Asparagus harvester
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related to a vegetable harvester an more particularly to apparatus for harvesting asparagus. Still more particularly, this invention relates to apparatus which will sense the presence of a mature asparagus spear and includes asparagus severing mechanism which is guided downwardly along the length of the spear to the base of the spear in which position the severing mechanism is activated to sever the spear. 
     2. Description of Prior Art and Objects 
     Traditionally, asparagus is grown as individual spear in a bed of spears. The asparagus spears do not all mature at the same time and it is generally desirable to select for harvesting only those spears which are of a proper height and breath. Traditionally, asparagus harvesting has been accomplished with manual labor. With the increasing labor costs, and the short season manual labor is expensive and not always readily available. 
     Various attempts have been made heretofore to provide a mechanical asparagus harvester such as that disclosed in U.S. Pat. No. 887,466 issued to David on May 12, 1908; U.S. Pat. No. 2,581,119 issued to Matteoli on Jan. 1, 1952; U.S. Pat. No. 2,690,043 issued to Marihart on Sept. 28, 1954; U.S. Pat. No. 3,447,292 issued to Rehmke on June 3, 1969; U.S. Pat. No. 3,609,949 issued to Neal on Oct. 5, 1971; and U.S. Pat. No. 4,007,579 issued to Wadekamper on Feb. 15, 1977. 
     Asparagus spears do not mature in a controlled cycle but rather randomly mature. It is desirable that the mature spears be harvested while leaving undamaged the immature spears. Accordingly, it is an object of the present invention to provide an asparagus harvester which will harvest mature spears with minimal disturbance to adjacent immature spears. 
     The apparatus harvestor constructed according to the present invention contemplates an asparagus spear height sensing, divider head which is mounted on a mobile frame a distance above the ground equal substantially to the predetermined height of mature asparagus spears. The head includes spaced apart, rearwardly converging divider legs which laterally inwardly direct the upper portions of the mature asparagus spears as the harvestor is forwardly propelled. 
     Mounted below and trailing the head is a guide foot having spaced apart guide legs which receive the mature spears therebetween. Severing mechanism is mounted on the foot which is mounted on a generally vertical, horizontally yieldable, vertically movable spring. As the foot is moved downwardly, the guide legs guide along the outer surface of the mature asparagus spear, even though the spear is curved or skewed. The mounting spring is selected of such material that its stiffness is less than the stiffness of an asparagus spear so that the spring, rather that the spear, will horizontally yield as the guide foot guides along the contour of the asparagus stalk spear to a position adjacent the base of the spear. Accordingly, it is an object of the present invention to provide an asparagus harvester which will guide a severing mechanism from a raised position along the contour of the asparagus spear to the base of the spear. 
     It is another object of the present invention to provide an asparagus harvester of the type described including a guide for guiding a severing mechanism in a path following the contour of an asparagus spear to a position adjacent the base of the spear. 
     Yet another object of the present invention is to provide an asparagus harvester of the type described including apparatus mounting severing mechanism for universal movement in any horizontal direction as it is being moved vertically and guide mechanism for guiding the severing mechanism along the contour of the stalk to a position adjacent the base of the stalk. 
     Still another object of the present invention is to provide an asparagus harvester including severing mechanism mounted on a guide foot which guides along the outer stalk surface as it is moved vertically and is mounted on a horizontally yieldable member which allows the severing mechanism to horizontally move as it is being vertically moved. 
     A further object of the present invention is to provide an asparagus harvester for selectively harvesting asparagus spears of a predetermined height and a predetermined breath. 
     A still further object of the present invention is to provide an asparagus harvester including a height sensing head including laterally spaced apart, forwardly projecting divider legs and a guide foot, vertically movably mounted on the height sensing head and having laterally spaced apart, forwardly projecting guide legs for guiding along a mature asparagus spear, and spear severing mechanism mounted on the guide foot. 
     Another object of the present invention is to provide an asparagus harvester of the type described having horizontally yieldable, spear severing mechanism which will horizontally yield in any direction as it vertically moves and follows the contour of a mature asparagus spear so as not to break the asparagus spear as it guides therealong. 
     Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds. 
     SUMMARY OF THE INVENTION 
     An asparagus harvester including a mobile frame, movable in a forward path of travel, severing mechanism on the frame for severing at least one mature spear in a bed of asparagus spears; apparatus for vertically moving the severing mechanism between a raised inoperative position and a lowered position adjacent the base of the spear including mechanism permitting the severing mechanism to horizontally move in any horizontal direction as the severing mechanism moves downwardly; and mechanism for horizontally guiding the severing mechanism in a path following the contour of the spear as the severing mechanism moves between the raised and lowered positions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more readily understood by referring to the accompanying drawings, in which: 
     FIG. 1 is a front elevational view of an asparagus harvester constructed according to the present invention; 
     FIG. 2 is a side elevational view thereof; 
     FIG. 3 is an enlarged sectional plan view of the height sensing, divider head, taken along the line 3--3 of FIG. 2; 
     FIG. 4 is an enlarged top plan view of the guide foot and spear severing mechanism, taken along the line 4--4 of FIG. 2; 
     FIG. 5 is a schematic diagram of an electrical control circuit for controlling the apparatus illustrated in FIGS. 1 through 4; 
     FIG. 6 is top plan view, similar to FIG. 4, illustrating a slightly modified embodiment, taken along the lines 6--6 of FIG. 7; and 
     FIG. 7 is a sectional side view, taken along the line 7--7 of FIG. 6. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     An asparagus harvestor, constructed according to the present invention, generally designated 9, is provided for harvesting a mature, growing asparagus spear or stalk, generally designated S, of predetermined height, without disturbing an immature asparagus stalk, generally designated 12, having a height less than the predetermined height. The harvesting apparatus 9 includes a plurality of harvesting units 10 mounted on a mobile frame, schematically designated F, which is mounted on a hydraulic lift system (lift system) conventially provided on a mobile vehicle (not shown) such as a tractor having spaced apart wheels that span the asparagus bed A. The asparagus bed A will typically include randomly spaced spears S which have grown to at least a predetermined height and immature spears 12 which have not yet grown to the predetermined height. Of the mature height spears S, some will have a breadth B which is at least a predetermined mature breadth and some will have a breadth B which is less than a mature breadth. 
     Although it should be understood that a plurality of the asparagus harvesting units 10 may be mounted on the frame F, only one such unit 10 is illustrated will be described in detail. The harvesting units 10 would typically be laterally spaced and longitudinally staggered along the length of the frame F which is mounted transverse to the length of the asparagus bed A and transverse to the forward direction of travel, represented by the arrow T. 
     Each harvesting unit 10 includes a height sensing divider head, generally designated 14, mounted on the frame F via a pair of upstanding guide rods 16 which are fixed, at their upper ends, to a mounting block 18, fixed to the frame F. The height sensing divider head 14 comprises a generally U shaped plate having a pair of forwardly projecting, height sensing, spear divider legs 20 which are spaced apart to provide a forwardly opening, stalk receiving channel 22. The width of the channel 22 might typically be four inches. 
     The frame F will typically be vertically adjustable via hydraulically or pneumatically controlled lift mechanism (not shown) conventionally provided on farm tractors to vertically adjust the level of the divider head 14 such that the underside 14a of the divider head is spaced from the ground G a distance substantially equal to the predetermined height of the asparagus spears to be harvested. This distance may typically be six to seven inches. The forward ends 23 of the height sensing divider legs 20 include opposed, laterally inward rearwardly converging guide surfaces 24 which laterally inwardly direct the upper portions of mature height asparagus sprouts S which are in the path T of the head 14. The forward ends 23 of each leg 20 forwardly converge to an apex 21. 
     The surfaces 24 will laterally inwardly guide the upper portion of a mature stalk S from a position schematically illustrated at 51, in the path of the divider legs 20 to a laterally inner position schematically illustrated at 53. 
