Rotary gerotor hydraulic device with fluid control passageways through the rotor

A rotary fluid pressure device is disclosed comprising a housing having fluid inlet and outlet means and enclosing a gerotor having an internally toothed member and a coacting externally toothed member having a less number of teeth than the internally toothed member and having its axis positioned eccentrically relative to the axis of the internally toothed member. A wobble stick in the housing has a first end connected to the axial drive shaft and a second end connected to the gerotor member having the orbital movement. The housing has one set of passageways communicating at all times with the expanding and contracting gerotor cells. The gerotor member having orbital movement is, in addition to its usual function, a valve with two travel passageways, one travel passageway extending straight through the rotor and coaxially surrounding the other travel passageway. These two travel passageways communicate at all times part of the set of passageways in the housing with only one fluid inlet or outlet while communicating other of this same set of passageways with the other fluid inlet and outlet.

An object of this invention is to provide a rotary fluid pressure device 
including a gerotor having a fixed stator inside of which is an orbiting 
and rotating rotor. The rotation of the orbiting rotor member provides the 
output or input at the shaft member. This rotor has a continuous ring 
valve on one side and both of the supplies of intake and exhaust pressure 
fluid are on the opposite side. The second embodiment shows again a fixed 
stator with an orbiting rotor with the rotating component of the rotor 
used at the output shaft; but in this embodiment the intake is on the 
internal diameter of one side of the rotor member with balanced area 
grooves in communication with the first named intake and exhaust grooves 
on the oppposite side of the rotor so as to provide a hydraulically 
balanced rotor. 
An added object of this invention is to provide a pressure loaded 
commutator ring urged with a wave spring for initial contact, together 
with a drive pin connected between the rotor and the commutator ring. 
Another object of the invention is to provide a pressure loading plate in 
the end cover of the housing so as to cause a pressure balance providing a 
head force towards the manifold and gerotor set. 
The present invention reduces the number of manufacturing operations 
necessary to make hydraulic pressure devices. The devices made in accord 
with this invention are simple, reliable and efficient. 
Another object of this invention is to provide a hydraulically balanced 
rotor. 
Still another object is to reduce the wear of and cool the wobble stick 
drive connections. 
Other objects and advantages of the present invention will be apparent from 
the accompanying drawings and the description. The essential features will 
be set forth in the appended claims.

DESCRIPTION OF PREFERRED EMBODIMENT 
Those familiar with this type of apparatus will understand that while the 
present invention is being described as a pump using a fluid inlet and a 
fluid outlet, nevertheless, the same structure may be used as a motor by 
merely reversing the fluid inlet and outlet so that the high pressure 
fluid now enters at what was previously the inlet and the device operates 
as a motor. 
In the description and claims occurring hereinafter, the term "housing" is 
used to include not only the main housing member but also the pressure 
plate, gerotor set, manifold and end cap, all of these latter parts being 
connected to the main housing portion by bolts. 
Referring now to FIG. 1, the first embodiment of this invention comprises a 
main housing unit 20 having a radially flat inner end to which is 
respectively attached a wear plate 21, a gerotor set 22, a manifold 23 and 
an end cap 24, all of these being secured together by bolts 25, which are 
shown in the various sectional views but omitted from FIG. 1, but those 
skilled in this art will recognize that the bolts have heads pressing 
against the outer righthand end of the end cap 24 and extending through 
the members 21, 22 and 23 and threaded tightly into the main housing 
portion 20. Sealing rings 26 seal all of the members against leakage 
between them. 
The gerotor set 22, best seen in FIGS. 1 and 4, comprises an internal 
toothed member 27 which is a stator inside of which a coacting externally 
toothed member 28, a rotor which rotates about its own axis A is seen in 
FIG. 4, but which is eccentric relative to the center of the stator 27 by 
the distance shown between A and B, on the line of eccentricity C, and the 
rotor orbits about the center B. During this movement of the rotor and 
stator a series of cells 29 and 29a from a series of cells of constantly 
changing size between the rotor and stator, the size of the cells becoming 
greater on one side of the line of eccentricity, and the cell size 
becoming smaller on the opposite side. In FIG. 4 the minimum size cell at 
29a approaches zero. The rotor rotates in the direction of the arrow shown 
in FIG. 4. The rotor has two flat axial end surfaces. 
