Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR PREVENTING SLIPPERINESS OF A
ROADWAY OR EQUIVALENT BY MEANS OF A FRICTION MATERIAL OR
FRICTION SURFACE
s The present invention relates to a method and apparatus as defined in the
preamble of claim 1 for preventing slipperiness of a roadway or equivalent.
The methods used to eliminate slipperiness are based on causing friction
materials, including organic or inorganic materials such as sand, gravel,
to crushed aggregate, expanded clay aggregate, peat, wood chips, sawdust,
etc.,
to adhere to the ground with the aid of water added to it. An adherence
phenomenon or "sticking" occurs when the surface temperature of a passage or
traffic area, such as a road, is below +0°C and friction material
spread onto the
surFace by a dispensing apparatus freezes fast on the ground (road or the
like).
is
By "gluing" the friction material to the. ground surface, it is possible to
use
friction material of finer composition (of smaller granular size) and smaller
layer
thicknesses, thus allowing a larger working area than before to be treated
with
one filling with the same amount of raw material. Friction material particles
2o sticking to the surface as if "glued" are not carried away with the air
currents
generated by vehicles, nor are they moved aside by being stuck to the tire
treads, nor do they flow down to the bottom of ruts; instead, they remain in
place, with the result that their effective service life is longer, allowing
the
number of treatments to be reduced. Using the "gluing" method, the same
2s results can be achieved by using lighter friction materials, e.g. expanded
clay
aggregate or organic materials (sawdust, wood chips, etc.).
Patent specification DE 3732657 discloses a method for improving the friction
of
an ice surface, using a granular, non-water-soluble friction material,
especially
3o sand. The friction material is moistened and heated before being spread on
the
road surface. However, moistening and heating the friction material before
application is a fairly difficult business and requires additional equipment,
which
means additional costs. Heating the friction material also adds to the costs.
~s Patent specification FI 105353 discloses a method for sanding a road or
equivalent, in which method the sand is spread from a moving vehicle over a
desired width, thus producing a sanded road. The sand is caused to adhere to
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the icy ground by heating the sand particles by means of runners moving
behind on the sanded area, which produce a friction and pressure effect on the
ground after the sand has been spread. The sand is thus heated and pressed
into the ice. The method according to this specification also requires
additional
s equipment for heating the sand, which again increases the costs.
The object of the invention is to eliminate the drawbacks of prior art and
achieve
a new type of method and apparatus for preventing slipperiness. The invention
is based on the idea of spreading liquid and/or friction material directly on
the
io ground to form friction areas, such as patches or equivalent, which makes
it
possible to create friction areas of desired form.
An embodiment of the invention is on the principle of spreading no separate
friction material onto the ground at all but forming the friction surface
needed to
is prevent slipperiness by applying a freezable liquid to the ground. The
liquid can
be applied to the ground as patches or equivalent of desired form, so it is
possible to create friction material areas of desired form. Thus, no extra
costs
are incurred due to the use, moistening or heating of friction material, which
would additionally be fairly laborious and require additional equipment, or
due to
2o environmental after-treatment, such as cleaning up, or anti-pollution
measures.
A second embodiment of the invention is based on the principle of spreading
friction material as such onto the ground and applying the liquid needed to
moisten it to the ground separately from the same vehicle or machine. The
2s liquid can be spread on the ground in patches or equivalent of desired
form,
thus allowing to create friction material areas of desired form. In this case,
the
friction material can be spread on the ground directly as such without being
moistened before the spreading, thus reducing the number of work operations
needed before the spreading of the friction material. The method of the
3o invention is simple and reliable. The equipment required is also very
simple.
By using e.g. patch-like friction material areas, it .is additionally possible
to save
friction material and, when desirable, to control the path of movement of a
vehicle running on a slippery road as it is moving on an icy surface.
The features characteristic of the method and apparatus of the invention are
presented in detail in the claims below.
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In the following, the invention will be described in detail by the aid of a
few
examples with reference to the attached drawing, which figure presents an
apparatus according to the invention for preventing slipperiness of roadway or
s equivalent, fitted on a truck.
