Portable working device and method for operating such a working device

Abstract

The invention relates to a portable working device, wherein the drive motor (3) drives the saw chain (6) guided in a guide groove of the guide rail (4) in a rotating manner via a drive sprocket (9), wherein the tensioning unit (21) is designed such that, in the released state of the fixing device (10), the spring unit (26) is operatively connected to the guide rail (4) in an unactuated, first position (41) of the tensioning unit (21) for tensioning the saw chain (6), and in an actuated, second position (42) of the tensioning unit (21), the operative connection between the spring unit (26) and the guide rail (4) is prevented by the tensioning unit (21) for releasing the saw chain tension, and wherein the tensioning device (20) comprises an actuating element (22) for actuating the tensioning unit (21) and a connecting shaft (27), wherein the tensioning unit (21) and the actuating element (22) are connected by the connecting shaft (27) are effectively connected to each other.

Description

[0001] The invention relates to a portable working device according to the preamble of claim 1. Furthermore, the invention relates to a method for operating a working device.

[0002] Portable tools are known that comprise a housing and a drive motor arranged within the housing, the drive motor driving a saw chain rotating on a guide bar. Such tools comprise a fixing device for attaching the guide bar to the housing and a tensioning device for tensioning the saw chain. When the fixing device is released, the guide bar can be displaced relative to the housing in the direction of its longitudinal center axis. When the fixing device is released, the saw chain can be tensioned by the tensioning device. The fixing device is then transferred to a fixed state. In this fixed state, the guide bar can no longer be moved relative to the housing. The tool is ready for use. Such a tool can be, for example, a power chainsaw, a pole pruner, or a wood cutter.

[0003] The disadvantage of such tools is the sometimes cumbersome handling of the tensioning device and the associated, imprecise adjustment of the saw chain tension.

[0004] It is therefore an object of the invention to provide a portable working device of the generic type which enables a simple and at the same time reproducible tensioning of the saw chain.

[0005] This object is achieved by a portable working device according to the features of claim 1.

[0006] It is a further object of the invention to provide a method for operating a portable work tool which provides a simple and at the same time reproducible tensioning of the saw chain.

[0007] This object is achieved by a method for operating a portable working device according to the features of claim 11.

[0008] The portable tool according to the invention comprises a housing, a drive motor arranged in the housing, a guide bar with a longitudinal center axis, and a saw chain. The drive motor drives the saw chain, which is guided in a guide groove of the guide bar, via a drive sprocket. Furthermore, the tool comprises a fixing device for fastening the guide bar to the housing and a tensioning device for tensioning the saw chain. In a released state of the fixing device, the guide bar is displaceable relative to the housing in the direction of its longitudinal center axis, and in a fixed state of the fixing device, the guide bar is clamped to the housing.The tensioning device comprises a spring unit and a release unit. The release unit is designed such that, when the fixing device is released, the spring unit is operatively connected to the guide rail in an unactuated, first position of the release unit to tension the saw chain. In an actuated, second position of the release unit, the operative connection between the spring unit and the guide rail is prevented by the release unit to release the saw chain tension. The tensioning device comprises an actuating element for actuating the release unit and a connecting shaft. The release unit and the actuating element are operatively connected to one another by the connecting shaft.

[0009] To tension the saw chain of the implement, the operator must first release the locking device. In this released state, the guide bar can be moved relative to the housing along its longitudinal center axis. If the release unit is now in the unactuated position, the spring unit acts on the guide bar and moves it, so that the saw chain is tensioned. This means that the saw chain is tensioned automatically as soon as the operator has released the locking device. No action by the operator is required. When tensioning the saw chain, the spring unit acts on the guide bar with an essentially reproducible, constant force, so that the saw chain can be repeatedly tensioned with almost the same tension. To complete the tensioning process of the saw chain, the locking device must be returned to a fastened state.The tensioning process of the saw chain of the working device according to the invention described above does not require any further operating operations, thus avoiding incorrect operations when tensioning the saw chain, which can lead to the saw chain being too high or too low in tension.

[0010] Furthermore, the active connection between the spring unit and the guide bar can also be broken by activating the release unit. If the locking device is released, no force acts on the guide bar after activating the release unit. The saw chain is no longer under tension. Maintenance work on the saw chain, guide bar, or other components can now be easily performed. This makes it particularly easy to replace the saw chain and / or guide bar of the implement, for example.

