The present invention relates to a telescopic boom lift.

Among the many types of self-propelled works vehicles, telescopic boom lifts, i.e., vehicles that allow to act at significant heights with respect to the ground, for example to move bulky goods and equipment or in any case to intervene in various manners at heights otherwise difficult to reach, are known.

Typically, known lifts A (such as the one for which a general diagram of the transmission components is provided in Figure 1) comprise a vehicle or truck mounted on wheels B or tracks, which can move on the ground and directly or indirectly supports at least one telescopic boom, to which various accessories can be associated, depending on the type of intervention that the lift A is called to perform.

Furthermore, in the sub-category of rotary telescopic boom lifts A, the vehicle supports a structure which rotates about a vertical axis, which typically comprises a cab, intended to receive an operator, and a base for the telescopic boom, to which said boom is articulated with its first end.

In some embodiments (such as indeed the one of Figure 1), the vehicle is equipped with a battery pack C which powers an electric motor D responsible for supplying the power required for movement on the ground. Typically, the pack C also powers a second electric motor D' associated with a distributor E which is responsible for moving the telescopic boom and the other moving parts of the lift A.

The use of electric motors D, D' is an increasingly popular solution, due to the growing sensitivity of the market and of institutions to goals such as the reduction of polluting emissions and environmental sustainability, but it is not free from drawbacks.

It should be noted in this regard that usually the electric motor D that moves the vehicle is connected directly to the transmission shaft F, which is responsible for transferring the mechanical energy to the axles G on which the wheels B are mounted (optionally with only the interposition of a gearbox H).

It is also well-known that electric motors D, D' offer low performance at startup: when the vehicle is at standstill and the motor D is started, however, said motor D is in a load condition and therefore the low performance leads to high energy consumption.

This situation is obviously undesirable, particularly in all those situations (which are, moreover, very common) in which the use of the lift A entails frequent stops and (re)starts.

Moreover, when the start occurs uphill or in any case in other particularly demanding conditions, the torque required from the electric motor D is very high, and this forces manufacturers to adopt motors D and associated control means (inverters) that are very expensive and oversized compared to ordinary use.

In practice, therefore, the choice falls on components that significantly increase the overall cost of the vehicle, just to be able to cope with high torque demands at start which, in practice, may occur very rarely.

The aim of the present invention is to solve the problems described above, providing a telescopic boom lift with electric traction that ensures a low energy consumption at vehicle start.

Within this aim, an object of the invention is to provide a telescopic boom lift with electric traction that at start requires a low torque from the respective electric motor, even in the case of an uphill start or in any case in demanding conditions.

Another object of the invention is to provide a lift of low cost, in which the components assigned to electric traction are sized as a function of the usual working conditions.

Another object of the invention is to provide a lift that ensures high reliability in operation.

Another object of the invention is to propose a lift that adopts a technical and structural architecture that is alternative to those of lifts of the known type.

Not least object of the invention is to provide a lift that can be obtained easily starting from commonly commercially available elements and materials.

Yet another object of the invention is to provide a lift having low costs and of assured application.

This aim and these and other objects which will become better apparent hereinafter are achieved by a lift according to claim 1 and by a method according to claim 11.

Further characteristics and advantages of the invention will become better apparent from the description of some preferred but not exclusive embodiments of the lift according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein: Figure 1 is a block diagram of the configuration of the traction and transmission elements in a lift with electric traction of the known type;

Figures 2, 3 and 4 are block diagrams of the configuration of the traction and transmission elements in a lift according to the invention, in three different embodiments; Figure 5 is a schematic view of the epicyclic gear train;

Figure 6 is a lateral elevation view of the telescopic boom lift according to the invention.

With particular reference to the figures, a telescopic boom lift is generally designated by the reference numeral 1 and comprises at least one vehicle 2 with electric traction, which can move over ground (on the road surface, on farmland, in the area of a construction site, or on any other resting surface) by means of movable elements such as wheels 3 and/or tracks.

