Field of the invention

The invention relates to a unit for grinding and melting snow. The invention also relates to a system for collecting, grinding and melting snow. Background of the invention

According to prior art, snow that has fallen during winter is ploughed or collected to mounds or directly onto a lorry for removal. For example, a wheel loader or a tractor with front loader is used. Particularly in city centres, urban areas or densely populated areas, snow has to be transported relatively long distances, especially if the snow dumping site is far from the centre. The transportation consumes fuel and binds a lot of resources, transportation capacity and, above all, time. Furthermore, in connection with heavy snowfall, a lot of collecting and transportation capacity is required, which is not in full use at other times, or it has to be acquired from elsewhere, which may increase the costs.

According to prior art, devices have also been developed which melt the collected snow into water. Because the density of freshly fallen snow is typically about 10% of the density of water, a significant reduction of even 90% is achieved in the need for transportation. The need for transportation may be eliminated almost totally, because the melted snow can even be drained in the form of water into a suitable sewer or another suitable place of dumping. The water can even be recirculated, when possible.

Document US 5,953,837 discloses a vehicle provided with equipment for both collecting and melting snow, as well as equipment for collecting melt water and equipment for discharging water. A corresponding vehicle utilizing a snow blower for collecting snow is disclosed in document US 6,305,105 B1 . A corresponding moving working machine is also presented in US 2,893,377 or US 3,150,660. Equipment comprising a show breaker and melting machinery is disclosed in US 2,684,209. Another apparatus is disclosed in US 4,697,572. An apparatus for melting snow may be a separate, stand-alone unit or combined with e.g. a vehicle, as presented in US 2006/0049289 A1 . A separate unit is also disclosed in US 2006/0137677 A1 .

Another snow crusher is disclosed in US 5,199,198 A. A snow melting roller equipped with a burner is disclosed in JP H032018 U.

However, the devices of prior art are not sufficiently efficient in melting snow. Large amounts of snow easily jam the apparatuses, and the application of heat is not efficient to be able to melt even large amounts of snow quickly. Brief summary of the invention

The purpose of the presented solution is to remove the above-described problems of prior art. The unit according to the invention is presented in claim 1 . The system according to the invention is presented in claim 10.

In the presented solution, heat for melting snow is distributed in the snow as efficiently and evenly as possible, so that melting takes place quickly. In par- ticular, a channel system is used, which distributes heat via a rotating roller and its radial structures throughout the snow to be melted or the snow that has already melted in part.

In the presented apparatus construction, it is possible to break up snow and to crush it, when needed, into a sufficiently fine material, resulting in quick and efficient melting of the fine snow by heat. The snow is efficiently mixed and kept finely grained until it melts by the effect of heat. A problem of prior art is that heat is not conducted sufficiently effectively, for example into the inner parts of a lump of snow. This problem is overcome by the present solu- tion. By means of the presented solution, the snow can be kept sufficiently finely ground so that no lumps or mounts can accumulate. In particular, the radial structures of adjacent rollers are used, moving in an intermeshed manner and thereby crushing or breaking up the snow, or keeping it finely ground. The presented solution further involves several steps, particularly rollers placed at different height levels and equipped with radial structures, whereby the snow gradually changes into liquid state by the effect of heat as it moves downwards in the apparatus according to the solution. In every stage, care is taken that the snow is sufficiently finely ground by rotating rollers equipped with radial structures, such as rod-like or bar-like protrusions.

In the presented solution, a separate unit is provided, into which the snow can be fed in a desired way. If necessary, the separate unit may also comprise a tank for melt water, or transferring means for feeding snow into the unit, or a collecting element, into which the snow is dumped and from which the snow is fed into the unit, or a movable and towable chassis, by means of which the unit can be transferred to a desired target site, or a chassis of a vehicle with a cabin, by means of which the unit can be driven to the desired site, or devices for collecting snow and transferring it to unit or a collecting part, such as a snow blower.

The unit is connected to or integrated in other devices, to form a desired system and to connect the desired functions to said system. Description of the drawings

Fig. 1 shows a unit according to the solution, seen from the side but with only its upper section drawn in the figure, as well as in a partial cross-sectional view, to illustrate the roller and its radial structures;

Fig. 2 shows a principle chart of an apparatus, in which the unit of Fig. 1 or Fig. 3 is placed; and

Fig. 3 shows a unit according to the solution seen from the side, and in a cross-sectional view. Detailed description of the invention

Figure 1 shows a unit 1 according to an example, for grinding and, if necessary, also crushing or breaking up and melting snow. It is a separate unit 1 which functions independently or which, in an example, is an integrated element in a system or an apparatus comprising, for example, a separate water tank 14, as shown in Fig. 2. The apparatus may be movable, or it is an independently moving vehicle in which the apparatus is placed. Figure 1 shows the two uppermost stages 2 and 3 of the unit 1 . Figure 3 shows a nearly equivalent unit 1 with three stages 2, 3 and 4, comprising three rollers, two rollers and one roller 5, when seen from above downwards. The unit 1 can be supplemented by adding rollers to the stages, or an apparatus with several separate units 1 can be used. In the presented example, for example the rollers of the stage 2 are all arrayed at the same height level and at regular intervals. In an example, the intervals between the rollers may also vary from that shown, as well as their height position in relation to the adjacent roller. With reference to Figs. 1 and 3, the unit 1 typically comprises a frame 10 or a corresponding bearing structure, to which the other parts are connected. Typically, the unit also comprises a housing 9 needed for protecting or covering the parts. The unit is equipped with a chamber 12, in which the rollers 5 are placed. In the upper part of the frame, a feed opening 1 1 is provided for feeding snow into the unit. The feeding opening 1 1 may be equipped with a necessary number of covers, guide surfaces or funnels for guiding the snow to a desired location, particularly between the rollers. The feeding may be implemented in various ways, for example by tipping or by means of a feed conveyor 16. The unit comprises two or more stages on top of each other, consisting of rollers 5 for mixing and breaking up snow, equipped with several radial protrusions 7. In an example, all the rollers 5 are substantially horizontal and they are rotated around substantially horizontal rotation axes. The rollers 5 are connected to the frame by, for example, suitable bearings, and in this example, the rollers 5 extend through two opposite walls of the chamber 12. The rollers 5 are driven in a desired manner, for example by means of one or more motors, or, for example, by a chain drive. Typically, a hydraulic motor is provided. The unit may be equipped with a hydraulic unit or driving motor of its own, or it can be connected to a working machine, from which it receives mechanically the driving power or pressurized medium for its operation.

