US1026887A - Rotary engine. - Google Patents

Description

J. H. VAN DEVENTER.

ROTARY ENGINE.

APPLIGATION FILED MAY 15,1911.

1,026,887, Patented May 21, 1912.

A 2 SHEETS-SHEET 1.

J. H. VAN DEVENTER.

ROTARY ENGINE.

'APPLICATION FILED MAY 1s, 1911.

Patented May 21, 1912.

z SHEETS-SHEET 2.

INVENTOE ZM M UNITED sTATEs PATENT oEEIoE;

JOHN H. VAN DEVENTER, 0F BUFFAIiO, NEW YORK, ASSIGNOR T0 BUFFALO FORGE COMPANY, 0F BUFFALO, NEW YORK, A CORPORATION OF NEW YORK.

ROTARY ENGINE.

To all whom it may concern:

Be it known that l, JOHN HERBERT VAN DEvEN'rEn, a citizen ot the United States of America, residing `at Buffalo., in the county of Erie and State of New York, have invented certain new and useful Improvements in Rotary Engines, of which the following` is a full, clear, and exact description.

`My invention relates to rotary engines and more particularly to engines with rotors cach having a plurality of spirally disposed and intermeshing tooth blades.

Some of the objects of my invention have been to provide a rotary engine in which all end thrust on the shafts might be eliminated; also one in which there should be substantially no leakage of the fluid under pressure between ends of the rotors andthe engine heads. To this end I employ two or more rotors each provided with one or moreI right hand and one or more left hand spirally arranged tooth blades and l place the admission ports between the intermeshing rotors and at the junction points of the right. hand and left hand spil-ally arranged tooth blades; thus I accomplish the above objects and at the same time provide a very powerful rotary engine, which occupies a small space.

Another object has been to provite a rotary engine which should be very eiliv cient in operation andeconomical in fluid consumption. ln order to attain this object I have arranged the inlet porty of my engine so that the fluid under its initial pressure is cut oti` from each bucket'. as the rotors revolve. b v the bucket which follows. or shortly after the time of admission of the lhiid to said buckets. The fluid eontained in each bucket after the supply has been cut ott, continues to expand until each bucket has tinished its cycle or until it is opened to the atmosphere, into which it is then exhausted.

By slight nualitication of the principal torm shown and described in this application, l provide a reversible aml also a multiple stage rotary engine which is very etlicient and compact.

The above. together with many other advantages which will bc apparent to those skilled in the art. have been accomplished by my invention herein Ishown and dcscrilwd.

ln the specilication and appended claims the term fluid will be used as a general term for the pressure medium but the engine is Specification of Letters Patent.

Application led May 15, 1911.

.of the same. sectional end vlew of the same and is taken Patented May '21, 1912.

Serial No. 627,166.

especially adapted for the use Aof steam and obviously it is applicable to be driven with either steam or compressed air as well as any fluid under pressure.

Reference is to be had to the accompanying drawings, forming art of the specification, in which like eiaracters of refer ence indicate like arts throughout the several views of whie Figure 1 is a plan view of my en ine. Fig. 2 is an end sectional elevation o the same taken on line A-B of Fig. 1. Fig. 3 is a bottom View of the en ine with the rib broken away and shows t e buckets as formed by the tooth blades on the rotors. Fig. 4 is a sectional end elevation and shows an inlet port of a modified shape. Fig. 5 is a diagrammatical view of a slightly modiod form of my invention and shows a twin or two-stage eti'ect. Fig. 6 is a diagrammatical sectional end view of the modified Jform shown in Fig. 5 and is taken on line (l-D of that figure. Fig. 7 is a diagramn'iatieal front elevation of a reversible engine. Fig. 8 is a diagrammat-ical plan view Fig t) is a diagrammatical on line lL-F of Fig. 8.

In the drawings, (Figs. 1 to 3) 10 is the base of my engine which is provided with .suitable bearings 11. Shafts 12 and 1Q are rotatably carried by the bearings 11 and the said shafts have mounted thereon, in a rigid manner, rotors 13 and 13 respectively. Each rotor is provided with 'a plurality of right hand spit-ally disposed tooth blades 14 extending across the rotor for substantiall one-halt its length and a plurality of le t hand spirally disposed tooth blades 15 extending across the rotor for substantially the remaining halt of its length. The said right hand and left hand tooth blades meet aml join one another at the center of each rotor. The right hand tooth blades 14 of termeshing tooth blades, has been developed.

