U.S. patent application number 10/168916 was filed with the patent office on 2003-01-02 for hand-held machine tool comprising a sealing ring disposed in the tool holder.
Invention is credited to Schlipf, Juergen, Ullrich, Andre.
Application Number | 20030000715 10/168916 |
Document ID | / |
Family ID | 7661435 |
Filed Date | 2003-01-02 |
United States Patent
Application |
20030000715 |
Kind Code |
A1 |
Ullrich, Andre ; et
al. |
January 2, 2003 |
Hand-held machine tool comprising a sealing ring disposed in the
tool holder
Abstract
A low-wear sealing ring, which assures a favorable sealing
action that prevents the escape of lubricants from the transmission
chamber of the machine tool and prevents the entry of dust into the
transmission chamber, has a number of sealing lips (6, 7) that rest
against a percussion bolt (3) in the machine tool. At least on its
lateral flank oriented toward the machine, the sealing ring (4) is
provided with one or more radially extending recesses (8, 9). This
lends the sealing lips (6, 7) a high degree of flexibility,
allowing them to easily follow the movements of the percussion bolt
(3), as a result of which the sealing ring (4) has a low
susceptibility to wear and assures a high degree of
impermeability.
Inventors: |
Ullrich, Andre;
(Filderstadt-Bernhausen, DE) ; Schlipf, Juergen;
(Leonberg, DE) |
Correspondence
Address: |
Michael J Striker
Striker Striker & Stenby
103 East Neck Road
Huntington
NY
11743
US
|
Family ID: |
7661435 |
Appl. No.: |
10/168916 |
Filed: |
June 24, 2002 |
PCT Filed: |
October 18, 2001 |
PCT NO: |
PCT/DE01/03981 |
Current U.S.
Class: |
173/213 |
Current CPC
Class: |
F16J 15/3232 20130101;
B25D 2250/365 20130101; B25D 17/06 20130101 |
Class at
Publication: |
173/213 |
International
Class: |
E21B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2000 |
DE |
10053580.1 |
Claims
1. A hand power tool with a tool holder (1), which can be driven in
a rotary and percussive fashion and in which a percussion bolt (3)
is supported so that it can move axially, in which the tool holder
(1) contains at least one sealing ring (5) that encompasses the
percussion bolt (3), characterized in that the sealing ring (5) has
a number of sealing lips (6, 7) that rest against the percussion
bolt (3) and that the sealing ring (5), at least on its lateral
flank oriented toward the machine, is provided with one or more
radially extending recesses (8, 9).
2. The hand power tool according to claim 1, characterized in that
the sealing ring (5) is provided with one or more radially
extending recesses (8, 9) on each of its two lateral flanks.
3. The hand power tool according to claim 1 or claim 2,
characterized in that the sealing ring (5) has a cross-sectional
form that is symmetrical in relation to a radial central plane
(10).
4. The hand power tool according to claim 1, characterized in that
with its side oriented away from the percussion bolt (3), the
sealing ring (5) is fitted into a radially extending groove (4) in
the tool holder (1).
Description
PRIOR ART
[0001] The current invention relates to a hand power tool with a
tool holder, which can be driven in a rotary and percussive fashion
and in which a percussion bolt is supported so that it can move
axially, in which the tool holder contains at least one sealing
ring that encompasses the percussion bolt.
[0002] DE 197 24 532 A1 has disclosed a drilling and hammering
machine tool of this kind. The percussion bolt must be sealed in
relation to the tool holder in such a way that on the one hand, no
lubricant escapes from the transmission chamber of the machine tool
and on the other hand, no dirt from the outside gets into the
transmission chamber of the machine through the tool holder. To
that end, in the known machine tool, sealing rings (O-rings) are
inserted into two radially extending grooves of the percussion
bolt, which seal the gap between the percussion bolt and the inside
of the tool holder.
[0003] In a percussive machine tool, the percussion bolt moves in
the axial direction, for example with a frequency of 65 to 85 Hz
and an amplitude of 1 to 10 mm. In addition, the percussion bolt
also moves in the radial direction depending on component
tolerances and a thermal expansion of the materials. Under these
circumstances, a seal inserted between the percussion bolt and the
tool holder experiences a relatively high amount of wear. The
object of the invention, therefore, is to produce a sealing ring,
which experiences the least amount of wear possible due to the
motion of the percussion bolt and therefore assures a high degree
of impermeability over a long operation time of the machine
tool.
ADVANTAGES OF THE INVENTION
[0004] The stated object is attained with the features of claim 1
by virtue of the fact that the sealing ring has a number of sealing
lips that rest against the percussion bolt and that at least on its
lateral flank oriented toward the machine, the sealing ring is
provided with one or more radially extending recesses. This
particular formation of the sealing ring lends the sealing lips a
very high degree of flexibility so that they can easily follow the
axial and radial movements and the thermal expansion of the
material without a large amount of wear and consequently produce a
reliable sealing of the percussion bolt in the tool holder.
[0005] Because one or more radially extending recesses are provided
on the lateral flank of the sealing ring oriented toward the
machine, the penetration of lubricant (oil or grease) from the
transmission chamber into the at least one recess causes the
sealing lip oriented toward machine to experience an increased
pressure against the percussion bolt and consequently increases the
impermeability against an escape of lubricant from the transmission
chamber of the machine tool. If the lateral flank of the sealing
ring oriented toward the tool is also provided with one or more
radially extending recesses, this also lends the sealing lip
oriented toward the tool a high degree of flexibility, allowing it
to easily follow the axial and radial movements of the percussion
bolt as well as thermal expansions of the material and consequently
produces an effective seal of the transmission chamber of the
machine tool against penetration of dust through the tool
holder.
