U.S. patent application number 10/337283 was filed with the patent office on 2003-07-24 for holding device for the inner seal of a fluid-operated percussion drive.
Invention is credited to Ahr, Torsten, Deimel, Thomas, Dorsch, Christian, Mellwig, Markus, Schneider, Hans-Jurgen.
Application Number | 20030136586 10/337283 |
Document ID | / |
Family ID | 7712957 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030136586 |
Kind Code |
A1 |
Schneider, Hans-Jurgen ; et
al. |
July 24, 2003 |
Holding device for the inner seal of a fluid-operated percussion
drive
Abstract
An apparatus having a housing (5) that shields a front of a
percussion drive (1) against the environment, and into which a
drive driven tool (3) projects. An exchangeable outer seal (10) is
disposed at the housing opening (6c) for the tool (3), surrounds
the tool transversely to its longitudinal axis (3a) with spacing,
and is moveable in this transverse direction. An inner seal (11) is
disposed behind the outer seal (10), and rests elastically against
the tool (3) outside of its tool guide (2). The inner seal (11) is
exchangeably secured to an elastic extension (12) of the tool guide
(2) that surrounds the percussive tool (3) in the region of the
inner seal (11) with a spacing larger than the largest transverse
displacement of the tool (3). The extension (12) is an independent,
elastic support that forms a detachable connection with the tool
guide (2) at one end.
Inventors: |
Schneider, Hans-Jurgen;
(Velbert, DE) ; Deimel, Thomas; (Mulheim, DE)
; Dorsch, Christian; (Bremen, DE) ; Mellwig,
Markus; (Hagen, DE) ; Ahr, Torsten; (Essen,
DE) |
Correspondence
Address: |
VENABLE, BAETJER, HOWARD AND CIVILETTI, LLP
P.O. BOX 34385
WASHINGTON
DC
20043-9998
US
|
Family ID: |
7712957 |
Appl. No.: |
10/337283 |
Filed: |
January 7, 2003 |
Current U.S.
Class: |
175/135 |
Current CPC
Class: |
B25D 2217/0065 20130101;
B25D 17/00 20130101 |
Class at
Publication: |
175/135 |
International
Class: |
E21B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2002 |
DE |
102 02 648.3 |
Claims
What is claimed is:
1. An apparatus comprising: a fluid-operated percussion drive; a
housing part that shields the percussion drive, at least at the
front, against the environment, and into which a percussive tool
driven by the drive projects axially into a tool guide of the
drive; an exchangeable outer seal disposed at an opening provided
in the housing part for the tool, with the seal surrounding the
tool, transversely to its longitudinal axis, with at least some
spacing, and being seated for movement in the transverse direction;
an inner seal disposed behind the outer seal, when seen counter to
the direction of action of the tool, and resting in an elastic
manner against the tool, outside of said guide, with the inner seal
being secured, so as to be exchangeable, to an axial extension of
the tool guide in the direction of the action of the tool, said
extension surrounding the percussive tool in the region of the
inner seal, with a spacing that is larger than the largest possible
transverse displacement of the percussive tool in the housing; and
wherein: said extension is an independent, elastic support element
that, on its rear side facing away from the inner seal, has a
beginning segment that forms a detachable connection with a
receiving segment of the tool guide in the longitudinal and
transverse directions; and the extension latches in the receiving
segment of the tool guide that is designed to secure the extension
in a snap connection.
2. The apparatus according to claim 1, wherein the extension is
formed of a thermoplastic elastomer.
3. The apparatus according to claim 2, wherein the thermoplastic
elastomer is polyurethane.
4. The apparatus according to claim 1, wherein the connection is
produced at least partially inside the tool guide.
5. The apparatus according to claim 1, wherein the extension is
supported on the outside of the tool guide facing away from the
percussive tool.
6. The apparatus according to claim 1, wherein the tool guide has
at least one annular-groove-type depression as a component of the
connection.
7. The apparatus according to claim 6, wherein the at least one
annular-groove-type depression is formed on the outside of the tool
guide facing away from the percussive tool.
8. The apparatus according to claim 6, wherein the
annular-groove-type depression is additionally undercut, at least
on one of the side facing the inner seal and the side facing away
from the inner seal.
