US3490383A

US3490383A - Hydraulic pump or motor

Info

Publication number: US3490383A
Application number: US805081*A
Authority: US
Inventors: John T Parrett
Original assignee: Koehring Co
Current assignee: Dana Inc; Bank of New England NA
Priority date: 1969-01-29
Filing date: 1969-01-29
Publication date: 1970-01-20
Anticipated expiration: 1987-01-20

Description

Jan. 20, 1970 PARRETT 3,490,383

HYDRAULIC PUMP OR MOTOR Filed Jan. 29, 1969 'guf.

if 13 i0 5 Sheets-Sheet 1 Jan. 20, 1970 J. T. PARRETT 3,490,383

HYDRAULIC PUMP OR MOTOR Filed Jan. 29, 1969 3 Sheets-Sheet 2 j j; 1 J16 Jan. 20, 1970 J. T. PARRETT HYDRAULIC PUMP OR MOTOR 3 Sheets-$heet 5 Filed Jan. 29, 1969 WNW NNN United States Patent 3,490,383 HYDRAULIC PUMP OR MOTOR John T. Parrett, Benton Harbor, Mich., assignor to Koehring Company, a corporation of Wisconsin Continuation-impart of application Ser. No. 574,180, Aug. 22, 1966. This application Jan. 29, 1969, Ser. No. 805,081

Int. Cl. F04c 1/02, 3/00 US. Cl. 103130 19 Claims ABSTRACT OF THE DISCLOSURE An orbital gear motor of the type having an externally toothed member rotatable about a fixed axis and connected to a drive shaft and an internally toothed orbiting member intermeshing therewith, with at least one end plate having a plurality of inlet and outlet ports an nularly arrayed therein adapted to be selectively opened and closed by the orbiting gear member.

This application is a continuation-in-part of application Ser. No. 574,180, filed Aug. 22, 1966, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates generally to hydraulic energy translating devices and more particularly to a hydraulic pump or motor device of the type having intermeshing gears.

In one type of intermeshing gear hydraulic device, one of the gear members is arranged to have orbital movement relative to the other gear member. By suitably arranging the input or output shaft relative to the gear members, hydraulic units of this type have been found to provide increased torque or capacity (depending upon whether the device is operating as a motor or as a pump) over prior known hydraulic devices of the gear type. Due to the geometry in orbital units the high and low pressure chambers formed by the interengaging gear teeth have circumferential motion, and the construction of a device which properly ports fluid to and from these chambers has been found diflicult. One prior solution has been a rather complex commutator valve which rotates at the same speed as the orbiting one of the gears. Such valving arrangements have both the disadvantage of complexity and limited applicability to units in which the orbiting gear has rotational, as well as orbital movement. All". other prior solution to this problem involves the provision of passages in the inner externally toothed gear member where the outer gear member, internally toothed, is the orbiting one of the members. These passages communicate with stationary ports aligned on the same circle as the passages in both of the end plates, the high pressure ports being in one plate, and the low pressure ports being in the other. This arrangement has the disadvantage of requiring extensive machining of .the passages in the inner gear member and further requires the high pressure ports to be formed in one end plate and the low pressure ports to be formed in the other to prevent a communication between the high and the low pressure sides of the system.

Summary of the invention It is, therefore, a primary object of the present invention to provide a new and improved gear type hydraulic unit in which one of the gear members partakes of orbital movement with a simplified and improved valving arrangement to deliver fluid to and from the unit.

A further object of the present invention is to provide an orbital gear hydraulic unit of the type described in ice ing and contracting fluid chambers, by the gear teeth themselves on the orbiting gear member.

A further object of the present invention is to provide a new and improved gear type hydraulic unit of the type described in which slots formed in one side of the orbiting gear member cooperate with alternately and annularly arranged high and low pressure ports in a valve plate to effect proper valving for the unit.

Still another object of the present invention is to provide a new and improved orbital gear type hydraulic unit of the general type described including a stationary outer member having internally disposed gear teeth, an intermediate member having both externally disposed gear teeth cooperating with the stationary gear teeth and internally disposed gear teeth, with the internally disposed teeth engaging cooperating teeth on an inner gear member mounted for rotation about a stationary axis, there being provided fluid chambers both between the stationary and intermediate gear members and between the intermediate gear member and the inner gear member to provide a hydraulic unit of increased capacity and torque over those heretofore known in the prior art.

