U.S. patent application number 11/204474 was filed with the patent office on 2006-02-23 for self-propelled device for milling road surfaces.
Invention is credited to Bernd Lemke.
Application Number | 20060039756 11/204474 |
Document ID | / |
Family ID | 35404601 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060039756 |
Kind Code |
A1 |
Lemke; Bernd |
February 23, 2006 |
Self-propelled device for milling road surfaces
Abstract
The invention relates to a self-propelled device for milling
road surfaces with a vertically adjustable chassis, which carries a
steerable travelling mechanism with at least one steering wheel and
a rear pair of wheels with individual wheel drives and a drive unit
for them and for driving a milling unit which is coupled to the
drive unit and comprises a milling roller which extends
transversely to the travelling direction, has a width smaller than
the width of the device and is arranged off-centre with respect to
the device, the traction of at least one wheel being modified in a
way corresponding to at least partial compensation for the moment
acting about the vertical axis of the device during milling.
Inventors: |
Lemke; Bernd; (Moringen,
DE) |
Correspondence
Address: |
ALIX YALE & RISTAS LLP
750 MAIN STREET
SUITE 1400
HARTFORD
CT
06103
US
|
Family ID: |
35404601 |
Appl. No.: |
11/204474 |
Filed: |
August 16, 2005 |
Current U.S.
Class: |
404/94 ;
299/39.4 |
Current CPC
Class: |
B60K 17/356 20130101;
B60K 17/043 20130101; B60K 7/0015 20130101; E01C 23/088 20130101;
B60K 2007/0092 20130101 |
Class at
Publication: |
404/094 |
International
Class: |
E01C 23/16 20060101
E01C023/16 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2004 |
DE |
10 2004 040 135.7 |
Claims
1. A self-propelled device for milling road surfaces, comprising: a
vertically adjustable chassis, which carries a steerable travelling
mechanism with at least one steering wheel and a rear pair of
wheels; a drive unit for driving individual wheel drives for the
wheels; and a milling unit which is driveably coupled to the drive
unit and comprising a milling roller which extends transversely to
the travelling direction of the device, the milling roller having a
width smaller than the width of the device and is arranged
off-centre with respect to the device; wherein the traction of at
least one wheel is modified in a way corresponding to at least
partial compensation for the moment acting about the vertical axis
of the device during milling.
2. The device according to claim 1, wherein the traction of a rear
wheel is modified in a way corresponding to at least partial
compensation of the moment acting about the vertical axis of the
device during milling.
3. The device according to claim 1, wherein the traction of a front
wheel is modified in a way corresponding to at least partial
compensation of the moment acting about the vertical axis of the
device during milling.
4. The device according to claim 1, wherein at least one individual
wheel drive has an adjusting device for the traction of the
associated wheel for the at least partial compensation of the
moment acting about the vertical axis of the device during
milling.
5. The device according to claim 4, wherein the individual wheel
drives are hydraulic axial piston motors connected in parallel, at
least one of which has an adjusting device for the traction of the
associated wheel.
6. The device according to claim 5, wherein the adjusting device
comprises a hydraulically or electrically actuated valve.
7. The device according to claim 1, wherein on one side of the
device at least one individual wheel drive has a gear mechanism
with a transmission which is different from the transmissions of
gear mechanisms of at least two individual wheel drives of wheels
on the other side of the device for at least partial compensation
of the moment acting about the vertical axis of the device during
milling.
8. The device according to claim 1, wherein on one side of the
device at least one wheel diameter is different from the wheel
diameters of wheels on the other side of the device for at least
partial compensation of the moment acting about the vertical axis
of the device during milling.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a self-propelled device for milling
road surfaces.
BACKGROUND OF THE INVENTION
[0002] In the case of small devices for milling road surfaces,
known as compact millers, the milling unit is usually arranged
flush with one side of the device and at a distance from the other
side of the device, since it has a relatively small width in
comparison with the width of the device, corresponding for example
to half the width of the device. Accordingly, the force applied to
the device is offset considerably from the middle. This offset
creates a moment about the vertical axis of the device. This has
the effect that the device has the tendency to be forced out of
line during the milling operation. This can be compensated by
constantly steering against it. However, this leads to a
corresponding operating effort and wearing of the tyres.
[0003] It is also known to alleviate this problem by providing a
swinging-out rear wheel on the side on which the milling unit is
arranged flush with the side of the device, with a relatively large
swing-out lever, so that as a result the milling unit is located
more centrally between the rear wheels when the rear wheel is swung
out. Apart from the fact that this leads to a corresponding width
of the device, it is not always possible to work with the rear
wheel swung out. If milling next to curbstones is intended, this is
only possible with the rear wheel swung in, so that then there is
still the problem that the device has the tendency to be forced out
of line.
SUMMARY OF THE INVENTION
[0004] An object of the invention is to provide a device for
milling road surfaces with which the tendency of the device to be
forced out of line during the milling operation is at least
significantly reduced or eliminated in a simple way.
