Patent Publication Number: US-11653598-B2

Title: Electric riding lawn mower

Description:
RELATED APPLICATION INFORMATION 
     This application is a continuation of U.S. application Ser. No. 16/909,549, filed on Jun. 23, 202, which application is a continuation of International Application Number PCT/CN2018/123856, filed on Dec. 26, 2018, through which this application also claims the benefit under 35 U.S.C. § 119(a) of Chinese Patent Application No. CN 201711457168.5, filed on Dec. 28, 2017, and Chinese Patent Application No. CN 201810885961.3, filed on Aug. 6, 2018, each of which is incorporated by reference in its entirety herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an electric riding machine, in particular to an electric riding lawn mower. 
     BACKGROUND 
     As a garden tool, lawn mowers are widely used in the field of trimming lawn and vegetation, etc. Existing lawn mowers generally include handheld lawn mowers and riding lawn mowers. Among them, handheld lawn mowers are widely used because of its advantages such as small size and convenient portability. However, mowing capacity, mowing efficiency, and battery life of handheld lawn mowers cannot meet the needs of large lawn areas. Therefore, a kind of electric riding lawn mowers has gradually emerged on the market. However, the riding lawn mowers currently on the market are generally powered by gasoline or diesel, which not only pollutes the environment and goes against environmental protection, but also incurs increased maintenance costs because the wearing parts in the fuel system needs to be replaced frequently. 
     SUMMARY 
     In one example, an electric riding lawn mower includes a seat for a user to ride; a main frame configured to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly configured to at least drive the electric riding lawn mower to travel in a first straight line on the ground and including a second motor to drive the walking assembly; and a power supply device including one or more first battery packs to power the electric riding lawn mower; wherein each of the one or more first battery packs including: a first battery pack housing; and battery cells disposed in the first battery pack housing; wherein the power supply device is mounted to the main frame, and at least one of the one or more first battery packs of the power supply device forms a pluggable connection with the main frame, and the battery cells are lithium batteries. 
     In one example, the one or more first battery packs detachably coupled to the main frame are also configured to power another power tool. 
     In one example, a discharge power of all of the one or more first battery packs included in the power supply device is greater than or equal to 2000 W and less than or equal to 4000 W. 
     In one example, a ratio of the discharge power of a single one of the one or more first battery packs to the nominal voltage of a single one of the one or more first battery packs is greater than or equal to 10 W/V and less than or equal to 25 W/V. 
     In one example, the capacity of a single one of the one or more first battery packs is greater than or equal to 130 Wh and less than or equal to 1000 Wh, and a number of the one or more first battery packs included in the power supply device is greater than or equal to 4 and less than or equal to 10. 
     In one example, the weight of a single one of the one or more first battery packs is greater than or equal to 0.1 kg and less than or equal to 4 kg, and a number of the one or more first battery packs included in the power supply device is greater than or equal to 4 and less than or equal to 10. 
     In one example, the discharge power of a single one of the one or more first battery packs is greater than or equal to 500 W and less than or equal to 6500 W, and a number of the one or more first battery packs included in the power supply device is greater than or equal to 4 and less than or equal to 10. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; wherein a number of the at least one first battery compartments is one or more; and wherein in a direction of the first straight line, a distance between a center of a whole constituted by all of the at least one first battery compartments disposed on the rear side of the seat along the direction of the first straight line and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; wherein a number of the at least one first battery compartments is two; and wherein in a direction of the first straight line, a distance between a center of a whole constituted by all of the at least one first battery compartments disposed on the rear side of the seat along the direction of the first straight line and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; wherein a number of the first battery compartments is one or more; and wherein in a horizontal direction perpendicular to the rotation axis of the second travelling wheel, a distance between a center of a whole constituted by all of the at least one first battery compartments disposed on the rear side of the seat along the horizontal direction and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel having a first diameter, and the second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; wherein a number of the at least one first battery compartments is one or more; and wherein in a direction perpendicular to the first straight line and perpendicular to the second axis, a distance between a center of a whole constituted by all of the at least one first battery compartments disposed on the rear side of the seat and the second axis is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel having a first diameter, and the second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; wherein a number of the at least one first battery compartments is one or more; wherein in a direction parallel to the second axis, a distance between a center of a whole constituted by all of the at least one first battery compartments disposed on the rear side of the seat and a center of two second travelling wheels is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: a first battery compartment set including one or more first battery compartments, wherein the one or more first battery compartment are disposed on the rear side of the seat, and the one or more first battery compartment are used for detachably mounting the one or more first battery packs, and the one or more first battery packs are further configured to power another power tool; wherein a number of the one or more first battery compartments are one or more, and the power supply device is disposed on the rear side of the seat; and wherein in the a of the first straight line, a distance between a center of gravity of the power supply device to which the one or more first battery packs are mounted and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: a first battery compartment set including one or more first battery compartments, wherein the one or more first battery compartments are disposed on the rear side of the seat, the one or more first battery compartments are used for detachably mounting the one or more first battery packs, and the one or more first battery packs are further configured to power another power tool; wherein a number of the one or more first battery compartments is one or more, and the power supply device is disposed on the rear side of the seat; and wherein in a horizontal direction perpendicular to a rotation axis of the second travelling wheel, a distance between a center of gravity of the power supply device to which the one or more first battery packs are mounted and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the power supply device includes: a first battery compartment set including one or more first battery compartments, wherein the one or more first battery compartments are disposed on the rear side of the seat, the one or more first battery compartment are used for detachably mounting the one or more first battery packs, and the one or more first battery packs are further configured to power another power tool; wherein a number of the one or more first battery compartments are one or more, and the power supply device is disposed on the rear side of the seat; and wherein in a direction perpendicular to the first straight line and perpendicular to the second axis, a distance between a center of gravity of a whole of the power supply device to which the one or more first battery packs are mounted and the second axis is less than or equal to 300 mm. 
     In one example, an electric riding lawn mower including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly configured to at least drive the electric riding lawn mower to travel in a first straight line on the ground and including a second motor to drive the walking assembly; and a power supply device including at least one first battery compartment to couple to a battery pack; wherein the at least one first battery compartment is mounted to the main frame, the at least one first battery compartment is used for pluggable coupling to the battery pack, the at least one first battery compartment is further provided with input terminals to bring in electrical energy to the electric riding lawn mower. 
     In one example, a number of the at least one first battery compartment is greater than or equal to 4 and less than or equal to 10. 
     In one example, the walking assembly included: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein a number of the at least one first battery compartment is one or more; and wherein in a direction of the first straight line, a distance between the center of a whole constituted by all of the at least one the first battery compartment disposed on the rear side of the seat along the direction of the first straight line and a rotating shaft of the second travelling wheel is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter greater than the first diameter; wherein a number of the at least one first battery compartment is one or more; wherein in a direction perpendicular to the first straight line and perpendicular to the second axis, a distance between a center of a whole constituted by all of the at least one first battery compartment disposed on the rear side of the seat and the second axis is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter greater than the first diameter; wherein a number of the at least one of first battery compartment is one or more; and wherein in a direction parallel to the second axis, a distance between the center of a center of a whole constituted by all of the at least one first battery compartment disposed on the rear side of the seat and a center of two second travelling wheels is less than or equal to 300 mm. 
     In one example, an electric riding machine including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly configured to at least drive the electric riding lawn mower to travel in a first straight line on the ground and including a second motor to drive the walking assembly; and a power supply device including at least one first battery pack to power the electric riding machine; wherein the power supply device is mounted to the main frame, at least one of the at least one first battery pack of the power supply device form a detachable connection with the main frame, and the at least one first battery pack detachably connected with the main frame is also configured to power another power tool. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis. 
     In one example, the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter greater than the first diameter. 
     In one example, the first travelling wheel is a universal wheel. 
     In one example, the main frame extends in a direction of the first straight line. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter larger than the first diameter; and wherein in a direction of the first straight line, a distance between a center of gravity of the electric riding machine and the second axis is greater than or equal to 0 and less than or equal to 400 mm. 
     In one example, a center of gravity of the electric riding machine is located on the lower side of the seat. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter larger than the first diameter; and wherein in a direction of the first straight line, a ratio of a distance between the center of gravity of the electric riding machine and the first axis to a distance between the center of gravity of the electric riding machine and the second axis is greater than or equal to 2 and less than or equal to 4. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter larger than the first diameter; and wherein in a direction perpendicular to the first straight line and perpendicular to the second axis, a distance between a center of gravity of the electric riding machine and the second axis is greater than or equal to 0 and less than or equal to 150 mm. 
