Captively Mounted Nut for Chain Saw Bar Attachment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chain saw tightening arrangements are prone to nut loss during detachment, especially in forest environments, and existing solutions either make the process cumbersome or complicate the mounting of the cover portion to the body.
Innovation Solution
The proposed arrangement features a cover portion with a recess and through aperture that captively attaches the nut, allowing for a certain play in the nut's rotation axis, enabling easier assembly and disassembly by allowing the nut to be attached to the cover portion while maintaining a larger movement range, facilitating correct mounting and reducing the risk of nut loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nut is disposed in the interior of the cover, then the nut cannot be lost when detaching the cover, but the cover cannot be pressed towards the body to hold the guide bar in position before threading the nut and bolt
Solution Approach 1:
The nut is nested within the cover interior, captured by a recess that allows the nut to move axially while preventing lateral displacement. This nesting arrangement ensures the nut cannot be lost during detachment while still allowing proper assembly sequence.
Solution Approach 2:
The nut is designed with dynamic movement capability along the engagement portion, allowing it to move a second distance (B) when not engaged, which is larger than the first distance (A) required for securing. This dynamic range enables the cover to be pressed towards the body to hold the guide bar in position before threading the nut and bolt.
2Strength
If two bar bolts are used to strengthen the mounting for large chain saws, then the mounting is strengthened, but the operator has to unthread the nuts alternately which makes detaching the cover tedious
Solution Approach 1:
The tightening arrangement is segmented into multiple independent bolt-nut pairs, each with its own nut captured in the cover. This segmentation allows each nut to be loosened and removed independently without interfering with other nuts, enabling sequential detachment rather than alternating unthreading.
3Reliability
If the nut is captively attached to the cover portion, then the nut cannot be lost, but the movement range of the nut is restricted
Solution Approach 1:
The nut is nested within the cover with a recess that provides axial play while preventing lateral escape. The recess dimensions are designed to allow the nut to move the required first distance (A) for securing and second distance (B) for assembly operations, while capturing the nut to prevent loss.
Data Source
Figure 1
AI summary
The invention relates to an arrangement for attaching a bar (1) of a hand-held motor driven tool, such as a chain saw, to a body (2) of the tool, the arrangement comprising: at least one bolt (3), having a first part (3a), securely arranged to the body (2), and a second part (3b) extending from the body, the second part having an engagement portion (3c) for engaging a nut (5, 15); a cover portion (4, 14) adapted to bear against a bar (1) such that the bar is arranged between the cover portion (4, 14) and the body (2); and at least one nut (5, 15), captively attached to the cover portion (4, 14). The nut is adapted to engage the engagement portion (3c) of the bolt (3) for securing a bar (1) between the cover portion (4, 14) and the body (2), the nut (5, 15) having a rotation axis (X). The nut is also arranged to move a first distance (A) along the engagement portion (3c) of the bolt (3), in a direction of its rotation axis (X), for securing a bar (1) between the cover portion (4, 14) and the body (2). When the bolt (3) and the nut (5, 15) are not engaged, the nut (5, 15) is captively attached to the cover portion (4, 14) in such a way that it is movable a second distance (B) relative the cover portion (4, 14) in a direction of its rotation axis (X), wherein the second distance (B) is larger than the first distance (A).Thereby, an attachment arrangement is achieved that facilitates changing of bars when the nut used in the attachment arrangement is captively arranged to the cover portion.