9. The apparatus according to claim 7, wherein the
annular-groove-type depression is additionally undercut, at least
on one of the side facing the inner seal and the side facing away
from the inner seal.
10. The apparatus according to claims 6, wherein the
annular-groove-type depression is formed as a front-side depression
that originates on the front side of the tool guide that faces the
inner seal.
11. The apparatus according to claim 10, wherein the front-side
depression is undercut in the direction of the tool guide.
12. The apparatus according to claim 1, wherein the extension is
additionally held in position in the direction of the receiving
segment of the tool guide by at least one annular securing
element.
13. The apparatus according to claim 1, wherein the extension has
at least one annular latch that extends into the receiving segment
of the tool guide.
14. The apparatus according to claim 13, wherein at least one latch
of the extension is supported in a non-positive lockup on the
receiving segment.
15. The apparatus according to claim 1, wherein the wall thickness
of the extension, with the exception of the beginning segment that
produces the connection, and its end segment, that supports the
inner seal, decreases in the direction of the end segment.
16. The apparatus according to claim 1, wherein an inner diameter
of the end segment of the extension that supports the inner seal is
larger than an inner diameter of its beginning segment that
produces the connection.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims the priority date of
German Application No. 102 02 648. 3, filed on Jan. 23, 2002, which
is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a holding device for the inner seal
of a fluid-operated percussion drive, having a housing part that
shields the percussion drive, at least at the front, against the
environment, and into which a percussive tool driven by the drive
projects; an exchangeable outer seal, which is disposed at the
opening provided in the housing part for the tool, the seal
surrounding the tool transversely to its longitudinal axis with at
least some spacing, and being embodied to move in this transverse
direction; and having an inner seal, which is disposed behind the
outer seal, seen counter to the direction of action of the tool,
and rests in an elastic manner against the tool, outside of its
guide. The inner seal is secured, so as to be exchanged, to an
extension of the tool guide in the direction of action. This
extension surrounds the percussive tool in the region of the inner
seal, with a spacing that is larger than the largest possible
transverse displacement of the percussive tool.
[0003] DE-A1-196 28 815, which was published prior to this
application, discloses a generic holding device in connection with
a protective device in a fluid-operated percussion drive. The known
protective device is particularly intended to improve the
functioning reliability of the percussion drive by decreasing the
wear in the region of the tool guide, as well as to decrease repair
and maintenance costs. The device accomplishes these objectives in
that the outer seal--formed, for example, as a movably seated cross
slide--simultaneously functions as a mechanical shield and an
advance scraper, while the inner seal disposed behind the outer
seal is intended to prevent the penetration of fine contaminants
into the region of the tool guide.
[0004] The percussion drive can have an arbitrary form, provided
that it includes a percussive tool that can be moved back and forth
in a tool guide, driven by the percussion drive.
[0005] The known protective device is capable of considerably
improving the functioning reliability of the percussion drive, but
it is disadvantageous that the inner seal is secured to an
extension of the tool guide that is an integral component of the
tool guide itself. In the event of tool breakage, which cannot
always be avoided, and may occur near the outer end segment of the
outer tool guide, the extension of the tool guide may be destroyed
or so heavily damaged that the tool guide must be disassembled and
replaced, which is usually a cost- and labor-intensive process.
[0006] Because the production of the tool guide with the extension
is relatively expensive, this guide is only used in fluid-operated
percussion drives having an inner seal that is disposed behind the
outer seal. Accordingly, different tool guides must be produced for
percussion devices of the same structural size but different
designs.
SUMMARY OF THE INVENTION
[0007] It is the object of the invention to improve the known
protective device with respect to the holding device for the
associated inner seal, and therefore make the percussion device
more economically feasible.
[0008] In particular, the novel holding device is to be designed
such that, in the event of serious malfunctions, especially tool
breakage, the tool guide need not be disassembled and exchanged,
provided that it is not also affected by the malfunction.
