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Title:
HYDRODYNAMIC LAUNCH DEVICE
Document Type and Number:
WIPO Patent Application WO/2018/151801
Kind Code:
A1
Abstract:
A launch device for coupling a rotary output of a prime mover to a rotary input of a transmission. The launch device including a front cover connected to a rear cover connected and rotatable therewith. The front and rear covers defining a chamber in which an impeller and turbine are located. The front cover defining the impeller and being provided with a plurality of impeller blades extending into the chamber. The turbine including a plurality of turbine blades generally opposing the impeller blades such that hydraulic coupling is defined between the impeller and the turbine. An isolation damper is arranged between the turbine and the rear cover. A launch clutch is arranged between the isolation damper and the rear cover. The launch clutch is moveable between engaged and disengaged positons with the rear cover through pressurization of at least one counter pressure chamber defined at least in part by the launch clutch.

Inventors:
BINDER, Scott William (54335 Birchwood Drive, South Lyon, MI, 48178, US)
Application Number:
US2018/000008
Publication Date:
August 23, 2018
Filing Date:
February 16, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
EXEDY GLOBALPARTS CORPORATION (8601 Haggerty Road, Belleville, MI, 48111, US)
International Classes:
F16D33/18; F16D25/0638; F16D39/00; F16H45/02
Domestic Patent References:
WO2015151637A12015-10-08
Foreign References:
JP2000283188A2000-10-13
Other References:
None
Attorney, Agent or Firm:
SOSENKO, Eric J. (Honigman Miller Schwartz and Cohn LLP, 315 East Eisenhower Parkway Suite 10, Ann Arbor Michigan, 48108, US)
Download PDF:
Claims:
CLAIMS

I/We claim:

1. A launch device for coupling a rotary output of a prime mover to a rotary input of a transmission, a front cover configured to connect to the rotary output member of the prime mover, a rear cover connected to the front cover and rotatable therewith, the front cover and the rear cover cooperating to define a chamber, an impeller having a plurality of impeller blades extending in the chamber, a turbine configured to be connected to the rotary input member of the transmission, the turbine including a plurality of turbine blades generally opposing the impeller blades such that hydraulic fluid is directed from the impeller blades and toward the turbine blades,

the launch device being characterized in that:

the front cover defines the impeller and has the impeller blades provided thereon;

an isolation damper arranged between the turbine and the rear cover; and

a launch clutch arranged between the isolation damper and the rear cover, the launch clutch being moveable between a disengaged position and an engaged position, in the engaged position the launch clutch coupling the rear cover to the isolated damper and in the disengaged position the launch clutch decoupling the rear cover from the isolated damper.

2. The launch device according to claim 1, wherein the launch clutch is moved between the engaged and disengaged positions by pressurization of a primary counter pressure chamber.

3. The launch device according to claim 2, wherein the primary counter pressure chamber is defined by at least a portion of the launch clutch.

4. The launch device according to claim 2, further comprising a secondary counter pressure chamber, upon pressurization of the secondary counter pressure chamber the launch clutch being moved into the disengaged position.

5. The launch device according to claim 4, wherein the secondary counter pressure chamber is defined between portions of the launch clutch and the rear cover.

6. The launch device according to claim 2, wherein the launch clutch includes a plurality of axially moveable interleaved laminations.

7. The launch device according to claim 6, wherein the interleaved laminations include a first set of lamination and a second set of laminations, the first set of laminations being supported by the rear cover and the second set of lamination are supported by the isolation damper.

8. The launch device according to claim 6, wherein at least one lamination of the interleaved laminations directly opposes and is engageable with a friction surface provided on the rear cover or on a reaction plate supported by the rear cover.

9. The launch device according to claim 8, wherein the friction surface is an interior surface of the rear cover.

10. The launch device according to claim 6, wherein the launch device includes a pressure plate coupled to the interleaved laminations and defining a portion of the primary counter pressure chamber, the pressure plate configured to cause axial movement of the interleaved laminations into the engaged position.

