FR3101387A1 - Planetary carrier for planetary gearbox, with lubricant storage space - Google Patents

Abstract

The invention relates to a planet carrier (10) for an epicyclic reduction gear. This planet carrier (10) comprises a body (19) and a journal (12) received in an opening of the body (19), this journal (12) being arranged to support and ensure a rotational guidance of a planet gear. According to the invention, the journal (12) and / or the body (19) of the planet carrier (10) comprise at least one groove (20) forming a lubricant storage space delimited radially inside by the au minus one journal (12). Figure for the abstract: Fig. 4

Description

Planetary carrier for planetary gearbox, with lubricant storage space

The invention relates to a planet carrier for an epicyclic reduction gear, for example for a motor vehicle electric brake actuator.

State of the prior art

A conventional planetary reduction gear comprises one or more planetary gear sets each having a planet carrier carrying one or more planet pinions configured to drive the planet carrier in rotation around an axis under the action of the rotation of a planetary pinion of entry around this same axis. Typically, the planet gears of the first or only train mesh both with the input sun gear and with a coaxial ring gear. Such an assembly results in a difference in rotational speed between the input planetary gear and the planet carrier of this train. When the reducer comprises several reduction stages, that is to say several planetary gear trains mounted in series, the planet carrier of a lower stage can typically carry a planet gear meshing with planet gears of a subsequent stage.

To allow the planet gears to be driven in rotation by a corresponding planet gear, each planet gear is typically mounted free in rotation on a journal of the planet carrier.

The rotation of a planet pinion on its pin generates friction which tends to wear these parts and which can hinder the operation of the reduction gear. For this reason, the friction faces of these parts are generally lubricated before assembly.

An object of the invention is to reduce friction and the risks of seizure resulting from the rotation of a planet pinion on its journal.

To this end, the subject of the invention is a planet carrier for an epicyclic reduction gear, comprising a body and at least one trunnion received in an opening of the body, the at least one trunnion being arranged to carry a planet pinion and provide guidance in rotation of this satellite pinion. According to the invention, the at least one journal and/or the body of the planet carrier comprise at least one groove forming a lubricant storage space delimited radially on the inside by the at least one journal.

In other words, for each trunnion of the planet carrier, either the trunnion comprises at least one groove forming such a storage space, or the body comprises at least one groove forming such a storage space, or both the trunnion and the body each comprise at least one groove forming such a storage space.

Such a storage space makes it possible to improve the lubrication of the journal and of the satellite pinion carried by this journal by storing a greater quantity of lubricant than in a conventional planet carrier. This makes it possible to reduce the friction of the planet gear on its journal during its rotation, and to reduce the risks of seizing during the rotation of the planet gear on the journal.

In one embodiment, the at least one groove may extend along a direction parallel to an axis of rotation of the pinion gear.

Such a groove orientation makes it possible to form a lubricant storage space capable of effectively lubricating the friction faces of the journal and of the pinion, a fortiori when the at least one groove is made over the entire length of the journal.

The axis of rotation of the planet pinion can typically form an axis of symmetry of the journal, along which the latter extends.

In one embodiment, the at least one groove can open onto a first face of the body and onto a second face of the body so as to form a lubricant storage space passing axially through the body of the planet carrier.

A groove running axially through the planet carrier body maximizes the amount of lubricant stored in the storage space. In addition, lubricant can thus be introduced into the storage space after assembly of the pinion on the planet carrier and of the planet pinion on the pin, from the first face of the body in the case where the planet pinion is mounted on the side of the second side of the planet carrier body.

According to a first variant, the at least one journal may comprise several grooves spaced circumferentially from each other on a radially outer face of this journal.

Preferably, these grooves can extend over the entire length of the journal, that is to say from a first end of the journal to a second end of the journal axially opposite the first end.

According to a second variant, the body of the planet carrier may comprise several grooves spaced circumferentially from each other on a radially internal face of this body, this radially internal face delimiting the reception opening of the at least one journal.

Preferably, these grooves can extend over the entire thickness of the body so as to open onto the first and the second face of the body.

