Patent Description:
According to the state of the art, automotive vehicles and particularly those intended for the transportation of goods, such as trucks, are usually pulled by their rear shaft having a powertrain formed by the engine and gearbox mounted at the front of the vehicle. The connection between the powertrain and the traction wheels is formed by a shaft, commonly called the cardan shaft, which, on the one hand, is connected to the output of the powertrain, usually the gearbox and, on the other hand, is connected to the differential of the shaft that is responsible for transmitting the power to the wheels.

In the case of road transport vehicles, such as truck-tractors with two rear shafts, the vehicle may have a <NUM>×<NUM> or <NUM>×<NUM> traction configuration, i.e., of the six wheels of the vehicle, only two are pulled, usually the two wheels of the first rear shaft, or the four wheels of the two rear shafts are pulled. In some vehicle applications configured for "off-road", they may also have an <NUM>×<NUM> or even <NUM>×<NUM> or <NUM>×<NUM> traction configuration.

The use of at least two traction shafts, as in a <NUM>×<NUM> configuration, can be quite interesting, both for legal reasons (in certain countries, such as Brazil, to transport a higher load limit the vehicle must have a <NUM>×<NUM> traction configuration), and reasons of use, as in the case of vehicles for off-road use, such as sugarcane or mining vehicles.

However, when the vehicle is not loaded, to save fuel and tires, it is desirable that one of the shafts is not used. If the traction configuration is, for example, a <NUM>×<NUM> configuration, one of the rear shafts, the one not pulled, can potentially be suspended and thus achieve a reduction in fuel consumption and tire wear. This is possible using some solutions that are already known, and where an air bag is generally used to suspend the shaft, thus taking advantage of the compressed air line fitted in these models of vehicles.

However, this solution cannot be used in vehicles with a <NUM>×<NUM> or <NUM>×<NUM> traction configuration, for example, since a traction shaft cannot be suspended because the power to the suspended shaft would be lost.

So, there is a need to allow the coupling or decoupling of the traction of at least one shaft of a vehicle, particularly a cargo vehicle, such as a truck or truck-tractor.

The state of the art reveals some solutions by which it is possible to automatically or manually select the traction of one or more shafts. A known solution is to engage or disengage the gear from the central differential that sends power to the shaft. This solution, however, cannot be used in the <NUM>×<NUM> or <NUM>×<NUM> traction configurations, since no central differential is generally employed; rather the traction is transmitted from one differential to another, sequentially, through a cardan shaft.

Another more elaborate solution, such as that revealed in the state-of-the-art document <CIT>, uses more complex features such as lamella clutches and electronic management. These solutions are complex and expensive, and may not work properly for very high torques, as in the case of goods transport vehicles, whose torque at the engine output can easily exceed <NUM>, and reach up to around <NUM>.

Another solution revealed in the state of the art can be observed in the document PCTBR201605050182, which refers to a coupling system driven by pneumatic devices installed concentrically with the propeller shaft between shafts to, thus, enable the coupling/decoupling of one of the pulled shafts. Although functional and revealing a solution to the means known to the state of the art, this option could be improved and refined, particularly with regard to the construction and assembly of the components responsible for the coupling and decoupling. More specifically, this state-of-the-art solution reveals a complex construction, requiring excessive expenditure of time and resources for its manufacture, assembly and application to vehicles.

Other examples known in the art are disclosed in publications <CIT>, <CIT>, <CIT> or <CIT>.

Thus, considering the present scenario, it is observed that there is still a need for a simple, practical and functional technical solution that can be easily applied to commercial cargo transport vehicles, without the need for substantial investments and resources, thus enabling the effective application of a safe solution to simpler models of vehicles with <NUM>×<NUM>, <NUM>×<NUM> or similar traction configurations. The invention aims, among others, to overcome these inconveniences of the state of the art.

So, in the light of the above, it is one of the aims of the present invention to provide a propeller shaft for a motor vehicle, particularly those used for transporting loads with a traction configuration of <NUM>×<NUM> or <NUM>×<NUM>, where said propeller shaft is equipped with technical, constructive and functional characteristics designed and developed to allow for the decoupling and coupling of at least one of the traction shafts in order to eliminate the problems, limitations and inconveniences of the solutions previously known to the state of the art, and as summarized above.

Another aim of this invention is to provide a vehicle, such as those used for the transportation of loads, which is configured with traction of the <NUM>×<NUM> or <NUM>×<NUM> type, and equipped with at least one propeller shaft as mentioned above, installed in place of the conventional cardan shaft of the vehicle, allowing for the selection of the type of traction.

Thus, as described above, and with the aim of achieving the aforementioned objectives and technical effects, the present invention refers to a propeller shaft and a vehicle as claimed in the appended set of claims.

