US3177670A

US3177670A - Thermoelectric refrigerator

Info

Publication number: US3177670A
Application number: US281863A
Authority: US
Inventors: Andrew P Boehmer; Boubene M Jaremus
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1963-05-17
Filing date: 1963-05-17
Publication date: 1965-04-13
Anticipated expiration: 1982-04-13
Also published as: SE307148B; FR1397625A; GB1056049A; DE1426927B1

Description

United States Patent 3,177,670 'llHEl'tF/HQELECTREC REFRKGERATUR Andrew P. Boehrner and Bouhene M. Jaremus, Barrington, llL, assignors to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Filed May 17, 1963, Ser. No. 281,863 14 Qiairns. (Cl. 62-3) This invention is directed to a thermoelectric refrigerator, and more particularly to such a refrigerator in which, although the freezer compartment and cooler compartment are thermally isolated with respect to each other, the thermoelectric assemblies which effect the cooling of these two isolated compartments are electrically connected in series.

It is usually desirable in a refrigerator to provide insulation around the freezer compartment to effect thermal isolation from the cooler compartment, because the cooling load presented by the freezer compartment is different from that associated with the cooler compartment. In the freezer compartment, for example, it is usually necessary to provide a temperature sufficiently lower than 32 F. to insure that water placed in an ice cube tray and inserted within the freezer compartment will be cooled to form ice. In the cooler compartment, the preservation of ordinary foods and liquids is generally effected by temperatures in the vicinity of 40 F. When the cooling apparatus has been operated for a time sufficient to reduce the emperature in the cooler compartment below 40 F., or any other reference temperature, the apparatus is generally put on low cooling, so that a lesser amount of heat is removed from the cooler compartment, and likewise a lesser amount of energy is required when the refrigerator is operating on low cooling. As the temperature in the cooler compartment gradually rises and exceeds the temperature at which a thermostat or other sensing means is set, the apparatus is returned to a high cooling operation in which more energy is supplied and more heat is removed from the cooler compartment in a given time period.

With the advent of practical and feasible thermoelectric cooling assemblies, compact refrigerators have been provided with thermally isolated freezer and cooler compartments. The most direct and simple method of supplying energy to such a refrigerator is to couple the thermoelectric module which removes heat from the freezer compartment in series with the one or more thermoelectric cooling modules which remove heat from the cooler compartment. However, with such an arrangement, it has been found that when the temperature in the cooler compartment decreases sufficiently and the apparatus is switched over from high cooling to low cooling, the decreased amount of electrical energy flowing through such series circuit has not been adequate to maintain the requisite freezing temperature within the freezer compartment.

It is therefore each primary object of the present invention to provide a thermoelectric refrigerator with thermally isolated freezer and cooler compartments, and in which effective operation is attained even though the thermoelectric assemblies which effect the cooling of each of these compartments are electrically coupled in series.

It is a more specific object of the invention to provide such a refrigerator which operates efficiently, so that even when the apparatus is switched over from high cooling to low cooling, the temperature maintained within the freezer compartment is sufficient to effect the freezing of water (or other products in the freezer compartment) at a rate approximately equal to that obtained when the apparatus is on high cooling.

Another important object of the invention is the provision of such a refrigerator which operates not only with ice a level of efficiency such to insure that water in the freezer compartment is always frozen but which operates at maximum efficiency, thereby to optimize the heat transfer between the external atmosphere and each of the freezer and cooler compartments, and to minimize the expenses of fabrication and operation.

The foregoing and other objects of the invention are realized, in one embodiment, by providing a thermoelectric refrigerator with thermally isolated freezer and cooler compartments. A first thermoelectric assembly is disposed adjacent the freezer compartment to effect the removal of heat therefrom as unidirectional electrical energy is passed through the assembly. A second thermoelectric assembly, which may comprise a plurality of assemblies, is disposed adjacent the cooler compartment, to effect a similar removal of heat therefrom upon energization by a unidirectional electrical energy flow. Circuit means couple the first and second thermoelectric assemblies in a series circuit for energization at either a first energy, level, or at a second energy level higher than the first level, as determined by the instantaneous position of a switching means in the power supply for the unit. The switching means is under the control of a sensing means, such as a thermostat, disposed to sense the ambient temperature in the cooler compartment. In one embodiment of the invention, the first thermoelectric assembly, the one which effects the heat removal from the freezer, is sized (for example, by regulating the length and/or area of its thermoelements) and constructed to have a peak operating efficiency at an energization level intermediate the first and second levels, and to have approximately the same efiicicncy at each of the first and second energization levels. The provision of these equaloperating efficiencies at the two different energy supply levels, related to the high and low cooling conditions, is more than adequate to effect the rapid freezing of water positioned within the freezer. i

