Self-propelled vehicle particularly for making turns with tight turning radii

A self-propelled vehicle particularly for making turns with tight turning radii, comprising a chassis provided with two driving wheels forming at least one driving portion, and which supports a motor kinematically connected to a motion distribution shaft. A functional connection is provided between the motion distribution shaft and each one of the driving wheels and is individually activatable or deactivatable on command for independent actuation of the driving wheels. A steering adapted to act on the functional connection, the latter comprising, between the motion distribution shaft and at least one of the driving wheels, a respective clutch coupling, activatable or deactivatable by the steering device.

The present invention relates to a self-propelled vehicle particularly for making turns with reduced turning radii.

BACKGROUND OF THE INVENTION

Land vehicles used for excavation work or provided with floor cleaning means are known which are capable of making turns with tight turning radii.

In particular, WO 02/46023 A1 discloses a self-propelled vehicle of the type described above, which has the particular characteristic of having a single driving motor, which can be kinematically connected, by way of functional connection means, selectively to two driving wheels in order to allow to turn the vehicle about the wheel whereto rotation is not transmitted.

These functional connection means are composed, for each driving wheel, by a kinematic connection shaft, which can oscillate, with respect to the structure of the vehicle, about an axis that is parallel and spaced thereto and on which a guiding pulley and a driving pulley are keyed, a first belt connected to a transmission shaft that receives motion from single motor being wound around the guiding pulley and the corresponding driving wheel being connected to the driving pulley by means of a second belt.

In practice, thanks to the oscillation of the kinematic connection shaft, which can be performed by means of appropriately provided control levers, it is possible to vary the tension of the first and second belts and deactivate, if the belts slacken, transmission of motion from the transmission shaft to the corresponding driving wheel. Accordingly, by deactivating the transmission of one driving wheel and keeping the other driving wheel engaged with the single motor, the vehicle is turned about the wheel that is disconnected from the motor and therefore remains idle.

Although this constructive solution is valid from a conceptual standpoint, it has proved to be not fully satisfactory from a practical standpoint, since deactivation of transmission provided by the oscillation of the kinematic connection shaft causes slippage of the belts on the guiding pulley or on the driving pulley, which rather rapidly causes wear of said belts, with a consequent increase in maintenance costs, especially in case of application to cleaning machines, due to the high temperatures reached during their use.

SUMMARY OF THE INVENTION

The aim of the present invention is to eliminate the drawbacks noted above by providing a self-propelled vehicle particularly for making turns with tight turning radii, which thanks to its particular constructive characteristics can offer higher reliability as well as the greatest assurances of safety in operation.

Within this aim, an object of the present invention is to provide a self-propelled vehicle particularly for making turns with tight turning radii that is very easy to use in all of its possible applications.

Another object of the present invention is to provide a self-propelled vehicle particularly for making turns with tight turning radii that has a very simple structure so as to be competitive also from a merely economical standpoint.

This aim and these and other objects that will become better apparent hereinafter are achieved by a self-propelled vehicle particularly for making turns with tight turning radii according to the invention, comprising a chassis, which is provided with two driving wheels, forms at least one driving portion, and supports a motor that is kinematically connected to a motion distribution shaft, functional connection means being provided between said motion distribution shaft and each one of said driving wheels, said functional connection means being individually activatable or deactivatable on command for independent actuation of one driving wheel with respect to the other, and steering means that are adapted to act on said functional connection means, characterized in that said functional connection means comprise, between said motion distribution shaft and at least one of said driving wheels, a respective clutch coupling, which can be activated or deactivated on command by way of said steering means.

In the examples of embodiments that follow, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other examples of embodiments.

Moreover, it is noted that everything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, the vehicle according to the invention, generally designated by the reference numeral1, comprises a chassis2, on which at least one driving portion3for the user is provided. The chassis2supports, so that it can rotate substantially about a same axis, two driving wheels4, which are arranged for example at the rear of the vehicle1with respect to its forward travel direction.

