Chain tensioning device for a chain saw

Abstract

The invention is based on a chain tensioning device for a chain saw, having two hand wheels, in particular two anti-loss mutually held, advantageously mutually bowl-shaped surrounded, preferably configured as outer and inner hand wheels, which are rotatable relative to one another about a common rotation axis, wherein a first hand wheel, in particular the outer hand wheel, of the two hand wheels is provided for the rotation of an eccentric which is configured to displace a stopper which is fixable on a saw blade of the chain saw longitudinally movably relative to a chain wheel of the chain saw which is flush with the saw blade in order to adjust the chain tension of a saw chain of the chain saw, and wherein at least one second hand wheel, in particular the inner hand wheel, of the two hand wheels is provided for fixing the chain tensioning device on the chain saw, in particular by screwing onto a positioning bolt of the chain saw, wherein the chain tensioning device further has a chain wheel cover on which the first hand wheel is lockingly anti-twist, in particular wherein the first hand wheel is anti-loss held on the chain wheel cover.

Description

Technical Field

[0001] This invention relates to a chain tensioning device for chainsaws. Background Technology

[0002] Such chain tensioning devices are known, for example, from EP 1 159 112 B1. Summary of the Invention

[0003] The present invention relates to a chain tensioning device and a chainsaw having such a chain tensioning device.

[0004] This invention is based on a chain tensioning device for a chainsaw, comprising two handwheels, particularly two mutually retaining and advantageously cup-shaped handwheels configured as an outer handwheel and an inner handwheel, which are rotatable relative to each other about a common axis of rotation. The first handwheel, particularly the outer handwheel, is configured for rotating an eccentric wheel, which is designed to longitudinally displace a stop, fixable to the chainsaw blade, relative to a sprocket flush with the chainsaw blade, to adjust the chain tension of the chainsaw chain. At least one second handwheel, particularly the inner handwheel, is configured to secure the chain tensioning device to the chainsaw, particularly by screwing it onto a locating bolt. The chain tensioning device also has a sprocket cover to which the first handwheel is torsionally locked in a form-locking manner, and the first handwheel is retained on the sprocket cover in a way that prevents loss. “Setup” should be understood in particular as specially designed and / or equipped. An object set for a defined function should be understood in particular as the object satisfying and / or implementing the defined function in at least one application and / or operating state.

[0005] It is proposed that the first handwheel can be torsionally coupled to the sprocket cover along the axis of rotation by means of an axially shaped locking connection, particularly by means of at least one axially shaped locking element, preferably an axial tooth segment, which engages with a corresponding axially shaped locking element of the sprocket cover, preferably an axial toothed ring. Advantageously, this provides a chain tensioning device comprising stable and / or less complex and / or fewer components. Advantageously, it enables resistanceless adjustment of the desired chain tension. The chain tensioning device can be fixed in the desired position without over-clamping, especially without over-clamping connectors. This improves operational comfort, avoids wear, and extends the life of the chain tensioning device.

[0006] It is proposed here that the first handwheel, especially at least one axial tooth segment of the first handwheel, can be advantageously fixed by means of the second handwheel, especially by means of the axial stop surface of the second handwheel, by means of the axial stop ring locking relative to the axial shape of the sprocket cover, and the above-mentioned advantages also apply here.

[0007] It is proposed that at least one axial shape-locking element of the first handwheel, preferably at least one axial tooth segment, is axially elastically displaced relative to the axial stop surface of the first handwheel, particularly corresponding to the tooth height dimension of the teeth of at least one axial tooth segment and / or toothed ring. Advantageously, this allows for resistance-free adjustment of the desired chain tension. The chain tensioning device is fixed in the desired position by a non-overlapping snap-fit ​​connector. This allows the chain tensioning device to be opened or released with minimal wear and force, and improves its service life.

[0008] It is proposed that the tooth tip of at least one axial shape locking element of the first handwheel, preferably at least one axial tooth segment, is placed flat relative to the axial sliding surface or moved back from the axial sliding surface in the axially unloaded state, while in the axially loaded state it protrudes beyond the axial sliding surface, particularly with a tooth height almost corresponding to the tooth segment. This also achieves the aforementioned advantages.

[0009] It is proposed that at least one axial shape-locking element of the first handwheel is held by an axially elastically displaceable spring tongue on the first handwheel, wherein the spring tongue has a stop surface on the side opposite to the shape-locking element for the second handwheel, particularly for an axial stop surface, advantageously for an axial stop ring of the second handwheel. This avoids overloading of the axial shape-locking element, particularly the axially elastically displaceable spring tongue.

[0010] It is proposed here that the eccentric wheel has a support device, particularly an axial stop surface, particularly an axial annular surface, which is configured to support the form-locking connection, particularly the corresponding axial form-locking element of the sprocket cover, preferably the axial toothed ring of the sprocket cover, and especially the corresponding axial annular surface of the sprocket cover for supporting the corresponding axial form-locking element, particularly resisting excessive deformation, and particularly resisting over-intervention that would enable the form-locking connection. The deformation-resistant support prevents the chain tensioner from unintentionally loosening during operation, especially under conditions of very high operating and / or working forces when using chainsaws and / or chain tensioners.

