Patent Description:
Cranes are known, comprising a respective articulated and I or extensible arm predisposed on a motor truck and mainly used for loading and unloading material from and onto a truck body on the truck.

With the aim of safely moving the load, the crane must be stabilised using appropriate devices, called "outriggers", predisposed on the support frame of the truck body and /or on the crane.

The outriggers are usually of the telescopic type, hydraulically activated, and have the aim of preventing a tipping of the machine during the operating steps.

In detail, two cross-members can be provided, arranged perpendicular to the axis of the motor truck and reciprocally joined by a pair of longitudinal members, two shafts being slidably inserted in each of the cross-members, which shafts bear, at distal ends thereof, respective rest feet, mounted on vertically-mobile outrigger jacks.

In practice, during the driving condition, the outriggers are in a retracted configuration, in which they have a minimum lateral dimension with respect to the advancement direction of the truck.

Before the loading and unloading steps, the outriggers must be brought into an extended configuration, in which the respective shafts are extracted from the relative cross-member so as to project at the flanks of the vehicle, and the feet are lowered down to the ground.

Often the machines must be stabilised on a surface, which can have irregularities or be uneven.

In these circumstances, the operator has to make judgement on the levelness of the machines on which the load lift system is mounted, with regards to the horizontal plane ensuring that the vehicle is "levelled" correctly, as a substantial inclination thereof might increase the risk of tipping over during the manoeuvring of the load lifting device. At present, the procedure followed for compensating the uneven level of the frame is the following.

The operator has available a mechanical level mounted on-board the vehicle which indicates the inclination of the vehicle and a radio command with which she or he can regulate the activating of the outriggers, in particular the vertical excursion of the jacks which bear the rest feet.

By walking around the means and performing visual assessments, the operator proceeds by trial and error to modify the thrust of the various outrigger jacks in an attempt to bring the frame into a position as horizontal as possible, and cyclically checking the level to see if the result has been attained.

The known system has some drawbacks, described in the following. Firstly, the effectiveness of the known levelling procedure is largely dependent on the individual abilities of the single operator.

Therefore, an inexpert or barely able operator might not correctly level the vehicle, with a consequent risk of loss of stability of the vehicle during the steps of movement of the load by the crane.

Further, the mechanical levels used in the known systems notoriously have rather high measuring tolerances, even up to three degrees, which results in uncertainty for the operator with regard to whether the vehicle is correctly levelled or not.

The technical task underpinning the present invention is therefore to provide an improved automatic levelling method and system which obviates the drawbacks of the prior art.

<CIT> discloses a levelling system and method according to the preamble of claims <NUM> and <NUM>, and discloses controlling a stroke support by a safety valve and a solenoid valve. Data is detected by horizontal alignment of a carrier body by using an inclination sensor and transmitted to a control unit i.e. programmable logic controller. Control signals are produced based on the transmitted data. Electrical control signals are produced for alignment of the body to a target level by the control unit.

<CIT> discloses a vehicle body levelling device for a working vehicle having outriggers provided at the front and rear of a self-propelled lower running body for stabilizing the vehicle body while in service wherein the inclinations of the vehicle body in the front to rear and left to right directions thereof are detected by means of a front to rear inclination detector and a left to right inclination detector, respectively, and the lengths of the outrigger arms are detected by outrigger length detectors so as to calculate by a controller required amount of extension of piston rods of the left and right jack cylinders provided on the front and rear outrigger.

<CIT> discloses an automatic leveling system for a vehicle supporting an articulable boom system. The automatic leveling system uses a microprocessor to monitor various inputs indicative of the current position of the vehicle and generates electrical drive signals to control the amount of extension of various outriggers extending from the vehicle.

The technical task is attained by the levelling system realised in accordance with claim <NUM> and by the method actuated according to claim <NUM>.

Further characteristics and advantages of the present invention will become more apparent from the following indicative, and hence non-limiting, description of preferred, but not exclusive, embodiments of the system of the invention, as illustrated in the accompanying drawings, in which:.

In detail, the levelling system of the invention is especially destined for use with a self-propelling work machine <NUM> for lifting loads, preferably cranes for trucks.

