US3259073A

US3259073A - Planetary gear pump

Info

Publication number: US3259073A
Application number: US318670A
Authority: US
Inventors: Wilson A Burtis
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-10-24
Filing date: 1963-10-24
Publication date: 1966-07-05
Anticipated expiration: 1983-07-05

Description

July 5, 1966 w. A. BURTIS 3,259,073

PLANETARY GEAR PUMP Filed 001;. 24, 1963 4 Sheets-Sheet 1 E no.1.

INVENTOR.

W/LSOA/ A. B44977:

Wm ,yzmu

July 5, 1966 w. A. BURTIS 3,259,073

PLANETARY GEAR PUMP Filed Oct. 24, 1963 4 Sheets-Sheet 2 122/ INVENTOR.

1 WLSOA/ A. B02775 July 5, 1966 w. A. BURTIS 3,259,073

PLANETARY GEAR PUMP Filed Oct. 24, 1963 4 Sheets-Sheet 5 147- mQA/E KR July 5, 1966 w. A. BURTIS 3,259,073

PLANETARY GEAR PUMP Filed Oct. 24, 1963 4 Sheets-Sheet 4 li a. 15.

INVENTOR.

United States Patent 3,259,073 PLANETARY GEAR PUMP Wilson A. Burtis, 5011 Harvard Ave., Westminster, Calif.

Filed Get. 24, 1963, Ser. No. 318,670 7 Claims. (Cl. 103126) The present invention relates generally to fluid pumps, and more particularly describes novel constructions by which to provide a very compact pump adapted to deliver fluid at any desired pressure, including pressures in the range of 3,000 psi. and above, and employing an annular .sun gear having generally radially disposed passageways therein and planetary gears meshing with the sun gear.

In accordance with the invention, there is provided a pump body having a hollow housing in which is rotatably mounted a sun gear having a hollow internal chamber communicating with .an axially disposed outlet opening in the pump body, the gear having a plurality of generally radially extending passageways providing paths for fluid flow inwardly into the internal chamber from the spaces between the roots of the teeth. The pump body housing includes a generally annular outer chamber supplied with working fluid from an inlet opening, and one or more planetary gears are journaled to the body in the outer chamber having teeth equal in axial extent to the teeth of the sun gear. When adjusted for minimum slippage as later described, the planetary gears are in full involute running contact with the sun gear teeth, each planetary gear tooth entering a sun gear space being in continuous sealing relation along moving lines of contact with the sun gear teeth adjacent the space. The spaces between sun gear teeth are bounded axially by a pair of spaced flange plates carried either by the sun gear or by each planetary gear, preferably by the sun gear, and in running sealing engagement with the end walls of the teeth of the other gear. Thus the entrance of a planetary gear tooth into a sun gear space traps fluid in the virtually hermetically sealed cavity so formed, and further movement of the planetary gear tooth into the space serves to pump the trapped fluid radially inwardly through the respective passageway of the sun gear into the internal chamber and thence to the pump outlet opening.

Means are provided, operative after the pumping stroke is completed, to open the cavity to upstream fluid and thereby to relieve the vacuum or suction drag which would otherwise impose an unnecessary load on the pump during withdrawal of a planetary gear tooth from a sun gear space. Such means desirably include a configuration of the planetary gear teeth providing one or more recessed portions or notches interrupting the tooth edge which, if not so interrupted, would be in running sealing contact with the side wall of a sun gear tooth during withdrawal of the planetary gear tooth.

