Patent Description:
The present invention finds its preferred, although not exclusive, application in a joint connection for a steering system of the work vehicle. Reference will be made to this application by way of example below.

As is known, a vehicle has a steering system which comprises a steering wheel operable by an operator of the vehicle, a first rotating element configured to rotate in response to rotation of the steering wheel, and a second rotating element configured to rotate in response to rotation of the first rotating element so as to transmit motion to downstream elements of a transmission.

The first and second rotating elements have respective first and second rotation axes, which are normally coincident. However, due to relative movements between the first and second rotating elements, the first and second rotation axes may be parallel but non-coincident, intersecting, or even skew.

In the case of a work vehicle, the first rotating element may be a steering column located inside a cabin of the vehicle, and the second rotating element may be a pin of a hydraulic transmission. The relative movements between the first and second rotating elements may be due to vertical and/or horizontal oscillations of the work vehicle, caused e.g. by the particular conformation of clods underneath it.

In order to allow transmission of rotation (and thus of torque) between the first and second rotating elements irrespective of the aforementioned relative movements, a joint connection interposed therebetween may be used, as disclosed e.g. in <CIT>.

However, known joint connections, such as the one cited above or the examples disclosed in <CIT> and <CIT>, have problems related to assembly, noise production, and backlash compensation.

Therefore, the need is felt to improve known joint connections.

An aim of the present invention is to satisfy the above-mentioned needs in a cost-effective and optimised manner.

The aforementioned aim is reached by a joint connection as claimed in the appended set of claims.

<FIG> shows an exemplarily interior space of a cab of a vehicle <NUM>, in particular a work vehicle, shown only partially for the sake of clarity.

In the following, a steering system will be described to provide an application of the present invention. However, it is clear that the present invention may be applied to other operational systems of the work vehicle.

As is known, the vehicle <NUM> has a steering system which comprises a steering wheel (not shown) operable by an operator of the vehicle, a first rotating element <NUM> configured to rotate about an axis A in response to rotation of the steering wheel, and a second rotating element <NUM> configured to rotate about an axis B in response to rotation of the first rotating element <NUM> so as to transmit motion to downstream elements of a transmission.

In particular, the first rotating element <NUM> is a steering column located inside the cab of the vehicle <NUM>, i.e. above a cab floor <NUM>, and the second rotating element <NUM> is e.g. a pin of the transmission, which is e.g. a hydraulic transmission.

The axes A and B are normally coincident. However, due to relative movements between the first and second rotating elements <NUM>, <NUM>, the relative position between the axes A and B may be any. In particular, the axes A and B may be parallel but non-coincident, or intersecting, or even skew.

The steering system comprises a joint connection <NUM> which is operatively interposed between the first rotating element <NUM> and the second rotating element <NUM>.

The joint connection <NUM> comprises a first coupling element <NUM> configured to be coupled to the first rotating element <NUM>, a second coupling element <NUM> configured to be coupled to the second rotating element <NUM>, and an intermediate assembly <NUM> interposed between the first coupling element <NUM> and the second coupling element <NUM>, as described in detail hereinafter.

The first coupling element <NUM> (<FIG>) is carried in a fixed manner with respect to rotation by the first rotating element <NUM>, i.e. it is configured to rotate about an axis C' together with (i.e. with the same angular speed as) such first rotating element <NUM>. In particular, the axis C' coincides, in use, with the axis A.

Similarly, the second coupling element <NUM> is carried in a fixed manner with respect to rotation by the second rotating element <NUM>, i.e. it is configured to rotate about an axis C" together with (i.e. with the same angular speed as) such second rotating element <NUM>. In particular, the axis C" coincides, in use, with the axis B.

The first coupling element <NUM> and the second coupling element <NUM> have substantially the same shape. Therefore, for the sake of conciseness, only the first coupling element <NUM> is described hereinafter, using apex ' in its reference signs. The same reference signs are used for the second coupling element <NUM>, wherein apex " is used instead of apex '.

The first coupling element <NUM> extends substantially along the axis C' and comprises a hub portion <NUM>' and two axial projections <NUM>' extending therefrom.

The hub portion <NUM>' is fixed to the first rotating element <NUM>, preferably via a shape coupling. In particular, the hub portion <NUM>' has an internal spline <NUM>', realised along the axis C', complementary to an external profile (not shown) of the first rotating element <NUM>.

