FR3038676B1 - "ELECTROMECHANICAL PARKING BRAKE ACTUATOR, ELECTRIC MOTOR FOR SUCH ACTUATOR, AND ASSEMBLY METHOD" - Google Patents

Abstract

The invention proposes an electromechanical actuator of which an electric motor, for actuating a parking brake of a motor vehicle, comprises a rotating shaft of which a rear axial end section (82) extends axially rearwards at a transverse rear face of the engine, in which the section (82) has a first axial front portion (P1) which carries an output pinion (86) arranged opposite the rear transverse face (84) and- second free end rear portion (P2), characterized in that the second portion (P2) of the rear axial end section (82) is a breakable portion. When not separated, the second part P2 carries a magnetic component 96.

Description

"Electromechanical parking brake actuator, electric motor for such an actuator, and method of assembly"

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an electromechanical actuator for actuating a parking brake of a motor vehicle, which can also act as an emergency or emergency brake, integrated with a hydraulically actuated disk brake. The invention also relates to an electric motor of such an electromechanical actuator. The invention also relates to a method of assembling such an electromechanical actuator.

STATE OF THE ART

Document US-B2-7,021,415 or WO-A1-2009 / 016660 discloses the structure of a hydraulically-controlled disk brake having an electromechanical parking brake.

In known manner, the brake comprises a yoke adapted to support and guide sliding two opposed friction pads adapted to cooperate with a rotating disc.

Independently of the main hydraulic actuation of the disc brake, it comprises electromechanical means for its actuation and operation as a parking brake or emergency brake. For this purpose, the brake comprises a torque or screw-nut group which is arranged in the hydraulically actuated brake piston and, on the other hand, an electric motor-gear unit called the electromechanical actuator for rotating drive, in both directions, the screw of the group screw-nut. The actuation of the parking brake by means of an electric motor belonging to this actuator makes it possible to apply to the screw of the screw-nut group a tightening torque which is converted by the screw-nut unit into an applied axial thrust of clamping. to the piston.

To produce such a torque, the actuator may comprise a reduction mechanism, which is rotated by the output shaft of the electric motor, for rotating an output member of the electromechanical actuator. The electromechanical actuator comprises an actuator housing which houses in particular the electric motor.

An example of such a design is illustrated in WO-A1-2014 / 095364. The electromechanical actuator 17, for actuating a parking brake of a motor vehicle, comprises an actuator housing 18 having a transverse rear end 34 and in which is housed, at least in part, an electric motor 39, the engine comprising: - a rear cap 80; and a rotating shaft 81 having a rear axial end portion 82 extending axially rearwardly beyond a rear transverse face 84 of the cap 80, in which the rear axial end section 82 of the rotating shaft comprises a portion which carries an output pinion 86 arranged axially facing the rear transverse face 84 of the cap 80, and wherein a free end face of the rear axial end section of the rotating shaft extends facing an inner face portion of the rear bottom of the housing.

As mentioned in this document, the electromechanical actuator may comprise means for detecting the rotation of the rotating shaft of the electric motor which comprise a sensor which is arranged facing the output gear and which detects the movement of the teeth of the pinion.

According to an alternative design of improved means for detecting the rotation of the rotating shaft of the electric motor, these comprise a component - such as for example a magnet or any other magnetic component such as a ring provided with more magnets - which is carried and rotated by another portion of the rear axial end section of the rotating shaft.

In this case, the design of the rear axial end section of the rotating shaft is such that it comprises: a first front portion which carries the output pinion arranged axially opposite the rear transverse face of the cap; and a second free end rear portion adapted to carry the component belonging to the rotating rotation detection means.

Thus, depending on the presence or absence of means for detecting the rotation of the rotating shaft, or depending on the design of these detection means, the rear axial end section of the rotating shaft has an axial length. more or less, that is to say with only the first part which carries the output gear, or with the second part which carries said component.

In view of the economic imperatives related to industrialization and mass production, it is not satisfactory to have two electric motor references, respectively with a "short" tree and a "long" tree, or with supply the assembly and assembly lines with one or the other of the two references. The object of the invention is to propose a design that requires only a single motor reference.

SUMMARY OF THE INVENTION

For this purpose, the invention proposes an electromechanical actuator of the type mentioned above, characterized in that the second part of the rear axial end section is a breakable part, which can be separated from the first part.