     The head 14 thus functions as a height sensing unit which will permit stalks 12 which are shorter than the predetermined height to pass below the rearwardly converging guide surfaces 24 to the position illustrated at 12a in FIG. 4 while guiding the upper portions of mature stalks S to be received in the channel 22 as schematically illustrated at 51, 53 and 55 (FIG. 3). 
     Mounted atop the mounting block 18 is a double acting, solenoid actuated, spring returned pneumatic or hydraulic cylinder, generally designated 26, having a piston rod 28 slidably received in an opening 29 provided in the block 18. The piston rod 28 is coupled to a slide 30 which is vertically reciprocally slidably mounted on the ways or guide rods 16. 
     Fixed to the underside of the slide 28 is a coil spring 32 which is freely, reciprocally received in a vertical passage 33 provided in the head 14 and a vertically disposed hollow guide sleeve 35 mounted thereon. 
     A guide foot, generally designated 34, is mounted on the lower end 36 of the spring 32 and comprises a generally U shaped plate 38 having a pair of spaced apart guide legs 40. The legs 40 are spaced apart by a forwardly opening gap or channel, generally designated 42, which is generally vertically aligned with the gap 22 provided in the height sensing divider head 14. The guide legs 40 include rearwardly converging guide surfaces 44 terminating in a rearward guide channel 46. As the harvester 9 moves forwardly, in the direction represented by the arrow T, the guide surfaces 44 will laterally inwardly move the upper portions of mature asparagus spear S from the position in the path of the guide surfaces 44, illustrated at 51, to a laterally inward position illustrated at 53 and thence to the guide channel, in the position illustrated at 55. 
     It should be noted that the horizontal breadth or width W of the guide legs 40 is substantially less than the breadth or width W1 of the divider legs 20 to minimize distrubance of the immature stalks as will become more readily apparent hereinafter. It should also be noted that the forward ends 47 of guide legs 40 trail the forward ends 21 of the divider legs 20. 
     Sensing apparatus, generally designated 48, is provided for sensing the thickness or breath B of the spears S which are of the predetermined height and includes a pair of relatively stiff, spring steel sensor wires 50 mounted on head 14 and overlie the guide foot channel 46. A mature spear S being received in the guide foot channel 46 will actuate the sensor wires 50 to actuate a microswitch 52 mounted on the legs 20 of head 14. The laterally inner terminal ends 50a of the spring wires 50 are spaced apart by a gap 54 which is slightly less than the predetermined breath B of the stalk S to be cut. The spring steel sensing wires 50 are sufficiently stiff so as not to yield to a stalk or spear S which is of predetermined height but is less than predetermined breath. If the spear is of less than predetermined breadth, the sensor wires 50 will merely direct it inwardly into the gap 54 where it will merely pass through the gap 54 and thence beneath the forwardly traveling frame F without actuating microswitch 52. In this way, stalks S having less than a predetermined breadth will not sufficiently flex the sensing wires 50 to actuate microswitch 52. 
     If desired, the sensing unit 48 could likewisely comprise other sensing mechanisms, such as two front-to-rear spaced apart photocells (not shown) and two oppositely disposed photo receptors (not shown). The photocells and receptors would be spaced such that if both of the photo receptors were not receiving light, then a signal would be sent to operate the cylinder 26. Likewisely, the sensing unit 48 could be replaced by a capacitance operated switch. 
     When the microswitch 52 is actuated, the cylinder 26 will be operated to lower the piston rod 28, slide 30, the spring 32 and the guide foot 34 from the raised inoperative position, illustrated in solid lines in FIGS. 1 and 2, to the lowered position illustrated in chain lines in FIGS. 1 and 2. 
     When a stalk or spear S of sufficient width and height is sensed and received at the position illustrated at 55 in FIG. 4, the cylinder 26 will be operated to extend the piston rod 28 and move the flexible, resilient spring 32 and guide foot 34 downwardly from the inoperative position, illustrated in solid lines in FIGS. 1 and 2, to the lowered positions, illustrated in chain lines in FIGS. 1 and 2. The mature spear or stalk S is retained in the guide channel 46 between the guide legs 40 and horizontally guides the lower end of flexible spring 32 as the guide foot 34 is downwardly moved along the length of the spear. The guide legs 40 and guide channel 46 will thus sense the contour of the spear and will follow the contour of the stalk. If the stalk or spear is bent or curved, as illustrated at 56, the foot 34, the guide legs 40 and the lower end of spring 32 will be directed and guided horizontally therealong in any horizontal direction as it moves the length of the stalk. 
