A mowing head with protection for the drive

Abstract

The mowing head comprises a housing, inside which a spool is provided for winding a cutting line. The mowing head also comprises a rotary knob, angularly constrained to the spool to rotate integrally therewith. The rotary knob is accessible from outside the housing and is coaxial with the axis of rotation of the mowing head. The rotary knob comprises a cavity facing the side of the rotary knob opposite the housing. The cavity is surrounded by an annular edge; and the rotary knob is attached to the side of the mowing head where coupling members are provided for coupling to a grass trimmer.

Description

A MOWING HEAD WITH PROTECTION FOR THE DRIVEDESCRIPTIONTECHNICAL FIELD

[0001] The present invention relates to the field of gardening equipment, at both amateur and professional level. More in particular, the invention relates to improvements to the mowing heads, and the components thereof, for grass trimmers or the like, using, as a cutting member, a line, for example made of plastic, for cutting vegetation.BACKGROUND ART

[0002] In the gardening sector, both at professional and amateur level, mowing heads are used to cut vegetation. The heads are applied to the rotary shaft of a grass trimmer that can be actuated by an endothermic or electric motor. The mowing heads have different members to cut vegetation. In many cases, the cutting member is a line made of polymeric material. A stock of cutting line is accumulated on a spool in the form of coils wound around a central body of the spool, preferably between two flanges of the spool. The two opposite ends of the cutting line protrude through suitable holes for the passage of the cutting line provided, for instance, in bushings, arranged on the perimeter wall of a housing inside which the spool is housed.

[0003] In use, the mowing head is rotated at high speed around the rotation axis thereof and the line portions protruding from the housing of the spool are tensioned due to the centrifugal force and act on the vegetation, cutting it.

[0004] In use, vegetation residues can get stuck and coil around the power take-off of the grass trimmer, between the power take off and the mowing head, which are difficult to remove and can hinder the proper operation of the mowing head.SUMMARY

[0005] A mowing head is disclosed herein, comprising a housing, inside which a spool is provided for winding a cutting line. The mowing head also comprises a rotary knob, angularly constrained to the spool to rotate integrally therewith. The rotary knobis accessible from outside the housing, is coaxial with the axis of rotation of the mowing head, and servers as a member for rotating the spool relative to the housing around the axis of the mowing head, in order to wind a stock of cutting line around the spool when the spool is within the housing.

[0006] To reduce the risk that, in use, vegetation residues coil around the drive shaft of the grass trimmer, between the drive shaft and the mowing head, the rotary knob characteristically comprises a cavity facing the side of the rotary knob opposite the housing. The cavity is surrounded by an annular edge; and the rotary knob is attached to the side of the mowing head where coupling members are provided for coupling to a grass trimmer.

[0007] Further advantageous features and embodiments of the mowing head are described below with reference to the accompanying drawings, and are set forth in the appended claims.BRIEF DESCRIPTION OF THE DRAWING

[0008] The invention will be better understood by following the description below and the attached drawing, showing a non-limiting embodiment of the invention. More specifically, in the drawing:Fig. 1 is an exploded view of an embodiment of a mowing head;Fig. 2 is a cut-away view of the exploded view of Fig. 1;Fig. 3 is an axonometric view of the mowing head of Figs. 1 and 2, mounted;Fig. 4 is a cross section of the mowing head of Fig. 3 according to a plane containing the axis of rotation of the mowing head;Fig. 5 is a cross section of a further embodiment of the mowing head;Fig. 6 is a cross section of a third embodiment of the mowing head;Fig. 7 is a cut-away exploded axonometric view of the mowing head of Fig. 6;Figs. 8 and 9 are respectively a cross section according to a plane containing the axis of rotation and a cut-away axonometric view of a fourth embodiment of the mowing head;Figs. 10 and 11 are respectively a cross section according to a plane containing the axis of rotation and a cut-away axonometric view of a fifth embodiment of the mowing head;Figs. 12 and 13 are respectively a cross section according to a plane containing the axis of rotation and a cut-away axonometric view of a sixth embodiment of the mowing head;Figs. 14 and 15 are respectively a cross section according to a plane containing the axis of rotation and a cut-away axonometric view of a seventh embodiment of the mowing head; andFigs. 16 and 17 are respectively a cross section according to a plane containing the axis of rotation and a cut-away axonometric view of a eighth embodiment of the mowing head.DETAILED DESCRIPTION

[0009] Figs. 1 to 4 show a first embodiment of a mowing head according to the present disclosure.

