초록 ▼

A control system for an electric lift truck that controls a traction motor and a hydraulic pump motor is disclosed. The speed of rotation of both motors is controlled by a pulse width modulated current supplied from a battery source by the controller in direct response to a demand communicated to th

A control system for an electric lift truck that controls a traction motor and a hydraulic pump motor is disclosed. The speed of rotation of both motors is controlled by a pulse width modulated current supplied from a battery source by the controller in direct response to a demand communicated to the controller through an interface manipulated by an operator. A pump driven by the pump motor supplies pressurized hydraulic fluid to a lift mechanism and a power assisted steering unit. A joystick with function switches mounted thereto is provided so that the operator steers with one hand while controlling truck propulsion and all functions of the lift mechanism with the other hand. The direct control of the pump motor speed enables a fully proportional control of the hydraulic system. The control system is a compact structure that requires minimal cabling and ensures that the hydraulic system operates with energy efficiency and minimal wear.

대표청구항 ▼

[ We claim:] [1.]1. A control system for an electric lift truck, the electric lift truck including a first electric motor for truck propulsion and a second electric motor connected to a hydraulic pump for supplying pressurized hydraulic fluid through a hydraulic circuit to a hydraulic lift mechanism

[ We claim:] [1.]1. A control system for an electric lift truck, the electric lift truck including a first electric motor for truck propulsion and a second electric motor connected to a hydraulic pump for supplying pressurized hydraulic fluid through a hydraulic circuit to a hydraulic lift mechanism, comprising:an interface for providing an integrated drive and hydraulic control system to permit an operator to control the propulsion of the electric lift truck and a plurality of functions of the hydraulic lift mechanism, the interface generating a plurality of electronic control signals in response to inputs through the interface by the operator;an electronic controller connected to the interface and the first and second electric motors for receiving the electronic control signals from the interface, and controlling a speed and a direction of revolution of the first electric motor, and a speed of revolution of the second electric motor in direct relation to the electronic control signals so that hydraulic functions are controlled by direct control of the second motor as well as incremental opening of control valves in response to the electronic control signals.