Abstract:
A fill detection device for a grass container includes:
       a detection switch;   a pivot sensor that is fastened inside the grass container, that can actuate the detection switch as a result of contact with cut grass, and whose position can be changed between a raised non-detection position and a lowered detection position, the pivot sensor having:
           a first pressure-sensing surface that faces generally upwardly when the pivot sensor is in the non-detection position; and   a second pressure-sensing surface that is linked to the first pressure-sensing surface, and that faces generally substantially rearwardly when the pivot sensor is in the non-detection position.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to fill detection devices for grass containers of lawn mowers and to grass containers provided with such a device. 
   When the cut grass that has accumulated in the grass container has reached a preset amount, e.g. when the grass container is fill, then such a fill detection device can detect that the amount of cut grass retained in the grass container has reached the preset amount through a detection operation of a detection means in which a pivot sensor is pivoted downward by the pressure exerted by the cut grass. 
   As this type of detection sensor, a sensor is known that is provided with a lever 88 (corresponding to a pivot sensor) that is supported by a mounting member 92 pivotably around a rotation axis 108, and an electric switch 96 in which a switch button 100 is actuated via a plate spring 98 by a second portion 102 of the lever 88, as shown in U.S. Pat. No. 6,272,818 (see cols. 7, 8, 9 and FIGS. 4 to 7). 
   Furthermore, as shown in this document, through the rotation of a swing arm 106 that is operatively fixed to the mounting member 92 around an axis 126, the mounting member 92 rotates together with the swing arm 106 around the axis 126, putting the lever 88 into a posture in which it extends in a relatively straight horizontal direction or into a vertical posture. 
   That is to say, by changing the angular position of the lever 88, it is possible to adjust the orientation of the pressure-sensing surface of the lever 88 such that the pressure-sensing surface when the lever 88 is in a raised non-detection posture is on the side facing upward or on the side facing sideways. 
   In this type of fill detection device, the pivot sensor is arranged nearly below the cut grass inlet port of the grass container, such that a detection is made before the cut grass collected in the grass container accumulates near the cut grass inlet port of the grass container and causes jamming of the cut grass inlet port. 
   As for the cut grass, there is light cut grass that is dry, and there is cut grass that is heavy e.g. because it is wet. In the case of light cut grass, the cut grass that is fed into the grass container falls down while being spread as it comes flying into the grass container, and tends to accumulate at a substantially uniform accumulation height over the entire area of the container. Also, if the pivot sensor receives the pressure exerted by the cut grass from a lateral direction when viewed from the direction of the pivot axis of the pivot sensor, then the efficiency with which the cut grass acts on the pivot sensor in order to pivot the pivot sensor is relatively poor. Therefore, in the case of light cut grass, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from a lateral direction, then already much more cut grass than the preset amount may have accumulated when the pivot sensor pivots downward and the detection means is actuated, and cut grass may easily accumulate up to the cut grass inlet port. 
   In the case of heavy cut grass, the cut grass that is fed into the container falls down without being spread within the grass container, and tends to accumulate with an accumulation height that is higher at locations further removed from the cut grass inlet port than at locations close to the cut grass inlet port. Moreover, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from a vertical direction with respect to the grass container, then the pivot sensor does not easily pivot downward as long as there is not very much cut grass above the pivot sensor, even when a relatively large amount of cut grass has accumulated in the grass container. Therefore, in the case of heavy cut grass, if the pivot sensor is adapted to receive the pressure exerted by the cut grass from above, then already much more cut grass than the preset amount may have accumulated when the pivot sensor pivots downward and the detection means is actuated, and cut grass may easily accumulate up to the cut grass inlet port. 
   When employing the above-described conventional detection technology, in the case of light cut grass, it is possible to realize a detection state in which the pivot sensor receives the pressure exerted by the cut grass from above by adjusting the angle of the pivot sensor such that the pressure-sensing surface of the pivot sensor faces upward, and in the case of heavy cut grass, it is possible to realize a detection state in which the pivot sensor receives the pressure exerted by the cut grass from the side by adjusting the angle of the pivot sensor such that the pressure-sensing surface of the pivot sensor faces to the side, but this requires the bothersome task of performing an angular adjustment of the pivot sensor depending on the weight or moisture of the cut grass. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a fill detection device for a grass container that can perform a suitable detection without requiring the task of an adjustment, regardless of whether the cut grass is light or heavy. 
