Patent ID: 9206896
Filing Date: 2015-12-08
Classification: F16H,Y10T

Abstract:
1. A transmission unit for use with a vehicle, the transmission unit comprising: a transmission including a gear train reconfigurable among a number of gear ratios and a hydraulic control system configured to set the gear train in one of the plurality of gear ratios, the hydraulic control system having a hydraulic reservoir, a hydraulic circuit, and a main pump mechanically driven to pressurize the hydraulic circuit, and an auxiliary hydraulic pressurization system coupled to the hydraulic reservoir and the hydraulic circuit, the auxiliary hydraulic pressurization system configured to maintain pressurization of the hydraulic circuit when the main pump is not mechanically driven, the auxiliary pressurization system including an auxiliary pump and a bypass valve coupled between the auxiliary pump and the hydraulic circuit, wherein (i) the hydraulic circuit includes a regulator configured to divert fluid supplied thereto from being used to pressurize the hydraulic circuit in response to fluid movement toward the regulator at a first pressure greater than a regulation pressure, (ii) the bypass valve is biased to a closed condition and configured to open in response to fluid movement from the auxiliary pump toward the hydraulic circuit at a second pressure greater than a threshold bypass pressure, and (iii) the regulation pressure and the threshold bypass pressure are substantially the same when the main pump is not mechanically driven.