US3280755A - Ring gear type pump - Google Patents

Description

RING GEAR TYPE PUMP Filed May 4, 1964 4 I 1eetsSheet 1 1966 L. Ross 3,280,755

RING GEAR TYPE PUMP Filed May 4, 1964 4 Sheets-Sheet 2 Oct. 25, 1966 ROSS RING GEAR TYPE PUMP 4 Sheets-Sheet 5 Filed May 4, 1964 L. ROSS RING GEAR TYPE PUMP Oct. 25, 1966 Filed May 4, 1964 4 Sheets-Sheet 4 [011156 F055 w WMMu/v wig United States Patent 3,280,755 RING GEAR TYPE PUMP Louis Ross, Rockford, Ill., assignor to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Filed May 4, 1964, Ser. No. 364,487 Claims. (Cl. 103126) This invention relates to rotary devices particularly of the gear-within-a-gear type in which nested complementary rotatable elements provide a plurality of fluid components of continuously varying dimensions.

Rotary gear pumps of the above type, now known in the art, have gear teeth of one rotor directly conjugate and meshing with the internal teeth of a ring gear disposed about the driving rotor. By proper choice of the number and dimension of the teeth-defined compartments, the total capacity of the pump can be increased over comparable type of pumps; this is based fundamentally on the relative rotation occurring between the inner and outer rotors as a result of having teeth of the inner rotor one less in number than corresponding teeth of the outer rotor. The differential series of interengaging teeth provide a constant but slow gain in revolutions of the inner rotor over the outer rotor. The sealed compartments expand and contract; by introducing fluid such as air or liquid at a point where the compartments have their greatest volume, the fluid can be exhausted in the subsequent contraction phase to provide a pressure head.

Despite the basic advantage of the such pumps, greater compactness and increased capacity is needed for more universal applications. Also, there is a definite limitation placed upon their use in view of present manufacturing costs; such costs are relatively expensive reflecting expensive broaching and machining processes required in producing an accurate fit between the rotors.

A primary object of this invention, therefore, is to provide a rotary gear pump of the ring gear type having increased pump displacement for a given mass of structure and to increase pump displacement for a given pump size and silhouette. A- structural feature pursuant to this object is the employment of a plurality of equi-spaced rollers in contact with and disposed between complementary convolutions of the inner and outer pump rotors which contribute to significant increase in the maximum volume of said compartments.

Another object of this invention is to provide a rotary .pump of the above type having a greater economy of manufacture and a more durable construction which is less susceptible to leakage than pumps of this type now known in the art. A particular feature pursuant to this object is the employment of hollow rollers having a degree of resiliency effective to accommodate mis-alignment between the pump rotors.

Still another object of this invention is to provide a rotary pump of the above type which has a longer maintenance-free life resulting from the rolling action of a plurality of rollers disposed between the rotors, the rollers being of such construction to reduce spinning inertia requiring less acceleration and deceleration in cycling and thereby reduce wear while permitting higher r.p.m. of the pumping elements.

Other objects and advantages of this invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a central sectional view of a ring gear type pump employing the principles of this invention;

FIGURE 2 is an end view of the embodiment of FIG- URE 1 taken substantially along line 22 thereof;

FIGURE 3 is a sectional view through one cover plate and taken substantially along line 3-3 of FIGURE 1.

3,280,755 Patented Oct. 25, 1966 FIGURE 4 is a sectional view through the other cover plate :and taken substantially along line 44 of FIG- URE 1;

FIGURE 5 is a sectional view taken substantially along line 55 of FIGURE 1;

FIGURE 6 is an elevational view of one phasing ring; and

FIGURE 7 is a schematic illustration depicting critical geometry of the centers of circles inscribing the rotor convolutions and rollers of the embodiment of FIGURE 1.

Referring to the drawings and more particularly to FIGURES 1-6, a preferred embodiment of the invention is shown. Broadly, the pump comprises a stationary housing 10 defined by a central cylindrical body A having cover plates B-1 and B-2 disposed on opposite sides thereof in a manner to define a circular cylindrical chamber 11 within which pumping elements :are disposed. A rotatable driving shaft D extends into the housing 10 and has one end journaled therein by a bearing assembly 12. The pumping elements comprise: annular rotors E, F disposed eccentrically having one within the other; spacing rings G, H disposed on opposite sides of the annular rotors E, F and fit snugly within chamber 11; and a plurality of cylindrical rollers I are journaled in said phasing rings in an equi-circumferential manner and are adapted to maintain contact with both said rotors during operation.

