Patent Publication Number: US-2021168998-A1

Title: Lawn mower

Description:
CROSS-REFERENCE TO RELATED INVENTIONS 
     This application is based upon and claims the benefit of priority from the prior Chinese Patent Application No. 201911224475.8, filed on Dec. 4, 2019, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The invention relates to a lawn mower, and in particular to the technical field of garden tools. 
     BACKGROUND ART 
     In order to increase cutting width, the blade of the lawn mower is also changed from a single blade to dual blades, which greatly increases the cutting width of the lawn mower and meets the higher requirements of consumers. 
     During the mowing process, obstacles such as stones often appear on the lawn. When the blade rotates at high speed and hits the obstacle, the counterforce of the obstacle will cause the blade to stop and the counterforce will pass through the blade connecting shaft to the plastic gear. At this time, the motor is still running, and the momentary torque is very large, which will cause the gears to collide with each other, causing the gears to damage and the lawn mower can&#39;t work normally. 
     In view of the foregoing problems, it is an object of the present invention to provide an improved lawn mower which can prevent an impact load from transmitting to the output shaft. 
     SUMMARY OF INVENTION 
     The object of the present invention is to provide a lawn mower, which has an impact protection function. 
     In order to achieve the above object, the present invention provides a lawn mower, which comprises a driving assembly, an impact protection assembly, a transmission assembly, and a cutting assembly. The impact protection assembly comprises a first bearing seat, a second bearing seat that is mated with the first bearing seat, and an elastic member and a ball that are disposed between the first bearing seat and the second bearing seat. The first bearing seat is provided with a protrusion. When the driving assembly is driven, the ball is pushed by the elastic member to contact with the protrusion of the first bearing seat to drive the transmission assembly and the cutting assembly to rotate synchronously. When the resistance received by the cutting assembly is greater than a preset value, the elastic member is continuously compressed and the ball passes over the protrusion, and a relative rotation between the transmission assembly and the driving assembly occurs. 
     As a further improvement of the present invention, the first bearing seat is further provided with a sliding groove for receiving the ball, and the sliding groove is annularly arranged and passes over the protrusion. 
     As a further improvement of the present invention, the driving assembly comprises a motor and a motor shaft, one end of the motor shaft is inserted into the first bearing seat, and a flat key is received in the first bearing seat so the motor shaft transmits the torque to the first bearing seat through the flat key. 
     As a further improvement of the present invention, the second bearing seat comprises a boss, and the elastic member and the ball are received in the boss, and when the second bearing seat is sleeved on the first bearing seat, the ball is in contact with the first bearing seat, and the elastic member is disposed between the boss and the ball. 
     As a further improvement of the present invention, the impact protection assembly further comprises a driving shaft connecting the transmission assembly and the cutting assembly, and a unilateral bearing sleeved on the driving shaft, when the driving assembly being driving, the transmission assembly driving the driving shaft, the unilateral bearing and the cutting assembly to rotate synchronously, when the resistance received by the cutting assembly being greater than a preset value, the unilateral bearing locking the driving shaft. 
     As a further improvement of the present invention, the transmission assembly comprises a first gear connected to the second bearing seat and a second gear meshed with the first gear, and the cutting assembly comprises a first blade assembly connected to the second gear, and the driving shaft and the unilateral bearing are connected between the second gear and the first blade assembly. 
     As a further improvement of the present invention, the transmission assembly further comprises a third gear and a fourth gear, the third gear meshes with the first gear and the fourth gear, respectively, and the cutting assembly further comprises a second blade assembly connected to the fourth gear, and the driving shaft and the unilateral bearing are also connected between the fourth gear and the second blade assembly. 
     As a further improvement of the present invention, the centers of the first gear, the second gear, the third gear, and the fourth gear are located on the same line, and the first blade assembly and the second blade assembly are perpendicular to each other and rotate in opposite directions in the same plane. 
     As a further improvement of the present invention, the transmission assembly further comprises a gear box formed with an accommodating space and a cover plate for covering the accommodating space, the gear box comprising a bottom wall, an annular side wall protruding upward from the bottom wall, and two protruding portions protruding downward from opposite ends of the bottom wall, the accommodating space being formed between the bottom wall and the annular side wall, the driving assembly being fixed on the cover plate, the two driving shafts respectively protruding downward beyond the corresponding protruding portion. 