   According to one aspect of the present invention, a fill detection device for a grass container includes:
         a detection switch;   a pivot sensor that is fastened inside the grass container, that can actuate the detection switch as a result of contact with cut grass, and whose position can be changed between a raised non-detection position and a lowered detection position, the pivot sensor having:
           a first pressure-sensing surface that faces generally upwardly when the pivot sensor is in the non-detection position; and   a second pressure-sensing surface that is linked to the first pressure-sensing surface, and that faces generally substantially rearwardly when the pivot sensor is in the non-detection position.   
               

   That is to say, the pressure-sensing portion of the pivot sensor includes a first pressure-sensing surface and a second pressure-sensing surface, so that if the cut grass is light and the cut grass accumulates at a substantially uniform accumulation height across the entire area of the container, a pressure is exerted on the first pressure-sensing of the pivot sensor by the cut grass that has accumulated above the pivot sensor. That is to say, the pivot sensor receives the pressure exerted by the cut grass from above, with respect to the vertical direction of the grass container. Thus, even when the accumulation height of the cut grass above the pivot sensor is low and the weight of the cut grass exerting pressure on the pivot sensor is relatively small, the pivot sensor is efficiently pivoted downward by the cut grass. Hence, a detection state can be realized in which the pivot sensor is pivoted downward and the detection means is actuated, before the actual accumulation amount of the cut grass becomes very different from the set amount, and before the cut grass accumulates to a height at which the cut grass inlet port is positioned. 
   If the cut grass is heavy, it tends to accumulate with an accumulation height that is higher at locations further removed from the cut grass inlet port than at locations close to the cut grass inlet port, and the cut grass that has accumulated to the side (when viewed from the pivot axis direction of the pivot sensor) exerts a pressure on the second pressure-sensing surface of the pivot sensor, even when cut grass hardly accumulates above the pivot sensor. That is to say, the pivot sensor receives the pressure exerted by the cut grass from the side. Thus, even when there is hardly any cut grass above the pivot sensor, a detection state can be realized in which the pivot sensor is pivoted downward and the detection means is actuated, before the overall amount of the cut grass accumulated in the container becomes very different from the set amount, and before the cut grass accumulates in the vicinity of the cut grass inlet port. 
   Consequently, with the present invention, it is possible to adjust the pivot sensor such that it receives the pressure of the cut grass from above, and to reduce the necessity for adjusting the pivot sensor such that it receives the pressure of the cut grass from the side. 

   
     BRIEF DISRUPTION OF THE DRAWINGS 
       FIG. 1  is an overall lateral view of a riding-type lawn mower. 
       FIG. 2  is an overall top view of a riding-type lawn mower. 
       FIG. 3(A)  is a lateral view showing how cut grass is discharged from the grass container. 
       FIG. 3(B)  is a lateral view showing a state in which the main container member is removed from the rear portion of the automotive vehicle body. 
       FIG. 4  is a longitudinal cross-sectional view of the grass container. 
       FIG. 5  is a rear view of the wall member of the grass container. 
       FIG. 6  is a lateral view of a fill detection device. 
       FIG. 7  is an oblique view of the fill detection device. 
       FIG. 8  is a front view of an adjustment guide member. 
       FIG. 9(A)  is a diagram illustrating how light cut grass accumulates. 
       FIG. 9(B)  is a diagram illustrating how heavy cut grass accumulates. 
       FIG. 10  is a sectional view showing how a cleaning rod is stowed away. 
       FIG. 11  is a lateral view of the portion of a grass cutter according to another embodiment that is provided with a cut grass discharge chute. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following is a detailed description of preferred embodiments of the present invention, with reference to the accompanying drawings. 
