Patent Publication Number: US-2022217911-A1

Title: Threshing Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the United States national phase of International Application No. PCT/JP2020/025012 filed Jun. 25, 2020, and claims priority to Japanese Patent Application Nos. 2019-120475 filed Jun. 27, 2019, 2019-211314 filed Nov. 22, 2019, and 2020-107679 filed Jun. 23, 2020, the disclosures of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a threshing apparatus including a threshing unit that has a receiving net and threshes crops, and a sorting unit that is provided below the threshing unit and sorts grain from a threshed product that has leaked from the receiving net. 
     Description of Related Art 
     Conventionally, a threshing apparatus for threshing crops from harvested grain culms has been used. One such threshing apparatus is described in, for example, Japanese Patent Application Laid-Open No. 2019-76061. 
     The threshing apparatus described in Japanese Patent Application Laid-Open No. 2019-76061 includes a threshing drum for threshing reaped grain culms, and is configured such that the threshed product falls from the receiving net onto a swinging sorting shelf below and is subjected to sifting processing. Also, this threshing apparatus is provided with a layer thickness sensor that detects the layer thickness of the processed product flowing on the swinging sorting shelf, and the opening degree of an opening/closing sieve is controlled in accordance with the detection result of the layer thickness sensor. Specifically, when the layer thickness of the processed product on the swinging sorting shelf increases, the opening/closing sieve is controlled in the opening direction, and when the layer thickness of the processed product on the swing sorting shelf decreases, the opening/closing sieve is controlled in the closing direction.
     Patent Document 1: Japanese Patent Application Laid-Open No. 2019-76061   

     SUMMARY OF THE INVENTION 
     The threshing apparatus described in Japanese Patent Application Laid-Open No. 2019-76061 is provided with a first phase spiral that transfers a first product (clean grains) collected below the swinging sorting shelf and a second phase spiral that transfers a second product (tailings). If the amount of the threshed product from the threshing drum increases, the opening/closing sieve is controlled in the opening direction, which leads to a phenomenon in which cut straw included in the processed product leaking from the opening/closing sieve increases. If a large amount of cut straw leaks from the opening/closing sieve, it is envisioned that the amount of the second product will also increase, and due to the amount of the second product transferred to the swinging sorting shelf increasing, the layer thickness of the swinging shorting shelf will also increase, which results in incurring a decrease in the sorting performance. 
     In view of this, a threshing apparatus is required which can suppress a decrease in sorting performance even if the amount of processed product increases. 
     A characteristic configuration of the threshing apparatus according to the present invention is a threshing apparatus including a threshing unit that has a receiving net and is configured to thresh a crop, and a sorting unit that is provided below the threshing unit and is configured to sort grain from a threshed product that has leaked from the receiving net, in which the sorting unit includes: a sorter configured to sort the grain as a sorted product from the threshed product; a first product collector configured to collect the sorted product as a first product; a second product collector configured to collect, as a second product, the threshed product that was not sorted as the sorted product; a second product returner configured to return the second product collected by the second product collector to the sorter; and a return amount detector configured to detect a return amount of the second product to be returned to the sorter. 
     With such a characteristic configuration, for example, the amount of the threshed product supplied from the threshing unit to the sorting unit can be adjusted, or the sorting condition (sorting degree) by the sorting unit can be adjusted in accordance with the return amount of the second product. Accordingly, it is possible to suppress a decrease in the sorting ability of the sorting unit in the threshing apparatus accompanying an increase in the amount of the second product. 
     It is also preferable that the sorter has a sorting amount of the threshed product to be sorted as the sorted product which sorting amount is changed in accordance with the return amount. 
     With such a configuration, the sorting ability can be changed in accordance with the return amount. Accordingly, it is possible to suppress a decrease in the sorting ability of the sorting unit accompanying an increase in the return amount. 
     It is also preferable that the sorting amount of the sorter is increased in accordance with an increase in the return amount. 
     With such a configuration, the collection amount of the first product can be increased when the return amount increases. Accordingly, it is possible to suppress an increase in the amount of the threshed product and the second product waiting to be sorted in the sorting unit, and to prevent retention. 
     It is also preferable that the sorter is provided with a chaff sieve including a plurality of chaff lips that are arranged side by side in a transport direction in which the threshed product is transported, the plurality of chaff lips each having a changeable opening degree, and the opening degree of each of the chaff lips is increased in accordance with an increase in the return amount. 
     With such a configuration, if the return amount is large, the flow speed of the threshed product and the second product on the chaff sieve can be increased. Accordingly, it is possible to suppress an increase in the amount of the threshed product and the second product waiting to be sorted on the chaff sieve, and to prevent retention. 
     It is also preferable that the sorting unit is provided with a winnowing fan configured to generate sorting air along the transport direction in an amount that is increased in accordance with an increase in the return amount. 
     With such a configuration, if the return amount is large, the sorting air can be increased to make it easier to blow away the cut straw and the like. Accordingly, it is possible to suppress an increase in the amount of the threshed product and the secondary product waiting to be sorted on the chaff sieve, and to prevent retention. 
     It is also preferable that the sorting unit is provided with a threshed product detector configured to detect an amount of the threshed product that leaks from the receiving net, and the sorting amount of the sorter is changed in accordance with the amount of the threshed product. 
     With such a configuration, the sorting ability can be changed if the amount of the threshed product that has leaked from the receiving net is large. Accordingly, it is possible to suppress a decrease in the sorting ability of the sorting unit accompanying an increase in the amount of the threshed product. 
     It is also preferable that the threshing unit includes a threshing drum that has a cylindrical drum body with an outer peripheral portion to which a plurality of threshing teeth are attached, and a threshing drum shaft that supports the drum body, and the drum body conveys the crop in an amount that is reduced in accordance with an increase in the return amount. 
     With such a configuration, if the return amount is large, the retention time of the crop in the threshing drum can be lengthened, and the amount of the threshed product leaking from the threshing drum can be reduced. Accordingly, it is possible to suppress an increase in the amount of the threshed product and the second product waiting to be sorted in the sorting unit, and to prevent retention. 
     It is also preferable that the threshing unit and the sorting unit are provided in a travel device body, and the travel device body has a traveling speed that is reduced in accordance with an increase in the return amount. 
     With such a configuration, if the return amount is large, the traveling speed of the travel device body can be reduced and the amount of crops supplied to the threshing unit can be reduced. Accordingly, it is possible to suppress an increase in the amount of the threshed product and the second product waiting to be sorted in the sorting unit, and to prevent retention. 
     It is also preferable that the return amount detector is configured to measure the return amount by coming into contact with the second product discharged by the second product returner. 
     With such a configuration, the return amount detector can accurately measure the return amount of the second product by coming into contact with the discharged second product. 
     Also, it is suitable that the return amount detector includes (i) a swing arm that is located on a discharge extension of the second product discharged by the second product returner and that swings in response to the discharged second product coming into contact therewith, and (ii) a measurement portion configured to measure the return amount based on a swing angle of the swing arm. 
     With such a configuration, the swing arm swings due to the second product coming into contact therewith, but the swing angle changes in accordance with the amount of the second product to be discharged. Therefore, the measuring unit can obtain the return amount from the swing angle of the swing arm. 
     It is also preferable that the second product returner includes a guide configured to guide the discharged second product toward the swing arm. 
     With such a configuration, the discharged second product can be guided by the guide to be accurately brought into contact with the swing arm. 
     It is also preferable that the guide has a planar shape extending along a swing path of the swing arm, and is provided laterally to the swing arm and adjacent to the swing arm in a swing axis direction of the swing arm, and the guide is configured such that when the swing arm swings in response to contact with the second product, a separation distance between a side portion of the swing arm and the guide increases in accordance with an increase in an swing amount of the swing. 
     In order for the return amount detector to accurately detect the return amount of the second product, it is preferable that the swing arm swings accurately in accordance with the return amount of the second product. If the separation distance between the swing arm and the guide changes accompanying the swinging of the swing arm, the detection accuracy of the return amount detector is affected. With this configuration, the guide is provided laterally to the swing arm in a state of being adjacent to the swing arm in the swing axis direction of the swing arm. Even if the return amount of the second product is small, the second product scatters along the planar shape of the guide, and therefore the swing arm that is not swinging and the second product can easily come into contact with each other, and the swinging of the swing arm is prompted. For this reason, the detection sensitivity of the return amount detector improves. Also, in accordance with an increase in the swing amount of the swing arm, the separation distance between the side portion of the swing arm and the guide is increased. For this reason, if the return amount of the second product is large, the second product slips through the gap between the side portion of the swing arm and the guide, whereby excessive swinging of the swing arm is suppressed. Due to this, even if the return amount of the second product is large, it is more difficult for the swing arm to fully swing to the maximum of the swing range, and thus the magnitude of the return amount of the second product can be measured in as wide a range as possible. That is, even if the return amount of the second product is small, the return amount detector can measure the return amount with good sensitivity and can measure the magnitude of the return amount in a wide range. 
