Robotic lawn mower having a height adjustment

A robotic lawn mower includes a mowing system, a housing, a working assembly and an energy source device. The mowing system includes a cutting assembly, a driving mechanism, and a height adjusting mechanism. The cutting assembly includes a mowing member for cutting the grass and a mounting shaft for mounting the mowing member. The mounting shaft is capable of rotating about a first axis relative to the housing. The driving mechanism includes a driving shaft for driving the cutting assembly to rotate. The height adjusting mechanism is used to adjust the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. When the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the driving shaft along the first axis.

RELATED APPLICATION INFORMATION

This application claims the benefit under 35 U.S.C. § 119(a) of Chinese Patent Application No. CN 201911245936.X, filed on Dec. 7, 2019, and Chinese Patent Application No. CN 202011370802.3, filed on Nov. 30, 2020, which applications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to garden tools, in particular to a lawn mower and a robotic lawn mower.

BACKGROUND

A lawn mower is one of commonly used garden tools, which is mainly used for mowing all kinds of lawns. Compared with a traditional lawn mower, robotic lawn mowers can run autonomously and complete mowing according to a planned path, which can save a lot of labor, reduce the cost of lawn maintenance and improve labor efficiency. Moreover, they use electric energy and scientifically plan a path, thereby reducing repetitive work and saving energy.

At present, most robotic lawn mowers can usually move the height of their mowing systems up and down in order to achieve different mowing heights. However, structures of an adjusting mechanism and components adjusted by the adjusting mechanism of the mowing systems are relatively complex, the stability of the robotic lawn mowers is poor, the structures are complex, and the stability is poor during adjusting.

SUMMARY

In one example of the disclosure, a robotic lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the robotic lawn mower to walk on a ground; and an energy source device used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a driving shaft for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. When the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the driving shaft along the first axis.

In one example, when the height adjusting mechanism drives the cutting assembly to move along the first axis, the position of the driving shaft relative to the housing in the first axis remains constant.

In one example, the driving shaft is formed with a driving portion for driving the mounting shaft to rotate synchronously with the driving shaft and the driving portion allows the mounting shaft to move relative to the driving shaft along the first axis.

In one example, the driving shaft is formed with a mounting hole extending along the first axis, the mounting shaft is inserted into or passes through the mounting hole, and the driving portion is formed on a hole wall of the mounting hole.

In one example, the height adjusting mechanism includes an operating member for a user to operate, an adjusting assembly including an adjusting member and a mounting bracket for mounting the mounting shaft, and when the operating member is operated by the user, the adjusting member drives the mounting bracket to move along the first axis.

In one example, the adjusting member is capable of rotating about a rotation axis relative to the housing, and the adjusting member and the mounting bracket form a transmission fit that can convert the rotation of the adjusting member into a sliding movement of the mounting bracket along the first axis.

In one example, the driving mechanism further includes a prime mover used to output power, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the prime mover remains fixed relative to the housing along the first axis.

In one example, the driving mechanism further includes a prime mover for outputting power to drive the cutting assembly to cut the grass, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the prime mover along the first axis.

In one example, the driving shaft is a prime mover shaft of the prime mover.

In one example, the driving mechanism further includes a transmitting assembly for realizing a power transmission between the prime mover and the mounting shaft, and the driving shaft is a power output member of the transmitting assembly.

In one example, when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the position of the transmitting assembly relative to the housing along the first axis remains constant.

In one example, the prime mover includes a prime mover shaft and the prime mover shaft is capable of rotating about a second axis that is parallel to and not coincident with the first axis.

In one example, the prime mover includes a prime mover shaft which is capable of rotating about a second axis perpendicular to or inclined to the first axis.

In one example, the height adjusting mechanism further includes a driving motor for driving the mounting shaft to move along the first axis.

In one example, the driving mechanism includes a prime mover for outputting power to drive the cutting assembly to mow grass, and the prime mover and the driving motor are arranged in the housing.

In one example of the disclosure, a robotic lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the robotic lawn mower to walk on a ground; and a battery pack used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a electric motor for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. Wherein when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the electric motor along the first axis.

