Cover for a gear motor unit for an electric disc brake actuator, and gear motor unit comprising such a cover

Abstract

The invention relates to a cover (1) for a gear motor unit (2) comprising a housing (4) enclosing an electric motor and a gear mechanism (5) comprising a pinion engaging with an inner surface (31) of a rotationally fixed ring gear (3) having a free edge (30). The cover (1) further comprises an axial protrusion (13), in particular an inner skirt, positionable so as to at least partially abut the free edge (30), said protrusion (13) having at least one elastically deformable element (15) on a free end (14) opposite the free edge (30) of the ring (3), the elastically deformable element being positionable at least partially against the free edge (30) of the ring (3) so as to retain said gear (3) in the housing (4) in the axial direction (A1) of the ring.

Description

[0001] The present invention relates to an electric motor gear unit mounted at the end of a disc brake actuator, comprising a cantilevered motor that is parallel to and on the same side as the output of a reduction gear. Background Technology

[0002] In the field of brakes, it has become common practice, especially for disc brakes, to install electric actuators directly on the brake itself. These brakes are generally used for parking and emergency braking, but sometimes also as service brakes.

[0003] Typically, the actuator is driven by an electric motor gear unit (MGU), which includes a drive unit (or motor) and a transmission unit (or reduction gear mechanism). These two units are interconnected (motor drive transmission) and enclosed in a protective housing, which includes an open housing on one hand and a closed cover on the other.

[0004] The cross-sectional shape of the open housing substantially matches the external shape of the assembly formed by the two connected devices. The cover also has the cross-sectional shape of the housing and is fixed to the housing by welding.

[0005] The transmission device includes several interconnected gear stages, particularly a planetary gear (which may include at least one toothed ring gear with internal teeth) including at least one toothed ring gear with internal teeth.

[0006] Brake motor gear units known from document FR 3074757 include at least two planetary gear trains forming a reduction stage mounted in series, which are enclosed in a housing or protective housing.

[0007] With the development of motor gear units, the manufacturing process of the parts containing these ring gears had to be changed: from then on, they had to be made of metal and installed in a housing, instead of being molded in a housing as before.

[0008] Typically, the housing has protruding ribs, and the ring gears are mounted in the housing in a force-fit manner to hold them in place: by being compressed against the ring gears, it is the ribs that hold one or more ring gears in the proper position within the housing.

[0009] However, it should be noted that by forcibly installing parts into the housing, debris may fall off the parts, which could adversely affect the rotational drive of the gears.

[0010] It was also noted that, by combining ribs and force, this solution could generate noise within the housing. Summary of the Invention

[0011] Therefore, the present invention aims to provide an alternative solution to ensure that the ring gear remains within the housing without generating debris within the housing, which could damage the gear or impair its operation.

[0012] Therefore, the present invention relates to a cover for a motor gear unit of an electric actuator for a brake, particularly for a disc brake, the motor gear unit comprising a housing surrounding an electric motor and a reduction gear mechanism mechanically connected to the electric motor to provide rotational drive of a shaft along an output axis at the output of the reduction gear mechanism; the reduction gear mechanism comprising a planetary gear system including planetary gears meshing with the inner surface of a rotationally fixed toothed ring gear, the reduction gear mechanism being mounted in a recess of the housing and having a ring gear axis defining an axial direction, the housing having an access opening into the recess such that the gear system or at least the toothed ring gear has a free edge pointing toward the access opening.

[0013] According to the invention, the cover is designed to close the access opening, and notably, it includes an axial protrusion, particularly an inner skirt, which, when the cover closes the opening, is positioned to at least partially abut against the free edge of the ring gear; the protrusion has at least one elastically deformable element at its free end opposite the free edge of the ring gear, which is capable of at least partially abutting against the free edge of the ring gear to retain the ring gear within the housing in the axial direction.

[0014] In this manufacturing method, the ring gear is axially held in place by the cover. The ring gear can then be assembled into the housing using either a free fit or a sliding fit. Therefore, the limitations and disadvantages of force-fitting are avoided, particularly the need for a press and the risk of chip formation.

