U.S. patent application number 10/549135 was filed with the patent office on 2006-08-10 for hand-held electric machine tool comprising a dust collection container and a level indicator.
Invention is credited to Juergen Hesse, Steffen Wuensch.
Application Number | 20060178087 10/549135 |
Document ID | / |
Family ID | 34625566 |
Filed Date | 2006-08-10 |
United States Patent
Application |
20060178087 |
Kind Code |
A1 |
Wuensch; Steffen ; et
al. |
August 10, 2006 |
Hand-held electric machine tool comprising a dust collection
container and a level indicator
Abstract
An electric hand-held power tool is described that has a machine
housing (11) with an integral dust-ejection connection (15) and a
dust collection container (16) attached thereto. To ensure, when
working with the electric hand-held power tool, that the dust
collection container (16) is emptied in time when full, a fill
level indicator is provided that indicates, at the least, the
maximum amount of dust allowed in the dust collection container
(16). The fill level indicator (20) is preferably integrated in the
machine housing (11) and includes a pressure sensor (21) that
measures the pressure in the dust-ejection connections (15), and a
display unt (22) that is actuated as a function of the pressure
measured (FIG. 1).
Inventors: |
Wuensch; Steffen;
(Holzgerlingen, DE) ; Hesse; Juergen; (Waldenbuch,
DE) |
Correspondence
Address: |
Striker Striker & Stenby
103 East Neck Road
Huntington
NY
11743
US
|
Family ID: |
34625566 |
Appl. No.: |
10/549135 |
Filed: |
November 8, 2004 |
PCT Filed: |
November 8, 2004 |
PCT NO: |
PCT/EP04/52841 |
371 Date: |
September 15, 2005 |
Current U.S.
Class: |
451/8 ; 451/344;
451/356 |
Current CPC
Class: |
B23Q 11/0046 20130101;
Y02P 70/10 20151101; Y02P 70/171 20151101; B24B 55/10 20130101;
A47L 9/19 20130101; B23Q 11/0071 20130101 |
Class at
Publication: |
451/008 ;
451/344; 451/356 |
International
Class: |
B24B 49/00 20060101
B24B049/00; B24B 27/08 20060101 B24B027/08; B24B 23/00 20060101
B24B023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 5, 2003 |
DE |
103 56 927.8 |
Claims
1. An electric hand-held power tool with a machine housing (11)
with an integral dust-ejection connection (15) and a dust
collection container (16) attached to the dust-ejection connection
(15), characterized by a fill level indicator (20) that indicates,
at the least, the maximum allowed dust load of the dust collection
container (16).
2. The electric hand-held power tool as recited in claim 1, wherein
the fill level indicator (20) is integrated in the machine housing
(11).
3. The electric hand-held power tool as recited in claim 2, wherein
the fill level indicator (20) includes a pressure sensor (21) that
measures the pressure in the dust-ejection connection (15), the
pressure sensor generating an output value that is proportional to
the measured pressure, and including a display unit (22) controlled
by the output value.
4. The electric hand-held power tool as recited in claim 3, wherein
the pressure sensor (21) is located in the machine housing (11) and
detects the pressure in the dust-ejection connection (15) via a
duct (24) in the machine housing (11) that leads into the
dust-ejection connection (15).
5. The electric hand-held power tool as recited in claim 2, wherein
the display unit (22) is visible on the machine housing (11), being
located preferably above a handle (17) formed on the machine
housing (11).
6. The electric hand-held power tool as recited in claim 3, wherein
the pressure sensor (21) is an electromechanical pressure sensor,
with which a pressure chamber (42) bounded by a diaphragm (32) or a
displacement piston (41) is acted upon by the pressure in the
dust-ejection connection (15) and which is preloaded via a spring
(38) against the pressure in the pressure chamber (42), and a
contact member of a break contact located in the circuit of an
electrical display unit (22) is coupled to the diaphragm (32) or
displacement piston (41), the contact member closing when the
diaphragm (32) or displacement piston (41) is displaced to a
specified extent.