A motor5is further mounted on the chassis2and is for example of the electric type and preferably of the permanent-magnet type, so that it is possible to reverse the direction of rotation of its output shaft. It should be noted that the motor5can also be constituted by an internal-combustion engine.

With reference to the example of embodiment shown in the figures, the chassis2is formed by a plurality of parts and in particular comprises a base2awhereto a support2bis fixed which is designed to support the motor5, in a per se known manner.

The motor5is kinematically connected to a motion distribution shaft6, which is supported so that it can rotate about its own axis, preferably with the interposition of appropriately provided bearings7and8, on the chassis2and more specifically on the support2b, according to the illustrated example.

For example, the motor5is connected to the motion distribution shaft6by means of a belt9, which transmits motion from a first pulley (not shown), which is keyed to the output shaft of the motor5, to a second pulley10, which is keyed to the motion distribution shaft6.

The motion distribution shaft6is designed to provide rotary motion to the two driving wheels4independently of each other by way of functional connection means, which can be activated or deactivated individually on command by way of steering means in order to steer the vehicle1.

According to the invention, said functional connection means comprise a clutch coupling, generally designated by the reference numeral12, which is interposed between the motion distribution shaft6and one of the driving wheels4. Preferably, a respective clutch coupling12is provided between the motion distribution shaft7and each driving wheel4.

Generally speaking, each clutch coupling12is conveniently composed of a first coupling portion13, which is rigidly coupled to the motion distribution shaft6, for example by using keys or another type of coupling, and a second coupling portion14, which is fitted around the motion distribution shaft6and can slide axially along the motion distribution shaft6though being rigidly coupled thereto in rotating or for joint rotation therewith about its axis. The second coupling portion14in fact is provided with a through hole14a, which has a slotted profile and mates with a slotted portion formed on a sleeve13a, which constitutes an axial extension of the first coupling portion13.

Advantageously, the functional connection means further comprise a mechanical motion transmission between each clutch coupling12and the respective driving wheel4.

Conveniently, said mechanical motion transmission is constituted by a toothed pulley15, which is fitted so that it can rotate about the motion distribution shaft6and can slide axially along the motion distribution shaft6. More particularly, the toothed pulley15is interposed between the first coupling portion13and the second coupling portion14and is advantageously associated, so that it can rotate about its own axis, with the sleeve13aof the first coupling portion13, for example by interposing a roller bearing16. The toothed pulley15is connected, by means of a chain17, to a sprocket18, which is arranged coaxially with respect to a respective driving wheel4and is rigidly rotationally coupled thereto.

Conveniently, said steering means comprise actuation means19, which are functionally connected to a pusher20, which is designed to act on the second coupling portion14in order to produce its axial sliding along the motion distribution shaft6from a deactivation position, in which said second coupling portion14is spaced and therefore disengaged from the toothed pulley15, to an activation position, in which the first coupling portion13and the second coupling portion14are coupled, on opposite sides, to the toothed pulley15, so as to rotationally associate the toothed pulley15with the motion distribution shaft6.

Advantageously, a first clutch element21is interposed between the first coupling portion13and the toothed pulley15and a second clutch element22is interposed between the second coupling portion14and the toothed pulley15. The first and second clutch elements21and22are made of a material that has a high friction coefficient, such as for example the material commercially known as brake lining or other similar material. The presence of the first and second clutch elements21and22ensures effectively, during activation of the clutch coupling12, mating with limited slippage of the first coupling portion13and of the second coupling portion14on the two opposite faces of the toothed pulley15.

Conveniently, the actuation means19are also functionally connected to a braking device23of a respective driving wheel4, for substantially simultaneous activation or deactivation of the clutch coupling12and of the braking device23. Said braking device23can be for example a drum brake or a brake of any other kind.

Advantageously, the pusher20comprises an annular body, which is arranged so that it can slide around or on the motion distribution shaft6for example by interposing a centering ring25. Conveniently, a spacer26and a thrust bearing24are interposed between the pusher20and the second coupling portion14.

