# US 8,784,246 B2 · Series drivetrain with CVT output > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,246 B2 - Document ID: US8784246B2 - Status: Granted - Kind: B2 - Application number: 13/325,970 - Filed: 2011-12-14 - Published: 2013-06-20 - Granted: 2014-07-22 - Earliest claimed: 2011-12-14 - Assignees: Caterpillar Inc. - Applicants: Benjamin Treichel; Bryan Cochran; Min Li - Inventors: Benjamin Treichel; Bryan Cochran; Min Li - Web page: https://patentgrep.com/patent/US8784246B2 ## CPC - B60K 6/365: with the gears having orbital motion - B60K 6/46: Series type - F16H 3/724: {using externally powered electric machines} - B60K 2006/381: {characterized by driveline brakes} - B60W 10/105: of electric type - F16H 2200/2005: with one sets of orbital gears - F16H 2200/2033: with one engaging means - Y02T 10/62: Hybrid vehicles - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - F16H: GEARING - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An electric drive system for driving a machine includes first and second electric drive motors linked to sun and ring gears respectively of a planetary output stage, and a ring brake associated with the ring gear to maintain the ring gear in a locked position. The carrier drives a fixed gear series drive train. In a first regime of operation corresponding to a first range of machine speeds, a controller employs the ring brake to brake the ring gear, and actuates only the first electric drive motor at a speed sufficient to yield the desired machine speed. In a second regime, corresponding to a second range of machine speeds, the controller drives the first electric drive motor at maximum speed, releases the ring brake, and drives the second electric drive motor so as to yield the desired machine speed. ## Claims ### Claim 1 A series electric drive train for driving a ground engaging mechanism of a machine, the series electric drive train comprising: a first electric drive motor having a first motor output; a second electric drive motor having a second motor output; an electrical generator for providing electrical power to the first electric drive motor and the second electric drive motor; a planetary gear set having a sun gear, a carrier, and a ring gear, the sun gear being rotationally fixed to the first motor output and the ring gear being rotationally fixed to the second motor output, the carrier providing a rotational output of the planetary gear set; a ring brake associated with the ring gear to maintain the ring gear in a locked position; and a fixed gear drive linking the rotational output of the planetary gear set to the ground engaging mechanism. ### Claim 2 (depends on 1) The series electric drive train according to claim 1, wherein the fixed gear drive linking the rotational output of the planetary gear set to the ground engaging mechanism is a reduction gear set. ### Claim 3 (depends on 1) The series electric drive train according to claim 1, wherein the first electric drive motor and the second electric drive motor are of essentially matching power capacities. ### Claim 4 (depends on 1) The series electric drive train according to claim 1, wherein the electrical generator is linked to, and driven by, a prime power source. ### Claim 5 (depends on 1) The series electric drive train according to claim 1, further including an energy storage system for providing electrical power to the first electric drive motor and the second electric drive motor. ### Claim 6 (depends on 5) The series electric drive train according to claim 5, wherein the energy storage system is further configured to receive electrical power from the first electric drive motor and the second electric drive motor during machine deceleration. ### Claim 7 An electric drive system for propelling a machine, the electric drive system comprising: first and second electric drive motors linked directly to a sun gear and ring gear respectively of a planetary output stage for driving a series drive train, an output of the planetary output stage being directly linked to a carrier of the planetary output stage, the planetary output stage including a ring brake for selectively braking and releasing the ring gear; an electrical energy supply system for supplying electrical power to the first and second electric drive motors; and a controller programmed to operate the first and second electric drive motors and the ring brake in two regimes of operation to provide a desired machine speed, wherein in the first regime of operation, corresponding to a first range of machine speeds, the controller actuates the ring brake to brake the ring gear, and actuates only the first electric drive motor at a speed sufficient to yield the desired machine speed, and wherein in the second regime of operation, corresponding to a second range of machine speeds higher than the first range of machine speeds, the controller drives the first electric drive motor at a fixed speed, actuates the ring brake to release the ring gear, and drives the second electric drive motor at a speed sufficient to yield the desired machine speed. ### Claim 8 (depends on 7) The electric drive system according to claim 7, wherein the electrical energy supply system includes one of an electrical generator and a connection to grid power. ### Claim 9 (depends on 8) The electric drive system according to claim 8, wherein the electrical energy supply system includes an electrical generator and wherein the electrical generator is driven by an internal combustion engine. ### Claim 10 (depends on 7) The electric drive system according to claim 7, wherein the electrical energy supply system includes an energy storage system. ### Claim 11 (depends on 10) The electric drive system according to claim 10, wherein the energy storage system includes a battery bank. ### Claim 12 (depends on 10) The electric drive system according to claim 10, wherein the energy storage system includes a capacitor bank. ### Claim 13 (depends on 7) The electric drive system according to claim 7, wherein driving the first electric drive motor at a fixed speed includes driving the first electric drive motor at its maximum allowable speed. ### Claim 14 (depends on 7) The electric drive system according to claim 7, wherein the controller is further programmed to determine the desired machine speed via a user interface. ### Claim 15 A method for operating, an electrically driven output stage to a series drive train to power a machine, the electrically driven output stage including a planetary gear set having a sun gear, a ring gear, and a carrier, a ring brake associated with the ring gear to maintain the ring gear in a locked position, a first electric drive motor rotationally linked to the sun gear, a second electric drive motor rotationally linked to the ring gear, and the carrier being rotationally linked to the series drive train, the method comprising: receiving an indication of a desired machine speed; operating the first electric drive motor, second electric drive motor, and ring brake to yield a machine speed matching the desired machine speed by: employing the ring brake to stop the ring gear and the second electric drive motor, and actuating the first electric drive motor at a speed sufficient to yield the desired machine speed when the desired machine speed is below a predetermined threshold speed; and employing the ring brake to release the ring gear, operating the first electric drive motor at a predetermined fixed speed, and actuating the second electric drive motor at a speed sufficient to yield the desired machine speed when the desired machine speed is at least as high as the predetermined threshold speed. ### Claim 16 (depends on 15) The method for operating an electrically driven output stage to a series drive train according to claim 15, wherein the predetermined fixed speed is a maximum allowable speed of the first electric drive motor. ### Claim 17 (depends on 15) The method for operating an electrically driven output stage to a series drive train according to claim 15, wherein receiving an indication of a desired machine speed includes determining the desired machine speed via a user interface of the machine. ### Claim 18 (depends on 15) The method for operating an electrically driven output stage to a series drive train according to claim 15, wherein the first electric drive motor and the second electric drive motor are of substantially the same power capacity. ### Claim 19 (depends on 15) The method for operating an electrically driven output stage to a series drive train according to claim 15, wherein the machine includes a service brake, and wherein operating the first electric drive motor, second electric drive motor, and ring brake to yield a machine speed matching the desired machine speed further comprises applying the service brake of the machine.