[0011] It is proposed here that (in a fixed state) the axial clearance between the support device and the corresponding axial annular surface of the corresponding axial shape locking element of the sprocket cover is slightly smaller than the tooth height of the tooth segment or tooth ring, especially at most half the tooth height, and preferably less than one-fifth of the tooth height. This allows the eccentric wheel to rotate with low resistance. Therefore, chain tension adjustment can be achieved simply and with minimal force.

[0012] It is proposed that the first and second handwheels and sprocket covers are mutually secured to prevent loss, especially as components, and can be removed from the chainsaw; and / or at least the stop and eccentric wheel are mutually secured to prevent loss, especially as components, particularly by means of a sleeve with a shoulder, and can be removed from the chainsaw. This improves operational comfort and makes it difficult to lose components.

[0013] This can improve the safety of chain tensioning devices and / or chainsaws.

[0014] Furthermore, a chainsaw is proposed that includes the aforementioned chain tensioning device. The chainsaw advantageously possesses the aforementioned chain tensioning device, whether assembled or not. Advantageously, this chainsaw allows for resistance-free adjustment of the desired chain tension. The chain tensioning device can be fixed in the desired position on the chainsaw without the need for a handwheel over-clamping mechanism, particularly without an over-clamping connector. This improves operational comfort and safety, while also preventing wear and extending the chainsaw's service life. Attached Figure Description

[0015] Further advantages are illustrated in the following figures. One embodiment is shown in the figures. The figures, description, and claims contain combinations of multiple features. Those skilled in the art will consider each feature individually and summarize them into other meaningful combinations.

[0016] The attached diagram shows:

[0017] Figure 1 A perspective view of the chainsaw according to the present invention;

[0018] Figure 2 : An exploded perspective view of at least the components related to the chain tensioning device according to the invention;

[0019] Figure 3 :according to Figure 2 An exploded side view of a component related to the chain tensioning device according to the invention;

[0020] Figure 4: a) Perspective sectional view of the assembled and unclamped chain tensioning device and b) Side sectional view;

[0021] Figure 5: a) Perspective sectional view of the assembled and clamped chain tensioning device and b) Side sectional view;

[0022] Figure 6 : As in Figure 4b Such an unclamped chain tensioning device, however, relative to Figure 4b A cross-sectional view with a 90° deflection;

[0023] Figure 7: a) A partial view of the chainsaw in the chain tensioner area with the sprocket cover removed and b) Figure 7a Partial cross-sectional view;

[0024] Figure 8: Perspective views of the front and rear sides of the outer handwheel. Detailed Implementation

[0025] Figure 1 A perspective view of a chainsaw 10 is shown, the chainsaw having a housing 12 from which a saw blade 14 protrudes. The saw blade 14 is surrounded by a saw chain 16, which is guided around the saw blade and is simplified as a dashed line. The housing 12 has a handle 18 with a switch 20 for turning on a motor (not shown). Additionally, the chainsaw 10 has an additional handle 17 for guiding the chainsaw 10 and a brake lever 19 for braking and / or quickly shutting off the saw chain drive. The chainsaw 10 has a chain tensioning device 28.

[0026] On the side of housing 12, chainsaw 10 supports sprocket cover 26. Sprocket cover 26 is part of chain tensioning device 28 (see...). Figure 2 -7), where a first (outer) handwheel 36 (see also Figure 8) and a second (inner) handwheel 38 are also visible. The second (inner) handwheel 38 has a gripping tab 39 for tightening and loosening the chain tensioning device 28 without tools. The saw blade 14 has a steering wheel 24 at its blade tip, via which the saw chain 16 is steered. The chainsaw 10 is, for example, electrically powered (its cable is partially visible) and has an electric motor (not referred to in the figures). However, the chainsaw 10 may also be battery-powered or run on fuel as an internal combustion engine. That is, the chainsaw 10 may be driven by an internal combustion engine or an electric motor or have other drive mechanisms. These and, if necessary, additional components and / or elements of the chainsaw are generally known to those skilled in the art.

[0027] A sprocket 22 is mounted below the sprocket cover 26 and on the side of the housing (see...). Figure 2 , 3 and especially Figure 7a , 7b The saw chain 16 can be positioned via the sprocket 22 as follows (see...). Figure 1 This creates a shape-locking connection between the two, and allows the saw chain 16 to be rotatably driven when the sprocket 22 rotates. The saw blade 14 has a groove 1400 on its edge (see, for example, see...). Figure 2The groove holds and guides the saw chain 16 in a form-locking manner on the saw blade 14. The sprocket 22 is advantageously connected to a drive unit (not shown) via a transmission device (not shown) and / or advantageously via a coupler (not shown).

