U.S. patent application number 11/124842 was filed with the patent office on 2005-12-22 for bearing device and fan apparatus.
Invention is credited to Braun, Willy, Frauhammer, Karl, Kuhnle, Axel, Schnerring, Heinz.
Application Number | 20050281687 11/124842 |
Document ID | / |
Family ID | 34684128 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050281687 |
Kind Code |
A1 |
Frauhammer, Karl ; et
al. |
December 22, 2005 |
Bearing device and fan apparatus
Abstract
In a bearing device equipped with a fastening element for
rotatably supporting a drive shaft of a hand tool unit, the
fastening element has a heat conducting structure for conveying
heat from a bearing region of the fastening element into a
ventilation region of said bearing element, and in a fan apparatus
provided with a fan impeller for cooling a drive unit of a machine
tool the fan impeller is provided to cool a heat conducting
structure which conveys heat from a bearing region of the hand
machine tool into a ventilation region of the same.
Inventors: |
Frauhammer, Karl;
(Leinfelden-Echterdingen, DE) ; Schnerring, Heinz;
(Dettenhausen, DE) ; Braun, Willy; (Neustetten,
DE) ; Kuhnle, Axel; (Freiberg A.N., DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
34684128 |
Appl. No.: |
11/124842 |
Filed: |
May 9, 2005 |
Current U.S.
Class: |
417/366 |
Current CPC
Class: |
H02K 9/22 20130101; H02K
5/1732 20130101 |
Class at
Publication: |
417/366 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2004 |
DE |
102004024287.9 |
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. A bearing device, comprising a fastening element for rotatably
supporting a drive shaft of a hand tool unit, said fastening
element having a bearing region and a ventilation region, said
fastening element having heat conducting means for conveying heat
from said bearing region of said fastening element into said
ventilation region of said fastening element.
2. A bearing device as defined in claim 1, wherein said heat
conducting means are configured to permit air to circulate around
said heat conducting means at least in said ventilation region.
3. A bearing device as defined in claim 1, wherein said heat
conducting means have at least one metallic subregion.
4. A bearing device as defined in claim 1, wherein said at least
one subregion of said heat conducting means has a symmetry axis
which corresponds to a rotation axis of the drive shaft.
5. A bearing device as defined in claim 1, wherein said heat
conducting means have a cylindrical subregion.
6. A bearing device as defined in claim 1, wherein said heat
conducting means are configured to form a part of a labyrinth
fan.
7. A bearing device as defined in claim 1; and further comprising a
housing, and at least one clamping element for clamping said
fastening element to said housing.
8. A bearing device as defined in claim 7, wherein said clamping
element is configured to provide a tolerance compensation.
9. A fan apparatus, comprising a fan impeller for cooling a drive
unit of a hand machine tool having a bearing region and a
ventilation region, said fan impeller being arranged to cool heat
conducting means provided to convey heat from said bearing region
into said ventilation region.
10. A fan apparatus as defined in claim 9, wherein said fan
impeller is provided with a labyrinth fan.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a bearing device and also
to a fan apparatus.
[0002] A bearing device equipped with a fastening element for
rotatably supporting a drive shaft of a hand tool unit is known in
the art. The fastening element is frequently provided to hold a
ball bearing in which the drive shaft is supported. Also, a fan
apparatus equipped with a fan impeller is known in the art. The fan
apparatus with the fan impeller is frequently provided for cooling
a drive unit of a hand machine tool.
[0003] It is believed that the above-mentioned existing devices can
be improved.
SUMMARY OF THE INVENTION
[0004] Accordingly, it is an object of the present invention to
provide a bearing device of the above mentioned general type and
also a fan apparatus of the above mentioned general type, which are
further improvements of the existing constructions.
[0005] In keeping with these objects and with others which will
become apparent hereinafter, one feature of the present invention
resides, briefly stated, in a bearing device with a fastening
element for rotatably supporting a drive shaft of a hand tool unit,
wherein the fastening element has heat conducting means for
conveying heat from a bearing region of the fastening element into
a ventilation region of the fastening element.
[0006] This makes it advantageously possible to prevent the
fastening element from overheating in the bearing region. It is
thus advantageously possible to prevent the occurrence of damage,
for example to seals or ball bearings, due to an overheating of the
bearing region. Furthermore a favorable thermal contact between the
bearing region and the ventilation region is possible, without it
being necessary for dust-laden air to penetrate into the bearing
region. This advantageously prevents an increased wear due to a
dust-induced contamination of the bearing region.
[0007] Hereinafter, the term "provided" is understood in this
context to also mean "designed" and "equipped". In principle, the
design according to the present invention can be used in all
bearings deemed appropriate by those skilled in the art. But it can
be used to particular advantage in hand machine tools due to the
typically high dust loads to which they are subjected and in
particular, in hammer drills or percussion drilling machines, due
to the high mechanical loads to which the bearing devices are
subjected.
[0008] In another embodiment of the present invention, the heat
conducting means are designed so that air circulates around them,
at least in a ventilation region. This makes it possible to achieve
a particularly effective removal of heat from the heat conducting
means.
