US2195990A

US2195990A - Refrigerating system

Info

Publication number: US2195990A
Application number: US183468A
Authority: US
Inventors: Clifford W Leegard
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1938-01-05
Filing date: 1938-01-05
Publication date: 1940-04-02
Anticipated expiration: 1957-04-02

Description

April 2, 1940. I

c. w. LEEGARD REFRIGERATING SYSTEM Filed Jan. 5, 193B a M9 M1 6 4 4 w. L 7 w 4 M r m Ln 3 2 a 4 m 4 w h 1 E PW h fl P 2 2 V v 0 5 Y a 6 M 2 l 2 u 5 lml a m J u n 5 M m g 9,. i z m P m I f x 0 0 Inventor Clifford W Leegard,

His Attorney.

Patented Apr. 2, 1940 UNITED STATES REFRIGERATING SYSTEM Clifford W. Leegard, Fort Wayne, Ind., assignor to General Electric Company, a corporation of New York Application January 5, 1938, Serial No. 183,468

5 Claims.

My invention relates to refrigerating systems, and more particularly to an arrangement for indicating loss of refrigerant from the system.

It has been proposed heretofore to provide a 5 refrigerating system with an arrangement for indicating the loss of refrigerant from the system. I have found that these arrangements are subject to the disadvantage that when adjustments are made to give a.\- correct indication under running conditions or active periods of the system, a correct indication will not be obtained when the system is inactive.

An object of my invention is to provide a refrigerating system having an improved arrangement for indicating the loss of refrigerant in the system under active and inactive'conditions.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying draw- 5 ing in which Fig. 1 is a diagrammatic illustration of a refrigerating system embodying my invention; Fig. 2 is a side elevation of the float chamber and the mounting therefor used in the system shown in Fig.1; Fig. 3 is a sectional view on the p line 3-3 of Fig. 2 partly in elevation; and Fig. 4 is a perspective view of the switch of the magnetically operated switch employed.

Referring to the drawing, I have shown a refrigerating system including a compressor l0 having a pulley H which is driven by an electric motor l2 through a belt l3. The compressor l0 and the motor l2 are mounted on a base 16 to provide a unitary structure, and a condenser I1 is mounted in the base. The motor l2 may be connected to an alternating current source of electrical supply through a switch l4 and lines l5. Upon closing the switch M the refrigerating system operates and refrigerant vapor is withdrawn from an evaporator through the suction line l8 into the intake of the compressor I 0. The compressed refrigerant is discharged from the compressor through a discharge line H! into the condenser I! where the compressed refrigerant is water-cooled and liquefied. The liquid refrigerant accumulates in the lower portion of the condenser, so that the condenser ll also serves as a receiver. The liquid refrigerant is supplied to an evaporator from the lower portion of the condenser ll below the level of liquid refrigerant therein through a supply conduit Ila,

a suitable device being provided to maintain the desired difference in pressure between the condenser and the evaporator, such as an expansion valve. I

During operation of the refrigerating system 5 the level of liquid refrigerant in the condenser and receiver I! is proportional to the amount of liquid refrigerant contained in the system. If there is any considerable loss of refrigerant from the system during its operation, it is desirable 10 to give an indication to an attendant of this loss of refrigerant. I also have found that during inactive periods of the refrigerating system, when the motor I2 is deenergized and stopped, there is a gradual rise in level in the condenser and receiver l1 to a somewhat higher level than the level therein during operation of the system.

I, therefore, provide an arrangement for giving an indication of loss of refrigerant from the system during active and inactive periods thereof. 2

The arrangement for giving this indication of loss of refrigerant from the system during inactive or rest periods comprises a container or auxiliary receiver 2|, which is connected to the condenser and receiver below the level of liquid 2 refrigerant therein by a conduit 22 and is connected to the condenser and receiver above the level of liquid refrigerant therein by a conduit 22a. The auxiliary receiver 2| is arranged with respect to the liquid refrigerant level in the condenser and receiver ll, so that during inactive periods of the machine the level of liquid refrigerant in the auxiliary receiver 2| is at the level 2la as indicated in Figs. 1 and 3. If there is any substantial loss of refrigerant from the "system under this inactive condition, an alarm device 20, such as a light, bell, or the like, is energized to give the attendant the desired indication. The alarm device 20 is controlled in response to an excessively low level of refrigerant during this inactive or rest condition of the system by a float 23 which is carried by an arm 24 pivotally mounted on a pin 25 secured to a cup 21 within the auxiliary receiver 2|. The arm 24 is provided with fingers 26 of magnetic material 5 which are arranged on diametrically opposite sides ofthe cup 21 of non-magnetic material. The cup 21 is hermetically sealed in an opening 2Ic in the wall of the auxiliary receiver 2|.