   As shown in  FIGS. 1 and 2 , a riding-type lawn mower is provided with a pair of steerable and drivable left and right front wheels  1 , a pair of drivable left and right rear wheels  2 , and a driving section including a prime mover portion such as an engine  3  that is provided at the front end of the vehicle body and adapted so as to transmit a moving force to the front and rear wheels  1  and  2 , and a driver seat  4  that is positioned above the region between the left and right rear wheels  2 . A grass cutter  10  is operatively coupled via a linking mechanism  6  to a vehicle frame  5  between the front and rear wheels. Motive power is transmitted from the engine  3  to the grass cutter  10 . A grass container  20  is provided behind the rear wheels  2  at the rear end of the automotive vehicle body. A cut grass discharge chute  11  of the grass cutter  10  is linked to the grass container  20  via a duct  30  that is arranged such that it is connected in the longitudinal direction of the automotive vehicle body to the region between the left and right rear wheels  2 . 
   This lawn mower performs the task of cutting lawn or grass. Through the operation of extending and contracting a hydraulic telescopic cylinder (not shown in the drawings) that is operatively linked to the linking mechanism  6 , the telescopic cylinder raises and lowers the linking mechanism  6  in a pivoting movement with respect to the vehicle frame  5 , thereby lowering the grass cutter  10  to a lowered operating position in which a ground gauge wheel  12  touches the ground and a raised operating position in which the ground gauge wheel  12  is raised from the ground. When the automotive vehicle body moves while the grass cutter  10  is in the lowered operating position, the grass cutter  10  cuts the lawn or grass with rotatively driven cutting blades  14  that are lined up in the transverse direction of the automotive vehicle body inside a cutting blade housing  13 . The cut lawn or grass (referred to for simplicity as “cut grass” below) is discharged from the cut grass discharge chute  11  of the cutting blade housing  13  by the draft that is generated when rotating the cutting blades  14 , and is carried through the duct  30  and between the left and rear wheels  2  in longitudinal direction of the vehicle body to the grass container  20 . The grass container  20  collects and retains the cut grass from the duct  30 . 
   As shown in  FIG. 4 , the grass container  20  includes a wall member  21  shaped as a vertical plate extending along the vehicle body&#39;s vertical direction when viewed from the side of the vehicle body, and a main container member  22  that is arranged behind this wall member  21 . The wall member  21  is rectangular when viewed from the front or the rear of the vehicle body, and is supported at the rear end of the vehicle frame  5  through a support frame  5   a  that extends from the vehicle frame  5  to the rear. 
   The main container member  22  has a box shape that is given by a container frame  23  made of round pipe members, a pair of left and right wall covers  24  linked to this container frame  23 , a bottom plate, a top plate and a rear wall plate. An aperture  25  formed by the container frame  23  is provided on the front end side of the main container member  22 . 
   A pair of left and right supporting arms  27  extend in rearward direction from the wall member  21  into the inside of the main container member  22 . A pair of left and right mounting brackets  26  provided inside the main container member  22  is linked rotatively to the end of the left and right supporting arms  27  such that the mounting brackets  26  can be individually attached or removed. The main container member  22  is supported by the wall member  21  such that it can be opened and closed vertically in a pivoting motion with respect to the wall member  21  around an axis X extending in lateral direction of the vehicle body positioned at the front ends of the supporting arms  27 , as shown in  FIG. 3(A) , and such that it can be lodged and dislodged with the mounting brackets  26  and the supporting arms  27 , as shown in  FIG. 3(B) . 
   As shown in  FIGS. 4 and 5 , the rear end of the duct  30  is positioned at a duct hole A of the wall member  21 , and the opening on the rear end side of the duct  30  forms a cut grass inlet port  32  of the grass container  20 . 
   That is to say, when performing a grass cutting operation, the main container member  22  is pivoted downward around the axis X with a handle  45  that is fastened to the top plate of the main container member  22  of the grass container  20  and a handle  46  protruding upward from the top plate of the main container member  22 , into a position in which the aperture  25  of the main container member  22  points in frontward direction and is shut by the wall member  21 , and the grass container  20  is in a shut position for collecting grass. When the grass container  20  is in a shut position for collecting grass, shutter hooks  28  (see  FIG. 4 ) arranged such that they are vertically pivotable at the left and right ends on the lower side of the wall member  21  interlock with the container frame  23 , so that the grass container  20  is locked in the shut position for collecting grass, and the task of cutting grass is carried out in this position. In this situation, the cut grass is carried from the cut grass discharge chute  11  of the grass cutter  10  at the front end of the duct  30  rearward due to the draft from the grass cutter  10 . At the rear end of the duct  30 , the cut grass is fed from the grass inlet port  32  into the grass container  20 , where the cut grass is collected and retained by the wall member  21  and the main container member  22 , while the draft that has entered the grass container  20  from the duct  30  together with the cut grass is evacuated out of the grass container through evacuation holes provided in the lateral side covers  24 . 
