US1796535A - Blade construction for compressors of the rotary type - Google Patents

Description

March 17, 1931. w. G. E. ROLAFF BLADE CONSTRUCTION FOR COMPRESSORS OF THE ROTARY TYPE Filed Sept. 26, 1927 2 Sheets-Sheet l /NV5N7'OBZ IVALTEB 6.6. BOLAFF.

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March 17, 1931. w. G. E. ROLAFF BLADE CONSTRUCTION FOR COMPRESSORS OF THE ROTARY TYPE Filed Sept. 26, 1927 2 SheetsSheet 2 hwcxvro/e: WAAJ'EE G. 6.1604AFF puma Mar. 17, 1931 UNITED STATES WALTER G, E. BOLAFF, OF KIRKWOOD,- MISSOURI BLADE CONSTRUCTIOTI COMPRESSORSQI' THE ROTARY TYPE application filed September 26, 1927. Serial 110. 221,977.

The general object of this invention is'to provide an improved piston blade for use in rotary compressors, which, in operation, will provide an eflicient seal between the blade and the walls of the blade slot without creating undue friction, which will automatically compensate for wear, and which will prevent angular displacement, or cooking, of the blade within the slot, so that the entire surface of the blade will bear upon the walls of the slot.

With the above general object in, view, my invention resides, broadly, in providing an expanding blade which, in operation, is capable of automatically adjusting itself un-' der pressure to engage thewalls of it's slot with suflicient force to provide an effective seal between the wearing surfaces of said 7 tion of the rotor to make sealing contact with" blade and the walls of said slot;

My invention further resides in providing a blade which shall not only be capable of expanding at right angles to the axis of rota- 'the walls of the slot, but which shall also be capable of expanding in a direction parallel to said axis, whereby said blade will operate to effect a seal with the end walls of the cylinder. This latter feature of a blade expanding parallel with the axis to engagewith compensating pressure the cylinder ends is disclosed in my prior Patents dated October 1st, 1918, and No. 1,358,176, dated November 9th, 1920. 1

While the blades of these prior patentswer vastly superior in operation to solid blades, or other forms of blades of the prior art, it was found that unless very accurately fitted to the blade slot in the rotor, or, in the present arrangement, to the slot in the cyhnder wall, they would allow too much oil to go into the cylinder, which oil, in the case of the use of methyl chloride as the refrigerant, would become heavily impregnated with this substance and would re-expand in the low pressure side of the cylinder and thus seriously reduce the efiiciency of the machine. In other words, while the expanding blades of my prior patents form and maintain a perfect seal with the ends of the cylinder, they .do not form such a provision of some means,

seal with the walls of the p blade slot in the rotor. Again, even a blade fitted very accurately in the blade slot of the rotor'would, by reason of the direction of forces exerted .upon it," assume a slanting or cocked position in the slot which would cause is to wear on the upper and lower edges and gradually detrimentally affect theefliciency of the machine 4 actly the same manner as if the blade had been loosely fitted in the first place.

For the above reasons, and for others which need not be mentioned, the use of ordinary lubricating oil was found impracticable, and glycerine was substituted therefor in conjunction with methyl chloride as a refrigerant. While glycerine is an eflicient lubricant, it was found that it developed acids which were very injurious to the machine as a whole. These difficulties necessitated the therefore, which would permit the use of ordinary lubricating oil and at the same time prevent the leakage of oil and refrigerant into the low side'of the system, which makes it necessary to shut down the machine from time to time to remove the accumulation of lubricant from the for the same reason and in exlow side. Consideration of the conditions resulting from the operation of compressors having only blades which sealed against the ends of the cylinder induced the conclusion that the difliculty lay in an imperfect sealing of the blade in the slot. As a result, the present type ofblade was evolved and it has been found in practice that such a blade entirely removes the objections above noted, and in the use of this blade I am now able to employ ordinary oil as a lubricant in conjunction I Figure 1 is a cross-section through a rotary compressor provided with a preferred form v of my improved blade;

Figure 9, is a section on the line 2-2 of i Fig. 1 and viewed in the direction of the arrows;

Fi e 3 is a view in front elevation of the housing enclosing the spring for maintaining pressure on the blade;

Figure 4 is a view in front elevation ofla double compensating blade; Figure 5 is a cross-sectional view thereof;-

I constructions of blades showing various ways of producin the expanding action of the blades accor ing to my invention; and

Figure 11 is a view in cross-section on an enlarged scale of the preferred form of blade, shown embodied in the structure of Fig. 1';

