SATELLITE CARRIER FOR DIFFERENTIAL EPICYCLOIDSOLE REDUCER OF A BRAKE ACTUATOR AND EPICYCLOIDSOLE REDUCER CONTAINING SUCH A SATELLITE CARRIER

Abstract

The invention relates to a planet carrier (3, 3') for a differential epicyclic gearbox of a brake actuator. It comprises an armature arranged and configured to carry planet gears (30) distributed angularly around the axis (A) of the planet carrier, said armature being a cylindrical sleeve (32) comprising a first and a second edge (33, 34). The sleeve includes at least one opening (35) through which a planet gear (30) projects radially.The first and second edges comprise respectively a first and second radial flange (36, 37) extending inwards towards the cylindrical sleeve, each comprising a notch (38) of circular cross-section, extending from the cylindrical sleeve on either side of said at least one opening (35) in a longitudinal direction (D) parallel to the axis (A) of said planet carrier, the notches supporting a shaft (31) of circular cross-section, ensuring the rotational guidance of said planet gear. Figure for the abbreviation: [Fig.4].

Description

Title of the invention: SATELLITE CARRIER FOR DIFFERENTIAL EPICYCLOIDSOLE REDUCER OF AN ACTUATOR EPICYCLOIDAL BRAKE AND REDUCER WITH SUCH A SATELLITE CARRIER

[0001] The present invention relates in particular to a planet carrier for differential reduction brake actuator.

[0002] The field of the invention is that of braking systems for automobiles.

[0003] The invention proposes a satellite carrier comprising an arranged frame and configured to carry satellite gears distributed angularly around the axis of the satellite carrier.

[0004] The armature comprises a single plate arranged and configured to form a cylindrical envelope which has openings through which at least one satellite pinion protrudes radially.

[0005] The plate has a notch forming a longitudinal groove on at least one side of the openings, along a direction parallel to the axis of the planet carrier, so as to support one or more rotating guide shafts protruding from said planet gears.

[0006] The brake actuator comprising such a planet carrier includes two radial rings which overlap at least partially and which each include an internal gear which interlocks with the gear of the same planet.

[0007] At least one of the two crowns is movable in translation.

[0008] PRIORITY OF THE TECHNOLOGY

[0009] In a vehicle, particularly a road vehicle, the function of the parking and / or emergency brake consists of applying and maintaining a clamping force of brake pads attached to a part fixed to the chassis, on a rotating moving part which is attached to one or more wheels, typically a disc or a drum.

[0010] In braking systems using one or more electric actuators, it is known to use a screw-nut system to exert linear pressure on the brake pad, often via a piston. This type of configuration exists for electric operation alone, or in combination with hydraulic actuation of this or another piston.

[0011] In general, the screw-nut system is actuated by a geared motor. Some gear reduction mechanisms include one or more epicyclic gear trains. An epicyclic gear train comprises two planetary gears (a first planetary gear, called the inner one, and a second planetary gear, called the outer one) and sun gears carried by a sun gear carrier. Each sun gear meshes simultaneously with both planetary gears, which are arranged coaxial arrangement. Most often, the outer planet gear is internally toothed and is often called the "crown." In this case, the inner planet gear is often simply called "the planet," without further specification.

[0012] Document FR 3 031 154 A discloses a reducer which includes two reduction stages.

[0013] With reference to [Fig. 1], it comprises an upstream reduction stage formed by an upstream epicyclic train with satellites 131 and a fixed ring 121.

[0014] This upstream train is driven at the input by its inner planetary gear 111, itself driven by a toothed shaft having a drive footprint 119 and having an axis A. This upstream epicyclic train drives at the output its planet carrier 130. This upstream planet carrier 130 carries the input planetary gear 139 for a second reduction stage called a differential epicyclic reducer (DPR) with double crown.

