Hand-held chainsaw with chain trap
By placing the chain trap at the sprocket cover in a handheld chain saw and using the capture inclined portion and guide inclined portion design, the problem of poor energy absorption when the chain is broken is solved, and the stability of the chain saw is improved and energy absorption capacity reduces the burden on the shell.
Patent Information
- Application Number
- CN202410855455.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-29
- Filing Date
- 2024-06-28
- Publication Date
- 2024-12-31
AI Technical Summary
When the chain trap of existing handheld chain saws breaks, the impact energy is directly introduced into the rigid shell, resulting in high loads and lack of effective energy absorption and deformation, affecting the robustness of the chain trap.
A hand-held chain saw is designed, the chain catcher is placed at the sprocket cover, the free end is adjacent to the abutment surface of the housing, and there is no shape-fitting stop in the longitudinal axis direction, and the capture edge has a resting surface from the abutment surface. The away capture inclined portion increases the deformation ability of the sprocket cover to absorb energy, and improves the robustness of the chain trap by guiding the inclined portion and the position stop portion that matches the shape.
Effectively absorb impact energy, reduce load on the shell, improve the robustness of the chain trap, prevent chain from entering through the gap, enhance chain capture ability and elastic deformation of the sprocket cover, and reduce lateral deformation and offset.
Smart Images
Figure CN119216671A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a handheld chain saw. Background Art
[0002] According to the relevant construction regulations, hand-held chain saws must be provided with suitable protection measures in the event of chain breakage. In the usual construction form, a so-called chain catcher is used for this purpose, which is arranged on the underside of the respective chain saw close to the drive wheel of the chain. Any chain section of the broken chain that moves backwards on the underside of the guide rail in the direction of the housing is caught by the chain catcher. The chain catcher must be designed to be able to absorb the impact energy of such a chain section. When the chain saw is approved, a pendulum impact test is carried out as a supplementary test for chain breakage in order to verify the correct design.
[0003] Different structural forms of such chain catchers are known in the prior art. In one of these structural forms, the chain catcher is directly fastened to the housing. In a variant of these structural forms, the chain catcher is additionally embedded in the receiving portion of the sprocket cover in a form-fitting manner. In other structural forms, the chain catcher is fastened to the sprocket cover, but its free end is also embedded in the corresponding receiving portion of the housing in a form-fitting manner. In the three mentioned cases, the chain catcher itself is firmly supported. However, the impact energy of the impacting chain segment or the impact swing can be directly introduced into the relatively rigid housing, which can cause high loads there due to the lack of flexibility.
[0004] In another known design, on which the present invention is based, the chain catcher is arranged on the sprocket cover, wherein the free end of the chain catcher rests on the contact surface of the housing, but here there is no positive position stop acting in the contact plane. As a result, the impact energy is introduced in particular into the relatively flexible sprocket cover, which reduces the impact by a corresponding deformation. As a result, the housing can be relieved.
[0005] In the absence of a form fit with the housing, deformations due to impacts can lead to the formation of a gap between the free end of the chain catcher and the contact surface of the housing, or an increase in an existing gap. A suitable design ensures that the chain fully outputs its energy to the catching edge of the chain catcher without penetrating into the gap between the chain catcher and the contact surface. Summary of the invention
[0006] The invention is based on the object of developing a chain saw of the generic type in such a way that the design of the chain catch of the chain saw is made more robust.
[0007] This object is achieved by a hand-held chain saw, which comprises: a cutting set, a housing with a lateral contact surface, a sprocket cover and a chain catcher with a catching edge, wherein the chain saw extends in the direction of a longitudinal axis predetermined by the cutting set, wherein the chain catcher is arranged on the sprocket cover, wherein the contact surface spans a contact plane, wherein the chain catcher adjoins the contact surface with a free end without a form-fitting position stop acting backwards in the direction of the longitudinal axis, and wherein the catching edge of the chain catcher has a catching bevel directed away from the contact surface at least in the region of its free end.
[0008] According to the invention, it is provided that the chain catcher adjoins the abutment surface with its free end without a form-fitting position stop acting backwards in the direction of the longitudinal axis, wherein the capture edge of the chain catcher has a capture bevel pointing away from the abutment surface at least in the region of its free end. In particular, the capture bevel is implemented as a concave capture hook. The chain is thereby reliably captured and held in the region of the capture edge of the chain catcher. Greater energy can be applied and an increased deformation of the sprocket cover can be achieved to absorb the energy without the chain being inserted through between the sprocket cover and the housing. By omitting at least a form-fitting connection to the housing backwards, the robustness of the chain catcher is improved.
