Valving for vane damper

A torsion isolator assembly (30) for reducing driveline torsionals includes a vane damper (36) including improved valving (40d, 40e) for increasing the damping factor of the damper, improved spiral springs (32,34 or 80,82) for reducing spring stress primarily due to centrifugal forces, and cam surfaces (44d,44c) for further reducing spring stress due to centrifugal forces.

CROSS REFERENCE 
This application is related to U.S. application Ser. Nos. 07/873,434 having 
Attorney Docket No. 90-rMAR-278, 07/872,876 having Attorney Docket No. 
91-rMAR-511 and 07/872,853 having Attorney Docket No. 92-rMAR-067. All of 
these applications are filed on the same day, all are assigned to the 
assignee of this application and all are incorporated herein by reference. 
FIELD OF THE INVENTION 
This invention relates to a valving arrangement for a hydraulic vane 
damper. More specifically, this invention relates to such a damper 
disposed in parallel with torsion isolator springs for use in a vehicle 
driveline. 
BACKGROUND OF THE INVENTION 
It is well-known that the speed of an Otto or Diesel cycle engine output or 
crankshaft varies even during so-called steady-state operation of the 
engine, i.e., the shaft continuously accelerates and decelerates about the 
average speed of the shaft. The accelerations and decelerations are, of 
course for the most part, a result of power pulses from the engine 
cylinders. The pulses may be of uniform frequency and amplitude when 
cylinder charge density, air/fuel ratio, and ignition are uniform. 
However, such uniformity does not always occur, thereby producing pulses 
which vary substantially in frequency and amplitude. Whether uniform or 
not, the pulses, which are herein referred to as torsionals, are 
transmitted through vehicle drivelines and to passengers in vehicles. The 
torsionals, which manifest themselves as vibrations, are detrimental to 
drivelines and derogate passenger-ride quality. Further, when an engine is 
abruptly accelerated and/or decelerated by accelerator pedal movement or 
other factors, torque pulses ring through the driveline and also derogate 
ride quality, such pulses are herein also referred to as torsionals. 
Since the inception of automobiles, many torsional isolator mechanisms have 
been proposed and used to isolate and dampen driveline torsionals. The 
isolator mechanism proposed in U.S. Pat. No. 5,078,649 includes, as does 
the isolator mechanism herein, flat, long travel spiral springs connected 
in parallel with a vane damper device. Both mechanisms are disposed in a 
torque converter housing and immersed in the pressurized torque converter 
oil therein. U.S. Pat. No. 5,078,649 is incorporated herein by reference. 
The amount of damping (i.e., damping factor) provided by the vane damper 
device in this patent has been considered marginal in some applications 
due to cost and reliability of a valving arrangement therein, and the 
spiral springs therein have also been considered of marginal life 
expectancy due to high stresses in some applications during certain 
operating conditions. The springs disclosed herein may be employed with 
other than vane damper devices and the vane damper device herein may be 
employed with other than spiral springs. 
The isolator mechanism disclosed herein includes features for overcoming 
the above mentioned disadvantages. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a torsion damper device having an 
improved damping factor. 
