JP2000220607A5

JP2000220607A5 -

Info

Publication number: JP2000220607A5
Application number: JP1999025161A
Authority: JP
Filing date: 1999-02-02
Publication date: 2004-10-14

Description

【００１０】
【課題を解決するための手段】
上記目的を達成するために、本発明の請求項１に係る発明は、原動機と、この原動機によって駆動される油圧ポンプ、及びパイロットポンプと、上記油圧ポンプから供給される圧油によって作動するアクチュエータと、上記油圧ポンプから上記アクチュエータに供給される圧油の流れを制御する流量制御弁と、この流量制御弁のストローク量を制御する操作手段と、上記油圧ポンプの最大吐出圧を規定する可変リリーフ弁と、この可変リリーフ弁のリリーフ圧を制御するリリーフ圧制御手段とを備えた建設機械の油圧駆動装置において、作動油温度を検出する温度検出手段を備えるとともに、上記リリーフ圧制御手段が、上記温度検出手段で検出された作動油温度に応じて上記パイロットポンプから吐出されるパイロット圧を制御する電磁比例弁を含み、この電磁比例弁から出力されるパイロット圧で上記可変リリーフ弁のリリーフ圧を制御するものから成る構成にしてある。[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention is a prime mover, a hydraulic pump driven by the prime mover, a pilot pump, and an actuator actuated by pressure oil supplied from the hydraulic pump. A flow control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the actuator; operating means for controlling the stroke amount of the flow control valve; and a variable relief valve for defining the maximum discharge pressure of the hydraulic pump When, in the hydraulic drive system for a construction machine that includes a relief pressure control means for controlling the relief pressure of the variable relief valve, provided with a temperature detection means for detecting a hydraulic oil temperature, the above relief pressure control unit, the temperature electromagnetic ratio for controlling the pilot pressure discharged from the pilot pump in accordance with the detected hydraulic oil temperature detecting means Includes a valve, are a configuration consisting controls the relief pressure of the variable relief valve in the pilot pressure output from the solenoid proportional valve.

Claims

A prime mover, a hydraulic pump driven by the prime mover, a pilot pump, an actuator operated by pressure oil supplied from the hydraulic pump, and a flow rate for controlling the flow of pressure oil supplied from the hydraulic pump to the actuator A control valve, operating means for controlling the stroke amount of the flow control valve, a variable relief valve for defining the maximum discharge pressure of the hydraulic pump, and relief pressure control means for controlling the relief pressure of the variable relief valve In the hydraulic drive system of construction machinery,
And temperature detection means for detecting the temperature of the hydraulic oil,
The relief pressure control means comprises a solenoid proportional valve which controls the pilot pressure discharged from the pilot pump in accordance with the working oil temperature detected by the temperature detecting means, a pilot pressure outputted from the solenoid proportional valve A hydraulic drive system for a construction machine, comprising controlling a relief pressure of the variable relief valve.

2. A hydraulic drive system for a construction machine according to claim 1, wherein the temperature detecting means is disposed upstream of the variable relief valve and in a position near the variable relief valve.