In another embodiment of the invention, both the first and second thermoelectric assemblies are fabricated with identical physical dimensions for maximum economy and expediency of assembly. In such embodiment, the switching means is utilized not only to regulate the energization of the system at the first and second energy levels, but additionally to regulate the circuit configuration presented by the modules. Switching of the cooler modules between parallel and series circuit arrangements regulates the effective impedance presented thereby, in accordance with the changes of energization level, to insure that the maximum operating efiiciency of the entire refrigerator is obtained under all conditions of energization. i

In another embodiment of the invention a similar switching means is utilized but the physical dimensions of the thermoelements and modules are varied to effect the requisite efiiciency of operation when the thermostat operates the switching means between its first and second states.

In order to acquaint those skilled in the art with the best mode contemplated for making and using the invention, a description thereof is set forth in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is a front view, partially broken away, and FIGURE 2 is a rear View, of a thermoelectric refrigerator having thermally isolated freezer and cooler compartments and in which the invention finds particular utility;

FIGURE 3 is a schematic diagram particularly illustrating energization of one embodiment of the invention;

FIGURE 4 is a graphical illustration useful in under- 3 standing the construction and operation of the embodiment shown in FIGURE 3 FIGURE 5 is a schematic diagram of a preferred embodiment of the invention; and 7 FIGURE 6 is a partial schematic diagram depicting still another embodiment of the invention.

As shown in FIGURE 1, the thermoelectric refrigerator 10 is geometrically a six-sided box structure including left and

right walls

11 and 112, top and bottom walls 13 and 14, and a rear wall 15, best seen in FIGURE 2.

Considering FIGURE 1, the box is closed by a front.

door member 16, connected by a pair of hinges l7 and 18 to the front of, the right Wall structure 12. Accordingly, by grasping and pulling on handle 19 affixed to the left hand portion of door 15, the front'door is opened pivotally to provide access to the interior of the cooler compartment. The refrigerator is supported by

front legs

20, 21 and

rear legs

22, 23. A power supply unit 24 is shown affixed to and depending from lower wall 14 of the refrigerator, and this power supply receives conventional alternating-current (A.-C.) energy over a cable 25 including interior conductors (not shown) responsive to insertion of plug 26 into a conventional female receptacle to which A.-C. energy is supplied.

As shown in the lower left portion of FIGURE 1, a freezer compartment is defined by portions of left wall 11 and bottom wall 14 together with other insulating members including a top wall 27 and a right wall 28. Within the freezer an ice cube tray 29 or other cooling load can be disposed on cold platefitl, which abuts a tapered heat-conducting element 31. Thermoelectric module 32, disposed between heat-conducting

components

31 and 33, may be formed of P and N type elements so interconnected that, upon energization by unidirectional electrical energy, heat is absorbed from one surface (adjacent element 31) and heat is liberated at the other surface (abutting element 33). Such thermoelectric modules are now commercially available from several sources, and need no further explanation at this point.

Heat conducting element 33 tapers outwardly to a maximum dimension at the exterior of bottom wall 14, and a plurality of fin elements 34 are afiixed to the exterionof element 33 to assist in removing heat to the adjacent atmosphere. A suitable insulating material 52, such as freon-filled polyurethane, is disposed between the inner and outer panels that actually form each of the wall portionsof the refrigerator.

Separate thermoelectric assemblies and separate fin arrangements are utilized to cool the interior of the cooler compartment, as shown in FIGURE 2. Four separate sets of

fins

35, 36, 37 and 38 are provided to respectively dissipate heat received from

thermoelectric modules

39, 40, 41 and 42 which are utilized to remove heat from the interior of the cooler. For purposes of the pres ent explanation and the appended claims, the modules 39-42 can be considered as a single module or thermoelectric assembly for energization at either a first or a second energy level, to effect either low cooling or high cooling of the interior of the cooler.

As shown in the embodiment depicted in FIGURE 3, power supply 24 includes a pair of input conductors 43 and 44 for receiving A.-C. electrical energy over plug 26. Within power supply 24, relay 45, transformer 46, and rectifiers or diodes 47 and 48 cooperate to pass over

output conductors

49 and 50 unidirectional electrical energy at either a first level, or at a second level which is higher than the first level. In effect,.relay 45 and transformer 46 cooperate as a switching means to establish the level of the alternating electrical energy. Rectifiers 47 and 48 only change the alternating energy to unidirectional energy, without affecting the output level, which depends upon the instantaneous position of the contacts of relay 45, which is regulated by cooler thermostat 51.

