US2873909A

US2873909A - Rotary devices and casing structures therefor

Info

Publication number: US2873909A
Application number: US464687A
Authority: US
Inventors: Nilsson Hans Robert
Original assignee: Svenska Rotor Maskiner AB
Current assignee: Svenska Rotor Maskiner AB
Priority date: 1954-10-26
Filing date: 1954-10-26
Publication date: 1959-02-17
Anticipated expiration: 1976-02-17

Description

Feb. 17, 1959 H. R. NILSSON 2,873,909

ROTARY DEVICES AND CASING STRUCTURES THEREFOR Filed'oct. 26, 1954 4 Sheets-Sheet 1 Feb. 17, 1959 H; R. NILSSON 2,87

ROTARY DEVICES AND CASING STRUCTURES THEREFOR Filed 061;. 26, 1954 4 Sheets-Sheet 2 Feb. 17, 1959 H. R. NILSSON 2,873,909

ROTARY DEVICES AND CASING STRUCTURES THEREFOR 4 Sheets-Sheet 5 Filed Oct. 26, 1954 Feb. 17, 1959 H. R. NILSSON I 2,873,909

ROTARY DEVICES AND CASING STRUCTURES THEREFOR Filed Oct. 26. 1954 4 Sheets-Sheet 4 IU'IIIH llll Unite Sttes Patent 2,873,909 v ROTARY DEVICES AND CASING STRUCTURES Hans Robert Nilssom Ektor-p, Sweden, as signorgby mesne 1 assignments, tou svenska lRotor'fMasRiner iAktiebolag,

Nacka, Sweden, a .corporationzofisweden Application oeoberizsprss'q, Serial N 4587 7*Clain 1s. (Cl."-.230i'i'143) Thepresent invention relates to a casin'gstructurefor' a rotary device of thekind providing,Woikingfspaces..or chambers 'between .iinterme'shing. rotors' 'oft the (screw wheel type. Such devices may'be employed ascompressors to-compressa gaseousifiilid orflas enginesgen'era ting power by the expansion- .of.fsuch fluid. Morespecificall-y, the invention relates .to aicasing structure for sucha device, having at :least .two. intersecting I parallel bores for a corresponding number of parallel rotors provided with intermeshing helical lobes .and grooves and [mounted to rotate in said bores.

. .One object .of .the invention .is,;to :provide a casing structure permitting. relative expansions of different parts of :the rotary device .due .to temperature differences .during .the .operationnof the same without warping-of the casing or derangement of the .close running .fit .between the rotors andthe boresenvelopingthe same;

Another objectof the invention is toprovideacasing structure in which onlythe parts thereof :CXPOSEdZtOShigh temperatures :or wear aremadeof a .high resistant rnaterial such as steel and which is-comparatively expensive while the rest of thecasingfis made ofa cheaper and notso'resistant material. Inthis respect the invention contemplates the useof a light weightmaterial such as light metals or light metal alloys in order torreduce the total=weightof theacomplete rotary device without affecting its performance.

2373,9119 Patented Feb. 17, 1959 "ice . 2 a Fig. 3 is an end view of the casing structuretaken in projection on the line 3- 3 ofFig. 2.

, Fig. 4 is a horizontal longitudinal section of the-casingstructure onthe line 4-4 of Fig. 2.

Fig. 5 is .an end view of the casing structure taken. in

projection on the line 5-5 of Fig. 2.

Fig. .6 isa transverse section of the casing structureon the line 6--6 of Fig. 2.

Fig. 7 is an end view taken in projection'on .the line 77-of Fig. 1 of a ring member to-close'the'outlet ends of the rotor grooves and provided with a conduit groove 1 for the working medium.

,A further 'objectof the inventiongis to providea casing structure having a cooling jacket providing an'efiective and uniform cooling.

