Patent Publication Number: US-2021185910-A1

Title: Grass mower

Description:
INCORPORATION BY REFERENCE 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2019-229377 6 filed on Dec. 19, 2019. The content of the application is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of Invention 
     The present invention relates to a grass mower. 
     Description of the Related Art 
     In recent years, working machines such as lawn mowers or grass mowers have been known in which a plurality of mowing blades are attached to a mowing blade disk that is driven by a motor and rotates substantially horizontally. 
     As such working machines, autonomous traveling working machines capable of autonomously traveling, namely robot working machines have been developed. 
     Such a working machine includes, for example, an output shaft driven by a motor, a mowing blade disk attached to the output shaft, and a plurality of mowing blades formed on the outer peripheral edge of the mowing blade disk, and drives a motor to rotationally drive a mowing blade disk via the output shaft, thereby rotating the mowing blades and mowing grass or lawn (see, for example, Japanese Patent Laid-Open No. 2016-135099). 
     However, although the technique in Japanese Patent Laid-Open No. 2016-185099 does not cause much problem in cases of mowing a short grass, for example, the technique has a problem in cases of mowing long grass, in which the rotational load of mowing blade disk increases when a mowing blade hits long grass, and the rotational load further increases if long grass wind around the output shaft of the motor. 
     In such a case, it is possible to increase the size of the motor to increase the output to cope with mowing long grass, but this increases the size of the working machine itself. 
     Further, when a load due to mowing of long grass is detected, it is also possible to lower the traveling speed of the working machine to cope with it, but it is not possible to prevent the grass from winding around the output shaft of the motor. 
     The present invention has been made in view of the above-mentioned point, and an object of the present invention is to provide a grass mower which can easily mow long grass. 
     SUMMARY OF THE INVENTION 
     In order to achieve the above object, a grass mower according to a first aspect of the present invention includes: a main body; a drive source mounted on the main body; an output shaft that projects downward from the drive source and that is rotated by the drive source; a mowing blade disk mounted to the output shaft; and an upper guard provided to cover the output shaft, the output shaft being between the mowing blade disk and the main body, wherein the upper guard includes a cutout portion for exposing the mowing blade disk at a rear end in the traveling direction of the main body. 
     A grass mower according to a second aspect of the present invention has the above configuration, wherein: the upper guard includes an engagement portion to be engaged with a housing on a first side of the upper guard, the housing supporting the drive source; and the upper guard is engaged with and fixed to the housing at the engagement portion, and is bolt-fixed to the housing on a second side of the upper guard. 
     A grass mower according to a third aspect of the present invention has the above configuration, wherein the mowing blade disk includes a plurality of mowing blades on the outer periphery of the mowing blade disk. 
     A grass mower according to a fourth aspect of the present invention has the above configuration, wherein the front end of the upper guard in the traveling direction of the main body is located rearward of the mowing blades. 
     A grass mower according to a fifth aspect of the present Invention has the above configuration, wherein: each of the mowing blades is rotatably attached to an attachment pin provided on the mowing blade disk; and the upper guard includes a guard portion that avoids the attachment pin. 
     Advantageous Effects of Invention 
     According to an aspect of the present invention, the upper guard is provided to guide the grass mown by the mowing blade disk, toward the upside of the upper guard, and this can prevent the mown grass from entering between the mowing blade disk and the output shaft, and can prevent the grass from winding around the output shaft. Further, since the cutout portion exposes the rear portion of the mowing blade disk, the mown grass can be efficiently discharged rearward. As a result, even in a case of mowing high or long grass, it is possible to prevent increase of the load to the mowing blade disk, and to mow long grass without increasing the output of the drive source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram showing an embodiment of a grass mower according to the present invention; 
         FIG. 2  is a cross-sectional view showing a working unit of this embodiment; 
         FIG. 3  is a plan view showing a working unit of this embodiment; 
         FIG. 4  is a plan view showing an upper guard of this embodiment; and 
         FIG. 5  is an explanatory diagram showing a state when mowing is performed according to this embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the drawings. 
       FIG. 1  is a schematic configuration diagram showing an embodiment of a grass mower according to the present invention. 