[0010] In this embodiment, the mowing head 1 comprises a housing 3, which in turn comprises a housing portion 3 A and a housing portion 3B. Here below, the housing portion 3 A will be conventionally referred to as "first portion" or "upper portion" of the housing 3, and the housing portion 3B will be conventionally referred to as "second portion" or "lower portion" of the housing 3. When the mowing head 1 is applied to a grass trimmer, the upper portion 3 A of the housing 3 faces the drive shaft of the grass trimmer.

[0011] The two housing portions 3A, 3B can be coupled with each other through mutual coupling and releasing devices. In some embodiments, the mutual coupling and releasing devices comprise elastic tabs and slots for engaging the elastic tabs. In the illustrated embodiment, the elastic tabs, indicated by the reference number 5, are integral with the first housing portion 3 A and enter slots 7 formed in the second housing portion 3B. It should be understood that the coupling between the two housing portions can be realized in any other suitable way, for example by means of screws, bayonet couplings, threaded couplings, or others.

[0012] The first housing portion 3A forms an outer surface 3C of the housing 3, transverse or generally orthogonal to an axis of rotation A-A of the mowing head 1. Similarly, the second housing portion 3B forms an outer surface 3D of the housing 3, transverse or generally orthogonal to the axis of rotation A-A of the mowing head 1.

[0013] The housing 3 also comprises a perimeter wall 3E. In the illustrated embodiment, the perimeter wall 3E is formed by the first housing portion 3A, and portions of the perimeter wall 3E form the tabs 5.

[0014] Holes 3F for the passage of a cutting line are provided in the perimeter wall 3E. Preferably, two holes 3F are provided, that are diametrically opposite, i.e., offset by 180° relative to each other around the axis A-A of rotation of the mowing head 1.

[0015] In advantageous embodiments, the holes are formed by bushings 9 with holes 9F. Whilst the housing portions 3 A, 3B are preferably made of polymeric material, the bushings 9 can be made of metal, or of fiber- or powder-reinforced polymeric material, which increase the wear resistance.

[0016] A spool 11 is insertable in the housing 3 formed by the first housing portion 3A and the second housing portion 3B. The spool 11 can have any shape. The shape illustrated and described in detail below is merely illustrative.

[0017] In the illustrated embodiment, the spool 11 comprises a central body 13 that in turn comprises a cylindrical wall with an outer cylindrical surface 13.1 and an inner surface 13.2. In advantageous embodiments, the outer surface 13.1 is cylindrical with circular cross-section and has a diameter D (see Fig. 4) of 100 mm or less, preferably 90 mm or less.

[0018] The spool 11 also comprises one or preferably two flanges, indicated in the attached drawing by the reference numbers 15 and 17. The flange 15 comprises a substantially flat outer surface 15.1 and a substantially flat inner surface 15.2. Similarly, the flange 17 comprises a substantially flat outer surface 17.1 and a substantially flat inner surface 17.2. Herein, the term “inner” refers to the surface of each flange facing the other flange, that is, the surfaces facing each other. When mounted, the outer surfaces 17.1, 15.1 face toward the housing portions 3 A, 3B and more exactly toward the walls of these housing portions that form the transverse surfaces 3C and 3D.