It should be noted that in this discussion the term "telescopic boom lift" also comprises all self-propelled work machines that are also known in the sector under the name "telescopic handler" or "telehandler.

For everything that will not be described hereinafter, the vehicle 2 can be of the traditional type and chosen so as to correspond to that embodiment (among the many widespread in the industry) that the person skilled in the art would be able to consider best suited for the purpose in each instance.

Furthermore, in order to be able to bear great loads and ensure a suitable support even during interventions at great heights, the vehicle 2 can be provided with stabilizer means 4, which can be also chosen of a known type.

The vehicle 2 supports directly or indirectly at least one telescopic boom 5 adapted to support a work accessory 6.

In well-known ways, the telescopic boom 5 is typically composed of a plurality of segments or extractable rods, which are arranged in series and can indeed be extracted from each other; moreover, on the opposite side with respect to vehicle 2, the free end of the boom 5 can be coupled to the accessory 6 of interest. The accessory 6 can be of any type: in the accompanying figures, by way of example, it has been chosen to show an accessory 6 constituted by a fork, but it could be any other object or tool suitable to the purpose for which one intends to use the lift 1 (and might be also a platform designed to accommodate a person).

The accessory 6 can also be interchangeable, so that it can be replaced at each intervention, as a function of the specific requirements.

The accessory 6 or a set of accessories 6 can therefore be comprised in the lift 1, but the protective scope claimed herein covers also lifts 1 without accessories 6, which can therefore be sourced separately. Moreover, the possibility is not excluded that the lift 1 might be provided with two or more booms 5 which are for example mutually articulated.

Moreover, the vehicle 2 can support directly or indirectly a cab 7 configured to accommodate an operator, typically in order to allow him to control the lift 1. The cab 7 can be integral with the vehicle 2 or can be rotatable about a rotation axis R; in greater detail, in said second embodiment (the one shown by Figure 6) the lift 1 can be a rotary telescopic boom lift, in which the boom 5 and the cab 7 are part of an assembly which can rotate with respect to the vehicle 2, indeed about the rotation axis R. Typically, said assembly comprises a base structure 8 which is supported rotatably by the vehicle 2: the telescopic boom 5 is articulated (about an axis which is horizontal, or parallel to the ground) with a first end to the structure 8, which rigidly supports the cab 7.

It is noted once again that for all the aspects not discussed in the present description, any constructive detail related to the vehicle 2, the stabilizer means 4, the boom 5, the cab 7 and others can be of a known type. In particular, therefore, the person skilled in the art can choose in each instance the equipment and the embodiment deemed most appropriate based on common expertise of the field and as a function of the specific requirements, without in any case abandoning the protective scope claimed herein.

According to the invention, the lift 1 comprises at least one electronic control and management device 9, which is configured to control the rotation rates of at least two primary electric motors 10 (which are mounted on the vehicle 2 or in any case on the lift 1). Each primary motor 10 can be any electric motor of a known type and control can occur in any manner.

The rotation rate of each primary motor 10 means in practice the rate at which the respective output shaft turns, one of the parameters on which the energy or mechanical power that the respective primary electric motor 10 supplies downstream (following the conversion of the electric power with which is supplied) depends.

The electronic device 9 can be of any type, and for example may comprise a control unit or an electronic processor and/or sensors or control systems which cooperate to control the rotation rates and the primary motors 10 in general, particularly for the purposes that will be described better hereinafter. The device 9 can in any case be integrated in the electronic system that is entrusted with controlling the entire lift 1.

Furthermore, the lift 1 comprises at least one transmission shaft 11, which is configured to transmit the mechanical energy provided by the primary motors 10 to the movable elements (for example, therefore, to the wheels 3). The transmission shaft 11 can be for example a cardan shaft, associated at the ends with two universal joints 12 which in turn are designed to transfer the movement to two respective axles 13 on which the wheels 3 are mounted.

