The present invention generally relates to launch devices used in connection with automotive vehicle powertrains. More specifically, the invention relates to a launch device, such as a torque converter, used in connection with an automatic transmission of an automotive vehicle.
Generally, vehicles with automatic transmissions utilize a torque converter, or launch device, to couple the output of the engine or motor with the input of the automatic transmission. The torque converter is connected to the flex plate of the engine/motor and rotates with the flex plate. This rotation drives the impeller (also sometimes referred to as a pump) of the torque converter, which may be formed unitarily or integrally with the torque converter's shell or cover. The impeller includes blades (or vanes) that drive a fluid retained within the shell. Driven by the impeller, the fluid is transferred from the blades of the impeller to the blades of a turbine, causing rotation of the turbine. This rotational output of the turbine is then coupled to the input of the automatic transmission.
To enable torque multiplication, a stator is located between the impeller and the turbine. The stator, which is mounted on a one-way clutch, redirects fluid from the turbine back to the impeller. This redirection of the fluid is conducted in such a manner that it results in a multiplication of the torque.
Presented in
Internally, the rear cover 906 is provided with a series of blades or vanes 908 so as to form the impeller 910. During rotation of the impeller 910, hydraulic fluid received through flow paths from the automatic transmission is centrifugally forced outward, then forward to impact against opposing blades 912 of the turbine 914. In
The shape of the turbine's blades 912 causes both rotation of the turbine 914 and redirection of the fluid. This redirection is both inward and back to the impeller 910. The turbine 914 is also mounted to a hub 916, which is in turn mounted to an input shaft (not shown) of the automatic transmission.
Positioned between the lower portions of the blades 908 of the impeller 910 and the blades 912 of the turbine 914 is a stator 918. The stator 908 receives hydraulic fluid being returned to the impeller 910 and redirects the fluid. This redirection is conducted in such a manner that it does not impede rotation of the impeller 910.
Forward of the turbine, between the turbine 914 and the front cover 902, the torque converter 900 also includes a rotational damper 920 and a lockup clutch assembly 922, of which the lockup clutch assembly 922 is forward most on the engine side of the torque converter 900.
Relative rotation between hubs of the rear cover 906, stator 918 and turbine 914 is permitted in the torque converter 900 by inclusion of axial thrust bearings, which may include roller balls or cylinders as the rolling elements.
During operation of the torque converter 900, as the engine speed increases, the fluid pressure inside the torque converter 900 similarly increases. Along with the increased fluid pressure, the hydrodynamic function of the fluid coupling between the impeller 910 and the turbine 914 causes the components within the torque converter 900 to experience an axial thrust load causing them to axially separate. This separation in turn causes the overall package of the torque converter shell 924, formed by the front and rear covers 902, 906 to expand or balloon. In some applications, the torque converter 900 may expand up to 2 mm. Since this expansion must be accommodated on both the engine and transmission sides of the torque converter, a total of 4 mm of axial expansion must be accounted for in protecting the torque converter 900.
To control this expansion, the front and rear covers 902, 906 are provided with a thickness that is sufficient to limit overall expansion to typically not more than 2 mm. The specific thickness of the front and rear covers 902, 906 depends on the particular application in which the torque converter 900 is used. However, in all applications, the increased thickness increases both the weight and the package size of the torque converter 900, which is contrary to the design optimization of the torque converter 900.
In overcoming the drawbacks and limitations of the known technology, launch device's embodying the principles of the present invention allow for light weighting and package size reduction while still controlling the expansion of the launch to not more than 2 mm. Through the teachings of the present disclosure, expansion of the torque converter can be controlled while allowing for a decrease in the thickness of the front and rear covers, resulting in the above-mentioned weight and package size reduction.
In one aspect of the invention, a launch device is provided including features that limit axial expansion of the launch device's shell.
In another aspect, a launch device is provided for coupling the rotary output of a prime mover to the rotary input of an automotive transmission. The launch device includes a front cover configured for connection to the rotary output of the prime mover, and a rear cover fixedly connected to the front cover and rotatable with the front cover. The front cover and the rear cover cooperate to form a shell defining chamber. Extending into the shell is an impeller having a plurality of impeller blades and being connected to one of the front and rear covers. A turbine is located in the shell and being supported for rotation relative to the shell. The turbine includes a plurality of turbine blades generally opposing the impeller blades and shaped to receive fluid from the impeller blades thereby causing rotation of the turbine. The turbine blades also redirect the fluid back toward the impeller. An output hub is rotatably supported with in the shell and coupled to the turbine wherein rotation of the turbine causes rotation of the output hub about a central axis. The output hub is configured to connect with the rotary input of the automotive transmission. A plurality of pull bearings constructively support the shell for relative rotation with respect to one or more internal components of the launch device. The pull bearings each include a rolling element between inner and outer races. Portions of the pull bearings are fixed relative to an associated one of the internal components of the launch device and limit axial movement of the inner and outer races relative to one another along the central axis, thereby limiting axial expansion of the shell.
