WO1998030807A1

WO1998030807A1 - On-the-fly, real-time controlled variable stroke crankshaft

Info

Publication number: WO1998030807A1
Application number: PCT/US1998/000466
Authority: WO
Inventors: Douglas C. Brackett
Original assignee: Brackett Douglas C
Priority date: 1997-01-10
Filing date: 1998-01-08
Publication date: 1998-07-16

Abstract

A variable stroke crankshaft includes a crankshaft (10) with a fixed crankpin (20) upon which is mounted a moveable crankpin shell (30). The shell (30) may be positioned at a selected degree of eccentricity relative to the fixed crankpin (20) of the crankshaft (10) under hydraulic or mechanical control. In a first embodiment, a portion of the shell (30) and a mating portion of the fixed crankpin (20) comprise at least one hydraulically sealed, variable volume chamber (84), such that fluid (80) inflow to the chamber (84) displaces the shell (30) radially and increases the effective stroke of the crankshaft (10). In an alternative embodiment, the position of a threaded cam rod (1055) mechanically determines shell position. The shell (30) may be displaced on-the-fly while the crankshaft (10) is in use and based on feedback to achieve real-time control.

Description

ON-THE-FLY, REAL-TIME CONTROLLED VARIABLE STROKE CRANKSHAFT

Technical Field of the Invention

The present invention relates to a crankshaft and mechanical

movements incorporating same, and, more particularly, to a real-time

controlled, variable stroke crankshaft having the capacity to change radius

(i.e., the distance between crankshaft center and crankpin center) to offset the

crankpin and vary stroke on the fly during the operation of the device.

Background Art

Through the years it has been an objective in the mechanical

arts to provide a mechanical movement permitting the variability of input shaft

speed/movement to the output volume/displacement of a cylinder or other

displaceable member in the mechanical movement. One of the most popular

mechanical apparatus for translating linear motion into rotary motion and vice

versa has been the crankshaft. Crankshafts are utilized in diverse apparatus

including internal combustion engines for translating the linear, reciprocating

motion of pistons into the rotary motion of a crankshaft, for compressors and

for other motion translating and transmitting apparatus. The crankshaft

mechanism has therefore been the subject of study in terms of providing a

variable stroke or crankpin offset for a variety of mechanical apparatus.

These prior efforts have resulted in very complex crankshaft apparatus which are heavy, difficult to manufacture, and mechanically weakened relative to a

conventional crankshaft. A change of stroke usually requires stopping and

dismantling the device to make adjustments before restarting. It is therefore

an object of the present invention to provide a simple, economical, sturdy,

adjustable stroke crankshaft which is adjustable in real time, on-the-fly,

without the need to stop the device to effect a stroke change.

Disclosure of the Invention

The problems and disadvantages associated with the

conventional techniques and devices utilized to provide a variable stroke

crankshaft are overcome by the present invention which includes a crankshaft

having a cylindrical shaft and a crankpin coupled to the shaft. A crankpin

active bearing member shell is disposed about the integral crankpin

foundation and is hydraulically radially displaceable by fluid, air or mechanical

means to a selected degree of eccentricity relative to the crankshaft shaft

center.

Brief Description of the Drawings

For a better understanding of the present invention, reference

is made to the following detailed description of various exemplary

embodiments considered in conjunction with the accompanying drawings, in

which: FIG. 1 is a plan view of a crankshaft in accordance with an

exemplary embodiment of the present invention;

FIG. 2 is a side view of the crankshaft of FIG. 1 ;

FIG. 3 is a front view of the crankshaft shown in FIGS. 1 and 2;

FIG. 4 is a cross-sectional view of the crankshaft of FIG. 1 taken

along section lines IV-IV and looking in the direction of the arrows;

FIG. 5 is the crankpin of FIG. 4 with a pair of active bearing

member segments shown exploded away from the crankpin;

FIG. 6 is the crankpin and active bearing member segments of

FIG. 5 in an assembled configuration and at a first crankpin bearing offset,

namely, zero offset;

FIGS 7-9 show the crankpin and active bearing member

segments of FIG. 6 at three sequentially larger crankpin bearing offset

positions;

FIGS. 10-12 show a second exemplary embodiment of the

present invention at three stages of crankpin offset;

FIG. 13 is a plan view of a crankshaft assembly constructed in

accordance with a third exemplary embodiment of the present invention;

FIG. 14 is a front view of the crankshaft assembly illustrated in

FIG. 13;

FIG. 15 is a plan view of a crankshaft assembly constructed in

accordance with a fourth exemplary embodiment of the present invention; FIG. 16 is a cross-sectional view of the crankshaft assembly

illustrated in FIG. 15, taken along the line XVI-XVI and looking in the direction

of the arrows;

FIG. 17 is an exploded perspective view of a crankshaft

assembly constructed in accordance with a fifth exemplary embodiment of the

present invention;

FIG. 18 is a side view of the crankshaft assembly illustrated in

FIG. 17;

FIG. 19 is a front view of a crankshaft assembly as illustrated in

FIG. 13 wherein the active bearing member travels along an arcuate path;

FIG. 20 is a front view of a crankshaft assembly as in FIG. 19

with the arcuate path of the active bearing member displaced eccentrically

relative to the outer cylindrical surface of the active bearing member;

FIG. 21 is a front view of a crankshaft assembly as illustrated in

FIG. 20 but incorporating a positioning piston and mating cylinder shown in

phantom;

FIG. 22 is a front view of a crankshaft assembly utilizing a one-

piece active bearing member;

FIG. 23 is a side view of the crankshaft assembly shown in FIG.

