U.S. patent application number 14/144392 was filed with the patent office on 2014-04-24 for attaching arrangement for hand-held motor-driven tools.
This patent application is currently assigned to HUSQVARNA AB. The applicant listed for this patent is HUSQVARNA AB. Invention is credited to Par MARTINSSON.
Application Number | 20140109416 14/144392 |
Document ID | / |
Family ID | 40549380 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140109416 |
Kind Code |
A1 |
MARTINSSON; Par |
April 24, 2014 |
ATTACHING ARRANGEMENT FOR HAND-HELD MOTOR-DRIVEN TOOLS
Abstract
The invention relates to an arrangement for attaching a bar of a
hand-held motor driven tool to a body of the tool, the arrangement
including: at least one bolt, having a first part, securely
arranged to the body, and a second part extending from the body,
the second part having an engagement portion for engaging a nut; a
cover portion adapted to bear against a bar such that the bar is
arranged between the cover portion and the body; and at least one
nut, captively attached to the cover portion. The nut is adapted to
engage the engagement portion of the bolt for securing a bar
between the cover portion and the body, the nut having a rotation
axis. 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.
Inventors: |
MARTINSSON; Par; (Jonkoping,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HUSQVARNA AB |
Huskvarna |
|
SE |
|
|
Assignee: |
HUSQVARNA AB
Huskvarna
SE
|
Family ID: |
40549380 |
Appl. No.: |
14/144392 |
Filed: |
December 30, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12682765 |
May 25, 2010 |
8615889 |
|
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PCT/SE2007/000895 |
Oct 12, 2007 |
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14144392 |
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Current U.S.
Class: |
30/383 |
Current CPC
Class: |
B27B 17/14 20130101;
B27B 17/02 20130101; F16B 37/043 20130101; F16B 41/002 20130101;
F16B 5/02 20130101; Y10T 403/18 20150115 |
Class at
Publication: |
30/383 |
International
Class: |
B27B 17/02 20060101
B27B017/02 |
Claims
1-19. (canceled)
20. An arrangement for attaching a cover to a bar of a saw, the
arrangement comprising: at least one first engagement device,
having a first part and a second part, the second part having an
engagement portion for engaging at least one second engagement
device; a cover portion adapted to bear against a bar; the at least
one second engagement device, captively attached to the cover
portion, wherein the second engagement device is adapted to engage
the engagement portion of the first engagement device for securing
the cover portion to the bar, the second engagement device having a
rotation axis; wherein the second engagement device is arranged to
move a first distance along the engagement portion of the first
engagement device, in a direction of the rotation axis of the
second engagement device; when the first and second engagement
device are not engaged, the second engagement device is captively
attached to the cover portion in such a way that it is movable a
second distance relative the cover portion in a direction of the
rotation axis of the second engagement device, wherein the second
distance is larger than the first distance, wherein the cover
portion has an inner surface that, when the cover portion is
arranged to the bar, is directed towards the bar, and an outer
surface that, when the cover portion is arranged to the bar, is
directed away from the bar, the cover portion further having a
through aperture extending between the inner and outer surfaces for
receiving the second part of the first engagement device, the cover
portion further comprising at least one receiving portion in which
an attaching portion of the second engagement device is arranged
for captively attaching the second engagement device to the cover
portion and the at least one portion is arranged separately from
the through aperture.
21. The arrangement as recited in claim 20, wherein the first part
of the at least one first engagement device is securely arranged to
a body.
22. The arrangement as recited in claim 21, wherein the second part
of the at least one first engagement device extends from the
body.
23. The arrangement as recited in claim 22, such that the bar is
arranged between the cover portion and the body.
24. The arrangement as recited in claim 21, wherein the second
engagement device is adapted to engage the engagement portion of
the first engagement device for securing a bar between the cover
portion and the body.
25. The arrangement according to claim 20, wherein the cover
portion has guiding device for guiding the first engagement device
towards the second engagement device.
