U.S. patent application number 10/489443 was filed with the patent office on 2004-12-16 for ground surface cutting device.
Invention is credited to Rettenweber, Alfred, Steffen, Michael.
Application Number | 20040251730 10/489443 |
Document ID | / |
Family ID | 7699119 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040251730 |
Kind Code |
A1 |
Steffen, Michael ; et
al. |
December 16, 2004 |
Ground surface cutting device
Abstract
The invention relates to a ground surface cutting device
comprising: a cutting motor for rotationally driving a cutting
tool; an advancing device for displacing the cutting tool with an
advancing speed relative to the ground surface, and; a rotationally
speed measuring device for measuring an actual value for the
rotational speed of the cutting tool or of the cutting motor. The
actual value is evaluated by a control device and is compared with
a predetermined set value. The control device controls the
advancing device and changes the advancing speed based on a
variation of the actual value from the set value.
Inventors: |
Steffen, Michael; (Munchen,
DE) ; Rettenweber, Alfred; (Munchen, DE) |
Correspondence
Address: |
BOYLE FREDRICKSON NEWHOLM STEIN & GRATZ, S.C.
250 E. WISCONSIN AVENUE
SUITE 1030
MILWAUKEE
WI
53202
US
|
Family ID: |
7699119 |
Appl. No.: |
10/489443 |
Filed: |
August 9, 2004 |
PCT Filed: |
September 12, 2002 |
PCT NO: |
PCT/EP02/10254 |
Current U.S.
Class: |
299/1.05 |
Current CPC
Class: |
B28D 1/045 20130101;
E01C 23/0933 20130101 |
Class at
Publication: |
299/001.05 |
International
Class: |
E21C 035/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2001 |
DE |
101 45 465.1 |
Claims
1-10. (Cancel)
11. A ground cutting device, comprising: a travelling mechanism; a
cutting motor supported by the travelling mechanism for
rotationally driving a cutting tool; and having an advancing device
for moving the cutting tool at an advancing speed relative to the
ground; wherein a rotational speed measuring device for measuring
an actual value of the rotational speed of the cutting tool or of
the cutting motor, and by a control device for comparing the actual
value measured by the rotational speed measuring device with a
predetermined desired value, and for changing the advancing speed
in dependence upon a deviation from the actual value and desired
value.
12. A ground cutting device as claimed in claim 11, wherein the
control device is formed in such a manner that it reduces the
advancing speed if the actual value of the rotational speed is less
than the desired value and that it increases the advancing speed if
the actual value is greater than the desired value.
13. A ground cutting device as claimed in claim 11, wherein the
desired value can be changed manually in dependence upon operating
parameters, wherein the operating parameters are parameters from
the group including the material which has been cut, the efficiency
of the cutting tool, the cutting depth, the nominal rotational
speed of the cutting motor.
14. A ground cutting device as claimed in claim 11, wherein the
travelling mechanism can be displaced relative to the ground by the
advancing device.
15. A ground cutting device as claimed in claim 11, wherein the
advancing device comprises an advancing motor which can be actuated
by the control device.
16. A ground cutting device as claimed in claim 11, wherein the
control device can be switched off and the advancing speed can be
adjusted either by manually pushing the ground cutting device or
manually specifying an advancing speed desired value for the
advancing device.
17. A ground cutting device, comprising: a travelling mechanism; a
cutting motor supported by the travelling mechanism for
rotationally driving a cutting tool; and having an advancing device
for moving the cutting tool at an advancing speed relative to the
ground; wherein a power measuring device for measuring an actual
value of the power of the cutting tool or of the cutting motor or
of a parameter which is dependent upon the power or corresponds to
the power; and by a control device for comparing the actual value
measured by the power measuring device with a predetermined desired
value, and for changing the advancing speed in dependence upon a
deviation from the actual value and desired value; wherein the
cutting motor comprises a rotational speed control device and/or a
rotational speed limiting device, of which the control activity can
be evaluated by the power measuring device for the purpose of
determining the actual value of the power of the cutting motor.
18. A ground cutting device, comprising: a travelling mechanism; a
cutting motor supported by the travelling mechanism for
rotationally driving a cutting tool; and further comprising an
advancing device for moving the cutting tool at an advancing speed
relative to the ground; wherein a rotational speed measuring device
for measuring an actual value of a parameter which is proportional
to the rotational speed of the cutting tool or of the cutting
motor; and by a control device for comparing the actual value
measured by the rotational speed measuring device with a
predetermined desired value, and for changing the advancing speed
in dependence upon a deviation from the actual value and desired
value; wherein the cutting motor is an internal combustion engine;
the parameter proportional to the rotational speed is an ignition
stroke of an ignition device for the cutting motor, and wherein the
rotational speed measuring device is formed for the purpose of
measuring the actual value with the aid of the ignition stroke.
Description
[0001] The invention pertains to a floor cutter according to the
preamble of patent claim 1.
[0002] Floor cutters of this type have been known for a long time
in the form of floor sawing machines, slit or joint cutter, and are
used to cut asphalt or concrete floors.