11. The launch device according to claim 10, wherein the axial movement of the interleaved laminations into the engaged position is axial movement toward the rear cover.

12. The launch device according to claim 10, wherein the axial movement of the interleaved laminations into the engaged position is axial movement toward the front cover.

13. The launch device according to claim 10, wherein a second counter pressure chamber is defined between the pressure plate and the rear cover, the second counter pressure chamber configured to move the launch clutch into the disengaged position upon pressurization of the second counter pressure chamber.

14. The launch device according to claim 1 , wherein the isolation damper is connected to the launch clutch.

15. The launch device according to claim 1 , wherein the launch device does not include a stator located between the impeller and the turbine.

16. A launch device for coupling a rotary output of a prime mover to a rotary input of a transmission, the launch device comprising:

a front cover configured to connect to the rotary output member of the prime mover, a rear cover connected to the front cover and rotatable therewith, the front cover and the rear cover cooperating to define a chamber,

an impeller having a plurality of impeller blades extending in the chamber, the front cover defining the impeller and having the impeller blades provided thereon;

a turbine configured to connect to the rotary input member of the transmission, the turbine including a plurality of turbine blades generally opposing the impeller blades such that hydraulic fluid is directed from the impeller blades and toward the turbine blades;

an isolation damper arranged between the turbine and the rear cover; and

a launch clutch arranged between the isolation damper and the rear cover, the launch clutch being moveable between a disengaged position and an engaged position, in the engaged position the launch clutch coupling the rear cover to the isolated damper and in the disengaged position the launch clutch decoupling the rear cover from the isolated damper.

17. The launch device according to claim 16, wherein the launch clutch is moved between the engaged and disengaged positions by pressurization of a primary counter pressure chamber defined at least in part by portions of the launch clutch.

18. The launch device according to claim 17, wherein the primary counter pressure chamber is defined by at least a portion of the launch clutch.

19. The launch device according to claim 17, further comprising a secondary counter pressure chamber, upon pressurization of the secondary counter pressure chamber the launch clutch being moved into the disengaged position.

20. The launch device according to claim 19, wherein the secondary counter pressure chamber is defined between portions of the launch clutch and the rear cover.

21. The launch device according to claim 17, wherein the launch clutch includes a plurality of axially moveable interleaved laminations.

22. The launch device according to claim 21, wherein the interleaved laminations include a first set of lamination and a second set of laminations, the first set of laminations being supported by the rear cover and the second set of lamination are supported by the isolation damper.

23. The launch device according to claim 21 , wherein at least one lamination of the interleaved laminations directly opposes and is engageable with a friction surface provided on the rear cover

24. The launch device according to claim 21 , wherein at least one lamination of the interleaved laminations directly opposes and is engageable with a friction surface provided on a reaction plate supported by the rear cover.

25. The launch device according to claim 23, wherein the friction surface is an interior surface of the rear cover.

26. The launch device according to claim 21 , wherein the launch device includes a pressure plate coupled to the interleaved laminations and defining a portion of the primary counter pressure chamber, the pressure plate configured to cause axial movement of the interleaved laminations into the engaged position.

27. The launch device according to claim 26, wherein the axial movement of the interleaved laminations into the engaged position is axial movement toward the rear cover.

28. The launch device according to claim 26, wherein the axial movement of the interleaved laminations into the engaged position is axial movement toward the front cover.

29. The launch device according to claim 26, wherein a secondary counter pressure chamber is defined between the pressure plate and the rear cover, the secondary counter pressure chamber configured to move the launch clutch into the disengaged position upon pressurization of the second counter pressure chamber.

30. The launch device according to claim 16, wherein the isolation damper is connected to the launch clutch.

31. The launch device according to claim 16, wherein the launch device does not include a stator located between the impeller and the turbine.