     The grass mower according to this embodiment is, for example, an autonomous traveling grass mower that mows grass while autonomously traveling in a predetermined mowing area partitioned by an area wire which is a wire for detecting a boundary. 
     The grass mower  1  includes a main body  10  having a traveling function and the like, and a vehicle body cover  11  that covers the main body  10 . Left and right front wheels  12  that can be steered to the left and right are provided at the lower front portion of the main body  10 , left and right rear wheels  13  functioning as drive wheels are provided at the lower rear portion of the main body  10 , and a working unit  14  is provided at the lower center portion of the main body  10 . In addition, a terminal unit  15  that is electrically connected to a charging station (not shown) is provided on the front portion of the grass mower  1 . 
     The main body  10  is also an electric and electronic unit including: left and right traveling motors  20  that individually drive the left and right rear wheels  13 ; a working unit driving motor  21  as a drive source for driving the working unit  14 ; a battery  22  that functions as a power supply for supplying operation power to each unit of the grass mower  1 ; a wheel speed sensor  23  for detecting the rotational speeds of the left and right rear wheels  13  which are driving wheels; a sensor unit  24  for detecting the area wire and the like to detect a position of the grass mower  1 ; and a control unit  25  that controls each unit of the grass mower  1 . 
     The control unit  25  has a CPU (Central Processing Unit) (not illustrated) and a memory (not illustrated) that stores programs and various data. By executing, by the CPU, the programs stored in the memory, the control unit  25  controls the driving of the traveling motor  20  to control the traveling of the grass mower  1 , and controls the driving of the working unit driving motor  21  to perform the predetermined work. The working unit  14  of this embodiment, is a mowing blade disk  31  provided with a mowing blade  30 , and the mowing blade disk  31  is rotationally driven to perform mowing work. 
     The control unit  25  identifies the position of the grass mower  1  based on the detection results of the wheel speed sensor  23  and the sensor unit  24 , and controls the traveling of the grass mower  1  based on the identified position. This allows the grass mower  1  to travel to appropriately mow the grass in the grass mowing area  4 , and to move to the charging station after finishing the mowing work. 
     Here, for the configuration of the main body  10  excluding the terminal unit  15 , configurations of known robot grass mowers can be widely applied. For example, for the technique to identify the grass mowing area, charging station, current position, and the like, a magnetic sensor for detecting the area wire may be applied as the sensor unit  24 , a position detection device such as GPS or a gyro sensor may be applied as the sensor unit  24 , and an image recognition technique using a camera, or the like may be applied. 
     The vehicle body cover  11  includes a main cover  16  that covers at least the front portion of the main body  10 , and a top cover  17  that is connected to the main cover  56  from above. The main cover  56  is formed as a cover that covers the front, rear, left, and right of the main body  20  and opens a part of the main body  10  upward, and is made of a resin material. Further, the top cover  17  is formed as a cover that covers a region of the main cover  16  in which a part of the main body  10  is opened, and is made of a resin material. These covers  16  and  17  function as a protective cover that prevents rainwater, dust, or the like from adhering to the main body  10  and a decorative cover that improves appearance. 
     Note that the vehicle body cover  11  is not limited to being made of resin. Further, when the grass mower  1  has a small size, the main cover  16  and the top cover  17  may be integrally formed. 
       FIG. 2  is a schematic cross-sectional view showing details of the working unit.  FIG. 3  is a plan view of the working unit.  FIG. 4  is a plan view of an upper guard. 
     As shown in  FIG. 2 , the main body  10  includes a motor housing  32  in which the working unit driving motor  21  is housed. The motor housing  32  is disposed so as to be inclined with respect to the main body  10  so that the front is located below. 
     A motor support portion  33 , which supports the lower surface of the working unit driving motor  21 , is provided at the lower end portion of the motor housing  32 . A shaft opening  34 , through which an output shaft  26  of the working unit driving motor  21  penetrates, is provided at a substantially central portion of the motor support portion  33 , A support flange  35  is formed on the outer peripheral side of the lower end of the motor support portion  33  so as to extend outward. 
     The working unit driving motor  21  is supported by the motor housing  32 , and the output shaft  26  of the working unit driving motor  21  projects below the motor housing  32  through the shaft opening  34 . The mowing blade disk  31  is mounted to the lower end portion of the output shaft  26 . 
