Chopper Housing Air Gap Reduces Back Pressure

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Solution Overview

Problem

Conventional combine designs experience back pressure buildup due to restricted air flow, despite vents upstream of the chopper rotor, and the close proximity of the chopper rotor's shroud to the blades further restricts air flow.

Innovation Solution

The design includes a chopper housing that is open above and to the rear of the chopper rotor, allowing air to flow unrestricted out of the combine through a gap between the rear hood and the chopper rotor, and through the chopper rotor itself without being affected by the blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If vents are placed upstream of the chopper rotor to allow air to escape, then back pressure is reduced, but the close proximity of the shroud to the blades further restricts air flow

Engineering Contradiction:

Improveback pressureVSAvoidair flow path length

Core Design Contradiction:

Stress or pressureVSLength of moving object

Solution Approach 1:

The patent introduces a vertical dimension for air flow by creating an opening in the top wall above the chopper rotor. This allows air to escape upward (vertical dimension) in addition to the traditional horizontal flow path, effectively adding another escape route that reduces back pressure without requiring longer horizontal flow paths

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent extracts the air flow restriction problem by removing the top wall section above the chopper rotor to create an opening. This extraction eliminates the shroud's restrictive effect in that region while maintaining the shroud's protective function elsewhere, allowing air to escape freely from the enclosed space

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the chopper housing is enclosed with a shroud around the rotor, then material containment is improved, but air flow is restricted due to close proximity of shroud to blades

Engineering Contradiction:

Improvematerial containmentVSAvoidair flow

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by maintaining the enclosed shroud structure in most areas for material containment, but specifically opens the top wall above the chopper rotor where air flow is needed. This localized modification preserves containment where necessary while enabling air flow where required, resolving the contradiction between containment and air flow

Inventive Principle:

Principle #3Local quality

3Productivity

If the blower generates substantial air flow to carry MOG to the chopper assembly, then cleaning function is improved, but back pressure builds up if air cannot escape

Engineering Contradiction:

Improvecleaning functionVSAvoidback pressure

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The patent converts the harmful back pressure buildup into a beneficial escape path by creating the opening above the chopper rotor. The air flow that would otherwise create back pressure is now directed upward through the opening, transforming the problematic pressure buildup into an effective air escape route that supports the blower's cleaning function

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 design significantly reduces back pressure inside the combine by allowing unobstructed air flow out of the combine, enhancing air flow through the chopper rotor and above it, and preventing back flow of air.

Implementation Method 1

a blower disposed in the interior of the housing, the blower configured to generate an air stream in a substantially rearward direction

Methodology Applied

Scientific EffectAir flow:

Implementation Method 2

a chopper rotor assembly disposed within the interior at a location below the rear hood of the housing, the chopper rotor assembly including a chopper rotor mounted about a hub for rotation about an axis defined by the hub and a plurality of blades coupled to the hub of the chopper rotor for chopping the residue as it is received via the air stream

Methodology Applied

Scientific EffectMechanical chopping:

Implementation Method 3

Methodology Applied

Scientific EffectAir flow through gap:

Data Source

PatentUS12284948B2Cross vented residue disposal system for an enclosed combine body

Publication Date: 2025.04.29 DEERE & CO

AI summary

A combine harvester includes a housing having a rear hood and defining an interior, a blower for generating an air stream in a substantially rearward direction, and a cleaning system separating residue from a crop material such that the residue is transported via the air stream rearwardly to be discharged from the housing. A chopper rotor assembly is disposed within the interior below the rear hood and includes a chopper rotor having a plurality of blades for chopping the residue as it is received via the air stream. A chopper housing is disposed within the interior and defines an inlet of the chopper rotor for receiving the residue and an outlet spaced rearward from the chopper rotor for discharge of the chopped residue from the interior of the housing. An air gap through which the air stream may exit the interior is defined between the rear hood and chopper rotor.