[0009] According to another embodiment, the heat conducting means
include at least one metallic subregion. The typically high thermal
conduction coefficient and high stability of metallic substances
permit the achievement of a particularly robust and effective heat
removal.
[0010] A particularly space-saving integration of the heat
conducting means into the hand tool unit can be achieved if a
rotation axis of the drive shaft constitutes a symmetry axis of at
least one subregion of the heat conducting means.
[0011] An inexpensive design of the heat conducting means can be
achieved if the heat conducting means has a cylindrical subregion,
which, in a particularly advantageous embodiment, can be designed
to encompass the drive shaft.
[0012] A favorable thermal contact and advantageous dust protection
can be achieved if the heat conducting means are designed to
constitute a part of a labyrinth fan.
[0013] If the bearing device has at least one clamping element
designed to clamp the fastening means to a housing, then it is
possible to achieve a particularly rapid, inexpensive assembly.
[0014] It is possible to eliminate the provision of additional
tolerance compensation devices if the clamping element is provided
to assure a tolerance compensation.
[0015] In accordance with another object of the present invention,
a fan apparatus equipped with a fan impeller for cooling a drive
unit of a hand machine tool is provided, wherein the fan impeller
is provided for cooling heat conducting means in order to convey
heat from a bearing region of the hand machine tool into a
ventilation region. This makes it possible to advantageously
prevent an overheating of the bearing region.
[0016] An effective dust protection of the bearing region can be
achieved if the fan apparatus includes a labyrinth fan.
[0017] The novel features which are considered as characteristic
for the present invention are set forth in particular in the
appended claims. The invention itself, however, both as to its
construction and its method of operation, together with additional
objects and advantages thereof, will be best understood from the
following description of specific embodiments when read in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows a section through a hammer drill with a bearing
device and a fastening element for supporting a drive shaft,
[0019] FIG. 2 shows a section along the line II-II in FIG. 1,
[0020] FIG. 3 shows the fastening element from FIGS. 1 and 2,
[0021] FIG. 4 is a top view of the fastening element from FIG.
3,
[0022] FIG. 5 shows a drive unit with a fan apparatus, the
fastening element, and the drive shaft,
[0023] FIG. 6 shows an alternative bearing device of a hammer
drill, with a clamping element,
[0024] FIG. 7 the fastening element from FIG. 6,
[0025] FIG. 8 a part of a housing of a hammer drill, with a
clamping element in another embodiment of the present
invention,
[0026] FIG. 9 is a sectional view of a hammer drill with a bearing
device and a fastening element for supporting a drive shaft in
another embodiment of the present invention,
[0027] FIG. 10 is a top view of the fastening element and a motor
housing from FIG. 9,
[0028] FIG. 11 is a sectional view of the fastening element from
FIGS. 9 and 10,
[0029] FIG. 12 shows a flexible tolerance compensation element in
another embodiment of the present invention,
[0030] FIG. 13 shows a flexible tolerance compensation element in
another embodiment of the present invention, and
[0031] FIG. 14 shows a wedge-shaped tolerance compensation element
in another embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 shows a bearing device equipped with a fastening
element 10 for rotatably supporting a drive shaft 12, which belongs
to a hand tool unit embodied in the form of a hammer drill and is
attached to an armature of a drive unit 28 embodied in the form of
an electric motor. A first bevel gear 30 is press-fitted onto the
drive shaft 12 and engages with a second bevel gear 32 attached to
a transmission shaft 34. The bevel gears 30, 32 transmit a rotating
motion of the drive shaft 12 to the transmission shaft 34, which in
turn drives a hammer mechanism and a rotating drive of the hammer
drill to which the bearing apparatus belongs.
[0033] The fastening element 10 is embodied in the form of a
fastening plate and has a subregion 18 that is metallic,
cylindrical, and represents a ventilation region 18 of the
fastening element 10. The fastening element 10 and in particular
the subregion 18 assumes the function of heat conducting means 14
that extend between the bearing region 16 of the fastening means 10
and the ventilation region 18. The bearing region 16 is an annular
region encompassing a round opening of the fastening element 10
that is in turn encompassed by the ventilation region 18. The
bearing region 16 is provided to hold a ball bearing 36 of the
bearing device, which ball bearing can be subjected to intense heat
during operation of the hammer drill. The heat absorbed in the
bearing region 16 is conducted by means of the metal of the
fastening element 10 to the ventilation region 18 during operation,
from whence the heat can radiate from an inner surface and an outer
surface. The opening is provided to allow the drive shaft 12 to
pass through, whose rotation axis constitutes a symmetry axis of
the cylindrical subregion 18.
[0034] A fan apparatus with a fan impeller 26 for cooling the drive
unit 28 of the hand machine tool embodied in the form of a hammer
drill is also provided to continuously circulate air around the
ventilation region 18 of the fastening element 10 and the heat
conducting means 14 during operation in order to assure an improved
removal of heat. To that end, on a back side oriented toward the
fastening element 10, the fan impeller 26 has a labyrinth fan 20,
which is partially formed onto the fan impeller 26 and includes two
cylindrical baffles encompassing the symmetry axis of the drive
shaft 12 and one sleeve.
