Patent ID: 12253147

DETAILED DESCRIPTION

As mentioned above, conventional torque converters employ a rotating shell, defined by front and rear covers, that is directly connected to the prime mover. Internally, the shell includes impeller blades that rigidly attached to the rear cover. When rotated with the rear cover, the shape of the impeller blades cause hydraulic fluid within the shell to be moved radially outward and thereafter thrust against blades of an opposing and rotatably supported turbine. The shape of the turbine blades and the force of the hydraulic fluid imparted upon them induces rotation of the turbine and, subsequently, redirects the hydraulic fluid back towards the impeller blades. The turbine is further mounted to a hub, which is in turn mounted to an input shaft of the device being driven, e.g. the transmission. Thus, rotation of the turbine and hub causes rotation of the input shaft of the transmission. To enable torque multiplication, located between the lower portions of turbine and impeller blades is a stator, which mounted on a one-way clutch. The stator redirects fluid from the turbine so that it is received by the impeller blades without impeding rotation of the impeller blades, thereby resulting in torque multiplication. As seen from the above description, the impeller, turbine and stator define a hydrodynamic coupling or circuit in the torque converter.

Referring now to the drawings, a launch device embodying the principles of the present invention is generally illustrated inFIG.1and designated at10. The launch device10provides for the selective transfer of torque and utilizes a fluid coupling provided by a novel torque converter11. As disclosed herein, the torque converter11excludes a rotating shell and replaces it with a static, non-rotating containment vessel12.

The containment vessel12is a sealed, fluid tight structure, defined by a rigid impeller baffle14and a rigid turbine baffle16, that encases the fluid of the torque converter's hydrodynamic circuit. While shown as being defined by the impeller and turbine baffles14,16, the containment vessel12may alternatively be defined by the housing or other portions2of the prime mover40, the housing or other portions4of the driven device50, a combination of both of these elements2,4or by a separate construction altogether.

Within the chamber defined by the containment vessel12are a driving element (an impeller)18and a driven element (a turbine)20. The impeller18, being located within the containment vessel10, and not formed as a part thereof, is not subject to ballooning loads and can be notably lighter in weight than a conventional torque converter's rear cover and its rigidly mounted impeller blades, allowing it to be designed and constructed as a less massive element of the driveline. By removing the shell and its weight from the rotating elements of the driveline, and by providing less massive driving and driven elements, the primary inertia of the powertrain is reduced.

With the present construction, the impeller18and turbine20rotate within the static containment vessel12. The impeller18includes a plurality of impeller blades22supported on an impeller hub24by an impeller shell or rings26. Similarly, the turbine20includes a plurality of turbine blades28supported on an turbine hub30by an impeller shell or rings32. The impeller hub24and turbine hub30extend from the containment vessel12for respective coupling to output and input members38,48of the prime mover40and driven device50, or to an intermediary device, such as a damper and/or isolator31. Seals33retain the fluid of the hydrodynamic circuit within the inner chamber of the containment vessel12.

The impeller blades22are fluidly coupled to and drive the turbine blades28in rotation, which in turn transmits torque to other powertrain system elements, such as a transmission of a motor vehicle. While the impeller18and turbine20are free to rotate independently of each other within the containment vessel12, the impeller18is coupled to the output member38of the prime mover40, either rigidly or through a clutch42, as further discussed below.

As mentioned above, conventional torque converters use a stator within the shell, between the impeller and the turbine, to modify the torque transmission characteristics of the torque converter. A conventional stator also utilizes a one-way clutch and reacts against a stator support shaft that is grounded to the body of the power transmission unit.

In the present launch device10, the containment vessel12is fixed and static relative to the rotating elements, the impeller18and the turbine20. As a result, a stator34may be grounded off of the containment vessel12and the need for a separate support shaft, and it's weight, for the stator34is eliminated from the driveline. With the stator34grounded off of the containment vessel12, a conventional one-way clutch located concentrically within the torque converter10is also not required. This space, designated at36between the impeller18and turbine20, can be used for other purposes, including packaging of a transfer clutch, a disconnect clutch or a damper. The one-way clutch44utilized with the stator34is therefor also grounded off of the containment vessel12and/or other fixed components, such as the engine/motor housing2or driven device housing4.

