Handheld garden tool for operator-controlled positioning of a blade carrier

Abstract

A handheld garden tool (1) for operator-controlled positioning of a blade carrier, in particular a hedge trimmer or a rotary trimmer, is proposed, comprising at least one reciprocating blade carrier (6, 7), a handle (3) with a throttle lever (5), a drive motor (10) for driving the blade carrier (6, 7) and a control device (9) for controlling a speed (n) of the drive motor (10), wherein the control device (9) is configured to control the speed (n) of the drive motor (10) depending on a selectable positioning mode (PM) of the garden tool, and wherein the speed (n) of the drive motor (10) in the positioning mode (PM) is set to a positioning speed (n).pos) is limited in such a way that the blade carrier (6, 7) is moved back and forth at most twice per second, in particular at most once per second, in positioning mode (PM), so that the position of the blade carrier (6, 7) can be selected by the operator by releasing the throttle lever (5) or a control element (15) of the garden device other than the throttle lever.

Description

[0001] The invention relates to a handheld garden tool designed to position at least one blade carrier in an operator-controlled manner.

[0002] Handheld garden tools, such as hedge shears or rotary shears, have a cutting mechanism for trimming hedges, shrubs, grass, and the like. Typically, such a cutting mechanism consists of several blades mounted on two stacked blade carriers, at least one of which is movable. When the two blade carriers, and with them their blades, are moved relative to each other, two blades from different blade carriers work together in pairs, thus functionally creating multiple shears.

[0003] DE 10 2009 012 181 A1 discloses a hedge shear comprising at least one reciprocating blade carrier, a handle with a throttle lever, a drive motor for driving the blade carrier and a control device for controlling the drive motor.

[0004] However, a disadvantage of previously known cutting devices has been found to be that the blades can wear unevenly along the blade carriers. This can be caused, for example, by an operator only using a portion of the total length or circumference of the blade carriers. Therefore, simply aligning the upper blade carrier with the lower blade carrier once is insufficient for resharpening the blades, as this alignment is not suitable for all areas of the blade carriers due to the varying wear patterns. Instead, the operator must visually inspect the blade carriers and align them so that a first section of the blades can be resharpened, and then realign the blade carriers to allow for the resharpening of a second section of the blades.It is currently neither easy nor reproducible to align the blade carriers in a way desired by the operator. The operator cannot predict the position in which the blade carriers of the garden tool will stop after releasing the throttle lever or any other control. Therefore, many attempts are necessary to randomly obtain a blade carrier position that comes as close as possible to the desired alignment. This makes resharpening time-consuming, and the operator may end up using a blade carrier position for resharpening that does not correspond to the desired alignment.

[0005] The objective is therefore to provide a handheld garden tool for operator-controlled positioning of a blade carrier that overcomes the aforementioned disadvantages. This objective is achieved by the handheld garden tool specified in claim 1.

[0006] According to the invention, the handheld garden tool comprises a control device configured to control the speed of the drive motor depending on a selectable positioning mode of the garden tool, wherein the speed of the drive motor in positioning mode is limited to a positioning speed such that the blade carrier is moved back and forth at most twice per second, in particular at most once per second, in positioning mode.

[0007] Operator-controlled positioning of a blade carrier means that releasing the throttle lever or a control element of the garden tool other than the throttle lever either stops the drive motor via the control unit, or, if the drive motor is already stopped, maintains the standstill, thus preventing the blade carrier from moving. The blade carrier essentially retains the position it was in at the moment the drive motor stopped. The operator therefore selects the position of the blade carrier by determining when to release the throttle lever or the control element other than the throttle lever. If the garden tool has a two-hand control system, the control element other than the throttle lever can be, in particular, another control element of the two-hand control system.

[0008] The handheld garden tool has a working mode in which the operator controls the cutting of hedges, shrubs, grass, and similar vegetation. In working mode, and at full throttle (i.e., with the throttle fully engaged or at 100% throttle), the blade assembly typically moves back and forth at least 40 times per second. This high cutting frequency results in a clean cut. A high cutting frequency is particularly important for trimming, i.e., cutting thin branches, to achieve a good, even cut.

