COVER FOR GEARBOX MOTOR GROUPS FOR AN ELECTRIC ACTUATOR OF A DISC BRAKE AND GEARBOX MOTOR GROUPS INCLUDING SUCH A COVER

Description

[0001] The invention relates to an electric geared motor group mounted at the end of a disc brake actuator, which comprises a motor mounted in a cantilever, parallel to the output of the reducer and on the same side. State of the art

[0002] In the field of brakes, for automobiles in general, and more specifically disc brakes, it has become common to install an electric actuator directly on the brake. This actuator is generally used for the parking and emergency brake function, but sometimes also as a service brake.

[0003] This actuator is generally motorized by an electric motor-gear unit (or MGU or "Motor Gear Unit"), which comprises a drive device (or motor) and a transmission device (or reduction mechanism), the two devices being connected to each other (the motor actuating the transmission device) and being enclosed in a protective casing comprising on the one hand an open housing and on the other hand a closing cover.

[0004] The open housing has a section whose shape substantially matches the external shape of the assembly formed by the two devices connected together. The cover also has the shape of the section of the housing and is fixed to the housing by welding.

[0005] The transmission device comprises several stages of gears linked to each other, and in particular a planetary gear (which may comprise two stages) comprising at least one toothed crown with internal teeth.

[0006] Document FR 3 074 757 discloses a brake motor-reducer unit which comprises at least two epicyclic gear trains, forming reduction stages mounted in series, enclosed in a protective housing or casing.

[0007] With the evolution of geared motor groups, the manufacture of parts containing these crowns had to change: they must now be made of metal and be fitted into the housing, instead of being molded into the housing as was done previously.

[0008] Typically, the case has protruding ribs and the crown is force-fitted into the case to be held there: by being compressed against the crown, it is the ribs which hold the crown(s) in position in the case.

[0009] However, when forcing the fitting of the parts into the housings, it was found that chips could detach from the parts, which could be a hindrance to the rotational drive of the gears.

[0010] It was also found that this solution, combining ribs and tight fitting, could be the cause of noise generation at the housing level. Statement of the invention

[0011] The invention therefore aims to propose an alternative solution to ensure that the crown is held in the housing, without generating chips in the housing which could damage the gears or compromise their operation.

[0012] To this end, the invention relates to a cover for a geared motor group for an electric brake actuator, in particular a disc brake, said geared motor group comprising a housing containing an electric motor and a reduction mechanism mechanically connected to said electric motor to provide, at the output of said reduction mechanism, a rotational drive of a shaft about an output axis, said reduction mechanism comprising an epicyclic gear system comprising planetary pinions meshing with the inner surface of a fixed rotating crown gear, which is fitted in a housing housing and has a crown axis defining an axial direction, said housing having an access opening to said housing, allowing said gear system or at least said crown gear to be axially introduced therein, said crown gear having a free edge directed towards said access opening.

[0013] According to the invention, the cover is designed to close the access opening, and is remarkable in that it comprises an axial projection, in particular an internal skirt, capable of being positioned at least partially in abutment on the free edge of said crown when the cover closes said opening, said projection having, on a free end opposite the free edge of the crown, at least one elastically deformable element capable of coming to bear at least partially against the free edge of the crown, so as to hold said crown in the housing in said axial direction.

[0014] Thus produced, the crown is held axially by the cover. It is then possible to assemble the crown in the housing in a free or sliding fit. This avoids the constraints and disadvantages of force fitting, in particular the need to use a press and the risk of chip formation.

[0015] According to an advantageous embodiment which will be presented subsequently, the axial projection comprises an internal skirt which is elastically deformable and / or which comprises at least three deformable, axially projecting studs which are distributed around the output axis, in particular with a gap between them of at least 60° or even at least 80°.

[0016] Furthermore, said at least three protruding studs are equidistant or substantially equidistant from each other.

[0017] Furthermore, said elastically deformable element is overmolded onto the free end of said axial projection.

[0018] According to an advantageous embodiment envisaged by the invention, said axial projection is made at least partially in a single piece with the cover.

[0019] According to an alternative embodiment, said axial projection is attached to said cover by assembly.

[0020] Furthermore, said axial projection forms an internal skirt which is made of elastomer and at least partially constitutes said elastically deformable element.

