초록 ▼

In an electric lift truck, an asynchronous electric motor, a reversible sealed pump driven by the motor, communicating with the hydraulic actuators and also with a reservoir, a device which measures the angular position and the angular velocity of the motor, and a control and monitoring unit which c

In an electric lift truck, an asynchronous electric motor, a reversible sealed pump driven by the motor, communicating with the hydraulic actuators and also with a reservoir, a device which measures the angular position and the angular velocity of the motor, and a control and monitoring unit which causes the motor to be supplied according to the required speed of raising and lowering of the load support and on the basis of data supplied by the measuring device are used for raising and lowering the load support by means of one or more hydraulic actuators. There is a saving of energy in raising; there is also a recovery of energy in lowering, in which the motor acts as a generator to recharge the accumulator batteries of the lift truck.

대표청구항 ▼

[ What is claimed is:] [1.] System for raising and lowering the load support of an electric lift truck, comprising an electric motor supplied from a rechargeable source of electrical energy, a pump driven by the electric motor and communicating with a reservoir containing hydraulic fluid, and one or

[ What is claimed is:] [1.] System for raising and lowering the load support of an electric lift truck, comprising an electric motor supplied from a rechargeable source of electrical energy, a pump driven by the electric motor and communicating with a reservoir containing hydraulic fluid, and one or more hydraulic actuators supplied with the hydraulic fluid by the pump and connected to the load support for the upward and downward movement of the said support, characterized in that the electric motor is asynchronous, the pump is a reversible sealed pump, means of measuring the angular position and angular velocity of the asynchronous motor are provided, and an electronic control and monitoring unit is provided to control the supply to the asynchronous motor according to the required speed of raising and lowering of the load support and on the basis of data supplied by the measuring means, the asynchronous motor acting as a generator to recharge the electrical energy source when the load support is lowered.