     In one example, the walking assembly includes: a first travelling wheel having a first diameter; and a second travelling wheel having a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat away from the first travelling wheel; wherein the at least one first battery pack of the power supply device is mounted to the at least one first battery compartment, and a number of the at least one first battery compartment is one or two or more; wherein in a direction of the first straight line, a distance between a center of a whole constituted by all of the at least one first battery compartment disposed on the rear side of the seat along the direction of the first straight line and the second axis is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein the first travelling wheel has a first diameter, and the second travelling wheel has a second diameter greater than the first diameter; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat away from the first travelling wheel; wherein the at least one first battery pack of the power supply device is mounted to the at least one first battery compartment, and a number of the at least one first battery compartment is one or more; and wherein in a direction perpendicular to the first straight line and perpendicular to the second axis, a distance between a center of a whole constituted by all of the at least one first battery compartment disposed on the rear side of the seat and the second axis is less than or equal to 300 mm. 
     In one example, the walking assembly includes: a first travelling wheel rotatable about a first axis; and a second travelling wheel rotatable about a second axis; wherein a number of the second travelling wheels is two, the two second travelling wheels are symmetrically disposed on both sides of a symmetrical plane, and the user faces a forward direction of the electric riding machine when the user sits on the seat; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; and wherein a number of the at least one first battery compartment is one or more, and a whole of all of the at least one first battery compartment disposed on the rear side of the seat is symmetrically disposed about the symmetrical plane. 
     In one example, the user faces the forward direction of the electric riding machine when the user sits on the seat; wherein the power supply device includes: at least one first battery compartment disposed on the rear side of the seat; the at least one first battery compartment is formed with a first groove, and the at least one first battery pack is detachably inserted into the first groove in the direction of a second straight line. 
     In one example, the direction of the second straight line in which the at least one first battery pack is inserted into the first groove intersects the direction of the first straight line obliquely. 
     In one example, the angle between the direction of the second straight line in which the at least one first battery pack is inserted into the first groove and the direction of the first straight line is greater than 60 degrees and less than 90 degrees. 
     In one example, the direction of the second straight line in which the at least one first battery pack is inserted into the first groove is perpendicular to the direction of the first straight line. 
     In one example, the direction of the second straight line in which the first battery pack is inserted into the first groove is parallel to the direction of the first straight line. 
     In one example, the at least one first battery compartment is also formed with a locking structure for locking the at least one first battery pack on the at least one first battery compartment. 
     In one example, a vibration damping device is further disposed between the power supply device and the main frame. 
     In one example, the at least one first battery pack includes a plurality of battery cells, an extending direction of the battery cells is parallel to the direction of a second straight line in which the first battery pack is inserted into the first groove. 
     In one example, when the at least one first battery pack is inserted into the first groove, the dimension in the direction of the first straight line of a cross section of the first battery pack in a plane perpendicular to the direction of the second straight line is smaller than the dimension of the cross section in the direction perpendicular to the first straight line and parallel to the plane. 
     In one example, at least one of the first battery pack of the power supply device is fixedly mounted to the main frame. 
     In one example, the user faces the forward direction of the electric riding machine when the user sits on the seat, and the at least one first battery pack is disposed on the rear side of the seat; wherein the power supply device further includes: a second battery pack disposed on the lower side of the seat. 
     In one example, the electric riding machine is a lawn mower, and the output member is a mowing element. 
     In one example, an electric riding lawn mower including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly including a front travelling wheel and a rear travelling wheel configured to at least drive the electric riding lawn mower walking on the ground, and a second motor to drive the rear travelling wheel, wherein the rear travelling wheel has a rotating shaft; and a power supply device including a first battery compartment set, the first battery compartment set including one or more first battery compartments, at least a portion of the one or more first battery compartments being disposed on the rear side of the seat, wherein the one or more first battery compartments are for detachably mounting a first battery pack, and the first battery pack is further configured to power another power tool; wherein a horizontal distance between a center of all of the one or more first battery compartments disposed on the rear side of the seat and a rotating shaft of the rear travelling wheel is less than or equal to 300 mm. 
     In one example, a vertical distance between a center of all of the one or more first battery compartments disposed on the rear side of the seat and the rotating shaft of the rear travelling wheel is less than 300 mm. 
     In one example, the one or more first battery compartments disposed on the rear side of the seat is disposed on the rear side of the rear travelling wheel. 
     In one example, at least one of the one or more first battery compartments is disposed on the front side of the rear travelling wheel and under the seat. 
     In one example, all of the one or more first battery compartments are located on the rear side of the seat and on the rear side of the rotating shaft of the rear travelling wheel. 
     In one example, a distance between a center of all of the one or more first battery compartments disposed on the rear side of the seat and a center of a rotating shaft of the rear travelling wheel is less than 100 mm in a left-right direction of the electric riding lawn mower. 
     In one example, an electric riding lawn mower including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly including a front travelling wheel and a rear travelling wheel configured to at least drive the electric riding lawn mower walking on the ground, and a second motor for driving the rear travelling wheel, wherein the rear travelling wheel has a rotating shaft; and a power supply device including one or more first battery compartments, at least a part of the one or more first battery compartments being disposed on the rear side of the seat, wherein the one or more first battery compartments are for detachably mounting a first battery pack, and the first battery pack is also configured to power another power tool; wherein a horizontal distance between a center of gravity of the electric riding lawn mower to which the first battery pack is mounted and the rotating shaft of the rear travelling wheel is less than or equal to 500 mm. 
     In one example, a vertical distance between a center of gravity of the electric riding lawn mower to which the first battery pack is mounted and a center of the rotating shaft of the rear travelling wheel is less than 300 mm. 
     In one example, the one or more first battery compartments disposed on the rear side of the seat are disposed on the rear side of the rear travelling wheel. 
     In one example, at least one of the one or more first battery compartments are disposed on the front side of the rear travelling wheel and under the seat. 
     In one example, all of the one or more first battery compartments are located on the rear side of the seat and on the rear side of the rear travelling wheel shaft. 
     In one example, a distance between a center of gravity of the electric riding lawn mower to which the first battery pack is mounted and a center of the rotating shaft of the rear travelling wheel are less than 100 mm in the lateral direction of the electric riding lawn mower. 
     In one example, an electric riding lawn mower including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly including a front travelling wheel and a rear travelling wheel configured to at least drive the electric riding lawn mower walking on the ground, and a second motor to drive the rear travelling wheel, wherein the rear travelling wheel has a rotating shaft; and a power supply device including one or more first battery compartments, at least a part of the one or more first battery compartments being disposed on the rear side of the seat, wherein the one or more first battery compartments are used for detachably mounting a first battery pack, and the first battery pack is also configured to power another power tool; wherein when the first battery pack is mounted to the one or more first battery compartments, a upper portion of the first battery pack is substantially equal to or shorter than the seat in a height direction. 
     In one example, an electric riding lawn mower including: a seat for a user to ride; a main frame to support the seat; a power output assembly including a mowing element for outputting power to realize a mowing function and a first motor for driving the mowing element to output power; a walking assembly including a front travelling wheel and a rear travelling wheel configured to at least drive the electric riding lawn mower walking on the ground, and a second motor for driving the rear travelling wheel, wherein the rear travelling wheel has a rotating shaft; and a power supply device for providing power; wherein the power supply device is disposed on the rear side of the seat, and a upper side of the power supply device is substantially equal to or shorter than the seat in a height direction. 
