Spool, trimmer head and method for mounting a trimmer head

Abstract

A spool (1) for a line trimmer head (100) is described, comprising a storage section (10) configured to hold several windings of a trimmer line (3) of the line trimmer head (100), a bearing section (15) configured to rotatably mount the spool (1) about a rotation axis (80) of the spool (1) on the line trimmer head (100), the spool (1) further comprising a tool section (20) configured to actuate a screw connection element (60) for mounting the line trimmer head (100). A line trimmer head (100) with a housing (50) that can be opened without tools and the spool (1) arranged therein, as well as a method for mounting the line trimmer head (100) to a drive shaft (200) for driving the line trimmer head (100), are also described.

Description

[0001] The invention relates to a spool for a string trimmer head, a string trimmer head with a spool and a method for mounting a string trimmer head to a drive shaft.

[0002] Line trimmer heads with spools are known in the 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 housing of the line trimmer head. Various readjustment mechanisms are known to those skilled in the art. A screw connection is frequently used to attach the line trimmer head to the drive shaft. Designs are known in which the screw connection is integrated into a housing part. To attach the line trimmer head to the drive shaft, the housing part must be rotated relative to the drive shaft. While the housing has a relatively large circumference, eliminating the need for an additional tool for loosening, the manufacturing costs are increased by the overmolded screw connection.

[0003] US 11,632,903 B1 discloses a line trimmer head with a housing that has a dome. A threaded insert is mounted in the dome, allowing the line trimmer head to be screwed onto the drive shaft. A spool located in the housing is rotatably mounted on the dome or on a cylindrical section of the threaded insert projecting from the dome. The rotation of the spool relative to the housing is blocked or released by an advance mechanism. The advance mechanism includes a hexagonal projection formed on the underside of the spool, which interacts with a corresponding hexagonal projection on an actuating knob of the advance mechanism.

[0004] From WO 2008 / 053 508 A2, a string trimmer head is known in which an insert, in particular a metallic one, is inserted into the spool and attached to the spool. The insert has a thread or other means for connection to the drive shaft.

[0005] There are also trimmer heads where the housing or spool is placed onto the drive shaft and then secured by screwing a nut onto the shaft. A tool is required to loosen the nut. It has been found that this tool is not always carried along, for example, because it is forgotten or the operator deliberately does not want to carry the additional weight of the tool all the time.

[0006] The objective is to provide a line trimmer head that is at least partially improved with respect to the aforementioned disadvantages. This objective is achieved by the spool for the line trimmer head specified in claim 1 and the line trimmer head specified in claim 8. Furthermore, the objective is to provide a method for mounting a line trimmer head to a drive shaft that is improved with respect to the aforementioned disadvantages. This objective is achieved by the method specified in claim 10.

[0007] Because the spool includes a tool section in addition to the supply and storage sections, and is designed to actuate a screw connection, no additional tool needs to be carried for operating (i.e., loosening or tightening) the screw connection. Since the spool incorporates the tool section, the tool is always readily available. A screw connection is understood to be a nut, bolt, or similar threaded element that can be screwed into a corresponding thread on the drive shaft to attach the trimmer head to the drive shaft.

[0008] The tool section is the portion of the spool that, when the spool is used as a tool, comes into contact with the screw connection and exerts a torque on the screw connection when the spool rotates. The tool section is specifically designed to be rotationally symmetrical about the axis of rotation. This prevents imbalances caused by the tool section during operation of the trimmer head, and therefore eliminates the need for additional mass on the spool to balance the tool section.

[0009] In one embodiment, the tool section has a raised area with a circumferential contour that deviates from a circular shape for actuating the screw connection element. In an alternative embodiment, the tool section has a recess, in particular an opening, with a circumferential contour that deviates from a circular shape for actuating the screw connection element. In particular, the circumferential contour is designed as a square, hexagon, or other rotationally symmetrical geometry that is matched to a counter contour of the screw connection element.

[0010] In one embodiment, the coil has a sleeve, and the tool section is formed on the sleeve, particularly on an end face of the sleeve. By utilizing the high stiffness-to-weight ratio of the sleeve, the tool section can be designed to be lightweight yet relatively rigid. A particularly robust arrangement is achieved when the tool section is formed as an opening in the end face of the sleeve. After penetrating the wall thickness of the end face, the screw connection element can enter the cavity of the sleeve. This prevents the tool section from unintentionally slipping off the screw connection element. In another embodiment, the bearing section of the coil is also arranged on the sleeve, particularly on an inner circumference of the sleeve.

[0011] The sleeve runs coaxially to the spool's axis of rotation. This ensures that when used as a tool, the spool rotates around the same axis as it does during operation. This makes using the spool as a tool particularly intuitive for the operator. At the same time, a rotationally symmetrical arrangement of the tool section is especially easy to achieve in this way.