26. The arrangement according to claim 20, wherein at least a part
of the through aperture has substantially the same cross-sectional
dimension as a cross-sectional dimension of the first engagement
device.
27. The arrangement according to claim 20, wherein the second
engagement device comprises a holder portion and an engagement
portion, the engagement portion being rotatably attached to the
holder portion.
28. The arrangement according to claim 27, wherein the holder
portion of the second engagement device has at least one attaching
portion extending away from the engagement portion the at least one
attaching portion extending into at least one receiving portion of
the cover portion for captively attaching the second engagement
device to the cover portion.
29. The arrangement according to claim 20, wherein the attaching
portion extends in a direction substantially parallel to the
rotation axis.
30. The arrangement according to claim 20, wherein the at least one
attaching portion has at least one protruding portion, the at least
one protruding portion being arranged to cooperate with at least
one protruding portion of the cover portion for captively attaching
the second engagement device to the cover portion.
31. The arrangement according to claim 20, wherein the at least one
attaching portion of the second engagement device has a resilient
structure.
32. The arrangement according to claim 20, wherein the at least one
attaching portion comprises at least three attaching portions
cooperating with at least three separate receiving portions of the
cover portion.
33. The arrangement according to claim 20, wherein the attaching
portion of the second engagement device comprises a protrusion
extending in a direction away from the rotation axis of the second
engagement device, and the cover portion comprises a protrusion
extending in a direction towards the rotation axis of the second
engagement device, said protrusions being arranged to cooperate
such that the second engagement device is captively attached to the
cover portion.
34. The arrangement according to claim 20, wherein the arrangement
comprises at least two first engagement device and at least two
second engagement device, each of the at least two second
engagement device being arranged to cooperate with a respective one
of the at least two first engagement device.
35. The arrangement according to claim 20, wherein the at least one
first engagement device is a bolt and the at least one second
engagement device is a nut arranged to cooperate with the bolt.
Description
TECHNICAL FIELD
[0001] The present invention deals with attaching arrangements for
hand-held motor-driven tools, such as chain saws. Especially, the
invention deals with arrangements for attaching a bar of such a
hand-held motor-driven tool to a body of the tool.
BACKGROUND
[0002] A conventional chain saw includes a body and a guide bar
that supports the saw chain. A cover clamps the guide bar to the
body by means of a tightening arrangement, comprising a bar bolt
and a nut. For some reasons, e.g. for changing bars or if the chain
has come off, the cover may have to be detached from the body.
Before the cover can be detached, the tightening arrangement has to
be loosened such that the nut is detached from the bar bolt.
[0003] A problem with conventional tightening arrangements, where
the nut is loose when detached from the bar bolt, is that an
operator of the tool might lose the nut when detaching the cover
from the body, especially if situated in a forest. The operator
often puts the nut on the ground after detaching it from the bar
bolt, and since the ground is usually covered by brushwood and
scrub, finding the nut again might be difficult.
[0004] An arrangement where the nut is disposed in the interior of
the cover, and consequently can't be lost when detaching the cover,
is disclosed in US2001/0042311. A disadvantage with this
arrangement is that the cover can not be pressed towards the body
in order to hold the guide bar in position before starting to
thread the nut and the bolt, since the nut will bear against the
bolt before the cover bears against the guide bar. Instead the
operator has to hold the guide bar in position with one hand while
threading the nut with the other hand, which makes the attaching
operation complicated.
[0005] For large chain saws, having long guide bars, the guide bar
tightening arrangement is exposed to greater strain and two bar
bolts with corresponding nuts are generally used in order to
strengthen the mounting. An arrangement having two bar bolts is
disclosed in U.S. Pat. No. 5,497,557. In a chain saw having more
than one bar bolt, the arrangement described in US2001/0042311 is
not convenient since it would not allow loosening the nuts one at a
time. Instead the operator has to unthread the nuts alternately,
which makes the detaching of the cover from the body a bit
tedious.
[0006] There are also other reasons for the operator to detach the
cover, not only for the purpose of changing bar or changing chain.
