Rotation retarder and use thereof

Abstract: The retarder has a stator (1), a rotor (3) designed to receive the rotation movement to be retarded, and an elastic means disposed between the rotor and the stator, the stator (2) having a seat (4) from which projects a shaft (6) with an overall cylindrical wall, the rotor (3) having a housing (13) with an overall cylindrical wall for rotational mounting on the shaft (6). The said retarder (1) is characterised in that the said elastic means (10) is in direct contact with the wall of the shaft (6) and wall of the housing (13) between which it is compressed, the area of contact between a first one of these walls and the elastic means (10) being larger than the area of contact between the second of these walls and the elastic means, whereby the elastic means is held on the first wall whilst the second wall is able to slide with respect to the elastic means.

Description: The present invention relates to a rotation retarder which includes a stator and a rotor designed to receive the rotation movement to be retarded. Many components, mounted in motor vehicles, but not exclusively, such as handles, glove-box lids, ashtray lids or others, have their opening controlled for example by springs. The movement caused by the spring is generally abruptly arrested by a stop. This gives rise to more or less intense noises and more or less violent impacts between the corresponding component and the stop. From FR-A-2 674 588 of French patent application 92-03741, a rotation retarder is known, by means of which the movements of the components caused by the spring are braked. This retarder includes a stator consisting of two cup-shaped pieces, one of which fits on top of the other in order to form a housing in which an O-ring made of elastic plastic is disposed against the peripheral wall, whilst it surrounds a circular component of smaller diameter forming part of the rotor, balls being disposed between the ring and the circular component, which for this purpose has notches in its periphery, the rotational mounting of the rotor being effected by means of a small spindle which the stator has at the centre of the housing, projecting with respect to the bottom thereof, the part of the rotor of which the circular component forms part having in its centre a bore engaged on this spindle, this part also having, opposite this bore, a shaft which passes through the stator cover by means of a hole formed at the centre of the cover, the rotor also having, outside the housing, a pinion fixed to this shaft in order to receive the rotational movement to be retarded. The invention aims to improve this type of retarder, notably with regard to the accuracy of the braking torque obtained. It also aims to produce a rotation retarder having a small number of parts, easy to manufacture and to assemble, the retarder obtained thus proving to be inexpensive. To this end it proposes a rotation retarder having a stator, a rotor designed to receive the rotation movement to be retarded, and an elastic means disposed between the rotor and the stator, the stator having a seat from which projects a shaft with an overall cylindrical wall, the rotor having a housing with an overall cylindrical wall for rotational mounting on the shaft, the said retarder being characterised in that the said elastic means is in direct contact with the wall of the shaft and wall of the housing between which it is compressed, the area of contact between a first one of these walls and the elastic means being larger than the area of contact between the second of these walls and the elastic means, thereby the elastic means is held on the first wall whilst the second wall is able to slide with respect to the elastic means. The retarder thus obtained offers a braking torque depending essentially on the characteristic of the elastic means and on the radial stress applied to the latter because it is compressed. Since such arrangements are easy to implement during manufacture, the retarder according to the invention offers torque values which can be determined accurately and which remain constant over time. In addition, this manufacture proves relatively easy, because of the small number of parts to be produced and assembled, in particular where at least some parts are obtained by plastic moulding. According to characteristics which are preferred for their simplicity and ease of implementation: the said elastic means is an annular component housed in a recess delimited by the said first wall, the said annular component is in contact with a cylindrical surface of the said second wall. In order to prevent any decoupling of the rotor and stator, the retarder also has steps disposed on the circumference of the wall of the said housing, adapted to come into abutment against the said elastic annular component if an axially oriented translational movement tends to move the said rotor away from the said stator. Advantage is taken here of the presence of the annular component to effect a translational connection which is particularly easy to produce and which has no effect on the braking torque. The internal face of the steps is advantageously curved. In order to prevent the friction between the rotor and stator due to the rotational guidance of one with respect to the other being irregular, which would disturb the regularity of the braking torque procured, the rotor is advantageously provided with studs affording contact with the said rotor, with a rounded top and distributed with regular angular spacing on the end of the rotor facing the said