Description:
HYDRODYNAMIC LAUNCH DEVICE

BACKGROUND

1. Field of the Invention

[0001] The present invention generally relates to launch devices used in connection with the powertrains of automotive vehicles. More specifically, the invention relates to a launch device, similar to a torque converter, utilized in connection with an automatic transmission of an automotive vehicle.

2. Description of Related Art

[0002] Generally, vehicles with automatic transmissions utilize a torque converter to couple the output of the engine with the automatic transmission. The torque converter includes a front cover that is connected to the flex plate of the engine and rotates with the flex plate. The front cover is connected to a back cover of the torque converter, the latter of which is unitary or integral with and causes rotation of the impeller (the impeller is sometimes referred to as the pump). Fluid driven by the blades of the impeller is transferred to and causes rotation of a turbine, whose output is 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 in an efficient manner that results in the torque multiplication.

[0003] As seen in Figure 1, the torque converter includes a front cover having mounting studs secured to the exterior face thereof allowing the torque converter to be mounted to the flex plate (not shown) of an engine (not shown). At its periphery, the front cover is secured to a rear cover.

[0004] Internally, the rear cover is provided with a series of blades or vanes to form the impeller of the torque converter. During rotation of the impeller, hydraulic fluid from the automatic transmission (not shown) is centrifugally forced radially outward, then forward (to the left in Figure 1) to impact against the blades of the turbine and cause rotation of the turbine. Accordingly, the radially outward portions of the blades of the turbine are opposed to the radially outward portions of the blades of the impeller so as to receive the hydraulic fluid from the impeller.

[0005] The shape of the turbine's blades is such that, in addition to causing rotation of the turbine, the flow of the hydraulic fluid is redirected radially inward (downward in the figure) and then back to the impeller. The turbine is further mounted to a hub, which is in turn mounted to an input shaft of the automatic transmission. Thus, rotation of the hub causes rotation of the input shaft.

[0006] Position between the impeller and the turbine, and more particularly between the lower portions of the respective blades of the impeller and turbine, is a stator. The stator receives the hydraulic fluid being returned from the turbine to the impeller and redirects the fluid so that it is efficiently received by the impeller and does not impede rotation of the impeller.

[0007] As seen from the above description, the impeller, turbine and stator define a hydrodynamic coupling or circuit is located on the rearward or transmission side of the torque converter.

[0008] Forward of the turbine, between the turbine and the front cover, the torque converter also includes a rotational damper and a lockup clutch assembly. Of these, the lockup clutch assembly is arranged most forward on the engine side of the torque converter.

SUMMARY

[0009] In overcoming various drawbacks and other limitations of the known art, the present invention provides a launch device for coupling a rotary output of a prime mover to a rotary input of a transmission. In an aspect of the invention, the launch device includes a front cover configured to be connected to the rotary output member of the prime mover, a rear cover connected to the front cover and rotatable therewith, the front cover and the rear cover cooperating to define a chamber. Located within the chamber are an impeller having a plurality of impeller blades and a turbine having a plurality of turbine blades that are generally opposing the impeller blades. The front cover defines the impeller and has the impeller blades provided thereon. An isolation damper is arranged between the turbine and the rear cover, and a launch clutch is arranged between the isolation damper and the rear cover. The launch clutch is moveable between a disengaged position and an engaged position. In the engaged position, the launch clutch couples the rear cover to the isolated damper and in the disengaged position the launch clutch decouples the rear cover from the isolated damper.

[0010] In another aspect of the invention, the launch clutch is moved between the engaged and disengaged positions by pressurization of a primary counter pressure chamber. [001 1] In a further aspect, the primary counter pressure chamber is defined by at least a portion of the launch clutch.

[0012] In an additional aspect of the invention, a secondary counter pressure chamber, upon pressurization of the secondary counter pressure chamber the launch clutch being moved into the disengaged position.

[0013] In yet another aspect, the second counter pressure chamber is defined between portions of the launch clutch and the rear cover.