These two variant embodiments can be combined. For example, the at least one pin may include several grooves spaced circumferentially from each other on the radially outer face of this pin and the body of the planet carrier may include several other grooves spaced circumferentially from each other on a radially inner face of the planet carrier body. When the grooves formed on the journal extend over one end of the journal housed in the corresponding opening of the body, one or more grooves of the journal can be arranged facing one or more grooves of the body or, alternatively, be arranged so that each of these grooves is circumferentially spaced from the grooves of the body of the planet carrier.

More generally, the embodiments described above can be combined in multiple ways without departing from the scope of the invention. By way of non-limiting example, the journal may comprise several grooves spaced circumferentially from each other on a radially outer face of this journal, while the body may comprise a single groove arranged or not opposite the one of the pin grooves.

A subject of the invention is also an epicyclic gear train comprising a planet carrier as defined above, an epicyclic reduction gear comprising such an epicyclic gear train, an electric brake actuator comprising such an epicyclic reduction gear, an electric brake comprising such an actuator, as well as a motor vehicle comprising such an electric brake.

Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

The following detailed description refers to the attached drawings in which:

is a partial schematic view in perspective and in longitudinal section of an electric brake, comprising an actuator provided with an epicyclic reduction gear according to the invention, the longitudinal section passing through a longitudinal axis around which the various components of the reduction gear extend ;

is a schematic perspective view of a planet carrier according to the invention, comprising a body and three journals housed in a respective opening of the body, one of the journals carrying a planet pinion;

is a partial view in longitudinal section of a planet carrier according to the invention, comprising a body and a pin housed in an opening of the body, the pin being provided with a groove;

is a partial front view of the planet carrier of FIG. 2;

is a partial view in longitudinal section of a planet carrier according to the invention, comprising a body and a journal housed in an opening of the body, the journal being provided with a plurality of grooves;

is a partial front view of the planet carrier of FIG. 4;

is a partial view in longitudinal section of a planet carrier according to the invention, comprising a body and a pin housed in an opening of the body, the body being provided with a groove;

is a partial front view of the planet carrier of FIG. 6;

is a partial view in longitudinal section of a planet carrier according to the invention, comprising a body and a pin housed in an opening of the body, the body being provided with a plurality of grooves;

is a partial front view of the satellite carrier of figure 8.

Detailed description of embodiments

Figure 1A shows an electric brake 1 for a motor vehicle (not shown).

In this example, brake 1 is a disc brake with a floating caliper 2 and an actuator 3.

The actuator 3 comprises a piston 4 movable in translation along a longitudinal axis A1. This piston 4 is immobilized in rotation around this longitudinal axis A1 by any conventional means, for example by inserting fingers (not shown) of the caliper 2 into notches (not shown) made in the piston 4.

In a manner known per se, such a brake 1 is configured to block the rotation of a brake disc (not shown) by clamping the latter between two friction pads (not shown) so as to generate a braking torque. To do this, the piston 4 is moved in translation along the longitudinal axis A1, in a tightening direction going from left to right in Figure 1A. Such a translation of the piston 4 allows it to bear against one of the friction pads interposed between the piston 4 and the brake disc, applying this pad against a first face of the brake disc. By reaction, the other pad interposed between the disc and a finger 5 of the caliper 2 forming an axial stop is pressed against a second face of the disc opposite the first face. To release the rotation of the brake disc, the piston 4 is moved in translation along the longitudinal axis A1, in a direction of release going from right to left in Figure 1A.

To move the piston 4 in translation along the longitudinal axis A1, an input torque generated by an electric motor (not shown) is transmitted to the piston 4 via planetary reduction gears belonging to the actuator 3.

In this example, actuator 3 includes an input reducer 6 having a single planetary gear train. This input reducer 6 is configured to transmit the rotary motion of the motor shaft (not shown) to a drive shaft 7 of a main reducer 8 housed in the piston 4. The planetary gear train of this reducer input 6 makes it possible to drive the drive shaft 7 in rotation around the longitudinal axis A1 at a rotational speed lower than the rotational speed of the motor shaft.

The drive shaft 7 is provided with a first internal planet gear 9 which is integral with the drive shaft 7 in rotation around the longitudinal axis A1.

The 8 gearbox comprises two planetary gear sets connected in series.