Conveniently, the actuation means19comprise a fork-like element28, which rotatably supports, with an end of its own arms28aand28b, the pusher20at two diametrically opposite regions of its lateral outer surface. In particular, in an intermediate portion of its arms, the fork-like element28is pivoted to the chassis2about a pivoting axis, which is formed by a pivot29that is substantially perpendicular to the motion distribution shaft6, so that when the fork-like element28is rotationally actuated about its pivoting axis it can produce the sliding of the pusher20in one direction or the other along the motion distribution shaft6.

Advantageously, one of the arms of the fork-like element28(by way of example the arm28a) is connected articulately, at its own end that is arranged opposite the end at which it is associated with the pusher20, to an actuation tension member36, which in turn acts on a respective braking device23so that a rotation of the fork-like element28in one direction or the other about its own pivoting axis can be converted into an activation or deactivation of said braking device23.

Conveniently, the sliding motion of the pusher20along the motion distribution shaft6, in the direction that causes the engagement of the second coupling portion14with the toothed pulley15, is elastically biased by elastic return means27, which act on the actuation means19. Advantageously, said elastic return means27are adapted to also bias the transition of the braking device23from its activation condition to its deactivation condition.

In a preferred example of embodiment, the actuation means19further comprise an actuation bar30, which is pivoted, at one of its longitudinal ends, to the end that lies opposite the end that is connected to the pusher20of an arm (for example the arm28b) of the fork-like element28and is connected, at its opposite longitudinal end, to an end of a control lever31by means of an appropriately provided kinematic connection32.

The control lever31is pivoted, in an intermediate portion, to the chassis2about an axis that is substantially perpendicular to its longitudinal direction and has, at its end that is opposite to the end connected to the actuation bar30, a control handle31a.

Conveniently, the angular strokes of the control lever31are controlled by said elastic return means27, which are preferably adjustable and are connected by a spring33, which is fitted coaxially to a bar34, which acts on the kinematic connection32and is arranged between an abutment35, which is rigidly coupled to the chassis2, and a shoulder, which is associated with the bar34and can move along it with respect to the abutment35, in order to adjust the pretension of the spring33.

More particularly, the elastic return means27tend to keep the control levers31in a substantially vertical inactive position, in which the driving wheels4are both disconnected from the motion distribution shaft6and therefore from the motor5due to the deactivation of the clutch couplings12, and are both locked in their rotation by the respective braking device23, so that in this situation, even when the motor5is on, the vehicle1remains motionless.

Advantageously, devices for controlling the motor5, of a per se known type, are provided at the driving portion3; by virtue of said means, it is possible to switch the motor5on or off, change its rotation rate, and optionally also reverse its motion.

Preferably, the vehicle according to the invention is further provided with at least one self-orientating castor50, which is mounted for example at the front on the chassis2preferably so that it can rotate freely about a substantially vertical axis in order to allow easy driving of the vehicle1, avoiding excessive sliding over the ground.

Operation of the vehicle according to the invention is as follows.

When the user does not act on the control levers31, the elastic return means keep said control levers31in a substantially vertical inactive position. In this situation, as mentioned above, the clutch couplings12are deactivated and the braking devices23of the driving wheels4are in the activation condition, and therefore the driving wheels4are both uncoupled from the motor5and are rotationally locked.

If the user wishes to actuate forward straight travel, he acts (while the motor5is on) by moving for example backwardly the actuation handle31aof both control levers31. The consequent angular movement of the control levers31is converted by means of the actuation bars30, into a rotation of the fork-like elements25, which at the same time produces the sliding of the pushers20in the direction that causes the engagement of the second coupling portions14with the toothed pulleys15and the coupling of the toothed pulleys15with the first coupling portions13and the deactivation of the braking devices23of the driving wheels4. In this situation, therefore, both driving wheels4are functionally connected to the motor5at the same rotation rate and therefore the vehicle according to the invention moves forward along a straight path.