     As a further improvement of the present invention, the first gear, the second gear, the third gear, and the fourth gear are received in the accommodating space, and the second gear and the third gear are disposed on opposite sides of the first gear, and the fourth gear is disposed away from the first gear. 
     The beneficial effect of the present invention is that the lawn mower of the present invention is provided with an elastic member and a ball between the first bearing seat and the second bearing seat, and at the same time, a protrusion is provided on the first bearing seat, so that when the driving assembly drives, the ball is pushed by the elastic member to contact with the protrusion of the first bearing seat, and the transmission assembly and the cutting assembly can be driven to rotate synchronously. When the resistance received by the cutting assembly is greater than a preset value, the elastic member is continuously compressed and the ball passes over the protrusion, and a relative rotation between the transmission assembly and the driving assembly occurs. And then the purpose of protecting the transmission assembly can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partial perspective view of the lawn mower according to the present invention. 
         FIG. 2  is a partially exploded view of  FIG. 1 . 
         FIG. 3  is an exploded view of the impact protection assembly in  FIG. 2 . 
         FIG. 4  is an exploded view of the transmission assembly in  FIG. 2 . 
         FIG. 5  is another perspective view of  FIG. 4 . 
         FIG. 6  is an exploded view of the first blade in  FIG. 2 . 
         FIG. 7  is an exploded view of the second blade in  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following describes the present invention in detail with reference to the accompanying drawings and specific embodiment. 
     The invention discloses a lawn mower (not shown), which includes a main body, a push rod extending backward from the main body, and a walking wheel provided at the bottom of the main body. The walking wheel includes two front traveling wheels arranged on both sides of the front end of the main body and two rear traveling wheels arranged on both sides of the rear end of the main body. Because the push rod and the walking wheel can be designed according to the existing scheme, the structure of the push rod and the walking wheel will not be described. 
     As shown in  FIG. 1  and  FIG. 2 , a driving assembly  10 , an impact protection assembly  20 , a transmission assembly  30 , and a cutting assembly  40  are installed on the main body. The driving assembly  10  is used to drive the transmission assembly  30  to rotate, and the transmission assembly  30  and the cutting assembly  40  are connected, so that when the transmission assembly  30  rotates, the cutting assembly  40  can be driven to rotate. 
     The driving assembly  10  includes a motor  11  and a motor shaft  12 . The motor shaft  12  protrudes beyond the bottom of the motor  11 , and one end of the motor shaft  12  extends into the transmission assembly  30 . When the motor  11  is turned on, the motor shaft  12  rotates and drives the transmission assembly  30  to rotate. 
     As shown in  FIG. 4  and  FIG. 5 , the transmission assembly  30  includes a first gear  31 , a second gear  32 , a third gear  33 , and a fourth gear  34  which are horizontally arranged. The center of the first gear  31 , the second gear  32 , the third gear  33  and the fourth gear  34  are located on the same straight line. The first gear  31  is connected to the motor shaft  12  so as to rotate synchronously with the motor shaft  12  driven by the motor shaft  12 . 
     The second gear  32  meshes with the first gear  31 , and the third gear  33  meshes with the first gear  31  and the fourth gear  34 , respectively. In other words, the second gear  32  and the third gear  33  are disposed on opposite sides of the first gear  31 , and the fourth gear  34  meshes with the third gear  33 . When the first gear  31  is rotated by the motor shaft  12 , the second gear  32  and the third gear  33  can be synchronously rotated, and the fourth gear  34  is also rotated synchronously by the third gear  33 . The second gear  32  and the fourth gear  34  rotates in the opposite direction, that is, when the first gear  31  rotates clockwise, the second gear  32  rotates counterclockwise, and the fourth gear  34  rotates clockwise. 
     The transmission assembly  30  further includes a gear box  35  formed with an accommodating space  301  and a cover plate  36  for covering the accommodating space  301 . The first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34  are all accommodated in the accommodating space  301 . The gear box  35  includes a bottom wall  351 , an annular side wall  352  protruding upward from the bottom wall  351 , and two protruding portions  353  protruding downward from opposite ends of the bottom wall  351 . The accommodating space  301  is formed by the bottom wall  351  and the annular side wall  352 . Two receiving spaces  302  communicating with the accommodating space  301  are respectively provided in the two protruding portions  353 , and the receiving space  302  penetrates the corresponding protruding portion  353  downward. 