[0019] An annular space, or winding space, for winding the cutting line is defined between the outer cylindrical surface 13.1 of the central body 13 and the surfaces 15.2 and 17.2, forming in this way a stock of cutting line consisting of coils wound aroundthe central body 13. Here below, the outer cylindrical surface is also referred to as “winding surface”.

[0020] In some embodiments, teeth 19 are provided on the outer surface 15.1 of the flange 15, and teeth 21 are formed on the outer surface 17.1 of the flange 17. The teeth 19 co-act with stops 25 provided on the housing portion 3B, and more specifically on the surface of the housing portion 3B facing the spool 11. The teeth 21 co-act with stops 23 provided on the housing portion 3A, and more specifically on the surface of the housing portion 3 A facing the spool 11 when the spool is mounted in the mowing head 1. By means of a known mechanism, which will be briefly described below, the first set of teeth 19, the second set of teeth 21, and the stops 25, 23 enable the stepwise rotation of the spool 11 within the housing 3 when the mowing head 1 is in use and is rotating, through an alternating translation movement of the spool 11 in the direction of the axis of rotation A-A of the mowing head 1.

[0021] In some embodiments, the spool 11 comprises a shank 27 coaxial to the wall of the central body 13 of the spool 11, forming the outer cylindrical wall 13.1. The shank 27 is preferably hollow inside, so as to leave space for a coupling member for coupling the mowing head 1 to the drive shaft of the grass trimmer (not shown).

[0022] In some embodiments, the shank 27 has a distal end 27.10, with a female thread 27.11, adapted to engage a male thread of a drive shaft, thus forming a mechanical coupling with the grass trimmer. The distal end 27.10 forms a connecting member, i.e., a drive, for the connection to a drive shaft of the grass trimmer.

[0023] In other embodiments, the distal end 27.10 and the female thread 27.11 can be realized as a separate element from the shank 27, attached to the shank 27 in a fixed manner, by gluing or co-molding, or removable manner.

[0024] In other embodiments, the connecting member comprises a threaded pin, with a male thread instead of a female thread, to engage to a female thread provided in the drive shaft of the grass trimmer.

[0025] The connecting members for connecting to the grass trimmer can be also realized in different ways.

[0026] The spool 11 comprises anchoring members, or constraining members, foranchoring a cutting line F. In the embodiments illustrated in the figures, the anchoring members are configured as described below.

[0027] For example, in some embodiments, the cylindrical wall of the central body of spool 11, which forms the outer cylindrical winding surface, 13.1 and the inner surface 13.2, comprises a first through opening 31 and a second through opening 33. The through openings 31, 33 are angularly offset around an axis B-B of the spool 11. When mounted, the axis B-B is coincident or approximately coincident with the axis A-A of the mowing head 1. The angular offset between the two opposite through openings, or pairs of through openings, 31, 33, is advantageously approximately equal to the angular offset of the holes 3F of the perimeter wall 3E and of the holes 9F of the bushings 9. In this way, when a new cutting line shall be loaded in the spool 11, the through openings 31, 33 and the holes 9F of the bushings 9 align. In the illustrated example, both the holes 9F and the through openings, or pair of through openings, 31, 33 are offset by 180°.

[0028] The through openings 31, 33 are connected to each other through an inner space 35 of the spool 11 (see especially Figs. 9 and 12), delimited between the inner surface 13.2 of the cylindrical wall of the central body 13 and the side surface of the shank 27. The inner space 35 is also delimited by a closing wall, which, in this embodiment, consists of an annular wall 37 that can be part of the spool 11, i.e. can be made in a single piece with the cylindrical wall forming the surfaces 13.1 and 13.2. Furthermore, the inner space 35 is closed by a second closing wall, which can consist of a washer, parallel to the annular wall 37 and spaced from it in the direction of the axis A-A. Alternatively, as will be described in more detail below, the inner space 35 is closed, when the spool 11 is mounted in the housing 3, by a second closing annular wall formed by a component 51 of the mowing head 1, described below.

