Work Machine Engine Speed Control Under Hydraulic Pump Load
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Solution Overview
Problem
Existing work machines face challenges in quickly increasing engine rotational speed for high loads, leading to reduced workability due to the time required and subsequent fuel inefficiency.
Innovation Solution
A work machine equipped with a controller that adjusts the engine rotational speed and hydraulic pump discharge rate to match load demands, allowing for rapid engine speed changes while maintaining power, by reducing hydraulic pump discharge during speed increases and increasing it after reaching the desired speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotational speed of the engine is increased for high load, then the power output is improved, but the time required to raise the rotational speed increases
Solution Approach 1:
The controller performs preliminary action by reducing the discharge rate of the hydraulic pump before increasing engine rotational speed. This preliminary reduction in hydraulic pump discharge creates a torque demand gap that allows the engine speed to rise quickly without being immediately counteracted by high torque demand, thus resolving the contradiction between achieving high power output and minimizing the time to reach it
2Productivity
If the rotational speed of the engine is increased quickly, then the workability is improved, but the fuel consumption increases
Solution Approach 1:
The controller implements periodic action by alternately adjusting the hydraulic pump discharge rate and engine rotational speed in controlled phases. During the speed increase phase, the pump discharge is reduced; once the target speed is reached, the pump discharge is increased. This periodic, phased approach allows quick response for improved workability while avoiding sustained high fuel consumption
3Use of energy by moving object
If the engine rotational speed is kept low for fuel efficiency, then the fuel consumption is reduced, but the response to high load demands is delayed
Solution Approach 1:
The system applies dynamics by making the engine rotational speed and hydraulic pump discharge rate adjustable and responsive to real-time load conditions. The controller dynamically switches between low-speed fuel-efficient operation and high-speed high-power operation based on hydraulic actuator load, resolving the contradiction between maintaining low fuel consumption and ensuring rapid response to high load demands
Data Source
AI summary
Provided is a work machine capable of achieving both low fuel consumption and ensuring of workability. The work machine is configured to, in a state where an output of an engine or hydraulic pump has increased to an increase threshold (S12: Yes) with the rotational speed being at a first rotational speed (S11: Yes), raise the rotational speed from the first rotational speed to a second rotational speed (S13); in a process of raising the rotational speed to the second rotational speed, output, to a regulator, a signal instructing reduction in the discharge rate (S14) so as to keep the output of the engine or hydraulic pump constant; and after the rotational speed has reached the second rotational speed, output, to the regulator, a signal instructing increase in the discharge rate (S16) so as to make the output of the engine or hydraulic pump have a value corresponding to a request load.