According to other characteristics of the actuator: the rear axial end section of the rotary shaft comprises at least one reduced-resistance section breaking initiation zone which is arranged axially between the first part and the second part; the rupture initiation zone consists of a radial groove formed in the rear axial end section of the rotating shaft; the rupture initiation zone consists of at least one notch intended to reduce the resistant section formed in the wall of the rear axial end section of the rotating shaft; the second portion of the rear axial end portion of the rotating shaft carries a component belonging to means for detecting the rotation of the rotating shaft; - This component is a magnetic element rotatably connected to the rotating shaft; - The free end of the rotating shaft has a trace of the breaking of the breakable part. the bottom of the housing is an attached cover which closes an open rear face of the housing; - The motor is mounted in the housing by introducing it, axially from rear to front, by said open rear face, then closing the housing by crimping and / or bonding of its rear cover. The invention also proposes an electric motor for actuating a parking brake of a motor vehicle, which comprises: a rear cap; and a rotating shaft having a rear axial end portion extending axially rearwardly beyond a rear transverse face of the cap, wherein the rear axial end section of the rotating shaft comprises: - A first portion which carries an output pinion arranged axially facing the rear transverse face of the cap; and a second free end portion, characterized in that the second portion of the rear axial end section is a breakable part.

According to other characteristics of the electric motor: the rear axial end section of the rotating shaft comprises a breaking initiation zone, with a reduced resistance section, which is arranged axially between the first part and the second part; the rupture initiation zone consists of a radial groove formed in the rear axial end section of the rotating shaft; the rupture initiation zone consists of at least one notch intended to reduce the resistant section formed in the wall of the rear axial end section of the rotating shaft; the second portion of the rear axial end portion of the rotating shaft carries a component belonging to means for detecting the rotation of the rotating shaft; - This component is a magnetic element rotatably connected to the rotating shaft. The invention also proposes a method of assembling an electromechanical actuator, for actuating a parking brake of a motor vehicle, which comprises an actuator housing comprising a transverse rear base and in which is housed, at least in part, an electric motor comprising: - a rear cap; and a rotating shaft having a rear axial end portion extending axially rearwardly beyond a rear transverse face of the cap, wherein the rear axial end section of the rotating shaft comprises: - A first portion which carries an output pinion arranged axially facing the rear transverse face of the cap; and a second free end portion, an electromechanical actuator in which a free end face of the rear axial end portion of the rotating shaft extends facing an inner face portion of said rear bottom of the housing, and wherein the second portion of the rear axial end portion is a breakable portion, characterized in that the method comprises a step of axially introducing the electric motor into the housing through an open transverse face of the housing.

According to other characteristics of the process: the step of axial introduction of the electric motor into the housing is preceded by a step of separating the second breakable portion from the first portion of the rear axial end section of the rotating shaft ; the step of axially introducing the electric motor into the housing is preceded by a step of mounting a component, belonging to means for detecting the rotation of the rotating shaft, on the second portion of the end section axial axis of the rotating shaft.

BRIEF DESCRIPTION OF THE FIGURES Other characteristics and advantages of the invention will appear on reading the following detailed description of an embodiment of the invention for which reference will be made to the appended drawings in which: FIG. 1 is a general perspective view of a parking brake disc brake having an electromechanical actuator; - Figure 2 is a view similar to that of Figure 1 which shows the main components of the brake of Figure 1 exploded; FIG. 3A is a large scale perspective view of the housing of the electromechanical actuator shown in FIGS. 1 and 2; - Figure 3B is an end axial view of the housing of Figure 3A which is shown without its closure cap and without its internal components; FIG. 4 is a perspective view of the electric motor of the electromechanical actuator of the preceding figures whose shaft is of the "short" type; - Figure 5 is a sectional view, by an axial plane of the assembly shown in Figure 4; FIG. 6 is a diagrammatic representation of an electric actuator motor whose shaft is of the "long" type, the rear axial end portion of which carries an output gear and a component belonging to a means of detecting the rotation of the tree; FIG. 7 is a view similar to that of the upper part of FIG. 6, which illustrates an exemplary embodiment of a rear axial end section of a shaft according to the invention in two parts, one of which is divisible and which carries an output gear and an additional component; FIG. 8 is a view similar to that of FIG. 7 which illustrates the rear axial end section of the shaft according to the invention illustrated in FIG. 7 which carries only the output gear and, and the second part of which breakable is being separated from the first part; and FIG. 9 is a schematic view of the second part after the separation of the first part.