22. FIG. 24 is a side view of a crankshaft assembly constructed in

accordance with a fifth alternative exemplary embodiment of the present

invention utilizing a composite active bearing member;

FIG. 25 is a front view of the crankshaft assembly of FIG. 24;

FIG. 26 is a side view of a crankshaft assembly in accordance

with a sixth alternative embodiment of the present invention;

FIG. 27 is a front view of the crankshaft assembly of FIG. 26;

FIG. 28 is a partially schematic plan view of the internal

components of the crankshaft assembly of FIGS. 26 and 27;

FIG. 29 diagrammatically shows the application of the present

invention in a scotch yoke system;

FIG. 30 diagrammatically shows the application of the present

invention in a slider crank/piston/connecting rod system; and

FIG. 31 diagrammatically depicts the application of the present

invention in a conjugate drive system.

Best Mode for Carrying Out the Invention

FIG. 1 shows a crankshaft 10 having a pair of opposing shafts

12, 14. The shafts 12, 14 are affixed to main bearing journals 16 and 18,

respectively. A crankpin 20 connects the two main bearings 16, 18. The

crankpin 20 shown in FIG. 1 is multifaceted, as can be more fully appreciated

from the perspective shown in FIG. 3, and has a flat top face 22, a rounded rear surface 24, and a rounded front surface 26. A flat bottom surface 28 of

the crankpin 20 is not visible in FIG. 1 , but can be seen in FIG. 3. The

crankpin 20 of the present invention is unconventional in that it is not

cylindrical and does not directly interact in a coaxial sliding manner with

another mechanical element, such as a connecting rod. Rather, the present

invention utilizes an intermediate, hydraulically actuated crankpin shell with

an internal hollow (active bearing member) 30 (see FIG. 6) to interact with a

cooperating mechanical link, such as a connecting rod, roller or block bearing

as shall be explained below. The crankshaft 10 is provided with passageways

or galleys for conducting an hydraulic actuating fluid, such as a lightweight oil,

which is supplied under pressure from a source of hydraulic fluid M (master

cylinder) to the crankshaft 10 via an annular groove 34 in one of the shafts 12,

14. The crankshaft 10 of the present invention would typically be utilized in

a crankcase or block equipped with bearing shells and a pressurized

lubrication system. In the alternative, ball or roller bearings could be

employed to support the crankshaft. A similar arrangement of close tolerance

bearing shells and seals and/or a stuffing box arrangement is preferably

employed to provide a separate sealed system to supply pressurized

hydraulic fluid to groove 34 which is communicates with a radial galley 36 for

supplying hydraulic fluid to an axial main galley 38 and from there to the

surface 26 of the crankpin 20 via a crankpin galley 40. As is conventional, the

internal galleys in the embodiment depicted are drilled in the crankshaft. In the embodiment shown, the main galley 38 is plugged by plug 42. In another

alternative, pressurized hydraulic fluid could be supplied to the main galley 38

via an opening in the end of the shaft 14, e.g., via a connection at the opening

sealed by plug 42.

FIG. 2 shows the same basic features as FIG. 1 except that the

entrances to the radial crankpin galley 40 and radial supply galley 36 are

visible in this view. It is also important to observe that the crankpin 20 in FIG.

2 is symmetrically disposed along the axis of the crankshaft 10. In contrast,

the plan view of FIG. 1 shows the crankpin 20 being axially offset to the right.

FIG. 3 also illustrates the above-mentioned asymmetry with

respect to the position of the crankpin 20 which is shown in phantom. FIG.

3 also illustrates that the crankpin 20 has flattened surfaces 22 and 28 and

rounded portions 24 and 26. The significance of this cross-sectional shape

is its interaction with the active bearing member 30 (see FIG 6) as shall be

described below. In FIG. 3, the crankpin 20 and radial crankpin galley 40 are

shown in phantom.

The cross-sectional view of the crankpin 20 shown in FIG. 4

illustrates that the crankpin 20 has a symmetrical shape and is offset from the

axis of the crankshaft 10. This can be most easily appreciated by observing

the position of the main axial galley 38, which is coaxial with the crankshaft

10, as well as the shafts 12, 14 and the main bearings 16, 18 (see FIG. 1).

Upon comparing the distance between to the surfaces 24 and 26 and the axial galley 38, it is apparent that the crankpin 20 is offset to the right of

crankshaft center line CL (see FIG. 1).

FIG. 5 shows the active bearing member 30 of the present

invention which is composed of a pair of mating active bearing member

segments 44 and 46. The active bearing member segments 44, 46 have

complementary mating structures 48, 50 and 52, 54, respectively, which may

take the form of mating dowels and holes or any other form of projection and

mating recess to positively locate the active bearing member segments 44,

46 relative to each other. Each of the active bearing member segments 44,

46 has apertures 56, 58 and 60, 62, respectively, (shown in phantom) for

accommodating a bolt or other connector for clamping the mating active

bearing member segments 44, 46 tightly together. Each of the active bearing

member segments 44, 46 has a pair of flat surfaces 64, 66 and 68, 70,

respectively, for slidably embracing the corresponding flat surfaces 22, 28 of

the crankpin 20. Further, each of the active bearing member segments 44,

46 has curved surfaces 72 and 74 sized and shaped to fit snugly against

surfaces 24, 26, respectively, of the crankpin 20. For instance, in FIG. 6, the

surface 74 of the active bearing member segment 46 fits against the surface

26 of the crankpin 20, while in FIG. 9, the surface 72 of the active bearing

member segment 44 fits against the surface 24 of the crankpin 20. While the

foregoing is an efficient configuration, the present invention does not require

complementary shapes for surfaces 72, 74 and 24, 26. Furthermore, while generally arcuate surfaces 72, 74, 24, 26 are shown in, e.g., FIG. 6, such

surfaces need not be arcuate but could assume any desired contour. For

instance, the surfaces 72, 74 and the surfaces 24, 26 can be flat.