The characteristics, advantages and technical effects of the present invention, as indicated above, will be better understood by a person skilled in the art from the following detailed description, provided for merely exemplative and non-restrictive purposes, of some embodiments, and with reference to the following schematic figures, where:.

The invention is now described in relation to its particular embodiments with reference to the figures attached as examples of embodiments. These figures are schematic, and their dimensions and/or proportions may not correspond to reality, since they merely aim to describe the invention didactically. In addition, certain known and common constructive details may have been omitted for better clarity and concision of the description provided below. The reference numbers indicated in the figures are repeated along the different views to indicate equal or similar technical characteristics. In addition, the terms sometimes used here, such as: above, below, upper, lower, side, right, left, frontal, rear and their variants should be interpreted according to the guidance given in <FIG>.

Initially, for merely illustrative purposes, and particularly for the due contextualization and better understanding of the matter, according to the present invention, <FIG> schematically represents a vehicle (V) intended for the transportation of cargo or goods, such as a truck known to the state of the art. This vehicle (V), as schematically represented in <FIG>, may be, for example, a model manufactured and marketed by CNH Industrial N.

Basically, it is possible to say that the vehicle (V) comprises a control and operation cab (C) under which are provided a transmission powertrain (M), such as a combustion engine associated with a gearbox, which are mounted on a chassis (E) supported by a front shaft (TD), a first rear shaft (T1) and a second rear shaft (T2). According to this description, these rear shafts (T1, T2) are pulled and, thus, will potentially be indicated as the first traction shaft (T1) and the second traction shaft (T2).

From the drive assembly (M), which is formed of the gearbox within which are arranged a series of gears and other components responsible for transmitting the power generated in the engine and, from which extends a first cardan shaft <NUM> to a first differential of the first traction shaft (T1) and, from the differential of the first traction shaft (T1), extends a second cardan shaft <NUM> to the differential of the second traction shaft (T2). The power is generally divided equally between the first and second differentials to the wheels of the first (T1) and second (T2) traction shafts. Thus, the differentials transmit the power to the wheels of each shaft in a normal way using a crown/pinion system and epicycloidal gears, which is already well known to persons skilled in the art and, thus, will not be explored in this case. In addition, other details of the vehicle (V) are represented in a schematic way and do not require further explanation, since they are known in conventional cargo transport vehicles.

As mentioned above, it may be of interest, in certain applications, such as an unloaded vehicle (V), that power is not transmitted from the differential of the first traction shaft (T1) to the differential of the second traction shaft (T2), causing the vehicle (V) with 6x4 traction to take on a 6x2 traction configuration. With this 6x2 traction configuration, it is possible for the second traction shaft (T2) to be raised, generating fuel and tire savings. The raising of the second rear shaft can be done by normal means known to the state of the art, such as using components driven by the pneumatic system of the vehicle itself.

The present invention aims, precisely, to allow for the coupling or decoupling, selectively and according to the interests of the driver, of the second differential from the second traction shaft (T2), transforming the traction configuration from 6x4 to a 6x2 traction configuration. Of course, in this more in-depth description of one embodiment of the invention, reference is made to a <NUM>×<NUM> and <NUM>×<NUM> traction configuration, but the invention can obviously be used in any traction configuration where one wishes to activate or deactivate a second traction shaft, such as a <NUM>×<NUM> / <NUM>×<NUM>, <NUM>×<NUM> / <NUM>×<NUM> traction configuration, etc..

With reference now to <FIG>, a transmission shaft <NUM> is shown, such as for coupling in a cardan shaft or replacing a conventional cardan shaft, which is specifically mounted between the first traction shaft (T1) and the second traction shaft (T2) of a vehicle (V). In this regard, the shaft <NUM> can be mounted between the differentials of two rear traction shafts of a vehicle comprising, for example, a <NUM>×<NUM> traction configuration, or even replace the second cardan shaft <NUM>.

Since the first rear shaft (T1) and the second rear shaft (T2) can have different assembly heights or can also be mounted to the suspension of the vehicle, being subject to oscillations in height and, consequently, at a distance from each other, crossheads <NUM> and <NUM> are provided at the ends of the shaft <NUM>, which form the mechanical connection with the rest of the transmission powertrain of the vehicle. Furthermore, the shaft <NUM> comprises an assembly <NUM> of two concentric toothed shafts, which allow for the compensation of the distance that may exist between the first traction shaft (T1) and the second traction shaft (T2).

It is worth noting that both the crossheads <NUM> and <NUM>, and the assembly <NUM>, are mechanical constructions used in cardan shafts that are widely known and used in the state of the art, and can thus be replaced by any equivalent mechanical constructions, such as homokinetic joints or flanges associated with screws and nuts, in cases where the coupling is mounted on a long cardan shaft. The decision to choose crossheads, homokinetic joints or other mechanical construction elements does not alter the technical effects foreseen for the present invention.