Turning now more particularly to the components of the pump, the cylindrical body A is circular in configuration and has covers B-1 and B-2 placed against the sides 13, 14 thereof respectively. The covers are joined to the body A by pins extending through aligned openings 16 provided in covers B-1, B-2 and body A. Cover B-2 is a circular cylinder :and is provided with a fluid inlet means 17 comprising a passage 18 communicating the outer periphery of the pump with an arcuate groove 19 opening to one side of the cover B-2 so as to be in general alignment with the spaces defined between the rotors at the instant where the groove communicates. Cover B-2 also has an annular recess 23 in the outer side thereof adapted to receive and journal the outer race 12a of the bearing assembly 12.

Cover B-1 similarly has a circular cylindrical configuration within which is defined in part fluid outlet means 20 comprising passage 21 communicating the outer periphery of the pump with an arcuate groove 22 opening to one side of the cover B-1 and is generally arranged in alignment with the spaces defined between the rotors and which are most adjacent the groove. The outer terminal portions of passages 21 and 18 may be provided with suitable threading to positively receive fluid conduits.

Each of the grooves 22, 19 of the opposed covers B-l, B2 are arranged to communicate with a different circumferential half of the chamber 11 (see FIGURES 3 and 4). Each of the covers B-1 and B-2 have aligned central openings 24 and 25 respectively through which extends the driving shaft D. The driving shaft has one end journaled in the inner race 12b of the bearing assembly 12, the bearing assembly being fixed axially upon the shaft D by snap rings 30 and 31. End plate 32 is secured by cap screws to cover B-2cooper-ating to entrain the bearing assembly 12.

Rotor E has a circular inner periphery 35 fitted about the outer surface of the shaft D and is keyed thereto for rotation through a radially directed key 36 extending into each of the rotor and the shaft. The outer periphery of the driving rotor E has a continuous series of uniform convolutions 37 (uniform being used in the sense both radially and circumferentially with respect to the axis of rotation of shaft D). The convolutions 37 here specifically have (14) ridges 38 and (14) valleys 39, the ridges and valleys being generally the complement of the other in 3 silhouette and configuration. A circle 40 inscribing the extremities or tips of the ridges 38 of said convolutions 37 will have a center C-l lying on the axis ofrotation of shaft D.

' The running rotor F has a circular cylindrical configuration of larger diameter than said driving rotor and has an outer periphery 41 fitting snugly within inner periphery 42 of the body A. The inner periphery of the running rotor is provided with a continuous series of convolutions 43 which are uniform and opposite in configuration and shape of the convolutions 37 of the driving rotor. Rotor F has (16) ridges 44 and (16) valleys 45. A circle 46 ci-rcumscribing the extremities or ridges of the convolutions 43 is close to being tangent to the circle 40 and has a center C-2 offset from center C-1 and increment K.

A plurality of rollers I are disposed between and in rolling contact with both said continuous series of convolutions 37 and 43 provided respectively on said driving and running rotors. The rollers are maintained at equicircumferentially spaced positions (circumferential being taken with respect to their annular arrangement about the rotor convolutions) positioned by phasing rings G,H. Each phasing ring is formed from a relatively thin plate and is disposed between a pump cover and one side of the rotor (see FIGURE 1); the rings are spaced on opposite sides of the rotors and each have defined therein a plurality of circular roller openings 50 effective to journal the ends of the rollers I; the rollers and rings together con stituting a roller set L, the openings on opposite rings being in alignment so as to permit each roller I to turn about its own axis 51 while entrained by the opening walls 50a.

A circle 52 incribing the projection of each of the roller axes has a center C-3 offset from each of the centers C-1 and -2. The eccentricity of the offset of each of said centers C-1, C-2 and C-3 will be more fully discussed below. A plurality of ports 54 smaller in diameter than the roller openings 50, are also provided in each of the phasing rings and are arranged with one port each disposed between said openings 50; the centers of said ports 54 lie on a circle common with the circle 52 inscribing the rotor axis. The phasing rings G and H have annular peripheries 55 entrained by the housing body A in a manner to rotate about center 0-3.