     Attachment pins  36  projecting upward are provided near, the outer periphery of the mowing blade disk  31 . The attachment pins  36  are provided at three locations in the circumferential direction of the mowing blade disk  31  at predetermined intervals. 
     One end portion of the mowing blade  30  is rotatably attached to each attachment pin  36 . 
     Then, the working unit driving motor  21  is driven to rotationally drive the mowing blade disk  31  via the output shaft  26 . This causes the mowing blades  30  to rotationally move about the attachment pins  36  and to be kept projecting to the outer peripheral side of the mowing blade disk  31  due to the centrifugal force of the mowing blade disk  31 . This then causes the mowing blades  30  to mow the grass. 
     Further, as shown in  FIGS. 2 and 3 , in this embodiment, an upper guard  40  located above the mowing blade disk  31  is attached to the lower end of the motor housing  32 . 
     As shown in  FIGS. 2 to 4 , the front side of the upper guard  40  with respect to the main body  10  is formed in an arc shape along the outer shape of the mowing blade disk  31 , and both sides of the upper guard  40  are linearly formed so as to extend in the front-rear direction of the main body  10 . 
     The rear end of the upper guard  40  has a cutout portion  41  formed substantially to the middle in the radial direction of the mowing blade disk  31 , so that the rear of the mowing blade disk  31  is exposed. As a result, a part of the rear of the mowing blade disk  31  is not covered by the upper guard  40  and is kept exposed to the outside. The upper guard  40  is formed in a substantially U shape in plan view as a whole. 
     A guard portion  42  is formed on the outer peripheral side of the upper guard  40 . The guard portion  42  has a shape that bulges upward to avoid the attachment pins  36  of the rotating mowing blade disk  31 . 
     A flat plate portion  43  is formed inside the guard portion  42  of the upper guard  40 , and a recessed cutout portion  44  is formed in the flat plate portion  43  to avoid the output shaft  26  of the working unit driving motor  21 . 
     Engagement cutouts  40 , which engage with the support flange  35  of the motor housing  32 , are formed at the inner corners between the cutout portion  41  and the recessed cutout portion  44  of the upper guard  40 . 
     Further, a fixing hole  47  for inserting a fixing bolt  46  for fixing the upper guard  40  to the motor housing  32  is formed on the front side of the upper guard  40  and at the boundary portion between the guard portion  42  and the flat plate portion  43 . 
     Further, in this embodiment, the front end portion of the guard portion  42  is positioned rearward in the front-rear direction by several mm to several tens of mm, from the position where each of the mowing blades  30  projects most forward. Further, the guard portion  42  is positioned such that the gap between the front end portion and the mowing blades  30  is several mm to several tens mm in the up-down direction. If the gap between the front end portion and the mowing blades  30  is too small, the grass may clog the gap between the mowing blade disk  31  and the upper guard  40 . 
     The front-rear direction position and the up-down direction position of the guard portion  42  with respect to each of the mowing blades  30  are not limited to the above-described dimensions, and can be appropriately adjusted according to the thickness or length of the grass to be mown. 
     The upper guard  40  is engaged with the support flange  35  of the motor housing  32  at the engagement cutout  45 , and then is fixed to the lower end of the motor housing  32  with the fixing bolt  46 , which is inserted into the fixing hole  47 , and the fixing nut  48 , which are tightened together. In this way, it is possible that the upper guard  40  is engaged at its engagement cutout  45  with the support flange  35  of the motor housing  32  and is fixed with the fixing bolt  46 , to be easily attached to the motor housing  32 . 
     Next, how this embodiment works is described below. 
     In mowing grass, the working unit driving motor  21  is first driven to rotationally drive the mowing blade disk  31  via the output shaft  26 . This causes the mowing blades  30  to rotationally move about the attachment pins  36  and to be kept projecting to the outer peripheral side of the mowing blade disk  31  due to the centrifugal force of the mowing blade disk  31 . This then causes the mowing blades  30  to mow the grass. 
       FIG. 5  is an explanatory diagram that shows a state where mowing is performed. 