Still another object of the present invention is to provide a multiple gear hydraulic unit of the type described immediately above in which passages or slots formed in the intermediate gear member serve to deliver fluid from high and low pressure ports to both sets of fluid chambers in a simplified manner.

A still further object of the present invention is to provide an improved gear type hydraulic unit of the type generally described above including an improved balancing plate at the end of the gear members opposite the ports for the purpose of hydrostatically balancing the gear members.

Brief description of the drawings FIG. 1 is a longitudinal section of a hydraulic unit according to one embodiment of the present invention;

FIG. 2 is a cross section of the hydraulic unit of FIG. 1, taken generally along line 22 of FIG. 1;

FIG. 3 is a longitudinal section of a hydraulic unit according to another form of the present invention;

FIG. 4 is a cross section, taken generally along line Description of the} preferred embodiment Referring now to the drawings and more particularly to the embodiment of the invention shown in FIGS. 1 and 2, a hydraulic motor device 10 is shown generally including hydraulic fluid inlet and outlet ports 12 and 13, mat- 1 ing gears 14 and 15 for receiving and expelling hydraulic which commutative valving is provided, for theex'pandfluid, and an output shaft 16 driven in rotation by the inner gear 15. While the present invention is described as a hydraulic motor, it should be understood that the device may operate as well as a pump by rotating the shaft 16 with a suitable prime mover and in this mode the mating gears will compress hydraulic fluid and deliver the same under pressure through one of the ports 12 or 13.

More specifically, the hydraulic unit 10 has a housing consisting of an end member 17, a central annular member 18, and a cover plate 19 all fastened together as a unit by suitable through bolts 21. The input shaft 16 is supported within the housing by roller bearing 23 mounted in housing section 17, and ball bearing 25 mounted in a port and support member '26 received within suitabl counterbores in the-housing section 19.

Interposed between the

housing sections

18 and 19 is a valve plate 28 which defines within the housing member 18 a chamber 30 within which the gear members 14 and cooperate.

The gear members 14 and 15 have respectively internal and external gear teeth 32 and 33 of a conventional shape that continuously engage during relative rotation between the gear members and define therebetween sealed expanding and contracting fluid chambers 35.

The internally toothed gear member 14 is arranged for orbital movement within the chamber 30. For this purpose, the outer diameter of the bear member 14 is less than the internal diameter of the housing member 18 and has formed on the periphery thereof a plurality of teeth 37 equal in number to internally formed teeth 39 in the housing member 18. As the number of teeth on gear member 14 and housing member 18 are equal, rotational movement of the gear member 14 about its own axis 40 is prevented, but orbital movement thereof is permitted about the centroid 41 of the chamber which is also the axis of rotation of the externally toothed gear member 15.

The externally toothed member 15 is formed with a lesser number of teeth than the internally toothed member 14 to effect the necessary relative rotation between these gear members. In the embodiment shown, seven teeth 32 are provided on the internally toothed member and six teeth 33 are provided on the externally toothed member. As shown in FIG. 2, the tooth 33 is fully meshed. As used hereinbelow a full mesh axis 44 extends through the axis of rotation 41 and the orbiting center 40 of the internally toothed member 14. This axis always passes through the teeth 32, 33 that are fully meshed, so that the fluid chambers on one side of the axis are high pressure chambers and those on the other side are low pressure chambers.

Assuming counterclockwise rotation of shaft 16 and externally toothed member 15, the internally toothed member 14 will orbit in a clockwise direction, i.e., the center will partake a circular path about rotational axis 41. As seven teeth are formed on the internally toothed member and six are formed on the externally toothed member, the internally toothed member will make six orbital revolutions for each revolution of the externally toothed member 15. This means that the full mesh axis 44 will also make six revolutions for each rotation of shaft 16.

Assuming motoring operation and counterclockwise rotation of shaft 16, the chambers 35' will be high pressure expanding fluid chambers while chambers 35" will be low pressure contracting fluid chambers. Now since the high and low pressure chambers are defined by the full mesh axis 44, they rotate, in the present device, with respect to the outer member 18, so that stationary inlet and outlet ports for the high pressure 35 and low pressure 35 chambers would not effect the necessary valving for these chambers. Note that the full mesh axis 44 rotates in a clockwise direction both with respect to the internally toothed member 14 and with respect to the externally toothed member 15.

