Auxiliary Hydraulic Braking for Engine Overspeed in Hydrostatic Drives
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Solution Overview
Problem
Agricultural vehicles equipped with hydrostatic drive systems often experience overspeed loads due to gravity or other external forces, which can cause engine damage as the excess power is not adequately absorbed by existing components, leading to increased engine and pump wear.
Innovation Solution
The implementation of an auxiliary hydraulic system with a processor-controlled system that measures engine rotation speed and generates a braking torque when it exceeds a threshold, using existing hydraulic components to counteract overspeed by transmitting the braking torque back to the engine, thereby reducing its rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If existing hydrostatic drive systems are used without additional braking devices, then device complexity is reduced, but engine overspeed damage occurs due to insufficient power absorption
Solution Approach 1:
The auxiliary hydraulic pump is integrated into the existing hydrostatic drive system and serves dual functions: normal auxiliary hydraulic operations and engine overspeed protection. By utilizing an existing component for multiple purposes, the system achieves reliable engine protection without adding dedicated braking devices, thus maintaining low device complexity while improving reliability.
2Reliability
If dedicated power mitigation devices are added to the pump, then engine protection is improved, but device complexity and cost increase
Solution Approach 1:
The auxiliary hydraulic pump automatically absorbs excess power during engine overspeed conditions through its own operational characteristics. The system uses the pump's natural hydraulic resistance and the existing hydraulic circuit to dissipate excess energy, eliminating the need for dedicated braking devices or complex control mechanisms while providing reliable engine protection.
3Device complexity
If internal friction of engine and pump is used to resist overspeed, then no additional devices are needed, but power absorption is insufficient to maintain acceptable overspeed levels
Solution Approach 1:
The auxiliary hydraulic pump acts as an intermediary power absorption mechanism between the engine and the hydraulic circuit. It provides additional resistance to overspeed by processing hydraulic fluid through its pumping action, thereby increasing power absorption capacity beyond what internal friction alone can provide, while still using existing system components.
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
Effectively mitigates engine overspeed without the need for additional braking or flow control devices, utilizing existing hydraulic systems to prevent damage from excessive power absorption, thus enhancing the safety and longevity of the engine and drive components.
Implementation Method 1
operating the respective auxiliary hydraulic component of at least one auxiliary hydraulic system to generate a respective braking torque at the respective auxiliary pump, and transmitting each respective braking torque to the engine
Data Source
AI summary
A method for operating an agricultural vehicle, the method including: generating an overdrive torque at a drive wheel motor of at least one ground drive system; transmitting the overdrive torque to the engine via a hydraulic ground drive circuit and a ground drive pump, to thereby bias the engine to operate at an increased rotation speed; measuring an engine rotation speed; comparing the engine rotation speed to a threshold value; and upon determining that the engine rotation speed satisfies the threshold value, operating the auxiliary hydraulic component of an auxiliary hydraulic system to generate a braking torque at a respective auxiliary pump, and transmitting each the braking torque to the engine to bias the engine to operate at a decreased rotation speed. An agricultural vehicle having a control system to perform the method is also provided.