     The bottom wall  351  of the gear box  35  is further provided with a convex post  303  and a through hole  304 . The convex post  303  is provided in a blind hole shape and is used to cooperate with the impact protection assembly  20  so as to limit the gear  31  in the up and down direction. The through hole  304  is correspondingly provided at the bottom of the third gear  33 . The fixed shaft  37  is received in the through hole  304  and fixed to the bottom wall  351  of the gear box  35  by the screw  50 . The third gear  33  is rotatably fixed at the fixed shaft  37 , in this way, it is ensured that the third gear  33  will not move arbitrarily in the gear box  35  and will not leave the gear box  35 . 
     The periphery of the cover plate  36  and the annular side wall  352  of the gear box  35  are fixed by screws to seal the accommodating space  301  and ensure that the first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34  can be fixed at a space to rotate. The cover plate  36  is provided in a horizontal plate structure and is provided with mounting holes  361  penetrating up and down. The driving assembly  10  is fixed on the cover plate  36  and is fixedly connected to the cover plate  36  through the mounting hole  361 . The motor shaft  12  passes downward through the mounting hole  361  and enters the inside of the accommodating space  301  and is connected to the first gear  31  and then drives the first gear  31  to rotate. 
     As shown in  FIG. 3  and in combination with  FIG. 2 , the impact protection assembly  20  includes a first bearing seat  21  and a second bearing seat  22  which are transitionally fitted, and an elastic member  23  and a ball  24  located between the first bearing seat  21  and the second bearing seat  22 . The first bearing seat  21  is provided with at least one protrusion  211 . When the driving assembly  10  is normally driven, the ball  24  is pushed to by the elastic member  23  to contact the protrusion  211  of the first bearing seat  21 , in order to drive the transmission assembly  30  and the cutting assembly  40  to rotate synchronously. When the resistance received by the cutting assembly  40  is greater than a preset value, the elastic member  23  is continuously compressed and the ball  24  passes over the protrusion  211 , and a relative rotation is generated between the transmission assembly  30  and the driving assembly  10 . 
     Specifically, the first bearing seat  21  includes a cylindrical body portion  210  and an extending portion  212  extending outwardly from an outer side wall of the body portion  210 . The extending portion  212  is provided in a ring shape and has a larger diameter than the diameter of the body portion  210 . Three protrusions  211  are provided on the upper surface of the extending portion  212  and are evenly distributed. The extending portion  212  is also provided with a sliding groove  213  for the ball  24  to slide. The sliding groove  213  is annularly arranged and passes over the protrusion  211 . That is, the protrusion  211  is also provided with a sliding groove  213 , so that the ball  24  can slide between the two adjacent protrusions  211  along the sliding groove  213 , or can directly pass over the protrusion  211  along the sliding groove  213 . 
     The body portion  210  is provided with an inner cavity  214  and two grooves  215  formed by being recessed outward from the inner side wall of the body portion  210 . Each groove  215  contains a flat key  216 , and one end of the motor shaft  12  is inserted into the inner cavity  214  and cooperates with the two flat keys  216 . In this way, torque can be transmitted between the motor shaft  12  and the first bearing seat  21  through the flat keys  216 . 
     The second bearing seat  22  is sleeved outside the body portion  210  of the first bearing seat  21  and cooperates with the extending portion  212 . The second bearing seat  22  is provided with a boss  221 , and the elastic member  23  and the ball  24  are received in the boss  221 . That is, when the second bearing seat  22  is sleeved on the first bearing seat  21 , the ball  24  is in contact with the sliding groove  213  on the first bearing seat  21  and the ball  24  is at least partially received in the boss  221 . The elastic member  23  is compressed and accommodated between the boss  221  and the ball  24  in a limited position. In this embodiment, three bosses  221 , three elastic members  23 , and three balls  24  are also provided respectively to correspond to the three protrusions  211 , but it should not be limited to this. 