In one example, the driving mechanism further includes a transmitting assembly for realizing a power transmission between the electric mover and the mounting shaft, and when the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the mounting shaft moves relative to the transmitting assembly along the first axis.

In one example, the height adjusting mechanism further includes a driving motor for driving the mounting shaft to move along the first axis.

In one example, the electric motor is fixedly mounted to the housing.

In one example of the disclosure, a lawn mower includes: a mowing system for mowing grass; a housing configured to support the mowing system; a working assembly including a working wheel configured to support the housing to drive the lawn mower to walk on a ground; and a battery pack used to provide energy source. The mowing system includes: a cutting assembly including a mowing member for cutting the grass and a mounting shaft for mounting the mowing member, wherein the mounting shaft is capable of rotating about a first axis relative to the housing; a driving mechanism including a electric motor for driving the cutting assembly to rotate; and a height adjusting mechanism for adjusting the movement of the cutting assembly along the first axis to achieve different cutting heights of the mowing member. When the height adjusting mechanism adjusts the cutting assembly to move along the first axis, the position of the electric motor relative to the housing in the first axis remains constant.

DETAILED DESCRIPTION

A lawn mower100of a first example shown inFIG.1is used to mow vegetation such as lawns and weeds. In this example, the lawn mower100is a robotic lawn mower that does not need to be pushed by a user, and the robotic lawn mower can automatically mow the lawns without being operating by the user. The lawn mower can also be a push-type lawn mower. For the push-type lawn mower, the user usually stands behind the push-type lawn mower, and the user pushes a handle of the push-type lawn mower to push it to walk on a ground. Alternatively, the lawn mower may also be a riding lawn mower. For the riding lawn mower, the user rides on a seat of the riding lawn mower to operate it to walk on the ground.

As shown inFIGS.1and2, the lawn mower100includes a mowing system10, a working assembly20, a control assembly, an energy source device40and a housing50. The mowing system10is used to implement a mowing function of the lawn mower100. The working assembly20includes a working wheel21for driving the lawn mower100to walk on. i.e., move over/across, the ground. The control assembly is used to control electrical equipment in the lawn mower100and to display intelligent performances of the lawn mower100. The energy source device40is used to provide an energy source for the mowing system10, the working assembly20, and the control assembly. In this example, the energy source device40is a power source device, and the power source device may include a battery pack41installed to the housing50. The housing50is used to support the mowing system10, the control assembly and the energy source device40. The walking assembly20is installed to the housing50and supports the housing50.

The mowing system10includes a driving mechanism110, a cutting assembly120, and a height adjusting mechanism130. The driving mechanism110includes a prime mover for outputting power. The cutting assembly120includes a mounting shaft121and a mowing member122. The mounting shaft121is used to drive the mowing member122to rotate about a first axis101to realize the mowing function. The mowing member122may be a blade for cutting grass. The height adjusting mechanism130can adjust the height of the mowing member122relative to the housing50in the first axis101, so that the lawn mower100has different cutting heights. For example, the height adjusting mechanism130can adjust the cutting assembly120to move the mowing member122to a first height and a second height. When the mowing member122is at the first height, the mowing member122is closer to the ground, so that more grass on the ground can be cut. When the mowing member122is at the second height, the mowing member122is far away from the ground, so that less grass on the ground can be cut.