In more detail, input conductor 43 is coupled over a fuse 53 to a first fixed contact 54, which is engageahle by a movable contact 55 of manual on-oif switch 55. Movable contact 55 is coupled to conductor 57. Another conductor 58 is coupled to movable contact 59 of switch 56, which upon initial action of the switch, engages fixed contact 60 to translate the input energy from plug 26 to

conductors

57 and 53.

Relay 45 includes a coil winding 61, a first contact set 62 including a movable contact or armature 63, and

fixed contacts

64 and 65. In the unoperated or deenergized position of relay 45 as illustrated, movable contact 63 engages fixed contact 64. Relay 45 also comprises another contact set 66, including a movable contact 67 which normally engages fixed contactes and is displaceable, upon energization of the relay, out of engagement with contact 68 to engage the other fixed contact 69. In the deenergized position of relay 45, conductor 57 is coupled over

contacts

67 and 68 to conductor 79, and conductor 58 is coupled over

contacts

63 and 64 to conductor 71.

Conductors

57 and 58 are also respectively coupled over

conductors

72 and 73 to thermostat 51, which may include a gas-filled bulb 74 or other temperature-sensitive means operable, upon reaching or exceeding a preset temperature, to effect the closure of contact set 75.

Transformer 46 includes a primary winding 76, the opposite end portions of which are coupled to

conductors

70 and 71. Primary winding 76 also includes a first tap or intermediate connection coupled over conductor 77 to fixed contact 69, and another tap coupled over conductor 78 to fixed contact 65. The center-tapped secondary winding 79 of transformer 46 has opposite end portions coupled to the anodes of rectifiers 47 and 48, the cathodes of which are intercoupled and connected to one end of a filter choke 80. The other end of choke 80 is coupled over output conductor 49 to thermoelectric module 32, represented as a simple resistance to facilitate explanation of the invention. In the series circuit arrangement, first thermoelectric module 32 is coupled to a second thermoelectric module comprising series-connected

modules

39, 40, 41 and 42. The last module 42 is coupled over output conductor 5t! back to the center-tap of secondary winding 79. Thus

conductors

49 and 50 comprise output means or circuit means which are a part of the series circuit connecting the thermoelectric modules.

In operation of the embodiment shown in FIGURE 3, thermostat 51 is adjusted to the temperature at or below which it is desired to maintain the interior of the cooler;

Plug 26 is inserted into a conventional wall receptacle (not shown), and on-oif switch 56 is displaced from the illustrated position so that

movable contacts

55 and 59 engage fixed contacts 54 and 60, respectively. It is assumed that the instantaneous temperature within the cooler compartment is below that at which the thermostat is set when the system is energized, so that the operating circuit for relay 45 is interrupted at contact set '75. With the closure of switch 56, power is applied over an obvious circuit to the full primary winding 76 of transformer 46, and the alternating energy induced in secondary winding 79 is rectified by diodes 47 and 48 to provide unidirectional energy at a first level which passes through freezer module 32 and cooler modules 39-42. It is further as sumed that the temperature within the cooler rises, as for example, by opening and closing the door several times, so that thermostat 51 is actuated and contacts 75 are closed to complete an obvious energizing circuit for the coil winding 61 of relay 45.

Relay 45 operates and at its contact set 65 transfers the energy received from conductor 57 over contact 69 to conductor 77, and at its contact set 62 transfers energy received over conductor 58 over contact 65 to conductor 78. Accordingly a lesser extent of primary winding 75 is energized to effectively change the turns ratio between the primary and secondary windings so that an induced voltage of higher amplitude appears across secondary winding '79. This higher voltage is rectified by diodes 47 and 4-3 to provide unidirectional energy at a second level, higher than the first level, which passes through freezer modules 32 and the individual cooler modules 3% 42 in series to place the system in high cooling operation. This operation is maintained until the temperature within the cooler compartment decreases below the preset temperature, thermostat 51 again operates to open contact set 75, and relay 45 is released to return the respective contact arrangements to their positions indicated in the drawings.

With the arrangement shown in FIGURE 3, if similar thermoelectric elements are chosen and utilized in constructing

modules

32 and 39%2, and no changes are made in the circuit connections of the freezer and/or cooler modules as the energization level is changed, with the result that all of the modules in both the freezer and in the cooler compartments exhibit a peak efiiciency at the same energization level, then it is manifest that at the reduced energization level for low cooling the efficiency of the modules will be correspondingly reduced. It has been found that, if the freezer module is constructed for peak efficiency on high cooling, the amount of cooling at the reduced eificiency exhibited when the system switches over to low cooling is generally such as to be inadequate either to freeze the water provided in ice cube tray 29 within a reasonable time period, or to maintain ice if the ice is already frozen.