The turbine20is coupled by a one-way clutch46to drive the input48of the driven device50.

As briefly noted above, through the use of selectable clutches42,52, the prime mover40may directly drive the driven device50and the hydrodynamic circuit and rotating elements (impeller18and turbine20) of the present torque coupling device11may be bypassed, leading to fuel economy gains (or miles per gallon equivalents), efficiency improvements and other benefits resulting from decreased pumping losses. This selectable aspect of the launch device10is useful for providing torque multiplication of electric motors during vehicle launch, while providing pass-through torque flow with minimal energy losses upon reaching a threshold where torque multiplication is no longer needed, e.g. a steady cruising speed.

Accordingly, the selectable clutches42,52may be used in concert to operate the driveline in a variety of modes, including full hydraulic launch, parallel launch (torque transfer through the hydraulic circuit of the torque converter with additional clutch-assistance), and direct drive (full bypass of the torque converter's hydraulic circuit).

The selectable clutches42,52may include wet or dry elements. Non-slipping disconnect clutches may also be practical for the facilitation of the present launch device10.

The selectable clutch, designated at40, is normally open and may be located between the output member38of the prime mover40and the input provided by the impeller hub24. As seen inFIG.1, this clutch42is located outside of the containment vessel12. The clutch42may alternatively be located internally of the containment vessel12, which is shown inFIG.2. A second selectable clutch52may be located relative to a direct drive shaft54connecting the output38of the prime mover40directly with the input48of the driven device50(e.g. the transmission).

Provided in this manner, the selectable clutches42,52can be configured to enable a complete bypass of the hydraulic circuit of the torque converter11. With the second selectable clutch52being a normally closed clutch that completes a direct drive connection through the drive shaft54and bypasses the hydrodynamic circuit, a command signal (typically hydraulic or pneumatic pressure, or potentially an electromagnetic lock up device) to close the clutch is not required. Considering typical duty cycles in existing torque converters, the majority of miles driven are in a direct drive mode with the clutch applied). Extrapolating to the present launch device10, with the second selectable clutch52being normally closed, the second selectable clutch52can provide energy savings by not requiring a parasitic control signal to actuate and close the clutch52during the majority of its duty cycle.

As seen from the above discussion, novel features of the present launch device10include, without limitation, a non-rotating containment vessel12, a low inertia impeller18, an impeller18that rotates independently from the containment vessel12, a stator34attached and grounded to the containment vessel12, and the ability to bypass the hydraulic elements of the system and directly drive the driven device. The present launch device10thus also offers the capability of a parallel launch where the fluid coupling is engaged, while the second selectable clutch52is allowed to “slip,” providing an alternate torque path that augments total torque transfer.

One advantage of the launch device10is the reduction in the primary inertia of the driveline, which benefits overall system energy efficiency. Also reduced, and potentially eliminated, is ballooning of the torque converter's containment vessel12. Reduced or eliminated ballooning may further allow elimination or simplification of system components (i.e. flex plate) that are currently required to accommodate the ballooning effects of contemporary torque converter designs. For engine starting, the reduced primary inertia allows a Belt Starter Generator (BSG) or a Belt Alternator Starter (BAS) system to be used. Finally, with the change from convention mounting of a stator, the launch device10is provided with the ability to package a clutch or other components radially inboard of the stator34, thereby allowing for decrease axial length and an increase in the system's packaging density.

The above description is meant to be illustrative of at least one preferred implementation incorporating the principles of the invention. One skilled in the art will really appreciate that the invention is susceptible to modification, variation and change without departing from the true spirit and fair scope of the invention, as defined in the claims that follow. The terminology used herein is therefore intended to be understood in the nature of words of description and not words of limitation.