Hydrostatic Transmission Engine Speed Control for Stall Feedback
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Solution Overview
Problem
Hydrostatic transmissions in wheel loader machines do not provide engine lug feedback to operators during stall conditions, leading to uncertainty about the machine's workload capacity, unlike geared transmissions.
Innovation Solution
A control system that includes sensors and a controller to reduce engine speed below a threshold during stall conditions, emulating the engine lug feedback, and ramps the speed back to normal when the stall condition passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a hydrostatic transmission is used instead of a geared transmission, then fuel economy and high mileage are improved, but engine lug feedback during stall conditions is lost
Solution Approach 1:
The control system monitors transmission output speed and engine speed to detect stall conditions, then actively reduces engine speed to generate audible feedback that simulates traditional engine lug, informing the operator that the machine is working to its capacity
Solution Approach 2:
The system replicates the engine lug effect by actively controlling engine speed to drop during stall conditions, creating a copied version of the traditional feedback mechanism that exists in geared transmissions
2Adaptability or versatility
If a hydrostatic transmission is used instead of a geared transmission, then continuous variable transmission capability is improved, but operator awareness of machine workload is reduced
Solution Approach 1:
The control system provides feedback to the operator by generating audible engine lug feedback during stall conditions, enabling the operator to sense when the machine is working to its capacity despite the continuous variable transmission capability
Data Source
AI summary
A control system for controlling speed of an engine of a work machine having a hydrostatic transmission is disclosed. The control system may include a power source and a hydrostatic transmission operatively coupled to the power source. The control system may also include a controller capable of receiving information from the power source and the transmission and actively controlling an engine speed of the work machine to reduce the engine speed below a threshold value to emulate an engine lug during a stall condition.