Means are also provided to prevent reverse flow of downstream pressure fluid (through those of the sun gear passageways which at a given moment, are not receiving fluid under pressure from their respective spaces. In one form of the invention, such means include check valves at the inner ends of the sun gear passageways, illustratively in the form of spherical members resiliently biased into sealing contact with the inner ends. In another form of the invention such reverse fluid flow is prevented by the provision of a stationary tubular outlet member having ported surfaces of convex cylindrical contour in running sealing engagement with the internal bore of the annular sun gear. Each port is in generally radial alignment with a planetary gear and communicates inwardly with a generally radial channel leading to the hollow interior of the outlet member. Desirably the channels 3,259,073 Patented July 5, 1966 are formed in shoe members carried by the tubular outlet member, the shoes being biased outwardly to form .a fluid-tight running seal with the bore of the sun gear. The outer cylindrical contour of each shoe may be provided with a vacuum relief groove either supplementing or supplanting the vacuum relief notching of one edge of each planetary gear tooth previously mentioned.

Desirably the sun gear is provided with an even number of teeth, and the planetary gears are arranged in oppositely disposed pairs therearound, whereby pumping impulses from a pair of gears are simultaneous and the system is dynamically balanced. Furthermore, to minimize pulsing flow giving rise to downstream pressure ripple, the pairs of gears are desirably staggered as to phase of their pumping strokes.

Means may be provided for selectively varying the displacement of the pump, a preferred form of such means including a construction by which to vary the positions of the planetary gear axes radially of the sun gear axis, thereby modifying the above described sealing relation between the planetary and sun gear teeth and permitting a controllably adjustable amount of slippage during operation. Thus each planetary gear may be journaled upon a cylindrical bearing seat of a shaft or support pin, the shaft in turn being mounted on the pump body for rotation about an axis eccentric relative to the planetary gear bearing surface. Means are further provided for fixing each shaft at a selected angular position about its axis, so that its planetary gear bearing seat may be positioned radially inwardly or outwardly as desired, including ganging means for identically adjusting the axes of all planetary gears simultaneously. This arrangement permits adjustment of the planetary gears to insure positive displacement by providing tight running contact between planetary and sun gears, not only initially to compensate for manufacturing tolerances, but also sub sequently during the life of the pump as may be desired. An exemplary control mechanism includes means for sensing pressure downstream of the pump and, for such pressure, moving the gauging means, thereby adjusting the etfective stroke of each tooth of the planetary gears in order to maintain the desired downstream pressure.

Accordingly, a principal object of the present invention is to provide and disclose novel improvements in planetary gear pumps. Additional objects and purposes are to provide, in such a pump, an annular sun gear having a plurality of generally radially disposed passageways extending through the body of the gear from the spaces between the teeth thereof; to provide in such a construction means for blocking selected passageways and thereby preventing reverse flow of the Working fluid during the inactive portion of the cycle of any particular such passageways; to provide means permitting adjustability of the position of a planetary gear axis radially of the sun gear; to provide displacement control or adjusting means in such a pump whereby to maintain a desired downstream pressure over a wide variation of flow; and for other and allied purposes as will be understood from a reading of the following description of preferred embodiments of the invention, taken in connection with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view of one form of pump embodying the present invention.

FIG. 2. is an end view of the pump of FIG. 1.

FIG. 3 is a perspective view of the sun gear assembly of the pump of FIG. 1.

FIG. 4 is a sectional view taken along the line IVIV of FIG. 1.

FIG. 5 is a fragmentary sectional view on an enlarged scale, showing the uppermost planetary gear and a portion of the sun gear at the end of the pumping stroke, a moment after the showing of FIG. 4.

FIG. 6 is a fragmentary perspective view of two teeth of a planetary gear showing the vacuum relieving notches on one edge of each tooth.

FIG. 7 is -a vertical sectional view of another embodiment of pump in accordance with the present invention.

FIG. 8 is an end view of the pump of FIG. 7.

FIG. 9 is a sectional view along line IX-IX of FIG. 7.

FIG. 10 is an exploded perspective view on an enlarged scale showing one form of sealing shoe assembly in the device of FIG. 7.

FIGS. 11, 12 and 13 are fragmentary views on an enlarged scale showing successive positions of the parts during a cycle of operation of the pump of FIG. 7.

FIG. 14 is an end view of a pump in accordance with the invention, including means for automatically controlling the displacement to maintain a desired fluid pressure downstream of the pump.

