Trimmer line supply control

Abstract

The present disclosure relates to a trimmer head (1). The trimmer head (1) includes a rotatable housing (12) connectable to a trimmer line spool (13), the housing (12) rotatably supporting the trimmer line spool (13), and a locking force (F) for locking the trimmer line spool (13). L The locking mechanism (14) is arranged to move from a locked to an unlocked position when the rotational speed of the trimmer head (1) is increased above the operating speed. R ) is the locking force (F L In the unlocked position, the locking mechanism (14) is configured so that the trimmer line spool (13) is movable, the trimmer line (3) wound around the trimmer line spool (13) is released, and the centrifugal force (F) generated by the rotation of the trimmer head (1) is released. C ) to release the trimmer line spool (13) from the housing (12) so that the trimmer line (3) can be fed.

Description

[Technical field]

[0001] The present disclosure relates generally to trimmers. In particular, various embodiments described in the present disclosure relate to a method for controlling the supply of a trimmer line, a trimmer head, and a trimmer. [Background technology]

[0002] A trimmer is a tool that uses a rotating line or multiple lines to cut grass and ground cover. Such trimmers are also known as string trimmers, line trimmers, or strimmers. Grass is cut by the line as it strikes the grass or other growth. This physical interaction between the grass and the trimmer line wears the trimmer line, and over time, the trimmer line typically shortens. More trimmer lines must be supplied to provide a uniform cutting action.

[0003] Traditionally, the push button is located on the back of the trimmer head. When the operator wants to dispense more trimmer line, he presses the push button by pressing the trimmer head against the ground. This dispenses the trimmer line. However, because the push button protrudes from the trimmer head, this arrangement increases the cutting height of the trimmer head, which is not suitable for fine and precise trimming. Furthermore, the pressing action can cause unwanted circular marks in the grass. Therefore, other methods of initiating trimmer line dispense have been developed, such as pressing a button, manual activation, and fully automatic dispense. In button press dispense, instead of pressing the trimmer head against the ground, the trimmer line dispense is performed by pressing a button. These trimmers usually operate with unidirectional rotation, i.e. the trimmer head rotates in one direction. To control bidirectional rotation trimmers, these trimmer heads have been further developed. However, such trimmer heads are complex and have many parts. Since the trimmer head is a part that is subject to wear and tear, it is desirable for it to be as simple and robust as possible.

[0004] Therefore, there is a need for an improved method of supplying trimmer lines that also works with bidirectional rotating trimmers. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, it is therefore a general objective of the aspects and embodiments described in this disclosure to provide a solution with an improved method of supplying trimmer lines that is robust, includes few parts and works with bi-directional rotating trimmers. [Means for solving the problem]

[0006] This general object is set out in the accompanying independent claims. Advantageous embodiments are set out in the accompanying dependent claims. According to a first aspect, there is provided a trimmer head. The trimmer head comprises a rotatable housing connectable to a trimmer line spool, the housing rotatably supporting the trimmer line spool, and a locking mechanism for locking the trimmer line spool to the housing with a locking force. The locking mechanism is arranged to move from a locked position to an unlocked position when the rotational speed of the trimmer head is increased above an operating speed. The increased rotational speed causes the release force to be greater than the locking force. The locking mechanism in the unlocked position releases the trimmer line spool from the housing such that the trimmer line spool is rotatable relative to the housing and the trimmer line wound around the trimmer line spool is released and pulled out by centrifugal force generated by rotation of the trimmer head to allow feeding of the trimmer line.

[0007] In some embodiments, the locking mechanism is a spring loaded locking mechanism. The lifting speed shifts the center of gravity of the locking mechanism, causing the release force to be greater than the locking force of the spring loaded locking mechanism.

[0008] In some embodiments, the locking mechanism is arranged to return from the unlocked position to the locked position when the rotational speed of the trimmer head slows below the operating speed, and the release force is reduced to be less than the locking force.

[0009] In some embodiments, the locking mechanism comprises a pivoting locking latch and the trimmer line spool comprises one or more stops. The pivoting locking latch is arranged to engage one of the one or more stops in the locked position. In one embodiment, the trimmer line spool may further comprise one or more release stops. The pivoting locking latch may be arranged to engage one of the one or more release stops when the locking mechanism is moved to the unlocked position.

[0010] In some embodiments, the trimmer head includes a button disposed on the housing that is operably connected to the locking mechanism to move the locking mechanism to an unlocked position when the button is pressed, thereby allowing a user to manually dispense the trimmer line by pressing the button to pull the trimmer line from the trimmer head.

[0011] In some embodiments, the locking mechanism allows for manual rotation of the trimmer line spool relative to the housing in one rotational direction, thereby providing a trimmer head that allows the trimmer line to be loaded into the trimmer head without having to dissemble the trimmer head.

[0012] In some embodiments, the trimmer head includes a grip disposed on the housing to facilitate loading the trimmer line into the trimmer head. In some embodiments, the trimmer head includes a recess on the underside of the trimmer head. The grip is disposed inside the recess. This provides a user-friendly trimmer head that is less likely to hit objects during operation of the trimmer head. Furthermore, the grip does not need to increase the cutting height of the trimmer head.

[0013] According to a second aspect there is provided a trimmer comprising a trimmer head according to the first aspect, the trimmer further comprising drive means for driving the trimmer head in rotation, the trimmer being arranged to increase the rotational speed of the trimmer head above an operating speed, thereby rotating the trimmer line spool relative to the housing.

[0014] In some embodiments, the rotational speed of the trimmer head increases in response to the activation action. In some embodiments, the trimmer is arranged to slow the rotational speed of the trimmer head below the operating speed to move the locking mechanism from an unlocked position to a locked position that locks the trimmer line spool to the housing. The trimmer may be arranged to slow the rotational speed of the trimmer head by alternately slowing and increasing the rotational speed of the trimmer head until the rotational speed of the trimmer head is below the operating speed.

