US2853978A - Improved fluid motor - Google Patents

Description

p 1958 E. D. SMYSER IMPROVED FLUID MOTOR 2 Sheets-Sheet 1 Filed March 5. 1956 QR m Q United States Patent IMPROVED FLUID MOTOR Elmer D. Smyser, Bakersfield, Calif. Application March 5, 1956, Serial No. 569,591 8 Claims. (Cl. 121-95) The present invention relates to fluid motors and more particularly to improvements in the form thereof giving rise to improved accuracy and durability as well as improved accommodation to fluids bearing solid particles, such as sand and gravel.

This application is a continuation-in-part of my prior co-pending applications Serial No. 275,817, filed March 10, 1952, now U. S. Patent No. 2,738,775 granted March 20, 1956 and Serial No. 513,804, filed June 7, 1955 on fluid flow meters of the type here involved. As a brief background to the developments of the subject invention, my meters of this type generally provide a housing having an internal chamber circumscribed by a cylindrical wall and having inlet and outlet ports communicating with the chamber. My prior meters have provided a bridge on the wall inwardly extended into the chamber between the ports, and a rotor having pivotal blades movable inwardly and outwardly and dividing the chamber into fluid-tight compartments when in their outer positions.

During rotation the blades successively ride over the bridge and together with additional means interposed the bridge and the rotor, such as auxiliary blades extended from the bridge into rotor ngagement, preclude fluid which enters the inlet port from passing directly between the rotor and the bridge to the outlet port. The blades successively leave the bridge, pass the inlet port and come into engagement with the chamber wall. Fluid entering the inlet port strikes the blades from behind to impart uni-directional rotation to the rotor.

Under optimum conditions blades leaving the bridge should engage the chamber wall immediately beyond the inlet port in the direction of rotation of the rotor so as to be in the most advantageous position to be driven by fluid entering the inlet port. However, the excessive loads sometimes placed on these meters frequently increases the rotor speed to such an extent that before the blades can be thrust into their outer wall engaging positions, as by springs or the like, they are carried well beyond the inlet port. During this interval, of course, fluid can pass between the blades involved and the wall resulting in an inaccurate measurement of fluid flow.

Further, it has been found in certain instances when the rotors operate at excessive speeds, that blades leaving the bridge are brought against the chamber wall so violently, due to centrifugal force or fluid thrust, as to damage or even break the blades after repeated impacts.

Additionally, in the usual conventional meters, provision has not been made for facilitating movement of blades between inner and outer positions when the chamber is full of oil, water or other fluid. In general, blades of the prior art have been solid members thereby impeding easy movement thereof in fluids.

Accordingly, it is an object of this invention to improve the accuracy, durability and dependability of a fluid motor.

Another object is to provide a fluid motor which will operate efliciently and accurately under excessive loads.

Another object is to provide a fluid motor, having a "ice rotor rotatably mounted in a chamber and providing blades resiliently extended from the rotor into engagement with the walls of the chamber to divided the chamher into fluid volume measuring compartments, in which accurate volume measurement is achieved between the blades even when the rotor is rotated at speeds in excess of normally recommended operating speeds.

Another object is to minimize breakage of blades in rotary fluid motors of the character described.

Another object is to control movement of blades in a rotary fluid motor filled with fluid which blades are adapted for pivotal movement between inner positions on a rotor on which they are mounted and outer positions against a wall of a chamber in which the rotor is mounted.

Another object is to provide a fluid motor which is adapted to pass an exceptionally high percentage of solid matter such as rocks, sand, and the like, without appreciably impairing the functioning thereof.

Another object is to provide a fluid motor having a minimum of drag and frictional resistance so as to impose a very small load on a fluid system in which it is used.

Other objects are to provide a fluid motor which is simple to construct and economical to operate, which is easy to repair, and which is highly effective for accomplishing its intended purposes.

These and other objects will become more fully apparent upon reference to the following description.

In the drawings:

Fig. 1 is a transverse section of a fluid motor constructed in accordance with the principles of the present invention.

Fig. 2 is a fragmentary axial section taken at a position represented by line 2-2 of Fig. 1.

Fig. 3 is a section taken at a position represented by line 33 of Fig. 1.

Fig. 4 is a somewhat enlarged fragmentary section taken at a position represented by 4-4 of Fig. 1.