     As shown in  FIG. 5 , since the upper guard  40  is provided above the mowing blade disk  31 , the grass mown by the mowing blades  30  is conveyed to the upper side of the guard portion  42  of the upper guard  40 . The mown grass is thus conveyed above the upper guard  40 , so that the mown grass does not enter between the mowing blade disk  31  and the upper guard  40 . 
     The grass guided to the upper side of the upper guard  40  is sequentially conveyed to the rear of the upper guard  40  and dropped downward from the rear end of the upper guard  40  when the working machine continues to travel to mow. 
     At this time, since the mowing blade disk  31  is exposed at the rear end, the mown grass can be easily discharged. Further, since the upper guard  40  is formed so as to cover the output shaft  26  part, it is possible to prevent grass from entering the output shaft  26  part and causing problems such as grass winding. 
     As described above, in this embodiment, a grass mower includes: a main body  10 ; a working unit driving motor  21  (drive source) mounted on the main body  10 ; an output shaft  26  that projects downward from the working unit driving motor  21  and is rotated by the working unit driving motor  21 ; a mowing blade disk  31  mounted to the output shaft  26 ; and an upper guard  40  provided to cover the output shaft  26 , the output shaft  26  being between the mowing blade disk  31  and the main body  10 , wherein the upper guard  40  includes a cutout portion  41  for exposing the mowing blade disk  31  at a rear end in the traveling direction of the main body  10 . 
     Accordingly, the upper guard  40  is provided to guide the grass mown by the mowing blades  30  of mowing blade disk  31 , toward the upside of the upper guard  40 , and this can prevent the mown grass from entering between the mowing blade disk  31  and the output shaft  26 , and can prevent the grass from winding around the output shaft  26 . Further, since the cutout portion  41  exposes the rear portion of the mowing blade disk  31 , the mown grass can be efficiently discharged rearward. 
     As a result, even in a case of mowing high or long grass, it is possible to prevent increase of the load to the mowing blade disk  31 , and to mow long grass without increasing the output of the working unit driving motor  21 . 
     Further, in this embodiment, the upper guard  40  includes an engagement cutout  45  (engagement portion) on a first side, to be engaged with a motor housing  32  (housing) that supports the working unit driving motor  21  (drive source), and the upper guard  40  is engaged with and fixed to the motor housing  32  at the engagement cutout  45  and is bolt-fixed to the motor housing  32  by a fixing bolt  46  on a second side of the upper guard  40 . 
     As a result, engaging the engagement cutout  45  with the motor housing  32 , and bolt-fixing by the fixing bolt  46  enables the upper guard  40  to be easily attached to the motor housing  32 . 
     Further, in this embodiment, the mowing blade disk  31  includes a plurality of mowing blades  30  on its outer periphery. 
     This makes it possible to mow the grass with the mowing blades  30  provided on the mowing blade disk  31 . 
     Further, in this embodiment, the front end of the upper guard  40  in the traveling direction of the main body  10  is located rearward of the mowing blades  30 . 
     As a result, the mown grass can be guided toward the upside of the upper guard  40 . 
     Further, in this embodiment, each of the mowing blades  30  is rotatably attached to an attachment pin  36  provided on the mowing blade disk  31 , and the upper guard  40  includes a guard portion  42  that avoids the attachment pins  36 . 
     Accordingly, long grass can be mown without hindering the rotating operation of the mowing blades  30 . 
     The above embodiment is merely an embodiment of the present invention, and can be modified and applied in any way without departing from the scope of the present invention. 
     For example, in the above-described embodiment, a grass mower that mows relatively long grass has been described, but the present invention is not limited to this, and can be applied as a lawn mower that mows relatively short grass (lawn). 
     REFERENCE SIGNS LIST 
       1  grass mower 
       10  main body 
       11  vehicle body cover 
       12  front wheel 
       13  rear wheel 
       14  working unit 
       21  working unit driving motor 
       26  output shaft 
       30  mowing blade 
       31  mowing blade disk 
       32  motor housing 
       35  support flange 
       36  attachment pin 
       40  upper guard 
       41  cutout portion 
       42  guard portion 
       43  flat plate portion 
       44  recessed cutout portion