[0012] If the supply section, the bearing section, and the tooling section are made of a single material, particularly a plastic, the spool can be designed and manufactured in a particularly weight- and cost-efficient manner. In particular, existing spool structures can be repurposed for new functions. This allows for even greater weight savings compared to an additional tool. For example, the spool can have a flange that defines the supply section and simultaneously forms a handle for gripping the spool when used as a tool. In one embodiment, the spool has a sleeve with the bearing section located on its inner circumference and the tooling section on its end face. In this way, the tooling section benefits from the rigidity of the sleeve shape, which is already intended for supporting the spool.Adding the tool section to the spool can be done in a virtually weight-neutral way. Virtually weight-neutral means a weight increase or decrease of no more than 10 percent compared to the same spool without the tool section.

[0013] In one embodiment, the tool section projects beyond the supply section, particularly in the axial direction with respect to the axis of rotation. This allows the operator to better see the tool section when using the coil as a tool, and thus makes it easier to attach to the screw connection element. Specifically, the tool section projects beyond any flange that may be present and axially limits the supply section. If the tool section is formed on a sleeve that also carries the bearing section, the sleeve is extended axially such that its axial end projects beyond the supply section.

[0014] To operate the screw connection element with minimal effort, the outer diameter at which the coil is gripped and rotated when used as a tool is at least 3 cm, and in particular at least 6 cm. To ensure that the diameter can still be easily gripped with one hand, it is in particular no more than 12 cm. Specifically, the diameter for gripping the coil is designed on a flange that delimits the supply section.

[0015] During operation of the trimmer head on a drive shaft, the spool is housed within the trimmer head's casing, thus largely protecting it from contamination. For easy removal of the spool from the casing, the casing comprises a first and a second housing section that can be connected and disconnected without tools. The operator can quickly and easily access the spool as a tool by simply releasing the connection between the housing sections. Specifically, the first and second housing sections are connected by a snap-fit ​​mechanism. After opening the casing, particularly after removing the second housing section, the spool can be removed from the first housing section. The second housing section secures the spool against falling out of the first housing section.

[0016] In one embodiment, the trimmer head includes a switching device for adjusting the trimmer line from the supply section. Such switching devices are known to those skilled in the art. In one embodiment, the tool section is arranged within a cavity that is delimited by a spring of the switching device. This arrangement allows the tool section to be housed in a particularly space-saving manner within the trimmer head. In particular, the spring is attached to the second housing part. In this way, the spring is removed together with the second housing part when the housing is opened.

[0017] The tool section of the spool is only in operative connection with the screw connection element when the spool is used as a tool. Torque transmission between the tool section of the spool and the screw connection element only occurs when the spool is used as a tool. No torque transmission occurs between the tool section of the spool and the screw connection element during operation of the line trimmer head.

[0018] When using the spool as a tool, the spool must be at least partially removed from the trimmer head housing. To do this, the first and second housing parts must be separated. To mount the trimmer head to a drive shaft, the first housing part is attached to the drive shaft, and the screw connector is threaded onto the drive shaft. Then, the tool section of the spool is attached to the screw connector, and by rotating the spool, torque is applied to the screw connector. This tightens the screw connection. Afterward, the tool section is removed from the screw connector, and the spool is inserted into the first housing part. Finally, the second housing part is connected to the first housing part. The trimmer head is then ready for use.To remove the trimmer head from the drive shaft, the second housing part is separated from the first. The spool is removed from the first housing part. Then, the tool section of the spool is placed against the screw connection, and by turning the spool, torque is applied to the screw connection. This loosens the screw connection. The screw connection is then unscrewed from the drive shaft, and the first housing part is removed from the drive shaft. To store the trimmer head, the spool is reinserted into the first housing part, and the housing is closed with the second housing part.

[0019] When used as a tool and when operating the trimmer head, the spool has a different orientation relative to the first housing part. Specifically, this different orientation represents a 180° turn of the spool. This means the spool must be turned over to use the tool section and then turned over again to insert the spool into the housing for operation.

[0020] 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 drawing shows: Fig. 1 A side view of a string trimmer head mounted on a drive shaft in a longitudinal section along an axis of rotation of the string trimmer head, Fig. 2 an isometric view of the spool of the string trimmer head Fig. 1 without trimmer line included in the supply section, Fig. 3. Remove the trimmer head Fig. 1 with the second housing part removed and the spool reversed without cutting line during the assembly or disassembly of the line cutting head.

[0021] Fig. Figure 1 shows a string trimmer head 100 for cutting grass, brush, and the like. The string trimmer head 100 is mounted on a drive shaft 200 by means of a screw connection 60 and, during operation, is driven by the drive shaft 200 about a rotational axis 80. The string trimmer head 100 has a housing 50 in which a spool 1 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. During normal operation of the string trimmer head 100, the housing 50 and the spool 1 do not move relative to each other. In order to unwind new cutting line 3 from the spool 1 when the cutting line 3 is worn out, the cutting head 100 has a switching device which temporarily releases a relative movement between housing 50 and spool 1 and in this way allows cutting line 3 to unwind from the spool 1.