[0015] In some embodiments the trimmer is arranged to reduce the rotational speed of the trimmer head when the rotational speed reaches a maximum rotational speed, while in other embodiments the trimmer is arranged to reduce the rotational speed of the trimmer head a predetermined time after the rotational speed has increased.

[0016] In some embodiments, the trimmer is an electric trimmer and the drive means comprises a power source and an electric motor, hi other embodiments, the trimmer is an internal combustion engine powered trimmer and the drive means includes a fuel tank, an engine, and may further comprise a gear assembly.

[0017] According to a third aspect, there is provided a method of controlling dispensing of trimmer line in a trimmer including a trimmer head. The trimmer head includes a rotatable housing, a trimmer line spool rotatably supported in the housing, and a locking mechanism for locking the trimmer line spool. The method includes increasing a rotational speed of the trimmer head above an operating speed, whereby at the increased rotational speed, the locking mechanism moves from a locked position to an unlocked position, and the trimmer line wound around the trimmer line spool is released and pulled out by centrifugal force generated by rotation of the trimmer head, thereby allowing dispensing of the trimmer line.

[0018] In some embodiments, the rotational speed increases in response to the actuation action. In some embodiments, the method further comprises slowing down the rotational speed of the trimmer head below the operating speed, whereby the locking mechanism moves from the unlocked position to the locked position; in one embodiment, the method comprises slowing down the rotational speed of the trimmer head by alternatingly slowing and increasing the rotational speed of the trimmer head until the rotational speed of the trimmer head is below the operating speed.

[0019] In some embodiments, the method further comprises decreasing the rotational speed of the trimmer head when the rotational speed reaches a maximum rotational speed, while in other embodiments, the method further comprises decreasing the rotational speed of the trimmer head a predetermined time after the rotational speed has increased.

[0020] Some of the above embodiments eliminate or at least mitigate the drawbacks discussed above in this disclosure. The embodiments proposed herein provide a robust and simple trimmer head with few parts that provides an improved supply of trimmer lines that also works with bi-directional rotating trimmers.

[0021] Other features and advantages of the disclosed embodiments will be apparent from the following detailed disclosure, the appended dependent claims, and the drawings. In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to "elements, devices, components, means, steps, etc." are to be interpreted in a non-limiting manner as referring to one or more examples of the element, device, component, means, step, etc., unless otherwise expressly stated. The steps of the methods disclosed herein do not have to be performed in the exact order disclosed, unless otherwise expressly stated.

[0022] These and other aspects, features and advantages will become apparent and elucidated in the following description of various embodiments, which proceeds with reference to the accompanying drawings. [Brief description of the drawings]

[0023] [Figure 1] Schematic diagram of a trimmer. [Diagram 2] Schematic diagram of a trimmer head. [Diagram 3] FIG. 1 is a schematic diagram of a trimmer head with a locking mechanism according to one embodiment. [Figure 4a] FIG. 2 is a schematic diagram of a trimmer line spool with a locking mechanism according to one embodiment. [Figure 4b] Schematic diagram of the trimmer line spool and locking mechanism according to FIG. 4a when mounted in the housing of the trimmer head. [Figure 5a] 13 is a schematic illustrating rotation of the spool relative to the locking mechanism during a supply line sequence, according to one embodiment. [Figure 5b] 4 is a time graph of a supply line sequence according to one embodiment. [Figure 6] 4 is a flow chart of a method according to one embodiment. [Figure 7] 11A-11C are schematic diagrams of a trimmer head according to some further embodiments of the present disclosure. [Figure 8a] 8 is a schematic diagram of a portion of a housing of a trimmer head according to the embodiment shown in FIG. 7. [Figure 8b] 8b is a schematic diagram of the portion of the housing shown in FIG. 8a when the button is pressed in a direction towards the axis of rotation of the trimmer head. [Figure 9] FIG. 5 is a schematic diagram of a trimmer line spool with a locking mechanism for a trimmer head according to the embodiment described with reference to FIGS. 7 to 8b. [Figure 10] 10 is a schematic diagram of a trimmer line spool with a locking mechanism according to the embodiment shown in FIG. 9, where the trimmer line spool is shown from a perspective coinciding with the axis of rotation of the trimmer head. [Figure 11] FIG. 11 is a perspective view of the underside of the trimmer head according to the embodiment described with reference to FIGS. 7 to 10. [Figure 12] 12 is a cross-sectional view of the trimmer head shown in FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The disclosed embodiments will be described in more detail below with reference to the attached drawings showing specific embodiments of the present invention. However, the present invention can be embodied in many different forms, and therefore should not be construed as being limited to the embodiments described herein. Rather, these embodiments are described as examples so that the present disclosure is comprehensive and sufficient, and the scope of the present invention can be fully conveyed to those skilled in the art. In the detailed description, the same reference numerals refer to the same elements.

[0025] In one of its aspects, the disclosure described herein relates to a trimmer 10. FIG. 1 shows a schematic of such a trimmer 10. The trimmer 10 of FIG. 1 is a string trimmer and may be used, for example, to cut or trim grass and ground cover in gardens, parks, and other areas with vegetation. The trimmer 10 includes a trimmer head 1 according to another aspect of the disclosure. The trimmer head 1 is a rotary cutting device and may include a trimmer line 3 extending radially from the trimmer head 1. The trimmer line 3 may extend in any number of directions, although a balanced arrangement is preferred. Typically, two trimmer lines 3 are used, arranged to extend in opposite directions.

[0026] FIG. 2 shows a schematic of a trimmer head 1 according to the present disclosure. As shown in FIG. 2, the trimmer head 1 comprises a housing 12. The housing 12 is connectable to a trimmer line spool 13 that is rotatably supported by the housing 12. Thus, when the trimmer 10 is in use, the housing 12 of the trimmer head 1 is connected to the trimmer line spool 13. When the trimmer 10 is not in use, the trimmer line spool 13 is not necessarily connected to the housing 12, but may be. The trimmer line spool 13 may be connected to the housing 12, for example, via a spring, such as a torsion spring. The trimmer line spool 13 is not shown in FIG. 2, since it may be connectable to the housing 12 inside or internal to the housing 12, as shown clearly in FIG. 4b. The trimmer line 3 extends through a hole or opening 11 in the trimmer head housing 12. As shown clearly in FIG. 4a, the trimmer line 3 is wound around the trimmer line spool 13.