The first epicyclic gear train of the reducer 8 comprises a planet carrier 10 and three planet pinions 11. The planet carrier 10 comprises a body having a central hole through which the drive shaft 7 passes as well as three eccentric openings with respect to the longitudinal axis A1. The planet carrier 10 includes three journals 12 each received in one of these off-center openings. Each of these journals 12 carries a respective satellite pinion 11 by ensuring rotational guidance of this satellite pinion 11.

Piston 4 forms an outer sun gear of this first planetary gear train. For this purpose, the piston 4 comprises an internal toothing 13 forming longitudinal grooves circumferentially spaced from each other to mesh with the planet gears 11.

The planet gears 11 meshing both with the first inner planetary gear 9 and with the outer sun gear formed by the piston 4, the rotation of the drive shaft 7 and therefore of the first inner planetary gear 9 around the longitudinal axis A1 drives each satellite pinion 11 on the one hand in rotation around its pin 12 and on the other hand along a circumferential path around the longitudinal axis A1, consequently driving the planet carrier 10 in rotation around the longitudinal axis A1.

The first planetary gear train of the main reduction gear 8 thus makes it possible to drive the planet carrier 10 in rotation around the longitudinal axis A1 at a speed of rotation lower than the speed of rotation of the drive shaft 7.

The planet carrier 10 carries a second inner planet gear 14 integral with each other in rotation around the longitudinal axis A1. This second inner planetary gear 14 drives a second planetary gear train of the reducer 8.

The second planetary gear train of reducer 8 comprises a planet carrier 15 and three planet pinions 16. The planet carrier 15 comprises a body with three openings eccentric with respect to the longitudinal axis A1. The planet carrier 15 comprises three journals 17 each received in one of these off-center openings. Each of these journals 17 carries a respective satellite pinion 16 by ensuring rotational guidance of this satellite pinion 16.

Piston 4 also forms an outer sun gear for this second planetary gear set. Specifically, the longitudinal grooves of the internal toothing 13 are configured to mesh with the planet gears 16.

The planet gears 16 meshing both with the second inner planet gear 14 and with the outer sun gear formed by the piston 4, the rotation of the planet carrier 10 and therefore of the second inner planet gear 14 around the longitudinal axis A1 drives each satellite pinion 16 on the one hand in rotation around its journal 17 and on the other hand along a circumferential trajectory around the longitudinal axis A1, consequently driving the planet carrier 15 in rotation around the longitudinal axis A1.

The second planetary gear train of the main reducer 8 thus makes it possible to drive the planet carrier 15 in rotation around the longitudinal axis A1 at a speed of rotation lower than the rotation speed of the planet carrier 10 and a fortiori of the shaft workout 7.

To transform the rotation of the planet carrier 15 into translation of the piston 4, the internal toothing 13 of the piston 4 forms an internal thread which cooperates with an external thread of the planet carrier 15. It results from the cooperation of the outer thread of the planet carrier 15 with the internal thread of the piston 4 that a displacement of the planet carrier 15 in rotation around the longitudinal axis A1 causes a displacement of the piston 4 in translation along the longitudinal axis A1, it being understood that the piston 4 is configured to slide into a housing 18 of the caliper 2.

In the example of Figure 1A, the drive shaft 7 extends into the piston 4 having one end housed in a cavity of the planet carrier 15. Such a configuration makes it possible in particular to hold the drive shaft 7 centered on the longitudinal axis A1.

Of course, in order to allow relative rotation of the drive shaft 7 with respect to the various rotating parts through which this drive shaft 7 passes, that is to say the planet carriers 10 and 15 as well as the second inner planetary gear 14, the drive shaft 7 and the respective holes of these rotating parts are adjusted to provide clearance between the drive shaft 7 and each of these parts.

The invention relates more specifically to the structure of a planet carrier of such a reducer 8 or 6, for example the planet carrier 10 of the first planetary gear train of the reducer 8.

The planet carrier 10 is shown in Figure 1B with a planet gear 11 carried by one of its three journals 12. The planet gears carried by the other two journals 12 are not shown in this figure.

Different structures of the planet carrier 10 according to the invention are shown in Figures 2 to 9.

In each of the embodiments of Figures 2 to 9, the planet carrier 10 is shown partially, with a single journal 12 and a body part 19 arbitrarily shown in annular form.