     It is also preferable that the guide has a planar shape extending along a swing path of the swing arm, and is provided laterally to the swing arm and adjacent to the swing arm in a swing axis direction of the swing arm, and the guide is configured such that when the swing arm swings in response to contact with the second product, a separation distance between a side portion of the swing arm and the guide is unchanged, regardless of a magnitude of an amount of the swing. 
     If a configuration is used in which the separation distance between the swing arm and the guide becomes smaller the more the swing arm swings, it is thought that the swing arm will suddenly fully swing to the maximum of the range at the time when the return amount of the second product exceeds a predetermined amount. In this case, it is conceivable that the detection value of the return amount detector remains stuck at the maximum value, and if the return amount of the second product is large, the return amount detector will not be able to accurately measure the return amount. In this configuration, the separation distance between the side portion of the swing arm and the guide is the same regardless of the magnitude of the swinging amount, and therefore it is less likely that the swing arm will swing out of range compared with the configuration in which the separation distance between the swing arm and the guide is smaller the more the swing arm swings. Accordingly, the return amount detector can measure the magnitude of the return amount in a wide range. 
     It is also preferable that the return amount detector is supported by a side wall of the threshing unit. 
     With such a configuration, the return amount detector is stably supported by the side wall having high rigidity, and therefore a correct measurement operation can be performed over a long period of time. 
     It is also preferable that the return amount detector is supported on an outer side portion of the side wall. 
     With such a configuration, since the threshed product is not present on the outer side portion of the side wall, there is no disadvantage such as the threshed product coming into contact with the support portion of the return amount detector and being damaged. 
     It is also preferable that the return amount detector is supported on an inner side portion of the side wall. 
     With such a configuration, the return amount detector is supported by the side wall at a position as close as possible to the detection target location of the second product, and therefore the return amount detector can be made compact. 
     It is also preferable that the threshing apparatus further includes a cover body for covering an upper portion of the return amount detector. 
     With such a configuration, even if the threshed product is present on the inner side of the side wall, it is possible to prevent the threshed product from falling on the return amount detector using the cover body, and it is possible to avoid the occurrence of a failure in the return amount detector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a lateral view of a combine including a threshing apparatus. 
         FIG. 2  is a plan view of the combine including the threshing apparatus. 
         FIG. 3  is a longitudinal cross sectional lateral view of the threshing apparatus. 
         FIG. 4  is a layout diagram of a return amount detector and a second product discharge port. 
         FIG. 5  is a layout diagram of the return amount detector and the second product discharge port. 
         FIG. 6  is a layout diagram of the return amount detector and the second product discharge port. 
         FIG. 7  is a lateral view of the return amount detector. 
         FIG. 8  is an example of a return amount detected by the return amount detector. 
         FIG. 9  is a diagram showing an example of changing an opening degree of a chaff lip. 
         FIG. 10  is a diagram showing an arrangement relationship between a swing arm and a guide. 
         FIG. 11  is a diagram showing an arrangement relationship between the swing arm and the guide. 
         FIG. 12  is a graph showing the return amount of the second product and the swing amount of the swing arm for each shape of the guide. 
         FIG. 13  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 14  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 15  is a perspective view of the return amount detector in a small return amount state in another embodiment. 
         FIG. 16  is a perspective view of the return amount detector in a large return amount state in another embodiment. 
         FIG. 17  is a longitudinal cross-sectional lateral view of a threshing apparatus of another embodiment. 
         FIG. 18  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 19  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 20  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 21  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 22  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
         FIG. 23  is a layout diagram of a return amount detector and a second product discharge port in another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The threshing apparatus according to the present invention is configured to be able to prevent deterioration of sorting performance even if the amount of a processed product increases. Hereinafter, a threshing apparatus  1  of the present embodiment will be described. 
       FIG. 1  is a lateral view of a combine  20  including the threshing apparatus  1  of the present embodiment.  FIG. 2  is a plan view of the combine  20  including the threshing apparatus  1  of the present embodiment. Also,  FIG. 3  is a cross-sectional view of the threshing apparatus  1 . Note that hereinafter, the combine  20  of the present embodiment will be described taking a so-called ordinary combine as an example. Of course, the combine  20  may also be a head-feeding combine. 
     Here, in order to facilitate comprehension, in the present embodiment, unless otherwise specified, “front” (the direction of arrow F shown in  FIGS. 1 and 2 ) means frontward in the body front-rear direction (traveling direction), and “rear” (the direction of arrow B shown in  FIGS. 1 and 2 ) means rearward in the body front-rear direction (traveling direction). Also, “up” (the direction of arrow U shown in  FIG. 1 ) and “down” (the direction of arrow D shown in  FIG. 1 ) are in a positional relationship in the body vertical direction (vertical direction), and indicate relationships in the above-ground height. Furthermore, the left-right direction or the lateral direction is the body crossing direction (body width direction) orthogonal to the body front-rear direction, that is, “left” (the direction of arrow L shown in  FIG. 2 ) and “right” (the direction of arrow R shown in  FIG. 2 ) mean the left and right directions of the body, respectively. 
     As shown in  FIGS. 1 and 2 , the combine  20  includes a body frame  2  and a crawler traveling apparatus  3 . A reaping portion  4  for reaping planted grain culms is provided in front of the travel device body  17 . The reaping portion  4  is provided with a raking reel  5  for raking in the planted grain culms, a reaping blade  6  for cutting the planted grain culms, and an auger  7  for raking in the reaped grain culms. 
     A driving cabin  8  is provided on the right side of the front portion of the travel device body  17 . The driving cabin  8  is provided with a driving portion  9  in which a driver rides, and a cabin  10  covering the driving portion  9 . An engine room ER is provided below the driving portion  9 . In addition to an engine E, the engine room ER houses an exhaust purification apparatus, a cooling fan, a radiator, and the like. The power of the engine E is transmitted to the crawler traveling apparatus  3 , a threshing drum  22  in the threshing apparatus  1 , a swing drive mechanism  43 , and the like using a power transmission structure (not shown). The threshing drum  22  and the swing drive mechanism  43  will be described later. 
     The threshing apparatus  1  for threshing the reaped grain culms (corresponding to “crops”) is provided rearward of the reaping portion  4 . A feeder  11  for transporting the reaped grain culms toward the threshing apparatus  1  is provided spanning between the reaping portion  4  and the threshing apparatus  1 . A grain tank  12  for storing the threshed grain is provided laterally to the threshing apparatus  1 . The grain tank  12  is configured to be able to swing about an axis extending in the vertical direction, and the grain tank  12  is configured to be able to swing open and closed between a working position and a maintenance position. A waste straw shredding apparatus  13  including a rotary blade  13   a  is provided at the rear of the threshing apparatus  1 . 
     The combine  20  is provided with a grain discharge apparatus  14  for discharging the grain in the grain tank  12  to the outside. A vertical transporter  15  for transporting the grain in the grain tank  12  upward, a horizontal transporter  16  for transporting the grain from the vertical transporter  15  toward the outside of the body are provided in the grain discharge apparatus  14 . The grain discharge apparatus  14  is configured to be able to rotate about the axis of the vertical transporter  15 . The lower end portion of the vertical transporter  15  is in communication with and connected to the bottom portion of the grain tank  12 . The end portion of the horizontal transporter  16  on the vertical transporter  15  side is in communication with and connected to the upper end portion of the vertical transporter  15  and is supported so as to be able to swing up and down. 
     In the present embodiment, the threshing apparatus  1  is provided on the travel device body  17 . The threshing apparatus  1  includes a threshing unit  41  for threshing crops and a sorting unit  42 . Accordingly, the threshing unit  41  and the sorting unit  42  are provided in the travel device body  17 . The threshing unit  41  is arranged at the upper portion of the threshing apparatus  1 , and a receiving net  23  is provided at the lower portion of the threshing unit  41 . The sorting unit  42  (excluding the “return amount detector  71 ” described later in this embodiment) is arranged below the threshing unit  41  and is configured to sort grain from a processed product (corresponds to “threshed product”) that has leaked from the receiving net  23 . The sorting unit  42  includes a swinging sorting apparatus  24  (an example of a “sorter”), a first product collector  26 , a second product collector  27 , a second product returner  32 , and a return amount detector  71 . 