FIG. 6 shows the active bearing member segments 44, 46

assembled together around the crankpin 20. As can be appreciated, when

the active bearing member segments 44, 46 are assembled together, they

form a space therebetween defined by the internal surfaces 64, 66, 68, 70,

72, 74. More particularly, the space is sized and shaped so as to allow the

active bearing member surfaces 64, 68 and 66, 70 to slide along the surfaces

22 and 28, respectively, of the crankpin 20 over a limited range of travel

toward and away from the crankshaft center line (see FIG. 1 ). When the

active bearing member 30 is displaced, as in FIG. 6, to its limit of travel in a

leftward direction, a chamber 76 is formed between the interior surface 72 of

the active bearing member segment 44 and the curved surface 24 of the

crankpin 20. This chamber 76 may be vented by a vent 78 in order to

express air and/or hydraulic fluid, as shall be explained below. As noted, the

active bearing member 30 is in its left-most position in FIG. 6, such that the

surface 26 of the crankpin 20 is proximate to or in contact with the interior

curved surface 74 of the active bearing member segment 46. Hydraulic fluid

80 is shown filling the main axial galley 38 and the radial crankpin galley 40.

In the present invention, exterior surface 82 of the active bearing member 30

is cylindrical in shape and is preferably machined and polished to serve as a suitable bearing/journal surface. The exterior surface 82 of the active bearing

member 30 is analogous to the exterior surface of a conventional crankpin

and receives the articulated member of the mechanical movement which

interacts with the crankpin, e.g., the large end of a connecting rod. It can thus

be appreciated that as the crankshaft 10 is turned, the crankpin 20 will revolve

about the crankshaft axis at a fixed angular orientation as defined, e.g., by an

axis of symmetry. The active bearing member 30 will revolve conjointly with

the crankpin 20 at the same angular orientation, that is, with the flat surfaces

22, 28 of the crankpin 20 closely engaging the flat surfaces 64, 66, 68, 70 of

the active bearing member 30. Accordingly, the active bearing member 30

does not rotate relative to the crankpin axis.

FIG. 7 illustrates that the active bearing member 30 can be

radially displaced hydraulically via pressurized hydraulic fluid 80 which is

pumped between the curved surface 26 of the crankpin 20 and the interior

curved surface 74 of the active bearing member segment 46, thereby creating

a chamber 84 filled with hydraulic fluid 80. The volume of hydraulic fluid 80

forced into the chamber 84 determines the crankpin bearing offset (or radial

displacement). Referring back to FIG. 6 briefly, one can note that in its left¬

most position (zero radial displacement), the outer surface 82 of the active

bearing member 30 is coaxial with the main bearing 16. In this position, the

crankshaft (crankpin) stroke is zero. In FIG. 7, the active bearing member 30

is offset (radially displaced), resulting in a total stroke equal to two times the offset. A connecting rod attached to the outer surface 82 of the active bearing

member 30 would be displaced by the rotation of the crankshaft 10, i.e., it

would trace a circle of radius equal to the offset. In a typical

piston/cylinder/connecting rod/slider crank arrangement, the active bearing

member offset of FIG. 7 would generate reciprocating linear piston

displacement equal to the stroke upon crankshaft rotation.

FIGS. 8 and 9 show greater active bearing member offsets

leading to larger crankshaft strokes and larger displacements, e.g., of a

crankshaft/connecting rod articulated reciprocating piston. For instance, FIG.

9 shows the active bearing member 30 in its maximum displacement position

and hence the greatest active bearing member offset. In this position, the

surface 72 of the active bearing member segment 44 is proximate to or in

contact with the surface 24 of the crankpin 20.

As can be appreciated by those of normal skill in the art, the

crankshaft of the present invention has numerous applications in a variety of

mechanical movements. For example, in a hydraulic pump or compressor,

the variable stroke achievable with the present invention would permit a

variable output from the pump. In addition, the torque/volume relationship

achievable due to a variable stroke can be used to match torque to the

power/speed requirements of a mechanical movement. Because the

displacement of the active bearing member can be regulated over an infinite

range from zero to the limit of travel of the active bearing member, the stroke is infinitely variable in accordance with the hydraulic positioning of the active

bearing member. For this reason, the present invention could readily be

utilized in such desirable applications as an infinitely variable hydraulic

transmission for transmitting power from a first driving mechanical movement

to a second driven movement. In addition to providing a simple, adjustable

stroke crankshaft, the crankshaft of the present invention is adjustable while

the crankshaft is in use, i.e., by controlling the hydraulic fluid regulating the

position of the active bearing member (stroke). As a result, the stroke of the

crankshaft can be dynamically altered in order to suit the requirements of the

application. For example, in the case of an infinitely variable hydraulic

transmission, high torque/high input/output ratios would be associated with

small active bearing member displacement. As torque demand decreases,

the active bearing member displacement can be gradually increased leading

to progressively larger stroke and lower input/output ratios. These

adjustments to crank stroke can be implemented while the crankshaft is

moving (on-the-fly) and may be controlled by feedback/demand to achieve

real-time control.