[0011] Since the tensioning device comprises a connecting shaft that operatively connects the actuating element for actuating the unclamping unit and the actuating element, the actuating element is spatially decoupled from the unclamping unit. Thus, the actuating element is arranged in such a way that it offers particularly user-friendly accessibility, at least when the sprocket cover is removed.

[0012] In particular, the actuating element is designed as a pivoting lever. A pivoting lever is easy to operate, especially when wearing protective gloves. The actuating element is preloaded by a spring element, in particular a torsion spring. This preloads the actuating element into its initial position. When the operator operates the actuating element, the necessary effort to overcome the spring force of the spring element appears to be of high quality.

[0013] In particular, it is provided that the actuating element is arranged on the housing in such a way that the actuating element is accessible to the operator when the locking device is released and is concealed by the locking device when the locking device is locked. Accordingly, operation of the actuating element is not possible when the locking device is locked. The operator can only operate the actuating element when the locking device is also released. This prevents incorrect operation of the actuating element.

[0014] In a side view of the tool, the actuating element is located below the guide bar. The guide bar has a bottom and a top side. On the bottom of the guide bar, the saw chain runs towards the drive motor, meaning the saw chain's running direction is towards the drive motor. On the top of the guide bar, the saw chain runs away from the drive motor, meaning the saw chain's running direction is away from the drive motor. If the actuating element is located below the guide bar, in other words, this means that the actuating element is arranged on the housing in such a way that the bottom of the guide bar faces the actuating element and the top of the guide bar faces away from the actuating element.

[0015] In particular, it is provided that the release unit comprises an eccentric. The eccentric is operatively connected to the actuating element, in particular via the connecting shaft.

[0016] In particular, the spring unit acts on a carriage movable in the direction of the longitudinal center axis of the guide rail, wherein the carriage is operatively connected to the guide rail in the direction of the longitudinal center axis. The carriage is connected to the guide rail in such a way that when the carriage moves in the direction of the longitudinal center axis of the guide rail, the carriage moves with it. In particular, a driver pin is formed on the carriage, which engages in an opening in the guide rail. The carriage and the guide rail are connected to one another in the direction of the longitudinal center axis of the guide rail, in particular in a form-fitting manner.

[0017] In particular, it is provided that the eccentric is designed so that it is not in contact with the carriage in the first position of the unclamping unit, and acts directly on the carriage in the second position of the unclamping unit. In particular, the eccentric is designed such that when the unclamping unit is switched from the first position to the second position, the eccentric causes the guide rail to move in the direction of the longitudinal center axis, counteracting a spring force emanating from the spring unit. The spring unit acts in particular on the carriage. In the second position of the unclamping unit, the eccentric acts on the carriage and thus counteracts the spring force of the spring unit. The spring force is neutralized by the eccentric, as a result of which the saw chain is no longer tensioned.

[0018] In particular, the eccentric and the slide are designed in such a way that the eccentric locks onto the slide in the second position of the release unit. Once the eccentric is locked, the operator can easily perform maintenance work on the tool.

[0019] It is particularly intended that a partition be provided between the guide bar and the tensioning device to protect the tensioning device from dirt particles emanating from the saw chain. The partition between the guide bar and the tensioning device prevents the transfer of dirt particles, such as chips, oil, etc., from the saw chain to the tensioning device. The tensioning device is thus protected from contamination, ensuring easy and reliable operation of the tensioning device in the long term.