     The present disclosure is advantageous in that the electric riding lawn mower of the present disclosure has high adaptability and low usage cost. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view of an electric riding lawn mower of a first example of the present disclosure when a grass collecting device is installed; 
         FIG.  2    is a perspective view of the electric riding lawn mower of  FIG.  1    from another angle; 
         FIG.  3    is a plan view of a user riding the electric riding lawn mower of  FIG.  1   ; 
         FIG.  4    is a top view of the electric riding lawn mower of  FIG.  1   ; 
         FIG.  5    is a schematic view of a power output assembly of  FIG.  1   ; 
         FIG.  6    is a plan view of a user climbing uphill on an electric riding lawn mower; 
         FIG.  7    is a schematic view showing a second travelling wheel and the centre of gravity of the entirety formed by a user and an electric riding lawn mower; 
         FIG.  8    is a schematic structural view of a power tool system; 
         FIG.  9    is a schematic structural view of a first battery pack of  FIG.  1   ; 
         FIG.  10    is a perspective view of the electric riding lawn mower of  FIG.  1    when a cover is opened; 
         FIG.  11    is a perspective view of the electric riding lawn mower of  FIG.  1    when a first battery pack is removed; 
         FIG.  12    is a top view of the structure shown in  FIG.  11   ; 
         FIG.  13    is a plan view of an electric riding lawn mower of a second example of the present disclosure; 
         FIG.  14    is a plan view of an electric riding lawn mower of a third example of the present disclosure; 
         FIG.  15    is a top view of an electric riding lawn mower of a fourth example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The electric riding machine shown in  FIG.  1    can be an electric machine for working indoors or outdoors. In the present example, the electric riding machine is specifically exemplified by the electric riding lawn mower  100 . The electric riding lawn mower  100  can be used for the user to ride. When sitting on the electric riding lawn mower, the user can effectively and quickly trim lawn, vegetation, etc. by operating the electric riding lawn mower. Comparing with walk behind lawn mowers, the electric riding lawn mower  100  of the present disclosure does not require the user to push the machine, nor does it require the user to walk on the ground, and because its large size brings longer endurance, the user is able to trim larger lawns, and trim for a long time with less tiredness. Furthermore, when it comes to power source, the electric riding lawn mower  100  uses electrical energy rather than gasoline or diesel used by existing riding lawn mowers; this not only costs less and is more environmental friendly, but also requires part replacement less often, reducing maintenance costs. 
     It can be understood that the electric riding machine may be other types of electric machines, as long as the electric machines can output power in other forms in addition to walking power to fulfil other functions besides walking, the electric machines can be considered as riding electric machines, such as riding snow throwers, riding agricultural machines, riding mops, riding sweepers and the like. In fact, as long as these tools include the substance described below in this disclosure, they all fall within the scope of this disclosure. 
     In order to facilitate the description of the technical solution of the present disclosure, the front side, the rear side, the upper side, the lower side, the left side, and the right side are defined as shown in  FIG.  1   . 
     As shown in  FIGS.  1 - 12   , the electric riding lawn mower  100  includes a main frame  11 , a seat  12 , a power output assembly  13 , a walking assembly  14 , an operating assembly  15 , and a power supply device  16 . 
     The main frame  11  is used to carry various modules of the electric riding lawn mower  100 . Specifically, the main frame is used to support the seat  12 , the power output assembly  13 , the walking assembly  14 , the operating assembly  15 , and the power supply device  16 , and the like. The main frame  11  extends generally in the front-rear direction. Specifically, the main frame  11  extends at least partially in a direction parallel to a first straight line  101  in the front-rear direction. The main frame  11  includes a frame  11   a  and a base  11   b . The frame  11   a  includes a first arm  111 , a second arm  112 , and a connecting arm  113  that connects the first arm  111  and the second arm  112 . The connecting arm  113  connects the first arm  111  and the second arm  112  such that the first arm  111 , the second arm  112 , and the connecting arm  113  constitute a frame  11   a  that supports the base  11   b . The first arm  111  and the second arm  112  may be in the front-rear direction. In the present example, the connecting arm  113  extends in the left-right direction; the number of the connecting arms  113  is two. One of the connecting arms  113  connects the first arm  111  and the second arm  112  at the front ends thereof, and the other connecting arm  113  connects the first arm  111  and the second arm  112  at the rear ends thereof, such that the first arm  111 , the second arm  112  and the two connecting arms  113  form a substantially rectangular frame  11   a . It is to be understood that the structure of the first arm  111 , the second arm  112  and the two connecting arms  113  is not limited thereto, and the structure of the frame  11   a  is not limited thereto. The frame  11   a  surrounds the base  11   b , and the shape of the base  11   b  is adapted to the shape of the frame  11   a . In the front-rear direction, the base  11   b  is provided at the front of the frame  11   a , the base  11   b  fills the front portion of the rectangular formed by the surrounding frame  11   a , and the base  11   b  is at least partially extended in a plane extending in the front-rear direction, and the base  11   b  serves as a work platform to support the user&#39;s feet and some mechanisms that can be operated with the user&#39;s feet. The seat  12  is for a user to ride, and the seat  12  is mounted to the main frame  11 . The seat  12  is slidable with respect to the main frame  11  in the direction of the first straight line  101 , so that the seat  12  can be moved forward or backward, so that the user can adjust the position of the seat  12  in the front-rear direction according to the user&#39;s height and usage habits, aiding comfort of the electric riding lawn mower  100 . The seat  12  specifically includes a bottom portion  121  and a backrest  122 . The bottom portion  121  extends substantially in the front-rear direction, and the backrest portion  122  extends upward from the bottom portion  121 . As shown in  FIGS.  1  and  3   , when the user sits on the seat  12 , the user faces the forward direction of the electric riding lawn mower  100 , i.e., the user faces the front side. The frame  11   a  can support the seat  12 , it should be understood that the frame  11   a  may directly support the seat  12 , and the frame  11   a  may also indirectly support the seat  12  by connecting to other structures. The seat  12  is provided on the upper side of the frame  11   a . In the front-rear direction, at least half of the seat  12  is disposed on the rear side of the base  11   b , so that when the user sits on the seat  12 , the user&#39;s feet can be placed on the base  11   b  on the front side of the seat  12 . In this way, on the one hand, the weight of the whole machine can be reduced, and the cost can be saved; on the other hand, the lower side of the seat  12  can free more space to set the other two parts, thereby saving space. 
     The power output assembly  13  includes an output member for outputting power to achieve a mechanical function. For example, in the present example, the output member may specifically be a mowing member  131 . The power outputted by the power output assembly  13  is the power other than enabling the electric riding lawn mower  100  to walk on the ground, and different output members enable the power output assembly  13  to perform different functions, for example, the output member may blow the snow, the output member may sweep the ground, the output member may also plow the field, etc. 
     In the present example, the output member is the mowing element  131 , which can realize the function of trimming the lawn, cutting the weeds, and the like. Specifically, the power output assembly  13  is also connected to the main frame  11 , and in the present example, the power output assembly  13  can be specifically mounted to the lower side of the main frame  11 . It should be understood that the main frame  11  may be directly connected to the power output assembly  13 , and may also be indirectly connected through other connection structures to the power output assembly. 
     The power output assembly  13  is disposed substantially on the lower side of the main frame  11 , which effectively utilizes the space on the lower side of the main frame  11 , and reduces the size of the entire electric riding lawn mower  100  in the front-rear direction such that the whole structure is more compact. Furthermore, it also reduces the center of gravity G 1  of the electric riding lawn mower  100 , improves the stability of the electric riding lawn mower  100 , and avoids the problem of machine rollover and backward turning during climbing. 
     The power output assembly  13  further includes: a first motor  132  and a chassis  133 . The mowing element  131  is used to implement the mowing function; the first motor  132  is used to drive the mowing element  131  to rotate at a high speed; the chassis  133  is formed with an accommodation space to accommodate at least a portion of the first motor  132  and at least a portion of the mowing element  131 . The power output assembly  13  may include one or more mowing element  131 , and respectively, the number of the first motors  132  can correspond to the mowing element  131 . For example, in the present example, the number of mowing elements  131  is two, which increases the cutting range of the electric riding lawn mower  100 , thereby improving the cutting efficiency. 
     The walking assembly  14  is used to enable the electric riding lawn mower  100  to walk on the lawn and on the ground. In the up-down direction, the walking assembly  14  is also capable of supporting the main frame  11  and the various components on the main frame  11 . The walking assembly  14  may specifically include a first travelling wheel  141  and a second travelling wheel  142 . The first travelling wheel  141  is disposed on the front side of the second travelling wheel  142  in the front-rear direction. Therefore, the first travelling wheel  141  may also be defined as the front travelling wheel, and the second travelling wheel  142  may also be defined as the rear travelling wheel. In the present example, the number of the first travelling wheels  141  is 2, and the number of the second travelling wheels  142  is also 2, which can improve the stability of the electric riding lawn mower  100  in the left-right direction and avoid rollovers on the ground or up the hill. In fact, the walking assembly  14  may also include only one first travelling wheel  141  and two second travelling wheels  142 ; alternatively, the walking assembly  14  may include two first travelling wheels  141  and one second travelling wheel  142 ; wherein in the direction along the first straight line  101 , the power output assembly  13  is at least partially disposed between the first travelling wheel  141  and the second travelling wheel  142 . 