The rollers I each have thin walls 56 defining a hollow cylindrical configuration; the thin walled construction providing a degree of resiliency (the rollers preferably being of steel composition typical of roller bearings now known in the art) to accommodate mis-alignment between rotors and to reduce the spinning inertia of the entire roller set L. The flexibility of the thin-wall rollers obviates much of the difficulty of manufacture of previous pump rotors in that tolerances and expensive broaching operations may be alleviated. Thus, as predetermined tolerances or spacing between the rotor convolutions are exceeded, the variance will be accommodated by the rollers to insure a constant tight fluid seal between the rotor convolutions and rollers. Since the roller set L undergoes constant acceleration and deceleration during operation, the inherent light mass of hollow rollers contributes to a lower spinning inertia thereby also permitting the pump to be designed for higher rotor revolutions per minute in a given size.

An important geometrical property herein is the definition of a plurality of variable volume chambers 59, which, through their expansion and contraction, provide the basic pumping effect. The variance in the volume of these chambers is not only due to the changing relation between rotor convolutions, but also to the changing relation of the rollers with respect to the varying rotors. The sides of all said chambers 59 are defined in common planes as determined by the phasing rings G and H; the sides of said chambers do not vary. The cooperation of the double series of convolutions and rollers provide a more enhanced degree of expansion and contraction than known in the ceived the outer surface A41 of the outer rotor F. The

prior art within a given size pump and with an equivalent mass of pump structure. Generally, the offset 'K between the centers C-1 and C-2 will largely be determined by the choice of roller diameter (here for the purposes of illustration the roller diameters of the preferred embodiment were chosen as .398" and from this value the offset K was calculated).

In order to provide for pumping action, one rotor must advance relative to the other and the roller set L must advance relative to each of the rotors; such advancement is achieved by a dissimilar number of ridges on one rotor with respect to the other and a dissimilar number of rollers with respect to each number of rotor ridges. Here the driving rotor is chosen with 14 ridges, the roller set with 1.5 rollers and the running rotor with 16 ridges. Thus, for each revolution of the rotor F, the rollers of set L will advance one ridge, and the ridges of the driving rotor will advance one roller with respect to the roller set.

Angular speeds of the rotors and roller set L can be determined by the following mathematics:

Part Angular Speed Driving rotor.-. W

Roller set %W Running rotori W W=angular speed of shaft D.

N=number of rollers. When C-1 and (3-2 are both determined by the location of their corresponding bearings, C-3 is then constrained to a fixed position in space even though no bearing is provided with C-3 as center. This follows from the fact that the distance from C-1 to C-3 and the distance from 0-2 to 0-3 are constants associated with the rotor convolutions.

Circles 40 and 46 are substantially tangent but can not in practice have perfect tangency. Perfect tangency would cause interference between the ridges of the complementary series of convolutions. A slight spacing is required even at the point where they would seemingly come to a perfect tangency; such degree of non-tangency is defined to be included in the term substantially tangent which shall be used hereafter.

The invention herein encompasses employment of the principles in variable displacement pumps running at constant speeds as well as fixed displacement pumps as illustrated in FIGURES 1-6. In FIGURE 8 a variable displacement pump 69 (similar parts of the embodiment of FIGURE 8 to those of the preferred embodiment in FIGURES 1-6 have similar part numbers prefixed by A) has an outer annular rotor bearing A72 provided with an inner surface A42 against which is snugly rebearing A72 has an annular outer surface A75 of smaller diameter than generally annular surface A73 of the body A within which it is nested. The axis of rotation of the outer rotor F and the coincident center of the rotor bearing A72 are both designated as C-2 and are determined by the lineal positioning of the rotor bearing within the larger interior cylindrical wall A73 of the body A. Axis C-2 is shifted up or down (as viewed in FIGURE 8) by a control rod A extending through a guide opening A77 in body A and has a radially inner end A74 in contact with the outer surface A75 of the'rotor bearing A72; although the means herein comprises a rod for shifting axis C 2 along the direction of movement of the rod, other means may be employed to shift the spacing between rotors which may also include slight angular adjustment as well as lineal adjustment. 1