[0029] The inner space 35 defines a transverse passage for the cutting line F that can pass through the spool 11 and be loaded from outside the mowing head 1 in the way described below, without the need to open the housing 3.

[0030] The mowing head 1 also comprises a control member 41 to control an axial movement of the spool 11 within the housing 3. In some embodiments, the control member comprises a knob 43, which can be made in a single piece with the shank 27,or (as illustrated) can consist of a separate component that is connected to the shank 27 of the spool 11, for example by means of a screw or an elastic ring 44 or the like.

[0031] As the knob 43 is arranged on the side of the mowing head 1 that is connected to the drive shaft of the grass trimmer, the knob 43 of the control member 41 is centrally holed, to allow the passage of the drive shaft or of an intermediate mechanical element connecting the mowing head 1 to the drive shaft of the grass trimmer. In the illustrated embodiment, the knob 43 is holed to allow the passage of the distal end 27.10 of the shank 27.

[0032] In some embodiments, the control member 41 protrudes from the mowing head 1 beyond the outer surface 3C of the first housing portion 3A, i.e., the housing portion that, when the mowing head 1 is mounted on the grass trimmer, faces the drive shaft of the grass trimmer (not shown).

[0033] In some embodiments, an elastic member 45 is associated with the control member 41. The elastic member 45 is for example a compression coil spring that, when mounted, surrounds the shank 27 of the spool 11 arranged in the housing 3. The elastic member 45 is compressed between the knob 43 and a stop that is axially fixed with respect to the housing 3. The axially fixed stop can be formed directly as an integral part of one of the housing portions 3A, 3B, and more precisely of that housing portion (in the illustrated example, the housing portion 3 A) from which the knob 43 protrudes.

[0034] In the embodiment of Figs. 1 to 4, as better described below, the mowing head 1 comprises a winding member for manually winding the cutting line around the spool 11. In the illustrated embodiment, the manual winding member comprises a rotary knob 51 that, when mounted, is coaxial with the shank 27 of the spool 11. As further described below, in this embodiment the rotary knob 51 also forms a stop to hold the elastic member 45.

[0035] In general, the rotary knob 51 is positioned on the side of the mowing head 1 from which it is possible to access the connecting members for connecting to the grass trimmer, that is, in the illustrated example, the distal end 27.10 of the shank 27 of the spool 11.

[0036] The rotary knob 51 comprises an outer annular portion 51.1 that, whenmounted, is positioned outside the housing 3 and protrudes from the same side from which the control member 41 protrudes. The outer annular portion 51.1 comprises a plurality of recesses 51.2 that facilitate grip by a user, for the purposes explained below.

[0037] In the illustrated embodiment, the rotary knob 51 comprises a cavity 51.10 surrounded by an annular edge 51.11, on the outer surface of which recesses 51.2 are formed that make it easier to grip and to rotate the rotary knob 51. The cavity 51.10 is provided on the face of the rotary knob 51 opposite the face facing toward the housing 3.

[0038] In advantageous embodiments, the annular edge 51.11, and therefore the cavity 51.10, have an inner diameter DI (see Fig. 4) of 40 mm or more. In this way, the end of the grass trimmer to which the mowing head 1 is attached can protrude inside the cavity 51.10 and can be at least partially surrounded by the annular edge 51.11. The annular edge 51.11 advantageously has a height H (see Fig. 4) of 2 mm or more, preferably of 3 mm or more, more preferably of 5 mm or more, even more preferably comprised between 5 mm and 20 mm, or between 5 mm and 15 mm.

[0039] When the mowing head 1 is applied to the grass trimmer, the cavity 51.10 with the annular edge 51.11 protects the power take-off of the grass trimmer, preventing or reducing the risk of vegetation twisting around the drive shaft of the grass trimmer while using the grass trimmer.

[0040] Moreover, the rotary knob 51 is configured to couple torsionally to the spool 11, so that the rotary knob 51 and the spool 11 rotate integrally with each other relative to the housing 3, around the axis A-A of rotation of the mowing head 1.