In an entirely particular manner, according to the invention the primary motors 10 are connected to the transmission shaft 11 with the interposition of at least one epicyclic gear train 14 (or reduction unit). The gear train 14 comprises a rotating central sun gear (or sun) 15, which meshes with a plurality of planet gears 16 which are movable (around the sub gear 15) and are in turn mounted on a planet carrier 17 and mesh with an internally toothed rotating ring gear 18. The general diagram of a possible gear train 14 according to the invention is shown by way of non limiting example in Figure 5.

If the sun gear 15, the planet carrier 17 and the ring gear 18 described above (which correspond to the application/connection points that the gear train 14 offers) are arranged in a per se traditional manner, it is emphasized that in the most common applications of epicyclic gear trains one of them is always kept fixed, thus allowing to transfer motion between the other two according to the transmission ratio defined by the shape and number of teeth of each one of these elements.

Vice versa, in an entirely particular manner the gear train 14 provides that the sun gear 15, the planet carrier 17 (with the planet gears 16, of course) and the ring gear 18 are all free to move, and this very condition allows to achieve the aim and objects of the invention. In fact, the primary electric motors 10 are connected, even indirectly, to the gear train 14 respectively at selectively two among the sun gear 15, the planet carrier 17 and the ring gear 18, while the transmission shaft 11 is connected, even indirectly, to the gear train 14 at the other among the gear 15, the planet carrier 17 and the ring gear 18. The term “connection”, even indirect, between two components from those described above means that there may be a rigid connection and also that the interposition of one or more toothed elements or in any case of additional transmission elements (to achieve different reduction ratios) can be provided.

In this manner, when one wishes to start the vehicle 2, the electronic device 9 can impose equal and opposite rotation rates to the two primary motors 10 or in any case choose (as a function of the reduction ratios involved) rotation rates such that the resulting rotation rate for the transmission shaft 11 is nil. Thus, the primary electric motors 10 can start and deal with the initial transient (in which, as is known, they have a low performance) by actually turning idle, without applied load, therefore without significant energy consumptions.

Only subsequently the device 9 can vary the rotation rates of the two primary motors 10 in order to turn progressively the transmission shaft 11 and therefore move the vehicle 2.

By virtue of the gear train 14, therefore, it is possible to achieve right now the intended aim.

In particular, in the preferred embodiment (and in the various embodiments shown in Figures 2-4), the primary electric motors 10 are connected, even indirectly, to the gear train 14 respectively at the sun gear 15 and at the ring gear 18, while the transmission shaft 11 is connected, even indirectly, to the gear train 14 at the planet carrier 17.

Usefully, the lift 1 comprises at least one battery pack 19, which is configured for the direct or indirect power supply of the primary motors 10 and for the supply of the electric power required to supply an apparatus for moving the arm 5.

Preferably, respective inverters 20 are interposed between the battery pack 19 and the primary motors 10: in the preferred embodiment, the electronic device 9 controls the rotation rate of the primary motors 10 indeed by acting on the inverters 20.

The movement apparatus preferably comprises at least one pump 21, even more preferably of the hydraulic type. More generally, the electric power provided by the battery pack 19 is used to supply the required energy to a movement apparatus comprising a distributor responsible for moving not only the boom 5 but also all the other movable components supported directly or indirectly by the vehicle 2 (and therefore, for example, also the cab 7 and the stabilizer means 4).

It should be noted that in the accompanying figures (and in the preferred solution), the two primary electric motors 10 are both supplied by the same battery pack 19. However, it is not excluded to arrange two or more packs 19 for the mutual independent supply of the two primary motors 10 (and/or of the movement apparatus), and provisions are made to supply power, even differently, to the primary electric motors 10 or to supply only the primary electric motors 10 with the battery pack 19 (using other power sources for the movement apparatus).

The methods with which the electric power supplied by the battery pack 19 is transferred to the pump 21 can be any, and some practical examples (also shown in the accompanying Figures 2-4) will be presented hereinafter by way of non-limiting example of the invention.

In particular, therefore, in a first practical option (Figure 2), the lift 1 comprises an auxiliary electric motor 22, which is powered by the battery pack 19 and is configured to deliver mechanical energy to the apparatus (to the pump 21, for example).