[0009] Because the maximum speed of the drive motor in positioning mode is significantly reduced compared to its maximum speed in working mode—specifically, that the blade carrier is moved back and forth only a maximum of twice, and in particular only once, instead of at least 40 times per second—the maximum speed of the blade carrier is also greatly reduced. This allows the operator to stop the blade carrier much more precisely in a desired position. This is because the movement of the at least one driven blade carrier is much slower in positioning mode than in working mode, making it easier for the operator to visually assess the relative position of both blade carriers and consequently select the stopping point more accurately.Because the rotational speed in positioning mode is significantly reduced compared to the rotational speed in operating mode, the kinetic energy stored in the drive train is also lower. This allows the at least one driven cutter bar to come to a standstill more quickly, particularly immediately, after releasing the throttle lever or any other control element. Since the positioning speed is limited, any overrun of the cutter bar is reproducible and can therefore be taken into account by the operator. In this way, the operator can achieve the desired alignment of the cutter bars relative to each other in fewer attempts, and often in just one.

[0010] The design of a handheld garden tool with at least one reciprocating blade carrier is known to those skilled in the art. A drive motor powers a conversion gearbox, often designed as an eccentric gearbox, to convert the continuous rotation of the drive motor into a reciprocating translational or rotary motion of the blade carrier. The drive motor is typically an electric motor. The drive motor can be a DC motor or an EC motor. In many cases, a reduction gearbox, which can be a planetary gearbox, for example, is arranged between the drive motor and the conversion gearbox to reduce the rated speed provided by the drive motor. Because various gear ratios are known in the prior art, the absolute value of the positioning speed depends on the gearbox of the garden tool.The drive motor can be powered by one or more batteries. It is also possible for the drive motor to be mains-powered.

[0011] By operating the throttle lever, for example by moving or pivoting it, a control device on the garden tool causes the drive motor to operate. The control device may be configured so that it only operates the drive motor if one or more additional conditions are met. One such condition could be an activated two-hand control. An activated two-hand control means that, in addition to the throttle lever, the other control element operated by the second hand is also activated. The control device is specifically designed to detect the operation of the throttle lever and, if present, the other control element. The control device is designed to detect the operation of the throttle lever. The throttle lever can be designed such that it only transmits an activated or deactivated signal to the control device. This can be achieved, for example, via a push-button switch on the throttle lever.The throttle lever can be operated via a control handle. In addition to an engaged or disengaged signal, the throttle lever can also transmit information about its degree of actuation to the control unit. In many cases, the degree of actuation is detected by a potentiometer or a Hall sensor array. The degree of actuation indicates the position of the throttle lever within its operating range, from a fully disengaged state to a fully engaged state. The operating range between the fully disengaged and fully engaged states is 100%. The fully disengaged state corresponds to a degree of actuation of 0%, while the fully engaged state corresponds to a degree of actuation of 100%. Any intermediate position of the throttle lever is assigned a corresponding degree of actuation between 0% and 100%, excluding the extreme positions between 0% and 100%.The garden tool may have additional operating elements, the activation of which is detected by the control unit and taken into account when deciding whether to operate the drive motor and / or select the operating mode. The control unit may be configured to evaluate further operating parameters of the drive motor. The control unit may include a control board, in particular, it may be formed by a control board. The control unit may be configured to be connected, directly or indirectly, to at least one accumulator for supplying power to the drive motor.

[0012] In one embodiment, the control device is configured to activate the positioning mode by actuating the throttle lever, in particular when the control device detects that i) the throttle lever is actuated with a degree of actuation less than or equal to a limit degree of actuation, or ii) the throttle lever has been actuated in an actuation pattern stored in the control device and the throttle lever is actuated within a defined time interval after execution of the actuation pattern, or iii) a control element other than the throttle lever has been actuated, in particular in an actuation pattern stored in the control device, and the throttle lever is actuated thereafter within a defined time interval. The first option i) is only available if the control device can detect intermediate positions of the throttle lever.This can be implemented, for example, using a throttle lever with a potentiometer, a Hall sensor array, or a similar device. The threshold actuation level is stored in the control unit. This threshold is selected from a range of 10% to 50%. A threshold actuation level of, for example, 10% means that the positioning mode is activated by the control unit as long as the throttle lever actuation level is at most 10%. The second option (ii) can also be used if the control unit cannot detect intermediate throttle lever positions. For this purpose, the throttle lever is actuated in a pattern, such as a double-click, and the control unit is configured to recognize this pattern. If the throttle lever is actuated again within the defined time interval, the positioning mode is activated.According to the third option iii), it may also be provided that the control unit is informed, via a control element other than the throttle lever, that the positioning mode should be started, and that this is executed as soon as the throttle lever is actuated within the specified time period after actuating the control element other than the throttle lever. If a two-hand control system is present, the control element other than the throttle lever can be the other control element of the two-hand control system. In particular, the control element other than the throttle lever can be actuated in a specific actuation pattern, and the positioning mode can thus be started when the throttle lever is actuated within the specified time period after executing the actuation pattern.