[0028] Figure 2 At least a perspective exploded view of the components and / or parts of the chainsaw 10 associated with the chain tensioning device 28, together with the chain tensioning device 28, is shown. Figure 3 In the exploded side view, they are shown. Figure 4a , 4b Figures 5a and 5b show cross-sectional views of at least assembled components, at least substantially related to the chain tensioning device 28, wherein a) is a perspective view and b) is a side view, wherein the chain tensioning device 28 is in Figure 4a , 4b The middle is loose, while... Figure 5a , 5b It is clamped in the middle. Figure 6 As shown in Figure 4b The chain tensioning device 28 is loosened in that way; however, this cross-section is compared to... Figure 4b The cross-section is shown deflected 90° around the longitudinal axis of the positioning bolt 34 or around the rotation axis 134 of the chain tensioning device 28. Figure 8 shows perspective views of the front and rear sides of the first, or rather, the outer handwheel 36. The combination of multiple figures helps to better understand the invention. Not all components are consecutively numbered in all figures, but repetition of the same components is generally used for better understanding.

[0029] Figure 7a The perspective view shows a portion of the chainsaw 10 in the chain tensioner 28 area with the sprocket cover 26 removed. At least a portion of the housing 12 and saw blade 14, sprocket 22, stop plate 32, positioning bolt 34 or positioning pin, and pawl stop 68 are visible. Furthermore, the shifting unit 130 or eccentric wheel 30 (integrated here) is also present. Figure 7a In the stereoscopic view and in Figure 7b It is visible in the three-dimensional sectional view. The shifting unit 130 or eccentric wheel 30 is in... Figure 7a The observer-facing side has a claw clutch 31 for engaging with the corresponding claw clutch 37 of the first or outer handwheel 36 in a force-transmitting, especially torque-transmitting, but disengaging manner. The direction of rotation for increasing (+) or decreasing (-) chain tension is indicated by arrows along the direction (+) or (-).

[0030] Figure 7b Show Figure 7aA partial cross-sectional view. The section is transverse to the axis of rotation 134, or transverse to the longitudinal extension of the locating bolt passing through the eccentric wheel 30. Similarly, portions of at least one drive shaft (not shown in the figures) of the sprocket 22, the locating bolt 34, and the stop plate 32 are also cut open. The saw blade 14 is held on the side of the housing 12 in the area of ​​its elongated hole 15. To ensure the position of the saw blade, as in... Figure 2 , 3 The protrusion 1681 shown in Figure 6 (formed by a metal part integrally constructed with the chuck stop 68) enters the elongated hole 15. Furthermore, the positioning bolt 34 (which is rotatably and axially fixed in the housing 12 of the chainsaw 10 about / relative to the axis of rotation 134) passes approximately centrally through the elongated hole 15 and extends beyond the saw blade 14 (relative to...). Figure 7b The sleeve 54 (which holds the shifting unit 130, or eccentric wheel 30, and the stop plate 32 together as assembly 540, particularly preventing loss, preferably by means of a radially shouldered end) radially surrounds the positioning bolt 34 and is arranged concentrically with it. The positioning bolt 34 extends along the axis of rotation 134 of the chain tensioning device 28.

[0031] Eccentric wheel 30 according to Figure 7bThe saw blade 14 has a helical winding 290. The longitudinal position of the saw blade 14 can be adjusted relative to the housing 12 in the direction of arrow 100 via the radial stop surface 29 of the eccentric wheel 30 or the helical winding 290. Here, a stop plate 32 arranged between the saw blade 14 and the eccentric wheel 30 serves as a coupling device. The stop plate 32 is supported on the saw blade 14 on one hand by engaging a retaining protrusion 133 protruding from its side, while on the other hand, a support protrusion 33 protruding from its other side abuts against the radial stop surface 29 or the eccentric wheel 30. The support protrusion 33 can be said to be supported on the periphery of the helical profile of the eccentric wheel 30 or the helical winding 290. The position of the stop plate 32 and thus the saw blade 14 can be adjusted by rotating the eccentric wheel 30 about the positioning bolt 34 or the rotation axis 134. Rotation of the eccentric wheel 30 about the axis of rotation 134 or about the positioning bolt 34 causes, for example, a longitudinal movement of the stop surface 32 or the saw blade 14 relative to the sprocket 22 or the housing 12 or relative to the positioning bolt 34 of 5 mm. Because the eccentric wheel 30 has approximately 2 1 / 4 turns (2 1 / 4) of helical winding 290, the saw blade 14 can be adjusted by more than 10 mm in its longitudinal direction using the chain tensioner 28. As further explained below in terms of function, the sprocket cover 26 has a toothed ring 27. This toothed ring here has, exemplarily, ninety teeth on the toothed ring 27 at 360°, thus one tooth is provided on the toothed ring 27 every 4°. Therefore, the chain tensioner 28 or the first handwheel 36 can be fixed relative to the sprocket cover 26 in 4° increments, which corresponds to a longitudinal movement of the radial stop surface 29 of 5 mm divided by 90 teeth, i.e., approximately 56 μm / increment. Therefore, the longitudinal position of the saw blade 14 can be adjusted or fixed in 56μm increments. This is relatively precise. Due to the longitudinal mobility of the saw blade 14 relative to the housing 12, the distance between the saw blade 14 and the sprocket 22 is variable, so that the saw chain 16 can be tensioned more or less.