Conveniently, the hub portion <NUM>' and the first rotating element <NUM> have respective through-holes, orthogonal to axis C', wherein a screw <NUM>' can be inserted so that the hub portion <NUM>' and the first rotating element <NUM> are rigidly coupled.

The two axial projections <NUM>' are arranged on opposite sides of the hub portion <NUM>' with respect to the axis C'. In particular, the two axial projections <NUM>' have substantially the same structure, are parallel and face each other. Therefore, the hub portion <NUM>' and the two axial projections <NUM>' collectively define a housing <NUM>', which is substantially "U-shaped".

Furthermore, the two axial projections <NUM>' have respective through-holes <NUM>' having a common axis D', orthogonal to the axis C'.

The intermediate assembly <NUM> comprises a first arm <NUM> and a second arm <NUM> hinged together on an intermediate hinge axis E. Furthermore, the first arm <NUM> is movably coupled to the first coupling element <NUM> via a first movable connection <NUM> with two rotational degrees of freedom, the second arm <NUM> is movably coupled to the second coupling element via a second movable connection <NUM> with two rotational degrees of freedom.

Conveniently (<FIG>), the first movable connection <NUM> is realised by a first cruise <NUM>, operatively interposed between the first coupling element <NUM> and the first arm <NUM>, and the second movable connection <NUM> is realised by a second cruise <NUM>, operatively interposed between the second coupling element <NUM> and the second arm <NUM>.

In particular, the first cruise <NUM> comprises first ends <NUM>' configured to define a first hinge axis F', and second ends <NUM>' configured to define a first-coupling-element hinge axis G' which is orthogonal to the axis C' of the first coupling element <NUM>. The first arm <NUM> is hinged to the first cruise <NUM> on the first hinge axis F', and the first coupling element <NUM> is hinged to the first cruise <NUM> on the first-coupling-element hinge axis G'.

Similarly, the second cruise <NUM> comprises first ends <NUM>" configured to define a second hinge axis F", and second ends <NUM>" configured to define a second-coupling-element hinge axis G" which is orthogonal to the axis C" of the second coupling element <NUM>. The second arm <NUM> is hinged to the second cruise <NUM> on the second hinge axis F", and the second coupling element <NUM> is hinged to the second cruise <NUM> on the second-coupling-element hinge axis G".

Conveniently, the first cruise <NUM> is arranged in the housing <NUM>' of the first coupling element <NUM>, and its second ends <NUM>' engage the respective through-holes <NUM>' in a rotationally-free manner, thus realising the hinge connection between the first coupling element <NUM> and the first cruise <NUM>. In particular, the axis D' of the first coupling element <NUM> coincides with the first-coupling-element hinge axis G' of the first cruise <NUM>.

Similarly, the second cruise <NUM> is arranged in the housing <NUM>" of the second coupling element <NUM>, and its second ends <NUM>" engage the respective through-holes <NUM>" in a rotationally-free manner, thus realising the hinge connection between the second coupling element <NUM> and the second cruise <NUM>. In particular, the axis D" of the second coupling element <NUM> coincides with the first-coupling-element hinge axis G" of the second cruise <NUM>.

Preferably, the first ends <NUM>' of the first cruise <NUM> are orthogonal to the second ends <NUM>' of the first cruise <NUM>, and the first ends <NUM>" of the second cruise <NUM> are orthogonal to the second ends <NUM>" of the second cruise <NUM>.

Preferably, the first hinge axis F', the second hinge axis F" and the intermediate hinge axis E are substantially parallel to each other.

Referring back to <FIG>, the first arm <NUM> and the second arm <NUM> of the intermediate assembly <NUM> preferably have a substantially curved profile.

Conveniently, the intermediate assembly <NUM> (<FIG>) is symmetric with respect to a plane orthogonal to the intermediate hinge axis E.

According to the invention, intermediate assembly <NUM> (<FIG>) comprises an intermediate pin <NUM>, described in detail hereinafter, configured to define the intermediate hinge axis E.

The first arm <NUM> of the intermediate assembly <NUM> has first extremities 91a, 91b and second extremities 92a, 92b opposite to the first extremities 91a, 91b with respect to the main extension of the first arm <NUM>.