   When the grass container  20  is full, an operation rod  29  (see  FIG. 4 ) operatively linked to one of the pair of left and right shutter hooks  28  is lifted, thus switching the shutter hook  28  to which the operation rod  29  is linked to an unlocked position in which it is dislodged from the container frame  23 . Since the two left and right shutter hooks  28  are operatively linked by a rotation shaft  28   a , also the other shutter hook  28  is switched to the unlocked state, so that the grass container  20  which has been locked shut by the shutter hooks  28  is released, and through operating the handles  45  and  46 , the main container member  22  is pivoted upward around the axis X, and the aperture  25  of the main container member  22  is removed to the rear from the wall member  21 , to a raised and open state in which the aperture  25  is open in downward direction. Thus, the grass container  20  is put into an open discharge state, in which the cut grass retained in the grass container can be discharged by letting it fall down from the aperture  25  of the main container member  22 . 
   As shown in  FIGS. 5 and 7  for example, a lid  40  made of sheet metal for a portion A 1  of the duct hole A of the wall member  21  that is positioned below the duct  30  in the vertical direction of the grass container is provided to the side on the rear (with respect to the vehicle body) of the wall member  21 , that is, to the side inside the grass container. The lid  40  is configured such that it can be shut and closed by pivoting it around an axis Y extending in vertical direction of the grass container and positioned on one side in lateral direction of the grass container. This lid  40  is provided with a fill detection device  50  provided with a pivot sensor  52  and a detection switch  51 . 
   When the cut grass collected in the grass container  20  reaches a preset amount, such as when the grass container  20  is full, the fill detection device  50  detects this and the detection switch  51  outputs the detection result, activating an alarm (not shown in the drawings) at the driver section. This is explained in detail in the following. 
   As shown in  FIGS. 6 and 7 , the fill detection device  50  includes the pivot sensor  52 , the detection switch  51  and a coil-shaped spring  61 . The pivot sensor is rotatively linked at a mounting base portion  52   a  via a support shaft  53  to a support plate portion  42  of a detector mounting member  41  supported on the rear side of the lid  40 . The detection switch  51  is supported by the support plate portion  42 . The coil-shaped spring  61  is operatively linked to a spring support arm  52   d  extending from the mounting base portion  52   a  of the pivot sensor  52 . 
   The pivot sensor  52  is provided with a pressure-sensing portion  52   c  extending from the mounting base portion  52   a  through a sensor hole  43  in the lid  40  into the grass container  20 . The pressure-sensing portion  52   c  is positioned nearly below the cut grass inlet port  32  and has a first pressure-sensing surface  54  and a second pressure-sensing surface  55 . The pivot sensor  52  is a plastic sensor, in which the mounting base portion  52   a , a switch actuating portion  52   b , the pressure-sensing portion  52   c  and the spring support arm  52   d  have been formed into one component from a resinous raw material. The pressure-sensing portion  52   c  of the pivot sensor  52  is made in such a manner that, when viewed in the direction in which the axis Z of the support shaft  53  extends, the first pressure-sensing surface  54  and the second pressure-sensing surface  55  are arranged perpendicularly or substantially perpendicularly to one another, and the rod-shaped member  54   a  of the first pressure-sensing surface  54  and the rod-shaped member  55   a  of the second pressure-sensing surface  55  are linked in a perpendicular arrangement. 