[0021] The invention also relates to a geared motor group for an electric disc brake actuator, said geared motor group comprising a housing containing an electric motor and a reduction mechanism mechanically connected to said electric motor to provide, at the output of said reduction mechanism, a rotational drive of a shaft about an output axis, said reduction mechanism comprising a gear system with toothed wheels and a crown at least partially receiving said gear system and having a crown axis defining an axial direction, said protective crown having a free crown edge, said housing having an access opening to said gear system and to said crown. According to the invention, the geared motor group is remarkable in that it comprises a cover as defined above, said cover closing said access opening.

[0022] According to one embodiment of the invention, the internal skirt of the cover (of the geared motor group) has a section whose shape is substantially the same as the shape of the section of the crown, so that the free edge of the crown is positioned opposite the free end of the internal skirt of the cover when the cover is positioned on the housing, to exert pressure on the entire free edge of the crown.

[0023] Advantageously, said crown, the housing receiving said crown and said internal skirt of the cover are each at least partially cylindrical.

[0024] Advantageously, the housing and the toothed crown interact with each other by shape cooperation, in particular by complementary reliefs formed around the crown to prevent said crown from rotating in said housing.

[0025] In the context of this embodiment, said crown comprises an external surface which has at least one first projecting element, said housing comprising an internal surface having at least one second projecting element, said at least one first projecting element of said crown being capable of engaging with said at least one second projecting element of said housing.

[0026] The invention also relates to a vehicle brake, in particular a disc brake, comprising an electric motor-reducer group as defined above or a motor-reducer group comprising a cover as defined above, which drives an electric braking actuator, in particular a parking brake.

[0027] Finally, the invention relates to a method of assembling a cover as defined above on an access opening of the housing of a geared motor group as defined above.

[0028] According to the invention, the method is remarkable in that it comprises the following steps: positioning the crown in the housing by free or sliding fitting (for example so that said at least one first projecting element engages with said at least one second projecting element of said housing), positioning the cover on the housing, by applying said elastically deformable element against the free edge of said crown, applying pressure to the cover so that said axial projection exerts pressure on the crown in the axial direction of the crown, and thus compressing the elastically deformable element(s), fixing the cover to the housing, in particular by welding or gluing.

[0029] It should be noted that, even if the method provides for a free fitting, vibrations are avoided thanks to the damping effect of the elastically deformable element(s) capable of coming to bear at least partially against the free edge of the crown, so as to maintain said crown in the housing in said axial direction. Presentation of figures

[0030] Other advantages and characteristics of the invention will appear on examining the detailed description of a non-limiting embodiment, and the appended drawings, in which: [ Fig. 1 ] is a perspective view of a geared motor group according to the invention, [ Fig.2 ] is a perspective view of a cover for a geared motor group according to the invention, [ Fig.3 ] is a perspective view of a cover and a toothed crown that comprise the geared motor group illustrated in [ Fig. 1 ], And [ Fig.4] is a perspective and partially exploded view of part of the geared motor unit shown in [ Fig. 1 ], showing a cover according to the invention, positioned above satellite pinions meshing with the inner surface of the toothed crown shown in [ Fig.3 ], the toothed crown being positioned below the pinions in order to uncover them. Description of an embodiment

[0031] The terms "upper", "lower", "left", "right", "top", "bottom" etc. are used in the following description only to help the reader find his way around the figures: it should be understood that these terms are not limitations of the invention.

[0032] A cover 1 forming the subject of the invention is shown alone in [ Fig.2 ]. On the figures 1 , 3 And 4, respectively, it is mounted in a geared motor group 2, or it is shown associated with a toothed crown 3 as positioned in the geared motor group ([ Fig.3 ]) or in a position away from the toothed crown 3 ([ Fig.4 ]).

[0033] The cover 1 shown in the figures is designed to hold the crown 3 in position in the geared motor group: it is therefore appropriate to present, firstly, which elements are included in the geared motor group 2 and their arrangement, so as to identify the zone of the geared motor group 2 where the cover 1 according to the invention is implemented.

[0034] There [ Fig. 1 ] shows the geared motor group 2 as a whole, with the cover 1 visible on the upper part of the geared motor group 2.

[0035] The geared motor group 2 is designed for a disc brake actuator, of the type comprising a movable caliper mounted to slide on a yoke, the actuator driving the caliper in movement under the action of the geared motor group or a hydraulic piston.