The embodiment of the invention illustrated in FIG- URE 3 overcomes this deficiency of known devices by utilizing a freezer module designed and constructed to exhibit a peak efficiency or temperature difference at an energization level intermediate the first and second energization levels, or the levels utilized to produce low and high cooling in the cooler. This criterion is depicted in FIGURE 4, where the ordinate scale represents degrees of temperature difference between the hot side of the module (T and the temperature at the cold side of the module (T for different energization levels. It is noted that the characteristic curve 81 rises steeply and nearly uniformly for the greater initial portion of the curve until the optimum current value is reached, that is, that value of current at which the maximum temperature difference is produced across the thermoelectric module. For certain applications and with given modules adjacent the cooler, high cooling can be effected with a current of approximately amperes passing through the modules, and this value can be reduced to approximately 11 amperes when only low cooling is required. In accordance with this aspect of the inventive teaching, module 32 for the freezer compartment is constructed to exhibit an optimum energization or current level at a value. intermediate the low and high energization values; in this embodiment the optimum level was approximately 15 amperes. Accordingly the eificiency or effectiveness of operation of module 32 is reduced slightly, both at the low and high cooling conditions, from the maximum obtainable to a level depicted by broken line 82. With such an arrangement system operation is more than adequate to freeze the water in ice cube tray 29 to ice Within a reasonable time period. If conventional practice is used and the optimum current level for module 32 set at about 15 amperes, it is manifest that the sharply sloping initial portion of curve 81 would reduce the temperature difference obtainable at the low cooling value to a level inadequate to produce effective operation of the freezer system.

By way of example, if the modules of this embodiment are constructed of uniform cylindrical elements, each inch in length, the cooler modules 39-42 can be formed of elements 7 millimeters in diameter, and the freezer module 32 can be constructed with thermoelectric elements only 5 millimeter in diameter by A inch in height. Thus, by placing the optimum current level of the freezer module at a value intermediate (but not midway be- 99 and center-tapped secondary winding Nil.

tween) the energization values for high cooling and low cooling, effective operation of the freezer unit is maintained notwithstanding whether the cooler compartment is on high cooling or low cooling.

In FIGURE 5 a preferred embodiment of the invention is illustrated. The energy input arrangement for this system is similar to that shown in FIGURE 3, and includes a wall plug, input conductors, fuse and an on-off switch identified by reference numerals identical to those. used in FIGURE 3. However, relay 45, or the switching means of FIGURE 3, has been replaced by relay 85 in FIGURE 5. Relay 85 comprises a winding 86, a first contact set 87 including a movable contact 88 and fixed contacts 39 and 943; a second contact set 91 including a movable contact 92 and fixed contacts 93 and 94; and a third contact set 95, comprising a movable contact or armature 96 and a single fixed contact 97. As will become clear hereinafter, the portion of relay 85 including winding 86 and first contact set 87 may be considered a primary switching means which in its operation is effective to adjust the level of the electrical energy passed to the modules, whereas Winding 86 in conjunction with sec- 0nd and third contact sets 91 and $5, respectively, comprises an auxiliary switching means, effective to adjust the total impedance exhibited by all the modules concomitantly with an adjustment in the level of the electricalenergy output, thereby to maintain optimum efficiency of module energization notwithstanding whether the refrigerator is operating on high or low cooling.

Another change as contrasted to FIGURE 3 is that transformer 46 has been replaced by a transformer 98 (FIGURE 5), including a center-tapped primary winding It Will be apparent that such arrangement differs from the showing in FIGURE 3 principally in the employment of only a single tapped connection in the primary winding of transformer 8. The end portions of secondary winding 1% are coupled over rectifiers 4'7 and 4-3 and over choke 8i] to conductor 59, as in FIGURE 3, and the center-tapped connection of secondary Winding ltiil. is again coupled to conductor 5h. However it is noted that conductor 49 is coupled both to fixed contact 53 and over a conductor fill to one terminal of module dil, the other terminal of which is coupled through module 39 to a common conductor 192, shown connected to each of fixed contacts 97 and 94. Movable contact 92 of second contact set 91 is, coupled over conductor 103,

modules

41 and 42, and conductor tee to junction 112, which is coupled over conductor 1-05 to movable contact 96 of the third contact set.

Thermostat unit 51 is intercoupled over conductors 1% and 107 with the energy input portion of the circuit. That is, conductor 1% intercouples contact set of thermostat 51 and one end of winding 86 of switching means 85. The other end of winding $6 is coupled both to contact 55 of the on-off switch and over conductor 168 to movable contact 88 of the first contact set. As shown, movable contact $8 engages fixed contact 89 which is coupled over conductor 109 to one end of primary winding 99. In the operated position of relay 85, movable contact 88 engages fixed contact 96, which is coupled over conductor lift to the center-tapped connection of primary winding 99. The other end of winding 99 is coupledover conductor 111 to contact 59 of the on-off switch, and over conductor 18 7 to thermostat 51.

