Patent Description:
The present application relates to a garden tool, for example, a chain saw.

As a garden tool, a chain saw can be operated by a user to cut workpieces. For the chain saw, a chain is driven by an electric motor to rotate to cut a workpiece such as wood. To satisfy power output, the chain saw generally includes components such as an electric motor which can output relatively high power, a transmission mechanism, an oil can, and a power supply. When the preceding components are mounted in a housing, the chain saw is caused to occupy a relatively large space and the whole machine is relatively bulky, which brings relatively great tiredness to the user operating for a long time. When operating the chain saw, the user is continuously in adjusted positions. In this case, the chain saw needs to be stored or connected to a strap or another connector. Moreover, since the chain saw is hung or stored on the user, a relatively large volume has a relatively great influence on the movement of the user.

A chain saw according to the preamble of claim <NUM> is known from <CIT>.

The present application provides a chain saw which has a compact structure and is convenient to store, where the chain saw can be conveniently hung or stored.

According to the invention, there is provided a chain saw comprising a housing extending substantially along a front and rear direction and formed with an accommodation space; an electric motor at least partially disposed in the accommodation space; a transmission system connected to the electric motor and capable of outputting a driving force; a control system including a circuit board assembly extending in a plane; and a power supply assembly disposed on a rear side of the housing and used for powering the electric motor. The circuit board assembly obliquely intersects with a first straight line extending along the front and rear direction; in a direction of a second straight line perpendicular to a direction of the first straight line and extending along an up and down direction, the electric motor has a projection surface perpendicular to the direction of the second straight line and the circuit board assembly has a first projection surface perpendicular to the direction of the second straight line; and the projection surface of the electric motor at least partially overlaps the first projection surface of the circuit board assembly; and in the direction of the first straight line, the power supply assembly has a projection surface perpendicular to the direction of the first straight line and the circuit board assembly has a second projection surface
perpendicular to the direction of the first straight line; and the projection surface of the power supply assembly at least partially overlaps the second projection surface of the circuit
board assembly.

In an example, in the direction of the second straight line, the transmission system has a projection surface perpendicular to the direction of the second straight line and the circuit board assembly has the projection surface perpendicular to the direction of the second straight line; and the projection surface of the transmission system at least partially overlaps the projection surface of the circuit board assembly.

In an example, the electric motor is an external rotor electric motor, and a ratio of a mass of the electric motor to a mass of the chain saw is greater than or equal to <NUM> and less than or equal to <NUM>.

In an example, an oil pumping system which includes an oil can is further included, where the housing is formed with an opening communicating with an outside along both the front and rear direction and a left and right direction, and the oil can is disposed in the accommodation space and seals at least part of the opening.

In an example, the oil pumping system, the transmission system, the control system, the electric motor, and the power supply assembly are sequentially arranged along the front and rear direction.

In an example, the housing further includes an air inlet and an air outlet, where when the chain saw is running, a heat dissipation air path flowing in from the air inlet and flowing out from the air outlet is capable of being formed, and the heat dissipation air path is capable of flowing through the transmission system and the control system simultaneously.

In an example, the air outlet is configured to have a first blowing direction in which air is capable of being blown forward and a second blowing direction in which the air is capable of being blown backward.

In an example, a guide plate connected to the housing and a chain distributed around the guide plate are further included, where the transmission system includes a drive shaft capable of driving the chain to rotate; the chain saw further includes a cover plate capable of sealing at least part of the guide plate and at least part of the chain, where the cover plate and the housing are connected to each other and form a chip discharge space, and the drive shaft is at least partially disposed in the chip discharge space; and the electric motor includes an electric motor shaft disposed away from the chip discharge space.

In an example, the transmission system includes a gearbox distributed along the front and rear direction, where the electric motor and an output shaft are disposed on the same side of the gearbox.

In an example, a length of the chain saw in the front and rear direction is less than or equal to <NUM>, and a width of the chain saw in a left and right direction is less than or equal to <NUM>.