As can be appreciated from FIGS. 7-9, the displacement of the

active bearing member 30 leading to larger crank stroke is caused and

maintained by an increased volume of incompressible hydraulic fluid 80 in

chamber 84. Because of inertia, a driven member, such as a connecting rod,

would resist any crankpin offset from the neutral position and would exert reactive forces tending to push the active bearing member back to a neutral

or zero displacement position. In such circumstances, in order to reduce

active bearing member displacement, for instance, from the displacement

shown in FIG. 9 to the displacement shown in FIG. 7, some of the pressurized

hydraulic fluid 80 is bled out of the chamber 84 via a release valve V (see

FIG. 1 ) disposed in the pressurized hydraulic line that supplies chamber 84.

Fluid bled out of the pressurized portion of the hydraulic system may be

directed to a reservoir R disposed on the supply side of the source M of

pressurized hydraulic fluid (see FIG. 1).

As depicted in FIGS. 6-9, the clearance between the surfaces

64, 66, 68, 70 of the active bearing member 30 and the surfaces 22 and 28

of the crankpin 20 must be as small as possible to inhibit fluid leakage from

the pressurized chamber 84 to, for instance, the unpressurized chamber 76.

Since some amount of leakage is inevitable, the chamber 76 is vented by vent

78 such that chamber 76 does not become filled with fluid that would impede

repositioning the active bearing member 30. Because some leakage of

hydraulic fluid from chamber 84 is expected, applications employing the

present invention may incorporate sensors that sense on active bearing

member displacement such that the source of hydraulic fluid controlling active

bearing member position can be operated based upon feedback from the

sensor. In this manner, a desired active bearing member displacement can be maintained, notwithstanding leakage of hydraulic fluid from the pressurized chamber 84.

The source M of pressurized hydraulic fluid controlling the

position of the active bearing member may be a separate hydraulic pump or

be bled off from the primary working fluid in those applications where the

working fluid is suitable for use in controlling the active bearing member, e.g.,

in a hydraulic transmission. As can be appreciated, a master and slave

hydraulic system can be utilized for controlling the position of the active

bearing member 30. Moreover, the hydraulic system can be entirely

contained inside the crankshaft 10 and be equipped with an internal or remote

passive/active motive control system or an external linkage/cable control

system. Further, the master chamber of the hydraulic system can be external

and have hydraulic lines adapted to feed its associated internal slave

chamber through active or passive intervention.

In those applications where the hydraulic displacement chamber

84 is unloaded during the cycling of the crank, e.g., at top and bottom dead

center of a reciprocating piston system, the vent 78 may be eliminated in favor

of a completely filled chamber 76 with fluid displaced from one chamber being

pumped into the other to establish a desired active bearing member position.

FIG. 10 shows an alternative embodiment of the present

invention wherein the active bearing member segment 146 includes an inner

surface 174 in the shape of a cylinder for receiving a piston 186. The piston 186 may have sealing or compression rings 188 for effecting an hydraulic

seal. The piston 186 may be monolithically formed with the crankpin 120 or

it may be a separate element affixed by a bolt or other fastening means. The

piston 186 may be cylindrical or elongated in the direction perpendicular to

the plane of the drawing. Instead of a single piston/cylinder as shown in FIG.

10, a plurality of pistons/cylinders can be employed. As is known to those

with skill in the art of hydraulic apparatus, a piston with seal rings can provide

an extremely effective seal within a mating cylinder, such that leakage of the

hydraulic fluid in pressurized chamber 184 can effectively be eliminated. FIG.

10 illustrates diagrammatically that the diameter of the shaft 112 may be

smaller than that of the active bearing member 130. This oversize crankpin

configuration is somewhat unconventional relative to common crankshafts

wherein the crankpin is typically of similar or smaller size than the crankshaft

size. The embodiment shown in FIGS. 10-12 operates in essentially the

same manner as the previously described embodiment shown in FIGS. 1-9.

Hydraulic fluid pumped through the axial main galley 138 communicates with

the radial crankpin galley 140 filling the space between the upper surface of

the piston 186 and the inner surface 174 of the active bearing member

segment 146. This can be used to displace the active bearing member 130

in an outward direction for greater crankpin offsets. In FIG. 10 the active

bearing member offset is zero. FIGS. 11 and 12 illustrate progressively larger hydraulic

displacements. In order to decrease active bearing member offset, fluid filling

chamber 184 can be bled off or redirected to the opposite side of the crankpin

as described above.

FIGS. 13 and 14 illustrate a crankshaft assembly 210

constructed in accordance with a third alternate embodiment of the present

invention. The construction and operation of the crankshaft assembly 210 of

FIGS. 13 and 14 are basically the same as those of the embodiment of FIGS.

