Patent Publication Number: US-2004055479-A1

Title: Juice extractor having soft start motor control

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates generally to the field of juice extractors and, more specifically, to juice extractors designed to remove the juice from fruits having peels.  
       BACKGROUND OF THE INVENTION  
       [0002] One type of mass production juice extractor includes a series of juice extractor units that are ganged together. Each juice extractor unit includes upper and lower cups for supporting the fruit and squeezing the fruit therebetween. The sides of both upper and lower cups have fingers that intermesh or interdigitate together. The upper cups are mounted to a cup drive beam, which moves in a fixed up and down path by means of a cam-drive positioned at the top of the juice extractor machine. The upper cups move into the bottom cups, which remain rigidly positioned.  
       [0003] A fruit, such as an orange, is initially fed into the bottom cup by a cam-operated feeding device, which essentially tosses the fruit in the bottom cup. The upper cup then descends into the lower cup. The fruit is pressed against a sharp circular cutter positioned at the top of a strainer tube adjacent the lower cup, and against a similar cutter positioned in the upper cup. The two circular cutters cut plugs into both the top and bottom portions of the fruit as the interdigitating fingers of the two cups mesh together. At the same time, the inner portions of the fruit (i.e., the pulp and juice) are forced down into the strainer tube. After the upper cup has descended toward the lower cup, an orifice tube moves upward into the strainer tube. The orifice tube applies pressure into the internal portion of the strainer tube to separate juice and pulp within the strainer tube, collect the core material and discharge the core material out of the bottom of the orifice tube. The core material typically includes membrane, seeds, and peel plugs.  
       [0004] Each of the upper and lower cups, together with the strainer tube and orifice tube, form a single juice extractor unit. Typically, three or more juice extractor units are ganged together to increase production and are positioned in one housing or juice extractor machine. The several orifice tubes of a juice extractor machine may be ganged together, such as by an orifice drive beam that supports each of the orifice tubes and is moveable to reciprocate within the strainer tube. The juice extractor machine and method of extracting juice is further described in U.S. Pat. No. 5,970,861, U.S. Pat. No. 5,992,311, and U.S. Pat. No. 5,996,485, the disclosures of which are hereby incorporated by reference and are assigned to the assignee of the present invention.  
       [0005] Each juice extraction machine is powered by a single motor usually located near the top of the machine. The motor is coupled to a drive shaft via a gear box that extends along the top of the machine. The drive shaft runs three systems on the juice extractor. One system is responsible for the reciprocating motion of the upper cups. Along the drive shaft are two cup cams coupled to a cup drive beam connected to the several upper cups of the juice extractor units. The cup cams rotate with the drive shaft causing the up and down motion of the cup drive beam and therefore, the several upper cups.  
       [0006] The rotation of the drive shaft also runs a system responsible for the reciprocating motion of the orifice tube into the strainer tube as previously described. The drive shaft further has two orifice cams coupled to pull rods extending from the drive shaft to the orifice tubes. The pull rods are in turn coupled to an orifice drive beam connected to the several orifice tubes of the juice extractor units. The orifice cams rotate with the drive shaft causing the up and down motion of the pull rods, orifice drive beam and consequently, the several orifice tubes.  
       [0007] Lastly, the rotation of the drive shaft runs the system responsible for feeding the fruits into the bottom cups of the extractor units. The drive shaft has a cogwheel coupled to a chain that is in turn coupled to another cogwheel of the feed system located adjacent the bottom cup. The feeder system is a cam-driven rotating system of fingers that pick the fruit up one at a time from chutes adjacent a gravity fed conveyor system and tosses it into the bottom cup. This system is appropriately synchronized with the motion of the upper cups so that the fruit is placed in the bottom cup prior to or as the upper cup starts its descent toward the bottom cup.  
       [0008] The drive mechanism of the juice extractor machine just described has several areas which present challenges. For example, in a typical start up procedure, a juice extractor might go from rest to approximately 100 rpm over a very short period of time. These excessive forces and accelerations during start up can lead to cam and cam follower separation such as between the cup cams and the cam followers on the cup drive beam. There is significantly less inertia associated with the drive shaft and connected cams than with the cam followers and cup drive beam. As a result, when the machine is started, the cams quickly accelerate but the cam followers cannot move as quickly, thus separation occurs. Contact between the cup cams and cam followers is effectuated by a series of springs that generate and maintain an upward force on the cup drive beam. Once the cup cams and cam followers become separated, the restoring force of the springs jerks the cup drive beam upward until the cam followers make contact the cams. This generates undesirable pounding or knocking heard during start up.  
