US2310761A - Refrigeration - Google Patents

Description

Feb. 9, 1943. G p DAlGER 2,310,761

REFRIGERATION Filed Feb. 5, 1940 INVENTOR George 1 Daiger ATTORNEY ciently.

Patented Feb.

REFRIGERATION George P. Daiger CantomDhio, assignor to The Hoover Company, North Canton, Ohio Application February 5,130, Serial No. 317,379

' 1 Claims. (01. (is-119.5)

Thisinvention relates to the artof refrigeration and more particularly to an absorption refrigerating system involving unique control and regulating features. 7 I v This invention particularly relates to threefluid absorption refrigerating systems of the type fluids therein. Motors of this type must be lubricated. However, considerable difllculty may the fact that under such circumstances the lubricant in the motor shell may be displaced by foreign material such as'absorption solution and once displaced it will be very dimcult to return the lubricant to its normal environment without materially reconstructing the apparatus.- Moreover, it may occur that the system will not be maintained in upright condition during ban-- dling and installation with the result that the lubricant will be spilled out of the motor casing and will not later bereturned thereto.

special arrangement for heating the lubricant to render the same fluid which comes into opera- J in which a circulating motor is hermetically sealed within the system in order to circulate the arise in handling and installing the system due to Y tion substantially simultaneously with the boiler heater and which will render the motor lubricant fluid at substantially the same time that the boiler discharges refrigerant vapor, after which the motor will be normally energized to permit the system to cycle.

It is a further object of the present invention to provide an absorption refrigerating system including a circulator, the rotor of which is immersed in a non-fluid lubricant which lubricant is rendered fluid by the heat generated by a high current passin through a portion only of the motor winding and which. heat is suflicient to render the lubricant fluid at the time that 'the Q boiler comes into full operation.

In order to obviate these difllculties it .is an object of the presentinvention to provide an absorption. refrigerating system of the above described character in which the motor. is submerged in a lubricating material which is not fluid at normal atmospheric temperatures and which will flow at the temperatures maintained by the heat generated by the motor winding in order to perform its lubricating function em- It is a further object of the present invention to provide an absorption refrigerating system of the-above referred to type in which the lubricant in its non-fluid state imposessufliclent drag upon the rotating portions of the motor to block the same until the lubricant has been liquefied, for example by the application of heat thereto.

It is a further object of the present invention to provide an absorption refrigerating system in which operation of thecirculating motor is prevented after energization thereof by reason of "q lator unit; and

Figure 3-is a schematicwiring diagram of the It is still another oblect ,of the present invention to provide an absorption refrigerating system which includes a lubricated circulator in which the circulator operates with a high current to provide suflicient heat to render the lubricant fluid and to provide an extremely high starting torque after which the entire motor winding is energized with the result that the same consumed a much lesser. current, generates only suflicient heat to maintain the lubricant in fluid condition and produces a smaller running torque. v

Other objects and advantages of the invention will become apparent as the-description proceeds v when taken inconnection with the accompanying drawing in which:

. Figure 1 is a diagrammatic representation of a1 three-fluid absorption refrigerating system em- I bodying' the present invention;

the lubricant blocking the motor for a period of time suflicient to permit the boiler to come into full operation; thatis, to discharge refrigerant vapor to the condenser in order thatlthesame may be liquefied and re-evaporated in the evaporator to produce a useful refrigerating eflect. with some lubricants, such as those having a high paraflln content, the period required to liquefy the same-by the heat generated by the.

small current normally flowing through the winding of the motor is excessive, wherefore it is an'obiect ofthe present invention to provide a rectifier R, a tubular air-cooled condenser C, an s Figure 2 is a partial sectional elevational view' drawn on an enlarged scale of the motor circucontrol circuit Referring now to the drawing in detail and first to Figure 1 thereof, there is illustrated a three-fluid absorption refrigerating system comprising a boiler B, an analyzer D, an air-cooled evaporator E, a gas heat exchanger G, a tubular inclined air-cooled absorber A, a liquid heat exchanger L, a solution reservoir S, and a circulating fan P which is driven by an electrical motor M. These elements are suitably connected by various conduits to form .a plurality of gas and liquid circuits constituting a complete refrigeratoperate on its normal operating.

ing system to which reference will be made in more detail hereinafter. I

The above described refrigerating system will be charged with a suitable absorbent, such as water, a suitable refrigerant, such as ammonia, and an inert pressure "equalizing medium preferably a dense inert gas like nitrogen.

