Auxiliary pump system for hybrid powertrains

A system in a motor vehicle, the system comprising:

• an automatic transmission configured to control an output speed ratio of the motor vehicle;
• a hydraulic control system having an engine driven pump and a plurality of clutches configured to control the automatic transmission;
• a first control device having an open state and a closed state, the first control device in fluid communication with the hydraulic control system;
• a hydraulic transformer having a first pump/motor unit connected with a second pump/motor unit, wherein the second pump/motor unit is in fluid communication with the first control device;
• a second control device having an open state and a closed state, the second control device in fluid communication with the first pump/motor unit;
• and
• an accumulator for storing and releasing the hydraulic fluid, the accumulator in fluid communication with the second control device,
• wherein the accumulator is charged with pressurized hydraulic fluid when the first control device and the second control device are in the open state and the engine driven pump is operational and wherein the pressurized hydraulic fluid from the engine driven pump drives the second pump/motor unit, the second pump/motor unit drives the first pump/motor unit, and the first pump/motor unit delivers a flow of pressurized hydraulic fluid having a higher pressure and a lower flow than the pressurized hydraulic fluid from the engine driven pump to the accumulator,
• wherein the accumulator stores the pressurized hydraulic fluid when the second control device is in the closed state, and
• wherein the accumulator discharges the pressurized hydraulic fluid to the hydraulic transformer when the second control device is in the open state and when the engine driven pump is non-operational and wherein the pressurized hydraulic fluid from the accumulator drives the first pump/motor unit, the first pump/motor unit drives the second pump/motor unit, and the second pump/motor unit delivers a flow of pressurized hydraulic fluid having a lower pressure and a higher flow than the pressurized hydraulic fluid from the accumulator to the plurality of clutches in the hydraulic control system.