The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 24, 2016
Filed:
May. 10, 2012
Yasutaka Tsuruga, Moriyama, JP;
Kiwamu Takahashi, Koka, JP;
Tatsuo Takishita, Koka, JP;
Hajime Kurikuma, Koka, JP;
Yasutaka Tsuruga, Moriyama, JP;
Kiwamu Takahashi, Koka, JP;
Tatsuo Takishita, Koka, JP;
Hajime Kurikuma, Koka, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
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 the fixed displacement type which is driven by a motor/generator, a plurality of directional control valves which respectively control the flow of hydraulic fluid supplied to a plurality of hydraulic actuators, a bidirectional converter which performs variable control on the revolution speed of the motor/generator, and an LS control device which controls 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.