[0013] In one embodiment, the control device is configured to deactivate the positioning mode when it detects that the throttle lever has been released. The garden tool is designed such that neither the positioning mode nor the operating mode can be active when the throttle lever is not actuated. This ensures that movement of the at least one blade carrier only occurs when the operator initiates this movement by actuating the throttle lever. This makes operating the garden tool particularly simple and intuitive. If a two-hand control system is present, the control device can also be configured to deactivate the positioning mode upon detecting that the other control element of the two-hand control system has been released.

[0014] Because the throttle lever is held continuously in positioning mode, the garden tool can easily switch from positioning mode to working mode by simply applying more throttle. More force corresponds to a greater degree of actuation. Positioning mode can therefore transition directly to working mode. "Directly" in this context means that the drive motor is neither switched off nor does it change its direction of rotation, but simply rotates faster. In one embodiment, the control device is designed to deactivate positioning mode if it detects that the throttle lever actuation has exceeded its limit and / or has increased by at least one limit. This limit is stored in the control device.The limit actuation degree is selected from a range of 10% to 50%. A limit actuation degree of, for example, 10% means that the positioning mode ends when the throttle lever actuation degree exceeds 10%. The limit actuation range is stored in the control unit. The limit actuation range is a segment of the actuation range. The limit actuation range is specifically between 10% and 50% of the actuation range. A limit actuation range of, for example, 20% means that the positioning mode ends when the throttle lever actuation degree changes from, for example, 5% to 25%, i.e., by at least 20% of the throttle lever actuation range. Hysteresis can be used for activation or deactivation.The positioning mode can be deactivated, for example, by activating it when the actuation level is between 1% and 10%, and deactivating it when it exceeds 20%. A slight increase in actuation level of less than 10% will therefore not trigger a transition to working mode. Due to the hysteresis, the throttle lever can be moved slightly beyond the 10% actuation level after activation of the positioning mode without unintentionally starting working mode. Specifically, the garden tool is designed so that it only transitions directly from positioning mode to working mode when the actuation level increases by at least the limit of the actuation range. At the moment the positioning mode transitions to working mode, the positioning mode is deactivated.

[0015] In positioning mode, the thermal load on the drive motor is increased due to reduced cooling capacity. Therefore, positioning mode should only be used temporarily and not continuously. Due to the significantly reduced speed of the at least one driven blade carrier, positioning mode is not intended for cutting plants or similar tasks. Positioning mode is used to precisely move the at least one blade carrier into a relative position to another blade carrier, enabling easy maintenance, particularly sharpening, of the at least one driven blade carrier while it is mounted on the garden tool.In one embodiment, the control device is configured to deactivate the positioning mode if it detects that the positioning time elapsed since the current positioning mode was activated exceeds a maximum positioning time stored in the control device. The maximum positioning time is at most one minute, in particular at most 30 seconds, and most especially at most 15 seconds. The control device may also reduce the maximum positioning time if it determines that, within a defined time range, the sum of all positioning times within that range exceeds a limit value and / or a monitored temperature of the drive motor exceeds a temperature limit value.Once the garden tool has been operated in working mode, particularly for a third holding period, a new time period can begin in which the previous positioning time periods are no longer added together.

[0016] It may be provided that the control device monitors only one of the four aforementioned conditions for deactivating the positioning mode and deactivates the positioning mode as soon as that single condition, in particular releasing the throttle lever, is met. It may be provided that the control device monitors at least two of the four aforementioned conditions for deactivating the positioning mode and deactivates the positioning mode as soon as any one of these conditions is met. It may be provided that the control device monitors at least two of the four aforementioned conditions for deactivating the positioning mode and deactivates the positioning mode as soon as at least two of these conditions are met.

[0017] When the garden tool is in working mode, the maximum permissible speed of the drive motor is usually its rated speed. Depending on the drive motor used, the rated speed is often between 15,000 and 40,000 revolutions per minute. The rated speed can be reduced by a reduction gear, resulting in a reduced speed at the conversion gearbox. Depending on the drive motor and reduction gear used, the conversion gearbox often operates at a reduced speed of between 2,500 and 6,000 revolutions per minute, which corresponds to 40 to 100 revolutions per second. With each revolution of the conversion gearbox, the blade carrier moves back and forth once, i.e., performs a double stroke. Therefore, in working mode, the blade carrier performs 40 to 100 double strokes per second.The term "double stroke" here refers to both a translational back-and-forth movement and a rotational back-and-forth movement. In one embodiment, the control device is designed to control the speed of the drive motor in positioning mode and with the throttle continuously engaged, such that the speed of the drive motor remains within a first speed range, wherein the first speed range extends from zero revolutions per minute up to a positioning speed, where the positioning speed corresponds to at most 2% of the rated speed of the drive motor.