[0003] The figure shows a known floor cutter of this type, which
will be explained in more detail below.
[0004] Smaller floor cutters are pushed by hand by the operator,
whereas larger devices are equipped with an automatic self-driven
advancing unit. To this end, usually one or more wheels are driven
mechanically, hydraulically or electrically. The advancement rate
is adjusted by the operator by hand using actuators, either
continuously or in discrete speed steps. In order to get the best
possible results, an optimum advancement rate is required that
depends on four factors. The main factors include the material
composition of the floor to be cut, the capacity and the service
life of cutting tool (the cutting disc), the cutting depth, the rpm
and the torque of the cutting shaft that drives the cutting disc,
as well as the stability and the track precision of the cutter.
[0005] Thus, because there are many factors, it is not easy to
adjust to a favorable advancement rate and to manually maintain it,
even for experienced operators. In particular, a few of the above
parameters can either not be detected by the operator at all or
they can only be detected through secondary effects. For example,
the operator can usually only estimate the rpm of the cutting shaft
by way of the noise coming from the cutting motor that drives the
shaft. This is usually difficult if the operator is wearing a
prescribed hearing protector or if there are other sources of noise
present in the direct vicinity of the workplace. Moreover, in
automatic advancement, the operator has no way to estimate the
advancement force, which is an important parameter that he can feel
directly from the force applied to the handle in floor cutters with
manual advancement.
[0006] If the advancement rate is not optimally adjusted, various
disadvantages can arise: shorter service life of the cutting disc,
increased chance of broken cutting discs, uneconomical or
environmentally unfriendly operating range of the cutting motor,
overloading of the cutter or cutting motor, more time needed to do
the work and poor quality of the work (e.g. uneven cutting
depth).
[0007] Therefore, the objective of the invention is to provide a
floor cutter with which an optimum advancement rate can be
guaranteed at all times.
[0008] According to the invention, the objective is met by a floor
cutter with the features of patent claim 1. Advantageous
developments of the invention are defined in the dependent
claims.
[0009] A floor cutter according to the invention has a power
detector and a controller that is coupled to the power detector.
The power detector detects an actual value for the power applied at
the cutting tool or of the power output at the cutting motor, which
is proportional to the power applied to the cutting tool.
Alternatively, the power detector can also monitor a parameter that
depends on one of the above power values or corresponds to it some
other way. This then provides another reliable indicator.
[0010] The actual value is sent to the controller, which compares
it to a prescribed setpoint value, e.g. one that had been stored at
the factory at assembly. The controller changes the advancement
rate in relation to a deviation of the actual and setpoint
value.
[0011] This makes it possible to adjust the advancement rate
automatically and not manually--either by means of the operator
pushing the floor cutter or manually adjusting the advancement
rate--through the controller. In the control circuit according to
the invention, the power applied to the cutting shaft, i.e. the
power applied to the cutting tool (cutting disc) or the output of
the main drive motor (cutting motor) represents the control
parameter.
[0012] In an advantageous development of the invention, the power
detector has an rpm detector to detect an actual value for the rpm
of the cutting tool or for the rpm of the cutting motor, which is
proportional to the rpm of the cutting tool. Alternatively, the rpm
detector can also monitor a parameter that depends on one of the
above rpm's or that corresponds to one of the rpm's and is thus
also a reliable indicator. The actual value of the rpm is used in
this embodiment instead of the actual value for the power and is
used as a control parameter for the controller. A known torque
characteristic of the cutting motor is that the rpm is a criterion
that corresponds to the physical power output.
[0013] If the advancement rate is too fast or too slow as a result
of external parameters (interference), the rpm of the cutting shaft
normally decreases or increases accordingly. The corresponding rpm
change is monitored by the rpm detector and is evaluated in the
controller. The controller can then increase or decrease the
advancement rate until the cutting shaft returns to the prescribed
setpoint rpm.
[0014] In another embodiment of the invention, the cutting motor
has an rpm controller and/or limiter to maintain a prescribed rpm,
the control activity of which can be evaluated by the power
detector that determines the actual value for the power output of
the cutting motor. This then can also provide a reliable indicator
of the motor load when the motor rpm does not change.
[0015] In a preferred embodiment of the invention, the cutting
motor is an internal combustion engine whose ignition stroke, i.e.
the time difference between ignitions, is used as the criterion for
the motor rpm and thus for the rpm of the cutting shaft and of the
cutting tool. The rpm detector monitors the actual value for the
rpm based on the ignition stroke, which is then forwarded to the
controller.
[0016] In another advantageous embodiment of the invention, the
cutting motor is an electric motor. In this case, it can be
advantageous if the instantaneous current draw of the cutting motor
is evaluated as the criterion for its rpm.
[0017] The setpoint provided in the controller can be permanently
adjusted at the factory. In another embodiment of the invention,
however, it is possible for the operator to change the setpoint
based on changing operating parameters, namely the material of the
floor to be cut, the capacity of the cutting tool, the cutting
depth or the nominal rpm of the cutting motor.
