lawnmower cutting unit, lawnmower and cutting disc

Abstract

This disclosure relates to a lawnmower cutting unit, a lawnmower, and a cutting disc. The lawnmower cutting unit includes: a cutting propulsion unit having a drive shaft adapted to rotate about a common axis of rotation; a hub rotatably connected to the drive shaft; a cutting disc; and a knob. The knob is rotatably connected to the hub such that it is adapted to rotate together with the hub and the drive shaft. The cutting disc is displaced along the common axis of rotation against the elastic force of a spring element. The cutting disc and the knob are included in a coupling joint, which is included in the lawnmower cutting unit and adapted to transmit rotational torque transmitted from the hub to the cutting disc. The coupling joint is adapted to releasably lock the cutting disc along the common axis of rotation into a plurality of mutually separated locking positions by means of elasticity, thereby assigning an associated specific mowing height to each locking position.

Description

Technical Field

[0001] This disclosure relates to a powered lawnmower, such as a robotic lawnmower, in which the user can easily adjust the cutting height. Background Technology

[0002] Lawn mowers are used for both domestic and commercial applications and can be powered by either an electric motor or an internal combustion engine. So-called rotary blades employ a cutting member that can rotate in a plane substantially parallel to the ground and about an axis orthogonal to the ground. This cutting member includes an arm or disc rotatably supported at its center and having cutting blades arranged at its ends or outer edges.

[0003] For example, automated or robotically powered tools such as robotic lawnmowers are becoming increasingly popular. In a typical work area (e.g., a garden) layout, the work area is enclosed by a boundary line to keep the robotic lawnmower within the work area. Electrical control signals can be transmitted through the boundary line, generating a (electro)magnetic field emanating from it. Robotic tools are typically equipped with one or more sensors suitable for sensing these control signals.

[0004] The robotic lawnmower can then automatically mow a user's lawn without user intervention, and it can automatically recharge itself, requiring no further manual management after being set up once. A typical robotic lawnmower includes a charging pad that contacts a corresponding contact plate in the charging station when docked to receive charging current, and can also be used to transmit information via electrical communication between the charging station and the robotic lawnmower.

[0005] Most traditional lawnmowers include some mechanism for adjusting the mowing height, because different users prefer to cut their lawns to different lengths, and different sections of their lawns to different lengths. This may depend on the grass growth rate and the frequency of mowing in a particular area, as well as the average user's desired mowing height.

[0006] Most lawnmowers include devices for providing an adjustable cutting height, such as wheels or rollers that can be connected to the housing in several different positions, each corresponding to a different cutting height. However, this requires a large number of parts to adjust the height, making it expensive to manufacture.

[0007] The cutting height can also be adjusted by inserting or removing a spacer between the cutting blade and the drive shaft, to which the cutting blade is secured. This adjustment involves removing the blade from the drive shaft, inserting or removing the spacer, and bolting the blade back onto the drive shaft. This operation is relatively complex and time-consuming, and requires storing the spacer.

[0008] EP 531071 discloses a method of displacing the cutting member against a compression spring to change the cutting height of the mower, and EP 766911 discloses a method of displacing the chassis of the mower to change the cutting height of the mower.

[0009] EP 3935933 discloses a lawnmower comprising at least two engagement platform devices connected to a cutting disc, the engagement platform devices being separated from each other along a vertical extension and adapted to receive a connecting member included in a drive shaft. This allows the cutting disc to have a specific vertical position depending on which engagement platform device receives the connecting member secured by bolts.

[0010] CN 103621244 discloses a lawnmower having a cutting head and a transmission component, the transmission component being provided with a mating connection surface for connecting to the cutting head in a mating mode. The cutting head is provided with a first mounting surface and a second mounting surface for connecting adjacent to the mating connection surface, with one mounting surface on each side of the cutting head. By rotating the cutting head, the user can switch between two different cutting heights.

[0011] However, there is a need to provide an improved and alternative device for setting the mowing height of a lawnmower, which is more versatile, simple and effective than the previously proposed device, requires fewer parts and does not require special tools. Summary of the Invention

[0012] The objective of this disclosure is to provide an improved and alternative device for setting the mowing height of a lawnmower, which is more versatile, simple and effective than previously proposed devices, requires fewer parts and does not require specialized tools.