For motoring operation, the inlet port 12 is connected to a suitable source of fluid under pressure, such as a pump (not shown), and the outlet port 13 is connected to a suitable tank or the inlet of the pump. For communicating the inlet 12 with the valve plate 28, a plurality of axial and

radial passages

48 and 49 are provided in the support member 26. These passages continuously communicate with high pressure ports 50 in the valve plate 28. As shown in FIG. 2, the high pressure ports 50 are annularly arrayed through the plate 28 with low pressure ports 51. Note that the high and low pressure ports are alternately arranged on the same circle. The high pressure ports 50 and the low pressure ports 51 are equal in number, each equaling the number of teeth 32 on the internally toothed member 14. In the example shown there are seven high pressure ports, seven low pressure ports, and seven teeth 32. Low pressure p rts 51 communicate with the outlet 13 through axial passages 55 in the support 26 and counterbore 56 in the housing member 19.

Ports

50, 51 have a diameter slightly greater than the arcuate distance between the ports and are defined on a circle formed about the axis of the centroid 41 of the chamber 30. The diameter of this circle is greater than the diameter of the circle defined by the crests of teeth 33 on the internal gear member 15 and less than the diameter of the circle defined by the roots of the teeth 32 on the external gear member. With this construction, the teeth 32 on the outer gear member 14 open and close the

ports

50 and 51 as the gear member 14 orbits.

A hydraulically balanced sealing plate 60 is provided on the side of the gears 14, 15 opposite the valve plate 28. Pressure plate 60 is mounted in a suitable counterbore 61 in the housing member 17 and serves to seal the fluid chamber 35. Formed in the side of the sealing plate 60 opposite the gears are several annular recesses 63 which receive fluid from the high pressure chambers 35' through restricted passages 65 and bores 66. In this manner, a small portion of the hydraulic fluid entering the device passes through passages 65 to recesses 63 urging the plate 60 toward the gear members to efiect proper sealing of the gears.

The operation of the embodiment shown in FIGS. 1 and 2 is as follows: With high pressure fluid entering port 12, the chambers 35 on the left side of the full mesh axis 44, shown in FIG. 2, will be pressurized as ports 50 communicate therewith, while chambers 35" on the right side of axis 44 will communicate with outlet port 13 through the low pressure ports 51 which communicate therewith. The relatively high fluid pressure in chambers 35' begins expansion thereof causing orbital movement of the outer gear member 14 in a clockwise direction. When the outer gear 14 orbits 180 degrees from the position shown in FIG. 2, the high pressure chambers 35 and the low pressure chambers 35 will have rotated 180 degrees as well. In this position, the chambers on the left side of the axis 44 (which rotates too) are contracting low pressure chambers communicating with the low pressure ports 51 which are then uncovered by the teeth 32 on the left side of the axis 44, as shown in FIG. 2.

This valving action may be seen more clearly by viewing two adjacent teeth 32 and the

ports

50 and 51 closest thereto. For example, the upper tooth 32A opens and closes low pressure port 51A, while the lower tooth 32A opens and closes the high pressure port 50A. As the lower tooth begins orbiting clockwise from its position shown in FIG. 2, it will close port 50A and immediately thereafter the upper tooth 32A will open low pressure port 51A causing the chamber formed between the teeth 32A and 32A? to become a low pressure chamber 35". As the outer member 14 orbits downwardly, the upper tooth 32A will close port 51A and the lower tooth 32A will open port 50A changing the associated fluid chamber back to a high pressure chamber. This cycle occurs once for each orbit of the outer gear member 14 so that the chamber between each of the teeth 32 are high pressure chambers for one-half of an orbit and low pressure chambers for the other half of the orbit.

Each time the outer gear member 14 orbits, the inner gear 15 and .the output shaft 16 turn in a counterclockwise direction one-sixth of a revolution (one tooth on the inner gear 15) so that after six orbits of the outer gear 14, the output shaft 16 will rotate one revolution. This provides the high torque capacity of the present device.

