Patent Application
20170030414
The present invention relates to automotive powertrains and in particular to installation of a torque converter onto a transmission in an automotive powertrain.
An automotive powertrain may include a torque converter to transfer torque from a power source—e.g., an internal combustion engine—to a transmission. As is known in the art, the torque converter typically comprises an impeller receiving torque from the power source, a turbine transmitting torque to the transmission, and a stator between the impeller and turbine. The powertrain may also include an auxiliary gear installed on a hub of the impeller. The auxiliary gear may, for example, drive a transmission fluid pump. The hub has an exterior surface and the auxiliary gear has an axial opening with an interior surface. The hub extends into the axial opening. The interior surface abuts the exterior surface such that the auxiliary gear mounts on, and rotates with, the hub.
During assembly, the torque converter and the transmission may be stacked vertically. For example, the auxiliary gear may be positioned at an upper end of the stacked transmission. The torque converter may then be lowered on the auxiliary gear such that the weight of the torque converter is bearing on an end face of the auxiliary gear. The torque converter is then indexed or clocked—i.e., the torque converter is rotated—such that the interior and exterior surfaces align and the auxiliary gear may be slid into an installed position on the hub. However, when the torque converter is rotated, the auxiliary gear may also rotate because of friction between the torque converter and auxiliary gear. The friction may be produced by the weight of the torque converter bearing on the auxiliary gear during indexing. The auxiliary gear rotating with the torque converter makes alignment, and thus mounting, the auxiliary gear to the torque converter more difficult.
An embodiment contemplates an automatic transmission assembly. The assembly includes a torque converter and a transmission. The torque converter has a turbine and an impeller, the impeller having a hub. The transmission drivably engages the turbine. The hub has an exterior surface, a first end face, and a first chamfered edge between the exterior surface and first end face. A gear is mounted on the hub. The gear has an axial opening, a second end face, and a second chamfered edge between the axial opening and the second end face. A plurality of extensions extend, in a normal direction, from the second chamfered edge.
Another embodiment contemplates an automatic transmission assembly. The assembly includes a torque converter drivably engaged with a transmission. The torque converter has an impeller with a hub. The hub has an exterior surface, a hub end face, and a first chamfered edge between the exterior surface and the hub end face. A gear has an axial opening, a gear end face, and a second chamfered edge between the axial opening and the gear end face. First and second extensions extend from the second chamfered edge. The first and second extensions extend in a direction normal to the second chamfered edge. During indexing of the torque converter, the first and second extensions contact the first chamfered edge.
An embodiment contemplates a method of assembling an automatic transmission assembly. A torque converter and a transmission are stacked. The torque converter has an impeller hub. The hub has an exterior surface, a first end face, and a first chamfered edge between the exterior surface and the first end face. The transmission has an auxiliary gear with a plurality of extensions normal to a second chamfered edge between an axial opening and a second end face. The extensions are the only contact between the torque converter and the auxiliary gear when the torque converter and transmission are stacked. The stacked torque converter is rotated on the extensions until the hub aligns with the axial opening. The aligned torque converter hub is slid into the axial opening.
An advantage of an embodiment is that friction is reduced between the torque converter and auxiliary gear during installation of the auxiliary gear to the hub of the torque converter impeller.
The powertrain 100 includes a power source 104. The power source 104 may be an internal combustion engine, an electric machine, or another type of power source. The power source 104 produces torque that is transmitted to a torque converter 106. The torque converter 106 in turn transmits the torque to a transmission 108, part of a transmission assembly 109. The transmission 108 turns a driveshaft 110. Torque is transmitted by the drive shaft 110, through a differential 112, to first and second drive wheels 114A and 114B, respectively.
In addition to the transmission 108, the torque converter 106 also supplies torque to an auxiliary component 116. The auxiliary component 116 is driven by the power source 104 in addition to the transmission 108. For example, the auxiliary component 116 may be a transmission fluid pump for circulating transmission fluid through the transmission 108. Alternatively, the auxiliary component 116 may be other than a transmission fluid pump.
As illustrated, the interior surface 140 has alternating curved constant radius portions and flat non-constant radius portions. The interior surface 140 has first and second curved constant radius portions 139 and 141, respectively, and first and second flat non-constant radius portions 144 and 146, respectively, spaced apart circumferentially. However, the gear 128 may have more or fewer of the curved and flat portions than is illustrated. As illustrated, the first and second flat portions 144 and 146, respectively, are separated by 180 degrees and located opposite each other across the axial opening 132. However, the first and second flat portions 144 and 146, respectively, may be located other than opposite each other. The first and second flat portions 144 and 146, respectively, may be referred to as D-flats. However, the first and second flat portions 144 and 146, respectively, may be other than flat. For example, the first or second flat portion 144 or 146, respectively, may be curved at a second radius different than the constant radius of the first and second curved portions 139 and 141, respectively.
Outwardly extending from the surface of the chamfered edge 142 at the first flat portion 144 is a first extension 148 and outwardly extending from the surface of the chamfered edge 142 at the second flat portion 146 is a second extension 150. As illustrated, the first and second extensions 148 and 150, respectively, are convex oval domes. Alternatively, the first and second extensions 148 and 150, respectively, may be other than oval domes. For example, the first and second extensions 148 and 150, respectively, may be outwardly extending circular domes, pyramidal shapes, or trapezoidal shapes. The term “outwardly extending” as used herein means that the first and second extensions 148 and 150 extend radially inward and axially forward from the surface of the chamfered edge 142 in order to form protrusions extending from the edge 142. As illustrated, the first and second extensions 148 and 150, respectively, extend in a direction normal to the chamfered edge 142. Alternatively, the first and second extension 148 and 150, respectively, may extend in a direction other than normal to the chamfered edge 142.
The gear 128 will not slide onto the hub 126 until the first portion 144 is aligned with the first recess 152 and the second portion 146 is aligned with the second recess 154. Therefore, the torque converter 106 is rotated (which may include jiggling back and forth rotationally) until the first portion 144 aligns with the first recess 152 and the second portion 146 aligns with the second recess 154—i.e., the torque converter 106 is indexed or clocked. When the first portion 144 is aligned with the first recess 152 and the second portion 146 is aligned with the second recess 154, the gear 128 is aligned with the hub 126. When aligned, the weight of the torque converter 106 causes the hub 126 to drop into the gear 128 in an assembled position. The gear 128 drops onto the hub 126 to a bottomed out position illustrated in
The gear 128 may be a formed powder metal part. The first and second extensions 148 and 150, respectively, may be formed with the gear 128 during the same forming process. Alternatively, the first and second extensions 148 and 150, respectively, may be formed as separate parts and fixed to the gear 128. For example, the first and second extensions 148 and 150, respectively, may be fastened or welded to the gear 128.
While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.