[0015] The second stage includes an epicyclic gear train driven at the input by the planetary gear 139 and whose satellites (or planetary gears) 141 mesh with a fixed ring 121, here the same as for the upstream epicyclic gear train.

[0016] From this fixed ring, by means of a common planet carrier 140 (or sleeve 140) (also represented by Figures 2a and 2b), the planets 141 of the differential reducer (DPR) drive at the output a movable ring 151. On its outer surface, this movable ring 151 has a thread 152 coaxial with the epicyclic gear trains, and cooperating with an internal thread 161 of the piston 16 to drive it in translation.

[0017] Preferably, the fixed ring gear 121 is common to both epicyclic gear trains, and the differential planet gears 141 are common to both rings 121, 151 of the differential train, which generally have a different number of teeth. The planet carrier is generally machined, sintered, or molded, made of metal or plastic.

[0018] The satellite carrier comprises an armature of general shape simply tubular, or approximately so, and open at its axial ends.

[0019] With reference to [Fig. 2] (2a and 2b), the frame of the satellite carrier 140 has the shape of a tube whose wall thickness is such that the wall encompasses the rotation shaft of each satellite. The satellite carrier is machined radially along its circumference to create several windows 149 (or housings), substantially rectangular in shape, each window being designed to receive a satellite.

[0020] Each window is delimited longitudinally at each end by a support part of the tube forming a rotation support for each satellite.

[0021] A bore is machined on each transverse face of a support part to receive a rotation shaft of a satellite. Thus machined, the satellite carrier constitutes a cage for the satellites.

[0022] Each support part forms a transverse flange for each end of the satellite and the satellites protrude radially from the circumference of the satellite carrier.

[0023] Each guide shaft is pressed into a bore of the planet carrier, each satellite being freely rotationally mounted on a guide shaft. Each satellite has a longitudinal through bore that opens onto each transverse face and is arranged and configured to receive a guide shaft.

[0024] However, it remains interesting to facilitate assembly and lower the manufacturing cost.

[0025] To this end, document FR 3 074 242 proposes a satellite carrier which includes a plate 20 ([Fig.3]) arranged and configured to form a cylindrical envelope, the plate 20 having openings 21 through which a satellite pinion 30 protrudes radially.

[0026] The plate 20 has a longitudinal groove 25 which extends from at least one side of the openings, along a direction parallel to the axis of the planet carrier, so as to support one or more rotating guide shafts 31 protruding from the planet gears 30.

[0027] The satellites are thus inserted radially on the cylindrical plate 20 of the satellite carrier and the plate 20 of the satellite carrier is made in one piece: these two features ensure a reduction in assembly time and a decrease in manufacturing cost.

[0028] However, it is still interesting to facilitate assembly, lower manufacturing costs and reduce the size of the satellite carrier, or even of the assembly comprising the satellite carrier and the fixed and moving rings. Description of the invention

[0029] According to a first aspect of the invention, at least one of the aforementioned goals is achieved with a planet carrier for a differential epicyclic reducer of a brake actuator, for the actuation of a vehicle parking brake, in particular an automobile, which planet carrier comprises an armature arranged and configured to carry planetary gears distributed angularly around the axis of the planet carrier, said armature being a cylindrical sleeve comprising a first and a second edge, said sleeve comprising at least one opening through which a planetary gear protrudes radially.

[0030] The satellite carrier according to the invention is remarkable in that said first and second edges respectively comprise a first and a second radial flange extending inwards towards the cylindrical sleeve, the first and second flanges comprising a notch of circular cross-section extending from the cylindrical sleeve on either side of said at least one opening following a longitudinal direction parallel to the axis of said satellite carrier, the notches supporting a shaft of circular section, ensuring the rotational guidance of said satellite pinion protruding through said at least one opening.

[0031] According to an advantageous embodiment, the notch includes a notch depth which corresponds, or substantially corresponds, to the radius of said shaft.

[0032] According to an alternative embodiment, the notch includes a notch depth which corresponds, or corresponds substantially, to the diameter of said shaft.