[0014] In a further aspect of the invention, the launch clutch includes a plurality of axially moveable interleaved laminations.

[0015] In still an additional aspect, the interleaved laminations include a first set of lamination and a second set of laminations, the first set of laminations are supported by the rear cover and the second set of lamination are supported by the isolation damper.

[0016] In another aspect, at least one lamination of the interleaved laminations directly opposes and is engageable with a friction surface provided on the rear cover or on a reaction plate supported by the rear cover.

[0017] In a still a further aspect, the friction surface is an interior surface of the rear cover.

[0018] In an additional aspect of the invention, the launch device includes a pressure plate coupled to the interleaved laminations and defining a portion of the counter pressure chamber, the pressure plate configured to cause axial movement of the interleaved laminations into the engaged position.

[0019] In a further aspect, the axial movement of the interleaved laminations is axial movement toward the rear cover.

[0020] In a still further aspect, the axial movement of the interleaved laminations is axial movement toward the front cover.

[0021] In another aspect, a second counter pressure chamber is defined between the pressure plate and the rear cover, the second counter pressure chamber configured to move the launch clutch into the disengaged position upon pressurization of the second counter pressure chamber.

[0022] In a further aspect, the isolation damper is connected to the launch clutch.

[0023] In an additional aspect, the launch device does not include a stator located between the impeller and the turbine. [0024] In another aspect of the invention, a launch device is provided having a front cover configured to connect to the rotary output member of the prime mover, a rear cover connected to the front cover and rotatable therewith, the front cover and the rear cover cooperating to define a chamber, the front cover defining an impeller and being provided with a plurality of impeller blades extending into the chamber; a turbine configured to be connected to the rotary input member of the transmission, the turbine including a plurality of turbine blades, the turbine blades generally opposing the impeller blades such that hydraulic fluid is circulated between the impeller blades and the turbine blades; an isolation damper connected to the launch clutch and arranged between the turbine and the rear cover; and a launch clutch arranged between the isolation damper and the rear cover and moveable between engaged and disengaged positons, in the engaged position the launch clutch coupling the rear cover to the isolated damper and in the disengaged position the launch clutch decoupling the rear cover from the isolated damper.

[0025] Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after review of the following description with reference to the drawings and the claims that are appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a fragmentary view, in axial cross-section, of a torque converter in accordance with a known construction of such devices, and which is discussed above;

[0027] Figure 2 is fragmentary half view, in axial cross-section, of a launch device embodying the principles of the present invention; and

[0028] Figure 3 is fragmentary half view, in axial cross-section, of another launch device embodying the principles of the present invention.

DETAILED DESCRIPTION

[0029] 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, Figure 2. The description that follows may use directional terms such as "upper" and "lower." These terms are intended to be read in the context of the orientation of the elements as presented in the drawings. Accordingly, "upper" indicates a direction toward the top of the drawing and "lower" indicates a direction toward the bottom of the drawing. The terms "left" and "right" are similarly interpreted. The terms "inward" or "inner" and "outward" or "outer" indicate a direction that is generally toward or away from a central axis of the referred to part, whether or not such an axis is designated in the drawing. An axial surface is therefore one that faces in the axial direction. In other words, an axial surface faces in a direction along the central axis. A radial surface therefore faces radially, generally away from or toward the central axis. It will be understood, however, that these relative terms are for convenience of description that are not intended to require a particular orientation. In actual implementation, the directional references used herein may not necessarily correspond with the installation and orientation of the corresponding components of the device.

[0030] Terms concerning attachments, coupling and the like, such as "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. These attachments and relationships may be movable or rigid, unless expressly described otherwise. "Integral" means that elements are connected together so as to form one unit. "Unitary" means a single, one piece element where all parts of the element are formed together. Thus, the term "unitary" is to be distinguished from the term "integral."