The boiler B is arranged to be heated by a gas burner H which will be described in more detail hereinafter. The application of heat to the boiler B generates refrigerant vapor from the solution therein contained. The vapors so generated pass upwardly through the analyzer D in counterflow to the strong solution flowing downwardly therethrough. After traversing the analyzer D the vapor is conveyed from the upper portion thereof to the upper portion of the condenser C by I means of a conduit II which includes the recti- I5 extends between the suction side of the fan F and the upper portion of the absorber A.

The lean solution is conveyed from the reservoir S to the conduit l5 adjacent its point of connection with the absorber A by means of a gas lift pumping conduit l6. Pumping gas is supplied to the conduit 16 by means of a conduit II which is connected between the discharge conduit ill of the circulating fan F and the gas lift pump l6 below the liquid level normally prevailing therein andin the solution reservoir S.

The lean solution flows downwardly through the absorber A in counterflow relationship to a rich mixture of inert gas and refrigerant vapor which is supplied to the bottom portion of the absorber from the evaporator in a manner to be described hereinafter.

In its traverse through the absorber the lean solution ,absorbs refrigerant vapor from the gas mixture flowing therethrough and the resulting heat of absorption is rejectedby the cooling flns to cooling air flowing over the exterior walls of the absorber vessel.

The strong solution thus formed in the absorber is conveyed therefrom to the upper portion of the analyzer D by way of the conduit I9, the liquid heat exchanger L, and a conduit 20, thus completing the absorption solution circuit.

Lean inert gas is formed in the absorber A-by the absorption of refrigerant vapor and is then conveyed from the upper portion of the absorber to the suction side of the circulating fan 15 by means of the conduit IS. The inert gas is placed under pressure in the fan F and is then conveyed therefrom to the lower portion of the evaporator E by way of the conduit l8, the outer path of the gas heat exchanger G and an evaporator gas supply conduit 22. v

The refrigerant vapor whlch'is supplied to the condenser C is liquefied therein by heat exchange relationship with atmospheric air and is then conveyed therefrom to the bottom portion of the evaporator E by way of the conduit 23 and a conduit 24 which includes a downwardly extending U -shaped looped portion which is designed to carry a liquid seal and a pressure balancing column of the liquid refrigerant. The conduits 23 and 24 are vented by means of a conduit 25 to the rich gas side of the gas heat exchanger G. As a result of this construction the pressure prevailing in the condenser and the condenser side of the conduit 24 is that prevailing on the discharge side of the evaporator whereas the pressure prevailing on the discharge side of the conduit 24 is that prevailing at the inlet to the evaporatorl This pressure difference is compensated by a pressure balancing liquid column which is supported in the condenser side of the conduit 24.

The evaporator E may be of any desired type of construction. However, as diagrammatically illustrated herein, it is of the type in which the high velocity gas stream flowing through the evaporator serves to sweep or drag liquid refrigerant upwardly therethrough as itis evaporating to produce refrigeration. A preferred construction of this type evaporator is disclosed and claimed in the co-pending application of Curtis 0. Coons and William H. Kitto, Serial No. 386,395, filed April 2, 1941, which is a continuation-inpart of application Serial No. 220,189, filed July 20, 1938.

An anti-blocking and overflow drain 21 is connected between the upper portion of the bottom conduit in the evaporator E and the strong solution return conduit i9. I 1 r The liquid refrigerant supplied to the bottom portion of the evaporator E meetsa high velocity gas stream flowing upwardly ther'ethrough with th result that the liquid refrigerant is propelled upwardly through the evaporator as it is evaporating into the gas stream to produce useful refrigeration.