7. The electric hand-held power tool as recited in claim 6, wherein
the maximum displacement of the diaphragm (32) or displacement
piston (41) is adjusted such that, when the pressure in the
pressure chamber (42) corresponds to the pressure that exists in
the dust-ejection connection (15) when the dust collection
container (16) is filled to the maximum level, the break contact
closes.
8. The electric hand-held power tool as recited in claim 3, wherein
the pressure sensor (21) is a mechanical pressure sensor with a
displacement piston (41) acted upon by the pressure in the
dust-ejection connection (15), and the display unit (22) is a
device that displays the displacement travel of the displacement
piston (41) as the fill level amount in the dust collection
container (16).
9. The electric hand-held power tool as recited in claim 3, wherein
the pressure sensor (21) is a piezoelectric pressure-measuring
cell.
10. The electric hand-held power tool as recited in claim 1,
wherein a fan wheel (14) of a suction fan is located in the machine
housing (11), the fan wheel (14) drawing in dust from the surface
of a machined workpiece and blowing it into the dust collection
container (16) via the dust-ejection connection (15).
Description
RELATED ART
[0001] The present invention relates to an electric hand-held power
tool according to the definition of the species in Claim 1.
[0002] With electric hand-held sanders in particular, such as
orbital, oscillating or belt sanders, cloth bags, paper bags or
boxes are used to collect the sanding dust, and they are
slid--using an outwardly-projecting inlet connection--onto a
dust-ejection connection that encloses a dust-ejection opening in
the machine housing. While paper bags are designed to be disposable
and to be thrown away with the collected dust, boxes have a dust
collection chamber that, after the box is opened, can be emptied so
the dust collection container can be reused. The inlet connection
leads into the dust collection chamber, and the dust collection
chamber is connected to an exhaust opening that has a dust filter
in front of it.
[0003] It has already been proposed (R.304108=6955) to configure a
dust collection container for an electric hand-held sander as a box
with a retracted, integrated inlet connection and a dust collection
chamber located above the inlet connection. The dust collection
chamber is closed with a removable cover that has an exhaust
opening and a dust filter located in front of the exhaust opening.
The inlet connection is slid onto a dust-ejection connection formed
on the machine housing, thereby resulting in a dust collection
container having a compact design and short overall length.
[0004] The dust collection container fills during the sanding
process. Its ability to take on more dust decreases continually
and, as the suction decreases, more and more dust is released to
the surroundings, which becomes increasingly more unpleasant for
the operator. With belt sanders, the problem also arises that, due
to the very large amount of material removed, the dust collection
container fills up very quickly and, as a result, the operator
usually does not notice that the dust collection container has
become too full until the dust-ejection connection and other
dust-transporting ducts in the device have become clogged. The
device must then be taken apart to be cleaned.
ADVANTAGES OF THE INVENTION
[0005] The electric hand-held power tool according to the present
invention having the features of Claim 1 has the advantage that, by
way of the fill level indicator, the operator is made aware in time
of the need to empty the dust collection container, thereby
preventing the operator from being irritated by dust and preventing
the suction ducts inside the device from becoming clogged.
[0006] Due to the measures listed in the further claims,
advantageous further developments and improvements of the electric
hand-held power tool described in Claim 1 are made possible.
[0007] According to a preferred embodiment of the present
invention, the fill level indicator includes a pressure sensor that
measures the pressure in the dust-ejection connection, the pressure
sensor generating an output value that is proportional to the
measured pressure, the output value corresponding to the current
fill level of the dust collection container. The pressure sensor is
preferably located inside the machine housing and detects the
pressure in the dust-ejection connection via a duct in the machine
housing that leads into the dust-ejection connection. The advantage
of this is that the pressure sensor is housed such that it is
protected from dust, so it cannot get dirty and therefore become
inaccurate, and any type of dust collection container--including
those having different volumes--can be connected to the
dust-ejection connection on the machine housing without needing to
adjust the fill level indicator to accommodate the particular dust
collection container. The fill level indicator can therefore be
used in different types of electric hand-held power tools. In the
case of electric hand-held power tools with a built-in suction fan,
however, the only requirement is that the fill level indicator be
adjusted for the exhaust pressure produced by the suction fan in
the dust-ejection connection.