For instance, the operator is doing a weekly overhaul that might
include inspection of break components and inspection of the
centrifugal clutch. The cover needs to be detached during such
inspections. A further reason for detaching the cover is for
getting access to and cleaning the grove or hole in the bar which
provides the chain with chain oil. The groove or hole might become
clogged by dirt during long term use in severe operating conditions
and is sometimes in need of cleaning.
SUMMARY
[0007] It is an object of the present invention to provide an
improved solution that alleviates at least some of the mentioned
drawbacks with present arrangements.
[0008] The object is achieved by an arrangement for attaching a bar
of a hand-held motor driven tool, such as a chain saw, to a body of
the tool, according to claim 1 of the present invention. The
arrangement comprises: at least one first engagement means, having
a first part, securely arranged to the body, and a second part
extending from the body, the second part having an engagement
portion for engaging a second engagement means; a cover portion
adapted to bear against a bar such that the bar is arranged between
the cover portion and the body; at least one second engagement
means, captively attached to the cover portion, wherein the second
engagement means is adapted to engage the engagement portion of the
first engagement means for securing a bar between the cover portion
and the body, the second engagement means having a rotation axis.
The second engagement means is arranged to move a first distance
(A) along the engagement portion of the first engagement means, in
a direction of the rotation axis of the second engagement means,
for securing a bar between the cover portion and the body. When the
first and second engagement means are not engaged, the second
engagement means is captively attached to the cover portion in such
a way that it is movable a second distance (B) relative the cover
portion in a direction of the rotation axis of the second
engagement means, wherein the second distance (B) is larger than
the first distance (A).
[0009] Preferably, when the first and second engagement means are
not engaged and the cover portion is dismounted from the body, the
second engagement means is captively attached to the cover portion
in such a way that it is movable a second distance (B) relative the
cover portion in a direction of the rotation axis of the second
engagement means, wherein the second distance (B) is larger than
the first distance (A).
[0010] By captively attaching the second engagement means to the
cover portion in such a way, it is possible for an operator to put
the cover portion onto the first engagement means such that the
cover portion can be pressed towards the bar for clamping the bar
between the cover portion and the body of the tool before the
operator starts to engage the second engagement means to the first
engagement means. Thereby, mounting the cover portion to the bar is
facilitated when a second engagement means captively attached to
the cover portion is used. The solution also ensures correct
mounting of the cover portion to the body, which is especially
crucial if a brake is mounted in the cover portion.
[0011] According to an embodiment of the invention, the cover
portion has an inner surface that, when the cover portion is
arranged to the body, is directed towards the body, and an outer
surface that, when the cover portion is arranged to the body, is
directed away from the body. The cover portion further has a
through aperture extending between the inner and outer surfaces for
receiving the second part of the first engagement means. The cover
portion further comprises at least one recess in which an attaching
portion of the second engagement means is arranged for captively
attaching the second engagement means to the cover portion.
[0012] By arranging the cover portion with such a recess and such a
through aperture, the nut can be captively attached to the cover
portion and still have a certain play in the direction of the nut
rotation axis, in relation to the cover portion.
[0013] According to another embodiment of the invention, the cover
portion has guiding means for guiding the first engagement means
towards the second engagement means. Thereby, it is facilitated to
guide the cover portion correctly onto the first attachment means,
since when the first attachment means is inserted into the guiding
means the first attachment means is guided towards the second
attachment means, whereby a correct arrangement of the cover
portion to the body is achieved.
[0014] According to yet another embodiment of the invention, at
least a part of the through aperture has substantially the same
cross-sectional dimension as a cross-sectional dimension of the
first engagement means. Thereby, the inner walls of the through
aperture functions as a guiding means for guiding the first
engagement means towards the second engagement means.
[0015] According to an alternative embodiment of the invention, the
at least one recess of the cover portion is arranged separately
from the through aperture. Thereby, the second distance B, the
distance that the second engagement means is movable relative the
cover portion can be increased and still it is possible to use the
whole length of the through aperture as a guiding means for guiding
the first engagement means towards the second engagement means.