Similarly, the second arm <NUM> of the intermediate assembly <NUM> has first extremities 101a, 101b and second extremities 102a, 102b opposite to the first extremities 101a, 101b with respect to the main extension of the second arm <NUM>.

According to the invention, the first extremities 91a, 91b of the first arm <NUM> are coupled to the first coupling element <NUM> via the first cruise <NUM>, the second extremities 92a, 92b of the first arm <NUM> are coupled to the first extremities 101a, 101b of the second arm <NUM> via the intermediate pin <NUM>, and the second extremities 102a, 102b of the second arm <NUM> are coupled to the second coupling element <NUM> via the second cruise <NUM>.

Therefore, the two rotational degrees of freedom between the first arm <NUM> and the first coupling element <NUM> are realised by the hinge connection between first arm <NUM> and the first cruise <NUM> and the hinge connection between the first cruise <NUM> and the first coupling element <NUM>.

Similarly, the two rotational degrees of freedom between the second arm <NUM> and the second coupling element <NUM> are realised by the hinge connection between second arm <NUM> and the second cruise <NUM> and the hinge connection between the second cruise <NUM> and the second coupling element <NUM>.

In the exemplarily shown embodiment, the second extremities 92a, 92b of the first arm <NUM> are interposed, with respect to the intermediate hinge axis E, between the first extremities 101a, 101b of the second arm <NUM>. In other words, the second extremities 92a, 92b of the first arm <NUM> are axially internal, along the direction of the intermediate hinge axis E, between the first extremities 101a, 101b of the second arm <NUM>. In particular, the second extremities 92a, 92b of the first arm <NUM> are in contact.

Preferably, the intermediate pin <NUM> is fixedly carried by the first arm <NUM>. In particular, the intermediate pin <NUM> may be provided with pegs 113a, 113b extending orthogonally to the intermediate hinge axis E and engaging respective holes of the second extremities 92a, 92b of the first arm <NUM>.

Conveniently, the intermediate assembly <NUM> comprises bushings 121a, 121b operatively interposed between the first arm <NUM> and the second arm <NUM>, as described in detail hereinafter.

The bushings 121a, 121b are substantially coaxial to the intermediate hinge axis E. In particular, the bushings 121a, 121b are arranged around the intermediate pin <NUM>, preferably towards terminal portions 81a, 81b thereof. Conveniently, the terminal portions 81a, 81b have the same diameter, which is slightly smaller than the diameter of a central portion 81c of the intermediate pin <NUM> interposed between the terminal portions 81a, 81b.

In particular, the bushings 121a, 121b comprise hinge bushings 122a, 122b and damping bushings 123a, 123b.

Preferably, the damping bushings 123a, 123b are made of a plastic material.

The hinge bushing 122a and the damping bushing 123a, which are arranged around the terminal portion 81a of the intermediate pin <NUM>, have substantially the same structure as, respectively, the hinge bushing 122b and the damping bushing 123b, which are arranged around the terminal portion 81b of the intermediate pin <NUM>. Therefore, for the sake of conciseness, only the hinge bushing 122b and the damping bushing 123b are described hereinafter.

The hinge bushing 122b (see the enlarged detail in <FIG>) is interposed between the terminal portion 81b and the damping bushing 123b, in particular both axially and orthogonally with respect to the intermediate hinge axis E.

In particular, along the direction orthogonal to the intermediate hinge axis E, the hinge bushing 122b cooperates by contact, on its internal side, with the terminal portion 81b and, on its external side, with the damping bushing 123b. The damping bushing 123b cooperates by contact, on its internal side, with the hinge bushing 122b and, on its external side, with the first extremity 101b of the second arm <NUM>.

Preferably, the hinge bushing 122b comprises a flange portion 124b, and the damping bushing 123b comprise a flange portion 125b, thus having an "L-shaped" cross-section. In particular, the flange portions 124b, 125b face the first arm <NUM>.

Conveniently, along the direction of the intermediate hinge axis E, the hinge bushing 122b, in particular the flange portion 124b thereof, cooperates by contact, on its internal side, with the second extremity 92b of the first arm <NUM> and, on its external side, with the damping bushing 123b. The damping bushing 123b, in particular the flange portion 125b thereof, cooperates by contact, on its internal side, with the hinge bushing 122b, in particular the flange portion 124b thereof, and, on its external side, with the first extremity 101b of the second arm <NUM>.