[0008] Various types of commercially-available sensors can be used
as pressure sensors.
[0009] According to a preferred embodiment of the present
invention, an electromechanical pressure sensor with a pressure
chamber bounded by a diaphragm or a displacement piston is used,
the diaphragm or displacement piston including a contact element of
a break contact. The pressure chamber is acted upon by the pressure
in the dust-ejection connection, and the break contact is located
in the circuit of an electrical display. When the diaphragm is
displaced to a specified extent, the break contact closes and the
display illuminates, indicating that the dust collection container
has reached its maximum fill level.
DRAWING
[0010] The present invention is described in greater detail in the
description below with reference to an exemplary embodiment shown
in the drawing.
[0011] FIG. 1 shows a schematized, semi-longitudinal cross-section
of an orbital sander with a dust collection container and a fill
level indicator for the dust collection container,
[0012] FIG. 2 shows a perspective view of an electromechanical
pressure sensor in the fill level indicator according to FIG.
1,
[0013] FIG. 3 shows a schematized, longitudinal cross-section of
the pressure sensor in FIG. 2,
[0014] FIG. 4 shows a schematized side view of a mechanical
pressure sensor for use in the fill level indicator according to
FIG. 1, as a partial cross-section.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
[0015] The orbital sander shown in FIG. 1 in a semi-longitudinal
cross-section as an exemplary embodiment of an electric hand-held
power tool has a housing 11 in which an electric motor 12 is
accommodated, the driven shaft of which drives a sanding disc (not
shown) via an eccentric gear set. Mounted on the drive shaft is a
fan 13 for ventilating electric motor 12, and a fan wheel 14 of a
suction fan that draws dust produced when the surface of a
workpiece is sanded through the sanding disc and blows it out via a
dust-ejection connection 15 formed on the machine housing 11. A
dust collection container 16 is connected to the dust-ejection
connection 15, which can be designed as a cloth or paper bag, or as
a box with a removable cover. Dust collection container 16 is slid
onto dust-ejection connection 15 via a guide connection 161, and
can be removed from dust-ejection connection 15 to dispose of the
collected dust. Dust-ejection connection 15 is located below a
U-shaped handle 17 integrally formed with machine housing 11. A
push button 18 for switching electric motor 12 on and off is
integrated in handle 17; when electric motor 12 is switched off,
push button 18 extends into the grip opening in handle 17 and can
be actuated using a finger of the hand holding handle 17.
[0016] To ensure that the operator empties dust collection
container 16 filled during the sanding process in time, thereby
avoiding exposure to an unnecessarily large amount of dust, a fill
level indicator 20 is integrated in machine housing 11 that detects
the fill level in dust collection container 16 and alerts the
operator via an optical or acoustic signal at the least when the
maximum allowed fill level has been reached, the signal altering
the operator that dust collection container 16 needs to be emptied
or replaced. Fill level indicator 20 includes a pressure sensor 21
that detects the pressure in dust-ejection connection 15, the
pressure sensor generating an output value that is proportional to
the measured pressure, and it includes a display unit 22 controlled
by the output value of pressure sensor 21. Pressure is detected in
dust-ejection connection 15 via a duct 24 leading into
dust-ejection connection 15, the duct extending in machine housing
11 to pressure sensor 21 and being connected to pressure sensor 21.
In the exemplary embodiment in FIG. 1, duct 24 is designed as an
elastic tube 23 installed in machine housing 11 and being fastened
at one end in a segment 25 located in the center of dust-ejection
connection 15.
[0017] In the exemplary embodiment shown, pressure sensor 21 is
designed as an electromechanical pressure sensor mounted on a
printed circuit board 26 installed in machine housing 11. Further
required components of fill level indicator 20 are mounted on
printed circuit board 26. Electromechanical pressure sensor 21,
which is available as an off-the-shelf product, is shown in a
perspective view in FIG. 2 and in a schematic longitudinal
cross-section in FIG. 3, to illustrate its mode of operation.
