Spool for a string trimmer head and string trimmer head with a spool

Abstract

A spool for a line trimmer head is described, comprising a storage section (10) configured to receive multiple windings of a trimmer line (3) of the line trimmer head, a bearing section (15) configured to rotatably mount the spool about an axis of rotation (80) of the spool on the line trimmer head, an underside (20) which, when the spool is installed in the line trimmer head, faces a removable cover part (52) of the line trimmer head, and at least one operating element (30) configured to be actuated by an operator to apply a moment (M) to the spool in a winding direction (81) about the axis of rotation (80), wherein the operating element (30) is arranged on the underside (20) of the spool so that it is accessible to the operator when the cover part (52) of the line trimmer head is removed. A line trimmer head with a housing (50) that can be opened without tools and the spool arranged therein is also described.

Description

The invention relates to a spool for a string trimmer head and a string trimmer head with a spool. Line trimmer heads with spools are known in the prior art. Several windings of trimmer line are stored on the spool, allowing a worn trimmer line to be readjusted by a relative movement of the spool and the trimmer head housing. Various readjustment mechanisms are known to those skilled in the art. When the supply of line stored in the reservoir is exhausted, the operator must refill it. To do this, the operator can open the trimmer head, remove the spool from the housing, and either rewind the same spool with line or use a pre-filled replacement spool and insert it into the housing. It has been found that inserting a line-wound spool into the housing is difficult for inexperienced operators, as the tightly wound line in the reservoir tends to spring back, requiring the operator to hold the line in place during insertion.Therefore, trimmer heads with line feeders that allow line to be refilled without opening the head are now common. This is achieved by inserting the line into a channel in the spool from the outside and then rotating the spool relative to the housing. However, this requires the use of mechanisms such as grip discs to transfer the operator's rotational movement from outside the housing to the spool located inside. This makes the trimmer head's design complex and relatively expensive. From patent application US 2011 / 0239468A1, a line trimmer head is known with a spool having a storage section bounded by a lower flange and two upper flange segments. An open channel is formed between the upper flange segments. Ramp-shaped stop elements of an advance mechanism are also arranged on the upper flange segments. The upper flange segments are accessible to the operator after the line trimmer head is opened. The patent application DE 10 2019 130 101 A1 discloses a modular mowing and / or trimming device, wherein the modules each comprise a housing unit and a thread spool arranged therein. The objective is to provide a trimmer head that is at least partially improved with regard to the aforementioned disadvantages. This objective is achieved by the spool for the trimmer head specified in claim 1 and claim 5, as well as by the trimmer head specified in claim 7. The present invention is based on the insight that, to refill the spool, it is not necessary to completely remove the spool from the housing of the trimmer head, provided that the spool, while still partially inside the housing, can be ergonomically rotated by the operator relative to the housing. This eliminates the tedious task of threading a full spool into the housing. Instead, line is inserted from the outside through the housing into the empty spool, which is still inserted in the housing, and wound into the supply section. For this purpose, the spool has a bearing section by which it is rotatably mounted on the trimmer head about an axis of rotation. Using at least one control element, the operator can apply a torque to the spool in a winding direction about the spool's axis of rotation, thereby filling the supply section with line. Since the spool is removed after opening the trimmer head, i.e.,By removing the cover, the underside of the spool is accessible to the operator, allowing the spool to be ergonomically rotated relative to the housing using at least one control element located on the underside. This eliminates the need for grip discs or similar devices that protrude from the housing when closed. This results in a simpler and more cost-effective trimmer head. During operation of the trimmer head on a drive shaft, the spool is arranged in a housing of the trimmer head and is thus largely protected from contamination. Because the trimmer head housing comprises a first housing part and a cover part, which can be connected and disconnected without tools, the spool is quickly and easily accessible to the operator. The cover part can be quickly and easily removed to access the underside of the spool with the at least one operating element. In particular, the first housing part and the cover part are connected by a snap-fit ​​connection. In one embodiment, the trimmer head includes a switching device for adjusting the trimmer line from the supply section. Such switching devices for adjusting trimmer line are known to those skilled in the art. In one embodiment, the control element is securely attached to the spool. The control element cannot detach from the spool unintentionally. In particular, the control element cannot detach from the spool during operation of the trimmer head. The control element can be formed as a single unit with the spool, for