Fig. 5 is a diagrammatic section similar to that of Fig. 1 and provided to enable a better illustration of the operation of the subject invention.

Referring more particularly to the drawings, the fluid motor of the present invention includes a body member 10 having a housing 11 and a pair of externally threaded outwardly extended fittings l2 and 13. The housing encloses an internal substantially cylindrical chamber 14, and the fittings provide inlet and outlet ports 15 and 16 extended into the chamber, spaced circumferentially of the chamber, and preferably being in substantially coaxial relation eccentrically of the chamber. .lt will be seen that the body member has an inner cylindrical wall 17 circuinscribing the chamber.

The housing 11 has opposite annular end faces 20 providing annular grooves 21. therein. Covers 22, having sheets 23 of resiliently flexible and compressible material internally thereof, are secured by means of bolts 24 to the end faces of the housing in covering relation to the chamber 14 and the annular grooves. O-rings or gaskets 25 are located in the grooves between the covers and the housing to preclude leakage of fluid from the chamber. The wall 17 includes an annular liner 30 of sheet metal having a sheet 31 of resiliently flexible and compressible material vulcanized or otherwise secured to the inner face thereof and circumscribing the chamber. This liner provides openings 32 and 33 in registration with the inlet and outlet ports 15 and 16, respectively. The wall in-- cluding the liner is generally referred to hereinafter as simply the wall.

An inwardly bulged member or bridge 38 is mounted on the wall 17 preferably integrally with the liner 30, and is extended longitudinally of the chamber 14 The bridge provides a main portion 39 extended circumferentially of the chamber between the inlet and outlet ports and 16 and a ramp portion extended in overlying relation to the inlet port. It will be noted that the ramp portion has a fluid passage 41 in registration with the inlet port to enable fiow from the inlet port into the chamber. The main portion of the bridge is tapered to a longitudinal edge 42 terminating adjacent to the outlet port at an edge thereof. The ramp portion is tapered circumferentially of the chamber beyond the inlet port to a longitudinal edge 43 considerably past the inlet port. Both the main portion and the ramp portion of the bridge join the wall 17 along smooth curves, this being especially true of the ramp portion. The bridge also has a sheet 44 of resiliently flexible and compressible material bonded to its internally disposed surface so as to provide an inner surface which is eccentric to the longitudinal axis of the chamber. It is to be noted that the inner surface of the bridge is in gradually decreased spaced relation to the longitudinal axis of the chamber from the edges 42 and 43 to a central portion of the bridge.

A bolt 48 is extended through the body 10 and is threadably engaged with the main portion 39 of the bridge 38 for securing it in position within the chamber 14. The main portion of the bridge also has a pair of slots 49 and 50 extended longitudinally, and spaced circumferentially, of the chamber. Auxiliary resiliently flexible blades 51 and 52 are slidably longitudinally extended into the slots 49 and 50, respectively, and outwardly extend into the chamber. The blades are mounted so as to fold outwardly against the bridge in a common direction toward the inlet port 15. An elongated, resilient prefferably thin metallic baffle 55 is also outwardly extended from the main portion of the bridge adjacent to the fluid passage 41 of the ramp portion. The battle and the auxiliary blades extend between the cover sheets 23.

A rotor provides a hub 61 concentrically mounted in the chamber 14 between the covers 22 for rotation in the chamber. The rotor further provides a plurality of Walls 62 having inner segments 63 radially outwardly extended from the hub in substantially equally angular rela tion and outer arcuate segments 64 extended from the inner segments in a common direction circumferentially of the rotor and concentrically of the hub 61.

As best seen in Figs. 1 and 3, the walls 62 provide forward surfaces having sheets 65 of resiliently flexible and compressible material bonded thereto. The walls have end edges 66 and rear longitudinal edges 67, and the sheets have edge portions 68 rearwardly inwardly extended from the end and rear longitudinal edges of the walls, The end edge portions movably engage the covers 22 in fluid-sealing relation. The rotor also has pairs of radially disposed end plates 69 secured to opposite end edges 66 of the walls and to the hub 61. The end plates serve as gusset plates which buttress the walls 62 and maintain them in rigid assembly with the hub.