Preferably, a radial clearance X is provided between the intermediate pin <NUM> and the first arm <NUM> or the second arm <NUM>. In particular, such radial clearance X is provided between the intermediate pin <NUM> and the arm (i.e. either the first arm <NUM> or the second arm <NUM>) whose extremities surrounding the intermediate pin <NUM> are axially external with respect to the intermediate hinge axis E. Therefore, in the exemplarily shown embodiment, the radial clearance X is provided between the intermediate pin <NUM> and the first extremities 101a, 101b of the second arm <NUM>.

Conveniently, radial clearance X is provided between the terminal portion 81a of the intermediate pin <NUM> and an axially terminal portion 131a of the first extremity 101a surrounding the terminal portion 81a itself.

Similarly, radial clearance X is provided between the terminal portion 81b of the intermediate pin <NUM> and an axially terminal portion 131b of the first extremity 101b surrounding the terminal portion 81b itself.

Conveniently, the radial clearance X is axially external, along the intermediate hinge axis E, with respect to the bushings 121a, 121b. In particular, the radial clearance X is opposite to the flange portions 124a, 125a, 124b, 125b of the respective bushings 122a, 123a, 122b, 123b.

Preferably, the radial clearance X is dimensioned so as to compensate the maximum admissible deflection of the axially terminal portions 131a, 131b of the respective first extremities 101a, 101b.

Conveniently, an axial clearance Y is provided between the bushings 121a, 121b and the first arm <NUM> or the second arm <NUM>. In particular, such axial clearance Y is provided between the bushings 121a, 121b and the arm (i.e. either the first arm <NUM> or the second arm <NUM>) whose extremities surrounding the intermediate pin <NUM> are axially external with respect to the intermediate hinge axis E. Therefore, in the exemplarily shown embodiment, the axial clearance Y is provided between the bushings 121a, 121b and the first extremities 101a, 101b of the second arm <NUM>.

Conveniently, axial clearance Y is provided between the bushings 122a, 123a and the axially terminal portion 131a of the first extremity 101a surrounding the terminal portion 81a.

Similarly, axial clearance Y is provided between the bushings 122b, 123b and the axially terminal portion 131b of the first extremity 101b surrounding the terminal portion 81b.

Conveniently, the axial clearance Y is axially external, along the intermediate hinge axis E, with respect to the bushings 121a, 121b. In particular, the axial clearance Y is opposite to the flange portions 124a, 125a, 124b, 125b of the respective bushings 122a, 123a, 122b, 123b.

Preferably, the axial clearance Y is dimensioned so as to compensate the maximum admissible deflection of the axially terminal portions 131a, 131b of the respective first extremities 101a, 101b.

Furthermore, the axial clearance Y and the radial clearance X together define an "L-shaped" overall clearance between the aforementioned elements.

Conveniently, each of the first arm <NUM> and the second arm <NUM> is realised in two pieces which are connectable to each other along the direction of the intermediate hinge axis E. In other words, the first arm <NUM> is realised in two pieces 51a, 51b which are connectable to each other along the intermediate hinge axis E, and the second arm <NUM> is realised in two pieces 52a, 52b which are connectable to each other along the direction of the intermediate hinge axis E.

Conveniently, the two pieces 51a, 51b realising the first arm <NUM> are symmetric with respect to a first plane orthogonal to the intermediate hinge axis E. Similarly, the two pieces 52a, 52b realising the second arm <NUM> are symmetric with respect to a second plane orthogonal to the intermediate hinge axis E. Preferably, such first plane and such second plane are coincident, i.e. they define the aforementioned plane with respect to which the intermediate assembly <NUM> is symmetric.

The first arm <NUM> has a central portion <NUM> interposed between its first extremities 91a, 91b and second extremities 92a, 92b and configured to join the two pieces 51a, 51b realising the first arm <NUM> itself. Conveniently, the central portion <NUM> is realised by respective central portions 141a, 141b of the respective pieces 51a, 51b realising the first arm <NUM>. In view of the structure and arrangement of its components, the first arm <NUM> has substantially a "Y" shape.