[0033] Advantageously, the satellite carrier comprises at least three notches and three satellite gears equidistant from each other, preferably four notches and four satellite gears equidistant from each other.

[0034] Furthermore, said cylindrical sleeve of said frame is made in one piece, preferably by molding.

[0035] Preferably, said satellite pinion and said shaft are made in one piece, preferably again by molding.

[0036] The invention also relates to a differential epicyclic reducer of a brake actuator, comprising a double ring and at least one planet carrier as defined above.

[0037] Advantageously, the double crown comprises a first fixed crown and a second movable crown rotating about its axis, said fixed and movable crowns each having an internal gear and being coaxial, said at least one satellite pinion engaging at least partially in the internal gear of said first crown and in the internal gear of said second crown.

[0038] In addition, the first and second rings overlap at least partially and said movable ring is partially inserted into said fixed ring, said movable ring having a radial wall which is crossed in its center by an opening having a gear or a thread, to drive in rotation respectively a toothed pinion or a worm screw.

[0039] The invention relates, finally, to a brake actuator comprising a reducer as defined above.

[0040] LIST OF FIGURES

[0041] Other features and advantages of the invention will become apparent from the detailed description of implementations and embodiments, which are by no means limiting, and from the accompanying drawings where:

[0042] [Fig.1] is a longitudinal sectional view of part of a mechanism of a brake actuator, including a planet carrier according to the prior art;

[0043] [Fig. 2] comprises two views 2a and 2b which are views of the satellite carrier according to the prior art of [Fig. 1], view 2a being an axial view in slight perspective, view 2b being a perspective view of a cross-section of the satellite carrier showing three of its sa- tellites;

[0044] [Fig.3] is a perspective-view computer-generated image of a satellite carrier according to art prior;

[0045] [Fig.4] is an axial cross-sectional view of a differential epicyclic reducer of an ac- brake actuator according to the invention;

[0046] [Fig.5] is a schematic representation of the reducer shown in [Fig.3], illustrating the moving and fixed elements of such a reducer;

[0047] [Fig.6] is a perspective view of a satellite carrier conforming to a first mode realization of the invention;

[0048] [Fig.7] is a perspective view of a satellite carrier conforming to a second mode of realization of the invention;

[0049] [Fig.8] is an axial cross-sectional view of a part of a reducer conforming to the invention, illustrating the radial forces that the elements of the reducer apply to each other;

[0050] [Fig.9] is a radial cross-sectional view of another part of the reducer conforming to the invention, illustrating the forces exerted by certain elements of the reducer on the satellite gears; and

[0051] [Fig. 10] is a radial cross-sectional view of a portion of the reducer illustrating the tangential components of the forces that the reducer elements apply to each other.

[0052] DESCRIPTION OF EMBODIMENT METHODS

[0053] The embodiments that will now be described are not limiting: in particular, variants of the invention may be made comprising only a selection of features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0054] Of course, the invention is not limited to the examples that will be described, and many modifications can be made to these examples without departing from the scope of the invention. Furthermore, the various features, forms, variants, and embodiments of the invention can be combined with one another in various ways, provided that they are not incompatible or mutually exclusive.

[0055] Figures 1 to 3 illustrate the prior art and have already been described previously.

[0056] Fig. 4 shows a reducer (also called a differential train) according to the invention.

[0057] This is a differential epicyclic reducer of a brake actuator, which includes a double ring (references 1 and 2) and a planet carrier (reference 3).

[0058] The satellite carrier 3 of the reducer shown in [Fig. 4] is the one shown alone in [Fig.7].

[0059] It includes an armature 32, made in the form of a cylindrical sleeve which, taken in its length L, has a first edge 33 of sleeve and a second edge 34 of sleeve.

[0060] The sleeve 32 comprising four openings 35 through which satellite gears 30 project radially.