[0031] Referring now to Figure 2, a launch device embodying the principles of the present invention is generally illustrated therein and designated at 10. The launch device 10 includes a front cover 12 having mounting studs 14, or similar features, spaced about its periphery and configured to connect the launch device 10 to a flex plate 16 or outlet of a prime mover (not shown), such as an internal combustion engine or other motor. At its radial periphery, the front cover 12 is integrally connected to or unitarily formed with the rear cover 18. The front cover 12 defines the engine side of the launch device 10, while the rear cover 18 defines the transmission side of the launch device 10.

[0032] Contrary to the device seen in Figure 1 , in the present launch device 10, it is the front cover 12 and not the rear cover 18 that forms the impeller 20 by having blades 22 provided theieoii. Accordingly, as the ilex plate 16 is rotated by the crankshaft (not shown) of the prime mover, the front cover 12, and therefore the impeller 20, is rotated. During this rotation, hydraulic fluid supplied from the automatic transmission (not shown) along a first pathway 24 is forced radially outwardly under the centrifugal force of the rotating impeller 20 and blades 22. The shape of the blades 22 and the front cover 12 in the area of the impeller 20 also directs this hydraulic fluid rearward, generally in the direction of rear cover 18. [0033] Immediately rearward of the impeller 20, the launch device 10 includes a turbine

26. The turbine 26 is mounted to a hub 28 that is connected to a rotatable input shaft 30 of the automatic transmission of the automotive vehicle (not shown). Like the impeller 20, the turbine 26 includes a series of blades 32. The turbine's blades 32 are oriented to receive the hydraulic fluid from the impeller 20 such that the force of the transferred hydraulic fluid will drive and rotate the turbine 26. Notably, the direction of rotation of the turbine 26 is the same as the direction of rotation of the impeller 20. Optionally, a baffle plate 33 may be used to alter and achieve desired fluid flow characteristics. The baffle plate 33 is illustrated as being directly connected to the impeller 20, but may alternatively be connected directly to turbine 26. The hydraulic fluid received by the turbine 26 is thereafter directed radially inward (downward in the figure) and redirected back (forward) toward the impeller 20. With this fluid coupling defined by the impeller 20 and turbine 26, rotation from the engine is transferred into rotation of the input shaft 30 of the automatic transmission.

[0034] Notably, the launch device 10 embodying the principles of the present invention has eliminated the use of a stator between the impeller 20 and turbine 26. Thus, the launch device 10 is stator-less. Instead of the stator, the launch device 10 employs a parallel launch clutch 34, which is further discussed below. By removing the stator from the launch device 10, the launch device 10 enjoys a reduction in mass, inertia, cost, and packaging space over previously known devices, while improving the shift feel and controllability of the launch device 10.

[0035] As further seen in Figure 2, the launch device 10 includes an isolation damper 36 mounted to the hub 28. The isolation damper 36 absorbs variations in the rotation speed of the front and rear covers 12, 18 via the parallel launch clutch 34 and provides for smoother operation of the automatic transmission and less vibration being transferred to the occupant of the vehicle. Since isolation dampers are well known in the technological field of the present invention, the isolation damper 36 of the present launch device 10 is not discussed in greater detail herein, except as necessary.

[0036] Arranged between the isolation damper 36 and the rear cover 18 is the parallel launch clutch 34 mention above. The parallel launch clutch 34 includes a series of axially movable interleaved laminations 38, alternating ones of which are respectively supported on an outer carrier 40 and an inner carrier 42. As seen in Figure 2, the outer carrier 40 is either integral or unitarily formed with a drive plate 44, which operates as the input member of the isolation damper 36. The other carrier, the inner carrier 42, is rigidly connected to rear cover 18.

