Electric drive system in lift trucks
AssigneeFiat Om Carrelli Elevatori S.p.A.
InventorGuido Palleggi
Life of this patent
Estimating the term…
Abstract
An electric drive system in lift trucks has, for driving the lift truck driving wheels, at least one separate excitation electric motor provided with a stator and a rotor which are energized independently of each other by means of an electronic drive and control unit; by this arrangement, space can be saved on the lift truck and the lift truck can be rendered reliable, low in running cost, adaptable to varying load conditions, and adjustable as regards its operational parameters.
Claims16
An electric drive system for use in an electrically powered lift truck having a DC voltage supply and driving wheels, the drive system comprising:
- at least one separately excited electric motor having a stator and a rotor, each being interconnectable with the DC voltage supply for power supply, said motor being interconnectable with the driving wheels for moving the lift truck;
- microprocessor means for controlling power supply to said stator and said rotor, said microprocessor means including transistor means for separately energizing said stator and said rotor and including braking means for dynamically braking said lift truck, said braking means including means for disabling energization of said rotor while raising power supply to said stator,
- means for maintaining constant polarity, and
- means for simultaneously progressively enabling short circuit connection of said rotor, thereby allowing operation of said motor as a generator and allowing recharging of the DC voltage supply;
- memory means operatively interconnected with said microprocessor means for storing information to be executed and processed by said microprocessor means, said microprocessor means writing data to and reading data from said memory means;
- lift truck controls interconnected with said microprocessor means;
- electrical operation parameter feedback means, interconnected with said microprocessor means, for providing feedback relating to electrical operation parameters;
- and
- display and input means interconnected with said microprocessor means for displaying operation characteristics and parameters of the lift truck, for setting and changing operation parameters, and for providing visual indications of the lift truck operating conditions.
A method for controlling lift truck operation, the lift truck comprising an electrically powered lift truck having a DC voltage supply, an electric motor including a stator and a rotor, and driving wheels, said method comprising the steps of:
- energizing both the stator and the rotor with a first polarity to cause the lift truck to move in a first direction;
- energizing the stator with a second polarity opposite the first polarity while maintaining the rotor at the first polarity to cause the lift truck to move in a second direction opposite the first direction;
- disabling energization of the rotor while raising the power supply to the stator at the same running polarity and, at the same time, progressively enabling short circuit connection of the rotor to the DC voltage supply such that the motor operates as a generator to recharge the DC voltage supply and provide dynamic braking to the lift truck;
- providing stored programs and data to a microprocessor unit capable of
- writing data to and reading data from a memory means;
- providing feedback information relating to electrical operation parameters of the lift truck to the microprocessor unit;
- setting and changing operation parameters of the lift truck;
- displaying operation characteristics and parameters of the lift truck;
- and
- providing visual indications of the lift truck operating conditions.
Dependencies are inferred from the claim text.