In another aspect, one of the pull bearings constructively supports the front cover relative to first internal component of the launch device.
In a further aspect, one of the pull bearings constructively supports the rear cover relative to first of the internal components.
In an additional aspect, a first pull bearing constructively supports the front cover relative to a first internal component of the launch device, a second pull bearing constructively supports the rear cover relative to a second internal component of the launch device and a third pull bearing constructively supports the first internal component relative to the second internal component.
In still another aspect, the first internal component is the output hub.
In a further aspect, the first, second and third pull bearings are axial bearings.
In an additional aspect, the rolling elements are cylindrical elements.
In another aspect, the rolling elements are needle elements.
In yet a further aspect, the rolling elements are ball bearings.
In an additional aspect, the pull bearings are supported on a radial surface of the output hub.
In another aspect, the radial surface is in inner radial surface of the output hub.
In a further aspect, the pull bearings include portions axially fixed to the associated ones of the internal components by welds.
In still an additional aspect, the portions axially fixed to the associated ones of the internal components are inner and outer races of the pull bearings.
In yet another aspect, the pull bearings include portions axially fixed to the associated ones of the internal components by snap rings.
In still a further aspect, the portions axially fixed to the associated ones of the internal components are bearing supports, the bearing supports supporting the inner and outer races of the pull bearings.
In another aspect, the launch device further includes an isolation damper and a lockup clutch assembly, the isolation damper being supported with the turbine on the output hub.
In an additional aspect, a turbine isolation damper and a lockup clutch assembly are also provided, wherein the turbine isolation damper includes a free portion connected to free portion of the turbine and supporting the turbine therethrough.
In still another aspect, the free portion of the turbine isolation damper is coupled to a spring plate, and the spring plate is supported by the output hub.
Referring now to the drawings, a launch device embodying the principles of the present invention is generally illustrated in, and will be described with reference to, the drawing seen in
Terms concerning attachment of structures and components, such as “coupled,” “attached,” “connected,” “joined,” “mounted” or “interconnected” refer to a relationship where the structures are secured or attached to one another either directly or indirectly through an intervening structure, unless specifically indicated otherwise. These attachments and relationships may be movable or rigid, unless indicated otherwise. “Integral” means that multiple elements are connected together so as to form one unit. “Unitary” means a single, one piece element. Thus, the term “unitary” is to be distinguished from the term “integral.”
Throughout the various figures, like elements are designated with like reference numerals to aid in understanding of the commonality of the like elements.
Referring now to
Internally, the rear cover 16 is provided with a series of blades or vanes 20 so as to form an impeller 18. During rotation of the rear cover 16 and impeller 18, hydraulic fluid is supplied from the automatic transmission along a first pathway and is forced radially outwardly under the centrifugal force of the rotating impeller 18 and blades 20. The shape of the blades 20 and the inner surface of the rear cover 16 cooperate to further direct the hydraulic fluid toward of front cover 12. In
Immediately forward of the impeller 18, the launch device 10 includes a turbine 22. The turbine 22 is mounted to a hub 24, and the hub 24 is connected to a rotatable input shaft 26 of the automatic transmission of the automotive vehicle. As seen in
Similar to the impeller 18, the turbine 22 also includes a series of blades 28. The blades 28 of the turbine are oriented to receive the hydraulic fluid from the impeller 18, and the force of the hydraulic fluid from the impeller 18, in cooperation with the shape of the blades 28 of the turbine, rotationally drives the turbine 22. This rotation is in the same direction as the rotational direction of the impeller 18. Hydraulic fluid received by the turbine 22 is then redirected downward and rearward, back toward the impeller 18.
Position between the lower portions of the blades 20 of the impeller 18 and the blades 28 of the turbine 22 is a stator 30. The stator 30 receives the hydraulic fluid being returned from the turbine 22 toward the impeller 18. The stator 30 further redirects the fluid so that it is in the same rotational direction as the impeller 18. This redirection is conducted in such a manner that it is efficiently received by the impeller 18 and does not impede rotation of the impeller 18. With this fluid coupling, rotation from the output of the engine is transformed into rotation of the input shaft 26 of the automatic transmission.