[0016] According to a variant of this alternative embodiment, the
second engagement means comprises a holder portion and an
engagement portion, the engagement portion being rotatably attached
to the holder portion. Since the engagement portion is rotatably
attached to the holder portion, the holder portion can be captively
attached to the cover portion without having to be rotatable.
Thereby, the cover portion does not have to allow rotational
movement of the holder portion in the cover portion, resulting in
less free space necessary for the second engagement means in the
cover portion.
[0017] According to another variant of the same alternative
embodiment, at least one attaching portion of the holder portion of
the second engagement means has a resilient structure. Thereby, the
holder portion can be snap-fitted into the at least one recess of
the cover portion, which results in a quick captive mounting of the
second engagement means to the cover portion.
[0018] According to yet another variant of the same alternative
embodiment, the at least one attaching portion comprises at least
three attaching portions cooperating with at least three separate
recesses of the cover portion. Thereby, a close fit can be achieved
between the recesses and the attaching portions of the nuts
irrespective of tolerances in construction of cover portions and
nuts.
[0019] According to another alternative embodiment of the
invention, the at least one recess for captively attaching the
second engagement means to the cover portion is a part of the
through aperture for receiving the first engagement means. Thereby,
the manufacture of the cover portion is simplified since recess and
through aperture is in the same hole.
[0020] According to a variant of this alternative embodiment, the
attaching portion of the second engagement means comprises a
protrusion extending in a direction away from the rotation axis of
the second engagement means, and the cover portion comprises a
protrusion extending in a direction towards the rotation axis of
the second engagement means, said protrusions being arranged to
cooperate such that the second engagement means is captively
attached to the cover portion. Thereby, a cost-efficient manner to
captively attach the nut to the cover portion is achieved.
[0021] According to another variant of this alternative embodiment,
the cover portion has a base portion and a plate portion, wherein
the plate portion is attached to the base portion by means of an
attachment device, and wherein the protrusion of the cover portion
is part of the plate portion. Thereby, captively mounting the nut
to the cover portion is facilitated. Also, changing a defect nut is
facilitated.
[0022] According to another embodiment of the invention, the
arrangement comprises at least two first engagement means and at
least two second engagement means, each of the at least two second
engagement means being arranged to cooperate with a respective one
of the at least two first engagement means. By using an arrangement
according to the invention for a tool having at least two first
engagement means with corresponding second engagement means, the
user may engage a second engagement means to its corresponding
first engagement means fully, before another second engagement
means is engaged to its corresponding first engagement means.
Thereby, assembling the cover portion to the body is facilitated.
Similarly, when disassembling the cover portion from the body, a
second engagement means can be disengaged from its first engagement
means before the other second engagement means are even loosened
from their corresponding first engagement means, which facilitates
the disassembling of the cover portion from the body.
[0023] According to another aspect of the invention, a hand-held
motor-driven tool, such as a chain saw is claimed. The tool
comprises a body and a bar and an arrangement according to the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will in the following be described in more
detail with reference to the enclosed drawings, wherein:
[0025] FIGS. 1 and 2 are cross sectional views of a part of a chain
saw including a first embodiment of the present invention.
[0026] FIG. 3 is a perspective view of a nut according to the first
embodiment of the present invention
[0027] FIG. 4 is a cross sectional view of a second embodiment of
the present invention.
DESCRIPTION OF EMBODIMENTS
[0028] The present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein; rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. In the drawings, like
numbers refer to like elements.
[0029] Two preferred embodiments of attaching arrangements for
hand-held motor-driven tools will be described with reference to
FIGS. 1-4. In these embodiments, the hand-held motor-driven tool is
a chain saw having a body and a chain guiding bar that in a
conventional manner supports and guides a saw chain in a peripheral
groove of the bar. The saw chain is driven by a sprocket wheel,
hidden under a cover portion. The body is provided with an engine
that via a driving arrangement drives the sprocket wheel. The guide
bar extends forwardly in the longitudinal direction of the chain
saw, and the rearward end of the bar is clamped between the body
and the cover portion by means of a tightening arrangement.