[0041] In some embodiments, the rotary knob 51 comprises, for example, a bush 51.3, integral with the outer annular portion 51.1. When mounted, the bush 51.3 extends coaxially around the shank 27 of the spool 11. The shank 27 extends through a hole provided in the bush 51.3. At an opposite end with respect to the outer annular portion 51.1, the bush 51.3 has an annular collar 51.4 protruding radially inward, that is, toward the axis of rotation A-A of the mowing head 1. The annular collar 51.4 defines a closing wall, closing the inner space 35 through which the cutting line F passes.

[0042] The rotary knob 51 is angularly constrained to the spool 11 by means of a mechanical coupling. To this end, one or more projections (two in the illustrated example) are for example provided along the collar 51.4, indicated by the reference number 51.5 (Fig. 2), which co-act with notches or cavities 27.1 (Figs. 1 and 2) formed in the shank 27 of the spool 11. The angular coupling between the rotary knob 51 and the spool 11 can be configured also in other ways, for example by means of a noncircular cross-section of the inner hole of the collar 51.4 and a corresponding crosssection of the shank 27, to achieve a fit coupling between the shank 27 and the rotary knob 51.

[0043] With this mechanical coupling, the rotation of the rotary knob 51 around the axis A-A of the mowing head 1 causes a rotation of the spool 11 within the housing 3.

[0044] In this embodiment, the annular collar 51.4 forms a stop for the elastic member 45, which is therefore held between the annular collar 51.4 and the knob 43. As a result, the rotary knob 51 is axially pushed toward the inside of the housing 3 by the elastic member 45, and the outer annular portion 51.1 is therefore pressed, by the spring force of elastic member 45, against the outer surface of the housing portion (in the example, the first housing portion 3 A), from which the control member 41 and the rotary knob 51 protrude.

[0045] Moreover, the elastic member 45 pushes the spool 11 to a rest position within the housing 3. This thrust is generated by the elastic member 45 that acts against the control member 41, biasing the spool 11 to rest against the inner surface of the first portion 3 A of the housing 3. As it will be explained below, by pushing the control member 41 toward the inside of the housing 3, for example, by resting the outer surface 3D of the lower housing portion 3B and pressing against the knob 43 by means of the grass trimmer, the control member 41 causes a contraction of the elastic member 45 and therefore an axial movement of the spool 11 toward the opposite housing portion 3A. This movement is indicated by the arrow fl 1 in Fig. 4. By releasing the knob 43, the elastic member 45 causes an axial movement of the spool 11 in the opposite direction.

[0046] The use of the mowing head 1 described above is as follows.

[0047] The cutting line (schematically indicated by the dashed line F in Fig. 4 andnot shown in the other figures) can be loaded into the mowing head 1 as follows. The spool 11, housed in the closed mowing head 1, is rotated, through the rotary knob 51, until the openings 31, 33 are aligned with the holes 3F, or more precisely with the corresponding holes 9F provided in the bushings 9. Once this position has been achieved, the user can insert a first end of a piece of cutting line F through the mowing head 1 by passing it through the hole 9F of one of the bushings 9, through the opening 31 or 33, through the inner space 35, through the opposite opening 33 or 31, and finally through the hole 9F of the bushing 9 opposite to the entrance bushing. The piece of cutting line F can be inserted through the mowing head 1 until two portions thereof of approximately equal length protrude from the two bushings 9.

[0048] At this point, by means of the rotary knob 51, the user can wind the cutting line F around the spool 11 by turning the rotary knob 51, and consequently the spool 11, within the housing 3 of the mowing head 1. While winding around the central body 13 of the spool 11, the cutting line F forms a series of stock coils (some of them shown in dashed line in Fig. 4) around the winding surface 13.1 of the spool central body 13, without the need to open the mowing head 1, which can remain for example attached to the grass trimmer (not shown).