In other practical options (Figure 3-4), the apparatus (be it the pump 21 or others) is powered by one of the primary motors 10. In greater detail, in an embodiment of considerable interest in application (Figure 3), a clutch 23 is interposed between the primary motor

10 adapted to power the apparatus (the pump 21 for example) and the gear train 14 and is configured to provide (temporarily) the decoupling of the respective primary motor 10 from said gear train 14 and therefore from the transmission shaft 11. Thus, when the chosen primary electric motor 10 provides mechanical energy to the pump 21, the transmission shaft 11 can be disconnected and vice versa.

The presence of the clutch 23 constitutes in any case a simple option: a solution in which it is absent (as in Figure 4) also falls within the protective scope claimed herein.

The ways in which the sun gear 15, the planet carrier 17 and the ring gear 18 are connected to the primary motors 10 and to the transmission shaft

11 may be any, according to the requirement of the case (and the transmission/reduction rates that one wishes to obtain).

In particular, therefore, first of all the sun gear 15 can rotate integrally with one of the primary electric motors 10 (the sun gear 15 is in practice keyed on the output shaft thereof), as in the accompanying figures. It is not excluded, however, to interpose one or more additional toothed elements between the sun gear 15 and the respective primary motor 10.

With further reference to the solutions of the accompanying figures, the gear train 14 comprises a first auxiliary gear 24, which meshes with the ring gear 18 and rotates integrally with one of the primary electric motors 10. Therefore, the ring gear 18 is provided with teeth both internally (for meshing with the planet gears 16) and externally (for meshing indeed with the first auxiliary gear 24) and said first wheel 24 is keyed to the output shaft of the respective primary motor 10.

It is not excluded, however, to connect in an integral manner the ring gear 18 and the respective primary electric motor 10.

Again with reference to the preferred solution adopted in the accompanying figures, the gear train 14 comprises a second auxiliary gear 25, which meshes with the planet carrier 17 and rotates integrally with the transmission shaft 11. The integral coupling can be for example obtained by keying the second auxiliary gear 25 directly on the transmission shaft 11 (as in the accompanying figures).

It is not excluded, however, to connect in an integral manner the planet carrier 17 and the transmission shaft 11.

Besides being capable of meeting practical requirements tied to the available space occupations, the adoption of the auxiliary gears 24, 25 offers greater versatility to the gear train 14 and in particular allows to shape at will the reduction ratios involved.

Advantageously, the lift 1 may comprise at least one brake for the transmission shaft 11 , which can be activated temporarily when the vehicle 2 starts from a standstill. The brake constitutes therefore a further assurance of the fact that when the vehicle 2 starts the transmission shaft 11 is stationary and that therefore the primary motors 10 rotate idly, for the advantages already described, even in the case of anomalies in the control of said primary motors 10 or of other irregularities.

In addition to the lift 1, the present description also relates to a method for controlling startup (of the primary electric motors 10 and of the vehicle 2), which can be performed when starting from a standstill in a lift 1 of the type described so far.

According to the invention, therefore, the method consists, in a step a., in choosing, and maintaining for a first time period, a ratio between the rotation rates of the primary motors 10 which corresponds, as a function of the reduction ratios defined by the gear train 14, to a nil rotation rate condition for the transmission shaft 11 (and therefore during the first time period the vehicle 2 remains stationary). The selection of the rates can be performed by the electronic device 9.

During step a., furthermore, the brake that acts on the transmission shaft 11 , if provided, can be activated.

At the end of the first period (which is chosen so as to be sufficient to make the primary electric motors 10 overcome the transient in which they offer low performance), in a step b. the method according to the invention provides for varying the ratio among the rotation rates of the primary motors

10 in order to increase progressively the rotation rate of the transmission shaft 11 and produce the starting (displacement) of the vehicle 2. Step b., too, in practice can be actuated by the electronic device 9.

The operation of the rotary telescopic boom lift according to the invention has in practice already been described, but a summary thereof is presented hereinafter.