[0030] A first embodiment of the present invention is shown in
FIGS. 1-3. FIGS. 1 and 2 show a portion of a chain saw including
the present invention. A cover portion 14 clamps a guide bar 1 to a
body 2 by means of a tightening arrangement, comprising two joints
10, 20. Each joint includes a first 3 and a second 15 engagement
means. The first engagement means 3 is a bolt and the second
engagement means 15 is a nut.
[0031] Each bolt 3 has a first part 3a and a second part 3b. The
first part 3a is securely attached to the body 2, e.g. by means of
force fit, and the second part 3b extends from the body in a
direction perpendicular to the guide bar plane and further through
an aperture in the guide bar 1 and through an aperture 14c in the
cover portion 14. The cover portion 14 has an inner surface 14a,
directed towards the body 2, and an outer surface 14b, directed
away from the body. A threaded part 3c of the second bolt part 3b,
functioning as an engagement portion for engaging the nut to the
bolt, projects at least partly beyond the outer surface 14b of the
cover portion. In order to clamp the bar 1 between the cover
portion 14 and the body 2, the nut 15 is engaged to the threaded
part 3c of the bolt 3, and tightened.
[0032] The joint 20 in the right part of FIGS. 1 and 2 illustrates
a condition when the nut 15 and the bolt 3 are not engaged but the
nut is captively connected to the holder portion 14.
[0033] The joint 10 in the left part of FIGS. 1 and 2 illustrates a
condition when the nut 3 and the bolt 15 are engaged and the nut 15
is tightened such that the joint clamps the bar 1 firmly between
the body 2 and the cover portion 14.
[0034] In FIG. 2, reference A indicates a first distance, which is
the length of thread engagement between the bolt 3 and the nut 15,
i.e. the distance in the direction of a nut rotation axis X that
the nut 15 has to move in thread engagement with the bolt 3 for
firmly clamping the bar 1 between the body 2 and the cover portion
14. When the nut is not engaged to the bolt, the nut can move a
second distance B relative the cover portion 14, in the direction
of the nut rotation axis X. In FIG. 2, this second distance B is
equal to the distance in the direction of the nut rotation axis X
between the position of the nut 15 in the left part of the figure
and the position of the nut 15 in the right part of the figure. The
second distance B is equal to or greater than the first distance A,
for allowing the nuts 15 to be loosened separately and
independently of each other when detaching the cover from the
body.
[0035] The nut 15 comprises a hollow and internally threaded body
portion 15b, which is rotatably attached to a holder portion 15a,
as shown in FIG. 3. The body portion 15b is rotatable compared to
the holder portion 15a around the nut rotation axis X.
[0036] The holder portion 15a comprises a substantially circular
portion that bears against the body portion 15b, and three
attaching portions 15c, formed as legs, extending from the
periphery of the substantially circular portion. The legs 15c are
flat and directed away from the body portion 15b in a direction
substantially parallel to the nut rotation axis X.
[0037] For each leg 15c a slot extends from an end of each leg
distal to the body portion in a direction towards the body portion
15b to a point between the distal end of the leg 15c and the
substantially circular portion of the holder portion 15a, such that
the slot partly divides each leg 15c into two parallel parts. Each
parallel part has a protruding portion 15d, shaped as a hook, in
the distal end.
[0038] The cover portion 14 has oblong recesses 14e for receiving
the legs 15c of the nut holder portion 15a. There is one separate
recess 14e for each leg 15c. The recesses 14e are arranged
separately from the through aperture 14c of the cover portion,
which aperture 14c is arranged for receiving the bolt 3. The outer
surface 14b of the cover portion 14 has protruding portions 14d
arranged to co-operate with the hooks 15d of the nut holder portion
legs 15c. The distance between these protruding portions 14d make
the width of an opening of the recess 14e smaller than the width of
the nut holder portion leg 15c at the position of the hooks 15d,
such that the holder portion legs 15c are captivated within the
recess 14e. The depth of each recess 14e is equal to or larger than
the length of a holder portion leg 14c. The recesses 14e may
according to an alternative embodiment extend from the outer
surface 14a to the inner surface 14 b of the body, e.g. the
recesses may be through apertures.