[0018] In positioning mode, the maximum permissible speed of the drive motor is the positioning speed. The positioning speed can, for example, be between 0.5% and 2% of the rated speed of the drive motor. In positioning mode, only a maximum of 0.5% to 2% of the number of double strokes in operating mode are performed per unit of time. Depending on the speed of the conversion gearbox, this equates to a maximum of 0.2 to 0.8 double strokes per second at a gearbox speed of 2,500 revolutions per minute and a maximum of 0.5 to 2 double strokes per second at a gearbox speed of 6,000 revolutions per minute.

[0019] In one embodiment, the control device is designed to maintain the rotational speed of the drive motor at a constant speed, specifically the positioning speed, for an initial holding period during positioning mode. The at least one blade carrier moves back and forth continuously during this initial holding period, albeit at a reduced speed compared to the operating mode. Releasing the throttle lever and / or any other control element can stop the drive motor, and consequently the blade carrier, in its current position.

[0020] Alternatively or additionally, in one embodiment, the control device is configured to alternately control the speed of the drive motor in positioning mode, in particular to increase and decrease it. Specifically, the speed of the drive motor is cyclically set to zero revolutions per minute. The speed can, for example, have a sawtooth waveform. That is, the speed can increase continuously to the positioning speed and then abruptly drop to zero after reaching the positioning speed. The speed can also be maintained for a holding period after reaching the positioning speed before dropping to zero. The drop from the positioning speed to zero can also occur gradually. It can also be provided that the speed has a sinusoidal waveform. The sinusoidal waveform can be around half the positioning speed.It can also be provided that the rotational speed has a sinusoidal curve around zero, meaning that the direction of rotation of the drive motor changes during positioning mode. The cycle of speed increase and decrease repeats as long as the throttle lever is actuated. In one embodiment, the control device is configured to hold the speed at zero for a second holding period after it has dropped to zero, before the speed increases again. The drive motor thus remains stationary for a second holding period cyclically during positioning mode. This second holding period allows the operator to select the position of the knife carrier reached when the drive motor stops, simply by releasing the throttle lever. The second holding period is, in particular, between 0.5 and 2 seconds.Due to the standstill of at least one driven knife carrier, the operator can see the relative alignment of the knife carriers even better and assess even more easily whether this alignment of the knife carrier is suitable for maintenance and should be maintained.

[0021] In one embodiment, the garden tool is designed such that the at least one driven blade carrier stops in a different relative position to the second blade carrier each time the drive motor stops. This offers the operator a choice of different orientations of the blade carriers relative to each other. To achieve this, the number of revolutions of the drive motor within a cycle is matched to the number of revolutions required for a double stroke. Because the drive motor does not rotate exactly as many times or by a multiple of that number between successive stops, i.e., within a cycle, as would be required for a precise back-and-forth movement of the blade carrier, it is prevented that the blade carrier comes to a standstill in the same position each time the drive motor stops.Because the number of revolutions required for a complete back-and-forth movement of the knife carrier is not a multiple of the number of revolutions between successive stops, i.e., within a cycle, the exact position of the knife carrier does not automatically repeat itself after just a few cycles, which would correspond to that multiple. This ensures that numerous different positions of the knife carrier are assigned to each successive stop of the drive motor, from which the operator can select one.

[0022] Further features of the invention will become apparent from the description and the drawing, which shows exemplary embodiments of the invention described in detail below. The drawings show: Fig. 1 A schematic representation of the handheld garden tool according to the invention, here in an exemplary embodiment as hedge shears, Fig. 2 a detailed view in the area of ​​the throttle lever of the handheld garden tool Fig. 1 according to detail Y in Fig. 1, Fig. 3 a first exemplary temporal progression of the degree of actuation of the throttle lever of the handheld garden tool without detectable intermediate states of the throttle lever and the resulting activation or deactivation of positioning mode, working mode and the temporal progression of the rotational speed of the drive motor, Fig. 4 a diagram according to Fig. 3, wherein the control device alternately controls the rotational speed in positioning mode, Fig. 5 a second exemplary temporal progression of the degree of actuation of the throttle lever of the handheld garden tool with detectable intermediate states of the throttle lever and the resulting activation or deactivation of positioning mode, working mode and the temporal progression of the rotational speed of the drive motor, Fig. 6 a diagram according to Fig. 5, wherein the control device alternately controls the rotational speed in positioning mode, Fig. 7 a detailed view of the cutting device of the handheld garden tool Fig. 1 according to detail Z in Fig. 1.