1 -9, except as follows. The crankshaft assembly 210 has an oversized

crankpin 220 and an oversized active bearing member 230 formed by a pair

of mating active bearing member segments 244, 246. The diameter of the

crankpin 220, as well as the active bearing member 230, is larger than those

of opposing shafts 212, 214 and main bearing journals 216, 218 of the

crankshaft assembly 210. This oversize crankpin and active bearing member

configuration is somewhat unconventional relative to common crankshafts

and it provides increased bearing surfaces associated with the crankpin 220

and the active bearing member 230 (e.g., the flat surfaces 222, 228 of the

crankpin 220 and the exterior surface 282 of the active bearing member 230)

and thereby enhances the structural integrity and load bearing capacity of the

crankshaft assembly 210. Because the crankpin 220 and the active bearing

member 230 are larger than the bearing journals 216, 218, the bearing

journals 216, 218 do not capture the active bearing member 230 therebetween like the bearing journals 16, 18 of the embodiment shown in

FIGS. 1-9. Rather, the active bearing member segments 244, 246 are

assembled together along a plane perpendicular to the axis of rotation of the

crankshaft assembly 210. Accordingly, the active bearing member segments

244, 246 have apertures 256, 258 and 260, 262, respectively, formed in facial

surfaces 290, 292, respectively, thereof for receiving fasteners, e.g., bolts.

The active bearing member segment 244 includes a pair of guide rails 294,

296 projecting from opposing flat surfaces 264, 266, respectively, and a web

298 covering a portion of a space formed between the active bearing member

segments 244, 246 (see FIG. 14). Likewise, the active bearing member

segment 246 includes a pair of guide rails 211 , 213 projecting from opposing

flat surfaces 268, 270, respectively, (see FIG. 13) and a web (not shown)

covering a portion of the space. The webs 298 cooperate with the flat

surfaces 264, 266, 268, 270 and the crankpin 220 to form a pressurized

chamber 284 adapted to be filled with hydraulic fluid for radially displacing the

active bearing member 230. The webs 298 also cooperate with the guide

rails 294, 296, 211 , 213 to securely position the active bearing member 230

on the crankpin 220 and therefore perform a function similar to that performed

by the bearing journals 16, 18 of the embodiment shown in FIGS. 1-9. That

is, the webs 298 and guide rails 294, 296, 211 , 213 cooperate to inhibit the

active bearing member 230 from moving longitudinally relative to the crankpin

220. FIGS. 15 and 16 illustrate a crankshaft assembly 310

constructed in accordance with a fourth alternate embodiment of the present

invention. The construction and operation of the crankshaft assembly 310 of

FIGS. 15 and 16 are basically the same as those of the embodiment of FIGS.

10-12 except as follows. The crankshaft assembly 310 has an oversized

crankpin 320 and an oversized active bearing member 330 formed by a pair

of mating active bearing member segments 344, 346. More particularly, the

diameter of the crankpin 320, as well as the active bearing member 330 is

larger than those of opposing shafts 312, 314 and main bearing journals 316,

318 of the crankshaft assembly 310. While this configuration is somewhat

unconventional relative to common crankshafts, it provides increased bearing

surfaces associated with the crankpin 320 and the active bearing member

330 (e.g., the flat surfaces 322, 328 of the crankpin 320 and the exterior

surface 382 of the active bearing member 330) and thereby enhances the

structural integrity and load bearing capacity of the crankshaft assembly 310.

The crankpin 320 is provided with a piston 386, while the active bearing

member segment 346 is provided with a cylinder 374 which cooperates with

the piston 386 for hydraulically displacing the active bearing member 330 with

respect to the crankpin 320. The piston 386 and the cylinder 374 also

cooperate to inhibit the active bearing member 330 from moving longitudinally

relative to the crankpin 320 during the operation of the crankshaft assembly

310. As a result, the active bearing member segments 344, 346 need not be provided with guide rails or webs similar to the guide rails 294, 296, 211 , 213

and the webs 298 of the embodiment shown in FIGS. 13 and 14.

Alternatively, the active bearing member 330 can be provided with guide rails

and/or webs to decrease the sideloading on the piston 386 and the cylinder

374.

FIGS. 17 and 18 illustrate a crankshaft assembly 410

constructed in accordance with a fifth alternate embodiment of the present

invention. The construction and operation of the crankshaft assembly 410 of

FIGS. 17 and 18 are basically the same as those of the embodiment of FIGS.

13 and 14, except as follows. A pair of mating active bearing member

segments 444, 446 are assembled together along an axis transverse to the

rotational axis of the crankshaft assembly 410 to form an active bearing

member 430. The active bearing member segments 444, 446 are provided

with dove-tail shaped keys 415, 417 projecting from active bearing member

surfaces 464, 468, respectively. The active bearing member segments 444,

446 also have box shaped keys 419, 421 projecting from opposing active

bearing member surfaces 466, 470, respectively. The keys 415, 417 and the

keys 419, 421 slidably engage complementarily shaped gibbed ways 423,

425, respectively, formed in crankpin 420. More particularly, as the active

bearing member 430 is displaced, the keys 415, 417 and the keys 419, 421

slidably move along the gibbed ways 423, 425. FIG. 19 shows an alternative embodiment of the present

invention wherein the crankpin 520 outer surfaces 522 and 528 are formed

concentrically with arc A. The surfaces 564 and 568 of the active bearing

member 530 are curved to approximate the curved crankpin surfaces 522,

528, respectively. As a consequence, when the active bearing member 530

is displaced relative to the crankpin 512, it moves along the path of arc A.

One of the beneficial attributes of this embodiment is that the arcuate

surfaces 522, 528 will have a tendency to bear against mating surfaces 564,

568 when under the maximum load exerted by the articulated member.

