# US 11,028,905 B2 · Coupled planetary gearbox > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,905 B2 - Document ID: US11028905B2 - Status: Granted - Kind: B2 - Application number: 16/353,413 - Filed: 2019-03-14 - Published: 2020-09-17 - Granted: 2021-06-08 - Earliest claimed: 2019-03-14 - Assignees: Hamilton Sundstrand Corporation - Applicants: Hamilton Sundstrand Corporation - Inventors: Aaron M. Finke; Stephen Michael Bortoli; Mark J. Franklin - Web page: https://patentgrep.com/patent/US11028905B2 ## CPC - F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H) - F16H 3/66: composed of a number of gear trains without drive passing from one train to another - F02C 3/113: with variable power transmission between rotors - F02C 7/32: Arrangement, mounting, or driving, of auxiliaries - F05D 2260/40311: of the epicyclical, planetary or differential type - F16H 2200/0043: the gear ratios comprising four forward speeds - F16H 2200/2007: with two sets of orbital gears - F16H 2200/2041: with four engaging means - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F16H: GEARING - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract Disclosed is a transmission, including: an input shaft; an output shaft; a gear system connected between the input shaft and the output shaft, the gear system including: a first epicyclical gear set that includes a first ring gear coupled to the input shaft, a first sun gear, a first planetary gear set, and a first planetary carrier connected to the first planetary gear set; and a second epicyclical gear set that includes a second ring gear, a second sun gear, a second planetary gear set, and a second planetary carrier connected to the second planetary gear set, wherein: the input shaft is coupled to the first ring gear and the second planetary carrier; and the first planetary carrier is coupled to the second ring gear; and clutches that engage the first epicyclical gear set and the second epicyclical gear set, the clutches shifting the transmission to generate overlapping transmission speeds. ## Claims ### Claim 1 A transmission, including: an input shaft configured to operationally connect to a low pressure section of a gas turbine engine; an output shaft configured to drive an engine aircraft accessory; a gear system connected between the input shaft and the output shaft, the gear system including: a first epicyclical gear set that includes a first ring gear coupled to the input shaft, a first sun gear, a first planetary gear set, and a first planetary carrier connected to the first planetary gear set; and a second epicyclical gear set that includes a second ring gear, a second sun gear, a second planetary gear set, and a second planetary carrier connected to the second planetary gear set, wherein: the input shaft is coupled to the first ring gear and the second planetary carrier; and the first planetary carrier is coupled to the second ring gear; and a plurality of clutches that engage the first epicyclical gear set and the second epicyclical gear set, the plurality of clutches being adapted for shifting the transmission to generate a plurality of respectively overlapping transmission speeds; wherein the plurality of clutches comprises one or more of: a first clutch configured for being shifted between: a closed state, to rotationally couple the output shaft with the second sun gear; and an opened state to rotationally decouple the output shaft from the second sun gear; a second clutch configured for being shifted between: a closed state to rotationally couple the output shaft with the second ring gear and the first planetary carrier; and an opened state to rotationally decouple the output shaft from the second ring gear and the first planetary carrier; a third clutch configured for being shifted between: a closed state to rotationally brake the first sun gear; and an opened state to rotationally release from braking the first sun gear; and a fourth clutch configured for being shifted between: a closed state to rotationally brake the second ring gear and the first planetary carrier; and an opened state to rotationally release from braking the second ring gear and the first planetary carrier; wherein the plurality of transmission speeds includes one or more of: a first transmission speed, wherein: the first clutch is in the closed state; the second clutch is in the opened state; the third clutch is in the opened state; and the fourth clutch is in the closed state; a second transmission speed, wherein: the first clutch is in the closed state; the second clutch is in the opened state; the third clutch is in the closed state; and the fourth clutch is in the opened state; a third transmission speed, wherein: the first clutch is in the closed state; the second clutch is in the closed state; the third clutch is in the opened state; and the fourth clutch is in the opened state; and a fourth transmission speed, wherein: the first clutch is in the opened state; the second clutch is in the closed state; the third clutch is in the closed state; and the fourth clutch is in the opened state; and wherein: the first transmission speed and the second transmission speed overlap by a first overlapping speed range; the second transmission speed and the third transmission speed overlap by a second overlapping speed range that is broader than three times the first overlapping speed range; and the third transmission speed and the fourth transmission speed overlap by a third overlapping speed range that is broader than five times the first overlapping speed range. ### Claim 2 (depends on 1) The transmission of claim 1, wherein: the first transmission speed generates a first output/input speed ratio; the second transmission speed generates a second output/input speed ratio that is less than sixty percent of the first output/input speed ratio; the third transmission speed generates a third output/input speed ratio that is less than the second output/input speed ratio and less than forty percent of the first output/input ratio; and the fourth transmission speed generates a fourth output/input speed ratio that is less than the third output/input speed ratio and less than thirty percent of the first output/input ratio. ### Claim 3 (depends on 1) The transmission of claim 1, further comprising: a first spline that connects: the