[0015] According to an advantageous embodiment presented below, the axial protrusion includes an inner skirt that is elastically deformable and / or includes at least three axially protruding deformable pillars distributed around the output axis, particularly with a gap between them of at least 60° or at least 80°.

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

[0017] Furthermore, the elastically deformable element is molded over the free end of the axial protrusion.

[0018] According to an advantageous embodiment of the invention, the axial protrusion is at least partially integral with the cover.

[0019] According to a variant embodiment, the axial protrusion is mounted on the cover by assembly.

[0020] Furthermore, the axial protrusion forms an inner skirt, which is made of an elastomer and at least partially constitutes the elastically deformable element.

[0021] The present invention also relates to a motor gear unit for an electric actuator of a disc brake, the motor gear unit comprising a housing surrounding an electric motor and a reduction gear mechanism, wherein the reduction gear mechanism is mechanically connected to the electric motor to provide rotational drive of a shaft along an output axis at the output of the reduction gear mechanism; the reduction gear mechanism comprises a gear system having toothed gears and a ring gear, the ring gear at least partially housing the gear system and having a ring gear axis defining an axial direction, the toothed ring gear having a free edge of the ring gear, and the housing having an access opening for entering the gear system and the ring gear. According to the present invention, it is noteworthy that the motor gear unit includes a cover as defined above, the cover closing the access opening.

[0022] According to an embodiment of the invention, the cross-sectional shape of the inner skirt of the cover (of the motor gear unit) is substantially the same as the cross-sectional shape of the ring gear, such that when the cover is on the housing, the free edge of the ring gear is positioned opposite to the free end of the inner skirt of the cover, so as to be supported on the entire free edge of the ring gear.

[0023] Advantageously, the ring gear, the housing housing the ring gear, and the inner skirt of the cover are each at least partially cylindrical.

[0024] Also advantageously, the recesses of the housing and the toothed ring gear interact through a form fit, particularly through complementary reliefs formed around the ring gear, preventing the ring gear from rotating within the recesses of the housing.

[0025] In this embodiment, the ring gear includes an outer surface having at least one first protruding element, and the housing includes an inner surface having at least one second protruding element, wherein the at least one first protruding element of the ring gear is capable of engaging with the at least one second protruding element of the housing.

[0026] The present invention also relates to vehicle brakes, particularly disc brakes, which include an electric motor gear unit as described above or a motor gear unit including a cover as described above, which drives an electric brake actuator, particularly for parking.

[0027] Finally, the present invention relates to a method for assembling the aforementioned cover onto the access opening of the housing of the aforementioned defined motor gear unit.

[0028] According to the present invention, it is noteworthy that the method includes the following steps:

[0029] - The ring gear is positioned in the recess of the housing by free fit or sliding fit (e.g., such that the at least one first protruding element engages with at least one second protruding element of the housing);

[0030] -The cover is positioned on the housing by abutting the elastically deformable element against the free edge of the ring gear;

[0031] - Applying pressure to the cover causes the axial protrusion to exert pressure on the ring gear along the axial direction of the ring gear, thereby compressing the elastically deformable element.

[0032] - In particular, the cover is fixed to the housing by welding or bonding.

[0033] It should be noted that even though the method provides free fit, vibration is prevented by the damping effect of (one or more) elastically deformable elements that can at least partially abut against the free edge of the ring gear, thereby holding the ring gear in the housing along the axial direction. Attached Figure Description

[0034] Other advantages and features of the invention will become apparent upon examination of the embodiments, which are not intended to limit the invention, as shown in the accompanying drawings:

[0035] Figure 1 This is a perspective view of a motor gear unit according to the present invention.

[0036] Figure 2 This is a perspective view of a cover for a motor gear unit according to the present invention.