An example provides a chain saw. The chain saw includes: a housing extending substantially along a front and rear direction and formed with an accommodation space; an electric motor at least partially disposed in the accommodation space; a transmission system connected to the electric motor and capable of outputting a driving force; a control system including a circuit board assembly extending in a plane; and a power supply assembly disposed on a rear side of the housing and used for powering the electric motor. The circuit board assembly obliquely intersects with a first straight line extending along the front and rear direction; in a direction of a second straight line perpendicular to a direction of the first straight line and extending along an up and down direction, the electric motor has a projection surface along the direction of the second straight line, wherein the projection surface is perpendicular to the direction of the second straight line, and the circuit board assembly has a projection surface along the direction of the second straight line, wherein the projection surface is perpendicular to the direction of the second straight line; and the projection surface of the electric motor along the direction of the second straight line at least partially overlaps the projection surface of the circuit board assembly along the direction of the second straight line; the power supply assembly has a projection surface along the direction of the first straight line, wherein the projection surface is perpendicular to the direction of the first straight line, and the circuit board assembly has a projection surface along the direction of the first straight line, wherein the projection surface is perpendicular to the direction of the first straight line; and the projection surface of the power supply assembly along the direction of the first straight line at least partially overlaps the projection surface of the circuit board assembly along the direction of the first straight line; and the housing further includes a lower bottom surface perpendicular to the up and down direction, the lower bottom surface extends substantially in a plane, and the housing is further recessed away from the lower bottom surface so that a hook is formed, wherein the hook is disposed in a range of a space between the lower bottom surface and the housing.

In an example, the housing is further formed with a recess in which the hook is at least partially disposed.

In an example, the chain saw further includes a guide plate connected to the housing and a chain mounted to the guide plate and configured to rotate around the guide plate, where the hook is disposed toward a front end where the chain is disposed.

In an example, the housing is formed with a coupling portion to which the power supply assembly is mounted; and the housing is further formed with a guide slot guiding the power supply assembly to be mounted to the coupling portion.

In an example, the guide slot extends along a left and right direction perpendicular to the front and rear direction, and the power supply assembly is mounted to the coupling portion from a left side of the housing or the rear side of the housing.

In an example, the housing includes a first housing and a second housing, and the guide slot is disposed on the first housing or the second housing.

In an example, the housing includes a first housing and a second housing, and the guide slot is disposed on both the first housing and the second housing.

In an example, the housing is connected to or formed with <NUM> to <NUM> protection panels which form an accommodation cavity for protecting the power supply assembly.

In an example, the housing is formed with or connected with a main handle, and a center of gravity of a whole machine of the chain saw is located substantially near the main handle in the front and rear direction.

In an example, the housing includes a first housing and a second housing, where the first housing and the second housing are substantially symmetrical and are connected to each other to form the housing, and a center of gravity of the chain saw is located at a joint of the first housing and the second housing.

A chain saw <NUM> as shown in <FIG> and <FIG> includes a housing <NUM>, a chain <NUM>, a guide plate <NUM>, a locking mechanism <NUM>, and a power supply assembly <NUM>. The guide plate <NUM> is configured to guide the chain <NUM>, and the chain <NUM> rotates around the guide plate <NUM>. A locking device is mounted to a joint of the guide plate <NUM> and the housing <NUM> and is detachably coupled to the housing <NUM>. The locking device is configured to fix the guide plate <NUM> and tension the chain <NUM>. The power supply assembly <NUM> is connected to the housing to power the chain saw <NUM>. In an example, the housing <NUM> is formed with a coupling portion 11d connected to the chain saw <NUM>, and the power supply assembly <NUM> is mounted to the coupling portion 11d. The housing <NUM> is further formed with or connected to a main handle 11a and further formed with or connected to an auxiliary handle 11b on a front side of the main handle 11a. The main handle 11a includes a main grip for a user to hold, and the auxiliary handle 11b is provided with an auxiliary grip for the user to hold. The main handle 11a is connected to a control system <NUM> for the user to control power output of the chain saw <NUM>. The auxiliary handle 11b is carried by the user, so as to cooperate with the main handle 11a for the operation of the chain saw <NUM>.

As shown in <FIG>, directions including "up", "down", "front", "rear", "left", and "right" are defined. The guide plate <NUM> is distributed substantially along a front and rear direction. The main handle 11a is disposed on a rear side of the housing, the auxiliary handle 11b is disposed on the front side of the main handle 11a, and both the main handle 11a and the auxiliary handle 11b are disposed on an upper side of the housing. A shield is disposed on a front side of the auxiliary handle 11b and used for protecting the user from being cut by the chain <NUM> under the action of recoil when the chain saw <NUM> is operated.