     The foot mounting coil spring 32 is selected of materials such that the section modulus and/or stiffness of spring 32 is less than the section modulus and/or stiffness, respectively, of a mature breadth asparagus spear S so that the lower portion 36 of the spring 32 will flex, displace or be moved horizontally. The spring 32, and not the asparagus spear S, will horizontally yield so that the spear S will not be bent and broken. This permits the foot member 34 to follow and guide on the asparagus stalk to its base at ground level G without breaking the mature height and breadth spear S. 
     Mounted on the foot member 34 is severing mechanism, generally designated 58, including a cutter blade 60 pivotally mounted on a spindle or shaft 62 fixed to the guide foot 40. As the guide foot is moved horizontally, the cutter blade 60 is concurrently moved therewith. The guide foot member trails the height sensing head 14 and receives the spears of predetermined height therefrom. 
     A double acting, pneumatically or hydraulically controlled, solenoid actuated, spring returned cylinder 64 is mounted on the foot 34 and includes a piston rod 66 pivotally connected, via pin 68, to the cutter knife 60 for swingably moving the cutter knife 60 from the non-severing position, illustrated in the solid lines in FIG. 4, to the spear severing position, illustrated in chain lines in FIG. 4, to cut the spear S. The inner surface 45 of foot 34 includes an opposing sharpened surface which cooperates with blade 60 to sever the spear S. 
     A ground actuated, pressure sensing switch 70 is provided on the underside of the foot 34 for actuating the blade actuating cylinder 64 when the foot is in the lowered, ground engaging position, illustrated in chain lines in FIGS. 1 and 2. The stroke of piston rod 28 is such that it will not be at the full length of its travel when the foot 34 engages the ground G. 
     Apparatus is provided for realigning the foot 34 with the head 14, upon return of the foot 34 to the raised inoperative position (illustrated in solid lines in FIGS. 1 and 2), and includes a plate 72, depending from the head 14, having a V-shaped downwardly opening V-shaped notch surface 74 for receiving a guide pin 76 projecting rearwardly from the foot 34. On the return path of foot 34 the cooperating guide pin 76 and guide block 72 reorients the foot 34 to the same position to receive the next asparagus spear to be harvested. 
     Spear picking or gripping apparatus, generally designated 80, is mounted on the slide 30 for gripping the severed spear and includes a pair of spear gripping jaws 82 swingably mounted provided on the block 30 via a pivot pin 84. A double acting, solenoid actuated, spring returned, pneumatically or hydraulically controlled cylinder 86 is pivotally mounted on one of the jaws 82 and includes a piston rod 88 pivotally coupled to this other jaw 82 for swinging the jaws 82 from the non-gripping positions, illustrated in solid lines in FIG. 1, to the closed spear gripping positions, illustrated in chain lines in FIG. 1, to grasp the upper portion of the severed spear S. 
     A limit switch 83 is mounted on the upper stationary mounting block 18 for sensing the presence of the slide 30 in its uppermost position. Mounted on the head 14 is a limit switch 85 which will be actuated when the slide 30 is in its fully downward position. This may occur if the ground &#34;falls away&#34; and the foot 34 does not contact the ground G when the foot is in its lowermost position. A limit switch 87 is also provided on the foot 34 for sensing the release of the cutter knife 60. 
     A frame supported airjet 89 is provided for blowing the released asparagus stalk into a bin (not shown) when the grippers 82 release the severed, lifted stalk. 
     THE CONTROL CIRCUIT 
     Referring now to FIG. 5, an electrical control circuit for controlling the apparatus illustrated in FIGS. 1-4 is schematically illustrated and includes a pair of lines 90 and 92 coupled to a source of power, such as a 12 volt D.C. battery D, mounted on the tractor. 
