Feed Mixer CVT Startup Pressurization to Prevent Loop Overtaking
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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 startup when the mechanical loop begins rotating before the hydrostatic loop can establish sufficient pressure.
Innovation Solution
Incorporating an additional pump to create a secondary flow of fluid into the closed circuit prior to the rotation of the input, and using a hydraulic accumulator to pressurize the circuit, along with a clutch mechanism to disengage power when pressure is below a threshold, ensuring the hydrostatic loop is pressurized before the mechanical loop starts rotating, thereby preventing overtaking and maintaining stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the mechanical loop begins rotating before the hydrostatic loop establishes sufficient pressure, then the startup time is reduced, but the mechanical loop overtakes the hydrostatic loop leading to failure
Solution Approach 1:
The system performs preliminary pressurization of the hydrostatic loop using an accumulator charged by a second pump before the input shaft begins rotation. This preliminary action ensures that sufficient hydraulic pressure is established in advance, preventing the mechanical loop from overtaking the hydrostatic loop during startup, thereby resolving the contradiction between reduced startup time and system reliability
2Reliability
If an additional pump is added to pressurize the hydrostatic loop before rotation, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The accumulator is charged in advance by the second pump during a preliminary phase before the input shaft rotates. This preliminary charging action ensures the hydrostatic loop is pre-pressurized, preventing overtaking and improving reliability without requiring complex real-time control mechanisms during operation
Solution Approach 2:
The accumulator serves as a self-contained energy storage device that automatically releases stored hydraulic pressure when needed, eliminating the need for complex electronic controls or sensors to manage the pressurization process, thereby improving reliability while minimizing added complexity
3Use of energy by moving object
If the clutch is engaged only when pressure is above threshold, then the energy efficiency is improved, but the response time increases
Solution Approach 1:
The clutch engagement is controlled by a feedback mechanism that monitors hydraulic pressure in the closed circuit. When pressure reaches the predetermined threshold, the clutch automatically engages, allowing full power transmission. This feedback-based control ensures energy efficiency by preventing the power source from operating under load before proper pressurization, while the automatic nature of the feedback response minimizes time delays
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 solution ensures that the hydrostatic loop is adequately pressurized before the mechanical loop begins rotation, preventing damage and failure by maintaining stable pressure and fluid flow, thus enhancing the reliability and efficiency of the CVT system.
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
an additional pump to create an additional flow of fluid, to incorporate into the closed circuit prior to the rotation of the input
Data Source
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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.