The inlet means to the housing is indicated at 30. The fluid outlet means 
is shown at 31. The inlet means is connected by means indicated only in 
dot-dash lines through a continuous annulus or distribution channel 32 in 
the main housing portion 20. This annulus opens through the wear plate 21 
which has a number of through openings or fluid travelway 33 the number of 
which is not important, but sufficient to take care of the flow of fluid 
necessary. These openings 33 are connected by connecting passages 33a to 
an annulus or annular ring transfer channel 34 of smaller diameter on the 
opposite face of the wear plate and opening into the rotor cavity toward 
the gerotor 22. 
The internal teeth 27a on the stator 27 are provided by cylinders 27a 
inserted in recesses 27b over 180.degree. in circumference so as to 
maintain the cylinders 27a in the positions shown in FIG. 4. It will be 
understood that the cylinders 27a terminate at the level of the opposite 
faces of the stator 27. The rotor 28 has external teeth which are formed 
to fit almost exactly between the internal teeth of the stator, as shown 
in FIG. 4. The rotor 28 has an open center 35 surrounded by a sealing 
strip 36 which is uninterrupted circumferentially and laterally outside of 
which is an annular liquid intake passageway 37. The axis of rotation for 
the wobble stick 38 is marked A in FIG. 4. The axis of rotation for the 
orbiting movement of the wobble stick 38 relative to the stator is 
indicated at B in FIG. 4. The line C passing through A and B is herein 
indicated as the line of eccentricity. The movement of the rotor herein 
described is as indicated by the arrow D in FIG. 4. During this rotation 
the cells 29 on the lefthand side of the line of eccentricity increase in 
size gradually while the cells 29 on the righthand side of the line of 
eccentricity gradually decrease in size as indicated in FIG. 4. The rotor 
functions as the main valve for the device. Six travel passageways or 
holes 37a are evenly spaced around the annulus 37 extending linearly 
through the rotor parallel to the axis of the rotor. These project 
radially inwardly from the annulus or annular channels 37 as seen at 37b, 
in one embodiment this being about 1/8 of an inch projection. The other 
travel passageway is generally on the central axis of the rotor, in the 
structure disclosed around the wobble stick-rotor device connection. There 
are sufficient openings in this type of drive connection that fluid flow 
is relatively unimpeded by the spline-gear interfaces. The transfer 
channel 34 communicates with the annular channel as the device is 
operated. 
A manifold 23 connects the rotor valve with the gerotor cells. The manifold 
23 will be best shown in FIGS. 5, 5A, and 6. Seven parallel through 
openings extend through rotor facing surface of the manifold 23 parallel 
to its axis. This set of openings, as best seen in FIGS. 5 and 6, have a 
peculiar cross section. These openings 40 will be herein described as 
"double-trapezoidal". Referring to FIG. 5, it will be seen that one of 
these openings appears substantially like two trapezoids facing each other 
with no middle partition and having opposite ends which are not quite 
parallel but instead are radial. The radially inner side of each opening 
is composed, not of straight lines, but of lines slightly concave inwardly 
meeting in a slight peak at the center 40a. The outer wall of this opening 
radially, as seen in FIG. 5, may be composed of two straight lines meeting 
in the center or preferably a single line slightly convex radially 
outwardly. The size of each of these openings is such as to fit in the 
opening, seen in FIG. 4, between two of the cylindrical openings 37a in a 
circumferential direction and between the central opening and the annulus 
37 in a radial direction. These openings 40 are swept by the travel 
passageways in the rotor as the device is operated. This performs the 
primary valving function of the device. Each of the openings 41, as seen 
in FIGS. 5 and 6, of which there are seven evenly spaced, on the side of 
the manifold toward the gerotor are connected by fluid passageways 41a 
sloping inwardly and downwardly to one of the openings 40 just described. 