[0027] The trimmer head 1 further includes a locking mechanism 14 for locking the trimmer line spool 13 to the housing 12. The trimmer line spool 13 is held by a retaining force F H The housing 12 is locked by a lock mechanism 14 having a holding force F H and locking mechanism 14. When trimmer line spool 13 is locked to housing 12, trimmer line spool 13 does not rotate relative to housing 12. In the locked position, trimmer line spool 13 rotates with housing 12.

[0028] FIG. 4a is a perspective view of the trimmer line spool 13 relative to the locking mechanism 14 and shows the applied retention force F H1 shows a schematic diagram of a trimmer head 100 according to an embodiment of the present invention. The locking mechanism 14 is arranged to move from the locked position to the unlocked position when the rotational speed of the trimmer head 1 is increased to be higher than the operating speed. The operating speed is the speed at which the trimmer head 1 is typically operated, i.e., the speed at which the trimmer head 1 may be used to cut grass or ground cover. The operating speed may include a range of speeds. In these embodiments, the rotational speed is increased to be higher than the maximum operating speed, for example, on the order of 1.1 to 1.3 times the maximum operating speed. As an example, the maximum operating speed may be about 5500 revolutions per minute (rpm). The increased speed may range from about 6500 to 7000 rpm. However, it is understood that the range of speeds may be lower or higher than the illustrated range, provided that the rotational speed that moves the locking mechanism 14 from the locked position to the unlocked position is different because it is significantly higher than the operating speed.

[0029] As the rotation speed increases, the release force F R is the locking force F L Therefore, as the rotation speed increases, the locking force F L Release force F greater than R is applied to the locking mechanism 14. The locking mechanism 14 is then forcibly moved from the locked position to the unlocked position. In the unlocked position, the locking mechanism 14 releases the trimmer line spool 13 from the housing 12 so that the trimmer line spool 13 is rotatable relative to the housing 12. The trimmer line 3 wound around the trimmer line spool 13 is then released and centrifugal force F generated by the rotation of the trimmer head 1 is applied to the locking mechanism 14. C This allows the trimmer line 3 to be fed. The feeding length of the trimmer line 3 corresponds to the relative rotation between the housing 12 and the trimmer line spool 13. Thus, when the rotation speed of the trimmer head 1 increases and is higher than the operating speed, the trimmer line 3 is fed.

[0030] By providing a trimmer head 1 where the trimmer line 3 is fed by increasing the rotation speed to be higher than the operating speed, the operating speed range is separated from the line feeding speed range. This ensures that the trimmer line 3 is not fed by mistake. The trimmer line 3 is fed only when the rotation speed is increased, which occurs when the motor is boosted higher than the operating speed. Thus, incorrect feeding is eliminated or at least reduced. Furthermore, due to the provided structure of the provided trimmer line feeding mechanism, it is also possible to use the line feeding mechanism with a bidirectional rotating trimmer.

[0031] According to one embodiment, as also shown in Figures 3, 4a and 4b, the locking mechanism 14 may be a spring-loaded locking mechanism 14. The lifting speed shifts the center of gravity of the locking mechanism 14, thereby increasing the release force F R The locking force F of the spring locking mechanism 14 L The release force F R is the locking force F L When it becomes greater, the locking mechanism 14 moves from the locked position to the unlocked position.

[0032] As shown in Figures 4a and 4b, the spring-loaded locking mechanism 14 according to one embodiment comprises a spring 19 and a base plate 15. According to the embodiment shown in Figures 4a and 4b, the spring is a type of coil spring. According to further embodiments, the spring-loaded locking mechanism 14 may comprise another type of spring, such as a leaf spring. The base plate 15 is provided with a slotted through hole. The slotted hole allows the base plate 15 of the spring-loaded mechanism to move as the center of gravity shifts with increasing rotation speed. The movement of the base plate 15 generates a release force F R and, as mentioned above, the release force F R is the locking force F L, the trimmer line spool 13 is released from the housing 12. Once the trimmer line spool 13 is released, the trimmer line 3 can be fed. By providing a spring loaded locking mechanism 14, the trimmer line feeding mechanism is achieved using fewer parts. This makes the trimmer head 1 robust and suitable for use with bi-directional rotation trimmers.

[0033] In some embodiments, as shown in Figure 5a, the locking mechanism 14 may include a pivoting locking latch 18 and the trimmer line spool 13 may include one or more stops 16. The pivoting locking latch 18 may be positioned to engage one of the one or more stops 16, 16' in the locked position. Thus, when the locking mechanism 14 is in the locked position A, A', the pivoting latch 18 may lock into one of the one or more stops 16, 16'.

[0034] According to some embodiments, the trimmer line spool 13 may further include one or more release stops 17. The pivoting locking latch 18 may be positioned to engage one of the one or more release stops 17 when the locking mechanism 14 is moved to the unlocked position. Thus, when the locking mechanism 14 is moved from the locked position to the unlocked position, the pivoting locking latch 18 is forced from a position where it engages one of the stops 16, 16′ to engage one of the one or more release stops 17.

[0035] According to these embodiments, the trimmer line spool 13 may rotate relative to the housing 12 to an extent defined by the distance B between the stop 16 and the release stop 17. Thus, the placement of the stops 16 and the release stop 17 and the distance between them may control the amount of rotation of the trimming line spool 13 relative to the housing 12. The amount of rotation B of the trimming line spool 13 relative to the housing 12 indicates the amount of trimmer line 3 dispensed each time the locking mechanism 14 rotates between the locked and unlocked positions. FIG. 5a illustrates a trimmer line spool 13 having six stops 16, 16' and six release stops 17. However, it is understood that the trimmer line spool 13 may have more or fewer stops 16, 16', 17. The more stops, the shorter the trimmer line 3 dispensed. The fewer stops, the longer the trimmer line 3 dispensed. However, with fewer stops 16, 16', 17 the user may feel a more abrupt stop in the trimmer line spool 13, so a design compromise may be made between the length of trimmer line 3 delivered and smoothness of operation.

