||62/223, 62/334, 251/61.3, 236/92.00B, 251/331, 62/384, 62/371|
|International Classification||F25D3/00, F25B25/00|
|Cooperative Classification||F25B25/005, F25D3/005|
|European Classification||F25B25/00B, F25D3/00A|