[0049] The winding of the stock of cutting line ends by leaving two pieces of cutting line protruding from the two bushings 9, so that, by rotating the mowing head 1 around the axis of rotation A- A, the portions of cutting line F protruding from the two bushings are lengthened and form members for cutting vegetation.

[0050] In use, the cutting line F protruding from the bushings 9 of the mowing head 1 gets worn out and may break. To have again a suitable length of cutting line protruding from both the bushings 9, while the mowing head 1 is kept rotating around the axis A-A of rotation through the drive shaft of the grass trimmer (not shown), the user presses, once or repeatedly, the knob 43 by means of the distal end of the grass trimmer, whilst the mowing head 1 is kept with the lower surface 3D resting against the ground. This causes repeated contraction and release of the elastic member 45 and therefore an axial movement of the knob 43 toward the inside of the housing. This repeated movement alternately causes the teeth 21 to be released from the stops 23 and the teeth 19 to be engage the stops 25. As the teeth and / or stops are angularly offset, the axial movement of the spool 11 within the housing 3 causes the stepwise rotationthereof, under the thrust of the centrifugal force acting on the portions of cutting line protruding from the bushings 9, consequently stressing the spool 11 to rotate about its axis B-B relative to the housing 3 in the direction of unwinding of the cutting line F.

[0051] Every time the mowing head is pressed against the ground and subsequently released, the spool 11 angularly rotates by one step and consequently unwinds a portion of cutting line F that is pulled outside both bushings 9 under the effect of the centrifugal force.

[0052] The operation is repeated one or more times until to have again the desired length of cutting line portions protruding from the mowing head 1.

[0053] Fig. 5 show a second embodiment of the mowing head 1 according to the invention. This embodiment differs from the first one in that the knob 43 is omitted and the rotary knob 51, in addition to serving as a winding member for manually winding the stock of cutting line around the spool 11, also serves as a control member for controlling the lengthening of the cutting line F.

[0054] To this end, the rotary knob 51 is constrained not only angularly but also axially to the shank 27 of spool 11. In this way, the rotation of the rotary knob 51 relative to the housing 3 around the axis A-A of the mowing head 1 controls a rotation of the spool 11 within the housing 3. Moreover, by pressing the rotary knob 51 according to the arrow fl 1, the rotary knob 51 and the and spool 11 translate against the elastic force of the elastic member 45. In this case, the elastic member 45 is held between the rotary knob 51 and a collar 3X, radially protruding toward the axis A-A of rotation, by a bush 3Y integral with the first housing portion 3A, i.e., forming part of the housing.

[0055] In this way, the elastic member 45 practically pushes the rotary knob 51 outward by pulling the spool 11 against the inner surface of the first housing portion 3 A. The thrust of the elastic member 45 is transmitted to the spool 11 through the shank 27, as in the previous embodiment.

[0056] In this case, the rotary knob 51 also comprises a cavity 51.10 surrounded by an annular edge 51.11, on the outer surface of which recesses 51.2 are formed that make it easier to grip and to rotate the rotary knob 51. The cavity 51.10 is provided onthe face of the rotary knob 51 opposite the face facing toward the housing 3.

[0057] In the embodiment of Fig. 5, the shank 27 of the spool 11 comprises an insert that forms the distal end 27.10 of the shank. The insert can be made of metal, or a resin of greater strength than the polymer forming the housing 3. In this embodiment, the insert forming the distal end 27.10 of the shank 27 has, as shown in Figs. 1 to 4, a threaded hole 27.11, with which an externally threaded shaft of the grass trimmer engages. In other embodiments, the insert forming the distal end 27.10 of the shank 27 has an externally threaded pin, so as to engage a drive of the grass trimmer that, instead of a male threaded pin, has a female threaded hole.

