US 5,240,457 AGrant
Sealing Arrangement for a Torque Converter Vane Damper
Issue Date:1993-08-31
•8 Claims
•3 Drawing Sheets
Abstract
A torsional isolator assembly for reducing driveline torsionals includes a vane damper (36) having valving (40d,40e or 161,163) and chamfers (200,201) on pistons (60 or 160). These chamfers (200,201) aid in forming a seal between a surface (42d or 142d) by creating a hydrodynamic film that biases the piston (60 or 160) toward the housing surface (42d or 142d).
Metadata
Assignee
- Eaton Corporation
Inventors
- Wayne K. Leichliter
- Ben S. Juday
Application Information
Application Number:US 968123&
Filing Date:1992-10-29
Priority Date:1992-10-29
Art Unit:245
Classifications
IPC:
F16D 380
Field of Search:
46419224;27;57-603.28;3.29;3.33;106.1
Patent Drawings (3 sheets)
Description
Cross Reference
This application is related to U.S. application Ser. Nos. 07/872,860 and 07/873,434, filed Apr. 23, 1992, and both assigned to the assignee of this application.
Field of the Invention
This invention relates to a hydraulic vane damper disposed in parallel with torsion isolator springs for use in a vehicle driveline. More specifically, this invention relates to reducing oil leakage from the hydraulic vane damper.
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 averages 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 valving arrangements employed therewith and leakage of oil from the working chambers of the damper. 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, has first and second axially oppositely facing end surfaces in sliding sealing relation respectively with the first and second end surfaces of chamber, and has first and second circumferentially spaced apart and oppositely facing surfaces, respectively intersecting the first and second oppositely facing 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. 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 improvement is characterized by the passage means including openings extending through the housing member for communicating the torque converter fluid with each volume via first and second paths associated respectively with the first and second volumes. Portions of the sealing relation between the pistons and the housings are movable to positions blocking the first paths and unblocking the second paths in response to flexing of the resilient means in a direction tending to decrease and increase the first and second volumes respectively. The portions are movable to positions blocking the second paths and unblocking the first paths in response to the flexing tending to decrease and increase the second and first volumes, respectively. At least one of the intersections of each piston first and second circumferentially facing surfaces with the piston end surface includes a chamber for promoting generation of a hydrodynamic film with the fluid for biasing each piston toward the chamber second end surface and for increasing the sealing relation between each piston second end surface and the chamber second end surface.
Brief Description of the Drawings
The torsion isolator assembly of the present invention is shown in the accompanying drawings in which:
FIG. 1 schematically illustrates a motor vehicle driveline including a torque converter type transmission employing a torque converter bypass drive embodying the torsion isolator assembly;
FIG. 2 is a detailed sectional view of the isolator assembly looking along staggered section line 2--2 of FIG. 3;
FIG. 3 is a reduced size detailed sectional view of the isolator assembly looking along staggered section line 3--3 of FIG. 2;
FIG. 4 is a sectioned view of a portion of the isolator mechanism looking leftward in FIG. 2;
FIG. 5 is a sectional view of a modified portion of the isolator mechanism;
FIG. 6 is a reduced size detailed sectional view of an alternative embodiment of the isolator assembly;
FIG. 7 is a sectioned view of a portion of the isolator mechanism in FIG. 6 and looking leftward as in FIG. 2;
FIG. 8 is a relief view of a piston in the isolator assembly of FIG. 6; and
FIG. 9 is a sectional view of a portion of the isolator assembly looking along line 9--9 of FIG. 7.
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. 2-4, 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 38,40 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 portion 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 portion 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 openings in flange portions 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 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 leftward in the direction of surface 42d thereof with pin lugs 66 in section and pistons 60 superimposed on surface 42d in phantom lines.