The embodiment shown in FIGS. 3 and 4 is somewhat similar in operation to the embodiment shown in FIG. 1 except that additional fluid pressure chambers are provided and the valving is effected in a somewhat different manner.

As shown in FIG. 3, the hydraulic motor includes

housing members

117, 118 and 119 held together by fasteners 121 similar to the FIGS. 1 and 2 embodiment.

Inlet and

outlet ports

112 and 113 are formed within the housing member 119. Inlet 112 communicates with high pressure ports 150 in valve plate 128 through axial passages 148 and radial passages 149 in a manner very similar to that shown in the FIGS. 1 and 2 embodiment. Likewise, low pressure outlet port 13 communicates with low pressure ports 151 in the valve plate through axial passages 155 and counterbore 156 in the housing 119. However, in the embodiment of FIGS. 3 and 4, internally disposed gear teeth 139 on casing member 118 and external gear teeth 137 on gear member 114 are formed to provide continuous sealing engagement with one another and expanding and contracting fluid chambers 170 therebetween, providing additional capacity for the unit increasing the torque when acting as a motor and increasing the output flow when acting as a pump over the embodiment shown in FIGS. 1 and 2.

The number of external teeth 137 on the intermediate gear member 114 is one less than the number of teeth 139 on the casing member 118. In this manner, intermediate gear member 114 orbits about axis 141 in a clockwise direction, and it will also rotate about its own geometric axis 140 in a counterclockwise direction. Each time the intermediate member 114 orbits, it will rotate one tooth so that in the exemplary embodiment shown wherein fifteen teeth 139 are provided and fourteen teeth 137 are provided, fourteen orbits of the intermediate member 114 are required for each complete revolution thereof about its own axis 140.

The intermediate member 114 also has internally disposed teeth 132 which sealingly engage externally disposed teeth 133 on an inner gear member 115 in the same manner as in the FIGS. 1 and 2 embodiment. The fluid chambers 135 expand and contract as the intermediate gear member 114 orbits and rotates in a similar manner as in the FIGS. 1 and 2 embodiments except that the rotational motion of the member 114 somewhat increases the angle of rotation of the inner gear member 115 with respect to the angle of movement of the full mesh axis 144 which extends through the axis of rotation 141 of the inner gear and the orbiting centroid 140 of the intermediate gear 114. Note that the full mesh axis 144 divides the high and low pressure chambers 135, as well as the high and low pressure chambers 170. For counterclockwise rotation of shaft 116, the chambers 135 on the right side of axis 144 are high pressure expanding chambers and the chambers 135" on the left side of axis 144 are low pressure contracting chambers. Further, chambers 170' on the left side of axis 144, shown in FIG. 4, are high pressuge expanding chambers, while chambers 170" on the right side of axis 144 are low pressure contracting chambers.

The high and low pressure ports 150 and 151 are arranged in the present device to deliver fluid to and from both the chambers 135 and the chambers 170. Toward this end, the ports 150, 151 are defined on a circle about the axis 141 of shaft 116 having a diameter approximately equal to one-half the sum of the diameter of the roots of teeth 132 and the diameter of the roots of teeth 137. There are in the exemplary embodiment shown, fourteen high pressure ports 150 and fourteen low pressure ports 151, each equal to twice the number of internally disposed teeth 132 (seven) on the intermediate member, the total ports being twice the number of external teeth 137 (fourteen) on the intermediate member 114.

Rather than the teeth themselves effecting valving with the high and low pressure ports as in the FIGS. 1 and 2 embodiment,

slots

175 and 176 are provided in one side of the intermediate gear 114 for opening and closing the ports and communicating them with the expanding and contracting fluid chambers between the gears. Slots 175 are shallow, radially extending grooves on the port plate side of the gear 114 communicating at their end-s with the chambers 170 at the roots of teeth 137. The number of slots 175 provided depend upon and are equal to the number of teeth 137. Slots 176 are similarly shaped and 6 communicate with the chambers at the roots of teeth 132. Slots 176 are equal in number to the teeth 132.