[0020] In particular, the tool comprises a sprocket cover. The sprocket cover conceals, in particular, a sprocket and parts of the guide bar with the saw chain. The sprocket cover conceals, in particular, the actuating element, at least in sections. To actuate the release unit, the sprocket cover must be detached from the housing of the tool, in particular, completely removed from the housing. The release unit is then actuated by the actuating element from the first position to the second position of the tensioning unit in order to move the guide bar against the spring force of the spring unit, thereby releasing the saw chain. Fig. 1 shows a side view of an embodiment of the portable working device according to the invention, Fig. 2 in a side view from behind the portable working device Fig. 1, Fig. 3 in the side view the portable working device according to Fig. 1 with dismantled sprocket cover, Fig. 4 in a partial, enlarged side view of the working device according to Fig. 1 with actuating element in the unactuated state of the release unit and with guide rail, Fig. 5 in a partial, enlarged side view of the working device according to Fig. 1 with actuating element in the actuated state of the release unit and with guide rail, Fig. 6 in a partial, enlarged side view of the working device according to Fig. 1 with actuating element in actuated state of the release unit without guide rail, Fig. 7 shows a partial, enlarged side view of the working device Fig. 1 with eccentric, connecting shaft and actuating element in actuated state, Fig. 8 shows a partial, enlarged top view of the working device according to Fig. 1 with eccentric, connecting shaft and actuating element in actuated state, Fig. 9 in a partial, enlarged side view of the working device according to Fig. 1 with actuating element in the unactuated state of the unclamping unit without guide rail and Fig. 10 in a partial, enlarged side view of the working device according to Fig. 1 with spring element, guide carriage and eccentric in the unactuated state of the unclamping unit.

[0021] In Fig. 1 shows an embodiment of a working device 1 according to the invention. The portable, in particular hand-carried, working device 1 is designed as a wood cutter in the exemplary embodiment. A wood cutter is a motor-driven working device intended in particular for cutting branches and small woody plants. The preferred use of a wood cutter is, in particular, the limbing of trees. In an alternative embodiment, the working device 1 can also be designed as a chainsaw or the like. In addition, the working device 1 can also be designed as a working device with a shaft, for example, as a pole pruner or the like. The term "portable" is to be understood in such a way that the working device is carried by the operator during its intended use.

[0022] The working device 1 comprises a housing 2. The working device 1 comprises a drive motor 3. The drive motor 3 is in Fig. 1 is shown only schematically by a dashed line. The drive motor 3 is arranged in the housing 2. Furthermore, the working device 1 comprises a tool 6, wherein the tool 6 is driven by the drive motor 3. In the present embodiment, the tool 6 is a saw chain. The saw chain is driven in rotation in a guide groove of a guide rail 4. The drive motor 3 drives a drive sprocket 9 ( Fig. 3), which in turn drives the saw chain 6 to rotate around the guide bar 4. A pivoting hood 18 is arranged on the housing 2. The hood 18 extends over the top of the guide bar 4 and thus also over the tool 6. When sawing through the material with the incoming chain, the hood 18 pivots upward.

[0023] The drive motor 3 is designed as an electric motor in the exemplary embodiment. As in Fig. 1, the working device 1 comprises at least one battery pack 11, 12 for supplying the drive motor 3 with electrical energy. In the preferred embodiment of the working device 1, this comprises a first battery pack 11. The first battery pack 11 is provided for supplying the drive motor 3 with electrical energy. The working device 1 comprises, in particular, a second battery pack 12. The second battery pack 12 is also provided for supplying the drive motor 3 with electrical energy. The working device 1, in particular the drive motor 3 of the working device 1, can in particular also be operated using just one of the two battery packs 11, 12. In the exemplary embodiment, the two battery packs are connected in series. The two battery packs 11, 12 and a rear end 46 of the working device 1 are only shown schematically by dashed lines.In an alternative embodiment of the working device 1, the drive motor 3 can also be designed as an internal combustion engine.

[0024] As in Fig. 2, the guide rail 4 comprises a longitudinal central axis 5. Furthermore, the working device 1 comprises a longitudinal plane 43, which is spanned by the guide groove of the guide rail 4. The longitudinal central axis 5 of the guide rail 4 lies in the longitudinal plane 43. The longitudinal central axis 5 runs centrally through the guide rail 4, whereby the guide rail 4, viewed perpendicular to the longitudinal plane 43 of the guide rail 4, is divided into two approximately equal parts by the longitudinal central axis 5. Furthermore, the guide rail 4 comprises a transverse plane 44. The transverse plane 44 is aligned orthogonally to the longitudinal plane 43 of the guide rail 4. The longitudinal central axis 5 lies in the transverse plane 44.

[0025] As in Fig. 1, the housing 2 of the working device 1 comprises a front end 45 and a rear end 46. The guide rail 4 is fastened to the housing 2 and protrudes from the housing 2 at the front end 45 of the housing 2. The rear end 46 of the housing 2 is formed in the present embodiment by a receiving section 13. The first battery pack 11 and the second battery pack 12 are held on the receiving section 13. The two battery packs 11, 12 are detachably held in the receiving section 13. In an alternative embodiment, the rear end 46 can also be formed by a handle of the working device 1.