As shown in <FIG>, the chain saw <NUM> further includes an oil pumping system <NUM>, a brake system, a transmission system <NUM>, and a power system <NUM>, where the oil pumping system <NUM>, the brake system, the transmission system <NUM>, the control system <NUM>, the power system <NUM>, and the power supply assembly <NUM> are sequentially disposed in the front and rear direction. In fact, the housing <NUM> is formed with a first accommodation space <NUM>, where the oil pumping system <NUM>, the brake system, the transmission system <NUM>, the control system <NUM>, and the power system <NUM> are at least partially disposed in the first accommodation space <NUM>. In an example, the oil pumping system <NUM> is disposed in the front side of the housing <NUM>, the power supply assembly <NUM> is disposed on the rear side of the housing <NUM>, and the transmission system <NUM> and the power system <NUM> are disposed between the oil pumping system <NUM> and the power supply assembly <NUM>. With such a design, a width of a whole machine of the chain saw <NUM> in a left and right direction can be set to <NUM> or less. In other examples, the width of the whole machine of the chain saw <NUM> in the left and right direction can be set to <NUM> or less. In addition, with the preceding arrangement, a length of the whole machine of the chain saw <NUM> in the front and rear direction can be set to <NUM> or less. In an example, the length of the whole machine of the chain saw <NUM> in the front and rear direction can be set to <NUM> or less. Thus, the whole machine of the chain saw <NUM> is very compact and has a lighter structure, which is convenient to operate and use.

As shown in <FIG>, the oil pumping system <NUM> includes an oil can <NUM> and an oil pump, where the oil pump is configured to connect the transmission system <NUM> to the oil can <NUM> and pump oil in the oil can <NUM> to the guide plate <NUM> of the chain saw <NUM> or the chain <NUM> of the chain saw <NUM>. In an example, a portion of the housing <NUM> where a front side of the housing <NUM> is connected to a right side of the housing <NUM> is provided with an opening <NUM>, and the oil can <NUM> is disposed in the housing <NUM> and at least seals the opening <NUM>. The opening <NUM> is configured to communicate with the outside in the front and rear direction of the housing <NUM> and the left and right direction of the housing <NUM> separately so that the oil can <NUM> disposed therein can be observed in both the front and rear direction and the left and right direction. In fact, four quadrants are included in a Cartesian coordinate system formed through the intersection of the front and rear direction with the left and right direction, the opening <NUM> is disposed in one of the four quadrants, and the oil can <NUM> can be observed in a range of <NUM>° in the quadrant where the opening <NUM> is located. In addition, in an up and down direction, the oil can <NUM> is also exposed in the range of <NUM>° of the quadrant where the opening <NUM> is located. Thus, the amount of oil in the oil can <NUM> is exposed on the front and right sides in a field of view that can be observed so that the oil can <NUM> has a better visual effect. In fact, no matter when the chain saw <NUM> is operated or the chain saw <NUM> is placed, the amount of oil in the oil can <NUM> can be easily observed so that the operation experience of the chain saw <NUM> is greatly optimized and the user does not need to shut down the chain saw <NUM> or deliberately seek a visual angle to observe the amount of oil in the oil can <NUM>. With this arrangement, a window of the oil can <NUM> becomes larger so that the user more easily observes the position of an oil level in the oil can <NUM>.

As shown in <FIG>, the housing <NUM> is further connected to or formed with a hook <NUM> configured to allow the chain saw <NUM> to be hung up. In an example, the housing <NUM> includes a lower bottom surface extending in a plane perpendicular to the up and down direction. In the up and down direction, the housing <NUM> further includes a recess <NUM> which is recessed upward from the lower bottom surface, and the recess <NUM> is also recessed backward at a position away from the lower bottom surface so that the housing <NUM> forms the hook <NUM>. In addition, the hook <NUM> is disposed toward a front side where the chain <NUM> is disposed so that when the chain saw <NUM> is hung, the chain <NUM> is downward and the housing <NUM> is upward. Thus, when the chain saw <NUM> falls because of misoperation or the like, the housing <NUM> can be away from the ground, thereby avoiding damage to the housing <NUM>. In this example, on the one hand, the hook <NUM> is formed by the housing so that an additional mounting opening or mounting accessory is avoided; and on the other hand, the hook <NUM> is disposed above the plane where the lower bottom surface is located so that the hook <NUM> does not protrude from the lower bottom surface of the whole machine of the chain saw <NUM>, thereby avoiding an increase of the dimension of the whole machine of the chain saw <NUM> in the up and down direction and making the whole machine of the chain saw <NUM> more compact.