Example 1
Fig. 1 presents a truck 2 moving on a road 1. Mounted on the truck 2 is an
1o apparatus according to the invention that produces a friction surface
preventing
slipperiness. For this purpose, the apparatus comprises a liquid tank 3
mounted
on the vehicle to store the water/liquid 4 to be used in forming the friction
surface. The liquid tank 3 may be thermally insulated.
is The water/liquid 4 is sprayed onto the surface of the roadway 1 by means of
a
liquid dispenser 5, into which the water/liquid is supplied via a pipe 6. The
dispenser 5 is provided with nozzles 7, by means of which the water/liquid can
be sprayed onto the ground in a desired way, e.g. in the form of patch-like
swells 8 forming an uneven friction surface on the ground 1.
To improve adhesion, it is possible, by using additives or even by mixing the
water with snow taken from outside, to gelatinize the water used as liquid,
thereby improving its drop adhesion properties and shaping on the ground.
2s The exhaust pipe 9 of the vehicle can be provided with a by-pass 10, which
is
so connected to the tank 3 that it produces lost heat for heating them if
necessary. It can also be used to heat the liquid dispenser 5 and the pipe 6.
The driver can control the amount of heat by adjusting the by-pass flow of
exhaust gas by means of a valve 11. The temperature of the waterlliquid
3o supplied can be optimized relative to the effects of weather and external
temperature, even by cooling if necessary. When pressurized spraying is used,
the water/liquid may be under-cooled before being. sprayed.
Example 2
Alternatively, the truck 2 moving on a road 1 as shown in the figure may be
provided with an apparatus according to the invention for spreading a friction
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material, preferably in granular form, preventing slipperiness, such as sand.
For
this purpose, the apparatus comprises a platform on which the sand to be
spread is loaded. In addition, the vehicle is provided with a liquid tank,
mounted
e.g. on the front side of the platform, for waterlliquid to be spread on the
s roadway 1 in connection with the spreading of sand. The liquid tank and also
the platform may be thermally insulated.
In the method of the invention, the sand is spread as such on the roadway by
means of a spreading/scattering device provided in the platform, and cold
io friction material can be used advantageously as it fastens sooner to the
road/ground.
The water/liquid is sprayed onto the surface of the roadway 1 before the
spreading of the sand, by means of the liquid dispenser mounted in front of
the
is spreading/scattering device, water/liquid being supplied into the dispenser
via a
pipe. The dispenser is provided with nozzles, by means of which the
waterlliquid can be sprayed onto the ground in a desired manner, e.g. in
patches, in which case the sand will only stick to the road in the area of
these
patches. This reduces the amount of sand consumed in sanding. Instead of
2o patches it is possible to use stripes etc., making it in some cases
possible to
influence a vehicle moving on the icy surface so as to direct it in a given
direction.
When instead of sand a friction material lighter than water is used, it will
not
2s dive in consequence of momentary melting of the surrounding ice but remains
buoyant in its melting pit, to be again frozen fast, thus behaving in the
desired
manner.
By using organic materials "glued" as friction materials, they can be brushed
3o directly to the green areas in the spring, thus allowing savings to be
achieved in
cleaning and transportation costs.
The exhaust pipe of the vehicle can be provided with a by-pass so arranged in
conjunction with the tank and the platform that it produces lost heat for
heating
3s these if necessary. It can also be used to heat the liquid dispenser and
the pipe.
The driver can control the amount of heat by adjusting the by-pass flow of
exhaust gas by means of a valve. The temperature of the water/liquid supplied
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can be optimized relative to the effects of weather and external temperature,
even by cooling if necessary. When pressurized spraying is used, the
waterlliquid may be under-cooled before being sprayed.
s Example 3
The friction material may also be spread on the ground by means of a patterned
cylindrical roll/roll mat 21 as presented in Fig. 2, whose surface is provided
with
flutings 22 of desired form. A spreading device like this may be of a self-
to propelling type or it may be of a type designed to be hauled behind a
vehiclelmachine. The roll/roll mat may be of a tooling type, in which case the
material used as friction material can be obtained entirely or partly from the
ground.
is It is obvious to the person skilled in the art that different embodiments
of the
invention are not limited to the examples described above, but that they may
be
varied within the scope of the claims presented below.
Thus, the friction material may also consist of e.g. triangular pieces of ice,
which
2o always stick by one side to the ground, optimal adhesion to the moistened
ground being thus ensured, so that no other friction material is needed.