[0026] As in Fig. 1, the working device 1 comprises a first handle 47 for supporting a hand of the operator. The first handle 47 is formed on a handle housing 49. The handle housing 49 is part of the housing 2. The working device 1 comprises a control element 50 for actuating the drive motor 3. The control element 50 is assigned to the first handle 47, i.e. during normal operation of the working device 1, the operator actuates the control element 50 with the hand that rests on the first handle 47. The control element 50 is designed in particular as a control lever. The handle 47 is preferably designed such that it can be grasped by the operator with one hand. This allows the operator to hold, in particular carry, the working device 1 by the handle 47.

[0027] As in Fig. 1, the working device 1 comprises a locking element 51, wherein the locking element 51 is designed in particular as a mechanical locking element 51. The locking element 51 is preferably designed as a locking lever. The locking element 51 is designed to lock the control element 50 in a locked position, in particular mechanically, and to release it in an operating position. If the operator wishes to actuate the control element 50, they must first unlock the control element 50 by actuating the locking element 51. The operator can then actuate the control element 50 and control the drive motor 3.

[0028] In addition to the first handle 47, the working device 1 comprises a second handle 48. The second handle 48 serves to support the operator's second hand and enables the operator to better guide the working device 1. The second handle 48 is provided on the housing 2, in particular in the area of ​​the drive motor 3.

[0029] As in Fig. 2, the working device 1 comprises a fixing device 10 for securing the guide rail 4. In a fixed state of the fixing device 10, the guide rail 4 is clamped to the housing 2. In a released state of the fixing device 10, the guide rail 4 is displaceable relative to the housing 2 in the direction of the longitudinal center axis 5. The guide rail 4 can be pushed away from the housing 2 in the direction of its longitudinal center axis 5, whereby the saw chain 6 can be tensioned.

[0030] As in Fig. 2, the working device 1 comprises a sprocket cover 14. The sprocket cover 14 is part of the fixing device 10. In the fixed state of the fixing device 10, the guide rail 4 is clamped between the sprocket cover 14 and the housing 2. A nut 15 is provided for fastening the sprocket cover 14 to the housing 2. The nut 15 is screwed onto a bolt 17 ( Fig. 3 and Fig. 4), which is firmly connected to the housing 2. The nut 15 presses the sprocket cover 14 against the guide rail 4, and the guide rail 4 against the housing 2. The nut 15 includes a pivoting lever 16, which, when in the upright position, serves to rotate the nut 15. Thus, the operator can tighten and loosen the nut 15 without the need for tools. Of course, the sprocket cover 14 covers the sprocket 9 driven by the drive motor 3.

[0031] As particularly in the Fig. 7 and Fig. 8, the working device 1 comprises a tensioning device 20. The tensioning device 20 is designed to tension the saw chain 6. When the fixing device 10 is released, the guide rail 4 is displaceable in the direction of its longitudinal center axis 5 relative to the housing 2. In this state of the fixing device 10, the tensioning device 10 can act on the guide rail 4 such that the guide rail 4 is pushed forward, i.e. in the direction of the longitudinal center axis 5 of the guide rail 4, away from the front end 45 of the housing 2. In the process, the saw chain 6, which rests on the guide rail, is tensioned.

[0032] The tensioning device 20 comprises a spring unit 26, a carriage 23 and a release unit 21. The spring unit 26 is supported at one end on the housing 2 and acts with its other end against the carriage 23. The carriage 23 is held on the housing 2 so that it can move in the direction of the longitudinal center axis 5 of the guide rail 4. The carriage 23 is in particular directly operatively connected to the guide rail 4. For this purpose, the carriage 23 comprises a driver pin 28. The driver pin 28 projects into an opening 29 in the guide rail 4. The driver pin 28 is aligned in its longitudinal direction approximately vertically to the longitudinal plane 43. In the direction of movement of the guide rail 4, the driver pin 28 and the guide rail 4 are positively connected to one another. If the carriage 23 is pushed via the spring unit 26 in the direction of the longitudinal center axis 5 of the guide rail 4, the carriage 23 takes the guide rail 4 with it via the driver pin 28.By driving the guide rail 4, the saw chain 6 is tensioned by means of the spring force of the spring unit 26.