.A still further object ofv theinvention is .to provide a,..double-'walled casing structuretha-ving a cooling jacket space between its walls, the inner one of said walls 'being relatively thin to promote an efieetive and uniform cooling .of the innerandouter walls .of the: casing structure but -yet able to withstand high pressure, differences between the working-chambersof the rotary device and the cooling jacket space thereof. I

According to the ir,1 vention the new casing structure comprises an inner lining andan outer housingsupportingsaid lining, the inner lining comprisingbarrelportions formed to envelop the-corresponding rotor sections and consisting of a material =too thinfiand insufficient in strength to withstand the gpressure conditions prevailing during operation of the device and the outer housing being provided to maintain the inner lining undeformed inits original shape. I p

Further objects and ,advantageszof the invention will be apparent from the followingdescription considered in connection with the accompanying drawings which form a .part of this specification, and of which: i

Fig. .l is -a vertical longitudinal section on. the line 11 of Fig. 3 through a rotary compressor device provided with a casingstructure constructed according tothe invention.

in said bores.

Fig. 8 is a horizontal longitudinal section of the ring member on theline 8-8 of Fig-7.

Fig. 9 is a longitudinal view of one half of the ring member takenin projection on the line 9 -.-9 of Fig. 7.

Fig. 10 is a detail section of the ring member taken onthelinelO-Jfi of Fig. 7.

.The'casing structure for the compressor has anouter housinglZ comprising two principally

cylindrical jacket portions

14 and 16 intersecting each otherand providing two intersecting

parallel bores

18 and 20 fora male and a female rotor, respectively, ofwhich the malerotor '22 is shown in Fig 1, said rotors being provided with intermeshing helical lobes and grooves and mounted .-in .a manner, which will be further described below, to rotate The

bores

18, 20 are provided-withinternal projections consisting of annularly disposed fins 24 evenly distributed along .the inside of the

bores

18,20 and so arranged that thefins .inone of the boresgpass over into the corresponding fins in the other bore. Said annular fins 24 serve as supporting 'means.for a thinwalled inner lining 26; comprising two

barreltportions

28 and 30, respectively, for each of the bores 18, 20 :formed to envelopthecorresponding-rotor. in'its respective bore. The

barr'el portions

28,,30 of. the lining ;-are provided withannularly disposed external;projections or fins 32 which are in engagement with the annular fins .24 on the insidewallof the

bores

18, 20 of the-outer housing 12. The fins 24 of theouter housing :12 are provided each with a-lateral groove 3j4andthe fins 32,

0fthe barrel portions

28, 30 of the lining are provided witha corresponding laterallyprotruding tongue portion 36 in keying engagement with the respective groove 34.; These finger portions interlockeach other in oneand the same direction so that an axialdilatation of the inner-lining 26 in relation to the outer :housing 12 ispermitte'd.

The "barrel portions.2,8 30 are inserted separately in

respective bores

18, 20 of the housing, the topportions of its fins 24 being cutaway at 3810 render the insertion possible and thereafter'the barrel 'portionsare turned so that they are brought to seat keyed by the fins' 24, 32 engaging each other. When the barrel portions 28, .30 are seated one pair of the meeting edges of said barrel portions, in the illustrated device the pair 40 at the .top, is welded together while the pair 42 at the bottom is :left free .to permit a perimetral dilatation of thezbarrel per.-

tions

28, 30. The centre of the bores for the lining z-in the outerhousingis preferably displaced upwardly a fraction of a millimetre to press thelining upwardxand minimize its displacement downwardly.

The fins 24 of the

bores

18,20 which support the inner lining 26 define a number of annular cooling spaces 44 evenly distributed along the casing structure and unload'to a high degree the inner lining from thepressure strains; "the same isXPOSGdtO during the'operation of the rotary device. The fins 32 of the lining 26 serveas further reinforcements for the lining wallso that the same-can'be made very thinbut yet be able to withstand high'pressure differences between the working chambers of the rotors ,and the cooling spaces 44 of the caing 3 structure. and uniform cooling of the inner and outer walls of the casing structure. v

According to a preferred construction the housing is made of a light metal or of a light metal alloy, such as aluminum or aluminum alloy, and the lining of a wear and high temperature resistant material, such as steel, in order to obtain a light but nevertheless stable casing construction.