[0036] In some embodiments, the locking mechanism 14 may be arranged to move back from the unlocked position to the locked position A' when the rotational speed of the trimmer head 1 slows down below the operating speed. According to some embodiments, the movement back to the locked position begins with the locking latch 18 engaging the release stop 17. When the rotational speed of the trimmer head 1 slows down below the operating speed, the release force F R The locking force F L 5a, the locking latch 18 will return to lock into the next stop 16', which is the position designated A' in Figure 5a, as will be described in more detail below in connection with the trimmer 10.

[0037] As explained above, in one of its aspects the disclosure presented herein relates to a trimmer 10 as shown in Figure 1. The trimmer 10 comprises a trimmer head 1 according to any of the above embodiments. The trimmer 10 further comprises drive means 2, 4 for driving the trimmer head 1 in rotation. The trimmer 10 is arranged to increase the rotational speed of the trimmer head 1 above an operating speed, thereby rotating the trimmer line spool 13 relative to the housing 12 of the trimmer head 1. This feeds the trimmer line 3.

[0038] In one exemplary embodiment, the trimmer 10 is an electric trimmer. The drive means may then comprise a power source 4, such as a battery or grid connector, which provides power to an electric motor 2 arranged to rotate the trimmer head 1. In another exemplary embodiment, the trimmer 10 is an internal combustion engine driven trimmer. The drive means may also comprise a fuel tank which provides fuel to the engine 4 to drive the trimmer head 1 via the gear assembly 2. It should be noted that although the description herein focuses on electric trimmers, the disclosure herein may also be applied to internal combustion engine driven trimmers. For example, an increase in operating speed may be achieved by providing increased power to increase the rotational speed of the motor, as well as by increasing fuel injection and / or increasing the engine throttle opening to increase engine rpm, as described in more detail below.

[0039] The trimmer 10 may further include one or more handles 5 and pole 6 on which the power supply 4 and trimmer head 1 may be positioned. The trimmer 10 may further include a trim guard or shield 7. User controls including one or more buttons, such as a speed control, a start button, and / or a button to initiate an automatic trimmer line feed, may be located adjacent to (or on) the one or more handles 5. The buttons may be located on a control panel 8. The controls may include a dead-man's-hand switch (depressed by the palm of the operator's hand while gripping the grip 5), a throttle control switch 28 (actuated by the operator's finger), among other controls such as changing power levels, changing direction of rotation, to name a few. The control panel 8 may also include visual indicators, such as LEDs (light emitting diodes), that indicate the status of the trimmer 10.

[0040] The trimmer 10 may be a bi-directional trimmer that changes the direction of rotation of the drive means between a clockwise and a counterclockwise direction for rotation of the rotary cutting implement, or the trimmer 10 may be a uni-directional trimmer.

[0041] A method and trimmer 10 according to the present disclosure will now be described with reference to Figures 5a, 5b and 6. Figure 5b shows a time graph of the rotational speed of the motor 2 when controlling the supply of the trimmer line 3. Figure 6 shows a flow chart corresponding to a method 600 for carrying out the control of Figure 5b.

[0042] As shown in FIG. 5b, a trimmer 10 according to the present disclosure is configured to first ramp up the angular velocity of the motor 2 to rotate at an operating speed. The operating speed is a rotational speed at which the trimmer head 1 of the trimmer 10 can operate and is used to cut or trim grass and ground cover. The operating speed may include a range of speeds, according to some embodiments. If the operating speed includes a range of speeds, there may be a maximum operating speed that corresponds to the operating speed. According to one embodiment, the maximum operating speed may be 5500 rpm, and this maximum operating speed is shown by the dotted line in FIG. 5b.

[0043] Once the trimmer 10 is operating at the operating speed, the motor 2 may further increase the rotational speed of the trimmer head 1. The rotational speed of the trimmer head 1 is increased to be higher than the operating speed in step 620 of the method 600. This may occur, for example, in response to receiving an activation action in step 610 of the method 600, i.e., in response to receiving an activation action 610. The rotational speed increases in response to the activation action. The activation action may be caused, for example, by an operator issuing a command to feed the trimmer line 3. The command may be given via a button, switch, or lever on the control panel 8. As the rotational speed increases, the locking mechanism 14 moves from the locked position to the unlocked position.

[0044] In an exemplary embodiment, as the locking mechanism 14 moves from the locked position, the locking latches 18 move radially outward from the stops 16 (position A in FIG. 5a) to the unlocked position (area B in FIG. 5a). When the locking mechanism 14 is in the unlocked position, the trimmer line spool 13 is released and the trimmer line 3 wound around the trimmer line spool 13 is pulled by the centrifugal force F caused by the rotation of the trimmer head 1. C, allowing dispensing of the trimmer line 3 in step 630 of the method 600. Dispensing of the trimmer line 3 occurs when the trimmer line spool 13 rotates relative to the housing 12, which occurs when the locking latch 18 is not in contact with the stops 16, 16' and the release stop 17, such that the locking mechanism 14 does not lock the trimmer line spool 13 to the housing 12.

[0045] In some embodiments, the trimmer 10 may be configured to move the locking mechanism 14 from the unlocked position to the locked position in step 640 of the method 600 by slowing the rotational speed of the trimmer head 1 below the operating speed. The speed reduction corresponds to region C in FIG. 5b. As shown in FIG. 5b, the rotational speed is reduced below the line showing the operating speed at 5500 rpm. Furthermore, if the operating speed is a range of speeds, the rotational speed is reduced to be below the operating speed or at least within a lower range of the operating speed. By actively braking the rotational speed to be lower than the operating speed, the locking mechanism 14 moves from the unlocked position back to the next locked position A', where it may ensure that the locking latch 18 engages the next stop 16' and that the locking mechanism 14 is not stuck in the unlocked position.

