초록 ▼

A hydraulic accumulator is provided in the hydraulic system of an electric vehicle, such as a lift truck, for conserving its battery power by minimizing the frequency of energy draining pump start-ups during operation. Pressurized fluid stored in such accumulator is utilized for powering any of the

A hydraulic accumulator is provided in the hydraulic system of an electric vehicle, such as a lift truck, for conserving its battery power by minimizing the frequency of energy draining pump start-ups during operation. Pressurized fluid stored in such accumulator is utilized for powering any of the various hydraulically actuated work elements employed on the vehicle when the pump is not being run. The system further provides for automatically starting and stopping the pump to keep the pressure in the accumulator within a predetermined operating range and for starting the pump when required to achieve the desired actuation of a particular work element.

대표청구항 ▼

A hydraulic system for an electric vehicle including an electric motor and a battery for driving such motor, comprising: a single hydraulic pump operatively driven by said motor; a first hydraulic circuit for a work implement disposed within said hydraulic system and having a manually actuatable con

A hydraulic system for an electric vehicle including an electric motor and a battery for driving such motor, comprising: a single hydraulic pump operatively driven by said motor; a first hydraulic circuit for a work implement disposed within said hydraulic system and having a manually actuatable control valve, said control valve being infinitely positionable between a closed center position and a fully actuated position for selectively controlling fluid pressure from the hydraulic system to its work implement; means for automatically energizing said motor when the control valve is moved past a predetermined intermediate position toward its fully actuated position so as to provide fluid pressure from said pump to the hydraulic circuit under such conditions; a second hydraulic circuit disposed within said hydraulic system in parallel with said first circuit; and means including a hydraulic accumulator disposed within said hydraulic system for storing fluid energy produced by said pump in excess of that needed for said first hydraulic circuit for subsequent use in powering the second hydraulic circuit without the necessity of running said pump so as to reduce the energy drain on the battery by minimizing the frequency of pump start-ups during operation.