In this example, the height adjusting mechanism130can drive the mounting shaft121and the mowing member122mounted on the mounting shaft121to move up and down along the first axis101. When the height adjusting mechanism130adjusts the mounting shaft121to move up and down, a position of the prime mover relative to the housing50in the first axis101remains fixed. In this way, the height adjusting mechanism130drives the cutting assembly120to move up and down along the first axis101, but does not drive the prime mover to move up and down synchronously with the cutting assembly120, so that a total number of parts driven by the height adjusting mechanism130that can move up and down in the first axis101synchronously with the mowing member122is small. A total weight of the parts is also relatively small, thereby improving the comfort of operating of the height adjusting mechanism130and the stability of the height adjusting mechanism130. A weight of loads driven by the height adjusting mechanism130is also relatively small, thereby prolonging the service life of the height adjusting mechanism130. In addition, the housing50is formed with or connected with a mounting structure51. Because the prime mover does not move up and down with the cutting assembly120, so that the prime mover can be fixedly installed to the mounting structure51, thereby improving the reliability of the prime mover and reducing the vibration generated by the prime mover during the operation of the lawn mower100, thereby prolonging the service life of the lawn mower100. Furthermore, the mounting shaft121and the mowing member122can be driven by the height adjusting mechanism130at the same time to move up and down in the first axis101, so that the mowing member122is stably mounted to the mounting shaft121, improving the reliability of the cutting assembly120. Especially for the robotic lawn mower, the size of the robotic lawn mower is relatively small. If the driving mechanism110also moves up and down along with the cutting assembly120, the robotic lawn mower needs a larger space for the driving mechanism110and the cutting assembly120to move, which is not conducive to the miniaturization of the robotic lawn mower. In this example, the driving mechanism110does not move with the cutting assembly120, so that the internal structure of the robotic lawn mower is relatively compact, thereby facilitating the miniaturization of the robotic lawn mower.

The prime mover includes a driving shaft1111for outputting power and the driving shaft1111is the prime mover shaft of the prime mover. In this example, the prime mover is an electric motor111, the electric motor111includes a stator assembly and a rotor assembly, the rotor assembly also includes a rotor shaft, and the rotor shaft is the driving shaft1111for outputting power of the electric motor111. When the height adjusting mechanism130drives the mounting shaft121and the mowing member122to move up and down along the first axis101, the position of the driving shaft1111relative to the housing50in the first axis101remains constant. In the present example, the driving shaft1111is arranged along the first axis101. The driving shaft1111is also coaxial with the mounting shaft121. The driving shaft1111is provided with a first mounting hole1111aextending along the first axis101, the first mounting hole1111apenetrates the driving shaft1111along the first axis101, and the mounting shaft121is inserted into or passes through the first mounting hole1111a. When the prime mover is in operation, the driving shaft1111can rotate around the first axis101, and the driving shaft1111transmits power to the mounting shaft121to drive the mounting shaft121to rotate around the first axis101. The mounting shaft121can also slide up and down along the first axis101relative to the driving shaft1111. Specifically, as shown inFIG.3, the driving shaft1111is provided with a driving portion formed on a hole wall of the first mounting hole1111a, the driving portion drives the mounting shaft121to rotate synchronously with the driving shaft1111, and the driving portion allows the mounting shaft121to slide up and down relative to the driving shaft1111. In this example, the driving portion is directly formed on the hole wall of the mounting hole1111aand the driving portion is a transmission plane parallel to the first axis101. It can be understood that in some other examples, a mounting hole of a driving shaft can also be provided with a driving member, the driving member may be a bushing, the bushing is fixedly connected with the driving shaft, and the bushing forms a driving hole, and a hole wall of the driving hole forms a driving portion that can drive a mounting shaft to rotate with the driving shaft, and the mounting shaft passes through the driving hole.

In the present example, the cutting assembly120also includes a mounting member for mounting the mowing member122to the mounting shaft121. The mounting member is a disc, the mowing member122is a blade mounted on the disc, and the blade also can rotate relative the disc. The disc is fixed to a preset position on the mounting shaft121through fasteners, and there is only one preset position. That is to say, the position of the disc relative to the mounting shaft121in the first axis101is not adjustable, and the position of the disc relative to the mounting shaft121in the first axis101is fixed. In this way, the disc can be more stably installed to the mounting shaft121, so as to prevent the disc from loosening relative to the mounting shaft121.

The height adjusting mechanism130includes an operating member and an adjusting assembly132. The operating member is used for the user to operate to control cutting heights of the cutting assembly120. In this example, the operating member is a knob131that can be turned by the user. The knob131may be arranged below the housing50or above the housing50. In other examples, an operating element may also be an operating button. The lawn mower100further includes a display screen60, and the operating member may be a touch button on the display screen60, and the display screen60is a touch screen.

