US2366562A - Refrigeration - Google Patents

Description

H. am 5mm@ REFRIGERATION v Filed Aug.

.to a much higher value.

Patented Jan. 2, 1945 REFRIGERATION Howard L. Schug, Palo Alto, Calif., assignor'to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application August 9, 1943, Serial No. 497,939

20 Claims.

This invention relates to refrigeration and more particularly to a circulator unit for circulating the mediums in a three-iluid absorption refrigerating machine utilizing ammonia as the refrigerant, water as the absorbent, and an inert pressure equalizing medium such as nitrogen or hydrogen.

Such machines are well known in the art and have a closed circuit between the evaporator and the absorber for the Circulation of inert gas therebetween.

The inert gas is for the purpose of equalizing the pressures throughout the entire machine, all of the partsrof which are 'in open communication, and for carrying refrigerant vapor from the evaporator to the absorber. vIn the evaporator the refrigerant liquid is vaporized by diffusion into the inert gas and inthe absorber the refrigerant vapor is absorbed out of the inert gas. A closed circuit is also provided between the generator and absorber for the circulation of the absorption solution usually consisting of a water solution of ammonia. In the generator, refrigerant vapor is driven from the solution by the: application of heat and in the absorber the Weak solution takes up refrigerant vapor from the inert gas. Some means must therefore be -provided for circulating the inert gas between the evaporator and the absorber and the solution between the generator and the absorber.

In prior art machines it has been usual practice to circulate the inert gas thermosiphonically or by differences in specific weights of different columns of the inert gas and to circulate the solution by a heat operated vapor liquid lift pump. Suchv machines operate satisfactorily under ordinary circumstances but in hot climates and at high room temperatures they are unsatisfactory because they operate inefiiciently and, have very low capacity. The problem can be solved if some means is provided for circulating the mediums but which is n-ot affected by changes in temperature. This is especially true in air cooled machines to which this invention relates.

It has been proposed to use mechanical pumps for the purpose of circulating the mediums in Thus it is practically impossible to use mechanical pumps having moving parts extending through the walls of said system.

In order to solve vthis problem a way had to be found of hermetically sealing the moving parts of the mechanical circulator unit on the interior of the apparatus and the present invention has to do with the solution of that problem.

Since all the parts of a three-fluid absorption refrigerating machine are in open communication with each other, the internal pressure is substantially the same throughout all parts except for liquid columns and the resistance of the circuits. Asv a result of this, a circulator unit which will develop a pressure difference of approximately four inches of water is sucient for circulating al1 the mediums in their circuits. Actually the power output of the medium circulator is only two or three watts and the power unit must be made very small. The problem of sealing the moving parts of such a power unit in the interior of the apparatus is not simple. Where a motor is used, the field coils and rotor should not be placed on the interior of the apparatus because. they would beattacked by the corrosive atmosphere in the interior of the apparatus.

According to this invention the entire motor lunit is positioned exterior the walls of a refrigdriver on the exterior of the system walls adjacent to the follower is eective to drive the mesuch refrigerating systems but the application of mechanical pumps to those vsystems is not a simple matter. The internal pressures of air cooled machines of this type vary from 250 to 400# per square inch under normal operating conditions and under certain abnormal conditions they go Before beinggput into operation, the systems are hydraulically tested up to 800# per square inch.

its minimum torque being the torque capacity of the driver magnet. However, the pull-in .torque for such magnetic transmission is eight to ten times the minimum torque.

It is an object of this invention to utilize the pull-in torque of a permanent magnet transmission for the initial starting of the medium circulator, fan and to pull the circulating fan back A ment relative thereto `andto provide a magnetic shunt adjacent the follower and driver so that strong magnetic poles are induced in the shunt by the .magnetic field of the magnets when the driver and follower magnets are in step. When the driver and follower magnets are not in step the magnetic poles in the magnetic shunt are not nearly as strong as when they are in step and the increased magnetic pull resulting when the driver and follower come into step is utilized to connect drivingly the follower to the fan so that the pullin torque between the driver and the follower can be utilized to start the circulating fan from a starting position or to pull it back into step with the driver magnet when the fan gets out of step with the driver.