[0033] As particularly in Fig. As shown in Figure 8, in the preferred embodiment, the spring unit 26 is formed from a helical spring. In an alternative embodiment, the spring unit 26 can be formed from a different type of spring and / or from multiple springs. A pin 35 is formed on the carriage 23, on which the spring unit 26, in particular the helical spring, is received.

[0034] The release unit 21 has an unactuated first position 41 and an actuated second position 42. The release unit 21 is designed such that, when the fixing device 10 is released, the spring unit 26 is operatively connected to the guide rail 4 in the first position 41 of the release unit 21 for tensioning the saw chain 6, and in an actuated second position 42 of the release unit 21, the operative connection between the spring unit 26 and the guide rail 4 is prevented by the release unit 21 for releasing the saw chain tension. In the second position 42, the release unit 21 counteracts the spring force of the spring unit 26 and thereby releases the tension of the saw chain 6 by displacing the guide rail 4 backward along the longitudinal center axis 5 of the guide rail 4.

[0035] As in the Fig. 7 and Fig. 8, the clamping device 20 comprises an actuating element 22 for switching the unclamping unit 21 into the first position 41 or into the second position 42. Furthermore, the clamping device 20 comprises a connecting shaft 27. The unclamping unit 21 and the actuating element 22 are operatively connected to one another via the connecting shaft 27. The connecting shaft 27 is rotatably mounted in the housing 2 about an axis of rotation 36. The axis of rotation 36 of the connecting shaft 27 is aligned in particular perpendicular to the transverse plane 44. The connecting shaft 27 extends along its axis of rotation 36 from a first end 37 to a second end 38. The unclamping unit 21 is arranged at the first end 37 of the connecting shaft 27. The actuating element 22 is arranged at the second end 38 of the connecting shaft 27. The unclamping unit 21 and the actuating element 22 are mechanically connected to one another via the connecting shaft 27.The release unit 21, the connecting shaft 27, and the actuating element 22 can be constructed as a single piece, for example, as a cast part, particularly as an injection-molded part, or as a multi-part assembly. If the components are constructed as multi-part components, they are, of course, firmly connected to one another.

[0036] As particularly in the Fig. 7 and Fig. 8, the actuating element 22 is designed as a pivoting lever. The pivoting lever, like the connecting shaft 27, can be pivoted about the rotation axis 36. The tensioning unit 21 also comprises a spring element 25 that is provided for preloading the actuating element 22. The spring element 25 is designed in particular as a torsion spring. The spring element 25 acts on the connecting shaft 27 and / or on the actuating element 22 such that the actuating element 22 is preloaded into the unactuated position 41 of the unclamping unit 21. If the operator wishes to switch the unclamping unit 21 to the second position 42 via the actuating element 22, he or she must overcome not only the spring force of the spring unit 25 but also the spring force of the spring element 25. The spring element 25 is preferably arranged at the second end 38 of the connecting shaft 27 and acts there directly as a torsion spring on the end 38 of the connecting shaft 27.The spring element 25 is supported on the housing 2.

[0037] As particularly in Fig. 8, the unclamping unit 21 comprises an eccentric 24. The eccentric 24 has a contour 39 which is designed such that when the eccentric 24 is pivoted by the actuating element 22 into the actuated position 42 of the unclamping unit 21, the carriage 23 is pushed rearward against the spring force of the spring unit 26. A first active surface 52 is formed on the contour 39 of the eccentric 24, which interacts with the carriage 23, in particular with a second active surface 53 of the carriage 23, when switching to the second position 42. A recess 54 is formed on the second active surface 53 of the carriage 23, in which recess the eccentric 24 latches. For this purpose, a holding contour 55 is formed on the recess 54, which prevents the eccentric 24 from being pivoted back into the unactuated position 41 due to the spring force of the spring element 25.To overcome the holding contour 55, the eccentric 24 must be actively pivoted back by the operator via the actuating element 22. This allows the operator to lock the unclamping unit 21 into the recess 54 of the second active surface 53 of the carriage 23 and, for example, to carry out corresponding maintenance work on the work tool 1 without having to hold the actuating element 22 in the actuated position 42. If the unclamping unit 21 is in the unactuated position 41, as shown in the . Fig. 9 and Fig. 10, the first effective surface 52 of the eccentric 24 and the second effective surface 53 of the carriage 23 do not contact each other as long as the guide rail 4 is tensioned against the saw chain 6.