[0036] There [ Fig. 1 ] shows an example of such a geared motor group and it can be seen that it comprises a housing 4, forming a protective casing for the geared motor group 2, the housing 4 having two parts: an upper part 40, having a substantially bean-shaped section, accommodating two cylindrical shapes: a first cylindrical shape 41 located on the left in the upper part 40 on the [ Fig. 1 ] and a second cylindrical shape 42 located on the right in the upper part 40 on the [ Fig. 1], a lower part 43, formed by the second cylindrical shape which projects downwards and which extends over a height substantially identical to the height of the upper part 40.

[0037] The lower part 43 actually extends the second cylindrical shape 42 downwards which accommodates an electric motor (not shown) of the geared motor group 2.

[0038] The geared motor group 2 also includes a reduction mechanism 5 (see [ Fig.3 ]) whose outlet 50 is visible and corresponds to the first cylindrical shape 41 in the lower part of the upper part 40 of the housing.

[0039] The reduction mechanism 5 is mechanically connected to the electric motor, by means of a pinion 51 shown in particular in figures 3 And 4 , the gear pinions being located in the upper part of the part 40 of the cylindrical shape 42 of the housing 4.

[0040] The reduction mechanism 5 comprises an epicyclic gear system comprising satellite pinions visible especially in [ Fig.4 ], meshing the inside of the toothed crown 3 (see [ Fig.3 ]) (the teeth of some pinions are engaged between the teeth of the inner surface of the toothed crown 3).

[0041] It should be noted that the toothed crown 3 is mounted fixed in rotation in the housing 4.

[0042] The crown 3 is fitted into a housing of the case 4, located in the cylindrical shape 41 of the upper part 40 of the case 4.

[0043] We note on the [ Fig.3 ] that the output 50 of the reduction mechanism has a shaft 52 which extends along an output axis A1.

[0044] The output axis A1 corresponds to the axis of the crown 3 and it defines an axial direction.

[0045] Shaft 52 controls the actuator that causes the movement of the disc brake piston caliper (actuator and disc brake not shown), typically of the screw-nut type.

[0046] The upper part 40 of the housing 4 has an access opening which is closed by the cover 1 according to the invention.

[0047] The access opening allows at least the gear system 5 and the toothed crown 3 to be introduced axially into the housing 4.

[0048] The lower part 43 of the housing 4, which at least partially accommodates the electric motor 4, is also closed.

[0049] THE figures 3 And 4 show that the crown 3 has a free edge 30 which is directed towards the access opening of the housing 4 (and therefore towards the cover 1 according to the invention closing the access opening).

[0050] The crown 3 is of generally cylindrical shape, having a toothed internal surface 31 and an external surface 32 which has three elements 33 projecting radially outwards and each extending in a direction parallel to the axial direction A1. The projecting elements 33 are equidistant from each other.

[0051] The interior of the case 4 which accommodates the crown 3 is cylindrical and has an internal case surface which also has inwardly projecting elements, these internal projecting elements engaging with the projecting elements 33 of the crown when it is accommodated in the case 4: in this way, the crown 3 is blocked in rotation in its housing in the case 4 when it is there.

[0052] Thus, the housing of the casing 4 and the toothed crown 3 interact with each other by cooperation of shape, in particular by complementary reliefs between them formed in particular around the crown 3 (projecting elements from the interior of the casing and those of the external surface of the crown 3).

[0053] Reference will now be made more particularly to the cover 1 according to the invention.

[0054] The cover 1 comprises a bottom wall 10 and a peripheral skirt 11, bordering the bottom wall 10, coming in line with the external wall of the housing 4 when the cover 1 is placed and fixed by welding on the housing 4.

[0055] The bottom wall 10 comprises projecting elements forming a honeycomb structure 12 (see [ Fig.2 ]), which has the function of limiting the vibrations of the cover 1 (the bottom wall 10 behaving like a vibrating skin).

[0056] The cover 1 has a shape similar to the shape of the cross-section of the housing 4.

[0057] In accordance with the invention, the cover 1 also comprises an axial projection (i.e. the axis of which merges with the axis A1 when the cover is positioned on the access opening of the housing 4).

[0058] The axial projection is, in the context of the example illustrated in the figures, an internal skirt 13, which is positioned at least partially in support on the free edge 30 of the crown 3 when the cover 1 closes the access opening of the housing 4 (see [ Fig.3 ]).

[0059] The internal skirt 13 (or axial projection) has a free end 14 opposite the free edge 30 of the crown 3. On this free end 14, the crown comprises at least one elastically deformable element 15 which is produced, in the context of the example illustrated, by eight elastically deformable pads 15.

