Filing My First  PPA Myself- Detailed Description - Selective Asparagus Harvester

Real Provisional Patent Application continued from previous page

With the new method, the spear still crosses the top beam first, but instead of only producing an output during the time the spear is in the beam as was done with previous machines, the output lasts for lets say 0.1 seconds.  At any time during that pulse, if the lower detector is activated, then the blade is fired.  This delays the cut until much closer to the ground, causing the cut location to be much more accurate.

The old way, if a spear was leaning in the direction opposite to the direction of travel, the cut will be "early" and quite possibly not cut through the spear.  With the new method the cutter isn't tripped until the spear crosses the top beam, which is identical to the old way.  So there is no improvement for spears leaning rearward in so far as the accuracy, but it does allow the two beam system to work much better since it will still often cut the spear even with less than perfect accuracy.

The amount the spear can lean is determined by the forward speed of the machine and the length of time duration of the output pulse. The longer the pulse the further a spear can lean and still activate the cutter. The time period can be automatically calculated by the electronics to provide a fixed amount of lean at any particular speed.
 

The spear pickup system

The spear pick up system is composed of a plurality of rotating shafts mounted parallel to each other and spaced equally apart in the same plane, with rubber fingers covering the shafts.  Each shaft is rotating in the opposite direction of the shaft on either side.  The rotating rubber fingers are just long enough that they barely touch the fingers on the adjacent rollers.

Fig 3, item1 is a motor for rotating the shafts, 2 is the support member, 3 is one of the rotating shafts, 4 is the rotating rubber fingered rollers, 5 is the collection conveyor, and 6 are asparagus spears.

The bottom roller grabs the spears and exerts an upward force on them before they are cut. When the cutter cuts the spear, the spear is lifted up and passed to the next set of rollers, the transport rollers, and brought up to a higher elevation with each succeeding set of rollers.  Any number of roller sets may be used. A conveyor running along the bottom of the top set of rollers collects the spears as they are ejected from the last set of rollers.

In figure 4, item 4 is a spear of asparagus, 3 is the uppermost transport roller assembly, 2 is the lower transport roller assembly, and 1 is the pickup roller assembly.  Item 5 of Figure 5 shows details of the rubber fingers that make up the rollers.
 

The Spear Cutting System

The spears are cut by a series of pneumatic cylinders with blades affixed to the end of the piston rod of each cylinder.  The cylinders are lined up in a row across the asparagus bed and aligned with the optical sensors so that the field of view of each sensor corresponds with the width of a blade and cylinder.

Fig 6  is a side view of the cutter and its position relative to the pickup roller assembly and consists of; 1 pickup roller assembly, 2 spear of asparagus, 3 clevis mount for the air cylinder, 4  air cylinder, 5  blade extended to its full stroke, 6  piston rod, 7  blade in the retracted position.

Fig 7 is an isometric view of a cutter assembly with a plurality of air cylinders mounted side by side across the asparagus bed.  The pickup rollers are also shown.  1 is the air cylinder assembly, 2 is the pickup assembly, 3 is a blade in the retracted position, and 4 is the blade fully extended.

The cylinders are mounted at an angle to the ground of 30 to 60 degrees, although it is not limited to that range.

Fig 8 shows a side view of the cutting cylinder assembly.  1 is a blade, 2 is a blade mount, 3 is the clevis cylinder mount, 4 is a dashpot cylinder, and 5 is a check valve.

The cutting cylinder has a smaller dashpot type cylinder or gas spring, screwed into the rear head, and it cushions the cutting cylinder's piston, rod, and blade assembly from impact when the blade returns to a retracted position. 

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