Field of the Invention

The present invention refers to an improvement introduced in the retaining ring for the damping elements of elastic couplings, more particularly of elastic couplings for torque transmission, which maintain the damping elements, made in an elastomeric material, adequately and securely retained in the interior of their respective housings, said retaining ring being constructed to present, not only a longer useful life and an adequate electric insulation in the elastic couplings in which it is applied, but also a considerably simplified construction which provides a reliable rotational and axial retention of the retaining ring around the coupling.

Prior Art

The known torque transmission elastic couplings are used for joining two machine elements, allowing the transmission of torque from one to the other, absorbing vibrations and shocks and compensating radial, axial and angular misalignments, in order to protect the machine elements coupled thereto, as it occurs with the coupling between two coaxially aligned torque transmission shafts.

The elastic couplings of the type considered herein are configured by a pair of symmetrical hubs, generally made of cast iron, each hub being provided with radial housings which cooperate with respective radial housings of the other hub, for the fitting of respective damping elements, in elastomeric material, for example, polyurethane , which is resistant to mineral oils and to wear.

In order to provide the retention of said damping elements in the respective cooperating pairs of housings of the two symmetric hubs of each elastic coupling, it is conventionally used a retaining ring, disposed around the junction region of the two hubs, over the radially outermost ends of the damping elements, in order to maintain the latter retained in the interior of the respective housings. The damping elements transmit, to the inner walls of the respective housings, the forces to be transmitted between the two hubs of the elastic coupling.

It is known the retaining rings, manufactured in steel or polyurethane and presenting a generally rectangular cross section, which are positioned between two circumferential and parallel alignments of bolts radially secured in the hubs and having their heads projecting outwardly from the hubs, each alignment being defined by bolts affixed in one of the two hubs constitutive of the elastic coupling.

The retaining rings, when made in steel, lead to a quick wear of the assembly, caused by the constant contact/friction of each of its lateral edges with the heads of the bolts belonging to the adjacent circumferential alignment of bolts. The wear of the bolt heads may rapidly achieve a condition which allows the retaining ring to move away from the positioning in which it retains the damping elements, allowing the latter to move out from their respective housings, thus impairing the correct operation of the elastic coupling.

On the other hand, the retaining rings made of polyurethane, although providing electric insulation and having the advantage of not wearing the heads of the retaining bolts, they do not have the adequate mechanical strength to withstand the forces applied thereon by the constitutive elements of the elastic coupling, thus presenting deformations after a short time of use, and allowing the damping elements to escape out of their respective housings.

As a function of the deficiencies of the retaining rings made in metallic or elastomeric material, the present applicant developed the retaining ring object of the Brazilian patent application PI 1001425-0, which presents a longer useful life and impedes the circulation of electric charges in the elastic coupling .

In the solution proposed in said prior patent application PI 1001425-0, it is provided a retaining ring formed by a metallic tape, having a rectangular cross section with opposite lateral edges, and which is mounted around the joining region of the two hubs of the coupling, over the damping elements and between the bolt circumferential alignments, the metallic tape being totally covered by a electrically nonconductive elastomeric coating, incorporating, close to at least one of the lateral edges of the metallic tape, at least one pair of axial projections, which are spaced apart so as to define a regulating spacing, inside which is positioned one of the bolts.

In said prior art solution of the present applicant, the retaining ring, coated with elastomer, impedes the circulation of electric charges through the elastic coupling and is rotatively locked, in relation to the latter, by actuation of a pair of axial projections against one bolt of one of the bolt circumferential alignments of one of the hubs of the elastic coupling. The axial locking of the retaining ring is made by the two circumferential alignments of bolts .

While defining a construction which is considerably improved in relation to the state of the art at the time PI 1001425-0 was filed, said prior art solution may be further improved, regarding the necessary elements for the adequate axial and rotational locking of the retaining ring. In the previous solution, it is necessary to provide two bolt circumferential alignments, each alignment being provided in a respective hub of the elastic coupling, in order to obtain the axial locking of the retaining ring in opposite senses. This constructive characteristic requires the provision and the mounting of two bolt assemblies and also allows for a certain axial and rotational wearing motion, even if reduced, between the retaining ring, including the axial projections, and the bolts affixed in the two symmetric hubs. Summary of the Invention

From the above, the present invention has the object to provide a retaining ring of the type described and claimed in the Brazilian patent application PI 1001425-0, but which is improved to promote, not only a longer useful life and an adequate electric insulation to the elastic couplings in which it will be applied, but also a considerably simplified construction, in terms of component parts and mounting operations, and which provides a secure rotational and axial retention of the retaining ring around the coupling .