example, using an injection molding process. Alternatively, the control element can be joined to the spool at a connection point. This connection point can form a bearing point where the control element is held so that it can move within limits relative to the spool, in particular rotatably and / or slidably. The movable control element has, in particular, an operating position and a different actuation position. During operation of the trimmer head, the control element is in the operating position. When the trimmer head housing is open, the trimmer head is in a standby position.With the cover removed, the operator can move the control element from the operating position to the actuation position. The operating position and the actuation position of the control element differ primarily in how easily accessible one or more of its operating surfaces are to the operator's fingers and / or how far the operating surface is from the axis of rotation in the radial direction. The greater the distance, the greater the torque the operator can apply to the coil with the same actuation force. In the actuation position, the operator can apply a higher torque to the coil than in the operating position. However, in the actuation position, the control element is also positioned further away from the coil than in the operating position.After the thread is wound onto the bobbin, the operating element must be moved from the actuating position to the operating position, particularly by the operator. The cover can only be connected to the first housing part when the operating element is in the operating position. It may be provided that placing the cover onto the first housing part causes the operating element to move from the actuating position to the operating position. Alternatively, a spring element may be provided that biases the operating element towards the operating position. In particular, locking devices are provided on the bobbin to secure the operating element in the operating position. In one embodiment, a chamber is formed on the underside of the coil, and the at least one control element is at least partially enclosed in the chamber. This can be advantageous both with a control element attached to the coil at a connection point, particularly a movable one, and with a control element formed as a single material with the coil. With a movable control element, the control element protrudes more from the chamber in the actuated position than in the operating position. The chamber lies radially between the bearing section and the storage section of the coil with respect to the axis of rotation. It can also be provided that the bearing section does not extend axially into the chamber with respect to the axis of rotation.By arranging the control element at least partially, and even completely, within the chamber, the available axial height of the chamber is utilized to accommodate the control element on the spool in a space-saving manner. The housing of the trimmer head therefore does not need to be enlarged, or only minimally enlarged, in the axial direction to provide a control element on the underside of the spool. In particular, it is designed so that a large portion of the control element's operating surface is located within the chamber. With a movable control element, a large portion of the operating surface is located within the chamber during operation. However, when the control element is activated, a large portion of the operating surface protrudes from the chamber. A movable control element allows for both a compact design and excellent accessibility of the operating surface. In one embodiment according to the invention, the control element is pivotably mounted on the coil about a pivot axis. The pivot axis is, in particular, orthogonal to the axis of rotation. The control element is, in particular, U-shaped and, in its operating position, extends over at least 120°, in particular at least 180°, and most especially 360° around the axis of rotation. In one embodiment, the spool has an annular flange on its underside, which limits the supply section of the spool in the axial direction with respect to the axis of rotation. When the spool is inserted in the housing, an annular gap is formed between the outer circumference of the flange and a circumferential wall of the housing. The gap has a width of less than 1.5 cm, and particularly less than 1.0 cm, along the circumference, especially at several points. This limits or prevents the thread wound on the spool from springing back when the spool is inserted in the housing. However, the narrow gap makes it difficult, if not impossible, for the operator to grasp the spool at the circumferential edge of the flange. In an embodiment according to the invention, the flange is provided with at least one opening or recess designed such that an operator's finger can engage it to rotate and / or remove the spool.The recess extends particularly from the outer circumference of the flange. This allows the operator's finger to be positioned partially within the recess and partially within the annular gap, ensuring that the operating surface of the control element formed by the recess is located as far away from the axis of rotation as possible. This enables the operator to apply a comparatively high torque. Specifically, at least two openings and / or recesses are designed as control elements on the flange, allowing the operator to engage different fingers simultaneously to apply an even greater torque to the coil in the winding direction. The control elements are distributed at uniform angular intervals around the axis of rotation. This prevents imbalance in the coil. The opening