FIG. 15 is a vertical section-a1 view taken on line XV- XV of FIG. 14.

FIG. 16 is a fragmentary sectional view taken on line XVIXVI of FIG. 14.

Referring now in detail to the drawings, and first to FIGS. 1 and 2, the body of the pump as there shown includes a casing indicated generally at 20 and a cover plate indicated generally at 22 fastened to the plate by suitable means 24, the cover plate being provided centrally with a leftwardly extending ported boss 26. Within the casing 20, and closed by the cover plate 22, is a hollow chamber 28 housing the moving parts of the present pump. Working fluid from inlet conduit 30 enters the chamber 28 through an inlet opening formed in the peripheral boss 32, and output fluid under pressure from the pump is forced leftwardly through the axial bore 34 in the boss 26 to the downstream conduit 36.

The casing 20 is mounted upon one end of a suitable source of rotational power such as an electric motor indicated generally at 40, having a leftwardly extending output shaft 42 terminating in a threaded portion 44.

Journaled within the casing 20 on

bearings

46 and 48 is a sun gear assembly indicated generally at 50 (see FIG. 3) and including a central toothed portion 52 constituting the sun gear proper and a pair of flanking, annular side plates 54 and 56, the three said elements being fixed relative to one another by suitable means such as by a brazing or similar process during manufacture.

A plurality of planetary gears are mounted for rotation within the chamber 28, in mesh with sun gear 52. In the present illustrative embodiment of the invention, there are four such planetary gears, arranged as best appears in FIG. 4, in two pairs of diametrically

opposite gears

60, 61 and 62, 63. The sun gear 52 may desirably have an even number of teeth, in the present instance twenty. Since each planetary gear, as will be later described in detail, constitutes in effect an individual pumping element, the diametrically opposite arrangement of a pair of planetary gears tends to maintain the pump as a Whole in dynamic balance and to minimize load on the bearings thereof. Moreover, it is desirable that the planetary gears of different pairs be so placed that the pumping impulses from each pair are spaced or staggered in time, so that pulsation of flow downstream of the pump is minimized. Thus, in the present illustrative embodiment wherein the sun gear has twenty teeth and a resultant tooth pitch of 18, the axes of the

planetary gears

60, 61 may be disposed in vertical alignment with the axis of the sun gear 52, while the axes of planetary gears 62, 63 are angularly spaced by 9 from the horizontal plane through the axis of the sun gear.

As will be seen in FIGS. 4 and 5, sun gear 52 is provided with an internal passageway extending inwardly from each space between successive teeth to the hollow interior of the sun gear, the passageways lying preferably radially or substantially radially of the sun gear. As most clearly appears in FIG. 5, showing the parts a moment after the position of FIG. 4, a space 73 which receives therein a tooth 74 of planetary gear 60. Internal passageway 75 extends inwardly through the annular 'body of the sun gear from the space 73. Means are provided at the inner end of passageway 75, as well as at the inner ends of all other such passageways in sun gear 52, to prevent outward flow of fluid therethrough. Thus, at the inner end of passageway 75 there are check valve means in the form of a 'ball resiliently biased outwardly by a generally circular spring indicated generally at 81 and having angularly spaced ball receiving pockets 82 therein. The inner end 83 of channel 75 is spherically concaved in order to provide a sealing seat for the ball 80.

Assuming clockwise rotation of sun gear 52, it Will be seen in FIG. 4, that fluid is trapped in the cavity formed by tooth 74 entering space 73, the cavity being bounded axially by annular port-ions of side plates 54 and 56, which extend radially at least substantially to the tips of the sun gear teeth and preferably therebeyond as shown, being in sliding sealing contact with the end walls of the planetary gears. Fluid so trapped is forced inwardly through passageway 75, displacing ball 80 from its seat 83 during the pumping stroke, which is just end-ing with the parts as seen in FIG. 5. Because the planetary gear tooth is in sealing running contact with the sun gear teeth, each such entrance of a planetary gear tooth into a sun gear space provides a positive pressure pumping impulse, so that downstream pressures of very high values can be maintained.