     Further, the power output assembly  13  is disposed substantially between the first travelling wheel  141  and the second travelling wheel  142 ; in the direction along the first straight line  101 , the seat  12  is also at least partially disposed between the first travelling wheel  141  and the second travelling wheel  142 , so that the center of gravity G 1  of the electric riding lawn mower  100  is located between the first travelling wheel  141  and the second travelling wheel  142  in the direction of the first straight line  101 , thereby improving the balance performance of the whole machine. Further, in the direction along the first straight line  101 , the seat  12  is closer to the second travelling wheel  142  and further from the first travelling wheel  141 , so that the electric riding lawn mower  100  can be effectively prevented from rollover during climbing. In the left-right direction, the two first travelling wheels  141  are respectively located at two sides of the main frame  11 , and the two second travelling wheels  142  are also respectively located at two sides of the main frame  11 ; that is, the projections of the two first walking wheels  141  in a plane perpendicular to the up-down direction are outside the projection of the main frame  11  in the plane, and the projections of the two second walking wheels  142  in the plane are also located outside the projection of the main frame  11  in the plane. In this way, the main load-bearing portion of the electric riding lawn mower  100  can be placed between the two first travelling wheels  141  and also between the two second travelling wheels  142 , so that the electric riding lawn mower  100  can be further effectively prevented from rolling over. 
     The first travelling wheel  141  may specifically be a universal wheel that can rotate about the first axis  102 . The first travelling wheel  141  has a first diameter. It can be understood that since the first travelling wheel  141  is a universal wheel, the electric riding lawn mower  100  can turn, and when the electric riding lawn mower  100  turns, the first axis  102  of first travelling wheel  141  also rotates, and the orientation of the first travelling wheel  141  rotates. The walking assembly  14  also includes a second motor  143  for driving the second travelling wheel  142  to rotate about the second axis  103 . The drive from the second motor  143  allows the walking assembly to drive the entire electric riding lawn mower  100  to walk on the ground. In this example, the second motor  143  is independent of the first motor  132  that drives the mowing element  131 , so that the structure of the whole machine is simpler and the driving is more convenient. The number of the second motors  143  is also two, and the two second motors  143  are capable of driving the two second travelling wheels  142  respectively. Thus, when the two second motors  143  drive the respective second travelling wheels  142  at different rotational speeds, a speed difference is generated between the two second travelling wheels  142 , thereby causing the electric riding lawn mower  100  to turn. The second travelling wheel  142  has a second diameter, and the second diameter of the second travelling wheel  142  is greater than the first diameter of the first travelling wheel  141 . Wherein, the second diameter of the second travelling wheel  142 , the ratio of the second diameter of the second travelling wheel  142  to the first diameter of the first travelling wheel  141  is greater than or equal to 1.4 and less than or equal to 2, such that the second diameter of the second travelling wheel  142  is larger than the first diameter of the first travelling wheel  141 , so that the electric riding lawn mower  100  is less likely to roll backward when climbing uphill. Of course, the second diameter of the second travelling wheel  142  cannot be excessively larger than the first diameter of the first travelling wheel  141  to avoid the risk of the electric riding lawn mower  100  rolling forward on the downhill slope. 
     In the present example, the distance between the second travelling wheel  142  and the center of the two second travelling wheels  142  is defined as c 1 , i.e., half of the distance between the two second travelling wheels  142  is considered to be c 1 . In the present example, with a large number of modelling, test analyses, theoretical analysis, and creative work on the electric riding lawn mower  100 , it is concluded that in order to avoid rollover when the electric riding lawn mower  100  climbs the uphill, the ratio of the distance c 1  between the second travelling wheel  142  and the center of the two second travelling wheels  142  to the second diameter of the second travelling wheel  142  is greater than or equal to 0.5 and less than or equal to 1, such that the distance c 1  between the second travelling wheel  142  and the center of the two second travelling wheels  142  is not excessively large, and the turning radius of the entire electric riding lawn mower  100  can be reduced, thereby making the electric riding lawn mower  100  turns faster. 
     Further, the distance between the center of gravity G 1  of the electric riding lawn mower  100  and the two second travelling wheels  142  in the up-down direction is defined as h 1 . The ratio of the distance h 1  to the second diameter of the second travelling wheel  142  is greater than or equal to 0.5 and less than or equal to 0.5 and less than or equal to 1, such that when the second diameter of the second travelling wheel  142  is fixed, the center of gravity G 1  of the electric riding lawn mower  100  can be placed in a reasonable position in the up-down direction. Therefore, the risk of rollover of the electric riding lawn mower  100  during climbing is reduced. The position of the center of gravity G 1  of the electric riding lawn mower  100  can be reasonably improved as the second diameter of the second travelling wheel  142  is increased. In the present example, the ratio of the distance h 1  between the center of gravity G 1  of the electric riding lawn mower  100  and the center of the two second travelling wheels  142  in the up-down direction to the distance c 1  between the second travelling wheel  142  and the center of the two second travelling wheels  142  is greater than or equal to k1 and less than or equal to k2, that is, k1≤h1/c1≥k2, and the setting of k1 and k2 is related to the dimension of the second diameter of the second travelling wheel  142 . Thus, when the second diameter of the second travelling wheel  142  is set, k1 and k2 can also be set to a reasonable value. Thus, when the distance c 1  between the second travelling wheel  142  and the center of the two second travelling wheels  142  is set small, the rollover issue during climbing can be alleviated by lowering the center of gravity G 1  of the electric riding lawn mower  100 . 
     When the center of gravity G 1  of the electric riding lawn mower  100  is set high, the distance c 1  between the second travelling wheel  142  and the center of the two second travelling wheels  142  can be increased to prevent the electric riding lawn mower  100  from rollover during climbing. For example, in the present example, k1 has a value of 0.6 and k2 has a value of 1.1, such that 0.6≤h 1 /c 1 ≥1.1. More specifically, in a direction perpendicular to the first straight line  101  and perpendicular to the second axis  103 , the distance L 1  between the center of gravity G 1  of the electric riding lawn mower  100  and the second axis  103  is greater than or equal to 0 and less than or equal to 150 mm, that is, the distance L 1  is greater than or equal to 0 and less than or equal to 150 mm in the up-down direction, so that the center of gravity G 1  of the electric riding lawn mower  100  is not too high in the up-down direction. When the user sits on the seat  12 , the center of gravity will rise to some extent, but since the center of gravity G 1  of the electric riding lawn mower  100  is set low, the center of gravity G 2  of the entirety formed by the user and the electric riding lawn mower  100  is not too high in the up-down direction, which improves stability. It should be noted that, in the present disclosure, the distance between two points, lines and planes in a certain direction refers to the projection distance of the spatial distance between them in the specified direction. 
     The operating assembly  15  is for user operation to control the electric riding lawn mower  100  to walk and output power. The operating assembly  15  can include a first operating element and a second operating element  152 . The first operating element is for user to operate to activate the first motor  132  in the power output assembly  13  to control the mowing element  131  to mow. The second operating element  152  is for user to operate to activate the second motor  143  in the walking assembly  14  to control the electric riding lawn mower  100  to walk on the lawn or on the ground. The number of second operating elements  152  is two. In the present example, two of the second operating elements  152  are used to respectively control two of the second motors  143 . The two second operating members  152  are respectively disposed on both sides of the seat  12  such that the two second operating members  152  on both sides can be more conveniently operated when the user sits on the seat  12 . 
     The power supply device  16  is for supplying power to the first motor  132  and the second motor  143 . The power supply device  16  includes a plurality of first battery packs  161 . Compared with the conventional riding lawn mowers powered by gasoline, the electric riding lawn mower  100  powered by the first battery pack  161  is more environmental friendly and the later usage cost is also lower. In the long run, the cost of the electric riding lawn mower using the first battery pack  161  will be lower. Compared with riding lawn mowers powered by alternating current, the first battery pack  161  supplies power without using a long power cord, which is safer and more convenient for mowing. In the present disclosure, the first battery pack  161  is a lithium battery pack, and the first battery pack  161  is lighter in weight, higher in charge and discharge efficiency, and longer in service life than other types of battery packs (for example, lead-acid batteries). Further, in the present example, the voltage of the first battery pack  161  is 56V. Of course, it can be understood that the voltage value of the first battery pack  161  is not limited thereto. 
     The power supply device  16  is disposed on the rear side of the seat  12 , and in the height direction, the upper end of the power supply device  16  is shorter than the seat  12 , or the upper end of the power supply device  16  is substantially of the same height to the seat  12 ; further, in the height direction, the upper end of the first battery pack  161  is shorter than the seat  12 , or the first battery pack  161  is substantially of the same height to the seat  12 . 