[0032] exist Figures 2 to 6The image shows, individually or at least in combination, a chain tensioning device 28 for the chainsaw 10 or one chainsaw. The chain tensioning device 28 has two handwheels 36, 38, particularly two handwheels 36, 38 that are anti-loss-preserving, advantageously cup-shaped surrounding each other, preferably configured as an outer handwheel and an inner handwheel 36, 38, which are rotatable relative to each other about a common axis of rotation 134. The first handwheel 36, particularly the outer handwheel 36, is configured for rotation of an eccentric wheel 30, which is longitudinally movably displaced relative to a sprocket 22 of the chainsaw 10 that is flush with the saw blade 14, in order to adjust the chain tension of the chainsaw chain (not shown here). At least one of the two handwheels, the second handwheel 38, particularly the inner handwheel 38, is configured to secure the chain tensioning device 28 to the chainsaw 10, particularly by screwing the second handwheel 38 onto the positioning bolt 34 of the chainsaw 10. Furthermore, the chain tensioning device 28 also has a sprocket cover 26 on which the first handwheel 36 can be torsionally locked in a form-locking manner, particularly wherein the first handwheel is held securely on the sprocket cover 26 to prevent loss, particularly by corresponding form-locking elements 1361, 1270 on the first handwheel 36 and the sprocket cover 26. The first handwheel 36 can be torsionally coupled to the sprocket cover 26 along the direction of the rotation axis 134 by means of an axial form-locking connection 1470, particularly by means of at least one axial form-locking element 147, preferably by means of an axial tooth segment 47, which engages with a corresponding axial form-locking element 127, preferably an axial toothed ring 27, on the sprocket cover 26. Specifically, according to Figure 8, three tooth segments 47 are arranged on the first handwheel 36, staggered by 120° around the axis of rotation 134. These three tooth segments, for example, each have two offset teeth 1472, particularly teeth 1472 arranged circumferentially offset from each other by 4°. The toothed ring 27 (preferably in...) Figure 2 (Clearly visible in the image) It has 90 regularly distributed teeth. One tooth is arranged every 4° in the circumferential direction.

[0033] The first handwheel 36, in particular at least one axial form-locking element 147 or axial tooth segment 47 of the first handwheel 36, can be axially form-locked relative to the sprocket cover 26 by means of the axial stop surface 138 of the second handwheel 36, in particular by means of the axial stop ring 1380.

[0034] At least one axial shape-locking element 147 or at least one axial tooth segment 47 (in these three axial tooth segments 47) of the first handwheel 36 can be axially elastically displaced relative to the axial stop surface 136 of the first handwheel 36, in particular by displacing the tooth height (corresponding to the dimension from tooth root to tooth tip) of the tooth 1472 of at least one axial tooth segment 47 and / or tooth ring 27, or the dimension of the corresponding axial shape-locking elements 147, 127 corresponding to alternating axial projection or retraction. The tooth tip 1471 of at least one axial shape-locking element 147 of the first handwheel 36, preferably at least one axial tooth segment 47, is placed flat relative to the axial sliding surface 1362 or relative to a sliding plane in an axially unloaded state, or is retracted from the axial sliding surface 1362 (while the axial shape-locking element 147 is not engaged). Under axial load (here, by screwing the second or inner handwheel 38 onto the positioning bolt 34 and by axial displacement of at least one tooth segment 47 via the axial stop surface 138), at least one axial shape locking element 147 of the first handwheel 36, preferably at least one tooth tip 1471 of the tooth 1472 of the axial tooth segment 47, protrudes beyond the axial sliding surface 1362, particularly corresponding to the tooth height of the tooth 1472 of the tooth segment 47 and / or corresponding to the tooth height of the tooth ring 27.

[0035] At least one axial form-locking element 147 of the first handwheel 36 is held by a spring tongue or by a spring tongue 46 on the first handwheel 36 that is axially elastically displaceable, wherein the spring tongue 46 has a stop surface 146 on the side opposite to the form-locking element 147 for the second handwheel 38, particularly the axial stop surface 138, advantageously the axial stop ring 1380 of the second handwheel 38. The spring tongue 46 extends circumferentially about the axis of rotation 134. One end of the spring tongue 46 is fixedly connected to the first handwheel 36, and the other end is free and carries the tooth segment 47.

[0036] The eccentric wheel 30 has a support device 1300, particularly an axial stop surface 1301 and a particularly axial annular surface 1302, which are configured to support the shape-locking connection 1470, particularly the corresponding axial shape-locking element 127 of the sprocket cover 26, preferably at least indirectly supporting the axial toothed ring 27 of the sprocket cover 26, particularly the corresponding axial annular surface 1260 of the sprocket cover 26 (for supporting the corresponding axial shape-locking element 127), and particularly resisting excessive deformation, particularly resisting deformable support that can realize the over-interlocking of the shape-locking connection 1470.