In operation of the FIG. 3 and FIG. 4 embodiment, and assuming high pressure fluid to be ported to inlet 112 pressurizing ports 150, the following operation occurs. Chambers 170 on the left side of axis 144 becomes pressurized as the ports communicate therewith through slots 175 on the left side of axis 144. At the same time, chambers 135 on the right side of axis 144 are also pressurized as ports 150 communicate therewith through slots 176. The chambers and the chambers 13S" communicate with low pressure through ports 151. Clockwise orbital movement of the intermediate member 114 will begin with centroid 140 proceeding in a circular path about the axis of rotation 141. The high pressure chambers 135 and low pressure chambers 135" rotate in the same manner as in the FIGS. 1 and 2 embodiments. It should be noted, however, that due to the fact that intermediate gear member 114 rotates counterclockwise about its own axis 140 that the output shaft 116 will make one revolution for somewhat less than six orbits of the intermediate gear member 114.

Valving in the FIGS. 3 and 4 embodiment is somewhat different that the FIGS. 1 and 2 embodiment, as the valvingslots and 176 have hypocycloidal motion rather than simple orbital movement as in the FIGS. 1 and 2 embodiments. That is, because of the rotational motion of the intermediate member 114, as well as orbital, each

slot

175 and 176 serially passes from one low pressure port 151 to the next highpressure port 150, and from there to the next low pressure port 151, etc., each serially communicating with all of the ports. The ports 150 and 151 are sized and spaced so that each

slot

175 and 176 communicates therewith through approximately one-half of each orbit of the intermediate member 114, and in this manner the proper valving action is effected.

It should be understood that the direction of flow of hydraulic fluid through either the embodiment shown in FIGS. 1 and 2 or the embodiment shown in FIGS. 3 and 4 may be reversed to reverse the direction of rotation of the output shaft, and that either device may be operated as a pump merely by rotating the shaft.

In FIG. 5 an additional embodiment of the present invention is shown generally similar to the FIGS. 1 to 4 embodiments further including an improved pressure balancing plate construction. A generally annular housing member 211 has a bearing 212 rotatably supporting one end of the output shaft 213 adapted to drive a suitable load when the hydraulic unit acts as a motor.

The casing for the hydraulic unit is further defined by a generally annular housing member 216 having teeth 217 formed internally therein in a manner similar to the FIGS. 1 and 2 embodiments. Closing the housing member 216 is an end cap 219 fastened to the housing members 211 and 216 by suitable threaded fasteners 222. Shaft 213 is keyed to an internal gear 224 which intermeshes with an orbiting gear 225 having external teeth 226 engaging teeth 217 on the housing 216 as its orbits. The

gears

224 and 225 form expanding and contracting fluid chambers in the same manner as in the FIGS. 1 and 2 embodiments.

Positioned and fixed within the housing member 211 is a valve member 230 which serves to convey fluid to and from the expanding and contracting chambers between the gears through ports 232 and 233. It should be understood that there are a plurality of ports 232 and 233 and that they alternate with one another in a circle concentric about axis 235 of shaft 213. Ports 233 are interconnected with one another through a first manifold 238 while ports 232 are interconnected with one another by a manifold 240, both of these being defined by annular spaces between the housing member 211 and valve member 230.

A pressure balancing plate 244 is provided for the purpose of balancing the hydraulic forces acting on the right ends of

gear members

224 and 225 from ports 232 and 233 (the high pressure ones), as well as for urging the pressure plate itself into engagement with the left sides of the gears.

Pressure plate 244 is mounted within a stepped counterbore 246 in the housing end cap 219 and has a centrally disposed bearing 248 therein rotatably supporting the distal end of driven shaft 213. Annualr grooves 252 and 253 are provided in the pressure plate 244 concentric with respect to axis 235 and extending inwardly from the end of the pressure plate adjacent the end cap 219. Groove 253 has a greater width than the groove 252 to provide substantially equal areas.

Groove 253 communicates through passages 256 with apertures 257 corresponding in number and size as Well as alignment With ports 233. Similarly, groove 252 communicates through apertures 258 with apertures 2611a equal in number and size and in alignment with the ports 232.

Positioned innermost in the grooves 252 and 253 are rigid steel rings 260 and 262 having annular grooves therein on their outer corners defining annular passages 264 and 265 which communicate with the apertures 260a and 257 respectively.

Seated in the ends of grooves 252 and 253 are rigid metal rings 268 and 269 which engage the housing memher 219. Seated between the rings 260 and 262, and rings 268 and 269 are resilient O-

rings

272 and 273 which seal the sides of the grooves 252 and 253 and are somewhat pinched between the associated rings.