The adjusting assembly132includes an adjusting member1321and a mounting bracket1322. The mounting bracket1322is composed of two parts. The adjusting member1321is connected to the operating member, and the mounting bracket1322is used for mounting the mounting shaft121. When the user operates the knob131, the adjusting member1321adjusts the mounting bracket1322to move along the first axis101or a direction parallel to the first axis101, and the mounting bracket1322drives a whole of the mounting shaft121and the mowing member122along the first axis101, so that the lawn mower100has different cutting heights.

The adjusting member1321can rotate around a rotation axis, and the adjusting member1321and the mounting bracket1322form a transmission fit that can convert the rotation of the adjusting member1321into a sliding movement of the mounting bracket1322along the first axis101. The transmission fit may be a direct fit between the adjusting member1321and the mounting bracket1322, or an indirect fit in which a switching structure is provided between the adjusting member1321and the mounting bracket1322. Specifically, the adjusting member1321is a screw rod. A first thread is formed on the screw rod, and a second thread that matches the first thread is formed on the mounting bracket1322. The rotation of the mounting bracket1322about the first axis101is restricted, that is, the mounting bracket1322cannot rotate about the first axis101. In this way, when the adjusting member1321rotates with the knob131, the adjusting member1321will drive the mounting bracket1322to move along the first axis101under the cooperation of the first thread and the second thread. The screw rod is mounted to the mounting structure51of the housing50.

As shown inFIG.2, the mounting bracket1322is formed with a second mounting hole1322bextending along the first axis101, and the mounting shaft121passes through the second mounting hole1322b. The second mounting hole1322bis also recessed along a radial direction perpendicular to the first axis101to form a groove1322c. The adjusting assembly132further includes a bearing1323, the bearing1323is installed in the groove1322c, and the bearing1323can move synchronously with the mounting bracket1322along the first axis101. A groove wall of the groove1322cis formed with a first limiting portion1322d, and the first limiting portion1322dcan restrict the bearing1323from separating from the mounting bracket1322along the first axis101. The bearing1323also supports the mounting shaft121, an inner ring of the bearing1323can be fixedly connected to the mounting shaft121, and an outer ring of the bearing1323can be fixedly connected to the groove wall of the groove1322c. In this example, the inner ring of the bearing1323can be interference fit with the mounting shaft121, and the outer ring of the bearing1323can be interference fit with the groove wall of the groove1322c.

In the present example, the mounting shaft121is formed with or connected with a second limiting portion1211, and the second limiting portion1211can limit the bearing1323from disengaging from the mounting shaft121along the first axis101. In the present example, the second limiting portion1211is a pair of annular protrusions formed on the mounting shaft121, and the bearing1323is arranged between the pair of annular protrusions. In other examples, a second limiting portion may also be a clamp ring provided on a mounting shaft.

The height adjusting mechanism130further includes a sliding rail for restricting the rotation of the mounting bracket1322, and the sliding rail is installed on the housing50along a direction parallel to the first axis101. One side of the mounting bracket1322is used as a sliding block to cooperate with the sliding rail. The sliding rail is formed on the housing50, or the sliding rail is formed of a part fixed relative to the housing50. The sliding rail limits the rotation of the mounting bracket1322around the first axis101and allows the mounting bracket to slide along the sliding rail in the first axis101. One end of the screw rod is fixed relative to the housing50, the screw rod can only rotate around the axis of the screw rod, and the other end of the screw rod passes through and is fixedly connected with the knob131, which can drive the screw rod to rotate when the knob131rotates.

When the user operates the knob131, the screw rod follows the knob131to rotate. Because the mounting bracket1322is matched with the screw rod, and the other side of the mounting bracket1322is fitted in the sliding rail and cannot rotate and move horizontally, the mounting bracket1322can move up and down along the slid sliding rail under the rotation of the screw rod.