[0009] The above object generally is achieved according to the
present invention by an apparatus comprising: a fluid-operated
percussion drive; a housing part that shields the percussion drive,
at least at the front, against the environment, and into which a
percussive tool driven by the drive projects axially into a tool
guide of the drive; an exchangeable outer seal disposed at an
opening provided in the housing part for the tool, with the seal
surrounding the tool, transversely to its longitudinal axis, with
at least some spacing, and being seated for movement in the
transverse direction; an inner seal disposed behind the outer seal,
when seen counter to the direction of action of the tool, and
resting in an elastic manner against the tool, outside of said
guide, with the inner seal being secured, so as to be exchangeable,
to an axial extension of the tool guide in the direction of the
action of the tool, said extension surrounding the percussive tool
in the region of the inner seal, with a spacing that is larger than
the largest possible transverse displacement of the percussive tool
in the housing; and wherein: the extension is an independent,
elastic support element that, on its rear side facing away from the
inner seal, has a beginning segment that forms a detachable
connection with a receiving segment of the tool guide in the
longitudinal and transverse directions; and, the extension latches
in the receiving segment of the tool guide that is designed to
secure the extension in a snap connection.
[0010] The essential concept of the invention lies in configuring
the elastomer extension for supporting the inner seal as an
independent, elastic support element which, on its rear side or end
facing away from the inner seal, forms a detachable connection with
the tool guide that is similar to a snap connection. Here, the
extension latches in the receiving segment of the tool guide that
is designed to secure it. In other words, the inner seal is
connected to the tool guide, and the extension, which can be
detached from the tool guide, is disposed between the seal and the
guide. Furthermore, the elastic deformability of the extension
allows it to engage the receiving segment designed to secure it,
and maintain the connection through its elastic behavior, provided
that no external forces are present that could overcome the
retaining forces between the extension and the tool guide.
[0011] Due to the elasticity of the extension, the extension and
the receiving segment of the tool guide are adapted to one another
such that the extension is immovably connected to the receiving
segment after being brought into the segment with the deformation
necessary for latching, provided that no measures are undertaken to
initiate the separation of the extension from the segment, or no
circumstances occur that could trigger correspondingly large
forces.
[0012] If tool breakage occurs outside of the outer end segment of
the tool guide, the broken piece typically only damages the
extension and the inner seal, so only the two aforementioned parts
must be exchanged. The tool guide itself need not be
disassembled.
[0013] It may be that the force originating from the broken piece
merely causes the connection between the receiving segment of the
tool guide and the extension to be broken; consequently, the
extension may be latched to the receiving segment again and reused
after the inner seal has been exchanged.
[0014] It is greatly significant that the elastic properties of the
extension allow it to be inserted into the correspondingly adapted
receiving segment of the tool guide and maintain the produced
connection automatically, so to speak.
[0015] In accordance with the above discussion, it is especially
simple to meet the requirements on the extension by using a
thermoplastic elastomer, notably polyurethane. Of course, the
extension can also be produced from other materials, should they
yield comparable properties in the connection considered here.
[0016] The subject of the invention can be expanded to include
forming the connection between the tool guide and the extension to
be at least partially inside the tool guide, or supporting the
extension on the outside of the tool guide, which faces away from
the percussive tool.
[0017] As an alternative, the invention also relates to embodiments
in which the extension is detachably supported on the inside of the
tool guide, which faces the percussive tool.
[0018] In an especially simple embodiment of the subject of the
invention, the tool guide has at least one annular-groove-like
depression as a component of the connection. The elastic
deformability of the extension allows it to latch in this recess,
thereby creating a form-fit and/or a non-positive lockup with the
tool guide.
[0019] Depending on the geometric relationships and other operating
conditions, a plurality of annular-groove-like depressions can be
provided, with spacing from one another, in the tool guide. In this
instance, the extension is supported in the depressions by a
plurality of adapted, annular projections.
[0020] The at least one annular-groove-like depression is
preferably formed on the outside of the tool guide facing away from
the percussive tool. The advantage of this arrangement is that the
receiving segment of the tool guide is in a region of the
percussion drive where it is less likely to be damaged.
[0021] Within the scope of the invention, the at least one
annular-groove-like depression can, however, also be disposed on
the inside of the tool guide facing the percussive tool.
[0022] The effect or operating reliability of the novel holding
element may be further improved if the annular-groove-like
depression is additionally undercut on at least the side facing the
inner seal or the side facing away from it. In such embodiments,
the annular-groove-like depression is partially closed by a
circumferential protrusion, so in a cross-section, the depression
has a hollow space with an opening that either faces the percussive
tool or is on the side of the tool guide facing away from the
tool.
