U.S. patent application number 11/120355 was filed with the patent office on 2005-11-10 for hand machine tool with a hammer mechanism.
Invention is credited to Henke, Thilo, Lennartz, Juergen, Meixner, Gerhard.
Application Number | 20050247462 11/120355 |
Document ID | / |
Family ID | 34684124 |
Filed Date | 2005-11-10 |
United States Patent
Application |
20050247462 |
Kind Code |
A1 |
Meixner, Gerhard ; et
al. |
November 10, 2005 |
Hand machine tool with a hammer mechanism
Abstract
A hand machine tool is equipped with a hammer mechanism, which
has a hammer (1) that moves axially back and forth in a guide tube
(2); a spring mechanism (4) is provided, which exerts a force on
the hammer (1) and can set the hammer (1) into a movement toward a
tool (3) that can be inserted into the hand machine tool. The
hammer mechanism produces a very high individual hammering energy
at a relatively low hammering frequency by virtue of the fact that
after each impact, the hammer (1) is set into a motion counter to
the force of the spring mechanism (4) in order to stress this
spring mechanism and after the stressing of the spring mechanism
(4), the hammer (1) is abruptly released again so that it flies
toward the tool (3).
Inventors: |
Meixner, Gerhard;
(Filderstadt, DE) ; Henke, Thilo; (Stuttgart,
DE) ; Lennartz, Juergen; (Ostfildern, DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
34684124 |
Appl. No.: |
11/120355 |
Filed: |
May 3, 2005 |
Current U.S.
Class: |
173/48 |
Current CPC
Class: |
B25D 2250/371 20130101;
B25D 2216/0015 20130101; B25D 11/125 20130101; B25D 2250/185
20130101; B25D 11/12 20130101; B25D 2216/0023 20130101; B25D
2250/375 20130101 |
Class at
Publication: |
173/048 |
International
Class: |
E02D 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2004 |
DE |
10 2004022623.7 |
Claims
1. A hand machine tool--preferably a hammer drill and/or slide
hammer--equipped with a hammer mechanism, which has a hammer (1)
that moves axially back and forth in a guide tube (2); a spring
mechanism (4, 15, 16) is provided, which exerts a force on the
hammer (1) and can set the hammer (1) into a movement toward a tool
(3) that can be inserted into the hand machine tool, wherein means
(8, 10, 13, 14) are provided, which set the hammer (1) into a
motion counter to the force of the spring mechanism (4, 15, 16)
after each impact in order to stress this spring mechanism and,
after the stressing of the spring mechanism (4, 15, 16), these
means (8, 10, 13, 14) abruptly release the hammer (1) again so
that, driven by the spring mechanism (4, 15, 16), it flies toward
the tool (3).
2. The hand machine tool as recited in claim 1, wherein the means
(8, 10, 13, 14) are comprised of a drive mechanism that produces a
frictional engagement with the hammer (1) after an impact has been
imparted, moves it counter to the force of the spring mechanism (4,
15, 16), and then releases the frictional engagement again as soon
as the hammer (1) has reached a certain position in its movement
counter to the force of the spring mechanism (4, 15, 16).
3. The hand machine tool as recited in claim 1, wherein the spring
mechanism (4, 15, 16) is comprised of a pressure reservoir (4),
which is filled with a compressible medium and is situated in the
guide tube (2) on the side of the hammer (1) oriented away from the
tool (3).
4. The hand machine tool as recited in claim 3, wherein a pump (7)
is able to supply compressible medium to the pressure reservoir
(4).
5. The hand machine tool as recited in claim 1, wherein the spring
mechanism (14, 15) is comprised of one or more compression springs
(15) and/or tension springs (16), which is/are supported against
the hammer (1) on the one hand and against a shoulder (5, 17) that
is stationary in the movement direction of the hammer (1) on the
other hand.
Description
[0001] The present invention relates to a hand machine
tool--preferably a hammer drill and/or slide hammer--equipped with
a hammer mechanism, which has a hammer that moves axially back and
forth in a guide tube; a spring mechanism is provided, which exerts
a force on the hammer and can set the hammer into a movement toward
a tool that can be inserted into the hand machine tool.