In this regard, based on the scenario summarized above, it may be said that the present invention refers to a new propeller shaft <NUM> comprising a first shaft segment <NUM>, which can be mounted on a power output, and a second shaft segment <NUM>, which can be mounted on a power input to receive the power coming from the first shaft segment <NUM>. Both shaft segments <NUM>, <NUM> are concentrically mounted within a housing <NUM>, so that the first shaft segment <NUM> can be rotated independently in relation to the second shaft segment <NUM>, where this first shaft segment <NUM> comprises, on the one hand, a power input and, on the other hand, is mounted concentrically with the second shaft segment <NUM>. The second shaft segment <NUM> also has, on one side, a toothed face (<NUM>) to receive a power input and, on the other side, it has a power output. Thus, the first <NUM> and second <NUM> shaft segments are coupled and decoupled selectively by means of a flange <NUM>, which is mounted concentrically on the first shaft segment and comprises a toothed face for the respective coupling with the toothed face of the second shaft segment. Furthermore, this flange <NUM> can move between a coupled and uncoupled position due to the coaxial displacement along the said first shaft segment <NUM>.

According to one embodiment of the present invention, the said flange <NUM> is driven by a coupler <NUM> formed of an actuator 14a that possesses a shaft 18c equipped with a means of return <NUM>, and a fork <NUM> connected to said flange <NUM> provided with a groove in its internal diameter for connection with a grooved part 12a provided for in the first shaft segment <NUM>, and teeth 15a on its lateral face to enable the connection with the teeth 16a arranged on the toothed face <NUM> of the second shaft segment <NUM>.

In these circumstances, it may be noted that the propeller shaft <NUM>, according to the present invention, can be installed in place of the second cardan shaft <NUM>, between the first traction shaft (T1) and the second traction shaft (T2) of said vehicle (V). Thus, the first shaft segment <NUM> is mounted next at a power output deriving from the first cardan shaft <NUM>, and the second shaft segment <NUM> is mounted on the power input, for example, on the differential of the second traction shaft (T2), said shaft segments <NUM>, <NUM> being selectively connected through said coupler <NUM> which is responsible for blocking and transmitting the power between the shaft segments <NUM>, <NUM>.

Also, in order to maintain the good functioning, and increase the service life, of said propeller shaft <NUM>, the object of the present invention, said housing <NUM> comprises sealant elements <NUM> to securely hold a lubricating and cooling fluid in contact with said shaft segments <NUM>, <NUM>, as well as with the actuator <NUM>.

Of course, although it is mentioned here that the first shaft segment <NUM> can be mounted on a power output and the second shaft segment <NUM> can be mounted on a power input, the configuration may be reversed, i.e., the first shaft segment <NUM> can be mounted on a power input and the second shaft segment <NUM> can be mounted on a power output without any prejudice or difference in relation to the technical effect achieved by the present invention.

According to one embodiment, said toothed face <NUM> may be a fixed flange that is provided with a grooved surface on its inner diameter for connection with a respective grooved part 13a positioned at the end of the second shaft segment <NUM>. In addition, as noted above, the toothed face <NUM> or said fixed flange possesses teeth 16a on its lateral face to enable the connection with the teeth 15a arranged on the side face of the mobile flange <NUM> of the first shaft segment <NUM>.

According to one embodiment of the present invention, said driver 14a can be of any model and use different appropriate means, such as, but not limited to, mechanical, magnetic, electrical or hydraulic means or a combination thereof, provided that it can enable the movement of said fork <NUM> between at least two positions and, consequently, achieve coupling or decoupling between the said first and second shaft segments <NUM>, <NUM>.

According to one embodiment of the coupler <NUM>, in accordance with the present invention, said driver 14a comprises a chamber <NUM> with airtight closure that is formed by a fixed cover 18a installed in a branch 11a of the housing <NUM>, and inside said chamber <NUM> a mobile piston 18b is positioned that is supported on the shaft 18c which supports the aforementioned fork <NUM> and the means of return <NUM>.

According to one embodiment of the present invention, the fixed cover 18a of the driver 14a is equipped with a channel 19a, that is fluidly connected to the hydraulic or pneumatic system of the vehicle (V) for feeding the chamber <NUM>. Thus, on introducing compressed air or hydraulic fluid inside the chamber <NUM>, this tends to expand its volume, shifting the mobile piston 18b axially along the shaft 18c, towards the arrow "X", and, consequently, the fork <NUM>, causing the mobile flange <NUM> to move until it achieves the corresponding coupling with the fixed flange <NUM>, thus transmitting power to the second shaft segment <NUM> and, consequently, to the second traction shaft (T2). Under these conditions, the driver is able to alter the configuration and traction of the vehicle from a configuration of <NUM>×<NUM> to <NUM>×<NUM> by simply activating and feeding said chamber <NUM> of the driver 14a.