[0013] This objective is achieved by a lawnmower cutting unit comprising: a cutting propulsion unit having a drive shaft adapted to rotate about a common axis of rotation; a hub rotatably connected to the drive shaft; a cutting disc; and a knob. The knob is rotatably connected to the hub such that it is adapted to rotate together with the hub and the drive shaft. The cutting disc is displaced along the common axis of rotation against the elastic force of a spring element. The cutting disc and the knob are included in a coupling joint, which is incorporated into the lawnmower cutting unit and adapted to transmit rotational torque from the hub to the cutting disc. The coupling joint is adapted to releasably lock the cutting disc along the common axis of rotation in a plurality of mutually separated positions by means of elasticity, thereby assigning an associated specific mowing height to each locked position.

[0014] This means that the mowing height can be adjusted by moving the cutting disc along a common axis of rotation and locking the cutting disc in a position corresponding to the desired mowing height.

[0015] According to some aspects, the cutting disc includes a connecting portion comprising an orifice and at least two engaging recesses formed in the orifice and extending parallel to a common axis of rotation to at least two different depths. A knob includes at least one engaging protrusion extending away from the common axis of rotation and adapted to transmit rotational torque transmitted from the hub to the cutting disc via a corresponding engaging recess. The recesses are adapted to receive the engaging protrusion along the common axis of rotation in at least two different mounting positions. The mounting positions are spring-locked such that the cutting disc has a specific vertical position along the common axis of rotation, depending on which engaging recess receives the corresponding engaging protrusion.

[0016] This means that mowing height can be adjusted by moving the cutting disc along a common axis of rotation and locking it in a position corresponding to the desired mowing height, without the need for any tools.

[0017] According to some aspects, the lawnmower cutting unit also includes a cover adapted to seal the end of the orifice that faces the ground surface during operation of the lawnmower cutting unit.

[0018] The cover prevents unwanted particles such as grass, debris, and dust from entering the orifice.

[0019] According to some aspects, the common axis of rotation extends through the center of the knob. This means that the knob is symmetrical about the connection joint.

[0020] According to some aspects, the connecting portion includes at least two pairs of opposing engagement recesses, with two of the two engagement recesses in each pair having the same depth along a common axis of rotation. According to some aspects, the knob includes two opposing connecting protrusions adapted to engage a pair of opposing engagement recesses.

[0021] When a pair of opposing engagement recesses are engaged via the connecting protrusion, a stable transmission of rotational torque is provided from the knob to the cutting disc.

[0022] According to some aspects, the connecting joint includes: a spring element adapted to surround the hub; a knob; a recess; a first spring element retainer; and a second spring element retainer.

[0023] This means that the joints consist of relatively few parts, resulting in low production costs and high reliability.

[0024] According to some aspects, the first spring element retainer is a retaining ring adapted to abut against a motor flange included in the cutting and propulsion unit, and the second spring element retainer is included in the connecting portion. The spring element is in the form of a helical spring positioned between the spring element retainers.

[0025] This means that the spring element can apply elastic force in a reliable and desired manner.

[0026] According to some aspects, the connecting joint includes a sleeve adapted to be positioned within the connecting part and surrounding the hub. The sleeve stabilizes the hub.

[0027] According to some aspects, the cutting disc can resist the elastic force of the spring element and move along a common axis of rotation as it moves toward the cutting propulsion unit. This means that the elastic force propels the cutting disc away from the cutting propulsion unit and enables a simple design and easy management of the mowing height settings.

[0028] This goal is also achieved through lawnmowers and cutting discs, which are associated with the advantages mentioned above. Attached Figure Description

[0029] This disclosure will now be described in more detail with reference to the accompanying drawings, in which:

[0030] Figure 1 A schematic side view of a robotic lawnmower is shown.

[0031] Figure 2 A first exploded schematic diagram of a lawnmower cutting unit included in a robotic lawnmower is shown.