Elongated pivot rods are extended between corresponding pairs of end plates 69 and mount journal bearings 76 at opposite ends thereof symmetrically of the hub. The pivot rods have U-shaped end portions 77 locked in one of their associated end plates, as shown in Fig. 3. Pairs of mounting arms 78 provide inner end portions 79 having journal collars 80 rotatably mounted on the bearings 76 and outer end portions 8|. The inner end portions extend outwardly from the pivot rods in planes substantially tangentially related to a circle concentric to the hub 61, and the outer end portions are outwardly obtusely extended from the inner end portions. Blades 86 provide rearward surfaces secured, as by welding, to the outer end portions 81 of the mounting arms and forward surfaces. The blades have longitudinal outer edges 87 and opposite end edges 88, and provides prongs 89 extended inwardly toward the hub 61 therefrom. Sheets 90 of resiliently flexible and compressible material are adhered to the forward surfaces of tilt; blades and have edge portions 91 and 92 rearwardly angularly extended from the lonigtudinal and end edges of the blades. The end edge portions engage the cover sheets 22 in fluid-sealing relation and the longitudinal edge portions are adapted for fluid-sealing engagement with the liner 30 of the chamber wall 17.

Springs 96 each provide pairs of coils 97 wrapped around the central portions of the pivot rods 75, intermediate U-shaped hooks 98 received on prongs 89 of the adjacent blades 86, and legs 99 radially inwardly extended and secured, as by welding, to the adjacent inner segments 63 of the walls 62. In this manner the springs urge the blades outwardly into engagement with the liner 30 of the wall 17 and with the bridge 38.

It is to be noted that the wall 17 from the edge 43 of the bridge 38 to the outlet port 16 in the direction of rotation of the rotor 60 is concentric to the axis of rotation of the rotor whereas the inner surface of the bridge, as stated, is eccentric to such axis and much more closely spaced to the hub.

Operation The operation of the described embodiment of the present invention is believed to be readily apparent and is briefly summarized at this point. The motor is connected in a fluid system so that fluid enters the inlet port 15 and leaves the meter through the outlet port 16. Fluid flowing through the inlet port enters the chamber 14 through the fluid passage 41 in the bridge 38 and strikes the blades 86 to impart rotation to the rotor 60 in a predetermined direction, this being clockwise as seen in Fig. 1.

It is to be noted that the springs 96 urge the blades 86 into positions outwardly extended into fluid-sealing engagement with the wall 17 and the bridge member 38 depending on the position of the blades. In their fully extended positions the blades engage the rearward edges 68 of the rotor walls 62 in fluid-sealing relation. The blades together with the rotor walls, the covers, the bridge, and the wall of the body member form compartments wherein the fluid is trapped for travel from the inlet to the outlet ports.

As a blade 86 travels, in a clockwise direction as viewed in Fig. 1, from the outlet port 16 to the inlet port 15 it passes over the bridge 38. In so doing, its spring 96 urges it against the bridge in sealing relation therewith. In addition, the auxiliary blades 51 and 52 extend outwardly into engagement with the outer wall segments 64 further to preclude passage of fluid directly from the inlet port between the rotor and the bridge to the outlet port. This insures that all of the fluid travels in a clockwise direction from the inlet port to the outlet port to enable accurate measuring. Additionally, the battle 55 deflects fluid coming from the inlet port in a general clockwise direction and thus acts as a barrier to its passage along the bridge. In so doing, however, it performs the even more significant function of deflecting sand, gravel and the like carried by the lluid in the desired direction of travel.

As the blade 86 leaves the auxiliary blade 52, its spring 96 continuously urges it outwardly into engagement with the ramp portion 39 of the bridge 38. As the rotor 60 continues its rotation, such blade rides along the ramp portion toward the edge 43 thereof until it again engages the wall 17 of the chamber 14. In this way passage of fluid from the inlet port between a blade and the wall of the chamber is prevented and all of the fluid entering the chamber from the inlet port is forced to enter substantially fluid-tight chambers defined by the blades. This prevents fluid from by-passing the blades, enables uniform rotational movement of the rotor, and thereby renders the meter more dependable and accurate in op eration. Inasmuch as the transition from the bridge to the wall 17 is gradual rather than abrupt, the blades do not strike the wall sharply and thus are not broken or damaged by repeated impacts with the chamber wall.