The illustrated rotary device has a principally axial inlet 46 for the working medium which opens into an inlet chamber 48 provided at one end 50 of the outer housing 12. Said inlet chamber 48 is in part, at 52, located in the end 50 referred to of the housing 12 and in part, at 54, in an end wall 56 fastened to said end 50 of the housing 12. The ends58 of the rotors exposed to the inlet 46 are in part covered by means of a shielding plate 60 to prevent a direct communication between the inlet and outlet ducts of the device through any of the grooves of the rotors. For that reason the shielding plate 60 is arranged at the upper half of the intersection '62 between the rotor ends and properly displaced in relation to the direction of rotation ofv the respective rotor.

The inlet chamber 48 surrounds the inlet ends 58 of the rotors annularly and is provided at its top with an inlet connecting piece 64.

The outlet 66 of the rotary device is radial and located at the top of the casing structure toward the opposite end thereof in relation to the inlet end 46. The outer housing has an opening 68 and the inner lining 26 an opening 70 for said inlet 66 whichoutwardly ends in a connection piece 72. i i

The top portion 74 of the outer housing diverges from the generally cylindrical form it has in its other portions and is raised radially upwardly, said top portion 74 being provided with inside longitudinal reinforcing fins 76. As mentioned above, the inner annular fins 24 of the outer housing are cut olf at 38 and in order to carry the top intersecting portions 78 (Fig. 6) of the

barrels

28, 30 and prevent the corresponding part of the lining 26 becoming downwardly displaced, this part ofthe lining is provided with upwardly extending lugs 80 and the top portion 74 of the outer housing with a downwardly extending lug 82. A stud 84 is inserted through-the lugs to join them together.

To the ends of the rotors,

shaft portions

86, 88 are bolted by means of which the rotors are supported-in hub portions 90, 92 of steel or other high temperature and wear resistant material. Said hub portions enclose suitable bearing and sealing arrangements which, however, form no part of the invention and therefore are not shown in detail.

The hub portions 90 for the rotor shafts 86 at the inlet end are supported in seats 94 provided in the outer housing itself, said seats being strengthened by radial fins 96 extending as spokes across the annular inlet to the corre sponding ends of the rotors. The surfaces 98 of the outer housing fitting closely with the hub portions 90 are provided with a lining 100 of steel or other high temperature and wear resistant material to protect said surfaces from wear of the assembled parts.

At the outlet end, the rotors end approximately in a plane flush with the vertical transverse section through the centre of the outlet 66. The hub portions 92 for the rotor shafts 88 at the outlet end are carried by an internal flange 102 provided on an extension member 104 of the outer housing formed as a sleeve and bolted to the end 106 of the outer housing. The surface 108 of the flange 102 fitting closely with the hub portion 92 .is provided with a similar protection lining 110 as the lining 100 for the inlet hub portion 90.

The housing extension member 104 is closed at its outer end by a lid 112 through the centre of which is inserted an inlet 114 for a cooling medium to each rotor. The rotors and their shafts are hollow to form a central A thin wall of the lining enables an effective cooling channel 116'closed' at'the outer end 118 of the shafts 86 at the inlet endand divided by means of a partition wall 120 in two

halves

122, 124. A pipe 126 conducts the cooling medium from its inlet 114 to the channel half 122 most remote from said inlet 114. A number of radially distributed channels 128 in the bodies of the rotors conduct the cooling medium back to the channel half 124 most nearly adjacent to the cooling medium inlet 114 from which channel half the cooling medium isdischarged through outlets 130.

The male and female rotors are provided with synchronizing gears 132 located at the ends of the rotor shafts 88 and the rotor shaft 86 of the male rotor is providedwitha connection piece 134 for its attachment to a prime mover..(not shown).

In order to close the grooves of the rotors at their outlet ends a ring member 136 is provided which is welded to a sleeve 138 guided by the inner lining 26 of the casing structure. The closingring member 136 comprises two principally

annular half portions

140, 142 concentrically arranged around respective rotor shafts 88 and the ends of said

half portions

140, 142 which face each other pass over into chord bars 144 which are riveted together. The closing ring member 136 is provided at its top with a conduit groove portion or funnel 146 for the working medium which faces a circumferentially restricted portion of the outlet ends of the rotors and communicates with the outlet duct 66 of the rotary device.