     In the present example, the first battery pack  161  can be detached from the main frame  11  by the user, that is, the first battery pack  161  for powering the electric riding lawn mower  100  is detachably mounted to the main frame  11 , so that when the power of the first battery pack  161  is insufficient, the user can detach the first battery pack  161  for charging, instead of directly charging the electric riding lawn mower  100 , thereby improving operational convenience; in addition, when the first battery pack  161  is damaged, the user can conveniently disassemble the first battery pack  161  for maintenance or directly replace the first battery pack  161 , which avoids fixing or replacing the riding lawn mower whose battery pack cannot be disassembled, and thus reduces the cost of maintenance at a later stage. Moreover, the ability to disassemble the first battery pack  161  also allows for differentiated design of products for different platforms or regions, making quality control and manufacture of the entire electric riding lawn mower  100  easier. Still alternatively, the power tool system  1  shown in  FIG.  8    includes the electric riding lawn mower  100  and a power tool  100   a  in the present disclosure. Wherein, the first battery pack  161  in the power supply device  16  for supplying power to the electric riding lawn mower  100  can be detached and mounted into the electric power tool  100   a , so that the first battery pack  161  can also power the electric power tool  100   a , that is, the first battery pack  161  in the power supply device  16  in the present disclosure can be applied not only to the electric riding lawn mower  100  but also to other electric power tools  100   a , thereby improving the adaptability of the first battery pack  161  and the ability of the electric riding lawn mower  100  to adapt to the first battery pack  161 . Thus, when the electric riding lawn mower  100  is not in use, the user can disassemble the first battery pack  161  for use in other electric power tools  100   a , thereby avoiding waste of resources and reducing usage cost. In other words, when the user needs to use the electric riding lawn mower  100 , the user can borrow the battery pack in other power tool  100   a  as the first battery pack  161 . In the present example, the first battery pack  161  is configured to be pluggably mounted by the user to the electric riding lawn mower  100 , and the first battery pack  161  is attached and detached by plugging and unplugging, making the operation more convenient, and the positioning of the first battery pack  161  more accurate. 
     Further, as shown in  FIG.  9   , the first battery pack  161  includes a plurality of battery cells  161   a  connected in series, in parallel, or in a combination of series and parallel. The plurality of battery cells  161   a  are combined in one battery case to constitute a whole, and the battery cells  161   a  may specifically be lithium-based. Specifically, the power tool  100   a  may be a garden tool such as a string trimmer, a hedge trimmer, a blower or a chain saw, a torque output tool such as an electric drill or an electric hammer, a sawing tool such as an electric circular saw, a curve saw or a reciprocating saw, or a grinding tool such as an angle grinder or a sander. Of course, in other examples, the first battery pack  161  can also be configured to power a hand-push power tool, such as a hand-push lawn mower, a hand-push snow blower, and the like. Thus, the first battery pack  161  of the present disclosure adapted to the electric riding lawn mower  100  can be pulled out by the user to be applied to the above power tool  100   a , in other words, the user can borrow the battery packs in the power tool  100   a  as the first battery pack  161  to power the electric riding lawn mower  100 , thereby improving the versatility of the electric riding lawn mower  100  and reducing the usage cost. 
     In the present example, the area surrounded by the frame  11   a  may be divided into a front portion, a middle portion, and a rear portion in the front-rear direction. The base  11   b  only fills the front portion of the frame  11   a , and the middle portion and the rear portion of the frame  11   a  are not provided with the base  11   b , and the seat  12  is provided on the upper side of the middle portion of the frame  11   a , so that the lower side of the seat  12  and the middle portion of the frame  11   a  have more space to for other components, so that the structure of the whole machine is more compact. The rear portion of the frame  11   a  and the rear side of the seat have a sufficiently large accommodation space which can be used to house the power supply device  16 . In the present example, the number of the first battery packs  161  included in the power supply device  16  is plural; the number of the first battery packs  161  is at least 4; the number of the first battery packs  161  is greater than or equal to 4 and less than or equal to 10. Further, in the present example, the number of the first battery packs  161  is exemplified by six, so that the electric riding lawn mower  100  is powered by the plurality of first battery packs  161 , and on the other hand, the endurance capability of the entire electric riding lawn mower  100  is improved, thereby avoiding the trouble of repeated charging, and improving the efficiency of work; on the other hand, the power supply device  16  includes a plurality of first battery packs  161 , and thus the weight of the power supply device  16  is heavier. For the entire electric riding lawn mower  100 , the weight of the power supply device  16  makes up a large proportion of the weight of the entire electric riding lawn mower  100 . Therefore, disposing the power supply device  16  in the rear end of the frame  11   a  and on the rear side of the seat  12  locates the power supply device  16  at the rear end of the electric riding lawn mower  100 , thereby enabling the center of gravity G 1  of the electric riding lawn mower  100  to move backward, further reducing the possibility of rolling over backwards when the electric riding lawn mower  100  climbs the slope, and improving the safety performance. 
     Further, the center of gravity G 1  of the electric riding lawn mower  100  is disposed on the lower side of the seat  12 . For the entire electric riding lawn mower  100 , the seat  12  is substantially in the middle position in the front-rear direction, and the center of gravity G 1  of the electric riding lawn mower  100  is disposed on the lower side of the seat  12 ; thus, the user sitting on the seat  12  only causes the center of gravity G 2  of both the user and the electric riding lawn mower  100  to change only in the up-down direction with respect to the center of gravity G 1  of the electric riding lawn mower  100  when the user is not sitting on the seat  12 . The position of the center of gravity G 2  does not change in the front-rear direction and the left-right direction, so that the risk of rollover caused by the user sitting on the seat  12  can be further reduced. The center of gravity G 1  of the electric riding lawn mower  100  is disposed on the lower side of the seat  12 . Therefore, regardless of whether a user with a relatively heavy weight or a user with a relatively light weight operates the electric riding lawn mower  100 , the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  will not change in the left-right direction and the front-rear direction, thereby improving the stability of the electric riding lawn mower  100 . 
     As described above, when the center of gravity G 1  of the electric riding lawn mower  100  is lowered in the up-down direction, and if the user sits on the seat  12 , the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  will also decline relatively. Thus, when the user rides the electric riding lawn mower  100  of the present disclosure to climb a slope, the second travelling wheel  142  has a contact point P with the slope surface, and the projection distance between the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the contact point P in the horizontal direction is B. In the direction perpendicular to the first line  101  and perpendicular to the second axis  103 , the distance between the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the slope surface is h, that is, in the direction perpendicular to the slope surface, the distance between the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the slope surface is h. Wherein, the following relationship is satisfied between the projection distance B and the distance h:
 
 B=A *cos α− h *sin α,
 
     Wherein, A is the distance between center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the second axis  103  of the second travelling wheel  142 ; the angle α is the angle between the slope surface and the horizontal plane. 
     From the above relationship between the projection distance B and the distance h, the distance A between center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the second axis  103  of the second travelling wheel  142  is fixed; and when the angle α formed between the slope surface and the horizontal plane is also fixed, the smaller the distance h between the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the slope surface in a direction perpendicular to the first straight line  101  and perpendicular to the second axis  103 , the larger the projection distance B between the center of gravity G 2  of the entirety constructed by the user and the electric riding lawn mower  100  and the contact point P in the horizontal direction, which makes the electric riding lawn mower  100  easier to climb and less likely to roll over. 
     The chassis  133  and the main frame  11  also need to be separated by a certain distance to allow the chassis  133  to waggle up and down. Specifically, the distance between the chassis  133  and the main frame  11  should be greater than or equal to 20 mm and less than or equal to 60 mm. In another example, it is also necessary to make the distance between the mowing element  131  and the ground satisfy the requirement of mowing. Specifically, the distance between the mowing element  131  and the ground should be greater than or equal to 20 mm and less than or equal to 120 mm. In another example, in the present example, the power of the first motor  132  is greater than or equal to 500 W and less than or equal to 1500 W, and therefore, the size of the space inside the chassis  133  also needs to meet the size of the first motor  133 . 
     In the direction along the first straight line  101 , the distance L 2  between the center of gravity G 1  of the electric riding lawn mower  100  and the second axis  103  is greater than or equal to 0 and less than or equal to 400 mm, such that the electric riding lawn mower  100  is not likely to roll over during climbing. In the direction along the first straight line  101 , The ratio of the distance L 3  between the center of gravity G 1  of the electric riding lawn mower  100  and the first axis  102  to the distance L 2  between the center of gravity G 1  of the electric riding lawn mower  100  and the second axis  103  is greater than or equal to 2 and less than or equal to 4, so that the center of gravity G of the electric riding lawn mower  100  is set at a proper position in a direction along the first straight line  101 . Therefore, not only can the climbing ability be taken into account, but also the problem of rollover when climbing uphill can be taken into account, and the problem of the overturning when going downhill with the electric riding lawn mower  100  can also be avoided. 