   That is to say, the pivot sensor  52  is supported in such a state that the pressure-sensing portion  52   c  pivots vertically around the axis Z of the support shaft  53 , which extends laterally in the grass container, inside the grass container  20 . When the cut grass inside the grass container  20  does not exert pressure on the pressure-sensing portion  52   c  of the pivot sensor  52 , then the pivot sensor  52  is in a raised non-detecting posture, in which, due to the combined effect of the spring force and/or the weight of the spring  61  and the weight of the pivot sensor  52 , the spring support arms  52   d  of the pivot sensor  52  abut against a stopper  56 . When the pivot sensor  52  is in the raised non-detecting posture, the first pressure-sensing surface  54  of the pivot sensor  52  becomes an upward-facing surface with respect to the vertical direction of the grass container, and the second pressure-sensing surface  55  of the pivot sensor  52  becomes a lateral surface with respect to the rear direction of the vehicle body when viewed in the direction in which the sensor pivot axis Z extends. In this state, the switch actuating portion  52   b  of the pivot sensor  52  is removed from an actuating portion  51   a  of the detection switch  51 , and the detection switch  51  is in the off position. When the cut grass inside the grass container  20  exerts pressure on the pressure-sensing portion  52   c  of the pivot sensor  52 , then the pressure-sensing portion  52   c  of the pivot sensor  52  pivots downward due to this pressure, and the switch actuating portion  52   b  tilts forward around the axis Z. Then, when the pressure due to the cut grass reaches the preset pressure, the pivot sensor  52  assumes a lowered detection posture, in which the switch operation portion  52   b  abuts against the actuating portion  51   a  of the detection switch  51 . When the pivot sensor  52  has assumed the lowered detection posture, the detection switch  51  is switched on by the switch actuating portion  52   b.    
   As shown in  FIG. 6 , a sensitivity adjusting means  60  for adjusting the sensitivity of the pivot sensor  52  is provided, including the spring  61  which is operatively linked to the pivot sensor  52 , and a sensitivity adjusting member  62  also serving as a spring support rod, whose one end is linked to the side opposite the side where the spring  61  is linked to the pivot sensor  52 . 
   As shown in  FIGS. 6 and 7 , the base end side of the sensitivity adjusting member  62  is supported rotatively by a support shaft  64  made of a bolt that is mounted to the fixed bracket  63  that is fixed with respect to the detector mounting member  41 . The front end side of the sensitivity adjusting member  62  is supported by an adjustment guide member  65  that is fixed with respect to the detector mounting member  41 . Raising and lowering an operating portion  66  that also serves as a spring latch provided in the middle of the sensitivity adjusting member  62 , the front end of the sensitivity adjusting member  62  can be raised or lowered along a guide groove  67  in vertical direction (with respect to the grass container) of the adjusting guide member  65 , with the sensitivity adjustment member  62  pivoting around the support shaft  64 , as shown in  FIG. 8 . When the sensitivity adjusting member  62  is raised to the upper side of the guide groove  67 , and held in position by being placed in the positioning groove portion  68   a  of the adjusting guide member  65  connected to the guide groove  67 , then the sensitivity adjusting member  62  is held while being placed in a high-sensitivity position B, and the spring  61  is loosened so much that it is in a free state while the pivot sensor  52  is in the raised non-detecting position. When the sensitivity adjusting member  62  is lowered to the lower side of the guide groove  67 , and held in position by being placed in the positioning groove portion  68   b  of the adjusting guide member  65  connected to the guide groove  67 , then the sensitivity adjusting member  62  is held while being placed in a low-sensitivity position C, and the spring  61  is tightened so that the spring  61  is elastically deformed, as the pivot sensor  52  is lowered from the raised non-detecting position. 
   Thus, when the sensitivity adjusting member  62  is placed in the high-sensitivity position B, the sensitivity adjusting means  60  adjusts the sensitivity with respect to the pressure exerted on the pivot sensor  52  by the cut grass to a high sensitivity, so that the spring  61  is substantially not deformed elastically even when the pivot sensor  52  pivots down, there is hardly any resistance by the spring  61  against a downward pivoting of the spring sensor  52 , and the pivot sensor  52  reacts to a comparatively light pressure of cut grass. On the other hand, when the sensitivity adjusting member  62  is placed in the low-sensitivity position C, the sensitivity adjusting means  60  adjusts the sensitivity with respect to the pressure exerted on the pivot sensor  52  by the cut grass to a low sensitivity, so that the spring  61  is elastically deformed as the pivot sensor  52  pivots down, there is resistance by the spring  61  against a downward pivoting of the spring sensor  52 , and the pivot sensor  52  does not react to a comparatively light pressure. 