Obviously if desired this rib may be continued around the rotors and `nibstantially surround them and thus form a casing in which the exhaust fluid may be confined and from which it may be carried to any desired place. 174 is the inlet port which is disposed at the center of the length ot' the rib lo and near its peak. This port is preferably disposed in a horizontal plane and extends -from one side of the rib through to the opposite side so that'the [luid entering under pressure will be caused to impinge on both rotors at the saine time. Suitable ports 1S and 1.9 are provided through which the tiuid is conducted to the inlet port 17, the port lt) being provided at its outer end with a screwthread, whereby suitable piping may be connected thereto. l

In Fig. t I have shown a modified inlet port 17a. In this figure the upper wall of the port is shown concave thereby producing a turbine etl'ect by causing the Huid to impinge upon the tooth blade at a tangent to the path of travel of said tooth blade.

In Figs. 5 to 9 I have shown in a diagrammatieal manner a few of the many vav ried modifications of my invention. .In Figs. 5 and 6, three rotors 20, 2,1 and 22 are i disposed one above the other with their tooth blades intermeshing. These rotors are provided with shafts 23, 24 and 25 respectively. Two ribs, 2o kand QT, are used and are placed on opposite sides of the engine; rib 26 being arranged between rotors 20 and 2l, and rib Q7 between rotors 21 and 22. Thus a twin el'ect or a two-stage elfect may be obtained by employing only three rotors instead of four and thereby making avery compact engine. The direction ot rotation of these rotors is indicated by the arrows in Fig. 6. Then arranged as a twin engine the fluid under its initial pressure will be supplied to inlet ports of both ribs but when arranged as a two-stage engine the fluid under initial pressure may, for instance, be supplied to the inlet. port. of the rib 26 and the inlet port of the rib supplied with the exhaust from the roto- rs 20 and 21. Obviously, when used as a twostage engine, as above described. the inlet ports carrying the fluid to the rotors l and 22 may be increased in length so as to coinpensate t'or the decreased pressure ot the tiuid which is exhausted from the rotors 2t) and 2l. l `urther1nore by employing four rotors a triple eti'ect may be produced.

In Figs. T to 9 a reversible engine is shown. ln this inoditication two shafts 2S and 29 are employed and upon each is mounted a rotor 30 and 8l respectively. 'Ihe blades of each ot these rotors are preferably disposed in three alternately arranged positions. 'a'. c., the rotor 30 has two sections 32 and 33 which are provided with lct't hand spirally disposed tooth blades and one section 34 with right hand spirally disposed tooth blades, and the rotor 3l has two sections provided with right hand spirally disposed tooth blades 35 and 3G and one section ,provided with left hand spirally disposet tooth blades 3T. These sections in the rotors are so arranged that the tooth blades of one rotor mesh with those ot the other rotor. Two ribs 3S and it!) are provided in this type. oi engine. The ribs are arranged one on each side ot thc rotors and preferably are each of such a length as to only extend across the rotors` for about' twothirds o't' their length. ri`hc rib nvextends across thefctions 32 and B-t of rotor 30 and sections 85 and 3T of rotor l while the rib Si) preferably extends across the sections 33 and 3l of rotor 3() and Athe sections f'and 37 of rotor 3l. through the inlet port in the rib 23.*? rotors will revolve in the direction ot' the full line arrows. llt) and il, but when the. tluid enters the inlet port in the r-.b 3S) the rotors will then revolve `in the direction of the dotted line arrows #l2 and 23. i

By referring to Fig. l it will clearly be seen that between the tooth blade i-- on the rotor 13L and the two tooth biades 4.5 and 46 on the rotor 153 betwtcn which the tooth blade 4.4 meshes, is formed a bucket 4T. llach rotor being provitjled with a plurality of right hand and let't hand spirally dis'- posed tooth blades. the formation ot' but one double-sided bucket is started by the internieshing' tooth blades at any one time. .it substantially the instant when such a bucket is started during the revolution ot' the rotors, the tiuid under pressure is made to iinpinge thereon, thus causing the capacity of said bucket to gradually increase on account ot' the recession of the points ot` mesh ot' the tooth blades forming the saine toward the ends of the rotors. Then any sucl'nbucket is under pressure and the rotors are thcrebv the revolved. thc tooth bladesI forming one side ot said bucket when passing the port cut o'tl the supply ot liuid from said bucket- (see Fig. 3). thus allowing the fluid contained in said bucket to expand until it has developed its 'full capacity or until the tooth blades it'orniing said bucket. cease to mesh. It is evident that the ratio of expansion may be ll'hen the tlnid is 'forced IO O atthe junction points of the right hand andv left hand spiral tooth blades at the center of each rotor angular pockets are formed land as the fluid under pressure is admitted at this point, any leakage at the end of the rotors is impossible. The only place where leakage may occur is between the perimeters of the rotors and the rib butl as it is possible to make a very good and practically non-leaking contact at this point, there is very little leakage in my engine thus making it very efficient in o eration.

