ASSISTANCE MODULE FOR A POWER STEERING SYSTEM OF A MOTOR VEHICLE, WITH ELIMINATION OF THE RISK OF EJECTION OF A SEPARATION CAGE FROM A MECHANICAL ROLLING BEARING

Abstract

An assistance module for a power steering system of a motor vehicle, including a reducer casing in which is mounted a reducer including an output shaft provided with a pinion, the output shaft being rotatably mounted inside the reducer casing by means of at least one mechanical rolling bearing carried by a bearing provided on reducer casing between the tangent wheel and pinion, the mechanical rolling bearing having several rolling elements kept at a distance from each other by a separation cage, rolling elements and separation cage being disposed in an annular rolling bearing space formed between a coaxial internal and external ring, the assistance module includes at least one blocking element having at least one stop surface facing the annular rolling bearing space at a distance such that at least one of the stop surfaces prevents an ejection of the separation cage out of the annular rolling bearing space.

Claims

1. An assistance module for a power steering system 1 of a motor vehicle, including a reducer casing in which is mounted a reducer comprising an output shaft provided with a pinion, said output shaft being rotatably mounted inside the reducer casing about a longitudinal axis by means of at least one mechanical rolling bearing carried by a bearing provided on the reducer casing between the tangent wheel and the pinion, said mechanical rolling bearing having several rolling elements kept at a distance from each other by a separation cage, said rolling elements and said separation cage being disposed in an annular rolling bearing space formed between a coaxial internal ring and external ring, said separation cage being capable of being ejected out of said annular rolling bearing space in an ejection direction, said assistance module being wherein it comprises at least one blocking element having at least one stop surface facing the annular rolling bearing space and in the ejection direction, at a distance such that at least one of the stop surfaces prevents an ejection of said separation cage out of the annular rolling bearing space.

2. The assistance module according to claim 1, wherein the rolling elements are balls of spherical shape and wherein the distance is less than or equal to half of a diameter of said balls.

3. The assistance module according to claim 2, wherein the distance is less than or equal to 2 millimeters.

4. The assistance module according to claim 3, wherein at least one stop surface is positioned, along the longitudinal axis, between the mechanical rolling bearing and the tangent wheel.

5. The assistance module according to claim 1, in which at least one stop surface is positioned, along the longitudinal axis, between the mechanical rolling bearing and the pinion.

6. The assistance module according to claim 1, wherein at least one blocking element is secured to the reducer casing.

7. The assistance module according to claim, wherein the blocking element is made in one piece with the reducer casing.

8. The assistance module according to claim 7, wherein the blocking element is produced by a foundry method with the reducer casing.

9. The assistance module according to claim 4, wherein the blocking element is fixed to the reducer casing by screwing, welding or force fitting.

10. The assistance module according to claim 1, wherein at least one blocking element is inserted between a shoulder of the reducer casing and the external ring of the mechanical rolling bearing.

11. The assistance module according to claim 1, wherein at least one blocking element is secured to the output shaft.

12. The assistance module according to claim 11, wherein the blocking element is made in one piece with the output shaft.

13. The assistance module according to claim 11, wherein the blocking element is fixed to the output shaft by screwing, welding or force fitting.

14. The assistance module according to claim 1, wherein at least one blocking element is inserted between a shoulder of the output shaft and the internal ring.

15. The assistance module according to claim 1, wherein a blocking element is secured to a clamping nut nut, said clamping nut being screwed inside the bearing between the mechanical rolling bearing and the pinion, and abuts against the external ring.

16. The assistance module according to claim 15, wherein the blocking element is made in one piece with the clamping nut.

17. The assistance module according to claim 15, wherein the blocking element is fixed to the clamping nut by screwing, welding or force fitting.

18. The assistance module according to claim 1, wherein at least one blocking element is inserted between the clamping nut and the external ring.

19. The assistance module according to claim 1, wherein a blocking element is secured to a crimping ring, said crimping ring being crimped inside the bearing between the mechanical rolling bearing and the pinion, and abuts against the internal ring.

20. The assistance module according to claim 19, wherein the blocking element is made in one piece with the crimping ring.

21. The assistance module according to claim 1, wherein at least one blocking element is inserted between the crimping ring and the internal ring.

22. The assistance module according to claim 1, wherein at least one blocking element has a stop surface of an annular shape, centered on the longitudinal axis.

