ELECTRIC DRIVE UNIT FOR CONSTRUCTION MACHINE
First Claim
1. An electric drive unit for a construction machine equipped with an electricity storage device (7), a motor/generator (29) which supplies and receives electric power to/from the electricity storage device (7), a hydraulic pump (30) of the variable displacement type which is driven by the motor/generator (29), a plurality of hydraulic actuators (22, 23), a plurality of operating means (37A, 37B) which command the operation of the hydraulic actuators (22, 23), and a plurality of directional control valves (33, 34;
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33A, 34A) which respectively control the direction and the flow rate of hydraulic fluid supplied from the hydraulic pump (30) to the hydraulic actuators (22, 23) according to operating directions and operation amounts of the plurality of operating means (37A, 37B), comprising;
pump control means (31) which performs variable control on the displacement volume of the hydraulic pump (30);
motor/generator control means (28) which performs variable control on the revolution speed of the motor/generator (29); and
command control means (45;
45A;
66;
70) which calculates command values for the pump control means (31) and the motor/generator control means (28) according to the change in a demanded flow rate determined based on operation command levels from the plurality of operating means (37A, 37B),wherein the motor/generator control means (28) performs regeneration control for converting inertial force of a rotor of the motor/generator (29) into electric power and thereby charging the electricity storage device (7) when the revolution speed of the motor/generator (29) is decreased in response to a decrease in the demanded flow rate.
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Accused Products
Abstract
An electric drive unit for a construction machine is capable of increasing the operating time of the construction machine. The electric drive unit has an electricity storage device, a hydraulic pump of variable displacement type which is driven by a motor/generator, a regulator which performs variable control on the displacement volume of the hydraulic pump, a bidirectional converter which performs variable control on the revolution speed of the motor/generator, and an LS control device which controls the regulator and the bidirectional converter so that LS differential pressure Pls equals a target value Pgr. The bidirectional converter performs regeneration control for converting the inertial force of the rotor of the motor/generator into electric power thereby charging the electricity storage device when the revolution speed of the motor/generator is decreased in response to an excess of the LS differential pressure Pls over the target value Pgr.
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Citations
9 Claims
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1. An electric drive unit for a construction machine equipped with an electricity storage device (7), a motor/generator (29) which supplies and receives electric power to/from the electricity storage device (7), a hydraulic pump (30) of the variable displacement type which is driven by the motor/generator (29), a plurality of hydraulic actuators (22, 23), a plurality of operating means (37A, 37B) which command the operation of the hydraulic actuators (22, 23), and a plurality of directional control valves (33, 34;
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33A, 34A) which respectively control the direction and the flow rate of hydraulic fluid supplied from the hydraulic pump (30) to the hydraulic actuators (22, 23) according to operating directions and operation amounts of the plurality of operating means (37A, 37B), comprising;
pump control means (31) which performs variable control on the displacement volume of the hydraulic pump (30); motor/generator control means (28) which performs variable control on the revolution speed of the motor/generator (29); and command control means (45;
45A;
66;
70) which calculates command values for the pump control means (31) and the motor/generator control means (28) according to the change in a demanded flow rate determined based on operation command levels from the plurality of operating means (37A, 37B),wherein the motor/generator control means (28) performs regeneration control for converting inertial force of a rotor of the motor/generator (29) into electric power and thereby charging the electricity storage device (7) when the revolution speed of the motor/generator (29) is decreased in response to a decrease in the demanded flow rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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33A, 34A) which respectively control the direction and the flow rate of hydraulic fluid supplied from the hydraulic pump (30) to the hydraulic actuators (22, 23) according to operating directions and operation amounts of the plurality of operating means (37A, 37B), comprising;
Specification