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Патент USA US3069923

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Dec. 25, 1962
R. J. MccRoRY HAL
3,069,913
CRANKLESS MOTION MECHANISM
Filed May 11, 1960
2 Sheets-Sheet 1
INVENTORS
ROLLIN J. MC CRORY
ALFRED w. CAREY, JR.
JOSEPH H. Mc NINCH, JR.
jig/guy 772% W
Dec. 25, 1962
R, J. MccRoRY ErAL
3,069,913
CRANKLESS MOTIQN MECHANISM
Filed May 11, 1960
2 Sheets-Sheet 2
.
4
_
was
>INVENTORS
ROLLIN J. Mc CRORY
ALFRED W. CAREY'JR.
JOSEPH H. McN|NéH,JR.
panes states Patent O?tice
3,’dt
.
-
CRANlKLEdS iii/‘6L c J MECHANESM
3,®h9,9l3
Patented Dec. 25, isez
prising: three position restraining means; each position
restraining means controlling the position or" a different
Rollin .li. Mctlrory, Wot ngton, and Alfred W. Carey,
reference point on the cage; the reference points being
5n, and Joseph H. Mei inch,
Columbus, @hio, as
angularly spaced at ?xed locations on the cage about the
signors, by mesne assignments, to The Pattelte Develop
merit ?orporaticn, Columbus, (hate, a corporation of 5 axis substantially at an angle between each reference
Delaware
point and the angularly nearest other reference point
Filed May i1, 196%, Ser. l To. 23,27b
of 120 degrees; the position restraining means so re
2 Qiaiuis. (til. 74-6lll
raining the angular displacements of the reference points
from their respective positions at a given position of
This invention relates to a crankless motion mechanism 10 the cage that the algebraic sum of the angular displace
for conversion between reciprocating motion and rotary
ments from the respective positions at any instant is zero.
motion about an axis.
in typical forms of the invention each position restraining
In crankless motion conversion mechanisms, reciprocat
ing moton is converted into rotary motion, or vice versa,
by a rotative slant also known as a swash plate. The con
version from one form of motion to the other may be
accomplished through a nonrotative, oscillating member
known as a cage to which the reciprocating members are
connected. The cage is in slidable engagement with the
slant, which is ?xedly attached to a shaft. The slidable
engagement between the cage and the slant causes the
means comprises a piston connected to a said reference
point on the cage, the piston being slidable in a direction
substantially perpendicular to the axis in a chamber at
a fixed position in the mechanism, substantially incom
pressible ?uid pressing against the piston at one end
thereof in the chamber; means interconnecting the ?uid
in the chambers at said one end of each piston within
a con?ned region, similar substantially incompressible
fluid supplied under pressure to a region in each cham
slant and its attached shaft to rotate as the cage rc~
' er normally between the ends of the piston, and means
Where the reciprocating motion applied to the cage
in each chamber for communicating the last-mentioned
region with the one end of the chamber adjacent said
ciprocates.
produces a torque on the slant to rotate the shaft,
as in a slant engine, the reaction between the slant and
the cage produces a torque on the cage that tends to
one end of the piston when said one end of the piston
moves within a predetermined distance from the adjacent
one end of the chamber, to supply a portion of the ?uid
rotate it in the opposite direction from the rotation
from the last-mentioned region to said one end of the
of the shaft. it is therefore necessary to restrain the
chamber and thus tend to press said one end of the piston
cage to prevent its rotation and yet allow it to react 30 away from said adjacent one end of the chamber.
against the slant. Such restraint is also required where
the rotation of the slant is used to produce reciprocating
In the drawings:
FIG. 1 is a sectional elevation of a crankless motion
motion in the cage.
mechanism embodying the present invention;
It has been found that a small amount of angular mo
FIG. 2 is a normal View, partly in section, of the
tion in the cage about the axis of rotation of the shaft no 01 cage of FIG. 1 and associated apparatus embodying the
is necessary for ef?cient operation. in fact, there is an
invention;
optimum path for such motion of any point on the cage.
HS. 1 shows a portion of a crankless motion mecha~
Any departure from the optimum path can produce high
nism comprising a main shaft 10 rotatably mounted in
inertia loads, causing undue wear and possible damage
to the mechanism. It is important therefore to control
the cage so as to permit the optimum motion while pre
venting any angular motion of the cage as a whole. This
invention provides improved apparatus for providing such
control of the angular position of the cage.
