High displacement-to-size ratio rotary fluid mechanism

A positive displacement fluid moving mechanism having internal construction features which allow it to possess a very high ratio of fluid displaced per unit rotation in relation to the volume of the displacing mechanism, whereas, this feature allows increased performance due to less energy required to operate the unit because of its reduced size and internal friction.

BACKGROUND OF THE INVENTION 
The present invention relates to fluid moving mechanisms and more 
specifically to a rotary fluid mechanism possessing a very high displaced 
volume to size ratio i.e., the displaced fluid per revolution is large 
compared to the volume of the mechanism which moves this fluid. The object 
of a high displacement-to-size ratio fluid mechanism is to obtain less 
mechanism friction in order to reduce either the power consumption to 
drive this mechanism as a fluid pump, or to reduce the fluid energy 
required to operate the device as a fluid motor or meter. 
The common prior art positive displacement fluid mechanisms possess 
relatively higher internal friction or resistance to flow and larger size 
and weight for equivalent displacement and higher noise levels as 
represented by the vane, piston, and gear types of fluid mechanisms. 
For example, rotary vane fluid mechanisms most commonly consist of a rotor 
with sliding vanes mounted eccentrically in a circular or elliptical 
chamber. To keep leakage to an acceptable value the vanes must provide a 
contact seal to a cam ring introducing friction forces and wear 
proportional to the number of vanes, the vane sealing surface and size of 
the cam ring. Typically vane mechanisms exhibit high vane friction and 
leakage, low efficiency, and require a substantial pressure differential 
to operate which produces a lateral force on the rotor that is transmitted 
to the associated shaft and bearings. The vane mechanism has a poor 
displacement-to-size ratio as compared to the present invention. The 
aforementioned properties are true for both the fixed and 
variable-displacement vane type mechanism. 
The piston type mechanism can be classified by the basic relationship 
between the piston and the piston barrel. The axial-piston version, have 
pistons that lay approximately along the axis of the barrel, whereas, in 
the radial-piston mechanisms, the pistons radiate outward from the 
barrels. The axial piston requires the complexity of an angled cam (or 
wobble) plate or the use of the bentaxis principle and usually require 
some type of check valve. 
The radial-piston version requires a rotating cam that runs through the 
center of the mechanism imparting reciprocating motion to the pistons. 
Check valve complexity is also usually required in this configuration. 
These basic piston mechanisms and many variations all require piston seals 
to reduce leakage, have a relatively high resistance to mechanical motion 
and have higher pressure drops when compared with the present invention. 
Energy loss due to the normal cyclic motion is also encountered with 
piston mechanisms and many cylinders are required for smooth operation. 
The major disadvantages of the piston mechanisms are the large size, 
complexity, and higher friction required for performance equal to that of 
the present invention. 
Gear type mechanisms have numerous configurations including gear-on-gear, 
three-gear, gear-within gear, and screw gear mechanisms and in general, 
are fixed displacement devices having high bearing loads, high friction 
and require heavier bearings, housings and shafts as compared to the 
present invention. Leakage of fluid that can be forced past internal seals 
between inlet and outlet ports is also very high for the gear type 
mechanisms. To reduce leakage at the gear interface, high contact forces 
and high precision are required resulting in increased size, weight and 
basic resistance of the mechanism. These mechanisms usually exhibit a low 
displacement-to-size ratio and are generally low pressure devices, have 
low mechanical efficiency and are noisy in operation. 
Another version somewhat similar in characteristics to the gear mechanism 
is the lobed-rotor mechanism. This mechanism consists of two rotating 
elements that revolve in opposite directions in a chamber. The rotors 
usually do not touch and, therefore, have a very high fluid leakage. 
Other prior art in rotary mechanisms similar to the invention do not offer 
the advantage of simple construction, novel porting between rotating 
chambers and a high displacement-to-size ratio with low mechanical 
resistance. In general all the prior art in positive displacement 
mechanisms require larger mechanisms with greater resistance to mechanical 
motion for the same fluid displacement per shaft revolution. 