The manifold 23, as seen in FIG. 6, shows seven inclined passageways 41a in 
broken lines which coact with the structure described in connection with 
the openings 41 and openings 40 as previously described. These coacting 
passageways are shown in broken lines in FIG. 6 to show the cooperation. 
Seven of such passages 41a are provided extending part way through the 
manifold from side to side. These are at a slight angle to the axis of the 
gerotor and are spaced at a diameter to register, as shown in FIGS. 5 and 
6. 
The elongated rigid wobble stick 38 is clearly seen in FIG. 1 and shown in 
section in FIGS. 2 and 3. One end of the wobble stick has a spline 
connection 44b with the drive shaft 44. It will be noted that this shaft 
has a solid outer end and a hollow inner end as indicated at 44a. The 
opposite end of the wobble stick has a spline connection 44c in a central 
bore in the rotor 28. These spline connections are provided in such a 
manner that the wobble stick may rotate and orbit around the center axes 
A, B, and that fluid can continuously flow over and around them. The 
exhaust passageway includes the open center 35 of the rotor over and 
around the wobble stick-rotor drive connection and the open center 21a of 
the wear plate and the hollow 44a, and is completed by four radial 
passageways 45 and 46 which are connected, as shown in dot-dash lines, 
with the outlet 31. 
Suitable needle bearings are shown at 47 and 48 supporting the drive shaft 
44 in the main housing portion 20. Also suitable sealing means as shown at 
49 and 50 are provided where the drive shaft passes out of the main 
housing portion 20. 
This embodiment has been described as a pump utilizing the drive shaft 44 
for the attachment of power which would cause intake of lower pressure 
fluid at 30 and exhaust of higher pressure fluid at 31. As previously 
explained, reversing the connections 30 and 31 will cause the device to 
operate as a motor producing power on the drive shaft 44. 
The operation of the first embodiment as a pump will now be described. 
Power is supplied to the protruding left end of the drive shaft 44 as seen 
in FIG. 1. This rotates the shaft, the wobble stick 38, the rotor 28, and 
also causes the rotor to orbit about the stator 27. This causes the cells 
29 to the left of the line of eccentricity C to gradually increase in size 
causing a suction at the intake 30. The cells 29 on the righthand side of 
the line of eccentricity C in FIG. 4 are also caused to progressively 
decrease in size thus causing the fluid under increased pressure to 
exhaust at the outlet 31. The incoming fluid from intake 30 passes through 
the annular channel 32, the passageways 33a to the annular channel 34, 
then through the rotor 28 through the annular channels 37 and the 
cylindrical holes 37a, then through the double trapezoidal openings 40 in 
the manifold 23, then through the passageways 41a and 42 in the manifold 
and through the openings 41 in the manifold and rotor and thus into the 
expanding cells 29. Other cells 29 are exhausted back through other 
openings 41 and other passsageways 42 and 41a and other double trapezoidal 
openings 40 in the manifold into the open center 35 of the rotor. The 
fluid then flows over and around clearances in the wobble stick-rotor 
drive connection, cooling and lubricating it, through the opening 21a, 
through the hollow portion 44a of the shaft and through openings 45 and 46 
and thus out through the outlet 31. 
The second embodiment of this invention is shown in FIGS. 8, 9, 10 and 11. 
FIG. 8 is a central sectional view through the second embodiment with the 
bearings and seals resembling those seen in FIG. 1 omitted for 
simplication of the drawings. 