DETAILED DESCRIPTION OF THE FIGURES

In the following description, identical, similar or similar elements and components will be designated by the same references.

FIGS. 1 and 2 show a disc brake caliper 10 which is shown here without its brake pads, nor without the associated means of guiding in axial sliding and return of these pads.

The disc brake essentially consists of a stirrup 12 having a rear casing 14 in which a hydraulic brake piston 16 is axially slidable from behind to forward, that is to say from the left to the rear. right considering Figure 1 along an axis A1.

The disc brake 10 comprises, at the rear, a geared motor group or electromechanical actuator 17 which has been shown a housing 18 which, as will be explained in detail later, houses an electric motor and a gear reduction gear mechanism with epicyclic gear.

The housing 18 is attached and fixed on a rear transverse face of the stirrup 12 against which the housing 18 is axially supported by its open front end transverse face 20, the attachment here being provided by screws 22.

The rear housing 14 of the stirrup 12 defines a hydraulic axial cavity 24 in which the piston 16 is mounted axially sliding tightly in both directions along the axis A1.

The brake piston 16 is a generally cylindrical piece open axially rearward and is adapted to cooperate, by its outer transverse front face 26, with an associated disk brake pad (not shown). The supply of hydraulic fluid under pressure of the chamber 24 causes a hydraulic actuation of the brake by axial thrust forward of the piston 16 relative to the rear housing 14 of the stirrup 1 2.

For the mechanical actuation of the piston 16 in said parking or "parking" operation, or in emergency brake operation, the piston 16 and the chamber 24 house a screw-nut unit comprising a drive rear screw 28 and a front nut 30 of axial thrust.

For its drive in rotation in both directions, the screw 28 comprises a rear section 32 which, in the assembled position, is accessible from the rear transverse face of the stirrup 12 so as to constitute a drive head in rotation of the screw 28 which is rotated in both directions by a movement output member of the electromechanical actuator 17.

As can be seen in Figures 3A and 3B, the housing 18 is a molded plastic part which internally delimits two main housing, each in the general shape of cylindrical pot, parallel axes A1 and A2.

The rear face of the housing 18 is closed by a bottom which is here a rear cover 34 attached and welded or glued to an open rear axial face 35 of the housing 18.

Before the cover 34 is put in place, the two recesses 36 and 38 are open axially towards the rear.

The first housing 36, on the left considering FIGS. 3A and 3B, is intended to house an epicyclic gear train (not shown), of which an internally toothed outer solar crown 40 is here made integrally by molding with the housing 18.

The first housing 36 is axially closed towards the front by an annular bottom wall 42.

The annular bottom wall 42 has a central hole 44 for the passage of a movement output member of the epicyclic gear train (not shown).

The second housing 38, on the right, while considering FIG. 3B, is also open axially towards the rear and is designed to house an electric drive motor 39 (not shown in FIG. 3B) including an output gear 86 is connected, by not shown gear means, to a sun gear of the epicyclic gear train housed in the first housing 36.

The second housing 38, which houses the electric motor, is closed axially towards the front by a bottom wall 46.

As can be seen in FIGS. 3A and 3B, the housing 18 of the actuator comprises, adjacent to the housing 38 and to the outside, a projecting portion 48 which constitutes a housing for an external electrical connector for the electrical connection of the electromechanical actuator with external circuits (not shown) of the motor vehicle for supplying electrical energy to the motor and for controlling its operation. For this purpose, the portion 48 is open axially towards the rear and has two pairs of passages 50 and 51 adapted to receive conductive terminals electrical connection (not shown in Figure 3B).

In the same way, adjacent to the housing 38 which is able to receive the electric motor, the housing 18 comprises an inner electrical connector 52.

The electric motor 39, the electromagnetic components of which are not shown in FIGS. 4 and 5, essentially consists of a housing comprising a cylindrical lateral wall 74 closed at its forward axial end by a transverse wall 76 which delimits a housing in which a front end section 78 of the output shaft 81 of the motor rotor 39 is rotatably mounted about the axis A2. The rear end of the cylindrical wall 74 of the housing 18 is closed axially by a cylindrical rear cap 80 which is a molded piece of plastic material which delimits a central housing in which a section is rotatably mounted about the axis A2. rear end 82 of the shaft 80 which protrudes axially beyond a rear transverse face 84 of the cap 80 and which here carries an output pinion 86 rotatably connected to the output motor shaft 80 of the motor 39.

