Forage Harvester Drive System Chopper Drum Runout Reduction
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Solution Overview
Problem
The large inertia and speed of rotation of a chopper drum in forage harvesters result in an unacceptably long time for the drum to cease rotation when the braking system is not engaged, posing a safety risk to operators.
Innovation Solution
A drive system with a single charge pump hydraulically connected to both hydraulic variable displacement pumps, a clutch for engaging and disengaging the chopper drum from the prime mover, and a pilot-operated blocking valve to divert fluid flow through a high-pressure relief valve, along with an electronic controller for controlling the clutch and valve operations, reduces the runout time of the chopper drum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braking system is added to stop the chopper drum quickly, then operator safety is improved, but device complexity increases
Solution Approach 1:
The braking function is merged with the existing hydraulic drive system by using the hydraulic motor and pump as integral components of the brake mechanism. The hydraulic motor becomes part of the braking system, and its displacement is controlled to provide both drive and braking functions, eliminating the need for separate braking components.
Solution Approach 2:
The hydraulic pump and motor are designed to perform multiple functions: they serve as the drive system during normal operation and as the braking system when needed. By controlling the pump's displacement to zero or negative values, the same components provide both propulsion and deceleration, reducing overall system complexity.
2Reliability
If individual charge pumps are added to each hydraulic pump, then hydraulic circuit reliability is improved, but device complexity and cost increase
Solution Approach 1:
Two separate charge pumps that would normally serve different hydraulic circuits are merged into a single charge pump. This unified charge pump supplies hydraulic fluid to both the first and second hydraulic circuits, reducing component count while maintaining reliable hydraulic supply through centralized fluid management.
Solution Approach 2:
The single charge pump is designed to serve multiple hydraulic circuits simultaneously, performing the function of what would traditionally require separate charge pumps for each circuit. This multi-functional design reduces complexity while ensuring each hydraulic system receives adequate charging pressure.
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 solution effectively reduces the chopper drum's runout time from 50 seconds to around 6-7 seconds, enhancing operator safety by rapidly stopping the drum and simplifying the hydraulic circuit with fewer components and lower costs.
Implementation Method 1
a first hydraulic variable displacement pump connected with the chopper drum which pumps fluid around a first hydraulic circuit connected to a first motor, a second hydraulic variable displacement pump which pumps fluid around a second hydraulic circuit to a feed roll motor
Implementation Method 2
operating a pilot-operated blocking valve in the first hydraulic circuit to disconnect fluid flow between the first pump and the first motor and divert flow through a high pressure relief valve located internally of the first hydraulic variable displacement pump
Data Source
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AI summary
A drive system for a forage harvester is disclosed. In a forage harvester having a prime mover (10), a chopper drum (4) driven from the prime mover (10) via a drive train, and feed rolls (34,36), the drive system comprises a clutch (24) operable between an engaged condition connecting the chopper drum (4) to the prime mover (10) and a disengaged position in which the chopper drum (4) is disconnected from the prime mover, a first hydraulic variable displacement pump (16) connected with the chopper drum (4) which pumps fluid around a first hydraulic circuit connected to a first motor (46), a second hydraulic variable displacement pump (14) which pumps fluid around a second hydraulic circuit to a feed roll motor (38) connected with the feed rolls (34,36) of the forage harvester. The drive system further comprises a single charge pump (30) hydraulically connected to both the first hydraulic variable displacement pump (16) and the second hydraulic variable displacement pump (14).