SUMMARY OF THE INVENTION 
The fluid mechanism of the present invention features four interconnected 
moving parts which form four separate variable volume chambers. These 
variable volume chambers are interconnected together by proper porting 
means so that two of the chambers are always in communication together and 
are expanding in volume, and the other two chambers are always 
communicating together and are contracting in volume. As the mechanism 
rotates these chambers will continuously switch communications with each 
other so as to maintain the two chambers expanding and two chambers 
contracting relationship. This basic mechanism operates similar to 
mechanisms covered in Class 417 Subclass 463. 
This invention possesses certain very desirable refinements which allows 
the mechanism to be used for low energy related devices. The primary 
objective of this invention is to provide a high fluid 
displacement-to-size ratio which is better than the before mentioned fluid 
moving devices. High displacement-to-size ratio means that the fluid 
displaced volume which passes through the mechanism for each revolution of 
the output shaft is large in comparison to the actual size or volume which 
the mechanism occupies. This is further interpreted as meaning the smaller 
the mechanism which is required to move a given amount of fluid through 
it, the less friction is encountered and the less energy is required for 
the device to function. This feature applies to motor driven pumps as well 
as fluid operated motors or meter mechanisms. 
This mechanism features construction techniques which allows a high 
displacement-to-size ratio and yet is economical to manufacture. One 
construction technique is accomplished by using a compact two piece rotary 
housing. By using two separate but identical rotary housing parts, an 
interconnecting or crossover member is eliminated which allows the rotary 
chamber member which slides between the two rotary housing members to 
possess a maximum stroke thus giving improved displacement volume in 
comparison to the mechanism volume. 
Accordingly it is one objective of the present invention to provide a 
mechanism improvement which allows reduced energy to operate it as a fluid 
motor, meter or pump. 
A further improvement to the two piece rotary housing members is to install 
anti-friction rollers in order to reduce further the moving friction of 
the rotary housing as it rotates inside the stationary fluid mechanism 
block. The combination of a separate rotary chamber with rollers allows 
constant distance roller tracking and no radial fluctuation movement of 
the strip seals. Since the strip seal slots can be orientated at a 
constant fixed distance away from the inside block bore, using separate 
housing members, the seal design can be economically and more simply 
constructed. 
Accordingly it is a still further object of the present invention to 
provide a fluid mechanism which has reduced friction and simpler 
construction to improve its energy input/output features and cost 
advantages through simpler construction. 
A second construction technique which further increases the 
displacement-to-size ratio and reduces the friction is accomplished by 
providing a low friction sliding means for the rotary piston. A bearing 
rod which slides through the center of the rotary piston accomplishes this 
low friction sliding. The rotary piston, therefore, does not make sliding 
contact with the rotary chamber member, but is guided and slides from one 
end of the rotary chamber member to the other by means of a centrally 
located guide rod. This feature allows a higher displacement mechanism 
than possible with conventional sliding contact between the rotary piston 
and rotary chamber member. 
Accordingly, it is a continued object of this invention to provide a rotary 
mechanism with increased displacement-to-size ratio which allows lower 
friction and reduced energy to operate the mechanism. 
Another method by which internal fluid shearing and sliding contact 
friction can be reduced is incorporated into this fluid mechanism by 
relieving the side walls in certain areas on the top (input) side and 
bottom (output) side. Relieving these wall areas significantly reduces the 
friction of the outer sliding members (where the friction is normally the 
highest) and thus reduces the overall energy input/output requirements of 
the mechanism. The sidewall relief is provided in an area where the 
input/output porting functions never communicate together in turn 
eliminating the tendency to short circuit the fluid through the unit. 
Additional fluid input/output port area is also provided by incorporating 
the fluid ports as part of these relieved areas. 