[0009] In an advantageous refinement, a straight catching edge section at least approximately perpendicular to the contact surface is connected to the catching bevel on the side of the catching bevel facing away from the contact surface. This ensures that no force components acting perpendicular to the contact surface that are worth mentioning occur at this location. Unwanted lateral deformations and deflections are reduced to a minimum.
[0010] In a preferred embodiment, a guide bevel is positioned on the abutment surface of the housing, which at least partially covers the capture bevel of the chain catcher in the direction of the lateral axis of the chain saw. In an advantageous improvement, the guide bevel begins in front of the capture bevel of the chain catcher with respect to the longitudinal axis of the chain saw and extends until behind the capture bevel of the chain catcher. The guide bevel causes the chain to be diverted laterally away from the abutment surface in advance before it hits the chain catcher, thereby achieving an increased lateral safety distance relative to the free end of the chain catcher and supporting the effect of the capture bevel of the chain catcher.
[0011] The chain catcher can be designed as a separate component, but in particular integrally formed on the sprocket cover. In a preferred embodiment, the sprocket cover is made of plastic. While avoiding local pressure peaks, a highly elastic deformation of the sprocket cover with high energy absorption can be achieved, which helps to relieve the remaining structures, in particular in the area of the housing.
[0012] In a suitable development, the sprocket cover has a positive locking mechanism acting at least in the direction of the longitudinal axis next to the chain catcher. In particular, the positive locking mechanism is formed by a pin of the sprocket cover which engages in a corresponding receiving opening of the housing. On the one hand, the deformation potential of the sprocket cover is thus maintained. On the other hand, a precisely positioned connection of the sprocket cover and a reliable introduction of forces into the housing are ensured.
[0013] In an advantageous embodiment, at least one positioning aid is formed on the contact surface of the housing for the chain catcher without a positive position stop acting backward in the direction of the longitudinal axis. The positioning aid allows precise positioning of the sprocket cover during its assembly, but does not significantly impair the elastic deformation and energy absorption of the sprocket cover in the event of a chain break. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings, wherein:
[0015] Figure 1 A chain saw according to the invention is shown in a perspective view, which has a housing, a sprocket cover and a chain catcher which rests loosely against the housing and is provided with a catch bevel which is designed as a catch hook.
[0016] Figure 2 A schematic partial view from below shows the Figure 1 In the case of a chain saw of the type described above, in the area of its sprocket cover and the chain catcher integrally formed on the sprocket cover,
[0017] Figure 3 The enlarged detail view shows the Figure 1 , Figure 2 A variant of the chain saw having a downwardly acting positioning edge for the chain catcher, and
[0018] Figure 4 The enlarged detail view shows the Figure 1 , Figure 2 A further variant of a chain saw has a guide bevel which is formed on a contact surface of the housing and adjoins the chain catcher. DETAILED DESCRIPTION
[0019] Figure 1A hand-held chain saw according to the invention is shown in a perspective view obliquely from the front and below. The chain saw comprises a housing 1, a grip housing 4 and a cutting kit 8. In the illustrated embodiment, the grip housing 4 is vibration-decoupled from the housing 1. Alternatively, the housing 1 and the grip housing 4 can also be implemented in a rigidly connected manner. A rear handle 6 and a front grip bracket 5 are configured and fastened to the grip housing 4. During operation, the chain saw is held and guided by the user's hands at the rear handle 6 and at the front grip bracket 5, respectively. A hand guard 7 is provided in front of the grip bracket 5 in the direction of the cutting kit 9.
[0020] A cutting set 8 is mounted laterally at the front on the housing 1, which includes a guide rail 9 and a saw chain 10 that can be driven to rotate around the guide rail 9. The saw chain 10 is driven by a drive motor in the form of an internal combustion engine, which is also not shown, via a sprocket, which is not shown. Alternatively, an electric motor driven by a mains or battery can also be provided as a drive motor for the saw chain 10. The aforementioned sprocket and the area where the cutting set 8 is fastened to the housing 1 with an associated chain tensioning device are covered by a sprocket cover 3 fastened laterally to the housing 1.
[0021] The guide bar 9 has a flat and generally elongated design with a longitudinal direction. The longitudinal axis x of the chain saw is predetermined by the longitudinal direction of the guide bar 9. The vertical axis z extends perpendicularly to the longitudinal axis x and parallel to the plane of the flat guide bar 9. The lateral axis y extends perpendicularly to the longitudinal axis x and also perpendicularly to the vertical axis z.