Similarly, the second arm <NUM> has a central portion <NUM> interposed between its first extremities 101a, 101b and second extremities 102a, 102b and configured to join the two pieces 52a, 52b realising the second arm <NUM> itself. Conveniently, the central portion <NUM> is realised by respective central portions 142a, 142b of the respective pieces 52a, 52b realising the second arm <NUM>. In view of the structure and arrangement of its components, the second arm <NUM> has substantially an "H" shape.

Conveniently, the first arm <NUM> comprises connecting means <NUM> configured to join its two pieces 51a, 51b. For example, the connecting means <NUM> of the first arm <NUM> comprise screws <NUM>' which extend parallel to the intermediate hinge axis E and can be inserted into respective through-holes provided in the central portion <NUM> of the first arm <NUM>.

Similarly, the second arm <NUM> comprises connecting means <NUM> configured to join its two pieces 52a, 52b. For example, the connecting means <NUM> of the second arm <NUM> comprise screws <NUM>' which extend parallel to the intermediate hinge axis E and can be inserted into respective through-holes provided in the central portion <NUM> of the second arm <NUM>.

Conveniently, the screws <NUM>', <NUM>' are configured to cooperate with respective support pins <NUM>', <NUM>' housed in the through-holes provided in the central portions <NUM>, <NUM>. In particular, the support pins <NUM>', <NUM>' are hollow and allow the respective screws <NUM>', <NUM>' to pass therethrough.

Preferably, the joint connection <NUM> also comprises a plurality of bearings, described in detail hereinafter. Conveniently, for each end of each cruise, one bearing is interposed between such end and the respective element to which such end is coupled.

The operation of the joint connection <NUM> according to the invention as described above is the following.

When the first rotating element <NUM> rotates about the axis A in response to rotation of the steering wheel, the first coupling element <NUM> rotates about the axis C', coincident with the axis A, with the same angular speed as the first rotating element <NUM>. The first cruise <NUM> is brought into rotation by the first coupling element <NUM>, in particular via the axial projections <NUM>' thereof. The intermediate assembly <NUM> is brought into rotation by the first cruise <NUM>, and brings into rotation the second cruise <NUM>. The second cruise brings into rotation the second coupling element <NUM>, in particular via the axial projections <NUM>" thereof. The second coupling element <NUM> rotates about the axis C", and the second rotating element <NUM> rotates about the axis B, coincident with the axis C", with the same angular speed as the second rotating element <NUM>.

The relative position between the axes A and B can be any, thanks to the two rotational degrees of freedom between the first coupling element <NUM> and the first arm <NUM>, the hinge connection between the first arm <NUM> and the second arm <NUM> of the intermediate assembly <NUM>, and the two rotational degrees of freedom between the second arm <NUM> and the second coupling element <NUM>.

Any relative displacements between the first coupling element <NUM> (and thus the first rotating element <NUM>) and the second coupling element <NUM> (and thus the second rotating element <NUM>) can be compensated for by the hinge connection between the first arm <NUM> and the second arm <NUM>. Indeed, the intermediate assembly <NUM> can move between an "open configuration", wherein the distance between the first extremities 91a, 91b of the first arm <NUM> and the second extremities 102a, 102b is maximum, and a "closed configuration", wherein such distance is minimum.

During the transmission of motion, via the joint connection <NUM>, from the first rotating element <NUM> to the second rotating element <NUM>, a tendency of homokinetic motion can be observed therebetween. Indeed, irrespective of the relative position between the first rotating element <NUM> and the second rotating element <NUM>, they have substantially the same angular speed due to the joint connection <NUM>, which thus tends to be a homokinetic joint.

During operation, there may be relative movements between the first arm <NUM> and the second arm <NUM> causing non-parallelism between the first hinge axis F', the second hinge axis F" and the intermediate hinge axis E. Such non-parallelism can be compensated by the bushings 121a, 121b. In particular, the radial clearance X and the axial clearance Y allow to compensate possible deflections of the second arm <NUM>, in particular of the axially terminal portions 131a, 131b, towards the intermediate pin <NUM>, in particular the terminal portions 81a, 81b.