[0039] The slots of each leg 15c make the structure of the nut
holder portion legs 15c resilient. The outer ends of the two
parallel parts can be pressed towards each other so that it is
possible to snap the legs into the openings of the recesses 14e in
the cover portion. Once inserted into the recesses, the legs 15c
will revert to their original shape. The legs 15c allow the nut 15
to move relative the cover portion 14 in a direction of the
rotational axis X of the nut. When the hooks 15d of the legs
reaches the protruding portions 14d of the cover portion 14, the
protruding portions 14d will co-operate with the hooks 15d such
that the movement of the nut 15 is stopped. In this way, the nut 15
is captively attached to the cover portion 14.
[0040] In FIGS. 1-3, the nut holder portion 15a has three legs 15c
and there are three recesses 14e in the cover portion 14 for
receiving the legs 15c. The number of legs 15c and corresponding
recesses 14e may also be one, two, four or more.
[0041] The cross section in FIG. 1 is taken along a plane that
intersects the centres of the bolts 3. The cross section in FIG. 2
is taken along a plane that is parallel to the cross section plane
in FIG. 1 and that intersects a leg 15c of the nut holder portion
15a.
[0042] If an operator of a tool would like to e.g. change bars 1
using the arrangement described in FIGS. 1-3, the operator starts
by loosening the nuts 15. Thanks to the second distance B being
larger than the first distance A, the length of thread engagement,
the nuts 15 can be unscrewed and loosened one at a time. When the
nuts are loose, the cover 14 including the nuts 15 captively
arranged in the cover is removed from the chain saw. Thereafter,
the operator removes the old bar 1 from the body 2 and the bolts 3
of the tightening arrangement, and arranges a new bar 1 onto the
bolts 3 such that the second part 3b of the bolts passes through
the apertures of the new bar 1.
[0043] When the new bar 1 has been arranged onto the bolts 3, the
cover portion 14 is arranged onto the bolts 3 by leading the bolts
through the through apertures 14c of the cover portion. The through
apertures 14c of the cover portion also function as a guiding means
for guiding the cover portion 14 onto the bolts 3 such that the
cover portion 14 comes into a correct position and such that the
nuts 15 are arranged correctly towards the end of the second parts
3b of the bolts. In chain saw configurations having break
components, such as a break band for a kick-back guard (not shown),
mounted in the cover portion it is important to obtain high
precision in the position of the cover portion 14. As the cover
portion 14 is mounted onto the bolts 3 of body 2 the through
aperture 14c of the cover portion 14 gets guidance from the second
part 3b of the bolt 3. The diameters of the second part 3b of the
bolt 3 and the through aperture 14c are preferably adapted to
achieve a close fit and thereby a sufficient guidance in order to
obtain a high precision in the position of the cover portion 4.
According to the present embodiment the precision in the position
of the cover portion 14 is even further improved by the relatively
long contact area, defined by the distance C in FIG. 1.
[0044] Thanks to the nuts 15 being captively attached to the cover
portion 14 in such a way that they are movable a second distance B
relative the cover portion 14 in a direction of their rotation axis
X, which second distance B is larger than the first distance A, the
cover 14 can be arranged onto the bolts 3 such that the cover 14
can be pressed towards the bar 1 and the body 2 before the nuts 15
are tightened. This measure facilitates a correct arrangement of
the bar between the cover and the body.
[0045] When the cover 14 has been arranged onto the bolts 3 and the
bar 1 is clamped towards the body 2 by the cover 14, the nuts 15
are tightened by threadingly engaging the nuts 15 to the bolts
3.
[0046] An alternative embodiment of the present invention is shown
in FIG. 4 wherein, as for the embodiment described with reference
to FIGS. 1-3, a cover portion 4 clamps a guide bar 1 to a body 2 by
means of a tightening arrangement, comprising two joints 10, 20.