The vehicle 2 can move on the ground to reach the exact location and point in which it is necessary to perform an intervention (usually at a certain height above the ground), for which indeed the use of the lift 1 (with the accessory 6 mounted on the boom 5) is required. In greater detail, after reaching the point of intervention, it is possible to activate the means 4, in order to obtain a more stable grip on the ground, and then rotate the cab 7 (if this possibility is provided) and rotate and/or extract the boom 5, moving the boom as well, until the accessory 6 is brought to the exact intervention point.

The vehicle 2 is provided with electric traction and the electric power is typically provided by a battery pack 19, which can be recharged in a traditional manner and which, in an entirely particular manner, supplies power to at least two primary electric motors 10 (which in practice are arranged in parallel and are) associated with the transmission shaft 11 with the interposition of a gear train 14.

The three degrees of freedom corresponding to the rotation of the two primary motors 10 (of the two output shafts) and of the transmission shaft

11 are made to correspond directly or indirectly (with additional intermediate toothed/transmission elements) to the sun gear 15, to the planet carrier 17 and to the ring gear 18 of the gear train 14. In particular, in the preferred embodiment, a first primary motor 10 is associated with the (sun) gear 15, the other primary motor 10 is connected to the ring gear 18 while the motion of the transmission shaft 11 is drawn from the planet carrier 17 (from the rotation of the planet gears 16 around the sun gear 15).

As shown, in this manner (preferably by means of the inverters 20) the electronic device 9 can control the primary electric motors 10, choosing rotation rates such that when one wishes to make the vehicle 2 start the rotation rate of the transmission shaft 11 is nil (the brake can contribute to this result). This can be obtained by adopting equal or opposite rotation rates for the primary motors 10 or by putting them in the most appropriate ratio, as a function of the existing reduction/transmission ratios.

In any case, in this manner the start of the primary electric motors 10 occurs at zero load, with the vehicle 2 stationary; if one recalls that the start of any electric motor is normally penalized by low performance, the invention ensures that said condition does not lead to significant energy consumption, since indeed in this transient step the load is zero.

Once the step characterized by low performance is passed, the vehicle 2 is actually made to start by varying conveniently the rotation rates of the primary motors 10, so that indeed the resulting rotation rate for the transmission shaft 11 is not nil and so that the rotation rate can turn the movable elements (the wheels 3 or the tracks) in order to indeed move the vehicle 2. By giving a higher rate to a primary motor 10 rather than the other, it is also possible to impose a direction of travel to the vehicle 2 or the opposite one.

In practice it has been found that the lift and the method according to the invention fully achieve the intended aim, since by virtue of the primary motors 10, the gear train 14 and the electronic device 9 it is possible to provide a telescopic boom lift 1 with electric traction that ensures a modest energy consumption when the vehicle 2 starts. In fact, in practice the invention allows to start the primary electric motors 10 idle (with little energy involved, and therefore the lower performance at start is negligible) and then apply the load only to primary motors 10 that have already started and have been brought to work in high efficiency regions.

Actually because of the particular choice to start the primary motors 10 idle, the telescopic boom lift 1 at start requires a low torque, even in the case of an uphill start or in any case in demanding conditions. Therefore, the sizing of the primary motors 10, and of the associated control systems, can be done as a function of the power required to do the work needed and no longer in order to solve a torque problem during start (as is the case instead in known solutions). Therefore, the invention allows to provide a lift 1 of modest cost, in which the components assigned to the electric traction are sized in relation to the usual working conditions.

Furthermore, it has been observed that in a very practical way it is possible to utilize the electrical power provided by the battery pack 19 (and optionally one of the primary motors 10, with or without a clutch 23) to actuate the hydraulic pump 21 required to move the boom 5 and other moving components. This evidently ensures a structural simplification of the lift 1 and a welcome reduction in space occupations (and weights).

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In the exemplary embodiments shown, individual characteristics, given in relation to specific examples, may actually be replaced with other different characteristics that exist in other exemplary embodiments.

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

The disclosures in Italian Patent Application No. 102021000018401 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.