The annular passages 264 and 265 function to interconnect whichever of the paertures 257 or 260a that are aligned with the high pressure ones of the ports 232 and 233 to provide a pressure balance on the

gear members

224 and 225 equal and opposite to the fluid pressure force caused by the high pressure ones of the ports 232 and 233.

The rings 260 and 262 have suflicient clearance with respect to their associated grooves that fluid is permitted to leaw therepast when the associated annular passage is under pressure, pressurizing the right side of one of the associated O-

rings

272, 273 which in turn urges one of the

rings

268 or 269 into engagement with the end cap 19 thereby serving by reaction to urge the entire pressure plate 244 towards the

gears

224 and 225. The O-rings seal the grooves to prevent any leakage therefrom and also to prevent leakage between the grooves themselves.

In FIG. 6 a somewhat modified form of the pressure balancing plat is shown and the primed reference numerals are used to indicate parts having a similar configuration from that in the FIG. embodiment. The basic diiference in this embodiment is that a single resilient ring 280 replaces the O-rings in the FIG. 5 embodiment and a single annular washer 282 replaces the

separate rings

268 and 269. Formed in the rear surface of the pressure plate 244 is a single annular groove 285 communicating with annular grooves 286 and 287 receiving the rings 2'60 and 262 respectively. The grooves 286 and 287 form an annular projection 290 on the pressure plate 244' which engages and deforms the ring 280 to provide a seal between the grooves 286 and 287 thereby isolating the annular passage 264 from annular passage 265'. This embodiment works in a similar manner to the FIG. 5 embodiment with fluid leaking past the high pressure one of the rings 26.0 and 261" serving to urge the sealing member 280 against ring 282 which in turn forces ring 282 in engagement with the end cap 219' thereby urging the entire pressure plate 244' to the left into engagement withthe hydraulic unit gears (not shown in FIG. 6). With one of the grooves 286 or 287 being under high pressure the resilient member 280 will bulge toward the other one of the grooves and engage the ring 260', 262 received therein so that these rings additionally serve to prevent the resil ient member 280 from engaging the passages interconnecting the grooves with the apertures 257', 260a.

I claim:

1. A fluid energy translating device, comprising: an

outer member having a chamber therein, an internally toothed gear member in said chamber, said chamber and internally toothed member having cooperating surfaces permitting orbital movement of said toothed member within said chamber, an externally toothed gear member rotatably mounted on an axis fixed with respect to said outer member with teeth operatively engaging the teeth on the internally toothed member, said teeth defining expanding and contracting fluid chambers as the internally toothed member orbits and the externally toothed member rotates about its own axis, valve means for porting fluid to and from the fluid chambers including inlet port means and outlet port means, a valve plate sealingly engaging one side of said toothed members, a plurality of ports in said plate generally annularly arrayed about the axis of the externally toothed member, said ports being equal to a number evenly divisible by the number of teeth on the internally toothed gear member, said ports being disposed on a diameter greater than the diameter of the teeth crests of the internally toothed member and cooperable with the orbiting internally toothed member to effect communication with said chambers, and means connecting said ports with at least one of said port means.

2. A fluid energy translating device as defined in claim 1, wherein said ports are positioned to be opened and closed by the teeth on the internally toothed member.

3. A fluid energy translating device as defined in claim 2, wherein each of said ports is positioned to be opened and closed by only one of said teeth on the internally toothed member.

4. A fluid energy translating device as defined in claim 1, wherein each of said ports serially communicates with each of said chambers.

5. A fluid energy translating device, comprising: an outer member having a chamber therein, an internally toothed gear member in said chamber, said chamber and internally toothed member having cooperating surfaces permitting orbital movement of said toothed member with in said chamber, an externally toothed gear member rotatably mounted on an axis fixed with respect to said outer member with teeth operatively engaging the teeth on the internally toothed member, said teeth defining expanding and contracting fluid chambers as the internall toothed member orbits and the externally toothed member rotates about its own axis, and valve means for porting fluid to and from the fluid chambers including inlet port means and outlet port means, a valve plate sealingly engaging one side of said toothed members, a plurality of ports in said plate generally annularly arrayed about the axis of the externally toothed member, said ports being disposed on a diameter greater than the diameter of the teeth crests of the internally toothed member to effect communication with said chambers, means connecting said ports with at least one of said port means, said ports lying on a circle greater in diameter than the root diameter of the teeth on said internally toothed member, and a plurality of slots in the side of internally toothed member adjacent said valve plate and communicating with said chambers, said slots extending radially a sulficient distance to serially communicate with said ports.