The cap 80 of the motor housing 39 consists essentially of a transverse wall, radially oriented, 88 and a cylindrical side skirt 90.

The transverse wall 88 comprises a central hole 89 for the axial passage of the section 82 of the shaft 80.

The cap 80 comprises a support 92 of connections and components in the general form of plate and axial orientation which is made integrally by molding with the cap 80.

In FIGS. 4 and 5, the design of the rear axial end section 82 is in accordance with the state of the art in that its length allows only the mounting and the rotational drive of the output pinion 86. therefore, within the meaning of the invention, of a section comprising only a first part P1. The section 82 is delimited axially towards the rear by a free end transverse face 94.

It is therefore a "short" shaft that does not allow the mounting of an additional component on the section 82, axially adjacent to the output gear 86.

FIG. 6 is a schematic representation of the electric motor 39 whose shaft is of "long" type, that is to say that the rear axial end section 82 carries the output gear 86 and an additional component 96 belonging to detection means.

The component is for example a magnet, or a similar unipolar or multipolar magnetic member, produced in the form of an annular ring which, as the output pinion 86 is pierced at its center and is carried by the section 82 to which, like the output gear 86, it is linked in rotation. For this purpose, the section 82 comprises a second portion P2 of free end which axially extends the first portion P1.

According to this known design of the state of the art, the rear axial end section 82 is a long section of constant section, corresponding to a "long" shaft electric motor. FIG. 7 shows an exemplary embodiment of an output shaft whose rear axial end section 82 is of the long type as in FIG. 6 and which is also equipped with the pinion 86 and the magnetic component 96 .

According to the invention, the first part P1 and second part P2 are separated by a breaking initiation zone P3 so as to make the second free end portion P2 breakable, ie separable from the first part P1 . By way of nonlimiting example, the zone P3 of initiation of rupture is here carried out with the aid of a radial groove 98.

When, as illustrated in FIG. 7, the section 82 is used in a long "version" carrying the pinion 86 and the magnetic component 96, the design and dimensioning of the different parts and zones of the section 82 are such that, in operation the section behaves like the "full" section of FIG. 6. By way of example, the external diameter of the section 82 is equal to 3 millimeters and the radial depth of the groove is between 1 and 2 millimeters, while the length of each of the two parts P1 and P2 is of the order of -6 millimeters.

As can be seen in FIG. 8, when it is desired to use the same electric motor with a "short" shaft, it suffices to definitively separate the free end portion P2 by causing the break in the zone P3 of start of rupture, and to throw the P2 part after separation which is illustrated in Figure 9.

The pinion 86 can be mounted on the part P1 before or after the separation of the breakable part P2. The invention is not limited to the embodiment which has just been described. The rupture initiation zone may for example be made with the aid of one or more notches formed in the outer lateral wall of the section 82.

We will now describe the mounting of the electric motor 39 in its housing 38 of the box 18.

The process begins with a step of, if desired, mounting a magnetic component 96 on the second portion P2 or by a step of separating the second breakable portion P2.

The motor 39 is then introduced axially, from rear to front, in the housing 38 by its front part by bringing its transverse front wall 76 in axial support against the inner portion vis-à-vis the bottom wall 46 of the housing 38.

In the design shown in the figures, an annular elastically deformable ring 130, made for example of elastomeric material, is interposed between the transverse wall 76 and the wall 46.

The function of the ring gear 130 is to provide damping of the vibrations, and in particular of the noise, and also acts as an elastic wedge mounted axially compressed, to compensate for the clearances for the axial mounting of the motor 39 in its housing 38 of the housing 18, also participating in a precise axial positioning of the motor 39, and therefore of its cap 80, relative to the housing 18.

Claims (18)