[0032] Figure 3 A second exploded view shows a lawnmower cutting unit included in a robotic lawnmower;

[0033] Figure 4 A schematic side sectional view of the lawnmower cutting unit in the first locked position is shown;

[0034] Figure 5 A schematic side sectional view of the lawnmower cutting unit in the second locked position is shown;

[0035] Figure 6 A schematic bottom side view of the cutting disc is shown, illustrating the first step for setting the mowing height;

[0036] Figure 7 A schematic bottom side view of the cutting disc is shown, illustrating the second step for setting the mowing height;

[0037] Figure 8 A schematic bottom side view of the cutting disc is shown, illustrating the third step for setting the mowing height; and

[0038] Figure 9 A schematic bottom side view of the cutting disc is shown, illustrating the fourth step for setting the mowing height. Detailed Implementation

[0039] Various aspects of this disclosure will be described more fully below with reference to the accompanying drawings. However, the different apparatuses, systems, computer programs, and methods disclosed herein may be implemented in many different forms and should not be construed as limited to the aspects set forth herein. In the drawings, similar reference numerals refer to similar elements.

[0040] The terminology used herein is for the purpose of describing various aspects of this disclosure only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein are intended to include the plural forms as well.

[0041] It should be noted that although the descriptions given in this article will focus on robotic lawnmowers, the teachings in this article can also be applied to any type of lawnmower with rotating blades.

[0042] Figure 1 A lawnmower 100 according to some embodiments of the present disclosure is schematically illustrated. According to the illustrated embodiments, the lawnmower 100 is a self-propelled autonomous robotic lawnmower 100 capable of autonomously navigating and mowing grass in an area without user intervention or control. This can be achieved through one or more environmental detection sensors, such as lidar, radar, and / or ultrasonic sensors, and boundary line sensors suitable for sensing boundary line control signals. Alternatively or alternatively, a navigation device, such as a GPS (Global Positioning System) device, may also be used.

[0043] Figure 1 A schematic side view of a robotic lawnmower 100 is shown, which is adapted for forward travel in the direction D and has a body 105 and multiple wheels 106, 107; in this example, the robotic lawnmower 100 has four wheels 106, 107, two rear wheels 106 and two front wheels 107, wherein the wheels 106, 107 are shown here in contact with a flat ground surface 108.

[0044] The robotic lawnmower 100 includes a control unit 110 and a first electric motor 150 adapted to provide power and / or steering to the robotic lawnmower 100. In this example, the rear wheel 106 is powered and constitutes the drive wheel, and steering can be achieved by rotating the rear wheel 106 in different directions. The unpowered wheel (here, the front wheel 106) constitutes the support wheel, which may be in the form of a pivotable caster along the direction of travel D.

[0045] According to another embodiment, the robotic lawnmower 100 may be provided with another number of wheels, such as three wheels. Furthermore, according to another embodiment, the robotic lawnmower 100 may be provided with another configuration of drive wheels and non-drive wheels, such as front-wheel drive or all-wheel drive.

[0046] According to the illustrated embodiment, the control unit 110 can be configured to control the propulsion of the robotic lawnmower 100 and to steer the robotic lawnmower 100 by controlling the drive wheels 106 of the robotic lawnmower 100.

[0047] It should be noted that although the description in this article focuses on electric motors, internal combustion engines can alternatively be used in combination with electric motor devices.

[0048] The robotic lawnmower 100 includes a charging pad 156 for contacting a contact plate (not shown) of the charging station when docked to the charging station, for receiving charging current and for transmitting information via electrical communication between the charging station and the robotic lawnmower 100.

[0049] The robotic lawnmower 100 also includes at least one rechargeable power source (e.g., battery 155) to power the electric motor device 150. The battery 155 is arranged to be charged by a charging current received from a charging station via a charging pad 156 or other suitable charging connector.

[0050] like Figures 2 to 5 As shown, the robotic lawnmower 100 also includes a lawnmower cutting unit 102, which includes a mowing device 160 and a cutting motor 165 (or more generally, a cutting propulsion unit 165), which is also powered by a battery 155 or alternatively by a separate power source. The cutting propulsion unit 165 is adapted to drive the mowing device 160 and includes a drive shaft 169 adapted to rotate about a common axis of rotation Ax.

