Patent Publication Number: US-2021168999-A1

Title: Robotic lawn mower

Description:
RELATED APPLICATION INFORMATION 
     This application claims the benefit under 35 U.S.C. § 119(a) of Chinese Patent Application No. CN 201911245936.X, filed on Dec. 7, 2019, and Chinese Patent Application No. CN 202011370802.3, filed on Nov. 30, 2020, which applications are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to garden tools, in particular to a lawn mower and a robotic lawn mower. 
     BACKGROUND 
     A lawn mower is one of commonly used garden tools, which is mainly used for mowing all kinds of lawns. Compared with a traditional lawn mower, robotic lawn mowers can run autonomously and complete mowing according to a planned path, which can save a lot of labor, reduce the cost of lawn maintenance and improve labor efficiency. Moreover, they use electric energy and scientifically plan a path, thereby reducing repetitive work and saving energy. 
     At present, most robotic lawn mowers can usually move the height of their mowing systems up and down in order to achieve different mowing heights. However, structures of an adjusting mechanism and components adjusted by the adjusting mechanism of the mowing systems are relatively complex, the stability of the robotic lawn mowers is poor, the structures are complex, and the stability is poor during adjusting. 
     SUMMARY 
     In one example of the disclosure, a robotic lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the robotic lawn mower to walk on a ground; and an energy source device used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a driving shaft for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. When the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the driving shaft along the first axis. 
     In one example, when the height adjusting mechanism drives the cutting assembly to move along the first axis, the position of the driving shaft relative to the housing in the first axis remains constant. 
     In one example, the driving shaft is formed with a driving portion for driving the mounting shaft to rotate synchronously with the driving shaft and the driving portion allows the mounting shaft to move relative to the driving shaft along the first axis. 
     In one example, the driving shaft is formed with a mounting hole extending along the first axis, the mounting shaft is inserted into or passes through the mounting hole, and the driving portion is formed on a hole wall of the mounting hole. 
     In one example, the height adjusting mechanism includes an operating member for a user to operate, an adjusting assembly including an adjusting member and a mounting bracket for mounting the mounting shaft, and when the operating member is operated by the user, the adjusting member drives the mounting bracket to move along the first axis. 
     In one example, the adjusting member is capable of rotating about a rotation axis relative to the housing, and the adjusting member and the mounting bracket form a transmission fit that can convert the rotation of the adjusting member into a sliding movement of the mounting bracket along the first axis. 
     In one example, the driving mechanism further includes a prime mover used to output power, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the prime mover remains fixed relative to the housing along the first axis. 
     In one example, the driving mechanism further includes a prime mover for outputting power to drive the cutting assembly to cut the grass, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the prime mover along the first axis. 
     In one example, the driving shaft is a prime mover shaft of the prime mover. 
     In one example, the driving mechanism further includes a transmitting assembly for realizing a power transmission between the prime mover and the mounting shaft, and the driving shaft is a power output member of the transmitting assembly. 
     In one example, when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the position of the transmitting assembly relative to the housing along the first axis remains constant. 
     In one example, the prime mover includes a prime mover shaft and the prime mover shaft is capable of rotating about a second axis that is parallel to and not coincident with the first axis. 
     In one example, the prime mover includes a prime mover shaft which is capable of rotating about a second axis perpendicular to or inclined to the first axis. 
     In one example, the height adjusting mechanism further includes a driving motor for driving the mounting shaft to move along the first axis. 
     In one example, the driving mechanism includes a prime mover for outputting power to drive the cutting assembly to mow grass, and the prime mover and the driving motor are arranged in the housing. 
     In one example of the disclosure, a robotic lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the robotic lawn mower to walk on a ground; and a battery pack used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a electric motor for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. Wherein when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the electric motor along the first axis. 
     In one example, the driving mechanism further includes a transmitting assembly for realizing a power transmission between the electric mover and the mounting shaft, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the transmitting assembly along the first axis. 
     In one example, the height adjusting mechanism further includes a driving motor for driving the mounting shaft to move along the first axis. 
     In one example, the electric motor is fixedly mounted to the housing. 