An electromechanical actuator (17) for actuating a motor vehicle parking brake, which comprises an actuator housing (18) having a transverse rear (34) transverse and in which is housed, at least in part an electric motor (39) comprising: - a rear cap (80); and - a rotating shaft (81) having a rear axial end section (82) extending axially rearwardly beyond a rear transverse face (84) of the cap (80), wherein the section rear axial end (82) of the rotating shaft comprises; - a first portion (PI) which carries an output gear (86) arranged axially opposite the rear transverse face (84) of the cap (80); and a second free end portion (P2), in which a free end face of the rear axial end portion (82) of the rotating shaft extends opposite an inner face portion of said bottom rear of the housing, characterized in that the second portion (P2) of the rear axial end section (82) is a breakable portion. 2. Electromechanical actuator according to claim 1, characterized in that the rear axial end section (82) of the rotating shaft comprises at least one reduced-resistance section breaking region () which is arranged axially between the first part (PI) and the second part (P2). 3. electromechanical actuator according to claim 2, characterized in that the rupture initiation zone is constituted by a radial groove formed in the rear axial end section (82) of the rotating shaft. 4. Electromechanical actuator according to claim 2, characterized in that the rupture initiation zone is formed by at least one notch, intended to reduce the resistant section, formed in the wall of the rear axial end section (82) of the rotating shaft. 5. electromechanical actuator according to any one of claims 1 to 4, characterized in that the second portion (P2) of the rear axial end section (82) of the rotating shaft carries a component belonging to the detection means of the rotation of the rotating shaft (81). 6. Electromechanical actuator according to claim 5, characterized in that said component is a magnetic element rotatably connected to the rotating shaft (81). 7. Electromechanical actuator according to any one of claims 1 to 4, characterized in that the free end of the rotating shaft comprises a trace of the breaking of the breakable part. 8. Electromechanical actuator according to any one of claims 1 to 4, characterized in that the bottom of the housing (18) is an attached cover which closes an open rear face (35) of the housing (18). 9. Electromagnetic actuator according to claim 7, characterized in that the motor (39) is mounted in the housing (18) by introducing it, axially from rear to front, by said open rear face, then closing the housing ( 18) by crimping and / or gluing its rear cover (34). Electric motor (39) for actuating a parking brake of a motor vehicle, comprising: - a rear cap (80); and - a rotating shaft (81) having a rear axial end section (82) extending axially rearwardly beyond a rear transverse face (84) of the cap (80), wherein the section rear axial end (82) of the rotating shaft comprises: - a first portion (PI) carrying an output gear (86) arranged axially facing the rear transverse face (84) of the cap (80); and a second portion (P2) of free end, characterized in that the second portion (P2) of the rear axial end section (82) is a breakable part. 11. Electric motor according to claim 9, characterized in that the rear axial end section (82) of the rotating shaft comprises a region (P3) of rupture initiation, reduced resistance section, which is arranged axially between the first part (PI) and the second part (P2). 12. Electric motor according to claim 10, characterized in that the region (P3) of initiation of rupture is constituted by a radial groove (98) formed in the rear axial end section (82) of the rotating shaft. Electric motor according to claim 10, characterized in that the zone (P3) of rupture initiation is formed by at least one notch, intended to reduce the resistant section, formed in the wall of the rear axial end section ( 82) of the rotating shaft. 14. Electric motor according to any one of claims 9 to 12, characterized in that the second portion (P2) of the rear axial end section (82) of the rotating shaft carries a component (96) belonging to the means detecting the rotation of the rotating shaft (81). 15. Motor according to claim 13, characterized in that said component (96) is a magnetic element rotatably connected to the rotating shaft (81). 16. A method of assembling an electromechanical actuator, for actuating a parking brake of a motor vehicle, which comprises an actuator housing (18) having a transverse rear end (34) and in which is housed, at least in part, an electric motor (39) comprising: - a rear cap (80); and - a rotating shaft (81) having a rear axial end section (82) extending axially rearwardly beyond a rear transverse face (84) of the cap (80), wherein the section rear axial end (82) of the rotating shaft comprises: - a first portion (PI) carrying an output gear (86) arranged axially facing the rear transverse face (84) of the cap (80); and a second free-end portion (P2), an electromechanical actuator in which a free end face of the rear axial end section (82) of the rotating shaft extends facing a portion of internal face said rear bottom of the housing, and wherein the second portion (P2) of the rear axial end portion (82) is a breakable portion, characterized in that the method comprises a step of axial introduction of the electric motor (39) in the housing (18) through an open transverse face of the housing (18). 17. An assembly method according to claim 15, characterized in that said step of axial introduction of the electric motor (39) into the housing (18) is preceded by a step of separating the second breakable portion (P2) from the first portion (PI) of the rear axial end section (82) of the rotating shaft. 18. An assembly method according to claim 15, characterized in that said step of axial introduction of the electric motor (39) in the housing (18) is preceded by a step of mounting a component (96) belonging to means for detecting the rotation of the rotating shaft (81) on the second portion (P2) of the rear axial end section (82) of the rotating shaft.