# US 2021/0277959 A1 · Clutch piston that applies through compensation dam > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0277959 A1 - Document ID: US20210277959A1 - Status: Published application - Kind: A1 - Application number: 16/812,420 - Filed: 2020-03-09 - Published: 2021-09-09 - Earliest claimed: 2020-03-09 - Assignees: Schaeffler Technologies AG & Co. KG - Applicants: Schaeffler Technologies AG & Co. KG - Inventors: Matthew Payne - Web page: https://patentgrep.com/patent/US20210277959A1 ## CPC - F16D 25/0638: with more than two discs, e.g. multiple lamellae - F16D 13/72: Features relating to cooling - F16D 13/74: Features relating to lubrication - F16D 25/123: {in view of cooling and lubrication} - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract A hydraulically applied clutch for a vehicle drivetrain includes a hub, a piston, and a compensation dam. The piston is sealed to the hub at a piston outer diameter and a piston inner diameter. The piston has a plurality of axial protrusions for applying an axial force to a clutch plate. The compensation dam is sealed to the hub at a compensation dam outer diameter. The compensation dam has a plurality of apertures for receiving the plurality of axial protrusions. In an example embodiment, the piston outer diameter and the compensation dam outer diameter are axially aligned. In an example embodiment, the hydraulically applied clutch includes a plurality of seals, each installed on a one of the plurality of axial protrusions for sealing the plurality of axial protrusions for the plurality of apertures. ## Claims ### Claim 1 A hydraulically applied clutch for a vehicle drivetrain, comprising: a hub; a piston, sealed to the hub at a piston outer diameter and a piston inner diameter, comprising a plurality of axial protrusions for applying an axial force to a clutch plate; and a compensation dam, sealed to the hub at a compensation dam outer diameter, comprising a plurality of apertures for receiving the plurality of axial protrusions. ### Claim 2 (depends on 1) The hydraulically applied clutch of claim 1 wherein the piston outer diameter and the compensation dam outer diameter are axially aligned. ### Claim 3 (depends on 1) The hydraulically applied clutch of claim 1 further comprising a plurality of seals, each installed on a one of the plurality of axial protrusions for sealing the plurality of axial protrusions for the plurality of apertures. ### Claim 4 (depends on 1) The hydraulically applied clutch of claim 1 further comprising a piston return spring for urging the piston away from the compensation dam. ### Claim 5 (depends on 1) The hydraulically applied clutch of claim 1 wherein: the hub comprises a first radial wall; and the piston comprises a second radial wall that contacts the first radial wall when the piston is displaced away from the compensation dam. ### Claim 6 (depends on 5) The hydraulically applied clutch of claim 5 wherein the second radial wall comprises a plurality of wall segments, each comprising a portion of a respective piston raised area. ### Claim 7 (depends on 1) The hydraulically applied clutch of claim 1 wherein the hub comprises an oil channel disposed axially between the piston and the compensation dam. ### Claim 8 (depends on 1) The hydraulically applied clutch of claim 1 wherein the compensation dam comprises a plurality of flow holes disposed radially proximate the piston inner diameter. ### Claim 9 (depends on 1) The hydraulically applied clutch of claim 1 further comprising: a first seal; and a second seal, wherein: the piston comprises a first seal groove at the piston outer diameter; the compensation dam comprises a second seal groove at the compensation dam outer diameter; the first seal is disposed in the first seal groove; and the second seal is disposed in the second seal groove. ### Claim 10 (depends on 9) The hydraulically applied clutch of claim 9 wherein the hub comprises an inwardly-facing circumferential wall contacting the first seal and the second seal. ### Claim 11 (depends on 1) The hydraulically applied clutch of claim 1 further comprising a snap ring, wherein: the hub comprises a snap ring groove; and the snap ring is installed in the snap ring groove for axially retaining the compensation dam. ### Claim 12 (depends on 1) The hydraulically applied clutch of claim 1 wherein the hub forms a portion of a rotor carrier of a hybrid module. ### Claim 13 (depends on 12) A hybrid module comprising: the hydraulically applied clutch of claim 12; a housing comprising a bulkhead; and a bearing supporting the hub on the bulkhead. ### Claim 14 (depends on 13) The hybrid module of claim 13 further comprising a third seal, wherein: the bulkhead comprises a third seal groove; and the third seal is installed in the third seal groove to seal the hub to the bulkhead. ### Claim 15 (depends on 13) The hybrid module of claim 13 wherein: the bulkhead comprises a first apply channel; and the hub comprises a second apply channel, hydraulically connected to the first apply channel, for providing a hydraulic pressure to the piston to clamp a clutch pack. ### Claim 16 (depends on 13) The hybrid module of claim 13 wherein: the hub comprises a first oil channel disposed axially between the piston and the compensation dam; and the bulkhead comprises a cooling channel hydraulically connected to the first oil channel for providing a balancing oil to the hydraulically applied clutch. ### Claim 17 (depends on 16) The hybrid module of claim 16 further comprising the clutch plate, wherein: the rotor carrier comprises an inwardly extending spline; and the clutch plate comprises an outwardly extending spline installed on the inwardly extending spline. ### Claim 18 (depends on 17) The hybrid module of claim 17 further comprising the rotor carrier, wherein the rotor carrier includes a second oil channel such that cooling oil from the cooling channel flows through the first oil channel, past the clutch plate, and through the second oil channel.