     The power supply device  16  includes a battery compartment housing  16   a  that includes a main body portion  16   b  and a cover  16   c  that is pivotally coupled to the main body portion  16   b . The main body portion  16   b  may include a first battery compartment  162  for mounting the first battery pack  161 , and the power supply device  16  may include two or more first battery compartments  162 , and the number of the first battery compartments  162  may also be a specific plural. Specifically, in this example, the power supply device  16  includes six first battery compartments  162 , and the six first battery compartments  162  are disposed on the rear side of the seat  12  away from the first travelling wheel  141 , that is, in the direction of the first straight line  101 , the first battery compartment  162  and the first travelling wheel  141  are respectively disposed on both sides of the seat  12 . In this way, the weight of the electric riding lawn mower  100  can be shifted back, thereby increasing the positive pressure of the second travelling wheel  142  at the rear end to the ground, thereby increasing grip of the second travelling wheel  142  of the electric riding lawn mower  100 , and making climbing uphill easier. 
     Correspondingly, the power supply device  16  includes six first battery packs  161 , and each of the first battery packs  161  can be respectively mounted to each of the first battery compartments  162 . The first battery compartment  162  may be formed with a first groove  162   a . The first battery pack  161  can be detachably inserted into the first groove  162   a  along the direction of the second straight line  104 . The first battery pack  161  can also be pulled out of the first groove  162   a  along the direction of the second straight line  104 . The cover  16   c  has an open state and a closed state, and when the cover  16   c  is in the open state, the first groove  162   a  is opened and the user can insert the first battery pack  161  into the first groove  162   a ; when the cover  16   c  is in the closed state, the first groove  162   a  is closed to provide a certain protection to the first battery pack  161  located in the battery compartment housing  16   a . It can be understood that the first battery compartment  162  can also be provided with a guiding structure  162   b  for guiding the first battery pack  161  to be inserted into the first groove  162   a  in the direction of the second straight line  104 , such that the first battery pack  161  can be positioned more accurately in the first groove  162   a . The first battery compartment  162  may also be provided with a latch  162   c  for locking the first battery pack  161  in the first groove  162   a . The latch  162   c  can lock the first battery pack  161 , and allow the first battery pack  161  to be pulled out. In this way, the waggle of the first battery pack  161  can be avoided. The first battery compartment  162  may also be provided with a pop-up structure  162   d  for ejecting the first battery pack  161 , thereby enabling the user to pull out the first battery pack effortlessly. The first battery compartment  162  is further provided with an input terminal  162   e  to electrically connect to the first battery pack  161 , and the input terminal  162   e  is for introducing the electric energy output by the first battery pack  161  to the electric riding lawn mower  100 . 
     The direction of the second straight line  104  in which the first battery pack  161  is inserted into the first groove  162   a  obliquely intersects with the direction of the first straight line  101 . Further, between the direction of the second straight line  104  and the direction of the first straight line  101 , an angle greater than 60 degrees and less than 90 degrees may be formed, enabling the user to easily insert and remove the first battery pack  161  without squatting. That is, the angle formed between the direction of the second straight line  104  in which the first battery pack  161  is inserted into the first groove  162   a  and the straight line extending in the up-down direction is greater than 0 degrees and less than or equal to 30 degrees, so that the user can easily insert and remove the first battery pack  161  without bending largely, thereby making the operation more effortless, and avoiding the user twisting or bending the arm when pulling out the first battery pack  161 , thereby facilitating the human-machine experience. It can be understood that the six first battery compartments  162  can also be formed by a single larger battery compartment, that is, the power supply device  16  may include only one battery compartment, and the plurality of first battery packs  161  are all installed in this battery compartment. 
     Alternatively, the power supply device  16  may include only one first battery compartment  162 ; correspondingly, the power supply device  16  may include only one first battery pack  161 . That is to say, the number of the first battery compartments  162  and the number of the first battery packs  161  are not specifically limited, and the correspondence relationship between the first battery compartment  162  and the first battery pack  161  is not limited to the one-to-one correspondence relationship. It can be understood that, in other examples, the direction of the second straight line  104  in which the first battery pack  161  is inserted into the first groove  162   a  may also be perpendicular to the direction of the first straight line  101 , and the direction of the second straight line  104  in which the first battery pack  161  is inserted into the first groove  162   a  may also be parallel to the direction of the first straight line  101 . 
     In the example, the power supply device  16  includes six first battery packs  161 , and the six first battery packs  161  are disposed on the rear side of the seat  12 . The six first battery packs  161  are arranged in a regular shape on the rear side of the seat  12 . The first battery compartment  162  disposed on the rear side of the seat  12  is further disposed on the rear side of the second travelling wheel  142 . The first battery pack  161  has a height direction extending in the direction in which it is inserted into the first groove  162   a , and has a longitudinal direction and a width direction perpendicular to the height direction; the dimension of the first battery pack  161  in the longitudinal direction is greater than the dimension thereof in the width direction. In this example, when the first battery pack  161  is inserted into the first groove  162   a , the longitudinal direction of the first battery pack  161  and the second axis  103  of the second travelling wheel  142  are parallel to each other, that is, the longitudinal direction of the first battery pack  161  extends in the left-right direction. Thus, when the user needs to install or remove the first battery pack  161 , the user does not need to twist the wrist, which improves the comfort of operation. 
     More specifically, the six first battery packs  161  are arranged in three rows in the front-rear direction, and each row has two first battery packs  161  arranged in the left-right direction. The two first battery packs  161  disposed in the left-right direction are defined as one battery unit group, or form a modular power supply device, and the length of the first battery pack  161  in the left-right direction is greater than the width thereof in the front-rear direction. Thus, two first battery packs  161  are arranged on a straight line parallel to the left-right direction, and three first battery packs  161  are arranged on a straight line parallel to the front-rear direction, and the orientation of each first battery pack  161  is arranged such that its length in the left-right direction is also greater than its length in the front-rear direction. Thus, the dimension of the six first battery packs  161  is not excessively long in the front-rear direction so as not to increase the size of the entire electric riding lawn mower  100  in the front-rear direction; and also the dimension of the six first battery packs  161  is not too small in the left-right direction to effectively utilize the space occupied by the electric riding lawn mower  100  in the left-right direction. Thereby, the arrangement of the power supply device  16  is more reasonable, the space is saved, and the modularization is facilitated. Of course, it can be understood that when two first battery packs  161  in the power supply device  16  are used as one battery unit group, the power supply device  16  may also include two battery unit groups, and may further include three or more battery unit groups, thereby facilitating modularization of the power supply device  16  and implementation of a variety of configurations. 
     In the present example, the capacity of a first battery pack  161  is greater than or equal to 130 Wh and less than or equal to 1000 Wh. Further, the capacity of a first battery pack  161  is greater than or equal to 130 Wh and less than or equal to 500 Wh, so that the discharge time of the first battery pack  161  can also meet the most basic requirements even when only one first battery pack  161  is included in the power supply device  16 ; or, when the plurality of first battery packs  161  included in the power supply device  16  are out of power and the electric riding lawn mower  100  needs to perform mowing, one first battery pack  161  or two first battery packs  161  may be charged first, and after the charging is completed, the one first battery pack or the two first battery packs  161  are inserted to the first battery compartment  162  to supply power. Therefore, because the capacity of the first battery pack  161  is greater than or equal to 130 Wh, the discharge time of the first battery pack  161  can meet the urgent needs of the user to cut a part of the grass, in other words, does not delay the use. It can be understood that, in the present disclosure, when any of the first battery packs  161  is installed in the battery compartment housing  16   a , the electric riding lawn mower  100  can be operated, that is, in the present disclosure, the electric riding lawn mower  100  is not limited to operate only if all of the first battery compartments  162  are installed with the first battery packs  161  capable of supplying power. Alternatively, when the plurality of first battery packs  161  are mounted to the battery compartment housing  16   a , and some of the first battery packs  161  are depleted, the electric riding lawn mower  100  can still operate, thereby improving work efficiency. Further, in the present example, the weight of one first battery pack  161  is greater than or equal to 0.1 kg and less than or equal to 4 kg, which eases carrying difficulties due to the excessive weight of the first battery pack  161 . Further, for considerations to allow the electric riding lawn mower  100  of the present disclosure to borrow battery packs in other electric power tools, it is also necessary to make the weight of the first battery pack  161  equal to or greater than 0.1 kg and equal to or less than 4 kg. More preferably, the weight of the first battery pack  161  is greater than or equal to 1 kg and less than or equal to 4 kg, so that the first battery pack  161  can satisfy the capacity and discharge time demands when the weight of the first battery pack  161  is not excessively heavy. 