seat. Advantageously also, the shaft of the stator has a body in which the said recess is hollowed out whilst centring surfaces are disposed so as to project with respect to the body. The annular component received in the recess, coming into abutment here against the centring surfaces if a translation movement tends to move the rotor away from the stator, in this way the translational connection mentioned above is improved. In addition, the friction due to the mounting between the rotor and stator is further limited, which reduces to the maximum extent the effect of this type of friction on the braking torque. According to another aspect, the present invention concerns the use of a retarder as disclosed above to retard the rotation movement of a first component, in engagement with the said rotor, with respect to a second component to which the said stator is fixed. The rotation retardation of a component rotating with respect to another component thus proves particularly easy to achieve. This aspect of the invention is also very interesting where the said first component is a door mounted so as to rotate on the said second component. The disclosure of the present invention will be continued with the description of a preferred embodiment, given below for illustration and non-limitatively, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a retarder according to the preferred embodiment of the invention; Figure 2 is a plan view of the stator of this retarder; Figure 3 is an elevation view in section along a plane of symmetry of this same retarder; Figure 4 is a plan view of the rotor of the retarder; and Figure 5 is a view in cross section of the rotor of Figure 4, taken along the cutting line V-V in this last figure. The rotation retarder 1 shown in Figures 1 to 5 has a stator 2 and a rotor 3 designed to receive the rotation movement to be retarded. As can be seen particularly in Figure 3, the stator 2 has a seat in the form of a cup 4, extended on the one hand, on the same side as the base 5 of the cup, by a shaft 6 with an overall cylindrical wall and on the other hand by two diametrically opposed lugs 7 for fixing the stator. One of the lugs 7 has a circular fixing hole 8 and the other an oblong fixing hole 9 offering a certain amount of play in the positioning of the fixing means designed to pass through this hole 9. The stator 2 and rotor 3 are each made of plastic moulded in a single piece. An elastic O-ring 10, here made of flexible plastic, is interposed and compressed radially between the stator 2 and rotor 3, in a manner which is detailed below. The rotor 3 is formed from a section of cylinder 11, open at both ends, and on the circumference of which, and over substantially half its length, teeth 12 forming a pinion are disposed. This section of cylinder 11 forms a housing 13 with an overall cylindrical wall for the rotational mounting of the rotor on the shaft 6 of the stator 2. In this case, the shaft 6 has a body and at its end furthest away from the base 5 there are disposed, projecting with respect to the body, over substantially half of its length, four centring surfaces 15a-15d with regular angular spacing. The section of cylinder 11 is guided in rotation on these surfaces 15a-15d. Rotational guidance of this type naturally proves to be easier than on a continuous surface. In addition, such arrangements make it possible to reduce to the maximum extent the areas of contact between the rotor 3 and stator 2, limiting the friction due to the mounting, designed to brake the rotor 3, solely through contact of this rotor 3 with the elastic O-ring 10. For the same reasons of reduction of the areas of contact between the rotor 3 and stator 2, the section of cylinder 11 comes into contact with the base 5, solely by means of three contact studs 16a-16c distributed with regular angular spacing on the end 17 of the section of cylinder 11, opposite the said seat 4. The tops of these contact studs 16a-16c are, in this regard, rounded. The elastic O-ring 10 is housed in an annular recess 18 of shape complementary to the ring 10 and hollowed out in the shaft 6. The bottom of the centring surfaces 15a-15d, facing the base 5, is also at the level of this annular recess 18, here delimited by the overall cylindrical wall of the shaft 6. In the non-assembled state of the rotor 3 and stator 2, the elastic O-ring projects slightly with respect to the centring surfaces 15a-15d, so that, in the assembled state, it is compressed between the rotor 3 at the bottom of the annular recess 18, in direct contact with the overall cylindrical walls of the shaft 6 and housing 13. In this way, its area of contact with the overall cylindrical wall of the shaft 6 is larger than that with the overall cylindrical wall of the housings 13 of the rotor 3. By virtue of these arrangements, the ring 10 is held, more or less firmly, against the overall cylindrical wall of the shaft 6, in the annular recess 18, whilst the overall cylindrical wall of the housing 13 of the rotor 3, and therefore the rotor 3, is able to slide with respect to the ring 10. The rotation movement which the rotor 3 may be given is thus retarded. Depending on the flexibility of the elastic O-ring 10 and the gripping thereof between the rotor 3 and stator 2, the braking torque to be applied can be chosen very precisely. A translational connection of the rotor 3 on the stator 2 is here effected by means of steps 19a-19c disposed on the circumference of the overall cylindrical wall of the housing 13, close to the end 17 of the latter coming to face the base 5. These steps 