Spool for a cutting head

Abstract

The invention starts from a cutting head (42) for a lawn trimmer (10), wherein the cutting head (42) is provided for automatically re-lengthening a cutting thread (44), having an oscillation lever (820) which is oscillatably supported about an oscillation lever rotation axis (822). It is proposed that, in a locked position of the oscillation lever (820), in particular wherein the cutting thread (44) is not being re-lengthened, a center of gravity (886) of the oscillation lever (820) has a radial distance to a rotation axis (60) of the cutting head (42) which is substantially the same or greater compared to a radial distance of the oscillation lever rotation axis (822) to the rotation axis (60) of the cutting head (42).

Description

[0001] This case is a divisional application of the patent application filed on April 23, 2019, with application number 201980027438.X and invention title "Cut head for lawn mower". Background Technology

[0002] A spool for a cutting head, for example, a lawnmower, is known according to the preamble of claim 1. Summary of the Invention

[0003] The present invention is a cutting head for a lawn mower, wherein the cutting head is configured to automatically extend the cutting line, the cutting head having a swing arm that is oscillatingly supported about a swing arm rotation axis.

[0004] It is proposed that, in the locked position of the oscillating lever (so that the cutting line is not re-extended or re-guided), the center of gravity of the oscillating lever has a radially approximately equal or greater distance from the rotation axis of the cutting head compared to the distance between the rotation axes of the oscillating lever and the rotation axis. The cutting head also has a housing. The spool can be arranged coaxially with the rotation axis on the housing. The oscillating lever interacts with the re-guided profile of the spool. This provides a locking device and a readjustment device for the cutting line. The oscillating lever is eccentrically supported on the housing relative to the rotation axis. The oscillating lever can move from the locked position to a re-guided or re-extended position in which the free line length is extended, which can extend radially from the cutting head. According to centrifugal force and / or according to acceleration (especially during braking), relative rotation between the spool and the housing can be achieved for the purpose of line readjustment or re-extending.

[0005] Advantageously, this allows for wire re-extension even when the lawnmower is turned off and / or the cutting head is stopped. With prolonged use of the cutting wire without significant wear at its tip, wear at the eyelet or the exit point where the cutting wire exits the spool is thus reduced. Sometimes, the cutting wire breaks not at its tip, but at the transition from the inside to the outside of the cutting head. Consequently, the cutting wire slides into the cutting head or eyelet, and the user must laboriously open the cutting head, manually extend the cutting wire, and then guide it outward through the eyelet again. Over-extension is avoided because a stop edge is typically provided on the lawnmower's protective cover, thus limiting the cutting wire to a defined maximum length. According to the invention, when the device is turned off, the cutting wire is extended by at least one increment, pre-defined by the re-guiding profile. Furthermore, the cutting wire is also extended when wear and breakage occur during rotational operation, for example, due to the user hitting or processing a hard object, such as stone, metal parts, or even a blade-like object. Here, the further elongation is achieved in a known manner due to the centrifugal force balance of the cutting line, the shift of the center of gravity of the swing arm and / or the centrifugal mass of the drive element, or the re-guided profile. In summary, according to the present invention, the operation of the lawn mower becomes more convenient and reliable.

[0006] Furthermore, a lawn mower is claimed to have a cutting head for automatically re-extending the cutting line, particularly having the aforementioned cutting head. It is proposed that the cutting line automatically re-extends when the cutting head is stopped or braked and / or the drive of the cutting head or lawn mower is turned off. This achieves the aforementioned advantages.

[0007] Furthermore, a method for operating a lawnmower with a cutting head rotatable about a rotation axis is proposed. This cutting head has a mechanism for automatically re-extending the cutting line, particularly the aforementioned mechanism, wherein, upon stopping or braking the cutting head and / or shutting off the lawnmower's drive, the cutting line is automatically re-extended, particularly by a length similar to that of a re-guide link. Building upon existing automatic re-guided mechanisms that only re-extend when the cutting line wears or shortens, according to the present invention, in addition to or in addition to wear-related re-extending, the cutting line is re-extended, particularly each time the motor or lawnmower stops, and thereby reaches the desired length. Thus, vibration, or undesirable vibration, can be limited to at least a smaller area. Convenience is improved. Continuous re-guided operation is ensured. Therefore, the previously known purely wear-based re-guided mechanisms are improved or extended.