Assuming the axis 0-2 to lie coincident with Center 0-1 the outer rotor F will be concentrically disposed about the inner rotor E. In such centered condition, turning of the inner rotor B will not produce a pumping action because the spaces 59 between the inner and outer rotors will remain constant in volume. However, as the control rod A70 is moved downwardly (as viewed in FIGURE 8) the displacement capacity of the pump will be increased; maximum downward movement of the rotor to the point where it bottoms on the body A as shown in FIGURE 8 represents the condition of maximum displacement and spaces 59 will undergo the largest change in volume during operation. Accordingly, locating the rotor bearing A72 at an intermediate position of lineal adjustment will produce an intermediate flow and thereby pump displacement can be adjusted from zero to a maximum rated value. Flat surfaces or lands A76 on the body A are provided to accommodate the lineal adjustment of bearing A72 while affording support thereto to withstand loads induced by pressure on the outer rotor F.

In any position the rotor bearing affording less than maximum displacement, the axis C3 will have two possible locations -3:: and C-3b as determined by intersecting arcs each having a radius M (approximately equal to one-fourth the roller diameter-see FIGURE 7). In such instances, the offset K between axes C-1 and C-2 will be less than one-half the general roller diameter. These geometrical relationships follow from the necessity of maintaining the roller set L conjugate with both rotors E and F. When the variable displacement pump is assembled, the roller set L will have its axis (3-3 take on one of said two possible locations and will be stable in such a position thereafter. The roller set L must maintain tangency with the convolutions of both of said rotors and must shift angularly as the spacing between the convolutions varies from that shown in full outline in FIG- URE 8 to that shown in broken outline in FIGURE 8.

It is further comprehended within this invention that the use of a roller set between rotors conjugately meshing with the rollers can be utilized in gear arrangements, such as planetary gear constructions to provide a greater degree of mechanical advantage than that formerly achieved by intermeshing gear teeth. The construction and arrangement of the various axes of rotation of the elements would be determined according to the principle disclosed herein for the pump embodiments.

For exemplary purposes, the displacement of the pump illustrated in FIGURE 1 can be determined by the following mathematical calculations:

DPR=21rEW (D DPR displacement per revolution in cubic inches. E =distance between rotor centers in inches. W =width of rotors in inches.

D =diameter of circle inscribing axes of roller set L.

d =radius of roller. N :number of rollers.

The above second equation permits the entire design of the pump to be derived primarily from a choice of roller diameter. E in Equation 1 has been replaced by d 2 and D has been replaced by In the second equation, nominal allowance for ridge interference can be made by approximating slight changes in d,..

:20 as shown in small arrows in FIGURE 3.

In operation, dirve shaft D turns the rotor E which in turn urges the meshing roller set L and running rotor F to turn in proper relationship. Fluid is drawn by suction into the inlet means 17 and is admitted to those spaces or compartments 59 which are expanding so that the maximum variable volume of the spaces will be filled with fluid. Notice that a considerable increase in volume takes place in counterclockwise movement from the position where the spaces at the upper adjacent position by axis Y-Y (see FIGURE 5 to lowermost adjacent position by axis Y-Y. The chamber or spaces 59 are defined so that the rollers may nest within the valleys of the rotors as shown in the uppermost portion of FIGURE 5. Fluid continues to enter through the ports 54 in the phase ring H as the compartments sweep past in a counter-clockwise direction of FIGURE 5. As the compartments begin to contract in volume, fluid is discharged through the ports 54 in the phasing ring G and forced through the outlet means It is the eccentric relation of the driving rotor with respect to the roller set L and the roller set L with respect to the running rotor (each having one less tooth or roller with respect to the member radially inward thereof); which gives rise to the formation of chambers of continuously varying dimensions and which go through a greater volumetric The long sweep of the grooves 22 and 19 with tributes the intake and discharge impulses in such manner that a uniform, non-pulsating pumping action is achieved.

While -I have described my invention in connection with a specific embodiment hereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of my invention is defined solely by the appended claims which should be construed as broadly as the 'prior art will permit.

