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:
Aug. 24, 2021
Filed:
Mar. 14, 2018
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Kouhei Ogura, Tsuchiura, JP;
Katsuaki Kodaka, Tsukuba, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A construction machine is provided. If the rotational speed of a prime mover is set lower than a rated rotational speed and the delivery rate of a hydraulic pump is lowered, the construction machine can prevent deterioration of the operability in slow speed operation works by keeping wide a lever operation range in which the rate of flow supplied to a hydraulic actuator is variable. A center bypass control valve () is arranged downstream of a plurality of directional flow control valves () in a center bypass line (), and if an engine rotational speed (N) detected by a rotational speed sensor () is lower than a rated rotational speed (Nmax), a controller () calculates a combined opening area obtained by combining opening areas of the plurality of directional flow control valves in the center bypass line based on operation pilot pressures (Pp, Ppto Pp) detected by pressure sensors () and controls the center bypass control valve such that an opening area of the center bypass control valve becomes smaller than the combined opening area.