     The threshing unit  41  accommodates the threshing drum  22  in a threshing chamber  21 , and includes the receiving net  23  at the lower portion of the threshing drum  22 . The threshing chamber  21  is formed as a space surrounded by a front wall  51  on the front side, a rear wall  52  on the rear side, left and right side walls  50  (see  FIG. 4 ), and a top plate  53  covering the upper portion. A supply port  54   a  through which a harvested product (corresponding to “crops”) is supplied is formed in a portion of the threshing chamber  21  below the front wall  51 , and a guide bottom plate  59  is arranged at the bottom portion of the supply port  54   a . Also, a debris discharge port  54   b  is formed in a portion of the threshing chamber  21  below the rear wall  52 . 
     The threshing drum  22  has a drum body  60  and a rotation support shaft  55  (an example of a “threshing drum shaft”). As shown in  FIG. 3 , the drum body  60  is formed in one piece by a raking portion  57  at the front end portion and a threshing processing portion  58  at a position rearward of the raking portion  57 . The raking portion  57  includes a double-helical spiral blade  57   b  on the outer circumferential portion of a tapered base portion  57   a  whose diameter decreases toward the front end of the threshing drum  22 . The threshing processing portion  58  has a plurality of rod-shaped threshing tooth support members  58   a  and a plurality of threshing teeth  58   b . The plurality of rod-shaped threshing tooth support members  58   a  are provided spaced apart from each other at a predetermined interval in the peripheral direction of the cylindrical drum body  60 . Each of the plurality of threshing teeth  58   b  protrudes from the outer peripheral portion of each of the plurality of threshing tooth support members  58   a , and is attached spaced apart from other threshing teeth  58   b  at a predetermined interval along the rotation axis X in a front-rear-facing orientation. 
     The rotation support shaft  55  extends along the rotation axis X and penetrates through the front wall  51  and the rear wall  52  in the front-rear direction. The drum body  60  and the rotation support shaft  55  rotate integrally about the rotation axis X. That is, the front end of the rotation support shaft  55  is rotatably supported by the front wall  51  via a bearing, and similarly, the rear end of the rotation support shaft  55  is rotatably supported by the rear wall  52  via a bearing. In this threshing unit  41 , the driving rotational force is transmitted from a rotation drive mechanism  56  to the front end portion of the rotation support shaft  55 . 
     A plurality of plate-shaped debris conveying valves  53   a  are provided on the inner surface (lower surface) of the top plate  53  at a predetermined interval along the front-rear direction. The plurality of debris conveying valves  53   a  are provided in an orientation of being inclined with respect to the rotational axis X in a plan view so as to cause a force for moving rearward to act on the processed product rotating together with the threshing drum  22  in the threshing chamber  21 . 
     The receiving net  23  is formed in a circular arc shape so as to surround a region extending below the threshing drum  22  and both lateral sides of the threshing drum  22 . Gaps are formed in the receiving net  23  due to a combination of a plurality of longitudinal frames arranged at a predetermined interval along the front-rear direction and widthwise frames in a front-rear-facing orientation supported on each longitudinal frame (see  FIG. 4 ). The processed product can leak from the gaps formed in the receiving net  23 . 
     In the threshing apparatus  1  of the present embodiment, the reaped grain culms supplied to the threshing chamber  21  are referred to as a harvested product, and the harvested product threshed in the threshing chamber  21  is referred to as a processed product (corresponding to “threshed product”). The processed product includes grain, cut straw, and the like. The first product is the processed product that mainly includes grain, and the second product is the processed product that includes grain that has been insufficiently processed into single grains, cut straw, and the like. 
     In the threshing unit  41 , the harvested product from the feeder  11  is supplied to the threshing chamber  21  via the supply port  54   a . The supplied harvested product is raked toward the rear of the threshing drum  22  along the guide bottom plate  59  by the spiral blade  57   b  of the raking portion  57 , and is supplied to the threshing processing portion  58 . In the threshing processing portion  58 , threshing is performed as a result of the harvested product being subjected to threshing processing by the threshing teeth  58   b  and the receiving net  23  accompanying the rotation of the threshing drum  22 . 
     When the threshing is performed in this manner, the processed product rotates together with the threshing drum  22 , whereby the processed product comes into contact with the debris conveying valves  53   a  and is subjected to threshing processing while being transported to the rear portion of the threshing chamber  21 . The grain obtained through the threshing processing, short pieces of cut straw, and the like leak from the receiving net  23  and fall into the sorting unit  42 . In contrast to this, the processed product (grain culms, long pieces of cut straw, etc.) that cannot leak from the receiving net  23  is discharged to the outside of the threshing chamber  21  from the debris discharge port  54   b.    
     As shown in  FIG. 3 , the sorting unit  42  is provided with a swinging sorting apparatus  24  and a winnowing fan  25 . Sorting air is supplied from the winnowing fan  25  to the swinging sorting apparatus  24 . The swinging sorting apparatus  24  performs a swinging operation in an environment in which sorting air is supplied, and sorts grain (first product) as the sorted product among the threshed products. The sorted product is grain sorted by the swinging sorting apparatus  24 . Also, the first product collector  26  and the second product collector  27  are arranged below the swinging sorting apparatus  24 . 
     The winnowing fan  25  is provided in the sorting unit  42  and generates sorting air along the transport direction of the processed product. The winnowing fan  25  is provided with a winnowing fan main body having a plurality of rotating blades  25   b , and the winnowing fan main body is housed inside a fan case  25   a . An upper discharge port  25   c  for sending the sorting air along the upper surface of an upper grain pan  61  is formed on the upper portion of the fan case  25   a . A rear discharge port  25   d  for sending the sorting air rearward is formed at the rear portion of the fan case  25   a.    
     The first product collector  26  collects the processed product selected as the sorted product among the threshed products as the first product. The processed product is guided to the first product collector  26  by the first product guide  62 . That is, the first product collector  26  is formed as a first product screw that transports the first product (grain of the first product) guided by the first product guide  62  in the lateral direction. The first product collected by the first product collector  26  is transported (lifted) upward toward the grain tank  12  by a first product collection transporter  29 . The first product transported by the first product collection transporter  29  is transported to the right by a storage screw  30  and supplied to the grain tank  12 . The first product collection transporter  29  is constituted by a bucket-type conveyor. 
     The second product collector  27  collects the processed product that has not been sorted as the sorted product among the threshed products as the second product. The processed product that has not been sorted as the sorted product corresponds to grain, culms, long pieces of cut straw, and the like that have not been sorted by the swinging sorting apparatus  24 , and is referred to as the second product. Such a second product is guided to the second product collector  27  by a second product guide  63 . That is, the second product collector  27  is formed as a second product screw that transports the second product guided by the second product guide  63  in a lateral direction. The second product collected by the second product collector  27  is transported diagonally upward and frontward by the second product returner  32 , and is returned to the upper side (upstream side of the sorting unit  42 ) relative to the swinging sorting apparatus  24 . The second product returner  32  is constituted by a screw-type conveyor. 
     The first product collector  26  is driven by a first product collection motor M 1  (see  FIG. 2 ), which is an electric motor, and the second product collector  27  is driven by a second product collection motor M 2  (see  FIG. 2 ), which is an electric motor. 
     The motive power of the first product collection motor M 1  is transmitted to the first product collector  26 , is transmitted from the first product collector  26  to the first product collection transporter  29 , and is transmitted from the first product collection transporter  29  to the storage screw  30 . Here, the first product collection transporter  29  is provided on the right side portion (outside of the right wall) of the threshing apparatus  1 , and the first product collection motor M 1  is provided on the left side portion of the threshing apparatus  1 . That is, the first product collection motor M 1  is provided on the side portion of the threshing apparatus  1  on the side opposite to the side on which the first product collection transporter  29  is provided. 
     The motive power of the second product collection motor M 2  is transmitted to the second product collector  27 , and is transmitted from the second product collector  27  to the second product returner  32 . Here, the second product returner  32  is provided on the right side portion (outside of the right wall) of the threshing apparatus  1 , and the second product collection motor M 2  is provided on the left side portion of the threshing apparatus  1 . That is, the second product collection motor M 2  is provided on the side portion of the threshing apparatus  1  that is on the side opposite to the side on which the second product returner  32  is provided. 