Referring now particularly to Figs. 1 and 2, the numeral 1 indicates a casing of a rotary compressor in which is mounted a shaft 2 driven by any conventional means such as a pulley 3 mounted on the end of said shaft extending beyond the casing. The casing 1 encloses a cylinder 4 within which is mounted a rotor 5, which is adapted to have a gyratory movement imparted thereto so as to cause it to roll over the inner wall 6 of the bore of the cylinder. Motion of the rotor is effected through the medium of an eccentric ring 7 which is mounted op an eccentric 8 formed on the shaft 2. Loosely mounted on the eccentric ring 7 is a ring 9 which supports on its periphery a series of roller bearings 10 on which is mounted a bearing ring 11 which, in turn, is in engagement with the inner wall of the rotor 5 and serves as the supporting bearing for the rotor. The rotor 5 is 'rovided with an integral flange 12 which 0 oses one end of the cylinder, as shown by Fig. 2, being yieldingly held in such contact through the medium of a circular plate 13 forced against the outer side of the flange 12 by means of springs 14. The rotor is adjusted-in position to engage the wall 6 of the cylinder by first turning the eccentric ring 7 over the eccentric 8, and when the proper contact of the rotor with the wall of the cylinder is thereby effected, the eccentric ring is permanently locked 1n position on the eccentric 8 of the shaft by means of a key 15, or in any other suitable manner. It will be readilyseen that as the shaft revolves, the eccentric ring 7 being locked in position on the eccentric 8 of the shaft, will itself act as an eccentric to impart, in its rotation, a gyratory movement to the ring bearing 9-11, as it rotates within the latter, and will impart a corresponding movement to the rotor 5. Extending through the wall of the cylinder 4 is an inlet port16, and at a suitable distance therefrom, an outlet port 17. The latter is closed against back pressure by avalve 18 which is yieldingly held against the outer end of the port 17 by means of a leaf spring 19. The port 17 discharges into a chamber 20 from which leads a discharge pipe 21. In practice, the discharge pipe 21 would communicate with a separating chamber from the bottom of which a pipe 22 communicates with the cylinder to return lubricant to the machine.

As these features, however, form no part ofthe present invention, they are not illustrated. They are clearly shown in my allowed application Serial No. 33,952, filed June 1st, 1925, patented 1 June 14,1927,N0. 1,632,562.

Extending through the wall of the cylinder 4 between the inlet port 16 and outlet port I 17 is a rectangular slot 23 in which is mounted myhmproved blade 24. Secured to the casting of the cylinder over the slot 23 is a plate 25 (Figs. 1 and 3) having an extension 26, closed at its outer end and provided with a circular bore which extends also through the plate 25. Secured to the outer end of the blade 24 is a rod 27 having on its outer end a disk 28 which fits snugly in the bore of the extension 26. Mounted in the bore of this extension is a coil spring 29 which bears at one end against the closed end of the extension andat itsother, against the disk 28. This spring operates to hold the blade 24 in yieldingcontact with the periphery of the rotor 5. As shown by Fig. 2, the blade 24 is of a width to extend between the end walls of the cylinder, one of these walls 30 being fixed, as indicated in Fig. 2, and the other being formed by the flange 12 of the rotor, as previously referred to. For ordinary use, the form of blade which,I prefer is that shown in Fig. 1 and on an enlarged scale in Fig. 11. This blade is made of two similar members 31 and 32, respectively, separated longitudinally and correspondingly inclined at their opposite ends to provide angular meeting surfaces 33 and 34, one end of each blade being enlarged, as indicated at 35, for this purpose. The rod 27 l: secured on one of these enlarged ends. It will readily be seen that pressure of the spring 29 will cause the inclined surfaces 33 and 34 of one of the members 31' (the member 32 as shown in the drawing) to slide over the similar inclined surfaces of the other member, thus tending to separate the two parts of the blades laterally and force their outer surfaces against the walls of the slot 23. This operates to form an effective sealing contact between the blade and the walls of its slot, and the two above referred to,

manner shown in my pending application and for this purpose I-have shown conventionally a pipe 36 connecting the high pressure chamber 20 with the bore of the extension 26 beyond the disk28. In initialy starting the machine, the spring'29 will a 0rd sufiicient pressure tomaintain the blade in sealing contact with the periphery of the rotor. Thereafter, as pressure is built up within the machine, such pressure will also be exerted on the blade and the higher the ressure the more firmly the blade will be orced against the rotor and as ,well against the sides of the blade slot.

Where it is desired to have a blade expand in two directions so as to form a compensating sealing contact. with both the end walls of the cylinder and the walls of.the blade slot, I employ. the construction of blade shown in Figs. 4 and5. In this construction, the contact with the end walls of the cylinder'is produced by a pair of packing plates 37 and 38, respectively, inclined on their inner sides toprovide a wedge-shaped space, and in this space I locate a freely movable wedge plate 39, the side edgesTofwhich engage the inclined edges of the packing plates so that when pressure is exerted upon the top of the wedge plate, it will tend to force the wedge plate inward and thus separate the packing plates, forcing their outer ends into engagement with the ends of the cylinder.

In this construction, the packing plates 37' and 38 and the wedge plate 39 are mounted in a recess 40 formed on the outer side of one member 41 of the blade otherwise formed as the blade 24 shown in Fig. 11, such member being suitably thickenedas shown in Fig. 5 to provide for saidrecess. On the side opposite to that containing the recess ,40, the

" member 41 of the blade is inclined at its top and bottom, and the other partof the blade 42 is correspondingly inclined to provide the inclined meeting surfaces 33 and 34 described with reference to the construction of Fig. 1 1.