     On the other hand, the ratio of the discharge power of a single first battery pack  161  to the nominal voltage of the first battery pack  161  is greater than or equal to 10 W/V and less than or equal to 25 W/V, and further, the ratio of the discharge power of a single first battery pack  161  to the nominal voltage of the first battery pack  161  is greater than or equal to 12 W/V and less than or equal to 20 W/V. Specifically, the discharge power of the first battery pack  161  is greater than or equal to 500 W and less than or equal to 6500 W. Further, the discharge power of the first battery pack  161  is greater than or equal to 500 W and less than or equal to 3000 W, which enables the first battery pack  161  to adapt to the high power needs of the electric riding lawn mower  100  of the present disclosure. In this example, the power supply device  16  includes a plurality of first battery packs  161 , and the plurality of first battery packs  161  provide an overall discharge power of greater than or equal to 2000 W and less than or equal to 4000 W, which enables the electric riding lawn mower  100  to output high power, and last a long time, saving the trouble of repeated charging. 
     In a horizontal direction along the first straight line  101  or along a rotation axis perpendicular to the second axis  103 , the distance L 4  between the center C of the battery compartment housing  16   a  provided on the rear side of the seat  12  and the second axis  103  of the second walking wheel  142  is less than or equal to 500 mm. Alternatively, the horizontal distance between the center of gravity of the electric riding lawn mower  100  with the first battery pack  161  mounted and the center of the rotating shaft of the second travelling wheel  142  is less than or equal to 500 mm. Alternatively, the horizontal distance between the center of some of the first battery compartments  162  and the center of the rotating shaft of the second walking wheel  142  is less than or equal to 500 mm. Alternatively, the horizontal distance between the center of all of the first battery compartments  162  disposed on the rear side of the seat  12  and the rotating shaft of the second travelling wheel  142  is less than or equal to 500 mm. Further, In a horizontal direction along the first straight line  101  or along a rotation axis perpendicular to the second axis  103 , the distance L 4  between the center C of the battery compartment housing  16   a  provided on the rear side of the seat  12  and the second axis  103  of the second walking wheel  142  is less than or equal to 300 mm. Alternatively, the horizontal distance between the center of gravity of the electric riding lawn mower  100  with the first battery pack  161  mounted and the center of the rotating shaft of the second travelling wheel  142  is less than or equal to 300 mm. Alternatively, the horizontal distance between the center of some of the first battery compartments  162  and the center of the rotating shaft of the second walking wheel  142  is less than or equal to 300 mm. Alternatively, the horizontal distance between the center of all of the first battery compartments  162  disposed on the rear side of the seat  12  and the rotating shaft of the second travelling wheel  142  is less than or equal to 300 mm. This increases the positive pressure of the second travelling wheel  142  against the ground and the grip of the second travelling wheel  142 , and reduces the torque required for the electric riding lawn mower  100  in zero-turns to make zero-turns more flexible. The horizontal distance between one point and another point or line recited in the present disclosure refers to the projection distance between the two on the horizontal plane when the electric riding lawn mower  100  is placed on a horizontal ground. Similarly, the vertical distance between one point and another point or line recited in the present disclosure refers to the projection distance between the two on the vertical plane when the electric riding lawn mower  100  is placed on a horizontal ground. 
     That is to say, the distance L 4  between the center C of entirety constructed by some or all of the first battery compartment  162  provided on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm. When all of the first battery compartments  162  in the power supply device  16  are provided with the first battery packs  161 , the distance between the center of gravity G 3  of the power supply device  16  on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm. Therefore, this increases positive pressure of the second travelling wheel  142  on the ground and the friction between the second travelling wheel  142  and the slope surface when the electric riding lawn mower  100  climbs uphill, thereby improving the climbing ability of the riding electric lawn mower  100 , and avoiding slippage during walking on the ground or climbing up the hill; in addition, this reduces the torque required for the electric riding lawn mower  100  in zero-turns, allowing more flexible turns to be performed by the electric riding lawn mower  100 . 
     In a direction perpendicular to the first straight line  101  and perpendicular to the second axis  103 , the distance between the center C of the battery compartment housing  16   a  disposed on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm, that is, in the up-down direction, the distance between the center C of the battery compartment housing  16   a  disposed on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm. It can be understood that, in a direction perpendicular to the first straight line  101  and perpendicular to the second axis  103 , the distance between the center C of entirety constructed by some or all of the first battery compartment  162  provided on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm, that is, in the up-down direction, the distance between the center C of entirety constructed by some or all of the first battery compartment  162  provided on the rear side of the seat  12  and the second axis  103  of the second travelling wheel  142  is less than or equal to 300 mm. In other words, the vertical distance between the center of at least some of the first battery compartments  162  and the center of the rotating shaft of the second travelling wheel  142  is less than or equal to 300 mm. Or the distance between the center of gravity of the electric riding lawn mower  100  with the first battery pack  161  mounted and the center of the rotation axis of the second travelling wheel  142  is less than or equal to 300 mm. In other words, the vertical distance between the center C of all the first battery compartments  162  disposed on the rear side of the seat  12  and the rotating shaft of the second travelling wheel  142  is less than or equal to 300 mm. This helps lowering the center of gravity G 1  of the entire electric riding lawn mower  100 , thereby reduces the possibility of rollover to the back when the electric riding lawn mower  100  climbs uphill, the possibility of rollover to the front when the electric riding lawn mower  100  goes downhill, and the possibility of rollover to the side when the electric riding lawn mower  100  walks on uneven ground. 
     Further, the distance between the center of at least some of the first battery compartment  162  and the center of the rotation axis of the second walking wheel  142  in the left-right direction is less than 100 mm; in other words, the distance between the center of gravity of the electric riding lawn mower  100  installed with the first battery pack  161  and the center of the rotation axis of the second walking wheel  142  in the transverse direction of the riding type electric lawn mower  100  is less than 100 mm, so that the center of gravity of the whole machine is closer to the center axis  105  of the whole machine, so that the machine is less likely to tip over when travelling transversely or laterally on the slope. 
     In a direction parallel to the second axis  103 , the distance between the center C of the battery compartment housing  16   a  disposed on the rear side of the seat  12  and the center of the two second travelling wheels  142  is less than or equal to 100 mm; that is, in the left-right direction, the distance between the center C formed by all the numbers of the first battery compartments  162  disposed on the rear side of the seat  12  and the center of the two second travelling wheels  142  is less than or equal to 100 mm. This enables the center of the power supply device  16  to be placed as close as possible to the center axis  105 , particularly in the case where the shape of the power supply device  16  is relatively regular, which causes the center of gravity of the power supply device  16  to be placed as close as possible to the center axis  105 , to avoid the problem of rollover in the left-right direction when the electric riding lawn mower  100  travels laterally on the slope surface, thereby improving the stability performance of the electric riding lawn mower  100 . 
     As described above, the number of the second travelling wheels  142  is two, and the two second travelling wheels  142  are symmetrically disposed on both sides of a plane of symmetry, and in the present example, the entirety constructed by all of the first battery compartments  162  on the rear side of the seat  12  is symmetrically disposed about the plane of symmetry, thereby improving the balance performance of the whole machine. 
     Referring to  FIG.  12    or  FIG.  13   , in the example of the present disclosure, all the battery packs disposed on the rear side of the seat  12  are such that the center of at least some battery packs is located on the right side of the center axis  105  of the electric riding lawn mower  100 , and the center of the other battery packs is located on the left side of the center axis  105  of the electric riding lawn mower  100 . Here, the center axis  105  of the electric riding lawn mower  100  is parallel to the front-rear direction or the forward direction of the machine. In some other examples of the present disclosure, assuming that the electric riding lawn mower  100  employs at least one large-sized battery pack, a portion of the at least one battery pack disposed on the rear side of the seat  12  is disposed on the right side of the center axis  105  of the electric riding lawn mower  100 , and the other portion of the at least one battery pack is disposed on the left side of the center axis  105  of the electric riding lawn mower  100 . The battery pack is arranged such that the center of gravity of the electric riding lawn mower  100  is located near the center axis  105  or closer to the center axis  105  of the whole machine, which is advantageous for balancing the center of gravity of the electric riding lawn mower  100 . 
