Hitachi Construction Machinery Co., Ltd.

Junichi Hosono

Mitsuo Kihara

Akira Tatsumi

Seiji Tamura

Kazuo Asano

Kazuhiro Ichimura

Hideaki Sayama

Hiroyuki Adachi

Hiroshi Watanabe

Masakazu Haga

Eiji Egawa

Toshiaki Nishida

Saburou Yoshio

Saburo Yoshio

A calculating portion 7a calculates a distance from the tip end of a front device to an interference prevention area, and a detection line 7m detects a moving speed of a boom 1. If the tip end of the front device comes close to the interference prevention area when the boom 1 is moving upward, control is made such that, while continuing to move the boom 1 upward, a control gain calculating portion 7h and a multiplier 7i cooperatively calculate a target speed of an arm in the arm dumping direction (interference avoiding direction) corresponding to the boom-up speed, and an input limit value calculating portion 7c, an adder 7j and a minimum value selecting portion 7f cooperatively control the arm to move in the interference avoiding direction relative to a vehicle body. Interference avoidance control enabling the tip end of the front device to be moved smoothly along the vicinity of a boundary of the interference prevention area is thereby effected and the front device can be prevented from interfering with the vehicle body without reducing the maneuverability and the working efficiency.

Interference preventing system for construction machine

The current operational condition is discriminated as being the vehicle propulsion condition or the performing work condition. When the vehicle propulsion operational condition is discriminated, the maximum engine revolution speed is limited to a first revolution speed and the maximum displacement is limited to a first displacement value. When the performing work condition is discriminated, the maximum engine revolution speed is limited to a second revolution speed equal to or lower than the first revolution speed and the maximum displacement is limited to a second displacement value higher than the first displacement value. The first and second revolution speeds and the first and second displacement values are so determined that the first revolution speed multiplied by the first displacement value at least as relating to pressure for vehicle propulsion on level ground is less than the second revolution speed multiplied by the second displacement value as relating to the pressure for below the range of torque limitation control. By this, the pump output flow during vehicle propulsion on level ground is made lower than while performing work and, during vehicle propulsion, reduction of the pressure loss is made possible. Even with the identical pump pressure, the effective motor pressure is increased, so that its output torque can be increased. Because also the maximum displacement of the motor can be reduced according to the reduction of the maximum pump output flow amount, the construction of the hydraulic circuit can be made more compact.

Control device for hydraulically propelled work vehicle

Apparatus for controlling revolution speed of prime mover for

Engine revolution speed control device for a hydraulically driven vehicle

Growing community of inventors

Ibaraki, Japan

Junichi Hosono