Caterpillar Sarl

Shin Caterpillar Mitsubishi Ltd.

Seiichi Akiyama

Hideo Konishi

Masayuki Tanaka

Kenji Arai

Yusuke Shimizu

Tetsuya Yoshino

Masumi Nomura

Hiroyasu Nishikawa

Yuya Kanenawa

Sei Shimahara

Masashi Shibata

Manabu Nakanishi

Atsunobu Doi

In a work machine including a hydraulic pump (), a swing motor (), and swing relief valves (and), the amount of the swing operation (P) related to the swing motion of the swing motor () is detected, and the hydraulic pressure (P) supplied from the hydraulic pump () to the swing motor is also detected. Additionally, the required flow rate (F) of hydraulic oil required for the swing motor () is set based on the amount of the swing operation (P). In addition, the volume of relief (F) is estimated from the hydraulic pressure (P) based on the override characteristics of the swing relief valves (and). The discharge flow rate of the hydraulic pump () is controlled based on the value obtained by subtracting the volume of relief (F) from the required flow rate (F).

Hydraulic swing-controlling apparatus of work machine

A hydraulic pump driven by an engine, a hydraulic actuator, and a negative control circuit are provided on an open center hydraulic circuit, for guiding the hydraulic pressure in the center bypass to the hydraulic pump, as a negative control pressure. A negative control pressure control device controls the negative control pressure to an arbitrary value is also provided. The pump characteristic of the hydraulic pump is set such that the discharge flow rate is minimized when the negative control pressure in the negative control circuit is equal to or greater than a first predetermined pressure. Furthermore, an idling detection device that detects whether the hydraulic actuator is in a non-operated state or not is provided. The negative control pressure is forcefully controlled to the first predetermined pressure or higher when the non-operating state is detected.

Hydraulic control apparatus for work machine

Hydraulic oil supplied from pumps ( ),( ) to an attachment actuator ( ) is controlled by attachment control valves ( ),( ). Hydraulic oil supplied from pumps ( ),( ) to other actuators ( ),( ),( ),( ) is controlled by other control valves ( ) through ( ). Control conditions for operating the attachment actuator ( ) alone and control conditions for operating the attachment actuator ( ) simultaneously with any of the other actuators ( ),( ),( ),( ) are discriminated by the pilot pressure sensors ( ),( ),( ),( ). Control characteristics of the attachment control valves ( ),( ) are controlled by a controller ( ) based on the discriminated control conditions.

Fluid pressure circuit control system

Disclosed herein is a hydraulic-pump controller that is capable of controlling absorbed pump torque in good balance against engine output at all times. In this hydraulic-pump controller, the discharge flow rates of the operating oil that are discharged from hydraulic pumps ( ) according to manipulation of manipulation units ( ) are predicted based on the discharge pressure of the hydraulic pumps ( ) that are driven by an engine ( ), and based on the manipulation amount of the manipulation units ( ) that manipulate hydraulic actuators ( ), or a physical quantity correlating with the manipulation amount. Based on the predicted discharge flow rates and the discharge pressure, the absorbed torque of the hydraulic pumps is computed. Then, the predictive engine speed of the engine ( ) is computed from the absorbed torque of the hydraulic pumps ( ) computed. Based on the deviation between the computed predictive engine speed and the actual engine speed of the engine ( ), the regulators ( ) of the hydraulic pumps ( ) are controlled.

Hydraulic pump control device

Growing community of inventors

Tokyo, Japan

Seiichi Akiyama