Integrated with the stator 30 is a one-way clutch assembly 50 that limits the directional rotation of the stator 32 to a single direction. The one-way clutch assembly 50 includes an outer race 52, upon which the stator 30 is supported, and an inner race 54. The inner race 54 of the one-way clutch assembly 50 is mounted upon a fixed, nonrotating support shaft 56 associated with the input of the automatic transmission. In the interest of brevity and since one-way clutch assemblies are well known in the technological field of the present invention, the one-way clutch assembly 50 of the present launch device 10 is not and need not be explained in any greater detail herein. Those skilled in the art will really appreciate the construction and operation thereof.
Forward of the turbine 22, between the turbine 22 and the front cover 12, the launch device 10 includes an isolation damper 32. The isolation damper 32 is commonly mounted to the hub 24 with the turbine 22. The isolation damper 32 absorbs variations in the rotation speed of the front and rear covers 12, 18 to provide for smoother operation of the automatic transmission and the transmitting of less vibration to the occupant of the vehicle. Isolation dampers are well known in the technological field of the present invention. Accordingly, the isolation damper 32 of the launch device 10 is not discussed in detail herein, except as necessary.
Between the isolation damper 32 and the front cover 12, the launch device 10 additionally includes a lockup clutch assembly 34. The piston 35 of the lockup clutch assembly 34 is axially moveable so as to engage the inner surface of the front cover 12, which is effective to lock rotation of the input shaft 26 of the transmission with the rotation of the front cover 12. Like isolation dampers, lockup clutch assemblies of this type are well known in the technological field of the present invention. Accordingly, the lockup clutch assembly 34 is discussed herein as is necessary, but is not in significant detail herein.
During operation of the launch device 10, in the clutch open mode, hydraulic fluid is received along one or more passageways (not shown) formed in the input shaft 26 of the transmission, flows through bearing 44 and into a chamber 37 located between the piston 35 of the lockup clutch assembly 34 and the front cover 12. During this clutch open mode, pressure in this chamber 37 is greater than chambers elsewhere in the launch device 10, keeping the piston 35 spaced from the front cover 12 and keeping the lockup clutch assembly 34 open.
From chamber 37, fluid flows radially around the distal end of the piston 35 and into a circumferential chamber 38, generally defined between the radial or perimetric sides of the front and rear covers 12, 16 and the turbine 22. Some of this fluid passes from the circumferential chamber 38 into the hydrodynamic torus space between the impeller 18 and the turbine 22. This fluid operates with the impeller 18 and turbine 22 to define a fluid coupling within the launch device 10. Hydraulic fluid also passes from the fluid coupling into pathway 40, through another bearing 44 and exits the launch device 10 through a passage 42, defined between the non-rotation support shaft 56 and a hub 57 to which the rear cover 16 is fixedly secured.
Flow in the reverse direction initially operates to close the lockup clutch assembly 34. In this situation, pressure in the circumferential chamber 38 and between the turbine 22 and piston 35 is greater than pressure in chamber 37. As a result, the piston 35 axially moves along the outer radial surface 23 of an axial hub extension of the outer hub flange 24b. Once in the clutch closed mode, the only path of hydraulic fluid flow is leakage or seepage through the lining material of the lockup clutch assembly and/or various oil seals, such as the seal 51 between piston 35 and the outer radial surface 23 of the outer hub flange 24b.
It should be noted that the above described fluid flow is for the illustrated launch device 10. The exact fluid flow can and will vary based manufacturer preferences and the specific design criteria of the associated launch device.
As mentioned above, during operation of the launch device 10, engine speed increases. With this increase in engine speed, the axial forces and thrust loads generated by the hydrodynamic function of fluid coupling, as well as the increased fluid pressure within the launch device 10, will operate to cause axial expansion of the launch device 10.
To control and limit expansion induced by the hydraulic function and increased pressure, the launch device 10 of the present disclosure incorporates what are herein referred to as pull bearings 44. The integrated pull bearings 44 limit and/or prevent axial expansion of the launch devices shell by accepting the axial forces of the hydraulic function and increased pressure.
As seen in
As will be readily appreciated by those skilled in the technological field of this disclosure, the pull bearings 44 may adopt other configuration, such as being radially oriented or provided with different roller elements (such as ball bearings, etc.), so long as the above functionality is maintained. The above general construction applies to each of the pull bearings 44 discussed below.