Obviously some detailed modifications of my invention as herein shown and described may be made without departing from the spirit of my invention and I do not wish to be limited to the exact embodiment herein shown and described.

Having thus described my invention, what I claim is:

. l. In a rotary engine, the combination of two or more intermeshing and engaging rotors. shafts secured in said rotors and 10- tatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at r1ght angles to the axis thereof toward one end of said rotors, and a pluralityof left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right and left hand'tooth blades of each rotor meeting and joiningr and thereby forming angular pockets and a fluid inlet provided with a port for conducting fluid under pressure. to said rotors, said port heilig so located and formed that said conducted fluid will be impinged within the angular' pockets formed by said tooth blades.

2. In a rotary engine, the combination of two or more intermeshing and engaging rotors, shafts secured in said rotors and ro-,

tatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors. -and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right hand and left hand spirally disposed tooth blades of one rotor meshing respectively with said left hand and right hand spirally disposed tooth blades of another rotor. whereby buckets are formed between the meshing tootlfblades of said rotors, and a fluid inlet. provided with a port for conducting fluid under pressure to said rotors, said port being so located and formed that said conducted fluid will be impinged within the. buckets formed by said tooth blades.

3. In a rotary engine the combination of two or more intel-meshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotorsV located in a plane at rlght angles to the axis thereof toward one end of said rotors and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets, and said right hand and left hand spirally disposed tooth blades of one rotor meshing respectively with said left hand and right hand spirally disposed tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of said rotors, and a fluid inlet provided with a port for conducting fluid under pressure to said rotors, said port being so located and formed that said conducted fluid will be impin Ved within the angular pockets formed by said tooth blades.

4. In a rotary engine the combination of two or or more intermeshing and engaging rotors. shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on -said rotors located in a plane at right angles to the axis thereof toward one end of said rotors, and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets and a fluid inlet provided with a port having lateral passages leading into said pockets whereby the conducted fluid impacts in said pockets and against said tooth blades substantially in the direction of rotation of said rotors.

5. ln a rotary engine the combination of two or more inter-meshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand 'spirally disposed tooth blades extending points toward the opposite end 'of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets, and a rib extending substantially parallel to-the axes of said rotors and in contact with the peripheries of said rotors for at least a portion of their circumferences, said rib being provided with a port for conducting fluid under pressure to the said angular pockets of said rotors.

G. In a rotary engine the combination of two or more mtermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed toot-h blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets, and a rib extending substantially parallel to the axes of said rotors and in contact with the peripheries of said rotors for at least a portion of theirA circumferences, said rib being provided with lateral passages leading into said pockets whereby the conducted fluid impacts in said pockets and against said tooth blades substantially in the direction of rotation of said rotors. f e

7. In a rotary engine the combination of two or more inter-meshing and engaging rotors, shafts secured in said rotorsand rotatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the axis thereoftoward one end of said rotors and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right hand and left hand spirally disposed tooth blades of one rotor meshing respectively with said left hand and right hand spit-ally disposed tooth blades of another rotor, wherebv buckets are formed between `the meshing tooth blades of said rotors, and

a rib extending substantiallyv parallel to the axes of said rotors and in contact with the peripheries of said rotors for at least. a portion of their circumferences, said rib being provided with a port for conducting fluid under pressure to said buckets of said rotors.

S. ln a rotary engine tl'ielcombination of two or more intermeshing and engaging rotors, shafts mounted in said rotors and rotatably mounted in suitable bearings, each l.

rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the laxis thereof toward one end o said rotors and a plurality of left hand spiralljT disposed tooth blades extending from said plurality of. circumferential points toward' tooth blades substantially in the direction of rotation of said rotors. l

9. ln a rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets, a rib extending substantiall y parallel to the axes of said rotors and in contact with the peripheries ofsaid rotors l y for at least a portion of theirfcircumferences, and one or more inlet ports located in said rib and opening into said. intermeshing tooth blades substantially at the-,junction of said right and left hand spirally disposed tooth blades. l