[0035] The cylindrical sleeve, which is integral to the fan
impeller 26, is provided for sliding the fan impeller 26 onto the
drive shaft 12, which rests against an inner surface of the sleeve
while an outer surface of the sleeve constitutes an inner wall of
the labyrinth fan 20. The ventilation region 18 protrudes into an
intermediate space between the outer surface of the sleeve of the
fan impeller 26 and a first baffle of the labyrinth fan 20. A
baffle formed onto the housing 24 of the hammer drill protrudes
into the annular intermediate space between the first and second
baffle of the labyrinth fan 20. During operation, air must flow
along a meandering path in the radial direction between the baffles
to the ventilation region 18, which prevents dust particles from
penetrating into the vicinity of the ventilation region 18. During
operation, the fan impeller 26 rotates and generates an airflow
that flows quickly past the surfaces of the ventilation region 18,
thus circulating around the ventilation region 18; the fan impeller
26 is provided to cool the heat conducting means 14, which are
designed to remove heat from the bearing region 16.
[0036] The sectional view depicted in FIG. 2 clearly shows how the
fastening element 10 is attached to the housing 24 of the hammer
drill. For this purpose, the fastening element 10 has two
hook-shaped tabs 38, 38' on opposite sides, which engage with a
clamping element 22 that is equipped with corresponding hook
elements and is embodied as a strip spring part. The clamping
element 22 embraces a part of the plastic housing 24, which in turn
encompasses the transmission shaft 34. When mounted in place, the
clamping element 22 clamps the fastening element 10 and with it,
the ball bearing 36, the drive shaft 12, and the fan impeller 26 to
the housing 24 in the axial direction in relation to the rotation
axis of the drive shaft 12. The hook elements of the clamping
element 22 are integral to it, are formed out of a strip spring,
and have a curvature radius of approximately 3 mm, which permits an
elastic deformation of the clamping element 22, thus assuring a
tolerance compensation between the housing 24 and the fastening
element 10.
[0037] During an assembly process, first the fan impeller 26, then
the fastening element 10, then the ball bearing 36, and finally the
bevel gear 30 are slid onto the drive shaft 12 (FIG. 5). The
assembled unit thus produced is then clamped to the housing 24 by
means of the clamping element 22.
[0038] FIGS. 6-14 show details or components of additional
embodiments of the present invention. The description will
essentially concentrate on differences in relation to the exemplary
embodiment depicted in FIGS. 1-5. With regard to characteristics
that remain the same, reference is hereby made to the description
regarding FIGS. 1-5. Characteristics and components that
essentially function in the same manner have been provided with the
same reference numerals.
[0039] In the exemplary embodiment depicted in FIGS. 6-8, the tabs
38, 38' of a fastening element 10 have threaded holes provided to
accommodate screws 40, 40' that attach the fastening element 10 to
a housing 24. The housing 24 encompasses a hammering mechanism, is
composed of multiple parts, and has an upper shell 42 and a lower
shell 44. A clamping element 46 embraces the upper shell 44, to
which it is attached by means of a screw 52, and engages in ribs in
the lower shell 42 (FIG. 8).
[0040] In the exemplary embodiment shown in FIGS. 9-11, tabs 38,
38' of a fastening part 10 are elongated in comparison to the
preceding exemplary embodiments. As a result, the fastening part 10
is suitable for diagonal placement inside a cross-section of a
housing 24 in the shape of a rounded square (FIG. 10). In an
assembly process, the housing 24 is screwed to a motor housing 48.
In this assembly process, the tabs 38, 38' of the fastening element
10 are clamped between the housing 24 and the motor housing 48 and
are subjected to a slight bending stress for tolerance compensation
purposes.
[0041] FIGS. 11-14 show other U-shaped tolerance compensation
elements 50-50", which are designed to be positioned between a
fastening part 10 and a housing 24. The tolerance compensation
elements 50, 50' each have spring elements on the legs of their
U-shape, which in the tolerance compensation element 50 (FIG. 12),
are embodied in the form of elongated tabs that protrude from the
legs at an angle and in the tolerance compensation element 50'
(FIG. 13), are embodied in the form of cambered subregions. The
tolerance compensation element 50" (FIG. 14) has wedge-shaped legs
provided for insertion between the fastening element 10 and the
housing 24. Tolerances can be compensated for through adaptation of
the insertion depth. In addition, it is possible for a bearing
device equipped with the tolerance compensation element 50" to be
offset in the axial direction with a prestressing force, thus
permitting the elimination of play.
[0042] It will be understood that each of the elements described
above, or two or more together, may also find a useful application
in other types of constructions differing from the types described
above.
[0043] While the invention has been illustrated and described as
embodied in a bearing device and fan apparatus, it is not intended
to be limited to the details shown, since various modifications and
structural changes may be made without departing in any way from
the spirit of the present invention.
[0044] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic or
specific aspects of this invention.
* * * * *