Specifically, according to this invention, the magnetic shunt and the follower magnet are provided with friction discs so that when the increased pull of the magnetic shunt, caused by the driver and the follower magnets coming into step, moves the follower axially so that the friction discs come into engagement to rotate the circulating fan in unison with the follower. When the above engagement occurs the pull-in torque y between the driver and follower which is eight to ten times the minimum running torque is utilized to start the circulating fan and to hold it from lagging behind the driver under certain operating conditions tending to stall the circulator unit.

The magnetic shunt and friction discs described above are associated with a magnetic follower and fan in which the follower is made of a permanent magnet mounted for rotative and axial movement on the shaft of the fan. The follower may have two or four poles. The fan and magnetic follower are mounted for rotation on the interior of the inert gas circuit on dry type bearings having slight frictional losses, A driver magnet is positioned on the exterior of the walls of the inert gas circuit and is driven by an electric motor. The driver magnet and the follower magnet are separated by a thin annulus of non-magnetic material such as stainless steel so as to reduce the air gap between the follower and driver.

The motor is so mounted that the gap between the driver magnet and the non-magnetic annulus may be made very small. The motor is mounted in a vertical position on an annular ring of rubber bonded to two metal rings so that the weight of the motor and driver places the rubber under a direct shear stress while any forces tending to misalign the driver with the non-magnetic annulus will subject the rubber to a direct compressive stress.

The driver magnet and the follower magnet according to this invention may be permanent magnets having two or four poles purchasable on the open market under the trade name of Alnico which is an alloy of aluminum, nickel, iron and cobalt or they may be any other type of permanent magnet.

The non-magnetic annulus between the driver and the follower may be made quite thin and still withstand the high pressures involved. It has been found that it can be made 0.020 of an inch in thickness, thus materially reducing the magnetic losses and increasing the efficiency of the entire unit.

While the magnetic transmission according to this invention has been disclosed for use in driving the circulating unit for a three fluid absorption refrigerating apparatus it is to be understood that it is not limited to suchuse but is of more general application and can be utilized in any place where motion is to be transmitted from one member to another.

Other objects and advantages of this invention will becomeapparent when taken in connec tion with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of the circulator unit according to this invention.; and

Figure 2 is an exploded view showing the details of the magnetic transmission of Figure l.

Referring to the drawing, the circulator unit, according to this invention, comprises a cylindrical casing I0 havinga bottom plate I2 and a top plate I4 welded or otherwise secured thereto. The casing I0 is divided into a suction chamber and a pressure chamber by a division plate I6 having an opening I8 leading to the eye of the fan. The casing I0 is Welded to Athe inert gas circuit of an absorption refrigerating apparatus by means of conduits 20 and 22. A mixture of inert gas and refrigerant vapor enters by con-l duit 20 and exits by conduit 22.

The fan 24 comprises a shroud 21, the annular hub 26 extending at right angles thereto having an inner diameter so that it can be passed tightly over the enlargement 28 on shaft 25. The fan blades extend radially of the annulus-,26 and are secured to the shroud 21. Secured to the bottom of the casing I0 and the bottom plate I2 is a cup shaped member 23 extending downwardly from the casing I 0.

The shaft 25 is mounted for rotation on the interior of the casing I0 and the inverted cupshaped member 29 by bearing assemblies 32 and 34. The bearing surfaces of the bearing assembly 32 is preferably made of material which does not require lubrication, such as tungsten carbide.

The upper bearing assembly 34 is preferably made of a material impregnated with graphite so as to require no lubrication.

Mounted for both rotative and axial movement on the shaft l25 is a permanent magnet 3| made of a material having a high magnetic retentivity and purchasable on the open market under the trade name of "Alnico which is an alloy of aluminum, nickel, iron and cobalt. The permanent magnet has a plurality of poles 33 positioned closely adjacent the inner periphery of the cup-shaped member 29.

Rigidly secured to the shaft 25, immediately above the permanent magnet 3l, is an inverted cup-shaped member 35 of highly magnetic material, which constitutes a magnetic shunt. Secured to the upper face of the permanent magnet 3| and the lower face of the inverted cupshaped member 35 are friction discs 36 and 31, respectively.

The cup 23 is made of non-magnetic material, preferably a non-magnetic stainless steel so as to resist corrosion by the ammonia.

Supported from a flange 33 of the cup-shaped member 29 is an electric motor 38. The motor 38 is supported by means of an annular metal ring 40 secured to the flange 33 and an annular metal ring 42 secured to the motor 33 separated by an annular rubber ring 44 bonded to the rings 40 and 42.