I claim:

1. A pump of the ring gear type, comprising: annular driving and running rotors one arranged radially within the other, each rotor having a continuous series of uniform convolutions with one series of convolutions facing the other and defined so that circles inscribin g each series of convolutions are substantially tangent at one point, a

plurality of equi-circumferentially spaced rollers disposed between and in contact with both said series of convolutions and having a circle inscribing the axes of rotation of said rollers substantially tangent to at least one of said former circles, means cooperating with said rotors to define fluid chamber and being effective to journal said rollers, therein, fluid inlet and outlet means effective to introduce and exhaust fluid at circumferentially spaced stations for spaces defined between said rollers and series of convolutions, the radially outermost series of convolutions having two more convolutions than the series of radially innermost convolutions and said rollers being one more in number than said innermost convolutions.

2. A pump as in claim 1 in which said rollers are hollow whereby the rollers are effective to resiliently flex and accommodate imperfections in spacing between said series of convolutions.

3. A pump as in claim 1 in which said chamber defining means includes a pair of phasing rings effective to entrain the sides of said rotors for rotation, each ring having a plurality of openings therein effective to journal the ends of said rollers and each said phasing ring having a plurality of ports between each of said roller openings effective to communicate said inlet or said outlet means with spaces defined between said rollers and convolutions.

4. A pump of the ring gear type, comprising: a stationary housing, a rotatable driving shaft journaled in said housing, an annular driving rotor mounted for rotation upon said shaft and having a series of convolutions on the outer periphery thereof, an annular running rotor disposed eccentrically about said driving rotor and having a series of convolutions on the internal periphery thereof,

said driving rotor having two less convolutions than said running rotor, circles circumscribing the extremities of said convolutions being substantially tangent, a plurality of hollow rollers disposed between said rotor convolutions and effective to maintain contact with both series of convolutions, phasing rings disposed on opposite sides of said rotors and effective to define variable volume spaces in cooperation with said rotors and said rings journaling said rollers, first fluid passage means defined in one of said rings and housing effective to introduce fluid to certain of said spaces disposed at one circumferential half of the housing, and second fluid vpassage means in the other of said rings and housing communicating other of said spaces at the other circumferential half of the housing.

5. A pump of the ring gear type, comprising: annular driving and running rotors one arranged eccentrically within the other, each rotor having a continuous series of uniform convolutions with one series of convolutions facing the other; means effective to support said rotors for rotation; means carrying a plurality of uniform equicircumferentially spaced rollers arranged in a ring and disposed between and in rolling contact with both said series of convolutions, said support means providing an offset between the axes of rotation of each of said rotors which is substantially one-half the diameter of one of said rollers, said rotor convolutions determining a fixed center of rotation for said roller ring which is offset from either of said rotors axes a distance substantially one-fourth the diameter of one roller, each of said axes of rotation of said roller ring and rotors lying on a common diameter; and fluid inlet and outlet means effective to introduce and exhaust fluid at circumferentially spaced stations for spaces defined between said rollers and series of convolutions.

6. A :pump of the ring gear type as in claim 4, in which said hollow rollers are formed with thin resilient walls effective to flex under pressure from imperfections in the spacing between said convolutions, said thin walled rollers a-lso reducing the spinning inertia of said plurality of rollers effective to reduce wear during acceleration and a deceleration of said rollers.

7. A pump of the ring gear type, comprising: annular driving and running rotors one arranged eccentrically within the other, each rotor having a continuous series of uniform convolutions facing one another; a pair of spaced.

apart rings having a plurality of equi-circumferentially spaced circular openings and a plurality of ports interposed between each of said circular openings; a plurality of thin walled hollow cylindrical rollers journaled in each pair of aligned openings of said rings and free to rotate about an axis determined by said openings, said rollers being of a diameter to fit substantially within the contours of said rotor convolutions; means journaling each of said rotors for rotation about axes offset -a distance diameter of one of said rollers, said rollers, rotors and phasing rings cooperating to define variable volume chambers which expand to a maximum volume which is greater than twice the volume of a roller; and means effective to introduce fluid through one of said phasing rings to said spaced and to exhaust fluid therefrom through the other of said phasing rings.

8. A device for transmitting rotary movement, comprising: an annular housing having a cylindrical interior cavity, a rotatable shaft journaled in said housing, an outer rotor journaled within said housing cavity for rotation, an inner rotor drivingly associated with said shaft and disposed within but spaced from said outer rot-or, each of said rotors having complementary continuous series of convolutions, means comprising a pair of spaced phasing rings journalling a plurality of rollers arranged in circumferentially spaced relationship with each roller disposed to maintain rolling conjugation with each series of convolutions during relative rotation between said rotors, said rotor convolutions and roller set defining a plurality of spaces each of which undergoes an expansion and retraction in volume during a rotative cycle of the inner rotor.