[0022] In the present case, the term "front" means the region of the chain saw with the cutting set 8, and the term "rear" means the region of the chain saw with the handle 6, likewise with reference to the direction of the longitudinal axis x. The term "front" in the sense of "pointing forward" or "pointing from the handle 6 to the cutting set 8" results in directional and relative descriptions used here, such as "front" and "front". Similarly, the term "rear" in the sense of "pointing backward" or "pointing from the cutting set 8 to the handle 6" results in directional and relative descriptions used here, such as "rear", "rearward", "rearward".
[0023] The sprocket cover 3 made of flexible plastic is provided with a one-piece formed chain catcher 11 in the region of its lower edge with respect to the vertical axis z. However, the chain catcher 11 can also be implemented as an independent, for example metal component and fastened to the sprocket cover 3 in a suitable manner. Corresponding to the chain catcher 11, the housing 1 has a contact surface 2 for the chain catcher 11. The contact surface 2 extends an imaginary contact plane 13, which is indicated here by a dot-dash line. The contact plane 13 is parallel to the longitudinal axis x and also parallel to the vertical axis z.
[0024] Figure 2The schematic partial view from below shows the Figure 1 The situation of the chain saw in the area of its sprocket cover 3. By using Figure 1 It can be seen from the overview that the chain catcher 11 formed on the sprocket cover 3 with its free end 14 abuts the abutment surface 2 without a positive locking stop acting backwards in the direction of the longitudinal axis x and in particular without an overall positive locking stop acting in the abutment plane 13. In other words, the chain catcher only rests loosely on the abutment surface 2. Direct contact does not necessarily have to exist. It can also be sufficient if there is a narrow gap between the free end 14 of the chain catcher 11 and the abutment surface 2 of the housing 1.
[0025] In particular, a positive position stop in the direction of the longitudinal axis x in the rearward direction refers to a positive fit which, under the influence of an impacting broken chain, at least blocks a position change of the relevant component in the rearward direction and, in other words, absorbs the corresponding impact energy. The lack of such a positive position stop of the chain catcher 11 at the abutment surface 2 provided according to the invention thus means that the chain catcher 11 is not supported at least in a direct positive manner in the rearward direction on the housing 1 or the abutment surface 2, and can then be unhindered to at least bounce or shift in the rearward direction under the influence of an impacting chain and thereby deform the sprocket cover 3. This excludes corresponding energy-absorbing support measures that act directly on the chain catcher 11. In particular, it is excluded that the free end 14 of the chain catcher 11 is inserted, for example, into a corresponding receiving opening of the abutment surface 2.
[0026] A chain catcher 11 is provided with a plurality of chain guides extending in the direction of the longitudinal axis x toward the cutting set 8 ( Figure 1 ) is directed toward the catching edge 12, which is used to strike a chain section of the saw chain 10 that may break. The catching edge 12 has a catching bevel 15 that is directed away from the abutment surface 2 or is inclined away. In other words, in the drawing plane spanned by the longitudinal axis x and the lateral axis y, the edge normal direction 20 perpendicular to the catching bevel 15 and the surface normal direction 21 perpendicular to the abutment surface 2 enclose an angle of <90°, so that the edge normal direction 20 is away from the abutment surface 2 in the direction of the lateral axis y and forward in the direction of the longitudinal axis x, that is, away from the rear handle 6 and towards the cutting set 8 ( Figure 1 ) points to.
[0027] The catching bevel 15 can extend over the entire length of the catching edge 12 and thus form the catching edge 12 as a whole. In the embodiment shown, the catching bevel extends only in the region of the free end 14 of the chain catcher, wherein on the side of the catching bevel 15 facing away from the abutment surface 2, a straight catching edge section 16 at least approximately perpendicular to the abutment surface 2 is connected to the catching bevel. The catching bevel 15 can extend in a straight line or in another suitable manner. In the preferred embodiment shown, the catching bevel is implemented as a concave catching hook, which has a straight and concavely curved edge section.
[0028] In addition Figure 2 It can also be seen that the sprocket cover 3 has a positive locking stop 23 next to the chain catcher 11 and at a distance from the chain catcher, which acts at least in the direction of the longitudinal axis x or acts in all directions against the plane 13. The positive locking stop 23 is located behind the chain catcher 11 with respect to the longitudinal axis x. In the embodiment shown, a pin 18 is formed on the sprocket cover 3 for this purpose, which engages in a corresponding receiving opening 19 of the housing 1, which is only schematically indicated here.