[0037] The parallel launch clutch 34 additionally includes an axially moveable pressure plate 50 that is interiorly positioned and aligned such that one end is engageable with a forwardmost or innermost one of the laminations 38. The other end of the pressure plate 50 is supported by the rear cover 18. At an intermediate position between its two ends, the pressure plate 50 is supported by a ring flange 48, which is part of a ring member 46 that is rotatably mounted to the hub 28 via an axial bearing 67 and to cylindrical casing 69 of the transmission input by a seal member, such as an o-ring. The seal member prevents leakage of oil from a passage 62 into chamber/fluid paths 54, 58, sustaining necessary pressure in passage 62 for clutch engagement, as further discussed below. Notably, the pressure plate 50 is axially movable relative to both the ring member 46 and the ring flange 48, as well as rear cover 18 and the inner carrier 42. Seals are provided between the ring member 46 and the pressure plate 50, between the ring flange 46 and the pressure plate 50, and between the rear cover 18 and the pressure plate 50. As a result of these seals, a primary counter pressure chamber 65 is formed generally between the pressure plate 50 and the ring member46, ring flange 48 and rear cover 18.

[0038] During operation of the launch device 10, hydraulic fluid is received along a first pathway 58 into various port holes 56 in hub 28, and via the fluid path 54 into a circumferential chamber 52 defined between the front cover 18, the turbine 26, and the rear cover 1 8. Some of the fluid escapes the circumferential chamber 52 to the fluid coupling, which is constituted by the impeller 20 and the turbine 26. Fluid in the fluid coupling escapes into fluid pathway 24, and may exit the launch device 10 through the bearing 25 into passage 27. Additionally, fluid may also escape into back to the circumferential chamber 52 via vent holes (not shown) formed in the turbine 26.

[0039] Flow in the reverse direction may also occurs. Accordingly, during operation of the launch device 10, the hydraulic fluid received from passage 27 through bearing 25 and along the first pathway 24 is provided into the fluid coupling constituted by the impeller 20 and the turbine 26. Some of the fluid escapes from between the impeller 20 and the turbine 26 and into the circumferential chamber 52 defined between the front cover 12 and the rear cover 18. Additional fluid may escape into the secondary chamber 52 via vent holes (not shown) provided in the turbine 26. Fluid in the secondary chamber 52 flows back along the return pathway 54 and may exit the launch device 10 through various ports 56, provided in the hub 28, and the pathway 58.

[0040] Upon increased pressure in the hydraulic fluid present in the primary counter pressure chamber 65, the pressure plate 50 is axially moved rearward, in the direction of the rear cover 18. This movement also causes the laminations 38 to also move in the direction of the rear cover 18. Upon sufficient pressure, the rearmost of the laminations 38 is forced into contact with a friction surface 60, defined on the inner face of the rear cover 18. The friction surface 60 is preferably a surface of the rear cover 18 that is machined or otherwise surface treated to a suitable roughness whereby the parallel launch clutch 34 can be frictionally locked and rotate with the rear cover 18. The friction surface 60 could alternatively be a separate friction member mounted to the rear cover 18.

[0041] To provide the counter pressure in the primary counter pressure chamber 65 and against the ring flange 48/ring member 46 so as to engage the launch clutch 34 via the pressure plate 50, the ring member 46, and therefore the ring flange 48, is rigidly mounted to the rear cover 18 via a collar portion 66 to which the rear cover is fixedly mounted. As seen in Figure 2, the counter pressure chamber 65 extends generally between the ring flange 48 and the rear cover 18 and between the ring member 46 and the collar portion 66 and is coupled through passageway 62 to pathway 64. As such, the collar portion 66 is viewed as defining the radially innermost portion of the rear cover 18 about the input shaft 30 of the automatic transmission. By varying the pressure of the fluid provided through the pathway 64 to the primary counter pressure chamber 65, engagement and disengagement of the launch clutch 34 can be controlled.

[0042] A return spring (not illustrated) may be provided between the pressure plate 50 and the inner carrier 42 or rear cover 18, depending on the desired performance criteria. The return spring's function would be to assist in returning the pressure plate 50 to its original unpressurized position, thereby assuring that no torque transfer occurs between rear cover 18 and outer carrier 40, when not desired.