[0005] The invention therefore relates to a self-propelled device
for milling road surfaces with a vertically adjustable chassis
which carries a steerable travelling mechanism with a front and a
rear pair of wheels with individual wheel drives and a drive unit
for them and for driving a milling unit which is coupled to the
drive unit and comprises a milling roller and a milling gear
mechanism for it, the milling roller extending transversely to the
travelling direction, having a width smaller than the width of the
device and being arranged off-centre with respect to the device. In
such a device, the traction of at least one wheel is modified in a
way corresponding to at least partial compensation for the moment
acting about the vertical axis of the device during milling. This
consequently allows a distribution of the tractive forces on the
individual wheels to be prescribed, to be precise in such a way
that the moment produced during the milling operation about the
vertical axis of the machine is at least partly compensated and the
straight-running of the device is correspondingly improved, even
under high milling loads.
[0006] In particular, a very simple solution is obtained if at
least one of the individual wheel drives has hydraulic axial piston
motors connected in parallel, an adjusting device for the traction
of the associated wheel, with which the distribution of the
tractive forces is influenced in a way corresponding to the at
least partial compensation of the moment acting about the vertical
axis of the device during milling.
[0007] However, it is also possible that at least one individual
wheel drive on one side of the device has a gear mechanism with a
transmission which is different from the transmissions of gear
mechanisms of at least two individual wheel drives of wheels on the
other side of the device for at least partial compensation of the
moment acting about the vertical axis of the device during milling,
or that at least one wheel diameter on one side of the device is
different from the wheel diameters of wheels on the other side of
the device for at least partial compensation of the moment acting
about the vertical axis of the device during milling. However, in
these cases the different traction of the wheels is retained during
the transporting operation of the device, so that straight-running
is adversely affected during the latter. Since the transporting
distances to be covered by the device are small, however, this is
of minor significance.
[0008] Further objects, advantages and embodiments of the invention
may be taken from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be explained below with respect to an
embodiment shown in the attached drawings.
[0010] FIG. 1 schematically shows a self-propelled device for
milling road surfaces in plan view.
[0011] FIG. 2 schematically shows the drive system of the device
from FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0012] The self-propelled device for milling road surfaces that is
represented in the drawings comprises a vertically adjustable
chassis 1, which has a steerable travelling mechanism with a front
and a rear pair of wheels 2 and receives a drive unit 3, for
instance a diesel engine, which drives a pump 4 for hydraulic oil,
for instance an axial piston pump. Also coupled to the drive unit 3
is a milling unit 5, which comprises a milling roller 7, which
extends transversely to the travelling direction, is provided with
milling cutters 6, has a width smaller than the width of the device
and is arranged off-centre with respect to the device, in this case
flush with the right side of the device.
[0013] The device represented comprises a swinging-out, right rear
wheel 2, so that, when the rear wheel 2 is swung out, the axis of
the rear wheels 2 and the axis of the milling roller 7 lie
virtually in a vertical plane. During the transporting operation
and during flush milling, for instance along the edge of curbstones
or the like, the right rear wheel 2 is swung in, since in the
latter case it cannot otherwise run on the road surface.
[0014] During the milling operation, the device is moved on the
road surface with the overall traction exerted by the wheels
2--arrow 8, the milling roller 7 rotating counter to the travelling
direction. As a result of the off-centre arrangement of the milling
roller 7, there is a corresponding off-centre application of force
to the device--arrow 9, which has the effect that a moment about
the vertical axis 10 (running perpendicularly to the plane of the
paper of FIG. 1) of the device--arrow 11--substantially
corresponding to the distance d between the centre longitudinal
plane 12 of the device and the central radial plane 13 of the
milling roller 7 is obtained (the not quite uniform mass
distribution of the device generally being of minor significance),
this moment attempting to force the device out of line.
[0015] As represented in FIG. 2, the pump 4 supplies individual
wheel drives 14, here axial piston motors, that are connected in
parallel with one another with hydraulic oil of equal pressure. The
individual wheel drives 14 are respectively provided with an
adjusting device 15, for instance a hydraulically or electrically
actuated valve, in order to modify the volume of the axial piston
motors by adjusting their swash plate. This takes place for example
by means of a control 16, which has an adjustable throttle control
lever 17.
[0016] If the milling unit 5 is then switched on, for instance by
means of a switch 18, at same time at least one individual wheel
drive 14 is adjusted in a way corresponding to at least partial
compensation of the moment acting about the vertical axis 10 of the
device during milling, for instance in that the volume of at least
one of the axial piston motors is correspondingly modified by means
of the associated adjusting device 15.
[0017] Expediently, the traction is to be reduced here on that side
which is away from the milling unit 5, in the exemplary embodiment
represented the left side, at at least one wheel 2, preferably at
both wheels 2, for instance in that the volume of the associated
axial piston motors is reduced.
[0018] However, it may be envisaged additionally or instead to
increase the traction on the side near the milling unit 5.
[0019] If appropriate, instead of a pair of driveable front wheels
2, the device may also have only a single steerable front wheel 2,
which is not necessarily provided with an individual drive.
[0020] While the invention has been shown and described with
reference to preferred embodiments, it should be apparent to one of
ordinary skill in the art that many changes and modifications may
be made without departing from the spirit and scope of the
invention as defined in the claims.
* * * * *