FLOW CONTROL DEVICE AND FLOW CONTROL METHOD FOR CONSTRUCTION MACHINE

摘要

Disclosed are a flow control device and a flow control method for a construction machine for preventing the loss of fluid exhausted from a hydraulic pump when a boom and an arm of an excavator are operated in combination. The flow control device for a construction machine according to the present invention includes: an engine; a variable capacity hydraulic pump connected to the engine; a first hydraulic cylinder and a second hydraulic cylinder connected to the hydraulic pump; a first control valve disposed in a center bypass channel of the hydraulic pump, the first control valve, in neutral, returning the fluid exhausted from the hydraulic pump to a hydraulic tank and, when switched, controlling the driving, stopping, and direction change of the first hydraulic cylinder; a second control valve disposed downstream of the center bypass channel of the hydraulic pump, the second control valve, in neutral, returning the fluid exhausted from the hydraulic pump to the hydraulic tank and, when switched, controlling the driving, stopping, and direction change of the second hydraulic cylinder; a regeneration fluid channel for supplementing and reusing fluid returned to the hydraulic tank during a compression stroke of the first hydraulic cylinder, and a regeneration valve disposed in the regeneration fluid channel; and a pressure-compensated flow control valve which is disposed in a meter-in fluid channel of a spool of the first control valve and limits the quantity of working fluid supplied from the hydraulic pump to the first hydraulic cylinder when the first hydraulic cylinder and the second hydraulic cylinder are operated in combination.

主权项

1. A flow control apparatus for a construction machine comprising:
an engine; a variable displacement hydraulic pump connected to the engine; a first hydraulic cylinder and a second hydraulic cylinder, which are connected to the hydraulic pump; a first control valve installed in a center bypass path of the hydraulic pump, the first control valve being configured to allow hydraulic fluid discharged from the hydraulic pump to be returned to a hydraulic tank in its neutral state and configured to control a start, a stop, and a direction change of the first hydraulic cylinder in its shifted state; a second control valve installed on a downstream side of the center bypass path of the hydraulic pump, the second control valve being configured to allow the hydraulic fluid discharged from the hydraulic pump to be returned to the hydraulic tank in its neutral state and configured to control a start, a stop, and a direction change of the second hydraulic cylinder in its shifted state; a regeneration flow path configured to supplement and reuse the hydraulic fluid that returns to the hydraulic tank during a retractable drive of the first hydraulic cylinder, and a regeneration valve installed in the regeneration flow path; and a pressure compensation type flow control valve installed in a meter-in flow path of a spool of the first control valve and configured to limit the flow rate of the hydraulic fluid supplied from the hydraulic pump to the first hydraulic cylinder during a combined operation of the first and second hydraulic cylinders.