According to a feature of this invention, a torsion assembly is adapted to 
be disposed for rotation about an axis in a driveline torque converter 
housing filled with an incompressible torque converter fluid. The assembly 
is immersed in the fluid and is drivingly connected between first and 
second rotatably mounted drives. The assembly comprises resilient means 
for transmitting driveline torque between the drives and a hydraulic 
coupling for damping torque fluctuations in response to flexing of the 
resilient means. The coupling includes first and second relatively 
rotatable housing means defining an annular chamber having radially spaced 
apart cylindrical surfaces and first and second axially spaced apart end 
surfaces. The cylindrical surfaces and the first end surfaces are defined 
by the first housing means. Circumferentially spaced apart walls are 
sealing fixed to the first housing means and extend radially and axially 
across the annular chamber for dividing the annular chamber into at least 
two independent arcuate chambers. A piston is disposed in each arcuate 
chamber for driving each arcuate chamber into pairs of first and second 
volumes which vary inversely in volume in response to movement of the 
pistons relative to the first housing means. Each piston has radially 
oppositely facing surfaces in sliding sealing relation with the chamber 
cylindrical surfaces, first and second axially oppositely facing end 
surfaces in sliding sealing relation respectively with the first and 
second end surfaces of chamber, and first and second circumferentially 
spaced apart and oppositely facing surfaces intersecting the first and 
second end surfaces. The second housing means includes an annular radially 
extending housing member having an axially facing surface defining the 
second end surface of the annular chamber. The housing member second end 
surface is in sliding sealing relation with each piston second end 
surface. The housing member is in sliding sealing relation with portions 
of the first housing means, is retained against axial movement in a 
direction away from the first surface of the annular chamber by means 
affixed to the first housing means, and includes a set of 
circumferentially spaced and axially extending through openings. Piston 
drive means connect the pistons to the first drive via a path independent 
of the resilient means. The piston drive means extend through the housing 
member openings with circumferential free play therebetween for allowing 
limited to-and-fro circumferential movement of the pistons relative to the 
housing member, and the piston drive means are connected to each piston at 
a position intermediate the first and second circumferentially facing 
surfaces thereof. Housing drive means connect the first housing means to 
the second drive independent of the resilient means. Passage means effect 
fluid communication of the pairs of volumes with the fluid in the torque 
converter housing. 
The invention is characterized by the passage means including first and 
second recesses in each piston second end surface and respectively 
extending circumferentially in opposite directions from an inlet thereof 
spaced from the drive means by a portion of the piston second end surface 
and to positions respectively communicating with the first and second 
volumes. Each first recess inlet is sealingly covered by the housing 
member second end surface and each second recess inlet opens into the 
associated housing member opening in response to movement of the pistons 
in a direction tending to decrease the first volumes, thereby respectively 
sealing the first volumes from communication with fluid in the torque 
converter housing via the first recesses and communicating the second 
volumes with fluid in the torque converter housing via the second 
recesses. Each second recess inlet is sealingly covered by the housing 
member second end surface and each first recess inlet opens into the 
associated housing member opening in response to movement of the pistons 
in a direction tending to decrease the second volumes, thereby 
respectively sealing the second volumes from communication with fluid in 
the torque converter housing via the second recesses and communicating the 
first volumes with fluid in the torque converter housing via the first 
recesses.

DETAILED DESCRIPTION OF THE DRAWINGS 
The motor vehicle driveline seen schematically in FIG. 1 includes an 
internal combustion engine 10, an automatic transmission 11 and a drive 
shaft 12 driving a load such as rear or front wheels 13 of a vehicle 
through a differential 14. 
The transmission includes a torque converter assembly 15 having an output 
shaft 16 and a gear ratio box 18 driven by the torque converter output 
shaft 16. Torque converter assembly 15 is filled with automatic 
transmission fluid and includes, in known manner, an impeller 20 driven 
from engine 10 through a torque converter housing 22, a stator 24, and a 
turbine 26 driven hydrokinetically by the impeller. A fluid coupling may 
be employed in lieu of a torque converter. 
Torque converter assembly 15 further includes a bypass driveline seen 
generally at 27 in FIG. 1. Bypass driveline 27 is operative when 
selectively actuated to provide a bypass drive between torque converter 
housing 22 and torque converter output shaft 16 through a torsion damping 
isolator assembly 30 thereby bypassing the high slippage drive path 
through the torque converter. 
Referring now to FIGS. 2-6, isolator assembly 30 includes a pair of nested, 
flat, spiral wound springs 32,34 disposed normal to the axis of the 
assembly, and a vane type damper mechanism 36 including housing members 
36,40 defining an annular chamber 42, and a clutch or piston plate 44. 
Plate 44 includes a radially extending portion 44a having an axially 
extending hub portion 44b at its center and an axially extending flange 
portion 44c at its radially outer edge. An outer cylindrical surface of 
hub portion 44b has an inner cylindrical surface of housing member 38 
journaled therein to maintain concentricity between the plate and housing. 