In the interior of the cup 21 an armature 25 is rotatably mounted on pins 30 as shown in F g. 4. The armature 29 is provided with diametrically opposite permanent magnet poles 3| which can turn within their enclosing casing 31a of nonmagnetic material. The armature 29 also arries a switch arm 32 provided with a contact 33 which is connected to a conductor 34. This contact 33 can be swung into and out of engagement with the stationary contact 35 by movement of the poles 3| of the armature. The arm 32 is provided with a pointer 32a visible through an arcuate window in the switch casing and cooperating with a scale on the switch casing, as shown in Fig. 2. The auxiliary receiver 2| is adjustably mounted by bolts 36 on an L-shaped supporting bracket 31. Under normal inactive or rest conditions of the system the position of the float 23 is such as to retain the poles 3| in a position to open the contacts 33 and 35 of the magnetically operated switch within the cup 21, so as not to energize the alarm device 20. This occurs because the position of the switch arm 32 is determined by the position of the fingers 2B controlled by the float 23, as the permanent magnets 3| follow any change in position of the fingers 26. If, however, there is a loss of refrigerant from the system, the float 23 will be lowered and move the arms 26, so as to cause the permanent magnets 3| within the cup 21 to close the relatively movable contacts 33 and 35, thus energizing the alarm device 20. The downward movement of the float 23 is limited to the circuit closing position by a stop pin 28. The alarm device is energized upon closing the contacts 33 and 35 from the secondary of a transformer 38 having its primary connected to a suitable electrical source of supply. The circuit is completed from one side of the alarm device through conductor 34, contacts 33 and 35, conductor 39, the contacts of switches 40 and 4|, and the secondary of the transformer 38 to the other side of the alarm device 20. Thus an attendant is given warning of the loss of refrigerant from the system and can take the necessary steps to stop the leakage of refrigerant.

When the refrigerating system has been operating, the level of liquid refrigerant in the condenser and receiver l1 and the auxiliary receiver 2| is at the low level 2|b indicated in Fig. 3. Upon opening the switch H to deenergize the motor I2 and stop the operation of the system, the refrigerant level in the condenser and receiver gradually rises to a higher level 2|a, as shown in Fig. 3. This is due to the draining of liquid refrigerant from the supply lines and from the interior of the condenser after the system is shut off. At the time of opening of the switch it the float 23 will be in a position to close the switch contacts associated therewith, because the liquid refrigerant in the auxiliary receiver 2| will be at the lower level 2|b. It is, therefore, necessary to delay completion of the circuit through the switch contacts controlled by the float 23 until the level of liquid refrigerant in the condenser and receiver and the auxiliar receiver 2| has risen to its normal level 2|a and raised the float 23 sufliciently to open the contacts 33 and 35 controlled by the float 23. If this provision is not made the float 23 will give a premature alarm of low level of refrigerant, whereas by providing this interval of delay the alarm device 20 will not be energized unless the float 23 comes to equilibrium during the inactive period of the machine in a position to indicate a low level of refrigerant in the auxiliary receiver 2| and a corresponding loss of refrigerant from the system.

I obtain this delayed action by connecting the operating coil of a switch 4| in circuit with the motor l2 through conductors 42. Thus, durin the operating period of the system the low level of refrigerant 2|b will be obtained in the auxiliary receiver 2| and the switch contacts controlled by the float 23 will be closed. The alarm device 20 will not, however, be energized, because the contacts of switch 4| will be retained open by the operating coil. Furthermore, the contacts of the switch 40 will be open during this active or operating period of the system, because the operating coil of the switch 40 also will be energized. The operating coil of the switch 40 is energized by connecting the same across lines through conductors 43 and a thermal switch 44. This thermal switch comprises a bimetallic strip 45, which is heated by an element 46 connected in parallel with the operating coil of the switch 4| through a flxed resistor 41 and a variable resistor 48. In its heated condition the bimetallic strip 45 is moved to close the contacts of the thermal switch 44 and complete the circuit through the conductors 43 to the operating coil of the switch 40. Upon opening the switch M to deenergize the motor l2, the switch 4| is deenergized so as to close its contacts, and at the same time the heating element 46 is deenergized, as it is connected in parallel with the operating coil of the switch 4|. The thermal switch 44 slowly cools upon this deenergization of its heating coil 46, and an interval after deenergizing the heating coil 46 the bimetallic element 45 is moved to open the contacts of the switch 44, arcing of the contacts being minimized by the condenser 45a which will not energize the operating coil of the switch 40 sufliciently to open these contacts when the contacts of the switch 44 are opened. This delay in opening the contacts of the switch 44 is suflicient to permit the level of liquid refrigerant in the auxiliary receiver 2| to rise to the lever 2|a and open the contacts controlled by the switch 23, if there has been no substantial loss of refrigerant from the system. On the other hand, if there has been a substantial loss of refrigerant from the system, or if this occurs while the system is at rest after this interval, the contacts of the switch 23 will be closed as above explained to energize the alarm device 20 through the

conductors

34 and 39 and the contacts of switches 40 and 4|.