When the motor is in use, the chamber 14 is normally filled with fluid such as oil. With some prior blade constructions it has been ditficult for the blades to move with ease between inner and outer positions, especially through the more viscous fluids. Since the blades 86 are mounted on spaced arms 78, such movements of the blades of the present invention are facilitated. This is best seen by reference to Fig. 5. Thus, as a blade moves toward its outer position as it descends the ramp portion 40, excess fluid in front of the blade is permitted to pass between the mounting arms as indicated by arrow 110, to the rear of the blade. In this way excess fluid is not trapped in the compartment forwardly of the blade which fluid, if trapped as in prior meters, tends to preclude or resist full movement of the blades into their chamber defining positions and as a result compartment leakage ensues. In the structure shown, free and precise movement of the blades to and from compartment defining positions is achieved. The mounting arms thus constitute mounting means providing passageways therein for passage of fluid therethrough during the described movement of the blades.

A somewhat similar problem is obviated as a blade 86 rides onto the bridge 38 after passing the outlet port 16. It is easily seen from Fig. 5 that there is a tendency for fluid to become trapped between the blade, the bridge 38, and the respective outer wall segment 64. However, such trapping is precluded by releasing fluid in front of the blade rearwardly through the associated mounting arms, as indicated by arrow 112. In this way, fluid which has been measured by compartments defined by the blades effectively exhausts from the outlet 16. Of course, there is normally residual fluid in the compartments as the bridge is traversed. If trapped, such residual fluid either precludes or at least impedes rotor rotation. The free release of such fluid, as indicated by arrow 112, obviates any appreciable impeding of rotor rotation by such residual fluid.

While no counter is shown in the drawings, it will be understood that any suitable such device may be utilized in driven connection to the shaft 61 and properly calibrated to read in any desired standard of volumetric or fluid velocity.

It will be evident from the foregoing that several significant improvements in fluid motors have been provided. Because of the described construction of the bridge 38, there is less breakage of blades, and results show that the accuracy of measurement of the motor is improved. The bridge member enables the motor to be operated under excessive loads and resultant high speeds without loss of accuracy, durability, or dependability. It has been found that a motor constructed in this manner can carry as high as forty percent of solid matter, such as sand, rocks, and the like, without appreciable impairment of its measuring function. The motor has im proved sealing characteristics, has a minimum of Erictional drag, and imposes a relatively low pressure load on any fluid system in which it is incorporated. Clearly, therefore, the motor of the present invention is highly effective in carrying out its intended functions.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of. the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a fluid motor, a body member providing a charm her and spaced inlet and outlet ports communicating with the chamber, a rotor mounted for rotation in a prede- (ill termined direction in the chamber about an axis of rotation and having a plurality of walls providing inner radially outwardly extended portions and arcuate outer portions concentric to the axis of rotation of the rotor and extended from their respective inner portions in a common direction circumferentially of the chamber opposite to the direction of rotation of the rotor, mounting means pivotally mounted on the walls of the rotor defining fluid passageways therein, and elongated blades secured to the mounting means for movement therewith between positions outwardly extended in engagement with the body member and their respective forwardly adjacent outer rotor wall portions and inner retracted positions, the passageways defined by the mounting means being adapted to permit passage of fluid therethrough during movement of the blades between said outwardly extended and retracted positions.

2. In a fluid motor, a body member providing a chamher and spaced inlet and outlet ports communicating with the chamber, a rotor mounted for rotation in a predetermined direction in the chamber about an axis of rotation and having a plurality of walls providing inner radially outwardly extended portions and arcuate outer portions concentric to the axis of rotation of the rotor and extended from their respective inner portions in a common direction circumferentially of the chamber opposite to the direction of rotation of the rotor, elongated mounting arms pivotally mounted in longitudinally spaced relation on the walls of the rotor defining fluid passageways therebetween and having inner end portions tangentially related to circles concentric to'the rotor axis and outer end portions angularly outwardly extended from their respective inner end portions, blades secured to the outer end portions of the mounting arms for movement therewith between positions outwardly extended in engagement with the body member and their respective forwardly adjacent outer rotor wall portions and inner retracted positions, and spring means interposed the walls of the rotor and the mounting arms for yieldably urging the mounting arms and their associated blades into their outer positions the passageways defined by the mounting means being adapted to permit passage of fluid therethrough during movement of the blades between said outwardly extended and retracted positions.