Each joint includes a first 3 and a second 5 engagement means. The
first engagement means 3 is a bolt and the second engagement means
5 is a nut.
[0047] The Joint 10 in the left part of FIG. 4 shows a state when
the nut 5 is engaged to the bolt 3 so that the bar 1 is firmly
clamped between the cover portion 4 and the body 2. The Joint 20 in
the right part of FIG. 4 illustrates a condition when the nut 5 and
the bolt 3 are not engaged but the nut is captively connected to
the cover portion 4.
[0048] In this second embodiment, the bolts 3 may be similar to the
bolts described with reference to FIGS. 1-3. Each bolt has a first
part 3a, securely attached to the body 2, and a second part 3b
extending from the body through an aperture in the guide bar 1 and
further through an aperture 4c,4g in the cover portion 4. The cover
portion 4 has an inner surface 4a, directed towards the body, and
an outer surface 4b, directed away from the body.
[0049] In contrast to the embodiment described with reference to
FIGS. 1-3, a plate 4f is attached to the outer surface 4b of the
cover portion by means of a screw 6. The second part 3b of the bolt
extends through an aperture in the plate 4f. A threaded part 3c of
the second bolt part 3b projects beyond the plate 4f, in a
direction away from the cover portion 4. In order to clamp the bar
1 between the cover portion 4 and the body 2, the nut 5 is engaged
to the threaded part 3c of the bolt 3, and tightened.
[0050] The nut 5 comprises an internally threaded body portion 5c
for engaging the threaded part 3c of the bolt. The internally
threaded body portion is provided with a flange 5d that is adapted
to bear against the plate 4f when the nut 5 is tightened. To allow
axial movement of the nut 5 in a direction of the nut rotation axis
X, the nut also comprises an attaching portion 5a, formed as a
neck, adapted to be inserted into the through aperture 4c, 4g of
the cover portion 4. The neck projects from the body portion in the
direction of the nut rotation axis X from the flange 5d and away
from the body portion 5c. The neck 5a has a protrusion, 5b formed
as a flange arranged at the end distal to the flange 5d. The
protrusion 5b is adapted to co-operate with at least one edge 4d of
the aperture of the plate 4f, the at least one edge defining a
diameter of the aperture in the plate 4f, so that the nut remains
captively attached to the cover portion 4. A nut 5 arranged in this
way could rather easily be manufactured with low tolerances.
[0051] The aperture 4c, 4g in the cover portion has two parts; an
inner part 4g closest to the inner surface 4a of the cover portion
4, and an outer part 4c closest to the outer surface 4b of the
cover portion 4. The diameter of the inner part 4g is smaller than
the diameter of the outer part 4c. The outer part 4c is arranged as
a recess in the aperture 4c, 4g. More specifically, the diameter of
the inner part 4g is equal to or slightly larger than the diameter
of the second part 3b of the bolt and the diameter of the outer
part 4c is equal to or larger than the diameter of the protrusion
5b of the nut neck 5a. The outer part 4c of the aperture 4c, 4g has
a larger diameter than the inner part 4g for being able to receive
the nut neck 5a with its protrusion 5b.
[0052] The inner part 4g, according to present embodiment, also
functions as a guide for the cover portion 4. In chain saw
configurations having break components, such as a break band for a
kick-back guard (not shown), mounted in the cover portion it is
important to obtain high precision in the position of the cover
portion 4. As the cover portion 4 is mounted onto the bolts 3 of
body 2 the inner part 4g of the aperture 4c, 4g gets guidance from
the second part 3b of the bolt 3. The diameters of the second part
3b of the bolt 3 and the inner part 4g of the aperture 4c, 4g are
preferably adapted to achieve a close fit and thereby a sufficient
guidance in order to obtain a high precision in the position of the
cover portion 4.
