Patent Application
20160305524
The present disclosure relates generally to torque converters and more specifically to torque converter front cover assembly pilots for aligning with crankshafts.
Currently, torque converter cover pilots are extruded out of the cover or are have a standard T-shape design. An example of an extruded pilot is shown in U.S. Pat. No. 6,651,330. U.S. Pat. No. 7,997,072 discloses a stamped pilot welded to a cover.
A torque converter cover assembly is provided. The torque converter cover assembly includes a front cover for facing an engine crankshaft and a pilot configured for aligning the front cover with the engine crankshaft. The pilot including a base end fixed to the front cover and a tapered section extending from the base end. The tapered section decreasing in size radially as the pilot extends axially away from the front cover.
A method of forming a torque converter is also provided. The method includes forming a front cover assembly including a front cover for facing an engine crankshaft and a pilot configured for aligning the front cover with the engine crankshaft. The pilot includes a base end fixed to the front cover and a tapered section extending from the base end. The tapered section decreases in size radially as the pilot extends axially away from the front cover.
The present invention is described below by reference to the following drawings, in which:
In order to improve durability of a friction weld, the present disclosure provides an embodiment of pilot including a frustoconical shape, a free end for crankshaft mounting and a wider base for additional projection weld contact. If the area of the weld between the pilot and cover of the torque converter is too small then the weld can fail while the pilot is aligning the torque converter to the engine which can cause the entire power train system to fail. If the pilot is not the desired size then the torque converter will not fit in the corresponding power train system and this will not function. The embodiment of the pilot described below provides strength in the pilot weld area of front cover assembly of the torque converter while also meeting the requirements for pilot size and envelope. The shape of pilot may provide a sufficient projection weld area, may eliminate weak points and provides a pilot fitting into the corresponding envelope.
Radially outside of blade supporting portion 22, turbine shell 21 includes an outer radial extension 24 radially protruding outwardly from an outer circumference of blade supporting portion 22. Impeller shell 16 includes a rounded blade supporting portion 25 for supporting a plurality of impeller blades 26. Radially outside of blade supporting portion 25, impeller shell 16 includes a radially extending wall 27 radially protruding outwardly from an outer circumference of a blade supporting portion 25. A friction material 28 is bonded onto a surface of outer radial extension 24 for engaging radially extending wall 27. In other embodiments, instead of or in addition to being bonded to outer radial extension 24, friction material 28 may be bonded to radially extending wall 27. Turbine 20 is connected to a damper assembly 30 that is circumferentially drivable by turbine 20 and is positioned between turbine 20 and front cover 14. Torque converter 10 also includes a stator 32 between turbine 20 and impeller 18 and a one-way clutch 34 supporting stator 32. Stator 32 includes a centering plate 34 holding one-way clutch 36 in place within stator 32. A thrust washer 38 is also provided axially between stator 32 and impeller shell 16.
Torque converter 10 further includes a pilot 40 extending axially from an engine-side surface 42 of a flat center portion 44 of front cover 14. Pilot 40, front cover 12 and rear cover 14 together form a cover assembly of torque converter 10. Pilot 40 is concentric with front cover 14 and is fixed to front cover by a projection weld 46. Pilot 40 is used to align cover studs 48 with a flexplate 50 during installation of torque converter 10. Flexplate 50 is fixed to crankshaft 12 by a plurality of bolts 52 and is fixed to front cover 14 by nuts 54 received on studs 48 such that front cover 14 is drivable by crankshaft 12 via flexplate 50. To align front cover 14, pilot 40 is received in an envelope of crankshaft 12, which is in the form of a bore 56 formed in an end of crankshaft 12. Bore 56 is cylindrical and is defined by a radially extending surface 58 and an axially extending surface 60. A radially extending surface 62 of a free end 64 of pilot 40 axially contacts radially extending surface 58 of bore 56 and an axially extending surface 66 of pilot 40 radially contacts axially extending surface 60 of bore 56. In the embodiment shown in
Pilot 40 is a single solid—i.e., not hollow—piece and further includes a base end 72 fixed to flat center portion 44 of front cover 14 and a tapered section 74 extending from base end 72. Tapered section 74 is positioned between base end 72 and free end 64 and decreases in size radially as pilot 40 extends axially away from front cover 14 such that base end 72 has a greater diameter than the entirety of tapered section 74. In the embodiment shown in
In a preferred embodiment, the shape of pilot 40 may be created by a forming process before pilot 40 is welded to front cover 12. In other embodiments, pilot 40 may be formed to be cylindrical in shaped and then later machined before or after being welded to front cover 12 to create the shape of pilot 40. According, pilot 40 may be formed to include tapered section 74 and then fixed by base end 72 to front cover 12, or pilot 40 may be fixed by base end 72 to front cover 12, then machined to form tapered section 74.
In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.