[0018] The controller operates an advancing motor provided in
addition to the cutting motor and that is part of the advancing
unit. This advancing motor moves the frame relative to the
floor.
[0019] The controller can be switched on or off so that the
operator still has the option as before of manually pushing the
floor cutter or of fixing the advancement rate by hand to a value
of his choice.
[0020] The automatic adjustment of the advancement rate reduces the
danger of incorrect operation, in particular by inexperienced
operators. Furthermore, manual control parts that used to be a
necessity can be eliminated. The automatic control system
guarantees better economical and ecological operation of the floor
cutter.
[0021] This and other advantages and features of the invention are
explained in more detail below with the help of an example and with
the aid of the figure.
[0022] The single FIGURE shows a joint cutter used as a floor
cutter.
[0023] A main drive motor is fastened to a frame 1 and serves as
the cutting motor 2. The cutting motor 2 is an Otto motor that
receives fuel from a tank 3. The cutting motor 2 drives a cutting
disc 4 as the cutting tool by way of a cutting shaft, which is not
shown. This cutting disc saws the floor to be worked on in a known
manner. The cutting disc 4 can, for example, be a diamond slitting
disc. Behind the tank 3 is a water feed system 5 that feeds water
to cool the cutting disc 4.
[0024] At the rear of the frame 1 is a rear axle with two rear
wheels 6, only one of which can be seen in the FIGURE. Similarly,
there is a front axle 7 at the front of the frame 1, also with two
wheels 8.
[0025] The rear wheels 6 can be driven by an advancing unit that is
not shown, which has among other things an advancing motor, for
example an electric motor, in addition to the cutting motor 2. The
electric motor that serves as the advancing motor for the rear
wheels can for example be powered by a generator that is driven by
the cutting motor 2.
[0026] There are basically two options for running the joint cutter
when cutting the floor:
[0027] One option is for the operator to push the joint cutter over
the floor using a handle 9. In the process, the operator can change
the advancement rate as desired, taking into account the effective
advancing force in particular (as an indication of the resistance
that opposes the cutting disc 4 during cutting) and the motor rpm,
which he can hear.
[0028] Alternatively, there is the known option from the prior art
of automatic advancement that the operator can switch on using
control element 10. The electric motor on the advancing unit then
drives the rear wheels 6, wherein the advancement rate available to
the operator is essentially held constant in known joint cutters
from the prior art.
[0029] According to the invention, however, an rpm detector and a
controller are provided that enable the advancement rate to be
automatically adjusted and changed. As criterion for the adjustment
of the advancement rate, the controller evaluates the rpm of the
cutting shaft or evaluates a parameter that depends on this rpm,
for example a parameter that is proportional to it. Thus, other
suitable parameters include the rpm of the cutting disc 4 or the
motor rpm.
[0030] The motor rpm can be established by monitoring the ignition
stroke, for example in an internal combustion engine. The
generation of the ignition sparks produces an electrical signal
that can be evaluated by the rpm detector in a simple manner. This
signal is a reliable criterion for the motor rpm.
[0031] If in other embodiments of the invention the joint cutter
has an electric motor as the cutting motor, the evaluation of the
current draw can be applied as the criterion for determining the
motor rpm, for example.
[0032] Of course, any other known option for rpm detection is
suitable to provide the required actual value.
[0033] In the controller, a setpoint value is saved at the factory
that should be maintained when operating the floor cutter. In order
to obtain the best possible results, the motor should always be run
at full load. It is of course possible to control the motor via
rpm, but this not absolutely necessary.
[0034] If the actual advancement rate is too fast, the forces
acting on the cutting disc 4 decelerate the rpm of the cutting disc
4 and thus of the cutting motor 2. If the actual value of the rpm
falls below the prescribed setpoint value, this is recognized by
the controller, which then adjusts the advancing motor of the
advancing unit, thus reducing the advancement rate produced by the
rear wheels 6. This reduces the cutting forces acting on the
cutting disc 4 so that the rpm of the cutting disc 4 can increase
and so that it returns to range of the setpoint rpm again.
[0035] If, however, the forces acing on the cutting disc 4 are too
low, the cutting motor rotates faster so that the rpm reaches the
nominal rpm, which in any case is above the setpoint rpm. Then, the
controller increases the advancement rate, which causes the cutting
forces to increase, thus causing the cutting disc 4 to
decelerate.
[0036] Using the controller, it is possible to continuously
maintain the joint cutter in an optimum operating range in order to
avoid an overloading of the cutting disc 4 and of the cutting motor
2 on the one hand and to facilitate expeditious completion of the
work on the other.
[0037] The advancement mechanism can be switched on or off in a
known manner in order to prevent the floor cutter from getting away
from the operator.
[0038] Also, the controller can be switched off in order to let the
operator either push the joint cutter by hand or--as in the prior
art--to input a constant value for the advancement rate, which is
then maintained independent of the actual loads.
[0039] The embodiment described above uses the rpm as a easy to
monitor and evaluate criterion for the power output to be detected.
However, other parameters can be used that are a criterion for the
power output or load of the cutting motor 2 or cutting disc 4.
* * * * *