6. A fluid energy translating device, comprising: an outer member having a chamber therein, an internally toothed gear member in said chamber, said chamber and internally toothed member having cooperating surfaces permitting orbital movement of said toothed member Within said chamber, an externally toothed gear member rotatably mounted on an axis fixed with respect to said outer member with teeth operatively engaging the teeth on the internally toothed member, said teeth defining expanding and contracting fluid chambers as the internally toothed member orbits and the externally toothed member rotates about its own axis, and valve means for porting fluid to and from the fluid chambers including inlet port means and outlet port means, a valve plate sealingly engaging one side of said toothed members, a plurality of ports in said plate generally annularly arrayed about the axis of the externally toothed member, said ports being disposed on a diameter greater than the diameter of the teeth crests of the internally toothed member and cooperable with the orbiting internally toothed member to effect communication with said chambers, means connecting said ports with at least one of said port means, a casing surrounding toothed members, said chamber being generally cylindrical and defined in said casing, an output shaft rotatably mounted in said casing and rotatably fixed to said externally toothed member, said inlet and outlet port means including an inlet port. and an outlet port in said casing, said valve plate ports being equal in number to twice the number of teeth on saidinternally toothed member, means connecting alternate ones of said valve plate ports to said inlet port, and means connecting the other valve plate ports to said outlet port.

7. A fluid energy translating device, comprising: an outer member having a chamber therein, an internally toothed gear member in said chamber, said chamber and internally toothed member having cooperating surfaces permitting orbital movement of said toothed member within said chamber, an externally toothed gear member rotatably mounted on an axis fixed with respect to said outer member with teeth operatively engaging the teeth on the internally toothed member, said teeth defining expanding and contracting fluid chambers as the internally toothed member orbits and the externally toothed member rotates about its own axis, and valve means for porting fluid to and from the fluid chambers including inlet port means and outlet port means, a valve plate sealingly engaging one side of said toothed members, a plurality of ports in said plate generally annularly about the axis of the externally toothed member, said ports being disposed on a diameter greater than the diameter of theteeth crests of the internally toothed member and cooperable with the orbiting internally toothed member to effect communication with said chambers, means connecting said ports with at least one of said ports means, a casing surrounding toothed members, said chamber be ing generally cylindrical and defined in said casing, an output shaft rotatably mounted in said casing and rotatably fixed to said externally toothed member, said inlet and outlet port means including an inlet port and an outlet port in said casing, said valve plate ports being equal in number to twice the number of teeth on said internally toothed member, means connecting alternate ones of said valve plate ports to said inlet port, means connecting the other valve plate ports to said outlet port, and the number of teeth on said externally toothed member being one less than the number of teeth on the interr'ially toothed member.

8. A fluid energy translating device as defined in claim 1, wherein the cooperating surfaces include internal teeth in said chamber, and an equal number of external teeth on said internally toothed member in operational engagement therewith.

9 A fluid energy translating device as defined in claim 1, including a casing surrounding said toothed members, a pressure balanced sealing plate in said casing on the other side of said toothed members, restricted passage means in said pressure plate communicating said chambers with the side of said pressure plate opposite said toothed members.

10. A fluid energy translating device, comprising: an outer member having a chamber therein, an internally toothed gear member in said chamber, said chamber and internally toothed member having cooperating surfaces permitting orbital movement of said toothed member within said chamber, an externally toothed gear member rotatably mounted on an axis fixed with respect to said outer member with teeth operatively engaging the teeth on the internally toothed member, said teeth defining expanding and contracting fluid chambers as the internally toothed member orbits and the externally toothed member rotates about its own axis, and valve means for porting fluid to and from the fluid chambers including inlet port means and outlet port means, a valve plate sealingly engaging one side of said toothed members, a plurality of ports in said plate generally annularly arrayed about the axis of the externally toothed member, said ports being disposed on a diameter greater than the diameter of the teeth crests of the internally toothed member and cooperable with the orbiting internally toothed member of effect communication with said chambers, means connecting said ports with at least one of said port means, a casing surrounding said toothed members, a pressure balanced sealing plate in said casing on the other side of said toothed members, restricted passage means in said pressure plate communicating said chambers with the side of said pressure plate opposite said toothed members, and said pressure plate passages including a plurality of annular recesses in the side of the pressure plate opposite said toothed members for receiving fluid and hydraulically urging the pressure plate into sealing engagem'ent with the sides of said toothed members.

