US 2122378 A
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Description (OCR text may contain errors)
June 28, 1938. A. A. M CORMACK 2,122,373
v RESILIENT YIELDING MATERIAL Filed Oct. :50, 1935 lww INVEN 1 OR ATTORNEYS Patente utime 28, 1938 STATES PATENT orrica nEsmmN'r mmmo MATERIAL v Alex A. McCormack, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application Qctober 30, 1935, Serial No. 47,516
2 Claims. (Cl. 106-22) This invention relates to refrigerating app tus and more particularly to a resilient yielding material for acting as a seal between metal parts in a refrigerating system.
In refrigerating systems it is necessary at many relatively short time causes it to become unsetisfactory for most sealing purposes and ordinarily permits the seal to leak after a period of time.
It has been proposed to use a polymer of chloro- 2-butadiene-L3 as a seal between metal parts of refrigerating systems in the place of rubber or other elastic materials which might be used. However, I find that ordinary compounds containing this polymer are not well suited for refrigerating systems because they tend to swell or increase in dimensions considerably when in contact with the refrigerant and the lubricant in the refrigerating system and because they tend to disintegrate or partially dissolve in the presence of a refrigerant and lubricant.
It is an object of my invention to provide an improved yielding, resilient, elastic rubber-like material containing no rubber which will satisfactorily and permanently provide a resilient elastic seal between metal parts of a refrigerating system.
It is a more specific object of my invention to provide an improved yielding elastic rubberlike material containing no rubber which will satisfactorily and permanently provide a seal between metal parts of a refrigerating system containing a halo derivative of a hydrocarbon and particularly systems containing chloro iiuoro derivatives of an aliphatic hydrocarbon such as difluorodichloromethane and tetrafiuorodichloroethane.
Further objects and advantages of the present invention will, be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present inventionv is clearly shown.
In the drawing:
Fig. 1 is a view of the refrigerating system, partly diagrammatic, illustrating one form of seal embodying my invention; and
Fig. 2 is an enlarged sectional view of a shaft portion of a refrigerant compressor illustrating another seal embodying my invention.
Briefly, as a resilient seal between metal parts in a refrigerating system, containing a halo derivative of a hydrocarbon, I employ a compound containing the following substances in parts by volume:
Parts Polymer of chloro-2-butadiene-1,3 100 Light calcined magnesium oxide 10 Zinc oxide :10' FF wood rosin 2 Channel black (carbon) 29 Referring now more particularly to the drawing, there is shown a refrigerating system generally designated by the reference character containing a refrigerant such as difiuorodichloromethane or tetrafluorodichloroethane and a lubricant such as a mineral base refrigerator oil 22 shown in the bottom of the crank case of a compressor 24. The compressor 24 is driven through its drive shaft 26 by an electric motor 28 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser 30 where the compressed refrigerant is liquefied and forwarded under the control of a suitable automatic valve 32 to an evaporating means 34 located within an enclosure 36 containing a medium to be cooled. Within the evaporating means 34 the refrigerant evaporates under a reduced pressure and is returned to the crank case of the compressor by conduit means.
The drive shaft to the compressor extends through the wall 38 of the compressor which wall is provided with a bearing 40 for supporting one end of the drive shaft. This wall is also provided with a hollow boss 42 for receiving a shaft seal which prevents the escape of refrigerant and lubricant from the crank case of the compressor through the opening provided for the drive shaft. This seal also prevents the ingress of air into the crank case. This boss 42 is provided with an end plate 46, fastened to the boss by screws 48.
the reduced portion 54 of the drive shaft 26.
. frigerant to this space. It will thus be seen that 2 This end plate is provided with an annular sealing surface 50 with which the shaft seal cooperates to form a relatively rotating fluid tight Joint toprevent the escape of refrigerant and lubricant between the sealing ring 52 and the reduced por-' tion 54 of the drive shaft 26 so as to form a fluid tight seal between the sealing ring 52 and the reduced portion 54 of the drive shaft 25. This is performed by a cup-shaped annular member 58 which surrounds the reduced portion 54 of the drive shaft 26 and holds one face and the adjacent portion of the outer periphery of the wedge-shaped rubberlike sealing ring 55 and also surrounds and rides upon the outer periphery of the sealing ring 52. This cup-shaped annular member 58 has an integral flange which receives one end of a compression type coil spring Gil. This coil spring 60 provides the force necessary for the cup-shaped member to wedge the resilient elastic rubberlike ring tightly between the sealing ring 52 and the reduced portion 54 of the drive shaft 25 as well as to provide sufficient force to hold the sealing ring 52 in sufliciently tight sealing engagement with the sealing surface 50 upon the end plate 56.