       [0009] One way that operators of juice extractors minimize the pounding and knocking during start up is to increase the restoring force generated by the springs. The accelerations and resulting forces during start up are then not large enough to overcome the force maintaining contact between the cams and cam followers. Juice extractors use a series of mechanical springs or a mix of mechanical springs and air springs to maintain contact between the cams and the cam followers on the cup drive beam. When air springs are utilized, an operator prevents knocking by increasing the pressure in the air springs. It is found that during steady state operation, an air pressure of 60 psi is needed to keep the cams and cam followers in constant contact with each other. At this pressure, however, knocking occurs during start up. In order to prevent the machine from knocking during start up, a pressure of approximately 80 psi is required in the air springs. It is not unusual for these machines to be run 24 hours a day, 7 days a week. Consequently, the increased pressure can play a significant role in wear, fatigue, breakage of drive train components, and increased energy consumption.  
       [0010] Another problem that is frequently encountered during start up is misfeeding of fruit into the lower cup due to changes in acceleration and timing. Since the feeding system is driven by the drive shaft, the feeding system also experiences large, abrupt accelerations during start up. Fruit often cannot be fed fast enough during this period leading to occasions where there is no fruit in the bottom cup during a machine cycle. There are also occasions where fruit is picked up by the rotating fingers but, due to the large accelerations, the machine often overshoots the bottom cup, again leading to occasions where there is no fruit in the bottom cup during a machine cycle.  
       [0011] There are also other types of mass production and point-of-purchase juice extractors that operate with similar or different extraction techniques but can have similar types of problems. For example, some machines use cups that are oriented horizontally with respect to each other and other machines slice the fruit in half and then use a reaming technique to extract the juice.  
       [0012] In view of the above problems and drawbacks with previous juice extractor start up procedures, it would be desirable to provide a juice extractor with a control system that prevents problems associated, for example, with separation of cams and cam followers and misfeeding of fruit.  
       SUMMARY OF THE INVENTION  
       [0013] The present invention is advantageous because it provides a juice extractor that may achieve steady state operation without the start up problems associated with traditional juice extractors. The invention utilizes a soft start controller coupled to the juice extractor motor to gradually bring the extractor up to its normal operating condition. In this way, the large accelerations and resulting forces that lead to the undesirable effects of knocking and pounding as well as fruit misfeeding are avoided. Previously, a motor starting from rest usually reached its operating voltage in less than approximately one half of a second. With a soft start controller, this time period is expanded to occur over a specific and, preferably, controllable period of time. To reduce the unique problems associated with juice extractors, the ramp up time period should be greater than two seconds. It is preferable that the ramp up time period be at least five seconds. The preferred embodiment uses a ramp up time period of approximately ten seconds.  
       [0014] Gradually increasing the motor voltage from zero to its normal operational voltage over a time period of at least two seconds has several advantages. One advantage in the preferred extractor is that the spring generated restoring force that keeps the cam and cam followers in contact with one another may be significantly reduced. For instance, in the case of a juice extractor having air springs, a soft start controller permits a pressurization of 60 psi instead of the 80 psi required to prevent knocking and pounding. This reduction in air pressure reduces the stresses and wear on the cams, shafts, bearings, gears, belts, etc. This can in turn lead to extended drive train life and reduced operation costs and machine down time.  
       [0015] Another advantage of the present invention is that a controlled start up prevents misfeeding of fruit. Because the accelerations are significantly reduced when start up is spread over an extended time period, pieces of fruit in the feeder system have time to be properly positioned so as to be properly and accurately fed into the extractor.  
       [0016] Still another advantage of the present invention is in trouble shooting technical problems in juice extractors. For instance, it is not uncommon that an extractor becomes clogged with foreign material such as twigs, aluminum foil, and any other type of foreign material. With existing extractors, a technician removes the foreign object(s) from the extractor then pushes the start and stop buttons in a quick series of motions to prevent too much momentum in the case that foreign material is still stuck in the machine. If the foreign objects are still stuck in the machine, allowing the machine to gain too much momentum could cause a catastrophic failure. A soft start controller causes the machine to start slowly. In this way, a technician can more readily check for additional clogs or other technical problems before any serious damage occurs to the machine. Additionally, having a soft start controller allows a technician sufficient time to determine other problems, such as misalignments and timing issues, that permit more accurate machine diagnosis and proper machine adjustments.  