[0061] We see, on [Fig.7], that the first and second edges 33 and 34 comprise respectively a first flange 36 and a second flange 37 (visible for example in [Fig.8]), radial, each of the flanges 36 and 37 extending towards the interior of the cylindrical sleeve 32.

[0062] In the context of the example, the sleeve is made by molding: it is a solid part, of thickness e, each collar corresponding to the lateral edge of the sleeve.

[0063] It should be understood that the sleeve 32 could also be made hollow without going out of the scope of the invention.

[0064] The difference with the sleeve 20 of the prior art embodiment shown in [Fig. 3] lies in the presence of the flanges in the embodiment according to the invention, which gives the sleeve greater robustness than that illustrated in [Fig. 3]. Indeed, the sleeve according to the invention does not have an assembly joint P (the sleeve 20 of the prior art being obtained by folding a sheet metal plate and joining the two free edges of the plate) and the presence of the flanges 36 and 37 forming lateral edges gives the sleeve 32 greater rigidity (it is less easily deformed).

[0065] The difference between the sleeve 32 according to the invention and the sleeve 140 of the prior art, illustrated in [Fig.2], lies in the realization of the housings: according to this prior art, the planetary gears 141 are inserted into the housings along a direction D which is parallel to the axis A of the sleeve 140.

[0066] The planetary gears 141 each comprise a shaft 142, of circular cross-section, ensuring the rotational guidance of the satellite gear.

[0067] The planetary gears 141 are positioned in the housing by inserting the end of their shaft 142 through an opening 143 which is made in the wall of the housing 149.

[0068] Then, the assembly is held by a ring 148 of the same diameter and thickness as the sleeve 140, the ring 148 also having through openings to accommodate the other end of the shafts 142 which ensure the rotational guidance of the planetary gears 141.

[0069] The satellite carrier according to the invention, illustrated in particular in [Fig. 7], is different: instead of the through openings 143, the sleeve 32 comprises notches 38 of circular section, and which have a diameter slightly greater than the diameter of the shafts 31 of the satellite gears 30 to accommodate them.

[0070] The notches 38 extend on either side of one side of the opening 35 (or housing for a pinion 30) along a longitudinal direction D which is parallel to the axis A of the cylindrical sleeve 32.

[0071] The notches 38 thus support the shafts 31 of the pinions 30 which protrude from the openings 35.

[0072] In this way, the satellite gears 30 are inserted radially into the openings 35: it is therefore not necessary to provide a retaining ring 148 as in the prior art.

[0073] It should be noted that the arrangement of the openings 35 is such that the satellite pinions 30, housed in the openings 35, are distributed angularly in an equidistant manner around the axis A of the satellite carrier.

[0074] The notches 38 can have different depths, depending on whether the satellite gears 30 are desired to be more or less prominent from the surface of the outer wall of the sleeve 32.

[0075] According to the embodiment illustrated in [Fig.7], the notches 38 comprise a notch depth which corresponds, or corresponds substantially, to the diameter of the shaft 31.

[0076] The satellite gears are thus salient by a height hl above the surface of the wall of the sleeve 32.

[0077] Fig. 6 presents an alternative embodiment 3' of the sleeve 32 of the satellite carrier: according to this alternative, the notches 38 have a depth which corresponds, or corresponds substantially, to the radius of the shafts 31 of the satellite gears 30: Thus, the satellite gears 30 protrude by a height h2 greater than the height hl.

[0078] It should be noted that all the satellite gears 30 are identical and that their shafts 31 are made in one piece with the toothed roller forming the body of the gear 30.

[0079] Reference will now be made to figures 4 and 5 to describe the movements of all the elements comprising the reducer according to the invention, as well as the double ring 1 and 2 and its particular arrangement on the satellite gears 30.

[0080] First of all, the reducer includes a first central pinion 4, also called "sun", which includes a toothed cylinder attached to a coaxial rotating drive shaft 40.