[0008] A method for re-extension is proposed, achieved by arranging the center of gravity of the oscillating arm in such a way that, when the cutting head is braked or stopped, the oscillating arm is transferred to a reguided position by a braking torque acting upon it. The center of gravity of the oscillating arm is arranged, particularly circumferentially, off-axis relative to the axis of rotation of the oscillating arm and / or in a region with the same or greater radial distance about the axis of rotation as the axis of rotation of the oscillating arm, thus enabling oscillation and re-extension during stopping or braking. Furthermore, this occurs when the cutting head rotates in one or the other direction of rotation, i.e., whether clockwise or counterclockwise, extension occurs during braking. Ideally, the center of gravity in the locked position of the re-extension mechanism is arranged with the same radial distance about the axis of rotation as the axis of rotation of the oscillating arm. The center of gravity is located in the region of the oscillating arm's centrifugal mass. This center of gravity is opposite the arm or profile sliding bolt about the axis of rotation of the oscillating arm.

[0009] Furthermore, a cutting head for a lawn mower is proposed, wherein the housing of the cutting head has an eyelet for leading out the cutting line, characterized in that the eyelet is U-shaped and open on one side. This allows for easy insertion or replacement of the cutting line. Guiding the cutting line through the hole or closed eyelet in the housing or cover is effortless. A positioning extension on the cover provides a clamping and / or positioning function during this process. This enhances user convenience. Constructing the eyelet as a metal component increases wear on the housing. The corners are rounded. The eyelet extends beyond the surrounding plastic housing, thereby dispersing the force. Wear on the cutting head is thus mitigated.

[0010] Furthermore, protection is claimed for a cutting head for a lawnmower, and particularly for a spool for the aforementioned cutting head or lawnmower, wherein the spool has a thread-end retaining recess parallel to the axis of rotation of the spool, the thread-end retaining recess being disposed on the winding surface of the spool, centrally or radially inside, and having a spool clamping device disposed radially inside the winding surface of the spool. This allows for the simple and reliable installation of new or replacement thread onto the spool. It avoids undesirable complete detachment of the cutting thread when it tilts towards its end. It ensures reliable fixation of the cutting thread on the spool.

[0011] Furthermore, it is proposed that the spool clamp is arranged axially (particularly spaced from the end face of the outlet of the spool fixing recess) below the spool winding surface, specifically from the radially inner to the radially outer side of the spool winding surface. This achieves two deflections and thus ensures reliable fixing of the cut wire.

[0012] Furthermore, it is proposed that the spool clamp be provided with at least two deflections for arranging the cutting wire on the spool, preferably a first deflection of >90° in a first direction and a deflection of >0° in a second deflection direction; in particular, it is proposed to provide a deflection of >135° in the first deflection direction and a deflection of >30° in the second deflection direction for arranging the cutting wire on the spool. Thus, reliable fixing of the cutting wire end is achieved in a simple and easily implemented or operable manner, for example, when replacing or refitting the spool.

[0013] Furthermore, it was proposed that the outlet of the wire fixing recess be arranged parallel to the end face plane of the spool.

[0014] Furthermore, it is proposed that an inclined surface be provided on the inner side of the spool winding surface at the online entry point, specifically, wherein the plane of the inclined surface is flush with the spool pressure device. This avoids bending of the thread, disperses the force, and achieves very smooth winding of the cutting thread (without protrusion on the side of the spool winding surface).

[0015] In addition, a method for winding the cutting wire of a lawn mower onto a spool is claimed, the method comprising the steps of: inserting the cutting wire (Schneidens) into a wire end fixing recess, deflecting the cutting wire by a spool wire presser, causing the cutting wire to re-deflect through the wire inlet toward the spool winding surface, and winding the cutting wire onto the spool winding surface.

[0016] Furthermore, it is proposed that the lawnmower or shrub cutter has a V-shaped handle unit; and / or, the center of gravity of the handheld tool is arranged along the longitudinal axis of the spacer unit and / or the main body; and / or, the center of gravity is located in the area of ​​the swing unit of the handle unit; and / or, the processing unit is arranged on one side of the longitudinal axis of the spacer unit and / or the main body, and the handle unit or at least one handle is arranged on the other side; and / or, there is a torque balance between the processing unit and the handle unit about the longitudinal axis of the spacer unit and / or the main body.

[0017] A cutting head for a lawn mower, wherein the cutting head is configured to automatically re-extend the cutting line, the cutting head having a swing arm that is oscillatingly supported about a swing arm rotation axis, characterized in that, in the locked position of the swing arm, particularly where the cutting line is not re-extended, the center of gravity of the swing arm relative to the rotation axis of the cutting head has a radially approximately equal or greater distance than the rotation axis of the swing arm relative to the rotation axis of the cutting head.