Because the bearing1323is fixed on the mounting bracket1322, the bearing1323has a tendency to move up and down following the mounting bracket1322, and thus has a tendency to move relative to the mounting shaft121. Since the mounting shaft121is provided with a stopper that restricts the relative movement of the bearing1323and the mounting shaft121, the bearing1323will drive the mounting shaft121to move up and down when the bearing1323is driven by the mounting bracket1322.

The mounting shaft121cooperates with the driving shaft1111of the driving mechanism110. But the mounting shaft121cannot drive the driving shaft1111to move up and down, thus cannot drive the driving mechanism110to move up and down.

Therefore, the height adjusting mechanism130only adjusts the height of the mounting shaft121and does not adjust the height of other components.

FIG.4shows the internal structure of a lawn mower of a second example. In this example, the lawn mower may also be a robotic lawn mower. The lawn mower includes a working assembly, a control assembly, and a power source device which are substantially the same as that in the lawn mower100in the first example. The lawn mower of this example further includes a mowing system20aand a housing for mounting the mowing system20a, and the housing includes a mounting structure200. The mowing system20aincludes a cutting assembly230and a height adjusting mechanism240that are basically the same as that in the lawn mower100of the first example. The main difference between this example and the first example is that the mowing system20aincludes a driving mechanism210that is different from that in the first example. The driving mechanism210includes a prime mover211and a transmitting assembly220for realizing a power transmission between the prime mover211and the cutting assembly. In this example, because the driving mechanism210is different from the first example and the driving mechanism210is mounted to the housing, the housing also includes another mounting structure200for mounting the driving mechanism210. The following mainly introduces the differences between this example and the first example, and the parts of this example with the same as the first example will not be described in detail.

As shown inFIG.4, the height adjusting mechanism240can adjust a whole of a mounting shaft231and a mowing member232to move up and down along a first axis201, so that the lawn mower has different cutting heights.

In this example, the prime mover211includes a prime mover shaft2111that can rotate about a second axis202. The transmitting assembly220is used to transmit a power output by the prime mover shaft2111to the mounting shaft231.

In this example, the transmitting assembly220is mounted to the mounting structure200of the housing. The transmitting assembly220includes a driving shaft for driving the mounting shaft231to rotate, which drives the mounting shaft231to rotate synchronously and allows the mounting shaft231to move up and down in the first axis201relative to it. Here, the driving shaft is considered as a part of the transmitting assembly220, and the driving shaft is a power output member of the transmitting assembly220. Of course, it can be considered that the driving shaft is not part of the transmitting assembly220, but that the transmitting assembly220is used to transfer a power between the prime mover211and the driving shaft. In this example, the driving shaft is a first driving wheel221, and the transmitting assembly220further includes a second driving wheel222and a driving belt223. The driving belt223is a synchronous belt, the first driving wheel221and the second driving wheel222are synchronous belt wheels, and a torque transmission of the transmitting assembly220is constant speed transmission. In other words, the transmitting assembly220only transmits a torque without changing the speed, so that the speed of the mounting shaft231is the same as that of the prime mover shaft2111. In other examples, a transmitting assembly can also change the speed transmitted from the prime mover shaft to the mounting shaft so that the speed of the mounting shaft is different from that of the prime mover shaft.

In some other examples, the transmitting assembly may be one or a combination of two or more of belt transmission, rope transmission, friction wheel transmission, gear transmission, chain transmission, screw transmission, or harmonic transmission.

By providing the transmitting assembly220, the prime mover211and the mounting shaft231are not arranged on the same axis, an overall size of the driving mechanism210and the cutting assembly230in a height direction of the housing can be reduced, thereby facilitating the miniaturization of the lawn mower. Moreover, in the present example, the prime mover211is a motor, and the transmitting assembly220is provided so that the electric motor can be a conventional electric motor in the prior art, which reduces the design and production cost of the motor and can also improve the structural strength and reliability of the motor. Furthermore, the transmitting assembly220is provided so that the cutting assembly230can be separated from the driving mechanism210, thereby facilitating maintenance of the driving mechanism210and the cutting assembly230separately.