or recess is designed to have a collar to increase the contact area with the operator's finger.In this way, operating the control element, which is designed as an opening or recess, is even more convenient for the operator. Further features of the invention will become apparent from the description and the drawing, in which a detailed embodiment of the invention is shown below. The figures show: Fig. 1 a side view of a string trimmer head, Fig. 2 an isometric view and a top view along the axis of rotation of the open string trimmer head from Fig. 1, with a spool according to a first embodiment, which has a movable control element shown in an actuating position, Fig. 3 the string trimmer head from Fig. 2, wherein the control element is shown in an operating position, Fig. 4 an isometric view and a top view along the axis of rotation of the open string trimmer head from Fig. 1, with a spool according to a second embodiment, which has a movable control element shown in an actuating position, Fig. 5 the string trimmer head from Fig. 4, wherein the control element is shown in an operating position.6 an isometric view and a top view along the axis of rotation of the open line trimmer head from Fig. 1, with a spool according to a third embodiment, which has operating elements formed in a chamber of the spool in a single material with the spool, Fig. 7 an isometric view and a top view along the axis of rotation of the open line trimmer head analogous to Fig. 1, with a spool according to a fourth embodiment, which has operating elements formed in a single material with the spool on a flange of the spool. Fig. 1 shows a string trimmer head for cutting grass, brush, and the like. The string trimmer head has a housing 50 in which a spool with a cutting line 3 wound on it is arranged. A free end of the cutting line 3 protrudes from a line opening 58 in the housing 50 to cut grass. In normal operation of the string trimmer head, the housing 50 and the spool do not move relative to each other. To unwind new cutting line 3 from the spool when the cutting line 3 is worn out, the string trimmer head has a switching device (not shown) that temporarily allows relative movement between the housing 50 and the spool about a rotational axis 80 in an unwinding direction, thus enabling cutting line 3 to unwind from the spool. The housing 50 comprises a first housing part 51 and a cover part 52, which are connected to each other without tools via a snap-fit ​​connection 54. When the trimmer line 3 is used up, the cover part 52 can be easily removed, so that the underside 20 of the spool still located in the housing part 51 is accessible to the operator. The switching device is inactive when the cover part 52 is open. The underside 20 of the spool extends orthogonally to the axis of rotation 80. The top views in Figs. 2, 3, 4, 5, 6 to 7 show a frontal view of the underside 20 of the spool. Figures 2, 3, 4, 5, 6 to 7 depict the trimmer head in the open position, i.e., with the cover part 52 removed. The underside 20 of the spool is freely accessible to the operator. Figures 2, 4, 6, and 7 show different embodiments of the spool, which differ essentially only in the type and / or design of the operating element 30 and will be described in detail later. A trimmer line 3 inserted through the line opening 58 of the housing 50 is fixed to the spool in a manner known to those skilled in the art. A line channel running through the spool may be provided for this purpose. Other retaining means known to those skilled in the art may also be provided on the spool.The operator then rotates the spool relative to the housing 50 around the axis of rotation 80 in a winding direction 81 using at least one control element 30, thus drawing the trimmer line 3 through the line openings 58 into the housing 50 and winding it onto the spool. The winding direction 81 is opposite to the unwinding direction. The spool has a storage section 10 to hold several turns of the trimmer line 3. The storage section 10 is bounded on the underside 20 of the spool by a lower flange 22. The spool may also have an opposing upper flange and a middle flange located between the upper and lower flanges, in which the line channel is formed. Radially with respect to the axis of rotation 80 within the storage section 10, the spool has a bearing section 15. The bearing section 15 allows the spool to rotate about the axis of rotation 80. In the embodiments shown in Figures 2, 3, 4 to 5, the coil has a control element 30 that is movably mounted on the coil. The control element 30 has an actuation position and an operating position. The control element 30 is designed as a bracket that pivots about a pivot axis 85. The control element 30 is securely connected to the coil by a pivot joint. Figures 2 and 4 show the control element 30 in the actuation position. Figures 3 and 5 show the control element 30 in the operating position. As can be seen in Figures 2, 3, 4 to 5, the control element 30, designed as a bracket, protrudes less from the coil in the operating position than in the actuation position. In the exemplary embodiments, the coil has a chamber 25 on its underside 20 in which the control element 30 is at least partially received.In this way, the radially available free space within the storage section 10 can serve to at least partially accommodate the control element 30. In the actuated position of the control element 30, an operating surface of the control element 30 protrudes from the chamber 25, i.e., the control element 30 is unfolded. In the operating position of the control element 30, an operating surface of the control element 30 protrudes only slightly or not at all from the