The other end of the compression spring 60 is held by a disc or washer 62 which presses against a shoulder 64 formed between the reduced portion 54 and the bearing portion of the drive shaft 26. The wedging of the rubberlike wedgeshaped ring 55 between the sealing ring 52 and causes the entire shaft seal to rotate with the shaft 26. This causes relative rotation between the sealing ring 52 and the sealing surface 50.
In order to lubricate these relatively rotating sealing surfaces, I have provided a passage for oil for lubricating the space containing the shaft seal. ,While this passage 66 is intended for oil, it also permits the free access of rethe rubberlike wedge-shaped ring 56 is exposed to the action of both refrigerant and lubricant. It is well known that rubber deteriorates in the presence of oil and is also attacked by the ordinary refrigerants. I have also found that ordinary compounds of rubber substitutes also are unsatisfactory for such use in a refrigerating system since most of them are subject to considerable swelling which is sufllcient to distort the ring 55 and to prevent its proper action. v
I have, therefore, provided an improved ring 55 of a molded composition which will meet the conditions required for this service. This composition contains no rubber and will withstand immersion in oil at relatively high temperatures without disintegrating or increasing the dimenof between 65 and '15 according tothe' Shore scleroscope system of measurement. It Is comcassava pounded according to the following formula in parts by volume:
Parts by g Specific y volvolume me gravity Pol er oI ehloro-2-butadIene-l. 3-. 100 66. 2 i. 24
Li t calcined magnesium oxide 10 6. 6 2. 4 Zinc oxide i0 6. 6 5. 57
FF wood rosin 2 1. 3 l. 4 Channel black.. 29 19. 2 l. 75
The channel black is a grade of carbon black. However, ordinary carbon black or lamp black or even graphite may be substituted in the same proportions for the channel black with very little or no change inproperties. This'substance may be used for various types of gaskets and washers used'in refrigerating systems containing halo derivatives of hydrocarbon and other uses. In the place of FF wood rosin, any equivalent resin ,may be used.
In Fig. 2, I have shown another form of seal having this same composition. In this modification, there is shown a wall I25 of a refrigerant compressor, preferably containing a lubricant and a halo derivative of a hydrocarbon as a refrigerant such as difluorodichloromethane or tetrafluorodichloroethane. This wall Iwis provided with a bearing I22 which supports one end of the compressor drive shaft I24 provided with a reduced portion I28 forming a shoulder 52s upon the drive shaft. Surrounding this reduced portion of the drive shaft is a bellows type of shaft seal which is enclosed within a hollow boss I provided with an outer ring I32 which clamps the fixed end plate I84 of the shaft seal to the wall of the compressor. This end plate supports one end of a flexible metal bellows I35 which surrounds the reduced portion I25 of the drive shaft I24. The other end of this bellows is provided with a sealing ring I35 of a good wearing material which is provided with a flange -I4Il which in turn supports one end of the compression spring I42 extending between the flange I45 and the fixed end plate I24 for resiliently urging the sealing ring I28 toward the shoulder ever, I have found that it is dimcult to provide a.v
hard, smooth, perfectly flat, concentric, wearing surface upon the shoulders of the shaft and I have therefore proposed a separate sealing ring I44 which is resiliently held in placebya resilient elastic rubberlike sealing ring I48 preferably of the some molded composition as specifled in detail above for the improved sealing ring 58. I find that such a compound foruse in connection with halide refrigerants is superior to any similar compound heretofore used. This rubberlike sealing ring extends around three sides of the annular metal ring I44 and fits tightly between the rings I44 and the reduced portion I25 of the drive shaft I24.
The metal seal ring I44 is preferably hardened and ground so that a p rfectly smooth face is provided-for mating with sealing surface I of the ring III. This seal likewise is exposed to the as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope oi the claims which follow.
t is claimed is as follows:
i. A resilient seal for refrigerating systems comprising a substance containing ingredients about in the following proportions by volume:
Per cent Polymer of chloro-2-butadiene-L3 68.2 cesium oxide 6.6 Zinc mflde 6.6 Wood xosh 1.3 Car I L 19.2
2. A resilient material comprising a substance containing ingredients about in the following proportions by volume:
Ports Polymer oi chloro-Z-butadiene-IB 100 Magnesium oxide 16 Zinc oxide 10 Wood rosin 2 Carbon 29 A. MccoRMAcKl