3. 111 a fluid motor, a body member providing a chamber and spaced inlet and outlet ports communicating with the chamber, an inwardly bulged bridge mounted in the chamber of the body member between the inlet and outlet ports, a rotor mounted for rotation in a predetermined direction in the chamber about an axis of rotation and having a plurality of walls providing inner radially outwardly extended portions and arcuate outer portions concentric to the axis of rotation of the rotor and extended from their respective inner portions in a common direction circumferentially of the chamber opposite to the direction of rotation of the rotor, and spaced inwardly from the bridge, elongated angulated mounting arms pivotally mounted in longitudinally spaced relation on the walls of the rotor having inner end portions tangentially related to a circle concentric to the rotor axis and outer end portions angularly outwardly extended from their respective inner end portions toward the outer portions oi their respectively adjacent rotor walls, blades secured to the outer end portions of the mounting arms having resiliently flexible sealing edges and being movable with the arms between positions outwardly extended in fluid-scaling engagement with the body member and their respective forwardly adjacent outer rotor wall portion and inner retracted positions, and spring means interposed the walls ol. the rotor and the mounting arms for yieldnbly urging the mounting arms and their associated blades into their outer positions.

4. A llnid motor comprising a body member having an internal chamber defined by a substantially cylindrical inner wall, and aligned inlet and outlet ports spaced circumfereutially of the chamber; a rotor concentrically mounted in the chamber; a rotor concentrically mounted in the chamber for rotation in a predetermined direction having a plurality of substantially equally spaced radially extended inner wall segments, and a plurality of fraetocylindrical outer wall segments concentric to the rotor axis and extended in a common direction opposite to the direction of rotation of the rotor circumfercntially of the chamber from the radially extended wall segments, the outer wall segments having rearward longitudinal edges spaced from their respective rearwardly adjacent wall segments and the wall segments being in endward fluidsealing engagement with the body member; an inwardly bulged member mounted on the wall in overlying relation to the inlet port extended radially into and longitudinally of the chamber having a central portion providing a fluid passage in communication with the inlet port, and opposite longitudinal edges joining the wall on opposite sides of the inlet port, the bulged member further having an inwardly disposed surface gradually convergently tapered from the central portion to the longitudinal edges so that the bulged member joins the wall along substantially smooth curves; a plurality of elongated mounting arms having inner end portions pivotally connected to the rotor wall segments and extended along planes substantially tangential to circles concentric to the rotor axis and outer end portions outwardly angularly extended from the inner end portions for movement inwardly and outwardly of the rotor; blades secured to the outer end portions of the mounting arms for fluid-sealing engage ment with the inner wall of the body member and the bulged member with the rearward edges of their respectively adjacent outer wall segments when the mounting arms are outwardly extended; and a plurality of springs mounted on the rotor walls engaging the rotor and the mounting arms for urging the arms into their outwardly extended positions.

5. in a fluid motor, the combination of a body member having opposite ends, an internal chamber circumscribed by an inner substantially cylindrical wall, and circumfercntially spaced inlet and outlet ports in communication with the chamber; a bridge secured to the body member and longitudinally extended in the chamber having a main portion intermediate the ports tapered to a longi tudinal edge adjacent to the outlet port, and a ramp portion integrally extended from the main portion in overlying relation to the inlet port tapered to a longitudinal edge meeting with the inner wall of the body along a smooth curve, the ramp portion having a fluid passage therein in registration with the inlet port to permit the passage of fluid from the inlet port into the chamber; a rotor concentrically mounted in the chamber for rotation in a predetermined direction about an axis longitudinally of the chamber including a hub, a plurality of walls having inner segments radially outwardly extended from the hub in substantially equally angular relation and outer arcuatc segments extended from the inner segments in a common direction circumferentially of the chamber terminating in rearward longitudinal edges, the rotor walls having forward and rearward surfaces and opposite end edges, and the rotor further having radially disposed end plates secured to the opposite end edges of the walls of the rotor, the rotor having sheets of resiliently flexible material adhered to the forward surfaces of the rotor walls providing edge portions etlgcwardly extended rearwardly from the rearwardly longitudinal edges or their respective walls and endwardly extended in lluidtight engagement with the opposite ends of the body member; pivot rods longitudinally extended between the end plates in substantially parallel relation to the hub of the rotor; arms having inner portions journalled in longitudinally spaced relation on the pivot rods and extended therefrom along planes tangentially related to a common circle concentric to the hub and outer portions outwardly aurearward surfaces secured to the outer portions of the arms, forward surfaces, and end and longitudinal edges, the blades having sheets of resiliently flexible material adhered to their forward surfaces including edge portions rearwardly edgewardly extended from the end and longitudinal edges of the blades in angular relation to the blades; springs having intermediate coiled portions around the pivot rods, end portions in engagement with the inner segments of their respectively adjacent rotor walls and outer end portions engaging the blades on the mounting arms connected to their associated pivot rods for yieldably urging the blades outwardly of the hub to bring the sheets of resiliently flexible material on the blades against the rearward longitudinal edge portions of the associated rotor walls and to bring the longitudinal edge portions of the sheets on the blades into engagement with the wall of the body member and the bridge to divide the chamber into compartments and a pair of resiliently flexible auxiliary blades mounted in the bridge between the inlet and outlet ports extended into the chamber into rotor engagement, said auxiliary blades being foldable outwardly toward the bridge in the direction of rotation of the rotor and being spaced a distance circumferentially of the chamber approximating but greater than the distance between the rearward edges of the rotor walls and their respective rearwardly adjacent rotor walls.

