US2454855A - Refrigerator humidity control - Google Patents

Description

J. J. BAUMAN REFRIGERATOR HUMIDITY CONTROL Nov. 30, i8.

Filed July 10, 1945 KTA Patented Nov. 30, 1948 2,454,855 nnrarosaa'roa umrmrrr coN'raOr.

John J. Bauman, Abington, Pa., assignor, by to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylmesne assignments,

vania Application July 10, 1945, Serial No. 604,161

8 Claims.

This invention relates primarily to refrlgerating apparatus and more particularly to refrigerators of the type which include a moist-cold compartment adapted for refrigeration of foodstuffs without dehydration and wherein means is provided for maintaining, within reasonable limits. a substantially constant relative humidity within the said compartment.

In my co-pending application S. N. 565,435, filed November 28, 1944, now Patent No. 2,442,188 granted May 25, 1948, I have described a refrigerator of the above class together with means responsive to relative humidity within the compartment for removing excessive moisture from the air within the latter so as to maintain the relative humidity below a predetermined maximum. In my co-pending application S. N. 575,876, now Patent No. 2,440 628 granted April 27, 1948, I have described a device for initiating and controlling the operation of the humidity control apparatus, said device including humidity-sensitive actuating means exposed to the atmosphere of the moistcold space and thereby operating directly in accordance with the percent relative humidity within said space.

The present invention contemplates devices for initiating and controlling the operation of the aforesaid dehumidifying means in accordance with the temperature difference between the air within the moist-cold space and the surface of the evaporator or other element which forms the active refrigerating surface for said space.

A primary object of the invention, therefore, is to provide a simplified and highly effective device for controlling the. operation of dehumidifying means associated with a refrigerated moist-cold food storage compartment.

Another object of the invention is to provide a control device of the stated character which utilizes the temperature differential between the air within the moist-cold compartment and the surface of the active refrigerating element or elements exposed within the refrigerated space.

In the attached drawings:

Fig. l is an elevational and partial sectional view of a refrigerator embodying the invention;

Fig. 2 is a fragmentary sectional view illustrating certain details of the refrigerator construction;

Fig.v 3 is an enlarged sectional view showing the details Of the control apparatus, together with the associated electrical wiring diagram, and

Fig. 4 is a view in perspective of one of the elements of the device illustrated in Fig. 3.

For the purposes of definition, the invention has been illustrated in the attached drawings in its application to a'refrigerator of the character illustrated in my Patent No. 2,442,188 aforesaid.

Thiscomprises a cabinet I having an outer shell 2 and a metal shell or liner 3 which embraces a main food storage space 4. A machinery compartment 5 is located in the lower part of the cab.-

inet and in this compartment is housed a motor compressor unit, designated by the reference numeral 6, which forms an essential part of the refrigerant circulation system by means of which the interior chambers of the cabinet are refrigerated. The cabinet further comprises a frozen food storage bin 1 having a top access opening 8 and, above the bin 1, a compartment 9 adapted to receive trays I8 in which water is frozen for manufacture of ice cubes. Above the machinery compartment and insulated therefrom is a low temperature storage compartment Il.

The three compartments 1, 9, and I I are refrigerated through the medium of an evaporator I2 which constitutes an element of the primary refrigerant system which includes the compressor 6. Thus the compressor is connected with the condenser I3 and through the condenser and by way of a capillary tube I4 with the said evaporator I2. From the, evaporator I2 a pipe I5 extends to a small primary evaporator I6 which in turn is connected through a suction pipe I1 to the compressor. The small primary evaporator I6 is operatively associated with the condensing portion I8 of a secondary refrigerant circuit which includes evaporator tubing I9 associated with the metallic inner liner 3 of the storage space 4, this secondar`y-circuitbeing completed by a tube 20 which returns to the condenser lI8 as illustrated.

The operation of the motor compressor 6 is controlled by a switch device 2l in the motor circuit. This switch is responsive to temperatures in the evaporator I6, and to this end the switch element is associated with a Sylphon actuator 22 which is operatively connected to a bulb 23 positioned in heat exchange relation with the evaporator I6. This Acontrol is of a character to afford a temperature dierential of several degrees be- I tween the opening and closing of the said switch 2i. Y p