[0023] Fig. Figure 1 shows a handheld garden tool 1 in an exemplary embodiment as a hedge trimmer. The garden tool 1 has a housing 2. A first handle 3 and a second handle 4 are arranged on the housing 2. A throttle lever 5 for indirect control of the drive motor 10 via a control device 9 is arranged on the first handle 3. Another control element 15 can be arranged on the second handle 4, which together with the throttle lever 5 forms a two-hand control. The drive motor 10 is supplied with power via a battery pack 8. The battery pack 8 can be arranged in or on the housing 2 and can be changed without tools. The drive motor 10 rotates about a motor shaft 80 at a speed n. In the exemplary embodiment, the drive motor 10 drives a reduction gear 11, which is designed as a planetary gear. The reduction gear 11 drives a conversion gear.In the exemplary embodiment, the conversion gearbox is designed as an eccentric gearbox, in which an eccentric shaft 20 is driven by the reduction gearbox 11. A first eccentric 21 with a first eccentric axis 81 and a second eccentric 22 with a second eccentric axis 82 are arranged on the eccentric shaft 20, via which a first knife carrier 6 and a second knife carrier 7 are driven back and forth in opposite directions in a known manner. The knife carriers 6, 7 move in opposite directions in a longitudinal direction 85. Alternatively, it can also be provided that the knife carriers 6, 7 are driven via connecting rods that are mounted on the eccentrics 21, 22. It is also possible that only one of the knife carriers 6, 7 is driven.

[0024] The first step 3 is in Fig. Figure 2 shows two different positions of the throttle lever 5, 5'. In the first position, the throttle lever 5 is shown in an unactuated position, i.e., with an actuation degree of 0%. In the second position, the throttle lever 5' is shown in a fully actuated position, i.e., with an actuation degree of 100%, indicated by a dashed line. An actuation range BTS of the throttle lever 5 extends between the unactuated position and the fully actuated position.

[0025] Fig. Figure 3 shows a first exemplary progression of the actuation degree BTG of the throttle lever 5 of the handheld garden tool 1 without detectable intermediate states of the throttle lever 5 and the resulting activation or deactivation of positioning mode PM, working mode AM, and the rotational speed n of the drive motor 10 over time t. The state "0" in the PM(t) or AM(t) diagram denotes a deactivated state. The state "1" in the PM(t) or AM(t) diagram denotes an activated state. Within a first time interval TI from time t.1 to t.3, within a second time interval TII from time t4 to t6, and within a third time interval TIII from time t7 to t11, the throttle lever 5 is continuously actuated, i.e., the actuation degree BTG is consistently 100%. Both the first time interval TI and the third time interval TIII are preceded by an actuation pattern BM of the throttle lever 5.In the exemplary embodiment, the actuation pattern BM is implemented as a double-click at times t.d1, t.d2, and t.d3, t.d4. By actuating the throttle lever 5 again at times t.1 and t.7, respectively, the positioning mode PM is activated and maintained as long as the throttle lever 5 is actuated. The time interval TA between the actuation pattern BM and the subsequent actuation of the throttle lever 5 is, in particular, at most one second. If the throttle lever 5 is actuated after the execution of the actuation pattern BM but only after the time interval TA has elapsed, the operating mode AM is activated. Successive actuations of the throttle lever 5 during the actuation pattern BM are, in particular, at most one second apart, and most specifically at most 0.5 seconds apart. After the actuation pattern BM is detected, the rotational speed n of the drive motor 10 is limited by the control device 9 to a positioning speed n.pos. The positioning speed n.The position speed (pos) is at most 2% of the rated speed (n.nenn) of the drive motor 10. For clarity, the speed profile n(t) is shown in a compressed form in operating mode AM. In positioning mode PM, the control device 9 effectively reduces any positive acceleration of the drive motor 10. This is evident from the flatter rise in the speed curve during the time interval t.1 to t.2 compared to the time interval t.4 to t.5. Once the positioning speed (n.pos) is reached, it is held constant for a holding period, here from t.2 to t.3 or from t.8 to t.10.