     As shown in  FIG.  13   , all the battery packs of the electric riding lawn mower  100  are provided, besides on the rear side of the seat  12  as shown in  FIG.  12   , on the front side of the seat  12 . Disposing some battery packs on the front side of the rotating shaft of the second travelling wheel  142 , and the other battery packs on the rear side of the rotating shaft of the second travelling wheel  142  increases the positive pressure of the second travelling wheel  142  against the ground and the grip of second travelling wheel  142 , and reduces the torque required for the electric riding lawn mower  100  in zero-turns to make zero-turns more flexible. In this example, the battery packs on the front side of the seat  12  may be fixedly mounted to the electric riding lawn mower  100 ; and the battery packs on the rear side of the seat may be detachably mounted to the electric riding lawn mower  100 . In some other examples of the present disclosure, if the battery pack provided in the electric riding lawn mower  100  is a large-sized battery pack, a portion of the large-sized battery pack is located on the front side of the rotating shaft of the second travelling wheel  142 , and the other portion of the large-sized battery pack is located on the front side of the rotating shaft of the second travelling wheel  142 , so as to increase the positive pressure of the second travelling wheel  142  against the ground and the grip of second travelling wheel  142 , and reduce the torque required for the whole machine in zero-turns to make zero-turns more flexible. 
     In order to prevent the first battery pack  161  from being detached from the first battery compartment  162 , a vibration damping device is further disposed between the power supply device  16  and the main frame  11 , so that the first battery pack  161  can be prevented from being detached from the first battery compartment  162 , thereby improving the effective electrical connection between the first battery pack  161  and the first battery compartment  162 . 
     When the first battery pack  161  is inserted into the first groove  162   a , the dimension of the cross section of the first battery pack  161  in a plane perpendicular to the direction of the second straight line  104  along the direction in the first straight line  101  is smaller than the dimension of the cross section along the direction perpendicular to the first straight line  101  and parallel to the plane, that is, when the first battery pack  161  is inserted into the first groove  162   a , the first battery pack  161  has a thinner dimension in the direction perpendicular the first straight line  101  than in the direction of the first straight line  101 , thereby facilitating the user to grasp the first battery pack  161  to insert the first battery pack  161  into the first groove  162   a  or pull it out from the first groove in  162   a.    
     The first battery pack  161  may specifically include a first battery pack housing  161   b  and a plurality of battery cells  161   a  disposed in the first battery pack housing  161   b . The direction in which the battery cells  161   a  extends in the first battery pack  161  is parallel to the direction of the second line  104  in which the first battery pack  161  is inserted into the first groove  162   a.    
     As shown in  FIG.  1   , the electric riding lawn mower  100  may further be provided with a grass collecting device  17  for collecting grass, and the grass collecting device  17  may be detachably connected to the main body portion of the electric riding lawn mower  100 . The grass collecting device  17  specifically includes a grass collecting basket  171  and a connecting pipe  172 ; the grass collecting basket  171  is for accommodating the cut grass clippings, and the connecting pipe  172  is connected to the bottom plate  133  and the grass collecting basket  171  to deliver the grass clippings to the grass collecting basket  171 . In the present example, the power supply device  16  is disposed on the rear side of the seat, and the power supply device  16  further includes a battery compartment housing  16   a . The plurality of first battery packs  161  of the power supply device  16  are arranged substantially in a plane perpendicular to the up-down direction. This allows the shape of the battery compartment housing  16   a  to be substantially disposed in the plane such that the upper side of the cover  16   c  of the battery compartment housing  16   a  and the rear side of the seat  12  have a large free space, which allows the grass basket  171  to be placed on the upper side of the battery compartment housing  16   a , thereby saving space, and making the structure of the whole machine more reasonable and more compact. Furthermore, due to its light weight, placing the grass basket  171  on the rear end of the electric riding lawn mower  100  does not have a great impact on the center of gravity of the whole machine. Therefore, it can be understood that the center of gravity of the electric riding lawn mower  100  or the center of gravity of the entirety of the electric riding lawn mower  100  and the user can be understood as either including the grass collecting device  17  or not including the grass collecting device  17 . 
     The electric riding lawn mower  200  of the second example shown in  FIG.  13    may have the same main frame  21 , seat  22 , power output assembly  23 , walking assembly  24  and operating assembly  25  as the electric riding lawn mower in the first example. This example only differs from the first example in that the power supply device  26  includes a second battery pack  263  besides the first battery compartment  262  and the first battery pack  261  as in the first example. The parts of the first example that are compatible with this example can be applied to this example, and details are not described herein. 
     In the present example, the second battery pack  263  can be disposed on the lower side of the seat  22 , so that the center of gravity G of the whole machine in the direction along the first straight line  201  can be as close as possible to the seat  22  and the first travelling wheel  241  in order to effectively avoid the problem of tilting up when the electric riding lawn mower  200  climbs uphill; and this also increases the positive pressure of the first travelling wheel  241  against the ground and the grip of the first travelling wheel  241  to prevent the electric riding lawn mower  200  from slippage when walking on the ground; further, especially when the rear end of the electric riding lawn mower  200  is provided with the grass collecting device, the structure of the second battery pack  263  being disposed on the lower side of the seat  22  can effectively reduce the center of gravity G of the electric riding lawn mower  200 , thereby improving the stability of the whole machine. Further, the second battery pack  263  is also disposed on the front side of the second travelling wheel  242 . 
     In addition, in the example, the second battery pack  263  may be fixedly mounted to the main frame  21 , that is, the second battery pack  263  is not quickly removable by the user without using auxiliary tools, so that the second battery pack  263  can be fixed on the main frame  21  to continuously supply power to the electric riding lawn mower  200 , thereby avoiding the situation when both the first battery pack  261  and the second battery pack  263  in the power supply device  26  are removed by the user such that the walking assembly  14  does not have power supply and that the electric riding lawn mower  200  cannot walk. Of course, it can be understood that the second battery pack  263  can also be configured to be detachable or pluggable by the user. 
     The position of the second battery pack  263  is not limited to being disposed on the lower side of the seat  22 , in fact, as long as it is distinguished from the position of the first battery pack  261  because of considerations in balance performance or structural adaptation of the whole machine, it is within the scope of this disclosure. 
     In the present example, only one second battery pack  263  is provided on the lower side of the seat  22 . Of course, it can be understood that the second battery pack  263  on the lower side of the seat  22  may also be two or more. In the direction perpendicular to the first line  201  and the first axis  202 , the distance between the center of gravity of the entirety formed by all the battery packs in the power supply device  16  and the second axis  203  is less than 300 mm, that is, the distance between the center of gravity of the entirety formed by all the first battery packs  261  plus all the second battery packs  263  and the second axis  203  is less than 300 mm, such that the center of gravity of the entire electric riding lawn mower  200  can be lowered, thereby avoiding the problem of rollover on the slope. 
     In addition, in other examples, it is also possible to configure one or more of the first battery packs  261  disposed on the rear side of the seat  22  to be fixedly mounted to the main frame  21 , which also prevents the electric riding lawn mower  200  from the problem of being unable to walk due to the lack of power source. 
     In the third example shown in  FIG.  14   , the electric riding lawn mower  300  may have the same main frame  31 , seat  32 , power output assembly  33 , walking assembly  34  and operating assembly  35  as the electric riding lawn mower  100  of the first example. This example only differs from the first example in that the power supply device  36  includes only a first battery pack  361  having a larger capacity, and the first battery pack  361  can be detachably coupled to electric riding lawn mower  300  with a pluggable approach performed by the user. In the fourth example shown in  FIG.  15   , the electric riding lawn mower  400  may have the same main frame  41 , seat  42 , power output assembly  43 , walking assembly  44  and operating assembly  45  as the electric riding lawn mower  100  of the first example. This example only differs from the first example in that the power supply device  46  includes a power supply interface  46   a  for connecting a backpack power supply device  410  such that when the user sits in the seat  42 , the user can carry the backpack power supply device  410  on the back to facilitate the operation of the electric riding lawn mower  400 . 
     The basic principles, main features and advantages of the present disclosure have been shown and described above. It should be understood by those skilled in the art that the above-described examples are not intended to limit the disclosure in any way, and the technical solutions obtained by means of equivalent replacement or equivalent transformation are all within the scope of the disclosure. It will also be understood that the present disclosure provides an electric riding lawn mower with better adaptability and less usage cost.