Brief description of the drawings

The invention will be described below, with reference being made to the appended drawing, given by way of example of one non-limiting embodiment of the invention and in which:

Figure 1 represents an exploded perspective view of an elastic coupling which has been improved according to the present invention;

Figure 2 represents a perspective view of the elastic coupling and of the retaining ring, illustrated in figure 1, but in the mounted condition .

Figure 3 represents a perspective view of the same retaining ring illustrated in figures 1 and 2, but with the coating being partially cut, in order to illustrate an optional constructive detail of the metallic tape; and

Figure 4 represents a sectional view of the retaining ring, taken according to line IV- IV in figure 3.

Detailed description of the invention

As mentioned before and illustrated in the appended drawings, the present invention refers to an improved retaining ring 10, to be applied to an elastic coupling AT, more particularly to a torque transmission elastic coupling, of the type comprising two equal hubs 20 which are generally made of cast iron or any other adequate material.

The hubs 20 define, jointly and in a mutual region, a plurality of radial housings 21, each one being partially defined in each of the two hubs 20, by respective radial housing portions 21a. The radial housing portions 21a, which are formed in each of the hubs 20, cooperate with the confronting and respective radial housing portions 21a of the other hub 20, in order to form, jointly, each radial housing 21, inside which is lodged a respective damping element 30, made of elastomeric material such as, for example, polyurethane, and generally presenting a cylindrical shape .

Each hub 20 is provided with a circumferential alignment of threaded radial holes 22, equally spaced from one another and slightly spaced from the joining plane of both hubs 20. In the illustrated constructive example, each hub 20 is provided with three threaded radial holes 22.

For providing the retention of said damping elements 30 in the respective housings 21, in the junction region of the two hubs 20 of the elastic coupling AT, it is provided the retaining ring 10, seated around the junction region of said two hubs 20, over the radially outermost ends of the damping elements 30, so as to maintain the latter retained in the interior of the respective radial housings 21.

The retaining ring 10 is formed by a continuous metallic tape 11, presenting lateral edges 11a and which is covered by a coating 12, made of an electrically non- conductive elastomeric material, for example, polyurethane 70 shore D, for avoiding the contact of the metallic tape 11 with the hubs 20.

According to the present improvement, the metallic tape 11 incorporates, in one of its lateral edges 11a, a plurality of axial projections lib equally spaced from each other, provided with a throughole 11c and covered with the coating 12, so as to form respective axial wings 13 in the retaining ring 10, which wings 13 are designed to be seated on one of the hubs 20 and provided, each one, with a throughole 14, coinciding with the respective throughole 11c, for receiving a bolt 40, to be affixed in a respective threaded radial hole 22 of the circumferential alignment of threaded radial holes 22 of said hub 20, onto which are seated the axial wings 13 of the retaining ring 10.

In the illustrated construction, each bolt 40 presents a head 41 which is entirely lodged in the interior of the throughole 14 of each respective axial wing 13 of the retaining ring 10, the axial wings 13 of the retaining ring 10 being provided generally in the same number of the threaded radial holes 22 of each hub 20, this number being preferably three.

Still according with a constructive form of the retaining ring 10, the metallic tape 11 is made of steel and provided with multiple through openings lid, defined along the circumferential extension of the metallic tape 11 and which are filled with the material of the coating 12, in order to allow the portions of the coating 12, which are seated on the outer and inner annular walls of the metallic tape 11, to be joined to each other in a single piece, increasing the fixation strength of said coating 12 when affixed to the metallic tape 11.

With the new constructive arrangement proposed by the present invention, the retaining ring 10 has its rotation and its opposite axial displacements, in relation to the elastic coupling AT, blocked by the bolts 40 which are housed, each one, in the interior of the throughole 14 of the respective axial wing 13 of the retaining ring 10, eliminating the friction wear between the head 41 of the bolts 40 and the retaining ring 10, which is kept immobilized in relation to the bolts 40 and to the hub 20 in which it is affixed. The coating 12 impedes the circulation of electric charges in the elastic coupling.

While the invention has been described in relation to only one embodiment illustrated in the drawings, it should be understood that some changes can be made in the form of the retaining ring and in the other parts of the elastic coupling, without departing from the constructive concept defined in the claim set which accompanies the present specification.