[0026] As shown by way of example at time t.10, the positioning mode PM may be terminated by the control unit 9 even if the throttle lever 5 is actuated. This can be triggered if the drive motor 10 has exceeded a temperature above a permissible limit, if the positioning mode PM is active for a positioning time period TP that exceeds a maximum positioning time period stored in the control unit 9, or if the number of revolutions of the drive motor 10 has exceeded a predefined limit. The area under the speed curve corresponds to the number x of revolutions of the drive motor 10 in the considered period. At time t.3, none of these individual termination criteria were met, and the positioning mode PM was terminated by releasing the throttle lever 5. By releasing the throttle lever 5 at time t.3, the operator selected the orientation of the knife carriers 6 relative to each other that existed at that time.

[0027] For the sake of simplicity, the exemplary embodiment describes only that the throttle lever 5 is released. If a two-hand control is present, it may also be provided that the operator releases the other control element 15 of the two-hand control instead of the throttle lever 5 in order to select the position of the at least one blade carrier 6, 7.

[0028] The in Fig. The diagrams shown in 4 essentially correspond to those in Fig. 3, therefore only the differences will be described below, and otherwise the previous description applies. Fig. 3 is referred to. In contrast to Fig. 3 is at Fig. Figure 4 shows an alternating speed profile n(t) controlled by the control unit 9 in positioning mode PM. The speed n assumes values ​​between zero and the positioning speed n.pos. This means that the control unit 9 controls the drive motor 10 in such a way that, in positioning mode PM, the drive motor 10 temporarily stops despite the throttle lever 5 being actuated. As shown, the drive motor 10 can be temporarily switched off at time t.2 or t.8, i.e., immediately after reaching the positioning speed n.pos. Alternatively, it can also be provided that the speed n of the drive motor 10 is kept constant at the positioning speed n.pos for a defined time before the control unit 9 temporarily switches off the drive motor 10.

[0029] The alternating speed profile is specifically designed so that the drive motor 10 completes a defined number of revolutions x between the start of a cycle, here at time t.1, t.7, or t.9, and the end of the cycle, here at time t.2, t.8, or t.11. The area under the speed curve indicates the number of revolutions x of the drive motor 10 in the time interval. The positioning speed n.pos and / or the duration of the cycle are specifically designed so that the number x of revolutions in the cycle does not correspond to a number y of revolutions, or a multiple thereof, that the drive motor 10 requires for exactly one back-and-forth movement of the knife carriers 6, 7. This prevents the knives of the knife carriers 6, 7 from coming to rest in the same relative orientation to each other every time the drive motor 10 stops. The number x can, for example, be set to x=(y / p)+y*f, where 3≤p≤10 and f=[0,1,2,3,4,5] The parameter p must be fixed. It must be at most ten so that the knife carriers 6, 7, and thus the knives, travel a minimum distance in each cycle. The parameter p must be at least three so that the operator is offered several orientations of the knife carriers 6, 7 for resharpening. Alternatively or additionally, the number x of revolutions of the drive motor 10 in the cycle can be adjusted so that the number y is not a multiple of the number x. That is, the parameter p can be a rational number. In this way, the operator is offered more orientations of the knife carriers 6, 7 relative to each other.

[0030] In Fig. At time t.3, the throttle lever 5 is released. Since the time interval between t.3 and t.2 was shorter than the second holding duration TS stored in the control unit 9, the drive motor 10 did not restart in the interim. Releasing the throttle lever 5 at time t.3 ended the positioning mode PM, and the orientation of the knife carriers 6 already achieved at time t.2 was maintained. Releasing the throttle lever 5 at time t.3 allowed the operator to select the orientation of the knife carriers 6. In contrast, the throttle lever 5 was not released during the time interval between t.8 and t.9, and the orientation achieved at time t.8 was therefore not selected.

[0031] The positioning mode PM, which extends from time t.7 to t.11, has a complete cycle from time t.7 to t.8. The rotational speed n is held at zero for a second holding period TS, which extends from time t.8 to t.9, before a new cycle begins at time t.9. Releasing the throttle lever 5 at time t.11 terminates the positioning mode PM before the positioning speed n.pos is reached. In contrast to the rotational speed profile from Fig. 3. The PM positioning mode will be in Fig. 4. Not prematurely terminated by reaching a limit value stored in the control device 9. This is intended to illustrate that, for example, the integral of the speed curve, i.e., the number x of revolutions of the drive motor 10 during the period, can represent a shutdown criterion that, in the speed profile, Fig. 3 was reached in the period t.7 to t.10 and in the speed profile after Fig. 4 was not reached in the period t.7 to t.11.

