Hydraulic driving control device and hydraulic shovel with the control device

• US 20060235595A1
• Filed: 08/06/2004
• Published: 10/19/2006
• Est. Priority Date: 08/11/2003
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Sawada, Hiroshi
• Granted Patent: US 7,469,535 B2
• Time in Patent Office: Days
• US Class Current: 701/50
• CPC Class Codes: E02F 9/2235 including an electronic controller
• CPC Class Codes: E02F 9/2246 Control of prime movers, e.g. depending on the hydraulic load of work tools
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers

Abstract

A hydraulic operation controlling unit where the engine can be driven stably at a target output torque point and reduction in the work speed can be prevented at the time of light load, includes an engine control unit controlling the output of an engine, so that the output properties of the engine become equi-horsepower properties or approximately equi-horsepower properties in a predetermined engine speed range (N₂ to N₆) that includes engine speed N₃, which corresponds to a matching point M₃. A controlling unit increases or reduces the absorbing torque of a hydraulic pump in response to an increase or decrease in the engine speed, and thus, controls the absorbing torque of the hydraulic pump so as to make the output torque T₃ of the engine, which corresponds to matching point M₃, and the absorbing torque of the hydraulic pump coincide with each other.

Claims

1. A hydraulic operation controlling unit, comprising:

an engine;

a hydraulic pump that is operated by this engine;

a hydraulic actuator that is operated by pressurized oil that is discharged from this hydraulic pump;

an engine controlling means for controlling an output of said engine; and

a hydraulic pump absorbing torque controlling means for controlling an absorbing torque of said hydraulic pump, wherein

a matching point where the output torque of said engine and the absorbing torque of said hydraulic pump coincide with each other is predetermined in accordance with work contents, said engine controlling means controls the output of said engine in such a manner that output properties of said engine become equi-horsepower properties or approximately equi-horsepower properties in a predetermined range of the engine speed which includes an engine speed that corresponds to said matching point, and said hydraulic pump absorbing torque controlling means controls the absorbing torque of said hydraulic pump in such a manner that the output torque of said engine that corresponds to said matching point and the absorbing torque of said hydraulic pump are made to coincide with each other by increasing or reducing the absorbing torque of said hydraulic pump in accordance with an increase and a decrease in the engine speed.

2. The hydraulic operation controlling unit according to claim 1, wherein a memory means for storing a relationship between the output torque of said engine and the engine speed, and an engine speed detecting means for detecting an actual engine speed of said engine, are provided, and said engine controlling means obtains a torque value that is to be outputted by said engine from the relationship between the output torque of said engine and the engine speed that are stored in said memory means and the actual engine speed that is detected by said engine speed detecting means, so that the output of said engine can be controlled on a basis of the torque value that has been obtained.

3. A hydraulic excavator, comprising the hydraulic operation controlling unit according to claim 1.

4. A hydraulic excavator, comprising the hydraulic operation controlling unit according to claim 2.