The invention is preferably used with a hydraulic crane <NUM>, provided with an articulated and/or extensible arm predisposed telescopically on the frame <NUM> (or "chassis") of the truck <NUM> and able to be used for loading and unloading material onto and from the truck body of the truck <NUM>, located on the frame.

For reasons of clarity of understanding of the figures, in the appended tables of drawings the truck body has not been illustrated.

The arm of the crane <NUM> is preferably mounted on a rotating turret located immediately behind the cabin <NUM> and, in turn, at a distal end thereof has a lift hook mounted.

The system of the invention includes a plurality of outriggers <NUM> mobile between a retracted rest configuration and at least an extended use configuration.

Further, the system comprises an activating apparatus <NUM>, preferably of an electro-hydraulic type, such as for example a proportional hydraulic distributor <NUM> mounted on the crane or on the frame <NUM> of the vehicle <NUM> and able to selectively activate the outriggers <NUM> and regulate functioning thereof.

In practice, each outrigger <NUM> can be gradually, in a regulated way, and singly, activated, by means of hydraulic actuators comprised therein.

In the invention, the distributor <NUM> (or other apparatus) is able to receive command signals and can cause passage of the outriggers <NUM> from one configuration to another as a function of the command signals received.

In general, the system of the invention can include a plurality of hydraulic actuators, for example hydraulic cylinders, predisposed for moving the outriggers <NUM> and for moving the arm of the crane <NUM>, subjected to at least a hydraulic distributor <NUM>, in turn subjected to a processing unit <NUM>, of which more in the following.

In the illustrated preferred embodiment, the system includes the use of four outriggers <NUM> predisposed on the support frame <NUM> of the truck body, subdivided into a front pair and a rear pair, thus providing two outriggers <NUM> for each flank of the machine <NUM>.

A case is possible in which only two outriggers <NUM> are present, for example arranged immediately behind the cabin.

Returning to the preferred embodiment of the invention, two cross-members <NUM> can be included, arranged perpendicular to the axis of the truck <NUM> and reciprocally joined by a pair of longitudinal members <NUM>, defining a counterframe fixed above the chassis of the truck <NUM>.

Two telescopic shafts <NUM> are slidably inserted in each of the cross-members <NUM>, which bear, at the distal ends thereof, respective rest feet <NUM>, which are vertically mobile.

More precisely, the shafts <NUM> are preferably located horizontally and the rest feet <NUM> are borne by outrigger jacks <NUM> or other extensible thrust elements, preferably arranged vertically; in detail, each jack <NUM> can be telescopic, preferably has one segment and is located at the distal end of the respective shaft <NUM>.

In still greater detail, the shafts <NUM> are substantially perpendicular to the longitudinal axis of the machine <NUM> and can be substantially mutually coplanar; in practice, they are positioned in a parallel plane to the plane in which the frame <NUM> of the machine <NUM> extends.

The outrigger jacks <NUM> are preferably substantially perpendicular to the relative shafts <NUM>.

Therefore, if the machine <NUM> is rested on a flat ground surface S, the shafts <NUM> of the outriggers are parallel to the ground surface and the jacks <NUM> are perpendicular thereto; if the ground surface is horizontal, then the jacks <NUM> are vertical.

The extraction of the shafts <NUM> and the descent of the feet <NUM> are obviously operated by the above-mentioned actuators when the distributor <NUM> is activated.

As is visible in the appended figures, which illustrate a preferable but not limiting embodiment of the invention, a cross-member <NUM> is located immediately behind the cabin <NUM>, while the other cross-member <NUM> is arranged behind the rear axle.

During the movement of the vehicle <NUM>, the outriggers <NUM> are in a retracted rest configuration, in which they have a minimum lateral dimension with respect to the advancement direction of the truck <NUM>, while, in use, the outriggers <NUM> are in one of the extended working configurations.

Further, the invention can include a radio command device <NUM> (or other portable command device) able to produce and transmit pilot signals as a function of the selections made by the operator <NUM>.

In general terms, the interface of the portable command device <NUM> is configured for enabling a setting of at least a command parameter representing a variation of the configuration of at least an outrigger <NUM> of the system.