The invention is particularly suited for the crankless
motion mechanism of US. Patent 2,475,295; but it is
not limited thereto. It may be used for angular control
in other mechanisms for the conversion of reciprocating
motion into rotary motion, or vice versa, such as those in
which the slant or swash plate is not ?xedly attached to
the shaft of rotation but is rotatably mounted on an ce
centrically positioned shaft at an angle to the shaft of rota
tion or in which the slant or swash plate is coupled to
the shaft of rotation in any other suitable manner. Crank
less motion conversion mechanisms have been utilized in
suitable bearings 11 and 12. The bearing 11 is located
substantially in the plane of the center of nutation O
of a cage 13 mounted facing a slant or swash plate 14
secured to the shaft iii. The bearing 12 is a?ixed to
a portion of a casing 15. Die shaft it} may be further
mounted in additional suitable bearings, not shown,
a?ixed to the casing 15.
T he block or casing 15 is provided with a plurality of
cylinders, generally designated in, substantially parallel
to the shaft iii and uniformly disposed in a circle about
the shaft 1h. The cage 13 receives the reciprocating
motion of a plurality of pistons, generally designated 17,
which reciprocate in the cylinders 16. A piston rod 18
is connected at one end to a piston 17 and at the other
end to the cage 13 through spherical socket bearings 19
and 2!), respectively. Bearing elements, generally desig
nated 21, which are attached to the cage 13, slidably en
combustion engines, blowing and pumping units, and other
gage the slant 14.
well-known apparatus, some of the means that have been
A mount 22 secured to the casing 15, holds the bearing
used for angular control of cage members of crank~
11 and encircles the shaft 16. The mount 22 has an
less motion conversion mechanisms have been extensions
outer bearing surface 23 comprising a portion of the sur
of the nonrotative, oscillating member or cage meshing
face of a sphere about the center 0. The inner bearing
with cam guides on the mount, or with guides attached to
surface 24 of the cage 13 is similarly shaped and thus
the block or casing. Many such devices occupy excessive
forms a universal joint with the mount 22.. At three ref
space, have small load-carrying capacity, have high fric
erence points 25, only one or" which is shown in FIG. 1,
tional losses or incur serious wear. require special lubri
position restraining means are provided. 'l' he reference
cation devices or manual adjustment and frequent main 65 points 25 preferably are located equidistant from the axis
tenance and repair, and in many applications are not
of rotary motion. The restraining means are angularly
as efficient or as practical as this invention.
spaced about the axis substantially at an angle between
The present invention provides, in a crankless motion
each reference point 25 and the nearest other reference
mechanism for conversion between reciprocating motion
point 25 of 120 degrees. The position restraining means
and rotary motion about an axis, by a rotative slant in 70 so restrain the angular displacements of the reference
slidable engagement with a cage, apparatus for controlling
points 25 from their respective positions at a given posi
the angular position of the cage about the axis, com
tion of the cage that the algebraic sum of the angular
3
in FIG. 1. For convenience these curves are drawn with
reference to a point 36 as indicated in HG. 1. The curve
position as shown in FIG. 2 the con?ned region com’
prising the inner ends 61 of the chambers 37 and the inter
connecting tubing 62 is completely ?lled with a substan
tially incompressible ?uid similar to that in the outer
ends 653 of the chambers 37 and the tubing 39. The
hydraulic interconnection 62 to the inner ends in of the
chambers 37 provides the same restraint on the angular
displacements of the reference points 2.5 as does the hy
draulic interconnection 3? of the outer ends so of the
13 as shown in FIG. 1.
Zero in order to maintain a constant volume of the
displacements from the respective positions at any instant
is zero. It has been found as an important part of this
invention that such restraint causes the cage 13 to move in
the optimum path for efficient operation with lowest
inertia loads and least wear.
The optimum path for movement of any point on the
cage 13 has the shape shown in the curves as, 2.7, and 2%
This is the case because the algebraic or
26 shows the locus of points over which the point so 10 chambers
net sum of ‘the displacements of the pistons se must be
travels as viewed normal to the cross section of the cage
Of course, the curve is dis
placed upward to avoid overlapping the mechanical com
con?ned region 61, as that is completely ?lled with the
ment of the point 36, and the curve 23 is an end View,
63, thereby providing an intermediate open space 6-42 iri
each chamber 37. Substantially incompressible ?uid
substantially incompressible ?uid.
ponents shown in FIG. 1. The curve 27 is a top view,
Each piston 36 includes a necked down midportion‘
as is indicated by the arrow 31, of the locus of the move-1 15
as is indicated by the arrow 32, of the same locus. The
locus of movement is substantially in the shape of a
lemniscate. All points on the cage 13 move in paths
having this same shape, although, of course, points far
ther from the center 0, such as the reference points 25,
similar to that in the ends 6t), er of the chamber 37 and2
in the tubing 39, s2 is supplied under pressure to the:
intermediate space 64 in each chamber 37, through the
tubing 65.