Another benefit derived from incorporating the fluid input/output ports 
into the relieved side plate areas is that the mechanism can be further 
compacted in size and can result in additional simplicity and reduced 
cost. 
Accordingly, it is yet another object of the present invention to provide a 
further reduction in internal friction and complexity in order to reduce 
the energy requirements and also reduce the production cost.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention relates to low friction fluid mechanisms which 
operate as either a pump, fluid motor or fluid meter (fluid flow measuring 
mechanism). This invention specifically relates to self starting or 
constant flow fluid mechanisms which have a displacement volume to 
mechanism volume ratio of 0.7 and greater. This ratio being a measure of 
the fluid displaced through the mechanism per one cycle of the mechanism 
to the volume of the mechanism which displaces the fluid. The described 
rotary mechanism is a type similar to those in Class 417 Subclass 463, but 
which possesses several very desirable improvements which allow the 
mechanism to operate with significantly reduced friction which 
proportionally reduces the energy required for applications involving a 
low leakage positive displacement fluid mechanism. 
In combination with having construction techniques which allow very low 
friction losses through a compact mechanism configuration, further 
reductions in friction are accomplished by relieving all noncritical 
sealing areas on the end plates. These features are now further described 
in detail to illustrate the overall energy savings possible by utilizing 
these features. 
All present art classified in Class 417 Subclass 463 consist of a 
relatively reciprocating piston in which this piston has a second pumping 
chamber formed integral within which also contributes to the overall 
pumping ability of the mechanism. 
FIG. 1 illustrates how the invention is configured with one side plate 
removed. Notice how the first construction technique of this invention 
accomplishes maximum displacement volume by allowing the outer rotating 
pumping chamber to be made up of two independent (identical) parts 1 and 
2. These separate parts contain rollers, denoted by 3 and 4 which allow 
these separate pieces to track around the inside of the circular housing 
track. 
FIG. 2 illustrates the rotating outer pumping chamber parts 1 and 2 
surrounding the inner pumping chamber 6. These figures illustrate there 
are no mechanical connecting arms which fix these two parts together. All 
prior art illustrates the outer rotating chamber as one piece construction 
whereby the configuration must be larger in diameter, width or both. 
FIG. 3 illustrates the larger size and corresponding smaller 
displacement-to-size ratio of a typical prior art fluid mechanism in which 
the rotating outer chamber member is of one piece construction with a 
connecting plate located on one side of the rotating chamber member. 
FIG. 4 illustrates another common method of attachment in which the 
rotating chamber member is joined around the outer circumference. 
The construction techniques illustrated in FIGS. 3 and 4 require either a 
larger diameter or a wider pumping mechanism construction in order to 
displace the same quantity of fluid per revolution as compared to the two 
piece construction referred to in this invention. Also, these prior art 
construction techniques result in higher operational friction. Higher 
friction is encountered with the double rubbing surfaces associated with 
the side attachment method shown in FIG. 4. 
Other undesirable features of these constructions are the greatly increased 
fluid leakage paths. Double leakage paths are associated with the side 
plate attachment method and increased leakage results from the larger 
diameter and longer sealing distances required when using the 
circumferential attachment method. 
The two piece construction utilized for the present invention also has 
benefits in simplicity of manufacture and is less complex and less costly 
to manufacture. The main construction advantage is derived from not having 
to grind internal sealing surfaces such as required in the one piece 
construction rotating chamber members. It is less involved to manufacture 
a straight flat sealing surface if this surface is not boxed in or located 
as an internal flat machined surface. 
A further object of this invention is to reduce friction by providing 
rollers between matting surfaces which experience cyclic dynamic load 
changes. Also rollers are provided between the inner rotating chamber 
member 6 and the two outer rotating chamber portions 1 and 2. A typical 
roller 7 is shown attached to the inner chamber member 6 of FIG. 2. This 
roller rolls on the flat surface of the outer rotating chamber member 1. 