[0053] The diameter of the aperture in the plate 4f is slightly
smaller than the diameter of the outer part 4c of the through
aperture 4c, 4g of the cover portion 4, such that the edge 4d of
the plate 4f aperture partly covers the opening of the aperture 4c,
4g in the cover portion 4.
[0054] When the nut 5 is loosened such that its threaded part is
not engaged to the threaded part 3c of the bolt, as illustrated by
joint 20 in FIG. 4, the nut 5 is still connected to the cover
portion 4 because the diameter of protrusion 5b is slightly larger
than the diameter of the aperture in the plate 4f.
[0055] In FIG. 4, reference A indicates a first distance, which is
the length of thread engagement between the bolt 3 and the nut 5,
i.e. the distance in the direction of the nut rotation axis X that
the nut 15 has to move in thread engagement with the bolt 3 for
firmly clamping the bar 1 between the body 2 and the cover portion
14. When the nut is not engaged to the bolt, the nut is engaged to
the cover portion 4 such that the nut can move a second distance B
relative the cover portion 4, in the direction of the nut rotation
axis X. In FIG. 4, this second distance B is equal to the distance
in the direction of the nut rotation axis X between the position of
the nut 5 of the joint 10 in the left part of the figure and the
position of the nut 5 of the joint 20 in the right part of the
figure. The second distance B is equal to or greater than the first
distance A, for allowing the nuts 5 to be loosened separately and
independently of each other. Reference C indicates the thickness of
the cover portion 4, i.e. a distance between the outer surface 4b
and inner surface 4a of the cover portion.
[0056] The walls of the inner part 4g of the through aperture will
function as a guiding means for guiding the bolt 3 towards the nut
5 when the cover portion 4 is lead on to the bolt 3 such that the
bar 1 is clamped between the cover portion 4 and the body 2.
Reference D indicates a length of the inner part 4g of the through
aperture 4c, 4g in the cover portion 4 in the direction of the nut
rotation axis X functioning as a guiding means, i.e. a guiding
length.
[0057] According to an embodiment, the aperture in the plate 4f may
be oblong having a smallest diameter similar to the diameter
between the edges 4d of the plate 4f and a largest diameter larger
than the diameter of the nut neck 5a at the protrusions 5b.
Thereby, when the plate 4f is not attached to the outer surface 4b
of the cover portion 4, it is possible to insert the nut neck 5a
through the aperture in the plate 4f where the aperture has a
diameter similar to or broader than the diameter of the nut neck 5a
at the protrusions 5b, by tilting the nut 5 relative the plate 4f,
before inserting the nut neck through the aperture in the plate 4f.
When the plate is attached to the cover portion by means of the
screw 6 such that the plate bears against the outer surface 4b of
the cover portion 4, and the nut neck 5a extends into the aperture
4c, 4g, the nut 5 can not be tilted and is thus captively attached
to the cover portion.
[0058] In another embodiment, the aperture in the plate 4f may be
circular having a diameter similar to the distance between the
edges 4d of the plate. For making it possible to insert the nut
neck 5a in the aperture of the plate 4f, the nut neck may have
slots extending in the direction of the nut rotation axis X, the
slots making the structure of the nut neck 5a resilient. Thus it
will be possible to compress the nut neck 5a and to snap it through
the aperture in the plate 4f. Once inserted, the nut neck 5a will
revert to its original shape, and the nut 5 is captively connected
to the plate 4f.
[0059] The plate 4f can be a separate plate or a part of an already
existing part of the hand-held motor-driven tool, such as a spike
or spike bumper of a chain saw.
[0060] Other embodiments of the present invention are also
possible. For example, there could be only one bolt and one nut in
the attaching arrangement.
[0061] Above, the tool is described as a chain saw. Although, the
tool may be any kind of hand-held motor-driven tool in which a bar
is clamped between a cover and a body, such as a hedge trimmer,
clearing saw, trimmer, pole saw or a power cutter.
[0062] In the drawings and specification, there have been disclosed
preferred embodiments and examples of the invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for the purpose of limitation, the
scope of the invention being set forth in the following claims.
* * * * *