chamber 25, i.e., the control element 30 is folded in. The cover part 52 cannot be connected to the first housing part 51 when the control element 30 is unfolded. The snap connection 54 between the cover part 52 and the first housing part 51 cannot engage as long as the control element 30 is in the actuated position. The control element 30 may be pre-tensioned to its operating position.To make the control element 30 easy to grip and avoid having to be unfolded from its operating position every time the user changes their grip, a detent position can be provided in which the control element 30 remains after being moved past a detent point by the operator. In the embodiment according to Fig. 2, it can be provided that placing the cover part 52 moves the control element 30 out of its detent position, and the control element 30 then automatically assumes the operating position due to the preload. In this way, it is ensured that the control element 30 is always automatically in the operating position when the housing 50 of the line trimmer head is closed. The embodiment according to Fig. 4 differs from the embodiment according to Fig. 2 in that the control element 30, which is designed as a bracket, is larger. As can be seen in Figs. 3 and 5, in the operating state, the control element 30 according to Fig. 2 extends approximately 180° with respect to theThe rotation axis 80 and the control element 30 according to Fig. 4 rotate completely, i.e., by 360°, around the rotation axis 80. In the embodiment according to Fig. 2, the pivot axis 85 is located on the bottom, particularly in the center, of the chamber 25, and in the embodiment according to Fig. 4, on an edge of the chamber 25. The pivot axis 85 runs orthogonally to the rotation axis 80. Due to the arrangement and orientation of the pivot axis 85, the control element 30 does not protrude from the chamber 25, or only minimally, in the folded-in state in both embodiments. If the control element 30 in its operating position would cause an imbalance of the spool during operation of the line trimmer head, it is advantageous to arrange a counterweight on the spool, particularly in the chamber 25. In the embodiment according to Fig. 2, a counterweight is arranged in the chamber 25 opposite the control element 30. In the embodiment according to Fig. 4, the mass of the control element 30 is largely balanced around the axis of rotation 80 in its operating position. The control element 30 and / or the coil may be provided with positioning elements to hold the control element 30 in its position in the operating position and, in particular, to absorb lateral forces. This reduces the forces on the bearing point of the control element 30, allowing the pivot joint to be smaller. In the exemplary embodiment, the positioning elements are designed as guide rails. Other designs that would appear advantageous to those skilled in the art are also conceivable. To exert a moment M in the winding direction 81 on the spool according to the embodiment shown in Fig. 2, the operator grasps the control element 30 in the embodiment shown in Fig. 2 with two fingers on opposing operating surfaces of the control element 30. The further the fingers are from the axis of rotation 80, the greater the moment M achievable with an operating force BK. To exert a moment M in the winding direction 81 on the spool according to the embodiment of Fig. 4, it is sufficient for the operator to insert a finger, schematically represented by a dotted line, into a central opening of the control element 30 and exert an operating force BK in the winding direction 81. Because the operating surface is located further away from the axis of rotation 81 than in the embodiment of Fig. 2, a sufficiently large moment M for winding the trimmer line 3 can be easily applied by the operator with just one finger. The control element 30 according to Fig. 4 can also be gripped by the operator in other ways. Furthermore, it can be provided that the actuating position of the control element 30 according to Fig. 4 is reached after a pivoting movement of the control element 30 of less than 180°, in particular approximately 90°, from the operating position about the pivot axis 85. In the embodiments shown in Figures 6 and 7, the control element 30 is formed as a projection or recess, integrated with the coil as a single piece of material. The control element 30 is fixed. This allows for a particularly cost-effective coil. In particular, at least two control elements 30 are formed on the coil, which are arranged, in particular, at a uniform angular interval around the axis of rotation 80 and at a distance from the axis of rotation 80. In particular, a maximum of four control elements 30 are provided, and most especially exactly two. Because a maximum of four control elements 30 are provided, the angular distance available between adjacent control elements 30 is sufficiently large to allow an operator to easily reach between them, even while wearing gloves. In an embodiment according to Figure 6, more than four control elements 30 can also be provided due to the larger diameter on which the control elements 30 are arranged.When two control elements 30 are positioned opposite each other with respect to the axis of rotation 80, a moment M about the axis of rotation 80 can easily be applied using the thumb and another finger of the same hand. The coil has, in particular, a chamber 25 on its underside 20, analogous to the previous embodiments. The control element 30 has a control surface against which the operator's finger rests. In the embodiment according to Fig. 6, the control surface extends transversely to a circumferential wall of the chamber 