[0037] Figure 3 This is a perspective view of the cover and the toothed ring gear, which includes... Figure 1 The motor gear unit shown, and

[0038] Figure 4 yes Figure 1 The diagram shows a partial exploded perspective view of a portion of the motor gear unit, illustrating the cover according to the invention, located in relation to... Figure 3 The toothed ring gear shown above the planetary gears meshing on the inner surface of the ring gear is positioned below the planetary gears so that they are exposed. Detailed Implementation

[0039] The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom” used in the following description are merely to help the reader locate their positions in the figures; it should be understood that these terms are not intended to limit the invention.

[0040] Cover 1, which is the subject of this invention, is described separately in Figure 2 As shown in [the image]. Figure 1 , Figure 3 and Figure 4 In the motor gear unit 2, it is installed in the motor gear unit 2, and it is associated with the toothed ring gear 3 located in the motor gear unit. Figure 3 Or spaced apart from the toothed ring gear 3. Figure 4 ).

[0041] The cover 1 shown in the figure is designed to fix the ring gear 3 in the appropriate position in the motor gear unit: therefore, the components included in the motor gear unit 2 and their arrangement are conveniently shown first, thereby determining in which area of ​​the motor gear unit 2 the cover 1 according to the invention is implemented.

[0042] Figure 1 The entire motor gear unit 2 is shown, with the cover 1 located on top of the motor gear unit 2 and visible.

[0043] The motor gear unit 2 is designed for disc brake actuators, including movable calipers that are slidably mounted on a bracket. The actuator drives the caliper to move under the action of the motor gear unit or a hydraulic piston.

[0044] Figure 1 An example of such a motor gear unit is shown, and it should be noted that it includes a housing 4, which forms a protective housing for the motor gear unit 2. The housing 4 has two parts:

[0045] - The upper portion 40 has a generally bean-shaped cross-section and houses two cylindrical pieces: located in Figure 1 The first cylindrical member 41 on the left side of the upper middle portion 40 and located in Figure 1 The second cylindrical member 42 on the right side of the upper middle part 40;

[0046] - The lower portion 43 is formed by a second cylindrical member that protrudes downward and extends to a height substantially equal to that of the upper portion 40.

[0047] In fact, the lower part 43 extends downwards to form a second cylindrical member 42 to accommodate the electric motor (not shown) of the motor gear unit 2.

[0048] Motor gear unit 2 also includes reduction gear mechanism 5 (see Figure 3 Its output 50 is visible and corresponds to the first cylindrical member 41 at the lower part of the upper portion 40 of the housing.

[0049] The reduction gear mechanism 5 is achieved by means of Figure 3 and Figure 4 The gear 51 shown is mechanically connected to an electric motor, and the pinion is located in the cylindrical part 42 of the upper part 40 of the housing 4.

[0050] The reduction gear mechanism 5 includes a planetary gear system containing planetary gears, which is particularly important in... Figure 4 As can be seen, it meshes internally with the toothed ring gear 3 (see...). Figure 3 (The teeth of some gears mesh between the teeth on the inner surface of the toothed ring gear 3).

[0051] It should be noted that the toothed ring gear 3 is fixedly installed inside the housing 4 and rotates.

[0052] The ring gear 3 is installed in the recess of the housing 4, in the cylindrical part 41 of the upper part 40 of the housing 4.

[0053] exist Figure 3 It is noted that the output 50 of the reduction gear mechanism has a shaft 52 extending along the output axis A1.

[0054] The output axis A1 corresponds to the axis of the ring gear 3, and it defines the axial direction.

[0055] Shaft 52 makes it possible to control the actuator at the origin of the piston caliper movement in a disc brake (actuator and disc brake not shown), which is typically of the screw and nut type.

[0056] According to the invention, the upper portion 40 of the housing 4 has an access opening, which is closed by the cover 1 according to the invention.

[0057] The access opening allows the gear system 5 and the toothed ring gear 3 to be axially introduced into the housing 4.

[0058] The lower portion 43 of the housing 4, which at least partially houses the electric motor 4, is also closed.

[0059] Figure 3 and Figure 4 The ring gear 3 is shown with a free edge 30 pointing to the entry opening of the housing 4 (and thus to the cover 1 that closes the entry opening according to the invention).