[0018] A lawn mower having a cutting head for automatically extending the cutting line, particularly having a cutting head according to any one of the foregoing technical solutions, characterized in that the cutting line is automatically extended when the cutting head is braked or stopped, and / or when the drive unit of the cutting head or the lawn mower is turned off.

[0019] A method for operating a lawn mower having a cutting head rotatable about a rotation axis, the cutting head having a mechanism for automatically re-extending the cutting line, characterized in that the cutting line is automatically re-extended when the cutting head is stopped or braked and / or the drive unit of the lawn mower is turned off.

[0020] A cutting head, lawn mower, or method, particularly according to any one of the foregoing technical solutions, is characterized in that the center of gravity of a swing arm is arranged on the cutting head for automatic reguiding or re-extending of the cutting line, whereby, when the cutting head is braked or stopped, the swing arm is switched to a reguiding or re-extending position by a braking torque acting on the swing arm.

[0021] The cutting head, lawn mower, or method according to any one of the foregoing technical solutions is characterized in that, in the case of braking or stopping, it provides a re-extension function independent of the rotation direction of the cutting head.

[0022] A cutting head for a lawn mower, particularly according to any one of the foregoing technical solutions, wherein the housing of the cutting head has an eyelet for leading a cutting line out of the cutting head, characterized in that the eyelet is U-shaped and open on one side.

[0023] According to the cutting head described in the above technical solution, the cutting head is configured such that the cutting wire can be inserted into the U-shaped orifice in an axial direction parallel to the rotation axis of the cutting head, and in particular, the wire outlet can be closed by a cover, preferably by a cover having a positioning extension for closing the open U-shaped orifice. Attached Figure Description

[0024] Other advantages arise from the following description of the accompanying drawings. The drawings, description, and claims contain multiple combinations of features. Those skilled in the art can also observe the stated features individually and combine them into other meaningful combinations.

[0025] The attached diagram shows:

[0026] Figure 1 A lawn mower according to the invention is shown in front view.

[0027] Figure 2 The cutting head according to the present invention is shown in a perspective view.

[0028] Figure 3 The cutting head according to the invention is shown in an exploded view.

[0029] Figure 4 Cross-sectional and detailed views of the cutting head according to the present invention are shown.

[0030] Figure 5 The diagram shows a bottom view of the cutting head with the cover removed, a cross-sectional view DD (with the cover) of the cutting head with the shell cut open, and a top view.

[0031] Figure 6 The perspective views of the housing with and without the spool are shown in top, side, and bottom views, with the spool also shown alongside.

[0032] Figure 7 The top view shows a housing with a swing arm arranged thereon, and the bottom view shows a housing with the swing arm in the locked position along with a guide profile to illustrate their interaction.

[0033] Figure 8 The diagram shows three stages of the oscillating rod and the reguided profile in the release or re-elongation position for the re-elongation of the cutting line or for the relative rotation of the spool relative to the housing. Detailed Implementation

[0034] Figure 1A lawnmower 10 is shown. The lawnmower 10 has a handle unit 12. The handle unit 12 includes at least one first handle 14. Furthermore, the handle unit 12 includes a second handle 16. The first handle 14 is connected to the second handle 16 via a connecting unit 18. The second handle 16 is movably or unfoldable relative to the first handle 14. In particular, the second handle 16 is pivotable relative to the first handle 14 or relative to the main pipe 22 via a swing unit 20. The swing angle is an acute angle 24. Thus, the handle unit 12 occupies a V-shaped position in the working position. The swing unit 20 is shown as part of the connecting unit 18 or the handle unit 12. The swing unit 20 is detachable via a release element 26. Thus, it can be unfolded and / or folded by the user. The handle unit 12 is fastened to the main pipe 22 or link of the lawnmower 10. The handle unit 12 can also be part of the main pipe 22 or link. The second handle 16 is also connected to the swing unit 20 via a tube 28. The tube 28 is partially shown as part of the handle unit 12 or the connecting unit 18. The main tube 22 or tube 28 is at least partially surrounded by connecting or reinforcing elements 30. These connecting or reinforcing elements can be integrally or in multiple pieces with the corresponding handles 14, 16. The connecting or reinforcing elements reinforce the positions of the handles 14, 16. They at least partially surround the main tube 22 and the tube 28. However, other arbitrary handle configurations are also conceivable, such as a configuration with one handle on the main tube 22 and another handle on the upper end of the main tube, or a similar configuration.