     Coupled across the lines 90 and 92 are a plurality of lines 93, 94, 95, 96, 97 and 98. Serially connected in line 93 is a set of normally open, breadth sensing limit switch contacts 52a which close when the breadth sensing limit switch 52 is actuated by the presence of an asparagus spear S of proper height and width sufficiently flexing the breadth sensing wires 50. Also serially coupled in line 93 is a set normally open limit switch contacts 83a which close when limit switch 83 is actuated by the slide 30 being returned to the uppermost position illustrated in solid lines in FIGS. 1 and 2. Also serially coupled in line 93 is a relay R1 which includes normally open contacts R1A (line 101) and R1B (line 94). 
     Serially connected in line 94 is the set of normally open limit switch contacts R1B, which close when relay R1 is energized, and a slide cylinder actuating relay 26a, which when energized will operate a valve directing air to the cylinder 26 causing it to downwardly move piston rod 28, the spring 32, and the guide foot 34. 
     Serially connected in line 95 is a set of normally open limit switch contacts 70a which are closed when the foot mounted switch 70 engages the ground G and a relay R2 having normally closed contacts R2A (line 101), and normally open contacts R2B (line 100) and R2C (line 96). As illustrated in FIG. 5, line 101 which includes the serially connected, normally closed contacts R2A and normally open contacts R1A, is connected in parallel circuit relation with the serially connected, normally open, switch contacts 52a and 83a. 
     Serially coupled in line 96 are the normally open switch contacts R2C and a gripper actuating solenoid 86a which when energized operates a valve directing air to the gripper actuating cylinder 86 causing the spear gripping jaw members 82 to move from the non-gripping positions illustrated in solid lines in FIG. 1, to the spear gripping positions, illustrated in chain lines in FIG. 1, to sever an asparagus spear S. A blade actuating solenoid 64a is connected in parallel circuit relation with solenoid 86a for directing air to blade actuating cylinder 64. 
     Serially connected in line 97 is a set of normally open limit switch contacts 87a which close when limit switch 87 is actuated by release of the cutter knife 60 and a relay R3 having normally open contacts R3A which are serially connected in line 98 with an airjet actuating solenoid 89a which operates a valve (not shown) for directing air to the airjet 89. 
     The two lines 99 and 100 are coupled in parallel relation with switch contacts 70a. Line 99 includes the normally open, lower slide limit switch contacts 85a which are actuated when the limit switch 85 is actuated by the slide 30 reaching its lower limit. Serially connected in line 100 are the normally closed contacts R3B and the normally open contacts R2B. 
     THE OPERATION 
     The head 14 is vertically positioned at the desired distance above the ground G such that the underside 14a of divider head 14 is spaced above the ground G a distance equal to the predetermined mature height of the asparagus spears to be harvested. As the mobile frame F moves forwardly, an asparagus stalk 12 which has grown to less than the predetermined height will merely pass below the harvester 10. If a stalk S of predetermined height is received between the terminal ends 21 of the divider legs 14, it will pass to the forwardly opening head channel 22. Those spears which are in alignment with the channel 22 will merely be received thereby whereas the upper portion of the stalk S which are in the path of divider legs 20 will be directed laterally inwardly by divider legs 20 from the position illustrated at 51 to the position illustrated at 53. As the harvester 9 moves forwardly, the converging guide surfaces 44 on the guide legs 40 will receive and further laterally inwardly guide the spears from the position illustrated at 53 to the positions illustrated at 55 and 57. If the stalk has sufficient breath, it will actuate the switch 52 causing the contacts 52a (line 93) to close, thereby energizing relay R1 (line 93) which closes the normally opened contacts R1B (line 94) and actuates the slide cylinder solenoid 26a causing the piston rod 28 to be downwardly extended. 