[0037] With the chain tensioning device 28 in a fixed state (see...) Figure 5a(b) The axial clearance a between the support device 1300 and the corresponding axial annular surface 1260 of the sprocket cover 26 (used to support the corresponding axial shape-locking element 127 of the sprocket cover 26, especially the toothed ring 27) is a small fraction smaller than the axial height of the corresponding shape-locking element, or the tooth height h of the tooth 1472 of the tooth segment 47 or the toothed ring 27. In particular, the clearance a is at most half the tooth height h of the tooth 1472 of the tooth segment 47 or the toothed ring 27, and preferably less than one-fifth of the tooth height. The distance h2 between the axial stop surface 138 or axial stop ring 1380 of the inner handwheel 38 and the corresponding axial stop surface 136 of the outer handwheel 36 (see...) Figure 5b The value is zero when clamped (see [reference]). Figure 5b In the unclamped state, the spacing h1 (see...) Figure 4b At least corresponding to the tooth height h, the clearance a is the same here.

[0038] The first and second handwheels 36, 38 and the sprocket cover 26 are held together to prevent loss, especially as part 260 (see Figure 2 They are held together to prevent loss and can be removed from the chainsaw 10. At least the stop 32 and the eccentric wheel 30 are held together to prevent loss, especially as component 540 is held together to prevent loss, especially by means of a sleeve 54 preferably with a shoulder, and are held together to be removed from the chainsaw 10.

[0039] Therefore, a chain tensioning device 28 is disclosed for tensioning the saw chain 16 and for securing the saw blade 14 to the housing 12 of the chainsaw 10 in a position that ensures the desired chain tension. The chain tensioning device 28 can be secured to the positioning bolt 34 or the housing 12 by a second or outer handwheel 38. The rotational connection between the outer handwheel 36 and the eccentric wheel 30 is configured as a claw clutch 31, 37. This allows for easy separation and connection, preferably, of the inner and outer handwheels 36, 38, which are configured as an anti-loss assembly 260, together with the sprocket cover 26, and a component 540, which is also configured as an anti-loss assembly. The component 540 is composed, in particular, of the eccentric wheel 30 and the stop plate 32, and is held together by a sleeve 54. It also includes the saw blade 14 secured to the stop plate 32 by means of a screw 64.

[0040] By going clockwise or along according to Figure 1 or Figure 7aRotating the outer handwheel 36 in the (+) direction, together with the eccentric wheel 30, allows the saw blade 14 to move in the direction that increases the distance from the sprocket 22, or towards the saw blade tip, thereby gradually tensioning the saw chain 16 (and vice versa for slack). If the saw chain 16 is substantially against the longitudinal edge of the saw blade 14 (in this state, the saw chain should typically be raised a few millimeters under a tension perpendicular to the longitudinal edge of the saw blade 14, preferably 3-4 mm, to ensure minimal friction on the saw chain 16 while allowing reliable rotation), the rotational resistance on the outer handwheel 36 increases. Afterward, the inner handwheel 38 can be axially tightened towards the housing 12 onto the positioning bolt 34. Here, the inner handwheel axially loads and clamps the saw blade 14 onto the housing 12 in the desired position towards the positioning bolt 34. During tightening, the axial clamping surface 135 of the inner handwheel 38 is pressed against the corresponding clamping surface 131 of the eccentric wheel 30. The axial clamping surface 132 of the eccentric wheel 30 then transmits this pressure to the corresponding clamping surface 1320 of the stop plate 32. The axial clamping surface 1321 of the stop plate 32 then presses against the corresponding clamping surface 140 of the saw blade 14. Finally, the saw blade 14 presses against the clamping plate 168 on the housing side with its axial clamping surface 141 and is thus fixed to the clamping surface 1680 of the clamping plate 168. Thus, when tightening the second, or inner, handwheel 38, the saw blade 14 is at least indirectly fixed to the housing 12 of the chainsaw 10 via the inner handwheel 38.

[0041] Furthermore, when tightening the second or inner handwheel 38, the axial stop surface 138 of the inner handwheel 38 is also pressed towards the corresponding axial stop surface 136 of the first or outer handwheel 36. During tightening, the axial stop surface 138 of the inner handwheel 38 first contacts the axial stop surface 146 of the spring tongue 46 of the outer handwheel 36, or all three axial stop surfaces 146 of the spring tongue 46 of the outer handwheel 36. The spring tongue 46 carries axial tooth segments 47 on the side opposite to the stop surface 146. The axially elastically displaceable spring tongue 46 protrudes towards the axial stop surface 138 of the inner handwheel 38 in the initial state or before it is axially clamped by the inner handwheel 38. Thus, the axial tooth segments 47 have not yet engaged with the corresponding axial tooth ring 27 of the sprocket cover 26, and the axial form-locking connection has not yet been formed. The outer handwheel 36 can thus rotate without resistance and adjust the desired position of the eccentric wheel 30, the longitudinal position of the saw blade 14, or the chain tension so easily. The stop face 146 of the spring tongue 46 protrudes approximately 1-2 mm, particularly approximately 1.4 mm, beyond the stop face 136 in the unloaded state. This roughly corresponds to the tooth height of the tooth 1472 of the tooth segment 47.