Pistons 60 each include circumferentially oppositely facing surfaces 60f,60g which cooperate with three pairs of restricted passages 40d,40e extending axially through housing member 40 for communication of pressurized makeup oil from torque converter chamber 54 into variable volume chambers 56a,56b. Each pair of passages are circumferentially spaced apart a sufficient distance determined by the circumferential spacing of piston surfaces 60f,60g, and the amount of circumferential free play between pin lugs 66 and through openings 40c. The circumferential free play allows sufficient limited circumferential movement of the pistons relative to housing member 40 for piston end surfaces 60d to close or block the passages associated with variable volume chambers which, at any given time, are decreasing in volume, and for the piston end surfaces 60d to move to positions opening or unblocking the passages associated with variable volume chambers which, at any given time, are increasing in volume.
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. 5, the clearance is provided by reducing the diameter of a portion 66a of the pin lugs received in piston recesses 60e.
Restricted passages 40d,40e in housing member 40 may be made larger than shown herein to allow a greater rate of oil flow therethrough and/or to allow forming of the passages by a low cost punching process rather than by drilling. If the enlarged passages are wider in the circumferential direction of movement of pistons 60, the circumferential free play between pin lugs 66 and housing member through openings 40c should be increased to ensure sufficient relative rotation of pistons 60 relative to housing member 40 to provide complete opening and closing of the passages by piston end faces 60d.
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 32 b,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.
FIGS. 6-9 illustrate an alternative embodiment for controlling supply of makeup fluid to variable volumes 56a,56b and the addition of chamfers on edges of the pistons for promoting generation of a hydrodynamic film at one end of each piston. Elements in FIGS. 6-8 which are substantially the same as in FIGS. 2-4 have the same reference number with a "1" prefix.
Housing member 140 includes outer and inner circumferential surfaces 140a,140b and three circumferentially spaced apart elongated through openings 141 which loosely receive round pin lugs 166 fixed at one end to the clutch plate and at the other end are slidably received in recesses 160e in the pistons. Openings 141 may be round as in FIGS. 2-4.
Pistons 160 each include circumferentially oppositely facing surfaces 160f,160g and porting recesses 161,163 for directing pressurized makeup oil from the torque converter chamber into variable volume chambers 156a,156b. The porting recesses extend circumferentially in opposite directions from an inlet end 161a,163a thereof to an outlet end thereof in direct communication with variable volume chambers 156a,156b. The circumferential free play between pin lugs 166 and through openings 141 allows limited circumferential movement of the pistons relative housing member 140 for surface 142d 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 161a,163a is spaced from the pin lugs 166 or piston pin lug recesses 160e by portions of piston surface 160d which cooperate with portions of housing member surface 142d to seal the inlets from communication with makeup oil via the openings 141. As seen in FIG. 9, porting recess inlets 163a are sealingly 14 covered by housing member surface 142d , and porting recess inlets 161a are uncovered and open into housing member openings 141 when torque transmission is in a direction tending to decrease volumes 156a and increase volumes 156b, thereby sealing volumes 156a from communication with the pressurized oil in torque converter chamber via porting recesses 161 and communicating the pressurized makeup oil to volumes 156b via recesses 163a. FIG. 7, which is viewed in a direction opposite the direction of FIG. 6, illustrates the position of the pistons and housing member 140 when torque transmission is in a direction tending to decrease volumes 156b and increase volumes 156a. Pistons 160 are preferably formed in known manner of compacted powered metal with piston pin recesses 160e and porting recesses 161,162 being formed during the compacting process.
As may be seen by reference to FIG. 9, the intersections of the piston circumferentially facing surfaces 160f,160g with piston end surface 160c are provided with chamfers 200,201 to promote generation of a hydrodynamic fluid film between piston end surface 160c and chamber surface 142c. The chamfering feature, of course, may be employed in the embodiment for FIGS. 2-4. The fluid film biases the piston toward chamber surface 142d, thereby improving the sealing relation between chamber surface 142d and piston end surfaces 160d for reducing leakage of fluid therealong from the variable volume chambers tending to decrease in volume (i.e., the chambers having fluid at relatively high pressure) to openings 141, and with reference to FIG. 2 to also reduce leakage across the interface of shim 62 with flange 64 and housing member 40. The angle .crclbar. of chamfer surfaces 200,201 is shown substantially greater than need be in practice. For example, satisfactory test results have been obtained with angles of about five degrees and openings X provided by the chambers of about 0.4 millimeters. Further, both intersections need not be chamfered if improved sealing is required in only one direction. Also, the chamfers need not extend the full length of the intersection and the chamfers need not be flat surfaces (i.e., the chamfers may be formed by rounding the intersections).