An inner cylindrical surface of hub portion 44b cooperates with an o-ring 
seal 46 carried in an annular recess in an outer surface of an adapter 48. 
The adapter is affixed to torque converter turbine 26 and includes 
internal splines 48a for mating with splines on shaft 16 and external 
splines 48b for slidably mating with splines on housing member 38. 
During non-bypass operation of the torque converter, pressurized 
transmission oil is admitted to the torque converter via a chamber 50 
receiving the oil through passages in shaft 16 in known manner. The oil in 
chamber 50 prevents frictional engagement of plate 44 with a friction 
lining 52 affixed to the shown portion of torque converter housing 22. The 
oil thus flows radially outward in chamber 50 past lining 52 and into the 
torque converter via a main torque converter chamber 54 separated from 
chamber 50 by plate 44. When it is desired to engage the isolator 
assembly, as for example, when the vehicle is operating in a higher gear 
ratio and above a predetermined vehicle speed, the direction of flow of 
the pressurized oil is reversed by actuation of a suitable valve, not 
shown. Specifically, the pressurized oil is now admitted first to chamber 
54 where it acts against the radially extending portion 44a of plate 44 
and slides the entire isolator assembly to the left to frictionally engage 
lining 52. Driveline torque now bypasses the torque converter and is 
transmitted to shaft 16 by spiral springs 32,34 which flex to attenuate 
torsionals in the torque. Damper assembly controls the rate of flexing of 
the springs. 
Annular chamber 42 includes radially spaced apart cylindrical surfaces 42a, 
42b defined by axially extending annular wall portions 38a, 38b of housing 
member 38, and axially spaced apart end surfaces 42c, 42d respectively 
defined by a radially extending portion 38c of housing member 38 and 
housing member 40. Annular chamber 42 is divided into three arcuate 
chambers 56 sealed from each other by fixed vanes or walls 58. The walls 
are press fit into grooves in wall portions 38a, 38b, 38c and extend 
radially and axially across the annular chamber. The radially outer extent 
of axially extending wall 38a includes a radially outwardly extending 
flange 38f and a pair of scroll or spiral shaped pad portions 38g to 
reduce bending stress concentration in the inner convolutions of the 
springs when they decrease in overall diameter due to transmission of 
torque in the positive direction of arrow A. 
Each arcuate chamber 56 is divided into pairs of variable volume chambers 
56a, 56b by moveable vanes or pistons 60. Pistons 60 are each separate 
members but may be affixed together in a manner similar to that in U.S. 
Pat. No. 4,768,637, which patent is incorporated herein by reference. Each 
piston 60 includes radially outer and inner surfaces 60a, 60b in sliding 
sealing relation with housing member cylindrical surfaces 42a, 42b, an 
axially facing end surface 60c in sliding sealing relation with housing 
end surface 42c, and an axially facing end surface 60d in sliding sealing 
relation with end surface 42d of housing member 40. Axial spacing of 
piston end surfaces 60c, 60d between end surfaces 42c, 42d of the chamber 
and between surface 42d and the adjacent ends of walls 38a, 38b is 
controlled and maintained by an annular shim 62 sandwiched between housing 
member 40 and a radially inner portion 64a of an annular flange 64. Flange 
64 abuts the free axial end of housing wall 38a and is affixed to housing 
member 38 by appropriate fasteners, such as by two sets of three fasteners 
65 which extend through openings in flange 64, openings in pad portion 
38g, and opening in flange portion 38f. A radially outer portion 64b of 
flange 64 includes through openings 64c spaced one hundred-eighty degrees 
apart and in axial alignment with openings 38h in flange portions 38f. 
Housing member 40 includes outer and inner circumferential surfaces 40a, 
40b in sliding sealing relation with cylindrical wall surfaces 42a, 42b, 
and three circumferentially spaced apart elongated through openings 40c 
which loosely receive round pin lugs 66 fixed at one end to clutch plate 
44 and at the other end are slidably received in recesses 60e in the 
pistons. Since pistons 60 are separate members, lugs 66 position and fix 
the circumferential spacing of the pistons relative to each other. The 
view of housing member 40 in FIG. 4 is looking rightward with pin lugs 66 
in section and pistons 60 shown in phantom lines behind member 40. 
