Heated Valve Unit for Cold-Weather Asparagus Severing
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Solution Overview
Problem
Existing asparagus harvesters are impaired by low ambient temperatures that prevent the valve units from switching between firing and holding positions, leading to uncut spears and spear loss during harvesting.
Innovation Solution
Incorporating a heater proximate to the valve unit to maintain its operating temperature and using spear guides and interfering members to prevent lateral ejection of severed spears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a pneumatic valve unit is used to control the severing blade, then the severing operation can be automated and controlled remotely, but the valve unit fails to switch between firing and holding positions when ambient temperature is low
Solution Approach 1:
The patent applies parameter changes by introducing a heating element that changes the temperature parameter of the valve unit from low ambient temperature to optimal operating temperature. This allows the valve unit to maintain its switching functionality between firing and holding positions even when the ambient temperature is low, thereby resolving the reliability issue while preserving the automated control capability
Solution Approach 2:
The heating element acts as an intermediary between the cold ambient environment and the valve unit. It mediates the thermal interaction by providing heat to the valve unit, ensuring that the valve unit operates within its functional temperature range and can reliably switch positions despite the cold external conditions
2Device complexity
If the pick-up apparatus operates without lateral guides, then the structure is simpler, but severed spears eject laterally outward from the pick-up apparatus
Solution Approach 1:
Spear guides are introduced as intermediary elements between the severed spears and the external environment. These guides mediate the movement of spears by providing lateral containment, preventing them from ejecting outward while allowing forward movement, thus reducing spear loss with minimal structural addition
Solution Approach 2:
The spear guides function as thin structural elements that provide lateral containment without significantly increasing the overall complexity of the pick-up apparatus. These guides act as flexible boundaries that constrain spear movement in the lateral direction while maintaining simplicity in the overall apparatus design
3Device complexity
If the pick-up apparatus operates without an interfering member at the trailing end, then the structure is simpler, but severed spears pass outwardly through the trailing end and are lost
Solution Approach 1:
An interfering member is introduced as an intermediary element at the trailing end of the pick-up apparatus. This member mediates the interaction between the moving spears and the trailing end structure by providing a physical barrier that prevents spears from passing outwardly through the trailing end, thereby reducing spear loss with minimal structural modification
Solution Approach 2:
The interfering member segments the trailing end opening into a constrained passage, dividing the open trailing end into a controlled zone where spear movement is restricted. This segmentation prevents spear loss while maintaining relatively simple apparatus structure by adding only a localized structural element
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
Ensures consistent severing and collection of asparagus spears even in low temperatures, reducing uncut spears and loss during harvesting.
Implementation Method 1
a heater mounted proximate to the valve unit and configured to sufficiently heat the valve unit to enable the valve unit to switch between the firing position and the holding position in the presence of an ambient temperature sufficiently low to impair the valve unit from sufficiently switching between the firing position and the holding position
Data Source
AI summary
An asparagus harvester includes a chassis movable over a bed of growing asparagus. Spears above a selected height are severed at the ground by a severing assembly. A conveyor receives from a pick-up apparatus and conveys away asparagus spears severed by the severing assembly. The severing assembly includes a severing blade carried by a plunger mounted in a pneumatic cylinder. Conduits couple the pneumatic cylinder to a source of air under pressure through a valve unit operable for actuating the pneumatic cylinder to repeatedly fire and withdraw the plunger for repeatedly moving the severing blade back-and-forth along a stroke path between a raised set position and a lowered severing position proximate to the ground. A heater mounted proximate to the valve unit is configured to sufficiently heat the valve unit to enable the valve unit to operate in the presence of an ambient temperature sufficiently low to impair its operation.