     The swinging sorting apparatus  24  sorts grain from the processed product. The swinging sorting apparatus  24  is arranged below the receiving net  23 , and the processed product leaks from the receiving net  23 . The swinging sorting apparatus  24  includes a frame-shaped sieve case  33 , which performs a swinging operation in the front-rear direction by an eccentric-cam-type swing drive mechanism  43  using an eccentric shaft or the like and is formed in a rectangular shape in a top view. 
     The sieve case  33  includes a first grain pan  34 , a plurality of first sieve lines  35 , a second sieve line  36 , a second grain pan  37 , a first chaff sieve  38 , a second chaff sieve  39 , a grain sieve  40 , an upper grain pan  61 , and a lower grain pan  65 . 
     The first chaff sieve  38  having a plurality of chaff lips  38 A is arranged rearward of the upper grain pan  61 , and a second chaff sieve  39  is arranged rearward of the first chaff sieve  38 . Note that the plurality of chaff lips  38 A are arranged side by side along the transport direction (front-rear direction) in which the processed product is transported, and each of the plurality of chaff lips  38 A is arranged in an inclined orientation that is oriented diagonally upward toward the rear end side. The lower grain pan  65  is arranged below the front end portion of the first chaff sieve  38 . The net-like grain sieve  40  is arranged rearward of the lower grain pan  65  in a state of being continuous with the lower grain pan  65 . The second chaff sieve  39  is arranged below the rear end portion of the first chaff sieve  38  and rearward of the grain sieve  40 . 
     In the sieve case  33 , an air passage for supplying the sorting air supplied from the upper discharge port  25   c  of the winnowing fan  25  along the upper surface of the upper grain pan  61  and an air passage for supplying the sorting air supplied from the rear discharge port  25   d  of the winnowing fan  25  along the upper surface of the lower grain pan  65  are formed. A discharger  28  is formed by the rear end portion of the swinging sorting apparatus  24  (the right end portion in  FIG. 3 ) and the rear end portion of the receiving net  23 . 
     In the swinging sorting apparatus  24  of the present embodiment, the processed product in the sieve case  33  is transported toward the body rear side due to the sorting air from the winnowing fan  25  being supplied from the body front side to the body rear side and the sieve case  33  swinging by the swing drive mechanism  43 . For this reason, in the following description, in the swinging sorting apparatus  24 , the upstream side in the transportation direction of the processed product is referred to as the front end or the front side, and the downstream side is referred to as the rear end or the rear side. 
     The grain sieve  40  is formed as a net-like body in which a plurality of metal wires are combined in a net-like shape, and is configured to allow grain to leak from the meshes. A first chaff sieve  38  is provided above the grain sieve  40 , and grain that has flowed between the chaff lips of the first chaff sieve  38  leaks onto the grain sieve  40 . 
     The sieve case  33  receives a large amount of the processed product that leaks from the receiving net  23 . Of the processed product leaking from the receiving net  23  in the sorting unit  42 , the processed product received by the upper grain pan  61  is supplied to the front end of the first chaff sieve  38  accompanying the swinging of the sieve case  33 . 
     The first chaff sieve  38  transports the processed product to the rear side through air sorting performed using the sorting air and specific gravity sorting accompanying swinging, and at the same time, leaks grain included in the processed product. Among the processed products subjected to such sorting, culms such as cut straw are delivered to the second chaff sieve  39 , are sent out from the rear end of the second chaff sieve  39  toward the rear of the sieve case  33 , and are discharged from the discharger  28  toward the waste straw shredding apparatus  13 . The culms discharged from the discharger  28  are shredded by the waste straw shredding apparatus  13  and are discharged to the outside of the threshing apparatus  1 . Also, the grain that leaks directly onto the second chaff sieve  39  via the receiving net  23  is sorted into grain and culms such as cut straw at the second chaff sieve  39 . 
     Here, considering the state of the processed product leaking from the receiving net  23 , among the harvested products supplied to the threshing chamber  21 , grain, grain that has been insufficiently processed into single grains, small pieces of straw, and the like leak through the receiving net  23  at an early stage when they are transported in the threshing chamber  21 . For this reason, the amount of leakage of the processed product in the upstream region of the receiving net  23  in the transport direction tends to be greater than that in the downstream region of the receiving net  23  in the transport direction. Also, as described above, since the processed product is supplied from the upper grain pan  61  to the front end side portion of the first chaff sieve  38 , the amount of the processed product leaking from the front end side portion of the first chaff sieve  38  is greater compared to that of the rear end side portion of the first chaff sieve  38 . 
     Also, the processed product that has leaked through the front end side portion of the first chaff sieve  38  is partially removed by sending part of it to the rear side using the sorting air immediately after leaking, and the processed product including a large amount of grain is received by the upper surface of the grain sieve  40 . Furthermore, since the air pressure of the sorting air and the swinging force act on the processed product supplied to the grain sieve  40 , the straw and the like included in the processed product are sent toward the rear on the upper surface of the grain sieve  40 , and the processed product that leaks through the grain sieve  40  includes a large amount of grain. The grain that has leaked through the grain sieve  40  flows down from the first product guide  62  to the first product collector  26  and is collected, and is stored in the grain tank  12  by the first product collection transporter  29 . 
     Also, although the processed product from the rear region of the first chaff sieve  38  is supplied to the grain sieve  40 , the cut straw and the like among the processed product that did not leak through the grain sieve  40  are sent rearward by the sorting air, and therefore the sorting processing is performed without significantly reducing the sorting efficiency in the rear region of the grain sieve  40 . 
     Furthermore, the first product (grain) leaked on the front side relative to the rearmost end of the grain sieve  40  flows down from the first product guide  62  to the first product collector  26 , is collected, and is stored in the grain tank  12  by the first product collection transporter  29 . 
     In contrast to this, the processed product that has leaked through the portion at the rearmost end of the grain sieve  40  or the processed product that has fallen from the second chaff sieve  39  flows down from the second product guide  63  to the second product collector  27 , is collected, and is returned to the upstream side of the swinging sorting apparatus  24  by the second product returner  32 . The processed product that did not fall from the second chaff sieve  39 , that is, debris such as straw waste generated by the sorting processing, is sent rearward from the rear end of the swinging sorting apparatus  24 , and is discharged from the discharger  28  to the straw waste shredding apparatus  13 . 
     As described above, the second product is returned to the upstream side, which is the front portion of the swinging sorting apparatus  24 , by the second product returner  32 . Specifically, the second product is returned to a position laterally to the receiving net  23  in the threshing unit  41 , which is a position at which the second product does not pass through (does not flow through) the receiving net  23 . Accordingly, an insertion hole is formed in the side wall  50  of the threshing unit  41  at a position outside in the radial direction of the circular arc-shaped receiving net  23 , and a second product discharge port  32 A of the second product returner  32  is provided in this insertion hole. That is, the second product discharge port  32 A of the second product returner  32  is provided at a position outside in the radial direction of the circular arc-shaped receiving net  23 , and the second product is discharged at this position. Thus, the threshing apparatus  1  is provided with a return amount detector  71  for detecting the return amount of the second product returned by the second product returner  32 .  FIGS. 4 to 6  show the arrangement mode of the second discharge port  32 A. 
     In the present embodiment, as shown in  FIG. 4 , the second product discharge port  32 A is provided toward the receiving net  23  side. As shown in  FIG. 5 , a rotary blade  32 B is provided in the vicinity of the second discharge port  32 A. The second product returner  32  is provided with a screw-type conveyor, and the rotary blade  32 B rotates integrally with the screw-type conveyor. The second product transported by the second product returner  32  is discharged to the outer side in the radial direction from the second product discharge port  32 A by the rotary blade  32 B (discharged as indicated by the broken line arrow in  FIG. 6 ). 
     The second product discharge port  32 A is provided with a guide  32 C that guides the discharged second product toward the upper side in the processed product transport direction of the swinging sorting apparatus  24 . The guide  32 C is formed in a shape that forms part of a cylinder having an inner peripheral surface that opposes the second product discharge port  32 A. In other words, the guide  32 C is formed in a shape obtained by bending a band plate into a circular arc shape. The discharge direction of the second product discharged by the rotating blade  32 B is restricted by the inner peripheral surface of the guide  32 C, and the second product is discharged toward the upper side in the transfer direction. 