[0081] The planet carrier 3 is fitted around the central pinion 4, so that the satellite pinions 30 engage with the central pinion 4: thus, when the central pinion is driven in rotation, the satellite pinions 30 are also driven, in the opposite direction, and drive the planet carrier 3 in rotation.

[0082] A first ring 1 is positioned around the satellite carrier 3: it comprises an internal gear 10 which comes into contact with the satellite gears 30, on a part a of the length L of the satellite gears 30 (see [Fig.5]).

[0083] The first ring 1 is a fixed ring: when the planet carrier 3 is driven in rotation, the first ring 1 does not rotate: it is the planetary gears 30 that move inside the first fixed ring 1.

[0084] The second ring 2 is a rotating ring about the axis A of the planet carrier: indeed, the second ring 2 is also arranged around the planet carrier 3, has an internal gear 22 which meshes with the gear of the planetary gears 30, over a portion b of the length L of the planetary gears (see also [Fig. 5]): thus, when the planet carrier 30 is rotated in one direction, it rotates the ring 2 in the opposite direction. The ring 2 therefore rotates in the same direction as the central gear 4.

[0085] It can be seen in [Fig.4] that the fixed ring 1 has an angled part 11 which covers the rotating mobile ring 2: the radial and axial bulk of the reducer is thus limited.

[0086] Furthermore, the movable ring does not have a gear on its outer wall: the ring 2 has an internal part 23 ([Fig.4]) of smaller diameter, with a gear and which is offset axially in relation to the gear 22 in contact with the satellite gears 30.

[0087] Thus, the movable ring 2 is not capped by a part forming a nut or brake piston, as in the prior art: the part forming a nut or brake piston is provided axially contiguous to the reducer, and it engages in the internal part 23 of the ring 2.

[0088] The embodiment according to the invention is thus less bulky radially than the solutions of the known state of the art.

[0089] The fixed crown 1 and mobile crown 2 are coaxial.

[0090] The rotating movable ring 2 ensures the drive in movement of a screw / nut system (not shown) of the brake system.

[0091] Thus designed, the reducer according to the invention is less bulky, more robust and easier to assemble than the reducers of the Prior Art.

[0092] Figures 8, 9 and 10 will now be described to explain the forces that the elements of the reducer according to the invention produce on each other.

[0093] Overall, the assembly of the elements together (double crown, planet carrier, planet gears and central pinion - or sun gear) ensures easy assembly and stable operation which makes it possible to reduce the number of planet gears in the planet carrier:

[0094] Indeed, as shown in [Fig. 8], the forces Fl and F2 exerted by the two rings 1 and 2 are greater than the centrifugal force F4 exerted by the pinion

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[0123] central 4 on the satellite gears Fig. 9 also shows that the forces generated by the interlaced teeth of the gears compensate each other: the gears of the two crowns 1 and 2 interlaced in the gears of the pinions 30 generate forces F3 and F5 which are directed towards the inside of the reducer, while the forces F6 and F7 of the gears of the central pinion 4 interlaced in the gear of the satellite pinion 30 are directed outwards. Finally, [Fig. 10] shows that the tangential forces F8 to F12 are predominant compared to the radial forces shown in [Fig.8]. The reducer according to the invention is thus stable and easy to implement. The invention is mainly applicable to the braking of motor vehicles. Nomenclature: A: axis of the planet carrier 3, the central pinion 4 and the reduction gear hl: height of the satellite gears h2: height of the satellite gears D: Direction parallel to axis A passing through the center of shaft 31 a: length of the satellite pinion gear meshing with the internal gear of the crown 1 b: length of the satellite pinion gear meshing with the internal gear of the crown 2 L: sleeve length 32 e: sleeve thickness 32 P: joint or seam 1: fixed crown 2: movable crown 3, 3': satellite carrier 4: central pinion 10: Internal gear of the fixed crown 1 11: angled part of the fixed crown 1 which covers the movable crown 2 16: piston 20: Satellite carrier plate 21: Openings 22: gear 23: Internal part with gear 25: Gorges 30: satellites 31: Satellite rotation guidance shaft 32: frame