[0060] The ring gear 3 is typically cylindrical, having a toothed inner surface 31 and an outer surface 32. The outer surface 32 has three radially outwardly projecting elements 33, each extending in a direction parallel to the axial direction A1. These projecting elements are equidistant from each other.

[0061] The interior of the housing 4 that houses the ring gear 3 is cylindrical and includes an inner surface that also has inwardly projecting elements. When housed within the housing 4, these internal projecting elements engage with the protruding elements 33 of the ring gear. In this way, when the ring gear 3 is located in the receiving recess of the housing 4, the ring gear is prevented from rotating within the receiving recess of the housing.

[0062] Therefore, the recess of the housing 4 and the toothed ring gear 3 interact through shape matching, especially through complementary reliefs formed specifically around the ring gear 3 (protruding elements inside the housing and protruding elements on the outer surface of the ring gear 3).

[0063] The cover 1 according to the invention will now be discussed more clearly.

[0064] The cover 1 includes a bottom wall 10 and an outer skirt 11 located at the edge of the bottom wall 10. When the cover 1 is placed in place and fixed to the housing 4 by welding, the outer skirt 11 is aligned with the outer wall of the housing 4.

[0065] The bottom wall 10 includes protruding elements formed as a honeycomb structure 12 (see...). Figure 2 It has the function of limiting the vibration of cover 1 (bottom wall 10 is used as a vibrating skin).

[0066] The cover 1 has a shape similar to the cross-sectional shape of the shell 4.

[0067] According to the present invention, the cover 1 further includes an axial protrusion (i.e., when the cover is located on the access opening of the housing 4, the axis of the axial protrusion merges with the axis A1).

[0068] In the example shown in the figure, the axial protrusion is the inner skirt 13, which is positioned at least partially abutting against the free edge 30 of the ring gear 3 when the cover 1 closes the entry opening of the housing 4 (see figure). Figure 3 ).

[0069] The inner skirt 13 (or axial protrusion) has a free end 14 opposite to the free edge 30 of the ring gear 3. On this free end 14, the ring gear has at least one elastically deformable element 15, which in the illustrated example is generated by eight elastically deformable pillars 15.

[0070] These eight pillars 15 protrude axially from the free end 14 of the inner skirt 13 and abut against the free edge 30 of the ring gear 3 (see...). Figure 3 ), so that the ring gear 3 can be fixed to the housing 4 in the axial direction A1.

[0071] The ring gear 3 is thus axially held by the cover 1 and can be assembled in the housing by free fit or sliding fit: thus avoiding the limitations and disadvantages of the force fit provided in the prior art, especially the need to use a press and the risk of debris formation that may have a detrimental effect on the proper operation of the motor gear unit.

[0072] The inner skirt 13 is at least partially cylindrical, and the eight pillars 15 are advantageously distributed equidistantly or at equal angles around the output axis A1.

[0073] It must be understood that the present invention is not limited to having eight columns, but may provide more or fewer columns.

[0074] In another embodiment, it may be specified that at least three posts are distributed around axis A1, and in particular, the gap between them is at least 60° or at least 80°.

[0075] The inner skirt 13 is at least partially cylindrical and its cross-sectional shape is substantially the same as that of the ring gear 3, such that when the cover 1 is on the housing 4, the free edge 30 of the ring gear 3 is positioned opposite to the free end 14 (edge) of the inner skirt 13 of the cover 1, so as to be supported on the entire free edge 30 of the ring gear 3.

[0076] In the variant, the skirt 13 and the pillar 15 are elastically deformable: for example, the skirt is made of an elastomer and will at least partially constitute an elastically deformable element according to the invention.

[0077] In variations that do not depart from the scope of the invention, these pillars are overmolded onto the free end 14 of the inner skirt 13.

[0078] In a variant, the elastically deformable element is overmolded onto the free end of the axial protrusion, i.e., the free end of the column 15, without exceeding the scope of the invention.