[0051] In this example, such as Figures 6 to 9 As shown, the mowing device 160 comprises a cutting disc 160, which, according to some aspects, includes a plurality of cutting blades, such as cutting blades 123, 124, and 125. According to some aspects, each cutting blade 123, 124, and 125 is pivotally arranged such that, during normal operation, these cutting blades are held in a working position due to centripetal force, extending radially outward from the center of the cutting disc. Of course, many types and numbers of cutting blades are conceivable.

[0052] Also refer to Figures 2 to 5 The lawnmower cutting unit 102 includes: a hub 166 rotatably connected to a drive shaft 169; and a knob 120 rotatably connected to the hub 166 such that the knob 120 is adapted to rotate together with the hub 166 and the drive shaft 169.

[0053] According to this disclosure, the cutting disc 160 can be displaced along a common axis of rotation Ax against the elastic force of the spring element 130. The cutting disc 160 and the knob 120 are included in a coupling engagement 140 adapted to transmit rotational torque transmitted from the hub 166 to the cutting disc 160. The coupling engagement 140 is adapted to releasably lock the cutting disc 160 along the common axis of rotation Ax into a plurality of mutually separated positions by means of elasticity, thereby assigning an associated specific mowing height to each locked position. The coupling engagement 140 is included in the lawnmower cutting unit 102.

[0054] This means that the mowing height can be adjusted by shifting the cutting disc 160 along the common axis of rotation Ax and locking the cutting disc 160 in a position corresponding to the desired mowing height.

[0055] According to some aspects, the cutting disc 160 includes a connecting portion 164 comprising an orifice 161 and at least two engaging recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b, which are formed in the orifice 161 and extend parallel to a common axis of rotation Ax to at least two different depths. The knob 120 includes at least one connecting protrusion 121, 122 extending away from the common axis of rotation Ax and adapted to transmit rotational torque from the hub 166 to the cutting disc 160 via the corresponding engaging recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b. Recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b are adapted to receive connecting protrusions 121, 122 along a common axis of rotation Ax in at least two different mounting positions, wherein the mounting positions are spring-locked such that the cutting disc 160 has a specific vertical position along the common axis of rotation Ax, the specific vertical position depending on which engaging recess 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b receives the corresponding connecting protrusion 121, 122.

[0056] This means that the mowing height can be adjusted by shifting the cutting disc 160 along the common axis of rotation Ax and locking the cutting disc 160 in a position corresponding to the desired mowing height without the need for any tools.

[0057] According to some aspects, the cutting disc 160 can resist the elastic force of the spring element 130 and shift along the common axis of rotation Ax as it moves toward the cutting propulsion unit 165. This means that the elastic force causes the cutting disc to move away from the cutting propulsion unit 165 and achieves a simple design and easy-to-manage mowing height setting. Figures 2 to 9 The example shown is an example of this.

[0058] It is also conceivable that when the cutting disc 160 is displaced away from the cutting advance unit 165 (e.g., when pulled toward the user while adjusting the mowing height), it can resist the elastic force of the spring element and shift along the common axis of rotation Ax. In this case, the connecting joint 140 must be designed accordingly; for example, the recess must extend in the opposite direction along the common axis of rotation Ax. Although the details of this design are not described here, those skilled in the art can certainly easily implement it.

[0059] According to some aspects, the connecting portion 164 includes at least two pairs of opposing engagement recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b, wherein two of the two engagement recesses in each pair of opposing engagement recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b have the same depth along a common axis of rotation Ax. The depth of each recess 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b is limited by the corresponding heels 176, 177, 178, and each connecting protrusion 121, 122 abuts against these heels and is pressed against the corresponding heels 176, 177, 178 by the elastic force of the spring element 130 (for clarity, in...). Figure 9 Only a few heel sections (176, 177, 178) are shown in the image.