The sleeve 138 attached to the closing ring member 136 consists of two

barrel halves

148, 150 conformable to the

barrel portions

28, 30 constituting the inner lining 26. The free end of the sleeve 138 is provided with '

ofiset fin portions

152, 154 keyed into

seats

156, 158 in the confronting ends of the lining 26 and the housing extension member 104.. This arrangement effectively holds the outlet funnel 146 in position and prevents the deformation of the composite structure of closing ring 136 and sleeve 138 at its top.

A number of evenly distributed distance bolts 160 connect the closing ring member 136 with the internal flange 102 of the housing extension member 104 to further stabilize the construction.

' The outer housing 12' is provided with a base 162 and a number of annularly and longitudinally disposed

external fins

164 and 166, respectively, to further reinforce the housing 12 and to improve the heat transfer to the atmosphere. I The invention also comprises any rotary device of the type referred to provided with a casing structure as set forth. What is claimed is: l. A housing structure for rotary devices of the kind having at least two intermeshing rotors with cylindrical envelopes and parallel axes, comprising an inner casing member having a wall providing cylindrical intersecting barrel portions with bores and axes corresponding with the envelopes and axes of the respective rotors, and an outer casing member around said inner casing member and encompassing the latter symmetrically thereto, each two of'said intersecting barrel portions of said inner casing having one pair of their longitudinal edges fastened together while the other pairremains free in order to allow expansion of said barrel portions in a circumferential direction, and at least one member of said inner casing and outer casing members being provided with interengaging tongue and groove arrangements having necessary axial clearance in the grooves to provide for the support of the inner casing member in the outer casing member while allowing axial expansion therebe- "tween. 2. A housing structure as claimed in claim 1, in which the inner casing member and the outer casing member are each provided with axially spaced projections in the form' of annular disposed-ribs provided with axially disposed slit and tongue means providing said tongue and groove arrangements for interengagement therebetween in one and the same direction so as to allow said axial expansion of the inner casing member relative'tothe outer casing member.

3. A housing structure as claimed in claim 1, in which the inner casing member is provided with radially outwardly, and the outer casing member with radially inwardly, directed lugs overlapping one another and pinned together.

4. A housing structure as claimed in claim 2, in which the annular ribs of the outer casing member comprise arcuate lengths of less circumferential width than the circumferential width of the barrel portions of the inner casing member in order to allow the introduction of said barrel portions and turning of the latter into slit and tongue engagement with the outer casing member.

5. A helical screw device operating with a gaseous medium and comprising a housing structure having an inlet and an outlet opening disposed adjacent opposite ends, a set of at least two inter-meshing rotors with cylindrical envelopes and parallel axes rotatably mounted in said housing structure, said housing structure comprising an inner casing member enveloping said set of rotors and an outer casing member around said inner casing member and encompassing the latter symmetrically thereto, the opening adjacent to the high pressure end being defined by principally radially directed duct means, in a vertical transverse plane to which the corresponding ends of the rotors terminate in flush, andv a composite ring element facing said ends of the rotor and including a circumferentially major portion closing said ends of the rotors and a circumferentially restricted minor pertion providing a conduit groove for the operating me dium and communicating with said radially directed duct means.

6. A helical screw device as claimed in claim 5, in which said composite ring element is carried by a composite sleeve structure inserted into and supported by said-inner casing member.

7. A helical screw device as claimed in claim 6, in which the ends of said composite sleeve structure remote from said composite ring element is provided with axially disposed fin members and the inner and outer casing members with corresponding slit means to receive said fin members.

References Cited in the file of this patent UNITED STATES PATENTS 1,344,331 Carrey June 22, 1920 1,879,136 Dubrovin Sept. 27, 1932 1,938,566 Birkigt Dec. 12, 1933 2,041,699 Dahlstrand May 26, 1936 2,066,788 Lysholm Jan. 5, 1937 2,316,813 Schaper Apr. 20, 1943 2,427,244 Warner Sept. 9, 1947 2,510,606 Price June 6, 1950 2,584,899 McLeod ,Feb. 5, 1952 2,592,476 Sennet Apr. 8, 1952 2,628,067 Lombard Feb. 10, 1953 2,755,990 Nilsson et al. a July 24, 1956 FOREIGN PATENTS 486,340 Great Britain June 2, 1938 644,977 Great Britain Oct. 18, 1950 a 908,254 Germany Apr. 5, 1954