[0022] In the exemplary embodiment, the spool 1 is driven indirectly by the drive shaft 200 via a drive element 30 to power the trimmer head 100. The housing 50 is driven by the spool 1 by the unactuated switching device. When the switching device is actuated, the housing 50 can rotate relative to the spool 1. It is also possible for the housing 50 to be driven by the drive shaft 200 to power the trimmer head 100. In this case, the spool 1 is driven by the housing 50 by the unactuated switching device, and when the switching device is actuated, the spool 1 can rotate relative to the housing 50.

[0023] The housing 50 comprises a first housing part 51 and a second housing part 52, which are connected to each other without tools via a snap connection. When the trimmer line 3 is used up, the spool 1 can be easily removed and new trimmer line 3 wound onto the spool 1. New trimmer line 3 can also be wound onto the spool 1 without disassembling the housing 50 in a manner known to those skilled in the art. For this purpose, a line channel 16 is provided in the spool 1. A trimmer line 3 inserted through the line opening 58 of the housing 50 is guided through the line channel 16, through the spool 1, and out of another line opening 58 in the housing 50. The spool 1 is then rotated relative to the housing 50, thus drawing the trimmer line 3 through the line openings 58 into the housing 50 and winding it onto the spool 1. In the exemplary embodiment, a handle disc 31 arranged outside the housing 50 is provided for rotating the coil 1 arranged in the housing 50.The handle disc 31 is operatively connected to the coil 1 via the driver 30. A rotation of the handle disc 31 causes a rotation of the driver 30 and thus of the coil 1. In an embodiment where the housing 50 is driven by the drive shaft 200 and the coil 1 is driven by the housing 50, the handle disc 31 can also be designed differently and arranged directly on the coil 1.

[0024] The switching device comprises a spring 55 and interacting first switching elements 56 and second switching elements 57, which are formed on the housing 50 and the coil 1. The spring 55 pre-tensions the first switching elements 56 and the second switching elements 57 against each other, so that they overlap axially with respect to the axis of rotation 80, thus blocking relative rotation of the housing 50 and the coil 1. In the exemplary embodiment, actuation of the switching device causes the coil 1 and the housing 50 to move axially with respect to the axis of rotation 80, disengaging the first switching elements 56 and the second switching elements 57 and allowing relative rotation. The spring 55 ensures that the coil 1 and the housing 50 return to their axial initial position without actuation of the switching device, and that the switching elements 56 and 57 prevent relative rotation.In this embodiment, spring 55 is designed as a helical spring. Spring 55 defines a cavity into which, in this embodiment, the drive shaft 200 projects. A screw connection between the drive shaft 200 and the screw connection element 60 is arranged in the cavity of spring 55. In this embodiment, the screw connection element 60 secures the driver 30 to the drive shaft 200.

[0025] The spool 1 has a storage section 10 for storing multiple windings of the trimmer line 3. In the exemplary embodiment, the storage section 10 is divided into two line chambers, each formed between an outer flange 11 and a middle flange 12. The line channel 16 is formed in the middle flange 12. In the exemplary embodiment, second switching elements 57 of the switching device are arranged on at least one of the outer flanges 11. A different arrangement of the second switching elements 57 on the spool 1 is also possible. Radially within the storage section 10, the spool 1 has a bearing section 15. The bearing section 15 rotatably supports the spool 1 about the axis of rotation 80. In the exemplary embodiment, the bearing section 15 also provides axial guidance for the spool 1 relative to the housing 50.

[0026] As in Fig. As can be seen in Figure 2, the coil 1 has a sleeve 19. The sleeve 19 extends along the axis of rotation 80. A tool section 20 is formed on one end face of the sleeve 19. The tool section 20 includes an opening 22, which is designed with a circumferential contour that deviates from a circular shape for actuating the screw connection element 60. In the exemplary embodiment, the circumferential contour is hexagonal. Other designs of the circumferential contour that would appear advantageous to a person skilled in the art, such as a multi-tooth spline, are also conceivable. As in Fig. As can be seen in Figure 1, the bearing section 15 is formed on a circumferential surface of the sleeve 19. The coil 1 is mounted on the driver 30 on an inner circumferential surface of the sleeve 19. In the exemplary embodiment, the coil 1 and the housing 50, in particular the second housing part 52, are axially displaceably mounted one within the other on an outer circumferential surface of the sleeve 19. In the exemplary embodiment, the supply section 10, the bearing section 15, and the tool section 20 are formed in one piece. The coil 1 is made of a plastic material, in particular a fiber-reinforced plastic.