[0060] exist Figures 2 to 9In the example shown, the connector 164 includes five pairs of opposing engagement recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b, which are numbered 1 to 5 in the cutting disc 160, and according to some other aspects, the knob 120 includes two opposing connecting protrusions 121, 122 adapted to engage a pair of opposing engagement recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b. In this example, there are a first pair of opposing engagement recesses 171a and 171b, a second pair of opposing engagement recesses 172a and 172b, a third pair of opposing engagement recesses 173a and 173b, a fourth pair of opposing engagement recesses 174a and 175b, and a fifth pair of opposing engagement recesses 175a and 175b. The depth gradually decreases from the first pair of opposing engagement recesses 171a and 171b to the fifth pair of opposing engagement recesses 175a and 175b.

[0061] When a pair of opposing engagement recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b are engaged, this provides a stable transmission of rotational torque from the knob 120 to the cutting disc 160 via the connecting protrusions 121, 122.

[0062] According to some aspects, the knob 120 can be accessed from the bottom side S1 of the robotic lawnmower 100, which faces the ground surface 108 during operation of the robotic lawnmower 100.

[0063] This means that the knob is easily accessible when adjusting the mowing height.

[0064] According to some aspects, the connecting joint 140 includes a spring element 130 adapted to surround the hub 166. The connecting joint 140 also includes a knob 120, recesses 171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b, a first spring element holder 131, and a second spring element holder 132.

[0065] This means that the connecting joint 140 includes relatively few parts, which results in low production costs and high reliability.

[0066] According to some aspects, the common axis of rotation Ax extends through the center of the knob 120. This means that the knob 120 is symmetrically positioned relative to the connecting joint 140.

[0067] According to some aspects, the cutting and propulsion unit 165 is mounted in a motor flange 167, which secures the cutting and propulsion unit 165 in a fixed position. According to some other aspects, the first spring element holder 131 is a retaining ring adapted to abut against the motor flange 167, and the second spring element holder 132 is included in a connecting portion 164, wherein the spring element 130 is in the form of a helical spring positioned between the spring element holders 131 and 132. This means that the spring element 130 can apply elastic force reliably and in a desired manner.

[0068] According to some aspects, the second spring element retainer 132 is a separate component that fits into the connecting portion 164.

[0069] According to some aspects, the connecting joint 140 includes a sleeve 134 adapted to be positioned within the connecting portion 164 and surrounding the hub 166. The hub 166 operates within the sleeve 134, which stabilizes the hub 166. According to some aspects, the sleeve 134 is a separate component or integral with the connecting portion 164.

[0070] Based on several aspects, an example of the operation of the connecting joint 140 will now be described in more detail. Figure 4 and Figure 6 The cutting disc 160 is shown in its highest position (i.e., furthest from the ground surface 108) and corresponding to the maximum mowing height. A helical spring 130 operates between a retaining ring 131 and a second spring element retainer 132 included in the connecting portion 164.

[0071] A retaining ring 131 abuts against the flange portion 166a of the hub 166, such that the coil spring 130, retaining ring 131, and second spring element retainer 132 are adapted to rotate together with the hub 166. An annular seal 133 surrounds the drive shaft 169 to provide a seal, and the annular seal fits in a collar portion 135, which is included in the motor flange 167. Here, the coil spring 130 is in its maximum compression state in the operating position, and the connecting protrusions 121, 122 engage the heels of the fifth pair of opposing engagement recesses 175a, 175b, which have a minimum depth along the common axis of rotation Ax and are marked "5" on the cutting disc 160. This brings the cutting disc 160 to the operating position closest to the cutting advance unit 165.

[0072] exist Figure 7In this process, the cutting disc 160 is pressed against the cutting propulsion unit 165 by the resistance spring force, causing the connecting protrusions 121, 122 to disengage from the heels of the fifth pair of opposing engagement recesses 175a, 175b, thereby disengaging from these heels. This means that the helical spring 130 is compressed slightly more than its maximum compression state in the operating position, and the cutting disc 160 is brought closer to the cutting propulsion unit 165.