A passage 66 is provided in each chamber 37 to com
municate the intermediate space dd with the outer end
space at} if the outer end of the piston 36 moves within
16 of the casing 15 and cause nutating motion of the cage 25 a predetermined distance from the outer end of the
chamber 37 such that the necked down midportion 63 of
13 by means of the piston rods 18 and the spherical
the piston 35 extends over a portion of the passage 66.
socket bearings 19 and 20. The mutating motion of the
This would happen only if the cage 13 were to move to a
cage 13 is converted to rotary motion of the slant 14 by
position beyond a predetermined desired limit, as might
the slidable engagement of the bearing elements 21 of the
move in larger lemniscate-shaped paths.
In the operation of the crankless motion mechanism
as illustrated, the pistons 17 reciprocate in the cylinders
cage 13 with the slant 14.
The slant 14, being secured 30 happen in the event of seepage of ?uid in the system.
to the main shaft 10, rotates, and thus causes the main
A portion of the ?uid supplied under pressure to the
intermediate space 64 would enter the outer end space
shaft 10 to rotate in the bearings 11, 12. Power take
6i) in the chamber 37, tending to press the outer end of
o?s may be attached to the main shaft 10.
the piston 36 away from the outer end of the chamber
The piston load conveyed by the rods 18 is trans
mitted through the socket bearings 20, through the non 35 37 and thus counteract the undesirable movement of the
cage 13.
rotative, nutatin‘g member or cage 13, and from there
A passage 67 is provided in each chamber 37 to com~j
through the bearing elements 21 to the slant 14, thereby
municate the intermediate space 64 with the inner ‘end
causing rotation of the slant 14. The inward or radial re
space 61 if the inner end of the piston 36 moves within
action from the bearing elements 21 is transferred through
a predetermined distance from the inner end of the cham:
ber 37 such that the necked down midportion 63 of the
piston se extends over a portion of the passage 67. This
the reference points 25.
would happen only if the cage 13 were to move to a posi
FIG. 2 brings out preferred details of a preferred form
tion beyond a predetermined desired limit, as might
of apparatus for controlling the angular position of
happen in the event of seepage of ?uid in the system.
the cage 1.3 about the axis of the shaft 19. Each refer
A portion of the fluid supplied under pressure to the
ence point 25 is connected through a spherical socket bear
intermediate space 64% would enter the inner end space 61
ing 33 to one end of a piston rod 34 the other end of
in the chamber 37, tending to press the inner end of the
which is connected through a spherical socket bearing
piston 3d away from the inner end of the chamber 37
35 to a piston 36. Each piston 36 is slidable in a direc
50 and thus counteract the undesirable movement of the
tion essentially perpendicular to the axis 10 in a chamber
cage 13.
37 in the housing 38 which is attached at a fixed point
A passage 68 in the shank 69 of the piston 35 communis
to the casing 15 of the crankless motion mechanism.
cates the inner end space 65. with an outlet ‘7t? in the case
The outer ends at} or" the chambers 3'’! are interconnected
if the inner end of the piston 36 moves beyond
by tubing 39. With the cage 13 in a given position as 55 ing
a predetermined distance from the inner end of the chain-:
shown in FIG. 2 the con?ned region comprising the
her 37, so that a portion of the ?uid from the inner end
outer ends 60 of the chambers 37 and the interconnect
space 61 can ?ow out of the space 61 and thus tend to
ing tubing 39 is completely ?lled with a substantially in
move the inner end of the piston as toward the inner
compressible ?uid.
Because of the hydraulic interconnection, as described, 60 end of the chambers 37. This action aids the action of
the ?uid under pressure in the intermediate space 64»
the movement of the cage 13 is restrained in such a
communicating through the passage 66 to the outer end
manner that the angular displacements of the reference
space so which tends to provide movement in the same
points 25 from their respective positions as shown in FIG.
direction. The release of ?uid from the inner end space
2 is such that the algebraic sum of the angular displace
51 of the chamber 37 also tends to maintain a constant:
ments of the reference points 25 at any instant is zero.
volume of ?uid in the apparatus.