[0038] As in Fig. 4, the guide rail 4 has a maximum height h, which is measured orthogonally to the transverse plane 44. As shown in Fig. As shown in Figure 7, the connecting shaft 27 has a length l measured in the direction of its rotational axis 36. The length l of the connecting shaft 27 is at least 50% of the maximum height h of the guide rail 4.

[0039] In Fig. Figure 2 shows the running direction 56 of the saw chain 6. On the underside of the guide bar 4, the saw chain 6 runs toward the sprocket, while on the top side of the guide bar 4, the saw chain runs away from the sprocket. The actuating element 22 is located below the guide bar 4, thus facing the underside of the guide bar 4. This makes the actuating element 22 particularly accessible and easy to operate for the operator.

[0040] As in Fig. 8, the working device 1 comprises a partition wall 7. The partition wall 7 is arranged between the guide rail 4 and the tensioning device 20. The partition wall 7 serves to protect the tensioning device 20 from dirt particles emanating from the saw chain 6. The housing 2 defines a housing interior 30. The partition wall 7 divides the housing interior 30 into a first interior 31 of the housing 2 and a second interior 32 of the housing 2. The guide rail 4 is arranged in the first interior 31. The tensioning device 20 is arranged in the second interior 32. The guide rail 4 and the tensioning device 20 are thus spatially decoupled from one another.

[0041] As in Fig. 8, the partition wall 7 comprises an opening 8. The carriage 23 protrudes through the opening 8 of the partition wall 7 with its driver pin 28 for a positive connection to the guide rail 4. The opening 8 is designed as large as necessary to allow the carriage 21 sufficient freedom of movement in the direction of the longitudinal center axis 5 of the guide rail 4 to tension the saw chain 6. In addition, the opening 8 is designed as small as possible to ensure effective protection for the tensioning device 20 against dirt particles emanating from the saw chain 6. The opening 8 is designed, in particular, as an elongated hole.

[0042] As in Fig. As shown in Figure 9, the opening 8 has a length a measured in the direction of the longitudinal center axis 5 of the guide rail 4. The carriage 23, in particular the driver pin 28, has a width b measured in the longitudinal center axis 5 of the guide rail 4. The length a of the opening 8 corresponds to at least 1.5 times, in particular at least 2 times, in particular approximately 2.5 times the width b of the driver pin 28. The opening 8 corresponds to at most 5 times, in particular at most 4 times, in particular at most 3 times the width b of the driver pin 28.

[0043] The operating procedure for working device 1 is described below: To tension the saw chain 6, the nut 15 and thus also the sprocket cover 14 must first be loosened. The locking device 10 is thereby transferred from a fixed state to a released state. If the guide bar 4 is no longer clamped between the housing 2 and the sprocket cover 14, the guide bar 4 is pushed forward via the carriage 23 by the spring force of the spring unit 26. The saw chain 6 is thereby tensioned. If the operator only wishes to tension the saw chain 6, they can now screw the sprocket cover 14 back against the guide bar 4 using the nut 15. The working device 1 is ready for operation again. The unclamping unit 21 is in the deactivated state 41.

[0044] However, if the operator wishes to perform any maintenance work or similar on the implement 1 without tensioning the saw chain 6, the operator must actuate the tensioning unit 21. To do this, the chain wheel cover 14 must first be removed from the housing 2. As shown in Fig. 2, the sprocket cover 14 is arranged on the housing 2 in such a way that it at least partially covers the actuating element 22 of the clamping unit 20, so that the actuating element 22 cannot be pivoted. If the sprocket cover 14 is removed from the housing 2, the operator has access to the actuating element 22, as shown in the Fig. 3 and Fig. 4. The release unit 21 is then in the unactuated position 41, as shown in the Fig. 3, Fig. 4, Fig. 9, Fig. 10. In the unactuated position 41 of the tensioning unit 21, the carriage 23 and the tensioning unit 21 do not contact each other. The saw chain 6 is tensioned.