6. In a tluidmotor, a body member providing a chamber and spaced inlet and outlet ports communicating with the chamber, an elongated rotor mounted for rotation in a predetermined direction in the chamber about a longi tudinal axis of rotation and having longitudinally ex tended angular walls providing inner portions outwardly extended from said axis and outer portions angularly extended from the inner portions in a common direction circumferentially of the chamber opposite to the direction of rotation of the rotor, mounting means pivotally mounted on the walls of the rotor providing fluid passageways therein, and elongated blades secured to the mounting means for movement therewith between positions outwardly extended in engagement with the body member and their respective forwardly adjacent outer rotor wall portions and inner retracted positions, the passageways defined by the mounting means being adapted to permit passage of fluid therethrough during movement of the blades between said outwardly extended and retracted positions.

7. in a fluid motor, a body member providing a chamher and spaced inlet and outlet ports communicating with the chamber, an elongated rotor mounted for rotation in a predetermined direction in the chamber about a longitudinal axis of rotation and having longitudinally extended walls providing inner portions outwardly extended from said axis and outer portions extended from their respective inner portions in a common direction circumlerentially of the chamber opposite to the direction of rotation of the rotor and defining a plurality of fluid entrapping concavities, mounting means pivotally mounted on the walls of the rotor within said concavities providing iluid passageways therein, and elongated blades secured to the mounting means For movement therewith between positions outwardly extended in engagement with the body member and their respective forwardly adjacent outer rotor wall portions and inner retracted positions, the passageways defined by the mounting means being tuaptcd to permit passage of fluid therethrough during movement ol the blades between said outwardly extended and retracted positions.

ls, in a fluid motor, a body member providing a chamher and spaced inlet and outlet ports communicating with the chamber. a rotor mounted for rotation in a predetcrmiucd direction in the chamber about an axis of rotation and having a plurality of walls providing inner radially outwardly extended portions and arcuate outer portions concentric to the axis of rotation of the rotor and ex gularly extended from the inner portions; blades having tended from their respective inner portions in a common direction circumferentially of the chamber opposite to the direction of rotation of the rotor, circumferentially adjacent walls of the rotor forming compartments therebetween, mounting means pivotally mounted on the walls of the rotor defining fiuid passageways therein, and elongated blades secured to the mounting means for movement therewith between positions outwardly extended in engagement with the body member and their respective forwardly adjacent outer rotor wall portions and inner retracted positions, each of the blades having a rear surface disposed rearwardly thereof with respect to the direction of rotation of the rotor, said rear surface of each blade being spaced circumferentially of the rotor from its respective rearwardly adjacent rotor wall in said outwardly extended positions for permitting passage of fluid from 10 the chamber between each blade and its respective rearwardly adjacent rotor wall into the compartment associated therewith, the passageways defined by the mounting means being adapted to permit passage of fluid therethrough during movement of the blades between said outwardly extended and retracted positions.

References Cited in the file of this patent UNITED S'IATES PATENTS 399,952 Ward Mar. 19, 1889 7l9,222 Huyck June 27, 1903 756,366 Hoffman Apr. 5, 1904 783,291 Leach Feb. 21, 1905 942,205 Johnson Dec. 7, 1909 1,097,756 Heister May 26, l9l4

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