Means is provided for circulation of the air in the chamber 4 and for passage of this air in course of circulation in intimate heat exchange relation with a portion of the refrigerant flow tubing i1. To this end manifold chambers 24 and 25 are provided in the insulated wall of the compartment 4 and at bottom and top respectively of the latter. Louvre openings 26-28 in the liner 3 provide communication between the Vmanifold chambers 2G and 25 and the interior of the chamber 4. At the back of the liner 3 a passage 21 is provided between the manifolds 24 and 25, this passage communicating at its lower end with the discharge side of a rotary fan or blower 28, the intake of which is connected to the manifold 2. Operation of the blower 28 has the effect of drawing air from the chamber 4 into the manifold 26 and of forcing this air upwardly through the passage 21 to the manifold 25 and through the upper louvres 26 into the upper part of the chamber il. As illustrated in Fig. 2, the suction duct il extends in part longitudinally through the interior of the passage 21 and within saidpassage is provided with projecting metallic fins 29. Bailies 38 within the passage 21 direct the air flowing therethrough in a tortuous path in intimate thermalV exchange relation with the' surface of the duct I1 and the thermal transfer ns 29. Means hereinafter described is provided for controlling the over the surfaces of the refrigerant duct il' and ns 29, the airloses moisture which is deposited on the said surfaces from whence the moisture eventually passes downwardly by gravity to a discharge vent 3l in the lower part of the passage 21. The operation of the blower continues until the relative humidity of the air in the compartment d has been reduced to a desirable value at which time the operation of the blower is automatically discontinued.

It' the motor compressor 8 is functioning during operation of the blower 2B. it will be evident that the suction line ,l1 within the passage 2l will be at a relatively low temperature, and the pointed out above, the control bulb 23 is positioned so that it may respond to this back flow of heat thereby to re-establish operation of the compressor 5 by closing the'control switch 2i. This will reduce the temperature of the suction line I1 to the required extent.

This refrigeratlng apparatus and its mode of operation have been fully described in my aforesaid Patent No. 2,442,188 and form no part of the present invention except insofar as the elements of the apparatus relate to the control means now to be described.

In accordance with the present invention, the

electrical control circuit of the actuating motor for the blower 26 is provided with a control switch of the character illustrated in Fig. 3 and designated generally by the reference numeral 32. In this figure, the actuating motor for the blower 28 is indicated at 33. In accordance with the invention, the switch 32 is actuated in response to a changing temperature differential between two thermo-sensitive pressure devices operatively associated with the chamber d. Each of these devices takes the form in the present instance of a Sylphon or like expandable and contractable element. 34 and 35 respectively, having connected thereto a closed bulb 36 and 31. The bulbs 36 and 31 and their associated Sylphons contain a thermo-sensitive medium which expands and contracts in accordance with increasing and decreasing temperatures to which the bulbs 36 and 31 may be exposed. In the present instance the bulbs are exposed Within the chamber 4 and the remaining portions of the devices, together with the switch 32, are contained within the insulation between the liner 3 and the outer wall 2 of the cabinet.

Asshown in Fig. 3, each of the Sylphons 3e and 35 carries at its outer end a pinl 36 or other suitable bearing element which respectively engage opposite sides of a lever 39 which is pivotally supported at 4G within the housing il of the switch device 32. Preferably and as illustrated, the points of engagement between the pins 38 and the lever 39 are slightly oiset with respect to each other longitudinally of the lever, the bearing point for the Sylphon 36 being relatively remote to the pivot pin til. The lever has an extension 42 of electrical insulating material, and on the outer end of this extension is a block 43 having in the forward side thereof a notch 4i, the function of which will be hereinafter deheat transferred from the air to the refrigerant will be absorbed in the primary refrigerating circuit.

1f on the other hand therelative humidity within the compartment should become excessive during an off period of the motor compressor cycle, the line i1 will be at a relatively high defrosting temperature and'its capacity to absorb further heat will be relatively small. VUnder such conditions only small amounts of moisture could be condensed in the dehumidifying zone. Should this reduced heat exchange capacity be insufficient to restore the desired relative humidity condition within the food compartment, operation of the compressor Vwill be re-established automatically, as follows: Y

'As soon as the temperature of the suction line and the adjacent surfaces of the passage 21 rise substantially, heat will ow back along the suction line to the primary evaporator II. As

scribed. Connected to the block 2l@ is a spring 45 which tends to retain the lever in a relatively elevated position as illustrated. The tension of the spring may be regulated from the exterior of the housing di through the medium of an adjusting screw it;

Secured to the housing iii and inside the latter is an insulator element di which extends upwardly at one end to form a support for a flexible switch member 48, Vthis member being more clearly illustrated in Fig. 4. As therein shown, the member has an opening 49 through which the block 43 extends and an arcuate tongue element 50, the free end of which seats within the notch 44 of the block 43, the relative dimensions being such that the tongue 50 when thus engaged with the block is held under compression. The outer end of the member 48 is provided with an electrical contact element 5| which is adapted for engagement with an opposed contact 52 which extends downwardly through a terminal extension of the insulator 41 and pro- `iects through an aperture 53 in the housing`4i.

The other end ofthe member 48 is secured to the insulator 41 through the medium of twoJ notch 44 will be moved below the plane of the member 48 whereupon the tongue, which isunder compression as described, will act to elevate the outer end of the member 48 with a snap action and to thereby separate the contact 5I from the contact 52. This will open the motor circuit and will interrupt the operation of the blower. It will be noted that the extent to which the resilient member 48 may ilex upwardly is limited by a. stop element 55 which is carried by an insulatorblock 56 within the housing 4I and which may be adjusted from the outside of the housing in a manner apparent from the drawing. The contact 52 similarly limits the flexing of the member 48 in the opposite direction so that the total movement of the member between the circuit-opening and -closing positions is a relatively small one. This type of micromatic switch member is well known in the electrical arts and per se forms no part of the present invention.

