Reinforced Ball Joint with Rotation Sensor

Abstract

A spherical joint, which comprises a body (1) of the joint, in which a pin (2) is inserted, the pin having a longitudinal axis and comprising a first threaded end (8) and a second spherical end (10), the second spherical end being rotatably arranged within a seat (14) of said body (1) and being able to cooperate with a first spherical cap-shaped element or shell (20) inserted within a seat of corresponding shape of a second spherical cap-shaped element or shell (21), the second spherical cap-shaped element or shell cooperating with a covering element (32) to enclose the spherical end (10) of the pin (2) within said body (1), the second spherical end (10) of the pin (2) and the first and second shells comprising pairs of recesses (40, 46) and ridges (41, 47) in contact areas suitable for reciprocal penetration, said pairs of recesses and ridges being arranged at 90° to each other to allow the pin (2) to rotate along all axes in space (X, Y, Z), an angular motion sensor (55) integral with the said body of the joint (1) being provided, the angular motion sensor being suitable for cooperating with the second element or shell (21) in order to detect the rotation of the pin (2) about said axis including the longitudinal axis of the pin itself.

Description

Technical Field

[0001] The present invention relates to a reinforced spherical joint according to the preamble of the independent claim. Background Art

[0002] Known spherical joints allow relative rotation between two components of a suspension along three axes in space, thus providing three independent rotational degrees of freedom.

[0003] The main problem affecting the use of such joints lies mainly in the difficulty of measuring the angle of rotation about the axis of the joint (especially about the Z-axis in space, i.e., the longitudinal axis of the joint itself), which is very important for certain applications. For example, being able to measure the angle of rotation about the vertical axis (or Z-axis) of the body in order to accurately calculate the steering angle is the basis for developing autonomous vehicles.

[0004] Solutions related to joints are known where the rotation about the Z-axis in space is measurable.

[0005] For example, patent document WO2016 / 147067 discloses a single-suspension wheel steering system that includes a sensor device adapted to measure the angle of rotation of its joint about the Z-axis. In particular, this prior art patent discloses a joint defined by a group or assembly of pins that extend about a pivot axis and include a spherical section inserted into a body or a rotating device, and the pins are disposed within an external bearing element adapted to allow only the entire body to rotate about the Z-axis. The pins are penetrated by a cylindrical plug passing through the center of rotation, the purpose of which is to allow oscillatory movement about the X-axis and Y-axis and prevent rotational movement of the pins about the Z-axis. An angle sensor measures the rotation between the body and the bearing seat portion.

[0006] Even though this solution allows the evaluation of the rotation of the joint about the Z-axis, it may have key problems in the following aspects: the machinability of the pins for inserting the plugs, the assembly of many components, and the overall large size of the pins due to the presence of bearing elements outside the body where the pins rotate.

[0007] Patent document EP1726512 discloses a steering angle sensor associated with a joint of a vehicle's wheel suspension. According to this prior art patent, the joint includes a pin whose spherical end is associated with an upper transverse element of the steering device and is adapted to rotate about the vertical axis or Z-axis in space. The upper end portion of the spherical section of the pin includes an opening of a recess that has a frustoconical shape extending to the center of the section. A drive shaft is hinged at this point and allows the pin to oscillate about the X-axis and Y-axis, and the shaft is driven to rotate about the Z-axis and allows its angle measurement. The opposite end of the shaft is integral with the rotor of an external angle sensor fixed to the body of the joint.

[0008] This known solution, even if it allows for angular measurement of the rotation of the joint about the Z-axis, is affected by problems related to the following: the possible weakening of the spherical segment due to the presence of the conical cavity, the precision required for machining the pins, and the tight tolerances of the connections between the joint, the drive shaft, and the sensor. Summary of the Invention

[0009] An object of the present invention is to provide a spherical joint by means of which it is possible to measure the angle of rotation about the longitudinal axis of the pin of the joint, that is, according to the Z-axis in space.

[0010] In particular, an object of the present invention is to provide a joint of the above type which is compact and easier to implement compared to known joints.

[0011] Another object is to provide a joint which is less subject to wear compared to known solutions and which, compared to known solutions, does not require substantial modification of its configuration, but at the same time is not equipped with complex devices suitable for performing angular measurements, in order to allow it to be closely integrated with the remaining parts of the mechanical element, for example, as a component of a suspension.