The proportional distributor <NUM> is able to singly command the outriggers, by separately regulating the extension of the shafts <NUM> and the descent of the feet <NUM>, together also with the pressure exerted by the jack <NUM> when the feet <NUM> touch the ground surface; therefore, preferably, the radio command <NUM> is configured for independently piloting each outrigger <NUM>, going to regulate the excursion of the shaft <NUM> and the excursion of the rod of the jack <NUM>.

In a case where the command device is a radio command <NUM>, the interface can comprise at least a command lever and, for example, one or more buttons; it does not exclude the possibility that the interface is constituted by a touchscreen display alternatively or in addition to levers and buttons and I or the interface enables vocal commands or includes other means for setting said command parameters.

In the following, for reasons of clarity of illustration and without departing from the general description, reference will be made by way of non-limiting example to a case in which the command device is a radio command <NUM> equipped with command levers for the operation of the outriggers <NUM>.

In an important aspect of the invention, the system includes at least an electronic measuring device of the inclination <NUM>, for example a digital level (represented only schematically in <FIG>), mounted on the frame <NUM> of the machine <NUM> or in any case associated to the frame <NUM>.

In practice, the level <NUM> (or other like device) can be mounted directly on the frame <NUM> or on a rotationally solid element, such as the above-mentioned cross-members <NUM> or even the shafts <NUM> or the crane.

The function of the level <NUM> is to establish the degree of inclination of the frame <NUM>, and therefore instant by instant, in particular with respect to the horizon or the vertical; in the following, reference will be made by way of example to a case where the level <NUM> measures the inclination of the frame <NUM> with respect to the horizon, a datum which can in any case be certainly extracted from the measuring of the inclination with respect to directions that are rigidly solid with the axis of the frame <NUM> or other fixed references with respect thereto.

More in general, the measuring device <NUM> is able to detect the inclination degree of a reference element of the machine <NUM>, which is preferably the support frame <NUM> but can also be the base of the crane or another element solidly constrained to the frame <NUM> itself.

For reasons of illustrative simplicity, in <FIG> this inclination is indicated by angle A, formed between the ground surface S and a lower edge of the frame <NUM>, which is presumed to be straight.

The level <NUM> can be positioned centrally of the frame <NUM>, both in the length direction and in the width direction, with the aim of determining a characteristic inclination value or there can be a plurality of levels distributed on the frame <NUM>, in order to calculate an average value or for also determining torque values; these verifications and calculations are carried out by the processing unit <NUM> connected to the inclination measuring device, whether this is a digital level <NUM> or not.

More precisely, the inclination-measuring device <NUM> is able to produce inclination signals that are a function of the inclination measured, which are directed to the processing unit <NUM> via cabling or radio signals or other transmission means.

The processing unit <NUM> is therefore able to receive and process the inclination signals and comprises a levelling module <NUM> configured for producing said command signals for the distributor <NUM> (or other activating apparatus).

The command signals produced by the processing unit <NUM> are able to modify the extension of the rods of the above-said jacks <NUM> included in the outriggers <NUM> as a function of the inclination A measured.

However, the processing unit <NUM> can be constituted by a single electronic device, including of the type commonly present on this type of machine, suitably programmed for carrying out the functions described. Alternatively, the processing unit <NUM> can be "distributed" and therefore constituted by a plurality of electronic devices.

In general, the processing unit <NUM> can make use of one or more microprocessors or microcontrollers for carrying out the instructions contained in memory modules and in the functional modules thereof; the microprocessors or microcontrollers can further be distributed over a plurality of local or remote calculators that can also constitute a network.

The invention thus enables automatically levelling the work machine <NUM> by means of the outriggers <NUM>, due to the fact that the inclination A can be assessed in real time, with significant precision, and enables compensating the uneven levels or irregularities of the ground surface S on which the machine <NUM> is to be operated.

Before illustrating further preferable specifications of the invention, there follows a brief description of the basic functioning thereof.

The machine <NUM> is brought to the site where the crane is to be used for carrying out the lifting and displacing operations of loads.

The operator commands the opening and the resting of the outriggers <NUM>, for example by means of the above-mentioned radio command <NUM>.

Once the stabilising step has been completed, the automatic levelling step is performed.

If the ground surface S on which the machine <NUM> is not horizontal (as in the case of <FIG>), the digital level <NUM> detects the inclination A and, on the basis of this, the processing unit <NUM> produces command signals which lead the distributor <NUM> to selectively activate the outriggers <NUM> so as to compensate for the unevenness.