     As shown in  FIGS. 5 and 6 , the return amount detector  71  is supported by the inner side portion of the side wall  50  of the threshing unit  41 . The second product is discharged from the second product discharge port  32 A by the rotary blade  32 B in the second product returner  32 , and the return amount detector  71  is configured to measure the return amount of the second product that is returned by coming into contact with the second product. The return amount detector  71  includes a swing arm  72 , a measurement portion  73 , a support frame  74  that supports the measurement portion  73  and the swing arm  72 , and a cover body  75  that covers the upper part of the return amount detector  71 . The swing arm  72  is located on the discharge extension line (on the parabola) which is a trajectory of the second product discharged by the second product returner  32 , and swings due to the discharged second product coming into contact therewith. The measurement portion  73  measures the return amount based on the swing angle of the swing arm  72 . 
     The support frame  74  is provided above the second product discharge port  32 A. The support frame  74  is formed by bending a strip plate into an approximate L shape, is provided with attachment portions  74   a  at end portions on both sides, and the attachment portions  74   a  are bolted to the side wall  50 . A potentiometer is built inside the case of the measurement portion  73 , and the measurement portion  73  is bolted to a location on the body inner side of the support frame  74 . The rotation shaft  76  of the measurement portion  73  is inserted through the support frame  74  and protrudes to the outside of the body (side wall  50  side). The swing arm  72  is attached to the rotation shaft  76 , and the swing arm  72  and the rotation shaft  76  are configured to be able to integrally rotate. The swing arm  72  extends downward from the rotation shaft  76  and is provided in a state of being located in a guide path in which the second product is guided by the guide  32 C. The swing arm  72  is supported so as to be able to swing about the axis of the rotation shaft  76  serving as the horizontal axis. 
     The cover body  75  is provided along the upper edge of the support frame  74 , and is configured to cover the upper portions of the swing arm  72 , the measurement portion  73 , and the support frame  74 . By providing such a cover body  75 , it is possible to prevent fine debris among the threshed products that leak through the receiving net  23  from falling on the swing arm  72  and the measurement portion  73  and hindering the measurement operation. 
     As shown in  FIG. 7 , the upper end portion of the swing arm  72  extends above the rotation shaft  76 . The spring receiving portion  77  is supported by the support frame  74 . A coil spring  78  is stretched between the portion of the swing arm  72  that extends above the rotation shaft  76  and the spring receiving portion  77 . The swing arm  72  is swing-biased by the pulling biasing force of the coil spring  78  so that the free end portion of the swing arm  72  on the side opposite to the side on which the coil spring  78  is located approaches the second product discharge port  32 A. A locking portion  79  is provided on the cover body  75 , the upper end portion of the swing arm  72  abuts on the locking portion  79 , and the swing arm  72  is positionally held in a downward standby orientation against the spring biasing force. 
     When the second product is discharged by the rotary blade  32 B through the second product discharge port  32 A and comes into contact with the swing arm  72 , due to the pressing force of the second product, the swing arm  72  swings against the biasing force of the coil spring  78 . When the swing arm  72  swings, the portion of the swing arm  72  below the rotation shaft  76  is separated from the second product discharge port  32 A. The swing angle is measured by the measurement portion  73 , and the return amount of the second product can be obtained based on the measurement result. 
     As described above, the swinging sorting apparatus  24  sorts the grain as the sorted product from the processed product, but the amount of the sorted product to be sorted can be changed in accordance with the return amount detected by the return amount detector  71 . The amount of the sorted product to be sorted being changeable in accordance with the return amount means that the sorting ability of the swinging sorting apparatus  24  can be changed in accordance with the return amount. The sorting ability of the swinging sorting apparatus  24  corresponds to the ratio of the amount of the first product collected by the first product collector  26  to the amount of the processed product leaking from the receiving net  23 , that is, the degree of sorting (or the sorting efficiency). 
     Here, if the amount of the crop reaped by the reaping portion  4  per unit time is constant, the amount of the processed product threshed by the threshing unit  41  per unit time does not change significantly and is constant. For this reason, the amount of processed product leaking from the receiving net  23  to the sorting unit  42  per unit time is also a constant amount. In this case, if the return amount from the second product returner  32  increases, it is envisioned that the number of processed products and second products waiting to be sorted by the swinging sorting apparatus  24  will gradually increase. 
     In such a case, since the threshing apparatus  1  cannot appropriately perform the threshing processing, in the present embodiment, the swinging sorting apparatus  24  is configured such that the sorting amount increases in accordance with an increase in the return amount. Increasing the sorting amount means increasing the amount of the first product collected by the first product collector  26 . Accordingly, the swinging sorting apparatus  24  is configured such that the amount of the first product collected by the first product collector  26  increases in accordance with an increase in the return amount relative to a predetermined threshold amount set in advance. 
     In this embodiment, the chaff lip  38 A is used to increase the sorting amount. As described above, the first chaff sieve  38  is provided with a plurality of chaff lips  38 A, and each of the plurality of chaff lips  38 A is arranged in an inclined orientation that is oriented diagonally upward toward the rear end side. In the present embodiment, the opening degree of each of the chaff lips  38 A can be changed. The opening degree being changeable means that the inclined orientation is changed. Specifically, the closer the chaff lip  38 A is to being parallel to the front-rear direction, the smaller the opening degree is, and the closer the chaff lip  38 A is to being parallel to the vertical direction, the larger the opening degree is. 
     In the present embodiment, the chaff lip  38 A is configured such that the opening degree increases in accordance with an increase in the return amount. That is, the inclined orientation of the chaff lip  38 A is changed to be closer to being parallel to the vertical direction in accordance with an increase in the return amount. As a result, the sorting amount of the first product in the first chaff sieve  38  increases, and it is possible to suppress the increase in the processed product and the second product waiting to be sorted in the swinging sorting apparatus  24 . 
     As described above, the second product is the processed product including grain that has been insufficiently processed into single grains, cut straw, and the like. In view of this, it is preferable that the winnowing fan  25  has a configuration in which the amount of sorting air increases in accordance with an increase in the return amount of the second product by the second product returner  32 , such that the cut straw and the like are removed in the first chaff sieve  38  and the grain sieve  40 . As a result, the ability of the first chaff sieve  38  and the grain sieve  40  to remove cut straw and the like improves, and even if the opening degree of the chaff lip  38 A is large, the inclusion of cut straw and the like into the first product collector  26  can be reduced. 
     Here, the sorting unit  42  of the present embodiment includes a layer thickness sensor  80  (an example of a “threshed product detector”) that detects the amount of processed product leaking from the receiving net  23 . Specifically, the layer thickness sensor  80  detects the layer thickness of the processed product that has leaked onto the sieve case  33  from the receiving net  23 . Since such a layer thickness sensor  80  is known, description thereof will be omitted here. It is also possible to use a configuration in which the sorting amount in the swinging sorting apparatus  24  is changed in accordance with the amount of the processed product detected by the layer thickness sensor  80 , that is, the layer thickness of the processed product on the sieve case  33 . Note that the position in the front-rear direction at which the layer thickness sensor  80  is provided may be on the front side relative to the position shown in  FIG. 3 . 
     In the above-described configuration, the opening degree of the chaff lip  38 A may be increased in accordance with an increase in the layer thickness of the processed product on the sieve case  33  when exceeding a predetermined threshold value. As a result, it is possible to suppress an increase in the amount of the processed product on the sieve case  33 . Note that the layer thickness sensor  80  may also perform the above-described control separately (independently) from the return amount detector  71 . 
     Also, both the opening degree of the chaff lip  38 A and the amount of the sorting air of the winnowing fan  25  may be changed in accordance with the detection result of the layer thickness sensor  80  (the layer thickness of the processed product on the sieve case  33 ). Specifically, for example, if the layer thickness of the processed product on the sieve case  33  exceeds a predetermined threshold value, it is preferable to increase the opening degree of the chaff lip  38 A and increase the amount of the sorting air of the winnowing fan  25 . It is also possible to use a configuration in which, if the layer thickness of the processed product on the sieve case  33  is a predetermined threshold value or less, the opening degree of the chaff lip  38 A is reduced and the amount of the sorting air of the winnowing fan  25  is reduced. 
     Also, as described above, a plurality of debris conveying valves  53   a  are provided on the inner surface (lower surface) of the top plate  53  in the threshing chamber  21 . These debris conveying valves  53   a  exert a force for moving the processed product rotating together with the threshing drum  22  to the rear side in the threshing chamber  21 . The debris conveying valve  53   a  is configured such that the attachment angle with respect to the top plate  53  can be changed. As a result, the conveying amount in the drum body  60  can be changed. In view of this, it is also possible to use a configuration in which the inclination of the debris conveying valve  53   a  with respect to the front-rear direction is controlled and the conveying amount of the crops in the drum body  60  is reduced in accordance with an increase in the return amount of the second product by the second product returner  32 . 