[0046] In some embodiments, the trimmer 10 may be configured in step 640 of the method 600 to move the locking mechanism 14 from a release stop position D, where the locking latch 18 engages the release stop 17, to a locked position A, A', where the locking latch 18 engages the stop 16, 16', by slowing the rotational speed of the trimmer head 1 below the operating speed. The speed reduction corresponds to region C in FIG. 5b. As shown in FIG. 5b, the rotational speed is reduced to be below the line showing the operating speed at 5500 rpm. As the rotational speed is reduced, the locking latch moves radially inward from the release stop position D. Furthermore, if the operating speed is a range of speeds, the rotational speed is reduced to be below the operating speed or at least within a lower range of the operating speed. By actively braking the rotational speed to be lower than the operating speed, the locking latch 18 may be moved back from the release stop position D to the next locked position A', thereby ensuring the delivery of a controlled length of trimmer line corresponding to the distance C between the release stop position D and the stop position A'. By combining this method with a trimmer head with inside and outside stop positions, very accurate control of the length of trimmer line dispensed during each actuation can be achieved.

[0047] The step 640 of reducing the rotational speed may be performed in different ways. According to one embodiment, the trimmer 10 may be configured to continuously reduce the rotational speed below the operating speed, for example, until the rotational speed reaches a certain predetermined value or for a certain period of time. Alternatively, the trimmer 10 may be configured to reduce the rotational speed by alternating between reducing and increasing the rotational speed of the trimmer head 1 until the rotational speed of the trimmer head 10 is lower than the operating speed. By alternating between reducing and increasing the rotational speed, the trimmer head 1 may move or oscillate with changing rotational speed, which may facilitate the locking mechanism 14 moving from the release stop position and / or the unlocked position to the inner locked position A'. Regardless of which method is used to reduce the rotational speed, the rotational speed may be reduced after a certain time after the rotational speed has increased or when the rotational speed reaches a maximum rotational speed, i.e. the maximum rotational speed possible for the trimmer 10. For example, in one embodiment, the rotational speed is reduced, for example, 0.1 to 0.5 seconds after the rotational speed starts to increase. Alternatively, the rotation speed is reduced when it reaches the maximum permissible rotation speed, which may have a value of, for example, 6000 to 7000 rpm. For example, for trimmers driven by electric motors, the international standard IEC 62841-1 SCF limits the maximum permissible rotation speed to 130% of the maximum operating rotation speed.

[0048] After the rotational speed has decreased below the operating speed, the trimmer 10 may be configured to increase the rotational speed again until the operating speed is reached in step 650 of method 600 so that the operator can continue to use the trimmer 10 to cut grass or ground cover. The entire process of increasing the rotational speed above the operating speed, decreasing the rotational speed below the operating speed, and then increasing the rotational speed again to reach the operating speed, i.e., the sequence shown in the time graph of FIG. 5b, may take approximately 0.3 to 1.0 seconds. Thus, a solution is provided for controlling the feed of the trimmer line that is smooth and fast.

[0049] Furthermore, the provided trimmer 10 and the provided method 600 allow for a simple yet robust structure with few parts to control the feeding of the trimmer line 3 in the trimmer head 1. The provided trimmer 10, trimmer head 1, and method 600 also work with bi-directional rotation. Furthermore, the present disclosure provides a solution where the trimmer line 3 is fed at a speed that exceeds the operating speed, thus avoiding erroneous line feeding. The trimmer 10 will not accidentally increase its rotation speed to be higher than the operating speed. This will only happen if an intentional speed increase is attempted. Thus, the present disclosure provides a safe solution for automatic remote trimmer line 3 feeding.

[0050] Fig. 7 shows a schematic of a trimmer head 1 according to some further embodiments of the present disclosure. The trimmer head 1 according to the embodiment shown in Fig. 7 has the same features, functions and advantages as the trimmer head 1 described with reference to Figs. 1 to 6, but with some differences which are described below. Furthermore, the method 600 described with reference to Figs. 5a, 5b and 6 may be performed using the trimmer head 1 according to the embodiment shown in Fig. 7.

[0051] The trimmer head 1 according to the embodiment shown in Figure 7 allows for manual feeding of the trimmer line 3 by pressing a button 32 located on the housing 12 of the trimmer head 1, as will be described below. Furthermore, the trimmer head 1 according to the embodiment shown in Figure 7 allows for quick and easy loading of the trimmer line 3 into the trimmer head 1 without the need to dissemble the trimmer head 1, as will be described below.

[0052] Fig. 8a shows a schematic of a part of the housing 12 of the trimmer head 1 according to the embodiment shown in Fig. 7. Fig. 8a shows the spring-loaded locking mechanism 14 of the trimmer head 1. Similar to the embodiments described with reference to Figs. 1 to 5a, the spring-loaded locking mechanism 14 according to these embodiments comprises a spring 19, a base plate 15 and a locking latch 18. According to the embodiment shown in Fig. 8a, the spring 19 is a type of leaf spring. According to a further embodiment, the trimmer head 1 according to the embodiment shown in Fig. 8b may comprise a coil spring like the embodiment of the trimmer head 1 described with reference to Figs. 1 to 5a.

[0053] Furthermore, according to the embodiment shown in Fig. 8a, the connection between the locking latch 18 and the base plate 15 has play, so that the locking latch 18 can be moved radially of the trimmer head 1 towards the axis of rotation ax of the trimmer head 1 without moving the base plate 15. During operation of the trimmer head 1, the trimmer head 1 is configured to rotate about the axis of rotation ax. Furthermore, according to the embodiment shown in Figs. 7 and 8a, a button 32 is operably connected to the locking latch 18. In Fig. 8a, the spring-loaded locking mechanism 14 is shown with the button 32 not pressed.

