Abstract:
The present invention relates to a device for working a snow surface, comprising an endless flexible band, snow-working members arranged on the outside of the band, support means for supporting and guiding the band, drive means capable of moving the band around the support means. The invention is characterised in shaping means arranged and designed such as to be capable of changing the shape of the part of the band that is in contact with the snow-surface during work.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to a device for preparing a snow surface in a ski run area, especially for finishing previously formed or worked snow surfaces, like half-pipes, jumps and other complexly shaped snow surfaces. The device is intended to be attached to a work unit, capable of handling the device in a plurality of directions and ways in order to follow the shapes of the snow surface to be finished.  
         BACKGROUND OF THE INVENTION  
         [0002]    For ski resorts, special vehicles are used in preparing the foundation for the ski runs and the cross-country trails. These special vehicles, so called snowgrooming vehicles, are track-driven in order to be able to manoeuvre. They are equipped with snow forming devices that are pulled behind for smoothing the surface. Further they are arranged with hydraulically manoeuvred ploughs in the front for transporting snow, such as to cut off bumps and fill deeper tracks and cavities.  
           [0003]    During recent years the demands on a more varied skiing in the ski runs has increased, in particular with the arrival of snowboard and its utilisers, but also for ordinary skiing. For that the ski run areas have been designed with different “artificial” configurations, such as mogules, jumps and so called half-pipes. The latter is mainly U-shaped runs where the riders go up and down on the sides and perform different tricks and stunts. These designs demand relatively large amount of work to build up and maintain, for which the conventional snowgrooming vehicles are not optimally designed.  
           [0004]    In order to overcome the drawbacks associated with the conventional machines and devices used for creating specially shaped ski-areas, patent application PCT/SE01/00206, discloses a working device comprising an arm rotatably arranged to a stand and that the arm is jointed. The arm is further also slidable in the longitudinal direction for altering the length of the arm. At the end of the arm, a number of different work tools can be attached, such as for example a thrower for removing and forming larger amounts of snow, a preparation device for fine preparation, shovel, work platform, bush cutter, gripping means, and other tools. The stand is designed as an individual self-supported unit that can be releasably attached to a vehicle.  
           [0005]    This makes it very simple to attach and detach the device according to need, which provides a very flexible way of working and which for example provides for a snowgrooming vehicle, which is used in ski run areas for preparing the ski runs, to readily attach the device in order to perform machining and preparations of half-pipes and the like. Due to the design of the arm with its joint and the moving in and out of the outreach, advantages are obtained in that a very good control of the working unit can be achieved regarding the desired forms, radii and the like and in that the working area can be varied from very small protrusions to the really large half-pipes with wall heights of up to 6 meters.  
           [0006]    The device according to PCT/SE01/00206 utilizes according to one embodiment a snow thrower specially adapted for the working and forming of snow surfaces such as half-pipes. This comprises a rotor with teeth designed and arranged such that a very good working is obtained also on very hard packed snow and where the worked snow can be controlled partly for obtaining an even worked surface, partly for removing and placing of the snow to selected places and partly.  
           [0007]    However, the described snow-thrower, that is capable of moving large amounts of snow, is not ideal for finishing work, ie to prepare the shaped surfaces of a ski-area after a days use. These kinds of surfaces, such as half-pipes, often have track-marks, grooves and the like, that have to be removed or smoothed out, which means that it is only the very top layer that has to be worked, and quite often rather small amounts of snow that has to be moved.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0008]    The aim of the present invention is to provide a device that is capable of performing finishing work on previously shaped snow-surfaces, which means that it shall follow the specific shapes previously made, in a simple and effective way.  
           [0009]    This aim is obtained according to one aspect of the invention with a device according to patent claim 1.  
           [0010]    Preferable embodiments of the invention are characterised by the dependent claims.  
           [0011]    According to one aspect of the invention, the present invention discloses a device for working a snow surface, comprising an endless flexible band, snow-working members arranged on the outside of the band, support means for supporting and guiding the band, drive means capable of moving the band around the support means, characterised in shaping means arranged and designed such as to be capable of changing the shape of the part of the band that is in contact with the snow-surface during work.  
           [0012]    According to another aspect of the invention, it is characterised in that the shaping means is capable of changing the curvature of the part of the band that is in contact with the snow-surface during work.  
           [0013]    According a further aspect of the invention, it is characterised in that the shaping means is capable of changing the part of the band that is in contact continuously and steplessly and that the drive means is capable of moving the band in both directions.  
           [0014]    According to yet an aspect of the invention, it is characterised in that it comprises an attachment means for attachment to a manoeuvring means that it is manoeuvrable in at least one degree of freedom.  
           [0015]    The advantages with the device according to the present invention are several. Because the shape of the part of the snow-finishing device that is in contact with the surface to be treated, the form of any previously shaped surface can be followed, and if the shape of the surface changes, it is easy to change the shape, and in particular the curvature, of the snow-finishing device. In that way the snow-finishing device can be used for all types of shaped surfaces, like for instance in half-pipes for snow-boards where parts of the half-pipe is curved while other parts are more or less planar. Of course, the shape of the snow-finishing device need not be adapted only to previously shaped surfaces, but may also be used to form specific shapes. The design of the snow-finishing device makes it ideal for preparing snow surfaces in ski areas that have been ridden on during a day, so that the surfaces are prepared and ready for the next day. Because the snow-finishing device preferably is attached to a work unit that is maneouvrable in at least three degrees of freedom, a very flexible device is obtained with a large work area. Due to the jointed arm arrangement movable along three coordinate axes, complex forms, such as for example the sides of a half-pipe, can be followed in a labour saving and at the same time exact way. When further the snow-finishing device is jointly, and also rotatably, arranged to the work unit, a very exact steering is obtained for optimal result.  
           [0016]    These and other aspects of, and advantages with, the present invention will become apparent from the following detailed description of some embodiments of the present invention and from the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    In the following detailed description of the invention, reference will be made to the drawings, of which  
         [0018]    [0018]FIG. 1 shows a plan view of the device according to the present invention attached to a work unit which in turn is attached to a snow-grooming vehicle,  
         [0019]    [0019]FIG. 2 shows a detailed view of the attachment between the snow finishing device according to the present invention and a manoeuvring means,  
         [0020]    [0020]FIG. 3 shows a side view of the snow finishing device according to the present invention,  
         [0021]    [0021]FIG. 4 shows an end view of the snow finishing device according to FIG. 3, and  
         [0022]    FIGS.  5 - 15  show different positions of the snow finishing device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    The snow finishing device according to the invention is intended to be releasably attached to a work unit for performing work tasks  10 . As is shown in FIG. 1 the work unit comprises a stand  12  arranged with an attachment (not shown) for attachment to the tool attachment arranged in the front of a snow-grooming vehicle  20 . In this context it shall be understood that other machines, such as wheel loaders, can attach the device according to the invention to its tool attachment, if certain work tasks shall be performed that do not require a snow-grooming vehicle.  
         [0024]    Hydraulic attachments (not shown) are arranged between the hydraulic system of the vehicle and the stand  12  via quick couplings.  
         [0025]    On the front transversal beam  16  support members, in this case skis, are arranged.  
         [0026]    A pillar  30  is rotatably attached to the stand  12 . A hydraulic motor (not shown) is attached to the pillar for the turning of this. To the upper end of the pillar a boom  32  is pivotably arranged. At the outer end of the boom  32  a second boom  37 , hereafter named outreach, is jointly arranged, FIG. 1. Between the boom and the outreach a hydraulic cylinder  38  is arranged, which acts on the outreach. The outreach is designed with a support part  41  with a longitudinal compartment. In this compartment an arm  43  is slidably arranged for forward and reverse movement.  
         [0027]    In the outer end of the arm a guide member  40  is arranged, FIG. 2. The guide member comprises an attachment plate  42  pivotably attached to the arm. A hydraulic cylinder  44  is arranged between the attachment plate  42  and the guide member  40 . To the attachment plate  42  a rotation attachment  46  is attached. The rotation attachment comprises a hydraulic motor (not shown) connected to the hydraulic system of the device. To the rotation attachment a first connection plate  50  is arranged, which displays locking bolts  52 . The locking bolts are intended to fit into corresponding recesses in a second connection plate  54  attached to a working unit  60 . When the locking bolts have been inserted in the second connection plate, both connection plates are locked with hydraulically driven locking pistons (not shown).  
         [0028]    FIGS.  5 - 15  show an embodiment of a snow-finishing device  60  according to the invention. It comprises a hollow column  62 . Inside the column a rod  64  is arranged telescopically, which is urged upwards by a compression spring (not shown) arranged inside the column. At the upper end of the rod two pressure wheels  66  are rotatably arranged, one on each side of the rod. On the side of the column an attachment plate  68  is pivotably arranged. A hydraulic piston/cylinder  70  is arranged between the outer edge, as seen from the column, of the attachment plate and the lower part of the column, for enabling a controlled pivoting of the attachment plate in relation to the column.  
         [0029]    A first arm  72  is pivotally arranged to the lower part of the column, to the left in FIG. 3. A second arm arrangement  74 , comprising two parallel arms, is pivotally arranged to the column a distance above the first arm. At the end of the second arm arrangement two support wheels  76  are rotatably arranged on each side of the arm arrangement. A cross-bar  78  is arranged between the end of the first arm  72  and the second arm arrangement. Further, a piston/cylinder arrangement  80  is arranged between the upper part of the column and the outer part of the first arm, stretching between the arms of the second arm arrangement.  