23. The assistance module according to claim 1, wherein at least one blocking element has several distinct stop surfaces, said stop surfaces being disposed about the longitudinal axis.

Description

[0069] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of an example of non-limiting implementation, made with reference to the appended figures in which:

[0070] FIG. 1 is a cross-sectional view of a power steering system of the state of the art;

[0071] FIG. 2 is an exploded view of a mechanical rolling bearing comprising a separation cage;

[0072] FIG. 3 is a cross-sectional view of a first embodiment of an assistance module according to the invention;

[0073] FIG. 4 is a cross-sectional view of a second embodiment of an assistance module according to the invention;

[0074] FIG. 5 is a cross-sectional view of a third embodiment of an assistance module according to the invention;

[0075] FIG. 6 is a cross-sectional view of a fourth embodiment of an assistance module according to the invention;

[0076] FIG. 7 is a cross-sectional view of a fifth embodiment of an assistance module according to the invention;

[0077] FIG. 8 is a cross-sectional view of a sixth embodiment of an assistance module according to the invention;

[0078] FIG. 9 is a cross-sectional view of a seventh embodiment of an assistance module according to the invention;

[0079] FIG. 10 is a cross-sectional view of an eighth embodiment of an assistance module according to the invention;

[0080] FIG. 11 is a cross-sectional view of a ninth embodiment of an assistance module according to the invention;

[0081] FIG. 12 is a cross-sectional view of a tenth embodiment of an assistance module according to the invention;

[0082] FIG. 13 is a cross-sectional view of an eleventh embodiment of an assistance module according to the invention;

[0083] FIG. 14 is a perspective view (FIG. 14a) and a front view (FIG. 14b) of the first embodiment of an assistance module according to the invention;

[0084] FIG. 15 is a perspective view (FIG. 15a) and a front view (FIG. 15b) of the first embodiment of an assistance module according to the invention.

[0085] FIG. 1 represents a power steering system 1 for a motor vehicle of the state of the art.

[0086] This power steering system 1 includes in particular an output shaft 2 mounted movable in rotation about a longitudinal axis 22 in a reducer casing 3.

[0087] This output shaft 2 is secured to a tangent wheel 23 meshing with a worm screw 4, this worm screw 4 being itself driven in rotation by an assistance motor (not represented).

[0088] The output shaft 2 also has a pinion 24 meshing with a rack 5 disposed in a steering casing 51: the rotational movement of the output shaft 2 about the longitudinal axis 22 thus causes a translational movement of the rack 5 in a direction orthogonal to the longitudinal axis 22.

[0089] This power steering system 1 thus makes it possible to transmit to the rack 5 a motor torque transmitted to the worm screw 4 by an assistance motor (not represented), in order to facilitate the steering of the electric vehicle by its driver.

[0090] Particularly, the output shaft 2 is mounted on the reducer casing 3 via a mechanical rolling bearing 6, disposed in a bearing 31 of the reducer casing 3.

[0091] This mechanical rolling bearing 6 is, in this embodiment, formed of an internal ring 61 and an external ring 62 coaxial and centered on the longitudinal axis 22.

[0092] The space between this internal ring 61 and this external ring 62 constitutes an annular movement space 63 in which are disposed rolling balls 64.

[0093] These rolling balls 64 are kept at a distance from each other by a separation cage 65, also disposed in the annular rolling bearing space 63 of the mechanical rolling bearing 6.

[0094] The mechanical rolling bearing 6 thus enables the rotational movement of the output shaft 2 about the longitudinal axis 22 relative to the reducer casing 3.

[0095] In this power steering system 1 of the state of the art, it is possible that, following a significant mechanical stress exerted on the mechanical rolling bearing 6 (for example, following a misalignment of the output shaft 2 relative to the longitudinal axis 22), the separation cage 65 undergoes a significant deformation and is ejected out of the annular rolling bearing space 63 in an ejection direction collinear with the longitudinal axis 22.

[0096] FIG. 2 represents, in an exploded view, a mechanical rolling bearing 6 including rolling balls 64 disposed between an internal ring 61 and an external ring 62.

[0097] This mechanical rolling bearing 6 also includes a protection 68.

[0098] The balls 64 are kept at a distance from each other by a separation cage 65.