This is the case because the algebraic or net sum of the
The front end portion 719 of each piston 36 containing’
displacements of the pistons 36 must be zero in order to
the
spherical socket bearing 35 is slidably held in a guide‘
maintain a constant volume of the con?ned region
chamber ‘71 to aid in guiding the direction of movement
(69, 39) that is completely ?lled with the substantially
of the piston 36 and avoid wear in the piston as and the
incompressible ?uid.
70 chamber 37 that would result from radial or twisting
To minimize any possible inaccuracies in the control
the cage 13 to the outer bearing surface 23 of the mount
22. The tangential or torque reaction is transferred to
that might be caused by seepage of ?uid, the apparatus
of FIG. 2 includes means for compensating for possible
forces on the piston as.
seepage. The inner ends 61 of the chambers .37 are inter
crankless motion mechanism for conversion between re
connected by tubing 62. With the cage 13 in a given
To summarize, the present invention provides, in a
ciprocating motion and rotary motion about an axis In),
5
3,069,913
by a rotative slant 14 in slidable engagement with a cage
13, apparatus for controlling the angular position of the
cage 13 about the axis 319, comprising: three position
6
cage, apparatus for controlling the angular position of
said cage about said axis, comprising: three position re
straining means; each said position restraining means con
trolling the position of a different reference point on said
restraining means; each position restraining means con
trolling the position of a different reference point 25
cage; said reference points being angularly spaced at
on the cage; the reference points 25 being angularly
fixed locations on said cage about said axis substantially
spaced at ?xed locations on the cage about the axis 10
at an angle between each reference point and the angular
substantially at an angle between each reference point 25
ly nearest other reference point of 120 degrees; said posi
and the angularly nearest other reference point 25 of
tion restraining means so restraining the angular dis~
120 degrees; the position restraining means so restraining 10 placements of said reference points from their respective
the angular displacements of the reference points 25 from
positions at a given position of said cage that the algebraic
their respective positions at a given position of the cage
sum of said angular displacements from said respective
13 that the alegbraic sum of the angular displacements
positions at any instant is zero; each said position restrain
from the respective positions at any instant is zero.
ing means comprising a piston connected to a said refer
Each position restraining means comprises a piston 36 15 ence point on said cage, said piston being slidable in a
connected (33, 3d, 35) to a reference point 25 on the
direction substantially perpendicular to said axis in a
cage 13, the piston 36 being slidable in a direction sub
chamber at a ?xed position in said mechanism, substan
stantially perpendicular to the axis 16 in a chamber 37
tially incompressible ?uid pressing against said piston at
at a ?xed position in the mechanism, substantially incom
one end thereof in said chamber; means interconnecting
pressible ?uid pressing against the piston 36 at one end
the ?uid in said chambers at said one end of each said
64) thereof in the chamber 37, means 39 interconnecting
piston within a con?ned region, similar substantially in
the ?uid in the chambers 37 at said one end 69 of each
compressible ?uid supplied under pressure to a region in
piston 36 within a con?ned region 6b, 39, similar substan
each said chamber normally between the ends of said
tially incompressible ?uid pressing against each piston 36
piston, and means in each said chamber for communicat
at the opopsite end 61 thereof in the chambers 37, means 25 ing said last-mentioned region with the one end in said
62 interconnecting the fluid in the chambers at said 0p
chamber adjacent said one end of said piston when said
posite end 61 of each piston 36 within a con?ned region
61, 62, similar substantially incompressible ?uid sup
plied 65 under pressure to a region 64 in each chamber
37 normally between the ends of the piston 36, means
66 in each chamber 37 for communicating the last-men
tioned region 6d with the one end 66) in the chamber 37
adjacent said one end of the piston 36 when said one end
of the piston 36 moves within a predetermined distance
from the adjacent one (outer) end of the chamber 37
to supply a portion of the ?uid from the last-mentioned
region 64 to the one end at} of the chamber and thus tend
to press said one end of the piston 36 away from the
adjacent one end of the chamber 37, means 67 in each
one end of said piston moves within a predetermined dis
tance from the adjacent one end of said chamber to
supply a portion of said fluid from said last-mentioned
region to said one end of said chamber and thus tend to
press said one end of said piston away from said ad
jacent one end of said chamber.