     In one example of the disclosure, a lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the lawn mower to walk on a ground; and a battery pack used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a electric motor for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. When the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the position of the electric motor relative to the housing in the first axis remains constant. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view of a lawn mower according to a first example; 
         FIG. 2  is a schematic view of a mowing system of the lawn mower of  FIG. 1 ; 
         FIG. 3  is a matching schematic view of a driving shaft and a mounting shaft of  FIG. 2 ; 
         FIG. 4  is a schematic view of a mowing system of a lawn mower according to a second example; 
         FIG. 5  is a schematic view of a mowing system of a lawn mower according to a third example. 
     
    
    
     DETAILED DESCRIPTION 
     A lawn mower  100  of a first example shown in  FIG. 1  is used to mow vegetation such as lawns and weeds. In this example, the lawn mower  100  is a robotic lawn mower that does not need to be pushed by a user, and the robotic lawn mower can automatically mow the lawns without being operating by the user. The lawn mower can also be a push-type lawn mower. For the push-type lawn mower, the user usually stands behind the push-type lawn mower, and the user pushes a handle of the push-type lawn mower to push it to walk on a ground. Alternatively, the lawn mower may also be a riding lawn mower. For the riding lawn mower, the user rides on a seat of the riding lawn mower to operate it to walk on the ground. 
     As shown in  FIGS. 1 and 2 , the lawn mower  100  includes a mowing system  10 , a working assembly  20 , a control assembly, an energy source device  40  and a housing  50 . The mowing system  10  is used to implement a mowing function of the lawn mower  100 . The working assembly  20  includes a working wheel  21  for driving the lawn mower  100  to walk on. i.e., move over/across, the ground. The control assembly is used to control electrical equipment in the lawn mower  100  and to display intelligent performances of the lawn mower  100 . The energy source device  40  is used to provide an energy source for the mowing system  10 , the working assembly  20 , and the control assembly. In this example, the energy source device  40  is a power source device, and the power source device may include a battery pack  41  installed to the housing  50 . The housing  50  is used to support the mowing system  10 , the control assembly and the energy source device  40 . The walking assembly  20  is installed to the housing  50  and supports the housing  50 . 
     The mowing system  10  includes a driving mechanism  110 , a cutting assembly  120 , and a height adjusting mechanism  130 . The driving mechanism  110  includes a prime mover for outputting power. The cutting assembly  120  includes a mounting shaft  121  and a mowing member  122 . The mounting shaft  121  is used to drive the mowing member  122  to rotate about a first axis  101  to realize the mowing function. The mowing member  122  may be a blade for cutting grass. The height adjusting mechanism  130  can adjust the height of the mowing member  122  relative to the housing  50  in the first axis  101 , so that the lawn mower  100  has different cutting heights. For example, the height adjusting mechanism  130  can adjust the cutting assembly  120  to move the mowing member  122  to a first height and a second height. When the mowing member  122  is at the first height, the mowing member  122  is closer to the ground, so that more grass on the ground can be cut. When the mowing member  122  is at the second height, the mowing member  122  is far away from the ground, so that less grass on the ground can be cut. 
     In this example, the height adjusting mechanism  130  can drive the mounting shaft  121  and the mowing member  122  mounted on the mounting shaft  121  to move up and down along the first axis  101 . When the height adjusting mechanism  130  adjusts the mounting shaft  121  to move up and down, a position of the prime mover relative to the housing  50  in the first axis  101  remains fixed. In this way, the height adjusting mechanism  130  drives the cutting assembly  120  to move up and down along the first axis  101 , but does not drive the prime mover to move up and down synchronously with the cutting assembly  120 , so that a total number of parts driven by the height adjusting mechanism  130  that can move up and down in the first axis  101  synchronously with the mowing member  122  is small. A total weight of the parts is also relatively small, thereby improving the comfort of operating of the height adjusting mechanism  130  and the stability of the height adjusting mechanism  130 . A weight of loads driven by the height adjusting mechanism  130  is also relatively small, thereby prolonging the service life of the height adjusting mechanism  130 . In addition, the housing  50  is formed with or connected with a mounting structure  51 . Because the prime mover does not move up and down with the cutting assembly  120 , so that the prime mover can be fixedly installed to the mounting structure  51 , thereby improving the reliability of the prime mover and reducing the vibration generated by the prime mover during the operation of the lawn mower  100 , thereby prolonging the service life of the lawn mower  100 . Furthermore, the mounting shaft  121  and the mowing member  122  can be driven by the height adjusting mechanism  130  at the same time to move up and down in the first axis  101 , so that the mowing member  122  is stably mounted to the mounting shaft  121 , improving the reliability of the cutting assembly  120 . Especially for the robotic lawn mower, the size of the robotic lawn mower is relatively small. If the driving mechanism  110  also moves up and down along with the cutting assembly  120 , the robotic lawn mower needs a larger space for the driving mechanism  110  and the cutting assembly  120  to move, which is not conducive to the miniaturization of the robotic lawn mower. In this example, the driving mechanism  110  does not move with the cutting assembly  120 , so that the internal structure of the robotic lawn mower is relatively compact, thereby facilitating the miniaturization of the robotic lawn mower. 