[0035] The handle unit 12 is connected to the processing unit 38 via a spacer unit 32 or a telescopic unit 34, here via another tube 36, particularly a telescopic tube. The spacer unit 32 connects the handle unit 12 and the processing unit 38 to each other and spaces them apart. The spacer unit 32 is configured to be movable relative to the handle unit 12, or the main tube 22. The spacer unit 32 can be extended or retracted by manipulating the adjustment device 40. In this way, the lawn mower 10 can be adapted to different operating heights and / or positions or stored or transported compactly (the position is not shown here). The processing unit 38 includes a cutting head 42. The cutting head 42 has a cutting line 44. Due to the high rotational speed of the cutting line 44, the cutting line is taut by centrifugal force and thereby can cut or fell the material, especially grass or shrubs. In the present example, the cutting head 42 includes a drive unit 46. The drive unit 46 is formed here by a motor, especially an electric motor, and sometimes a rear-mounted reducer or accelerator. If the drive unit 46 rotatably drives the cutting head 42, or the cutting line 44 protruding from the cutting head 42, then grass or lawn can be cut or trimmed, or shrubs can also be cut or trimmed, using the cutting line 44 in a known manner. The drive unit 46 is exemplarily powered by a battery (not shown here). For example, here the battery can be arranged on the battery housing 52 at the end of the main pipe 22 spaced apart from the processing unit 38. This serves, as here, to improve the balance distribution of the lawnmower 10 or to improve the ergonomic design of the lawnmower 10. The battery can be said to act as a counterweight for the motor or the cutting head 42. To activate the motor, the user can operate the switch 54, particularly the accelerator switch. The switching signal and / or control signal and / or energy transfer between the handle unit 12 and the cutting head 42 can be exemplarily accomplished here by a cable (not shown) that can be laid inside the main pipe 22 and the spacer unit 32. Of course, the lawnmower 10 can have a controller or regulator that, at least from the signal from switch 54, controls or regulates the motor, and / or monitors, controls, or regulates the battery state, motor state, and / or similar states. Similarly, in the case of this gardening appliance, the motor can also be located in other parts, for example, at the end of the main pipe 22 spaced apart from the cutting head 42 (i.e., in the area of ​​the battery interface 52 shown here). The motor can supply driving power to the cutting head 42, for example, via a force transmission shaft running through the main pipe 22 and the spacer unit 32, or another pipe 36. Alternative drives, such as internal combustion engines, pneumatic devices, hydraulic devices, etc., are also contemplated.In addition, the processing unit has a protective cover 48, a spacer 50, and a foot pedal 59, which is used, for example, to perform edge cutting by swinging the processing unit 38, and the foot pedal is used here to adjust the orientation (horizontal or vertical cutting) of the cutting head 42 and the angle of the main tube 22, or the spacer 32, relative to the processing plane.

[0036] For better clarity and orientation, coordinate system 56 is depicted. Regarding the cutting head 42 presented here, or the lawnmower 10 in the horizontal cutting configuration 58, the cutting head, or cutting line 44, rotates about the axis of rotation 60, or the Y-axis. The horizontal cutting plane is defined by the X-axis and Z-axis. Here, this is also the plane in which the cutting line 44 rotates. For better illustration, the Z-axis, extending from the viewing plane of the accompanying drawings, also defines the main cutting direction 62. This main cutting direction 62 exemplarily defines the straight-ahead walking direction (Gerade-Aus-Gang) of the user of the lawnmower 10 when performing horizontal cutting.

[0037] Figure 2 The cutting head 42 is shown in perspective. The cutting head has a housing 800 and a cover 802. They are connected to each other by a locking flange 804 on the cover 802, which engages with a locking groove 806 on the housing 800. When the gripping plate 808 (with identical gripping plates, locking flanges, and locking grooves arranged on opposite sides) is manipulated or pressed, the locking flange 804 can disengage from the locking groove 806. The cover 802 can then be lifted, for example, for changing a spool or thread or for inspection. A cutting line 44 protruding from a U-shaped eyelet 810 is also shown. A positioning extension 812 on the cover 802 restricts axial movement parallel to the axis of rotation 60 of the cutting line 44 in the region of the eyelet 810. The eyelet 810 has rounded edges so that the cutting line 44 can be supported under low load. In the presence of resistance from the material to be cut, the cutting line 44 is pressed against the eyelet 810. Rounding helps prevent rapid wear. At the exit point 813 where the cutting wire 44 exits the cutting head 42, the cutting wire 44 is typically subjected to intense load. This is a possible, undesirable breakage point if there is no continuous or periodic elongation of the cutting wire 44. Furthermore, a guide plate 814, a bearing 816, and a bolt bearing 818 for a swing arm (not shown here) are present, with the rotation axis 60 of the cutting head 42 oriented at the center of this bearing.