[0023] Within the scope of the invention, the annular-groove-like
depression can also be formed as a front-side depression that
starts at the front side of the tool guide facing the inner seal.
The advantage of this embodiment is that the extension, which has a
countersurface that is adapted to a respective depression, can be
connected to the tool guide without being severely deformed.
[0024] The front-side depression is advantageously undercut in the
direction of the tool guide, so in a correspondingly adapted
embodiment of the extension, a form-fit connection can be produced
using the front-side depression.
[0025] The operating reliability of the novel holding device can
also be increased, if necessary, by additionally holding the
extension in position in the direction of the receiving segment of
the tool guide by means of at least one annular securing element.
Depending on how the receiving segment is oriented, the securing
element is either pushed onto the outside or inside of the
extension and supports the holding force originating from the
extension itself.
[0026] The annular securing element can essentially have any other
form or embodiment, for example, that of a bushing or a helix. The
securing element is preferably formed as a spring element in order
to ensure that the extension can detach from the tool guide in the
event of an unacceptably high force, despite the use of the
securing element, and avoid more extensive damage.
[0027] For producing a detachable connection with the receiving
segment of the tool guide, the extension has at least one annular
latch, which extends into the receiving segment of the tool
guide.
[0028] In this case, at least one latch of the extension can be
embodied or formed such that it is supported in a non-positive
lockup on the receiving segment. This can be effected in a simple
manner by dimensioning the latch to be larger than the
annular-groove-like depression that receives it, so that the latch
extends into the depression with a prestress.
[0029] Of course, it is possible within the spirit of the invention
to combine the embodiments described above.
[0030] In particular, the tool guide can have at least one
depression on the front side, and at least one annular-groove-like
depression on either the outside facing away from the tool or the
inside facing the tool, in which instance the extension is equipped
with projections that are adapted to the relevant depressions and
are supported in them.
[0031] The holding device can further be formed such that the wall
thickness of the extension, with the exception of its beginning
segment that forms the connection, and its end segment that
supports the inner seal, decreases in the direction of the end
segment. In the simplest case, the wall thickness changes in linear
fashion. However, it can also follow a curved path.
[0032] It can be advantageous to dimension the inner diameter of
the end segment of the extension that supports the inner seal to be
larger than the inner diameter of the beginning segment that forms
the connection.
[0033] The invention is described in detail below by way of
embodiments that are illustrated schematically in the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a partial section through the lower part of a
percussion drive having an associated housing part that receives an
exchangeable component whose outer seal is seated so as to be
displaced.
[0035] FIG. 2 is a partial section of the embodiment according to
FIG. 1, on an enlarged scale.
[0036] FIG. 3 is a partial section through an embodiment similar to
the one in FIG. 2, with the annular-groove-like depression that is
formed on the inside of the tool guide being undercut in the
direction of the tool guide.
[0037] FIG. 4 is a partial section in the region of the tool guide,
the extension connected to the guide and the inner seal secured
thereto, the tool guide being provided with an annular-groove-like
depression on its outside.
[0038] FIG. 5 is a partial section through an embodiment similar to
the one in FIG. 4, with the outside of the tool guide being
provided with two annular-groove-like depressions that are spaced
from one another.
[0039] FIG. 6 is a partial section through an embodiment similar to
the one in FIG. 4, in which the annular-groove-like depression that
is provided on the outside of the tool guide is undercut in the
direction of the tool guide.
[0040] FIG. 7 is a partial section through an embodiment in which
the extension supporting the inner seal is held by an
annular-groove-like depression on the outside of the tool guide, on
the one hand, and by an annular-groove-like, front-side depression
that originates from the front side of the tool guide, on the
other.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Because the rest of the embodiment of the fluid-operated
percussion drive is not of importance for the realization of the
invention, FIG. 1 only illustrates the lower part 1 of the
percussion drive, in which a tool guide 2 is immovably held. A
percussive tool in the form of a chisel 3 and having the
longitudinal axis 3a is supported so as to move longitudinally in
the guide 2. An arrow 4 indicates the direction of movement of the
chisel 3 in the direction of action. The pendulous movements that
the chisel 3 may perform are schematically indicated on an
exaggerated scale by dashed lines 3b and 3c.