11. A fluid energy translating device, comprising: an outer member having a generally cylindrical chamber therein, said chamber having internally formed teeth thereon, an intermediate member having external teeth sealingly engaging the internal teeth, and being disposed eccentrically in said chamber, said intermediate member having a lesser number of teeth than said chamber and being adapted for orbital movement therein and rotational movement whereby a plurality of expanding and contracting fluid chambers are defined between said members as the intermediate member orbits, said intermediate member having internal teeth, an inner member mounted for rotation about an axis fixed with respect to said chamher, said inner member having external teeth sealingly engaging the internal teeth on the intermediate member and defining therewith a second plurality of expanding and contracting fluid chambers, valve means for porting fluid to and from said first plurality of fluid chambers, and valve means for porting fluid to and from said second plurality of fluid chambers.

12. A fluid energy translating device as defined in claim 11, wherein said valve means includes a valve plate adjacent said members, a plurality of ports in said valve plate for delivering fluid to and from said first and second plurality of fluid chambers.

13. A fluid energy translating device as defined in claim 12, wherein said plate ports are in general annular array on diameter greater than the root diameter of the internal teeth on the intermediate member and lesser than the crest diameter of the external teeth on said intermediate member, a plurality of radially extending slots in said intermediate member communicating with said first plurality of fluid chambers, and a second plurality of radially extending slots in said intermediate member communicating with said second plurality of fluid chambers, said radial slots each extending across the circle defining the plate ports in all positions of said intermediate member whereby the ports serially communicate with said fluid chambers, said valve means including inlet port means and outlet port means, means connecting the inlet port means to alternate ones of said plate ports, and

means connecting the outlet port means to the other plate ports.

14. A fluid energy translating device as defined in claim 13, wherein said ports being equal in number to twice the number of external teeth on said intermediate member, said first plurality of slots being equal in number to the number of external teeth on the intermediate member, said second plurality of slots being equal in number to the number of internal teeth on the intermediate member.

15. A hydraulic unit, comprising: drive shaft means, rotatable means connected with said drive shaft and defining expanding and contracting fluid pressure chambers as the drive shaft means rotates, a valve plate at one 11 end of said rotatable means having a plurality of inlet ports and a plurality of outlet ports therein, said inlet and outlet ports being alternately spaced, a pressure balancing plate at the end of the rotatable means opposite said valve plate, said pressure plate having a plurality of apertures therein corresponding in number to the number of ports in said valve plate and being substantially aligned therewith, housing means engaging said pressure plate on the side thereof opposite said rotatable means, first and second annular grooves in said pressure plate opening the side of the pressure plate adjacent the housing means, passage means communicating alternate ones of said apertures to said first anular groove, passage means communicating the other alternate ones of said apertures to said second annular groove, a member in each of said grooves defining an annular passage, and annular means adjacent said grooves and engaging said housing means,.

said member being sized to permit leakage therepast to said annular means biasing the annular means against the housing means and the pressure plate against the rotatable means.

16. The combination as defined in claim 15 wherein said annular means includes a rigid annular ring in each of said grooves.

.12 l 17.. The combination the annular means includes a resilient ring in each or said grooves between said member and said rigid annular rlng. I

18. Theflcombination as defined in claim 15 wherein said annular means includes a single rigid ring overlying both of said grooves.

19. The combination as defined in claim 18 wherein v said annular means includes a single annular resilient ring 10 overlyingboth of said groves and positioned between said rigid ring and said members, said resilient ring sealing said first groove from said second groove.

References Cited 3,215,043 11/1965 Huber 91-56 LEONARD H. GERIN, Primary Examiner as'defined in claim 16 wherein