[0058] In advantageous embodiments, the rotary knob 51 has, inside the annular edge 51.11, an annular slot 51.15 opposite the opening of the cavity 51.10, shown in Figs. 4 and 5. The annular slot 51.15 engages an annular proj ection 3L that protrudes parallel to the axis A-A from the outer surface 3C of the first housing portion 3 A. This provides stabilization and guidance for the rotary knob 51 on the housing 3. This arrangement can be also reversed, with a projection provided on the rotary knob 51, engaging an annular slot provided on the outer surface 3C of housing portion 3B, from which the rotary knob 51 protrudes.

[0059] A further embodiment of the mowing head 1 is shown in Figs. 6 and 7, where equal numbers indicate equal or equivalent parts to those illustrated with reference to Figs. 1 to 5, that will not be described again.

[0060] The embodiment of Figs. 6 and 7 is similar to that of Fig. 5 in that it does not have a control member 41 to control the lengthening of the cutting line, and the rotary knob 51 serves both as a member for lengthening the cutting line F and as a member for manually rotating the spool in order to wind the cutting line in the spool 11.

[0061] Differently from the embodiment of Fig. 5, in the embodiment of Figs. 6 and 7 the elastic member 45 is provided not around the shank 27 of the spool 11, but between the spool 11 and the housing portion 3B, and has the same function of stressing the spool 11 toward a rest position.

[0062] Figs. 8 and 9 show a further embodiment of the mowing head 1. The same numbers indicate parts identical or equivalent to those of the previous embodiments.The embodiment of Figs. 8 and 9 is similar to that of Figs. 1 to 4, where, however, the rotary knob 51 has an annular portion, which protrudes radially beyond the annular edge 51.11 toward the periphery of the mowing head 1, and on which the recesses 51.2 are formed, which are, therefore, on a larger radius than the outer radius of the annular edge 51.11.

[0063] Figs. 10 and 11 show an embodiment similar to that of Fig. 5, where, however, the rotary knob 51 extends radially until to cover the entire portion 3 A of the housing 3. The recesses 51.2 are provided on a larger diameter than in Fig. 5, and the cavity 51.10 is formed within an annular edge 51.11 that protrudes from the rotary knob 51, similarly to what illustrated for Figs. 1 to 4.

[0064] Figs. 12 and 13 show a variant of embodiment of the mowing head 1, where the rotary knob 51 extends radially until to cover the entire portion 3 A of the housing 3, similarly to what illustrated in Figs. 10 and 11, but the cavity 51.10 is formed as a recess within an edge facing the inside of the mowing head, as shown in Figs. 5 and 6, instead of being formed within an edge protruding from the rotary knob 51 (as in Figs. 10 and 11).

[0065] Figs. 14, 15 and Figs. 16, 17 show two embodiments, where the cavity 51.10 and the annular edge 51.11 are configured similarly to what illustrated in Figs. 10 and 11 and Figs. 12 and 13, respectively. However, the embodiments of Figs. 14,15 and 16, 17 differ from the previous ones in that a knob 43 is provided, shaped and functioning as already described with reference to Figs. 1 to 4, the knob being not provided in Figs. 10, 11 and 12, 13.

[0066] In the various illustrated embodiments, the annular edge 51.11 surrounding the cavity 51.10 protects the drive shaft (not shown) of the grass trimmer, to which the mowing head is attached, preventing or reducing the risk that the vegetation, on which the mowing head 1 acts, twists around the drive shaft.

Claims

CLAIMS1. A mowing head (1) comprising: a housing (3); a spool (11) for winding the cutting line (F), insertable into the housing (3) coaxially with the axis of rotation (A- A) of the mowing head (1); a rotary knob (51), angularly constrained to the spool (11) so as to rotate integrally therewith; wherein the rotary knob (51) is accessible from outside the housing (3) and is coaxial with the axis of rotation (A-A) of the mowing head (1); characterized in that the rotary knob (51) comprises a cavity (51.10) facing the side of the rotary knob (51) opposite the housing (3); the cavity (51.10) is surrounded by an annular edge (51.11); and the rotary knob is attached to the side of the mowing head (1) where coupling members (27.10, 27.11) are provided for coupling to a grass trimmer.