25. The control surface is essentially perpendicular to the bottom of the chamber 25 and projects beyond the lower flange 22. A large part of the control surface lies within the chamber 25. In this way, the cavity can be used radially within the storage section 10, so that only a small part of the control surface projects beyond the lower flange 22. The overall height of the coil is only slightly increased by the control elements 30.With an even greater distance between the bottom of chamber 25 and the lower flange 22, an arrangement is also conceivable in which the control element 30 does not project beyond the lower flange 22, i.e., the height of the spool is not extended by the control element 30. The height of the spool is measured in the axial direction with respect to the axis of rotation 80. In the embodiment according to Fig. 7, the control element 30 is designed as a recess in the lower flange 22. The recess extends radially inwards from an outer diameter of the flange 22, in particular by at least 1.0 cm, in particular by at least 1.5 cm, in particular to a base of the storage section 10. The first winding of the trimmer line 3 rests on the base of the storage section 10. Because the control element 30 is arranged outside the chamber 25, the operating area is not limited by a base of the chamber 25. Rather, the operator's finger projects into the storage section 10.The recess enlarges the gap between the first housing part 51 and the lower flange 22 in the area of ​​the recess. This allows the operator's finger to engage between the spool and the housing 50. This enables the operator to grip the spool at the largest possible diameter. As a result, a small operating force BK is sufficient to apply a moment M in the winding direction 81 to the spool. In the exemplary embodiment, a collar is arranged on the recess to enlarge the operating surface. The recess can also serve as a viewing window to observe the changing fill level of the spool during winding. As can be seen in Fig. 7, the spool can also have at least one operating element 30, even though the line trimmer head has a handle for rotating the spool from the outside. The operating element 30 provides an additional means of winding trimmer line 3 onto the spool. The operating element 30 can further facilitate the removal of the spool from the first housing part 51. This applies in particular to an operating element 30 according to the embodiments shown in Figures 1 to 5 and 7. There, the operating element 30 provides an undercut in the axial direction, on which the operator can grasp the spool and remove it from the first housing part 51 in the direction of the axis of rotation 80.

Claims

A spool for a line trimmer head comprising: a storage section (10) configured to receive several windings of a trimmer line (3) of the line trimmer head; a bearing section (15) configured to mount the spool rotatably about an axis of rotation (80) of the spool on the line trimmer head; a bottom surface (20) which, when the spool is arranged in the line trimmer head, faces a removable cover part (52) of the line trimmer head; at least one operating element (30) configured to be actuated by an operator to apply a moment (M) to the spool in a winding direction (81) about the axis of rotation (80), wherein the operating element (30) is arranged on the bottom surface (20) of the spool so that it is accessible to the operator when the cover part (52) of the line trimmer head is removed; characterized in that the operating element (30) is pivotably mounted on the spool about a pivot axis (85). Coil according to claim 1, characterized in that the control element (30) is arranged on the coil in a way that prevents it from being lost. Coil according to one of the preceding claims, characterized in that the coil has a chamber (25) on its underside (20) and the control element (30) is at least partially received in the chamber (25). Coil according to one of the preceding claims, characterized in that the control element (30) is movable relative to the coil and has an operating position and an actuation position different therefrom. A spool for a line trimmer head comprising: a storage section (10) configured to receive several windings of a trimmer line (3) of the line trimmer head; a bearing section (15) configured to rotatably mount the spool about an axis of rotation (80) of the spool on the line trimmer head; an underside (20) which, when the spool is arranged in the line trimmer head, faces a removable cover part (52) of the line trimmer head; at least one operating element (30) configured to be actuated by an operator to apply a moment (M) to the spool in a winding direction (81) about the axis of rotation (80), wherein the operating element (30) is arranged on the underside (20) of the spool so that it is accessible to the operator when the cover part (52) of the line trimmer head is removed; characterized in thatthat the coil has a flange (22) on its underside (20) to delimit the supply section (10) and the operating element (30) is designed as an opening or recess in the flange, the opening or recess having a collar. Coil according to claim 5, characterized in that the recess extends from an outer circumference of the flange (22). Thread trimmer head comprising a housing (50) and a spool arranged therein according to one of the preceding claims, wherein the housing (50) comprises a first housing part (51) and a cover part (52) which can be connected and separated without tools. Thread trimmer head according to claim 7, comprising a switching device for adjusting the trimmer line (3) from the supply section (10).

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