[0042] A housing part 5, which detachably receives an exchangeable
component 6 at its front side (at the bottom in the figure), is
secured as an extension to the lower part 1 of the percussion
drive. For receiving the exchangeable component 6, the housing part
5 is provided with a recess 7 that is slightly deeper than the
height of the component, and whose diameter is adapted to the
diameter of the component. The parts 5 and 6 are detachably secured
to one another by pins 8.
[0043] The exchangeable component 6 comprises a front plate 6a and
a rear plate 6b. These plates have a sufficiently large passage 6c
for the chisel 3, and limit an annular chamber 9 transversely to
the longitudinal axis 3a. An outer seal in the form of a
disk-shaped cross slide 10 is seated to move in this chamber 9.
[0044] The height of the annular chamber 9 in the direction of the
longitudinal axis 3a is slightly larger than the thickness of the
cross slide 10, so the transverse movements of the chisel 3
relative to the housing part 5 cause the slide to move back and
forth as a rigid unit.
[0045] Unlike in the schematic representation of FIG. 1, the wall
10a of the cross slide 10, which limits the opening for the chisel
3, is formed such that transverse movements of the chisel 3
(indicated by the lines 3b and 3c) do not cause the parts 3 and 10
to become misaligned. For this purpose, the wall 10a has a convex
curvature in the direction of the chisel 3 (unlike in the
illustration).
[0046] The parts 6a and 6b are connected (not shown). Accordingly,
the exchangeable part 6 can be installed and removed as a unit with
the cross slide 10 seated to move freely therein.
[0047] Inside the housing part 5, an inner seal 11 is disposed
behind the cross slide 10, seen counter to the direction of action
(arrow 4). The sealing lip 11a of the seal rests in an elastic
manner against the chisel 3, and acts as a scraper for contaminants
that have entered the housing part 5.
[0048] The inner seal 11 is detachably secured to an extension 12
via a securing groove 12b cut into the end segment 12a of the
extension (FIG. 2). In the region of the inner seal 11, the
extension 12 surrounds the chisel 3 at a distance s, which is
larger than the largest possible transverse displacement of the
chisel in this region (indicated by the lines 3b and 3c).
[0049] To assure proper functioning of the inner seal 11 under
different operating conditions, the length of the sealing lip 11a
should be selected so that the ratio of its length to the largest
possible transverse displacement of the chisel 3 in the region of
the sealing lip is a value greater than 2.
[0050] Unlike in the prior art, the elastomer extension 12 is
formed as an independent, elastic support element. Its beginning
segment 12c, which rests on the rear side or end of the extension
12 facing away from the inner seal 11, can form a detachable,
snap-like connection with a correspondingly adapted receiving
segment 2a, in the region of the front side or end 2b of the tool
guide (FIG. 2).
[0051] For this purpose, the receiving segment 2a is provided with
an annular-groove-like depression 13 that is spaced from the front
side or surface 2b and is oriented transversely to the longitudinal
axis 3a.
[0052] The beginning segment 12c of the extension 12 has a
circumferential latch 14, which is formed in the manner of an
annular shoulder and is likewise spaced from the support surface
12d of the extension 12 that cooperates with the front side 2b.
[0053] The ability of the extension 12 to be elastically deformed
allows it to be displaced relative to the tool guide 2 such that
its latch 14 extends into the region of the annular-groove-like
depression 13 and latches in the depression 13, thereby forming the
aforementioned detachable connection.
[0054] The elastic deformability of the extension 12 maintains the
connection formed in this manner between the receiving segment 2a
and the beginning segment 12c as long as no external forces larger
than the holding force that originates from the extension act upon
the extension 12.
[0055] If tool breakage occurs in the region of the extension 12,
the extension can first be deformed due to the effect of the
transverse forces, or if the stress is excessive, it can detach
from the receiving segment 2a of the tool guide 2, which may
prevent damage at least to the tool guide 2. Depending on the
effects of the relevant malfunction, the detached extension 12 may
be reused, that is, latched again with the receiving segment
2a.