[0054] Figure 8b shows a schematic of the part of the housing 12 shown in Figure 8a when the button 32 is pressed in a direction towards the axis of rotation ax of the trimmer head 1. As a result, the locking latch 18 moves in a direction towards the axis of rotation ax, as shown in Figure 8b. Due to the play between the locking latch 18 and the base plate 15, the user can see the locking force F exerted by the spring 19 on the locking mechanism 14 when pressing the button 32. L Thus, when the button 32 is pressed, the locking latch 18 moves to the unlocked position shown in Figure 8b, thereby moving the locking mechanism 14 from the locked position to the unlocked position.

[0055] In the following, unless otherwise indicated, Figures 7 to 8b are simultaneously referred to. A user may, for example, press the button 32 to move the locking mechanism 14 to the unlocked position and pull the trimmer line 3 out of the opening 11 of the trimmer head 1 to feed it manually. As an example, a user may perform manual feeding of the trimmer line 3 when the trimmer line 3 is too short and the rotation of the trimmer head 1 does not provide enough momentum to pull the trimmer line 3 out.

[0056] Fig. 9 shows a schematic of the trimmer line spool 13 with the locking mechanism 14 of the trimmer head 1 according to the embodiment described with reference to Figs. 7 to 8b. In the following, Figs. 7 to 9 are referred to simultaneously unless otherwise indicated. The locking mechanism 14 is configured to lock the trimmer line spool 13 to the housing 12 when in the locked position according to the embodiments of the trimmer head 1 described with reference to Figs. 1 to 5a. However, according to these embodiments, the trimmer line spool 13 is fixed to the housing 12 for rotation in only one of two rotational directions. That is, as shown in Fig. 9, each stop 16 of the trimmer line spool 13 comprises an inclined surface 36 on one side of the stop 16 and a stop surface 38 on the opposite side of the stop. The inclined surface 36 of the stop 16 displaces the locking latch 18 to the unlocked position upon relative rotation between the housing 12 and the trimmer line spool 13 about the rotation axis ax, as described below.

[0057] FIG. 10 shows a schematic of the trimmer line spool 13 with the locking mechanism 14 according to the embodiment shown in FIG. 9, when the trimmer line spool 13 is shown from a perspective coinciding with the rotation axis ax of the trimmer head 1. In the following, unless otherwise indicated, reference is made simultaneously to FIGS. 7 to 10. The components of the locking mechanism 14, including the locking latch 18, are mounted on the housing 12 of the trimmer head 1. In FIG. 10, the locking latch 18 is shown in a locked position and abutting against a stop surface 38 of one of the stops 16 of the trimmer line spool 13. The abutting contact between the locking latch 18 and the stop surface 38 of the stop 16 prevents the trimmer line spool 13 from rotating relative to the housing 12 in a first rotational direction r1 shown in FIG. 10. Similarly, the abutting contact between the locking latch 18 and the stop surface 38 of the stop 16 prevents the housing 12 from rotating relative to the trimmer line spool 13 in a second rotational direction r2 shown in FIG. 10. The second rotation direction r2 is opposite to the first rotation direction r1.

[0058] However, the angled surface 36 of the stop 16 of the trimmer line spool 13 is configured such that abutting contact between the angled surface 36 and the locking latch 18 displaces the locking latch 18 to the unlocked position. In FIG. 10, the locking latch 18' is shown diagrammatically in dashed lines to facilitate understanding of the working principle of the trimmer head 1 and the interaction between the locking mechanism 14 and the stop 16 of the trimmer head 1. As will be appreciated from the above, the trimmer line spool 13 is free to rotate relative to the housing 12 in a second rotational direction r2 shown in FIG. 10. Similarly, the housing 12 is free to rotate relative to the trimmer line spool 13 in a first rotational direction r1 shown in FIG. 10, facilitating loading of the trimmer line onto the trimmer line spool 13, as will be explained below.

[0059] Figure 11 is a rear perspective view of the trimmer head 1 according to the embodiment described with reference to Figures 7 to 10. As best seen in Figure 11, the trimmer line spool 13 of the trimmer head 1 is provided with a grip 40. According to the illustrated embodiment, the grip 40 is formed as a knob and is arranged inside a recess 42 at the rear side of the trimmer head 1. However, according to some further embodiments, the grip 40 may also protrude from the trimmer head 1. The grip 40 may be integral with the trimmer line spool 13 or may be a separate part attached to the trimmer line spool 13. The grip 40 further facilitates loading of the trimmer line, as will be explained below.

[0060] FIG. 12 shows a cross section of the trimmer head 1 shown in FIG. 11. In FIG. 12, the cross section is along a plane including the rotation axis ax of the trimmer head 1. In the following, unless otherwise indicated, FIGS. 7 to 12 will be simultaneously referred to. Due to the features of the trimmer head 1 according to these embodiments, a user can load the trimmer line 3 onto the trimmer line spool 13 by simply inserting the trimmer line 3 into the opening 11 of the housing 12 and passing it through the through hole 44 of the trimmer line spool 13 without the need to dissemble the trimmer head 1. Then, the user can manually rotate the trimmer line spool 13 and the housing 12 relative to each other to supply the trimmer line 3 to the trimmer line spool 13. In this way, the user can perform manual relative rotation between the trimmer line spool 13 and the housing 12. As will be appreciated from the above, a user may wind the trimmer line 3 on the trimmer line spool 13 by rotating the housing 12 of the trimmer head 1 relative to the trimmer line spool 13 in a first rotational direction r1 as shown in Figures 10 and 12. Of course, alternatively, a user may wind the trimmer line 3 on the trimmer line spool 13 by rotating the trimmer line spool 13 of the trimmer head 1 relative to the housing 12 in a second rotational direction r2 as shown in Figure 10.

[0061] A user may use the grip 40 and grasp around the housing 12 when rotating the trimmer line spool 13 relative to the housing 12. The grip 40 is disposed inside the recess 42 on the back side of the trimmer head 1 so that no portion of the grip 40 protrudes from the trimmer head 1. In this manner, the grip 40 is less likely to hit objects during operation of the trimmer head 1. Furthermore, the grip 40 may not increase the cutting height of the trimmer head 1. However, as noted above, according to some further embodiments, the grip 40 may also protrude from the trimmer head 1.

