Decoupling Hydraulic Pump Speed from Engine via Electric Motor Variator
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Solution Overview
Problem
In work machines with hydraulically powered auxiliary units, the engine speed often needs to be increased to provide additional hydraulic power, leading to inefficient engine operation as the speed of the hydraulic pump is directly tied to engine speed.
Innovation Solution
A system that decouples the speed of the hydraulic pump from the engine speed by using a planetary gear set to combine power inputs from both the engine and an electric motor, allowing independent control of the hydraulic pump speed through the electric motor's speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If engine speed is increased to provide additional hydraulic power, then hydraulic power availability is improved, but engine operation efficiency deteriorates
Solution Approach 1:
The power transmission path is segmented into two independent channels: one from the engine to the hydraulic pump, and another from the electric motor to the hydraulic pump through the variator. This segmentation allows the engine speed to be optimized for primary working unit operation while the electric motor independently controls hydraulic pump speed, resolving the contradiction between hydraulic power availability and engine efficiency.
Solution Approach 2:
The electric motor acts as an intermediary between the engine and the hydraulic pump. Instead of directly coupling engine speed to hydraulic pump speed, the electric motor mediates the power transmission, enabling independent control of hydraulic power while the engine operates at optimal efficiency points. The variator further mediates by providing variable speed ratio between the electric motor and hydraulic pump.
2Device complexity
If hydraulic pump speed is directly tied to engine speed, then system simplicity is maintained, but operational flexibility deteriorates
Solution Approach 1:
The system transitions from a static direct coupling between engine and hydraulic pump to a dynamic configuration where the variator provides continuously variable speed ratio. This dynamic capability allows the hydraulic pump speed to be independently adjusted according to actual hydraulic power needs while the engine operates at constant optimal speed, significantly improving operational flexibility without excessive complexity increase.
Solution Approach 2:
The electric motor serves multiple functions: it drives the hydraulic pump through the variator to provide hydraulic power, and simultaneously can be controlled to maintain engine operation at optimal efficiency points. This multi-functionality allows the system to achieve both simplicity and flexibility by using the electric motor for dual purposes.
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
This decoupling allows for more efficient engine operation by enabling the hydraulic pump to receive the necessary power without increasing engine speed unnecessarily, improving overall machine efficiency.
Implementation Method 1
a planetary gear set. The planetary gear set may include a first power input connected to the engine, a second power input connected to the electric motor, and a power output connected to the hydraulic pump
Data Source
AI summary
A work machine includes an engine for driving a primary working unit. At least one hydraulically powered auxiliary working unit is powered by a hydraulic pump. The engine and an electric motor both provide power to the hydraulic pump via a planetary gear set which sums the power inputs from the engine and the electric motor. The pump speed of the hydraulic pump is thereby decoupled from the engine speed of the engine.