The main housing portion 60 has secured to it a wear plate 61, a gerotor 
set 62, a manifold 63, and an end cap 64, all secured rigidly together by 
a plurality of bolts 65 extending from the righthand end of the device as 
seen in FIG. 8 into threads in the main housing portion 60. The main 
housing portion has an air intake 66 connected by a passage 67 through the 
housing portion 60 with a continuous annulus chamber 68, which 
communicates with a plurality of radial openings 69 which lead inwardly to 
a hollow portion 70a of a drive shaft 70 which is rotatably mounted in the 
housing portion 60. An elongated rigid wobble stick 71 has a spline 
connection 71a at one end with the drive shaft 70 and another spline 
connection 71b at the opposite end with the rotor member of the gerotor 
set 62. The spline connections 71a and 71b are so shaped as to permit the 
rotation of the wobble stick while at the same time permitting it to 
follow the orbiting movement of the rotor in the stator as will presently 
appear. 
The wear plate 61 has a circular opening 61a which permits the necessary 
movement of the wobble stick 71 and at the same time forms part of the 
intake passageway for fluid. 
Six pairs of intake passageways 82 and 83 extending through the rotor 72 
connecting the circular opening 61a in the wear plate 61 with the annular 
passageway 84. The annular passageway 84 opens towards the manifold 63. 
The gerotor 62 is best seen in FIG. 9. It comprises a stator 62a which has 
a plurality of internally extending teeth formed partly by direct 
formation in the stator but also in part by six cylindrical members 62b 
which are firmly held in recesses 62c which extend for a distance greater 
than the diameter of each of the cylinders 62b so that they are held 
firmly in the position shown in FIG. 9. A rotor 72 is shown having a 
plurality of externally extending teeth 72a which are shaped to fittingly 
coact with the internally extending teeth 62, 62a and 62b, these external 
teeth being one less in number than the internal teeth previously 
described. The rotor has an axis E which is eccentric relative to the axis 
F of the stator and the line G passing through points E and F is herein 
designated as the line of eccentricity. The rotor is provided with a 
generally annular ring 73 forming part of the intake passageway for fluid. 
This passageway is concentric around the axis E. Inside the annular ring 
73 is a circular opening 74, also concentric, for the exhaust of fluid 
from the rotary fluid pressure device. 
Referring now to FIGS. 9, 10 and 11, FIG. 11 shows the face of the manifold 
toward the gerotor structure 62. Centrally there is the exhaust opening 75 
which communicates with the exhaust opening 74. In the next circle, and 
concentric, are seven rotor communicating openings 76, and in an outer 
concentric circle are seven passageway openings 77 so positioned that they 
cooperate circumferentially with the cells 80 which are formed in changing 
fashion between the rotor and the stator as seen in FIG. 9. 
FIG. 10 shows the face of the manifold 63 toward the end cap 64. This shows 
the through passageways 76 each connected to one of the openings 77 by 
means of angular passageways 78 and 79, each pair of which joins at an 
opening 79a. 
The cooperation of these parts is shown in dot-dash lines in FIG. 9 at 81. 
This shows one of the openings 77 in position to cooperate with a cell 80a 
at the top of FIG. 9 and it is in cooperation through passageways 78 and 
79, here shown diagrammatically, with one of the openings 76, which you 
might say is about two and one-half positions away going around the 
circle. It will now be seen how the radially outward openings 84a in the 
annular ring 84 cooperate with the communicating passageways 76. There are 
six of the formations 84a and each comprises a central, radially outermost 
portion 84b which extends substantially circumferentially and at each end 
of this outermost portion is a radially and circumferentially inwardly 
sloping portion 84c which extends to a radially innermost separating 
portion 84d. Each of the passageways 76 is herein described as double 
trapezoidal in section inasmuch as the opposite halves of the section are 
approximately trapezoid with their wider edges opening toward each other 
in the center. It will now be seen in FIG. 9. that when the dead pocket 
80a at the top of FIG. 9 is in communication with its associated opening 
77, then the other end of the connection through the 78, 79 connection and 
shown at 76 in dot-dash lines will illustrate how the exhaust pocket 
related to cell 80a is shut off before the fluid is transferred from the 
associated intake pocket 76. This gives the dead center pocket a higher 
pressure than the supply at 66 because the fluid is trapped at that 
particular moment. This higher pressure causes the rotor 72 to seal better 
against the cylindrical members 62b on the opposite side of the axis. This 
higher pressure in cell 80a also provides oil to the pivot roll near the 
upper dead center in FIG. 9 whereby the rotor floats on a hydrodynamic oil 
film thus giving a higher mechanical efficiency output. It will now be 
seen that the shape of each of the portions 84a of the annular ring 84 
match fairly well with the radially outer edges of the double trapezoidal 
passageways 76. 
