Combine Rotor Start-Up Control for Constant Acceleration
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Solution Overview
Problem
Existing combine harvesters face challenges in smoothly ramping up the rotor speed during start-up, which leads to vibrations and reduced operator comfort.
Innovation Solution
A method utilizing a planetary gear assembly and a fluid circuit with a reversible pump and motor, along with a clutch system, to control the rotor speed during start-up, ensuring constant acceleration and reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotor speed is rapidly increased during start-up, then the productivity is improved, but the vibrations increase and operator comfort deteriorates
Solution Approach 1:
The system dynamically adjusts the acceleration rate of the rotor during start-up. The controller modulates the clutch engagement and pump operation to maintain a constant, controlled acceleration rate rather than allowing rapid speed increases. This dynamic control resolves the contradiction by enabling productivity improvement through speed increase while preventing harmful vibrations through controlled acceleration.
Solution Approach 2:
The system uses feedback from acceleration sensors to monitor the rotor acceleration rate and adjusts the clutch engagement and pump operation accordingly. The controller receives feedback on the actual acceleration rate and modulates the clutch slip control to maintain the desired constant acceleration rate, thereby preventing excessive vibrations while achieving necessary rotor speed for productivity.
2Device complexity
If a simple direct drive system is used, then the device complexity is reduced, but the ability to control acceleration rate and reduce vibrations is lost
Solution Approach 1:
The system introduces a clutch as an intermediary component between the engine and the rotor drive system. This clutch enables controlled torque transmission and acceleration rate management. The planetary gear assembly with its multiple components (ring gear, sun gear, carrier) acts as a mechanical intermediary that provides inherent torque multiplication and speed control capabilities, resolving the contradiction between simplicity and controllability.
Solution Approach 2:
The system uses a hydrostatic pump and motor arrangement to provide controlled power transmission. The pump, driven by the engine, drives the motor which in turn drives the planetary gear assembly. This hydraulic intermediary system allows precise control of the rotor acceleration rate while maintaining relative simplicity through the use of off-the-shelf hydraulic components.
3Power
If the clutch is fully engaged immediately, then the power transmission is maximized, but the rotor acceleration becomes uncontrolled and vibrations increase
Solution Approach 1:
The clutch engagement is made dynamic rather than static. The controller modulates the clutch engagement state during the start-up phase, transitioning from partial engagement to full engagement as the rotor accelerates. This dynamic control allows the system to maximize power transmission only when appropriate, while controlling acceleration rate during the critical start-up phase to prevent vibrations.
Solution Approach 2:
The system performs preliminary controlled acceleration using the clutch in a partially engaged state before full power transmission is applied. The clutch is initially engaged in a controlled slip state to gradually accelerate the rotor, and only after the rotor reaches a certain speed threshold does the clutch become fully engaged for maximum power transmission. This preliminary action prevents vibration-induced problems while still achieving full power utilization.
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
The method achieves a smooth and continuous start-up process for the rotor, reducing vibrations, improving operator comfort, and increasing productivity by maintaining constant acceleration.
Implementation Method 1
a fluid circuit including (i) a reversible pump that receives power from the engine and (ii) a motor that is fluidly connected to the pump
Implementation Method 2
a planetary gear assembly including (i) a first gear (e.g., a ring gear) that is mechanically connected to an output shaft of the engine, (ii) a second gear (e.g., a sun gear), and (iii) a carrier that is mechanically connected to both the first gear and the second gear
Implementation Method 3
a clutch having an input member that is either directly or indirectly connected to the output shaft of the engine and an output member that is connected to the first gear, wherein step (b) further comprises partially engaging and modulating the clutch to drive rotation of the first gear
Data Source
Figure 1
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AI summary
An agricultural vehicle has an engine (32), a threshing rotor (40), and a rotor drive system including a planetary gear assembly (206) and a fluid circuit for driving the threshing rotor (40) at a constant acceleration during a start-up procedure of the threshing rotor (40).