[0038] Figure 3 The cutting head 42 is shown in an exploded view. Figure 2The same components are numbered the same and are generally not described again. The internal structure of the cutting head 42 can also be seen from the exploded view. The swing arm 820 can also be seen, which is oscillatingly supported about the swing arm rotation axis 822. The swing arm 820 has a thickened arm with a centrifugal mass 824. Opposite to it is an arm 826, which has a profile sliding bolt 828 at its free end. The profile sliding bolt 828 is oriented parallel to the swing arm rotation axis 822 and parallel to the rotation axis 60. In addition, the swing arm 820 has at least one axial stop surface 830. The axial stop surface can support the two arms relative to the housing 800. In addition, the swing arm 820 has a first radial stop surface 832 on the side of the centrifugal mass 824 and a second radial stop surface 834 on the arm 826. The swing arm 820 is axially fixed to the housing 800 by a retainer 836 via bolts (not shown) pressed into the bolt bearing 818 of the housing 800 and is oscillatingly supported.

[0039] Furthermore, a spool 838 is presented. A guide profile 840 is arranged on the upper side of the spool and is advantageously integrally constructed with the spool 838. A cutting line 44 extends from the spool 838. Below the figures, a cover 802 is shown together with its gripping plate 808, locking flange 804, and positioning extension 812. The cover also has a pin receiving portion 842.

[0040] Figure 4 A generally self-evident sectional view and detailed view of the cutting head 42 according to the invention are presented. Generally, as in the following text, repeated reference numerals from the foregoing figures are used, however, there is no obligation to restate them. Additionally, the cutting line 44 wound on the spool 838, or the spool winding surface 844, can be seen here.

[0041] Figure 5 The top view shows a bottom view of the cutting head 42 with the cover 802 removed, the middle view shows a cross-sectional view of the cutting head 42 (with the cover 802), and the bottom view shows a top view of the cutting head 42 with the cut upper side of the housing. Opposite to the cutting line 44, the housing 800 has a counterweight or balancing mass 846, which compensates for the centrifugal force emanating from the protruding cutting line 44 during rotation. Furthermore, the bolt 848 supporting the swing arm 820 can be seen in the middle view. The outer contour 850 and inner contour 852 of the guide contour 840 can be seen in the bottom view. The inner contour 852 forms a protrusion 854 or extension at the location indicated by the reference numerals, and the outer contour 850 forms a protrusion 856 radially spaced from the protrusion. This is opposite in the circumferential direction. The spool has a total of nine protrusions 854. Therefore, the cutting line increment is 1 / 9 * 2 * pi * r, where r is the distance between the wound cutting line 44 and the axis of rotation 60. The automatic re-elongation of the cutting line 44 corresponds to this cutting line increment.

[0042] Figure 6 A perspective view of the housing 800 without the spool 838 is shown in the upper left, and a perspective view of the housing 800 with the spool 838 is shown below it. On its right side, the spool 838 is shown from top to bottom in top, side, and bottom views. An axial stop surface 858 for the swing arm 820, or the arm of the swing arm, is presented in the housing 800. The housing 800 has a radial stop 859 for the swing arm 820. A fan-shaped balancing mass 846 can be seen.

