Patent Description:
Recently, the demand for towing tractors that are battery-powered is more and more increasing. According to a known art, lithium battery assemblies can be installed on the towing tractor in a substantially permanent manner, so that the battery is not replaced during normal operation. See for example <CIT>.

In order to achieve a satisfactorily long reach and power, rather bulky and heavy lithium battery assemblies are necessary, in case of battery assemblies that are permanently mounted on the tractor; accordingly, the frame of the towing tractor must be dimensioned and designed to support the stresses induced by the weight of the batteries, in addition to the usual forces that are caused by the operation for towing tractor, such as the stresses induced by the trailers and, more in general, to the loads that are carried by the towing tractor. Accordingly, the structure and the frame of the towing tractor must be manufactured with a suitable dimensioning of the frame parts, this leading to an increase in the cost and a complex design.

There is therefore a need for improvement that may allow to reduce the complexity of the structure of the electrically-powered towing tractor and to possibly save manufacturing costs and material usage, while achieving a satisfactorily long range and power.

The mentioned problems are solved by the subject-matter of the main claim. Specifically, the embodiments of the present invention may provide substantial benefits that are described in part herein.

According to an embodiment of the present invention, there is provided an electrically-powered towing tractor including:.

Embodiments of the present invention, which are presented for better understanding the inventive concepts but which are not to be seen as limiting the invention, will now be described with reference to the figures in which:.

In <FIG> a towing tractor <NUM> is shown including a counterweight <NUM> on the rear side. The towing tractor <NUM> may include a user cabin <NUM> on the front of the vehicle. The towing tractor <NUM> may include four wheels <NUM>. The towing tractor <NUM> may include a loading surface formed by a panel <NUM> positioned between the cabin <NUM> and the rear end of the towing tractor <NUM>. The towing tractor <NUM> includes coupling means <NUM> for connecting a trailer to the towing tractor. Preferably, the counterweight may be formed as a single piece, more preferably a single piece made of cast iron. Preferably, the coupling means <NUM> may be mounted directly on the counterweight <NUM> as shown in <FIG>. The coupling means may include a vertical plate fixed to the counterweight <NUM> and one or more perforated plates protruding from the vertical plate, each of the one or more perforated plates forming a hole for receiving a connecting pin <NUM> for connecting the trailer (not shown) to the towing tractor <NUM>. The vertical plane of the coupling means <NUM> may be advantageously screwed to the rear part of the counterweight <NUM>, e.g. to a substantially vertical rear surface of the counterweight <NUM>.

The towing tractor <NUM> is electrically-powered and includes a battery assembly, e.g. configured to feed electrical power to an electrical traction motor of the towing tractor. The battery assembly may include a housing <NUM> that forms a recess <NUM> for receiving one or more battery cells (see <FIG>); the battery cells may include lithium battery elements or cells. The housing <NUM> may form part of a central battery module <NUM> of the towing tractor that includes the housing and the battery cells inside the housing <NUM>; in other words, the housing <NUM> may form the outer shell of the central battery module <NUM>. In a preferred embodiment, the battery assembly may additionally include one or two lateral battery modules <NUM> and <NUM> (see <FIG>), in addition to the central battery module <NUM>; preferably, the battery modules <NUM> and <NUM> may include lithium battery elements or cells, as well.

As shown in <FIG> and <FIG>, the towing tractor <NUM> includes a front frame portion <NUM>. The front frame portion <NUM> forms part of, or supports, a front axle structure. For example, the front frame portion <NUM> may support a frame element <NUM> that in turn is connected to the axle <NUM> onto which the front wheels <NUM> are mounted (see <FIG>).