[0042] By tightening the inner handwheel 38, the axially elastically displaceable spring tongue 46 is axially displaced, and the toothed segment 47 engages with the corresponding axial toothed ring 27 of the sprocket cover 26. Rotation of the outer handwheel 38 relative to the sprocket cover 26 is now prevented by the mutual engagement of the toothed segment 47 and the toothed ring 27 (see [link]). Figure 5a (b) The axially elastically displaceable spring tongue 46 is pre-tightened toward the inner handwheel 38 or its axial stop surface 138 or axial stop ring 1380, by an axial elastic displacement / clamping amount of 1-2 mm, especially 1.4 mm. This acts anti-torsionally on the inner handwheel 38, almost like an axially pre-tightened safety ring acting on the axial stop surface 138 of the inner handwheel 38. Overextension of the axially elastically displaceable spring tongue 46 of the outer handwheel 36 Overload is eliminated because the inner handwheel 38 not only rests against the spring tongue 46, but also largely rests against the axial stop surface 136 of the outer handwheel 36. This almost completely eliminates overload protection and prevents over-displacement, which can sometimes lead to the breakage of the spring tongue 46. Therefore, the tightening of the inner and / or outer handwheels 36, 38 can be achieved entirely without an over-engagement clutch (as is known in the art), which is sometimes easily worn or the chain tensioner 28 is not sufficiently clamped, for example, because the user's hand force required for over-engagement is insufficient or too small.

[0043] Figures 4a-5b A schematic cross-section of the chainsaw 10 in the area of ​​the chain tensioning device 28 (transverse to the longitudinal direction of the saw blade 14) is shown in the perspective and side views. Figure 6 The longitudinal section (along the longitudinal direction of the saw blade) is shown at a 90° deflection. Figure 4a b and Figure 6 The chain tensioning device 28 is shown in its unclamped state, while Figure 5a Figure b shows the chain tensioning device in the clamped state. A positioning bolt 34 is anchored in the housing 12. This positioning bolt has external threads, through which the remaining chain tensioning device 28 is fixed or clamped to the chainsaw 10. An internally threaded member 35, particularly of metal, is mounted on the inner handwheel 38. This internally threaded member is torsionally and non-dislodged in the inner handwheel 38, which is also made of plastic. The internally threaded member 35 extends circumferentially and axially opposite the gripping tab 39, and the inner handwheel 38 has an axial clamping surface 135 (see Figure b). Figure 3 In particular, the axial stop ring 1380, the inner handwheel 38 extends through the slot 1360 of the outer handwheel 36 (see Figure 8) with the internal threaded part, so as to apply axial clamping force to the corresponding mating clamping surface 131 of the eccentric wheel 30.

[0044] An eccentric wheel 30 with a helical radial stop surface 29 is supported on a support protrusion 33 on the side of a stop plate 32. The stop plate 32 is fixed to the planar side of the saw blade 14 by screws 64. Furthermore, the stop plate 32 engages with an elongated hole 15 in the saw blade 14 with a fixing protrusion 133 protruding toward the side of the saw blade 14 and is supported on the leading edge of the elongated hole. Therefore, as the stop surface 29 of the eccentric wheel 30 rolls relative to the support protrusion 33, the stop plate 32, together with the saw blade 14, moves forward more or less in the longitudinal direction according to the eccentricity of the eccentric wheel 30, thereby causing the saw chain 16 guided by the saw blade 14 to be more or less taut, depending on how the distance between the saw blade 14 and the sprocket 22 changes.

[0045] The outer handwheel 36 is axially secured but rotatably held on the sprocket cover 26. For this purpose, radial locking protrusions 1361 (here, three locking protrusions arranged 120° apart, see especially) Figure 8b The inner handwheel 38 is constructed with a radial ring 1270 (see...). Figure 2 , 3 The corresponding shape-locking device is provided. A radial ring 1270, particularly slightly radially outwardly offset, carries a toothed ring 27. This toothed ring is arranged on the side of the sprocket cover 26 facing the inner and outer handwheels 36, 38. A corresponding axially elastically displaceable tooth segment 47 of the outer handwheel 36 can be form-locked into the toothed ring. This occurs using three axial tooth segments 47 machined at the ends of circumferentially oriented spring tongues 46 into the advantageously cup-shaped, particularly plastic, flat bottom of the outer handwheel 36. Each tooth segment 47 carries an axial tooth portion that engages with and is fixed to the axial teeth of the toothed ring 27. Undesirable over-clamping, especially during chainsaw operation under very large forces, is prevented particularly by providing an axial support ring with an axial annular surface 1260 on the mating side of the axial teeth of the sprocket cover 26 or the toothed ring 27. The axial support ring / axial annular surface is integrally constructed with the sprocket cover 26. The annular surface 1260 is configured to support the corresponding axial annular surface 1302 of the eccentric wheel 30. At least in the unloaded state, a small axial clearance a is provided between the corresponding annular surfaces 1260 and 1302, which is less than the tooth height, especially a small portion of the tooth height, particularly less than 1 mm, preferably about 0.1-0.3 mm. Whenever a large force occurs during the operation of the chainsaw 10 (which may sometimes cause deformation of the sprocket cover 26 and / or the toothed ring 27), axial displacement of the toothed ring 27 away from the tooth segment 47, or axial displacement of the tooth segment 47 away from the toothed ring 27, is substantially prohibited, especially because the axial clearance a is limited to a very small size by the small gap between the corresponding annular surfaces 1260 and 1302, which is preferably significantly smaller than the tooth height of the tooth 1472 of the toothed ring 27 or the corresponding tooth segment 47.