Upon closing the switch l4 the operating coil of the switch 4| will be energized to open its contacts, and the heating coil 46 of the thermal switch 44 will be energized to close the contacts of the switch 44 and open the' contacts of the switch 40; these switches will remain in this relation as long as the switch I4 is closed to operate the motor l2. Operating the refrigerating system in this way will gradually reduce the level of the refrigerant in the condenser and receiver l1 and the auxiliary receiver 2| to the level 2|b indicated in Fig. 3. In order to provide an alarm during operating or active periods of the system, I provide another float 23a in the auxiliary receiver 2| carried by an arm 24a pivotally mounted on a pin 25a and having fingers 26a cooperating with a cup 21a of nonmagnetic material hermetically sealed in an opening in the auxiliary receiver 2|. The fingers 2641 are of magnetic material, so that the permanent magnets 3| of the armature 29 follow the movement of the fingers 25a upon rising and falling of the float 23a due to variation in liquid level in the auxiliary receiver 2|. The downward movement of the float 23a is limited by a stop 28a in which position the relatively movable contacts 33 and 35 of the switch within the cup 21a shown in Fig. 4 are closed. Upon closing of these contacts a circuit is completed through conductors l3 and 50 to energize the alarm device 20. During ordinary operation of the system the level of liquid refrigerant in the auxiliary receiver 2! will be as indicated at 2lb in Fig. 3, which will raise the float 23a sufficiently to open the contacts 33 and 35 controlled thereby. Upon loss of refrigerant from the system the level 2") during operation of the system will be excessively low, and the.

float 23a will fall slightly to close the contacts 33 and 35 and energize the alarm device from the secondary of the transformer 38. In order-- a to adjust the relation of the permanent magnet poles 3| of the switch controlled by the float 23a with respect to the terminal 35, a locking screw 5| is provided which can be released to adjust the enclosing casing 3| a of the switch with-re-- spect to the fingers 26a. A similar locking screw 52 is provided for adjusting the relation. of the permanent magnets 3! controlled by the float 23 with respect to terminal 35. This adjustment of the permanent magnets 3! with respect to the terminals makes it possible tochange the position of the float 23 or the float 23a, which will cause closing of the contacts controlled by these floats.

It will thus be seen that I have provided a refrigerating system having an arrangement for giving an indication of loss of refrigerant from the system during active and inactive periods of the system, and in which the indicating device cannot be energized during the inactive period until an interval suflicient to obtain equilibrium conditions .in the system.

Although I have shown and described my in vention in connection with a particular type of refrigerating system, it will be understood that it is also applicable to other types of refrigerating systems. I do not, therefore, desire my in-v vention to be'limited to the particular construction shown and described, and I' intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire'to secure by.

refrigerant in said system and containing a predetermined amount of liquid refrigerant when said system is active and containing a greater amount of liquid refrigerant when said system inactive, and means a liquid refrigerant container associated with said receiver for v indicating an excessively low level 01' liquid refrigerant in said receiver during active and inactive periods of said system, said container be-. ing adjustable with respect -to said receiver to vary the response of said indicating means.

2. A refrigerating system containing refrigerant, means for indicating a loss of refrigerant from said system during active periods thereof, means for indicating a loss of refrigerant from said system during inactive periods thereof, and means for delaying the response of said inactive period indicating meansuntil a predetermined interval after shutting off of said system.

3. A refrigerating system containing refriger ant and including a compressor, means includ-. ing a motor for driving said compressor, means for indicating a loss of refrigerant from said system during operation of said motor, means for indicating a-loss of refrigerant from said system when said motor is deenergized, and means for delaying the response of said last mentioned means an interval after said motor is deenergized. 4. A refrigerating system containing refrigerant and including a compressor, means including a motor for driving said compressor, means for accumulating from said system liquid refrig erant in proportion to the amount of refrigerant contained therein, means associated with said accumulating means for indicating loss of refrig-' erant from said system during operation oisaid motor, means associated with said accumulating means and independent of the energization of said motor for indicating loss of refrigerant from said system when said motor is deenergized, and means for delaying the response of said last mentioned means an interval after said motor is de- -cluding a motor for driving said compressor, means for accumulating liquid refrigerant from said system in proportion to the amount of refrigerant therein, means including a float associated with said accumulating means for indicating a loss of refrigerant from said system during operation of said motor, means independent of the energization of said motor and including a float associated with said accumulating means for indicating a loss of refrigerant from said'system when said motor is deenergized. and means for delaying the response oil-said last mentioned means an interval after said motor is deenergized.

CIIFFORD W. LEEGARD.