[0029] Figure 3 The enlarged detail view shows the Figure 1 , Figure 2 In this embodiment, a positioning edge 22 is formed on the lateral contact surface 2 below the free end 14 of the chain catcher 11, against which the free end rests loosely. However, this does not involve form-fitting position stops such as pins 18 and receiving openings 19 ( Figure 2 The positioning edge 22 protrudes only slightly beyond the contact surface 2 so that in the event of a simulated or actual chain break, without a significant local introduction of forces into the housing 1, the chain catcher 11 can at least perform a largely unhindered deformation movement to the rear.
[0030] Figure 4 The enlarged detail view shows the Figure 1 , Figure 2Another variant of the chain saw. In this embodiment, a guide bevel 17 is constructed at the lateral abutment surface 2 below the free end 14 of the chain catcher 11, which is raised above the abutment surface 2 from its front end with respect to the longitudinal axis x at a height that increases rearwards, and then passes under the chain catcher 11 until it extends at least to the rear of the catching bevel 15 of the chain catcher. Currently, the guide bevel even extends to the rear of the entire chain catcher 11. In the direction of the lateral axis y, the catching bevel 15 of the chain catcher 11 is at least partially covered by the guide bevel 17 or extends beyond it. A position stop with a shape fit as specified above is also not involved here. As shown in the positioning edge 22 ( Figure 3 ), the guide bevel also projects only slightly beyond the contact surface 2 so that in the event of a simulated or actual chain break, without a significant local introduction of forces into the housing 1, the chain catcher 11 can at least perform a deformation movement to the rear that is somewhat unhindered. Alternatively, the guide bevel 17 can also be arranged above the chain catcher 11. The guide bevel 17 can also be arranged at the same height as the chain catcher 11, wherein the guide bevel then preferably ends directly in front of the chain catcher 11.
[0031] In terms of the remaining features and reference numerals, Figure 3 , Figure 4 The embodiments are consistent with each other and with Figure 1 , Figure 2 The same as the embodiment of .
Claims
1. A hand-held chain saw comprising: A cutting set (8), a housing (1) with a lateral abutment surface (2), a sprocket cover (3) and a chain catcher (11) with a catching edge (12), wherein the chain saw extends in the direction of a longitudinal axis (x) predetermined by the cutting set (8), wherein the chain catcher (11) is arranged on the sprocket cover (3), wherein the abutment surface (2) spans a abutment plane (13), and wherein, in the absence of a positive locking stop acting backwards in the direction of the longitudinal axis (x), the chain catcher (11) adjoins the abutment surface (2) with a free end (14), It is characterized in that The catch edge (12) of the chain catcher (11) has, at least in the region of its free end (14), a catch bevel (15) pointing away from the contact surface (2).
2. The handheld chain saw according to claim 1, It is characterized in that The catch bevel (15) is implemented as a concave catch hook.
3. The handheld chain saw according to claim 1, It is characterized in that A straight catching edge section (16) perpendicular to the abutment surface (2) is connected to the catching bevel (15) on the side facing away from the abutment surface (2).
4. The hand-held chain saw according to claim 1, It is characterized in that A guiding inclined portion (17) is positioned on the abutment surface (2) of the housing (1), and at least partially covers the catching inclined portion (15) of the chain catcher (11) in the direction of the lateral axis (y) of the chain saw.
5. The hand-held chain saw according to claim 4, It is characterized in that The guide bevel (17) starts in front of the catching bevel (15) of the chain catcher (11) with respect to the longitudinal axis (x) of the chain saw and extends until behind the catching bevel (15) of the chain catcher (11).
6. The hand-held chain saw according to claim 1, It is characterized in that The chain catcher (11) is integrally formed on the sprocket cover (3).
7. The hand-held chain saw according to claim 1, It is characterized in that The sprocket cover (3) is made of plastic.
8. The hand-held chain saw according to claim 1, It is characterized in that The sprocket cover (3) has, next to the chain catcher (11), a positive locking stop (23) which acts at least rearwardly in the direction of the longitudinal axis (x).
9. The hand-held chain saw according to claim 8, It is characterized in that The positive-locking position stop (23) is formed by a pin (18) of the sprocket cover (3) which engages in a corresponding receiving opening (19) of the housing (1).
10. The hand-held chain saw according to claim 1, It is characterized in that For the chain catcher (11), at least one positioning aid (22) is formed on the contact surface (2) of the housing (1), without a positive locking stop acting rearwardly in the direction of the longitudinal axis (x).