"Door hinge for a vehicle"

Technical field of the invention The invention relates to a door hinge, particularly applicable to a car door. Background of the invention The hinges of some car doors, of the type comprising two hinge plates joined together in a canted way by a hinge bolt which passes through one or several tubular extensions on both hinge plates, comprise a braking element for generating a friction torque in the opposite direction to the relative turning movement between the hinge plates. In this type of hinge, one of the hinge plates is fixed to the vehicle's chassis while the other is fixed to the vehicle's door in such a way that the latter can turn around the axis of rotation, determined by the hinge bolt, although rubbing is produced between the moving parts. For this purpose, an antifriction sleeve is provided on the cylindrical cavity of at least one tubular extension of a hinge plate, said sleeve being interposed between the inner cylindrical surface of the tubular extension and the hinge bolt, whereby to open or close the vehicle door a turning torque is needed which exceeds a predetermined value, depending on the friction torque generated by the contact between the antifriction sleeve and the hinge bolt, and finally between both hinge plates. The rubbing sleeve, also called the antifriction sleeve, gives the hinge a dynamic behaviour which differs depending on the materials and dimensions of the sleeve, given that the braking torque generated by the antifriction sleeve depends greatly on the radial pressure between the external surface of the hinge bolt and the antifriction sleeve; and by the axial pressure which may be exerted on several flanges on the ends of the antifriction sleeve and which press on the end edges of the tubular extension where said sleeve is housed, it being possible to clip on these flanges via the adjoining edge of the tubular extension of the additional hinge plate. The antifriction sleeve, in its multiple variations, may be easily damaged during introduction of the hinge bolt in the tubular extension, the response of the hinge in its movement of opening and closing the door seen to be greatly affected. This problem . is solved by introducing the hinge bolt using the appropriate tools and, prior to introducing the bolt, by plastically and elastically deforming the antifriction sleeve so that on partially recovering its original form, it makes contact with the outer surface of the hinge bolt. However, in the modern construction of vehicles, it is usual to dismount the door after painting the assembled and adjusted array, separating it from the vehicle, in order to fit the door and the bodywork separately. Subsequently, on completing the final vehicle assembly, the doors are replaced in the correct position on the bodywork without having to carry out any further adjustment or alignment. Once the hinge bolt is adjusted, this operation involves having to remove it in order to be able to separate the door from the bodywork, it being possible to damage the antifriction sleeve, and also involves having to mount the door again in the final assembly of the vehicle whereby the hinge bolt must again be inserted in the tubular extensions of the hinge plates, whereby it is difficult for the final assembly to be like the original assembly with respect to its dynamic behaviour, since the antifriction sleeve may have been displaced and/or damaged during the dismounting and subsequent mounting. In addition, is it usual, during the final assembly of the hinge, to use a shaft or hinge bolt different from the one used in the original assembly, whereby the change in the dimensions of the diameter of the bolt, not yet within the established range of tolerances, as well as its different surface finishing, may significantly alter the turning torque of the door. This is the torque needed for opening and closing the door. The lack of an unhookable hinge is therefore noted, which allows dismounting and subsequent mounting, without the end functioning of the hinge being harmed and without the dynamic response of the hinge being altered or the antifriction sleeve of the hinge being damaged, all this so that dismounting and mounting does not become too complicated.

Explanation of the invention The hinge being the object of the invention, which resolves the abovementioned problems of the state of the art, is one which comprises a first hinge body and a second hinge body which are joined together via a hinge bolt, which forms the hinge shaft, one end of which is to form part of one of the two hinge bodies, both bodies having one or several portions with respective holes, axially aligned and superimposed when, in an operational position, both bodies are joined together in a canted way by the hinge bolt which passes through them simultaneously, the hole of at least one of said portions having an inner antifriction sleeve for producing a braking friction opposite to the turning of said portion around the hinge bolt. In essence, the hinge is characterized in that it also comprises a second rigid separating sleeve, interposed between the hinge bolt and the inner antifriction sleeve, to avoid direct contact between the outer surface of the hinge bolt and the aforementioned first antifriction sleeve, all this so that the hinge bolt can be removed from and reintroduced into the holes it passes through in the operational position, again separating and joining the hinge bodies, without damaging the first inner antifriction sleeve. According to another characteristic of the invention, when both hinge bodies are in an operational position, joined by the hinge bolt, the second separating sleeve forms part of the hinge body to which the hinge bolt is fixed, whereby when one of the hinge bodies turns, the inner antifriction sleeve rubs against the surface facing the second separating sleeve. In a preferred embodiment, the second separating sleeve is formed by an essentially cylindrical tubular body, suitable for being introduced in the hole of one of the portions of a hinge body, with an outer ringed rim, like a flange, which presses on the outside of one of the outer edges of the hole of said portion. In accordance with another characteristic of the invention, the hinge bolt has an opening or recess for tightening, to push on and exert pressure against the flange of the second separating sleeve, thus fixing it to the hinging body to which the hinge bolt forms a part. According to another characteristic of the invention, the first antifriction sleeve has on its two ends two outer ringed rims which remain pressed against the respective end edges of the hole of the portion of the hinge body wherein the antifriction sleeve is introduced, and in the operational position, one of the aforementioned outer ringed rims is embedded between one of said end edges and the flange of the second separating sleeve. In a preferred embodiment, the portions with respective holes are configured in the form of tubular extensions, which form part of the hinge bodies, axially aligned and superimposed in the operational position of the hinge. Brief description of the drawings The attached drawings show, as a non-limitative example, a preferred form of embodiment of the door hinge for a vehicle door. In said drawings: Fig. 1 is an exploded perspective view of the different parts forming the hinge; Fig. 2 is a perspective view of the assembled hinge unit in Fig. 1 ; and Fig. 3 is a elevational, cross-section detail of the hinge in Fig. 1.