[0012] These and other objects are achieved by a spherical joint according to the appended claims. Brief Description of the Drawings

[0013] The following drawings are attached for illustrative and non-limiting purposes only in order to better understand the present invention, in which:

[0014] Figure 1 A exploded view of a spherical joint according to the present invention is shown;

[0015] Figure 2 is shown according to Figure 1 a cross-sectional view taken along line 2-2 in;

[0016] Figure 3 is shown according to Figure 1 a cross-sectional view taken along line 3-3 in;

[0017] Figure 4 is shown from Figure 1 a partial simplified perspective view of the other side of the joint in; and

[0018] Figure 5 is shown Figure 1 an enlarged perspective view of the section identified by the letter A in. Detailed Description of the Embodiment

[0019] Referring to the attached drawings, the ball joint includes a body 1 and a pin 2 that are coupled to each other. The body 1 has a bowl shape and includes a cylindrical portion 3 that is open at a first end 4; the body 1 includes an annular section 6 at a second end of the portion 3, and the annular section 6 defines a hole 7.

[0020] The stem 2A and the tapered section 2B of the pin 2 pass through the hole 7; such a pin has a threaded first end 8 and a second spherical end 10. The second spherical end 10 is enclosed between a first covering element 12 and a second covering element 13, and these two covering elements have the shape of spherical sections or regions that are complementary to and opposite each other with respect to the second end; the second spherical end 10 is disposed within the cylindrical portion 3, and the cylindrical portion 3 includes a seat 14 in the shape of a spherical cap, and the first covering element 12 is arranged between the seat 14 and the second spherical end 10. The second covering element 13 is placed between the second spherical end 10 and an outer cylindrical washer 17, and the outer cylindrical washer 17 also has an inner seat 18 in the shape of a spherical cap.

[0021] A first spherical-cap-shaped shell 20 is inserted into the washer and is located on a part of the second spherical end 10 of the pin 2 or on the spherical cap 19, and is in turn inserted into a second spherical-cap-shaped shell 21. Both the first spherical-cap-shaped shell 20 and the second spherical-cap-shaped shell 21 are arranged (together with the washer 17) inside the body 1 of the joint.

[0022] A protective flexible covering 25 is associated with the body 1 corresponding to the annular section 6, and annular seals 26 and 27 are associated with the body 1.

[0023] Another annular seal 30 is placed between the body 1 and the washer 17; a covering or annular closing element 32 finally exists on the washer and on the second spherical-cap-shaped shell 21 to enclose the body 1 of the joint (fixed to the body in a manner known per se and forming a receiving element that receives the second spherical end 10 of the pin 2), and all the elements have been assembled by means of plastic deformation of the usual dedicated sections of the body 1. Finally, seals 33 and 34 correspondingly exist with respect to the annular closing element 32.

[0024] In the spherical cap 19 of the second spherical end 10 of the pin 2, recesses or grooves 40 are derived that are arranged along the Y-axis in space (see the representation of the three axes in space in Figure 1 . The recesses or grooves 40 are adapted to cooperate with ridges 41 that project (also arranged along the Y-axis) inside the first spherical-cap-shaped shell 20.

[0025] Recesses or grooves 46 that are arranged along the X-axis and are derived on the outer surface 43 (referred to as the pin 2) of the first spherical-cap-shaped shell 20 are adapted to cooperate with corresponding ridges 47 that are provided on the inner surface of the second spherical-cap-shaped shell 21 (also arranged along the X-axis).

[0026] The fit between the grooves 40 and 46 and their respective ridges 41 and 47 (which are joined to each other in a convex-concave relationship) enables the pin 2 to move within the body 1 of the joint. In fact, the fit between the groove 40 and the ridge 41 enables rotational movement about the Z-axis (i.e., the longitudinal axis of the pin 2) and about the Y-axis to be transmitted between the pin 2 and the first spherical cap-shaped housing 20; all this is possible because the X-axis is positioned at an angle of 90° with respect to the groove 40 and with respect to the ridge 41, so free rotation about the X-axis is possible.

[0027] On the other hand, the fit between the groove 46 and the ridge 47 enables rotational movement about the Z-axis (i.e., the longitudinal axis of the pin 2 and thus the longitudinal axis of the spherical joint) and about the X-axis to be transmitted between the first spherical cap-shaped housing 20 and the second spherical cap-shaped housing 21, and free rotation about the Y-axis is possible because the Y-axis is arranged at 90° with respect to the groove 46 and the ridge 47.