[0056] If necessary, within the scope of the invention, the
connection between the receiving segment 2a and the beginning
segment 12c may be further reinforced through the selection of the
height of the circumferential (seen parallel to the longitudinal
axis 3a) latch 14 in the disassembled state to be larger than the
height of the annular-groove-like recess 13 in the described
direction (see FIG. 2 in particular). Accordingly, the latch 14 is
compressed when brought into the depression 13, so the latch is
also held with a non-positive lockup in the receiving segment
2a.
[0057] In addition to or instead of this measure, the subject of
the invention can also be embodied such that the annular groove
formed between the latch 14 and the front side 12d forms a
non-positive lockup with the receiving segment 2a.
[0058] As can be seen from FIGS. 1 and 2, the annular-groove-like
depression 13 is disposed on the inside of the tool guide 2 facing
the chisel 3. Furthermore, the effective inner diameter of the tool
guide 2 and the inner diameter of the extension 12 in the region of
its beginning segment 12c are adapted to one another such that the
tool guide 2 changes over into the extension 12, thereby forming a
shoulder A. With the exception of the beginning segment 12c in the
region of the receiving segment 2a, the wall thickness of the
extension decreases continuously in the direction of the end
segment 12a, with a constant outer diameter.
[0059] This ensures that the extension 12 is located outside of the
working region of the percussive tool 3 in the normal state (FIG.
1), and may be able to detach from the receiving segment 2a of the
tool guide 2.
[0060] FIG. 3 illustrates an embodiment of the invention in which
the receiving segment 2a of the tool guide 2 is provided with an
annular-groove-like depression 15 that is undercut in the direction
of the guide (toward the top in the drawing). As already explained
in conjunction with FIGS. 1 and 2, the depression is disposed on
the inside of the tool guide 2 facing the percussive tool 3, and
thus the longitudinal axis 3a.
[0061] Because of the aforementioned undercut, the depression 15
has an annular, circumferential shoulder 2c in the direction of the
longitudinal axis 3a. Accordingly, the opening of the depression 15
(seen parallel to the longitudinal axis 3a) is smaller than the
total height in the described direction.
[0062] The beginning segment 12c of the extension 12 is provided
with a circumferential latch 16 that is spaced from the front side
12d, and, seen in cross-section, is oriented essentially parallel
to the longitudinal axis 3a.
[0063] The dimensions of the latch 16 parallel to the longitudinal
axis 3a are shown in exaggerated form merely for illustration
purposes. Of course, the depression 15 and the latch 16 must be
adapted to each other in terms of size such that the latch 16 can
be guided into the depression 15 and retain the assumed latched
position, thereby producing the desired detachable connection,
provided that no excessively high forces are exerted on the
extension 12 and break the connection between the receiving segment
2a and the beginning segment 12c.
[0064] If necessary, the receiving segment 2a and the beginning
segment 12c of the extension can be adapted to one another,
especially in terms of the embodiment and dimensions of the
depression 15 and the latch 16, such that the latch 16 is held in a
non-positive lockup in the recess 15.
[0065] Unlike in the embodiment shown in FIGS. 1 and 2, the
extension 12 forming an independent, elastic support element is
formed such that its inner diameter, with the exception of the
beginning segment 12c, increases continuously in the direction of
the end segment 12a, with a constant wall thickness in the
assembled state.
[0066] In the embodiment according to FIG. 4, the receiving segment
2a for securing the elastic extension 12 has an annular-groove-like
depression 17, which is formed on the outside of the tool guide 2
facing away from the percussive tool (FIG. 1), and is oriented
transversely to the longitudinal axis 3a. The extension 12 is thus
adapted to the receiving segment 2a such that its beginning segment
12c has an annular latch 18 that projects in the direction of the
longitudinal axis 3a and has an inclined edge 18a for facilitating
the process of inserting the extension into the recess 17.
[0067] Because of the elastic deformability of the elastomer
extension 12, the latch 18 can be displaced so far past the front
side 2b in the direction of the receiving segment 2a that it
eventually latches into the annular-groove-like depression 17 and
detachably connects the extension to the tool guide 2 via the
beginning segment 12c.
[0068] This connection may be broken if desired, or in the event of
a malfunction, by exerting sufficient transverse forces onto the
extension 12.