The top portion of the evaporator is provide with a large diameter finned box-cooling conduit 28 into which both the liquid and gas discharge. The gas flows at a slow rate through this conduit, ,7

hence the same is inclined rearwardly in order to permit liquid to flow by gravity. The resulting rich gas and unevaporated material in the evapo- 'rator is conveyed from the conduit 28 into the rich the bottom portion of the absorber A by means of the conduit 30. Thus, the conduit serves as a rich gas return conduit and as an evaporator drain. The rich gas then flows upwardly through the absorber'A in counterflow relationship with the leansolution flowing downwardly therethrough in the manner heretofore described.

It will be noted that with the construction thus conduit I9 in a manner such that it cannot reach the circulating fan and the fan is so connected to the absorber that lean solution cannot be conveyed thereinto from the lean solution supply lines. This is of considerable importance in preventing absorbing solution from finding its way to the motor shell, as will be explained in more detail hereinafter.

Referring now to Figures 1 and 2, it is apparent that the fan casing F carries a sealed motor shell 35 depending therefrom. The motor M consists of a rotating element 36 which is mounted within the shell and a stationary field winding or stator structure-31 which is mounted on the outside of the shell whereby the magnetic circuit for the induction rotor 36 must pass through the shell '35. The rotor is supported on suitable bearing assemblies indicated generally at 38 and 39 within the shell 35. The motor shaft 40 passes throughthe bearing 38 and carries a suitable fan within the fan housing 4| in a conventional manner.

The depending motor shell 35 is fllled with a suitable lubricant up to the level of the line indicated generally at 44; that is, the rotor is completely submerged and part of the bearing 38 is submerged in the lubricant.

One such lubricant is paraffin and it is obtainable in a. longrange of melting points and specific gravity. By selecting parafiln of the proper melting point or by mixing it with other lubricants, almost any melting point desired can be obtained. This lubricant has the characteristic that it is non-fluid at ordinary room temperatures but will become fluid when heated above that temperature in order to lubricate the bearings to permit the motor to rotate. In its nonfluid state the drag of this lubricant is suflicient to stall the rotor or the motor. V i

In this connection it should be emphasized that this motor is very small and develops only sufiicient power to circulate .the inert gas with a few inches of water pressure differential, hence the lubricant dragis easily suflicient to stall the same.

A switch housing 45 of insulating material is mounted on the lower end of the shell 35 directly beneath the stator structure and is provided with a switching housing or chamber 48 within which is mounted an electrical switch 49.

A bracket 50 is attached to the bottom portion of the shell 35 within the housing 48 and carries a snap-acting thermostatic strip or disc as may be desired, directly above the switch 49. The disc 5| is provided with an actuating button 52 which may be made of a composition insulating material and which is positioned to strike the movable element 53 of the switch 49 to actuate the same.

As was mentioned previously a heater H is provided for the 'boilerB, Gas is supplied to the heater H from a suitable source of supply through a conduit 55 which includes a solenoid valve V.

lary conduit 6| which connects to a fluid containing bul'b 52 positioned to be influenced by temperature changes at or adjacent the evaporator E. The exact construction of the thermostatic switching mechanism 60 is conventional and need not be disclosed in detail herein. Power is supplied to the apparatus from a pair of electrical conductors 63 and 64.

The conductor 83 connects directly to the switching mechanism 50 which is connected by means of the conductors 55 and 56 to the solenoid valve V and to the winding 51 of the stator of the motor M. The conductor 64 connects directly to the valve V and is connected to the movable element 53 of the switch 49 by means of a conductor 58.

The movable element 53 of the switch 49 is arranged to make contact with an upper fixed contact 10 which is connected to approximately the mid point of the winding'fil by means of a conductor II or to make contact with a lower flxed contact 12 which is connected to the end of the winding 61 by means of a conductor 13.

As can readily be seen from an inspection of Figure 3, approximately half the motor winding is energized when the movable switch arm 53 makes contact with the contact element 10 as illustrated, whereas the entire motor winding is energized when the arm 53 makes contact with the fixed contact 12. 7

The operation of the invention, except insofar as the same has already been disclosed in connection with the construction of the refrigerating apparatus per se, is as follows: When the apparatus is initially installed substantially all portions thereof will be at room temperature and the lubricant which is contained within the shell 35 will be non-fluid or substantially solid and will interpose sufficient resistance to rotation of the motor to prevent operation thereof. Immediately the apparatus is connected to suitable sources of gas and electricity, the thermostatic switch 50, being in closed circuit position, will energize the solenoid valve V to supply fuel to the burner H through the following circuit: 63, 50, 65, 55, V, 54.

