Wheel Loader Engine Speed Control at Hydraulic Stroke Ends
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Solution Overview
Problem
Existing wheel loader technologies experience reduced working efficiency and increased fuel consumption when hydraulic cylinders reach their stroke ends, leading to potential delays and operational inefficiencies.
Innovation Solution
A work vehicle equipped with a vehicle body controller that limits the engine's upper rotational speed based on accelerator and brake pedal inputs, torque converter speed ratio, hydraulic pump discharge pressure, and hydraulic cylinder stroke amounts to maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine rotational speed is limited when a hydraulic cylinder reaches the stroke end, then fuel consumption is reduced, but working efficiency may be compromised
Solution Approach 1:
The patent applies dynamics by making the engine rotational speed limit variable rather than fixed. The controller dynamically adjusts the upper limit rotational speed based on real-time detection of hydraulic cylinder stroke amounts. When the stroke end is approached, the speed limit is reduced to prevent shock and energy waste; when the cylinder is away from the stroke end, the speed limit is maintained at higher levels to ensure working efficiency. This dynamic adjustment resolves the contradiction between fuel consumption reduction and working efficiency maintenance.
Solution Approach 2:
The patent changes the parameter of engine rotational speed limit based on the stroke amount of the hydraulic cylinder. By detecting the position of the piston in the hydraulic cylinder and adjusting the engine speed limit accordingly, the system optimizes fuel consumption only when necessary (near stroke end) while maintaining high speed during normal operation. This parameter change approach allows selective energy reduction without compromising overall productivity.
2Reliability
If the engine rotational speed is reduced to prevent shock at stroke end, then hydraulic system stability is improved, but operational responsiveness deteriorates
Solution Approach 1:
The patent applies preliminary action by detecting when the hydraulic cylinder is approaching the stroke end and proactively reducing the engine rotational speed limit before the piston actually reaches the stroke end position. This advance adjustment prevents shock and hydraulic fluid relief from occurring in the first place, thereby maintaining system stability without needing to respond reactively. The preliminary speed reduction ensures smooth operation while preserving responsiveness during the majority of the operational cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces fuel consumption while maintaining working efficiency by preventing engine stalling and hydraulic fluid relief at stroke ends, ensuring smooth operations.
Implementation Method 1
a torque converter for amplifying a torque transmitted from the engine
Implementation Method 2
a loading hydraulic pump driven by the engine and supplying a hydraulic oil to the hydraulic cylinder
Data Source
AI summary
Provided is a work vehicle capable of reducing the fuel consumption while maintaining the working efficiency. A wheel loader 1 comprising a vehicle body controller 5, 5A for controlling an engine 41, wherein the vehicle body controller 5, 5A limits an upper limit rotational speed of the engine 41 based on an accelerator pedal step-on amount α, a brake pedal step-on amount β, a torque converter speed ratio e which is a ratio of a rotational speed of a torque converter 42, a discharge pressure P1 of a loading hydraulic pump 44, and a stroke amount S1 of lift arm cylinders 22 or a stroke amount S2 of a bucket cylinder 24.