[0043] The fixing of the cutting wire 44 on the spool 838 according to the invention will be described below with reference to a view of the spool 838, and the eyelet 810 according to the invention will be discussed in detail. The spool 838 has a wire end fixing recess 860 that runs parallel to the axis of rotation 60 of the spool 838. This wire end fixing recess is arranged in and / or radially inside the spool winding surface 844. A spool pressurer 862 is also visible. This spool pressurer is radially arranged inside the spool winding surface 844 about the axis of rotation 60. Furthermore, the spool pressurer 862 is axially arranged at the same height as or below the wire inlet 864 relative to the spool winding surface 844. The wire inlet 864 extends radially from the radial interior to the radial exterior of the spool winding surface 844. The spool pressurer 862 is advantageously configured with two (in opposite directions) deflections for the cutting wire 44 that can be arranged on the spool 838. Preferably, the deflection 866 is >90° in the first deflection direction and >0° in the opposite second deflection direction 868. Specifically, the deflection 866 in the first deflection direction can be >135°, and the deflection in the second deflection direction 868 can be >30°. Therefore, the cutting wire 44, which can be arranged on the spool 838, is compressed at the outlet 870 of the end-fixing recess 860 and the spool pressure device 862 due to its internal rigidity that counteracts the deflection or the two deflections, generating static friction sufficient to reliably fix or fasten the cutting wire 44 to the spool 838. The end-fixing recess 860 is slightly cut into the area of ​​the outlet 870, 871, so that the cutting wire 44 can be guided out of the end-fixing recess 860 parallel to the plane of the end face 872 of the spool 838. An arrow 874, defining the winding direction of the cutting wire 44 and recognizable by the user, is also presented on the end face 872. Correct coil orientation may be necessary in order to Figure 7 and Figure 8The automatic re-extension mechanism, described in more detail below, operates normally. Furthermore, a flare 876 is provided on the inner side 875 of the wire inlet 864 relative to the spool winding surface 844. The flare plane 878, opened by the flare, is oriented substantially flush with the spool pressurer 862. The method of mounting the cut wire 44 onto the spool 838 is described below. First, the cut wire 44 is inserted into the wire end fixing recess 860 until it axially impacts the opposing wall 880. Then, the cut wire 44 is pressed or deflected below the spool pressurer 862. By deflecting the cut wire 44 at least slightly again, it is guided through the wire inlet 864 to the spool winding surface 844. Thus, the end of the cut wire (not shown here, inserted into the wire end fixing recess 860) is reliably fixed onto the spool 838. Consequently, the remaining cut wire 44 can be wound onto the spool winding surface 844, particularly in a parallel trajectory. Finally, the free end of the cutting wire 44 is inserted into the U-shaped eyelet 810, such that the cutting wire 882 is long enough to extend beyond the radial wall 884 of the housing 800, or the cutting head 42. Through the semi-open U-shaped eyelet 810, the cutting wire 44 can be easily inserted axially without having to be inserted radially from inside the housing 800 to the outside.

[0044] Figure 7 A bottom view of the housing 800 with a swing arm 820 arranged thereon is presented above. The position of the center of gravity 886 on the swing arm 820 is also shown. A radial stop 859 for the swing arm 820 is also shown. This radial stop restricts swinging motion in both clockwise and counterclockwise directions. The arm 826 is able to strike the radial stop surface 888 once; in the case of counterclockwise rotation, the centrifugal mass 824 strikes the radial stop surface 890. Therefore, the swing arm 820 can only rotate in a restricted radial direction. The swing arm 820 is arranged opposite the wire exit 813 as a balancing mass, such as a balancing mass 846, for cutting the wire 44.

[0045] exist Figure 7Below is an illustration of the oscillating lever 820 in the locked spool 838 position, illustrating its interaction with the reguide profile 840. The oscillating lever 820 rests against the radial stop surface 888 with its arm 826. Furthermore, the profile sliding bolt 828 rests against the outer profile 850 of the reguide profile 840 in the end region 892 of the protrusion 856. The wall of the outer profile 850 is curved at approximately 90° in this end region and has a similar, slightly larger radius than the profile sliding bolt 828. The wall legs of the reguide profile are arranged radially and tangentially relative to the axis of rotation 60 and have a radius that is the same as or slightly larger than that of the profile sliding bolt 828. Arrow 894 indicates the direction of rotation of the cutting head 42. The housing 800 and the spool 838 rotate together with the cutting head. In principle, the re-extension mechanism functions normally even if the direction of rotation of the cutting head 42 is reversed.

