Sprocket cover of a hand-held chainsaw

Abstract

Sprocket cover of a hand-held chainsaw (1), comprising a sprocket cover (2), a housing (3), at least one stud bolt (4) attached to the housing (3) for screwing the sprocket cover (2) to the housing (3), and at least one nut (5) for screwing onto a free threaded end of the stud bolt (4) of the stud bolt (4) which, in the assembled state, passes through an opening (7) of the sprocket cover (2), wherein the nut (5) is removable and held with sufficient force by at least one magnet (6) of the sprocket cover (2), characterized in that, when the sprocket cover (2) is in the operating position, the nut (5) can be completely released from the stud bolt (4) and held by the magnet (6).

Description

[0001] The invention relates to a sprocket cover of a hand-held chainsaw having the features according to the preamble of claim 1.

[0002] Handheld chainsaws feature a cutting chain that runs around the outside of a guide bar, which has a bar tip at the end facing away from the saw. There, the saw chain is deflected by a movable sprocket. An externally toothed sprocket drives the cutting chain, which is driven by a drive motor via a centrifugal clutch. The outer teeth of the sprocket engage between the links of the cutting chain, driving them.

[0003] The drive shaft of the sprocket is mounted in a housing, usually via a needle bearing of the centrifugal clutch on the crankshaft axis of the chainsaw's drive motor. At least one stud bolt is embedded in the housing for the bolted attachment of the sprocket cover. When installed, this bolt passes through an opening in the sprocket cover. A nut is screwed onto a free threaded end of the stud bolt, which presses the sprocket cover firmly against the housing, thus securing it.

[0004] The cutting chain's guide bar is threaded through a slotted hole on the opposite end of the sprocket sprocket to at least one stud bolt and clamped between the housing and the sprocket cover. Thus, in addition to providing protection against contact, the sprocket cover also serves as a holding device for the guide bar.

[0005] For maintenance work on the guide bar or saw chain, or to replace them, the sprocket cover is released by loosening the retaining nut. Only then can the guide bar be removed or the saw chain replaced.

[0006] Since the nut must be removed from the stud bolt during the disassembly of the sprocket cover, there is an increased risk of the nut becoming lost. Especially at worksites in the forest, lost nuts are difficult or impossible to find in the forest floor. Therefore, the nut must be stored safely until the saw bar and sprocket cover are installed.

[0007] During assembly, the saw chain is first placed on the guide bar, and then the guide bar, including the saw chain, is threaded onto at least one stud. The sprocket cover is then placed on top so that all studs protrude through the opening in the sprocket cover. To complete the assembly, the nut is screwed onto the free threaded section of the stud and tightened, thus securing both the sprocket cover and the guide bar.

[0008] Installing the guide bar and saw chain by the user is difficult, especially in outdoor working conditions. The guide bar with saw chain and the sprocket cover must be held in place while the nut is screwed onto the stud bolt. The nut can fall off and become lost.

[0009] The invention is based on the object of developing a generic sprocket cover in such a way that the fastening process of the sprocket cover is simplified and the fastening nuts are secured during the disassembly or assembly process by means of a suitable holding device.

[0010] This object is achieved by a sprocket cover having the features of claim 1.

[0011] A sprocket cover is proposed in which the nut is held captively on the sprocket cover after its removal. For subsequent sprocket cover installation, the nut can be safely removed and is thus immediately available for assembly.

[0012] The nut is preferably designed as a collar nut. By eliminating the need for a removable washer, the collar of the collar nut creates only low surface pressure on the sprocket cover while still ensuring a strong, friction-locking connection between the sprocket cover and the housing.

[0013] Flange nuts are advantageous in the proposed arrangement in that they have a favorable surface that improves the holding process of the nut on the sprocket cover during disassembly and assembly of the sprocket cover.

[0014] Even in a design with two stud bolts and two nuts, the arrangement according to the invention is suitable for holding both nuts captive.

[0015] Embodiments of the invention are described in more detail below with reference to the figures. They show: In Fig. 1 shows a hand-held, motor-driven chainsaw with a sprocket cover according to the invention. The hand-held chainsaw (1) comprises a housing (3) in which a drive motor (not shown) is arranged. A guide rail (8) is arranged on the side of the housing (3) and projects forward beyond the housing (3) in relation to the normal working position. A cutting chain (9) driven by the drive motor is guided around the outer edge of the guide rail. The chainsaw is carried and guided by hand during operation by means of two handles 10, 11. Fig. 2 shows an exploded view of the arrangement according to Fig. 1 in the area of ​​the sprocket cover (2). The threaded ends of the stud bolts (4) protruding from the housing (3) are shown with the collar nuts (5) already loosened. The holding magnet (6) is shown in the immediate vicinity of the recesses on the sprocket cover for the stud bolts. Fig. 3 shows an exploded view of the arrangement according to Fig. 1 in the area of ​​the sprocket cover (2). The threaded ends of the stud bolts (4) protruding from the housing (3) are shown with the collar nuts (5) already removed and fixed to the holding magnet (6). In this arrangement, the collar nuts (5) are fixed to the sprocket cover (2). In a further assembly step, the sprocket cover (2) with the fixed collar nuts (5) can now be removed from the housing (3). Fig. 4 shows an exploded view of the arrangement according to Fig. 1 in the area of ​​the housing (3) and the sprocket cover (2). The collar nuts (5) fixed to the sprocket cover (2) are captively connected to it. The sprocket cover (2) is separated from the housing (3). The threaded ends of the stud bolts (4) protruding from the housing (3) are now exposed and allow the saw bar (8) to be removed. List of reference symbols: 1 hand-held chainsaw 2 sprocket cover 3 Chainsaw housing 4 studs 5 collar nut 6 Holding magnet 7 Hole in the sprocket cover for the stud bolt 8 saw rail 9 saw chain 10 front handle 11 rear handle

Claims

[1] Chain wheel cover of a hand-held chainsaw (1), comprising a chain wheel cover (2), a housing (3), at least one stud bolt (4) fastened to the housing (3) for screwing the chain wheel cover (2) to the housing (3), and at least one nut (5) for screwing onto a free threaded end of the stud bolt (4) of the stud bolt (4) which, in the assembled state, is guided through an opening (7) of the chain wheel cover (2), wherein the nut (5) is removable and held with sufficient force by at least one magnet (6) of the chain wheel cover (2), characterized by that when the chain wheel cover (2) is in the operating position, the nut (5) can be completely loosened from the stud bolt (4) and held by the magnet (6). [2] Sprocket cover according to claim 1, characterized by that when the sprocket cover (2) is removed in the maintenance position, the nut (5) is completely loosened from the stud bolt (4) and can be held by the magnet (6). [3] Sprocket cover according to claim 1 or 2, characterized by that the placement of the magnet (6) for fixing the nut (5) can be at different positions on the sprocket cover (2). [4] Sprocket cover according to claims 1 to 3, characterized by that several magnets (6) for fixing several nuts (5) can be attached to different positions of the sprocket cover (2). [5] Sprocket cover according to claims 1 to 4, characterized by that the nut (5) is a collar nut.

Images