     The second bearing seat  22  and the first gear  31  are fixed together by screws, and the first bearing seat  21  and the motor shaft  12  are fixed by two flat keys  216 , so that the entire impact protection assembly  20  does not fall down, and the stability is better. 
     As shown in  FIGS. 2 and 4 , in order to further protect the transmission assembly  30 , the present application further adds a locking structure (as part of the impact protection assembly  20 ) between the transmission assembly  30  and the cutting assembly  40 . And the rotation direction of the locking structure is opposite to the rotation direction of the cutting assembly  40 , so that when the cutting assembly  40  hits a hard object, the locking structure is directly locked, and a part of the momentary impact force is transferred to the gear box  35  to reduce the impact on the transmission assembly  30 . 
     Specifically, the impact protection assembly  20  further includes a driving shaft  25  connecting the transmission assembly  30  and the cutting assembly  40  and a unilateral bearing  26  sleeved on the driving shaft  25 . When the driving assembly  10  is normally driven, the transmission assembly  30  drives the driving shaft  25 , the unilateral bearing  26  and the cutting assembly  40  to rotate synchronously. When the resistance received by the cutting assembly  40  is greater than a preset value, the unilateral bearing  26  locks the driving shaft  25  to avoid the transmission assembly  30  from being affected by the momentary impact force. 
     As shown in  FIGS. 4 to 7  in combination with  FIG. 2 , the cutting assembly  40  includes a first blade assembly  41  connected to the second gear  32  and a second blade assembly  42  connected to the fourth gear  34 . Since the rotation directions of the second gear  32  and the fourth gear  34  are opposite, the first blade assembly  41  and the second blade assembly  42  are perpendicular to each other and rotate in opposite directions in the same plane. 
     The first blade assembly  41  includes a first blade  411 , a first fixing seat  412  positioned above the first blade  411  to limit the first blade  411 , a first shim  413  positioned below the first blade  411 , and a first nut  414  for fixing the first shim  413 , the first blade  411 , and the first fixing seat  412  together. The second blade assembly  42  includes a second blade  421 , a second fixing seat  422  positioned above the second blade  421  to limit the second blade  421 , a second shim  423  positioned below the second blade  421 , and second nut  424  for fixing the second shim  423 , the second blade  421 , and the second fixing seat  422  together. Both the first blade  411  and the second blade  421  are used to mower grass, and they have the same rotation speed and opposite rotation directions. 
     Since the cutting assembly  40  includes a first blade assembly  41  and a second blade assembly  42 , two driving shafts  25  are correspondingly provided, which include a first driving shaft  251  connected between the second gear  32  and the first blade  411 , and a second driving shaft  252  connected between the fourth gear  34  and the second blade  421 . The unilateral bearings  26  are also provided with two, which include respectively the first unilateral bearing  261  sleeved on the first driving shaft  251  and a second unilateral bearing  262  sleeved on the second driving shaft  252 . 
     The first driving shaft  251  is accommodated in the receiving space  302  of one of the protruding portions  353  of the gear box  35 , and the top end is fixedly connected to the second gear  32  through the bearing seat  271  and the end cover  272 , and the bottom end protrudes downward beyond the protruding portion  353 . The protruding portion  353  is connected to the first blade  411  through the first fixing seat  412 . And the bottom end goes through the first shim  413  and is fixed to the first nut  414 , so the first blade  411  is fixed to the first driving shaft  251 . The first unilateral bearing  261  is located at the lower end of the first driving shaft  251  and is disposed near the first fixing seat  412 . When the first driving shaft  251  is rotated by the second gear  32 , it can drive the first blade assembly  41  to rotate as a whole, and the first blade  411  performs a cutting operation. 
     The second driving shaft  252  is received in the receiving space  302  of the other protruding portion  353  of the gear box  35 , and the top end is also fixedly connected to the fourth gear  34  through the bearing seat  271  and the end cover  272 , and the bottom end protrudes downward beyond the protruding portion  353  and is connected to the second blade  421  through the second fixing seat  422 . And the bottom end goes through the second shim  423  and is fixed to the second nut  424 , so the second blade  421  is fixed to the second driving shaft  251 . The second unilateral bearing  262  is located at the lower end of the second driving shaft  252  and is disposed close to the second fixing seat  422 . When the second driving shaft  252  is rotated by the fourth gear  34 , the second blade  42  can be rotated as a whole, and the second blade  421  performs a cutting operation. 