Considering the operation of the preferred embodiment set forth in FIGURE 5, it is initially assumed that wall plug 26 is inserted into a conventional wall receptacle (not shown) and that on-ofi switch 56 is closed to energize the system, with the temperature in the interior of the cooler compartment of the refrigerator below the temperature level at which thermostat 51 is set. Accordingly the system is on low cooling, with switching means in the position illustrated. In this position, contact set 87 transfers the input energy over conductor 1639 to one end of primary winding Q9, so that the levelof the output energy is at the first or lower value. In the illustrated position, all of the output energy flows from choke 89 over conductor 49, but where conductor 49 is joined to conductor 101, this energy divides. Half of the electrical energy flows over conductor 191, cooler modules 4tland 39, conductor 192,

contacts

97 and 96, and conductor 195 to junction 112. The other half of the electrical energy flows from conductor 49 over

contacts

93 and 92, conductor 103, cooler modules at and 42, and conductor 194 to junction 112. At this junction the electrical energy from each of the two separate paths is joined and all the energy flows through freezer module 32 and over conductor 50 back to the center-tapped connection on the secondary winding of transformer 98. Accordingly the cooler modules are connected in parallel and therefore exhibit a first or low impedance to the passage of electrical energy therethrough, when the switching means is in the first state.

As the temperature within the box or the cooler rises, and reaches the level at which thermostat 51 is set, contact set 75 is closed to complete an obvious energization circuit for winding $6. Relay 85 operates and at contact set 87 effectively changes the energization of the primary winding of transformer 98 to produce a change in the turns ratio of the transformer, thereby providing a second or higher energization level at the output side 'of power supply 113. Thus this primary switching means, or winding 86 in conjunction with contact set 87, is seen to regulate the energization level of the power supply for the refrigerator.

\Vith operation of relay 85, contact 92 is displaced out of engagemen t with contact 93 and engages contact 94, and contact 96 is displaced out of engagement with contact 97. Accordingly energy flowing from conductor 49 now sees only a single path, a series circuit which extends from conductor 49 over conductor 101, cooler modules and 39, conductor 162, contacts 94 and 92, conductor 103,

cooler modules

41 and 42, conductor 194, junction 112, freezer module 32, and conductor back to the centertapped connection of secondary winding 1041. Accordingly even though energy at a higher level is passed to the thermoelectric cooling circuit including modules 32 and 39-42, the total impedance exhibited by this module configuration is increased in proportion to the increase of the energization level by changing the circuit connections of cooler modules 39-42 from a parallel to a series circuit as the energization level is raised. With this arrangement, the energization of freezer module 32 is kept substantially constant, while the high and low cooling within the cooler compartment is effected by the different current levels which pass through modules 39-42 in the respective parallel and series circuit configurations.

As the temperature in the interior of the cooler decreases below the setting of thermostat 51, contact set '75 is opened to interrupt the energization circuit for winding 86 of relay 85, which releases. Accordingly the connections of the primary winding 99 are returned to the illustrated position and energization at the first level is provided at the output side of the transformer. Simultaneously the second and third contact sets 91 and 95 return totheir illustrated positions, thereby returning the connections of cooler modules 39-42 to the illustrated parallel circuit arrangement. In this preferred embodiment freezer assembly 32 was actually comprised of two individual modules, each fabricated with 16 thermoelements, with each thermoelement being seven millimeters in diameter and 4; inch in length. Each of the four cool modules is produced, by the combination of (1) varying the circuit configuration of the freezer modules (rather than the cooler modules, as in FIGURE 5) between series and parallel circuit arrangements, and (2) providing the freezer and cooler modules with the different geometry requisite to accommodate this operation.

More specifically, as shown in FIGURE 6, the second and third contact sets of the relay are comprised respectively of a contact set including a movable contact 121 and fixed

contacts

122 and 123, and a contact set 124, including a movable contact and a fixed contact 126. In that the relay winding arrangement and the disposition of the first contact set to vary the effective energization level produced, together with other components depicted in FIGURE 5, are not modified to produce the embodiment shown in FIGURE 6, the unchanged components and circuitry are not illustrated or described.