     The prime mover includes a driving shaft  1111  for outputting power and the driving shaft  1111  is the prime mover shaft of the prime mover. In this example, the prime mover is an electric motor  111 , the electric motor  111  includes a stator assembly and a rotor assembly, the rotor assembly also includes a rotor shaft, and the rotor shaft is the driving shaft  1111  for outputting power of the electric motor  111 . When the height adjusting mechanism  130  drives the mounting shaft  121  and the mowing member  122  to move up and down along the first axis  101 , the position of the driving shaft  1111  relative to the housing  50  in the first axis  101  remains constant. In the present example, the driving shaft  1111  is arranged along the first axis  101 . The driving shaft  1111  is also coaxial with the mounting shaft  121 . The driving shaft  1111  is provided with a first mounting hole  1111   a  extending along the first axis  101 , the first mounting hole  1111   a  penetrates the driving shaft  1111  along the first axis  101 , and the mounting shaft  121  is inserted into or passes through the first mounting hole  1111   a.  When the prime mover is in operation, the driving shaft  1111  can rotate around the first axis  101 , and the driving shaft  1111  transmits power to the mounting shaft  121  to drive the mounting shaft  121  to rotate around the first axis  101 . The mounting shaft  121  can also slide up and down along the first axis  101  relative to the driving shaft  1111 . Specifically, as shown in  FIG. 3 , the driving shaft  1111  is provided with a driving portion formed on a hole wall of the first mounting hole  1111   a,  the driving portion drives the mounting shaft  121  to rotate synchronously with the driving shaft  1111 , and the driving portion allows the mounting shaft  121  to slide up and down relative to the driving shaft  1111 . In this example, the driving portion is directly formed on the hole wall of the mounting hole  1111   a  and the driving portion is a transmission plane parallel to the first axis  101 . It can be understood that in some other examples, a mounting hole of a driving shaft can also be provided with a driving member, the driving member may be a bushing, the bushing is fixedly connected with the driving shaft, and the bushing forms a driving hole, and a hole wall of the driving hole forms a driving portion that can drive a mounting shaft to rotate with the driving shaft, and the mounting shaft passes through the driving hole. 
     In the present example, the cutting assembly  120  also includes a mounting member for mounting the mowing member  122  to the mounting shaft  121 . The mounting member is a disc, the mowing member  122  is a blade mounted on the disc, and the blade also can rotate relative the disc. The disc is fixed to a preset position on the mounting shaft  121  through fasteners, and there is only one preset position. That is to say, the position of the disc relative to the mounting shaft  121  in the first axis  101  is not adjustable, and the position of the disc relative to the mounting shaft  121  in the first axis  101  is fixed. In this way, the disc can be more stably installed to the mounting shaft  121 , so as to prevent the disc from loosening relative to the mounting shaft  121 . 
     The height adjusting mechanism  130  includes an operating member and an adjusting assembly  132 . The operating member is used for the user to operate to control cutting heights of the cutting assembly  120 . In this example, the operating member is a knob  131  that can be turned by the user. The knob  131  may be arranged below the housing  50  or above the housing  50 . In other examples, an operating element may also be an operating button. The lawn mower  100  further includes a display screen  60 , and the operating member may be a touch button on the display screen  60 , and the display screen  60  is a touch screen. 
     The adjusting assembly  132  includes an adjusting member  1321  and a mounting bracket  1322 . The mounting bracket  1322  is composed of two parts. The adjusting member  1321  is connected to the operating member, and the mounting bracket  1322  is used for mounting the mounting shaft  121 . When the user operates the knob  131 , the adjusting member  1321  adjusts the mounting bracket  1322  to move along the first axis  101  or a direction parallel to the first axis  101 , and the mounting bracket  1322  drives a whole of the mounting shaft  121  and the mowing member  122  along the first axis  101 , so that the lawn mower  100  has different cutting heights. 