[0069] If necessary, the connection produced between the segments
2a and 12c can be additionally supported by producing the latch 18
with excess material, and fitting it into the depression 17 with a
non-positive lockup.
[0070] Furthermore, the discussed connection can be additionally
reinforced by pushing a lock washer 19 onto the extension 12 from
the outside at the height of the depression 17. This lock washer 19
additionally generates a force component that serves in keeping the
latch 18 inside the recess 17.
[0071] To prevent an undesired displacement of the lock washer 19,
the extension 12 should have a corresponding element for securing
its position, such as the annular groove 20 indicated in FIG. 4,
which receives the lock washer 19.
[0072] The extension 12 is otherwise formed such that its
cross-section decreases continuously in the direction of the inner
seal 11, with a constant inner diameter.
[0073] The inner diameter of the tool guide 2 changes over in
conical fashion into the inner diameter of the extension 12 in the
region of the receiving segment 2a.
[0074] The embodiment according to FIG. 5 differs from the
above-described embodiment in that the receiving segment 2a of the
tool guide 2 has annular-groove-like depressions 17 and 21, which
are spaced from one another, and in which the elastically
deformable extension 12 is detachably supported by annular latches
18 and 22, respectively.
[0075] As already explained in conjunction with FIG. 4, the
connection between the segments 2a and 12c may additionally be
secured by pushing a securing element, preferably one that can be
elastically deformed, onto the extension 12 at the height of the
receiving segment 2a and fixing it appropriately to avoid undesired
movements parallel to the longitudinal axis 3a.
[0076] The holding device illustrated in FIG. 6 corresponds to the
one in FIG. 3 insofar that the receiving segment 2a likewise has an
annular-groove-like depression 23, which is undercut in the
direction of the tool guide 2 (toward the top in the drawing), and
in which an annular latch 24 is supported in the assembled state.
The latter can be pressed into the recess 23 with a corresponding
prestress.
[0077] Unlike in the embodiment according to FIG. 3, the
annular-groove-like depression 23 is formed on the outside of the
tool guide 2 facing away from the percussive tool 3 (FIG. 1).
Accordingly, the latch 24 also projects in the direction of the
percussive tool 3, or the longitudinal axis 3a, inside the
depression 23.
[0078] With the exception of the embodiment and arrangement of the
latch 24 in the region of the receiving segment 2a, the elastic
extension 12 with the inner seal 11 secured thereto is formed
identically to the embodiment shown in FIG. 4.
[0079] In the embodiment of the invention shown in FIG. 7, the
receiving segment 2a of the tool guide 2 is provided with an
annular-groove-like depression 25, which is oriented transversely
to the longitudinal axis 3a and is disposed on the outside of the
tool guide 2. In the assembled state, an annular, circumferential
latch 26 having an inclined edge 26a (corresponding to the one in
FIG. 4) projects into this depression 25.
[0080] The receiving segment 2a further has an annular-groove-like
front-side depression 27 that originates from the front side 2b and
becomes wider, that is, it is undercut, in the direction of the
tool guide 2 (toward the top in the drawing).
[0081] Corresponding to the embodiment of the receiving segment 2a,
the beginning segment 12c of the extension 12 is provided with a
further annular latch 28, which has a head part 28a with two
holding surfaces 28b.
[0082] In the illustrated assembled state, the head part is fixed
inside the widened part of the front-side depression 27 by the
holding surfaces 28b.
[0083] The above-described holding device thus results from a
combination of a latch 26 and a latch 28 that latch laterally and
at the front side, respectively, in adapted, annular-groove-like
depressions.
[0084] The particular advantage attained with the invention is that
the tool guide provides more extensive protection against damage
than before through the embodiment of the extension that supports
the inner seal as an independent support element. The extension
represents a relatively low-cost exchangeable part whose elastic
deformability allows it to produce and maintain a detachable
connection with the tool guide, provided that the extension is not
acted upon by unacceptably high external forces.
[0085] In the event of a malfunction, the extension can detach from
the tool guide, which may avoid further damage to the tool guide
and, possibly, to the extension itself.
[0086] The invention now being fully described, it will be apparent
to one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
or scope of the invention as set forth herein.
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