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.
Claims
What is claimed is:
1. A torsion isolator assembly adapted to be disposed for rotation about an axis in a driveline torque converter housing filled with an incompressible torque converter fluid, the assembly immersed in the fluid and drivingly connected between first and second rotatably mounted drives; the assembly comprising 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 including 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 surface defined by the first housing means, and circumferentially spaced apart walls sealingly fixed to the first housing means and extending radially and axially across the annular chamber for dividing the annular chamber into at least two independent arcuate chambers; a piston disposed in each arcuate chamber for dividing 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 having radially oppositely facing surfaces in sliding sealing relation with the chamber cylindrical surfaces, having first and second axially oppositely facing end surfaces in sliding sealing relation respectively with the first and second end surfaces of the chamber, and having first and second circumferentially spaced apart and oppositely facing surfaces respectively intersecting the first and second oppositely facing end surfaces; the second housing means including an annular radially extending housing member having an axially facing surface defining the second end surface of the annular chamber, the second end surface being in sliding sealing relation with each piston second end surface, the housing member being in sliding sealing relation with portions of the first housing means and retained against axial movement in a direction away from the first end surface of the annular chamber by means affixed to the first housing means, and the housing member having a set of circumferentially spaced and axially extending through openings; piston drive means for connecting the pistons to the first drive via a path independent of the resilient means, the piston drive means extending 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; housing drive means for connecting the first housing means to the second drive independent of the resilient means; and passage means for effecting fluid communication of the pairs of volumes with the fluid in the torque converter housing; characterized by: the passage means including fluid passages extending through the housing member for communicating the torque converter fluid with each volume via first and second paths associated respectively with the first and second volumes, portions of the sealing relation between the pistons and the housing movable to positions blocking the first paths and unblocking the second paths in response to flexing of the resilient means in a direction tending to decrease and increase the first and second volumes respectively, and the portions movable to positions blocking the second paths and unblocking the first paths in response to the flexing tending to decrease and increase the second and first volumes, respectively; and at least one of the intersections of each piston first and second circumferentially facing surfaces with the piston end surface including a chamfer for promoting generation of a hydrodynamic film with the fluid for biasing each piston toward the chamber second end surface and for increasing the sealing relation between each piston second end surface and the chamber second end surface.
2. The torsion isolator assembly of claim 1, wherein: both of said intersections include said chamfer for promoting the generation of the hydrodynamic film.
3. The torsion isolator assembly of claim 1, wherein: the fluid passages of the passage means include a first and a second passage respectively being the first and second paths and associated with each piston for respectively communicating the first and second volumes with the fluid in the torque converter housing, the first and second passages respectively blocked and unblocked by the second end surface of the associated piston in response to said flexing in a direction tending to decrease the first volumes, and the second and first passages respectively blocked and unblocked by the second end surface of the associated piston in response to said flexing in a direction tending to decrease the second volumes.
4. The torsion isolator assembly of claim 3, wherein: the resilient means comprises at least two flat spiral wound springs having nested spiral convolutions, each convolution including a radially outer end secured to the piston drive means and a radially inner end secured to the first housing means.
5. The torsion isolator assembly of claim 3, wherein: both of said intersections include said chamfer for promoting the generation of the hydrodynamic film.
6. The torsion isolator assembly of claim 1, wherein: the fluid passages of the passage means are defined by the housing member openings and the first and second paths include 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 sealingly covered by the housing member second end surface and each second recess inlet opening 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, and each second recess inlet sealingly covered by the housing member second end surface and each first recess inlet opening 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.
7. The torsion isolator assembly of claim 6, wherein: the resilient means comprises at least two flat spiral wound springs having nested spiral convolutions, each convolution including a radially outer end secured to the piston drive means and a radially inner end secured to the first housing means.
8. The torsion isolator assembly of claim 6, wherein: both of said intersections include said chamfer for promoting the generation of the hydrodynamic film.