Enough rollers are provided between 6 and 1 and 2 in order to eliminate 
all sliding contact between these members with the exception of the thin 
low friction strip seals 8. Since the side plates do not experience any 
loading they require only close fitting surfaces in order to accomplish 
optimum sealing for typical medium pressure pump or motoring applications. 
The second construction technique which yields an even higher 
displacement-to-size ratio is provided by allowing the rotary piston 9 of 
FIG. 2 to slide on and be guided by the center slide or piston guide rod 
10. The center rod 10 is rigidly connected to the ends of the inner rotary 
chamber member in apertures such as 23 as shown in FIG. 2. The object of 
the rotary piston 9 sliding on this center rod 10 is to allow the inner 
chamber member to be much wider. This is accomplished since the rotary 
piston can be much narrower at the top because it does not need sliding 
guidance between itself and the inner chamber member. Also since the inner 
rotary chamber member does not have to provide sliding bearing contact 
area for the rotary piston 9, the inner chamber member can be wider and 
arched down on the ends to provide maximum stroke and avoid external 
interference contact with the stationary block or housing 21. The top and 
bottom of the rotary piston 9 never directly contact the top and bottom of 
the inner rotary chamber member 6 because it is positioned and guided back 
and forth by the center guide rod 10. Note that strip seals such as 11 
disposed in slots in the piston 9 do contact the inner rotary chamber 
member to provide proper sealing between the chambers separated by the 
rotary piston. Similar strip seals such as 5 are provided in slots in the 
outer chamber member 1 and 2 for sealing against the cylindrical housing 
interior. 
The prior art mechanisms which do not feature the separate outer chamber 
member and center sliding rod for the rotary piston have a maximum 
displacement-to-size ratio of less than 0.6. This conventional mechanism 
is shown in FIG. 5; as a method of comparison, FIG. 6 illustrates the 
present invention with a two piece outer chamber member and the rod guided 
rotary piston. The present invention as illustrated has a 
displacement-to-size ratio of 0.95. 
FIG. 7 through 10 pictorially illustrate how the component parts of the 
present invention work together as the mechanism rotates through angular 
increments of 45.degree.. Note, the width of the inner chamber member is 
about the same as the height of the rotary piston in order to allow all 
four variable volume chambers to be equal in potential volume. The volume 
occupied by the piston guide rod must be taken into consideration if it is 
desired that all four chambers are exactly equal in volume, for example, 
for metering purposes. 
FIG. 11 and 12 pictorially illustrate how the side or end plates Nos. 13 
and 18 can be ported and provide cut outs such as 14, 15, 19 and 20 in 
order to reduce the sliding friction between the side plates and rotating 
components to a minimum. 
The combination of the friction reducing cut outs, together with the 
input/output conduits 16 and 17, provide a unique means of achieving lower 
friction, together with providing an extremely compact means of inducing 
the fluid into and out of the mechanism. As illustrated in FIGS. 11 and 
12, it is important to provide ribs such as 22 and 24 between the port 
holes in order to contain the strip seals located in the inner and outer 
rotating chamber members. Notice the symmetrical curved rib 25 is for the 
purpose of containing the outer rotating chamber member seals and the 
radial spiraling rib such as 22 provided to contain the inner rotating 
chamber member seal. 
Referring now to FIGS. 1, 2, 11 and 12, the rotary mechanism of the present 
invention may be summarized as including a stationary housing 21 having a 
generally cylindrical interior extending axially along the axis 27 between 
the substantially flat generally parallel end portions which are, of 
course, the visible faces of the end plates 13 and 18 of FIGS. 11 and 12. 