[0073] Now, as Figure 8 As shown, the cutting disc can be rotated about a common axis of rotation Ax relative to the knob 120, thereby allowing another pair of opposing recesses to be selected for the connecting protrusions 121, 122. In this example, the first pair of opposing engaging recesses 171a, 171b, which have the greatest depth along the common axis of rotation Ax and are marked "1" on the cutting disc 160, are selected.

[0074] like Figure 5 and Figure 9 As shown, when the cutting disc 160 is released, the spring force causes the connecting protrusions 121, 122 to engage with the heels of the selected first pair of opposing engagement recesses 171a, 171b, which brings the cutting disc 160 to its lowest position (i.e., closest to the ground surface 108) and corresponds to the minimum mowing height. Here, the coil spring 130 is in its maximum extension state, and the connecting protrusions 121, 122 engage with the first pair of opposing engagement recesses 171a, 171b having the maximum depth along the common axis of rotation Ax.

[0075] In this manner, either pair of opposite recesses can be selected for the connecting protrusions 121 and 122, thereby positioning the cutting disc 160 in the corresponding position along the common axis of rotation Ax to impart the corresponding mowing height.

[0076] When the cutting disc 160 is properly positioned, a cover 126 can be used to seal one end of the opening 161, which is adapted to face the ground surface 108 during operation of the lawnmower cutting unit 102 and during operation of the robotic lawnmower 100. The cover prevents unwanted particles such as grass, debris, and dust from entering the opening 161.

[0077] The collar portion 135 is adapted not to contact the hub portion 166. Figure 2 , Figure 4 and Figure 5 The image shows flange portion 166a including step 166b. Figure 2 (as shown in the diagram) to avoid the contact.

[0078] This disclosure is not limited to the foregoing, but can be freely varied within the scope of the claims. For example, although the above description is directed to a robotic lawnmower 100, this disclosure is applicable to any type of lawnmower having at least one motor-driven cutting disc, such as a robotic lawnmower, a manual lawnmower with or without motor-driven wheels, and a ride-on lawnmower.

[0079] Although two coupling protrusions are shown in the example, the knob may include more or fewer coupling protrusions. At least one coupling protrusion is adapted to engage the corresponding heel of the recess such that the mowing height is defined by the position of the cutting disc 160 along the common axis of rotation Ax.

[0080] The connecting portion 164 includes at least two engaging recesses having different depths along a common rotation axis Ax. As previously described, the engaging recesses can be arranged in pairs relative to the common rotation axis Ax and in opposite positions, wherein two opposing engaging recesses have equal depths along the common rotation axis Ax. In this case, there should be at least two pairs of opposing engaging recesses, wherein these pairs of opposing engaging recesses have different depths along the common rotation axis Ax.

[0081] According to some aspects, the hub 166 is press-fitted to the drive shaft 169. According to some aspects, the hub 166 and the drive shaft 169 have cylindrical shapes and run along a common axis of rotation Ax. The hub 166 may be at least partially hollow, thereby allowing its threaded connection to the drive shaft 169 and a secure fit by press-fit or other types of fit. Of course, other methods of securing the hub 166 to the drive shaft 169 are also conceivable, such as gluing, welding, and / or fastening bolts or pins. It is even conceivable that the hub 166 and the drive shaft 169 are formed as a single component. According to some aspects, the hub 166 and the retaining ring 131 are formed as a single component. According to some other aspects, the retaining ring 131 is attached to the hub 166.

[0082] In some respects, the knob is connected to the hub by bolts 127, allowing for easy replacement if one or more connecting protrusions become braked. Such bolts may be included in the connecting joint 140.

[0083] Other types of spring elements can be conceived, and in some respects, the cutting disc 160 should be able to resist the elastic force of the spring element 130 as it moves toward the cutting advance unit 165 and shifts along the common axis of rotation Ax.

[0084] According to some aspects, the lawnmower cutting unit 102 includes a connecting joint 140, a cover 126, a seal 133, a motor flange 167, and a cutting propulsion unit 165. According to some aspects, certain details of, for example, the cover 126 and the seal 133 are optional in the lawnmower cutting unit 102.