[0060] The eight studs 15 project axially from the free end 14 of the internal skirt 13 and they come to bear against the free edge 30 of the crown 3 (see [ Fig.3 ]) to hold the crown 3 in the housing 4 in the axial direction A1.

[0061] The crown 3 is thus held axially by the cover 1 and it is possible to assemble the crown 3 in the housing in a free or sliding fit: this avoids the constraints and disadvantages of the force fit provided in the State of the Art mentioned previously, in particular the need to use a press and the risk of formation of chips which could hinder the proper functioning of the geared motor unit.

[0062] The internal skirt 13 is at least partially cylindrical and the eight pads 15 are advantageously distributed equidistantly and / or equiangularly around the output axis A1.

[0063] It should be understood that the invention is not limited to the presence of eight studs and that more or fewer could be provided.

[0064] In another embodiment, at least three pads could be provided distributed around the axis A1, in particular with a gap between them of at least 60°, or even at least 80°.

[0065] The shape of the internal skirt 13 is at least partially cylindrical and has a section whose shape is substantially the same as the shape of the section of the crown 3, so that the free edge 30 of the crown 3 is positioned opposite the free end 14 (the edge) of the internal skirt 13 of the cover 1, when the cover 1 is positioned on the housing 4, so as to exert pressure on the entire free edge 30 of the crown 3.

[0066] Alternatively, the skirt 13 is elastically deformable with the studs 15: it is, for example, made of elastomer and would at least partially constitute the elastically deformable element(s) in accordance with the invention.

[0067] Alternatively, without departing from the scope of the invention, the studs are overmolded onto the free end 14 of the internal skirt 13.

[0068] Alternatively, the elastically deformable element is overmolded onto the free end of the axial projections, i.e. the free end of the studs 15, without departing from the scope of the invention.

[0069] The axial projections, or studs 15, are: either made in one piece with the skirt 13, or made on the free end 14 of the cover by being attached to this free end.

[0070] THE figures 2 And 3also show that the cover further comprises a second internal skirt 16, formed by the partial outline of two interlaced rings. The second internal skirt 16 is positioned for example around pinions located in the upper part of the housing, and in particular pinion 51 in the example illustrated in the figures.

[0071] Reference will now be made to a method of assembling the cover 1 onto the housing 4 of the geared motor group 2.

[0072] Firstly, the crown 3 is positioned in the housing 4 by free or sliding fitting.

[0073] Then, the cover 1 is positioned on the housing 4, by applying the elastically deformable studs 15 against the free edge 30 of said crown 3.

[0074] Pressure is then applied to the cover 1 so that said axial projection (free end of the internal skirt) 14 exerts pressure on the crown 3 in the axial direction A1 of the crown and thus compresses the elastically deformable stud(s) 15.

[0075] Finally, the cover 1 is fixed to the housing 4, in particular by welding or by gluing.

[0076] It is understood from the preceding description how the invention makes it possible to hold the crown 3 in place in the housing 4 of a geared motor group 2 without force fitting.

[0077] It should be understood that the invention is not limited to the embodiment specifically shown in the figures and described above. The invention extends to the implementation of equivalent means and to the production of a brake (not illustrated), such as a vehicle disc brake comprising an electric motor-reducer unit as described above (for example) which would comprise a cover such as that shown and described above, or comprising equivalent characteristics. In such a case, the vehicle brake according to the invention is designed to drive an electric braking actuator, in particular a parking brake. List of cited documents

[0078] 1 - cover 2 - geared motor unit 3 - toothed crown 4 - housing 5 - reduction mechanism 10 - bottom wall 11 - peripheral skirt bordering the bottom wall 12 - honeycomb structure 13 - internal skirt 14 - free end of the internal skirt 15 - elastically deformable element 16 - second internal skirt 30 - free edge of the crown 31 - toothed internal surface 32 - external surface 33 - projecting elements 40 - upper part of the housing 41 - first cylindrical shape 42 - second cylindrical shape 43 - lower part 50 - output of the reduction mechanism 51 - output pinion of the motor shaft 52 - output shaft of the reduction mechanism A1 - output axis / axial direction