Depending upon the application, this may occur, e.g., at top dead center. The

urging of the crankpin against the active bearing member surfaces 564, 568

transfers the load mechanically and/or through friction from the active bearing

member 530 to the crankpin. This diverts loading of the hydraulic chamber

584 which would otherwise induce leaking of hydraulic fluid from the chamber

584 and/or would tend to push the actuating or slave piston that displaces the

active bearing member to a lower displacement position via backpressure.

As before, the active bearing member 530 shown in FIG. 19 is concentrically

located relative to shaft 512 when in the neutral position.

In FIG. 20, which shows a seventh alternative embodiment of

the present invention, the opening in the active bearing member 630 for

receiving the crankpin 620 is positioned relative to the exterior surface thereof

682 such that the active bearing member 630 is eccentrically located relative to the crankpin 620 even in the fully retracted position. This results in the

active bearing member 630 always having a degree of eccentricity relative to

shaft 612 such that there is no neutral or zero displacement position. The

embodiment of the present invention shown in FIG. 20 therefore has the

capacity to have a larger maximum displacement than a crank assembly

having a neutral position. Further, the shielding of the hydraulic chamber 684

from the maximum load may be enhanced by the eccentric configuration.

In FIG. 21 , an eighth exemplary embodiment of the present

invention includes an active bearing member 730 with an arcuate

displacement path and an eccentric initial position utilizes a piston 786

traveling along arc A for positioning the active bearing member relative to the

crankpin 720. A short integral connecting rod ending in a sphere projects

from the piston 786 and is received within a mating socket 727 in the crankpin

720 for intermediating between the crankpin 720 and the piston 786 to

determine active bearing member 730 position relative to the crankpin 720.

A conventional connecting rod could also be employed.

FIGS. 22 and 23 show a ninth alternative embodiment of the

present invention wherein a one-piece or monolithic active bearing member

830 has an interior hollow (as defined by surfaces 864, 868, 872 and 874) for

receiving a mating crankpin 820 therein. A pair of plates 831 and 831' (not

shown) are installed over the main bearing journals 816, 818 on either side

of the active bearing member 830 and are held in fluid-tight association with the active bearing member 830 by snap rings 833, 835 received in grooves

in the main bearing journals 816, 818. This configuration provides a sealed

hydraulic chamber divided by the crankpin 820. In the embodiment depicted

in FIG. 22, the crankpin 820 is eccentrically disposed relative to the active

bearing member in the zero displacement position.

FIGS. 24 and 25 show a tenth alternative embodiment of the

present invention wherein the active bearing member 930 is comprised of left

and right mating segments 944 and 946. A pair of plates 931 , 931 ' similar to

plates 831 and 831' sealably embrace the mating segments 944 and 946.

The assembly is held together by fasteners 933, 935.

In FIG. 25, it can be appreciated that the medial line ML relative

to the crankpin 920 is not parallel to the direction of the load vector L at the

crank angle shown. If one assumes that the crank angle depicted is that at

which maximum loading of the crank occurs, one can appreciate that the

misalignment of medial line ML and the load vector L will have the effect of

diverting loading force from the hydraulic fluid trapped between the active

bearing member and the crankpin (used to control the displacement of the

active bearing member) to the active bearing member/crankpin interface.

Thus, in addition to utilizing an arcuate slot in the active bearing member for

shielding the hydraulic fluid, one can also utilize a reoriented medial line ML.

In this manner, at periods of maximum loading in the cycle, the active bearing member 930 can transmit loads mechanically and/or fictionally directly to the

crankpin 920.

FIGS. 26-28 depict an eleventh embodiment of the present

invention wherein a threaded cam rod 1055 is threadedly received within a

sleeve 1053 having a control arm 1057 for holding the sleeve in a fixed

position. The sleeve is inserted into the shaft 1012 of the crankshaft

assembly 1010 via a suitable bore 1051 which permits the sleeve 1053 to

rotate freely within the bore 1051 as the crankshaft assembly is turned and

the sleeve control arm 1057 is held stationary. A bronze bushing, roller

bearing or other friction reducer may be introduced between the sleeve 1053

and the bore 1051. The position of the cam rod 1055 is determined by a cam

controller 1059 which can simply be a lever arm, nob or other end-effector for

rotating the cam rod to a selected position. As the cam rod 1055 is rotated

in a first direction it screws into the sleeve 1053 and it inserts into the

crankshaft assembly 1010 whereupon a tapered tip thereof 1065 contacts a

cam follower 1061. The cam follower presses against the active bearing

member 1030 to determine the position of the active bearing member 1030

relative to the center line of the crankshaft. A spring 1063 eliminates lash

between the crankpin 1020 and the active bearing member 1030. Rotation

of the cam rod 1055 in the opposite direction withdraws it from the assembly

1010 allowing the active bearing member 1030 to assume a position of

decreased eccentricity. FIGS. 29-31 show some of the various mechanical movements

in which the crankshaft of the present invention could be employed. More

specifically, FIG. 29 depicts a scotch yoke mechanism 1171 wherein a shuttle

1173 has a slot 1175 therein for accommodating a crankpin of a crankshaft.

For simplicity of illustration, only main bearing journal 1118 and external

periphery 1182 of the crankpin shell assembly of the present inventive

crankshaft are shown.

In FIG. 30, the present invention is shown in cooperation with

a piston 1277 and connecting rod 1279 arrangement. Again for simplicity of

illustration, only the main bearing journal 1218 and external periphery 1282

of the crankpin shell assembly are shown.