19a-19c are shaped on the one hand so as each to create a shoulder 20 adapted to come into abutment against the elastic O-ring 10, so that the rotor 3 is immobilised with respect to translation on the stator 2. This is because an axially oriented traction force applied to the rotor 3, in order to attempt to withdraw it from the stator 2, will be arrested by the steps 19a-19c coming into abutment against the elastic O-ring 10, which for its part is retained by its annular recess 18 and possibly the centring surfaces 15a-15d. In this way any translation movement will then be stopped. It will also be noted that any translation movement in a direction opposite to that which has just been mentioned is arrested by the contact studs 16a-16c coming into abutment against the base 5 of the cup-shaped seat 4. Moreover, these steps 19a-19c have an internal face which is curved, in order to facilitate the engagement of the rotor 3 on the stator 2 in the course of assembly. They too are sized so as not to rub on the stator 2. It will also be noted that the shaft 6 has an internal hollow 21 opening out onto the inside of the cup, so as to obtain a stator 2 of substantially constant thickness, in order to minimise any differences in shrinkage which may occur during manufacture, and to save on material. In order to assemble the rotation retarder 1, it suffices to insert the elastic O-ring 10 in its annular recess 18 in the stator 2, and then to engage the rotor 3 on the stator 2 by a simple pushing movement. When the pinion formed by the teeth 12 receives a rotation movement from a component given such a movement, for example a glove-box lid whose opening is controlled by a spring, the rotor 3 is driven with respect to the rotor 2 fixed to another component, for example the glove box itself, a resistive torque which brakes, damps or retards the rotation movement then being communicated to this rotor 3 by means of the elastic O-ring 10. Many variants are possible according to circumstances. Notably several elastic O-rings could be used, housed in several annular recesses, along the shaft 6, or again a plurality of elastic means, such as studs made from elastic material, each held in a retaining cavity formed either in the overall cylindrical wall of the shaft 6 or in that of the housing 13. The retaining cavities can be formed in one of the walls, so that the elastic means occupy at least a plurality of zones angularly distributed around the shaft, in place of the elastic O-ring 10 housed in the annular recess 18. The shape of the seat of the stator 2 can also be modified in order to adapt it to a given support. It should be stated that the invention is not limited to the examples described and depicted.

Claims: Rotation retarder having a stator (2), a rotor (3) designed to receive the rotation movement to be retarded, and an elastic means disposed between the rotor and the stator, the stator (2) having a seat (4) from which projects a shaft (6) with an overall cylindrical wall, the rotor (3) having a housing (13) with an overall cylindrical wall for rotational mounting on the shaft (6), the said retarder (1) being characterised in that the said elastic means (10) is in direct contact with the wall of the shaft (6) and wall of the housing (13) between which it is compressed, the area of contact between a first one of these walls and the elastic means (10) being larger than the area of contact between the second of these walls and the elastic means, thereby the elastic means is held on the first wall whilst the second wall is able to slide with respect to the elastic means. Retarder according to Claim 1, characterised in that the said elastic means (10) is an annular component housed in a recess (18) delimited by the said first wall. Retarder according to Claim 2, characterised in that the said annular component is in contact with a cylindrical surface of the said second wall. Retarder according to either one of Claims 2 and 3, characterised in that it has steps (19a-19c) disposed on the circumference of the wall of the said housing (13), adapted to come into abutment against the said elastic annular component (10) if an axially oriented translational movement tends to move the said rotor (3) away from the said stator (2). Retarder according to Claim 4, characterised in that the said steps have a curved internal face. Retarder according to any one of Claims 2 to 5, characterised in that the said shaft (6) has a body in which the said recess is hollowed out whilst centring surfaces are disposed so as to project with respect to the body. Retarder according to any one of Claims 1 to 6, characterised in that the said rotor (3) is provided with studs (16a-16c) affording contact with the said stator (2), with a rounded top and distributed with regular angular spacing on the end of the rotor facing the said seat (4). Retarder according to any one of Claims 1 to 7, characterised in that the said rotor (3) and the said stator (2) are each made of plastic moulded in a single piece. Use of a rotation retarder according to one of Claims 1 to 8, for retarding the rotation movement of a first component, in engagement with the said rotor (3), with respect to a second component to which the said stator (2) is fixed. Use of a rotation retarder according to Claim 9, characterised in that the said first component is a door mounted so as to rotate on the said second component.

Inventors: LAFON THIERRY, LAFON, THIERRY
Applicants: ITW DE FRANCE, I.T.W. DE FRANCE
Application year: 1996
Main classification: F16F7
IPC codes: F16F7, E05F5, E05F3