The towing tractor <NUM> includes two longitudinal members <NUM> located on opposite lateral sides of the housing <NUM> of the battery assembly. The two longitudinal members <NUM> are connected to the counterweight <NUM> by means of releasable fastening means <NUM>, e.g. by means of screws. Preferably, each longitudinal member <NUM> is fixed to the counterweight by means of two or four screws. Preferably, each longitudinal member <NUM> is fixed to the counterweight <NUM> at a substantially vertical surface <NUM> of the counterweight facing towards the front frame portion <NUM>. The longitudinal members <NUM> connect the counterweight <NUM> and the front frame portion <NUM> on opposite lateral sides of the electrically-powered towing tractor and are configured to transfer forces between the counterweight <NUM> and the front frame portion <NUM> during operation of the electrically-powered towing tractor. In other words, the longitudinal members <NUM> are configured and designed to withstand the forces that must be transferred from the front frame portion <NUM> to the counterweight <NUM> during the normal operation of the tractor, due for example to stresses induced by the trailers via the coupling means, the load on the loading surface <NUM> or the driving of the tractor while transporting a load. The panel <NUM>, the counterweight <NUM> and the longitudinal members <NUM> are such to define a loading plane. In other words, above the panel <NUM> a load can be carried by the towing tractor. The panel <NUM> is fixed directly to the longitudinal members <NUM> and to the counterweight <NUM>.

Similar to the connection to the counterweight <NUM>, the longitudinal members <NUM> may be fixed to the front frame portion <NUM> by means of releasable fastening means <NUM>, such as screws. For example, each longitudinal member may be fixed to the front frame part <NUM> by means of two or four screws <NUM>.

The longitudinal members <NUM> are dimensioned to withstand the operational stresses transferred between the front axle on the one hand, and the counterweight <NUM> on the other hand. As shown above, the longitudinal members <NUM> are fixed to the counterweight <NUM> and to the front portion <NUM> of the frame by means of releasable fastening means. This allows to manufacture towing tractors of different sizes while using always the same design for the counterweight and the front frame portion, by simply preparing battery assemblies of different size in the longitudinal direction. Hence, different wheel bases can be achieved in a cost-effective manner.

Preferably, the longitudinal members <NUM> include flanges at opposite ends that are joined to the counterweight <NUM> and the front frame portion <NUM>, respectively, by means of the releasable fastening means <NUM>, <NUM>.

The housing <NUM> of the battery assembly includes two opposite lateral walls, a first one of said two opposite lateral walls being fixed to a first one of the two longitudinal members <NUM> and a second one of said two opposite lateral walls being fixed to a second one of the two longitudinal members <NUM>. The housing <NUM> is positioned between the counterweight <NUM> and front frame portion <NUM>. The housing <NUM> is configured to support the weight of the battery cells during operation of the tractor <NUM>. The housing <NUM> can have a box-like shape and can be made of metal sheets.

The longitudinal members <NUM> are substantially parallel. The longitudinal members <NUM> have a beam-like structure. Preferably, the longitudinal members <NUM> are formed with a C-shaped cross section or a H-shaped cross section. The longitudinal members <NUM> preferably includes a central plate portion 14a (see <FIG>) that in use is positioned substantially in a vertical plane. The longitudinal members include further an upper plate portion <NUM> that in use is positioned substantially in a horizontal plane. The longitudinal members may further include a lower plate portion that in use is positioned substantially in a horizontal plane, wherein the central plate portion 14a connects the upper and lower plate portions of each longitudinal member.

The two opposite lateral sides (or walls) of the housing <NUM> are substantially vertical and contact the longitudinal members <NUM>. The lateral sides of the housing <NUM> are fixed to the longitudinal members <NUM> by means of fastening means <NUM>, e.g. releasable fastening means, such as by nut and bolt, or a screw. Preferably, each lateral wall of the housing <NUM> is fixed to a respective longitudinal member <NUM> by means of two fastening means, e.g. two screws, or four screws. The longitudinal members <NUM> may include corresponding holes <NUM> for receiving the fastening means <NUM> on a lateral side thereof.