Pistons 60 each include circumferentially oppositely facing surfaces 60f, 
60g and porting recesses 61,63 for directing pressurized make-up oil from 
the torque converter chamber 54 into variable volume chambers 56a, 56b. 
The porting recesses extend circumferentially in opposite directions from 
an inlet end 61a, 63a thereof to an outlet end thereof in direct 
communication with chambers 56a, 56b. The circumferential free play 
between pin lugs 66 and through openings 40c allows suffice limited 
circumferential movement of the pistons relative housing member 40 for 
surface 46d to sealingly cover one set of the porting recess and uncover 
the inlet ends of the other set in response to torque in either direction. 
Each inlet 61a, 63a is spaced from the pin lugs 66 or piston pin lug 
recesses 60e by portions of piston surface 60d which cooperate with 
housing member surface 40d to seal the inlets from communication with 
make-up oil via the openings 40c. As seen by use of phantom lines in FIG. 
3, porting recess inlets 61a are sealing covered by housing member surface 
40d, and porting recess inlets 63a are uncovered and open into housing 
member openings 40c when torque transmission is in a direction tending to 
decrease volumes 56a and increase volumes 56b, thereby sealing volumes 56a 
from communication with the pressurized oil in torque converter chamber 54 
via porting recesses 61 and communicating the pressurized make-up oil to 
volumes 56b via recesses 63a. FIG. 4, which is viewed in a direction 
opposite the direction of FIG. 3, illustrates the position of the pistons 
and housing member 40 when torque transmission is in a direction tending 
to decrease volumes 56b and increase volumes 56a. Pistons 60 are 
preferably formed in known manner of compacted powered metal with piston 
pin recesses 60e and porting recesses 61,62 being formed during the 
compacting process. 
In vane damper 36, as thus far described, pin lugs 66 are received in 
piston recesses 60e with little or no clearance therebetween. 
Alternatively, pin lugs 66 and piston recesses 60e may have additional 
clearance or free play therebetween so as to provide a lost motion between 
piston plate 44 and pins 66 for providing a non-hydraulic damping zone of 
1 or 2 or more rotational degrees. Herein, as shown in FIG. 7, the 
clearance is provided by reducing the diameter of a portion 66a of the pin 
lugs received in piston recesses 60e. 
Spring convolutions 32,34 respectively include radially outer ends 32a, 34a 
and radially inner ends 32b, 34b. The ends may be attached in any of 
several known ways, e.g., such as disclosed in previously mentioned U.S. 
Pat. No. 5,078,649. Herein it should suffice to say that outer ends 32a, 
34a are pivotally secured to the radially outer extent of clutch plate 44 
by pins 68 and brackets 70, and with the pins locked in place by unshown 
split pins in known manner. The inner ends 32b, 34b of the springs are 
secured to housing member 38 by pins 72 extending through axially aligned 
openings 64c, 38h and are locked in place in the same manner as pins 68. 
When the springs are transmitting positive torque and tending to wind up, 
pivotal movement of the spring ends 32b, 34b is limited by scroll pads 
38g. When the springs are transmitting negative torque or being acted on 
by centrifugal forces and therefore tending to unwind or expand radially 
outward, pins 72 allow free pivotal movement of spring inner ends 32b, 
34b. Herein, maximum wind-up or unwinding of the spiral spring 
convolutions is limited by engagement of piston surfaces 60f, 60g with 
walls 58. By way of example, wind-up is limited to +52 degrees and 
unwinding is limited to -25 degrees. The springs are shown in the relaxed 
state in FIG. 3. 
The spiral spring convolutions disclosed in previously mentioned U.S. Pat. 