[0099] The separation cage 65 has a front face 651 and an opposite rear face 652 and includes housings 653 formed in the front face 651, each of these housings 651 having a shape adapted to receive a ball 64: the separation cage is thus clipped (that is to say, secured by pressure) by its front face with the balls 64.

[0100] Due to its particular structure, the housings 653 having an aperture opening only on the front face 651, the separation cage 65 can only be detached from the balls 64 by a movement in an ejection direction 654.

[0101] The orientation of this ejection direction 654 thus depends on the direction of mounting of the separation cage 65 in the mechanical rolling bearing 6.

[0102] Once the mechanical rolling bearing 6 is positioned in the bearing 31 of the steering casing 51, this ejection direction 654 is collinear with the longitudinal axis 22 and defines the ejection trajectory of the separation cage 65 outside the annular rolling bearing space 63: depending on the mounting direction of the separation cage in the mechanical rolling bearing 6, it will be capable of being ejected either in the direction of the tangent wheel 23, or in the direction of the pinion 24.

[0103] Thus, knowing the orientation of this ejection direction 654, it is necessary to dispose a blocking element only on one side of the mechanical rolling bearing 6 along the longitudinal axis 22, that is to say either between the mechanical rolling bearing 6 and the pinion 24, or between the mechanical rolling bearing 6 and the tangent wheel 23.

[0104] Embodiments including several blocking elements disposed both between the mechanical rolling bearing 6 and the pinion 24 and between the mechanical rolling bearing 6 and the tangent wheel 23 are also conceivable.

[0105] FIG. 3a represents a power steering system 1 according to the invention, FIG. 3b being a detailed view of the bearing 31.

[0106] In the embodiment represented in this FIG. 3, the separation cage 65 is capable of being ejected in an ejection direction 654 in the direction of the tangent wheel 23.

[0107] The reducer casing 3 includes a blocking element 32 disposed between the tangent wheel 23 and the bearing 31, this blocking element 32 having a stop surface 33 extending facing the annular rolling bearing space 63 of the mechanical rolling bearing 6.

[0108] Particularly, this stop surface 33 is positioned perpendicular to an ejection axis 66 materializing the trajectory of the separation cage 65 in the ejection direction 654.

[0109] The stop surface 33 intersects this ejection axis 66 near the ball rolling bearing 6: in this way, the stop surface 33 physically prevents a movement of the separation cage 65 along the ejection axis 66 and in the direction of the tangent wheel 23.

[0110] Thus, this blocking element 32 makes it possible to prevent (at least partially) the ejection of the separation cage 65 out of the annular rolling bearing space 63 in the direction of the tangent wheel 23.

[0111] In this embodiment, the blocking element is made in one piece with the reducer casing 3, and was produced by a foundry method with this reducer casing 3.

[0112] Obviously, many other embodiments of the invention can be envisaged, particularly concerning the shape of the blocking element 32 and its stop surface 33, and the placement of these relative to the mechanical rolling bearing 6 and to the annular rolling bearing space 63.

[0113] FIG. 4 represents an alternative embodiment of the invention, in which a blocking element 7, external to the reducer casing 3, is fixed on the latter by screwing or welding, or even by force fitting.

[0114] This blocking element 7 has a stop surface 71, disposed perpendicular to the ejection axis 66 and facing the annular rolling bearing space 63 of the mechanical rolling bearing 6.

[0115] In this way, this blocking element 7 makes it possible to prevent an ejection of the separation cage 65 from the annular rolling bearing space 63, along the ejection axis 66 and in the direction of the tangent wheel 23.

[0116] FIG. 5 represents a third embodiment of the invention, in which the blocking element is formed by a washer 8 inserted between the external ring 62 of the mechanical rolling bearing 6 and a shoulder 34 of the reducer casing 3.

[0117] This washer 8 is thus positioned in abutment against the external ring 62, between the mechanical rolling bearing 6 and the tangent wheel 23, and has a stop surface 81 extending facing the annular rolling bearing space 63, perpendicular to the ejection axis 66.

[0118] As previously, the presence of this washer 8 thus makes it possible to physically prevent the ejection of the separation cage 65 out of the annular rolling bearing space 63, in the direction of the tangent wheel 23.

[0119] For example, it is conceivable that the washer 8 is made of a material of the metallic or plastic type.