[0028] Finally, the section 51 of the second spherical cap-shaped housing 21 facing the annular closing element 32 is cylindrical so that the housing, the pin, and thus the joint can rotate only about the Z-axis (i.e., the longitudinal axis of the pin). This section 51 penetrates the opening 56 of the annular closing element 32 until it reaches the end of the closing element; in said section 51, a seat 52 is derived (for example, a seat having a polygonal wall 53 or a seat having a geometrically similar shape in cross-section), and this seat 52 is adapted to receive a movable element (which has a housing), such as a magnetic element or a mechanical drive shaft (not shown). Such a movable element is adapted to cooperate with an angular displacement sensor or an angular encoder 55 of a type known per se (for example, provided with a drive shaft or of the magnetic type) and integral with the body 1, as Figure 4 schematically shown in.

[0029] Therefore, the joint according to the present invention is able to provide precise and continuous control of the position about the Z-axis of the pin, thanks to a realization solution that is simpler, mechanically more reliable, and more robust in terms of wear compared to known solutions. Additionally, compared to existing spherical joints that perform the same mechanical linking function between two components of a suspension, the dimensions of this joint have hardly changed (however, existing spherical joints cannot measure the angle of rotation), which also facilitates the installation of this joint in the mechanical structure of the suspension of known and commercially available vehicles.

[0030] Specific embodiments of the present invention have been described above. However, other embodiments are possible: for example, the torsional connections between the second spherical end 10 and the first spherical cap-shaped shell 20, and between the first spherical cap-shaped shell 20 and the second spherical cap-shaped shell 21 can also be obtained by other means known to those skilled in the art (for example, by inverting the grooves and ridges on the components relative to the above arrangement), while allowing rotation about the X-axis and Y-axis of the pin respectively.

[0031] These solutions are also considered to fall within the scope of the present invention.

Claims

1. A spherical joint, including the body (1) of the joint, wherein, A pin (2) is inserted into the body, the pin (2) having a longitudinal axis and including a first end (8) and a second spherical end (10), the second spherical end having a spherical shape, the second spherical end (10) being rotatably arranged within a seat (14) of the body (1), characterized in that a first spherical cap-shaped shell (20) is inserted into a seat of corresponding shape within a second spherical cap-shaped shell (21), the second spherical cap-shaped shell (21) cooperating with an annular closing element (32) to enclose the second spherical end (10) of the pin (2) within the body (1), the second spherical end (10) of the pin (2) and the first and second spherical cap-shaped shells including reciprocating torsional coupling elements (40, 46; 41, 47) so as to allow the pin (2) to rotate about all axes in a space (X, Y, Z), the longitudinal axis of the pin coinciding with one of the axes (Z-axis) in the space (X, Y, Z), an angular displacement sensor (55) being provided integral with the body (1) of the joint, the angular displacement sensor (55) being adapted to cooperate with a magnetic or mechanical drive element, integral with the second spherical cap-shaped shell (21), so as to estimate the rotation of the pin (2) of the joint about the longitudinal axis of the pin (2) itself, the reciprocating torsional coupling elements including pairs of grooves (40, 46) and ridges (41, 47), the pairs of grooves (40, 46) and ridges (41, 47) being derived from within and on the contact surfaces of the second spherical end (10) of the pin (2), the contact surface of the first spherical cap-shaped shell (20), and the contact surface of the second spherical cap-shaped shell (21).

2. The spherical joint according to claim 1, characterized in that The second spherical end (10) of the pin (2) includes: a spherical cap (19) inserted into the first spherical cap-shaped shell (20), and a groove (40) provided in the spherical cap (19) of the second spherical end (10), the groove (40) being adapted to cooperate with a ridge (41) provided on the surface of the first spherical cap-shaped shell (20) in direct contact with the pin (2).

3. The ball joint according to claim 1, characterized in that, The outer surface (43) of the first spherical cap-shaped shell (20) includes a groove (46), the groove (46) being adapted to receive a ridge (47) protruding from the inner surface of the second spherical cap-shaped shell (21) in contact with the first spherical cap-shaped shell (20).

4. The ball joint according to claim 1, characterized in that, The second spherical cap-shaped shell (21) includes a section (51) facing the outside of the spherical joint, the section (51) having a seat (52) adapted to accommodate a mechanical drive element or a magnetic element.

5. The ball joint according to claim 4, characterized in that, The section (51) of the second spherical cap-shaped shell is cylindrical.

6. The ball joint according to claim 5, characterized in that, The cylindrical section (51) is inserted into the opening (56) of the annular closing element (32) which is formed in an annular shape.

7. The ball joint according to claim 1, characterized in that, The angular displacement sensor (55) is arranged corresponding to the annular closing element (32) and is integral with the body (1) of the joint.

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