Following the position of the parts of FIG. 5, tooth 74 commences to withdraw from space 73, and means are provided to permit entrance of upstream fiuid into the enlarging cavity so formed and thus to break the vacuum otherwise created therein. As best appears in FIG. 6, each planetary gear tooth has a leading edge 84- which is continuous, while the trailing edge 85 is interrupted by one or more recessed portions or notches of which two are illustratively shown at 86 and 87. Thus, referring back to FIG. 5, it will be seen that during the withdrawal stroke then beginning, with sun gear 52 rotating clockwise, the interrupted contact of non-continuous trailing edge 85 with the side wall of sun gear tooth 72 permits fluid to be drawn downwardly through the notched recesses 86 and 87 into the enlarging cavity in the space '73.

Desirably the

planetary gears

60, 61, 62 and 63 are so mounted within the chamber 28 as to permit a certain amount of adjustment of their axes radially of the sun gear 52. Thus, with particular reference to FIG. 1, planetary gear 60 is rotatably mounted upon a cylindrical seat 90 of a suppont pin indicated generally at 92, cylindrical seat 90 being eccentric relative to the concentric shank portions 9 4 and 96 received in aligned seats formed respectively in casing 20 and cover plate 22. The outer end of pivot pin 92 is desirably provided with a screwdriver slot or the like 98, and a lock nut 99 serves to maintain the pin 32 in any angular position in its relationship with the casing as may be desired, thereby adjusting the position of the eccentric seat 90 of the planetary gear 60 radially relative to the center of sun gear 52. The other planetary gears 61, 62 and 63 are similarly mounted. Thus, adjustment of the position of each of the planetary gears radially relative to the sun gear will control the amount of displacement per stroke during meshing contact of the planetary gears with the sun gear, and will moreover permit periodic adjustment of the planetary gears to compensate for wear over the life of the pump. In FIGS. 7, 8 and 9, together with the detailed showings in FIGS. 10, ll, 12 and 13, there is shown another embodiment of the invention wherein a tubular output member is fixedly carried by the cover plate and extends into the hollow interior of the annular sun gear, being there provided with a number of generally radial channels therethrough corresponding to the number of planetary gears used and in substantial radial alignment therewith.

More particularly, the pump seen in FIG. 7 includes a hollow casing indicated generally at 120 and a cover plate indicated generally at 122 fixed to the casing by suitable fastening means 124, the casing having formed therein an annular chamber 128 within which the operative components of the pump are mounted. An inlet opening 13% formed in a radially outwardly projecting boss 132 communicates input fluid to the internal chamher 128. High pressure fluid flowing outwardly of the pump moves axially lettwardly through the central bore of tubular output member indicated generally at 136 .carried by the cover plate 122. Output member 136 includes an enlarged annular internal portion 138, held in abutting sealed contact with the cover plate at 140 by a nut 142 threaded on the output member. The inner end of enlarged portion 138 is closed by end wall 139.

The casing 120 and the other parts heretofore described are mounted upon a motor indicated generally at 40 in the same manner as in the case of the device of FIG. 1 hereto-fore described, the motor being provided with a leftwardly extending output shaft 42 terminating in a threaded end 44.

Within the internal chamber 128 of the casing there is rotatably mounted on bearings 146 and 148 a sun gear assembly indicated generally at 150 and including a sun gear proper 152 (see FIG. 9) flanked by

annular plates

154 and 156. The three latter named components are fixed together forming an integral sun gear assembly, substantially in the manner heretofore described in connection with the device of FIG. 1, and threadedly mounted on output shaft 42. However, the inside diameter of sun gear assembly 150 is suificiently large to provide running clearance with the enlarged portion 138 of the output member 136. Similarly, the end wall 139 of the output member is spaced axially from the face of side plate member 156. One or more ports 157 may extend through plate 156, communicating .the annular space surrounding output member enlarged portion 138 with upstream fluid in chamber 128 and thereby relieving any fluid pressure in the annular space.

