Excavator Hydraulic Pump Control for Engine Torque Delay

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Solution Overview

Problem

Conventional excavator control systems do not account for the delay in rising engine torque, leading to a risk of the oil hydraulic pump's absorbing torque exceeding the engine's actual torque, resulting in decreased engine speed.

Innovation Solution

An excavator with a controller that delays the response of the oil hydraulic pump until the engine's actual torque rises to match the load, preventing the absorbing torque from exceeding the engine's torque by limiting the discharge rate and using a variation reducing unit to smooth torque transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the oil hydraulic pump responds immediately to load increase, then productivity is improved, but the absorbing torque temporarily exceeds the actual torque of the engine causing engine speed to decrease

Engineering Contradiction:

Improveresponse speed of oil hydraulic pumpVSAvoidengine speed stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The control device delays the response of the oil hydraulic pump until the actual torque of the engine rises to a level corresponding to the load. This preliminary timing adjustment ensures that the pump does not increase its absorbing torque before the engine is ready, preventing engine speed drops while still maintaining productive operation once the engine torque is sufficient.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the discharge rate of the oil hydraulic pump is increased, then productivity is improved, but the absorbing torque exceeds the engine torque causing harmful effects

Engineering Contradiction:

Improvedischarge rate of hydraulic pumpVSAvoidexcessive absorbing torque

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The control device monitors the actual torque of the engine and uses this feedback information to control the discharge rate of the oil hydraulic pump. By continuously comparing the engine's actual torque with the pump's absorbing torque requirements, the system adjusts the discharge rate to match the engine's capacity, preventing excessive absorbing torque while maximizing productivity.

Inventive Principle:

Principle #23Feedback

3Power

If the engine load is increased, then power output is improved, but the actual torque rises with delay causing control instability

Engineering Contradiction:

Improveengine power outputVSAvoiddelay in torque response

Core Design Contradiction:

PowerVSLoss of time

Solution Approach 1:

The control device anticipates the delay in actual torque response by delaying the pump's response until the torque level is reached. This preliminary timing coordination ensures that the pump's absorbing torque increases in sync with the engine's actual torque, eliminating control instability caused by the torque response delay while maintaining increased power output.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3951087B1excavator

Publication Date: 2023.06.14 SUMITOMO CONSTRUCTION MACHINERY

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AI summary

An excavator (100) includes a lower traveling body (1); an upper turning body (3) pivotally installed to the lower traveling body (1); an engine (11) installed in the upper turning body (3); a main pump (14) driven by the engine (11); and a controller (30) configured to control a flow rate of hydraulic oil discharged by the main pump (14). The controller 30 is configured to, when a load of the engine (11) increases, delay a response of the main pump 14 until an actual torque of the engine (11) rises up to a level corresponding to the load of the engine (11).