In each of the embodiments of Figures 2 to 9, the body 19 of the planet carrier 10 comprises a first face 21 and a second face 22 opposite each other along an axis A2.

The opening receiving the pin 12 shown in these figures crosses the body 19 from side to side, so that this opening leads to both the first 21 and the second face 22 of the body 19.

The trunnion 12 is in these examples a cylindrical axis extending along the axis A2 which forms an axis of rotation of the planet gear (not shown in Figures 2 to 9) carried by this trunnion 12. The trunnion 12 is fixed in rotation around the axis A2 relative to the body 19, for example thanks to an assembly with clamping of these parts.

A first end of the trunnion 12 is housed in the opening of the body 19 so that an end face of this trunnion 12, perpendicular to the axis A2, forms with the first face 21 of the body 19 a common face.

A second end of the trunnion 12 projects from the second face 22 of the body 19, so that a planet pinion can be mounted on this second end.

When the planet carrier 10 of one of Figures 2 to 9 is mounted in the gearbox 8 of Figure 1A, the axis A2 is in this example parallel to the longitudinal axis A1 of the gearbox 8.

In the embodiment of Figures 2 and 3, the journal 12 includes a groove 20 made on one face of this journal 12 which is radially external with respect to the axis A2.

The groove 20 forms a lubricant storage space making it possible to lubricate the journal 12 and a planet gear carried by this journal 12, in order to limit the wear of these parts during the rotation of the planet gear around the axis of rotation A2 .

Groove 20 in this example extends in a direction parallel to axis A2 and the full length of pin 12, the length being the dimension of pin 12 along axis A2.

Thus, the groove 20 opens onto the first face 21 of the body 19.

Referring to Figure 2, on the first end of the pin 12, that is to say the part of the pin 12 housed in the opening of the body 19, the groove 20 is delimited radially inside by the pin 12 and radially on the outside by the body 19. On the second end of the pin 12, that is to say the part of the pin 12 intended to carry a planet pinion, the groove 20 is delimited radially on the inside by the pin 12. When pin 12 carries a pinion, on the second end of pin 12, groove 20 is delimited radially inside by pin 12 and radially outside by this pinion.

The embodiment of Figures 4 and 5 differs from that of Figures 2 and 3 in that the journal 12 comprises several grooves 20, each having the same structural characteristics as the groove of the journal of Figures 2 and 3. The presence of several grooves 20 increases the amount of lubricant stored in planet carrier 10.

In this example, the grooves 20 are spaced circumferentially from each other on the radially outer face of the journal 12, with a constant pitch.

In the embodiment of Figures 6 and 7, the body 19 comprises a groove 23 made on one face delimiting the receiving opening of the journal 12, this face being radially internal with respect to the axis A2.

The groove 23 forms a lubricant storage space for lubricating the journal 12 and a planet gear carried by this journal 12, in order to limit the wear of these parts during the rotation of the planet gear around the axis of rotation A2 .

The groove 23 extends in this example in a direction parallel to the axis A2 and over the entire thickness of the body 19, that is to say from the first face 21 to the second face 22 of the body 19 Thus, the groove 23 opens on the first face 21 and on the second face 22 of the body 19.

Referring to Figure 6, the groove 23 is delimited radially on the inside by the journal 12 and radially on the outside by the body 19.

The embodiment of Figures 8 and 9 differs from that of Figures 6 and 7 in that the body 19 comprises several grooves 23, each having the same structural characteristics as the groove of the body 19 of Figures 6 and 7. The presence of multiple grooves 23 increases the amount of lubricant stored in planet carrier 10.

In this example, the grooves 23 are spaced circumferentially from each other on the radially inner face of the body 19, with a constant pitch.

In summary, in the embodiments of Figures 2-5, journal 12 includes one or more lubricant storage grooves 20 while body 19 does not include a lubricant storage groove. Conversely, in the embodiments of Figures 6 to 9, the pin 12 does not include a lubricant storage groove while the body 19 includes one or more lubricant storage grooves 23.