     That is, by performing setting such that the conveying amount of the crops in the drum body  60  decreases in accordance with an increase in the return amount of the second product by the second product returner  32  when exceeding a predetermined threshold value, the crop is less likely to fall from the threshing chamber  21 , and it is possible to suppress an increase in the amount of the processed product on the sieve case  33 . 
     Furthermore, it is also possible to use a configuration in which the amount of crops supplied to the threshing unit  41  itself is reduced in accordance with an increase in the return amount of the second product by the second product returner  32 . As a result, an increase in the amount of the processed product on the sieve case  33  is suppressed. As such a method, for example, it is preferable to use a configuration in which the traveling speed of the travel device body  17  is reduced in accordance with an increase in the return amount of the second product by the second product returner  32 . 
     As described above, the threshing apparatus  1  controls the sorting ability of the swinging sorting apparatus  24  in accordance with the return amount of the second product by the second product returner  32 . In other words, the sorting amount by the swinging sorting apparatus  24  (the sorting ability of the swinging sorting apparatus  24 ) is feedback-controlled based on the return amount of the second product by the second product returner  32 . Accordingly, the opening degree of the chaff lip  38 A, the amount of the sorting air by the winnowing fan  25 , the inclination of the debris conveying valve  53   a  in the front-rear direction, and the traveling speed of the travel device body  17  correspond to the gain adjustment parameters in the feedback control. 
       FIG. 8  shows the change over time in the return amount of the second product, and  FIG. 9  shows a mode of the chaff lip  38 A in which the opening degree is changed in accordance with the return amount. Accompanying an increase in the return amount at time t 1  and onward, the opening degree of the chaff lip  38 A increases, and the increase in the return amount stops at time t 2 . Thereafter, the return amount decreases from time t 3  to time t 4 . Accompanying this, the opening degree of the chaff lip  38 A returns to the same opening degree as before time t 1 . In this manner, with the threshing apparatus  1  of the present embodiment, even if the return amount of the second product increases, reduction of the threshing function is suppressed. 
     OTHER EMBODIMENTS 
       FIGS. 10 and 11  show an example of a configuration in which the return amount detector  71  can detect the return amount of the second product with good sensitivity. In the embodiment shown in  FIGS. 10 and 11 , the guide  32 C has a planar shape that extends along the swing path of the swing arm  72 , and is provided laterally to the swing arm  72  in a state of being adjacent to the swing arm  72  in the swing axis direction of the swing arm  72 . The guide  32 C is supported in a cantilever fashion on the side wall  50  of the threshing unit  41 . Note that the guide  32 C may also be supported on both ends by the side wall  50 . 
     In order for the return amount detector  71  to accurately detect the return amount of the second product, it is preferable that the swing arm  72  swings accurately in accordance with the return amount of the second product. In particular, since the second product is guided to the upper side in the transfer direction of the swinging sorting apparatus  24  by the guide  32 C, the second product discharged from the second product discharge port  32 A is easily concentrated on the guide surface of the guide  32 C. For this reason, if the separation distance between the swing arm  72  and the guide  32 C changes accompanying the swinging of the swing arm  72 , the detection accuracy of the return amount detector  71  is influenced. In particular, if a configuration is used in which the separation distance between the swing arm  72  and the guide  32 C decreases the more the swing arm  72  swings, it is thought that the swing arm  72  will suddenly fully swing to the maximum of the swing range at the time when the return amount of the second product exceeds a predetermined amount. If this occurs, a case is conceivable in which the detection value of the measurement portion  73  will remain stuck at the maximum value in the state where the swing arm  72  has fully swung, and if the return amount of the second product is large, the return amount detector  71  cannot accurately measure the return amount. That is, if a configuration is used in which the separation distance between the swing arm  72  and the guide  32 C decreases accompanying the swinging of the swing arm  72 , the detection sensitivity of the return amount detector  71  decreases when the return amount of the second product is small and the detection sensitivity of the return amount detector  71  becomes excessive when the return amount of the second product is large. For this reason, it is desirable to use a configuration in which the swing arm  72  does not fully swing and the return amount can be measured accurately even if the return amount of the second product is large. Also, since the return amount of the second product is often small, it is preferable to use a configuration in which the return amount detector  71  can detect the return amount of the second product with good sensitivity even if the return amount of the second product is small. 
     In the embodiment shown in  FIG. 10 , the support base end portion region of the guide  32 C is formed into a circular arc shape, and the guide  32 C is formed so as to be closer to a linear shape toward the leading end side (the side away from the side wall  50 ). The swing arm  72  and the guide  32 C approach each other in a state in which the swing arm  72  is positionally held in the downward standby orientation. At this time, the separation distance between the swing arm  72  and the guide  32 C is the same over the region from the swing base end portion where the rotation shaft  76  is located to the free end portion located below the rotation shaft  76  of the swing arm  72 . 
     When the second product is discharged from the second product discharge port  32 A, the second product comes into contact with the swing arm  72  and the swing arm  72  swings. At this time, the separation distance between the lower region of the swing arm  72  and the guide  32 C is greater than the separation distance between the swing base end portion of the swing arm  72  and the guide  32 C. In  FIG. 10 , the state in which the swing arm  72  has swung is indicated by a solid line, and the separation distance between the central portion of the swing arm  72  in the lengthwise direction indicated by the solid line and the guide  32 C is indicated by the distance d 1 . 
     When the contact amount between the second product and the swing arm  72  increases and the swing arm  72  swings further, the separation distance between the lower region of the swing arm  72  and the guide  32 C further increases. In  FIG. 10 , the state in which the swing arm  72  has swung further is indicated by a broken line, and the separation distance between the central portion of the swing arm  72  in the lengthwise direction indicated by the broken line and the guide  32 C is indicated by the distance d 2 . The distance d 2  is greater than the distance d 1 . That is, in accordance with an increase in the swing amount of the swing arm  72 , the gap between the guide  32 C and the swing arm  72  (the space or region between the edge of the swing arm  72  on the guide  32 C side extending between the base end portion and the free end portion and the guide  32 C) increases, and the second product slips more easily through the gap between the side portion of the swing arm  72  and the guide  32 C. In other words, the guide  32 C is configured such that when the swing arm  72  comes into contact with the second product and swings, the separation distance between the side portion of the swing arm  72  and the guide  32 C increases in accordance with an increase in the swing amount. 
     The guide  32 C may also be formed in a bent shape as shown in  FIG. 11 . The guide  32 C is formed by bending in a direction toward the front of the body between the support base end portion and the leading end portion of the guide  32 C. The guide  32 C has a flat planar shape along the swing path of the swing arm  72 , and is provided laterally to the swing arm  72  in a state of being adjacent to the swing arm  72  in the swing axis direction of the swing arm  72 . 
     With the shape of the guide  32 C shown in  FIG. 11 , the guide  32 C is configured such that the separation distance between the side portion of the swing arm  72  and the guide  32 C is the same regardless of the magnitude of the swing amount when the swing arm  72  comes into contact with the second product and swings. In  FIG. 11 , the state in which the swing arm  72  has swung is indicated by a solid line, and the separation distance between the central portion of the swing arm  72  in the longitudinal direction indicated by the solid line and the guide  32 C is indicated by the distance d 11 . The state in which the swing arm  72  has swung further is indicated by a broken line, and the separation distance between the central portion of the swing arm  72  in the lengthwise direction indicated by the broken line and the guide  32 C is indicated by the distance d 12 . The distance d 11  and the distance d 12  are the same. That is, the size of the gap between the guide  32 C and the swing arm  72  is constant or approximately constant regardless of the swing amount of the swing arm  72 . 
     In  FIG. 12 , the relationship between the return amount of the second product and the swing amount of the swing arm  72  is indicated by a line graph. The configuration in which the separation distance between the swing arm  72  and the guide  32 C decreases the more the swing arm  72  swings is indicated by the “first pattern”. The configuration in which the separation distance between the swing arm  72  and the guide  32 C increases the more the swing arm  72  swings, that is, the configuration shown in  FIG. 10 , is indicated by the “second pattern”. The configuration in which the separation distance between the side portion of the swing arm  72  and the guide  32 C is the same regardless of the magnitude of the swing amount of the swing arm  72 , that is, the configuration shown in  FIG. 11 , is indicated by the “third pattern”. 