Pressure sensor 21 has a housing 27 in which two housing openings
28, 29 are formed. Upper housing opening 28, at the least, as shown
in FIGS. 2 and 3, is enclosed by a connecting tube 30, onto which
tube 23 is slid. A diaphragm 32 is located in housing 27, diaphragm
bounding a pressure chamber 31 in housing 27, housing opening 28
being located in pressure chamber 31. Housing opening 29 leads into
the region in housing 27 behind diaphragm 32. A contact bridge 33
is installed on diaphragm 32, the contact bridge interacting with a
contact carrier 34. Contact carrier 34 has two contact surfaces 35,
36. Each contact surface 35, 36 is contacted on a connecting pin
37, 38 that extends out of the underside of housing 27. Contact
bridge 33, together with contact areas 35, 36 on contact carrier
34, forms an electrical break contact located in the circuit of the
electric display unit 22 (FIG. 1). When contact bridge 33 touches
contact areas 35, 36, the break contact is closed, and display unit
22 illuminates. A compression spring 38 is located between contact
bridge 33 and contact carrier 34, the axial preload of which is
adjustable using an adjusting screw 39 to adjust the travel of
contact bridge 33 to the pressure in dust-ejection connection
15.
[0018] Electromechanical pressure sensor 21 operates as
follows:
[0019] The blower pressure in dust-ejection connection 15 created
by fan wheel 14 is transferred via tube 23 to pressure chamber 31
of pressure sensor 21. As dust collection container 16 fills, the
pressure in dust-ejection connection 15 increases. Diaphragm 32
bulges downward (FIG. 3) and displaces contact bridge 33 against
the return force of compression spring 38 in the direction of
contact carrier 34. Compression spring 38 is adjusted such that, as
a result of the pressure in dust-ejection connection 15 that occurs
when dust collection container 16 is filled to the maximum level,
diaphragm 32 displaces contact bridge 33 so far that contact bridge
33 touches contact surfaces 35, 36 and closes the break contact. As
a result, display unit 22--which is located in machine housing 11
above handle 17 such that it is visible to the
operator--illuminates and indicates to the operator that dust
collection container 16 is full.
[0020] Instead of diaphragm 32, a displacement piston can be
located in housing 27 of pressure sensor 21, the end face of
displacement piston bounding pressure chamber 31. Housing opening
29 in the part of the housing bounded by the back side of
displacement piston is therefore located such that it can not be
closed by the displacement piston, regardless of its position.
[0021] The exemplary embodiment of pressure sensor 21 shown in FIG.
4 is a mechanical pressure sensor that can be used in place of
electromechanical pressure sensor 21. This mechanical pressure
sensor is also commercially available. It has a housing 40 in which
a displacement piston 41 is guided in an axially displaceable
manner. Displacement piston 41 bounds, with one of its end faces, a
pressure chamber 42, and is sealed off from the inside wall of the
housing by a sealing ring 43. Housing 40 has an opening 44 in the
region of pressure chamber 42, opening 44 being enclosed by a
connecting tube 45. Tube 23 leading into dust-ejection connection
15 is slid onto connecting tube 45 so that pressure chamber 42 is
acted upon by the pressure in dust-ejection connection 15. An
indicator bar 46 is mounted on the back side of displacement piston
41 facing away from pressure chamber 42. Indicator bar 46 has
indicator markings 47 and can be seen through a window 48 formed in
housing 40. As the pressure in pressure chamber 42 increases,
displacement piston 41 is displaced further to the right (as seen
in FIG. 4) against the return force of compression spring 49, and
an ever-larger portion of indicator bar 46 becomes visible in
window 48. When maximum pressure is reached in pressure chamber
42--which corresponds to the pressure in dust-ejection connection
15 when collection container 16 is filled to its maximum
level--indicator bar 46 has reached the indicator markings 50 that
signal to the operator that dust collection container 16 urgently
needs to be emptied.
[0022] A piezoelectric pressure-measuring cell can also be used as
the pressure sensor 21 in the fill level indicator 20,
piezoelectric pressure-measuring cell generating an electrical
signal voltage in piezoceramics that is proportional to the
pressure in dust-ejection connection 15, it being possible to use
the electrical signal voltage to control display unit 22.
* * * * *