More precisely, the outrigger jacks <NUM> which are on the lower side of the machine <NUM> are activated to thrust and thus raise the machine <NUM> up to when the frame <NUM> is horizontal or in any case in an acceptable condition of inclination.

In other words, the outrigger jack <NUM> which is in the lower position is hydraulically activated so that the thrust rod thereof slides perpendicularly to the ground surface S, the adjustment of the pressure with which the jack <NUM> is piloted, and therefore the sliding excursion of the rod, being regulated by the proportional distributor <NUM> as a function of the commands received from the processing unit <NUM>.

The levelling module <NUM> is preferably configured for producing said command signals for modifying the activating of the jacks <NUM>, as long as an absolute value of the inclination A measured is greater than a levelling threshold.

In other words, via a memory module <NUM>, a range of angles of inclination considered acceptable can be preset in the processing unit <NUM>, for example between +<NUM> and - <NUM> degrees and the processing unit <NUM> will continue to command a thrusting action on the jacks <NUM> located lower, up to when the value of the inclination A measured by the digital level <NUM> enters the acceptable range.

It is possible that, with the aim of obtaining the ideal levelling, it might be necessary, together with a thrust of the jacks <NUM> positioned lower, for the reduction of the thrust of the jacks <NUM> positioned higher, with a consequent retraction of the rod bearing the feet <NUM> rested on the ground surface S. The processing unit <NUM> can also include an enabling module <NUM> configured for activating or disabling the levelling module <NUM>.

To be precise, the radio command <NUM> or other portable command apparatus can be provided with an interface selectable by an operator <NUM> for enabling the activating of the automatic levelling step, following the initial stabilisation.

For example, the radio command <NUM> can comprise an appropriate button which enables activating the enabling module <NUM> which, on the evidence of measurements of the level <NUM>, selectively commands the outriggers <NUM>. Further, the invention comprises one or more rest sensors <NUM> (schematically represented in <FIG>), mounted on the work machine <NUM> and able to verify whether one or more of the wheels <NUM> thereof are resting on the ground surface S or are raised, and to produce "grounded" signals as a function of the verifications carried out.

According to the invention, the processing unit <NUM> is able to receive said grounded signals and the above-mentioned enabling module <NUM> is configured for activating or disabling the levelling module <NUM> on a basis of whether said wheels <NUM> are resting or are raised.

In fact, for some types of work machines <NUM>, such as for example cranes for trucks, the reference standard provides that all or some wheels <NUM> (typically the braking wheels) are never separated from the ground surface S during the working steps of the crane.

Therefore, the enabling module <NUM> can be configured for preventing the outrigger jacks <NUM>, during the levelling step, from lifting the machine <NUM> to the point of separating the wheels <NUM> from the ground surface S (either all the wheels or those that must always be grounded).

In practice, following the stabilising step, the processing unit <NUM> proceeds, if necessary, to command the proportional distributor <NUM> so that it can pilot the jacks <NUM> for the compensation of the non-horizontal position of the frame <NUM>, an operation which is concluded either when the frame <NUM> reaches an acceptable level of inclination A (and preferably nil) or before at least one of the wheels <NUM> designated always to remain resting on the ground surface is raised.

The above-mentioned rest sensors <NUM> can be dynamic sensors, for example force sensors associated to the wheels <NUM> and applied for example to the suspension springs or can be sensors measuring the distance, for example using optic or acoustic technology or can be pressure sensors associated to the tyres or others besides.

As mentioned in the foregoing, in the embodiment in which a plurality of levels <NUM> (or like devices) is applied to the frame <NUM>, for example two levels <NUM> at different points of the length of the frame <NUM>, the processing unit <NUM> can comprise a torque module <NUM> configured for calculating the torque of the frame <NUM> about the longitudinal axis thereof.

In this case, the enabling module <NUM> can be enslaved to the torque module <NUM> with the purpose of preventing the levelling operations from leading to an excessive torque of the frame <NUM>, which over time might weaken the mechanical resistance thereof.

Further, an anti-torque module <NUM> can be included, configured for commanding the levelling module <NUM> so that it selectively activates the outriggers <NUM>, and in detail the jacks <NUM>, with the aim of compensating for any strong torque that the frame <NUM> might have following the initial stabilising step.