[0046] To replace saw chain 16, turn the inner handwheel 38 in the loosening direction (counterclockwise or along the reference direction). Figure 7a The (-) direction is rotated for such a long time until the internal threaded part 35 is completely disengaged from the locating bolt 34. Once the axial shape-locking connection 1470 is removed, especially between the axial shape-locking element 147 or the axial tooth segment 47 and the corresponding axial shape-locking element 127 or the axial tooth ring 27, the outer handwheel 36 can be rotated counterclockwise to loosen the saw chain 16. Immediately afterwards, the sprocket cover 26, together with the outer handwheel and the inner handwheels 36, 38, can be axially removed from the locating bolt 34, especially as assembly 260. The second assembly 540 can then be separated, and the saw chain 16 can be replaced, maintenance performed, etc.

Claims

1. A chain tensioning device (28) for a chain saw (10) having two hand wheels, which hand wheels can be rotated relative to one another about a common axis of rotation (134), wherein The first hand wheel (36) of the two hand wheels is provided for the rotation of an eccentric (30) which is configured for the longitudinally movable displacement of a stop (32) which is fixed on a saw blade (14) of a chainsaw (10) relative to a chain wheel (22) of the chainsaw (10) which is flush with the saw blade (14) in order to adjust the chain tension of a chain (16) of the chainsaw (10), and wherein at least one second hand wheel (38) of the two hand wheels is provided for fixing the chain tensioning device (28) on the chainsaw (10), wherein the chain tensioning device (28) also has a chain wheel cover (26) on which the first hand wheel (36) can be locked in a form-locked manner against rotation, characterized in that the first hand wheel (36) can be coupled to the chain wheel cover (26) against rotation in the direction of the axis of rotation (134) by means of an axial form-locked connection (1470), wherein the first hand wheel (36) can be coupled against rotation by means of at least one axial form-locked element (147), and wherein the axial form-locked element (147) is an axial toothing (47) which engages into a corresponding axial form-locked element of the chain wheel cover (26), wherein the corresponding axial form-locked element is an axial toothing ring (27), wherein at least one axial toothing (47) of the first hand wheel (36) can be fixed axially form-locked relative to the chain wheel cover (26) by means of an axial stop surface of the second hand wheel (38), and wherein at least one axial form-locked element (147) of the first hand wheel (36) can be displaced axially elastically relative to an axial stop surface of the first hand wheel (36), wherein the axial elastic displacement of the at least one axial form-locked element (147) is limited by the axial stop surface of the second hand wheel (38) resting on the axial stop surface of the first hand wheel (36).

2. Chain tensioning device (28) according to claim 1, characterized in that The two hand wheels are two hand wheels which are held in each case without loss.

3. The chain tensioner (28) of claim 1, wherein, The two hand wheels are two hand wheels which are mutually bowl-shaped.

4. The chain tensioner (28) of claim 1, characterized in that, The two hand wheels are configured as an outer hand wheel and an inner hand wheel.

5. The chain tensioner (28) of claim 1, wherein, The second hand wheel (38) is provided for fixing the chain tensioning device (28) on the chainsaw (10) by screwing onto a set screw (34) of the chainsaw (10).

6. The chain tensioner (28) of claim 1, characterized in that, The first hand wheel (36) is held without loss on the chain wheel cover (26).

7. The chain tensioner (28) of claim 1, wherein At least one axial toothing (47) of the first hand wheel (36) can be fixed axially form-locked relative to the chain wheel cover (26) by means of an axial stop ring (1380) of the second hand wheel (38).

8. Chain tensioning device (28) according to any one of claims 1 to 7, characterized in that At least one axial form-locked element (147) of the first hand wheel (36) can be displaced axially elastically relative to an axial stop surface of the first hand wheel (36) corresponding to the height (H) of the teeth (1472) of the at least one axial toothing (47).

9. Chain tensioning device (28) according to any one of claims 1 to 7, characterized in that At least one axial form-locking element (147) of the first hand wheel (36) lies flush or recedes from an axial sliding surface (1362) of the first hand wheel (36) in an axially unloaded state and protrudes beyond the axial sliding surface (1362) of the first hand wheel (36) in an axially loaded state.

10. Chain tensioning device (28) according to claim 9, characterized in that At least one axial form-locking element (147) of the first hand wheel (36) lies flush or recedes from an axial sliding surface (1362) of the first hand wheel (36) in an axially unloaded state and protrudes beyond the axial sliding surface (1362) of the first hand wheel (36) in an axially loaded state by a tooth height (H) of the teeth (1472) of the axial toothing (47).