[0006] Advantageous modifications of the invention can be inferred
from the dependent claims.
[0007] It is useful to provide both lateral flanks of the sealing
ring with one or more recesses in order, as mentioned above, to
produce a seal that prevents both the penetration of dust and the
escape of lubricant.
[0008] The sealing ring preferably has a cross-sectional form that
is symmetrical with regard to a radial central plane thus
preventing a laterally reversed insertion of the sealing ring.
[0009] A favorable adhesion of the sealing ring in the tool holder
is achieved by virtue of the fact that the sealing ring is fitted
with its side oriented away from the percussion bolt into a
radially extending groove in the tool holder.
DESCRIPTION OF AN EXEMPLARY EMBODIMENT
[0010] The invention will be explained in detail below in
conjunction with an exemplary embodiment shown in the drawing.
[0011] The sole FIGURE of the drawing shows a longitudinal section
through the front part of a rotating and hammering hand power tool,
namely a percussive drill or a hammer drill. Freed of all parts of
the hand power tool that are unnecessary for the explanation of the
invention, the drawing shows a tool holder 1 with a receiving bore
2 for a tool, for example a drill bit, a chisel, or the like. This
tool holder transmits a rotary motion from a drive mechanism that
is not shown to a tool that is inserted into it. A percussion bolt
3 is supported so that it can move axially in the tool holder 1. A
drive mechanism moves this percussion bolt 3 back and forth axially
in the tool holder 1 with a frequency of 65 to 85 Hz and an
amplitude of 1 to 10 mm and transfers this motion to a tool
inserted into the tool holder 1.
[0012] A sealing ring 5, which encompasses the percussion bolt 3,
is inserted into an annular groove 4 on the inside of the tool
holder 1. The purpose of this sealing ring 5 on the one hand is to
prevent an escape of lubricant (grease or oil) from the
transmission chamber of the machine tool into the tool holder 1 and
on the other hand to prevent the penetration of dust from the tool
holder 1 into the transmission chamber. Fulfilling these high
sealing requirements for the longest possible operating time of the
machine tool is problematic because the percussion bolt 3
encompassed by the sealing ring 5 moves not only in the axial
direction, but also moves in the radial direction due to component
tolerances and thermal expansion of the materials. In order, even
with these movements of the percussion bolt 3, to minimize the wear
susceptibility of the sealing ring 5 and therefore a slackening of
its sealing action, the sealing ring 5 has two parallel sealing
lips 6 and 7 in the axial direction of the percussion bolt 3. The
sealing lip 6 oriented toward the interior of the machine seals the
transmission chamber against the escape of lubricant and the
sealing lip 7 oriented toward the tool produces a seal preventing
the penetration of dust from the tool holder 1. The sealing ring 5
is thus formed so that separate sealing lips 6 and 7 perform the
two sealing functions. The sealing ring 5 can also have more than
two sealing lips.
[0013] A rapid wear of the sealing ring 5 and therefore a loss of
sealing action can be counteracted by giving the sealing lips 6 and
7 a high degree of flexibility so that they can easily follow the
axial and radial movements of the percussion bolt 3. A high degree
of flexibility of the sealing lips 6 and 7 is achieved by virtue of
the fact the sealing ring 5 is provided with recesses 8 and 9 that
extend radially around the sealing ring on both of its lateral
flanks above the sealing lips 6 and 7. This gives the sealing ring
5 a waist above the sealing lips 6 and 7, which make these sealing
lips very mobile.
[0014] In contrast to the exemplary embodiment shown, a recess 8, 9
does not have to be provided on each lateral flank of the sealing
ring 5. However, it is advantageous to provide at least one recess
8 on the lateral flank oriented toward the machine. This recess 8
would namely have the effect that lubricant from the transmission
chamber of the machine tool could penetrate into this recess and,
due to the pressure of the lubricant in the recess 8, the sealing
lip 6 disposed underneath it would be pressed against the
percussion bolt 3 with a greater pressure.
[0015] The size and depth of the recesses 8 and 9 and depending on
them, the thickness of the sealing lips 6 and 7, influence the
flexibility of the sealing lips 6 and 7 and their contact force
against the percussion bolt 3. The flexibility of the sealing lips
6 and 7 could be further increased by providing not only one recess
8, 9 on each lateral flank of the sealing ring 5, but a number of
radially extending recesses that are offset from one another.
[0016] The ends of the sealing lips 6 and 7 resting against the
percussion bolt 3 are rounded so that they can slide as well as
possible against the moving percussion bolt 3.
[0017] The sealing ring 5 is preferably comprised of an elastomer
material.
[0018] If, as shown in the drawing, a sealing ring 5 is used, which
has a cross-sectional form that is symmetrical with regard to a
radial central plane 10, no particular insertion direction of the
sealing ring 5 needs to be maintained.
[0019] The region of the sealing ring 5 oriented away from the
percussion bolt 3 fills the annular groove 4 in the tool holder 1
over its entire width and rests flush in the groove. As a result,
the outer region of the sealing ring 5 has a high degree of
stability and a favorable adhesion in the tool holder 1 so that the
ring is secured against sliding in the axial direction and against
rotating around the tool holder axis.
* * * * *