The rollers 5 are preferably hollow structures, for example pipes. The hollow structure constitutes a channel system, through which heat from burner devices 6 can be conducted to the protrusions 7 connected to the roller 5. The protrusions 7 extend away from the roller 5. Preferably, the protrusions 7 extend radially in relation to the roller 5, and in an example, they are provided at intervals of about 90°. Several protrusions 7 are arrayed in parallel, for example in a row. Figures 1 and 3 show an example of the array of the protrusions 7, but their number, dimensioning and array may vary from those shown and may vary among different rollers 5. The number as well as the placement and orientation of the protrusions 7 are affected particularly by the fact that the protrusions 7 of adjacent rollers 5 rotate in an intermeshed manner, to break up the snow 17 as effectively as possible. Between the rollers 5, the snow is finely ground by the protrusions 7 and is simultaneously guided downwards as the rollers 5 rotate at a suitable speed. The finely ground snow is melted into water by heat that is evenly distributed in the snow. The protrusions of each roller intermesh efficiently with the protrusions of one or more rollers, which affects the configuration of the protrusions 7. The intervals, distances and/or the rotation and synchronization of the protrusions 7 are arranged in such a way that the protrusions of the rollers do not collide with each other.

The protrusions 7 are preferably hollow structures, for example pipes. The hollow structure makes up a channel system, and the inner part of the structure is in connection with the channel system of the roller 5 for conducting heat to the protrusions 7. The outermost ends of the protrusions 7 are open, or alternatively closed with a structure with one or more holes or openings. The heat is conducted via the end, holes or openings into the snow. In an example, holes or openings are provided merely in the side surfaces of the protrusions 7, or also at the end of the protrusion 7, if necessary. A burner device 6 is placed in at least one end of the roller 5, which is open, for producing heat and guiding it into the roller 5. Preferably, a burner device 6 is placed at each end of the roller 5, to provide all the protrusions 7 with sufficient heat for melting snow. In each stage 2, 3 and 4, one or more rollers 5 are equipped with a burner device 6, depending on the need for heat and the output capacity, at which the finely ground snow is to be melted. Some of the stages may also be without a burner device, if sufficient heat is obtained from the other stages, that is, the protrusions 7. The burner device 6 is, for example, a gas burner whose flame is introduced into the roller 5. The burner device 6 may also comprise a fan or air feeding device to boost the transfer of heat and to feed air into the roller 5, which air becomes warmer and is discharged via the protrusions 7.

In a unit 1 according to the example of Fig. 3, there are three stages on top of each other in such a way that the number of rollers 5 in each stage is equal to or preferably smaller than in the stage above it. The frame and housing of the unit 1 are fitted in such a way that the chamber 12 of the unit 1 tapers downwards. Two opposite walls of the chamber 12, which are parallel with the rotation axes of the rollers 5, converge for example diagonally, in one or more stages. The distance between the protrusions 7 and the walls is fitted as desired in such a way that snow cannot enter the bottom of the unit, past the rollers, to an excessive degree.

In the lowermost stage, in the stage 4 in the example of Fig. 3, preferably all the snow has changed into water which drops onto the bottom 13 of the chamber 12. The bottom 13 of the chamber can be used as a collecting tank, or the water is guided or sucked from the bottom of the chamber into a tank that is separate from the unit 1 or elsewhere in connection with the unit. In an example, the water is drained from the chamber 12 directly to a desired dumping site.

Figure 2 shows some examples of applying the unit 1 and connecting it to other devices, whereby a system or an apparatus is formed, which comprises one or more of the following, such as a collecting part 15, into which the snow is tipped or fed, a transfer device 16 for feeding snow into the unit 1 , for example from the collecting part 15 or elsewhere, for example from a snow blower. Furthermore, a tank 14 for collecting the water formed by melting snow is feasible. The unit 1 , as well as said devices, can be included in a portable apparatus which can be moved to a site where snow is collected. The apparatus may also be movable on wheels of its own, for example a towable trailer. The unit 1 and the necessary other devices can also be placed in a vehicle. The vehicle may also comprise, for example, a snow blower for collecting snow; the snow is conveyed from the blower to the collecting part 15 or directly to the unit 1 . The unit 1 and other devices may also be constructed as a vehicle which is independently movable to a desired site. If necessary, the apparatus can be supplemented with cleaning or filtering devices for melt water, or sieving devices for removing litter from the snow.

The invention is not limited solely to the variants mentioned in the above description or shown in the figures, but it can also be applied within the defi- nitions given in the appended claims.