     The adjusting member  1321  can rotate around a rotation axis, and the adjusting member  1321  and the mounting bracket  1322  form a transmission fit that can convert the rotation of the adjusting member  1321  into a sliding movement of the mounting bracket  1322  along the first axis  101 . The transmission fit may be a direct fit between the adjusting member  1321  and the mounting bracket  1322 , or an indirect fit in which a switching structure is provided between the adjusting member  1321  and the mounting bracket  1322 . Specifically, the adjusting member  1321  is a screw rod. A first thread is formed on the screw rod, and a second thread that matches the first thread is formed on the mounting bracket  1322 . The rotation of the mounting bracket  1322  about the first axis  101  is restricted, that is, the mounting bracket  1322  cannot rotate about the first axis  101 . In this way, when the adjusting member  1321  rotates with the knob  131 , the adjusting member  1321  will drive the mounting bracket  1322  to move along the first axis  101  under the cooperation of the first thread and the second thread. The screw rod is mounted to the mounting structure  51  of the housing  50 . 
     As shown in  FIG. 2 , the mounting bracket  1322  is formed with a second mounting hole  1322   b  extending along the first axis  101 , and the mounting shaft  121  passes through the second mounting hole  1322   b.  The second mounting hole  1322   b  is also recessed along a radial direction perpendicular to the first axis  101  to form a groove  1322   c.  The adjusting assembly  132  further includes a bearing  1323 , the bearing  1323  is installed in the groove  1322   c,  and the bearing  1323  can move synchronously with the mounting bracket  1322  along the first axis  101 . A groove wall of the groove  1322   c  is formed with a first limiting portion  1322   d,  and the first limiting portion  1322   d  can restrict the bearing  1323  from separating from the mounting bracket  1322  along the first axis  101 . The bearing  1323  also supports the mounting shaft  121 , an inner ring of the bearing  1323  can be fixedly connected to the mounting shaft  121 , and an outer ring of the bearing  1323  can be fixedly connected to the groove wall of the groove  1322   c.  In this example, the inner ring of the bearing  1323  can be interference fit with the mounting shaft  121 , and the outer ring of the bearing  1323  can be interference fit with the groove wall of the groove  1322   c.    
     In the present example, the mounting shaft  121  is formed with or connected with a second limiting portion  1211 , and the second limiting portion  1211  can limit the bearing  1323  from disengaging from the mounting shaft  121  along the first axis  101 . In the present example, the second limiting portion  1211  is a pair of annular protrusions formed on the mounting shaft  121 , and the bearing  1323  is arranged between the pair of annular protrusions. In other examples, a second limiting portion may also be a clamp ring provided on a mounting shaft. 
     The height adjusting mechanism  130  further includes a sliding rail for restricting the rotation of the mounting bracket  1322 , and the sliding rail is installed on the housing  50  along a direction parallel to the first axis  101 . One side of the mounting bracket  1322  is used as a sliding block to cooperate with the sliding rail. The sliding rail is formed on the housing  50 , or the sliding rail is formed of a part fixed relative to the housing  50 . The sliding rail limits the rotation of the mounting bracket  1322  around the first axis  101  and allows the mounting bracket to slide along the sliding rail in the first axis  101 . One end of the screw rod is fixed relative to the housing  50 , the screw rod can only rotate around the axis of the screw rod, and the other end of the screw rod passes through and is fixedly connected with the knob  131 , which can drive the screw rod to rotate when the knob  131  rotates. 
     When the user operates the knob  131 , the screw rod follows the knob  131  to rotate. Because the mounting bracket  1322  is matched with the screw rod, and the other side of the mounting bracket  1322  is fitted in the sliding rail and cannot rotate and move horizontally, the mounting bracket  1322  can move up and down along the slid sliding rail under the rotation of the screw rod. 
     Because the bearing  1323  is fixed on the mounting bracket  1322 , the bearing  1323  has a tendency to move up and down following the mounting bracket  1322 , and thus has a tendency to move relative to the mounting shaft  121 . Since the mounting shaft  121  is provided with a stopper that restricts the relative movement of the bearing  1323  and the mounting shaft  121 , the bearing  1323  will drive the mounting shaft  121  to move up and down when the bearing  1323  is driven by the mounting bracket  1322 . 