BACKGROUND OF THE INVENTION
[0002] A compression hammer mechanism of this kind, which executes
repeating hammering movements and is intended for an
electro-pneumatic hammer drill and/or slide hammer of the kind
known from DE 198 10 088 C1, is comprised of an eccentric drive
unit, a piston, and a hammer. These three elements serve to convert
a rotating motion into a hammering motion. The axial back-and-forth
motion of the hammer in a guide tube occurs in the following way:
the piston, which the eccentric drive unit moves forward,
compresses the air cushion between the piston and the hammer, thus
causing the hammer to fly freely toward the tool inserted in the
machine. The hammer imparts its hammering energy to the tool and
from it, receives an impetus in the backward direction. At the same
time, the eccentric drive unit also moves the piston backward,
which produces a certain vacuum in the air cushion between the
piston and the hammer. The moment the piston reaches its reversal
point but the hammer is still flying toward the piston, the air
cushion between the two is compressed, generating a compression,
which, with a renewed forward motion of the piston, then causes the
hammer to fly at an even higher speed in the forward direction
toward the tool. In a compression hammer mechanism of this kind,
the piston and the hammer move with the same frequency. A high
individual hammering energy at a low hammering frequency is not
possible with a hammer mechanism of this kind. The same is true for
a so-called spring buckle hammer mechanism of the kind known from
EP 544 865 B1. In it, an eccentric drive unit sets an angle made of
spring steel into an oscillating motion and this spring steel piece
drives the hammer forward toward the tool or toward an intermediate
anvil provided between the tool and hammer. The recoil energy of
the hammer is stored in the spring buckle and released again during
forward motion as in a pneumatic hammer mechanism.
[0003] The object of the present invention is to disclose a hammer
mechanism of the type mentioned at the beginning, which can be
implemented with the simplest possible technical means and is able
to generate a high individual hammering energy at a low hammering
frequency.
SUMMARY OF THE INVENTION
[0004] The stated object is attained with the characteristics of
claim 1 in that means are provided, which set the hammer into a
motion counter to the force of the spring mechanism after each
impact in order to place this spring mechanism under stress; after
the spring mechanism has been stressed, the means abruptly release
the hammer again so that, driven by the spring mechanism, the
hammer flies toward the tool. Because the hammer is actively moved
counter to the force of the spring mechanism after each impact, a
very powerful energy is imparted to the hammer after it is
subsequently released for a new impact.
[0005] A suitable drive unit for the hammer produces a frictional
engagement with the hammer after an impact has been imparted, moves
it counter to the force of the spring mechanism, and then releases
the frictional engagement again as soon as the hammer has reached a
certain position in its movement counter to the force of the spring
mechanism.
[0006] An advantageous spring mechanism is comprised of a pressure
reservoir that is filled with a compressible medium and situated in
the guide tube, on the side of the hammer oriented away from the
tool. The pressure reservoir can be filled with a gas, for example
air, or also a fluid. The compressible medium--gas or
fluid--remains in the pressure reservoir on a constant basis and
only certain leakage losses from the pressure reservoir need be
compensated for. To that end, a pump can be provided, which
supplies compressible medium to the pressure reservoir to
compensate for leakage losses. The pumping capacity of this pump
can be very low because it only needs to compensate for leakage
losses in the pressure reservoir. Such a pump, which does not take
up much space or weigh much, can be integrated into the hand
machine tool.
[0007] Another advantageous spring mechanism can be comprised of
one or more compression springs and/or tension springs that are
supported against the hammer on the one hand and against a shoulder
that is stationary in the movement direction of the hammer on the
other hand.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows a longitudinal section through a hammer drill
and/or slide hammer equipped with a hammer mechanism and a spring
mechanism embodied in the form of a pressure reservoir and
[0009] FIG. 2 shows a longitudinal section through a hammer drill
and/or slide hammer equipped with a hammer mechanism and a spring
mechanism embodied in the form of compression/tension springs.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] FIG. 1 shows a longitudinal section through a hand machine
tool equipped with a hammer mechanism. For example, this hand
machine tool is a hammer drill and/or slide hammer. The schematic
depiction of the hand machine tool shows only the hammer mechanism,
which is the subject of the present invention. All other functional
units usually provided in a hand machine tool are not shown.
[0011] The hammer mechanism is comprised in an intrinsically known
way of a hammer 1 that is supported so that it can move in a
reciprocating fashion in a guide tube 2. A tool 3, for example a
drill bit or chisel, is inserted into a tool socket of the hand
machine tool. If the hammer 1 flies forward toward the tool 3, then
the hammer 1 imparts its hammering impetus to the tool 3. Between
the tool 3 and the hammer 1, it is also possible for an
intermediate anvil (not shown here) to be provided in the guide
tube 2, which transmits the hammering impetus from the hammer 1 to
the tool 3.
[0012] The forward motion of the hammer 1 toward the tool 3
inserted into the hand machine tool is generated by a spring
mechanism whose force is directed toward the hammer 1 in the
direction of the forward motion. In the exemplary embodiment
depicted in FIG. 1, this spring mechanism is a pressure reservoir
4, which is filled with a compressible medium and is situated in
the guide tube 2 on the side of the hammer 1 oriented away from the
tool. The pressure reservoir 4 is delimited by the side wall of the
guide tube 2, the hammer 1 sliding in the guide tube, and a back
wall 5 of the guide tube 2 at its end oriented away from the tool
3. A seal 6 is inserted between the hammer 1 and the side wall of
the guide tube 2 and prevents the compressible medium from escaping
from the pressure reservoir 4.