9. A rotary device as in claim 8, in which there is a circular cylindrical bearing disposed in said housing cavity having a diameter less than said cavity and adapted to be moved for positoning the axis of rotation of said outer rotor disposed within said bearing, and control means for adjusting said bearing within said cavity and effective to maintain said bearing in said adjusted position.

10. A variable displacement pump of the gear-withina-gear type comprising: a circular cylindrical housing having a circular cylindrical cavity therein, a shaft ex- .tending into said housing and journaled for rotation therein, an annular bearing adjusted in position disposed within said caivty having freedom for limited movement to adjust the positioning thereof, an outer rotor journaled by said bearing effective to rotate about :an axis as defined by the bearing position, an inner rotor disposed within said outer rotor in spaced relationship and drivingly connected to said shaft for rotation therewith, each of said rotors having a continuous series complementary convolutions thereon with convolutions of opposed rotors facing each other, means comprising a pair of spaced phasing rings journalling a plurality of rollers arranged in circumferentially spaced relationship, each roller being effective to maintain rolling conjugation with each of said series of rotor convolutions upon relative rotation between said rotors, said inner rotor having one less convolution than the number of rollers of said roller set and said roller set having one less roller than the number of convolutions of said outer rotor, said roller set and said rotor convolutions together defining a plurality of spaces each of which expands and contracts during a rotative cycle of said inner rotor, and control means for adjusting the position of said bearing within said housing cavity whereby the degree of cyclic expansion and contraction of each of said spaces may be varied from a minimum to -a maximum value.

References Cited by the Examiner UNITED STATES PATENTS 1,389,189 8/ 19211 Feuerheerd l238 1,968,113 7/1934 Weaver 123l2 2,223,070 11/ 1940 Kleckner 103-126 2,490,115 12/1949 Clarke 103126 2,657,638 11/1953 English 103-126 2,672,824 3/1954 Quintil-ian 103-126 2,790,394 4/1957 Mori" 103 126 2,792,788 5/1957 Eames 103-126 MARK NEWMAN, Primary Examiner.

WILBUR J. GOODLIN, Examiner.

Claims (1)

1. A PUMP OF THE RING GEAR TYPE, COMPRISING: ANNULAR DRIVING AND RUNNING ROTORS ONE ARRANGED RADIALLY WITHIN THE OTHER, EACH ROTOR HAVING A CONTINUOUS SERIES OF UNIFORM CONVOLUTIONS WITH ONE SERIES OF CONVOLUTIONS FACING THE OTHER AND DEFINED SO THAT CIRCLES INSCRIBING EACH SERIES OF CONVOLUTIONS ARE SUBSTANTIALLY TANGENT AT ONE POINT, A PLURALITY OF EQUI-CIRCUMFERENTIALLY SPACED ROLLERS DISPOSED BETWEEN AND IN CONTACT WITH BOTH SAID SERIES OF CONVOLUTIONS AND HAVING A CIRCLE INSCRIBING THE AXES OF ROTATION OF SAID ROLLERS SUBSTANTIALLY TANGENT TO AT LEAST ONE OF SAID FORMER CIRCLES, MEANS COOPERATING WITH SAID ROTORS TO DEFINE FLUID CHAMBER AND BEING EFFECTIVE TO JOURNAL SAID ROLLERS THEREIN, FLUID INLET AND OUTLET MEANS EFFECTIVE TO INTRODUCE AND EXHAUST FLUID AT CIRCUMFERENTIALLY SPACED STATIONS FOR SPACES DEFINED BETWEEN SAID ROLLERS AND SERIES OF CONVOLUTIONS, THE RADIALLY OUTERMOST SERIES OF CONVOLUTIONS HAVING TWO MORE CONVOLUTIONS THEN THE SERIES OF RADIALLY INNERMOST CONVOLUTIONS AND SAID ROLLERS BEING ONE MORE IN NUMBER THAN SAID INNERMOST CONVOLUTIONS.

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