10. ln a rotary engine the combination of two or more intermeshing and engaging rotorsv` shafts mounted in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand spirally disposed toot-h blades extending from a plurality of circumferential points on said rotors located in a plane. at right angles to the axis thereof toward one end of said rotors and a plurality of lett hand spirally disposed tooth blades extending from said plurality of circumferential points toward the. opposite end of said rotors, said rightl disposed tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of said rotors, a rib extending substantially pa 'allel to the axes of said rotors and in contact with the peripheries of said rotors for at least a portion ot` their cireumferences, and one or more inlet ports located in said rib and opening into said .buckets at substantially tbe junction of said right and left hand spirally disposed tooth blades.

ll. In a rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of right hand spi rally disposed tooth blades extending from a plurality of circumferential points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors and a plurality of left hand spirally disposed tooth blades extendingt'rom said plurality of circumferential points toward the opposite end of said rotors, said right and left hand tooth blades of each rotor meeting and joining and thereby forming angular pockets, a rib extending substantially parallel to the axes of said rotors and iu contact with the peripheries of said rotors t'or at least a portion of their circumferelues, and one or more inlet ports located in said rib and opening into said intermeshing tooth blades at substantially the junction ot' said right and left hand spirally disposed tooth blades, said ports being so arranged that the admission of the fluid under pres` sure into any pair of intermeshing tooth blades is cut ott by the succeeding intermesliing tooth blades before the said first mentioned tooth blades have developed their full capacity.

12. In a rotary engine the combination ot' two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality ot' right hand spirally disposed` tooth blades extending from a plurality oit' circumferential points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors and a plurality of lett hand spirally disposed tooth blades extending from said plurality ot circumferential points to the opposite end of said rotors, said right and left hand tooth blades ot each rotor meeting and joining and thereby forming angular pockets, a rib extending substantially parallel to the axes of said rotors and in contact with the peripheries ot' said rotors for at least a portion of their circumferences, and one or more inlet ports located in said rib and openi'ng into said intermeshing tooth blades `at substantially the junction of said right and left hand spirally disposed tooth blades, said ports being so arranged 1n said rib that a curve drawn parallel to said right or left hand tooth blades and tangent to the curve in which that port orifice which is the greatest distance from the formation of said pockets eut said rib, shall be shorter than the full length ot either said right or said left hand tooth blades of each of said rotors, whereby the admission of the fluid under pressure into any pair of intermeshing tooth blades is cut. ott' by the succeeding intermeshing tooth blades before the said tirst mentioned tooth blades have developed their tull capacity.

13. In a rotary engine the combination of two or more interlneshing and engaging rotors, 'shafts mounted in said rotors and rotatably mounted in suitable bearings, each rotor having a plurality of' right hand spirally disposed tooth blades extending from `a plurality of `circumferential `points on said rotors located in a plane at right angles to the axis thereof toward one end of said rotors and a plurality of left hand spirally disposed tooth blades extending from said plurality of circumferential points toward the opposite end of said rotors, said right hand and left hand spirally disposed tooth blades of one rotor meshing respectively with said lett hand and right hand spirally disposed tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of said rotors, a rib extendingr substantially parallel to the axis of said rotors and in contact with the peripheries of said rotors for at least a portion of their circumferences. and one or more inlet ports located in said rib and opening into said buckets vat substantially the junction of said right and left hand spirally disposed tooth blades, said ports being so arranged that the admission of the fluid under pressure into any bucket is cut off by the tooth blades forming one side of the succeeding bucket bet'ore the said first mentioned bucket has developed its full capacity.

14. In a reversible rotary engine the combination of two or more inter-meshing and engaging rotors, shafts secured in said rotors and. rotatahlymounted in suitable bearings, each rotor having three or more sections, each alternate section on each rotor being provided with a plurality of right hand spirally disposed tooth blades and the other alternate section of the same rotor being provided with a plurality of left hand spirally disposed tooth blades, the said right and left hand tooth blades on each rotor meeting and joining so as to term angular pockets.

15. In a reversible rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having three or more secl tions, each alternate section on each rotor l engagingy rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having three or more sections, each alternate section on each rotor being provided with a plurality of right hand spirally disposed tooth blades and the other alternate section of the same rotor being provided with a plurality of left hand spirally disposed tooth blades, the said right and left hand tooth blades on each rotor meeting and joiningso as to form angular pockets, the right hand and left hand tooth blades on one rotor meshing respectively with the left hand and right hand tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of the said rotors.

