Patent Application
20120145508
The present disclosure relates to a core plate for a clutch assembly. More specifically, the present disclosure relates to a core plate with an extruded spline.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A typical motor vehicle automatic transmission includes gear elements and multiplate clutches that are selectably engageable to establish one of several forward speed ratios between the transmission input and output shafts. The input shaft is coupled to the vehicle engine through a fluid coupling such as a torque converter, and the output shaft is coupled to the vehicle drive wheels through a differential gear set.
A multiplate clutch generally includes a set of friction plates, a set of separator plates, and a hub all of which are housed in a clutch case. Spline grooves in the clutch case engage with splines along the outer periphery of the separator plates and another set of spline grooves in the hub engage with splines around the inner surfaces of the friction plates. The separator plates and the friction plates are arranged alternately so that they can be engaged or disengaged with each other.
In general the contact area between each spline and respective spline groove results in high contact stresses. Accordingly, there is a need in the art for a multiplate clutch assembly with separator plates and friction plates with splines that have more contact area over each spline.
The present invention provides a core plate for a multiplate clutch assembly. The core plate is annular in shape and includes a spline with a plurality of teeth. At least one of the plurality of teeth is either partially or fully extruded. The spline may be disposed around the inner surface of the annular core plate or may be disposed around the outer surface of the core plate. The core plate can be a core plate associated with a friction plate or can be a core plate associated with a separator plate.
Some embodiments of the core plate may have one or more of the following advantages. Because the extruded teeth provide a larger contact area, the contact stresses are reduced. Hence, the mating surfaces of the clutch assembly components that engage the teeth may be made from a softer material than found in typical clutch assemblies. Because of the decreased contact stresses, a thinner friction core plate material may be used without impacting the performance or the robustness of the multiplate assembly.
Further, the contact area between each clutch plate creates heat when the clutch is engaged. Use of an extruded spline allows for a thinner friction core plate, which also allows for added thickness to the separator plate in a multiplate packaging environment; thereby adding thermal sink capacity to the clutch system, since the amount of heat that can be absorbed and dissipated is proportional to the thickness of the separator plates in the multiplate assembly.
In general, the increased contact area provided by the extruded spline can be utilized to allow the use of alternate spline materials for the friction clutch plate interface, such as, for example, Aluminum, Magnesium, or any other suitable material.
Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, like reference characters designate corresponding parts throughout the different views. In the drawings:
a is a front view of a core plate for the fiction plate assemblies of
b is a close up view of a single spline of the core plate in the region 2b of
c is a close up view of a single spline in accordance with another embodiment of the present invention;
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Referring now to
Referring further to
In another implementation as shown in
In alternative applications, a friction plate 12″ includes an outer surface 21″, an inner surface 23″, and a spline 20″ with extruded teeth 19″ around the outer surface 21″.
In yet other applications, the separator plate 14 may also include a core plate with an inner spline similar to the core plate shown in
In typical clutch assemblies, the hub 16 is made of steel. However, if extruded splines are employed, the contact area between the teeth of the splines and the spline groove in the hub increases and thereby decreases the contact stress between the hub and the teeth of the spline as compared to splines that are not extruded. Accordingly, with decreased contact stresses, a material softer than steel can be employed for the hub, such as, for example, aluminum. Alternatively, the hub can be steel, but the increased contact area associated with an extruded spline allows for the use of a thinner core plate. Hence, the mass is reduced, resulting in a cost reduction in the manufacturing of such core plates. In such arrangements, the separator plate can be thicker than a conventional separator plate to allow for a greater heat sink such that higher energy can run through the clutch assembly that occupies the same space, or, alternatively, more friction plates may be employed in the same space.
To make the teeth 19 or 19″ on the splines, each core plate associated with a friction plate or separator plate is initially stamped or fine blanked. Then the edges of the teeth are coined or drawn to form the extruded spline. That is, the outer edge of each tooth is folded down to form a fully extruded tooth as shown in
In sum, the use of friction plates with an extruded spline allows for reduced mass, greater choice in mating component materials, increased axial packaging flexibility, and allows greater clutch energy capacity that results from thinner friction core plates and thicker separator plates.
Depending on the application, certain teeth of a spline associated with either the separator plate or the friction plate may not be extruded. That is, for a particular inner or outer spline, some teeth may be extruded while others are not.
Referring to
The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