[0062] As shown in FIG. 12, the through hole 44 of the trimmer line spool 13 includes a number of non-straight portions 44'. The non-straight portions 44' may also be referred to as bent or curved portions. The non-straight portions 44' may provide space for additional components and arrangements of the trimmer head 1. However, according to further embodiments, the through hole 44 of the trimmer line spool 13 may be straight throughout the entire length of the through hole 44.

[0063] In the above-described loading procedure of the trimmer line 3 onto the trimmer line spool 13, the user may have to align the opening 11 of the housing 12 with the opening of the through hole 44 before inserting the trimmer line 3 into the opening of the through hole 44 of the trimmer line spool 13. However, this can be done in a simple manner, since the housing 12 is free to rotate in a first rotational direction r1 relative to the trimmer line spool 13 as explained above, and the trimmer line spool 13 is free to rotate in a second rotational direction r2 relative to the housing 12. The trimmer head 1 may be provided with one or more markings, such as one or more symbols, arrows, text, etc., indicating one or more rotational positions between the trimmer line spool 13 and the housing 12, where the opening 11 of the housing 12 is aligned with the opening of the through hole 44 of the trimmer line spool 13.

[0064] In the following, with reference to Fig. 10, during one rotation of the housing 12 in a first rotation direction r1 relative to the trimmer line spool 13, the locking latch 18 reaches all stops 16 of the trimmer line spool 13 and displaces between the locked and unlocked positions due to interaction with the inclined surfaces 36 of the stops 16. However, when the housing 12 rotates in a second rotation direction r2 relative to the trimmer line spool 13, the locking latch 18 reaches a stop surface 38 of one of the stops 16, which prevents the housing 12 from further rotating in the second rotation direction r2 relative to the trimmer line spool 13. The interaction between the locking latch 18 and the stops 16 of the trimmer head 1 according to the embodiment shown in Figs. 7 to 12 thus functions as a so-called ratchet mechanism, which allows only one rotation direction of the trimmer line spool 13 relative to the housing 12.

[0065] As can be seen from the above, the trimmer head 1 is configured so that when the trimmer line spool 13 rotates in the second rotational direction r2 relative to the housing 12, the trimmer line 3 is fed into the trimmer line spool 13, and when the trimmer line spool 13 rotates relative to the housing 12 in the first rotational direction r1, the trimmer line 3 is fed out from the trimmer line spool 13.

[0066] According to the embodiments shown in Figures 7 to 12, the locking latch 18 is a pivoting locking latch 18. That is, also in these embodiments, the locking latch 18 is arranged to be pivotable about a pivot axis. The locking latch 18 may be biased towards the locked position by a spring.

[0067] 10, the base plate includes an abutment surface 46 configured to abut against a portion 48 of the locking latch 18. During operation, the rotational speed of the trimmer head 1 increases above the operating speed, thereby increasing the release force F R is the locking force F L4, the movement of the base plate 15 is translated into a movement of the lock latch 18 towards the unlocked position by the abutment contact between the abutment surface 46 of the base plate 15 and the portion 48 of the lock latch 18. In this way, the lock mechanism 14 can be moved to the unlocked position as described with reference to Figures 1 to 6. However, as will be understood from the description herein, when the lock latch 18 is displaced towards the unlocked position by pressing the button 32 or by the inclined surface 36 of the stop 16 of the trimmer line spool 13, the abutment contact between the abutment surface 46 of the base plate 15 and the portion 48 of the lock latch 18 is released so that the lock latch 18 is free to move towards the unlocked position without moving the base plate 15. The trimmer head 1 according to the embodiment shown in Figures 7 to 12 comprises a number of release stops 17. The release stops 17 have similar features and functions as the release stops 17 of the trimmer head 1 described with reference to Figures 1 to 6.

[0068] Those skilled in the art having the benefit of the disclosure set forth in the foregoing description and the associated drawings will have ideas of modifications and other variations of the described embodiments. It is therefore understood that the embodiments are not limited to the specific exemplary embodiments described in this disclosure, and that modifications and other variations are intended to be included within the scope of this disclosure. For example, the locking mechanism may be configured such that the stop and release stop positions change, with the locking latch engaging the outer stop in the locked position. In this case, increasing the rotational speed of the trimmer head to a speed higher than the operating speed causes the movement of the locking latch to move inward to the unlocked position.

[0069] It is also possible to design the locking mechanism so that centrifugal force causes the locking latch to move vertically between the stop and the release stop. Furthermore, even if certain terms are used herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Thus, those skilled in the art will recognize multiple variations to the described embodiments that still fall within the scope of the appended claims. The terms "comprise" or "include" used herein do not exclude the presence of other elements or steps. Furthermore, even if individual features may be included in different claims, they may be advantageously combined, and the inclusion of different claims does not imply that a combination of features is not feasible and / or advantageous. Furthermore, the singular does not exclude a plural.

Claims

1. A rotatable housing (12) connectable to a trimmer line spool (13), the housing (12) rotatably supporting the trimmer line spool (13), and a locking force (F) for locking the trimmer line spool (13) Ｌ a locking mechanism (14) for locking the trimmer head (1) to the housing (12) with a The locking mechanism (14) is arranged to move from a locked position to an unlocked position when the rotational speed of the trimmer head (1) is increased above an operating speed, and the increased rotational speed generates a release force (F Ｒ ) is the locking force (F Ｌ ) and The locking mechanism (114) in the unlocked position allows the trimmer line spool (13) to rotate relative to the housing (12), and the trimmer line (3) wound around the trimmer line spool (13) is released and centrifugal force (F) generated by the rotation of the trimmer head (1) is released. Ｃ ) to release the trimmer line spool (13) from the housing (12) so as to allow the trimmer line (3) to be fed; the trimmer (10) further comprises a drive means for driving the trimmer head (1) in rotation, the trimmer (10) being configured to increase the rotational speed of the trimmer head (1) above the operating speed, thereby moving the trimmer line spool (13) relative to the housing (12); the trimmer (10) is configured to slow the rotational speed of the trimmer head (1) below the operating speed to move the locking mechanism (14) from the unlocked position to the locked position that locks the trimmer line spool (13) to the housing (12); The trimmer (10) is configured to reduce the rotational speed of the trimmer head (1) by alternately reducing and increasing the rotational speed of the trimmer head (1) until the rotational speed of the trimmer head (1) is lower than the operating speed.