[0043] Instead of or in addition to a return spring, the launch device 10 may be provided as four path embodiment, instead of the three path embodiment seen in Figure 2. In a four path embodiment, an additional passage for pressurized fluid is used in conjunction with a secondary counter pressure chamber 70 to move the pressure plate 50 from its engaged position to its disengaged position. The fourth path, if provided, connects to the secondary counter pressure chamber 70, defined between the rear cover 18 and the pressure plate 50. When pressure in the fourth path and secondary counter pressure chamber 70 is greater than the pressure in the primary counter pressure chamber 65, the pressure plate 50 is moved forward, away from the rear cover 18 and into its disengaged position. While not illustrated in Figure 2, persons skilled in the art will readily appreciate that the fourth path to the secondary counter pressure chamber 70 may be provided in a variety of ways, depending on the particular application. Accordingly, the fourth path is only represented in Figure 2 by the secondary counter pressure chamber 70.

[0044] In a further embodiment of the launch device, seen in Figure 3 and designated at

100, an implementation is provide where the rear cover 118 is not the friction reaction surface of the launch clutch 134. The embodiment of Figure 3 includes many components that are identical or substantially identical to corresponding components described in connection with Figure 2. These components are identified with similar reference numerals, but in a one hundred (100) series designation. In view of the identical or similar nature of many components, a full discussion of these components would be repetitive and unnecessary for persons skilled in the present technology. For this reason, reference is herein made to the prior description regarding identical and similar components, and the present description will proceed with a discussion of the distinguishing components and features of the embodiment seen in Figure 3.

[0045] In a design alternative where the rear coverl 18 is not the friction reaction surface, a reaction plate 139 is affixed to and extend from the rear cover 1 18 via a snap ring 149. Rearward of the reaction plate 139, an outer carrier 140 is also mounted to the rear cover 1 18 and supports a set of the interleaved laminations 138 for axial movement relative to the reaction plate 139. An inner carrier 142 supporting the other set of axially moveable interleaved laminations 138 is either integrally or unitarily formed with a drive plate 144 of the isolation damper 136. Provided between the interleaved laminations 138 and the rear cover 1 18 is a pressure plate 150, which is axially moveable relative to both of these components. For this purpose, one end of the pressure plate 150 is supported by an axial extension 141 of the outer carrier 140, with a seal provided therebetween, and the other end of the pressure plate 150 is supported by a ring flange 148, with a seal provided therebetween. The ring flange 148 is, like the earlier embodiment, part of a ring member 146 that is rigidly connected to the rear cover 1 18. With the above construction, a primary counter pressure chamber 165 is defined between the pressure plate 150 and the rear cover 118, and generally extends between the ring member 146, rear cover 1 18 and collar portion 166 to pathway 162, which connects it to fluid pathway 164.

[0046] Upon pressurization of the primary counter pressure chamber 165, the pressure plate 150 is moved axially forward until a forward end or face 151 of the pressure plate 150 engages the most rearward one of the laminations 138. Resultantly, the laminations 138 are pressed axially forward, engaging one another, until the most forward one of the lamination 138 engages the reaction plate 139 thereby locking up the launch clutch 136.

[0047] As with the prior embodiment, a return spring (not shown) may optionally be provide to assist in moving the pressure plate 150 into its rearward position, thereby disengaging the launch clutch 136 upon depressurization of the primary counter pressure chamber 165. The return spring could be provided as a tension spring between the pressure plate 150 and the rear cover 118 or a compression spring between the pressure plate 150 and an end of the inner carrier 142. Also as with the prior embodiment, and either with or without a return spring, the launch device 110 may implement a four path construction with a secondary counter pressure chamber 170 to aid in moving the pressure plate 150 rearward and disengaging the launch clutch 1 10.

[0048] 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.