first clutch to the second sun gear; and the first clutch to the output shaft; and a second spline that connects: the second clutch to the second ring gear; and the second clutch to the output shaft. ### Claim 4 (depends on 1) The transmission of claim 1, further comprising: a first rotor coupled to the second sun gear, and the first rotor being a stub shaft that is: axially aligned with the input shaft and the output shaft; and axially intermediate the input shaft and the output shaft; wherein the first clutch is coupled to the first rotor so that engaging the first clutch engages the first rotor; a second rotor coupled to the first sun gear; wherein the third clutch is a first band brake configured to engage the second rotor; and the fourth clutch is a second band brake configured to engage the second ring gear. ### Claim 5 A method of transmitting rotational speed, comprising: providing a first epicyclical gear set that includes a first sun gear, a first ring gear surrounding the first sun gear, a first planetary gear set that mechanically couples the first sun gear to the first ring gear, and a first planetary carrier connected to the first planetary gear set; providing a second epicyclical gear set that includes a second sun gear, a second ring gear surrounding the second sun gear, a second planetary gear set that mechanically couples the second sun gear to the second ring gear, and a second planetary carrier connected to the second planetary gear set; driving from an input shaft of a transmission: the first ring gear, thereby driving the first planetary gear set, and the first planetary carrier; and the second planetary carrier, thereby driving the second planetary gear set, and the second sun gear; driving, from the first planetary carrier, the second ring gear; and controlling a plurality of clutches in the transmission to engage the first epicyclical gear set and the second epicyclical gear set, thereby shifting the transmission between a plurality of transmission speeds that are respectively overlapping; wherein controlling the plurality of clutches includes one or more of: shifting a first clutch of the plurality of clutches between: a closed state, to rotationally couple an output shaft with the second sun gear; and an opened state to rotationally decouple the output shaft from the second sun gear; shifting a second clutch of the plurality of clutches between: a closed state to rotationally couple the output shaft with the second ring gear and the first planetary carrier; and an opened state to rotationally decouple the output shaft from the second ring gear and the first planetary carrier; shifting a third clutch of the plurality of clutches between: a closed state to rotationally brake the first sun gear; and an opened state to rotationally release from braking the first sun gear; shifting a fourth clutch of the plurality of clutches between: a closed state to rotationally brake the second ring gear and the first planetary carrier; and an opened state to rotationally release from braking the second ring gear and the first planetary carrier; wherein the method further comprises one or more of: generating a first transmission speed of the plurality of transmission speeds by: shifting the first clutch to the closed state; shifting the second clutch to the opened state; shifting the third clutch to the opened state; and shifting the fourth clutch to the closed state; generating a second transmission speed of the plurality of transmission speeds by: shifting the first clutch to the closed state; shifting the second clutch to the opened state; shifting the third clutch to the closed state; and shifting the fourth clutch to the opened state; generating a third transmission speed of the plurality of transmission speeds by: shifting the first clutch to the closed state; shifting the second clutch to the closed state; shifting the third clutch to the opened state; and shifting the fourth clutch to the opened state; generating a fourth transmission speed of the plurality of transmission speeds by: shifting the first clutch to the opened state; shifting the second clutch to the closed state; shifting the third clutch to the closed state; and shifting the fourth clutch to the opened state; and wherein: the first transmission speed and the second transmission speed overlap by a first overlapping speed range; the second transmission speed and the third transmission speed overlap by a second overlapping speed range that is broader than three times the first overlapping speed range; and the third transmission speed and the fourth transmission speed overlap by a third overlapping speed range that is broader than five times the first overlapping speed range. ### Claim 6 (depends on 5) The method of claim 5, wherein: the first transmission speed generates a first output/input speed ratio; the second transmission speed generates a second output/input speed ratio that is less than sixty percent of the first output/input speed ratio; the third transmission speed generates a third output/input speed ratio that is less than the second output/input speed ratio and less than forty percent of the first output/input ratio; and the fourth transmission speed generates a fourth output/input speed ratio that is less than the third output/input speed ratio and less than thirty percent of the first output/input ratio. ### Claim 7 (depends on 5) The method of claim 5, wherein the transmission includes: a first spline that connects: the first clutch to the second sun gear; and the first clutch to the output shaft; and a second spline that connects: the second clutch to the second ring gear; and the second clutch to the output shaft. ### Claim 8 (depends on 5) The method of claim 5, wherein the transmission includes: a first rotor coupled to the second sun gear, and the first rotor being a stub shaft that is: axially aligned with the input shaft and the output shaft; and axially intermediate the input shaft and the output shaft; wherein the first clutch is coupled to the first rotor so that engaging the first clutch engages the first rotor; a second rotor coupled to the first sun gear; wherein the third clutch is a first band brake configured to engage the second rotor; and the fourth clutch is a second band brake configured to engage the second ring gear.