As shown in FIGURE 6, with the system on low cooling a series circuit is provided which extends from conductor 50 over cooler modules 39-42, conductor 127, junction 130,

freezer modules

32d and 320, conductor 123,

contacts

123 and 121, conductor 129,

freezer modules

32b and 32a, to conductor 49. Accordingly at'the first or lower energization level, a unidirectional current flows through each of cooler modules 39-42 in series to provide low cooling in the cooler compartment, and then through the series circuit comprised of freezer modules 32a-32d to conductor 49. As the temperature within the cooler rises sufiiciently to cause thermostat 51 tooperate and effect the change in states of the switching means, the second and third contact sets 1 20 and 124 are displaced from the illustrated positions to the positions in which contact 121 engages contact 122 and contact 125 engages contact 126. Accordingly current at the second or higher level flows from conductor 59 over cooler modules 39-42, conductor 127, to junction 139, where the current divides. Half the current flows over freezer modules 320! and 32c, conductor 128,

contacts

125 and 126, to conductor 49. The other half of the current flows from junction 139 over conductor 131,

contacts

122 and 121, conductor 129,

freezer modules

32b and 32a, to' conductor 49. In this configuration each of the cooler modules 39-42 was comprised of four individual modules, making a total of eight modules. Each of these cooler modules included 16 thermoelements, each seven millimeters in diameter by /8 inch in length. Each of the four freezer modules was comprised of 16 thermoelements, each seven millimeters in diameter by 4 inch in length. With this difference in geometry and the difference in circuit arrangement at the high and low energization levels, the cooler modules are operated between the high and low energization levels while the freezer modules are constantly energized at the same level. The embodiment of FIGURE 6 differs from that illustrated in FIGURE 5 in that uniformity of module construction and geometry is not utilized to attain maximum economy and efliciency of assembly and operation.

While only particular embodiments of the invention have been described and illustrated, it is apparent that modifications and alterations may be made therein. It is therefore the intention in the appended claims to cover all such modifications and alterations as may fall within the truespirit and scope of the invention.

What is claimed is:

1. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply for receiving alternating electrical energy and providing unidirectional electrical energy, including switching means effective in a first position to provide unidirectional electrical energy at a first ,level and effective in a second position to provideunidirectional electrical energy at a second level, a first thermoelectric assembly positioned to remove heat from said freezer compartment and constructed 9 to exhibit a peak efficiency at an energy level intermediate said first and second levels.

a second thermoelectric assembly positioned to remove heat from said cooler compartment,

and electrical circuit means for passing the unidirectional electrical energy from the power supply through said first and second thermoelectric assemblies in series, so that electrical energy at the same level is always applied to both of said thermoelectric assemblies.

2. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, switching means coupled to said input means and effective in a first position to provide electrical energy at a first level and effective in a second position to provide electrical energy at a second level, and rectifier means coupled to said switching means to provide unidirectional electrical energy,

a first thermoelectric assembly positioned to remove heat mom said freezer compartment and constructed to exhibit a peak efficiency at an energy level intermediate said first and second levels,

and electrical circuit means for passing the unidirectional electrical energy from said rectifier means through said first and second thermoelectric assem blies in series, so that energy at the same, level is always applied to both of said thermoelectric assemblies.

3. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, switching means coupled to said input means and operative in a first position to provide electrical energy at a first level and operative in a second position to provide electrical energy at a second level, and rectifier means coupled to said switching means for providing unidirectional electrical energy at one of said first and second levels,

a first thermoelectric assembly positioned to remove heat from said freezer compartment and constructed to exhibit a peak efficiency at an input energy level intermediate said first and second levels,

circuit means for passing the unidirectional electrical energy from said power supply through said first and second thermoelectric assemblies in series, so that energy at the same level is always applied to both of said thermoelectric assemblies, 7

and sensing means disposed to sense the temperature in the cooler compartment and regulate the position of said switching means in accordance with the temperature sensed.

4. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from said freezer compartment, the combination of:

a first thermoelectric module disposed adjacent said cooler compartment for removing heat from said cooler compartment upon the passage of electrical energy therethrough, operable to remove heat at a first rate upon passage of electrical energy of a first level therethrough and to remove heat at a second rate greater than said first rate responsive to passage of electrical energy at a second level higher than said first level therethrough;

a second thermoelectric module disposed adjacent said freezer compartment for removing heat therefrom responsive to the passage of electrical energy therethrough, said second thermoelectric module exhibitable between first and second states, transformer means connectedito have the effective turns ratio thereof regulated by the state of said switching means, and rectifier means coupled to said transformer means for providing unidirectional electrical energy at one of said first and second levels as determined by the state of said switching means;

thermostat means disposed to sense the instantaneous temperature in said cooler compartment and to regulate the state of said switching means as a function of the temperature sensed;

and circuit means for coupling said rectifier means, said first thermoelectric module, and said second thermo electric module in a series circuit, whereby the same energy level is applied to each of said first and second thermoelectric modules.