As will be seen in FIG. 9, the present embodiment of the invention includes six planetary gears arranged in diametrically disposed pairs, 160 and 16-1, 162 and 163, and 164 and 165. An equal number of generally radial openings are provided through the annular enlarged portion 138 of the output member 136. The outermost ends of such openings in the output member are in substantial alignment with the axis of each of the planetary gears. 'Desirably, each of the openings formed in the output member includes means resiliently biased outwardly in order to maintain sealing contact with the inside diameter of sun gear 152, such resiliently biased means provided with a channel formed therethr-ough constituting the actual flow path of fluid pumped by the present device.

In FIG. is shown a preferred form of such resiliently biased sealing means to be received in each opening of the output member. A sealing shoe indicated generally at 180 includes a lower cylindrical shank 181 and an upper polygonal head 182, with a channel 183 extending axially throughout the length of the shoe. The upper face 184 of the shoe is a portion of a cylindrical surface about a center eccentric relative to the longitudinal axis of the shoe itself, for reasons later appearing. Resilient means such as an annular sheet metal spring 185 is adapted to receive through its center the cylindrical shank 181 of the shoe and .to bear upwardly against the lower face of the polygonal head 182, immediately outwardly of the shank.

The entire shoe 180 is desirably made of a metal somewhat softer than the steel or equivalent metal of which the gears of the pump are made. In this way, the shoe, and more particularly the cylindrical outermost face 184,

will receive the major portion of wear over the life of the pump, while sealing contact between the outermost cylindrical surface and the inner cylindrical surface of sun gear 152 is maintained by the resilient member 185. Desirably the channel 183 is somewhat tapered from a maximum outer cross-sectional area to a smaller inner area, so that a component of pressure fluid forced therethrough tends to urge the shoe inwardly, against the force of spring 185, thereby minimizing the frictional effect between the shoe face and the sun gear during high pressure operation.

As will be seen in FIG. 9, the shoe 180 is one of six identical shoes, together with a resilient member 185 in conjunction with each, slidably received in correspondingly formed openings formed in the enlarged portion 138 of the output member 136. The openings may be radially oriented, but preferably are inclined at an angle of the order of 10 to a radius of the output member. The precise orientation and relationship of the parts during operation of the pump will be understood by reference to the detailed showings of FIGS. 11, 12 and 13, representing successive moments during operation as sun gear 152 rotates clockwise.

Thus, in FIG. 11 the tooth 174 of planetary gear is shown with its outermost tip 169 making contact with the upper portion of the side wall of tooth 170, while the base portion of tooth 174 has made contact with the side of the tip of tooth 172. Keeping in mind that the inwardly facing surfaces of

plates

154 and 156 are in sealing contact with the side walls of planetary gear 160, it will be seen that fluid is entrapped in the cavity consisting of the remaining space 173 between the

teeth

170 and 172 of the sun gear. Consequently, with continued rotation into the position seen in FIG. 12, such entrapped fluid will be forced, by reason of the diminishing volume of the cavity, downwardly through the radial passageway 175 of the sun gear and into the axial channel 183 of the shoe and thence into the central tube 134 of the output member 136.

Continued clockwise movement of the sun gear 152 brings the parts to the final portion of the pumping stroke as seen in FIG. 13. At this point the volume of the cavity is at a minimum, so that fluid flow in passageway 175 is momentarily stopped. Further movement of the parts will result in an increase of the volume of the cavity, and means are desirably provided for permitting fluid flow upwardly through the passageway 175 into the cavity. In the present form .of the invention, such means include a relief groove 186 formed on the trailing side of the outer face 184 of shoe 180, providing a path of fluid flow into the lower end of the passageway 175 from the annular space between the enlarged portion 138 and the inside diameter of sun gear 152.