17. In a reversible rotary engine the combination of two,y or more intermeshing and engaging rotors, shafts secured in said roi tors and rotatably mounted in suitable bearings, each rotor having three or more sections, each alternate section on each rotor being provided with a plurality of righty hand spirally disposed tooth blades and the other alternate section yof the same rotor being provided with a plurality of left hand spirally disposed tooth blades, the said right and left hand tooth blades on each rotorK meeting and joining so as to form angular pockets, a rib extending across said angular pockets on one side of said rotors and a rib extending across said angular pockets on the opposite sideof said rotors, each of said ribs being substantially parallel to the axes of said rotors and in contact with the peripheries of said rotors for at least a portion of their circumferences.

18. In a reversible rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in, said rotors and rotatably mounted in suitable bearings, each rotor having three or more sections, each alternate section on each rotor beingA provided with a plurality of right hand spirally disposed tooth blades and the other alternate section of the same rotor being provided with a plurality of left hand spirally disposed tooth blades, the rightand left hand tooth blades on one rotor meshing respectively with the left hand and right hand tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of the said rotors, a rib extendrotors and a rib extending across said buckets on the opposite side of said rotors, each of said ribs being substantially parallel to the laxes of said rotors and in contact with thev peripheries of' said rotors for at least a portion of their circumferences.

19. In a reversible rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bears ings, each rotor having three or more sections, each alternate section on each rotor being provided with a plurality of right hand spirally disposed tooth blades and the other alternate section of the same rotor being provided with a plurality of left hand spirally disposed tooth'blades, the said right and left hand tooth blades on each rotor meeting and joining so as to form angular pockets, a rib extending across said angular pockets on one side of said rotors and a rib extending across said angular pockets on the opposite side of said rotors, each of said ribs being substantially parallel to the aXes of said rotors and in contact with the peripheries of said rotors for at least a portion of their circumferences, and one or more inlet ports located in each of said ribs and openings into the intermeshing tooth blades at substantially the junction of each right hand and left hand set of tooth blades where the said angular pockets are formed.

20. .In a reversible rotary engine the combination of two or more intermeshing and engaging rotors, shafts secured in sald rotors and rotatably mounted in suitable bear ings, each rotor having threeor more sections, each alternate section on ea'ch rotor being provided with a plurality of right. Ahand spirally disposed tooth blades and the other.alternate section of the same rotor being provided with a plurality of left hand' spirally disposed tooth blades, the right and left hand tooth blades on one rotor meshing respectively with the left hand and right hand tooth blades of another rotor, whereby buckets are formed between the meshing tooth blades of the said rotors, a rib extending across said buckets on one side of said rotors, a rib extending across said buckets on the opposite side of said rot-ors, each of said ribs being substantially parallel to the' being provided with a plurality of right hand spirally disposed tooth blades and the other alternate section of the same rotor being provided with a plurality of left hand splrally disposed tooth blades, the said right and left hand tooth blades on each rotor meeting and joinin so as to form angular pockets, a rib exten ing across said angular pockets on one side of said rotors and a rib extendin across said angular pockets on the opposite side of said rotors, each of said ribs being substantially parallel to the axes of said rotors and in cont-act with the peripheries of said rotors for at least a portion of their circumferences, and one or more inlet ports located in each of said ribs and openings int'o the interineshing tooth blades at substantially the junction of each right hand and left hand set of tooth blades where the said angular pockets are formed, said ports being so arranged that the admission of the tluid under pressure into any pair of intermeshing tooth blades is cut off by the succeeding informes-hing tooth blades before the said irst mentioned tooth blades have developed their full capacity.

22. In a reversible rotary engine the combinationA of two or more intermeshing and engaging rotors, shafts secured in said rotors and rotatably mounted in suitable bearings, each rotor having three or more sections, each alternate section on each rotor being provided with a pluralit of right hand spirally disposed tooth bla es and the other alternate section of the same rotor being provided with a plurality of left hand spirally disposed tooth blades, the right and left hand tooth blades on one rotor meshing respectively with the left hand and right hand tooth blades of another rotor, whereby buckets are formed between t-he meshing tooth blades of the said rotors, a rib extending across said buckets on one side of said rotors, a rib extendin(lr across said buckets on the opposite side o? said rotors, each of said ribs being substantially parallel to the axes of said rotors and in contact with the peripheries of said rotors for yat least a portion of their eircumferences, and one or more inlet ports located in each of said ribs and opening into said buckets, said ports being so arranged that the admission of the fluid under pressure into any bucket is cut ott by the tooth blades forming one Side of the succeeding bucket before the said first mentioned bucket has developed its full capacity. y

In witness whereof, I have hereunto set my hand in the presence of two witnesses.

JOHN H. VAN DEVENTER.

Witnesses:

JOHN M. CIIIPMAN, J. WM. ELLIS.

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