     The mounting shaft  121  cooperates with the driving shaft  1111  of the driving mechanism  110 . But the mounting shaft  121  cannot drive the driving shaft  1111  to move up and down, thus cannot drive the driving mechanism  110  to move up and down. 
     Therefore, the height adjusting mechanism  130  only adjusts the height of the mounting shaft  121  and does not adjust the height of other components. 
       FIG. 4  shows the internal structure of a lawn mower of a second example. In this example, the lawn mower may also be a robotic lawn mower. The lawn mower includes a working assembly, a control assembly, and a power source device which are substantially the same as that in the lawn mower  100  in the first example. The lawn mower of this example further includes a mowing system  20   a  and a housing for mounting the mowing system  20   a,  and the housing includes a mounting structure  200 . The mowing system  20   a  includes a cutting assembly  230  and a height adjusting mechanism  240  that are basically the same as that in the lawn mower  100  of the first example. The main difference between this example and the first example is that the mowing system  20   a  includes a driving mechanism  210  that is different from that in the first example. The driving mechanism  210  includes a prime mover  211  and a transmitting assembly  220  for realizing a power transmission between the prime mover  211  and the cutting assembly. In this example, because the driving mechanism  210  is different from the first example and the driving mechanism  210  is mounted to the housing, the housing also includes another mounting structure  200  for mounting the driving mechanism  210 . The following mainly introduces the differences between this example and the first example, and the parts of this example with the same as the first example will not be described in detail. 
     As shown in  FIG. 4 , the height adjusting mechanism  240  can adjust a whole of a mounting shaft  231  and a mowing member  232  to move up and down along a first axis  201 , so that the lawn mower has different cutting heights. 
     In this example, the prime mover  211  includes a prime mover shaft  2111  that can rotate about a second axis  202 . The transmitting assembly  220  is used to transmit a power output by the prime mover shaft  2111  to the mounting shaft  231 . 
     In this example, the transmitting assembly  220  is mounted to the mounting structure  200  of the housing. The transmitting assembly  220  includes a driving shaft for driving the mounting shaft  231  to rotate, which drives the mounting shaft  231  to rotate synchronously and allows the mounting shaft  231  to move up and down in the first axis  201  relative to it. Here, the driving shaft is considered as a part of the transmitting assembly  220 , and the driving shaft is a power output member of the transmitting assembly  220 . Of course, it can be considered that the driving shaft is not part of the transmitting assembly  220 , but that the transmitting assembly  220  is used to transfer a power between the prime mover  211  and the driving shaft. In this example, the driving shaft is a first driving wheel  221 , and the transmitting assembly  220  further includes a second driving wheel  222  and a driving belt  223 . The driving belt  223  is a synchronous belt, the first driving wheel  221  and the second driving wheel  222  are synchronous belt wheels, and a torque transmission of the transmitting assembly  220  is constant speed transmission. In other words, the transmitting assembly  220  only transmits a torque without changing the speed, so that the speed of the mounting shaft  231  is the same as that of the prime mover shaft  2111 . In other examples, a transmitting assembly can also change the speed transmitted from the prime mover shaft to the mounting shaft so that the speed of the mounting shaft is different from that of the prime mover shaft. 
     In some other examples, the transmitting assembly may be one or a combination of two or more of belt transmission, rope transmission, friction wheel transmission, gear transmission, chain transmission, screw transmission, or harmonic transmission. 
     By providing the transmitting assembly  220 , the prime mover  211  and the mounting shaft  231  are not arranged on the same axis, an overall size of the driving mechanism  210  and the cutting assembly  230  in a height direction of the housing can be reduced, thereby facilitating the miniaturization of the lawn mower. Moreover, in the present example, the prime mover  211  is a motor, and the transmitting assembly  220  is provided so that the electric motor can be a conventional electric motor in the prior art, which reduces the design and production cost of the motor and can also improve the structural strength and reliability of the motor. Furthermore, the transmitting assembly  220  is provided so that the cutting assembly  230  can be separated from the driving mechanism  210 , thereby facilitating maintenance of the driving mechanism  210  and the cutting assembly  230  separately. 