In a known way, though not in combination with the other characteristics of the invention, a play can deliberately be left between the shafts <NUM> of the outriggers <NUM> and the above-mentioned cross-members, wherein the shafts <NUM> are inserted, or between two segments comprised in the shaft <NUM> itself, which play enables the inclination of the shaft <NUM> in a vertical plane.

In schematic <FIG>, this play is represented between two segments that are a part of the shafts <NUM>, but this is a non-limiting example chosen because it enables a simpler and clearer graphic representation. Owing to the weight, when a shaft <NUM> is extracted from the cross-member <NUM>, and before the jack <NUM> is activated for the purpose of the descent of the foot <NUM>, the shaft <NUM> has a downwards inclination (<FIG>).

Once the stem of the jack <NUM> has been extended up to pressing, with the foot thereof, on the ground surface S, the play is taken up in an upwards direction (<FIG>).

With the application of a sensor <NUM>, the above-described play can be exploited for verifying whether the outrigger <NUM> has been rested on the ground surface S.

In fact, the rest sensor <NUM> can be able to verify when the shaft <NUM> is hanging downwards and when it "loses" the reading when the play is reabsorbed upwards; consider for example a case of a switch applied inferiorly on the outrigger <NUM> which is pressed by the beam when the beam is freely subjected to the force of gravity.

In this case, when there is an interruption of the signal transmitted by the sensor to the processing unit <NUM>, the processing unit <NUM> is informed of the fact that the relative outrigger <NUM> has gone to rest on the ground surface.

In detail, the enabling module <NUM> can be configured for activating the stabilising module only if all the rest sensors <NUM> have interrupted transmission of the signal or send, to the processing unit <NUM>, a signal indicating the fact that the play of the beam has been reabsorbed.

Differently, the rest sensor <NUM> can include detecting when the play of the beam is reabsorbed upwards, transmitting a signal that the resting operation has taken place to the processing unit <NUM>.

In both cases, the enabling module <NUM> is configured for activating/disabling the stabilising module on the basis of signals received from the rest sensors <NUM>.

The invention also relates to a method for levelling a work machine <NUM> able to lift loads and comprising a plurality of outriggers <NUM> mobile between a rest position and at least a working position in which the outriggers can rest on the ground surface S; each outrigger <NUM> includes an extensible thrust element <NUM> able to abut on the ground S.

In practice, the method is destined to perform a levelling of a work machine <NUM> of the above-described type.

The method of the invention can comprise further steps corresponding to the functionality of the components of the system of the invention, including the modules of the processing unit <NUM>.

Claim 1:
An automatic levelling system for a work machine (<NUM>) able to lift loads, comprising:
a plurality of outriggers (<NUM>) mobile between a rest position and at least a working position in which the outriggers can rest on a ground surface (S) so as to stabilise said machine (<NUM>), each outrigger (<NUM>) including an extensible thrust element (<NUM>) able to rest on the ground surface (S);
at least an activating apparatus (<NUM>) able to selectively activate said outriggers (<NUM>), able to receive command signals and able to regulate an extension of the thrust element (<NUM>) of each outrigger (<NUM>) with respect to the ground surface (S), according to said command signals;
at least an electronic measuring device (<NUM>) for measuring an inclination, destined to be associated to a reference element (<NUM>) of the machine (<NUM>), able to measure the inclination (A) thereof and produce inclination signals as a function of the inclination (A) measured;
a processing unit (<NUM>) able to receive said inclination signals and comprising a levelling module (<NUM>) configured for producing said command signals as a function of the inclination (A) measured by said electronic device (<NUM>), the command signals being able to modify the extension of the thrust elements (<NUM>) included in the outriggers (<NUM>); characterised in comprising
one or more rest sensors (<NUM>), destined to be mounted on the work machine (<NUM>) and able to verify whether one or more of wheels (<NUM>) thereof are resting on the ground surface (S) or are raised, and to produce grounded signals as a function of verifications carried out, the processing unit (<NUM>) being able to receive said grounded signals and comprising an enabling module (<NUM>) configured for activating or disabling the levelling module (<NUM>) on a basis of whether said wheels (<NUM>) are resting or are raised.