[0013] The compressible medium can be a fluid or a gas. Preferably,
the pressure reservoir 4 is filled with air. In order to compensate
for leakage losses from the pressure reservoir 4, the pressure
reservoir 4 is connected to a pump 7 that can supply compressible
medium to the pressure reservoir 4 in order to compensate for
leakage losses. Since it is only necessary to compensate for
leakage losses of the compressible medium, it is sufficient to
provide a small pump 7 with a low pumping capacity, which can
easily be accommodated in the hand machine tool because of its low
weight and small volume.
[0014] The hammer mechanism has a drive unit, which, after each
impact with the tool 3, sets the hammer 1 into a motion counter to
the force of the spring mechanism, thus stressing the spring
mechanism. The aforementioned drive unit is designed so that after
the stressing of the spring mechanism, it abruptly releases the
hammer 1 again so that, driven by the spring mechanism, the hammer
1 flies toward the tool. Because the spring mechanism is stressed
not only by the recoil force of the hammer 1, but also actively by
the separate drive unit, which exerts a very high stress on it, a
very powerful hammering force is imparted to the hammer 1 upon
release of the spring mechanism. Consequently, a very high
individual hammering energy can be generated, even at a relatively
low hammering frequency.
[0015] In the exemplary embodiment shown in FIG. 1, the
above-described drive unit is embodied as follows:
[0016] The side of the hammer 1 oriented away from the tool 3 is
attached to a rod 8, which extends in the direction of the
longitudinal axis of the guide tube 2 and passes through the back
wall 5 of the guide tube 2. A seal 9 between the rod 8 and the
guide opening in the rear wall 5 of the guide tube 2 prevents
compressible medium from escaping from the pressure reservoir 4.
Outside the pressure reservoir 4, the rod 8 ends in the vicinity of
a driving gear 10, which is rotatable around an axis that extends
perpendicular to the longitudinal axis of the guide tube 2. The
shaft 11 of a motor, not shown, sets the driving gear into
rotation, e.g. by means of a parallel shaft gearing (not shown in
the drawing). On the driving gear 10, offset from the rotation axis
12 of the driving gear, a pin 13 is provided, which protrudes from
the driving gear 10 perpendicular to the plane of the drawing. The
end of the rod 8 oriented toward the driving gear 10 is embodied in
the form of a hook 14 so that when the driving gear 10 rotates, the
pin 13 can travel into the hook 14. If the hammer 1 is moving
backward after striking the tool, then the rod with the hook 14
slides toward the driving gear 10. The pin 13 of the rotating
driving gear 10 slides into the hook 14 and carries the rod 8 with
the hammer 1 toward the driving gear 10--clockwise in the exemplary
embodiment--so that the hammer 1 moves toward the back wall 5 of
the guide tube 2, thus causing the medium in the pressure reservoir
4 to be compressed. This results in a sharp increase in the
pressure on the hammer 1 toward the tool 3. As soon as the driving
gear 10 has completed a half rotation and the pin 13 has thus
reached a position 13', which is the furthest from the guide tube
2, then the pin 13 slides back out of the hook 14 again. At this
moment, the hammer 1 is released and can move toward the tool 3 to
strike it again, driven by the pressure in the pressure reservoir
4. The rotation speed of the driving gear 10 must be set so that
whenever the hammer 1 is traveling backward after an impact, the
hook 14 at the end of the rod 8 is situated directly over the pin
13 of the driving gear 10.
[0017] In lieu of the drive mechanism described above, which pulls
the hammer 1 by means of the rod 8 counter to the force of the
spring mechanism, it is also possible to provide a drive mechanism
that pushes the hammer 1 counter to the force of the spring
mechanism. In that case, the drive mechanism would have to be
situated on the side of the hammer 1 oriented toward the tool. By
contrast with the drive unit for the hammer 1 described above by
way of example, it is possible to use any other mechanism that
moves the hammer 1 counter to the force of the spring mechanism
after each individual impact in order to stress the spring
mechanism.
[0018] FIG. 2 shows a schematic cross section through a hand
machine tool in which the spring mechanism is not comprised of a
pressure reservoir as in the exemplary embodiment of FIG. 1, but
instead, one or more tension and/or compression springs are used.
Aside from the spring mechanism, all other functional elements are
the same as in the previously described exemplary embodiment of
FIG. 1 and are also provided with the same reference numerals in
FIG. 2 as in FIG. 1.
[0019] As shown in FIG. 2, the chamber of the guide tube 2 between
the hammer 1 and the back wall 5 of the guide tube contains a
compression spring 15, which rests against the back wall 5 of the
guide tube 2 at one end and against the hammer 1 at the other.
Alternatively to this compression spring 15 or in addition to it,
it is also possible to provide a tension spring 16 on the side of
the hammer 1 oriented toward the tool 3. This tension spring is
connected to the hammer 1 at one end and is connected to a shoulder
of the guide tube 2 at the other. Instead of only one compression
spring 15 and/or tension spring 16, it is also possible for several
compression and/or tension springs to be used, which impart the
required hammering force to the hammer 1.
* * * * *