In a preferred embodiment, the surface of the battery assembly facing downwards is not in contact with parts of a frame of the towing tractor <NUM>. In other words, the weight of the battery assembly is not supported by portions of the frame of the towing tractor positioned under the battery assembly. Thus, the lower part of the housing <NUM> is not supported by a frame portion. In a preferred embodiment, the lower part of housing <NUM> extends downwardly at a height below the longitudinal members <NUM>. The lower part of housing <NUM> may also extend downwardly at a height below the counterweight <NUM>. This structure of the battery assembly allows to reduce the usage of material while achieving a suitable robustness of the towing tractor to withstand operational stresses. The weight of the battery assembly is supported by the connection of the longitudinal members <NUM> to the counterweight <NUM> and the front frame portion <NUM>. The housing <NUM> and the battery cells contained in the housing <NUM> are fully supported laterally by the longitudinal members <NUM>. Hence, the space available for the battery assembly is increased, as the battery assembly can extend downwardly relatively close to ground. This allows to increase in turn the space available for the battery cells and, hence, to increase the reach and the power of the towing tractor.

As well shown in <FIG>, the longitudinal members <NUM> may preferably have a substantially horizontal orientation. The rear ends of the longitudinal members <NUM> that are connected to the counterweight <NUM> are located at a height entirely above rear wheels of the towing tractor. The front ends of the longitudinal members <NUM> that are connected to the front frame part <NUM> are at a height entirely above the front wheels of the towing tractor. This configuration may contribute to achieve suitable mechanical robustness and material savings.

Although detailed embodiments have been described above, these only serve to provide a better understanding of the invention defined by the independent claims and are not to be seen as limiting.

The battery assembly may include a lateral battery module <NUM> or <NUM> mounted between one of the longitudinal members <NUM> and a lateral cover element (not shown) of the towing tractor configured to protect the lateral battery module <NUM> or <NUM> from external agents. In <FIG>, the lateral battery modules <NUM> and <NUM> are shown on opposite lateral sides of the towing tractor. The lateral cover elements may be absent, in this case the lateral battery element <NUM>, <NUM> is simply mounted to a corresponding longitudinal member <NUM> on an opposite side with respect to the housing <NUM>. The lateral battery assembly <NUM> includes a housing connected to longitudinal member <NUM> by means of releasable fastening means <NUM>, e.g. screws. The housing of the lateral battery assembly <NUM> may include four arms protruding in a horizontal direction, two on each one of opposite sides of the housing, wherein each of the arms carries a fastening mean for fixing the lateral battery module to the longitudinal member <NUM>. In the example of <FIG>, four screws <NUM> are used to fix the lateral battery assembly <NUM> directly to the longitudinal member <NUM>. The screws may engage in corresponding holes <NUM> formed on the longitudinal member <NUM> (see <FIG>). The other lateral battery module <NUM> may have a similar configuration and attachment to the other longitudinal member <NUM>. Alternatively, instead of including four arms, the housing of the lateral battery module may include only two arms, each one on opposite sides of the lateral battery module. The number of arms could also be different. This allows to improve the connection between the lateral battery module and the longitudinal member.

Claim 1:
An electrically-powered towing tractor (<NUM>) including:
- a counterweight (<NUM>),
- coupling means (<NUM>) configured for connecting a trailer to the towing tractor,
- a front frame portion (<NUM>), and
- a battery assembly comprising a housing (<NUM>) that forms a recess (<NUM>) for receiving one or more battery cells,
characterized in that the towing tractor further comprises two longitudinal members (<NUM>) located on opposite lateral sides of the housing (<NUM>), wherein the two longitudinal members (<NUM>) are connected to the counterweight (<NUM>) by means of releasable fastening means (<NUM>), wherein the longitudinal members (<NUM>) connect the counterweight (<NUM>) and the front frame portion (<NUM>) on opposite lateral sides of the electrically-powered towing tractor and are configured to transfer forces between the counterweight (<NUM>) and the front frame portion (<NUM>) during operation of the electrically-powered towing tractor.