[0032] The Fig. Figures 5 and 6 show diagrams that are largely the same as those from Fig. 3 and 4 correspond, therefore only the differences are described below, and otherwise reference is made to the previous description of the Fig. 3 and Fig. 4 is referred to. The ones that belong to the Fig. 5 and Fig. The associated embodiment 6 differs from the one relating to the Fig. 3 and Fig. 4. Associated embodiment in that the throttle lever 5 has intermediate states detectable by the control device 9. In this way, activation of the positioning mode PM can now be carried out in accordance with the Fig. 5 and Fig. 6 by actuating the throttle lever 5 with an actuation degree BTG of at most 10%. An actuation pattern BM, as in Fig. 3 and Fig. The steps described in section 3 are therefore unnecessary. Actuation of the throttle lever 5 at time t.1 or t.7 with an actuation degree BTG of 10% activates the positioning mode PM. Because the actuation degree BTG is detectable by the control device 9, a stronger actuation of the throttle lever 5, in particular an increase of at least 10% of the actuation range BTS, allows a direct transition from positioning mode PM to operating mode AM, as shown by way of example at time t.20. The third time interval TIII, in which the throttle lever 5 is continuously actuated, also begins at time t.7 and ends at time t.21. In the third time interval, the positioning mode transitions directly into the operating mode. Fig. In step 5, the rotational speed n increases directly from the already achieved positioning speed n.pos. Fig. At time t.9, 6 started a new alternating speed cycle. At time t.20, the drive motor 10 was still accelerating to positioning speed n.pos and was prompted to accelerate more strongly by the control unit 9 due to the activation of operating mode AM. At time t.21, operating mode AM was deactivated by releasing the throttle lever 5. The increase in speed n is a measure of the acceleration. In all Fig. 3 to 6 it is provided that the drive motor 10 accelerates more slowly in positioning mode PM than in operating mode AM.

[0033] In Fig. 7 is an excerpt from garden tool 1. Fig. Figure 1 schematically illustrates the first knife carrier 6 and the second knife carrier 7. The knife carriers 6 and 7 are shown in exemplary orientations (1) to (7) relative to each other, which are set sequentially in successive cycles at zero speed during alternating control of the rotational speed profile by the control device 9. As can be seen, the number x of revolutions of the drive motor 10 per cycle is adjusted so that it corresponds to only approximately 1 / 6 of the number y of revolutions per double stroke. Therefore, in positioning mode PM, with alternating control, the knife carriers 6 and 7 only perform a displacement c of approximately 1 / 3 of a stroke or approximately 1 / 6 of a double stroke from one stop to the next. The length of a stroke corresponds to the distance a between adjacent knives.The distance a between adjacent knives is twice the eccentricity of the eccentrics 21, 22 when the knife carriers 6, 7 are driven in opposite directions, and once the eccentricity when only one knife carrier 6, 7 is driven. Because the knife carriers 6, 7, and thus the knives, shift by a predefined offset c from one cycle to the next, the operator can see when which orientation is automatically achieved when positioning mode PM is activated. This allows the operator to release the throttle lever 5 when the knife carriers stop in the second orientation and sharpen the back edges 62 of the knives of the first knife carrier 6 and the front edges 71 of the knives of the second knife carrier 6.Upon reactivation of the positioning mode, for example by actuating the throttle lever in operating pattern BM or with an actuation level of up to 10%, the knife carriers move again by an offset c and reach the third orientation upon automatic stop. This allows the operator to resharpen the remaining front edges 61 of the knives of the first knife carrier 6 and the rear edges 72 of the knives of the second knife carrier 6. Fig.Figure 7 shows, by way of example, that the parameter p is chosen as an integer so that the knife carriers 6 and 7 return to their initial orientation after p cycles. This makes it particularly easy for the operator to predict when the knife carriers 6 and 7 will assume a specific orientation relative to each other. However, this also limits the number of possible orientations. Therefore, it may also be possible to choose p as a non-integer to increase the variety of achievable orientations.

