Energy recovery arrangement for hydraulic fork-lift truck - uses spring loaded storage cylinder to accept high pressure fluid as load is lowered and returns energy for next lift

摘要

The hydraulic lifting mechanism uses a three way solenoid valve to control the distribution of hydraulic fluid between the lifting cylinder, a high pressure storage cylinder, and the hydraulic reservoir and pump. The hydraulic line from the lifting cylinder branches to the supply side through a solenoid valve, and to the energy recovery cylinder. The energy recovery cylinder contains a spring loaded piston, and as the load is lowered the hydraulic pressure is coupled to the recovery cylinder, storing the energy in the spring. Supply of the lifting cylinder is derived from the storage cylinder and from an electrically driven pump, by suitable sequence control of solenoid valves.