2. in a cranlrless motion mechanism for conversion
between reciprocating motion and rotary motion about an
axis, by a rotative slant in slidable engagement with a
cage, apparatus for controlling the angular position of
said cage about said axis, comprising: three position re
straining means; each said position restraining means con
chamber 37 for communicating the last mentioned region 40 trolling the position of a di?erent reference point on said
cage; said reference points being angularly spaced at ?xed
64 with the opposite end 61 in the chamber 37 adjacent
locations on said cage about said axis substantially at an
said opposite end of the piston 36 when said opposite
angle between each reference point and the angularly
end of the piston 36 moves within a predetermined dis
nearest
other reference point of 120 degrees; said position
tance from the adjacent (inner) opposite end of the
restraining means so restraining the angular displacements
chamber 37 to supply a portion of the ?uid from the last
of said reference points from their respective positions
mentioned region 64 to the opposite end 61 of the cham
at a given position of said cage that the algebraic sum
ber and thus tend to press said opposite end of the piston
of said angular displacements from said respective posi
35 away from the adjacent opposite end of the chamber
tions at any instant is zero; each said position restraining
37, and means 63 in the chamber 37 for communicating
said opposite end 61 with an outlet 7o therefrom when 50 means comprising a plston connected to a said reference
point on said cage, said piston being slidable in a direction
said opposite end of the piston 36 moves beyond a pre—
substantially perpendicular to said axis in a chamber at
determined distance from said adjacent opposite end of
a ?xed position in said mechanism, substantially incom
the chamber 37 to permit a portion of the ?uid from
pressible ?uid pressing against said piston at one end
said opposite end 61 of the chamber to flow out of the
chamber and thus tend to move said opposite end of said 55 thereof in said chamber, means interconnecting the ?uid
in said chambers at said one end of each said piston within
piston toward said adjacent opposite (inner) end of the
a con?ned region, similar substantially incompressible
chamber 37.
?uid pressing against each said piston at the opposite end
The reference characters in the above summary indi
thereof in said chambers, means interconnecting the ?uid
cate generally the primary components shown in the
drawings corresponding to the recited features, to facili 60 in said chambers at said opposite end of each said piston
within a con?ned region, similar substantially incompres
tate understanding of the claims. The reference char
sible ?uid supplied under pressure to a region in each
acters are used merely by way of example, however, and
said chamber normally between said ends of said piston,
not in any limiting sense.
means in each said chamber for communicating said last
While the forms of the invention herein disclosed con
stitute preferred embodiments, it is not intended to de 65 mentioned region with the one end in said chamber ad
jacent said one end of said piston when said one end of
scribe all of the possible equivalent forms or rami?cations
said piston moves within a predetermined distance from
of the invention. It will be understood that the words
the adjacent one end of said chamber to supply a portion
used are words of description rather than of limitation,
of said ?uid from said last-mentioned region to said one
and that various changes, as in shape, relative size, and
arrangement of parts, may be made without departing 70 end of said chamber and thus tend to press said one end
from the spirit or scope of the invention.
of said piston away from said adjacent one end of said
What is claimed is:
chamber, means in each said chamber for communicating
l. in a crankless motion mechanism for conversion be
said last-mentioned region with the opposite end in said
tween reciprocating motion and rotary motion about an
chamber adjacent said opposite end of said piston when
axis, by a rotative slant in slidable engagement with 21
said opposite end of said piston moves within a predeter
3,069,913
4
mined distance from the adjacent opposite end of said
chamber to supply a portion of said ?uid from said last
mentioned region to said opposite end of said chamber
and thus tend to press said opposite end of said piston
away from said adjacent opposite end of said chamber,
and means in said chamber for communicating said
opposite end with an outlet therefrom When said opposite
end of said piston moves beyond a predetermined distance
8
tend to move said opposite end of said piston toward said
adjacent opposite end of said chamber.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,105,019
2,326,912
2,917,931
'Turner _______________ __ Ian. 11, 1938
Allison ______________ __ Aug. 17, 1943
Sherman _____________ __ Dec. 22, 1959
1,132,634
France ________________ __ Nov. 5, 1956
from said adjacent opposite end of said chamber‘ to
permit a portion of said ?uid from said opposite end 10
.of said chamber to flow out of said chamber and thus
FOREIGN PATENTS
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