A first chamber means or member comprising the separate individual 
portions 1 and 2 rotates within the housing 21 about the axis 27 with the 
portions of the first chamber means held together to form the chamber 
solely by the housing interior and held apart to form that chamber by a 
second chamber means or member 6. A power transfer axle or shaft 12, which 
is of course concentric with the power transfer axis 29, is fixed within 
the housing and is journaled in the respective end plates in apertures 31 
and 33. Note that the power transfer axis 29 is displaced from the 
cylinder axis 27 . The piston 9 is, therefore, supported within the 
cylinder by the shaft 12 for rotation about the axis 29. A second chamber 
6 reciprocates within and rotates with the first chamber member 1 and 2 
and this second chamber member 6 defines by its interior surfaces such as 
35 a chamber for relative reciprocation of the piston 9 therein. A piston 
guide rod 10 is fixed within the chamber member 6 to slidingly connect the 
piston within the second chamber 6 to support and align the piston 9 
within that chamber member. A first plurality of rollers such as 3 and 4 
support the first chamber member in rolling engagement with the housing 
cylindrical interior and a second plurality of rollers such as 7 supported 
on the second chamber member rollingly engage the interior surfaces such 
as 37 of the first chamber member. A plurality of strip seals for sealing 
against the cylindrical interior are associated with the first and second 
chamber members and the piston and are identified as 5, 8, and 11 
respectively. These strip seals minimize fluid leakage between chambers. 
Chamber sealing is completed against the end plates by surface seal 
material such as 43 on the piston 9 and similar materials on the edges 41 
of chamber member 6 and 45 of the chamber member portions 1 and 2. 
The piston 9 has a pair of opposed working faces such as 39 which in 
conjunction with interior walls such as 35 of the second chamber member 
define a pair of chamber portions 69 and 71 of FIGS. 7, 8, 9 and 10 and 
reciprocation of the piston 9 within the second chamber member expands the 
chamber portion 69 while contracting chamber portion 71 on the one hand, 
and expands chamber portion 71 and contracts chamber portion 69 on the 
other. Similarly, the opposed working faces of the second chamber member 
in conjunction with interior walls such as 37 of the first chamber member 
portions 1 and 2 define the chamber portions 65 and 67 of FIGS. 7, 8, 9 
and 10 with reciprocation of the second chamber member expanding one of 
the last mentioned chambers while contracting the other in an alternate 
manner. Thus, rotation of the power transfer shaft 12 which transfers 
motion between the rotary mechanism and an external device on the one hand 
and rotation of the first chamber means 1 and 2 in the housing 21 and 
relative reciprocation of both the second chamber means 6 and the piston 9 
on the other hand, occur together and in a precisely determined ratio. 
For example, the shaft 12 might be coupled to a counter or metering device 
to determine a quantity of fluid passing in inlet 16 and out the outlet 
17. The fluid would pass into inlet 16 and by way of opening 47 in the 
housing end portion 13 be fed to a conduit 49 which passes through the 
length of the housing to communicate with a similar opening 51 in housing 
end portion 18 thereby supplying this fluid through both end plates via 
similar input or inlet ports 14 and 15. Further, the interior portion of 
the conduit 49 may be slotted or otherwise apertured to allow even greater 
unrestricted fluid flow into the chamber adjacent to the inlet ports. 
Diametrically opposed to this chamber will be a second chamber 
communicating with outlet ports such as 20 and 19 in each end plate and, 
for example, the fluid flowing into the outlet port in end plate 18 is 
conveyed by way of opening 53 and conduit 55 to a further opening 57 which 
communicates with the outlet 17. Thus, fluid is sequentially supplied to 
and received from chambers defined by the opposed working faces of the 
piston 9 and the interior of the second chamber member 6 on the one hand 
and to and from chambers defined by the opposed working faces of the 
second chamber member 6 and the interior of the first chamber member 
portions 1 and 2 on the other hand. Fluid flow to and from the chamber 
containing the piston 9 within the chamber member 6 is easily achieved by 
providing a number of fluid flow paths 59, 61 and 63 of FIG. 6, however 
many other fluid flow paths could be devised. 
Thus while the present invention has been described with respect to a 
specific preferred embodiment, numerous modifications will suggest 
themselves to those of ordinary skill in the art and accordingly the scope 
of the present invention is to be measured only by that of the appended 
claims.