Claims

1. A lawnmower cutting unit (102) comprising: A cutting propulsion unit (165) having a transmission shaft (169) adapted to rotate about a common rotation axis (Ax); a hub (166) rotatably connected to the transmission shaft (169); a cutting disc (160); and a knob (120) rotatably connected to the hub (166) so that the knob (120) is adapted to rotate with the hub (166) and the transmission shaft (169), wherein the cutting disc (160) is displaceable along the common rotation axis (Ax) against a spring force of a spring element (130), wherein the cutting disc (160) and the knob (120) are comprised in a coupling interface (140) comprised in the lawnmower cutting unit (102) and adapted to transmit a rotational torque transmitted from the hub (166) to the cutting disc (160), the coupling interface (140) being adapted to releasably lock the cutting disc (160) in a plurality of mutually separate locking positions along the common rotation axis (Ax) by means of the spring force, thereby imparting for each locking position an associated specific mowing height; wherein the cutting disc (160) comprises a connection (164) comprising an aperture (161) and at least two engagement recesses (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b) formed in the aperture (161) and extending to at least two mutually different depths parallel to the common rotation axis (Ax), and wherein the knob (120) comprises at least one coupling protrusion (121, 122) extending away from the common rotation axis (Ax) and adapted to transmit a rotational torque transmitted from the hub (166) to the cutting disc (160) via a corresponding engagement recess (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b), the engagement recess (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b) being adapted to receive the coupling protrusion (121, 122) in at least two different mounting positions along the common rotation axis (Ax), wherein the mounting positions are locked by means of the spring force so that the cutting disc (160) has a specific vertical position along the common rotation axis (Ax) depending on which engagement recess (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b) receives the corresponding coupling protrusion (121, 122).

2. The lawnmower cutting unit (102) according to claim 1, further comprising a cover (126) adapted to seal an end of the aperture (161) adapted to face a ground surface (108) during operation of the lawnmower cutting unit (102).

3. The lawnmower cutting unit (102) according to any one of the preceding claims, wherein, The common rotation axis (Ax) extends through a central portion of the knob (120).

4. The lawnmower cutting unit (102) according to the preceding claim 1 or 2, wherein The connection portion (164) comprises at least two pairs of opposite engagement recesses (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b), the two engagement recesses of each pair of opposite engagement recesses (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b) having the same depth along the common rotation axis (Ax).

5. The lawnmower cutting unit (102) according to claim 4, wherein, The knob (120) comprises two opposite coupling protrusions (121, 122) adapted to engage a pair of opposite engagement recesses (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b).

6. The lawnmower cutting unit (102) according to the preceding claim 1 or 2, wherein The coupling engagement portion (140) comprises: The spring element (130) is adapted to surround the hub portion (166); The knob (120); The engagement recesses (171a, 171b; 172a, 172b; 173a, 173b; 174a, 174b; 175a, 175b); a first spring element holder (131); and a second spring element holder (132).

7. The lawnmower cutting unit (102) according to claim 6, wherein, The first spring element holder (131) is a retaining ring adapted to abut against a motor flange (167) comprised in the cutting propulsion unit (165), and the second spring element holder (132) is comprised in the connection portion (164), wherein the spring element (130) is in the form of a coil spring positioned between the first spring element holder (131) and the second spring element holder (132).

8. The lawnmower cutting unit (102) according to the preceding claim 1 or 2, wherein The coupling engagement portion (140) comprises a sleeve (134) adapted to be positioned in the connection portion (164) and around the hub portion (166).

9. The lawnmower cutting unit (102) according to any of the preceding claims 1-2, wherein, The cutting disc (160) is displaceable along the common rotation axis (Ax) against the spring force of the spring element (130) when displaced towards the cutting propulsion unit (165).

10. A lawnmower (100) comprising the lawnmower cutting unit (102) according to any one of claims 1 to 9.

11. The lawnmower (100) according to claim 10, wherein The knob (120) is accessible from a bottom side (SI) of the lawnmower (100), the bottom side (SI) facing a ground surface (108) during operation of the lawnmower (100).

Images