       [0017] These and other objects, advantages, and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description taken in conjunction with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018]FIG. 1 is a perspective view of an automated juice extractor machine incorporating the present invention.  
     [0019]FIG. 2 is a cross-sectional view of a portion of a juice extractor unit showing upper and lower cups, strainer tube, and orifice tube.  
     [0020]FIG. 3 is a schematic of a juice extractor machine illustrating the components of the drive train system including the cams, cam followers, drive beams, air and mechanical springs, and the soft start controller of the present invention.  
     [0021]FIG. 4 is a graph demonstrating the present invention by comparing the motor&#39;s ramp up to its normal operational voltage when the motor has no soft start controller and when the motor includes a soft start controller. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0022] With reference to FIG. 1, a juice extractor machine  10  includes five extractor units  12 , each having an upper cup  14  and lower cup  16 , ganged together in a common frame  18  and receiving fruit along chutes  20 . It will be understood that mass production extractors of other configurations as well as point-of-purchase extractors may also incorporate the principles of this invention with its attendant advantages.  
     [0023] Before a fruit is placed on the individual extractor unit  12 , it is unloaded either manually or otherwise into a hopper from which it is conveyed through a washing process, typically a series of brushes where the fruit is gently scrubbed to remove field oils, soil, mold and dust. Fruit is then typically discharged onto a roller grader where workers or automatic sorters select the fruit to remove broken pieces, leaves and other undesirable materials from the flow of fruit supply. The fruit is then typically conveyed to a sizing roller to separate the fruit into sizes equivalent to the size range of the upper and lower cups of the individual extractor units in order to ensure the maximum yield and quality. The fruit is then conveyed to the proper extractor machine  10 , such as that shown in FIG. 1 where the individual fruits roll down chutes  20  so that each piece of fruit will nest in the lower cup of the individual extractor units  12 .  
     [0024] With reference now to FIGS. 2 and 3, there is seen an individual extractor unit  12  with the upper and lower cups  14 ,  16  respectively. The upper cup  14  is supported on a cup drive beam  22  which moves in a fixed up and down direction by means of a cam-operated drive contained in the top portion of the extractor machine  10 . The lower cup  16  is rigidly positioned and secured to the frame  18 .  
     [0025] As illustrated, the upper and lower cups  14 ,  16  are formed as interdigitated cups having fingers  21  that intermesh together as the upper cup is moved into the lower cup. The cam-operated drive system forces the upper cup  14  into the lower cup  16  and presses the fruit  28  against a circular cutter tube  24  located at the base of the lower cup  16  and on top of an elongated prefinishing or strainer tube  26 . The cutter  24  cuts a plug in the bottom of the fruit  28  to allow the internal portions of the fruit access to the interior of the strainer tube  26 . An upper cutter  30  is associated with the upper cup  14  and cuts a plug in the top of the fruit to permit separation of the peel from the internal portions of the fruit  28  as the fruit is squeezed between the upper and lower cups  14 ,  16 . The inner portion of the fruit  28  is forced down into the strainer tube  26 , and an orifice tube  32  received on the interior of the strainer tube  26  moves upwardly to force the inner portions of the fruit  28  that are appropriately sized through the strainer tube and into a juice manifold or reservoir  34 , where the juice and pulp  36  is collected. The orifice tube  32  is supported on an orifice drive beam  58  vertically moveable on bushings by means of pull rods  59  coupled to the cam mechanism located in the upper portion of the machine  10 , as mentioned before.  