If the user wishes to make the vehicle turn for example to the right, while keeping the control lever31that is arranged to the left in a backward position, he moves the control lever31that is arranged at the right to the substantially vertical inactive position. This movement of the right control lever leads to a rotation of the fork-like element28that is connected thereto in the direction that produces both the deactivation of the clutch coupling12that is interposed between the motion distribution shaft6and the driving wheel4arranged on the right, by virtue of the disengagement of the corresponding second coupling portion14from the corresponding toothed pulley15, and the simultaneous activation of the braking device of the driving wheel4arranged on the right. In practice, the disengagement of the coupling portion14from the corresponding toothed pulley15causes the toothed pulley15, by no longer being rigidly rotationally coupled to the motion distribution shaft6, to no longer transmit, by means of the chain17, the rotary motion to the right driving wheel4, which due to the simultaneous activation of its braking device is stopped. Since the left driving wheel4is still engaged with the motion distribution shaft6, it still has a given rotation rate, which allows the vehicle according to the invention to turn right about the right driving wheel4, which by having a nil rotation rate in practice acts as a pivot, and therefore the vehicle, according to the invention, turns to the right with a tight turning radius.

The same operation performed with the control lever31that is arranged on the left allows the vehicle to turn left.

Moreover, if the user wishes to operate the vehicle in reverse, he activates the control device that actuates reversal of the rotation of the output shaft of the motor5and moves backwardly both control levers, if he wishes to travel along a straight path, or a preset control lever31, if he wishes to turn in reverse.

It should be noted that if the user leaves the control levers31, said levers, by way of the elastic return means, move automatically to the inactive position, with consequent disengagement of the motion distribution shaft7from the driving wheels and braking of said driving wheels, to the full benefit of safety. Moreover, thanks to the optional possibility of adjustment of the elastic return means, it is possible to vary the intervention times of the braking devices23, with the consequent possibility to vary the space required by the vehicle to brake if the control levers31are released.

For the sake of completeness in description, it should also be added that in a preferred embodiment, each kinematic connection32comprises a pivot40, which is supported so that it can rotate about its own axis by the chassis2and is arranged so that its axis is substantially parallel to the motion distribution shaft6. Two connecting arms protrude laterally, with respect to the axis of the pivot40and on opposite sides, at the ends of said pivot40; one connecting arm, designated by the reference numeral41in the figures, is articulated to the actuation bar30and is connected to the bar34, and the other connecting arm (not shown in the figures) is rotatably connected to one end of a connecting linkage (also not shown in the figures), which in turn is rotatably connected at its other end to the end portion that lies opposite the control handle31aof a respective control lever31.

It should be noted that with this constructive solution of the kinematic connections32, when the user pushes forward both control levers31the straight forward travel of the vehicle is actuated by the activation of the clutch couplings12and by the simultaneous deactivation of the braking devices23of both driving wheels4. When instead the user pushes both control levers31backwardly, he actuates the quick braking of the vehicle1, causing the disengagement of the clutch couplings12and the activation of the braking devices23of both driving wheels4. To turn for example to the right, in this case the user has to therefore keep the control lever31that is arranged to the left in a forward position and push backwardly the lever that is located on the right, so as to lock rotationally the right driving wheel4and keep the left one in motion. To turn to the left, one of course proceeds in reverse to what has been described above. Finally, it should be noted that even with this constructive solution, if the user leaves both control levers31, said levers, by virtue of the elastic return means, automatically return to the vertical position, causing gradual braking of the vehicle1.

All the characteristics of the invention described above as advantageous, convenient or the like, may also be omitted or be replaced with equivalents.

The individual characteristics described with respect to general teachings or to particular embodiments may all be present in other embodiments or may replace characteristics in these other embodiments.

In practice it has been observed that the invention achieves, in all of its embodiments, the intended aim and objects.

In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to requirements and to the state of the art.

All the details may further be replaced with other technically equivalent elements.

The disclosures in Italian Patent Application No. VR2004A000079 from which this application claims priority are incorporated herein by reference.