[0046] Due to the high rotational speed of the cutting head 42 during operation, a relatively high centrifugal force acts on the cutting line 44 (see...). Figure 7 (Lower left). Because the cutting line 44 is eccentrically arranged about the axis of rotation 60 on the spool 838 (or its winding surface 844), a torque is generated on the spool 838, which pulls or rotates the spool relative to the housing 800 in the direction of arrow 874. Therefore, the force applied by the spool 838 to the profile sliding bolt 828 acts in the direction of arrow 896. This results in static friction between the profile sliding bolt 828 and the guide profile 840. Simultaneously, a centrifugal force acting radially outward (i.e., in the direction of arrow 898) acts on the oscillating rod 820 on the centrifugal mass 824. The oscillating rod, the spool, and the cutting line (including their geometry and mass) are so coordinated that the centrifugal force does not exceed the static friction at the optimal cutting length of the cutting line 44. In other words, the oscillating rod 820 does not pivot during normal rotational operation. However, once the cutting wire 44 shortens, for example due to wear, its centrifugal force decreases, the spool 838 is only pressed weakly against the profile sliding bolt 828, and the centrifugal force of the centrifugal mass 824, which remains constant relative to this, now dominates. Therefore, the pivoting bolt pivots, as also from... Figure 8 As I learned from it.

[0047] This mechanism is generally known. Thus, the cutting line 44 can automatically re-extend in the event of wear. However, the feature here according to the invention is the arrangement of the center of gravity 886 of the oscillating arm 820 relative to the axis of rotation 822 and relative to the axis of rotation 60. That is, the center of gravity 886 of the oscillating arm 820 in its locked position (as in...) Figure 7As shown below, so that the cutting line 44 is not further extended or reguided, the axis of rotation 60 of the cutting head 42 is radially spaced from the axis of rotation 822 of the oscillating arm at approximately the same distance. This is illustrated by a circle 900 surrounding the axis of rotation 60, the radius of which corresponds precisely to the radial distance between the axis of rotation 822 of the oscillating arm and the axis of rotation 60. On this circle 900, the center of gravity 886 of the oscillating arm 820 in this configuration or position of the oscillating arm is also arranged at approximately the same distance as the axis of rotation 822 of the oscillating arm.

[0048] Once the cutting head 42 is in Figure 8 As shown in the diagram, when the brakes are applied, or the motor is stopped, or the lawn mower 10 is turned off, the cutting head 42 decelerates and thus experiences acceleration in the direction of arrow 902 (see [reference]). Figure 8 (Above). This results in a reaction force acting on the swing arm 820, which causes the swing arm to pivot in the direction of arrow 904 due to the aforementioned arrangement of the center of gravity 886. In the case of the braking cutting head 42, the static friction between the profile sliding bolt 828 and the reguided profile 840 is overcome. Due to the rotation of the swing arm 820 about the axis of rotation 822 of the swing bolt, the center of gravity 886 also moves outward of the circle 900, which further enhances the torque, or rotation in the direction of arrow 904 or 906, and thus reliably transfers the swing arm 820 to the reguided position. Therefore, the pivoting of the swing arm 820 occurs independently of the cutting line length during braking. Therefore, the re-elongation of the cutting line 44 is independent of whether the cutting line already has its ideal cutting length. Figure 8 As shown (in the middle and bottom), the spool 838, or its reguide profile 840, undergoes relative movement relative to the housing 800 in the direction of arrow 908. Through the reguide profile 840 (here along the inner profile 852 and the protrusion 854), the spool 838, or its reguide profile 840, rotates further relative to the profile sliding bolt 828 by at least one increment until the profile sliding bolt 828 is once again positioned... Figure 7 The initial position is shown below. This process is repeated during the stopping or shutdown of the lawn mower 10.

[0049] Therefore, the lawnmower 10 is configured to automatically re-extend the cutting line 44, and also automatically extend the cutting line 44 when the cutting head 42 is stopped or braked and / or the cutting head 42 or the drive unit 46 of the lawnmower 10 is turned off. A method for operating the lawnmower 10, having a cutting head 42 rotating about a rotation axis 60, having a mechanism for automatically re-extending the cutting line 44, is also disclosed, which occurs when the cutting head 42 is stopped or braked and / or the drive unit 46 of the lawnmower 10 is turned off, specifically extending by an increment or length similar to a reinforcing link. An arrangement of the center of gravity 886 of the oscillating arm 820 is also disclosed, such that when the cutting head 42 is braked or stopped, the oscillating arm 820 is switched to a reinforcing position due to the braking torque acting on it (here in the direction of arrow 904, i.e., radially away from the rotation axis 60). This results in the re-extending of the cutting line 44. Therefore, the center of gravity 886 of the swing arm 820 is arranged on or outside a circle 900 about the rotation axis 60 of the cutting head 42, which passes through the swing arm rotation axis 822 of the swing arm 820. Figure 8 The three stages of the swing rod 820 and the reguide profile 840 in the release position, or re-extending position, for re-extending the cutting line 44 are illustrated. Thus, in the top-to-bottom view, the process of relative rotation between the spool 838 and the housing 800 for re-extending the cutting line 44 is shown.