   As shown in  FIG. 7 , a setting height adjustment means  70  for adjusting the setting height of the pivot sensor  52  is configured by a coupling screw  71  for tightening the detector supporting member  41  to the lid  40 , and a bolt hole  72  provided in the detector supporting member  41  such that the coupling screw  71  can be screwed into it. 
   That is to say, the bolt hole  72  is a elongate hole extending in the vertical direction of the grass container  20 . The detector mounting member  41  can be raised and lowered with respect to the lid  40  along the bolt hole  72  and the elongate hole-shaped screw holes  40   a  of the lid  40 , thus raising and lowering the pivot sensor  52  with respect to the lid  40  along the elongate hole-shaped sensor hole  43  of the lid  40 . By raising and lowering the pivot sensor  52  together with the detection switch  51  and the sensitivity adjustment means  60  with respect to the lid  40 , the setting height adjustment means  70  changes the vertical position of the pivot sensor  52  with respect to the grass collector  20  and also changes the position of the detection switch  51  and the sensitivity adjustment means  60  together with the pivot sensor  52 . 
   Thus, the fill detection device  50  operates as follows: 
   When the cut grass is light, for example because it is dry, then the cut grass that is fed into the grass container  20  falls down while being spread as it comes flying into the grass container, and tends to accumulate at a substantially uniform accumulation height over the entire area of the container, as shown in  FIG. 9(A) . In this case, the cut grass that accumulates above the pivot sensor  52  exerts a pressure on the first pressure-sensing surface  54  of the pivot sensor  52 . That is to say, the pivot sensor  52  receives the pressure exerted by the cut grass from above the pivot sensor  52 , with respect to the grass container. Thus, even when the accumulation height of the grass above the pivot sensor  52  is low and the weight of the cut grass exerting pressure on the pivot sensor  52  is comparatively low, the pivot sensor  52  is pivoted down efficiently by the cut grass, given the weight of that cut grass. Therefore, as the cut grass accumulates in the grass container  20 , before the accumulation amount of the cut grass becomes very different from the set amount that depends on the height at which the pivot sensor  52  is arranged, and before the cut grass accumulates near the cut grass inlet port  32 , the detection switch  51  is turned on by lowering the pivot sensor  52  to the lowered detection posture, and the detection switch  51  detects the pivoting of the pivot sensor  52  to the lowered detection posture. Thus, the detection switch  51  detects when the amount of retained cut grass has reached the set amount, and outputs this detection result as an electrical signal. 
   On the other hand, if the cut grass is heavy, for example because it is wet, then the cut grass that is fed into the grass container  20  falls down without being spread in the grass container, and tends to accumulate with an accumulation height that is higher at locations further removed from the cut grass inlet port  32  than at locations close to the cut grass inlet port  32 , as shown in  FIG. 9(B) . In this case, even with hardly any cut grass accumulating above the pivot sensor  52 , the cut grass accumulating to the side of the pivot sensor  52  when viewed in the sensor pivot axis direction exerts a pressure on the second pressure-sensing surface  55  of the pivot sensor  52 . That is to say, the pivot sensor  52  receives the pressure exerted by the cut grass from the side of the sensor. Thus, as the cut grass accumulates in the grass container  20 , before the accumulation amount of the cut grass becomes very different from the set amount that depends on the height at which the pivot sensor  52  is arranged, and before the cut grass accumulates near the cut grass inlet port  32 , the detection switch  51  is turned on by lowering the pivot sensor  52  to the lowered detection posture, and the detection switch  51  detects the pivoting of the pivot sensor  52  to the lowered detection posture. Thus, the detection switch  51  detects when the amount of retained grass has reached the set amount, and outputs this detection result as an electrical signal. 