A first one of the pull bearing 44a is constructively arranged between the front cover 12 and the hub 24 that supports the turbine 22. More specifically, the pull bearing 44a is positioned between an inner radial surface of the outer hub flange 24b and an outer radial surface of an alignment stub 13 that is fixedly secured to the front cover 12 via a weld or other means and that extends into the torque converter's shell. To position the pull bearing 44a, outer and inner bearing supports 60, 62 are respectively mounted via axial portions to the inner and outer radial surfaces of the outer hub flange 24b and the alignment stub 13, and retained by snap rings 64 located in corresponding grooves formed in the axial portions of the bearing supports 60, 62 and in the inner and outer radial surfaces of the outer hub flange 24b and alignment stub 13. The outer race 48 of the first pull bearing 44a is accordingly positioned on a radial portion of the outer bearing support 60 and the inner race 46 is positioned on a radial portion of the inner bearing support 62.
A second pull bearing 44b is arranged between the hub 24 supporting the turbine 22 and the hub forming the inner race 54 of the one-way clutch assembly 50. More specifically, the pull bearing 44b is positioned between an inner radial surface of the inner hub flange 24a and an outer radial surface of the inner race 54. Like the first pull bearing 44a, the second pull bearing 44b is positioned by outer and inner bearing supports 60, 62 respectively mounted via axial portions to the inner and outer radial surfaces of the inner hub flange 24a and the inner race 54 of the one-way clutch assembly 50, and retained by snap rings 64 located in corresponding grooves formed in the axial portions of the bearing supports 60, 62 and in the inner radial surface of the inner hub flange 24a and an outer radial surface of the inner race 54. The outer race 48 of the second pull bearing 44b is accordingly position on the radial portion of the outer bearing support 60 and the inner race 46 is positioned on the radial portion of the inner race 54.
A third pull bearings 44c is constructively arranged to between the impeller 18, including the rear cover 16, and the hub forming the inner race 54 of the one-way clutch assembly 50. More specifically, the pull bearing 44c is positioned between an outer radial surface of the and the hub forming the inner race 54 and an inner radial surface of an extension of the hub 57 to which the rear cover 16 is fixedly secured, via a weld or other means, and which extends into the torque converter's shell. To position the pull bearing 44c, outer and inner bearing supports 60, 62 are likewise employed and respectively mounted via axial portions thereof to the inner and outer radial surfaces of the hub 57 supporting the rear cover 16 and hub forming the inner race 54 of the lockup one-way clutch assembly 50. As with the prior pull bearings 44a, 44b, the outer and inner bearing supports 60, 62 of the third pull bear are secured with snap rings 64 located in corresponding grooves formed in the radial surfaces of the hub forming the inner race 54 and the inner extension of the hub 57. The outer race 48 of the third pull bearing 44s is accordingly positioned on the radial portion of the outer bearing support 60 and the inner race 46 is positioned on the radial portion of the inner bearing support 62.
While not discussed in detail herein, bushings 70, which may be plastic bushings, are provided laterally of the one-way clutch assembly 50, between the assembly 50 and the second and third pull bearings 44b, 44c, for additional lateral support. These bushings 70 assist in axially retaining the stator 30 in resistance to hydraulic forces exerted from the fluid flow between the impeller 18 and the turbine 22 during drive and coast maneuvers of the vehicle.
As a result of the pull bearings 44 and the construction provided herein, the launch device 10 is provided with a mechanism that limits the overall expansion of the launch device 10, while also allowing for the thickness of the front and rear covers 12, 16 to be reduced along with the overall axial packaging requirements of the launch device 10.
Referring now to the variation of the torque converter 10 of
A third pull bearing 44c of
As can be imparted from the differences between
A further alternative embodiment of the launch device 10 is seen in
Referring now to
With the construction seen in
With the turbine 22 not mounted to the hub 24, the stator 30 is more greatly impacted by hydraulic forces resulting from fluid flow between the impeller 18 and turbine 22 during drive and coast maneuvers of the automotive vehicle. As seen in
As a person skilled in the art will readily appreciate, the above description is meant as an illustration of at least one implementation of a launch device incorporating the principles of the present invention. This description is not intended to limit the scope or application of this invention since the invention is susceptible to modification, variation and change without departing from the spirit of this invention, as defined in the following claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2019/037030 | 6/13/2019 | WO | 00 |
Number | Date | Country | |
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62684372 | Jun 2018 | US |