11. The chain tensioner (28) of claim 9, characterized in that, A tooth tip (1471) of the teeth (1472) of the at least one axial toothing (47) lies flush or recedes from an axial sliding surface (1362) of the first hand wheel (36) in an axially unloaded state and protrudes beyond the axial sliding surface (1362) of the first hand wheel (36) in an axially loaded state.

12. Chain tensioning device (28) according to claim 11, characterized in that A tooth tip (1471) of the teeth (1472) of the at least one axial toothing (47) lies flush or recedes from an axial sliding surface (1362) of the first hand wheel (36) in an axially unloaded state and protrudes beyond the axial sliding surface (1362) of the first hand wheel (36) in an axially loaded state by a tooth height (H) of the teeth (1472) of the axial toothing (47).

13. Chain tensioning device (28) according to any one of claims 1 to 7 and 10 to 12, characterized in that At least one axial form-locking element (147) of the first hand wheel (36) is held by a spring tongue (46) which is axially elastically displaceable on the first hand wheel (36).

14. The chain tensioner (28) of claim 13, characterized by The spring tongue (46) has a stop face (146) for an axial stop face (1380) of the second hand wheel (38) on a side facing away from the axial form-locking element (147) of the first hand wheel (36).

15. The chain tensioner (28) of claim 13, characterized by, The spring tongue (46) has a stop face (146) for an axial stop face (1380) of the second hand wheel (38) on a side facing away from the axial form-locking element (147) of the first hand wheel (36).

16. The chain tensioner (28) of claim 13, characterized by The spring tongue (46) has a stop face (146) for an axial stop face (1380) of the second hand wheel (38) on a side facing away from the axial form-locking element (147) of the first hand wheel (36).

17. Chain tensioning device (28) according to any one of claims 1 to 7 and 10 to 12 and 14 to 16, characterized in that The eccentric wheel (30) has a support device (1300), wherein the support device (1300) is configured as an axial stop face of the eccentric wheel (30).

18. Chain tensioning device (28) according to claim 17, characterized in that The axial stop face of the eccentric wheel (30) is an axial annular face (1302) of the eccentric wheel (30).

19. Chain tensioning device (28) according to claim 18, characterized in that The axial annular face (1302) of the eccentric wheel (30) is provided for supporting the axial form-locking connection (1470) against overstraining.

20. The chain tensioner (28) of claim 18, characterized by, The axial annulus (1302) of the eccentric (30) is configured to support the axial form-fit connection (1470) against a deformation enabling an over-travel catch of the axial form-fit connection (1470).

21. The chain tensioner (28) of claim 18, characterized by, The axial annulus (1302) of the eccentric (30) is configured to support a corresponding axial form-fit element of the sprocket cover (26).

22. The chain tensioner (28) of claim 18, characterized by, The axial annulus (1302) of the eccentric (30) is configured to support an axial toothing (27) of the sprocket cover (26) to support a corresponding axial form-fit element of the sprocket cover (26).

23. The chain tensioner (28) of claim 18, characterized by, The axial annulus (1302) of the eccentric (30) is configured to support a corresponding axial annulus of the sprocket cover (26) to support a corresponding axial form-fit element of the sprocket cover (26).

24. Chain tensioning device (28) according to claim 23, characterized in that An axial gap (a) between the support means (1300) and a corresponding axial annulus of the sprocket cover (26) to support a corresponding axial form-fit element of the sprocket cover (26) is smaller than a tooth height (H) of the axial toothing (47) or of the teeth (1472) of the axial toothing (27).

25. Chain tensioning device (28) according to claim 24, characterized in that The axial gap (a) is at most half of the tooth height (H).

26. The chain tensioner (28) of claim 24, characterized by The axial gap (a) is smaller than one fifth of the tooth height (H).

27. Chain tensioning device (28) according to any one of claims 1 to 7 and 10 to 12 and 14 to 16 and 18 to 26, characterized in that The first hand wheel (36) and the second hand wheel (38) and the sprocket cover (26) are held against loss to each other and can be removed from the chainsaw (10), and / or at least the stop (32) and the eccentric (30) are held against loss to each other and can be removed from the chainsaw (10).

28. Chain tensioning device (28) according to claim 27, characterized in that The first hand wheel (36) and the second hand wheel (38) and the sprocket cover (26) are held against loss to each other as an assembly and can be removed from the chainsaw (10).

29. Chain tensioning device (28) in accordance with claim 27, characterized in that The stop (32) and the eccentric (30) are held against loss to each other as an assembly and can be removed from the chainsaw (10).

30. Chain tensioning device (28) in accordance with claim 27, characterized in that The stop (32) and the eccentric (30) are held against loss to each other as an assembly (540) by means of a sleeve (54) with a shoulder and can be removed from the chainsaw (10).

31. A chainsaw (10) having a chain tensioning device (28) according to any one of the preceding claims.

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