   Also, in the case of light cut grass, as well as in the case of heavy cut grass that is long and accumulates in a state of reduced density, the pressure exerted on the pivot sensor  52  is light for the accumulated amount, the pivot sensor  52  can be adjusted with the setting height adjustment means  70  to the lower side with respect to the grass container  20 , whereas in the case of heavy cut grass, the pivot sensor  52  can be adjusted with the setting height adjustment means  70  to the upper side with respect to the grass container  20 . Thus, the detection switch  51  can be adjusted such that the accumulation height of the cut grass during detection operation is the same or substantially the same for light cut grass and for heavy cut grass. Furthermore, even when there is no change in the weight of the cut grass, by adjusting the height of the pivot sensor  52  with respect to the grass container  20  with the setting height adjustment means  70 , it is possible to adjust the detection switch  51  such that the accumulation height of the cut grass during the detection operation is lower than before the adjustment operation, or to adjust the detection switch  51  such that the accumulation height of the cut grass during the detection operation is higher than before the adjustment operation. 
   Furthermore, for example in the case of light cut grass as well as in the case of heavy cut grass that is long and accumulates in a state of reduced density, so that the pressure exerted by the cut grass on the pivot sensor  52  is light for the accumulated amount, the pressure exerted by the cut grass on the pivot sensor  52  is lower and the pivot sensor  52  is less easily pivoted downward than in the case of heavy cut grass, even if a large amount of cut grass has accumulated. Conversely, in the case of heavy cut grass, the pressure exerted by the cut grass on the pivot sensor  52  is higher and the pivot sensor  52  is more easily pivoted downward than in the case of light cut grass, even if only a small amount of cut grass is accumulated. Therefore, in the case of light cut grass, the sensitivity with respect to the pressure exerted by the cut grass on the pivot sensor  52  is set to a high sensitivity with the sensitivity adjustment means  60 , thus allowing an adjustment where, if the retention amount of cut grass reaches the set amount or substantially the set amount, the pivot sensor  52  is sufficiently pivoted downward by the pressure exerted on it by the cut grass, and the detection switch is actuated. And in the case of heavy cut grass, the sensitivity with respect to the pressure exerted by the cut grass on the pivot sensor  52  is set to a low sensitivity with the sensitivity adjustment means  60 , thus allowing an adjustment where, if the retention amount of cut grass does not reach the set amount or substantially the set amount, the pivot sensor  52  is not sufficiently pivoted downward even when pressure is exerted on it by the cut grass, and the detection switch  51  is not actuated. 
   As shown in  FIGS. 4 and 10 , a grip portion  46   a  of the handle  46  is linked in a removable fashion with a threaded portion  46   c  to a tubular member  46   b  of the handle  46  that is fixed inside the main container member  22 . The grip portion  46   a  is furthermore linked to a cleaning rod  47  that can be inserted into the tubular member  46   b.    
   During operation, this cleaning rod  47  can be stowed away within the tubular member  46   b  of the handle  46 , so that it will not be displaced or forgotten, and when the need arises to clean the cut grass adhering to the inside of the grass container  20 , the cleaning rod  47  can be removed from the tubular member  46   b  of the handle  46   a  for use. 
     FIG. 11  shows a grass cutter  10  of a lawn mower according to another embodiment. In this grass cutter  10 , a guide bottom plate  16  arranged in the cut grass discharge chute  11  of the cutting blade housing  13  in such a manner that it guides the cut grass to the duct  30  is supported vertically pivotably on the cutting blade housing  13  by a rotation support shaft  17  positioned at the rear end side of the guide bottom plate  16 . The guide bottom plate  16  is biased toward a lowered guide posture by a return spring  19  that is operatively coupled to an operation arm  18  linked to one end of the rotation support shaft  17  such that the operation arm  18  and the rotation support shaft  17  can be rotated together. 
   When cut grass has jammed or adhered in the cut grass discharge chute  11  of the cutting blade housing  13 , the main container member  22  of the grass container  20  is removed, the duct  30  is removed, and the guide bottom plate  16  can be pivoted up and down around the axis of the rotation support shaft  17  by moving an operation rod  18   a  extending in the vehicle body&#39;s rearward direction from the operation arm  18  back and forth. Thus, the guide bottom plate  16  serves as a cleaning means, and jammed or adhering cut grass can be cleaned by discharging it from the cut grass discharge chute  11  in rearward direction. 
   Other Embodiments 
   Instead of a detection switch  51 , it is also possible to attain the object of the present invention by configuring the fill detection device  50  with a potentiometer or the like. The detection switch  51  and the potentiometer or the like are collectively referred to as “detection means  51 .”