The rotating shaft of the motor 33 carries a permanent magnet 46 having a plurality of poles 48 corresponding in number to the poles 33 on the follower magnet 3| and constitutes a driver magnet. The magnet 48 is carried on the motor shaft by means of, a mounting spider. 5I). The motor 38A is mounted sothat its.` shaft isvin the exact center of the cup 23 andfthe poles 48 of the magnetic driver are or suchtsie that only a small air gap is provided between the poles 48 and the exterior of the cup 29. The driver magnet 46 is also preferably made of a nickel-aluminumcobalt-iron alloy purchasable on the open market under the trade name of Alnico.

The magnetic shunt 35 is mounted on the shaft 25 in a position to be attracted by both the follower magnet and the driver magnet 46 so that the poles of thosemagnets induce magnetic poles in the shunt 35.

In operation the motor 38 is energized and rotates the driver magnet 46. The north poles of the driver magnet 46 will tend to attract the south poles of the`fo1lower magnet 3| and its south poles will tend to attract the north poles of the follower magnet which will cause the follower magnet 26 to rotate on the shaft 25. vThe slip between the driver magnet 46 and the follower magnet 3| will be greatest in starting; however, this is reduced as the follower magnet 3| comes up to speed and eventually the driver magnet 46 and the follower magnet 3| will fall into step. This will occur quickly since there is no load on the follower magnet 3|.

The poles of both the driver magnet 46 and the follower magnet 3| will induce magnetic polesin the magnetic shunt 35. When the follower magnet 3| is out of step with the driver magnet 46, the poles induced in the magnetic shunt 35 will tend to oppose each other so that the strength of the poles induced in the magnetic shunt 35 will be quite weak. However, when the magnetic follower 3| and the driver magnet 46 come into step the poles induced in the magnetic shunt 35 by each of the magnets will be additive and will draw the follower magnet 3| upwardly so as to bring the friction discs 36 and 3T into engagement so that the magnetic shunt 35 will rotate with the follower magnet 3l and in turn quickly bring the fan 24 into rotation in unison with the follower magnet 3i.

The reason the magnetic poles induced in the magnetic shunt 35 are Weak prior to the time the driver magnet 46 and the follower magnet 3| come into step is because the magnetic circuits through those magnets are out of alignment. However, when the driver magnet 4B and the follower magnet 3| come into step, a strong magnetic circuit is formed through the shunt which will induce strong magnetic poles in the magnetic shunt 35.

If for any reason the circulator fan should tend to stall during operation the follower magnet 3| would be pulledy out of step with the driver mag-v net 46 and the poles induced in the magnetic stalling force on the fan and again rotate the fan in unison with the driver magnet 46.

Conditions under' operation which might impose a stalling force on the fan may, for instance,

' be a frozen'bearing or an accumulation ofscle about the fan? and the utilization of the pullntorque of the driver and follower magnets would tend to break this obstructing force.

From the foregoing it can be seen that this invention provides a magnetic transmissiony for transmitting movement from the exterior of the -three-fluid absorption refrigerating machine to the rotating parts on the interior inA which the follower magnet is quickly brought into step with the driver magnet and the magneto motive force so produced is utilized to engage drivingly the follower magnet 3| with the circulating fan 2li so that the pull-in torque of the driver magnet and the follower magnets may be utilized to overcome the inertia of the fan or to break any stall ing force tending to stop the rotation of the fan.

While I have shown but a single embodiment of this invention it is to'be understood that this embodiment is to be taken as illustrative only and not in a limiting sense. I do not wish to be limited to the particular structure shown and described but to include all equivalent variations thereof except as -limited by the scope of the claims. l

I claim:

1. A medium circulator for a three-fluid absorption refrigerating apparatus comprising, a fan hermetically sealed on the interior of said apparatus, a follower magnet cn the interior of said apparatus, a driver magnet mounted on the exterior of the apparatus walls adjacent the follower magnet so as to transmit magnetic lines of force through the walls of the apparatus to the follower magnet, a magnetic shunt mounted on the interior of said apparatus adjacent the driver 'and follower magnet so thatra magnetic fiux is netic flux to said follower magnet on the interior of said apparatus and having minimum torque characteristics of from -1-0 tol/8 of the pull-in torque between said driver and follower magnets and means for utilizing the pull-in torque between said driver and follower magnets for starting said shaft, a magnetic shunt rigidly secured to said shaft and being positioned to receive magnetic 'flux from bot-h the driver and follower magnets,

the arrangement being such that an increased magnetic flux is induced in said magnetic shunt when oppcsitepoles of said driver and follower Ymagnets are in alignment and means utilizing the increased magnetic fiux for drivingly connecting said follower magnet to said shaft.