Similarly, in FIG. 31 , the main bearing journal 1318 and the

periphery 1382 of the crankpin shell assembly illustrate the presence of the

crankshaft in a conjugate drive system having a pair of conjugate drivers

1381 , 1383 interacting with mating conjugate bearing surfaces in a conjugate

bearing block 1385. For a more complete description of the nature and

workings of conjugate drive mechanisms, one may refer to certain prior

patents of the present inventor which are incorporated herein by reference,

viz., U.S. Patent Nos. B1 5,259,256; 5,259,256; 5,351 ,567; 5,417,309;

5,445,039 and 5,456,159.

It should be understood that the embodiments described herein

are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the

invention as defined in the appended claims. For example, while a single

throw crank is depicted with a single crankpin between two main bearings,

any number of crankthrows could be employed. The crankpins need not all

be associated with a main bearing, some may be attached to a web that is not

a bearing member, as is conventional in many multithrow crankshafts.

Whereas the present invention has been described above with the active

bearing member position determined by an incompressible liquid, it could also

utilize a gaseous or a gas/liquid fluid under suitable circumstances, i.e., very

low load.

Claims

Claims:

1. A crankshaft, comprising a generally cylindrical shaft; a crankpin

coupled to said shaft; and a crankpin shell disposed about said crankpin, said

shell being radially displaceable to a selected degree of eccentricity relative to said shaft.

2. The crankshaft of Claim 1 , wherein said shell has an interior

hollow of greater volumetric capacity than said crankpin, such that said shell

can be moved on said crankpin.

3. The crankshaft of Claim 2, wherein at least a portion of said

crankpin sealingly engages a first portion of a surface in the interior hollow of

said shell defining at least one chamber of variable volume, said volume of

said chamber depending upon the position of said shell relative to said

crankpin.

4. The crankshaft of Claim 3, wherein said chamber is in fluid

communication with a source of pressurized fluid, such that the inflow of

pressurized fluid into said chamber results in the movement of said shell in a

first direction relative to said crankpin and the outflow results in the movement

of said shell in an opposite direction to said first direction, the position of said

shell establishing a selected degree of eccentricity relative to said shaft.

5. The crankshaft of Claim 4, wherein said chamber is in the form

of a cylinder having an open end and a closed end, and said crankpin includes a piston-shaped projection sealingly received within said open end

of said chamber.

6. The crankshaft of Claim 5, wherein said piston-shaped projection includes a seal ring.

7. The crankshaft of Claim 6, wherein said piston-shaped

projection is a separate piston element attached to said crankpin.

8. The crankshaft of Claim 6, wherein said piston-shaped

projection is monolithic with said crankpin.

9. The crankshaft of Claim 6, further including a plurality of piston-

shaped projections and mating cylinder shaped chambers.

10. The crankshaft of Claim 4, wherein said crankshaft includes a

pair of surfaces extending perpendicular to said crankpin on either side of

said crankpin for forming the sides of said chamber.

11. The crankshaft of Claim 10, wherein said pair of surfaces are

opposing surfaces of a pair of main bearing journals disposed on either side

of said crankpin.

12. The crankshaft of Claim 11 , wherein said pair of surfaces are

opposing surfaces of a pair of crankpin webs disposed on either side of said

crankpin.

13. The crankshaft of Claim 4, wherein said crankpin is coupled to

said shaft via an intermediate member extending radially and generally

perpendicularly relative to said shaft.

14. The crankshaft of Claim 13, wherein said intermediate member

is a crankshaft journal.

15. The crankshaft of Claim 13, wherein said intermediate member

is a crankpin web extending from said shaft to said crankpin.

16. The crankshaft of Claim 4, wherein said fluid is fed to said

chamber via a galley internal to said crankpin.

17. The crankshaft of Claim 16, wherein said generally cylindrical

shaft has a peripheral groove therein, said groove receiving said fluid therein

and communicating with a radial supply galley leading to an axial supply

galley leading to said crankpin galley.

18. The crankshaft of Claim 4, wherein said shell when in a fully

retracted position provides a crankshaft having a stroke of zero.

19. The crankshaft of Claim 18, wherein said shell when fully

deployed to its outward radial limit of travel corresponds to maximum stroke

for said crankshaft.

20. The crankshaft of Claim 4, wherein an external surface of said

shell is cylindrical.

21. The crankshaft of claim 20, wherein said external shell surface

serves to support a connecting rod end.

22. The crankshaft of Claim 4, wherein said shell is in two pieces

removeably fastened together.

23. The crankshaft of Claim 22, further including alignment means

for aligning said two pieces of said shell.

24. The crankshaft of Claim 4, further including a second chamber

of variable volume defined by a second portion of the interior surface of said

interior hollow of said shell in sealing engagement with said crankpin.

25. The crankshaft of Claim 24, wherein said second chamber is

vented to allow fluid to be expressed therefrom.

26. The crankshaft of Claim 24, wherein said second chamber is in

fluid communication with said first chamber and further including fluid control

means for selectively filling said first and second chambers.

27. The crankshaft of Claim 4, wherein said shell interacts with the

slot of the shuttle of a scotch yoke in the manner of a crankpin.

28. The crankshaft of Claim 4, wherein said shell interacts with the

conjugate bearings of a conjugate drive in the manner of a crankpin.

29. The crankshaft of Claim 4, wherein said crankpin is generally

cylindrical with a pair of opposing flat faces along the length of said crankpin

and said shell surface in said interior hollow has a mating pair of flat surfaces

embracing said flat surfaces of said crankpin.