2. The mowing head (1) of claim 1, wherein the cavity (51.10) has an inner diameter of at least 40 mm; and wherein preferably the annular edge (51.11) has a height (H) of 2 mm or more, preferably of 3 mm or more, more preferably of 5 mm or more, even more preferably comprised between 5 mm and 20 mm, or between 5 mm and 15 mm.

3. The mowing head of claim 1 or 2, wherein the housing (3) comprises a first housing portion (3 A) and a second housing portion (3B) that can be coupled to, and released from, each other; wherein one of the first housing portion (3 A) and second housing portion (3B) comprises a perimeter wall (3E) extending around an axis of rotation (A-A) of the mowing head (1), the perimeter wall (3E) comprising at least two holes (3F), angularly offset around the axis of rotation (A-A) of the mowing head (1), for the passage of a cutting line (F); and wherein the mowing head (1) further comprises an elastic member (45) associated with the spool (11) and adapted to stress the spool (11) to an axial rest position within the housing (3); wherein the spool (11) is axially movable within the housing (3) compressing the elastic member (45).

4. The mowing head (1) of claim 3, wherein the rotary knob (51) is axially constrained to the spool (11), so that an axial movement of the knob (51) causes an axial movement of the spool (11) within the housing (3); the axial movement of therotary knob (51) toward the housing (3) causing the elastic member (45) to contract.

5. The mowing head (1) of claim 3, comprising a control member (41) axially constrained to the spool (11); wherein the control member (41) protrudes axially from the housing (3); and wherein the axial movement of the control member (41) relative to the housing (3) causes an axial displacement of the spool (11) within the housing (3) against the stress of the elastic member (45).

6. The mowing head (1) of claim 5, wherein the elastic member (45) is held between an annular collar (51.4) of the rotary knob (51) and the control member (41), the control member (41) being coaxial with the rotary knob (51).

7. The mowing head (1) of one or more of claims 3 a 6, comprising a mechanism with teeth (19, 21) and stops (23, 25) configured to control a stepwise rotation of the spool (11) within the housing (3) under the action of the centrifugal force generated when the head (1) is rotating, when the spool (11) displaces axially within the housing (3).

8. The mowing head (11) of any one of claims 3 a 6, comprising a first set of teeth (19) integral with a first face of the spool (11) and co-acting with a first set of stops (23) integral with the first housing portion (3 A); and a second set of teeth (21) integral with a second face of the spool (11) and co-acting with a second set of stops (25) integral with the second housing portion (3B); wherein the teeth (19, 21) and the stops (23, 25) are angularly offset around the axis of rotation (A-A) of the mowing head (1), in such a way that the axial movement of the spool (11) within the housing (3) when the head (1) is rotating causes, due to the effect of the centrifugal force, a stepwise angular movement to deliver cutting line from the spool (11) through the holes (3F) in the perimeter wall (3E).

9. The mowing head (1) of any one of the preceding claims, wherein the rotary knob (51) comprises a bush (51.3), within which the elastic member (45) is at least partially housed; and wherein preferably the spool (11) comprises a shank (27) coaxial to the spool (11), and wherein the shank (27) extends coaxially in the bush (51.3) of the rotary knob (51).

10. The mowing head (1) of any one of claims 1 to 8, wherein the spool(11) comprises a shank (27) coaxial with the spool (11), and wherein the shank (27) comprises a coupling member for mechanically coupling the mowing head (1) to a drive shaft of a grass trimmer, the shank (27) extending through the rotary knob (51).

11. The mowing head (1) of any one of the preceding claims, wherein the rotary knob (51) comprises an annular slot (51.15) on a face facing the housing (3), and the housing (3) comprises an annular projection (3L) engaged in the annular slot (51.15), or vice versa; wherein the annular slot (51.15) preferably extends along the annular edge (51.10) of the rotary knob (51).

Images