These embodiments are in no way limiting and can for example be combined with each other. For example, in an embodiment not shown, the planet carrier 10 includes both one or more grooves formed on the radially outer face of the pin 12 and one or more grooves formed on the radially inner face of the body 19, thus combining the embodiments previously described.

In a variant not shown, one or each of the openings of the body 19 receiving a pin 12 can be non-through, so that it does not lead to the first face 21 of the body 19.

Furthermore, the groove(s) 20 and/or 23 can be oriented in directions that are not parallel to the axis of rotation A2, for example having a helical shape.

When the planet carrier 10 comprises several grooves 20 and/or 23, these may have different dimensions with respect to each other. For example, one or more grooves 20 made on a trunnion 12 may have a radial and/or circumferential dimension less than a radial and/or circumferential dimension of one or more grooves 23 made in a receiving opening of this trunnion 12. For another example, two grooves 20 of the same pin 12 can form lubricant storage spaces having a different volume relative to each other.

What has just been described with respect to the part of the planet carrier 10 shown in FIGS. 2 to 9 can be applied in the same way to the parts of the planet carrier 10 not shown in these figures, in order to form storage spaces of lubricant suitable for lubricating all of the satellite pinions 11 and the corresponding journals 12 of this planet carrier 10.

More generally, the invention applies to any planetary carrier of planetary reduction gear, for example to the planetary carrier 15 of the second planetary gear train of the main reduction gear 8 of FIG. 1A and/or to the planetary carrier of the input reduction gear 6 of Figure 1A. In particular, the invention applies to a planet carrier of a reduction gear that may belong to an actuator different from that described above with reference to FIG. 1A, such as a fixed-caliper brake actuator.

Nomenclature

A1 longitudinal axis

A2 planet gear rotation axis

1 electric brake

2 stirrup

3 actuator

4 piston / outer planetary

5 caliper finger / axial stop

6 planetary input reducer

7 drive shaft

8 main planetary gearbox

9 first inner planetary gear of the main reducer

10 planet carrier of the first planetary gear set of the main gearbox

11 satellite pinions of the first epicyclic gear train of the main reducer

12 planet carrier trunnions 10

13 internal gearing of the outer sun gear

14 second main reducer inner planetary gear

15 planet carrier of the second planetary gear of the main gearbox

16 planet gears of the second epicyclic gear train of the main reducer

17 planet carrier trunnions 15

18 caliper housing

19 carrier body 10

20 trunnion groove(s) 12

21 first face of planet carrier body 10

22 second side of planet carrier body 10

23 planet carrier slot(s) 10

Claims (10)

Planet carrier (10) for an epicyclic reduction gear (6, 8), comprising a body (19) and at least one trunnion (12) received in an opening of the body (19), the at least one trunnion (12) being arranged to carry a planet pinion (11) and ensure rotational guidance of this planet pinion (11), this planet carrier (10) being characterized in that the at least one journal (12) and/or the body (19 ) of the planet carrier (10) comprise at least one groove (20, 23) forming a lubricant storage space delimited radially on the inside by the at least one journal (12). A planet carrier (10) according to claim 1, wherein the at least one groove (20, 23) extends along a direction parallel to an axis (A2) of rotation of the planet gear (11). Planet carrier (10) according to Claim 1 or 2, in which the at least one groove (20, 23) opens on a first face (21) of the body (19) and on a second face (22) of the body ( 19) so as to form a lubricant storage space passing axially through the body (19) of the planet carrier (10). A planet carrier (10) according to any one of claims 1 to 3, wherein the at least one journal (12) includes a plurality of circumferentially spaced apart grooves (20) on a radially outer face of that journal (12 ). A planet carrier (10) according to any one of claims 1 to 4, wherein the body (19) of the planet carrier (10) includes a plurality of circumferentially spaced apart grooves (23) on a radially inner face thereof. body (19), this radially inner face delimiting the receiving opening of the at least one journal (12). A planetary gear comprising a planet carrier (10) according to any one of claims 1 to 5. Planetary reduction gear (6, 8) comprising a planetary gear train according to claim 6. Actuator (3) of an electric brake (1), comprising an epicyclic reduction gear (6, 8) according to claim 7. Electric brake (1), comprising an actuator (3) according to claim 8. Motor vehicle, comprising an electric brake (1) according to claim 9.