Claims

1. Cover (1) for a motor gear unit (2) for an electric actuator for a brake, in particular a disc brake, said motor gear unit (2) comprising a housing (4) enclosing an electric motor and a reduction gear mechanism (5) mechanically connected to said electric motor to provide at the output (50) of said reduction gear mechanism (5) a rotational drive of a shaft (52) along an output axis, said reduction gear mechanism (5) comprising an epicyclic gear system comprising planet gears meshing with the inner surface (31) of a toothed ring gear (3) fixed in rotation, which is mounted in a recess of the housing (4) and has a ring gear axis defining an axial direction (A1), said housing (4) having an opening for access to said recess, making it possible to axially insert said gear system therein or at least said toothed ring gear (3), said toothed ring gear (3) having a free edge (30) directed towards said access opening, said cover (1) being designed to close the access opening, and being characterized in that it comprises an axial projection (13), in particular an inner skirt, capable of being positioned at least partially bearing against the free edge (30) of said ring gear (3) when the cover (1) closes said opening, said projection (13) having on a free end (14) opposite the free edge (30) of the ring gear (3) at least one elastically deformable element (15) capable of at least partially bearing against said free edge (30) of the ring gear (3), so as to hold said ring gear (3) in the housing (4) in said axial direction (A1).

2. Cover according to claim 1, characterized in that said axial projection (13) comprises an inner skirt (13) that is elastically deformable and / or that comprises at least three axially projecting elastically deformable studs (15) that are distributed about the output axis, in particular with a gap between them of at least 60° or at least 80°.

3. Cover according to claim 2, characterized in that said at least three projecting studs (15) are equidistant or substantially equidistant from each other.

4. Cover according to any one of the preceding claims, characterized in that said elastically deformable element (15) is overmoulded on the free end (14) of said axial projection (13).

5. Cover according to any one of the preceding claims, characterized in that said axial projection (13) is produced at least partially in a single piece with the cover (1).

6. Cover according to any one of claims 1 to 4, characterized in that said axial projection (13) is mounted on said cover (1) by assembly.

7. Cover according to claim 6, characterized in that said axial projection (13) forms an inner skirt (13) that is produced from elastomer and that at least partially constitutes said elastically deformable element (15).

8. Motor gear unit (2) for an electric actuator for a disc brake, said motor gear unit (2) comprising a housing (4) enclosing an electric motor and a reduction gear mechanism (5) mechanically connected to said electric motor to provide at the output (50) of said reduction gear mechanism (5) a rotational drive of a shaft (52) along an output axis, said reduction gear mechanism (5) comprising a pinion gear system and a toothed ring gear (3) at least partially accommodating said gear system (5) and having a ring gear axis defining an axial direction (A1), said toothed ring gear (3) having a free edge (30) of the ring gear, said housing (4) having an access opening to said gear system (5) and to said ring gear (3) characterized in that it comprises a cover (1) according to any one of claims 1 to 7, said cover (1) closing said access opening.

9. Motor gear unit according to claim 8, characterized in that the inner skirt (13) of the cover (1) has a cross section the shape of which is substantially the same as the shape of the cross section of the ring gear (3), so that the free edge (30) of the ring gear (3) is positioned opposite the free end (14) of the inner skirt (13) of the cover (1) when the cover (1) is positioned on the housing (4), in order to bear on the entire free edge (30) of the ring gear (3).

10. Motor gear unit according to claim 8 or 9, characterized in that said ring gear (3), the housing (4) receiving said ring gear (3) and said inner skirt (13) of the cover (3) are each at least partially cylindrical.

11. Motor gear unit according to claim 10, characterized in that the recess of the housing (4) and the toothed ring gear (3) interact with each other by cooperation of shape, in particular by mutually complementary reliefs (33) formed around the ring gear (3) to lock said ring gear (3) in rotation in said recess of the housing (4).

12. Vehicle brake, in particular a disc brake, comprising an electric motor gear unit (2) according to any one of claims 8 to 11 or a motor gear unit (2) comprising a cover (1) according to any one of claims 1 to 7, which drives an electric braking actuator, in particular for parking.

13. Method for assembling a cover (1) according to any one of claims 1 to 7, onto an access opening of a housing (4) of a motor gear unit (2) according to any one of claims 8 to 11, characterized in that it comprises the following steps: - positioning the ring gear (3) in the recess of the housing (4) via free or sliding fit, - positioning the cover (1) on the housing (4), by applying said elastically deformable element (15) against the free edge (30) of said ring gear (3), - applying a pressure on the cover (1) so that said axial projection (13) exerts a pressure on the ring gear (3) in the axial direction (A1) of the ring gear, and - fastening the cover (1) onto the housing (4), in particular by welding or bonding.