When assembling the intermediate assembly <NUM> of the joint connection <NUM>, first the intermediate pin <NUM> is provided. Then, the two pieces 51a, 51b are connected to each other along the direction of the intermediate hinge axis E, thus realising the first arm <NUM>. In particular, the second extremities 92a, 92b of the first arm <NUM> come into contact with each other. After that, the bushings 121a, 121b are arranged on the respective terminal portions 81a, 81b of the intermediate pin <NUM>. Finally, the two pieces 52a, 52b are connected to each other along the direction of the intermediate hinge axis E, thus realising the second arm <NUM>.

In view of the foregoing, the advantages of the joint connection <NUM> according to the invention are apparent.

The joint connection <NUM> is an improvement of known joint connections in terms of assembly, noise production, and backlash compensation.

In particular, since each of the each of the first arm <NUM> and the second arm <NUM> is realised in two pieces which are connectable to each other along the intermediate hinge axis E, the assembly of the joint connection <NUM> is easier and the centring of its components is improved. Furthermore, the reliability and the precision of the joint connection <NUM> is increased.

The bushings 121a, 121b operatively interposed between the first arm <NUM> and the second arm <NUM> of the intermediate assembly <NUM> allow to reduce noise production, to dampen movements between the first arm <NUM> and the second arm <NUM>, to attenuate vibrations coming from other upstream and/or downstream elements, and to compensate for any non-parallelism between the first hinge axis F', the second hinge axis F" and the intermediate hinge axis E. In particular, the radial clearance X and the axial clearance Y allow to preserve the quality of motion in case of sudden cracking, jumping, mechanical performance worsening, and even impacts.

The support pins <NUM>', <NUM>' increase resistance to shear stresses and thus overall strength of the first arm <NUM> and the second arm <NUM>, each realised in two pieces.

It is clear that modifications can be made to the described joint connection <NUM> which do not extend beyond the scope of protection defined by the claims.

For example, the shape of the elements of the joint connection <NUM> may be different from that described.

The first arm <NUM> and the second arm <NUM> may be swapped with each other.

Claim 1:
Joint connection for a vehicle (<NUM>), comprising a first coupling element (<NUM>) configured to be coupled to a first rotating element (<NUM>), a second coupling element (<NUM>) configured to be coupled to a second rotating element (<NUM>), and an intermediate assembly (<NUM>) operatively interposed between the first and second coupling elements (<NUM>, <NUM>), wherein the intermediate assembly (<NUM>) comprises a first arm (<NUM>) and a second arm (<NUM>) hinged together on an intermediate hinge axis (E), the first arm (<NUM>) being movably coupled to the first coupling element (<NUM>) via a first movable connection (<NUM>) with two rotational degrees of freedom, the second arm (<NUM>) being movably coupled to the second coupling element (<NUM>) via a second movable connection (<NUM>) with two rotational degrees of freedom,
wherein each of the first arm (<NUM>) and the second arm (<NUM>) is realised in two pieces (51a, 51b, 52a, 52b) which are connectable to each other along the intermediate hinge axis (E);
said joint connection further comprising:
- a first cruise (<NUM>) operatively interposed between the first coupling element (<NUM>) and the first arm (<NUM>), the first cruise (<NUM>) defining the first movable connection; and
- a second cruise (<NUM>) operatively interposed between the second coupling element (<NUM>) and the second arm (<NUM>), the second cruise (<NUM>) defining the second movable connection;
the joint connection being characterized in that the intermediate assembly (<NUM>) comprises an intermediate pin (<NUM>) configured to define the intermediate hinge axis (E), wherein each of the first arm (<NUM>) and the second arm (<NUM>) has first extremities (91a, 91b, 101a, 101b) and second extremities (92a, 92b, 102a, 102b) opposite to the first extremities (91a, 91b, 101a, 101b), wherein the first extremities (91a, 91b) of the first arm (<NUM>) are coupled to the first coupling element (<NUM>) via the first cruise (<NUM>), the second extremities (92a, 92b) of the first arm (<NUM>) are coupled to the first extremities (101a, 101b) of the second arm (<NUM>) via the intermediate pin (<NUM>), and the second extremities (102a, 102b) of the second arm (<NUM>) are coupled to the second coupling element (<NUM>) via the second cruise (<NUM>).