Due to the fact that the lubricant is in the cold solid condition the thermostatic disc 5| will be flexed upwardly as is indicated in Figures 2 and 3 to bring the switch arm 53 into contact with the contact 10. Under these conditions that portion of the winding of the motor between the conductors 65 and 1| will be energized by the following circuit: 63, 80, 65, 66, winding 61, H, 15, 53, 53 and 64. Under these conditions a relatively high current will flow through that portion of the motor winding included between the conductors 55 and 1| and will produce a relatively large quan- 'tity of heat. This short winding -with its attendant high current produces a starting torque approximately 2 to 3 times the normal running torque of the motor. The drag of the non-fluid lubricant will block the rotor; however, the heat generated by this high current will shortly render the lubricant fluid and the high current flowing in the winding with its attendant high starting torque will start rotation of the rotor 36. After the lubricant has been rendered fluid the temperature of the shell 35 will be increased sufliciently to cause flexure of the thermostat 5| downwardly, as viewed in Figures 2 and 3, thereby breaking the circuit between the elements 53 and I0 and closing the circuit between the elements 53 and 12. The entire winding will now be energized and the motor will run in accordance with its normal operating characteristic.

It will be understood that the winding and lubricant will be selected in such fashion that the lubricant will be rendered fluid and rotation of the motor will begin substantially immediately after the boiler B has come into full operation; that is, immediately after the boiler B is generating refrigerant vapor and is discharging the same to the condenser.

The above operation will continue until the temperature at or adjacent the evaporator reaches a value for which the thermostatic mechanism 60 has been set whereupon the thermostatic switch 50 will break the circuit between the conductors 63 and 55, thus de-energizing the motor and reducing the flame on the heater H to a mere pilot or ignition flame.

The motor will now cool and the lubricant will solidify if the apparatus is maintained deenergized a suflicient length of time to permit the lubricant to solidify. In normal cycling of the apparatus the lubricant will be rendered nonfluid an appreciable period of time before reenergization of the refrigerating mechanism by the thermostatic switch mechanism 60. However, if for any reason a short cycle should occur, the motor will develop suflicient torque to start without going through the starting cycle as long as the lubricant is in its fluid condition and the thermostat 5| will prevent the motor from attempting to start without going through the normal starting cycle unless the lubricant is in a fluid condition and will not interpose a blocking drag upon the rotor 36.

In normal operation of the apparatus the heat generated by the running winding is suflicient to maintain the lubricant in a fluid condition without other aid.

' Thus, the motor has a starting cycle in which the same is supplied with a high current which generates a large amount of heat and produces a high starting torque and a running condition in which a much lesser quantity of heat is generated and a lower or running torque is produced. The starting condition is inefficient but is not objectionable for mere starting purposes, whereas the running condition of the motor is relatively highly eflicient and generates a relatively small quantity of heat which, however, is suflicient to maintain the lubricant in a fluid condition.

The illustrated construction is the preferred arrangement. However, the thermostatic cutout for the starting condition of the motor may be arranged to shift the motor from starting to running condition in response to a change in the condition of another portion of the system which is induced by energization of the system. For example, the thermostatic switch for the motor could be arranged to respond to the temperature of some portion of the pipe II. This pipe is heated by hot vapor enroute to the condenser. There is a time lag between initiation of full flame operation of the burner and heating of this pipe which will allow suflicient'heating of the lubricant to render the samefiuid and to render the'motor capable of starting. Such a construction will produce the desired lag in operation of the motor with respect to the burner.

Thus, the present invention provides a very advantageous construction of an absorption refrigerating system together with the control mechanism therefor which insures that lubricant will not be lost from the motor shell during transit, handling and installation and which provides a construction whereby the lubricant is rendered fluid prior to energization of the motor and also in which the time period re- 7 quired to condition the motor for energization is so correlated through the control for the boiler-heater that the boiler is brought up to operating condition just prior to energization of the motor whereby the system goes into complete operationimmediately the motor is energized and no loss of heat is entailed in the preliminary heating of the boiler-analyzer assembly.