No. 5,078,649 have a shape commonly referred to as a spiral of Archimedes 
wherein each convolution curve is generated by a point moving away from or 
toward a fixed point at a constant rate while the radius vector from the 
fixed point rotates at a constant rate and that has the equation 
.rho.=a.theta.in polar coordinates. The convolutions formed according to 
this equation increase in radius at a constant rate and have all radially 
adjacent surfaces radially spaced the same distance apart. 
The flex range of such spiral springs readily allow substantial relative 
rotation between the shafts they interconnect and, therefore, are 
considered well suited for torsion isolator mechanisms since they allow a 
damping device connected in parallel therewith to have a long travel for 
more smoothly damping torsionals. However, high stresses acting at several 
locations along the length of the convolutions has limited use of such 
springs in torsion isolator mechanisms in applications subjecting the 
springs to relatively high spin speeds and torque loads encountered in 
automotive vehicles. 
The spiral spring convolutions 32,34, which have substantially the same 
circumferential length (.apprxeq.720 degrees) and cross-sectional 
dimensions as the springs in the above mentioned patent, are modified to 
reduce stress thereon due to torque transmission and due to centrifugal 
forces acting thereon. Also, flange 44c of plate 44 is provided with cam 
surfaces 44d, 44e circumferentially extending between the outer ends of 
the convolutions to further reduce stress on the convolutions due 
primarily to centrifugal forces encountered during relatively high spin 
speeds while transmitting little or no torque to a load. 
The spring modification consists of forming the convolution such that 
radially adjacent surfaces of radially outer portions of the nested 
convolutions have a lesser radial spacing therebetween than do radially 
inner portions of the convolutions. This is accomplished, using the spiral 
of Archimedes equation, by forming the first half or three hundred-sixty 
degrees of the convolutions from inner ends 32b, 34b with a greater rise 
rate than the remainder or outer lengths of the convolutions. 
Alternatively, the spiral of Archimedes equation may be modified to 
provide convolutions which uniformly decrease in rise rate to provide 
closer spacing of the outer convolutions. One example of such an equation 
is given by .rho.=a (.theta.).theta. wherein the coefficient "a" is now a 
function of .theta. rather than a constant. Springs 80, 82 in FIG. 8 are 
an example of springs formed according to this governing equation. 
Stresses due primarily to high spin speeds are reduced by radially inwardly 
facing cam surfaces 44d, 44e having spiral profiles extending 
substantially the full circumferential distance between outer ends 32a, 
34a or attachment pins 68. When two nested springs are used, the 
circumferential distance is approximately one hundred and eighty degrees. 
The cam surfaces are positioned to be engaged by the adjacent radially 
outwardly facing surface of the associated convolutions in response to 
centrifugal forces acting on the springs. The cam surfaces limit radial 
outward movement of the convolutions due to the centrifugal forces and 
provide smooth reaction surfaces substantially conforming to the spiral 
shapes of the convolutions extending between the outer ends of the 
convolutions. 
The graph of FIG. 9 illustrates stress along the length of the spiral 
convolutions by a curve A for a baseline spring having the same radial 
spacing between the nested convolutions and having cam surfaces extending 
about half the distance between the outer ends of the convolutions, by a 
curve B for the baseline springs with full cam surfaces 44d, 44e according 
to FIG. 3, and-by a curve C for the modified spring of FIG. 6 with the 
full cam surfaces. Stress curves A,B and C represent stress at the 
indicated positions along the length of the convolutions with the isolator 
mechanism not connected to a load and operating at 7000 rpm with the 
springs flexed to the -25 degrees position, such condition being 
considered a worse case condition for stress due to centrifugal forces. 
The graph of FIG. 9 also illustrates stress along the length of the spiral 
convolutions by a curve D for the baseline springs at zero rpm and flexed 
to the +52 degree position, and by curve E for the modified springs of 
FIG. 5 at zero rpm and flexed to the +52 degree position. 
While the embodiments of the present invention have been illustrated and 
described in detail, it will be apparent that various changes and 
modifications may be made in the disclosed embodiments without departing 
from the scope or spirit of the invention. The appended claims are 
intended to cover these and other modifications believed to be within the 
spirit of the invention.