[0120] It will be noted that it is possible to combine the various embodiments previously described, for example by associating the use of a washer 8 (external to the reducer casing 3) as represented in FIG. 5 with a blocking element 32 (secured to the reducer casing 3) as represented in FIG. 3, this blocking element 32 is made in one piece with the shoulder 34.

[0121] The following FIGS. 6 to 8 respectively represent a fourth, a fifth and a sixth embodiment of the invention, in which a blocking element is secured to the output shaft 2 and adapted to prevent, as previously, an ejection of the separation cage 65 in the direction of the tangent wheel 23.

[0122] Particularly, in the fourth embodiment of the invention described in FIG. 6, the power steering system 1 has a blocking element 9 made in one piece with the output shaft 2.

[0123] This blocking element 9 has a stop surface 91 extending facing the annular rolling bearing space 63 and perpendicularly intersecting the ejection axis 66: the blocking element 9 thus makes it possible in this way to prevent an ejection movement of the separation cage 65 out of the annular rolling space 63, along the ejection axis 66 and in the direction of the tangent wheel 23.

[0124] It should be noted that, this blocking element 9 being secured to the output shaft 2, it is also driven in the rotational movement of the latter about the longitudinal axis 22.

[0125] Similarly, in the fifth embodiment described in FIG. 7, the blocking element 9 made in one piece with the output shaft 2 is replaced by a blocking element 18, external to the output shaft 2 and secured to the latter by screwing, welding or force fitting.

[0126] This blocking element 18 has a stop surface 181 intersecting the ejection axis 66 and thus making it possible to prevent an ejection of the separation cage 65 from the annular rolling bearing space 63, in the direction of the tangent wheel 23.

[0127] FIG. 8 represents a sixth embodiment of the invention, in which the blocking element takes the form of a washer 11, positioned between a shoulder 25 of the output shaft 2 and the internal ring 61 of the mechanical rolling bearing 6, and has a stop surface 111 extending opposite the annular rolling bearing space 63, perpendicular to the ejection axis 66.

[0128] This washer 11 therefore makes it possible in this way to prevent an ejection movement of the separation cage 65 out of the annular rolling bearing space 63, along the ejection axis 66 and in the direction of the tangent wheel 23.

[0129] The following FIGS. 9 to 13 illustrate embodiments of the invention, in which a suitable blocking element makes it possible to prevent an ejection of the separation cage 65 from the annular rolling bearing space 63 in the direction of the pinion 24, that is to say in an ejection direction opposite to that of the embodiments previously described by FIGS. 1 to 7.

[0130] Particularly, the following FIGS. 9, 10 and 11 respectively represent a seventh, an eighth and a ninth embodiment of the invention, in which a blocking element is secured to a clamping nut 10, while the following FIGS. 12 and 13 respectively represent a tenth and an eleventh embodiment of the invention, in which a blocking element is secured to a crimping ring 13.

[0131] With reference to FIG. 9, the steering system 1 includes a blocking element 12 made in one piece with a clamping nut 10, screwed inside the bearing 31 of the reducer casing 3 between the mechanical rolling bearing 6 and the pinion 24, in abutment against this same mechanical rolling bearing 6.

[0132] The function of this clamping nut 10 is to keep the mechanical rolling bearing 6 in position in the bearing 31 of the reducer casing 3.

[0133] In the embodiment represented by FIG. 9, the blocking element 12 made in one piece with the clamping nut 10 has a stop surface 121 extending facing the annular rolling bearing space 63 perpendicular to the ejection axis 66.

[0134] Thus, the stop surface 121 makes it possible to physically block an ejection movement of the separation cage 65 out of the annular rolling bearing space 63, in the direction of the pinion 24.

[0135] Similarly, in the embodiment described in FIG. 10, the blocking element 12 made in one piece with the clamping nut 10 is replaced by a blocking element 14, external to the clamping nut 10 and secured to the latter by screwing, welding or force fitting.

[0136] This blocking element 14 has a stop surface 141 intersecting the ejection axis 66 and thus making it possible to prevent an ejection of the separation cage 65 out of the annular rolling bearing space 63, in the direction of the pinion 24.

[0137] In the embodiment represented by FIG. 11, the blocking element takes the form of a washer 15, positioned between the clamping nut 10 and the external ring 62 of the mechanical rolling bearing 6, and has a stop surface 151 extending facing the annular rolling bearing space 63, perpendicular to the ejection axis 66.