Claims

1. A spool (838) for a cutting head (42), characterized in that, The spool (838) has a wire end fixing recess (860) extending parallel to the axis of rotation (60) of the spool (838), the wire end fixing recess being arranged radially inside the spool winding surface (844), the spool also having a spool pressure device (862) being arranged radially inside the spool winding surface (844), wherein the spool pressure device (862) is arranged axially at the same height as the spool winding surface (844) or below the wire inlet (864), and a cutting line (44) that can be arranged on the spool (838) can be deflected below the spool pressure device (862).

2. The spool (838) according to claim 1, characterized in that, The spool pressure device (862) is configured to deflect at least twice the cutting line (44) that can be arranged on the spool (838).

3. The spool (838) according to claim 1, characterized in that, An inclined surface (876) is provided on the inner side (875) of the wire inlet (864) with respect to the winding surface (844) of the spool.

4. The spool (838) according to claim 1, characterized in that, The spool (838) is the spool (838) for the cutting head (42) of the lawn mower (10).

5. The spool (838) according to claim 1, characterized in that, The wire inlet is a wire inlet (864) that is radially inside to radially outside the winding surface (844) of the spool.

6. The spool (838) according to claim 2, characterized in that, The spool pressure device (862) is configured to allow for a deflection of >90° in a first deflection direction and a deflection of >0° in a second deflection direction (866, 868) of the cutting line (44) arranged on the spool (838).

7. The spool (838) according to claim 6, characterized in that, The spool pressure device (862) is configured to allow for a deflection of >135° in a first deflection direction and a deflection of >30° in a second deflection direction (866, 868) of the cutting line (44) arranged on the spool (838).

8. The spool (838) according to claim 3, characterized in that, The inclined plane (878) is arranged to be flush with the spool pressure device (862).

9. A method for winding a cutting wire (44) of a lawn mower (10) onto a spool (838) according to any one of claims 1 to 8, the method comprising the steps of: inserting the end of the cutting wire into a wire end fixing recess (860), deflecting (866) the cutting wire (44) around a spool pressurer (862), re-deflecting (868) the cutting wire (44) through the wire inlet (864) toward the spool winding surface (844), and winding the cutting wire (44) onto the spool winding surface (844).

10. A cutting head (42) for a lawn mower (10), having at least one spool according to any one of claims 1 to 8, wherein, The cutting head (42) is configured to automatically re-extend the cutting line (44), and the cutting head has a swing arm (820) that is oscillatingly supported about a swing arm rotation axis (822). The characteristic feature is that, in the locked position of the swing arm (820), the center of gravity (886) of the swing arm (820) has a radially approximately equal or greater distance from the rotation axis (60) of the cutting head (42) compared to the rotation axis (822) of the swing arm relative to the rotation axis (60) of the cutting head (42).

11. The cutting head (42) according to claim 10, characterized in that, The center of gravity (886) of the swing arm (820) is arranged on the cutting head (42) for automatically reguiding or re-extending the cutting line (44), thereby switching the swing arm (820) to the reguiding or re-extending position by means of the braking torque acting on the swing arm when the cutting head (42) is braked or stopped.

12. The cutting head (42) according to claim 10 or 11, characterized in that, In the event of braking or stopping, a re-extension function is provided regardless of the rotation direction of the cutting head (42).

13. The cutting head (42) according to claim 10 or 11, wherein, The housing (800) of the cutting head (42) has an eyelet (810) for leading the cutting line (44) out of the cutting head (42), characterized in that the eyelet (810) is U-shaped and open on one side.

14. The cutting head (42) according to claim 13, wherein the cutting head is configured such that the cutting line (44) can be inserted into the U-shaped eyelet (810) axially parallel to the axis of rotation (60) of the cutting head (42).

15. The cutting head (42) according to claim 10, characterized in that, In the locked position of the swing arm (820), the cutting line (44) is not extended again.

16. The cutting head (42) according to claim 14, characterized in that, The line outlet (813) can be closed by the cover (802).

17. The cutting head (42) according to claim 16, characterized in that, The line outlet (813) can be closed by a cover (802) having a positioning extension (812) for closing the U-shaped open eyelet (810).

18. A lawn mower (10) having a spool according to any one of claims 1 to 8 and / or at least a cutting head (42) according to any one of claims 10 to 17.

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