Construction machinery

Abstract

The invention provides a piece of construction machinery, comprising an oil hydraulic circuit which drives a bucket rod by pressure oil flows out from an oil chamber on a cylinder bottom of a boom cylinder. The construction machinery comprises a control device (30) which is provided with a control executing determining portion (300), a confluence control portion (301), and an output capacity reduction portion (302). The control executing determining portion (300) determines whether control start conditions are satisfied. The confluence control portion (301) controls inflow of the pressure oil which flows out from the oil chamber on the cylinder bottom of the boom cylinder to a stick cylinder (8). The output capacity reduction portion (302) controls output capacity of a main pump (12L). When the control device determines movable arm operation amount on a descent direction is in a scheduled intermediate operating area and bucket rod operation amount on an opening direction is in a scheduled upper limit side operating area through the control executing determining portion, the pressure oil which flows out from the oil chamber on the cylinder bottom of the boom cylinder flows in an oil chamber on a side a rod of the stick cylinder through the confluence control portion. Output capacity of the main pump is limited by the output capacity reduction portion.

Description

technical field [0001] The present invention relates to a construction machine provided with a hydraulic circuit that effectively utilizes pressure oil flowing out of a bottom-side oil chamber of a boom cylinder when the boom is operated in a downward direction. Background technique [0002] Conventionally, there is known a boom lowering regeneration circuit that supplies pressurized oil flowing out of the bottom side oil chamber of the boom cylinder to the rod side oil chamber of the boom cylinder when the boom is operated in the lowering direction (for example, refer to Patent Document 1 ). [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 10-89317 [0004] However, since the rod penetrates the oil chamber, the volume of the rod-side oil chamber of the boom cylinder is smaller than that of the bottom-side oil chamber of the boom cylinder, so the total amount of pressurized oil flowing out of the bottom-side oil chamber cannot be recycled, Since the re...

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Problems solved by technology

[0004] However, since the rod penetrates the oil chamber, the volume of the rod-side oil chamber of the boom cylinder is smaller than that of the bottom-side oil chamber of the boom cylinder, so the total amount of pressurized oil flowing out of the bottom-side oil chamber cannot be recycled, Residual pressurized oil that cannot be recycled is returned to the tank, so it is difficult to say that the effective reuse of energy is sufficiently pursued

In addition, even when the pressure oil flowing out from the bottom side oil chamber of the boom cylinder is supplied to other hydraulic cylinders other than the boom, it may be required to be larger than the bottom side oil chamber of the boom cylinder depending on the operating state of the construction machine. The pressure of the outflowing pressure oil is higher, and due to the complexity of the oil supply path to other hydraulic cylinders, etc., the effective use of the pressure oil outflow from the cylinder bottom side oil chamber of the boom cylinder cannot be fully achieved.

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