[0034] Due to the slow movement of the blade carriers 6, 7 in positioning mode PM, the operator can achieve any desired alignment of the blade carriers 6, 7 relative to each other with just a few attempts by releasing the throttle lever 5. If an alternating rotational speed profile is provided, the blade carriers also stop automatically in incrementally shifted positions, and the operator only needs to release the throttle lever within the second holding period TP when the alignment is satisfactory. The various described embodiments of operator-controlled positioning of at least one driven blade carrier 6 can also be used for garden equipment 1 in which the control device 9 has no information about the position of a rotor of the drive motor 10.

Claims

[1] Handheld garden tool (1) for operator-controlled positioning of a blade carrier, in particular a hedge trimmer or a rotary trimmer, comprising at least one reciprocating blade carrier (6, 7), a handle (3) with a throttle lever (5), a drive motor (10) for driving the blade carrier (6, 7) and a control device (9) for controlling a speed (n) of the drive motor (10), wherein the control device (9) is configured to control the speed (n) of the drive motor (10) depending on a selectable positioning mode (PM) of the garden tool, wherein the speed (n) of the drive motor (10) in the positioning mode (PM) is limited to a positioning speed (n.pos) such that the blade carrier (6, 7) is moved back and forth in the positioning mode (PM) at most twice per second, in particular at most once per second. [2] Handheld garden tool (1) according to the preceding claim, characterized by, that the control device (9) is configured to activate the positioning mode (PM) by actuating the throttle lever (5), in particular when the control device (9) detects that i) the throttle lever (5) is actuated with an actuation degree (BTG) that is less than or equal to a limit actuation degree, or ii) the throttle lever (5) has been actuated in an actuation pattern (BM) stored in the control device (9) and the throttle lever (5) is actuated within a defined time interval (TA) after execution of the actuation pattern (BM), or iii) a control element (15) of the garden device other than the throttle lever (5) has been actuated and the throttle lever (5) is actuated thereafter within a defined time interval. [3] Handheld garden tool (1) according to any one of the preceding claims, characterized by, that the control device (9) is configured to deactivate the positioning mode (PM) when the control device (9) detects that i) the throttle lever (5) has been released or ii) an actuation degree (BTG) of the throttle lever (5) has exceeded a limit actuation degree of the throttle lever or iii) an actuation degree (BTG) of the throttle lever (5) has increased by at least one limit actuation span of the throttle lever (5) or iv) a positioning time span (TP) that has elapsed since an activation of the current positioning mode (PM) is greater than a maximum positioning time span stored in the control device (9). [4] Handheld garden tool (1) according to the immediately preceding claim, characterized by, that the garden device (1) has a working mode (AM), and that the garden device (1) is designed such that it immediately transitions from the positioning mode (PM) to the working mode (AM) when the control device detects that the actuation degree (BTG) of the throttle lever (5) has increased by at least the limit actuation span. [5] Handheld garden tool (1) according to any one of the preceding claims, characterized by , that the control device (9) is configured to control the speed (n) of the drive motor (10) in positioning mode (PM) such that the speed (n) is within a first speed range, wherein the first speed range extends from zero revolutions per minute up to a positioning speed (n.pos), wherein the positioning speed (n.pos) corresponds to at most 2% of a nominal speed (n.nenn) of the drive motor (10). [6] Handheld garden tool (1) according to the immediately preceding claim, characterized by, that the control device (9) is designed to maintain the rotational speed (n) of the drive motor (10) at a constant speed, in particular the positioning speed (n.pos), for a first holding period in positioning mode (PM). [7] Handheld garden tool (1) according to claim 5, characterized by , that the control device (9) is designed to alternately control the speed (n) of the drive motor (10) within the first speed range in positioning mode (PM). [8] Handheld garden tool (1) according to the immediately preceding claim, characterized by , that the control device (9) is designed to cyclically set the rotational speed (n) of the drive motor (10) to zero revolutions per minute in positioning mode (PM). [9] Handheld garden tool (1) according to one of claims 7 to 8, characterized by, that the control device (9) is designed to keep the rotational speed (n) of the drive motor (10) constant at zero revolutions per minute for a second holding period (TS) in positioning mode (PM). [10] Handheld garden tool (1) according to any one of claims 7 to 9, characterized by , that the garden tool (1) is designed such that the drive motor (10) has rotated a number (x) of revolutions between a first stop and an immediately following stop, and the blade carrier (6, 7) requires a number (y) of revolutions of the drive motor (10) for a back-and-forth movement, and wherein the number (x) of revolutions between the stops is not a simple or multiple of the number (y) of revolutions required, and / or ii) wherein the number (y) of revolutions required is not a multiple of the number (x) of revolutions between the stops.

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