     When the driving assembly  10  is normally driven, firstly the motor shaft  12  drives the first bearing seat  21  to rotate. When the first bearing seat  21  rotates until the ball  24  contacts the protrusion  211 , the elastic member  23  is compressed. The axial force received by the first gear  31  cannot continue to compress the elastic member  23 , so that the ball  24  cannot pass over the protrusion  211  on the first bearing seat  21 , and the second bearing seat  22  and the first gear  31  rotate with the first bearing seat  21 . Then, with the drive of the first gear  31 , the second gear  32 , the third gear  33  and the fourth gear  34  rotate synchronously Finally, the second gear  32  drives the first driving shaft  251  and the first unilateral bearing  261  to rotate, and the first blade  411  rotates smoothly. The fourth gear  34  drives the second driving shaft  252  and the second unilateral bearing  262  to rotate, and the second blade  421  rotates smoothly. At this time, the first blade  411  and the second blade  421  can perform mowing at the same time. 
     When the first blade  411  rotates at a high speed, if it hits a hard object in an instant, the first blade  411  will quickly transmit the reverse axial force it receives to the second gear  32 , and the first gear  31  receives a big axial force at the same time. The axial force will continue to compress the elastic member  23  in an instant, and the ball  24  passes over the protrusion  211  on the first bearing seat  21 , so that no torque can be transmitted between the first bearing seat  21  and the second bearing seat  22 , and the first gear  31  is slipping. That is, the first bearing seat  21  and the second bearing seat  22  are unloaded, and the first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34  are protected. In addition, the first blade  411  also transmits the received reverse axial force to the first driving shaft  251  and the first unilateral bearing  261 . Since the first unilateral bearing  261  can only rotate in one direction, the first unilateral bearing  261  locks the first driving shaft  251  under the action of a large axial force. At this time, part of the axial force is distributed to the gear box  35 , so that the instantaneous impact force received by the first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34  is small, thereby protecting the first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34 . 
     Similarly, when the second blade  421  rotates at a high speed, if it hits a hard object instantly, the elastic member  23  and the ball  24  can also be used to unload the first bearing seat  21  and the second bearing seat  22 . At the same time, the second unilateral bearing  262  can also be used to lock the second driving shaft  252 , so that part of the instant impact force is distributed to the gear box  35 , so that the instantaneous impact force received by the first gear  31 , the second gear  32 , the third gear  33 , and the fourth gear  34  is small. 
     In summary, on the one hand, the lawn mower of the present invention is provided with an elastic member  23  and a ball  24  between the first bearing seat  21  and the second bearing seat  22 , and a protrusion  211  is provided on the first bearing seat  21 . Therefore, when the driving assembly  10  is normally driven, the ball  24  is pushed by the elastic member  23  into contact with the protrusion  211  of the first bearing seat  21 . And then the transmission assembly  30  and the cutting assembly  40  are driven to rotate synchronously. When the cutting assembly  40  receives an external obstacle&#39;s reaction force greater than a preset value, the elastic member  23  is continuously compressed and the ball  24  passes over the protrusion  211 , causing relative rotation between the transmission assembly  30  and the driving assembly  10  to achieve unloading. The purpose of protecting the transmission assembly  30  is achieved. 
     On the other hand, the driving shaft  25  and the unilateral bearing  26  sleeved on the driving shaft  25  are disposed between the transmission assembly  30  and the cutting assembly  40 . When the driving assembly  10  is normally driven, the transmission assembly  30  drives the driving shaft  25 . The unilateral bearing  26  and the cutting assembly  40  rotate synchronously. When the reaction force of the cutting assembly  40  by an external obstacle is greater than a preset value, the unilateral bearing  26  locks the driving shaft  25  to prevent the transmission assembly  30  from receiving the instant impact force. The purpose of protecting the transmission assembly  30  is achieved. 
     The above embodiment is only used to illustrate the technical solution of the present invention. Although the present invention has been described in detail with reference to the preferred embodiment, those skilled in the art should understand that the technical solution of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.