A balancing ring 86 is on the opposite side of the rotor from the annular 
ring 84. Small passages 87 through the rotor connect the balancing ring 86 
to the opening 74. The balancing ring 86 equalizes the hydraulic pressure 
on the rotor 72. 
It should now be apparent how the operation of this device as shown in 
FIGS. 8-11 operates. Power is applied to the shaft 70 causing the rotor 72 
to rotate in the stator 62a in the direction of the arrow shown in FIG. 9. 
The intake flow is from the inlet 66 through passageways 67 and 68, then 
through the hollow shaft portion 70a and through the central opening 61a 
in the wear plate. Then the flow is through passageways 82 and 83 to the 
annular passageway 84 which opens toward the manifold 63. Then the flow 
passes through an opening to passageway 76 on one side of the eccentricity 
line G through the manifold passages 78, 79 to one of the openings 77 
which is in communication with one of the cells 80 between the rotor and 
stator. Meanwhile, one of the cells 80 on the other side of the 
eccentricity line G communicates back to the appropriate passageway 76 and 
back through the manifold 63 to the exhaust passageways 74, 75 and 85 to 
exhaust. 
FIG. 12 shows a portion of the righthand end of FIG. 1 where the same parts 
are given the same reference numbers. Otherwise, the device operates as 
described in connection with FIG. 1. However, in FIG. 12 there has been 
added a pressure plate 90 inserted in a suitable recess in the end cap 
240, and the end cap is pushed toward the left as viewed in FIG. 12 by 
means of pressure admitted through lines 91, connected with the exhaust 
45, and line 92 connected with the intake 30. Each of the lines 91 and 92 
has adjacent the pressure loading plate 90 a ball check valve 93 so that 
the loading plate 90 is always pressed inwardly toward the manifold 23 and 
the gerotor set 22 beyond it. This provides a head force towards the 
manifold and rotor set. This will take care of any wear between the 
engaging rubbing portions 22 and 23. 
FIG. 13 also shows a portion of the righthand end of FIG. 1 and all of the 
same parts are given the same reference characters. The added feature here 
is a pressure loaded commutator ring 95 which extends inwardly, toward the 
left in FIG. 13, against a shoulder 96 with a wave spring 97 circular in 
shape and pressed between the commutator ring and the shoulder 96 to give 
an inicial pressure. The wave spring is made of spring metal which weaves 
back and forth from a generally common plane as one goes around the 
circle. A seal 98 prevents leakage between the parts. There is provided a 
pin connection 99 which as seen in FIG. 13 is in general an axial 
extension of the splines 440b connecting the wobble stick 380 and the 
rotor of the gerotor set 22. This pin fits between the splines 440b and 
extends into a suitable opening 99a in a portion of the commutator ring. 
This pin connection is somewhat loose so as to use the rotational 
component of the rotor as a means of timing the opening and closing of the 
connection indicated in dot-dash lines in FIG. 9. 
Although this invention has been described in its preferred form with a 
certain degree of particularity, it is to be understood that the present 
disclosure of the preferred form has been made only by way of example and 
that numerous changes in the details and in the combination and 
arrangement of parts may be made without departing from the spirit and the 
scope of the invention as hereinafter claimed.