The position of the lever 39 is determined by the differential between the pressures exerted by the Sylphons 34 and 35, and these pressures are functions of the temperatures'cf the bulbs 36 and 31 which are exposed within the chamber 4. These temperatures differ by reason of the fact that whereas the bulb 31, which communicates with the Sylphon 35, is supported in the interior of the chamber 4 in a position remote to and conductively disassociated with the surface of the liner 3, the bulb 36 is mounted in direct thermal exchange relation with' the said liner. The control movementof the lever 39 is, therefore, a function of the temperature -differencebetween the air in the space 4 and the liner 3, which in this case constitutes a functional part of the evaporator which includes the tubing I9. When this temperature diierence exceeds or reaches a predetermined upper limit the motor 33 and blower 28 are actuated to circulate the air in the chamber 4 over the surface of the duct i1 and iins 29 as previously described. Since an increase in the temperature differential to or 'in excess of the predetermined value will generally be. accompanied by an undesirable rise in the humidity of the chamber air, the device operates automatically to regulate humidity in obvious manner.

In more specic explanation of the mode of operation of the device, let it'be assumed that the wall 3 (or other active refrigerating surface, as the case may be) is operating at 36 F., and that this results in maintenance of an average temperature within the chamber 4 in the neighborhood of 38 F. Under these conditions the rela tive humidity of the box air may go as high as 75% without -danger of the air falling below its dew point temperature when in contact with the 36 Wall. As long as the temperature differential between the wall 3 and the air within the chamber 4 is 2, or less, the lever 39 will be held,by the Sylphons 34 and 35 in a position such'that the switch member 48 will rest against the stop 55 remote to the contact 52. The motor 33 will then be inoperative; Assume, further, that air at '70 enters the chamber 4 through the opened door, said air being at, say, 30% relative humidity, a common condition. Such air, if reduced to 36 F.. would pass the saturation point and condensation would occur upon the wall. The introduction of this relatively warm air, however, will increase the temperature of the air within the chamber beyond the normal 2 diilerential, and resultant expansion of the Sylphon 35, which is subject to the air temperature within the chamber, will move the lever 39 upwardly, as viewed in Fig. 3, until the tongue will have shifted to an extent causing the member 48 to snap down upon the contact 52. The motor 33 and blower 28 will thereby be actuated to circulate the air as described and will.

remain in operation until the 2 differential is reestablished at which time the excessive humidity condition will have been rectified,

On the other hand, itI will be appreciated that should the temperature of the wall fall appreciably, without a rapid corresponding decrease in the temperature of the compartment air, the Sylphon 34 will contract, thus permitting lever 39 to rise and the contacts 5 i-52, to close.

I claimt 1. In means for regulating humidity in an evaporator-cooled Ahigh humidity chamber, the combination with dehumidifying means, of an actuator for said means responsive to variation inthe temperature differential between the said evaporator 'and the air within said chamber.

2. In a refrigerator comprising a moist-cold compartment and evaporator means in heat exchange relation with said compartment, the combination with meansfor reducing Ithe humidity of lthe air withir` the compartment, of an actuator for said reducing means responsive to variation in the temperature differential betweenthe said evaporator and the air within said chamber.

3. In a refrigerator comprising a moist-cold compartment and evaporator `means in heat exchange relation with. and presenting a surface within said compartment cooler than the compartment air and subject to undesirable moisture deposition, means for reducing the humidity of the compartment air,I land actuating means for said reducing means responsive to the temperature differential between the said compartment air and the said cooling surface of the evaporator.

4. In means for regulating humidity in an evapcrater-cooled high humidity chamber, the combination with `dehumidifying means, of a control device operative to initiate operation of the Ydehumidifying means when the temperature differential between the said vaporator and the compartment air exceeds a predetermined value.

5. In a refrigerator comprising -a moist-cold compartment and van evaporator associated with a wall of said compartment and operative through said wail to cool the compartment air, the combination with means for reducing the humidity of the said compartment air, of a control device for said means responsive to the temperature differenti-a1 between the said air and said wall. 1

6. In a refrigerator comprising a moist-cold compartment having therein a cooling surface normally at a lower temperature than that of the compartment air, the combination with means for reducing lthe humidity of the air within the compartment, of an actuator for said reducing means responsive .to variation in thetemperature megane I differential between said cooling surface and the said air.

7. In means for regulating humidity in a. high humidity chamber having therein a cooling lsurface normally at a lower temperature 4than that 5 s operative also to maintain operation of the dehumidiiying means until said predetermined diiierential has been re-established.

. JOHN J. BAUMAN REFERENCES crrlm The following references are of record in the me of this patent:

i UNITED sums PATENTS Number Name Date 2,101,498 Grooms Dec. 7, 1937 Schweller Aug. 4. 1942

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