[0079] The axial protrusion or column 15 is:

[0080] -Or it can be made as a single piece with skirt 13.

[0081] -Or it can be manufactured on the free end 14 of the cover.

[0082] Figure 2 and Figure 3 The cover is also shown to have a second inner skirt 16 formed by the partial outlines of two interlaced rings. This second inner skirt 16 surrounds, for example, a gear located in the upper portion of the housing, particularly gear 51 in the example shown in the figure.

[0083] The method of assembling cover 1 onto housing 4 of motor gear unit 2 will now be discussed.

[0084] First, the ring gear 3 is positioned in the recess of the housing 4 by free fit or sliding fit.

[0085] Then, the cover 1 is positioned on the housing 4 by abutting the elastically deformable element 15 against the free edge 30 of the ring gear 3.

[0086] Then pressure is applied to the cover 1, so that the axial protrusion 14 (the free end of the inner skirt) applies pressure to the ring gear 3 along the axial direction A1 of the ring gear, thereby compressing the elastically deformable column 15.

[0087] Finally, the cover 1 is fixed to the housing 4, especially by welding or bonding.

[0088] As can be understood from the foregoing description, the present invention demonstrates how to keep the ring gear 3 in the proper position within the housing 4 of the motor gear unit 2 without the need for force.

[0089] It must be understood that the present invention is not limited to the specific embodiments shown in the accompanying drawings and the description above. The invention extends to implementations of equivalent methods and embodiments of brakes (not shown), such as vehicle disc brakes comprising, for example, a motor-gear unit as described above, which would include the cover shown and described above, or include equivalent characteristics. In this theoretical context, the vehicle brake according to the invention is designed to drive an electric brake actuator, particularly for parking.

[0090] Explanation of reference numerals in the attached figures

[0091] 1. Cover

[0092] 2 Motor Gear Unit

[0093] 3. Toothed ring gear

[0094] 4. Shell

[0095] 5. Reduction Gear Mechanism

[0096] 10 bottom wall

[0097] 11. Outer skirt of the bottom edge

[0098] 12. Honeycomb structure

[0099] 13. Inner skirt

[0100] 14. Free end of the inner skirt

[0101] 15 Elastically deformable elements

[0102] 16 Second Inner Skirt

[0103] 30. Free edge of the ring gear

[0104] 31 Toothed inner surface

[0105] 32 Outer surface

[0106] 33 Prominent Components

[0107] 40 Upper part of the shell

[0108] 41 First cylindrical component

[0109] 42 Second cylindrical component

[0110] 43 Lower part

[0111] 50 Output of the reduction gear mechanism

[0112] 51 Output gear of motor shaft

[0113] 52 Output shaft of the reduction gear mechanism

[0114] A1 Output axis / axis direction

Claims

1. A cover (1) for a motor gear unit (2) of an electric actuator for a brake, the motor gear unit (2) comprising a housing (4) surrounding an electric motor and a reduction gear mechanism (5), wherein the reduction gear mechanism (5) is mechanically connected to the electric motor to provide rotational drive of a shaft (52) along an output axis at the output (50) of the reduction gear mechanism (5), The reduction gear mechanism (5) includes a planetary gear system, which includes planetary gears meshing with the inner surface (31) of a rotary fixed toothed ring gear (3), the toothed ring gear (3) being mounted in a recess of the housing (4) and having a ring gear axis defining an axial direction (A1). The housing (4) has an access opening into the recess, allowing the gear system, or at least the toothed ring gear (3), to be axially inserted therein. The toothed ring gear (3) has a free edge (30) pointing towards the entry opening. The cover (1) is designed to close the access opening, and is characterized in that the cover includes an axial protrusion that, when the cover (1) closes the opening, is positioned to at least partially abut against the free edge (30) of the ring gear (3). The protrusion (13) has at least one elastically deformable element (15) on its free end (14) opposite to the free edge (30) of the ring gear (3), the at least one elastically deformable element being able to at least partially abut against the free edge (30) of the ring gear (3) so as to retain the ring gear (3) in the housing (4) along the axial direction (A1).