As shown in <FIG>, in this example, the power system <NUM> includes an electric motor <NUM> which is specifically configured to be an external rotor electric motor <NUM>. An electric motor <NUM> with a small volume and a high energy/power density is used as the external rotor electric motor <NUM>, where a rotational speed of the external rotor electric motor <NUM> is set to be greater than or equal to <NUM> r/min and less than or equal to <NUM> r/min. In an example, the rotational speed of the external rotor electric motor <NUM> is set to be greater than or equal to <NUM> r/min and less than or equal to <NUM> r/min. In this example, a mass of the external rotor electric motor <NUM> is set to be greater than or equal to <NUM> and less than or equal to <NUM>, and a mass of the whole machine of the chain saw <NUM> without the power supply assembly <NUM> is set to be greater than or equal to <NUM> and less than or equal to <NUM>. A ratio of the mass of the external rotor electric motor <NUM> to the mass of the whole machine of the chain saw <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. Such an electric motor <NUM> is provided, which can effectively reduce the space occupied by the electric motor <NUM> in the first accommodation space <NUM> and can reduce the dimension of the whole machine of the chain saw <NUM> on the one hand and can also ensure that the chain saw <NUM> has relatively high power output and relatively high cutting efficiency on the other hand. In an example, the transmission system <NUM> includes an output shaft <NUM> and a three-stage gear <NUM> for transmission. The three-stage gear <NUM> includes a first-stage gear 172a, a second-stage gear 172b, and a third-stage gear 172c, where the output shaft <NUM> is connected to the first-stage gear 172a, an electric motor shaft 181a is connected to the third-stage gear 172c, and the second-stage gear 172b is connected to the first-stage gear 172a and the third-stage gear 172c. The three-stage gear <NUM> is configured for transmission so that a distance between the electric motor shaft 181a and a drive shaft configured to drive the chain <NUM> to rotate can be effectively increased, thereby causing the electric motor shaft 181a to be away from a chip discharge space <NUM> of the chain saw <NUM>. The transmission system <NUM> may be provided with a two-stage gear or a multi-stage gear for the transmission. In an example, the locking device further includes a cover plate <NUM> sealing at least part of the chain <NUM> and at least part of the guide plate <NUM>. The drive shaft protrudes from the first accommodation space <NUM> of the housing <NUM>, a driving wheel is disposed on the drive shaft, and the chain <NUM> is engaged with the driving wheel and can be driven by the driving wheel to rotate around the guide plate <NUM>. When cutting a workpiece, the chain <NUM> generates many chips, and part of the chips rotate along with the chain <NUM> to the vicinity of the driving wheel and fall in the vicinity of the driving wheel. When sealing at least part of the chain <NUM> and at least part of the guide plate <NUM>, the cover plate <NUM> mates with the housing <NUM> to form the chip discharge space <NUM>. The chip discharge space <NUM> occupies most of the space of the cover plate <NUM> in the front and rear direction. The chip discharge space <NUM> is formed with a chip discharge opening <NUM> downward so that the chips which rotate along with the chain <NUM> to the vicinity of the driving wheel fall out of the chip discharge space <NUM>. To make the chip discharge space <NUM> larger, the chip discharge opening <NUM> wider, and a chip discharge effect better and to prevent the chain saw <NUM> from being locked, the electric motor shaft 181a is disposed, in the front and rear direction, on the rear side away from the chip discharge space <NUM>. In addition, the three-stage gear <NUM> performs the transmission so that the space of the housing <NUM> occupied by the transmission system <NUM> in the left and right direction is also reduced. Thus, the transmission system <NUM> can be effectively prevented from occupying the chip discharge space <NUM> in the left and right direction so that on the premise that the chain saw <NUM> has the same volume and relatively high output power, the chip discharge space <NUM> can be configured to be relatively large and have a better chip discharge effect. In an example, the transmission system <NUM> includes a gearbox <NUM> configured to accommodate at least part of the three-stage gear <NUM> and distributed substantially along the front and rear direction. In the left and right direction, the electric motor <NUM> and the output shaft <NUM> are both disposed on the same side of the gearbox <NUM>. In this example, the electric motor <NUM> and the output shaft <NUM> are both disposed on a right side of the gearbox <NUM>. In a direction of a preset straight line passing through the up and down direction, a lowermost side of the output shaft <NUM> in the up and down direction includes a first plane perpendicular to the direction of the preset straight line, and an uppermost side of the electric motor shaft 181a in the up and down direction includes a second plane perpendicular to the direction of the preset straight line. The first plane is located above the second plane, that is, the electric motor shaft 181a and the output shaft <NUM> are also staggered in the up and down direction and are located in two planes so that the electric motor <NUM> can be further away from the chip discharge space <NUM>.