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[0148] 33: first edge 34: second edge 35: opening 36: first collar 37: second collar 38: notch 40: central pinion drive shaft 4 111: planetary gear 119: drive recess 121: fixed ring gear 130: planet carrier 131: planet gear 139: planetary gear 140: planet carrier 141: planet gear 142: planetary gear shaft 143: opening 148: retaining ring 149: window or housing 151: movable ring 152: thread 161: thread Fl, F2: radial forces exerted by the rings 1 and 2 on the planet gear 30 F4: radial force exerted by the central pinion on the planet gear 30 F3, F5: forces exerted by the ring gears on the planet carrier gear 30

[0149] F6,F7: forces exerted by the central pinion gear 4 on the satellite pinion gear 30

[0150] F8, F9, F10, Fl 1 and F21: radial forces exerted by the elements on each other, others.

Claims

Claims

1. Planet carrier (3, 3') for a differential epicyclic reducer of a brake actuator, for actuating a vehicle parking brake, in particular a motor vehicle, which planet carrier (3, 3') comprises an armature arranged and configured to carry planet gears (30) distributed angularly around the axis (A) of the planet carrier, said armature being a cylindrical sleeve (32) comprising a first and a second edge (33, 34), said sleeve (32) comprising at least one opening (35) through which a planet gear (30) projects radially, characterized in that said first and second edges (33, 34) respectively comprise a first and a second radial collar (36, 37) which extends towards the inside of the cylindrical sleeve (32), the first and second collars (33, 34) comprising a notch (38) of section circular,extending from the cylindrical sleeve (32) on either side of one side of said at least one opening (35) in a longitudinal direction (D) parallel to the axis (A) of said planet carrier, the notches (38) supporting a shaft (31) of circular section, ensuring the rotational guidance of said satellite pinion (30) projecting through said at least one opening (35).,

2. A planet carrier (3') according to claim 1, characterized in that said notch (38) comprises a notch depth which corresponds, or which substantially corresponds, to the radius of said shaft (31).

3. A planet carrier (3) according to claim 1, characterized in that said notch (38) comprises a notch depth which corresponds, or which substantially corresponds, to the diameter of said shaft (31).

4. Planet carrier (3, 3') according to any one of the preceding claims, comprising at least three notches (38) and three planet gears (30) equidistant from each other, preferably four notches (38) and four planet gears (30) equidistant.

5. Planet carrier (3, 3') according to any one of the preceding claims, characterized in that said cylindrical sleeve (32) of said frame is made in a single piece, preferably by molding.

6. Planet carrier (3, 3') according to any one of the preceding claims, characterized in that said satellite pinion (30) and said shaft (31) are made in one piece, preferably by molding.

7. 7. Differential epicyclic reducer of a brake actuator, comprising a double crown (1, 2) and at least one planet carrier (3, 3') according to any one of the preceding claims.

8. 8. Reducer according to claim 7, characterized in that the double crown (1, 2) comprises a first fixed crown (1) and a second crown (2) movable in rotation around its axis, said fixed (1) and movable (2) crowns each having an internal gear (10, 22) and being coaxial, said at least one satellite pinion (30) meshing at least partially in the internal gear (10) of said first crown (1) and in the internal gear (22) of said second crown (2).

9. 9. Reducer according to claim 8, characterized in that said first and second crowns (1, 2) overlap at least partially and in that said movable crown (2) is partially inserted in said fixed crown (1), and in that said movable crown (2) comprises a radial wall which is crossed in its center by an opening having a gear or a thread, to drive in rotation respectively a toothed pinion or a worm screw.

10. Brake actuator comprising a reducer according to any one of claims 7 to 9.

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