     In the range where the return amount of the second product is between zero and F 1 , the swing amount of the swing arm  72  in the line graph of the second pattern is greater than the swing amount of the swing arm  72  in the line graph of the first pattern. Also, in the range where the return amount of the second product is between zero and F 1 , the swing amount of the swing arm  72  in the line graph of the third pattern is greater than the swing amount of the swing arm  72  in the line graph of the first pattern. Therefore, in the second pattern and the third pattern, the swing arm  72  swings firmly even if the return amount of the second product is small compared to the case of the first pattern, and the measurement sensitivity of the return amount detector  71  in the region where the return amount is low is high. 
     In the line graph of the first pattern, when the return amount approaches the region of F 2 , the swing amount of the swing arm  72  suddenly increases, and when the return amount reaches the region of F 3 , the swing amount of the swing arm  72  fully swings to the maximum, and the return amount detector  71  cannot measure a return amount higher than that. In the line graphs of the second pattern and the third pattern, even if the return amount approaches the region of F 2 , the swing amount of the swing arm  72  does not increase rapidly, and the line graph of the first pattern surpasses the line graphs of the second pattern and the third pattern. 
     In the first pattern, in accordance with an increase in the swing amount of the swing arm  72 , the separation distance between the side portion of the swing arm  72  and the guide  32 C is reduced, and therefore the degree of contact between the second product and the swing arm  72  increases, and the swing amount of the swing arm  72  further increases in accordance with an increase in the amount of the second product. In the second pattern, in accordance with an increase in the swing amount of the swing arm  72 , the separation distance between the side portion of the swing arm  72  and the guide  32 C is increased, and therefore second product easily slips through the gap between the side portion of the swing arm  72  and the guide  32 C and the swing amount of the swing arm  72  is suppressed. In the second pattern, the separation distance between the side portion of the swing arm  72  and the guide  32 C is the same regardless of the magnitude of the swing amount, and therefore the frequency of contact between the second product and the swing arm  72  is low and the swing amount of the swing arm  72  is suppressed compared to the case of the first pattern. 
     In the line graph of the second pattern, when the return amount approaches the region of F 4 , which is greater than F 3 , the swing amount of the swing arm  72  reaches the maximum or substantially the maximum. In this manner, in the case of the second pattern, compared to the case of the first pattern, the return amount detector  71  can measure the return amount with good sensitivity even if the return amount of the second product is small, and can measure the magnitude of the return amount in a wide range. 
     Also, in the line graph of the third pattern, when the return amount approaches the region of F 4 , which is greater than F 3 , the swing amount of the swing arm  72  reaches the maximum or substantially the maximum. In this manner, in the case of the third pattern, compared to the case of the first pattern, the swing arm  72  is less likely to fully swing and the return amount detector  71  can measure the magnitude of the return amount in a wider range. 
     In the above embodiment, a configuration was used in which the return amount detector  71  is supported by the inner side portion of the side wall  50 , but as shown in  FIGS. 13 and 14 , it is also possible to use a configuration in which the return amount detector  71  is supported by the outer side portion of the side wall  50 . 
     In this embodiment, the return amount detector  71  includes a swing arm  72  and a measurement portion  73 , similarly to the above embodiment. As shown in  FIGS. 13 and 14 , the support frame  90  that supports the swing arm  72  and the measurement portion  73  is formed in an approximate box shape, and is fixed and supported on the outer surface of the side wall  50  by bolting. The measurement portion  73  is supported by the outer surface  90 A of the support frame  90 . The rotating shaft  76  of the measurement portion  73  passes through the outer surface  90 A of the support frame  90  and protrudes to the side where the side wall  50  is located. The rotation support shaft  91  of the swing arm  72  is rotatably supported by a pivot boss  92  through which the inner side surface  90 B of the support frame  90  is inserted. The rotation support shaft  91  passes through the inner side surface  90 B and extends to the side where the measurement portion  73  is located. The swing arm  72  extends downward from the rotation support shaft  91  on the body inner side relative to the side wall  50 . The swing arm  72  is provided in a state of being located in a guide path on which the second product is guided by the guide  32 C. 
     As shown in  FIG. 15 , at a location on the outer side relative to the side wall  50  of the rotation support shaft  91 , a linking member  93  extending outward in the radial direction and a contact member  94  obtained by bending a rod body in an approximate L shape are provided in a state of being integrally rotated with the rotating support shaft  91 . Also, the rotating shaft  76  of the measuring unit  73  is provided with an operating arm  95  extending outward in the radial direction. A locking pin  96  extending toward the side wall  50  is provided on the free end side of the operation arm  95 . The locking pin  96  is engaged and linked to the linking member  93  in a state of being inserted through an insertion hole  97  formed in the linking member  93 . The insertion hole  97  is an elongated hole that is longer in the radial direction. A coil spring  99  is stretched between the linking member  93  and the spring receiving portion  98  of the support frame  90 , and the swing arm  72  is biased to return to the downward standby orientation (see  FIG. 15 ) due to the biasing force of the coil spring  99 . The abutting member  94  abuts on a front side surface  90 C of the support frame  90 , and the swing arm  72  is positionally held in the standby orientation. When the return amount of the second product increases, the swing arm  72  is pushed by the second product and swings. The abutting member  94  is restricted by abutting on the rear side surface  90 D of the support frame  90  (see  FIG. 16 ) at the maximum swing position. Due to this configuration, the axes of the rotation shaft  76  of the measurement portion  73  and the rotation support shaft  91  of the swing arm  72  do not need to be accurately aligned with each other and thus assembly is easier. 
     When the second product discharged from the second product discharge port  32 A by the rotary blade  32 B comes into contact with the swing arm  72 , the swing arm  72  swings in the direction away from the second product discharge port  32 A against the biasing force of the coil spring  99  due to the pressing force of the second product. Along with this, the rotation shaft  76  of the measurement portion  73  is operated to rotate via the operating arm  95 , the locking pin  96 , and the linking member  93 , and the swing angle of the swing arm  72  is measured. Then, the return amount of the second product can be obtained based on the measurement result of the swing angle. 
     In the above-described embodiment, the return amount detector  71  is configured to include the swing arm  72  and the measurement portion  73  for measuring the swing angle of the swing arm  72 , but instead of this configuration, the following configuration may also be used. 
     In this embodiment, as shown in  FIGS. 17 to 19 , the return amount detector  71  is provided ahead in the discharge direction restricted by the guide  32 C. Also, the return amount detector  71  has a cuboid pressure-sensitive portion  100 , a pressure-receiving portion  101 , and a support portion  102 . The pressure-sensitive portion  100  is formed using a known piezoelectric material. The pressure-sensitive portion  100  is fixed to the non-rotating portion of the threshing unit  41  via a bracket  103  (see  FIG. 19 ). The pressure-receiving portion  101  is provided in a thin plate shape. The pressure-receiving portion  101  is connected to the pressure-sensitive portion  100  via the supporting portion  102  such that the pressure-sensitive portion  100  can detect the pressure from the second product guided by the guide  32 C. In order to make the pressure-sensitive portion  100  more likely to bend in response to the pressure from the second product, between the end portion to which the support portion  102  is connected and the end portion fixed to the bracket  103 , a through hole  104  is provided that penetrates in a direction orthogonal to both the direction of a line connecting the two end portions and the stacking direction of the pressure-sensitive portion  100  and the pressure-receiving portion  101 . Accordingly, the return amount detector  71  can detect the return amount of the second product. 
     In the above-described embodiment, description was given taking an example of a case where the threshing apparatus  1  is mounted on the combine  20 , but the threshing apparatus  1  may also be mounted on a work vehicle different from the combine  20 , or may be applied to a work vehicle in which only the threshing apparatus  1  is mounted. 
     In the above-described embodiment, regarding the swinging sorting apparatus  24 , it was described that the amount of the processed product to be sorted is changed in accordance with the return amount, but for example, it is also possible to use a configuration in which the sorting amount of the swinging sorting apparatus  24  is not changed in accordance with the return amount, but notification is performed if the return amount detected by the return amount detector  71  exceeds a predetermined amount. 
     In the above-described embodiment, it was described that the sorting amount of the swinging sorting apparatus  24  is increased in accordance with an increase in the return amount, but the change amount for increasing the sorting amount of the swinging sorting apparatus  24  may also be changed in accordance with the change amount by which the return amount increases, or the increase amount of the sorting amount may also be changed if the return amount exceeds a set value. 