The rear side of the housing <NUM> protrudes rightward so that a second accommodation space <NUM> is formed, where the electric motor <NUM> is disposed in the second accommodation space <NUM>. The first accommodation space <NUM> and the second accommodation space <NUM> at least partially communicate with each other. In an example, a right end face of the electric motor <NUM> is disposed on a right side of the chain <NUM> and the guide plate <NUM>. With this arrangement, on the one hand, the electric motor <NUM> can occupy less of the second accommodation space on the left side, and when the cover plate <NUM> is mounted to the housing, it can be ensured that the cover plate <NUM> and the housing <NUM> are substantially in the same flush position in the front and rear direction.

As shown in <FIG>, part of the housing <NUM> forming the second accommodation space <NUM> further includes a movable air outlet <NUM>. The air outlet <NUM> is disposed on an outer surface of the housing <NUM>. The air outlet <NUM> is configured to be rotatable or retractable in a preset direction so that a blowing direction of cooling air of the electric motor <NUM> is adjusted. In an example, the air outlet <NUM> includes a first blowing direction and a second blowing direction. When the air outlet <NUM> is adjusted to the first blowing direction, the air can be blown forward via the air outlet <NUM> so that the chips discharged from the chip discharge opening <NUM> can be blown forward, thereby preventing the chips from falling on the user. When the air outlet <NUM> is adjusted to the second blowing direction, the air can be blown backward via the air outlet <NUM>, thereby blowing on the power supply assembly <NUM> disposed on the rear side of the housing <NUM> to cool the power supply assembly <NUM>.

As shown in <FIG>, in this example, the control system <NUM> includes a circuit board assembly <NUM> disposed in the first accommodation space <NUM>, where the circuit board assembly <NUM> extends in a plane. The circuit board assembly <NUM> is obliquely disposed in the first accommodation space <NUM>. In an example, the circuit board assembly <NUM> and a first straight line <NUM> extending in the front and rear direction intersect obliquely with each other and are at a preset included angle. Since the transmission system <NUM> gradually occupies a smaller space from the front to the rear, that is, a gap between the transmission system <NUM> and the housing <NUM> is obliquely distributed, the circuit board assembly <NUM> makes full use of the oblique space. In an example, the circuit board assembly <NUM> is configured to overlap the electric motor <NUM> and the gearbox <NUM> in the up and down direction and overlap the power supply assembly <NUM> in the front and rear direction. That is, in a direction of a second straight line <NUM> perpendicular to a direction of the first straight line <NUM> and extending along the up and down direction, the electric motor <NUM> has a projection surface along the direction of the second straight line <NUM>, where the projection surface is perpendicular to the direction of the second straight line <NUM>, and the circuit board assembly <NUM> has a projection surface along the direction of the second straight line <NUM>, where the projection surface is perpendicular to the direction of the second straight line <NUM>; and the projection surface of the electric motor <NUM> along the direction of the second straight line <NUM> at least partially overlaps the projection surface of the circuit board assembly <NUM> along the direction of the second straight line <NUM>. The transmission system <NUM> has a projection surface along the direction of the second straight line <NUM>, where the projection surface is perpendicular to the direction of the second straight line <NUM>, and the circuit board assembly <NUM> has the projection surface along the direction of the second straight line <NUM>, where the projection surface is perpendicular to the direction of the second straight line <NUM>; and the projection surface of the transmission system <NUM> along the direction of the second straight line <NUM> at least partially overlaps the projection surface of the circuit board assembly <NUM> along the direction of the second straight line <NUM>. The power supply assembly <NUM> has a projection surface along the direction of the first straight line <NUM>, where the projection surface is perpendicular to the direction of the first straight line <NUM>, and the circuit board assembly <NUM> has a projection surface along the direction of the first straight line <NUM>, where the projection surface is perpendicular to the direction of the first straight line <NUM>; and the projection surface of the power supply assembly <NUM> along the direction of the first straight line <NUM> at least partially overlaps the projection surface of the circuit board assembly <NUM> along the direction of the first straight line <NUM>.