     [0026] With reference now to FIG. 3, there is seen a juice extractor machine  10  and its associated cam-driven power train  38 . The juice extractor machine  10  is powered by a motor  40  located near the top of the machine. A gear box  42  is coupled to the motor  40 , by means of a belt and pulley system  43 , so as to control the rotation of a primary drive shaft  44  that runs along the top of the juice extractor machine  10 . Drive shaft  44  runs three systems on the juice extractor machine  10 . One system driven by drive shaft  44  is responsible for the reciprocating motion of the upper cups  14 , as shown by reference numeral  45 . Two cup cams  46  are securely fixed to drive shaft  44  so as to rotate with drive shaft  44 . Cup cams  46  are appropriately shaped so as to provide a full up and down cycle with each rotation of the cam. The cup cams  46  are in contact with two cam followers  48  located within cup drive beam  22  which are connected to upper cups  14  by connection rods  49 . The cup drive beam  22  moves in a vertical direction  45  along drive beam guides  50  as cams  46  rotate. To keep cup cams  46  and cam followers  48  in constant contact with one another, a series of springs  52 ,  54  are used to generate and maintain an upward force on the cup drive beam  22 . In the preferred embodiment, there are four mechanical springs  52  and four air springs  54 , only two are shown for purposes of illustration. The air springs  54  are primarily responsible for maintaining contact between the cup cams  46  and cam followers  48 . The mechanical springs  52  provide a minimal level of restoring force and is primarily relied upon for backup and safety concerns. However, those of ordinary skill in the art will recognize that any combination of air springs and mechanical springs may be used to maintain contact between the cams and cam followers, including using all mechanical springs.  
     [0027] Another system driven by drive shaft  44  is responsible for the reciprocating motion of the orifice tube  32  inside the strainer tube  26 , as shown by reference numeral  57 . Two orifice cams  56  are securely fixed to drive shaft  44  so as to rotate with drive shaft  44 . Orifice cams  56  are appropriately shaped so as to provide a full up and down cycle with each rotation of the cam. Pull rods  59  couple the orifice cams  56  to an orifice drive beam  58  that is connected to the several orifice tubes  32 . The orifice drive beam  58  moves in a vertical direction  57  along drive beam guides  50  as cams  56  rotate. The orifice cams  56  are also configured such that the upward motion of the orifice tube  32  is slightly behind the downward motion of the upper cups  14 .  
     [0028] The drive shaft  44  also runs the system responsible for feeding the fruit to the lower cups  14  of each juice extractor unit  12 . A cogwheel  60  is securely fixed to drive shaft  44  so as to rotate with drive shaft  44 . A chain  61  couples the primary drive shaft  44  to a secondary drive shaft  62  that rotates a fruit cam  63  having three fingers  64  extending therefrom. As the fruit cam  63  rotates, the fingers  64  picks up fruits  28  one at a time at the bottom of chutes  20 . The fruit  28  runs along a fruit guide rail  66  that ends just prior to lower cups  16 . As the fruit cam  63  continues to rotate, the fruit  28  is essentially tossed into the lower cup  16 . The feeder system is configured such that the fruit is placed in the lower cup prior to or as the upper cup starts its descent toward the lower cup.  
     [0029] To overcome the problems associated with previous juice extractor start up procedures, a soft start motor controller  68 , such as the Allen-Bradley SMC-3™ controller, is coupled to the juice extractor motor  40 . Now referring to FIG. 4, it is seen by curve  70  that motors without a soft start controller have a natural ramp up curve at start up. Starting from rest, a motor without a soft start controller will typically reach its normal operating voltage in less than approximately one half of a second. As shown by curve  72 , to receive any mechanical benefits, the ramp up time period should not be less than two seconds and is preferably between five and fifteen seconds. In the preferred embodiment, the ramp up time period is approximately ten seconds, as shown in curve  74 .  
     [0030] In operation, a juice extractor  10  with a soft start controller  68  significantly reduces the accelerations, forces, and resulting stresses experienced by the drive train system  38  during start up and steady state. Because motor  40  of juice extractor  10  is gradually brought up to its normal operating voltage, the acceleration on drive shaft  44  and cup cams  46  are not so high that cams  46  and cam followers  48  separate. This has the advantageous result that air springs  54  do not have to be over pressurized to prevent knocking but may be set at its lower steady state value, e.g. 60 psi instead of 80 psi. Additionally, a soft start controller  68  reduces misfeeds during start up. Due to the high accelerations of non-controlled start up, fruit feeding from chute  20  may not keep up with the rotation of fruit cam  63  or fruit moving along guide  66  by fingers  64  might overshoot the lower cup  16 . With a controlled start up that gradually brings the extractor up to speed, the fruit fed from chute  20  may keep up with fruit cam  63  and fingers  64  do not propel fruit  28  beyond the lower cup  16 .  
     [0031] While the present invention has been illustrated by a description of a preferred embodiment and while this embodiment has been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims.