Patent Description:
The present invention relates to a tracked vehicle for preparing ski slopes.

Generally, a tracked vehicle of the type identified above comprises a chassis extending along a longitudinal axis; a cab mounted on the chassis; a powertrain mounted on the chassis; two drive wheels actuated by the powertrain and adapted to actuate two respective tracks; and tools powered by the powertrain.

When the tracked vehicle is used for preparing particularly steep ski slopes, the tracked vehicle comprises a winch, which is mounted on the chassis and comprises a cable having a free end adapted to be constrained to a fixed point; and a boom configured to guide and selectively orientate the cable of the winch relative to the chassis about a pivot axis.

Generally, the boom is rotated about the pivot axis when the end of the cable of the winch is not anchored to a point external to the tracked vehicle. Generally, when the cable is under tension the boom is left free to orientate itself about the axis, therefore the boom in this configuration is aligned with the portion of cable external to the boom. Usually the boom can be controlled as other implements of the snowgroomer by a joystick provided with buttons and minilevers as disclosed in <CIT>.

When the tracked vehicle for preparing ski slopes operates along very steep slopes and resorts to the use of the winch, it can occur that the trajectory of the tracked vehicle differs from the trajectory set by means of the operation of the drive wheels and of the respective tracks.

Such vehicle behaviour can be attributable to various factors. When the tracked vehicle is structured so that the pivot axis of the boom is relatively far from the centre of gravity of the tracked vehicle, the force exerted by the cable on the tracked vehicle does not pass through the barycentre of the tracked vehicle and applies a yaw torque to the tracked vehicle. <CIT> teaches to provide the snowgroomer with at least one control means for automatically compensating at least one of the cable torque that can be a cable traction force applied by cable winch in relation to the yaw axis.

Whereas, the yaw torque is negligible in the tracked vehicles where the pivot axis of the boom is relatively close to the centre of gravity, at least in a plan representation, therefore these tracked vehicles have negligible yaw moments also when the winch applies a significant force.

Another factor which causes the deviation from the preset direction is the differential track slippage attributable primarily to the different configuration and/or state of the snowpack underlying the two tracks.

In some cases, the differential track grip loss is also induced by the force applied by the cable of the winch. Indeed, since the application point of the cable force is arranged on the contact zone of the tracks on the substrate, the cable applies to the tracked vehicle an overturning moment which tends to unload the track arranged on the opposite side from that where the cable is arranged and to promote the loss of grip of said track.

Regardless of the reason why a loss of grip of a track occurs, it is necessary to correct the trajectory of the tracked vehicle. However, operating the tracks at different speeds so as to correct the trajectory may turn out to be useless precisely because of the different amount of track grip.

An object of the present invention is to manufacture a control device for a tracked vehicle for preparing ski slopes which is capable of mitigating the drawbacks of the known art highlighted herein.

In accordance with the present invention, a tracked vehicle for preparing ski slopes is manufactured, the tracked vehicle comprising:.

In this manner, the operator manages to intuitively and immediately control the direction of the tracked vehicle. The immediacy of vehicle direction control is extremely important when the vehicle is on very steep slopes and at least one track is losing grip.

In particular, the tracked vehicle comprises a control device provided with a sensor for detecting the direction of travel of the tracked vehicle; and a control unit configured to enable the first switch to rotate said boom in the first direction in a forward travel condition and to rotate said boom in the second direction in a reverse travel condition, and enabling the second switch to rotate said boom in the second direction in a forward travel condition and in the first direction in a reverse travel condition.

In this manner, the intuitiveness of the controls is independent of the direction of travel.

The present invention further relates to a method of controlling a tracked vehicle which is free from the drawbacks of the known art.

In accordance with the present invention, a method of driving a tracked vehicle for preparing ski slopes is provided, the method comprising:.

The method provides a driving mode which is extremely intuitive and alternative to the driving of the tracked vehicle traditionally performed by varying the relative speed between the two tracks.

In particular, in order to make the driving of the tracked vehicle intuitive regardless of the direction of travel, the driving method provides for:.

Further characteristics and advantages of the present invention will become apparent from the following description of a non-limiting example embodiment, with reference to the accompanying Figures, wherein:.

