Feed Mixer CVT Startup Control for Hydrostatic Pressure Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In continuously variable transmission (CVT) systems for livestock feed mixers, the mechanical loop often overtakes the hydrostatic loop, leading to potential failure due to insufficient pressure and fluid loss, especially during start-up when high torque is required.
Innovation Solution
The implementation of a CVT system with a mechanical loop and a hydrostatic loop, where a secondary pump and accumulator ensure pressure is maintained in the closed circuit before rotation, and a clutch disengages power transfer when pressure is low to prevent mechanical overload, along with a direct-drive pump to manage internal leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the CVT starts in an off-center position to reduce starting torque, then the torque needed to begin rotation of mixing members is reduced, but the mechanical loop overtakes the hydrostatic loop leading to CVT failure
Solution Approach 1:
The system performs preliminary pressurization of the hydrostatic loop before starting the mixing members. The off-center start position is used to initially pressurize the hydraulic circuit, ensuring adequate fluid pressure is established before full power transfer occurs, thereby preventing mechanical loop overtaking while maintaining reduced starting torque requirements
Solution Approach 2:
The system uses feedback control through the off-center position mechanism to monitor and adjust the balance between mechanical and hydrostatic loops. The off-center positioning provides feedback on the pressure differential, allowing the system to maintain proper pressure balance and prevent mechanical loop overtaking during operation
2Productivity
If the mechanical loop rotates faster than the hydrostatic loop, then power transfer is improved, but fluid pressure is insufficient causing CVT failure
Solution Approach 1:
The off-center positioned elements act as an intermediary mechanism between the mechanical and hydrostatic loops. This intermediary position allows the system to control the rate of pressure buildup in the hydrostatic loop, ensuring it keeps pace with mechanical rotation and maintains adequate fluid pressure during power transfer operations
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 configuration prevents mechanical loop overtaking, ensuring stable operation by maintaining pressure and fluid flow, reducing the risk of CVT failure and enhancing energy efficiency by managing torque and fluid distribution effectively.
Implementation Method 1
a first pump to create a primary flow of fluid
Implementation Method 2
an accumulator to pressurize the closed circuit prior to the rotation of the output
Implementation Method 3
a clutch provided between the input and the output, in which the clutch is configured to disengage when a pressure of the closed circuit is below a predetermined threshold, and is configured to engage when the pressure of the closed circuit is above the predetermined threshold
Implementation Method 4
a direct drive pump drivingly connected to the input to create a direct flow of fluid
Data Source
AI summary
A transmission system for a feed mixer including a continuously variable transmission (CVT) is provided. The CVT includes a mechanical loop and a hydrostatic loop. The CVT is operated so that the mechanical portion of the CVT is prevented from overtaking the hydrostatic portion of the CVT at start up of the CVT.