[0138] This washer 15 therefore makes it possible in this way to prevent an ejection movement of the separation cage 65 out of the annular rolling bearing space 63, along the ejection axis 66 and in the direction of the pinion 24.

[0139] It will also be noted, in these FIGS. 9 to 11, the presence of the blocking element 32 secured to the reducer casing 3, whose stop surface 33 prevents (as previously described) an ejection movement of the separation cage 65 in the opposite direction, namely in the direction of the tangent wheel 23.

[0140] FIG. 12 represents a tenth embodiment of the invention, in which a blocking element 16 is made in one piece with a crimping ring 13.

[0141] This crimping ring 13 has the function, similar to the clamping nut 10, of holding the mechanical rolling bearing 6 in position in the bearing 31 of the reducer casing 3, and is usually positioned between the mechanical rolling bearing 6 and the pinion 24, in abutment against the internal ring 61.

[0142] This blocking element 16 has a stop surface 161 intersecting the ejection axis 66 and thus making it possible to prevent an ejection of the separation cage 65 out of the annular rolling bearing space 63, in the direction of the pinion 24.

[0143] Alternatively, in the embodiment represented by FIG. 13, the blocking element takes the form of a washer 17 positioned between the crimping ring 13 and the internal ring 61 of the mechanical rolling bearing 6, and has a stop surface 171 extending opposite the annular rolling bearing space 63, perpendicular to the ejection axis 66.

[0144] This washer 17 thus makes it possible in this way to prevent an ejection movement of the separation cage 65 from the annular rolling bearing space 63, along the ejection axis 66 and in the direction of the pinion 24.

[0145] It should be noted that, for each of the embodiments previously described and represented by the preceding FIGS. 2 to 13 in transverse view, it is conceivable that the stop surface of each considered blocking element has an annular shape, centered on the longitudinal axis 22.

[0146] For example, FIGS. 14a and 14b are respectively representations of the embodiment described by the preceding FIG. 3 in perspective and in front view (along the longitudinal axis 22).

[0147] In these figures, the stop surface 33 of the blocking element 32 made in one piece with the reducer casing 3 has an annular shape surrounding the output shaft 22 and centered on the longitudinal axis 22: this stop surface 32 thus extends over the entire periphery of the external ring 62 and thus prevents any movement of ejection of the separation cage 65 out of the annular rolling bearing space 63 of the mechanical rolling bearing 6 along any ejection axis facing the annular rolling bearing space 63 and parallel to the longitudinal axis 22, in the direction of the tangent wheel 23.

[0148] Conversely, it is also conceivable that the considered blocking element in each of the embodiments of the preceding FIGS. 2 to 13 has several distinct stop surfaces, these distinct stop surfaces being disposed about the longitudinal axis 22.

[0149] For example, FIGS. 15a and 15b are respectively representations of the embodiment described by the previous FIG. 3 in perspective and in front view (along the longitudinal axis 22).

[0150] In this FIG. 15, the blocking element 32 (secured to the reducer casing 3) has four stop surfaces 33 disposed about the output shaft 2 and equidistant from the longitudinal axis 22.

[0151] In this configuration, the stop surfaces 33 of the blocking element 32 prevent an ejection movement of the separation cage 65 from the annular rolling bearing space 63 along several ejection axes 66 facing which are disposed stop surfaces 33.

[0152] However, the ejection movements of the separation cage 65 along the ejection axes 67 positioned between these stop surfaces 33 (and therefore facing none of them) are left free.

[0153] Due to the rigidity and the size of the separation cage 65, it is however very improbable that it can be entirely ejected out of the annular rolling bearing space 63 of the mechanical rolling bearing 6 in an interval separating two stop surfaces 33: if a portion of the separation cage 65 should be ejected along an ejection axis 67 (facing no stop surface 33) other adjacent portions of this same separation cage 65 would be ejected according to ejection axes 66 (facing at least one stop surface 33) would then come into contact with one or more stop surfaces 33.

[0154] Thus, the total ejection of the ejection cage 65 from the annular rolling bearing space 63 is prevented by the stop surfaces 33, even when the latter do not extend over the entire periphery of the mechanical rolling bearing 6.

[0155] The latter solution has the advantage of ensuring good guiding of the output shaft in the reducer casing 3 thanks to the presence of a blocking element having weaker area and therefore less costly stop surfaces.