In summary as to the operation shown in FIGS. 11, 12 and 13, and with particular attention to the relationship between passageway 175 and shoe channel 183, it will be seen that the lower end of passageway 175 is just opening into communication with channel 183 in FIG. 11, with tooth 174 commencing its pumping stroke; that the passageway and channel are virtually fully opened to each other in FIG. 12 with the tooth 174 approximately half way through its pumping stroke; and that the passageway and channel are just closing in the position seen in FIG. 13, with the tooth 174 at the effective end of its pumping stroke. Consideration of the movement of the fluid through such passageways will also emphasize the desirability of the angular inclination of the shoe 180, or at least of its channel 183, relative to a radius of the sun gear and output member. Thus, the absolute motion of fluid moving generally downwardly through passageway 175 includes a component moving rightwardly, resulting from clockwise rotation of the sun gear. This rightward component is permitted to continue, to a certain degree, during the further generally downward flow of the fluid through the channel 183, by

reason of such inclination, thus minimizing turbulence and other adverse effects otherwise resulting from a sharp or abrupt change of direction of fluid flow.

For reasons previously discussed in connection with the embodiment of the invention first described and illustrated, it is desirable in the form of the pump shown in FIG. 7 to provide some adjustability of the positions of the axes of the planetary gears radially of the sun gear. Thus, with particular reference to FIG. 7, a support pin indicated generally at 192 includes a cylindrical seat 190 upon which planetary gear 160 is rotatably mounted. The cylindrical seat 190 is eccentric relative to the

portions

194 and 196 of the pin, which are received in aligned openings formed in the casing 120 and cover plate 122 respectively. The pin 190 may be rotated about the axis of the latter named openings by means such as a screw driver slot 198, and the pin locked in desired position by lock nut 199.

Adjust-ability of the positions of the planetary gears radially of the sun gear axis is advantageous also in order to vary the effective displacement of the pump during operation. This function may be performed by means responsive to downstream pressure of the fluid supplied by the pump, whereby to maintain such downstream pressure at a desired value over a wide range of variation in the amount of flow demanded by the apparatus supplied by the pump. A preferred arrangement for accomplishing this is shown in FIGS. 14, and 16, where a total of four planetary gears is shown, for clarrty of illustration. It is to be understood that this construction is applicable to either of the forms of the invention heretofore shown and described.

In accordance with the apparatus of FIGS. 14, 15 and 16, an actuating assembly indicated generally at 200 is mounted upon one end of the pump by suitable means such as an angle bracket 202. The assembly 200 includes a cylindrical casing 204 having slidably mounted therein a piston 206 to which is connected a piston rod 208. A cam plate indicated generally at 210 is mounted for rotation upon a central hub 212 of a cover plate 1nd1- cated generally at 222, the plate 210 being retained on the hub by a lock ring 214. The outermost end of piston rod 208 is in-turned at 209 and is received in aperture 215 formed in the cam plate.

The periphery of camming plate 210 is provided with a number of spaced, generally semi-circular indentations 216, to permit limited angular movement of the plate 210 on hub 212 without interference with the planetary gear support pins extending through the indentations. Planetary gear 224 is rotatably mounted upon a cylindrical seat 226 of a support pin indicated generally at 228. The seat 226, as in the case of the forms of the invention earlier described and illustrated, is eccentric relative to the axis of pin 228, as determined by coaxial cylindrical support surfaces 230 and 232, rotatably received in aligned bores of the cover plate 222 and the pump body (not shown).

Leftwardly of support surface 230 on pin 228 there is provided a threaded shank 240* of reduced diameter, and an apertured end of a bell crank arm indicated generally at 242 is mounted upon the threaded shank abutting the shoulder of surface 230 and held in fixed relation with the pin 228 by a nut 244. It will be understood that the angular position of the axis of pin 228 may be adjusted preliminarily as desired, and that such adjustment relative to the bell crank arm 242 will be maintained when the nut is tightened upon the bell crank arm. The outer end of bell crank ar'm 242 is provided with a pin 250 which is received in 'slidable engagement with a camming slot 252 formed in the camming plate 210. The other planetary gear support pins are similarly provided with bell crank arms having outer ends in camming engagement with slots formed in the camming plate 210, whereby rotation of the latter plate about its mounting upon hub 212 causes identical angular movement of each of the support pins about its oWn axis, thereby adjusting the position of its corresponding gear radially of the sun gear.