. It will be noted that a slight space 43 is provided between the top of the wedge plate 39 and the top of the recess 40 which will permit the pressure within the casting to exert its force upon the top of the wedge plate In Fig. 6, I have illustrated a modified construction of blade embodying the principle of the blade shown in Fi s. 5 and 11 as to the wedging action alforde by opposed inclined surfaces, but in this construction the inclined meeting surfaces, indicated at 44, are 10- rious waysof securing the wedging action cated at the center of the blade instead of at both ends as in the construction first referred to.

In Figs. 7 to 9, inclusive, I have shown vaby inclined meeting surfaces. In Fig. 7, the blade is composed of two similarly shaped members 45 and 46 oppositely inclined from blades 48 is provided with a 49 projecting over the upper end of the other 'ment of the members 52 member 50 of the blade and has a set screw 51 mounted therein and adapted to bear upon the top of the member 50 of the blade, so that by screwing down on the set screw 51 the two members of the blade may be moved laterally to cause them to engage the side walls ofthe blade slot with sufficient force to provide a sealing contact without producing undue friction in operation. It will be understood, of course, in this connection, that there is always a film of oil between the contact surfaces of\. the blade and the wall of the slot, and this applies to all of the con structions. In Fig. 9, I have shown a blade composed of three parts, two outer members 52 and 53 and an inner member 54, the members 52 and 53 having their inner sides inclined outwardly in an upward direction,-

and the inner member 54 being correspondingly inclined in the opposite direction. Pressure, either automatic or otherwise, will, of course, be exerted on the end of the member 54 to cause the necessary lateral displaceand 53 to produce sealing contact with the walls of the slot.

In-Fi z 10, the expansion of the blade is produced bymeans of a spring. In this construction, one member of the blade 55 is made ofsuificient thickness to substantially fill the blade slot, and intermediate'itsends is provided with a recess 56 in one of its sides, in which is mounted a plate 57 normally lying flush with the side of the blade, and between this blade and the bottom of the recess 56 is located a spring 58 which will operate to force the plate 57 outwardly into yielding contact with the wall of the blade slot.

The blades illustrated, in Figs. 6 to 10 are largely presented for the purpose of showing that the broad idea of causing a blade to expand in its slot so that it will always form sealing contact therewith may find its embodiment in various arrangements of the numbers of the blade, to support the statement which I now make that such broad idea of the invention is not limited to any one of the particular embodiments of the invention which I have shown. However,I may state that where it is desired to provide a compensating sealing contact between the blade and the walls of its slot, I prefer the construction shown in Figs. 1 and 11. Where "a double expanding blade is desired, I, of course, prefer the construction shown in Figs. 4 and 5.

Furthermore, the invention is not limited to the use of the expanding blade with pressure developed in the machine, as where llplS required for producing relatively low pressures, the spring 29 may be found suificient to exert the necessary pressure to maintain a sealing contact of the blade with the rotor. However, as the use of pressure developed in the machine affords a compensating action on the blade, causing the blade to be forced into firmer contact with the rotor, the higher the pressure that is developed by .the latter in the machine, and as this action. moreover,is automatic,'I practically in all cases find it desirable to employ the pressure developed in the machine in conjunction with the spring 29.

I claim:

1. In a compressor having a rotor and a c linder affording a blade slot, a blade slida ly mounted in said slot and bearing at one end on the periphery of said rotor to separate the inlet from the discharge of said cylinder, said blade comprising two members placed side by side and having a point of contact providing corres onding inclined surfaces, one of said mem ers projecting beyond the other at its inner end and providing the contact surface for the rotor and the other member bein longitudinally movable with respect to the first member, and means for continuously exerting yielding pressure on the outer end of said other member to cause its inclined surface to ride over the inclined surface of the first named member, whereby to cause said blade to expand and maintainsealing contact with the walls of its'slot.

2. In a compressor having arotorand a cylinder affording a blade slot, a blade slida ly mounted in said slot and hearing at one end on the periphery of said rotor to separate the inlet from the discharge of said cylinder, said'bla-de comprising two members placed side b side andhavmg a point of contact provi ing corresponding inclined surfaces, one of said members projecting beyond the other at its inner end and providing the contact surface for the rotor and the other memher being longitudinally movable with respect to the first member,and means for conmeans for continuously applying pressure generated by the compressor to said blade.

4. A bladefor use in the blade slot of ainclined meeting surfaces, and a pair of expansible packing plates mounted'on one of said members.

6. A blade for use in the blade slot of a compressor having a rotor, comprising two members expansible under pressure at right angles to the axis of the rotor, and two other members expansible under pressure in a direction parallel with the axis of the rotor.

In testimony whereof, I have hereunto set my hand.

' WALTER G. E. ROLAFF.

tinuously applying pressure generated by too compressor on the outer end of said other member to cause its inchned surface to ride over the inclined surface of said first named blade, whereby 'to expand said blade and cause it to maintain seal ing contact with the walls of its slot.

3. In a compressor having a rotor and a cylinder affording a blade slot, a blade slidof the cylinder and the walls of said slot and

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