2. The cover according to claim 1, characterized in that, The axial protrusion includes an inner skirt (13), which is elastically deformable and / or includes at least three axially protruding elastically deformable columns distributed around the output axis.

3. The cover according to claim 2, characterized in that, The at least three axially projecting, elastically deformable columns are equidistant from each other.

4. The cap according to any one of claims 1 to 3, characterized in that, The elastically deformable element (15) is molded over the free end (14) of the axial protrusion.

5. The cap according to any one of claims 1 to 3, characterized in that, The axial protrusion is at least partially integral with the cover (1).

6. The cap according to any one of claims 1 to 3, characterized in that, The axial protrusion is assembled onto the cover (1).

7. The cover according to claim 6, characterized in that, The axial protrusion forms an inner skirt (13), which is made of an elastomer and at least partially constitutes the elastically deformable element (15).

8. The cap according to any one of claims 1 to 3, characterized in that, The brake is a disc brake.

9. The cover according to claim 2, characterized in that, The gap between at least three axially projecting, elastically deformable columns is at least 60° or at least 80°.

10. A motor gear unit (2) for an electric actuator of a disc brake, the motor gear unit (2) comprising a housing (4) surrounding an electric motor and a reduction gear mechanism (5), wherein the reduction gear mechanism (5) is mechanically connected to the electric motor to provide rotational drive of a shaft (52) along an output axis at the output (50) of the reduction gear mechanism (5). The reduction gear mechanism (5) includes a pinion system and a toothed ring gear (3) that at least partially accommodates the gear system. The toothed ring gear (3) has a ring gear axis defining an axial direction (A1) and a free edge (30) of the ring gear. The housing (4) has an access opening for entering the gear system and the ring gear (3). The mechanism is characterized in that... The motor gear unit includes a cover (1) according to any one of claims 1 to 9, the cover (1) closing the access opening.

11. The motor gear unit according to claim 10, characterized in that, The cross-sectional shape of the inner skirt (13) of the cover (1) is substantially the same as that of the ring gear (3), such that when the cover (1) is located on the housing (4), the free edge (30) of the ring gear (3) is positioned opposite to the free end (14) of the inner skirt (13) of the cover (1) so as to be supported on the entire free edge (30) of the ring gear (3).

12. The motor gear unit according to claim 10 or 11, characterized in that, The ring gear (3), the housing (4) that houses the ring gear (3), and the inner skirt (13) of the cover are each at least partially cylindrical.

13. The motor gear unit according to claim 12, characterized in that... The recess of the housing (4) and the toothed ring gear (3) interact through a form fit to prevent the ring gear (3) from rotating in the recess of the housing (4).

14. The motor gear unit according to claim 12, characterized in that... The recess of the housing (4) and the toothed ring gear (3) interact through complementary reliefs (33) formed around the ring gear (3), preventing the ring gear (3) from rotating in the recess of the housing (4).

15. A vehicle brake comprising an electric motor gear unit (2) according to any one of claims 10 to 14 or a motor gear unit (2) comprising a cover (1) according to any one of claims 1 to 9, which drives an electric brake actuator for parking.

16. The vehicle brake according to claim 15, characterized in that, The vehicle brakes are disc brakes.

17. A method for assembling a cover (1) according to any one of claims 1 to 9 onto an access opening of a housing (4) of a motor gear unit (2) according to any one of claims 10 to 14, characterized in that, The method includes the following steps: -The ring gear (3) is positioned in the recess of the housing (4) by free fit or sliding fit. -The cover (1) is positioned on the housing (4) by abutting the elastically deformable element (15) against the free edge (30) of the ring gear (3). - Apply pressure to the cover (1) such that the axial protrusion applies pressure to the ring gear (3) along the axial direction (A1) of the ring gear, and - Fix the cover (1) onto the housing (4).

18. The method according to claim 17, characterized in that, The cover (1) is fixed to the housing (4) by welding or bonding.

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