     As the slide 30 and spring 32 move downwardly, the asparagus spear S will continue to be received in the position illustrated at 55 and the foot 34 will guide along the outer contour of the stalk S. The guide legs 40 thus follow the contour of the asparagus stem in any horizontal direction as the foot 34 is moved downwardly. The lower end of spring 32 is universally movable in any horizontal direction in response to movement of the guide foot 34 guiding on the asparagus spear S. 
     As is evident from the drawing, the head 14 might laterally move the upper portion of a selected asparagus spear in one lateral inward direction and as the foot 34 descends and follows the contour of the spear, the foot guide 34 will laterally direct the cutter blade 60 in a laterally opposite direction. 
     When the foot 34 contacts the ground G, the limit ground sensing switch 70 will be actuated to close the contacts 70a (line 95) to actuate the relay R2 (line 95) which closes the normally opened contacts R2D (line 96) and energizes the spear gripping solenoid 86a, thus actuating the spear gripper cylinder 86 to cause the gripper members 82 to grip the upper portion of the stalk S. The cutter solenoid 64a is simultaneously energized to cause the cutter blade 60 to move from the position illustrated in solid lines in FIG. 4 to the severing position illustrated in chain lines in FIG. 4 to sever the stalk. The cutter blade will temporarily remain in this position to underly the lower end of the severed spear. 
     If the foot does not reach the ground G to actuate the limit switch 70, the slide 30 will activate the switch 85 thus closing limit switch contacts 85a (line 99) to energize relay R2 and thus cause the gripper solenoid 86a and the cutter blade solenoid 64a to be energized. 
     As is evident from the drawing, the horizontal breadth W of the foot is substantially less than the horizontal breadth W1 of the height sensing divider head 14. Thus, as the guide foot 34 moves downwardly, it will not disturb as many adjacent immature spears as would otherwise be disturbed if the height sensing head 14 was moved downwardly. 
     When relay R2 (line 95) is energized, the slide 30, the foot 34 and the severed stalk begin to travel upwardly as slide cylinder 26a &#34;loses its air&#34; as a result of normally contacts R2A (line 101) being opened when relay R2 is energized. 
     When the slide 30 is near its full up or raised position, illustrated in FIG. 1, the limit switch 87a is actuated by return of the knife blade 60, causing relay R3 (line 97) to be energized to close the contacts R3A (line 98) and thus energize relay 89a directing an upwardly blast of air to blow the raised stalk to a storage bin (not shown) as contacts R3B (line 100) are opened. The V-shaped plate 72 and guide pin 76 will cooperate to reorient the guide foot 34 which would have been disoriented as a result of following the skewed path of the asparagus spear. 
     When the slide 30 is fully returned, the slide return switch 83a (line 93) again closes and the cycle may be repeated. 
     ALTERNATE EMBODIMENT 
     Referring now more particularly to FIGS. 6 and 7, a slightly modified embodiment is illustrated wherein similar parts will be referred to by similar numerals followed by a prime designation. The harvester 9&#39; primarily distinguishes from the harvester 9 in that the guide foot 34 is replaced by a guide tube 34&#39; fixed to the lower end 36&#39; of the resilient, horizontally flexible spring 32&#39; which is aligned with the apex 106 of rearwardly converging surfaces 108&#39; provided at the rearward ends of legs 20&#39;. 
     The tube 34&#39; includes a forward wall opening 110&#39; which permits the upper end of the asparagus spear to be received therein and bear against a dependent semicylindrical rear wall flange 112&#39; which catches the asparagus stalk and aligns it with the opening O provided in the hollow flexible spring 32&#39;. A support 114 is fixed to the lower dependent rearward wall 112&#39; and mounts a cylinder 64&#39; for actuating a knife blade assembly, generally designated 60&#39;, pivotally mounted on the foot 34&#39; via a pivot pin 62&#39;. 
     In the embodiment illustrated in FIGS. 6 and 7, the severed asparagus stalk S is aligned with the opening in the coil spring 32&#39; and as the foot 34&#39; is lowered, the guide cylinder 34&#39; surrounds or encompasses the stalk S such that the stalk S passes upwardly within the opening O and is retained thereby as the spring 32&#39; is retracted. 
     It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.