     In the above-described embodiment, the chaff lip  38 A was described as having a larger opening degree the greater the return amount is, but the amount of change in the opening degree of the chaff lip  38 A may also be changed in accordance with the amount of change by which the return amount increases, or the opening degree may also be changed if the return amount exceeds a set value. Furthermore, a configuration may also be used in which if the return amount is smaller than a preset reference amount, the opening degree of the chaff lip  38 A is reduced. 
     In the above embodiment, it was described that the amount of sorting air of the winnowing fan  25  is increased in accordance with an increase in the return amount, but the amount of change in the amount of air of the winnowing fan  25  may also be changed in accordance with the amount of change by which the return amount increases, or the amount of the sorting air may also be changed if the return amount exceeds a set value. 
     In the above-described embodiment, the sorting unit  42  was described as including the layer thickness sensor  80 , but the sorting unit  42  can also be formed without including the layer thickness sensor  80 . 
     It is also possible to use a configuration in which the opening degree of the chaff lip  38 A is changed based on the detection results of both the layer thickness sensor  80  and the return amount detector  71  (considering the detection results of both). 
     In the above-described embodiment, the threshing drum  22  was described as reducing the conveying amount of the crops in the drum body  60  in accordance with an increase in the return amount, but the amount of change in the conveying amount of the threshing drum  22  may also be changed in accordance with the change amount by which the return amount increases, or the conveying amount may also be changed if the return amount exceeds a set value. Of course, it is also possible to use a configuration in which the conveying amount of the crop in the drum body  60  is not changed, regardless of the return amount. 
     In the above-described embodiment, it was described that the traveling speed of the travel device body  17  is reduced in accordance with the return amount, but the change amount by which the traveling speed of the travel device body  17  is reduced may also be changed in accordance with the change amount by which the return amount increases, or the traveling speed may also be changed if the return amount exceeds a set value. 
     In the above-described embodiment, a configuration was used in which the first product collector  26  and the second product collector  27  are driven by an electric motor, but instead of this configuration, it is also possible to use a configuration in which the motive power from the engine E is transmitted via a transmission belt. 
       FIGS. 20 to 23  show an example of a configuration in which the return amount detector  71  can detect the return amount of the second product with good sensitivity. In the embodiment shown in  FIGS. 20 to 23 , the second product returner  32  extending vertically is supported on the right side surface of the side wall  50  on the body right side. The second product collected by the second product collector  27  is transported upward by the second product returner  32  and is returned to the upper side relative to the swinging sorting apparatus  24 . 
     The second product discharge port  32 A and the guide  32 C formed in a box shape are provided at the upper end portion of the second product returner  32 . The second product discharge port  32 A is located on the body right side (the outer side with respect to the threshing apparatus  1 ) relative to the side wall  50  on the body right side. The guide  32 C is interposed between the second product discharge port  32 A and the side wall  50  in a state of being located on the body front side of the second product discharge port  32 A. The guide  32 C is located on the body front side of the second product discharge port  32 A. The guide  32 C is formed so as to be closer to the side wall  50  toward the front side relative to the second discharge port  32 A in a plan view. That is, the guide  32 C is formed so as to bulge to the body right side relative to the side wall  50  on the right side, corresponding to the position and shape of the second product discharge port  32 A. Also, the guide  32 C is formed wider in the vertical direction toward the front side relative to the second product discharge port  32 A. That is, the guide  32 C is formed so as to have a diverging shape toward the front side relative to the second product discharge port  32 A. 
     The rotary blade  32 B rotates counterclockwise in the plan view of  FIG. 22 . The second product discharged from the second product discharge port  32 A by the rotary blade  32 B is guided to the upper side in the transfer direction of the swinging sorting apparatus  24  along the surface on the inner peripheral side of the guide  32 C. 
     A top plate  32   t  is formed at the upper end portion of the guide  32 C shown in  FIGS. 20 to 23 , and an opening is formed in the top plate  32   t . Also, a bulging portion  110  is provided on the top plate  32   t  so as to cover this opening. The bulging portion  110  bulges upward relative to the top plate  32   t , and a bulging space H is formed inside the bulging portion  110 . 
     The rotation shaft  76  of the swing arm  72  is supported by the bulging portion  110 . The swing arm  72  penetrates through the opening of the top plate  32   t  and can swing over the bulging space H and the space on the swinging sorting apparatus  24  side in the guide  32 C. The bulging portion  110  is formed such that the portion located directly above the rotation shaft  76  is the highest position of the bulging portion  110 . Also, an inclined surface  110   a  is formed on the body front portion of the bulging portion  110 , and the inclined surface  110   a  approaches the upper end portion of the guide  32 C toward the body front side. Note that in order to show the swing arm  72  in an easily comprehensible manner, the inclined surface  110   a  in  FIG. 22  shows only the portion on front lower side. 
     The inner peripheral side surface of the guide  32 C shown in  FIGS. 20 to 23  has a flat planar shape along the swing path of the swing arm  72 . The swing arm  72  is provided laterally to the surface on the inner peripheral side of the guide  32 C in a state of being adjacent to the surface on the inner peripheral side of the guide  32 C in the direction of the swing axis of the swing arm  72 . The guide  32 C is configured such that, when the swing arm  72  comes into contact with the second product and swings, the separation distance between the side portion of the swing arm  72  and the guide  32 C is the same regardless of the magnitude of the swing amount. That is, the size of the gap between the guide  32 C and the swing arm  72  is constant or approximately constant regardless of the swing amount of the swing arm  72 . 
     When the amount of the second product discharged from the second product discharge port  32 A increases and the swing arm  72  swings significantly, the swing arm  72  and the front lower end portion of the inclined surface  110   a  come into contact with each other, and the swing arm  72  stops swinging. In other words, due to the swing arm  72  and the front lower end portion of the inclined surface  110   a  coming into contact with each other, the swing arm  72  fully swings to the maximum. In this state, substantially the entirety of the swing arm  72  other than the free end portion is located above the guide  32 C and is housed in the bulging portion  110 . At this time, since the second product discharged along the inner peripheral side surface of the guide  32 C touches only the free end portion of the swing arm  72 , most of the second product does not touch the swing arm  72  and is guided upward in the transfer direction of the swinging sorting apparatus  24 . 
     A stay  111  is provided on the body left side of the bulging portion  110 , and the stay  111  is supported by the bulging portion  110 . Although not shown in the drawings, the stay  111  is coupled to and supported by the side wall  50  on the body right side. The measurement portion  73  is supported by the stay  111 . A through hole is formed in the stay  111 , and the rotating shaft  76  penetrates through the through hole. An operating arm  112  is provided at an end portion of the rotating shaft  76  on the side opposite to the side where the swing arm  72  is located with the stay  111  interposed therebetween, and the operating arm  112  extends outward in the radial direction of the rotating shaft  76 . Also, an operating arm  113  is provided on the rotation axis of the measurement portion  73 , and the operating arm  113  extends outward in the radial direction. A circular hole is formed in one of the operating arm  112  and the operating arm  113 , and an elongated hole is formed in the other of the operating arm  112  and the operating arm  113 . The elongated hole extends along the other longitudinal direction. Also, the operating arm  112  and the operating arm  113  are coupled by a pin by inserting one pin  114  through the one circular hole and the other elongated hole. As a result, the swing arm  72  that rotates integrally with the rotating shaft  76  and the measurement portion  73  are interlocked and coupled to each other via the operating arm  112 , the operating arm  113 , and the pin  114 . 
     The configuration disclosed in the above-described embodiment (including other embodiments; the same applies hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. Also, the embodiment disclosed in this specification is an example, and the embodiment of the present invention is not limited to this, and can be modified as appropriate without departing from the object of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be used in a threshing apparatus that includes a threshing unit that has a receiving net and threshes crops, and a sorting unit that is provided below the threshing unit and sorts grain from a threshed product that has leaked from the receiving net. 
     DESCRIPTION OF REFERENCE SIGNS 
     
         
         
           
               1  Threshing apparatus 
               17  Travel device body 
               22  Threshing drum 
               23  Receiving net 
               24  Swinging sorting apparatus (sorter) 
               25  Winnowing fan 
               26  First product collector 
               27  Second product collector 
               32  Second product returner 
               32 C Guide portion 
               38  First chaff sieve (chaff sieve) 
               38 A Chaff sieve 
               41  Threshing unit 
               42  Sorting unit 
               50  Side wall 
               55  Rotation support shaft (threshing drum shaft) 
               58   b  Threshing tooth 
               60  Drum body 
               71  Return amount detector 
               72  Swing arm 
               73  Measurement portion 
               75  Cover body 
               80  Layer thickness sensor (threshed product detector)