Output or downstream pressure of the pump existing in conduit 270 is communicated through sensing tube 272 to the upper end of the cylinder 200, above the piston 206 slidably mounted therein. The piston is biased upwardly by resilient means such as spring 274, so that the piston assumes a position longitudinally of cylinder 200 as determined by the balance of the force of the spring 274 and the force of pressure fluid in the upper chamber 276 closed by threaded plug 278. Such linear movement 01f piston rod 208 causes angular rotational movement of plate 210 about hub 212 by reason of the engagement of end 209 in opening 215, thereby adjusting the axes of all planetary gears radially of the sun gear. It may be noted that the planetary gear axes move slightly angularly about the sun gear axis while moving radially thereof. Such angular movement is immaterial in the form of the invention first shown and described, and is so small as to be inconsequential in the second form.

It will be understood that the adjusting mechanism of FIGS. 14, 15 and 16 operates in an inverse feedback manner. Thus a tendency for the downstream pressure to increase above a predetermined value moves piston 206 downwardly as seen in FIG. 14, and the resulting camming adjustment of the planetary gear axes moves the planetary gears radially outwardly into less hermetically tight contact with the sun gear, thereby decreasing both the amount of fluid pumped per stroke and the pressure imposed thereon. The piston will accordingly seek a balanced position determined by the force of spring 274. In a typical installation the strength of the spring is originally selected in the light of the design requirements of the system in which the present pump is to be used, and need not ordinarily be changed so long as those requirements remain unchanged.

Although certain illustrative embodiments of the invention have been herein shown and described, minor modifications and changes therefrom may be made, and are intended to be embraced within the scope of the appended claims.

I claim:

1. A fluid pump comprising:

a hollow housing;

an annular sun gear rotatably mounted in the housing having a central bore and generally radial passageways communicating said bore with the spaces between successive teeth;

a planetary gear rotatably mounted in the housing and meshing with the sun gear, the planetary gear teeth and sun gear teeth being equal in axial dimensron;

axially spaced flange means sea-lingly bounding the sun gear space during meshing engagement therein of a planetary gear tooth;

means preventing fluid flow outwardly through all passageways except the passageway communicating With a sun gear space receiving a planetary gear tooth, including a tubular output member fixedly mounted centrally of the sun gear and having a generally radial channel therein, the output member having its inner axial end closed and its outer axial end constituting the pump outlet port,

a shoe movably carried by the output member for movement generally radially thereof, the outer surface Olf the shoe having a cylindrical contour in sealing engagement with the portion of the sun gear bore surface defining the inner end of said excepted passageway, and the shoe having said channel formed therein;

said housing being provided with a fluid inlet port in communication with .the meshing zone of said gears;

and means for rotating the sun gear.

2. The invention as stated in claim 1 wherein said cylindrical contour surface has a generally circumferentially extending groove formed therein communicating with said excepted passageway only during withdrawal of a planetary gear tooth from the sun gear space communicating with said passageway.

13. The invention as stated in claim 1 wherein said channel is inclined to the radius of the output member at the outer end of said channel.

4. The invention as stated in claim 1 including means resiliently urging the shoe outwardly into said sealing engagement with the sun gear bore surface.