     Specifically, the second driving wheel  222  is fixedly connected to the prime mover shaft  2111 , and the first driving wheel  221  is formed with a driving portion  221   a.  The driving portion  221   a  can output torque to the mounting shaft  231  to drive the mounting shaft  231  to rotate synchronously with the first driving wheel  221 . The driving portion  221   a  also allows the mounting shaft  231  to move up and down along the first axis  201 . In this way, when the user operates an operating member  241 , the height adjusting mechanism  240  can adjust a whole of the mounting shaft  231  and the cutting member  232  to move up and down along the first axis  201  relative to the transmitting assembly  220 , thereby enabling the lawn mower to have different cutting heights. 
     In the present example, the height adjusting mechanism  240  only drives the cutting assembly  230  to move up and down in the first axis  201 , while the prime mover  211  and the transmitting assembly  220  are kept constant relative to the housing in the first axis  201 . A total number of parts driven by the height adjusting mechanism  240  that can move up and down in the first axis  201  synchronously with the mowing member  232  is small, and a total weight of the parts is also relatively small, thereby improving the comfort of operation of the height adjusting mechanism  240  and improving the stability of the height adjusting mechanism  240 . The weight of loads driven by the height adjusting mechanism  240  is also relatively small, thereby prolonging the service life of the height adjusting mechanism  240 . In addition, since the prime mover  211  and the transmitting assembly  220  do not move up and down together with the cutting assembly  230 , the prime mover  211  and the transmitting assembly  220  can be mounted to the mounting structure  200  of the housing, thereby improving the reliability of the prime mover  211  and the transmitting assembly  220 , reducing the vibration generated by the prime mover  211  and the transmitting assembly  220  during the operation of the lawn mower, thereby extending the service life of the lawn mower. Furthermore, the mounting shaft  231  and the mowing member  232  can be driven by the height adjusting mechanism  240  to move up and down in the first axis  201 , so that the mowing member  232  is stably mounted to the mounting shaft  231 , which improves the reliability of the cutting assembly  230 . 
     In the present example, the fit between the first driving wheel  221  and the mounting shaft  231  is clearance fit. When the mounting shaft  231  moves up and down under an external force, because the mounting shaft  231  is in the clearance fit with the first driving wheel  221 , the mounting shaft  231  does not drive the first driving wheel  221  and the driving belt  223  matched with the first driving wheel  221  to move up and down, so the prime mover  211  dose not move with the mounting shaft  231  when the mounting shaft  231  moves up and down. 
     The driving mechanism  210  can be assembled at any position in the housing under a premise of ensuring that the prime mover shaft  2111  can transmit torque to the mounting shaft  231  through the transmitting assembly  220 , so that it can also be assembled at a more reasonable position according to the position of a center of gravity of the lawn mower and the arrangement of internal structures. 
     The second axis  202  on which the prime mover shaft  2111  rotates does not overlap with the first axis  201  on which the mounting shaft  231  rotates. 
     Preferably, the first axis  201  and the second axis  202  are parallel to each other and spaced apart by a distance. The second axis  202  is parallel to and not coincident with the first axis  201 . Alternatively, in some other examples, a second axis and a first axis may be perpendicular to each other, or the second axis may be inclined relative to the first axis. 
       FIG. 5  shows the internal structure of a lawn mower of a third example. In this example, the lawn mower may also be a robotic lawn mower. The structure of the lawn mower is basically the same as that of the lawn mower in the second example. The main difference is that the lawn mower in this example is not used for a user to manually adjust a knob to achieve speed regulation, but a driving motor  331  is provided in an adjusting mechanism  330 , the driving motor  331  drives an adjusting member  3321  to rotate through a gear assembly  333 , and then the adjusting member  3321  drives a mounting bracket  3322  and a mounting shaft  321  to move up and down along a first axis  301 . In this way, an electric adjustment of the cutting height of the cutting assembly  320  can be realized, thereby facilitating the user&#39;s operation. Moreover, the driving motor  331  may also be connected with a controller and a detecting device, the detecting device detects load parameters, grass height parameters, etc., and the controller controls the operation of the driving motor  331  according to a detection result of the detection device to adjust the cutting assembly  320  to a corresponding cutting height. Alternatively, in other examples, a driving motor  331  can also be connected to a control panel, and the user can input a cutting height on the control panel, and then the driving motor  331  operates to adjust the cutting assembly  320  to a corresponding cutting height. In this example, the driving motor  331  and a prime mover are both arranged in a housing  35 .