Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

A power split and power convergence combined hydro-mechanical hybrid transmission device includes an input member, a power split mechanism, a mechanical transmission mechanism, a power convergence mechanism, an output member, a hydraulic transmission mechanism, a clutch assembly, and a brake assembly. The input member is connected to the power split mechanism, the power convergence mechanism is connected to the output member, and the clutch assembly connects an output end of the power split mechanism to an input end of the mechanical transmission mechanism and an input end of the hydraulic transmission mechanism and connects an input end of the power convergence mechanism to an output end of the mechanical transmission mechanism and an output end of the hydraulic transmission mechanism. The clutch assembly and the brake assembly provide a continuous transmission ratio between the input member and the output member.

A power split and power convergence combined hydro-mechanical hybrid transmission device includes an input member, a power split mechanism, a mechanical transmission mechanism, a power convergence mechanism, an output member, a hydraulic transmission mechanism, a clutch assembly, and a brake assembly. The input member is connected to the power split mechanism, the power convergence mechanism is connected to the output member, and the clutch assembly connects an output end of the power split mechanism to an input end of the mechanical transmission mechanism and an input end of the hydraulic transmission mechanism and connects an input end of the power convergence mechanism to an output end of the mechanical transmission mechanism and an output end of the hydraulic transmission mechanism. The clutch assembly and the brake assembly provide a continuous transmission ratio between the input member and the output member.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor. A desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model's output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor. A desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model's output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydraulic pump and a hydraulic motor rotationally coupled in parallel with a first planetary gear set and a second planetary gear set. In the system, sun gears of the planetary gear sets are rotationally coupled to the hydraulic motor, a carrier of the first planetary gear set is rotationally coupled to a first clutch and a second clutch, and a ring gear of the second planetary gear set is rotationally coupled to a third clutch.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydraulic pump and a hydraulic motor rotationally coupled in parallel with a first planetary gear set and a second planetary gear set. In the system, sun gears of the planetary gear sets are rotationally coupled to the hydraulic motor, a carrier of the first planetary gear set is rotationally coupled to a first clutch and a second clutch, and a ring gear of the second planetary gear set is rotationally coupled to a third clutch.

Methods and systems for a transmission are provided herein. In one example, a hydraulic system is provided that includes a boost pump, a relief valve in fluidic communication with the boost pump and a reservoir, and a plurality of control valves in fluidic communication with the boost pump, positioned downstream of the relief valve, and in fluidic communication with a plurality of hydraulic devices. The hydraulic system further includes a controller designed to actively adjust a position of the relief valve based on an aggregate hydraulic pressure demand of the plurality of hydraulic devices to alter a boost pressure of a hydraulic fluid supplied to the plurality of control valves.

An automotive axle includes a housing including gears and a bath lubricating the gears, the bath including gear oil and about 0.1 to 5 wt. % secondary alcohol ethoxylate based on total weight of the bath such that during automotive operation at temperatures less than a threshold, reverse micelles form to trap air bubbles in the bath, emulsifying the bath, and at temperatures greater than the threshold, the reverse micelles dissipate.