         [0030]    A number of rods  82  are attached pivotally to each other as to form a linkage, where one end of the linkage is pivotally attached to the lower end of the column. The other end of the linkage is connected to the outer part of the first arm via a cross-bar  84 . A further cross-bar  86  is also arranged between the linkage and the first arm at a distance closer to the column. A plurality of sets of wheels  88  are rotatably arranged along the linkage.  
         [0031]    To the right of the column, an identical set of arms, linkages and wheels are arranged as described above, with the exception that a hydraulic drive motor  90  is arranged at the end of the first arm and the second arm arrangement. Instead of two wheels at the end of the arms, as for the left side, there is one drive wheel  92  that is driven by the drive motor. Around the circumference of the drive wheel a number of protrusions  94  are arranged.  
         [0032]    Around the drive wheel  92 , the sets of wheels  88  of the linkages, the pressure wheels  66  and the support wheels  76 , a flexible snow-finishing band  96  is arranged. The snow-finishing band comprises two bands  98  of a material that is flexible in the transversal direction but cannot be extended in the longitudinal direction, like for example rubber reinforced with carbon fibres. A plurality of snow working members  100  are attached to the bands transversal to the longitudinal direction of the bands such that a space is created between the bands. The snow-working members are elongated profiles of metal that in the embodiment shown have a U-shape in cross-section, where the legs of the profiles are directed outwards. The width of the drive wheel and its protrusions are arranged such as the protrusions fit in the space between the bands and are in contact with the profiles so as to thereby drive the snow-finishing band. Inside the snow-finishing band a plurality of guide plates  102  are arranged in order to guide the snow-finishing band in relation to the support wheels and the wheels of the linkage.  
         [0033]    The function of the device will now be described. The device is attached to the connection plate  50  of the guide member  40 . The longitudinal direction of the device will thus be parallel with the extension of the arm of the work unit  10 .  
         [0034]    During use the hydraulic cylinders of the work unit are manoeuvred in order to turn the pillar  30  and turn the boom  32  and the outreach  37 . The guide member  40  at the end of the outreach, FIG. 5, permits a turning of the working unit around the axis  48  by its hydraulic motor and tilting of the snow-finishing device with the help of the rotation attachment  42  and the hydraulic cylinder  44 . The hydraulic motor  45  on the outreach permits in and outgoing movement, i e shortening and extension of the length of the outreach. With the help of the cylinder  70  between the attachment plate and the column, the snow-finishing device may be tilted, also in order to follow the shape of the surface to be treated.  
         [0035]    In all a large spectrum of movement and working area is obtained for the working unit due to the design of the device, where the work area comprises substantially half a sphere. It is therefore very easy to accurately follow the shape of a snow-surface. When a surface is to be finished the drive motor is driven thereby rotating the band. The drive motor can of course have a reverse direction of rotation, where the direction of rotation is chosen by the operator depending on the working conditions.  
         [0036]    The operator can also activate the cylinders between the column and the arms. When the first arm is lifted the second arm arrangement is also lifted due to the cross-bar  78  and further the outer end of the linkage is lifted due to the cross-bar  84 . The intermediate part of the linkage is lifted somewhat less due to the crossbar  86 , which in all creates a curvature of the linkage. The more the arm is lifted the more curved will the linkage become. This enables the operator to continuously and steplessly adapt the underside of the snow-finishing device to the shape of the surface or in order to create a certain shape of the surface. FIGS.  5 - 15  show some of the shapes that the underside of the snow-finishing device can have. The spring-loaded rod  64  with its pressure wheels  66  creates and maintains a tension of the snow-working band during use and during change of shape of the underside of the snow-finishing device. The movable, and not stiff, tensioning of the snow-working band provides a continuous movement of the snow-working band, which prevents packing of snow inside the device, especially wet snow which tends to pack and obstruct the use.  
         [0037]    The rotation of the snow-finishing band causes the snow-working members  102  to scrape the surface, ie to move the top-layer of the surface in the direction of rotation. This can be done in order to fill cracks, grooves and the like marks in the snow surface, or to move small amounts of snow from one place to another. Due to the ability to change the shape of the underside of the snow-finishing device according to the invention continuously and steplessly by the operator, any changes in the shape of the surface can be taken care of easily and quickly. In all, the operator has full control of the finishing work and full freedom to create and maintain any shapes.  
         [0038]    Preferably, all the hydraulic equipment of the snow-finishing device according to the invention are connected via the work to hydraulic system of the snow-grooming vehicle or any other suitable machine.  
         [0039]    It is to be understood that the invention as described above and shown in the drawings only is to be regarded as non-limiting examples of the present invention and that it is defined by the following patent claims.