2. The lock mechanism (14) is a spring-type lock mechanism, and the center of gravity of the lock mechanism (14) shifts due to an increase in speed, causing the release force (F Ｒ ) is the locking force (F) of the spring-type locking mechanism (14). Ｌ 2. The trimmer (10) of claim 1, wherein the trimmer (10) is greater than 1.

3. The locking mechanism (14) is arranged to return from the unlocked position to the locked position when the rotational speed of the trimmer head (1) decreases below the operating speed, and the release force (F Ｒ ) is reduced and the locking force (F Ｌ 3. The trimmer (10) of claim 1 or 2, wherein the width of the trimmer (10) is smaller than the width of the trimmer (10).

4. 4. The trimmer (10) of claim 1, wherein the locking mechanism (14) comprises a pivoting locking latch (18) and the trimmer line spool (13) comprises one or more stops (16), the pivoting locking latch (18) being positioned to engage one of the one or more stops (16) in the locked position.

5. 5. The trimmer (10) of claim 4, wherein the trimmer line spool (13) further comprises one or more release stops (17), and the pivoting lock latch (18) is positioned to engage one of the one or more release stops (17) when the locking mechanism (14) is moved to the unlocked position.

6. 6. The trimmer (10) of any one of claims 1 to 5, wherein the trimmer head (1) comprises a button (32) disposed on the housing (12), the button (32) being operably connected to the locking mechanism (14) to move the locking mechanism (14) to the unlocked position when the button (32) is pressed.

7. 7. The trimmer (10) of claim 1, wherein the locking mechanism (14) allows manual rotation of the trimmer line spool (13) relative to the housing (12) in one rotational direction (r2).

8. The trimmer (10) according to any one of the preceding claims, wherein the trimmer (10) is configured to reduce the rotational speed of the trimmer head (1) when the rotational speed reaches a maximum rotational speed.

9. A trimmer (10) comprising a trimmer head (1) including a rotatable housing (12) connectable to a trimmer line spool (13), the housing (12) rotatably supporting the trimmer line spool (13), and a locking mechanism (14) locking the trimmer line spool (13) to the housing (12) with a locking force (F L ), the locking mechanism (14) is arranged to move from a locked position to an unlocked position when the rotational speed of the trimmer head (1) is increased above an operating speed, the increased rotational speed causing a release force (F R ) to be greater than the locking force (F L ); The locking mechanism (114) in the unlocked position releases the trimmer line spool (13) from the housing (12) so that the trimmer line (13) can rotate relative to the housing (12) and the trimmer line (3) wound around the trimmer line spool (13) is released and pulled out by centrifugal force (F C ) generated by the rotation of the trimmer head (1), thereby enabling the trimmer line (3) to be supplied; the trimmer (10) further comprises a drive means for driving the trimmer head (1) in rotation, the trimmer (10) being configured to increase the rotational speed of the trimmer head (1) above the operating speed, thereby moving the trimmer line spool (13) relative to the housing (12); the trimmer (10) is configured to slow the rotational speed of the trimmer head (1) below the operating speed to move the locking mechanism (14) from the unlocked position to the locked position that locks the trimmer line spool (13) to the housing (12); The trimmer (10) is configured to reduce the rotational speed of the trimmer head (1) a predetermined time after the rotational speed has increased.

10. 10. The trimmer (10) according to any one of the preceding claims, wherein the trimmer (10) is an electric trimmer (10) and the drive means (2, 4) comprises a power source (4) and an electric motor (2).

11. A method (600) for controlling the supply of a trimmer line (3) in a trimmer (10) having a trimmer head (1) comprising a rotatable housing (12), a trimmer line spool (13) rotatably supported in the housing (12), and a locking mechanism (14) for locking the trimmer line spool (13), the method (600) comprising: and increasing the rotational speed of the trimmer head (1) above an operating speed (620), wherein at the increased rotational speed, the locking mechanism (14) moves from a locked position to an unlocked position, and the trimmer line (3) wound around the trimmer line spool (13) is released and the centrifugal force (F) generated by the rotation of the trimmer head (1) is released. Ｃ ) to allow the supply of the trimmer line (3), The method (600) further comprises the step (640) of slowing down the rotational speed of the trimmer head (1) below the operating speed, whereby the locking mechanism (14) moves from the unlocked position to the locked position; The method (600) further comprises the step (640) of decreasing the rotational speed of the trimmer head (1) by alternatingly decreasing and increasing the rotational speed of the trimmer head (1) until the rotational speed of the trimmer head (1) is lower than the operating speed.

12. 12. The method (600) of claim 11, further comprising the step of decreasing (640) the rotational speed of the trimmer head (1) when the rotational speed reaches a maximum rotational speed.

13. A method (600) for controlling the supply of a trimmer line (3) in a trimmer (10) having a trimmer head (1), the trimmer head (1) having a rotatable housing (12), a trimmer line spool (13) rotatably supported in the housing (12), and a locking mechanism (14) for locking the trimmer line spool (13), the method (600) comprising: The method (600) further comprises a step (620) of increasing the rotational speed of the trimmer head (1) above an operating speed, at which the locking mechanism (14) moves from a locked position to an unlocked position, and the trimmer line (3) wound around the trimmer line spool (13) is released and pulled out by centrifugal force (F C ) generated by the rotation of the trimmer head (1), thereby allowing the trimmer line (3) to be fed; the method (600) further comprises a step (640) of decreasing the rotational speed of the trimmer head (1) below the operating speed, whereby the locking mechanism (14) moves from the unlocked position to the locked position; The method (600) further comprises the step (640) of decreasing the rotational speed of the trimmer head (1) a predetermined time after the increased rotational speed.

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