To ensure effective heat dissipation on components in the housing <NUM>, an air inlet <NUM> is also disposed on the housing <NUM>. In an example, the air inlet <NUM> is disposed on a left side of the housing <NUM> and substantially in the position of the transmission system <NUM>. When the chain saw <NUM> is operated, the electric motor <NUM> rotates to drive a cooling fan connected to the electric motor shaft 181a to rotate synchronously, thereby forming a negative pressure in the housing <NUM>. In this case, an airflow flows from the air inlet <NUM> into the housing <NUM>, flows through the gearbox <NUM>, the circuit board assembly <NUM>, and the electric motor <NUM> separately, and finally flows out from the air outlet <NUM>. In this process, since the circuit board assembly <NUM> is obliquely disposed in the housing <NUM> and the circuit board assembly <NUM> overlaps the electric motor <NUM> and the gearbox <NUM>, the heat dissipation airflow can flow through the circuit board assembly <NUM> and the gearbox <NUM> simultaneously and can flow through the circuit board assembly <NUM> sufficiently so that heat on the circuit board assembly <NUM> can be carried away to the maximum extent, thereby effectively increasing the heat dissipation efficiency of the circuit board assembly <NUM>.

In this example, the brake system is configured to be an electronic brake, where a control loop of the electronic brake is disposed in the circuit board assembly <NUM>, and when the electric motor <NUM> is controlled by a switch to stop, the electric motor <NUM> is braked by a counter-electromotive force generated during the running of the electric motor <NUM>. The electronic brake is provided, which avoids an accommodation space occupied due to the use of a mechanical brake. Thus, the housing <NUM> does not need to form a portion for accommodating a mechanical brake assembly, thereby making the whole machine of the chain saw <NUM> more compact.

In this example, the housing <NUM> includes a first housing <NUM> and a second housing <NUM>, where the first housing <NUM> and the second housing <NUM> are substantially symmetrical and are connected to each other to form the complete housing <NUM> and form the first accommodation space <NUM> and the second accommodation space <NUM>. With the preceding arrangement, a center of gravity of the chain saw <NUM> in the present application can be located substantially at a joint of the first housing <NUM> and the second housing <NUM>, that is, the center of gravity of the chain saw <NUM> can be located substantially at a center of symmetry of the whole machine in the left and right direction and in a center line of the whole machine in the front and rear direction. It is to be explained that the whole machine of the chain saw <NUM> here refers to a whole after the guide plate <NUM> and the chain saw <NUM> are removed. With the preceding arrangement, the center of gravity of the whole machine of the chain saw <NUM> is located substantially near the main handle 11a so that when the chain saw <NUM> is operated or is in a placed state, the chain saw <NUM> neither overturns nor slants, and the operation experience is excellent. In addition, since the center of gravity of the whole machine of the chain saw <NUM> is disposed near the main handle 11a, when the chain saw <NUM> is operated, a wrist of the user does not need to additionally output an acting force for balancing the whole machine of the chain saw <NUM>, and it is very laborsaving for the user to operate the chain saw <NUM>. In addition, after the guide plate <NUM> and the chain <NUM> are mounted, the center of gravity of the whole machine of the chain saw <NUM> is moved forward so that a portion where the chain <NUM> of the chain saw <NUM> is located can automatically droop to get close to the workpiece. Thus, when the user operates the chain saw <NUM>, a reaction force of the workpiece to the chain <NUM> can be effectively counteracted so that the user does not need to output a relatively large force during a cutting process to force the chain saw <NUM> to cut the workpiece.

Claim 1:
A chain saw (<NUM>), comprising:
a housing (<NUM>) extending substantially along a front and rear direction and formed with an accommodation space;
an electric motor (<NUM>) at least partially disposed in the accommodation space;
a transmission system (<NUM>) connected to the electric motor (<NUM>) and capable of outputting a driving force;
a control system (<NUM>) comprising a circuit board assembly (<NUM>) extending in a plane; and
a power supply assembly (<NUM>) disposed on a rear side of the housing (<NUM>) and used for powering the electric motor (<NUM>);
wherein the circuit board assembly obliquely intersects with a first straight line (<NUM>) extending along the front and rear direction; in a direction of a second straight line (<NUM>) perpendicular to a direction of the first straight line (<NUM>) and extending along an up and down direction, wherein the electric motor (<NUM>) has a projection surface
perpendicular to the direction of the second straight line (<NUM>) and the circuit board assembly has a first projection surface perpendicular to the direction of the second straight line (<NUM>); and the projection surface of the electric motor (<NUM>) at least partially overlaps the first projection surface of the circuit board assembly; characterized in that
in the direction of the first straight line (<NUM>), the power supply assembly (<NUM>) has a projection surface perpendicular to the direction of the first straight line (<NUM>) and the circuit board assembly has a second projection surface perpendicular to the direction of the first straight line (<NUM>); and the projection surface of the power supply assembly (<NUM>) at least partially overlaps the second projection surface of the circuit board assembly.