[0045] As in the Fig. 5 to 8, the actuating element 22 is to be actuated in order to transfer the tensioning unit 21 into the second, actuated position 42. The eccentric 24 acts against the carriage 23, thereby releasing the tension of the saw chain 6. The actuating element 22 is, in particular, to be pivoted open until the tensioning unit 21 latches onto the carriage 23. In this position, the eccentric 24 lies with its first active surface 52 in the recess 54 of the second active surface 53 of the carriage 23 and, in particular, contacts the retaining contour 55 of the recess 54. The operator can carry out maintenance work on the work tool 1 with the saw chain 6 relaxed.

[0046] Once the maintenance work is complete, the operator pivots the actuating element 22 back, moving the tensioning unit 21 from the actuated position 42 to the deactuated position 41. The saw chain 6 is tensioned again. The sprocket cover 14 can then be screwed back onto the guide bar 4 using the nut 15.

Claims

[1] Portable work tool comprising a housing (2), a drive motor (3) arranged in the housing (2), a guide rail (4) with a longitudinal central axis (5) and a saw chain (6), wherein the drive motor (3) drives the saw chain (6) guided in a guide groove of the guide rail (4) via a drive sprocket (9) in a rotating manner, a fixing device (10) for fastening the guide rail (4) to the housing (2) and a tensioning device (20) for tensioning the saw chain (6), wherein in a released state of the fixing device (10) the guide rail (4) is displaceable in the direction of its longitudinal central axis (5) relative to the housing (2) and in a fixed state of the fixing device (10) the guide rail (4) is held clamped to the housing (2), wherein the tensioning device (20) comprises a spring unit (26) and a relaxation unit (21), characterized bythat the tensioning unit (21) is designed such that, in the released state of the fixing device (10), the spring unit (26) is operatively connected to the guide rail (4) for tensioning the saw chain (6) in an unactuated, first position (41) of the tensioning unit (21), and in an actuated, second position (42) of the tensioning unit (21), the operative connection between the spring unit (26) and the guide rail (4) is prevented by the tensioning unit (21) for releasing the saw chain tension, and that the tensioning device (20) comprises an actuating element (22) for actuating the tensioning unit (21) and a connecting shaft (27), wherein the tensioning unit (21) and the actuating element (22) are operatively connected to one another by the connecting shaft (27). [2] Working device according to claim 1, characterized by that the actuating element (22) is designed as a pivoting lever. [3] Working device according to claim 1 or 2, characterized bythat the actuating element (22) is prestressed by a spring element (25), in particular a torsion spring. [4] Working device according to one of claims 1 or 3, characterized by that the actuating element (22) is arranged on the housing (2) in such a way that the actuating element (22) is accessible to the operator when the fixing device (10) is released and is covered by the fixing device when the fixing device (10) is fixed. [5] Working device according to one of claims 1 to 4, characterized by that the actuating element (22) is arranged below the guide rail (4) in a side view of the working device (1). [6] Working device according to one of claims 1 to 5, characterized by that the relaxation unit (21) comprises an eccentric (24). [7] Working device according to one of claims 1 to 6, characterized bythat the spring unit (26) acts on a carriage (23) movable in the direction of the longitudinal center axis (5) of the guide rail (4), wherein the carriage (23) is operatively connected to the guide rail (4) in the direction of the longitudinal center axis (5). [8] Working device according to claim 7, characterized by that the eccentric (24) is designed to be contact-free with the slide (23) in the first position (41) of the unclamping unit (21) and acts directly on the slide in the second position (42) of the unclamping unit (21). [9] Working device according to claim 8, characterized by that the eccentric (24) and the slide (23) are designed such that the eccentric (24) locks onto the slide (23) in the second position (42) of the unclamping unit (21). [10] Working device according to one of claims 1 to 9, characterized bythat a partition wall (7) is provided between the guide rail (4) and the tensioning device (20) to protect the tensioning device (20) from dirt particles emanating from the saw chain (6). [11] Method for operating the working device according to one of claims 1 to 10, comprising the method steps: - Detaching a sprocket cover from the housing (2) of the working device (1) - Actuating the relaxation unit (21) by the actuating element (22) from the first position (41) into the second position (42) of the tensioning unit (20) to move the guide rail (4) against the spring force of the spring unit (26), whereby the saw chain (6) is relaxed.

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