5. In a thermoelectric refrigerator:

a freezer compartment;

a cooler compartment thermally isolated from said freezer compartment;

a power supply, including a transformer having a primary winding with'intermediate tapped connections thereon and a center-tapped secondary winding, relay means operable in a first position to effectively provide a first turns ratio between said primary and secondary windings and operable in a second position to effectively provide a second turns ratio between said primary and secondary windings, and rectifier means coupled to said secondary winding to provide unidirectional electrical energy at a first level when said relay is in said first position and to provide unidirectional electrical energy at a second level when said relay is in said second position;

thermostat means disposed adjacent said cooler compartment to sense the temperature therein and to regulate the position of said relay in accordance with the temperature sensed;

a first thermoelectric module disposed adjacent said freezer compartment and constructed to exhibit maximum efiiciency at an energization level intermediate said first and second levels;

a plurality of thermoelectric modules disposed adjacent said cooler compartment and connected in series, operative upon energization at said first level to efiect low cooling and upon energization at said second level to effect high cooling within the cooler compartment;

and circuit means for intercoupling in a series circuit said first thermoelectric module and said plurality of thermoelectric modules, whereby the same level of electrical energization is always applied to the thermoelectric modules of the refrigerator.

6. ln a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply for receiving alternating electrical en ergy and providing unidirectional electrical energy including switching means effective in a first position to provide unidirectional electrical energy at a first level and effective in a second position to provide unidirectional electrical energy at a second level,

a first thermoelectric assembly positioned to remove heat from said freezer compartment,

a second thermoelectric assembly positioned to remove heat from said cooler compartment, operative to remove heat at a first rate when said switching means is in said first position and to remove heat at a second rate when said switching means is in said second position, i

and electrical circuit means for passing the unidirectional electrical energy from the power supply through c said first and second thermoelectric assemblies in series.

In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of power supply for receiving alternating electrical energy and providing unidirectional electrical energy ina second thermoelectric assembly positioned to remove heat from said cooler compartment, operative to remove heat at a first rate when said switching means is in said first position and to remove heat at a second rate when said switching means is in said second position,

electrical circuit means for passing the unidirectional electrical energy from the power supply through said first and second thermoelectric assemblies in series,

and sensing means, positioned to sense the temperature in said cooler compartment, for regulating the position of said switching means and thus regulating the rate of heat removal from said cooler compartment.

In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, primary switching means coupled to said input means and effective in a first position to provide electrical energy at a first level and in a second position to provide electrical energy at a second level, rectifier means coupled to said switching means to provide unidirectional electrical energy, and output means coupled to said rectifier means,

first thermoelectric assembly positioned to remove heat from said freezer compartment and coupled in series with said output means of the power supply so that the level of unidirectional electrical energy passing through said first thermoelectric assembly is the same as that received over said output means,

a second thermoelectric assembly, including a plurality of modules, positioned to remove heat from said cooler compartment,

and auxiliary switching means, including a portion of compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, primary'switching means coupled to said input means and effective'in a first position to provide electrical energy at a first level and in a second position to provide electrical energy at a second level, rectifier means coupled to said primary switching means to provide unidirectional electrical energy, and output means coupled to said rectifier means,

Y a second thermoelectric assemblyfincludihg a plurality of modules, positioned to remove heat from said cooler compartment,

and auxiliary switching means, including a portion of said primary switching means, for both coupling said modules between said first thermoelectric assembly and said output means of the power supply and'for changing the circuit arrangement of said modules between parallel and series circuit arrangements simultaneously with operation of said first switching means, to maintain maximum efficiency of operation of said second thermoelectric assembly at both the first and second energization levels.

10. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, relay means including a winding for coupling to said input means and further including first, second, and third contact seats, trans former means having tapped connections for selective coupling over said first contact set to said input means to provide electrical energy at a first level when said relay means is in a first state and to provide electrical energy at a second level when said relay means is in a second state, rectifier means coupled to said transformer means for providing unidirectional electrical energy, and output means coupled to said rectifier means,

a first thermoelectric assembly positioned to remove heat from said freezer compartment and coupled in series with said output means of the power supply so that the level of unidirectional electrical energy passing through said first thermoelectric assembly is the same as the level of energy transferred over said output means,

and circuit means, including said second and third concompartment and a cooler compartment thermally isolated from the freezer comparment, the combination of a power supply including input means for receiving alternating electrical energy, primary switching means coupled to said input means and effective in a first position to provide electrical energy at a first level and in a second position to provide electrical energy at a second level, rectifier means coupled to said switching means to provide unidirectional electrical energy, and output means coupled to said rectifier means,

a first thermoelectric assembly positioned to remove heat from said cooler compartment and coupled in series with said output means of the power supply so that the level of unidirectional electrical energy passing through said first thermoelectric assembly is the same as that received over said output means,

a second thermoelectric assembly, including a plurality of modules, positioned to remove heat from said freezer compartment,

and auxiliary switching means, including a portion of said primary switching means, for both coupling said modules between said first thermoelectric assembly 13 and said output means of the power supply and for modifying the circuit configuration of said modules simultaneously with operation of said first switching means to maintain maximum efficiency of operation of said second thermoelectric assembly at both the first and second energization levels;

12. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, primary switching means couple to said input means and effective in a first position to provide electrical energy at a first level and in a second position to provide electrical energy at a second level, rectifier means coupled to said switching means to provide unidirectional electrical energy, and output means coupled to said rectifier means,

a first thermoelectric assembly positioned to remove heat from said cooler compartment and coupled in series with said output means of the power supply sothat the level of unidirectional electrical energy passing through said first thermoelectric assembly is the same as that received over said output means,

a second thermoelectric assembly, including a plurality of modules, positioned to remove heat-from said freezer compartment,

and auxiliary switching means, including a portion of said primary switching means, for both coupling said modules between said first thermoelectric assembly and said output means of the power supply and for changing the circuit arrangement of said modules between parallel and series circuit arrangements simultaneously with operation of said first switching means, to maintain maximum efficiency of operation of said second thermoelectric assembly at both the first and second energization levels.

13. In a thermoelectric refrigerator having a freezer compartment and a cooler compartment thermally isolated from the freezer compartment, the combination of a power supply including input means for receiving alternating electrical energy, relay means including a Winding for coupling to said input means and further including first, second, and third contact sets, transformer means having tapped connections for selective coupling over said first contact set to said input means to provide electrical energy at a first level when said relay means is in a first state and to provide electrical energy at a second level when said relay means is in a second state, rectifier means coupled to said transformer means for providing unidirectional electrical energy, and output means coupled to said rectifier means,

a first thermoelectric assembly positioned to remove heat from said cooler compartment and coupledin series with said output means of the power supply so that the level of unidirectional electrical energy passing through said first thermoelectric assembly is the same as the level of energy transferred over said output means,

and circuit means, including said second and third contact sets, for coupling said modules between said first thermoelectric assembly and said output means in a series circuit arrangement when said relay means is in' the first state, and for changing the circuit arrangement to a parallel circuit responsive to operation of said switching means to the second state, thereby to maintain a maximum efi'iciency of operation of both thermoelectric assemblies at the first and second energization levels.

14. A thermoelectric refrigerator as set forth in claim 13 in which each of said first and second thermoelectric assemblies includes a plurality of individual thermoelements, each thermoelement in said first assembly being uniform in configuration and having a given diameter measurement and a givenlength measurement, and each thermoelement in said second assembly being of uniform configuration but having at least one of its diameter and length measurements different from said given diameter and length measurements.

References Cited by the Examiner UNITED STATES PATENTS 2,932,953 4/60 Becket 62-3 2,964,912 12/ Roeder 623 2,970,450 2/61 Roeder et al. 62----3 2,986,009 5/ 61 Gaysowski 62-3 ROBERT A. OLEARY, Primary Examiner.

WILLIAM J. WYE, Examiner.

Claims

1. IN A THERMOELECTRIC REFRIGERATOR HAVING A FREEZER COMPARTMENT AND A COOLER COMPARTMENT THERMALLY ISOLATED FROM THE FREEZER COMPARTMENT, THE COMBINATION OF A POWER SUPPLY FOR RECEIVING ALTERNATING ELECTRICAL ENERGY AND PROVIDING UNIDIRECTIONAL ELECTRICAL ENERGY, INCLUDING SWITCHING MEANS EFFECTIVE IN A FIRST POSITION TO PROVIDE UNIDIRECTIONAL ELECTRICAL ENERGY AT A FIRST LEVEL AND EFFECTIVE IN A SECOND POSITION TO PROVIDE UNIDIRECTIONAL ELECTRICAL ENERGY AT A SECOND LEVEL, A FIRST THERMOELECTRIC ASSEMBLY POSITIONED TO REMOVE HEAT FROM SAID FREEZER COMPARTMENT AND CONSTRUCTED TO EXHIBIT A PEAK EFFICIENCY AT AN ENERGY LEVEL INTERMEDIATE SAID FIRST AND SECOND LEVELS. A SECOND THERMOELECTRIC ASSEMBLY POSITIONED TO REMOVE HEAT FROM SAID COOLER COMPARTMENT, AND ELECTRICAL CIRCUIT MEANS FOR PASSING THE UNIDIRECTIONAL ELECTRICAL ENERGY FROM THE POWER SUPPLY THROUGH SAID FIRST AND SECOND THERMOELECTRIC ASSEMBLIES IN SERIES, SO THAT ELECTRICAL ENERGY AT THE SAME LEVEL IS ALWAYS APPLIED TO BOTH OF SAID THERMOELECTRIC ASSEMBLIES.