4. A'm-edium circulator for a three-fluid-absorption refrigerating apparatus comprising, a driver magnet on the exterior of said apparatus walls. a follower magnet mounted on the interior of said apparatus so as to receive magnetic flux from said driver magnet and being separated from dri"er magnet by a hermetically sealed wall, said follower magnet being loosely mounted on a rotatable shaft, a fan rigidly secured to said 5. A medium circulator for a three-fluid absorption refrigerating apparatus comprising, a shaft mounted for rotation on the interior of said apparatus, a follower magnet loosely mounted on said shaft, a fan rigid with said shaft, a driver magnet mounted for rotation exteriorly of said apparatus walls and being positioned to transmit magnetic flux through the apparatus walls to said follower magnet and means utilizing the flux of said driver and follower magnet for drivingly connecting said follower magnet to said shaft.

6. A medium circulator for a three-fluid absorption refrigerating apparatus comprising, a shaft mounted for rotation on the interior of said v apparatus, a follower magnet loosely mounted on said shaft, a fan rigid with said shaft, a driver magnet mounted for rotation exteriorly of said apparatus walls and being positioned to transmit magnetic flux through the apparatus walls to said follower magnet, and means utilizing the flux of said driver and follower magnets for drivingly connecting said follower magnet to said shaft, said last mentioned means comprising a magnetic shunt secured to said shaft and being positioned to receive magnetic flux from both the driver and follower magnets and to pull said follower magnetinto 'engagement by the magnetic poles induced therein.

'7. A'medium circulator for a three-fluid ab sorption refrigerating apparatus comprising, a shaft mounted for rotation on the interior of said apparatus, a follower magnet loosely mounted on said shaft, a fan rigid with said shaft, a driver magnet mounted for rotation exteriorly of said apparatus walls and being positioned to transmit magnetic flux through the apparatus walls to.

said follower magnet and means utilizing the flux of said driver and follower magnets for drivingly connecting said follower magnet to`Y said shaft, said last mentioned means' comprising a magnetic shunt positioned to receive magnetic l j flux from both the driver and follower magnets. y

8. A circulator unit for a three-fluid absorption refrigerating apparatus comprising 'a fan and follower magnet hermetically sealed on the interior of .said apparatus, a driver magnet mounted on the exterior of the walls of said apparatusto transmit magnetic flux to said follower magnet on the interior and having minimum torque characteristics of from 116 to 1A; of the pull-in torque between the driver and follower magnets, and means for utilizing the pull-in torque between said driver and follower magnets for starting said fan, said means comprising a magnetic shunt positioned to receive magnetic flux from both the driver and follower magnets.

- 9. A magnetic transmission comprising, driver and follower magnets mounted for rotation on opposite sides of -a wall in a position to exert mutual magnetic attraction, said driver and follower magnets being so constructed and arranged that the pull-in torque between the driver and follower magnet is 8 or 10 times as great as the minimum torque of the driver magnet, a. member positioned and arranged that the to be driven by said follower magnet, said member being normally free of driving connection with said follower magnet, and means utilizing the pull-in torque between the driver and follower magnet for drivingly connecting said follower magnet to said member.

10. A magnetic transmission comprising, driver and follower magnets mounted for rotation on opposite sides of a wall in a position to exert mutual magnetic attraction, said driver and follower magnets being so constructed and arranged that the pull-in torque between the driver and follower magnet is 8 or 10 times as great as the minimum torque of the driver magnet, a member positioned to be driven by said follower magnet, said member being normally free of driving connection with said follower magnet, and means utilizing the pull-in torque between the driver and follower magnets for drivingly connecting said follower magnet to said member, said means comprising a magnetic shunt positioned to be magnetized by the magnetic flux of said driver and follower magnets. l

11. A magnetic transmission comprising, driver and folldwer magnets mounted for rotation in a position to be mutually attracted, a magnetic shunt mounted for rotation in a position to be magnetized by the driver and follower magnets, a member positioned to be driven by said follower magnet, and means for utilizing the increased magnetism induced in said magnetic shunt when opposite poles of said driver and follower magnets are in alignment for drivingly connecting said follower magnet t0 said member. f

12. A magnetic transmission comprising, a shaft mounted for rotation on a vertical axis, a follower magnet mounted on said shaft for independent rotation, a, driver magnet mounted independently turning moment on driver and follower said follower magnet, said magnet being so constructed pull-in torque between the driver and follower magnets is 8 or 10 times the minimum torque of the driver magnet, and means utilizing the pull-in torque between the driver and follower magnets for drivingly connecting said follower magnet to said shaft.