5. A fluid pump comprising:

a hollow housing;

a planetary gear rotatably mounted in the housing and meshing with the sun gear, the planetary and sun gear teeth being equal in axial dimension and movement of a planetary gear tooth into a sun gear space constituting a pumping stroke;

axially spaced flange means sealingly bounding the sun gear space during the pumping stroke;

an output member fixed to the housing, including a portion disposed in the sun gear bore, a shoe movably carried by said portion for movement generally radially of the bore and having formed therein a channel whose radially outer end is surrounded by a shoe outer convex surface contoured to sealing contact the concave surface of the sun gear bore surrounding the inner end of passageway during the pumping stroke of its associated sun gear space, the channel being in fluid communication with said passageway during said stroke, and means urging the shoe outwardly into said sealing contact, said output member having a portion provided with a pump outlet port in fluid communication with said channel;

said housing having a fluid inlet port formed therein in fluid communication with the mesh-ing zone of said gears;

and means for rotating the sun gear.

6. The invention as stated in claim 5 wherein said shoe outer convex sunface is provided with a generally circumferentially extending groove formed therein communicating with said passageway inner end only during withdrawal of a planetary gear tooth from said associated sun gear space.

7. The invention as stated in claim 5 wherein said channel is inclined to the sun gear radius to the passageway inner end during the pumping stroke.

References Cited by the Examiner UNITED STATES PATENTS 1,418,741 6/1922 Stallman 103-126 1,456,694 5/1923 Ingraham 103126 1,728,529 9/1929 Butler 103-126 1,902,346 3/1933 Vogt 103-126 1,909,418 5/1933 Norwood 103-126 1,912,738 6/1933 Svenson 103126 2,601,003 6/1952 Pontius 103126 2,845,031 7/1958 Guibert 103126 3,067,691 12/1962 Wiggermann 103-120 3,077,835 2/1963 Wiggermann 103120 MARK NEWMAN, Primary Examiner.

WILBUR J. GOODLIN, Examiner.

Claims

1. A FLUID PUMP COMPRISING: A HOLLOW HOUSING; AN ANNULAR SUN GEAR ROTATABLY MOUNTED IN THE HOUSING HAVING A CENTRAL BORE AND GENERALLY RADIAL PASSAGEWAYS COMMUNICATING SAID BORE WITH THE SPACES BETWEEN SUCCESSIVE TEETH; A PLANETARY GEAR ROTATABLY MOUNTED IN THE HOUSING AND MESHING WITH THE SUN GEAR, THE PLANETARY GEAR TEETH AND SUN GEAR TEETH BEING EQUAL IN AXIAL DIMENSION; AXIALLY SPACED FLANGE MEANS SEALINGLY BOUNDING THE SUN GEAR SPACE DURING MESHIN ENGAGEMENT THEREIN OF A PLANETARY GEAR TOOTH; MEANS PREVENTING FLUID FLOW OUTWARDLY THROUGH ALL PASSAGEWAYS EXCEPT THE PASSAGEWAY COMMUNICATING WITH A SUN GEAR SPACE RECEIVING A PLANETARY GEAR TOOTH, INCLUDING A TUBULAR OUTPUT MEMBER FIXEDLY MLUNTED CENTRALLY OF THE GUN GEAR AND HAVING A GENERALLY RADIAL CHANNEL THEREIN, THE OUTPUT MEMBER HAVING ITS INNER AXIAL END CLOSED AND ITS OUTER AXIAL END CONSTITUTING THE PUMP OUTLET PORT, A SHOE MOVABLY CARRIED BY THE OUTPUT MEMBER FOR MOVEMENT GENERALLY RADIALLY THEREOF, THE OUTER SURFACE OF THE SHOE HAVING A CYLINDRICAL CONTOUR IN SEALING ENGAGEMENT WITH THE PORTION OF THE SUN GEAR BORE SURFACE DEFINING THE INNER END OF SAID EXCEPTED PASSAGEWAY, AND THE SHOE HAVING SAID CHANNEL FORMED THEREIN; SAID HOUSING BEING PROVIDED WITH A FLUID INLET PORT IN COMMUNICATION WITH THE MESHING ZONE OF SAID GEARS; AND MEANS FOR ROTATING THE SUN GEAR.