Detailed description of the drawings The hinge represented in the drawings comprises a first hinge body 1 and a second hinge body 2, which are complementary and joined together in a canted way, in a form that is already known, via a hinge bolt 3 which forms the shaft thereof. In the example in Figs. 1 and 2, the hinge body 1 comprises two portions which make up tubular extensions 5 and 7 both with a hole 5' and T, respectively, said tubular extensions being separated and axially aligned, the hinge body 1 having a U-shape, while the second hinge body 2 has a single portion with a hole 6' and also configured in the form of a tubular extension 6. In Fig. 1 it can be seen that the hinge comprises a first antifriction sleeve 8, for producing a braking friction opposite to the relative turning movement between the two hinge bodies 1 and 2, which determines the minimum turning torque that the user must apply on the second hinge body 2 to make it turn around the hinge bolt 3. This antifriction sleeve 8 may be made, according to a known method, of a plastic material, which could be reinforced with a metal structure. This antifriction sleeve 8 is suitable for being introduced in the hole 6' of the tubular extension 6, wherein it is housed during the subsequent functioning of the hinge. As can be seen in Fig. 1 , the antifriction sleeve 8 has on its two ends two outer ringed rims 14 and 15 which are to press against the end edges 12 and 16 of the tubular extension 6. The hinge in the invention also comprises a second rigid separating sleeve 9, formed by an essentially cylindrical tubular body 10 and suitable for being introduced in the hole 6' of the tubular extension 6, so that the outer surface of this second separating sleeve 9 remains pressed against the antifriction sleeve 8, previously introduced in the cavity of the same tubular extension 6. The aforementioned second separating sleeve 9 has an outer ringed rim, like a flange 11, for pressing on the outside of the outer edge 12 of the tubular extension 6 as shown in Fig. 3, the outer ringed rim 14 of the first antifriction sleeve 8 being embedded between the flange 11 and the aforementioned outer edge 12 of the ringed extension 6. In the operational position in Figs. 2 and 3, the tubular extension 6 of the second hinge body 2 is situated between the tubular extensions 5 and 7 of the additional hinge body, and axially aligned with these, the tubular extensions of the two hinge bodies 1 and 2 being alternately axially aligned and superimposed. The lower end 4 of the hinge bolt 3, which passes through the holes 5' and 6' of the tubular extensions 5 and 6, forms part of the lower tubular extension 7 of the first hinge body 1 by a screwing action. For this purpose, the hole T of said lower tubular extension 7 has internal screw threading. The recess 13 of the hinge bolt 3 exerts pressure against the flange 11 of the second separating sleeve 9, in such a way that the more the lower end 4 of the bolt 3 is screwed on to the tubular extension 7 of the first hinge body 1 , the greater the pressure that the recess 13 exerts on the flange 11. As a result, in the operational position of the hinge, the second separating sleeve 9 forms part, by the pressure of the bolt 3, of the first hinge body 1 and the hinge bolt 3, in such a way that with a relative turning movement between the hinge bodies 1 and 2 around the hinge shaft, there is friction between the first antifriction sleeve 8 and the second separating sleeve 9. Depending on the contact pressure between the facing surfaces of the two sleeves 8, 9 and of the pressure exerted on the outer ringed rims 14 and 15, the first embedded between the flange 11 and the outer edge 12 of the tubular extension 6; and the second between the outer edges of the tubular extensions 7 and 6 and the hinge bodies 1 and 2, respectively, the braking force opposing the turning movement will be higher or lower. Unlike known embodiments, the flange 11 protects the outer ringed rims 14 and 15 from the antifriction sleeve 8 during assembly of the hinge, especially at the time when the tubular extension 6 of the second hinge body 2 must be positioned between the tubular extensions 5 and 7 of the first hinge body 1. Similarly, the subsequent adjustment via the screwing action of the bolt 3 allows a greater play of tolerance whereby it stays within the distance of separation between the tubular extensions 5 and 7, of the first hinge body 1 , and the length of the tubular extension 6, of the second hinge body 2, which must be positioned between the first ones, thus facilitating assembly of the hinge. The second separating sleeve 9, once introduced in the hole 6' with the antifriction sleeve 8, is not removed again and remains inside the hole during subsequent assembly work on the car, wherein the hinge bolt 3 is removed and reintroduced to dismount and remount the new hinge 1. The second separating sleeve 9, during dismounting of the hinge, stops the hinge body 3 from damaging the antifriction sleeve 8 since the bolt has no direct contact whatsoever with said antifriction sleeve 8. The same occurs in the subsequent assembly of the hinge, since introduction of the hinge bolt 3 in the tubular extension 6, wherein the antifriction sleeve 8 is housed, is done through the inside of the tubular body 10 of the second separating sleeve 9, the wall whereof remains interposed between the hinge bolt 3 and the antifriction sleeve.