13. A magnetic transmission comprising, Aa shaft mounted for rotation on a vertical axis, a follower magnet mounted on said shaft for independent rotation, a'driver magnet mounted independently of said shaft for rotation in a position to exert a turning moment on said follower magnet, said driver and follower magnet being so constructed and arranged that the pull-in Atorque between the driver and follower magnets is from 8 to 10 times the minimum torque of the driver magnet, and means utilizing the increased magnetic field produced when opposite poles of said driver and follower magnets are in alignment for moving said follower magnet axially of said shaft tg ctonnect drivingly said follower magnet to said s a t. f

14. A magnetic transmission comprising, a follower magnet, a load to be driven thereby, said follower magnet being freely rotatable independently of said load, a driver magnet mounted for rotation in a position to exert a. magnetic innuence on said follower magnet, and means utilizing the increased magnetic field when the follower magnet falls into step with the driver magnet for connecting said follower magnet with said load.

l5. A magnetic transmission comprising, a follower magnet, a load to be driven thereby, said ently of said load, a driver magnet mounted for rotation in a position to exert a magnetic influence on said follower magnet, and means utilizing the increased magnetic field when the follower magnet falls into step with the driver magnet for connecting said follower magnet with said load, said means comprising a magnetic shunt positioned to be magnetized by the magnetic field of both magnets, n

16. A magnetic transmission comprising, a follower magnet, a load to be driven thereby, said follower magnet being freely rotatable independently of said load, a driver magnet mounted for rotation in a position t0 exert a magnetic influence on said follower magnet and means utilizing the increased magnetic field when the follower magnet falls into step with the driver magnet for connecting saidv follower magnet with said load, said means comprising a magnetic shunt positioned to be magnetized by the magnetic field of both magnets, said follower magnet being mounted to be pulled into engagement with said magnetic shunt by the increased magnetic eld when said follower magnet falls into step with said driver magnet.

17. A magnetic transmission comprising, a shaft mounted for rotation on a vertical axis, a follower magnet mounted on said shaft for independent rotation and axial movement, a driver magnet mounted independently of said shaft for rotation in a positionto exert a turning moment on said follower magnet and means utilizing the magnetic flux of both magnets for moving said follower magnet axially of said shaft to connect drivingly said follower magnet to said shaft.

i8. A magnetic transmission comprising, a shaft mounted for rotation on a vertical axis, a follower magnet mounted on said shaft for independent rotation and vertical movement, va driver magnet mounted for rotation in i position to exert a turning moment on said follower magnet and means utilizing the magnetic flux of both magnets for raising said follower magnet against the action of gravity for drivingly connecting said follower magnet to said shaft.

19. A magnetic transmission comprising, a shaft mounted for rotation on a vertical axis, a follower magnet mounted on said shaft for independent rotation and vertical movement, a driver magnet mounted for rotation in va position t0 exert a turning moment on said follower magnet and means utilizing the magnetic flux of both magnets for'raising said follower magnet against the action of gravity for drivingly connecting said follower magnet to said shaft, said means comprising a magnetic shunt positioned above said follower magnet and being rigidly connected to said shaftf 20. A medium circulator for a three-fluid absorption refrigerating apparatus comprising, a hermetically sealed casing, a shaft mounted in said casing for rotation on a vertical axis, a fan secured to the upper end of said shaft, a follower magnet mounted on the lower end of said shaft for rotatable and vertical movement relative theretma magnetic shunt secured to said shaft above said follower magnet and a driver magnet mounted for rotation on the exterior of said casing ina position to exert a turning moment on saidV follower magnet, the arrangement being such that the magnetic flux of both magnets creates magnetic poles in said magnetic shunt-and the increased magnetic flux created when said follower magnet falls into step with said driver magnet induces magnetic poles in said magnetic shunt of sufficient strength to raise said follower magnet against said magnetic shunt to connect drivingly said vfollower magnet to said shaft.

HOWARD L. SCHUG.

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