Specifically, the second driving wheel222is fixedly connected to the prime mover shaft2111, and the first driving wheel221is formed with a driving portion221a. The driving portion221acan output torque to the mounting shaft231to drive the mounting shaft231to rotate synchronously with the first driving wheel221. The driving portion221aalso allows the mounting shaft231to move up and down along the first axis201. In this way, when the user operates an operating member241, the height adjusting mechanism240can adjust a whole of the mounting shaft231and the cutting member232to move up and down along the first axis201relative to the transmitting assembly220, thereby enabling the lawn mower to have different cutting heights.

In the present example, the height adjusting mechanism240only drives the cutting assembly230to move up and down in the first axis201, while the prime mover211and the transmitting assembly220are kept constant relative to the housing in the first axis201. A total number of parts driven by the height adjusting mechanism240that can move up and down in the first axis201synchronously with the mowing member232is small, and a total weight of the parts is also relatively small, thereby improving the comfort of operation of the height adjusting mechanism240and improving the stability of the height adjusting mechanism240. The weight of loads driven by the height adjusting mechanism240is also relatively small, thereby prolonging the service life of the height adjusting mechanism240. In addition, since the prime mover211and the transmitting assembly220do not move up and down together with the cutting assembly230, the prime mover211and the transmitting assembly220can be mounted to the mounting structure200of the housing, thereby improving the reliability of the prime mover211and the transmitting assembly220, reducing the vibration generated by the prime mover211and the transmitting assembly220during the operation of the lawn mower, thereby extending the service life of the lawn mower. Furthermore, the mounting shaft231and the mowing member232can be driven by the height adjusting mechanism240to move up and down in the first axis201, so that the mowing member232is stably mounted to the mounting shaft231, which improves the reliability of the cutting assembly230.

In the present example, the fit between the first driving wheel221and the mounting shaft231is clearance fit. When the mounting shaft231moves up and down under an external force, because the mounting shaft231is in the clearance fit with the first driving wheel221, the mounting shaft231does not drive the first driving wheel221and the driving belt223matched with the first driving wheel221to move up and down, so the prime mover211dose not move with the mounting shaft231when the mounting shaft231moves up and down.

The driving mechanism210can be assembled at any position in the housing under a premise of ensuring that the prime mover shaft2111can transmit torque to the mounting shaft231through the transmitting assembly220, so that it can also be assembled at a more reasonable position according to the position of a center of gravity of the lawn mower and the arrangement of internal structures.

The second axis202on which the prime mover shaft2111rotates does not overlap with the first axis201on which the mounting shaft231rotates.

Preferably, the first axis201and the second axis202are parallel to each other and spaced apart by a distance. The second axis202is parallel to and not coincident with the first axis201. Alternatively, in some other examples, a second axis and a first axis may be perpendicular to each other, or the second axis may be inclined relative to the first axis.

FIG.5shows the internal structure of a lawn mower of a third example. In this example, the lawn mower may also be a robotic lawn mower. The structure of the lawn mower is basically the same as that of the lawn mower in the second example. The main difference is that the lawn mower in this example is not used for a user to manually adjust a knob to achieve speed regulation, but a driving motor331is provided in an adjusting mechanism330, the driving motor331drives an adjusting member3321to rotate through a gear assembly333, and then the adjusting member3321drives a mounting bracket3322and a mounting shaft321to move up and down along a first axis301. In this way, an electric adjustment of the cutting height of the cutting assembly320can be realized, thereby facilitating the user's operation. Moreover, the driving motor331may also be connected with a controller and a detecting device, the detecting device detects load parameters, grass height parameters, etc., and the controller controls the operation of the driving motor331according to a detection result of the detection device to adjust the cutting assembly320to a corresponding cutting height. Alternatively, in other examples, a driving motor331can also be connected to a control panel, and the user can input a cutting height on the control panel, and then the driving motor331operates to adjust the cutting assembly320to a corresponding cutting height. In this example, the driving motor331and a prime mover are both arranged in a housing35.