This-type of control is not only economical but is also more efficient than the previously known simultaneous energization type of controls which have been used on this type of reiri'gerating system.

The present control provides a highly efllcient construction in which rapid heating of the lubricant is assured and in which the motor is provided with a high starting torque and immediately after operation of the motor the same is changed from its starting heating condition to its more eflicient though lower torque operating and lubricant maintenance condition.

While I have shown but one embodiment of my invention, it is to be understood that this embodiment is to be taken as illustrative on'y and not in a limiting sense. I do not wish to DB limited to the particular structure shown and described but to include all equivalent variations thereof except. as limited by the claims.

I claim:

1. Absorption refrigerating apparatus comprising a boiler, a condenser, an evaporator, ar absorber and a fluid circulator connected in circuit, a drive motor for said fluid circulator including a rotating part at least partially submerged in a lubricant which is non-fluid at atmospheric temperatures, a field winding for said motor, a heater for said boiler, control means for said apparatus arranged to energize said heater and to energize said motor field in such fashion that the same generates a high starting torque and high heat and means responsive to a change in the thermal condition of a portion of the apparatus induced by energization thereof by said control means for energizing said field in such fashion that it produces a normal running torque and a low heat.

2.- Absorption refrigerating apparatus comprising a boiler, a condenser, an evaporator, an absorber and a fluid circulator connected in circuit, a drive motor for said fluid circulator including a rotating part contacted by a lubricant which is non-fluid at'atmospheric temperatures, a fieldwinding for said motor, a heater for said boiler, control means for said apparatus arranged to energize said heater and to energize said motor field in such fashion that the same generates a high starting torque and high heat and means responsive to the temperature of said lubricant for energizing said field in such fashion that it produces a normal running torque and a low heat.

3. An absorption refrigerating system comprising a boiler, a condenser, an evaporator, an absorber and a fluid circulator connected in circuit,- a drive motor for said circulator including a rotating part hermetically sealed in said system and immersed in a lubricant which offers suflicient resistance at atmospheric temperatures to block rotation of said rotating part, a field winding for said motor, a heater for said boiler, refrigeration demand responsive means for energizing a portion of said field winding and said heater, and means for energizing the entire field winding when said lubricant has softened sufficiently to allow said motor to start.

4. Absorption refrigerating apparatus including a fluid circulator, a drive-motor for said fluid circulator having a rotating part sealed in the system and supported in a normally nonfluid lubricant, a multi-polar field for said motor mounted exteriorly of said apparatus, control means for energizing a portion only of said field, and means for energizing all of said field when said lubricant has been rendered fiuid by the heat generated by said portion of said field.

5. Absorption refrigerating apparatus including a generator, 2. liquefier, an evaporator, an absorberand a fluid circulator connected in' circuit, a heater for said generator, an electric motor arranged to drive said circulator, said electric motor including a field winding, control means for energizing said heater and for energizing a part of said field winding to produce a high starting torque, and means for energizing said field winding to produce a normal running torque in response to a change in the condition of a part of the apparatus induced-by operation thereof.

6. Absorption refrigerating apparatus including a generator, a liquefier, an evaporator, an absorber and a fluid circulator connected in circult, a heater for said generator, an electric motor arranged to drive said circulator, a lubricant for said motor and in contact therewith which is sufliciently thick at atmospheric temperatures to impose a stalling load upon said motor, said electric motor including a field winding, control means for energizing said heater and for energizing a part of said field winding to produce a high starting torque and a large quantity of heat for softening said lubricant, and means for energizing said field winding to produce a normal running torque when said lubricant has been heated sufficiently to serve its lubricating function without imposing a stalling load upon said motor.

7. Absorption refrigerating apparatus including a fluid circulator, a drive motor for said fiuid circulator having a field winding, starting connections for said motor arranged to energize a portion only of said winding, running connections for said motor arranged to energize all of said field winding, refrigeration demand responsive control means arranged to energize said motor through said starting windings, and means operated bya change in the condition of a part of the apparatus induced by initiation of operation thereof for energizing said motor through said running connections.

GEORGE P. DAIGER.

Images