[0027] In operation of the line trimmer head 100, the tool section 20 projects beyond the outer flange 12 of the spool 1 by a projection u. In operation of the line trimmer head 100, the screw connection element 60 is arranged inside the sleeve 19, with the screw connection element 60 not projecting into the opening 22 of the tool section 20.

[0028] Fig.Figure 3 shows the use of the spool 1 as a tool. The second housing part 52 is separated from the first housing part 51. The spool 1 is removed from the housing 50, rotated 180°, and the tool section 20 is attached to the screw connection element 60. The overhang u allows the operator to easily see the orientation of the tool section 20 relative to the screw connection element 60 and thus facilitate its positioning. By rotating the spool 1 around the axis of rotation 80, a torque can be applied to the screw connection element 60 to actuate it. The operator can grip the spool 1 at one or more of the flanges 11, 12 to facilitate the application of the torque around the axis of rotation 80. The outer diameter d of the flanges is approximately 8 cm. Depending on the size of the trimmer head 100, the outer diameter d can also be smaller or larger. The screw connection element 60 dips into the opening 22 when the coil 1 is used as a tool.Because the tool section 20 is formed on a sleeve 19, the screw connection element 60 can immerse itself in the cavity of the sleeve 19, thus virtually eliminating the possibility of the tool section 20 slipping off the screw connection element 60 when the spool 1 is rotated. After the screw connection element 60 is actuated, i.e., loosened or tightened, the spool 1 is removed from the screw connection element 60, rotated 180°, and reinserted into the first housing part 51. Connecting the second housing part 52 to the first housing part 51 secures the spool 1 in the housing 50. In this embodiment, the spring 55 is held on the second housing part 52, so that when the second housing part 52 is connected to the first housing part 51, the spring 55 automatically engages the first and second switching elements 56, 57, thereby restoring the operating state of the line trimmer head 100.

Claims

[1] Spool (1) for a string trimmer head (100) comprising - a storage section (10) designed to accommodate several windings of a trimmer line (3) of the trimmer head (100), - a bearing section (15) designed to mount the spool (1) rotatably about an axis of rotation (80) of the spool (1) on the line trimmer head (100), characterized by , that the spool (1) further comprises a tool section (20) which is configured to actuate a screw connection element (60) for mounting the line trimmer head (100), wherein the tool section (20) is configured to be in operative contact with the screw connection element (60) only when the spool (1) is used as a tool, and wherein the spool (1) is configured to have a different orientation relative to a first housing part (51) of the line trimmer head (100) when used as a tool and in operation of the line trimmer head (100). [2] Coil (1) according to claim 1, characterized by , that the tool section (20) is rotationally symmetric to the axis of rotation (80) of the coil (1). [3] Coil (1) according to any one of the preceding claims, characterized by , that the tool section (20) has an opening (22) with a circumferential contour that deviates from the circular shape for actuating the screw connection element (60). [4] Coil (1) according to any one of the preceding claims, characterized by that the coil (1) has a sleeve (19) and the tool section (20) is formed on the sleeve (19), in particular on an end face of the sleeve (19). [5] Coil (1) according to any one of the preceding claims, characterized by , that the supply section (10), the storage section (15) and the tool section (20) are made of a single material, in particular of a plastic material. [6] Coil (1) according to any one of the preceding claims, characterized by, that the tool section (20), in particular in the axial direction with respect to the axis of rotation (80), protrudes by a projection (u) over the supply section (10). [7] Coil (1) according to any one of the preceding claims, characterized by , that the coil (1) has a flange (11) to limit the supply section (10) and the flange (11) has an outer diameter which is between 3 cm and 12 cm. [8] Thread trimmer head (100) comprising a housing (50) and a spool (1) arranged therein according to one of the preceding claims, wherein the housing (50) comprises a first housing part (51) and a second housing part (52) which can be connected and separated without tools. [9] Thread trimmer head (100) according to claim 8, comprising a switching device for adjusting the trimmer line (3) from the supply section (10), wherein the switching device comprises a spring (55) and the spring (55) defines a cavity, wherein the tool section (20) is arranged in the cavity. [10] Method for mounting a string trimmer head (100) according to one of the preceding claims to a drive shaft (200) for driving the string trimmer head (100), comprising the steps a. Mounting a first housing part (51) of the housing (50) of the string trimmer head (100) onto the drive shaft (200) b. Threading a screw connection element (60) onto the drive shaft (200) c. Attaching the tool section (20) of the coil (1) to the screw connection element (60) d. Tightening the screw connection element (60) by rotating the coil (1) e. Removing the tool section (20) of the coil (1) from the screw connection element (60) f. Inserting the coil (1) into the first housing part (51), in particular after first turning the coil (1) inside out, g. Connecting a second housing part (52) to the first housing part (51), in particular by means of a snap connection.

Images