With reference to <FIG>, reference numeral <NUM> indicates as a whole a tracked vehicle for preparing ski slopes. The tracked vehicle <NUM> comprises a chassis <NUM>; a track <NUM> (<FIG>); a track <NUM>; a drive wheel <NUM> (<FIG>) and a drive wheel <NUM> independent of each other and coupled to the track <NUM> (<FIG>) and to the track <NUM>, respectively; a plurality of hydraulically actuated tools <NUM> connected to the chassis <NUM>; a cab <NUM> mounted on the chassis <NUM>; and a user interface <NUM> arranged inside the cab <NUM> and comprising driving and control instrumentation.

In particular, the tools <NUM> comprise a tiller <NUM> movably connected to the chassis <NUM>; a shovel <NUM> movably connected to the chassis <NUM>; and a winch <NUM> mounted on the chassis <NUM> to selectively wind out and wind in a cable <NUM> anchorable to a point <NUM> (<FIG>) external to the tracked vehicle <NUM>.

In accordance with a non-limiting embodiment of the present invention, the cab <NUM> is arranged at the front of the tracked vehicle <NUM> and facing the shovel <NUM>. In such configuration, the winch <NUM> comprises a drum <NUM> pivoting about a pivot axis A1 for winding in and winding out the cable <NUM> and is arranged at the rear of the tracked vehicle <NUM>, behind the cab <NUM>.

Furthermore, the winch comprises a boom <NUM>, which is mounted pivoting relative to the chassis <NUM> about a pivot axis A2, and is configured to guide and orientate the cable <NUM>; an actuation system <NUM> (<FIG>) for actuating the boom <NUM> about the given axis A2; and a control device <NUM>.

The control device <NUM> allows implementing the following operating modes also when the cable <NUM> is under tension:.

More specifically, the tracked vehicle <NUM> comprises a support structure <NUM> fixed to the chassis <NUM>, which sustains the drum <NUM> of the winch <NUM> and supports the boom <NUM> in a pivoting manner; and a series of idler pulleys <NUM>, <NUM>, <NUM>, and <NUM> which are mounted in a pivoting manner on the support structure <NUM> and on the boom <NUM> and have the function of guiding the cable <NUM> along a given path.

With reference to <FIG>, the actuation system <NUM> comprises two actuators <NUM> and <NUM> coupled to the boom <NUM> for selectively transmitting to the boom <NUM> respective torques about the pivot axis A2.

In accordance with further embodiments, the number of actuators may vary and should not be understood as limiting the present invention. By way of example, the actuation system <NUM> may comprise one single actuator, two actuators, or four actuators.

With reference to <FIG>, the control device <NUM> receives signals from the user interface <NUM> in order to control the actuation system <NUM> and comprises a joystick <NUM> controllable by said operator U.

With reference to <FIG> and <FIG>, the tracked vehicle <NUM> has a centre of gravity C, which is arranged at a relatively small distance D1 from the pivot axis A2.

With reference to <FIG>, in the described and illustrated case, the actuators <NUM> and <NUM> are supported by the support structure <NUM> and are arranged on opposite sides relative to the boom <NUM>.

In particular, the actuators <NUM> and <NUM> are two-way flow hydraulic motors fed with a pressure variable between a minimum and a maximum value so as to transmit a torque variable between a minimum and a maximum value.

With reference to <FIG>, the actuation system <NUM> comprises a hydraulic circuit <NUM>, which is fed by a pump <NUM>.

The control device <NUM> comprises a pressure modulating valve <NUM> for adjusting the supply pressure for each actuator <NUM> and <NUM> between a minimum and a maximum value; a direction control valve <NUM>; and a direction control valve <NUM>, each of which is configured to selectively shut off power to the respective actuator <NUM>, <NUM> or to supply power to the respective actuator <NUM>, <NUM> in a first flow direction or to supply power to the respective actuator <NUM>, <NUM> in a second flow direction opposite the first flow direction.

In particular, the actuation system comprises control modules <NUM>, <NUM>, and <NUM>, which are configured to control the pressure modulating valve <NUM>, the direction control valve <NUM>, and the direction control valve <NUM>, respectively, depending on the commands given by the joystick <NUM> and the selected operating mode.

The control device <NUM> comprises a sensor <NUM> configured to acquire the direction of travel of the tracked vehicle <NUM>; and a control unit <NUM> to control the control modules <NUM>, <NUM>, and <NUM> depending on the signals emitted by the user interface <NUM> and by the signal acquired by the sensor <NUM>.

More specifically, each control module <NUM>, <NUM>, <NUM> is configured to control the respective valve <NUM>, <NUM>, <NUM> so as to supply the actuators <NUM> and <NUM> with a pressure and a flow direction suitable to the selected operating mode.

The joystick <NUM> comprises two switches <NUM> and <NUM>, in this case two buttons for controlling the pivoting of the boom <NUM> of the winch <NUM> (<FIG>). The two switches <NUM> and <NUM> are arranged in front of the operator, to the right and left of each other relative to the operator, respectively (<FIG>).

In accordance with a variation not illustrated, the two buttons are replaced by one single rocker button with an operating position on the left and an operating position on the right and a neutral position in the centre.

With reference to <FIG>, when the switch <NUM> on the right is operated, the tracked vehicle <NUM> corrects its trajectory by turning to the right.

With reference to <FIG>, when the switch <NUM> on the left is operated, the tracked vehicle <NUM> corrects its trajectory by turning to the left.

With reference to <FIG>, the tracked vehicle <NUM> is moving uphill along a slope by means of the assistance of the winch <NUM>. The cable <NUM> is anchored to the anchor point <NUM> and the boom <NUM> is arranged on the right side of the tracked vehicle <NUM> relative to the direction of travel.

In the illustrated case, the loss of grip of the left track <NUM> causes a variation of the trajectory of the tracked vehicle <NUM>. By operating switch <NUM>, the boom <NUM> is rotated anticlockwise so as to induce a compensating torque acting clockwise about the pivot axis A2 for re-establishing the predefined trajectory.

With reference to <FIG>, the tracked vehicle <NUM> is moving uphill along a slope by means of the assistance of the winch <NUM>. The cable <NUM> is anchored to the anchor point <NUM> and the boom <NUM> is arranged on the left side of the tracked vehicle <NUM> relative to the direction of travel.

In the illustrated case, the loss of grip of the right track <NUM> causes a variation of the trajectory of the tracked vehicle <NUM>. By operating switch <NUM>, the boom <NUM> is rotated clockwise so as to induce a compensating torque acting anticlockwise about the pivot axis A2 for re-establishing the predefined trajectory.

With reference to <FIG>, the tracked vehicle <NUM> is moving downhill along a slope by means of the assistance of the winch <NUM>. The cable <NUM> is anchored to the anchor point <NUM> and the boom <NUM> is arranged on the right side of the tracked vehicle <NUM> relative to the direction of travel.

With reference to <FIG>, the tracked vehicle <NUM> is moving downhill along a slope by means of the assistance of the winch <NUM>. The cable <NUM> is anchored to the anchor point <NUM> and the boom <NUM> is arranged on the left side of the tracked vehicle <NUM> relative to the direction of travel.

In the illustrated case, the loss of grip of the left track <NUM> causes a variation of the trajectory of the tracked vehicle <NUM>. By operating switch <NUM>, the boom <NUM> is rotated clockwise so as to induce a compensating torque acting anticlockwise about the pivot axis A2 for re-establishing the predefined trajectory.

Since in the described configuration of the tracked vehicle <NUM> the distance D1 between the pivot axis A2 and the centre of gravity C is relatively small, the yaw phenomena are negligible and it is not necessary to correct the yaw moment because it is of negligible entity.

With the purpose to allow the free pivoting of the boom <NUM> about the given axis A2, in order to arrange the boom <NUM> aligned with the portion of cable <NUM> external to the boom <NUM>, the operator U of the tracked vehicle <NUM> controls by means of the user interface <NUM>, actuating the pressure modulating valve <NUM> (<FIG>) so as to apply a minimum torque to the boom <NUM> by means of each actuator <NUM>, <NUM> and opposite the minimum torque applied by the other actuator <NUM>, <NUM>.

Claim 1:
A tracked vehicle for preparing ski slopes, the tracked vehicle (<NUM>) comprising:
- a chassis (<NUM>) extending along a longitudinal axis (A);
- a winch (<NUM>) mounted on the chassis (<NUM>);
- a boom (<NUM>) pivoting about a pivot axis (A2) to guide and orientate the cable (<NUM>) of the winch (<NUM>) between the chassis (<NUM>) and the cable anchor point (<NUM>);
- an actuation system (<NUM>) for rotating the boom (<NUM>) about the pivot axis (A2) relative to the chassis (<NUM>) in a first and second direction; and
- a user interface (<NUM>) comprising a first and a second switch (<NUM>, <NUM>) arranged in front of an operator (U) and to the right and left of each other and configured to rotate said boom so as to steer the tracked vehicle (<NUM>) to the right and to the left respectively when the cable (<NUM>) is anchored to the cable anchor point (<NUM>).