30. The crankshaft of Claim 4, wherein said crankpin is radially

offset in a first dimension and radially centered in a second dimension.

31. The crankshaft of Claim 1 , wherein said shell is displaceable

when said crankshaft is in motion.

32. The crankshaft of Claim 1 , wherein said shell is displaceable

when said crankshaft is in use.

33. The crankshaft of Claim 32, wherein said shell is displaceable

in response to the requirements of the use of said crankshaft.

34. The crankshaft of Claim 33, wherein said shell is displaceable

in response to feedback data.

35. The crankshaft of Claim 22, wherein said pieces are assembled

together along a line perpendicular to the axis of rotation of said crankshaft.

36. The crankshaft of Claim 22, wherein said pieces are assembled

together along a line parallel to the axis of rotation of said crankshaft.

37. The crankshaft of Claim 4, wherein said crankpin has a diameter

which is greater than the diameter of said shaft for enhancing the structural

integrity and load bearing capacity of said crankshaft.

38. The crankshaft of Claim 13, wherein said crankpin has a

diameter which is greater than the diameter of said shaft and the diameter of

said intermediate member for enhancing the structural integrity and load

bearing capacity of said crankshaft.

39. The crankshaft of Claim 4, wherein said crankpin includes a

groove on an outer surface thereof and said shell indicates a mating

projection slidably received in said groove.

40. The crankshaft of Claim 39, wherein said crankpin includes

another groove on an opposite outer surface thereof and said shell includes

another mating projection slidably received in said another groove.

41. The crankshaft of Claim 39, wherein said projection has a dove┬¼

tail shape.

42. The crankshaft of Claim 39, wherein said projection has a box

shape.

43. The crankshaft of Claim 1 , wherein said crankpin shell is

displaced by a mechanical linkage.

44. The crankshaft of Claim 43, wherein said mechanical linkage

includes a cam rod, said crankpin shell position determined by the position of

said cam rod.

45. The crankshaft of Claim 44, further including a cam follower

intermediating between said cam rod and said crankpin shell.

46. The crankshaft of Claim 45, wherein said cam rod inserts into

said generally cylindrical shaft proximate the axis thereof and is displaceable

along said axis and wherein said cam follower is positioned at approximately

a right angle to said cam rod.

47. The crankshaft of Claim 46, wherein said cam rod is threadedly

received within a sleeve freely floating and coaxially positioned in said

generally cylindrical shaft, said sleeve and said cam rod held in a fixed position relative to said generally cylindrical shaft which turns independently

of said sleeve and said cam rod.

48. The crankshaft of Claim 47, wherein said crankshaft includes a

means for biasing said crankpin shell against the direction of increased

eccentricity relative to said shaft.

49. The crankshaft of Claim 3, wherein said at least one chamber

of variable volume is partially defined by opposing arcuate surfaces for

guiding said crankpin shell along an arcuate path relative to said crankpin.

50. The crankshaft of Claim 49, wherein said crankpin has mating

arcuate surfaces thereon having a curvature approximating that of said

opposing arcuate surfaces of said chamber, said mating arcuate surfaces

sliding along said opposing arcuate surfaces.

51. The crankshaft of Claim 4, wherein said chamber is in the form

of an arcuately bent cylinder having an open end and a closed end, and said

crankpin has a piston-shaped projection attached thereto, said projection

sealingly received within said open end of said chamber.

52. The crankshaft of Claim 51 , further including a connecting rod

disposed between said piston-shaped projection and said crankpin.

53. The crankshaft of Claim 52, wherein said two pieces of said

shell assemble along a plane perpendicular to the longitudinal axis of said

crankpin.

54. The crankshaft of Claim 36, further including a pair of endplates

for clamping said crankpin shell therebetween, said endplates completing and

sealing said chamber of variable volume.

55. The crankshaft of Claim 4, further including a pair of endplates

for clamping said crankpin shell therebetween, said endplates completing and

sealing said chamber of variable volume.

56. The crankshaft of Claim 55, wherein said endplates are held in

position relative to said shell by a pair of retainer rings positioned on either

side of said endplates distal to said crankpin shell.

57. The crankshaft of Claim 4, wherein said opposite direction of

movement of said crankpin shell relative to said crankpin is different than the

direction of a force vector operating on said crankpin shell and opposing

rotation of said crankshaft.

58. The crankshaft of Claim 57, wherein said opposite direction is

along an arcuate path.

59. The crankshaft of Claim 57, wherein said opposite direction is

along a linear path skewed relative to said force vector.

60. A method for adjusting the stroke of a crankshaft having internal

galleys for conducting fluid to a crankpin surface, a crankpin shell disposed

about the crankpin, the crankpin shell being hydraulically radially displaceable

to a selected degree of eccentricity relative to the axis of rotation of the

crankshaft, while said crankshaft is rotating, comprising the steps of: a) providing a pressurized fluid to the internal galleys of said

crankshaft;

b) controlling the volume of pressurized fluid provided in

step A to determine the displacement of the crankpin shell.

61. The method of Claim 60, further including the steps of:

c) selecting a particular stroke for said crankshaft;

d) monitoring the position of the crankpin shell;

e) comparing current stroke to the selected stroke;

f) providing additional fluid when current stroke is less than

the selected stroke; and

g) venting fluid to reduce the crankshaft stroke when current

stroke exceeds the selected stroke.

62. The method of Claim 61 , further including the step of changing

the selected stroke as the crankshaft is operated.