Conversely, in order for the vehicle (V) to achieve a traction configuration of the <NUM>×<NUM> type, it is necessary for the pressure inside the chamber <NUM> of the driver 14a to be alleviated, allowing the fork <NUM> to shift the movable flange <NUM> in the direction of the arrow "Y", causing it to decouple from the toothed face <NUM>, interrupting the power transmission to the second traction shaft (T2) and thus allowing this second shaft to be raised.

Optionally, the fixed cover 18a of the driver 14a comprises a complementary input 19b to allow for the installation of sensors, for example, a sensor for monitoring the pressure inside the chamber <NUM>.

In accordance with the aforementioned embodiments, compressed air or hydraulic fluid is used. The use of these components as one of the ways to enable the displacement of the fork <NUM> and, consequently, the mobile flange <NUM>, is appropriate since the lines of compressed air and, potentially, of hydraulic fluid already present in most commercial vehicles and machinery can be used.

Naturally, as highlighted above, although this description refers to the use of compressed air to vary the pressure inside the chamber <NUM>, other means can be provided, such as other fluids, like oil or water, or magnetic or even electromechanical means, such as solenoid valves. Furthermore, although it is noted that the mobile flange <NUM> is in the disengaged position when the pressure inside the chamber <NUM> is approximately equal to the ambient pressure, it is clear that this embodiment can be reversed, so that the flange <NUM> is in the disengaged position only when the pressure inside the chamber <NUM> is increased, but this is less preferential, due to questions of operating safety. Nevertheless, although this specification refers to the terms "ambient pressure" and "increased pressure" with ambient pressure as a reference, it is clear that other pressure differentials that are not necessarily based on atmospheric pressure such as the base pressure can be used, including higher or even negative pressures, using a vacuum, provided that the pressure differential applied in the chamber <NUM> is sufficient to cause a shift of the mobile flange <NUM> through an axial movement, as indicated above.

Additionally, it is important to highlight that, to ensure the return of the fork <NUM> and, consequently, the decoupling of the mobile flange <NUM>, when there is a reduction of pressure in the chamber <NUM>, and for the purpose of preventing the coupling medium from escaping from a coupled position to a decoupled position, the means of return <NUM> may be a helical spring, ensuring that the coupler <NUM> remains in a predetermined position, such as a decoupled standard position, as represented in the drawings, or, conversely, a coupled standard position. Obviously, the means of return can be suppressed if other forms of displacement of the fork <NUM> are used, such as magnetic or electromechanical means. Nevertheless, other means of return can also be provided, such as magnetic, mechanical or hydraulic means, etc..

Specifically, the coupling and decoupling of the coupler <NUM> must be done with the vehicle stationary, that is, without the first shaft segment <NUM> rotating, however, though less advantageous, there is nothing to prevent such coupling and/or decoupling being done with the vehicle in motion.

Finally, and as observed above, the present invention also refers to a vehicle (V) for the transportation of cargo or goods, which comprises a control and operation cabin (C) and under which are provided a transmission powertrain (M), such as a combustion engine associated with a gearbox, which are mounted on a chassis (E), which is supported by a front shaft (TD), a first rear traction shaft (T1) and a second rear traction shaft (T2), connected by a propeller shaft <NUM>, like that observed above.

According to specific embodiments of the present invention, said vehicle (V) is a truck, such as those used in the road transportation of cargo or goods and, more particularly, which possesses the traction configuration of the <NUM>×<NUM> or <NUM>×<NUM> type, or the like.

Claim 1:
Propeller shaft for a vehicle, comprising:
a first shaft segment (<NUM>);
a second shaft segment (<NUM>);
wherein said first and second shaft segments (<NUM>, <NUM>) are mounted concentrically within a housing (<NUM>), the first shaft segment being able to rotate independently in relation to the second shaft segment,
wherein the first shaft segment (<NUM>) possesses, on the one hand, a power input and, on the other hand, is mounted concentrically on the second shaft segment (<NUM>);
the second shaft segment (<NUM>) comprising, on the one hand, a toothed face (<NUM>) to receive a power input and, on the other hand, having a power output,
wherein said first and second shaft segments can be coupled or decoupled selectively by a flange (<NUM>),
the flange (<NUM>) comprising a toothed face for coupling to the toothed face (<NUM>) of the second shaft segment (<NUM>) and being mounted concentrically on the first shaft segment (<NUM>);
the flange (<NUM>) also being able to move between a coupled and a decoupled position due to coaxial displacement along said first shaft segment (<NUM>),
the propeller shaft being characterized by further comprising, at its ends, crossheads (<NUM>, <NUM>) for mechanical connection with the rest of the transmission powertrain of the vehicle (V), and also possessing an assembly (<NUM>) formed of toothed concentric shafts to compensate for the distance between a first traction shaft (T1) and a second traction shaft (T2) of the vehicle (V).